Refrigeration loop

Your home central air-conditioning system is a good example of a simple refrigeration loop. Figure 22.1 illustrates the basic components ... 

After purification, the natural gas stream is cooled successively by vaporization of propane, ethylene, and methane. Each of these gases, in turn, has been liquefied in a conventional refrigeration loop. Each refrigerant may be vaporized at two or three pressure levels to increase the natural gas cooling efficiency, but at a cost of considerably increased process complexity. 

Because the boiling model described above is fully explicit, it is rapid and easy to apply. It has been used with success in modelling steam drums and boiler recirculation loops, direct-contact feedwater heaters, high-pressure feedwater heaters, deaerator towers and vessels, condensers and refrigeration loops. The application of the boiling model to a steam drum and recirculation loop will be discussed in the next section because of its importance for the modelling of power stations. 

Most of the compression capacity is absorbed by the propylene cycle (80 to 90 per cent). This is because the initial condensation of the propylene ensures the operation of the cascade. For the demethanizer. Fig. 2.19 also shows the practical production of the reflux created by the vaporization of ethylene from the refrigeration loop. 

The refrigerant vapor from the evaporator is compressed to allow it to condense against cooling water. The refrigerant loop in Fig. 9.27 is a simplified version of the process explained in Section 9.1.7.1 and shown in Fig. 9.26. 

Containment of LiBr and maintenance of vacuum are essential. A small amount of air in the refrigeration loop can make the process inoperative. All components of the refrigeration loop may be mounted in one shell in order to reduce the potential for inleakage. 

An external multi-evaporation level compression chiller. Since heat has to be removed at temperature below the CO2 triple point, binary refrigerating loops propane/ethylene loops can be conveniently used. 

This process cools and liquefies gas using two refrigeration loops powered by gas turbine compressors propane (C3) for precooling, Mixed Refiigerant (MR) for liquefaction and subcooling. 

In the MR refrigeration loop, the high pressure MR is cooled against propane to approximately -35°C, and it partially liquefies. The stream is separated in the HP MR separator into MR liquid (MRL) and MR vapor (MRV). The MRL enters the MCHE, where it is subcooled. It is removed at an intermediate point of the MCHE, and sent to the MCHE shell side. The MRV enters the MCHE, where it liquefies and is subcooled. It exits at the LNG temperature and is returned to the shell side. The MRV and MRL boil on the shell side, which provides the refiigeration to liquefy and subcool the incoming natural gas and MR. 

The problems that occur with refinery refrigeration systems are much the same as those we have at home with air conditioners and refrigerators, the major difference being that at home we use freon as a refrigerant and in the refinery propane and butane are most often employed. The simplified refrigeration loop in Figure 10-1 shows the major components ... 

A conceptual breakthrough in one process can be adapted to other processes. If the freezer desalinator can be modified to operate without a refrigeration loop and a coolant, perhaps an air conditioner can be modified as well... 

The air warms in the adsorber because water vapor releases heat when it adsorbs. Of course, the desiccant would be recycled, for example, by heating to drive off the water. The coolant would be recycled through a refrigeration loop, such as the loop we developed for the desalination process. 

Repeat the process described in Problem 12 using a sinple refrigeration loop to determine the cost of providing 1 GJ of refrigeration at -50°C using the following working fluids ... 

Determine whether any of the working fluids given above cannot be used in a sinple (noncascaded) refrigeration loop. For these fluids, would using a cascaded refrigeration system to provide -50°C refrigerant make sense Explain carefully your answers to these questions. 

Figure C.4 Propylene Refrigeration Loop for Allyl Chloride Process (Unit 600)...

The design of a steam condensate collection system is a complex task. It cannot be approached just as a problem in hydraulics, because it is also a problem in vapor-liquid equilibrium and in the conversion of sensible heat to latent heat. Considering these three factors together requires quite complex calculations, for which I have had to rely on the use of a computer model. These same sorts of considerations apply to multicomponent hydrocarbon systems, such as propane-butane refrigeration loops, but then the calculation complexity increases by an order of magnitude. 

Running the compressor suction below atmospheric pressure is possible, but dangerous. Oxygen can be drawn into the refrigerant loop due to minor air leaks in the suction piping. To avoid this... 

---