Configurations and methods for gasification plants

Abstract

A syngas treatment plant has a decarbonization section and a desulfurization section that use the same solvent to remove various acid gases. Contemplated methods and plants are highly effective in removal of CO2, recycle sulfurous contaminants to extinction. Minimal loss of H2 while maximizing H2S concentration in a Claus plant feed during regeneration of the solvent is achieved by stripping the solvent with both treated syngas and a flash vapor of the desulfurization section.

Description

[0001]This application claims priority to our copending U.S. provisional application with the Ser. No. 61 / 417975, which was filed Nov. 30, 2010.FIELD OF THE INVENTION[0002]The field of the invention is syngas processing, and especially hydrogen (H2) and carbon dioxide (CO2) production with concurrent removal of carbonyl sulfide (COS) and / or hydrogen sulfide (H2S).BACKGROUND OF THE INVENTION[0003]With today's increasing natural gas prices, gasification route of low value feedstocks to produce ammonia / urea fertilizer or electric power is becoming an economically attractive option. However, shifted syngas from coal or coke gasification typically contains over 40 mol % CO2, which must be removed to minimize carbon emissions. CO2 removal is typically performed with physical solvents as such solvents can be flash-regenerated and require less energy for their regeneration, particularly where high CO2 partial pressure syngas is treated.[0004]Absorption of acid gases is generally dependent u...

AI Technical Summary

Benefits of technology

The present invention is about methods and configurations for treating syngas to remove various acid gases, such as H2S, COS, and CO2, to create a fuel gas for power plants. The methods and plants should capture over 95 mol% carbon while recycling sulfurous contaminants to extinction. In especially preferred methods and plants, the same solvent is used for acid gas removal, and the solvent is regenerated with minimal loss of H2 from the syngas.

Problems solved by technology

Unfortunately, co-absorption of CO2 with currently known physical solvent processes for removal of H2S is generally very high, particularly in treating shifted syngas gases.

The high CO2 content in the H2S-rich solvent therefore often produces a dilute H2S feed gas with a low heating value that is not suitable for a conventional sulfur plant.

In most cases, acid gas with less than 45 mol % H2S requires special equipment in the sulfur plant (e.g., supplemental fuel gas firing, acid gas preheating, and / or oxygen enrichment), which is frequently energy inefficient and costly.

However, such enrichment units will also produce an overhead gas that contains the sulfur contaminants that must be incinerated and the release of such incinerated effluent will create an emission problem.

While such plants provide certain advantages in gas treatment, one or more drawbacks nevertheless remain.

However, as such configurations and methods use a single regenerator, relatively high operating costs are encountered.

Moreover, such plants are also optimized for hydrocarbon recovery and are thus less suitable for syngas treatment.

Consequently, although many configurations and methods for H2S, COS, and CO2 removal from syngas are known in the art, all or almost all of them suffer from one or more disadvantages.

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