Success Story of the Development of Extremely Low-BTU Flare Tip Technology

Abstract

Current low-BTU flare tip technologies require a flare gas lower heating value (LHV) of approximately 200 BTU/scf while significant advancement on CO2 removal membrane technology has resulted in an extremely low-BTU waste gases having LHVs around 140 BTU/scf. This requires the extremely lean waste gas to be supplemented with methane to raise its heating value to achieve stable combustion. Not only does the operator lose the benefit of the advanced membrane technology but they also lose product (sellable gas) and have increased green house gas (GHG) emissions at the production site. Consequently, the development of the "Extremely Low-BTU Flare Tip" is beneficial in multiple ways. The Extremely Low-BTU Flare Tip development project was launched as a joint research and development project between PTTEP and John Zink Hamworthy Combustion (JZHC). The innovative design is based on theories behind low heating value gas combustion and improves upon existing low-BTU flare technology. The goal was to obtain flame stability and safe operation in offshore oil and gas production environments at LHVs significantly lower than 200 BTU/scf. This project included multiple iterations of prototype design, simulation, and testing, with various parameter adjustments to optimize the performance against completeness of combustion criteria. The design was studied through computational fluid dynamics (CFD) simulation and prototype testing to develop the operating envelope of the Extremely Low-BTU Flare Tip. The design of the tip integrates John Zink's existing technology with additional components i.e. spokes and top hat. CFD simulation was performed to observe the fluid behaviors, including temperature, velocity, and unburned hydrocarbon; allowing modification of the design prior to the fabrication of the prototype. The final design has been proven by a series of prototype tests to reinforce the level of confidence in its performance and mechanical integrity. The test results show that the Extremely Low BTU Flare Tip has the capability to combust flare gases with an LHV as low as 110 Btu/scf which is a significant improvement over existing flare tip technology. The benefit of this technology is estimated to be between 10-31 MMUSD per year per platform, depending on the lowest achieved heating value. The success of the Extremely Low BTU flare tip development project provides a breakthrough technology which is not limited to brownfield applications but also supports future acquisition and development of Greenfield sites. This Extremely Low BTU flare tip technology will improve the probability of success for greenfield development with a high CO2 reservoir by maximizing reservoir recovery, optimizing overall capital and operational expenditure, and minimizing hydrocarbons flared which has the direct effect of increasing gas sales and decreasing greenhouse gas emissions.