IMPROVEMENT OF HIGH HEATING VALUE OF COMMERCIALISED LIQUEFIED NATURAL GAZ OF GL1Z PLANT BY OPTIMISING THE LPG EXTRACTION AMELIORATION DU POUVOIR CALORIFIQUE SUPERIEUR DU GAZ NATUREL LIQUEFIE DU COMPLEXE GL1Z EN OPTIMISANT LA RECUPERATION DES GPL

摘要

During recent years, the quality of the feed natural gas to the liquefied natural gas plant GL1Z has become leaner in heavy hydrocarbons. Leaner feed gas makes it increasingly difficult to obtain the required propane and butane to be recycled to the scrub tower. This has led to long start up times to stabilise the scrub tower operation and sometimes causes certain instabilities even during normal operation. To overcome these problems, a LPG recovery heat exchanger, using multi-component refrigerant as a cooling medium has been installed in the scrub tower overhead circuit. With the addition of this exchanger downstream of the scrub tower condenser, LPG recycle to the scrub tower is not required to achieve the scrub tower overheads specification. However, a decrease of the high heating value of the commercialised LNG, and an overload of the fractionation unit have been experienced. As a solution, the initial operating temperature of the LPG recovery heat exchanger has been increased, in order to improve the high heating value of the commercialised LNG product. The objective of this paper is to share, with the LNG 14 Conference participants, the GL1Z plant experience in operating the LPG recovery heat exchanger, hoping that this may be beneficial for similar LNG plants modifications elsewhere.