| 摘要 |
PURPOSE: To produce liquid nitrogen efficiently by cooling liquefied natural gas and compressing through multistage compression to a specified pressure, separating it to two sub-flows, cooling one sub-flow with liquefied natural gas and then compressing before expanding, cooling and condensing the other sub- flow with the expanded sub-flow and the liquefied natural gas and then producing a two-phase flow and separating it to gas and liquid. CONSTITUTION: Low pressure nitrogen 80 is cooled with LNG in a heat exchanger 92 and compressed to 300 psi by means of compressors 118, 126, 130, 134. The highest pressure nitrogen flow 136 is divided into sub-flows 138, 140 and the sub-flow 140 is passed through the heat exchanger 92, and expanders 142, and the heat exchanger 100, 102 and combined with flow from the compressors 118. The sub-flow 138 is cooled and condensed through the heat exchangers 92, 102, 100 and then expanded through an expander 152 to produce a two-phase flow 153 which is fed to a separator 154. The two-phase flow is separated to gas and liquid and liquid nitrogen 162 is fed to a phase separator 164 and subjected to phase separation. The separated vapor nitrogen 160 is combined with high pressure gas nitrogen 86. |
