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Hydrogen Sulfide Removal

 

Hydrogen sulfide is a chemical compound with the molecular formula H2S. H2S is a colorless toxic gas with an extreme rotten egg odor. Humans can normally detect the odor of the compound at 0.0047 ppm.  A single breath at 1000 ppm is lethal. The need to control or remove hydrogen sulfide to safe levels is necessary in all types of industries and applications, but is particularly necessary for the hydrocarbon processing industry. In addition to the safety concerns for plant personnel and operators, H2S removal is required for corrosion control due to the highly corrosive of the compound to pipelines, equipment and downstream processes.

Hydrogen sulfide removal processes can be classified according to level of sulfur removal per day (lbs of H2S per day). As a general rule, H2S removal up to 2,000 lbs per day should consider the use of an H2S scavenger type system.  A requirement that exceeds this general level of sulfur would consider other processes capable of handling larger quantities of sulfur.

Chemical Products' SULFURTRAP® would be categorized as an H2S scavenger. H2S Scavengers can be futher classified as either (1) liquid or (2) solid based. Both types are treatment options for low temperautre H2S removal from sour hydrocarbons. Liquid H2S scavengers have been commonly used for many years for low-pressure and low-sulfur gas wells. Today, liquid systems are being replaced by solid scavengers due to the advantages solid based systems present over their liquid H2S scavenger counterparts.

Liquid scavengers are typically supplied in drums, and work by pumping the scavenger liquid directly into the sour gas pipeline. When the liquid scavenger runs out, the empty drum must be replaced with fresh chemical. The primary disadvantage of liquid hydrogen sulfide removal chemicals is the high operating/treating cost. Operating costs (OPEX) can run as much as 10 times or more than fixed-bed scavengers. The reason the cost difference is so great is that H2S concentrations and gas flow rates fluctuate, but the liquid scavenger pump is pre-set to treat the maximum expected H2S concentration. When H2S levels drop, or flow rate decreases, the pump continues pumping the same amount of liquid. This overuse of chemical leads to much higher OPEX. Capital expenditures (CAPEX) for liquid systems are relatively low, while OPEX are high.

Conversely, solid hydrogen sulfide scavenger systems do require an initial investment for permanent or skid mounted equipment, but CAPEX can be recouped quickly as OPEX is much lower with solid systems. Solid H2S scavenger equipment is relatively simplistic in design and operation.

Solid hydrogen sulfide scavengers work by passing the sour gas stream through a fixed volume of scavenger in a vertical vessel. Solid scavengers can handle fluctuations in flow rate and H2S concentration with no change in performance or the need to “add” scavenger, thus drastically lowering operating costs.

Solid H2S scavenger systems are also capable of handling much larger volumes of H2S per day than liquid systems. Liquid scavenger can typically only treat up to 55 lbs H2S per day where solid scavenger systems, such as Chemical Products SULFURTRAP™ can economically handle up to 1 ton per day.

The choice may seem clear when comparing  liquid to solid H2S scavenger systems, but are all solid hydrogen sulfide removal systems alike?

They are not…

Many solid H2S scavenger offerings on the market only work in anaerobic, water saturated gas environments and can be extremely difficult to remove from the treating equipment.  Caking and agglomeration of these types of H2S scavengers can not only lead to an increase in pressure drop, but also pose a safety concern to operators and plant personnel. In these instances, potentially dangerous methods to loosen or break the used material out of the equipment must be used leading to a decrease in overall production and higher replacment costs.

A solution is finally available…

SULFURTRAP® by Chemical Products Industries, Inc. is the next generation in H2S scavenger technology. SULFURTRAP® easily removes H2S to <1 ppm, is capable of high sulfur loading capacity and is free-flowing in its used form. Finally,a product that performs as expected, and is both safe and easy to replace.

Call us today for assistance with the design of your next hydrogen sulfide removal project, or for information concerning the replacement of your current H2S scavenger system.