Technological Institute of the Philippines

363 P.Casal St. Quaipo, Manila

CHE 502
UNIT OPERATIONS LABORATORY 2
MIDTERM PROJECT

Submitted by:
Ana Mariel P. Ventura

Submitted to:
Engr. Efren Chavez
Agitator

An agitator is a device or mechanism to put something into motion by shaking or stirring.

There are several types of agitation machines, including washing machine agitators (which rotate
back and forth) and magnetic agitators (which contain a magnetic bar rotating in a magnetic field).
Agitators can come in many sizes and varieties, depending on the application.
In general, agitators usually consist of an impeller and a shaft. An impeller is a rotor located
within a tube or conduit attached to the shaft. It helps enhance the pressure in order for the flow of
a fluid be done. Modern industrial agitators incorporate process control to maintain better control
over the mixing process.
Industrial agitators are machines used in industries that process products in the chemical, food,
pharmaceutical and cosmetic industries, in a view of :

 mixing liquids together

 promote the reactions of chemical substances
 keeping homogeneous liquid bulk during storage
 increase heat transfer (heating or cooling)

Principle of Agitation
The agitation is achieved by movement of the heterogeneous mass(liquid-solid phase),to
the impeller. This is due to mechanical agitators, to the rotation of an impeller. The bulk can be
composed of different substances and the aim of the operation is to blend it or to improve the
efficiency of a reaction by a better contact between reactive product. Or the bulk is already blended
and the aim of agitation is to increase a heat transfer or to maintain particles in suspension to avoid
any deposit.
Application
Chemical Plant & Engineering (CPE) designs and manufactures agitation equipment to suit
a range of agitation and mixing applications and industries. The agitators can be manufactured to
meet the stringent sanitary requirements of the dairy industry through to the arduous duties as
required in industrial and mineral processing applications.
Applications include:
 Food
 Dairy – sanitary standard
 Water and waste water
 Chemical
 Wine
 Mineral processing
 Numerous other industries which require gas dispersion, re-pulping, solids suspension and
a host of other specialties.
Drying

Drying is a mass transfer process consisting of the removal of water or another solvent by
evaporation from a solid, semi-solid or liquid. This process is often used as a final production step
before selling or packaging products. To be considered "dried", the final product must be solid, in
the form of a continuous sheet (e.g., paper), long pieces (e.g., wood), particles (e.g., cereal grains
or corn flakes) or powder (e.g., sand, salt, washing powder, milk powder). A source of heat and an
agent to remove the vapor produced by the process are often involved. In bioproducts like food,
grains, and pharmaceuticals like vaccines, the solvent to be removed is almost invariably water.
Desiccation may be synonymous with drying or considered an extreme form of drying.
In the most common case, a gas stream, e.g., air, applies the heat by convection and carries away
the vapor as humidity. Other possibilities are vacuum drying, where heat is supplied by conduction
or radiation (or microwaves), while the vapor thus produced is removed by the vacuum system.
Another indirect technique is drum drying (used, for instance, for manufacturing potato flakes),
where a heated surface is used to provide the energy, and aspirators draw the vapor outside the
room. In contrast, the mechanical extraction of the solvent, e.g., water, by filtration or
centrifugation, is not considered "drying" but rather "draining".
Drying Principle
Heated air drying and low-temperature drying (also referred to as near-ambient drying or in-store
dyring) employ two fundamentally different drying principles. Both have their own advantages
and disadvantages and are sometimes used in combination e.g., in two stage drying systems.
 Heated air drying employs high temperatures for rapid drying and the drying process is
terminated when the average moisture content (MC) reaches the desired final MC.
 In low-temperature drying the objective is to control the relative humidity (RH) rather than
the temperature of the drying air so that all grain layers in the deep bed reach equilibrium
moisture content (EMC).
Application
 Food

Foods are dried to inhibit microbial development and quality decay. However, the
extent of drying depends on product end-use. Cereals and oilseeds are dried after harvest
to the moisture content that allows microbial stability during storage. Vegetables are
blanched before drying to avoid rapid darkening, and drying is not only carried out to
inhibit microbial growth, but also to avoid browning during storage. Concerning dried
fruits, the reduction of moisture acts in combination with its acid and sugar contents to
provide protection against microbial growth. Products such as milk powder must be dried
to very low moisture contents in order to ensure flow ability and avoid caking. This
moisture is lower than that required to ensure inhibition to microbial development. Other
products as crackers are dried beyond the microbial growth threshold to confer a crispy
texture, which is liked by consumers.

 Non – food products

Among non-food products, some of those that require considerable drying
are wood (as part of timber processing), paper, flax, and washing powder. The first two,
owing to their organic origins, may develop mold if insufficiently dried. Another benefit
of drying is a reduction in volume and weight.

 Sludges and fecal materials from sanitation processes

In the area of sanitation, drying of sewage sludge from sewage treatment plants,
fecal sludge or feces collected in urine-diverting dry toilets (UDDT) is a common method
to achieve pathogen kill, as pathogens can only tolerate a certain dryness level. In addition,
drying is required as a process step if the excreta based materials are meant to be
incinerated.
Air Properties
Sling Psychrometer

There are 2 thermometers in this instrument.

1.Dry bulb thermometer, whose sensor bulb is in direct contact with air (mercury is the sensing
element)

2.Wet bulb thermometer: the sensor bulb of this thermometer is covered with a wick of cotton or
muslin moistened with pure water
A glass frame is provided as the housing for the instrument.

A rotating handle is attached to the glass frame housing – the arrangement of the thermometer to
ensure that the air in the wet bulb always in immediate contact with the wet wick.

When a thermometer bulb is directly exposed to a mixture of air-water vapor, the temperature
indicated by the thermometer is the dry bulb temperature.

When the bulb of a thermometer is covered by a constantly wet wick and if the bulb covered by
the wet wick is exposed to the mixture of air vapor and water, the temperature indicated by the
thermometer is the temperature of the wet bulb.

Operation of Sling Psychrometer.

In order to measure the dry bulb and the temperature of the wet bulb, the disposition of the
thermometer of the psychrometer- glass cover – is rotated from 5 m / s to 10 m / s to obtain the
necessary air movement.

Note: An important condition is that the correct / accurate measurement of the wet bulb
temperature is obtained only if the air moves with the speed around the wet wick. To get this air
velocity, the psychrometer is spinning.

The thermometer whose bulb is empty contacts the air indicates the temperature of the dry bulb.
 At the same time, the thermometer whose bulb is covered with the wet wick comes in contact with
the air and when this passes the wet wick present in the thermometer bulb, the moisture present in
the wick begins to evaporate and a cooling effect occurs produced in bulb. Now the temperature
indicated by the thermometer is the wet bulb thermometer that will naturally be lower than the
temperature of the dry bulb.

Application of Sling Psychrometer

1. It is used for checking humidity level in air-conditioned rooms and installations.

2. It is used to set and check hair hygrometer.
3. It is used in the measurement range of 0 to 100% RH.
4. It is used for measuring wet bulb temperature between 0’C to 180’C.