Enhanced Control Scheme_Rev0
Publication Date: 2016-Dec-19
The IP.com Prior Art Database
Publication shows a refrigeration-led control scheme for controlling the performance of a Main Cryogenic Heat Exchanger (MCHE) in a natural gas liquefaction process.
Figures 1-2 show a Refrigeration Led control scheme for controlling the performance of a Main Cryogenic Heat Exchanger (MCHE) in a propane precooled mixed refrigerant process that liquefies natural gas to produce liquefied natural gas (LNG). A mixed refrigerant typically comprises components such as methane, ethane, ethylene, propane, butane, and/or other hydrocarbons. The mixed refrigerant is typically split into a mixed refrigerant liquid (MRL) and a mixed refrigerant vapor (MRV). The MRL flow determines the available refrigeration, which in turn determines achievable LNG production. This control scheme converts the desired LNG production to a MRL flow set point. The scheme is also ratio-driven, such that the MRV and LNG flows are multiples of MRL flow and the ratios are trimmed to maintain a desired LNG temperature and a desired warm-end delta T (WEDT). The WEDT is calculated as the difference between the input and output refrigerant at the warm end of the MCHE and is indicative of the efficiency of the liquefaction process.
It is to be noted that the general concepts described and shown herein are applicable to any natural gas liquefaction cycle such as Single Mixed Refrigerant (SMR), Dual Mixed Refrigerant (DMR), Cascade, hybrid processes, Brayton refrigeration cycle, etc. The exchangers in the figures are shown to be coil-wound heat exchangers, however any type of heat exchanger such as plate and fin, shell and tube...