Industries 2-Lecture 1

Chemical Industries Technologies (2)
Chapter 8:
Industrial Gases
Dr. Asma Eskhan
1
Chapter 8: Industrial Gases
Outline:
• Carbon dioxide
• Hydrogen
• Oxygen and Nitrogen
• Helium
• Acetylene
• Sulfur dioxide
• Carbon monoxide
• Nitrous oxide 2
Chapter 8: Industrial Gases
• The industrial gases are important for many specific uses.
• As a class they have already become among the most vital raw
materials for the chemical industry.
• Every day, new uses are being developed by aggressive

researchers and trained sales personnel of the manufacturing
companies.
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Chapter 8: Industrial Gases: Carbon Dioxide
• Carbon dioxide in liquid and solid forms has been known for over a century.
• Although Thilorier produced solid carbon dioxide in 1835 from the liquid material, it
was not until 1924 that the solid product gained industrial importance by its first and
still most important use for refrigeration.
• This industry has grown rapidly, and in 1953 there were 179,230 tons of liquid and
gaseous carbon dioxide and 554,109 tons of solid manufactured.
Uses:
• By far the largest use of the solid form is for refrigerating ice cream, meat, and other
foods. It has an added advantage in that a carbon dioxide atmosphere reduces meat
and food bacteria spoilage.
• The solid form is also important as a source of carbon dioxide for inert atmospheres
and occasionally for carbonated beverages. There are many other specialty uses such
as chilling aluminum rivets and shrink-fitting of machine parts. 4
• The largest outlet of liquid carbon dioxide is for carbonated beverages. It is also
important as a fire-extinguishing material.
• Gaseous carbon dioxide has many applications in the chemical industry such as in
the making of salicylic acid and as a raw material for soda ash
• Carbon dioxide has advantages over ordinary acids for neutralizing alkalies because:
1. it is easily shipped in solid form,
2. it is noncorrosive in nature,
3. It is light in weight.
• Chemically it is equivalent to more than twice its shipping weight in sulfuric acid or
about five times its weight in hydrochloric acid.
• In respect to food refrigeration, solid carbon dioxide is primarily a transport refrigerant.
Its advantages cannot be attributed to anyone single factor but result from its dryness,
its relatively high specific gravity, its excellent refrigerating effect, its low temperature,
and the insulating and desiccating action of the gas evolved. 5
Table 1. Comparison of physical properties of solid CO2, and water ice
6
• Generally, around 1,000 Ib. of solid carbon dioxide will refrigerate an average car for a
transcontinental rail trip without recharging. A similar load of water ice would require
3,700 Ib. initially plus several supplemental chargings along the way.
Manufacture of Pure CO2

• Although there are many sources of carbon dioxide, the following three are the most
important for commercial production:
1. Flue gases which result from burning carbonaceous material and contain about 10
to 18 percent carbon dioxide.
2. By-product from the fermentation industries through dextrose breakdown into
alcohol and carbon dioxide, the gas containing about 99 percent carbon dioxide.
3. By-product of limekiln operation where carbonates are calcined to the oxides, the
gases analyze from 10 to 40 percent CO2
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• An absorption system is used for concentrating the CO2 gas obtained in (1) and (3) to
over 99 percent.
• In all cases the almost pure carbon dioxide must be given various chemical
treatments for the removal of the minor impurities which contaminate the gas. One of
the reactions for the concentration of the carbon dioxide is,
• This reaction is forced to the right by increasing the partial pressure of the CO2 and by
reducing the temperature. It is forced to the left by heating up the sodium bicarbonate
solution.
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• The absorption efficiency of 18 percent CO2 is not very good as the quantities of Fig. 1
indicate. This absorption could be increased by use of another absorbing tower.
However, the CO2 available in this case comes from the combustion of carbon in a boiler
plant generating the required steam; it happens that the steam is the critical, expensive,
and controlling item.
• To carry out this manufacture, the principal unit operations (Op.) and unit processes
(Pr.) that are necessary are detailed in the following tabulation:
Coke or other carbonaceous fuel burned, giving heat for steam and economizer, and furnishing 18 percent
CO2 (Pr. and Op.).
Gas purified, cooled, and washed (Op.).
Gas reacted countercurrent forming NaHCO3 solution from CO2 and Na2CO2 solution (Pr.).
Concentrated (99.9 percent) CO2 boiled out of NaHCO3 solution (Pr. and Op.).
CO2 purified and dried (Pr.).
CO2 compressed, cooled, and liquefied (Op.).
For "Dry Ice":
Liquid CO2 subjected to reduction in pressure with consequent partial solidification (Op.). 9
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Recirculation, with recompression and recooling of evaporated CO2 (Op.).
CO2 "snow" compressed to solid cake (Op.).
Dry Ice cakes sawed to shape (Op.).
• A typical flow sheet, continuously producing either liquid or solid and embracing the
sequences of these unit operations and unit processes, is shown in Fig. 1.
• In the merchandising of liquid carbon dioxide: the energy (and hence expense) involved
in handling the cylinders, full and empty, is so great that this one fact has required the
installation of many relatively small plants economically located in consuming centers.
• However, bulk shipment of relatively low-pressure liquid cold carbon dioxide is now
being practiced to save container cost and weight.
• Where pure carbon dioxide from fermentation, for example, is not available, the practice,
largely conditioned by the energy balance, is to burn coke to furnish the necessary
energy and the carbon dioxide at the same time.
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Chemical Industries Technologies (2)

Dr. Asma Eskhan

• Every day, new uses are being developed by aggressive

Manufacture of Pure CO2

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