cooling tower

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GROUP ‘A’ TEAM MEMBERS:-:

GROUP ‘A’ TEAM MEMBERS :- Abdul Rehman Bilal Hassan Farhan Akhtar CE09-10M04 CE09-10M17 PG09-10M12

A PRESENTATION ON LABORATORY SCALE COOLING TOWER:

A PRESENTATION ON LABORATORY SCALE COOLING TOWER

Contents:

Contents Introduction Objective Theory Principles Mathematical equation Equipment classification Construction of equipment Procedure Calculations/Observations Applications & limitations Safety Result Discussion

COOLING TOWER:

COOLING TOWER INTRODUCTION :- In cooling tower air and water are brought into countercurrent contact which employ natural or mechanical draught. The water flows down over a series of wooden slats which give a large interfacial area and promote turbulence in the liquid. The air is humidified and heated as it rises, while the water is cooled.

OBJECTIVE:

OBJECTIVE To study the effect of air flow rate, water inlet temperature, and water flow rate on the Dry and Wet Bulb Temperature of air and Temperature of water along the height of the cooling tower using top cooling tower.

THEORY:

THEORY Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers are large diameter columns which special type of packing(structured packing)designed to give good gas liquid contact with low pressure drop.

WORKING PRINCIPLES:

WORKING PRINCIPLES Cooling towers are use the evaporation to remove process heat and cool the working fluid.Most common system is of air and water. When hot water is brought in contact with cold and unsaturated air part of liquid evaporates and the liquid temperature drops.

PowerPoint Presentation:

The heat transfer process involves:- 1) Latent heat transfer owing to the vaporization of a small portion of water. 2) Sensible heat transfer owing to the difference in temperature.

IMPORTANT POINTS ABOUT COOLING TOWER:

IMPORTANT POINTS ABOUT COOLING TOWER They are direct contact heat exchangers which use simultaneous heat and mass transfer operation(humidification)to cool working fluid. They can achieve water temperature below the temperature of air used to cool it. They are cheaper than other exchangers for same load.

EQUIPMENT CLASSIFICATION:

EQUIPMENT CLASSIFICATION There are two types of cooling towers:- Mechanical Draft Towers Forced Draft Induced Draft Natural Draft Towers

MECHANICAL DRAFT TOWER:

MECHANICAL DRAFT TOWER Mechanical draft towers are those which uses power driven fan motors to force or draw air through the tower.

NATURAL DRAFT TOWER:

NATURAL DRAFT TOWER Natural draft towers are those in which warm moist air naturally rises due to the density difference to the dry and cooler outside air.

Natural Draft Cooling Towers:

Natural Draft Cooling Towers Cross flow Air drawn across falling water Fill located outside tower Air drawn up through falling water Fill located inside tower

Induced draft tower:

Induced draft tower It is the mechanical draft tower with the fan at the discharge to pull air through it. the fan induces hot moist air out the discharge. This produces low entering and high exit air velocities, reducing the possibility of recirculation in which discharged air flows back into the air intake .

FORCED DRAFT TOWER:

FORCED DRAFT TOWER In the forced draft tower the fan is mounted at the base and the air is forced in at the bottom and discharged at low velocity through the to p.

CROSS FLOW/COUNTER FLOW DESIGN:

CROSS FLOW/COUNTER FLOW DESIGN Induced draft tower is further classified into counterflow and crossflow design. Cross flow design in which air flow is directed perpendicular to water flow. In counter flow the air flows opposite to water flow .

CROSS FLOW/COUNTER FLOW DESIGN:

Counter flow Cross flow CROSS FLOW/COUNTER FLOW DESIGN

CONSRTUCTION OF EQUIPMENT:

CONSRTUCTION OF EQUIPMENT It consist of:- Frame &casing Fill Cold water basin Drift eliminator Air inlet Louvers Nozzles Fan

SCHEMATIC DIAGRAM:

SCHEMATIC DIAGRAM LEGENDS: CT 1= BLOWE CT 2= STEAM INLET CT 3= WATER INLET CT 4= GLOBE VALVE CT 5= ROTA METER CT 6= HEATERS CT 7= COOLING TOWER CT 8= PHYCHROMETRIC GUN CT 9= STEAM OUTLET CT 10= WATER OUTLET

OBSERVATIONS:

OBSERVATIONS Room temperature: Dry bulb = Wet bulb = Cooling tower data: Max water flow = Max air flow = Overall height = Packed height = Width of rectangular section = Length of rectangular section = Type of packing = Material of packing = Max water basin level =

CALCULATIONS:

CALCULATIONS Sr.No HEIGHT (cm) AIR DRY BULB TEMP (0C) AIR WET BULB TEMP (0C) WATER TEMP (0C) WATER m3/h AIR m3/H 1 2 3 4 5 6

PROCEDURE :

PROCEDURE Draw and label the schematic diagram in the space provided above. Record the dry and wet bulb room temperature on the thermometers. Open the water flow regulating valve and adjust its flow rate. Start the air flow fan and adjust its flow rate at the minimum by closing the gate on the suction port. Now switch on one heater and wait to how much temperature rises at the inlet of cooling tower.If it is not at desired temp,start another heater.

CONTINUE…..:

CONTINUE….. Once the hot water inlet temp is established,adjust air flow at the minimum level and wait for steady state. At steady state,note down the temp of dry and wet bulb temp. Install wet and dry bulb thermometers on the psychometric gun,remove the caps at position 1 and insert the air suction probe there.Insert another thermometers for water temperatures in the port available at the same level.The gun should be positioned carefully to keep thermometers in the upright position. Once the experiment is completed remove thermometers and leaves the gun in one of the ports.

CONTINUE….:

CONTINUE…. Switch off heaters . Close water supply valve.Do not turn water off before the heaters. Turn the fan off. Clean the area.

APPLICATIONS :

APPLICATIONS Cooling the circulating water used in: Oil refineries Chemical plants Power stations Building cooling

LIMITATIONS:

LIMITATIONS Their ability to cool water is based on how much water is lost due to evaporation.The evaporation from a cooling tower is based on quality of air in surrounding area.If area has high humidity , less water will evaporate than in a dry climate.

SAFETY :

SAFETY Electrical switches wiring should not be damaged. Wet floor may cause an accident. Moving parts do not use loose cloths. Keep working area free of obstacles. Never switch on heaters before opening the water flow. Never close water supply before switching off the heaters.

Question & Answer Section:

Question & Answer Section