Maximizing LPG Recovery from Fuel Gas Using a Dividing Wall Column
Over the last several years, refiners have faced increasing challenges maximizing the recovery of high valued products from process off-gases that are either used as fuel gas or flared. These off-gases used as fuel gases hold a high composition of valuable C3, C4 components. With refiners facing increased pressure to remain profitable, there has been a high focus on maximizing recovery of LPG range material from the fuel gases.
In a refinery, fuel gases are produced from various units such as fluid catalytic crackers, catalytic reformers, hydrotreaters, coker units, crude units, etc. A typical configuration of fuel gas producing units in a refining complex is shown in Fig. 1. There are many processes available for LPG recovery (either through cryogenic or absorption systems) of which some are licensed and others are available in the public domain. However with all these conventional technologies available, there are major challenges in maximizing the recovery (over 95wt %) of an LPG range material while at the same time being highly energy efficient.
To cover this engineering gap, a new solution has been developed that maximizes LPG recovery and lowers energy consumption. Following are in-depth details of this process with a case study highlighting the analysis of an existing refinery’s LPG recovery scheme and the application of this advanced solution for best process performance and higher ROI. These results help in understanding the best way to optimize operations and maximize LPG recovery from fuel gases. A key element in this study is dividing wall column (DWC) selection to overcome some of the challenges commonly associated with processing fuel gas and recovering higher LPG product economically way using traditional methods. Table 1 shows basic process advantages and a simple payback period for implementing the DWC system.