Single-tower multi-stage circulating ammonia/ammonium sulfate flue gas desulfurization method

Abstract

The invention discloses a single-tower multi-stage circulating ammonia / ammonium sulfate method flue gas desulfurization method. The method comprises the following steps: step 1, pre-washing flue gas,2, carrying out flue gas desulfurization, 3, further desulfurizing the flue gas, 4, removing desulfurization liquid drops from the flue gas, 5, washing the desulfurized flue gas with water, 6, removing outlet fog drops from the flue gas, and 7, concentrating and crystallizing. The method has the advantage of controlling ammonia escape and aerosol.

Description

technical field [0001] The invention relates to the technical field of flue gas desulfurization, and more specifically relates to a single-tower multi-stage circulating ammonia / ammonium sulfate flue gas desulfurization method. Background technique [0002] Sulfur dioxide is the main air pollutant. It is directly discharged into the atmosphere, which will affect human health. It will form "acid rain" in contact with water, corrode buildings and vegetation, and cause great harm to the human living environment. For a long time, my country's SO 2 Emissions have remained high, and it has become the third largest acid rain area in the world after Europe and the United States. In order to reduce the emission of sulfur dioxide, the Chinese government has implemented more stringent policies to limit the emission of sulfur dioxide from thermal power plants. Clean emissions" target, the action requires that by the end of 2020, the concentration of soot, sulfur dioxide and nitrogen ox...

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Problems solved by technology

[0006] (1) There is no chain feedback for ammonia addition in this patent. In actual engineering, with fluctuating flue gas load, the control of ammonia water regulation is a difficult point; in the prior art, the regulation is generally based on the detection results of the net flue gas at the outlet of the absorption tower The amount of ammonia added, but this method has a long delay time, which will cause the adjustment of ammonia addition to be untimely, resulting in the failure of desulfurization efficiency or exceeding the standard of ammonia escape;

[0007] (2) The means of controlling ammonia escape and aerosol in this patent are complicated, and there is no control in the absorption section. The subsequent treatment process often increases the height of the tower. For example, the demist section is equipped with an electric demister and a cleaning spray layer from top to bottom , grid packing layer, folded plate mist eliminator

However, these methods do not start from the source of aerosol and ammonia escape during the absorption process, but only focus on how to eliminate the escaped ammonia and aerosol during the absorption process, which makes the number of tower sections more and more complicated, and the treatment effect is not good. Yes, and the cost of investment and operation has increased significantly;

[0008] (3) The patent does not specify the specific composition, concentration, absorption temperature and pH of the absorption liquid solution, and there is no monitoring of the corresponding data in the process flow, so the coordinated control of absorption, oxidation and concentration cannot be realized, and the escape of ammonia and gas cannot be completely controlled from the swimming head. The generation of sol, and the flue gas after simple water washing and defogging is still difficult to meet the current ultra-low emission standards or higher requirements

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