Comparison of Multistage Compression Configurations for Single Mixed Refrigerant Processes

Abstract

This study investigates the effects of multistage compression on single mixed refrigerant processes in terms of specific work. Comparison of specific work published in the literature is not straightforward due to the variety of compression configurations and the design bases. Therefore, four configurations (two-, three-, and four-stage and pump-added three-stage compressions) along with three natural gas compositions were considered. To compare with the simulation and optimization results in the literature, these 12 cases, having the same design basis, were optimized by adjusting the optimization variables such as the flow rate and composition of the refrigerant, the compression ratio of each compressor, the inlet pressure of the first compressor, and the outlet temperatures of the hot and cold refrigerant streams. There were two important findings: (1) adding a pump reduces specific work more than adding a compressor or decreasing the minimum temperature difference value in the compressors; (2) among the four configurations, the refrigerant composition does not significantly change, although it greatly affects the efficiency. The former results from the compressor constraint of the gaseous inlet and the latter from the minimum temperature constraint of the multistream heat exchanger. Furthermore, direct comparisons to other studies were also performed showing the importance of optimization and the effect of the design basis.

A Critical Analysis of Natural Gas Liquefaction Technology

“…The characteristics of the mixed-refrigerant cycle (MRC) is that a multi-element mixture composed of C1 (methane) to C5 (pentane) hydrocarbons and nitrogen is adopted as the refrigerant. And the refrigeration method is throttling refrigeration [18,19].…”

Case Studies for SMR Natural Gas Liquefaction Plant by Capacity in Small Scale Gas Wells through Cost Analysis

“…다양한 천연가스 액화공정 중 가장 간단한 형태의 SMR (single mixed refrigerant) 공정은 하나의 혼합냉 매(mixed refrigerant, MR) 사이클을 통해 천연가스를 냉각시킨다 [6]. SMR 공정은 구조가 단순하기 때문에 소용량, 즉 3 MTPA (millon ton per annum)용량 이하 의 공정에서 사용된다 [7].…”

MINLP Model for Operational Optimization of LNG Terminals

“…For example, Rao et al used the Nonlinear Optimization by Mesh Adaptive Direct Search (NOMAD) algorithm to prove that the two-stage recondensation is superior to other structures [30]. Tak et al investigated the influences of multi-stage compression on single-mixed refrigerant processes [31]. Yuan et al analyzed the parameters in four types of BOG recondensation systems.…”