Comprehensive treatment method for high-concentration ammonia nitrogen waste water and boiler flue gas

Abstract

The invention belongs to the field of the recycling of waste water and waste gas, and particularly relates to a comprehensive treatment method for high-concentration ammonia nitrogen waste water and boiler flue gas. The method comprises the following steps of: after separating crude synthesis gas formed by the waste water from a gasification process by a gas-liquid separator, conveying the separated gas to a low-temperature methanol washing process, and conveying low-temperature condensate generated by washing the gas and high-pressure flashing gas from a gasification lime water process into a steam stripping tower; conveying steam subjected to gas stripping by the steam stripping tower into a boiler by a pipeline; and performing reduction reaction of NH3 and NOx in the flue gas to generate N2 and water, reacting the NH3 with SO2 in the flue gas to generate (NH4)2SO3, and combining the (NH4)2SO3 with O2 to generate stable (NH4)2SO4. According to the comprehensive treatment method, the high-concentration ammonia nitrogen waste water serving as a denitration agent is used for the desulfuration and denitration of the boiler, so that the problem of the pollution of nitrogen oxides in petrochemical enterprises is solved, the discharged high-concentration ammonia nitrogen waste water is 'eliminated completely' in the desulfuration and denitration processes, two pollution sources are eliminated, and the win-win aims of environmental protection and resource recycling are fulfilled.

Description

[0001] technical field [0002] The invention belongs to the technical field of waste water and waste gas treatment, and in particular relates to a method for comprehensive treatment of high-concentration ammonia nitrogen waste water and boiler flue gas. Background technique [0003] In recent years, with the rapid development of fertilizer, petrochemical and other industries, the resulting high-concentration ammonia nitrogen wastewater has also become one of the restrictive factors for the development of the industry. Most petrochemical enterprises form part of waste ammonia or high-concentration ammonia-nitrogen wastewater during production. In the past, waste ammonia water was treated or discharged by traditional "three wastes" treatment methods after being discharged as wastewater, which not only increased production costs but also caused environmental pollution. The discharge of a large amount of ammonia nitrogen wastewater into the water body will cause the reduction...

AI Technical Summary

Problems solved by technology

[0014] The disadvantages of the limestone-gypsum wet desulfurization process are that the system is complex and occupies a large area; the cost is high and the one-time investment is large; the by-product gypsum is large in quantity and is not easy to handle, and at the same time it will generate greenhouse gas CO 2 discharge, as well as waste water discharge, which is prone to secondary pollution

[0015] The disadvantage of the sodium-based wet desulfurization process is that the cost of the desulfurizer is much higher than the discharge charge, and the more desulfurization, the worse the economy

[0016] The disadvantage of the spray drying desulfurization process is that this method has high requirements on the quality of the desulfurizer, the calcium-sulfur ratio is relatively high, and it requires a high level of production management. Small and medium-sized boilers with low efficiency, limited by the reaction tower and spray at the same time

[0017] Circulating fluidized bed desulfurization process uses quicklime or slaked lime as absorbent, the cost of raw materials is high, and there are high requirements for lime quality; because the flue gas after desulfurization contains more dust, the downstream dust removal equipment is required to have higher dust removal Efficiency; desulfurization by-product is a mixture of calcium sulfite and calcium sulfate, comprehensive utilization is limited

[0018] The disadvantage of the MgO wet flue gas desulfurization method is that the recovery of by-products is difficult, because MgSO 3 and MgSO 4 The solubility in water is relatively high. If the method of evaporative crystallization is used, a large amount of energy will be consumed. If the flocculation-settling agent (polyacrylamide) is added and then filtered and separated, the flocculation-settling agent may have an impact on downstream devices, but for ionic soluble The salts should be under a certain pH condition, and the addition of flocculation and sedimentation agent can make Mg 2+ Separated from the solution; the cost of desulfurizer and magnesium oxide is high; there may be side reactions, so the actual consumption of MgO will be more than theoretically expected