Out tower double circulation desulfurization system and desulfurization process thereof

Abstract

The invention relates to a limestone-gypsum wet desulphurization of coal-fired boiler flue gas, and in particular relates to an out tower double circulation desulfurization system and a desulfurization process thereof; the out tower double circulation desulfurization system comprises a tower body, an out tower low pH value slurry pool and an out tower high pH value slurry pool; the bottom of the tower body is provided with a flue gas inlet, the top of the tower body is provided with a flue gas outlet, and a low pH value spray zone, a conical liquid collecting bucket, a high pH value spray zone and a demister are arranged fixedly in turn from bottom to top at the position between the flue gas inlet and the flue gas outlet in the tower body. The out tower low pH value slurry pool and the out tower high pH value slurry pool are arranged outside the tower body, so that operation effect is visual, the problems such as bubbling, overflowing, agitator seal position slurry leakage and the like of a traditional desulfurization system with a slurry pond arranged in an absorption tower can be effectively avoided, the failure rate of the desulfurization system is reduced, the desulfurization equipment availability can be improved, the normal unit operation can be ensured, full oxidation and efficient desulfurization can be ensured, and high-quality gypsum can be produced.

Description

Technical field [0001] This application relates to limestone-gypsum wet desulfurization of flue gas from coal-fired boilers, and in particular to an external dual-cycle desulfurization system and a desulfurization process. Background technique [0002] In recent years, national environmental protection policies have become increasingly strict, and ultra-low emission standards have been put forward for the thermal power industry, which requires the emission concentration of sulfur dioxide in the flue gas of coal-fired boilers in thermal power plants to meet the emission standard of gas turbines, which is 35mg / Nm 3 Below, the traditional single-tower single-cycle spray desulfurization system cannot meet the requirements of the latest standards. [0003] The single-tower double-circulation system can effectively improve the desulfurization efficiency and realize the sulfur dioxide emission under the ultra-low emission standards; but its slurry pool is set at the bottom of the tower, an...

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Problems solved by technology

[0002] In recent years, the national environmental protection policies have become increasingly stringent, and ultra-low emission standards have been put forward for the thermal power industry, which requires the emission concentration of sulfur dioxide in the flue gas of coal-fired boilers in thermal power plants to meet the emission standards of gas turbines, that is, 35mg / Nm 3 Below, the traditional single-tower single-cycle spray desulfurization system is difficult to meet the requirements of the latest standards

[0003] The single-tower double-circulation system can effectively improve the desulfurization efficiency and realize the emission of sulfur dioxide up to the standard under the ultra-low emission standard; however, the slurry tank is set at the bottom of the tower, and the operation effect is not intuitive, which cannot avoid the traditional single-tower single-circulation desulfurization system Problems that are prone to occur in the slurry tank in the tower, such as foaming, overflow, slurry leakage at the seal of the agitator, etc., increase the failure rate of the desulfurization system, reduce the availability of the desulfurization device, and affect the normal operation of the unit; The desulfurization system of the pool needs to be equipped with an accident slurry pool. Before the absorption tower is overhauled, the slurry in the tower should be emptied to the accident slurry pool.

In addition, the current dual circulation systems are mixed and interact with each other; the pH value in the two circulation systems fluctuates and becomes unstable, and the desulfurization and gypsum production processes cannot strictly control the quality

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