Optimization of Operating Parameters of a Nitrogen Liquefier Functioning as a Unit of a Liquid Methane Supercooling System

The problem of thermodynamic optimization of the operating parameters of a nitrogen liquefier functioning as a unit of a liquid methane supercooling system is identified and solved. Solution of this problem enabled determination of the following: the specific work required for liquefaction of 1 kg of nitrogen in schemes with oil- and water-filled compressors, characteristics of heat exchange equipment and expansion-compression unit, and operating parameters at all calculation points. It was found that waterfilled screw compressor helps reduce specific liquefaction work by 19%. Direct flow pressure of 1.2 MPa and throttle flow fraction of 0.14 are the optimum parameters for nitrogen liquefaction.