Gasification furnace operating method and gasification furnace

1 . A method for operating a gasification furnace in which an organic raw material is charged to form gas and slag, comprising charging an alkali metal-containing compound directly or indirectly into the gasification furnace to reduce the viscosity of the slag, the method characterized by comprising:

analyzing the content of sodium and silicon of the slag,

determining, based on the analyzed content, a molar ratio of silicon dioxide and sodium oxide in the slag (the number of moles of silicon dioxide/the number of moles of sodium oxide); and

maintaining the molar ratio of silicon dioxide and sodium oxide in the slag to be 2.5 or more, by controlling charging of the alkali metal-containing compound based on the determined molar ratio, wherein the controlling comprises charging the alkali metal-containing compound when the molar ratio of silicon dioxide and sodium oxide in the slag is 2.5 or less,

wherein the alkali metal-containing compound is sodium silicate.

2 . The method according to claim 1 , wherein the sodium silicate is charged in the form of an aqueous solution.

3 . The method according to claim 1 , wherein the molar ratio of silicon dioxide and sodium oxide in the sodium silicate (the number of moles of silicon dioxide/the number of moles of sodium oxide) is 0.4 or more and 4.5 or less.

4 . The method according to claim 1 , comprising charging a silicon containing compound directly or indirectly to the gasification furnace.

5 . The method according to claim 4 , wherein the silicon containing compound is a bed material.

6 . The method according to claim 1 , wherein the molar ratio of silicon dioxide and sodium oxide (the number of moles of silicon dioxide/the number of moles of sodium oxide) in the slag having a reduced viscosity is 2.5 or more and 15.0 or less.

7 . The method according to claim 1 , wherein the slag having a reduced viscosity comprises an alkali metal in an amount of 1.5% by mass to 20.0% by mass in terms of oxide.

8 . The method according to claim 1 , comprising mixing the alkali metal-containing compound with the organic raw material, and charging the mixture into the gasification furnace.

9 . A method for two-stage gasifying organic waste, comprising forming an organic raw material by primary gasification of the organic waste in a low temperature gasification furnace, charging the organic raw material into a high temperature gasification furnace, forming gas and slag by secondary gasification of the organic raw material in the high temperature gasification furnace, and charging an alkali metal-containing compound directly or indirectly into the high temperature gasification furnace to reduce the viscosity of the slag, the method characterized by comprising:

analyzing the content of sodium and silicon of the slag,

determining, based on the analyzed content, a molar ratio of silicon dioxide and sodium oxide in the slag (the number of moles of silicon dioxide/the number of moles of sodium oxide); and

maintaining the molar ratio of silicon dioxide and sodium oxide in the slag to be 2.5 or more, by controlling charging of the alkali metal-containing compound based on the determined molar ratio, wherein the controlling comprises charging the alkali metal-containing compound when the molar ratio of silicon dioxide and sodium oxide in the slag is 2.5 or less,

wherein the alkali metal-containing compound is sodium silicate.

10 . The method according to claim 9 , wherein the high temperature gasification furnace is a gasification furnace for forming gas and slag from an organic raw material, comprising a combustion chamber for gasifying or combusting the organic raw material, a non-combustible material separation chamber for cooling and recovering the formed slag, and an inlet for an alkali metal-containing compound provided in the combustion chamber.

11 . The method according to claim 9 , wherein the low temperature gasification furnace is a fluidized bed gasification furnace.