Patent ID: 7244405
Filing Date: 2007-07-17
Classification: B01D,C10K,Y02P

Abstract:
1. Method for cleaning coke oven gas by washing the gas, whereby caustic soda as a washing liquid is guided into a washing liquid circuit and impurities in said washing liquid are expelled in a desorber for regeneration of the caustic soda, and whereby the coke oven gas is washed with the washing liquid in a counter-flow, comprising the following steps: washing of the gas which occurs in two stages, and comprises a first alkaline washing stage for the acidic gas components, as well as a second washing stage that works in the neutral to acidic pH range, for the absorption of ammonia, passing the coke oven gas to be cleansed in at a foot of the second washing stage, flowing through the two washing stages, one after the other, and being drawn off at a head of the first washing stage, putting a washing liquid consisting of caustic soda in at the head of the first washing stage, passing the washing liquid that flows out of the first washing stage to a top segment of the second washing stage, lowering the pH of the washing liquid, by an absorption of the acidic gas components, to such an extent that a washing liquid can be used for the absorption of ammonia in the second washing stage, passing the washing liquid into the desorber for regeneration of the caustic soda, whereby in the desorber all the acidic gas components as well as ammonia are expelled, so that only caustic soda remains in the liquid, balancing absorbent losses by adding NaOH to the regenerated caustic soda and returning the washing liquid to the head of the first washing stage, and withdrawing a waste water containing sodium salt from the washing liquid circulation and balancing the liquid loss with coal water that occurs in the coke oven operation.