Refrigeration systems process flow

Jotile-Thomson Valves The principal function of a J-T valve is to obtain isenthalpic coohng of the gas flowing through the valve. These valves generally are needle-type valves modified for cryogenic operation. They are an important component in most refrigeration systems, particularly in the last stage of the liquefac tion process. Joule-Thomson valves also offer an attractive alternative to turboexpanders for small-scale gas-recovery applications. 

Figure 11-18. Lithium bromide absorption refrigeration system concept water is the refrigerant. Actual commercial and industrial process flows reflect various heat recovery arrangements.

Deformable bodies, flow past, 11 775-777 Deformation, defined, 21 702 Deformation maps, 13 479-480 Deformation processing, of metal-matrix composites, 16 169-171 Deformation strain, 13 473 Defrost controllers, in refrigeration systems, 21 540... 

Now that the evaporator is cooler, we could increase the flow of warm process fluid to the evaporator. Thus, improving the efficiency of the condenser will increase the capacity of a refrigeration system to cool. This happens mainly by lowering the compressor discharge pressure rather than producing a colder condensed refrigerant. 

Flow Sheet and Mass Balances. Figure 2 represents a flow sheet of the 15,000-gallon-per-day pilot plant. The four major components are the freezer, the wash-separation column, the ice melter, and the vapor-handling device. The other essential components are the deaerator, which removes air from the saline water before it enters into the evacuated freezer the auxiliary refrigeration system, which removes heat leakage into the system and thermal inefficiencies of the process an ice scraper, pumps, controls, and instruments. 

Figure 7.7 Simplified process flow diagram for a refrigeration unit (inhibitor regenerator system not shown.

The most widely used is ammonia absorption in water. A flow-sketch of the process is in Figure 8.27. Liquid ammonia at a high pressure is obtained overhead in a stripper, and then is expanded through a valve and becomes the low temperature vapor-liquid mixture that functions as the refrigerant. The low pressure vapor is absorbed in weak liquor from the bottom of the stripper. Energy input to the refrigeration system is primarily that of the steam to the stripper reboiler and a minor amount of power to the pump and the cooling water circulation. 

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). 

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. 

Figure 11.29 shows a liquefaction unit. As with chlorine compressors, the refrigeration systems associated with liquefaction can be supplied as completely automated packages. Within their capacity, they will automatically adjust to the amount of chlorine fed to the system. The chlorine separator temperature is used to adjust the refrigerant evaporation pressure (and therefore, its temperature). With control by PLC, the only other signals to be passed to the main control center are the alarms and the shutdown status. Refrigerant flow is balanced with process demand by control of its level in the liquefier. 

---