Ultralow-emission power generation system using low-calorific-value fuel for combustion

Abstract

The invention discloses an ultralow-emission power generation system using low-calorific-value fuel for combustion. The ultralow-emission power generation system comprises a high temperature circulating fluidized bed boiler, a low temperature dust remover, a wet-process smoke desulphurization system and a wet type electric dust remover, wherein the high temperature circulating fluidized bed boiler comprises a controllable multi-stage air supply system, an ash staging cooling and discharging system, a low resistance air distribution device, a highly efficient cyclone separator, a deep denitration system and a strong smoke cooler and is small in N2O emission amount, and porous ashes are used for adsorbing SO3 and heavy metals; the ash concentration in the boiler and material grain size distribution can be adjusted through the ash staging cooling and discharging system when the low-calorific-value fuel for combustion is combusted so as to optimize combustion, heat transmission and flowing; the ultralow emission of NOx is realized through the controllable multi-stage air supply system and the deep denitration system; the ultralow emission of SO2 is realized by combining the wet-process smoke desulphurization system and calcium-injection desulfurization in the boiler; the ultralow emission of dust is realized through the lower temperature dust remover, the wet-process smoke desulphurization system and the wet type electric dust remover. According to the ultralow-emission generation system, the emission standards of thermal power plants and natural gas turbine generator units in key areas, the cost of pollutant removal is low and the environmental benefit is remarkable.

Description

technical field [0001] The invention relates to the technical field of low-calorific-value fuel combustion, in particular to an ultra-low-emission power generation system for low-calorific-value fuel. Background technique [0002] my country is the world's major coal producer and consumer, and also a country that uses coal as its primary energy source. With the production and washing of coal, a large amount of low calorific value fuels (including gangue, washed medium coal, coal slime, etc.) are produced. If not utilized, a large amount of land will be occupied and the environment will be polluted. Due to the low calorific value of fuel, the converted sulfur content and converted ash content are very high, so it is difficult to burn efficiently, and the amount of pollutant emissions is also large. [0003] Since pulverized coal boilers have high requirements for fuel and cannot use low calorific value fuels, conventional circulating fluidized bed boilers are widely used in ...

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Problems solved by technology

[0005] 2) Adding limestone can achieve desulfurization in furnace combustion, and the desulfurization efficiency can reach 90%, but the Ca / S molar ratio is high (usually 3 or even higher), and the utilization rate of limestone is low (less than 40%);

[0006] 3) The low-temperature combustion method is adopted, the combustion efficiency is low, and the boiler efficiency is low;

[0007] 4) The low calorific value fuel has high ash content, which is affected by the low efficiency of the dust collector, and the dust emission concentration is high;

[0008] 5) After the desulfurization in the furnace is adopted, a large amount of CaSO is mixed in the ash 3 , CaO, etc., coupled with the high carbon content of fly ash, it is not easy to comprehensively utilize the ash

Although the desulfurization efficiency of conventional circulating fluidized bed boilers can reach 90%, SO 2 The emission concentration is lower than 100mg / m 3 Difficult to achieve, NO controlled by combustion x The emission concentration is lower than 100mg / m 3 It is also difficult to achieve. The conventional dust removal method should make the dust emission reach 30mg / m 3 even lower is difficult

Therefore, combined with the current environmental protection situation, conventional circulating fluidized bed boilers cannot meet the requirements of large-scale clean utilization of low calorific value fuels

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