Method and system for improving quality of desulfuration byproduct ammonium sulfate

Abstract

The invention discloses a method and a system for improving the quality of a desulfuration byproduct ammonium sulfate. After flue gas enters a desulfurizer, the method comprises the processes of ammonium sulfate crystallization, SO2 absorption and demisting and ammonia removal. The system comprises an ammonium sulfate crystallization section, a SO2 absorption section and a demisting and ammonia removal section from bottom to top in turn, wherein the ammonium sulfate crystallization section is provided with a flue gas inlet; an ammonia water adding device, an oxidant adding device and a stirrer are arranged in a slurry tank below the flue gas inlet; and a primary circulating spraying device is arranged above the flue gas inlet and connected with the slurry tank through a circulating pump. Through reasonable addition of strong oxidizers such as ozone and ammonia water, the oxidation of (NH4)2SO3 is strengthened, the concentration of the ammonia sulfate in the slurry is improved, and secondary pollution in the concentrating and drying processes of the ammonia sulfate is avoided; and through reasonable utilization of the heat energy of the flue gas per se, the using amount of steam for drying the ammonia sulfate is reduced, and the quality of the desulfuration byproduct ammonium sulfate is integrally improved.

Description

【Technical field】 [0001] The invention relates to the field of environmental protection equipment and methods, in particular to a method and system for improving the quality of ammonium sulfate, a by-product of desulfurization. 【Background technique】 [0002] In my country's energy structure, coal is the primary energy source, accounting for more than 75%. A large amount of coal burning leads to SO in my country 2 The pollution is serious, and it is estimated that my country emits one ton of SO every year 2 The resulting economic loss was about RMB 20,000. In strict SO 2 Under the emission standards, my country's desulfurization industry is in full swing, and the most resourceful and promising desulfurization method is the ammonia desulfurization technology. Ammonia desulfurization technology uses ammonia or ammonia water alkaline solution to absorb SO in flue gas 2 The main reaction formula of the principle of producing ammonium sulfate fertilizer is as follows: [00...

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Problems solved by technology

[0009] At present, ammonia desulfurization technology oxidizes nitrite, SO 2 Absorption of circulating liquid, ammonium sulfate crystallization, etc. are all completed in a slurry tank, therefore, in order to ensure SO 2 The washing effect must be ensured in the slurry (NH 4 ) 2 SO 3 and NH 4 HSO 3 The appropriate ratio of , resulting in the following problems: ① cannot use strong oxidizing agents in the system to oxidize (NH 4 ) 2 SO 3 , otherwise (NH 4 ) 2 SO 3 A large amount of oxidation to (NH 4 ) 2 SO 4 , seriously affects the SO 2 absorption effect; ② in the slurry (NH 4 ) 2 SO 4 The mass concentration is low; ③Because the slurry contains NH 4 HSO 3 and (NH 4 ) 2 SO 3 More, in the follow-up ammonium sulfate concentration and drying molding process, the thermal decomposition of acid nitrite and nitrite produces a lot of ammonia gas, causing secondary pollution, resulting in poor production environment, and waste of absorbent ammonia or ammonia water; ④ due to the The mass concentration of the gas is low, and a large amount of steam is used in drying. On the one hand, it consumes a lot of energy, and on the other hand, the large amount of heat carried in the flue gas has not been optimized.

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