Enhancing Propane Refrigerant Performance at Pre-Cooling Stage During Hot Climate Conditions at LNG Plants – Case Study from Egypt

As a result of the growth of LNG markets, the LNG production capacity of liquefaction trains is increasing continuously. This is true not only for new projects, but also for the debottlenecking of existing trains.
When the propane refrigerant is condensed through air coolers, limitation of the variation in atmospheric temperature plays a vital role in the efficiency of the condensing system as it will be affecting the Natural Gas temperature and vaporization rates. That will increase the load on the Propane Compressor and Air Coolers till the condensing rate of the refrigerant is affected. That will result in limiting the ability of the Plant to go for full load when Propane-MR refrigerants are used as the Technology for Natural Gas liquefaction.
This study took the challenge in studying a cost effective solution to maintain a high efficiency performance of the condensing system of the Propane Refrigerant in LNG Plant during hot climate conditions, Temperature range of 25ᵒC - 35ᵒC.
Two approaches were examined through this study which are:
1. Effect of passing the propane feed from the discharge of the compressor to the recycle cooler before the main propane condenser during hot climate conditions. (Two Stages Condensing System)
2. Effect of changing the propane composition on the performance of the refrigerant.
This study is based on SEGAS LNG Plant in Damietta, Egypt where a mixed component refrigerant is pre-cooled by another refrigerant made up of propane.
At the end of the study, the following results were obtained:
1. Full condensation of the Propane Refrigerant when utilizing the two stages condensing system over Hot Climate conditions.
2. Pure Propane refrigerant showed the least power consumption and lower Air condensing duty against other compositions tested.