Independent circulating wet desulphurization system and method

Abstract

The invention discloses an independent circulating wet desulphurization system and method. The system comprises a main tower, a pre-washing crystallization tower, a limestone / lime slurry supply pump, a main tower circulating pump, an oxidization fan, a main tower gypsum discharge pump, a pre-washing crystallization tower circulating pump and a pre-washing crystallization tower gypsum discharge pump, wherein a flue gas outlet of the pre-washing crystallization tower is communicated with a flue gas inlet of the main tower; a flue gas outlet of the main tower is communicated with atmosphere; a main tower slurry pond, a main tower desulphurization region and a demist region are arranged in the main tower from bottom to top; a main tower stirrer is arranged on the main tower slurry pond; an oxidization crystallization slurry pond and a pre-washing crystallization tower desulphurization region are arranged in the pre-washing crystallization tower; and a pre-washing crystallization tower stirrer is arranged on the oxidization crystallization slurry pond. The independent circulating wet desulphurization system is in an independent circulating mode that SO2 removal by the main tower with a high pH value is taken as a main function and deep oxidization and crystallization of desulphurization slurry are taken as the main function of the pre-washing crystallization tower; the system and the method have high desulphurization efficiency, and relatively low system energy consumption; and high-quality gypsum can be generated.

Description

technical field [0001] The invention relates to the technical field of limestone / lime-gypsum wet desulfurization, in particular to an independent circulation wet desulfurization system and method. Background technique [0002] The recently released "Coal Power Energy Conservation and Emission Reduction Upgrading and Transformation Action Plan (2014-2020)" proposed higher energy efficiency and environmental protection standards, stipulating that newly built coal-fired units in the eastern 2 The emission concentration basically reaches 35mg / Nm 3 , new coal-fired units SO 2 The concentration is close to or reaches 35mg / Nm 3 ; In addition, in order to further remove CO from the flue gas after desulfurization 2 requirements, the flue gas SO needs to be 2 Emission concentration reaches 20mg / Nm 3 following concentration standards. [0003] At present, the conventional limestone / lime-gypsum wet desulfurization system and method are applied to units burning low-sulfur coal, whi...

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Problems solved by technology

[0003] At present, the conventional limestone / lime-gypsum wet desulfurization system and method are applied to units burning low-sulfur coal, which can meet the emission standards; for units burning medium-high sulfur coal, to meet higher emission standards, large-capacity absorption must be built Tower, set multiple large-scale slurry circulation pumps and oxidation fans, resulting in high desulfurization energy consumption; in addition, if the method of increasing the pH value of the slurry to achieve higher desulfurization efficiency will make it difficult to oxidize and crystallize gypsum, resulting in poor quality gypsum

[0004] Therefore, it is necessary to develop a new limestone / lime-gypsum wet desulfurization technology to solve the problems of high desulfurization energy consumption and poor gypsum quality while meeting higher emission standards

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