Hydrogen sulfide (H2S) is a colourless, flammable, and extremely toxic gas commonly found in oil and gas systems. Its presence poses significant risks to workers, equipment, and the environment, and requires strict attention to ensure safe operations. Owners are challenged with choosing the most appropriate H2S recovery solution for their facility, their employees, and the environmental requirements of their location. Part of that decision revolves around what is being treated and the quantity of H2S present in that stream.
Of all the H2S recovery options available, liquid redox systems have emerged as the predominant solution for H2S removal for treatment of gas streams containing 1.5 tpd up to 20 tpd of sulfur removed. LO-CAT® is a liquid redox system that uses a chelated iron solution to convert H2S to innocuous, elemental sulfur. It does not use any toxic chemicals and does not produce any hazardous waste byproducts. Its environmentally safe catalyst is continuously regenerated, so operating costs are low, and its aqueous-based ambient temperature process applies to any gas stream. The technology's design has a small carbon footprint yet achieves more than 99.9% removal efficiency. There are no liquid waste streams, so there is no requirement for liquid treatment and disposal. Its unique design also allows for 100% turndown in gas flow. OPEX for LO-CAT systems is extremely low, which makes it an excellent solution for long-term operations with higher flow rates and H2S quantities.
Solid scavengers, also known as adsorbents, are an efficient and widely used method for H2S removal in oil and gas operations and are an excellent option for treating lower levels of H2S (below 1.5 tpd of sulfur removed). When choosing an adsorbent, one should take into consideration the target contaminant and its concentration, operating conditions such as temperature and pressure, the desired removal efficiency, regeneration or replacement needs, cost, environmental impact, and the physical properties of the adsorbent material, including surface area, pore size, and chemical reactivity.
Maintenance is also a consideration when choosing an adsorbent. Maintenance of adsorbent systems includes periodic replacement of spent media. Challenges occur when that media cakes or becomes hard leading to higher pressure drops at end of run (EOR) of the bed, channeling through the bed and potential difficulty in replacing the media. Caking can lead to large chunks or layers of concrete-like hardened material that requires jackhammering or hydro-blasting to chisel it away, which makes spent adsorbent changeouts tedious and potentially dangerous as well as taking significantly longer and costing more money.
SULFURTRAP® EX is a solid adsorbent with proprietary chemistry and manufacturing techniques that allows it the ability to efficiently decrease the H2S content to <1 ppm with a continuous low-pressure drop (SOR to EOR), loading 2 - 3 times more sulfur than conventional products while keeping the cost of the media low and being significantly easier and safer to change out.
Fewer and easier changeouts on an annual basis result in lower OPEX costs which are easily achievable with the right adsorbent. SULFURTRAP EX can be used to remove H2S from gaseous and light liquid hydrocarbons and can also remove low levels of oxygen and light mercaptans, if present, which further eliminates the corrosive nature of the hydrocarbon.
Owners have a range of H2S mitigation techniques from which to choose. Selecting the most appropriate solution involves several factors including flow rates, H2S quantity, space, capital and operating expenses (CAPEX / OPEX), as well as other considerations. There are multiple possibilities in the marketplace, but choosing the right option or technology is key to a sustainable, environmentally friendly and safe solution to a potentially toxic issue.
Written by Merichem Technologies. Click here to learn more.
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