Distillation Column Report PDF

CE 3003 Advanced Process Design – Individual Project
EXECUTIVE SUMMARY:
The main objective of this project was to carry out a design on the Propane distillation column for a
process that produces 1,3 Butadiene. The raw materials used are Butane, Oxygen and Water and
the process capacity is 100 000 tonnes per annum nominal. In the previous work it was stated that
the plant is located in China. The main location of the plant is in the capital city of the Gansu
Provence, Lanzhou. This was decided as the location over other provinces due to the excellent
transport links and the availability of raw materials and cheap labour. The close proximity to
suppliers, customers and skilled labour all make Lanzhou the ideal location for the plant to be
located.
The design of the distillation column consists of the packed type. The distillation is a multi-
component distillation involving separation of Propane from the other components at very high
pressure. The number of theoretical stages chosen was 16 stages based on a reflux ratio of 0.608.
The column diameter calculated was 0.61 at maximum pressure gradient possible for distillation
columns and 0.66m for minimum pressure gradient, which was then scaled up to 0.65m. This was a
reasonable decision as it may be helpful when the plant capacity increases. The column has a height
of 8m. Feed location for the arrangement of packing is at stage 3 from the top of the column. Pall
rings constructed out of stainless steel with a size of 25mm is used for packing. The vessel thickness
of the column is around 5mm, constructed out of stainless steel also to avoid corrosion.
A preliminary design on the condenser for this distillation column was also carried out. The type of
condenser is a fixed plate with a 1 shell and 1 tube pass. The tubes are stainless steel, 119 in
number, 2.44m in length, and with a square pitch arrangement. The overall heat transfer coefficient
was also calculated as 486.026W/m2C. The pressure drop on the tube side was 7.306 N/m2 (almost
negligible) as only one tube pass is used with a very short length. The pressure drop on the shell
side was 46.64 N/m2
The next section details on the Piping and Instrumentation over the column. The control system
used for better efficiency of the units is also featured in the same P and ID.. The control mainly used
for this, is the cascade control for the temperature and product composition, also in the varying of
the bottom product flow rate to control the level at the bottom of the column. The variables
Richie Gandhi Page 1

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controlled are the top and bottom temperatures including product composition and the reflux drum
and also the level at the base of the column.
There were two group tasks performed in this term along with the individual design. The first group
task performed was the HAZOP on the feed line of the propane distillation column. The aim of the
HAZOP was to evaluate the selected process line and identify the possible deviations which could
result into a hazard; the possible causes to the deviations, consequences and actions needed to
avoid the consequences were also discussed. An improvised P and ID was then produced after
Hazop was done. The Hazop was done with Dr. Titiloye as the Study Leader. The deviations
discussed include no flow, less flow, less temperature due to weather conditions, more
temperature likely to occur as a result of external fire and extra phase in an event of poor
separation, presence of heat transfer fluids, presence of off gases, corrosion inside the pipe catalyst
pellets in the pipe and excess residue due which leads ultimately to contamination.
The second group work is the economic appraisal, which was useful in concluding that if this project
were to be operational; the payback period would be two years which would leave 13 years of net
profit. So, from a financial aspect, the project was found to be very viable and attractive.
Both the group works are attached in the Appendix VI and VII

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Contents
1.0 Project Brief: ..................................................................................................................................... 5
1.1 Introduction to the product: ........................................................................................................ 5
1.2 Production: ................................................................................................................................... 6
1.3 Location [4] .................................................................................................................................... 7
2.0 Project Plan and Objectives:........................................................................................................... 10
2.1Technical Objectives:................................................................................................................... 10
2.2 Personal Objectives: ................................................................................................................... 12
2.3 Schedule ..................................................................................................................................... 13
2.3.1Project Schedule ................................................................................................................... 13
3 The Revised Process: ......................................................................................................................... 15
4 The Chemical Design: ........................................................................................................................ 17
4.1 Calculations: ............................................................................................................................... 20
4.1.1 Reflux ratio and the number of Theoretical Stages ............................................................ 21
4.1.2 Determination of the Diameter of the Column: ................................................................. 28
4.1.3Feed Location: ...................................................................................................................... 31
4.2 Choice of Plates and Packing: ..................................................................................................... 33
4.2.1 Types of Packing: ................................................................................................................. 34
4.3 Column Internals [21][22]: .............................................................................................................. 43
5.0 CONDENSER:................................................................................................................................... 48
5.1 Energy Balance Over the condenser: ......................................................................................... 49
5.2 Shell Side Coefficient: ................................................................................................................. 54
5.3 Tube Side Coefficient: ................................................................................................................ 55
5.4 Overall Heat transfer Coefficient U; ........................................................................................... 56
5.5 Shell side Pressure Drop: ............................................................................................................ 59
5.6Tube Side Pressure Drop: ............................................................................................................ 63
6.0 REBOILER: ....................................................................................................................................... 65
6.1 Heat Duty over the Reboiler:...................................................................................................... 66
6.2 Choice of type of reboiler used with the Propane Distillation: [28] ............................................. 67
7.0 Overall Energy Balance over the Distillation Column: ................................................................... 68
8.0 Piping and Instrumentation Diagram ............................................................................................. 69

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8.1 Control Loop ............................................................................................................................... 72

8.2 Control Systems over the Distillation Column: .......................................................................... 73
9.0 Hazard and Operability Studies HAZOP.......................................................................................... 76
10.0 Conclusion: ................................................................................................................................... 77
11.0 References: ................................................................................................................................... 78
12.0 APPENDIX: ....................................................................................... Error! Bookmark not defined.
Appendix I ............................................................................................ Error! Bookmark not defined.
Appendix II ........................................................................................... Error! Bookmark not defined.
Appendix III .......................................................................................... Error! Bookmark not defined.
Appendix IV ......................................................................................... Error! Bookmark not defined.
Appendix V .......................................................................................... Error! Bookmark not defined.
Appendix VI ......................................................................................... Error! Bookmark not defined.
Appendix VII ........................................................................................ Error! Bookmark not defined.

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1.0 Project Brief:
1.1 Introduction to the product:

Butadiene is a simple conjugated diene. It is an
important industrial chemical used as a monomer in
the production of synthetic rubber. Butadiene at most
of the times refers to 1,3-butadiene. 1,2-butadiene,
which is a cumulated diene is an isomer which is
difficult to prepare and has no industrial significance.[1]
1, 3 Butadiene (CH2=CH-CH=CH2), is a colourless gas

with mild aromatic odour. Butadiene is soluble in
alcohol and ether, insoluble in water and polymerizes readily, particularly if oxygen is present. It is
non-corrosive and has a molecular formula of 54.09. Its boiling point is -4.4C and its vapour pressure
is 1,790 mm Hg (239kPa) at 20◦C. It is easily liquefied, with a density of 0.6211 g/ml at 20C. It is
soluble with ethanol, diethyl ester, and organic solvents and very slightly soluble in water. 1, 3
Butadiene has a flash point of -76C and can slowly be dimerised and may form peroxides upon
exposure to air. Because 1, 3 Butadiene is a highly volatile gas, it is expected to partition in the
atmosphere and then undergo rapid destruction by photo-initiated reactions. [1]
A table of properties can be seen in Appendix I section (a)
In 1863, a French chemist isolated a previously unknown hydrocarbon from the pyrolysis of amyl
alcohol.[1] This hydrocarbon was identified as butadiene in 1886, after Henry Edward
Armstrong isolated it from amongst the pyrolysis products of petroleum.[1] In 1910,
the Russian chemist Sergei Lebedev polymerized butadiene, and obtained a material with rubber-
like properties. This polymer discovered was too soft to replace the natural rubber in many of its
uses, especially automobile tires.
The butadiene industry originated during the World War II. Many of the belligerent nations realized
that in the event of war, they could be cut off from rubber plantations controlled by the British
Empire, and sought to remove their dependence on natural rubber.

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In 1929,Eduard Tschunker and Walter Bock, working for IG Farben in Germany, made a copolymer
of styrene and butadiene that could be used in automobile tires. Worldwide production quickly
ensued, with butadiene being produced from grain alcohol in the Soviet Union and the United
States and from coal-derived acetylene in Germany.[1]
Butadiene is the raw material used [2] in the making of various synthetic rubbers and polymer resins
as well as a few chemical intermediates.
It is mainly used to make styrene butadiene rubber (SBR) which is used to make automobile tyres. It
is also used in adhesives, sealants, coatings and rubber article such as shoe soles. SBR is has a high
molecular weight, as it has excellent resistance to abrasion, it is widely used in the automobile tyre
industry.
Various other uses of butadiene are detailed in the table attached in Appendix I Section (b).
Figure 2: Chart Showing Various Uses of different forms of 1,3

Butadienehttp://www.sriconsulting.com/WP/Public/Reports/pie_charts/Butadiene.gif
1.2 Production:
Butadiene is produced commercially by three main processes:[3]
 Steam Cracking of Paraffinic Hydrocarbons: In this process, butadiene is a co-product in the
manufacture of ethylene (the ethylene co-product process).
 Catalytic Dehydrogenation of n-Butane and n-Butene (the Houdry process).
 Oxidative Dehydrogenation of n-Butene (the Oxo-D or O-X-D process).

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Each of these processes produces a stream commonly referred to as crude butadiene that is rich in
1,3-butadiene.
In the United States, western Europe, and Japan, butadiene is produced as a by-product of
the steam cracking process which is used to produce ethylene and other olefins. The quantity of
butadiene produced depends on the hydrocarbons used as feed. Light feeds, such as ethane, give
primarily ethylene when cracked, but heavier hydrocarbons favour the formation of heavier olefins,
butadiene, and aromatic hydrocarbons.
Butadiene can also be produced by the catalytic dehydrogenation of normal butane. The first
commercial plant, producing 65,000 tons per year of butadiene, began operations in 1957
in Houston, Texas.
In the previous project it was decided that Oxydehydrogenation Process would be employed to
produce butadiene for the plant to be built in China, which uses Butene as the main raw material.
Due to the easy availability of Butane from the nearby industries, it was decided to integrate the
process, where butane was first decided to be catalytically dehydrogenated to Butnene and the O-
X-O D Process follows after that. The specification was not clearly illustrated in the project earlier,
and hence it’s now detailed further in this project.
1.3 Location [4]

Since 2002, the Global Butadiene industry has maintained relatively fast growth especially in Asia
due to its variety of uses. The global annual butadiene output increased from 8.08 million tons in
2002 to 10.15 million tons in 2007, with an average annual growth rate of 4.68%.
China is one of the fastest developing Asian countries in the world. Along with the rapid
development of china butadiene industry, the national output of butadiene increased from 725,000
tons in 2001 to 1.36 million tons in 2007, with an average annual growth of 9.4%. Even after
increase in production, China has to import huge quantities of butadiene from different countries.
Korea is the biggest supplier of butadiene to china.

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Figure 3 : graph to show Production Capacity and Output of Butadiene in China, 2001-2008 (Unit:
10,000 tons)http://www.researchinchina.com/UpLoads/Article/2008112601.gif
It was decided that the best place locate the butadiene plant in China which can satisfy the
demands of its market in near future is in Lanzhou, the capital of the Gansu province which is in
north western china.
Figure 4: Map of Gansu Province in China

http://janetong.com/image_gallery/data/agansubest.jpg i
While deciding the plant location several factors were taken into consideration:
Productivity - Since 1949 Lanzhou has been transformed from the capital of a poverty-stricken
province into the centre of a major industrial area. The GDP per capita of Lanzhou was 25,566 Yuan
(RMB) (US$3,681) in 2008, ranked no. 134 among 659 Chinese cities.

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River - Lanzhou is situated at the upper course of the Yellow River. The river can provide water to
the plant as the process requires large quantities of water for scrubbing and cooling. Also the river
provides hydropower to the industries and cities in Gansu. A large multipurpose dam has been built
in the Liujia Gorge on the Yellow River above Lanzhou. The river also helps in transportation.
Natural Resources - Lanzhou has many natural resources which include coal, gold, silver, nickel,
manganese, clay and dolomite. The Coal is obtained from Qinghai which provides thermal power.
The catalyst for our process is nickel which will be cheaper to buy and will be available in large
quantities.
Cheap Labour - Due to the presence of the Yellow river the site is a residential area for more than
3.3 million people. Cheap labour is available for the plant. There are many top ranked universities in
this province which means qualified staff will be available at the site.
Industrial area - Gansu has one of the largest oil refineries in the country and Lanzhou itself is the
centre of the province's petrochemical industry. The main industries include rubber, petrochemical,
oil refinery and machinery industry. Butane which is the raw material for our process is readily
available and also Butadiene (product) can be sold to the neighbouring industries. Also, the
machinery parts will be available from the neighbouring industries which will reduce the cost of
transportation and energy and time.
Transportation - Lanzhou is very well interconnected to various cities and provinces through
highways, railways and airlines. There are 3 major national highways namely China National
Highways 212,213 and312, connecting Lanzhou to different provinces of the country.
Transportation is cheap and easy. The Lanzhou Sustainable Urban Transport Project in China aims at
improving the transport infrastructure and urban road networks. The total Asian Development Bank
contribution is estimated at US$150 million. This project is under planning and is expected to get its
approval by 11th Dec; 2010.This will greatly enhance the transportation of our product to different
provinces when our plant is ready for production.

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2.0 Project Plan and Objectives:

The Second part of this project aims at carrying out a design study on a selected process section for
the production of 100 000 tonnes per year of 1, 3 Butadiene from Butane for a plant to be built in
China.
Project Supervisor: Dr. James Titiloye
Project Author: Richie Gandhi
The process development project aims to give third year Chemical Engineering students a chance to
experience what working on a project in an industry might be like. Working in groups, they must
cover all the major areas involved in designing a process. The main process unit which has been
discussed in this project is a Distillation Column which separates Propane from 1,3 butadiene.
Within this task other objectives have been set to ensure that the goal is met which are outlined
below:
2.1Technical Objectives:
 Chemical engineering design to achieve the following outcomes is to be done

 Understanding solving a complex engineering design problem
 Design a distillation column according to the engineering standards
 To design a distillation column to meet the desired criteria
 Gain an understanding of chemical engineering unit operations
 Description of a control system for the distillation column for best possible results is to be
done
 To study concepts of process control including principles of feedback and feed forward,
apply these concepts to the design of instrumentation and control system for a
distillation column.
 Propose a control system which will execute the desires of the process functionality
 Piping and Instrumentation Diagram for the distillation column is obligatory
 Exhibit an understanding of engineering codes, standards and regulations
 Develop skills through use of computer software such as Microsoft Visio

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 Carry out a group study on the HAZOP for any one of the individual selected processes to
achieve the following outcomes
 To be able to investigate how the chemical plant might deviate from the design intent
 To be able to identify scenarios that would lead to the release of hazardous and
flammable materials to the environment and also to determine whether a particular
deviation would result into an hazard
 Work effectively in a team to achieve the project goal
 Economic appraisal (group work) for the full process on production of 1,3 Butadiene in order
to gain the following outcomes
 Work effectively in the group to enhance team work skills
 To estimate the costs and benefits of production of products using the desired process
route
 To study the economic feasibility of the production of products
 Written report preparation based on the selected design to achieve the following
 Assemble and use relevant background information
 Provide Complete Referencing
 Appendices containing lengthy derivations, calculations, large drawing, computer
printouts etc.

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2.2 Personal Objectives:

 Understanding how chemical process work: Upon completion of this project, a better
understanding of the Butadiene process will be gained. Also technical skills in carrying out a
detailed distillation column design study will be improved, which will help towards future
projects as a chemical engineer.
 Enhance organisational skills and keeping to deadlines: The tasks would be scheduled at
regular meeting with the supervisor where the deadlines will be decided which have to be
met for a successful project.
 To utilize our initiative: Many decision making processes will be used in the undertaking a
couple sections of this project. Each member will need to use their initiative to come to a
sensible and reasonable conclusion, which will benefit the entire group.
 Develop Communication Skills: Communication skills are enhanced both by meetings with
the supervisor and the group meetings. This would provide and individual a platform to build
his confidence and propose his ideas.
 Enhance Team-working Skills: HAZOP and Economic Appraisal have to be carried out as a
group. The group members are required to co-operate with each other, share and listen to
ideas and take constructive criticism from group members. This will encourage each
member to provide advice and feedback.
 Professional report writing: At the end of our project I wish to able to deliver a professionally
laid out report.

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2.3 Schedule
To support me in achieving these objectives a schedule has been devised to plan the project and
ensure that all required tasks are undertaken, within the time period set for the study to be
completed. This can be seen below. A Gantt chart is also attached for assistance in the Section 3(b)
in the Appendix II. This is the revised Gantt Chat according to with the schedule has actually been
carried out. A Gantt chart which was made earlier to aid in maintain time is attached in Section 3(a)
in the Appendix II
2.3.1Project Schedule
Serial
No. Objective Start Date End Date
 Get feedback on report/presentation and

1 mass and energy balance from Dr. Titiloye
 Submit project plan. 19/01/10 22/01/10
2  Tutor meeting and discussing the topic.

 Gathering relevant information from 1st 25/01/10 29/01/10
term project
3  Discuss findings with tutor

 Put together a list of all the equations 01/02/10 07/02/10
required to design a Distillation Column for
the process
 Start Designing the Distillation Column in
the Butadiene production process.
4  Calculating diameter and size of Distillation 08/02/10 19/02/10

Column along with the flow though them
thereby completing the design
 Review the mass balance and calculating 22/02/10 5/03/10
other dimensions

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5  Piping and instrumentation diagram 1/03/09 10/03/10

 Control and instrumentation research
 Calculating cost and profit
6  HAZOP 10/03/10 19/03/10
7  Calculating cost and profit 01/03/10 15/03/10

 Economic appraisal
8  Completing referencing 25/01/10 17/03/10

 Executive summary 13/03/10 17/03/10
9  Ensuring completion of all section 20/03/10 21/03/10

 Submit report
 Review with tutor
 Make changes
10  Proof read 22/03/09 26/03/09

 Submit report
To complete the objectives of the project various sources would be utilised for research work. The
main source of information used will be university library, Birmingham city library, Aston
University’s access to online journals, internet and contacting companies in relation to scope of the
project. Discussions would be carried out with Dr. Titiloye to check the track of the work and to
ensure correct research is carried out.

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3 The Revised Process:
Phillips OXO-Process [3]

The n-butene, steam and air react at 590-650°C on a fixed bed heterogeneous catalyst (probably a
ferrite (iron or iron alloy) with Zn, Mn or Mg). Addition of steam controls the selectivity. With
butane conversions between 75-80%, the butadiene selectivity reaches
roughly 88-92%.
Magnesium ferrite
C4H8 + ½ O2 C4H6 + H2O..................................(1)
1 bar / 590-650°C
It is a one step process, where Butene gets oxidised straight away, without the need of butane
dehydrogenation. Since our plant is close to an oil refinery plant, where butane can be obtained at a
cheaper price in abundance, a decision to integrate the conversion of Butane to Butene in our
process was made. This reaction would take place in the first reactor and then the produced butene
is fed into the second reactor for further processing. The catalytic dehydrogenation of Butane to
Butene is not a part of our OXO process which we had considered in the previous report.[3] The
same method was carried out in the first project, but it was not stated clearly stated in literature.
Tubular Rector
C4H10 + O2 0 C4H8 + H2O.................................(2)
1Atms/590 C
Cromina-Alumina
Equation (1) gives 100% completion; higher conversions at lower temperatures are possible with
fewer side reactions and improved yields. It is also easier to remove the hydrogen as it is now
present as water vapor and can be condensed out. It is an exothermic reaction; heat input to the
reactor is thus eliminated as heat is recovered to generate high pressure steam. By feeding stream
and air to the reactor it is possible to carry out continuous in-situ catalyst regeneration. The steam
also absorbs some heat released by a small amount of hydrocarbon oxidation and has a beneficial
effect on butene selectivity to butadiene. In general, the equipment used is smaller and utilities
usage is reduced for a given throughout compared with the conventional dehydrogenation process.
A typical flow goes from the feed stream, with a composition of butene feedstock, 90% n-butene,

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5% butane, 2% of small amounts of Hydrocarbon and 1% Butadiene. Air is compressed and mixed
with steam before heating in a furnace at 480-590◦C. This mixture is then blended with butenes and
passed over the oxidative dehydrogenation catalyst bed in the reactor. Three reactors are used in
parallel (multitubular reactor) with a fixed bed of mixed oxide catalysts, feeding into a single stream
recovery and purification train. The products from the reactor are cooled. Heat is recovered from
reactor effluent with water sprays and can be used to generate process stream. After quenching,
Stream is cooled to about 400◦C, by direct contact with cold water. Cooling the stream causes
condensation, the condensate being removed by a simple phase separation. Washing and scrubbing
occurs in order to remove all water-soluble impurities, the C4 fraction is recovered in an oil
absorption section. The mineral oil absorber has the ability to absorb the hydrocarbon components
of the stream, in this case the butadiene whilst rejecting gases such as nitrogen, carbon dioxide. The
fat oil is stripped and crude butadiene is transferred to the final purification step. The product is
then obtained from the tailing column which is then fed into the recovery unit. Small amounts of
oxygenated compounds are also produced and these are separated and taken to a waste disposal
unit. Water sprays are used to reduce fouling in the plant.
The advantages for this process are that the catalyst life is long which lasts for around 1000 hours.
The capital costs compared to the other oxidative dehydrogenation process routes are more
favorable because of the low steam requirements for the mixture and the relatively high
concentration of butadiene leaving the reactor. Reactors are set up to de-coke the catalyst and
restore its activity, and to allow more effluent output of butadiene. At high temperatures (up to
6000C), oxygen acts to oxidatively regenerate the catalyst. Also there are a class of metal Vanadate
catalysts that are newly being used, which has highly selectivity and high conversions and the
formation of oxygenated by-products is suppressed. The feedstock raw materials are inexpensive in
the United States; a major factor causing this is the trend towards greater usage of feedstock such
as natural gas liquids (ethane, propane). However, there is a growing shortage of these raw
materials, encouraging the use of heavy feedstock such as ethylene. During this process, various by
products are produced. These by-products must be removed to produce butadiene, so it can be
polymerised. One major by product is vinyl acetylene, which is a highly unsaturated compound, a
poison for the catalysts that polymerise butadiene. Therefore there is a need to produce a
purification process by providing a stream with distillation steps. This allows the process to be
energy-conserving and simple.

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A revised Flow Sheet is attached in Appendix III. A compressor is added after the extractive
distillation column, in the new flow sheet that increases the pressure of the process before it can be
sent to the Propane Distillation Column for further purification.
I assume the mass balance to be correct as it was based on many assumptions which were
acceptable. A Copy of the Mass Balance done in the previous project is attached in Appendix IV.
4 The Chemical Design:

The design chosen for this project is a continuous distillation column. The separation of the liquid
mixture by distillation depends on differences in volatility between the components. The separation
becomes easier if the differences in the volatilities between the components are massive. Figure 5
shows a basic distillation column. The liquid mixture is heated up and routed into the distillation
column. The feed when enters the column flows down. Heat is vaporise the volatile components is
provided by the reboiler. The components with lower boiling points vaporise and rise to the top of
the distillation column. Vapour flows up and the liquid flows counter currently down the column.
These two phase come in contact with each other on a surface which can be trays or packing. The
composition of the vapour above the liquid differs from the liquid composition. The vapour is then
separated and condensed into a liquid; it becomes richer in the lower boiling component(s) of the
original mixture.
Part of the condensate from the condenser is returned to the top of the column which provides
liquid flow above the feed point and part of the liquid from the base of the column is vaporised in
the reboiler and returned to provide vapour floe rate. [5]

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Figure 5: Basic Distillation Column

http://wpcontent.answers.com/wikipedia/commons/e/e0/Distillation_Column.png
The highlighted distillation column in the flow sheet in Appendix III is the Propane/Butadiene
distillation column which is considered to be designed. The main objective of this unit is to get rid of
propane from the process. The distillation is a multi-component distillation thereby it involves more
than two components. It operates at very high pressure of 13.5 bars and consists of three streams.
The feed enters the distillation column at a temperature of about 350C. On distillation, the Propane
vapour leaves the top of the column to the condenser and collected in the reflux drum. Partial
amounts of 1,3 Butadiene is also lost at the top of the column. The bottom product majorly
comprises of 1, 3-Butadiene, 1, 2-Butadiene and Pentane.

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The table below shows the preliminary Mass Balance over the Distillation Column
Table 1 (a): FEED:
Components Flow rate (kg/h) Kmols/hr Kmols fraction
Propane 424.23 9.64 0.04
1,3 butadiene 11904.76 220.46 0.91
1,2 butadiene 500.00 9.26 0.038
Pentane 138.84 1.93 0.008
Total 12967.83 241.29 1
Table 1 (b): Distillate:

Propane 424.23 9.64 0.687
1,3 Butadiene 237.6 4.4 0.313
Total 661.83 14.04 1
Table 1 (c): Bottom:

1,3 Butadiene 11667.16 216.06 0.951
1,2 Butadiene 500.00 9.26 0.041
Pentane 138.84 1.93 0.0085
Total 12306.00 227.25 1
The boiling points of the feed components at 1 atmospheric pressure are as below:
Propane: −42.09 °C
1,3 Butadiene: -4.4 °C
1,2 Butadiene: 10.8 °C
Pentane: 36.1 °C
Looking at the temperature differences it can be said that the components can be separated easily
by reducing the temperatures but since in tangible situations, it is very expensive to reduce down
the temperatures in the plant for continuous process we have to increase the pressure inside the

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unit to separate it at reasonable costs. This is done by using compressors or pumps before the feed
is fed into the unit.
It is assumed that the distillate is at a temperature of 400C which is a reasonable assumption as
chilled water can be used to cool down the components in the distillate. Taking this as our basis we
can calculate the pressure and temperature for rest of our unit using Antoine’s Equation. Detailed
calculations are attached in Appendix V; Section (a)
4.1 Calculations:
Basis: 1hr
Units: 1 Kg
Propane boiling point: 40°C/313K @ 13.5 bars
Specifications
Feed condition: Cold Liquid under pressure
Feed inlet temperature @35°C/308K
Temperature of Top of distillation column @ 45°C/318K
Temperature of Bottom of distillation column @ 95°C/368K
Therefore column Temperature will be taken as the average @ 70°C/343K
The detail distillation design was performed by using the main steps below
- Determination of reflux ratio and number of stages required for the distillation
- Calculation of the column diameter and determining the type of column to be used, Packed
or trays
- Column design in detail

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4.1.1 Reflux ratio and the number of Theoretical Stages

The vapour reaching the top of the column is totally condensed and the resulting liquid is divided
into two parts. One part, L (reflux), is returned to the column and the other part, D (distillate), is
withdrawn as product. The reflux ratio is the ratio of L to D, that is R = L/D. [6]
Smaller values of reflux ratios means less the number of theoretical stages in the distillation column
increases, which reduces the energy costs as most of the vapour is condensed as distillate and only
partial amounts of reflux is sent back to the column.
The minimum reflux ratio and the infinite reflux ratio place a constraint on the range of separation
operation. Any reflux ratio between Rmin and Total R will produce the desired separation, with the
corresponding number of theoretical stages varying from infinity at Rmin to the minimum number
(Nmin at Total R). The relationship between R and N is shown in the Figure below. The choice of
reflux ratio to use is governed by cost considerations [7]
Figure 6: Generalised graph between number of theoretical stages V/S Reflux Ratio
http://www.separationprocesses.com/Distillation/DT_Chp04n.htm
Calculations:
The minimum reflux ratio is calculated by using Underwood method. [8]

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Since the minimum reflux is calculated for a distillation column which consists of four components,
four variables are used in the above equation. For a multi-component mixture to be split into two
streams (distillate and bottoms) by distillation, it is common to specify the separation in terms of
two ‘’key components’’ of the mixture. Hence in this way multi components can be reduced to
equivalent binary systems.
Light Key: Most Volatile component in the Bottom Product

Heavy Key: Least Volatile component in the Top Product. [8]
Hence, from the table 1 (b) and (c);
Heavy Key (HK) – 1,3 Butadiene
Light Key (LK) – 1,3 Butadiene
This will cause a problem in the calculation, since both the HK and LK are the same component
therefore an unreasonable reflux ratio will be obtained. Therefore to trounce this problem, a small
amount of Propane was added to the bottom product, making Propane the LK.
I assume that 99% mole of propane and 2% mole of 1,3 Butadiene is now in the Distillate and the
remaining are the bottom product.
Revised Balance over the distillation column is as follows:
Table 2 (a); FEED
Feed
Flow rate Kmols/hr Kmol
Components (kg/h) Fraction
Propane 424.23 9.64 0.04
1,3 220.46 0.91
butadiene 11904.76
1,2 9.26 0.04
butadiene 500.00
Pentane 138.84 1.93 0.01
Total 12967.83 241.29 1

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Table (b); Distillate and Bottoms

Distillate Bottoms
Components Kmols/hr Kmol Fraction Kmols/hr Kmol Fraction
Propane 9.544 0.684 0.096 0.0005
1,3 4.41 0.316 216.05 0.95
butadiene
1,2 - - 9.26 0.041
butadiene
Pentane - - 1.93 0.0085
Total 13.954 1 227.336 1
Therefore new key components are:

HK – 1,3 Butadiene
LK – Propane
The next step is to find the relative volatilities of each component with respect to the HK which in
this case is 1, 3 Butadiene. The calculations are attached in the Appendix V, Section (b) and are
tabulated below:
Table 3:
Components α
Propane α =2.724
1,3 Butadiene α= 1
1,2 Butadiene α = .66
Pentane α = .31
Using the UNDERWOOD EQUATION:
Where q ≠ 1 as the feed is cold liquid @ 35°C.

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Calculation of feed condition q[9]:
Therefore,
Table 4: Latent Heat of the Components inside the Column [9]

Components Latent Heat in Relative Calculation Latent Heat in
KJ/Kg Molecular KJ/Kmol
Mass
Propane 229.93 44 229.93*44 10116.92
1,3 Butadiene 335.55 54 335.55*54 18119.7
1,2 Butadiene 387.38 54 387.38*54 20918.52
Pentane 333.24 72 333.24*72 23993.28
Latent Heat = (10116.92* 0.04) + (18119.7* 0.91) + (20918.52* 0.038) + (23993.28* 0.008)
Latent Heat = 17880.454 J/mol or KJ/Kmol
Table 5: Specific Heat of the Components inside the Column [9]

Components Specific Heat in
KJ/KmolK
Propane 81.84
1,3 Butadiene 138.78
1,2 Butadiene 136.08
Pentane 182.88

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Specific Heat to Vaporize the 1 mol of feed = mcp∆T + mHvapuorisation

=> {[(81.84*0.04) + (138.78*0.91) + (136.08*0.038) + (182.88* 0.008)] * (70-35)] } + 17880.454
J/mol
Specific heat to Vaporise 1 mol of feed to 70oC = 4766.79 J/mol + 17880.454 J/mol
Therefore, Specific Heat = 22647.244 J/mol
q = 1.267
Using the above value of “q” in the Underwood Equation (1), θ is obtained;
θ θ θ θ
Therefore; by using excel spread sheet:

Θ= 2.67; which is acceptable as the value for Θ should lie between the values obtained for relative
volatility of heavy key and light key.
Next, proceed to calculate Rmin.
Rmin +1=1.468, therefore Rmin = 0.468.

Reflux ratio is generally between 1.1 -1.5 times the minimum reflux ratio based on practical values
but there is no relationship between Rmin and the optimum value.[8]
R = 1.1*0.468= 0.515
To find the number of theoretical stages using FENSKE EQUATION [11]

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Therefore,
From CHART – Erbar-maddox correlation in the figure below we have,
Graph 1: Ebbar Maddox Correlation

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N= 20 theoretical stages
Table 6: Number of theoretical stages at different Reflux Ratios
R R/R+1 Nm/N N
1.1*0.468 = 0.515 0.34 0.4 20
1.2*0.468 = 0.562 0.36 0.42 19
1.3*0.468 = 0.608 0.39 0.49 16
1.4*0.468 = 0.655 0.4 0.53 15
1.5*0.468 = 0.702 0.41 0.55 15
1.6*0.468 = 0.749 0.43 0.58 14
From the above observations it is clear that increasing the reflux ratio reduces the number of
stages. But it is seen that increasing the minimum reflux ratios by 1.4 to 1.5 does not changes the
number of theoretical stages.
There are two options available to decide which reflux ratios could be used in our design. Either a
line can be drwan from the origin of the graph as shown below which means that the best available
technique is a mid way between the number of stages and the reflux ratio or this can be debated on
the basis of economic costs.
Figure 8: Selection of Reflux ratio and the number of stages

http://www.separationprocesses.com/Distillation/DT_Chp04n.htm
The increase in the reflux ratio reduces the number of stages in a distillation column. But energy
costs shoot up which has to be considered as well. Since the Distillation column is almost running

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for (350 days* 15 years) approximately, it is not a good option to run the column at high reflux
ratios. But if very low reflux ratios are opted, the metal costs to build the column go up. The reflux
ratio chosen for the process is 1.3 × Rmin. I have decided to use a reflux ratio of 0.608 which requires
reasonable costs and the number of stages are also acceptable. [8]
If the Feed is assumed to enter the column at its boiling point there is a huge difference in the reflux
ratios
4.1.2 Determination of the Diameter of the Column:
FAIR CORELLATION (1961)[10] is used to calculate the diameter of the column. To find the diameter,
velocity of the fluids has to be calculated. The calculations are detailed below:
Internal Traffic [11]:

L =RD ; 0.608*661.83 = 402.39kg/hr
L’ = L + qF ; 402.39+(1.267*12967.83) = 16832.63 kg/hr
V = L+D ; 402.39+661.83 = 1063.22 kg/hr
V’ = V – (1-q)F ; 1063.22 – (1-1.267)* 12967.83= 4525.63 kg/hr
FLV = L/G (ρV/ρL)0.5 [18]
where;
L = Liquid mass flow rate, kg/s
G = Vapour mass flow rate, kg/s
Vapour density, kg/m3 = ρV
Liquid density, kg/m3 = ρL
The calculation of ρL and ρv (see section (C) of Appendix V)
ρL = 599.69 Kg/m3 and ρv = 30.324 kg/m3
The Flooding correlation is calculated at both the sides of the column because it can be a stepped
column.
Therefore, the flooding correlation above the feed

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Using the CHART –flooding velocity, sieve plates, in Graph 2 and taking a generalized plate spacing
of 0.6m:
Graph 2: Flooding Velocity Sieve plates
K1 (top) = 0.1
The velocity can now be calculated by;
Hence,
Taking percentage flood @ 80% based on good design considerations, therefore velocity @
flooding:
uf (top) = 0.8*0.4333 => 0.34664 m/sec

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Maximum Volumetric Flow Rate:
Net Area Required
Allowing 10% for down comer and 10% for support rings;
There total area = 0.028*1.1*1.1 = 0.034 m2
Hence column diameter above the feed point;
√ √
Similarly for the lower section of the column;
Using the CHART –flooding velocity, sieve plates in Graph 2; taking a generalized plate spacing of
0.6m:
K1 (bottom) = 5*10-2
The velocity can now be calculated by;

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Taking percentage flood @ 80% based on good design considerations, therefore velocity @
flooding:
uf (bottom) = 0.8*0.21665 => 0.17332 m/sec
Maximum Volumetric Flow Rate:
Net Area Required
Allowing 10% for down comer and 10% for support rings;
There total area = 0.237*1.1*1.1 = 0.288 m2
Hence column diameter below the feed point;
√ √
4.1.3Feed Location:
The number of stages is greatly affected by the subsequent position of the feed into the column.
The feed should enter the column at a point that matches best with the composition of the feed. It
is always a wise decision to provide two or three feed point nozzles around the predicted feed point
which will account for the changes in the feed compositions after the start up.
The propane Distillation column is operating under high pressure. Hence, the feed is either
compressed or pumped into the column. It can be made to compress to a slightly higher pressure

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into the feed pipe, approximately 14 bars, so that when it enters the column which is slightly at a
lower pressure than the pipe, some of the propane from the components will immediately expand
and undergo a partial flash vaporisation resulting in vapour liquid separation as it enters the
distillation column.
4.1.3 Calculation of the Feed Position:
Krickbride(1994)[13] can a practical equation to calculate the feed point location
[ ]
Where,
Nr = number of stages above the feed, including any partial condenser
Ns = number of stages below the feed, including the reboiler
B = Molar Flow Bottom Product
D = Molar Flow Top Product
XfHK = concentration of the heavy key in the feed
XfLK = concentration of the light key in the feed
XbLK = concentration of the light key in the bottom product
XdHK = concentration of the heavy key in the Distillate
Therefore, by substituting the values in the above equation;
[ ]

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This can also be rewritten as;

......................(A)
Since the total number of stages being used is 16,

Therefore;
Substitution the value of Nr from Equation (A) in equation (B),

We get, Ns = 12.8 (≈ 13) which means, there are 13 stages below the feed position which includes
the reboiler as well.
Since, the feed location is almost at the top of the column leaving 3 stages, the design of a stepped
column is pointless. It is made with an overall diameter of 0.6m.
4.2 Choice of Plates and Packing:
The calculated value for the distillation column is approximately 0.6 m. The choice between packing
and trays was made on the basis of advantages and disadvantages of each type, and it is concluded
that a PACKING would be best for such small diameters. This decision was made because: [14]
 Plate columns are generally designed to handle wider range of vapour and liquid flow rates
than packed columns. Since the gas flow rates in the top of the column is minor, plate
installation would not be a good idea.
 Packed columns are not suitable for very low liquid flow rates.
 The pressure drop per equilibrium stage (HETP) is lower for packing than plates. Since, the
column is operated at high pressures; it would be a better option to choose packed column
rather than plates to avoid complications.
 Packing should always be considered for smaller diameters, generally for column diameters
>0.9m as it is very expensive and difficult to install plates in such columns.
After the decision is made, the design over the packed column has to be done. This includes the
following procedures: [14]
 The type and packing size has to selected corresponding to the diameter of the column
 Determining the height of the column required for the desired separation

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 Calculation of the column diameter (capacity), to handle the liquid and vapour flow rates.
 Selection of column internal features like; packing support, liquid distributor, redistributors.
4.2.1 Types of Packing:
A packing should always fulfil the following requirements: [14]

 Provide a large interfacial area between the gas and the liquid.
 Should have an open structure for low resistance to gas flow.
 Should provide consistent liquid distribution on the packing surface
 Promote unvarying vapour gas flow across the column cross section
Hence, keeping the above requirements into consideration, the packing is broadly classified as
 Structured Packing: These are packing with standard geometry made of wire mesh or
perforated metal sheets which are folded and arranged together. Some metal structured
packing commonly used in distillation columns are shown in the figure 10. They have low
height of equivalent theoretical plates (HETP) and low pressure drops. They are generally
used in difficult separations which require many stages, like separating isotopes or in high
vacuumed distillation columns. Using structured packing can also used to increase the
capacity and reduce the reflux ratio requirements.
Figure 10: Structured Packing

http://img.alibaba.com/photo/50678452/Ceramic_Metal_Plastic_Structured_Packing.jpg

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 Random Packing: These are variously shaped in rings, saddles etc, and are dumped into the
distillation column to take up a random shape. These structures can be made up of plastics,
ceramics and metals. The various types of random packing are shown in figure 11 below. The
packing manufacturers should be consulted for details for many special types of packing that
are available for special applications.
Figure 11: Various kind of random packing

http://img.alibaba.com/photo/50553772/Ceramic_Random_Packing.jpg
Raschig rings are the oldest types of random packing whose length is equal to the diameter. These
are cheaper compared to any of the random packing structures but not as efficient as others.
These were then modified to Pall rings which have openings made by folding strips of the surface
into the ring. This increases the liquid distribution by increasing the surface area.
Other types of random packing are, Berl Saddle Ceramic, Intalox Saddle Ceramic, Metal Hypac and
Super Intalox Ceramics.

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Selection of Packing:
Type and Material [15]:

From the above information it would be cheaper to use Random Packing with Metallic (Carbon-
Steel) Pall Rings. This is because the column is operating at high pressures and has a very small
diameter. Also the components inside the column are non-corrosive. It would require too much
effort and capital to install structured packing inside the column which would separate the same
amount of propane. Also Ceramic pall rings can be considered, but they are more expensive than
the metallic ones.
Figure 12: Metallic Pall rings

http://www.pall-ring.com/images/product/Chempack_metal_pall_ring_02.jpg
Packing Size [15]:

The largest size of packing suitable for any size of column should not exceed more than 50mm. This
is because the larger packing sizes would cause flooding due to poor liquid distribution. Very small
sizes are also available but are much more expensive than the larger ones.
The sizes recommended for different column diameters are:
Table 7: Packing size depending on the Column Diameter
Column Diameter Packing Size
< 0.3m < 25mm (1inch)
0.3 m to 0.9m 25mm to 38mm (1inch to 1.5 inches)
> 0.9m 50mm to 75mm (2 inch to 3 inches)
Hence, for the Propane distillation column Metallic Pall rings with a size of 25mm is used.

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Column Diameter (capacity)[16]:

A distillation column is always designed to operate at height economical pressure drop. This ensures
good liquid and gas distribution. For random packing the pressure drop normally does not exceed
more than 80mm of H2O/m of the packing column.
A distillation column’s design values for pressure gradients are between 40 -80 mm Hg/m packing.
[17]
These values are almost halved when the liquid starts to foam. The proposed design has a
diameter of 0.61m with trays. Since random packing is now considered a new diameter has to be
calculated.
Pressure gradient over the enriching section using column diameter as 0.61m
A generalised pressure gradient/flooding correlation graph can be seen in Graph 3 below:
Graph 3: Graph to determine the Flooding Line

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Values for “x” and “y” axis can be calculated and the flooding line can be plotted in the figure above.
Where,
L = Liquid Rate per Area
G= Gas Rate per Area
Since the area remains same; the ratio can just be taken as the normal flow rates of vapours and
liquids.
Hence;
Now,
Where,
Fp = Wet Packing Factor; Appendix V; section (d)
Ψ = Ratio; (density of water/Density of Liquid inside the column)
μL = Liquid Viscosity of 1,3 butadiene is considered in the calculations, as major fraction of the liquid
comprises of 1,3 Butadiene
g = Gravitational constant
Hence;
From the Graph 3; the flooding line is calculated at 6, which is 81 mm Hg/meter. This result is
acceptable since the pressure gradient calculated above, 6mm Hg, it is concluded that the system is
expected to run at very extreme pressure gradients.

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The values of pressure gradients for the lower range over the distillation column can be used to
calculate a new diameter. Any of the values between the two ranges can be used for the design.
From the same graph above a new value of “ ” is plotted at 40mmHg/m is now calculated.
Hence the Flooding line would be,
As 13.6 mm Hg is the specific gravity of mercury.

“ ” axis in now 0.015.
Again using Equation on the Y axis in Graph 3; a new gas flow rate per area is calculated which
would give the new diameter.
Since,
Therefore,
Since the gas flow rate per area in decreased; the diameter has to be increased.
Hence,
√ √
Since, the change in diameter is not drastic the packing used can still be suitable for this diameter.
The capacity of the column can be anything between 0.61m – 0.66m depending on the flooding line.
Hence, it has been concluded that the capacity will be 0.65m; which can also be helpful when the
production capacity of the plant increases. The flooding like can be changed accordingly.

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Packed Bed Height:[18]

The heights of equivalent equilibrium stage or HTEP is the height of a single packing which gives the
same amount of separation as an equilibrium stage in a trayed column. The HTEP is for a specific
type of packing is usually constant and is independent of the physical properties of the components.
This provides good liquid distribution and does not let the pressure drop fall below 17mm H 2O/m of
the packing height.
Table 8: The recommended HETP’s for Pall rings

Size of the Pall Ring in mm HETP in m
25mm 0.4m – 0.5m
38mm 0.6m – 0.75m
50mm 0.75m – 1.0
Hence, HETP for the propane distillation column is 0.5m as the size for pall rings used is 25mm.
This means, one stage is 0.5m since there are 16 stages calculated earlier, total height of the column
= 0.5*16 = 8m
Flooding is prevented due to the tall height of the column.
Since the feed stream is put after 3 stages; the position of the feed stream is (0.5m*3 stages) 1.5 m
at the top and the length below it is 6.5 m.
Choice of material used for construction:

The column is decided to be made up of stainless steel (18Cr/8Ni, Ti stabilised)(321). Steel is a very
strong metal with high ductility and high malleability which can withstand high stress. Since the
column has to with stand high pressures and high temperatures, poor choice of material should not
be used. Also the column is very tall. Also stainless steel does not corrode. It is more expensive than
carbon steel, but it one time investment is affordable. Also the column is required for purification
purposes; hence any corroded metal in the product would not be appreciated.

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Thickness of the metal:

It is assumed that the column is cylindrical in shape. The welds are fully radio-graphed. This column
is operating at very high pressure of 13.5 bars. Hence, a pressure has to be designed in such a way
that the column resists the increase in pressure due to equipment failure.
Internal pressure is designed at 10% above operating pressure.
= (13.5 – 1)* 1.1 => 13.75 bars (1.375N/mm2)
The thickness of the cylindrical section of the column can be calculated by a formula from British
standards PD 5500:
Where,
Pi = Internal pressure
σs = Design Stress for stainless steel @ 1000C; Appendix V; section (e)
e = minimum thickness of the material
Hence,
Allow 1mm for corrosion;

Hence the thickness of the cylindrical section should be 4mm.
The thickness of the Domed Section of the column can be calculated by:
A standard dished head (torisphere) is assumed;
Crown Radius, Rc = Di = 0.65 m

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Knuckle radius = 6%of Rc = 0.039m
( √ ) ( √ )
A head of this size would be formed by pressing: no joints, hence, J = 1
Substituting, correct values in the above equation;
A tank diameter of less than 15m should have a minimum allowable thickness of 5mm [16]. The
thickness obtained from calculation would hold the weight of content in the vessel, but would not
stand depression or dent. Therefore, a 5mm minimum allowable thickness was given for any vessel
less than 1m because this can withstand depression. Hence, the results obtained are acceptable.
Diameter and Thickness of the Pipes:

It is decided to use Pipes made of Stainless Less because they have high tensile strength and are
ductile. These twp parameters are matter much as the system is operating at high pressures. The
diameter is calculated by equation 19[20] and the thickness is calculated from equation 20[20]
For Stainless steel;
The thickness of the pipe; t

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 The Feed Pipe:
And;
 Pipe to the Condenser:
And,
 Pipe to the Reboiler:
And,
4.3 Column Internals [21][22]:

The internal packing in a packed distillation column should be designed carefully, to ensure better
performance.
Generally, the standard fittings are developed by the packing manufacturers and its uses are
specified. Some of the typical designs are discussed as follows.

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Packing Support: The support plate

carries the weight of the random
structures inside the column. A poorly
designed of the support plates causes
flooding or very high pressure drops
inside the column. A simple Grid or a
perforated plate support can be used.
The only disadvantage with such kind of
support systems is that the liquid and
the gas have to vie through the same
openings. Hence, wide spaced grids are
used to avoid this problem and increase
the flow area. The larger sizes packing are dumped into the column first if wider grids are used,
which support the smaller random packing. (As shown in Figure 13)
The best design for packing support is the

gas injection type of support. The gas
inlets are provided above the level where
the liquid flows from the bed. The
problem of local flooding and high
pressure drops is solved with the
application of these support rings. These
supports are available in a variety of sizes
and materials, like plastics, ceramics and metals.
Figure 14; shows design for the gas injection supports and Figure 15 shows the Principle of gas
injection packing support

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Liquid Distributors:
Uniform flow of liquid throughout the

column and good initial liquid distribution
is a very essential factor for good
performance of a column. A central open
feed pipe or a pipe with a spray nozzle is
best suited for proper distribution of
liquid in small diameter columns. But for
larger diameters, more elaborate designs
are required. The two most common type
of distributors used are orifice type and
weir type.
The orifice type has holes in the plate
which allows passage for the liquid and it has short stand pipes, through which the gas flows. Sizing
of gas pipes are compulsory as it provides sufficient area for the gas flow without letting the
pressure to drop significantly. The holes should be of an appropriate size, neither too small nor too
big so that at lowest liquid flow rate, there should be a level of liquid always present on the plate
and at highest flow rates, the liquid distributor does not over flows. Figure 16 shows the C.S and the
T.S of an orifice distributor.
In the Weir types the liquid flows over the notched weirs in the gas stand-pipes. These stand an
upper grade over the orifice type in handling wider range of liquid flow rates. The column designed

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uses Orifice type of distributor. A pipe manifold distributor shown in figure 17 is used when the
liquid is fed to the column under pressure and the flow rate is reasonably constant. The distribution
pipes and orifices are accurately sized for equal uniform distribution.
Orifice
type is exploited in the propane distillation column.
Liquid Redistributors:
The main purposes of redistributors

are to collect liquid that has moved
to the column walls and redistribute
it evenly over the packing also
redistributors will even out any
maldistribution that has occurred
within the packing.
A full distributor shown in figure 18 combines the function of packing support and liquid distributor.
The maximum bed height that should be used without liquid redistribution lies solely on the type of
packing and the process. The wall-wiper type is mainly used in small columns of less than 0.6m in
diameter. This operates in a mechanism were a ring collects liquid from the column wall and
redirects it into the centre packing.

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Hold Down Plates:

Fluidisation of the top layer of packing can
occurs due to high gas flow rates or surging
effects due to mis-operation. The ceramic
packing crushes during such circumstances but
the metal and plastic packing can be wafted
out of the column. Bed-Limiters are used for
plastic and metal packing to prevent to
prevent expansion of bed at higher pressure
drops.
These are similar to Hold Down plates. Such
plates should have smaller grids to retain the
packing but not too small to restrict the fluid flow.
Installing Packing:
The column is filled with water and the packing is dumped into the water ensuring the level of
water always being above the packing at all times. Metal and Ceramic packing are generally
deserted into the column “WET”. This ensures random distribution and prevents any damage to the
packing.
In case of “DR ” packing the packing should be lowered into the columns in buckets or other
containers.
Concept Drawing:
The Concept Drawing Details the application of column internals more in detail. Bit-Map is used to
create the column showing every possible detail and dimension. The non calculated values are
assumed to British standards.

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5.0 CONDENSER:
Condensers are units similar to heat exchangers, which are used to condense the vapours to their
liquid state. Condensers vary in size ranging from hand handled units to large industrial scale units.
For condensers used in distillation columns, the process fluid generally flows through the shell side
and the cooling fluid is made to flow through the tube side. The two fluids never come in contact
with each other. The diagram below shoes a one tube pass condenser.
Figure 20: One pass tube side condenser

http://upload.wikimedia.org/wikipedia/commons/c/cd/Straight-tube_heat_exchanger_1-
pass.PNG
Four condenser configurations are possible:[23]

 Horizontal, with condensation in the shell, and the cooling medium in the tubes
 Horizontal, with condensation in tubes
 Vertical, with condensation in shell
 Vertical, with condensation in the tubes
Horizontal shell side and vertical tube side is widely used as condensers. The other two are usually
used in arrangements for heaters and vaporisers using steam as the heating medium.

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Assumptions:
 It is assumed that a horizontal shell side condenser is used to cool the propane vapours.
 It is a complete condenser. Hence all the vapours are cooled down.
 There is one shell and one tube pass inside the condenser and the flow is counter current.
 Since the top product mainly comprises of the propane, the physical properties of propane
are used for all the calculations.
 The cooling fluid chosen is chilled water that enters the tube side at 15 0C and leaves at 450C.
 The tube layout for this particular design is arranged in a squared pitch.
Basis: 1 hour
Flow rate entering the condenser; V
V = L+D; 402.39 + 661.83 = 1063.22 kg/hr
5.1 Energy Balance Over the condenser:

Q = (Vapour flow rate * latent heat of vaporisation of methanol) + mCp∆T
“mL” due to phase change, since it is a complete condenser where phase change occurs; and
“mCp∆T” due to increase in the energy per degree rise in temperature.
Vapour Flow Rate;
Latent heat of Vaporisation of Propane (1,3 Butadiene is ignored as it would not bring a vast
difference)= L = 322.76 kJ/Kg
Therefore,

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Since the Heat lost by the condenser is calculated the flow rate of water required can also be
calculated as relevant from the following formula;
It is assumed earlier that the chilled water enters the condenser @ 150C and leaves @ 450C. Hence
∆T = 300C
Hence,
Water flows at a flow rate of 0.781Kg/sec inside the tubes.
Figure 21: My Diagram for better understanding of ∆T LM
From the diagram above it now becomes easier to ∆TLM. The Log mean temperature difference is
given by:
Where,
∆TLM = log mean temperature
TIN = inlet temperature of process fluid

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TOUT = outlet temperature of process fluid

tIN = inlet temperature of cooling water
tOUT = outlet temperature of cooling water
To begin with the design, we assume an approximate overall coefficient. This is done in aid with
Graph 4; where the fluid in the process side are classified as Paraffin and the fluid in the service side
is taken as River, Well or Sea Water.
Hence, the assumed overall coefficient = 600 W/m2 0C
Graph 4: Overall Coefficients (join process side to the service side and read U values from the
centre line)

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Trial Area:
Where,
Q= Heat Transfer per unit Time
U= Heat Transfer Coefficient
A= Area
∆TLM = Log Mean Temperature difference
Layout and Tube Size[24]:
Usually the plant standards require tubes of:

 The outer diameter is 20mm
 The inner diameter is 16 mm
 The length is taken to be 2.44 m (8 ft)
 The tubes are made of arbitrary brass.
 The arrangement is a squared pattern.
Hence, the surface area can now be calculated from the above data specified.
Therefore,

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Since there is slight condensation occurring, hence the number of tubes calculated is so less.
Since, it was decided to use a Square Pitch;
Tube Bundle Diameter; Db
Where,
Nt = number of tubes
K1 and n = constants obtained from table 9[25]
Do = Outer diameter
Table 9: K and n constants for square arrangements:
Square pitch, Pt = 1.25 do
Number of Passes 1 2 4 6
K1 0.215 0.156 0.158 0.0402
n1 2.207 2.291 2.263 2.617
Hence,
Number of tubes in the centre row:
We take it as 12 tubes as the number of tubes should be even and divisible by 4 as the arrangement
is a square pitch.

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5.2 Shell Side Coefficient:

The Tube Wall temperature, Tw can be estimated if the condensing coefficient is assumed. The value
for the condensing coefficient is assumed to be 1500W/m0C
Mean temperature:
Hence, the wall temperature is 350C.

Table 10: Physical Properties of Propane @ 350C[26]
Liquid Density (ρL) @ 350C 514.13 Kg/m3
Liquid Viscosity (μL) @ 350C 0.11321 centi-poise
Liquid Thermal Conductivity (kL) @ 350C 0.095W/m K
Vapour Density @ 40 0C mean vapour temperature (ρV) = 28.6 Kg/m3

Using Kern’s Method [27], the mean transfer coefficient for the tube bundle is given by:
( )
ρ (ρ ρ ) ( )
[ ]
μ
Where,
Wc = Flow rate of the distillate in Kg/sec

L = Length of the tubes
Nt = Number of tubes

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Hence,
Substituting the values in the Kerns Equation:
( )
( )
[ ]
The value obtained is close enough to the value assumed (1500W/m 2K), hence the estimated Tw is
acceptable.
5.3 Tube Side Coefficient:
Eagle and Ferguson (1930) adapted a much reliable formula for the heat transfer coefficient for
water used in the tube side. This is stated as below:
Where,
hi = inside coefficient for water
t = mean water temperature
ut = water velocity
di = tube inside diameter
ut can be calculated from the internal diameter of the tube

Tube Cross- Sectional Area;

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Density of water at 27.50C (mean water temperature in the tubes) = 995.65 Kg/m3
Tube Side Velocity, ut
Hence, substituting the values of velocity, the heat transfer coefficient of water inside the tube is;
5.4 Overall Heat transfer Coefficient U;
Where,
U = the overall coefficient based on the outside area of the tube, W/m 2 0C
ho = outside fluid film coefficient, W/m 2 0C
hi = inside fluid film coefficient, W/m 2 0C
hod = outside dirt coefficient; fouling factor, W/m 2 0C
hid = inside dirt coefficient; fouling factor, W/m 2 0C
kw = thermal conductivity of the tube wall material, W/m0C
di = tube inside diameter, m
do = tube outside diameter, m
Fouling Factors: As neither of the fluid is heavily fouling, the dirt coefficient at both the sides has
been assumed to be 6000 W/m 2 0C and kw is assumed to be 50 W/m0C

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Substituting all the values in the equation 31;
Hence, Overall Heat transfer coefficient;
The value obtained is significantly lower than the assumed value of 600 W/m2 0C
The calculation has to be repeated using different values of Overall heat transfer coefficient by trial
and error method; and the closest possible answer firms up the final design.
The calculations are redone with a new value of 500 W/m2 0C
Hence, the number of tubes now changes,
Tube Bundle Diameter; Db

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Shell Side Coefficient:

As already known,
( )
ρ (ρ ρ ) ( )
[ ]
μ
Where,
And
Therefore, substituting the values of Гh and Nr in equation 32
Tube Side Coefficient:
Again using Eagle and Ferguson’s (1930) formula tube side coefficient is calculated. But the velocity
of the water in the tubes changes;
New Cross sectional Area

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Hence, the tube velocity,
Hence, the new calculated value for the Tube Side Coefficient;
Overall Heat transfer Coefficient;
Hence, Overall Heat transfer coefficient;
The results are satisfactory. The values obtained are close enough to the values assumed hence, the
design is confirmed.
5.5 Shell side Pressure Drop:
Specifications:
 Pull through Floating head is used, no close clearance is required.

 35% cut of the Baffle Spacing
 A condenser has wider baffle spacing, lB ≈ Ds

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Pressure Drop is given by;
Where,
Jf = Friction factor
L = Length of the tubes
Lb = baffle Spacing
All the unknowns are calculated below.
Shell internal Diameter; Ds
Clearance is = 89mm estimated from the graph 5
Graph 5: Shell- Bundle Clearance

Hence,

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Cross Sectional Area As for the hypothetical row of tubes at the Shell Equator
Where,
Pt = Tube Pitch
Ds = shell inside diameter
LB = baffle spacing
Shell Side mass Velocity Gs
Where,
Ws = Fluid Flow Rate on the shell side in kg/sec
Linear Velocity us
Shell Side Equivalent Diameter; de

The equivalent diameter for a square pitch arrangement is given by;
( )

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Friction Factor; jf
Friction factor is estimated from a graph in FIG; which is a correlation between Reynolds’s number
and baffle cut.
Hence,
Graph 6: Shell side Friction Factor; Segmental Baffles
From the graph Friction Factor is determined to be 4.8 *10-2
Substituting all the above calculated values in the pressure drop equation;

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Ignoring the viscosity correlation;
The Pressure drop is negligible; hence more sophistication calculation is not justified.
5.6Tube Side Pressure Drop:
The pressure Drop on the Tube side is given by,
[ ( ) ]
The viscosity correlation is neglected;

Jf ; Friction Factor is given by a graph 7
Where,
Hence,

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Graph 7: Tube side Friction Factor

Hence from the graph below,
Jf = 9*10-3
Substituting the values in the pressure drop equation;
The pressure drop is almost negligible due to the following reasons:

 The flow is laminar as Re < 2000
 The velocity of the cooling water is very low
 Only one tube pass is used, hence there is a straight pipe through which the pipe flows.

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6.0 REBOILER:
Reboilers are used with the distillation column to vaporise a fraction of the bottom product.
There are three different kind of reboilers used: [28]
 Forced Circulation; where the fluid is pumped through the exchanger. The vapour formed is
separated and sent back to the bottom of the distillation column and rest is removed.
Figure 22: Forced Circulation Reboiler

http://upload.wikimedia.org/wikipedia/commons/a/a7/ForcedCirculation.png
 Thermosyphon, unlike forced circulation it has natural circulation. The liquid circulation is
maintained by the difference in densities of the two-phase mixtures of vapour and liquid.
These kinds of Reboilers can have vaporisation on the tube side; when they are vertically
placed or the vaporisation occurs on the shell side, when placed horizontally.
Figure 23: Thermosyphon

http://upload.wikimedia.org/wikipedia/commons/5/57/Thermosyphon_Reboiler.png

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 Kettle Reboilers, also called submerged bundle reboilers; where boiling takes place on the
tubes immersed in a pool of liquid. The liquid does not circulate through the heat exchanger.
These are the most expensive kind of Reboilers.
Figure 24: Kettle Reboiler

http://www.spiraxsarco.com/images/resources/steam-engineering-
tutorials/2/13/Fig_2_13_5.gif
6.1 Heat Duty over the Reboiler:
In the above equation, the ∆H® (Heat of Vaporisation) is considered only for 1, 3 Butadiene as major
fraction of the component entering the Reboiler comprises of 1, 3 Butadiene. Minor fractions of
propane, pentane and 1, 2 Butadiene is ignored. This would not affect the result drastically as the
Heat of vaporisation of the other components somewhere lies in the same range.
Hence,
Assuming; that the bottom product is liquid at boiling point which enters the Reboiler at 368K.
Amount of Steam Required:
Heat obtained by the process fluid is the heat lost by the steam entering the Reboiler.

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Hence the “Q” remains same. Assuming steam entering the Reboiler at 2.6 bars,
Hence, ∆H® for steam at 2.6 bars = 2177.42 KJ/Kg
6.2 Choice of type of reboiler used with the Propane Distillation:[28]
The choice of the kind of reboiler used with a distillation column solely depends on the following:
 The viscosity and the propensity to fouling of the process fluid
 The operating pressure
 The headroom available to layout the equipment.
After careful judgement, it is concluded that a Horizontal Thermosyphon Reboiler would be used
with this distillation column, since the horizontal reboilers require less headroom. These are most
economical type of reboilers for most application and are not suitable for high viscous fluids. The
fluids in the column have very low viscosity.
Also these reboilers are suitable for high temperatures and high pressure which fulfil the demands
for this unit.
The only disadvantage with this kind of reboiler is that a hydrostatic head is required for the
thermosyphon effect which requires elevation of the column base. This problem can be overcome
by using supporters at the distillation column is not huge.

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7.0 Overall Energy Balance over the Distillation Column:
The Energy Balance over the column could not be calculated in the first part of the assignment as
the Reflux Ratios were unknown.
The Heat Duty over the Condenser and the Reboiler is calculated. It is summarised in the table
below.
Units Energy Required Energy Released
Condenser - 98.434 KW
Reboiler - 421.826KW -
Total -323.392 KW
The Negative Sign shows that the Energy is required to run the unit.

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8.0 Piping and Instrumentation Diagram
The Piping and Instrument diagram (P and ID) shows the engineering details of the
equipment, instruments, piping, valves and fittings and their arrangements which is not
detailed in the process Flow sheet. It should include the following. [29] [30]
 All process equipment identified by an equipment number. The equipment should be

drawn roughly in proportion, and the location of nozzles shown.
 All pipes, identified by a line number. The pipe size and material of construction
should be shown. The material can be included as part of the line identification
number.
 All valves control and block valves, with an identification number. The type and size
should be shown. The type may be shown by the symbol used for the valve or
included in the code used for the valve number.
 Pumps identified by a suitable code number.
 All control loops and instruments, with an identification number.
 For simple processes, the utility (service) lines can be shown on the P and I diagram.
For complex processes, separate diagrams should be used to show the service lines,
so the information can be shown clearly, without cluttering up the diagram.
Since the Process of Butadiene production is very complex which includes many units, the P
and ID is only done over the Propane Distillation Column which is attached in Appendix, 6
(issue number 002) The basic units and symbols used in the P and ID are briefly described
below:
 Control Valves [31]: The parameters such as temperature, pressure, flow and level are
controlled by the control valve. Control Valves can be manual or automatic which are
partially or fully open or closed. The action of the control valves are in response to the
signals received from their respective controllers that compare the set-point to the
process variables.
Figure25: Detailed Diagram of a Control Valve

http://www.isa.org/Images/InTech/2005/April/20050415-3.gif
 Gate Valve [32]: These valves are opens by lifting a round or rectangular wedge out of
the path of the fluid. Gate valves are used when a straight-line flow of fluid and
minimum restriction is desired. These valves should never be used as control valves
unless those are specifically designed for it. Typical gate valves are designed to be
fully opened or closed. There is very low frictional loss when the valve is fully open
due to negligible obstruction. Gate valves are present before and after every control
valve and pump which offers effortless maintenance during equipment failure.
Figure 26: Detailed diagram of a Gate Valve

http://www.spiraxsarco.com/images/resources/steam-engineering-tutorials/12/1/fig_12_1_1.gif
 Transmitters: These are sensors which monitor the changes in the process variables
and simultaneously send signals to the controller.

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They are named as FT (flow Transmitter), PT (Pressure Transmitter), TT (Temperature

Transmitter) and LT (Level Transmitter) respectively. They are Locally Mounted which
means that the controller and the display are located in the plant where the sensing
instrument is placed.
 Drain Valve: As the name suggests, these valves are used to drain the components
from the unit or pipelines. These are generally closed and are in operation usually
during site or unit maintenance.
 Relief Valve: The relief valve is a type of valve used to control or limit the pressure in a
system or vessel which can build up by a process upset, instrument or equipment
failure, or fire. The pressure is relieved by allowing the pressurised fluid to flow from
an auxiliary passage out of the system. Since the distillation Column taken into
consideration is operating under high pressures, a relief valve can act as a
precautionary measure which would help to get rid out the extra pressure built up
into the unit. It is built on the reflux drum, as building it over the column can lose its
components in the vapour phase that is released. As it is the last stage the purified
butadiene cannot be afforded to be wasted.
RV-1
 Pneumatic Lines: The signals transmitted from a controller to the valve are generally
shown by pneumatic lines on a P and ID.
 Electric Lines: The dotted lines show the transmission of electric signal in the P and ID.
The electric signal is send by the transmitter to the controller.

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 High and Low Level Alarms: Alarms alert the operators of serious and potentially
hazardous deviations in the process conditions. Key instruments are fitted with
switches. If there is a delay or lack of response by the operator a hazardous situation
can occur in a short span of time. Often drills are practiced to overcome such
catastrophic situations. When this system turns on, a trip system automatically comes
into action which includes, shutting down of pumps, closing valves, operating
emergency systems etc.
8.1 Control Loop

A chemical plant is composed of several processing units; these cannot be treated as simple
systems working independently. They are integrated to form a systematic, rational and
controlled process. This process must then satisfy many requirements in order to achieve its
objective of converting raw material to the desired products. Control systems are employed
to successfully satisfy the requirements of safety, product specifications, taking into account,
operational constraints, plant economics and environmental regulations. The control system
is composed of an arrangement of equipment such as temperature / pressure indicators,
pneumatic valves, process controllers linked with computers (CPU). The requirements of
control are stated below:[33]
Safety [33]
A principal prerequisite of the plant is to operate safely for the well being of plant
stakeholders and to continue satisfying the economic goal. To achieve this, temperature,
pressures, flow rates etc need to be controlled within allowable limits.
Operational Constraints [33]
Different process equipment have variable process constraints i.e. tanks should not overfill,
distillation columns should not be flooded and centrifugal pumps must maintain a certain net
positive suction head, these need to be considered when determining the control system.
Environmental Constraints [33]
Involves ensuring discharges are within acceptable limits e.g. as prescribed under IPC.

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Economics [33]
Plant operating conditions need to be controlled to ensure that the plant is operating at its
optimum, thus ensuring maximum profitability.
Although control is essential, it is known in industry that trying to tightly control absolutely
every stream in the process is very costly and unrealistic and can result in total inflexibility
and even destabilisation of the plant, (control loops may start to interfere with each other’s
actions). Similarly measurement sensors and control valves are expensive, so unnecessary
measurement is a loss of money. Therefore these factors will need to be taken into account
when deciding upon the control.
8.2 Control Systems over the Distillation Column:
Various control measures have been taken into account to meet the objectives of the plant
such as safety, operation, environmental constraints and economics. Sensors have been
installed at various process lines and equipments to make the operator aware of the
situation with the equipment and the process. The sensors transfer signals to the controller
which then send back commands to the respective valves to carry out the action.
Control system of the process will be explained as we go along the PID from left to
right.[34][35]
FC 1: the feed pipe is installed with a flow controller, which helps to control the flow
throughout the pipe. The flow rate is received as input to the FT-1, which then sends output
signals to the flow controller FC, which then sends on information to the automated control
valve CV-1. This ensures a steady state and control flow rate of feed to the distillation
column.
PC 1: The distillation column is operating under high pressures. The pressure is a very crucial
variable and has to be controlled to avoid flooding. The pressure is read by a pressure gauge
and this input is received by a PT1 which sends signal to the PC 1 which then forwards the
information to the control valve on the condenser. The condenser would reduce the flow
rate of water if the pressure drops; this intern increases the temperature of the distillate
entering the reflux drum as desired heat exchange was not possible; which increases the

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pressure back into the column. The reverse action is carried out if the pressure inside the
column increases. There is a relief valve on the reflux drum which also operates when the
pressure inside the column increases drastically.
LC 1: For desired separation to take place, it is important to maintain the ratio of the
distillate to the reflux Liquid. Hence it is vital to maintain the level in the reflux drum. The
level is read by a level indicator which sends the information to the LT 1 which further
forwards the signal to the control valve on the pipe back to the condenser. If the level in the
drum falls, the controller sends signal to close the valve which results in maintaining the level
in the drum.
TC 1 and FC 2: The temperature should be well maintained inside the column to provide
vaporisation of the volatile fluids for desired separation. Heat is provided by the steam flow
in the reboiler. Hence a controller valve is installed on the pipe which carries steam to the
reboiler. This controller receives signal from the flow transmitter (FT2) or the temperature
transmitter (TT1). If the temperature inside the column reduces, the controller sends signal
to the control valve to open slightly. This increases the flow rate of steam into the reboiler
increasing the temperature of the column.
LC 2: Flooding is a problem commonly faced by distillation columns if the design is poor.

Sometimes blockage in the support systems inside the column can cause obstruction to the
passage of the liquid and the gases. This can increase the level in the column resulting in
spillage of the valuable product. A level controller is installed in the pipe leaving the column
at the bottom. This control valve receives signals from the level controller which gets its
input from the level transmitter. If the level in the column falls down, the valve closes slightly
to maintain the level and prevent it from becoming dry. Also when the level falls down too
low or rises to high, the alarms blow up which would alert the operators to take serious
actions immediately like evacuating the plant or shutting all the valves and stopping the flow
rates.

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Indicators:
There are three main indicators used in the P and ID. These are mainly to provide
information of the operating conditions. There are two sample indicators SI (1-1) and SI (1-2),
which provide information about the purity of the fluids entering and leaving the column.
Since, the column’s top temperature is different from the bottom one, two temperature
indicators are required.
A combination of automated valves, flow and temperature indicators along with controllers
are used to control the process. Investment in these instruments and the control system is
required and is necessary. The control system along with the PID is then checked by senior
manager and engineers over a HAZOP meeting. Changes are made to the control and the PID
before the system is installed, in such a way money is saved and at the same time safety of
the operator is ensured.
Since Hazop was carried out on this section of the process, there were certain changes made
from the previously designed control loop system. Issue 001 in Appendix VI shows the draft
copy of the previously designed P and ID which was then improvised to Issue 002

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9.0 Hazard and Operability Studies HAZOP

HAZOP is a procedure for critical, systematic examination of the operability of a process.
Procedure of a Hazop involves taking a full description of a process, generally using a PID,
and systematically questioning every part of it. This helps to establish deviations from the
design intent. When the deviations are identified assessments are made on the
consequences of the deviation and the required action which should be taken to prevent or
control the hazard from taking place.
The analysis of Hazop is carried out in a structured way by following the guidlines attached; it
completely relies on the realising and imagination to discover the credible causes of the
deviations by the Hazop team. In practise many of the causes will be very obvious such as
pump failure. But putting a Hazop meeting encourages highlighting many causes which might
be obvious in first consideration. In this way the study is carried out and becomes more
rigorous and encourages the involvement of all the team members. The result of the Hazop
there is a good chance of identifying and recording relevant actions to be taken against
failures and problems which have not been experienced before. More over a documented
file of Hazop is required by legislation to confirm that preventive measures had been taken
to ensure the safe working condition of the operators and the environment.
In our study we carried out a Hazop with Dr. Titiloye on the Feed pipe entering the Propane
Distillation column. (As highlighted Green in Figure attached in Appendix VII). General
consequence of a Hazop leads to an updated version of the PID to be made after including all
the safety features discussed during the meeting. Hence the slight deviation in the final P and
ID (ISSUE no. 2) is due to Hazop done on the pipe.
In practise Hazop should be carried out over the whole process, but due to time constraints
and requirements of the project only one line of the process is looked at.
Hazop discussions have also been added, this includes all the causes and their consequences
looked at and also preventive actions have been highlighted. The Hazop is attached in
Appendix VII.

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10.0 Conclusion:
The design project has been successful in its aims of providing a detailed knowledge a
chemical process unit. This project was a learning process where different challenges were
faced. At this stage, such a project is aimed to increase general design knowledge of a given
operating unit in this case; a packed bed distillation column. As this was just a preliminary
design, the amount of detail of the design and the accuracy of the final calculations might be
questionable. However, it remains a fact that this project targets more than just design but
also gives an idea of how to make reasonable assumptions and where data is not available,
the use of values which can be used to make reasonable estimates. Overall the project
enhances one’s ability to play around with available data in order reach a reasonable
estimate.
After calculating all the values over my distillation column I conclude that one distillation
column can be used to separate propane and recover 1,3 butadiene. A stepped column can
be used as the diameter for the pentane distillation column, (the unit where the 1,3
butadiene is pumped to for further purification.) is 2 m as suggested my group mate. Since
the diameter for the propane distillation column is 0.65m the top part of the column can
have this diameter and the lower part of the column should have a diameter of 2m. This can
reduce the operating costs and also a significant amount of raw material to build the column
would be reduced.
Also a separator can be used instead of a distillation column, but the temperature has to be
reduced too low, to obtain such separation. This can be more expensive than providing high
pressure inside the column.

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11.0 References:
[1]: http://www.wakefield.gov.uk/NR/rdonlyres/F456AD74-5BC2-4697-9414-
55C32FCBE9E2/0/s1_13Butadiene.pdf,( (Part 1: Group Project on1,3 Butadiene Production)
accessed date 28/11/09
[2]: http://www.icis.com/v2/chemicals/9075172/butadiene/uses.html; accessed date

07/02/10
[3]: http://www.dow.com/productsafety/pdfs/butadiene_guide.pdf accessed date 15/03/10
[4]: http://www.gansu.gov.cn/en/BasicDetail.asp?CID=50 (Part 1: Group Project on1,3

Butadiene Production)
[5]: http://www.britannica.com/EBchecked/topic/166112/distillation-column; accessed date

13/02/10
[6]: http://www.websters-online-dictionary.org/re/reflux+ratio.html accessed date 13/02/10
[7]: http://www.separationprocesses.com/Distillation/DT_Chp04n.htm; accessed date

23/02/10
[8]: Dr. Bruce, 3rd year Chemical Engineering Advanced Separation Class Notes, Aston
University, 2010; Lecture 1
[9]: http://www.processglobe.com/Liquid_Specific_Heat.aspx; accessed date 24/02/10
[10]: Coulson J.M & Richardson J.F ‘’Chemical Engineering Design’’, 4th ed., vol. 6, Pergamon,
Oxford, 2005 page 567-569,
Oxford, 2005 page 579
*13+: Coulson J.M & Richardson J.F ‘’Chemical Engineering Design’’, 4th ed., vol. 6, Pergamon,
*14+ : Coulson J.M & Richardson J.F ‘’Chemical Engineering Design’’, 4th ed., vol. 6, Pergamon,
Oxford, 2005 page 588-593
[16]: Dr. Bruce, 3rd year Chemical Engineering Advanced Separation Class Notes, Aston
University, 2010; Lecture 3

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[17]: http://www.tower-packing.com/metal/metal_pall_ring_tower_packing.htm, accessed

date 29/02/10
Oxford, 2005 page 216 and 221
[21]: http://www.zehua-chem.com/
[24]: http://www.alibaba.com/showroom/condenser-tube.html; assessed on 26/02/10
[25]: Dr. John Brammer, 2nd Year Chemical Engineering Heat transfers Notes, Aston
University.
[26] : http://www.processglobe.com/Liquid_Specific_Heat.aspx
[30]: http://www.azom.com/Details.asp?ArticleID=863; accessed date 09/03/10
[31]:
http://www.documentation.emersonprocess.com/groups/public/documents/book/cvh99.pd
f ; accessed date 14/03/10
Oxford, 2005 page 197 -198
[33]: Dr. Fletcher, 2nd Year Chemical Engineering Control Process Notes, Aston University
*34+:Page S. Buckley, William L. Luyben and Joseph P. Shunta ‘’Design of Distillation Column
Control Systems’’

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[35]
:http://www.see.ed.ac.uk/~jwp/control06/controlcourse/restricted/course/fourth/course/m
odule3-1.html
[36]: Dr. Drahun, 2nd Year Chemical Engineering Advanced Design Process, Aston University.
[37]: Dr Brammer’s, 3rd Year Chemical Engineering Process Economics lecture notes, Section
C,
*38+: Dr Brammer’s, 3rd Year Chemical Engineering Process Economics lecture notes
[39]: (ref: www.informaworld.com/index/778741608.pdfl); accessed date 24/03/10
4(a)
4(b)
Graphs and Correlations:
Graph 1 : Coulson J.M & Richardson J.F ‘’Chemical Engineering Design’’, 4th ed., vol. 6,
Pergamon, Oxford, 2005 page 524
Grapgh 2: Coulson J.M & Richardson J.F ‘’Chemical Engineering Design’’, 4th ed., vol. 6,
Graph 3: Dr, Bruce Davies; 3 year Chemical Engineering advanced Separation notes; Lecture 3
Graph 4: Coulson J.M & Richardson J.F ‘’Chemical Engineering Design’’, 4th ed., vol. 6,

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CE 3003 Advanced Process Design – Individual Project

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8.1 Control Loop ............................................................................................................................... 72

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1.0 Project Brief:

1.1 Introduction to the product:

1, 3 Butadiene (CH2=CH-CH=CH2), is a colourless gas

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Figure 2: Chart Showing Various Uses of different forms of 1,3

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1.3 Location [4]

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Figure 4: Map of Gansu Province in China

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2.0 Project Plan and Objectives:

 Chemical engineering design to achieve the following outcomes is to be done

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2.2 Personal Objectives:

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 Get feedback on report/presentation and

2  Tutor meeting and discussing the topic.

3  Discuss findings with tutor

4  Calculating diameter and size of Distillation 08/02/10 19/02/10

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5  Piping and instrumentation diagram 1/03/09 10/03/10

6  HAZOP 10/03/10 19/03/10

7  Calculating cost and profit 01/03/10 15/03/10

8  Completing referencing 25/01/10 17/03/10

9  Ensuring completion of all section 20/03/10 21/03/10

10  Proof read 22/03/09 26/03/09

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3 The Revised Process:

Phillips OXO-Process [3]

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4 The Chemical Design:

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Figure 5: Basic Distillation Column

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Table 1 (b): Distillate:

Table 1 (c): Bottom:

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4.1.1 Reflux ratio and the number of Theoretical Stages

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Light Key: Most Volatile component in the Bottom Product

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Table (b); Distillate and Bottoms

Therefore new key components are:

Using the UNDERWOOD EQUATION:

Where q ≠ 1 as the feed is cold liquid @ 35°C.

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Calculation of feed condition q[9]:

Table 4: Latent Heat of the Components inside the Column [9]

Table 5: Specific Heat of the Components inside the Column [9]