(71i) Dynamic simulation of discharge process safety and optimization for multi-stage ground flare

Ground flares have attracted more and more attention for petrochemical plants and oil & gas fields in China because of its high efficiency, flame invisibility and low heat radiation, especially for the intense land resource area. Multi-stage discharge system is a remarkable feature for ground flare, through which the stages could open or close according to the discharge amount and the high efficiency could be realized. Therefore, it’s an important issue to determine that number of stages and the treatment capacity of each stage. If this issue could not be solved properly, many problems may occur, such as frequency open/close action of stage valves, inefficiency of the combustors, and the high backpressure of related facility.

In order to solve this problem, the dynamic simulation model was established including the main pipeline, water seal tank, arrestor, and eight stages with the combustors based on a real ground flare for a lubricating oil hydrogenation unit. The pressure drop through the whole pipe network was analyzed. The main pipeline pressure, treatment amount of each stage/combustor was calculated. Meanwhile, the action of stage valves were tracked.

Results shows that the multi-stage discharge system is complicated and could be impacted by stage pressure setting and combustors’ number of each stage. The dynamic model could help to the proper design of such kind of system.

Keyword: Ground flare; multi-stage; dynamic simulation; pressure drop.