Heat exchanger for heating gas and use of the heat exchanger

Abstract

The invention relates to a heat exchanger for heating gas to a temperature in the range from 150 to 400° C., wherein the gas is heated by indirect heat transfer and all the surfaces of the walls of the heat exchanger which come into contact with the gas have been hot dip galvanized and the surfaces which come into contact with the gas, after the hot dip galvanization, have been heat treated at a temperature in the range from 400 to 750° C. The invention further relates to the use of the heat exchanger.

1 . A heat exchanger for heating gas to a temperature in the range from 150 to 400° C., the gas being heated by indirect heat transfer, wherein all surfaces of walls of the heat exchanger which come into contact with the gas have been hot dip galvanized and the surfaces which come into contact with the gas, after the hot dip galvanization, have been heat treated at a temperature in the range from 400 to 750° C. 
     
     
         2 . The heat exchanger according to  claim 1 , wherein the heat treatment is conducted over a period of 1 to 5 min. 
     
     
         3 . The heat exchanger according to  claim 1 , wherein the walls of the heat exchanger have been manufactured from sheet steel. 
     
     
         4 . The heat exchanger according to  claim 1 , wherein the heat exchanger is a plate heat exchanger, a shell and tube heat exchanger or a spiral heat exchanger. 
     
     
         5 . The heat exchanger according to  claim 1 , wherein the walls which come into contact with the gas have fins. 
     
     
         6 . The heat exchanger according to  claim 1  used for drying superabsorbent particles. 
     
     
         7 . The heat exchanger according to  claim 6  used in a belt drier for drying superabsorbent particles. 
     
     
         8 . The heat exchanger according to  claim 7 , wherein the heat exchanger is disposed beneath the drying belt of the belt drier. 
     
     
         9 . The heat exchanger according to  claim 6  for heating drying gas which is added to a spray tower for production of superabsorbent particles. 
     
     
         10 . The heat exchanger according to  claim 9 , wherein the drying gas is circulated. 
     
     
         11 . The heat exchanger according to  claim 6 , wherein the heat transfer medium used is a thermal oil, an ionic liquid, a salt melt, or steam. 
     
     
         12 . A method of drying superabsorbent particles comprising the use of the heat exchanger according to  claim 1 . 
     
     
         13 . The method according to  claim 12 , wherein the heat exchanger is disposed beneath a drying belt of a belt drier.