Process design refrigeration

Many compressors are designed and operated at a fixed condition in a process or refrigeration cycle. However, at least an equal number are designed and operated over a varying, or at the initial selection unknown, set of conditions of suction or discharge pressures. This situation is a reality and an economical necessity if the full horsepower of the compressor and driver combination is to be realized. 

LNG production involves cryogenic technologies that include concepts, refrigerants and process design. A state-of-the-art review of liquefaction concepts - especially on smaller scale - have been given. Cost level and relative pricing have been indicated in order to provide rough estimates. 

B. Walsh (1993) Mixed Refrigerant Process Design, Off. Proc. Comb. Conf, 6 Conf. AsiaPac. Confederation. Chemical Engineering, 1, 59/1-64/1... 

In the new revamp study (Alanis and Sinclair, 2002), a pinch analysis study considering both process changes and heat integration was conducted to identify process design changes that can reduce refrigerant compressor shaftwork. Pinch and... 

A low temperature of approach for the network reduces utihties but raises heat-transfer area requirements. Research has shown that for most of the pubhshed problems, utility costs are normally more important than annualized capital costs. For this reason, AI is chosen eady in the network design as part of the first tier of the solution. The temperature of approach, AI, for the network is not necessarily the same as the minimum temperature of approach, AT that should be used for individual exchangers. This difference is significant for industrial problems in which multiple shells may be necessary to exchange the heat requited for a given match (5). The economic choice for AT depends on whether the process environment is heater- or refrigeration-dependent and on the shape of the composite curves, ie, whether approximately parallel or severely pinched. In cmde-oil units, the range of AI is usually 10—20°C. By definition, AT A AT. The best relative value of these temperature differences depends on the particular problem under study. 

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