TITLE:
Gas Flare Design Debottlenecking Using Pinch Analysis
AUTHORS:
Lawrence Leelabari Pemii, Kenneth Kekpugile Dagde, ThankGod Oweifa Goodhead
KEYWORDS:
Gas Flaring, Pinch Analysis, Debottlenecking, Aspen FlareNet, Optimization, Header Pipe, Tail Pipe
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.10 No.4,
September
4,
2020
ABSTRACT: Gas flaring is concerned with the combustion of lighter ends of
hydrocarbon mostly produced in association with crude oil. Flare networks are
designed to handle the gas volume required to be flared. Most times, this flare
networks are in close proximity but still have independent flare stacks, increasing
risk to environment and cost on infrastructures. There is a need to integrate
the flare networks in facilities within same area and through the application
of Pinch Analysis concept, the resultant flare network can be optimized to give
a system having optimal tail and header pipe sizes that will reduce cost and
impact on environment. In the light of the
foregoing, the concept of pinch analysis
was used in debottlenecking integrated gas flare networks from a flow
station and a refinery in close proximity. Both flare networks were integrated
and the resultant gas flare network was optimized to obtain the optimum pipe
header and tail pipe sizes with the capacity to withstand the inventory from
both facilities and satisfy the set constraints such as Mach number, noise,
RhoV2 and backpressure. Mach number was set at 0.7 for tail pipes
and 0.5 for header pipes, noise limit was not to exceed 80 dB upstream and 115 dB
downstream the sources, RhoV2 was limited to 6000 kg/m/s2 and the back pressure requirement was source
dependent respectively. The fire case scenario was considered, as it is the
worst-case scenario in the studies. When pinch analysis was applied in
debottlenecking the combined gas flare network, it gave smaller tail and header pipe sizes which is more economical. A 20%
decrease in pipe sizes was recorded at the end of the study.