Removal of ammonia from coke-oven gas is an integral part of the traditional coke production process. Foul gas from coke plants in eastern Russia contains 8-14 g ammonia per m~3. Ammonia and other harmful impurities must be removed from the gas in order to prevent corrosion of lines and equipment involved in the further processing of this gas, and also to prevent environmental damage from toxic nitrogen oxides released by burning the ammonia in the gas [1]. The most common method of removing ammonia from coke-oven gas is to use sulfuric acid in a saturator or other device. However, in recent years, the sulfuric acid method has been less economically feasible, in part due to declining interest in the ammonium sulfate, given the increased production of more effective multicompo-nent fertilizers. The method uses large amounts of sulfuric acid, which presents a considerable environmental hazard. These problems could be addressed by switching to less expensive, more environment-friendly technologies for removing ammonia from coke-oven gas. The problem of determining the feasibility limits for the sulfuric acid method vs. the circulating phosphate method can be reduced to the problem of calculating the feasibility of the investment project for converting from sulfuric acid to circulating phosphate. For the initial data used in this example and the present assumptions (including DPP = 6-7 yr), the feasibility limit for using either method is determined by the following ratio of prices for ammonium sulfate and sulfuric acid: Price H_2SO_4 = 1.397 Price (NH_4)_2SO_4 + 70.748 dollars/t. At the current prices for sulfuric acid and ammonium sulfate, it is not feasible to convert from sulfuricacid to the circulating phosphate method.
展开▼
