Special surface coolers consisting of copper or stainless steel tubes with string fins. The principle is to let the heat medium or cold medium or refrigerant flow through the inner cavity of the metal pipe, and the gas to be processed flows through the outer wall of the metal pipe for heat exchange to achieve the purpose of heating or cooling the gas. The purpose of string fins is to expand the heat exchange area and get a better effect of heat exchange. It is necessary to select suitable materials according to the actual use conditions.This series of environmental protection and emission reduction equipment has played a certain role in promoting the comprehensive management of energy and environment in specific enterprises.