Chiller, refrigeration process

Chiller Cools process stream by refrigerant at temperature lower than prevailing water, can be chilled by water cooling the process fluid or by refrigerant such as ammonia, propylene, and freon. (Also see Evaporator. )... 

Hot water or steam can also be used in absorption-type chillers to provide chilled water with the reduction in electrical power needed for the refrigeration process. 

Many pulp and paper facilities operate industrial process refrigeration units such as chillers for chlorine dioxide plants. For those units that utilize ozone-depleting chemicals, such as chlorofluo-rocarbons (CFCs), facilities are required under Title VI to follow leak repair requirements. 

Refrigerant circulation or kettle level (possible inadequate flow resulting in superheating of refrigerant). 4. Process overload of refrigerant system. or Chiller 2. Expansion valve capacity. 3. Chiller or economizer level control malfunction. 4. Restriction in refrigerant flow (hydrates or ice). 

Process water from most lakes, rivers, or wells is suitable for equipment condensers and is usually much cheaper than municipal water. In areas where water cost is high or conservation is required, condenser water may be recycled through water cooling towers or refrigeration chillers. Condenser water cost may be reduced also by re-using condenser effluent water as follows, in (1) plating operations, (2) spray paint water curtain systems, (3) heat treating quench towers, and (4) numerous other industrial secondary uses. 

Problem 6.31 The process shown in Figure 6-iq is part of a chiller unit that uses water as the refrigerant. The following data are available stream 1 is a vapor-liquid mixture at 0.5 bar stream 5 is saturated vapor at 5 C stream 6 is at 500 C stream 7 is at 100 C. Calculate the following on the basis of 1 kg/s of water in stream 1 ... 

In a suction chiller, chlorine returned from liquefaction boils at compressor suction pressure. Since this pressure is usually close to atmospheric, chlorine will boil at about —34 C, where its heat of vaporization is 288 kJ kg . Returning 15% of the net throughput to the suction chiller can cool the gas to —30°C or lower and allow the compression ratio in the first stage to be increased by about 58%. This technique increases the flow of chlorine through the compressor by the amount of liquid vaporized. In cooling the gas, it removes no heat from the process. The heat load ultimately is transferred to the refrigeration system in liquefaction. 

The process temperature is measured in the uncondensed gas as it leaves the chlorine knockout pot or separator. This procedure is more accurate than measurement of the temperature of the liquefied chlorine, which may be subcooled. The tenqierature sensor in Fig. 11.29 is an RTD in a flanged Monel thermowell. The reverse-acting proportional-plus-integral controller adjusts the set point of the refrigeration chiller pressure controller. 

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