Hitachi, Ltd.

Shoichi Kimura

Toshihiko Takahashi

Zensuke Tamura

Morihisa Maruko

A reducing gas, such as a synthetic fuel gas, produced by gasification of a fossil fuel, containing ammonia or both ammonia and hydrogen sulfide, is purified by passing the reducing gas at first, through a first removing agent of iron or nickel system when the hydrogen sulfide is contained, and then through a second removing agent of iron or nickel system, both at elevated temperatures. For example, when the reducing gas contains both ammonia and hydrogen sulfide, the gas is passed through the first removing agent at a temperature of 450.degree.-700.degree. C. to remove substantially all of the hydrogen sulfide and then is passed through the second removing agent at a temperature of greater than 700.degree. C., preferably up to 900.degree. C., to remove substantially all of the ammonia contained in the gas. Not only a remarkable effect upon prevention of environmental pollution but also a great improvement of energy efficiency, as compared with the conventional process, can be obtained.

Process for removing harmful components from gas

A refining process of a hot gas such as coal gas containing hydrogen sulfide and ammonia comprises steps of contacting the hot gas with a first catalyst comprising iron oxide to remove hydrogen sulfide, and then contacting the hot gas with a second catalyst comprising reduced iron made by reducing iron oxide prior to introducing the hot gas into the catalyst to remove ammonia. The refining process further includes steps of temperature adjustment of the gas directing to the first and second catalyst and the removal of hydrogen sulfide remaining in the hot gas after the removal of the ammonia with a third catalyst comprising iron oxide.

Refining process of hot gas containing hydrogen sulfide and ammonia

A high temperature, high pressure raw coal gas containing hydrogen sulfide, ammonia, and tarry matter, is purified by contacting the raw coal gas with solid particles thereby cooling the raw coal gas to a temperature suitable for hydrogen sulfide removal and at the same time depositing the tarry matter onto the solid particles by condensation to recover the tarry matter from the raw coal gas, removing the hydrogen sulfide from the cooled and substantially tar-free coal gas, expanding the raw coal gas to a pressure suitable for ammonia decomposition, heating the expanded raw coal gas to a temperature suitable for ammonia decomposition by heat obtained by combusting the recovered tarry matter on the solid particles, thereby regenerating the solid particles for reuse, and then decomposing ammonia in the raw coal gas, thereby removing ammonia therefrom. A process for efficiently purifying raw coal gas by removing tarry matter, hydrogen sulfide and ammonia, including effectively utilizing the recovered tarry matter to produce heat while also effectively utilizing the energy obtained by expanding the coal gas through a pressure-reducing means such as an expansion turbine.

Process and apparatus for purifying raw coal gas

Hydrogen sulfide is removed from coal gas for gas turbine power generation and recovered as elemental sulfur by contacting a coal gas formed by gasification of coal with an iron oxide catalyst, thereby removing hydrogen sulfide from the coal gas and obtaining a desulfurized coal gas; regenerating the iron oxide catalyst of lowered desulfurization activity, thereby obtaining a regeneration off-gas containing sulfur dioxide; converting a portion of said desulfurized coal gas to reducing gas containing hydrogen; reacting the hydrogen of the resulting reducing gas with the sulfur dioxide in a portion of said regeneration off-gas, thereby producing hydrogen sulfide; reacting the resulting hydrogen sulfide with the sulfur dioxide in the remaining portion of the regeneration off-gas in the presence of a catalyst, thereby producing a gas containing elemental sulfur, and recovering the elemental sulfur from the gas.

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Kudamatsu, Japan

Shoichi Kimura