Refrigeration system for a natural gas liquefaction process

摘要

Provided is an improved refrigeration system for pre-cooling natural gas or cooling a mixed refrigerant for natural gas liquefaction in a propane refrigeration process widely used for the liquefaction of natural gas. The system comprises a plurality of plate-fin heat exchangers preferably arranged in a parallel relationship for passing a propane refrigerant as a vertical flow and pre-cooling natural gas or cooling a mixed refrigerant for liquefying natural gas, and a thermo siphon drum for the propane refrigerant consisting of a horizontally disposed, laterally elongated tank. Because the passages of the heat exchanger for the natural gas or the mixed refrigerant extend over their entire length in mutually separate relationship, even when the propane refrigerant, the natural gas or the mixed refrigerant is in both gas and liquid phases, a high efficiency of heat transfer can be attained, and the size of the heat exchanger can be reduced. In particular, from an economic view point, it is preferable if the thermo siphon drum serves also as a flash tank.