Mercury (Hg) in Natural Gas

Mercury in natural gas is often found at trace levels, predominantly in its elemental form, differing from crude oil. Concentrations can vary from 0.01 µg/Nm³ up to 5,000 µg/Nm³. According to ACGIH’s 2019 guidelines and OEHS, mercury is highly toxic with a threshold limit TWA of 0.025 mg/m³.

Mercury, a high vapor element, poses significant environmental hazards and serious corrosion problems. It reacts with aluminum to form amalgams, quickly producing alumina, elemental Hg, and hydrogen, which can damage equipment and cause embrittlement and cracks within facilities. Mercury was the main cause of the catastrophic explosions at the Skikda LNG plant in Algeria in 1975 and the Moomba gas plant in Australia in 2004. 

The process of removing mercury from natural gas differs from that of flowing crude oil. The technology for mercury removal from natural gas has been commercialized for some time, with most applications based on either chemisorption or physisorption processes. In these processes, gas flows through a fixed bed of sorbent media containing reactive chemical species supported on inert materials.

Both non-regenerative and regenerative processes are commonly implemented, each with its own advantages and disadvantages based on operating mechanisms, complications, and the treatment process of contaminated equipment or parts.

Hekma Petroserv’s lead experts have designed a system utilizing nanofiltration technology, inline mixers, and other tools tailored to each gas specification. This system can be integrated within existing gas processing facilities with a minimal footprint, significantly reducing both Capex and Opex. Additionally, the easy handling of contaminated parts and their maintenance minimizes environmental and health hazards, promoting a sustainable economic process.