Triazines (Hexahydrotriazines) are one of the most used H2S scavenger chemistries in the North American oil and gas industry, specifically MEA triazines. The chemistry and application methods are well known due to over 2 decades of use, it has gained a commodity status and is thus a highly cost effective H2S treatment solution. Currently it offers one of the lowest cost per mass of H2S removed available in the market. There are however risks when using triazines, one being the formation of polymeric solids. This is mainly due to "overspending" the Triazine (over exposure of the dithiazine to H2S). The term "over spent" was commonly referred to the creation of Trithianes. Recent studies have shed more light on the triazine reaction pathways and provided a more realistic approached to solids formation.4
This paper will focus on the use of MEA triazines in static and dynamic systems, specifically co-current and counter-current flooded dynamic contact towers, and how solids form in them, what can be done to reduce or eliminate solids formation and design suggestions for systems that has far lower fouling risks. The solutions and suggestions discussed in this paper comes from field experience with these systems.
Liquid H2S Scavengers can be any liquid that physically or chemically remove H2S from liquids or gas. There are numerous liquid H2S scavengers currently being utilized in the North American oil and gas industry with MEA Triazines being the most popular for applications requiring < 2 tons of Sulfur removal per day and typical amine or Claus systems for >2 tons of Sulfur removal/day. In this paper focus will be placed on the non-oxidative and non-regenerative H2S scavenger MEA Triazine and its application in contact tower systems, specifically looking at solids (polymeric dithiazine) formation.
Some of the reasons why solids form in these systems will be discussed in this paper. To better understand the discussion, a brief overview of the most commonly used MEA Triazine contact tower configurations will be presented first. After looking at why and how the solids form, a solution section will follow providing advice and suggestions on how to eliminate or reduce the occurrence of solids.