Heat exchanger for cooling slag-containing gases from coal gasification

Abstract

A tube bundle heat exchanger having an additional tube bottom with insertion tubes arranged in the inlet chamber upon the inlet side of the hot gases for the tubes located between the tube bottoms of the tube bundle. The additional tube bottom is arranged in such a way that both tube bottoms in the inlet chamber define another inlet chamber for colder, slag-free gases, which inlet chamber is accessible through an inlet in the shell of the tube bundle heat exchanger. The insertion tubes project far into, but not to the end of, the tubes of the tube bundle. The insertion tubes, with the outer tubes, form relatively narrow annular spaces suitable for generating high discharge speed. Four spiral formed strips respectively located in the annular spaces impart a twist to the gas flow discharging from the annular spaces to assure that gas discharging between the insertion tubes and the tubes of the tube bundle remain in flowing contact along the inner walls of the tubes. Slag-containing gas coming from a coal gasificatin reactor flows through an inlet into the inlet chamber of the tube bundle heat exchanger and is cooled off in three regions during flowing through the tube bundle heat exchanger whereby temperatures of the cooling-off gas are maintained in such a manner that slag is precluded from depositing upon the heat transfer surfaces while the gas is cooling off.