Wet ammonia desulfurization concentration process of cold and hot state discharge

Abstract

The invention relates to a wet ammonia desulfurization concentration process of cold and hot discharge. A desulfurization tower is partitioned into a concentration section and an absorption section through a gas-liquid separation partition plate; oxidized saturated ammonium sulfate solution is concentrated, and original flue gas is washed, wetted and cooled at the concentration section; the saturated ammonium sulfate solution is continuously concentrated, and partial crystal is generated; the slurry of the concentration section is controlled in certain pH value and density range; when the solid content is high, cold state discharge is adopted; when the solid content is low, hot state discharge is adopted; and when the solid content is in a proper range, the slurry is discharged out of thedesulfurization tower in two discharge modes of cold and hot states and enters subsequent devices for processing, and high-quality ammonium sulfate byproducts are produced. By the process, synchronous implementation of crystallization in the tower and crystallization out of the tower can be realized, the recovery rate of ammonia is maximized and the purposes of achieving high desulfurization efficiency, saving energy, reducing consumption and producing the high-quality ammonium sulfate byproducts are fulfilled.

Description

technical field [0001] The invention relates to the technical field of resources and environment, and specifically relates to a wet ammonia desulfurization and concentration process for discharging materials in cold and hot states. Background technique [0002] At present, the limestone-gypsum method is basically the main desulfurization device in my country. Firstly, because the desulfurization agent limestone is abundant and cheap, and the limestone-gypsum method technology is quite mature and open in foreign countries, and it is easy to obtain. However, the equipment of this technology is easy to foul and block, the system is complex, the investment is large, the area is large, the secondary pollution is generated, and the operating costs are high. The wet ammonia desulfurization technology does not produce carbon dioxide when removing sulfur dioxide in the flue gas (calcium method produces 0.7 tons of carbon dioxide when removing 1 ton of sulfur dioxide), and does not pr...

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Problems solved by technology

[0005] There are many problems in this process in practical engineering application: (1) Absorption, oxidation and concentration are all carried out in the tower, it is difficult to control the oxidation rate, absorption effect, pH value and crystal formation at the same time; (2) The temperature of the raw flue gas is generally As high as above 120°C, the direct absorption effect is very poor, because the decomposition temperature of the main product ammonium sulfite after absorption is roughly 50°C-60°C, and ammonium sulfite will decompose again, which will affect the desulfurization effect; (3) Excessive flue gas High absorbent ammonia water will also be decomposed by heat, resulting in ammonia escape and damage to the demister; (4) Since the desulfurization process is affected by many factors, such as boiler load, coal quality and absorbent pH value, etc., a Discharge method, if there are few crystals generated, the ammonium sulfate product will not be obtained by using cold discharge, and will increase the load in the tower; if there are many crystals, use hot discharge, which will increase energy consumption and may even block the pipe (5) Because the absorption, oxidation and concentration of the tower bottom solution are all carried out in the tower, the solution is always a mixture of ammonium sulfate, ammonium bisulfite, ammonium sulfite, ammonium bisulfite and other components, it is difficult to Control the quality of the by-products obtained from the slurry out of the tower

It can be seen that although this process has achieved a certain desulfurization effect, it is difficult or even impossible to obtain high-quality ammonium sulfate by-products, resulting in a waste of resources

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