Underground coal gasification gas purification system and use method thereof

The invention relates to the technical field of coal gasification, and discloses an underground coal gasification gas purification system and a use method thereof.The underground coal gasification gas purification system comprises a plurality of cooling boxes and cooling gas inlet pipes located in the cooling boxes, the tops of the cooling gas inlet pipes are connected with a plurality of cooling branch pipes, and the cooling branch pipes are spiral; the top of the cooling branch pipe is connected with the other end of the cooling air outlet pipe located at the upper end of the cooling box. The top and the bottom of the cooling box are provided with a cooling water inlet and a cooling water outlet correspondingly. The cooling box and the spiral cooling pipe are arranged, high-temperature coal gas can be cooled, meanwhile, the high-temperature coal gas is prevented from making direct contact with a cooling medium, it is guaranteed that no new matter is generated when the high-temperature coal gas is cooled, du