Generic Methods for Coke Oven Gas Desulphurisation by Wilfried ...

198THE COKE OVEN MANAGERS’ASSOCIATIONThe available processes suitable for desulphurisation of coke ovengas can be subdivided into three generic methods, namely• dry oxidative processes,• wet oxidative processes and• neutralization or absorption/stripping processes.In Fig. 3 you can see the most common processes for each of thegeneric methods.Dry Oxidative ProcessesThe Iron Oxide Process was used for the first time in the early 17 thcentury and the process has hardly changed since then. For theabsorption of hydrogen sulphide ferric hydroxide mass is utilised.An iron oxide process based plant mainly consists of cleaning,depositing and emptying towers with a certain number of baskets or ofboxes with layers of ferric hydroxide.As you can see from Fig. 5, oxygen for sulphur forming is required(approx. 1 to 1.5 % vol. of oxygen). That means oxygen has to beadded to the coke oven gas. Due to formation of water by the process,the coke oven gas should be slightly overheated before entering thetowers/boxes.By this process elemental sulphur is produced and forms a layer onthe iron oxide mass and lowers the activity of the mass. Therefore afterloading of the mass to a certain extent, this basket tower/box has to bechanged to a tower/box with fresh mass. In the beginning in using thisprocess big boxes were used, but later cylindrical towers have beenused because of operating the process at higher pressure and because ofless necessary space.Another way to adsorb hydrogen sulphide is the use of the ZincOxide Process.