GTC Technology, in alliance with CrystaTech, is supporting projects utilizing CrystaSulf® technology, a nonaqueous process that has been developed specifically for the treatment of high-pressure sour natural gas in medium-sized sulfur applications with produced sulfur in the range of 0.1 to 30 tons per day.

 

CrystaSulf® uses a nonaqueous solution with a high solubility for elemental sulfur. Because the elemental sulfur stays dissolved in the solution, there are no solids in the liquid circulated to the absorber. By design, CrystaSulf® avoids the problems that make the aqueous sulfur recovery systems unsuitable for direct treatment of high-pressure sour gas.

 

With this process, H₂S is removed from the sour gas in a conventional tray absorber. The H₂S reacts with dissolved sulfur dioxide (SO₂) to produce dissolved elemental sulfur. There are no solids in the absorber, flash tank, or solution lines, which minimizes the chance of plugging. Rich solution from the absorber passes to a flash step. The flash gas may be compressed and recycled to the inlet stream. After the flash step, the solution flows to a crystallizer where the temperature is lowered and solid elemental sulfur crystals form. The crystallizer/filter area is the only location where sulfur solids exist within the process. The lean liquid overflows from the slurry tank to a surge tank and a pump transfers the solution back to the absorber.

 

SO₂ can be added in two different ways. Liquid SO₂ can be purchased and metered into the lean solution line; this option is economical when SO₂ is readily available for purchase and sulfur throughputs are small. Alternatively, a portion of the product sulfur can be burned with the resulting SO₂ absorbed into the solution via a separate, small SO₂ absorber.

 

In this process, SO₂ binds chemically with species in the nonaqueous solution. This bond is strong and there is generally no detectable concentration of SO₂ in the gas phase anywhere within the system, including the sweetened gas. A large excess of SO₂ can exist within the solution, and this background concentration creates a buffering effect, providing operational flexibility. The CrystaSulf process offers the inherent capital cost benefit of a one-step approach while avoiding the operating problems of the aqueous-based processes. CrystaSulf® has been proven to be beneficial to operators who have stranded natural gas due to its H₂S content, or who are drilling gas wells in areas that tend to produce sour gas containing significant amounts of CO₂.
 

 

Process Advantages

• The solution dissolves elemental sulfur, so there are no solids present (except in the crystallizer/filter section)
• The solution does not foam because there are no surfactants or particles present
• Circulation rates are low as there is complete H₂S removal, eliminating the need for tail gas treating
• Solution is non-corrosive

 

Please contact us to learn more about the hydrogen sulfide removal technology.