Coupled double-fluidized-bed low-nitrogen combustion device and method

Abstract

The invention discloses a coupled double-fluidized-bed low-nitrogen combustion device. The coupled double-fluidized-bed low-nitrogen combustion device comprises a combustion unit, a gasification unit,a reburning denitration burnout area and a tail flue; an inlet of the reburning denitration burnout area respectively communicates with an outlet of the combustion unit and an outlet of the gasification unit; an outlet of the reburning denitration burnout area communicates with an inlet of the tail flue; and one or more post-combustion air nozzles are formed in the side wall of the after-combustion denitration burnout area. The invention further discloses a coupled double-fluidized-bed low-nitrogen combustion method, by using the device, NO<x> generated in flue gas of a combustion chamber andcoal gas generated in the gasification chamber are subjected to denitration reduction reaction in a reburning denitration post-combustion area, most of NO<x> in the flue gas is reduced, and low-nitrogen combustion is achieved. The method has the beneficial effects that a reducing agent is provided for a coal combustion denitration reaction through gasification of solid waste, so that the originalemission concentration of NO<x> and the denitration cost are remarkably reduced, and meanwhile, the resource utilization of the solid waste is realized.

Description

technical field [0001] The invention belongs to the technical field of clean and high-efficiency coal combustion, and in particular relates to a coupled double fluidized bed low-nitrogen combustion device and method. Background technique [0002] China is the world's largest coal producer and consumer, with coal output reaching 3.75 billion tons in 2019, accounting for 57.7% of primary energy consumption. Judging from my country's energy resources and economic development level, coal will still be the most important primary energy source in my country for a long period of time. According to statistics, 70% of my country's nitrogen oxide (NOx) emissions come from coal combustion, so the development of clean and efficient coal combustion technology has become particularly important and urgent. With the promulgation and implementation of the national "Emission Standard of Air Pollutants for Thermal Power Plants" (GB13223-2011), NOx emissions will be implemented at 100mg / m 3 C...

AI Technical Summary

Problems solved by technology

At present, technical measures to reduce NOx emissions from coal-fired boilers are mainly divided into three categories: (1) Low-nitrogen combustion technology in the furnace, including low-NOx burner, air classification and fuel classification technology, thick-lean combustion technology, flue gas recirculation technology, etc., such as Chinese patent 201610614713.6 discloses a low-nitrogen combustion method and system for industrial pulverized coal boiler flue gas recirculation, which improves the stability of pulverized coal ignition while obtaining the same emission reduction effect; however, the low-nitrogen combustion technology in the furnace denitrifies Efficiency is only 10-30%, far below the requirements of emission standards

(2) tail flue gas denitration technology, including selective catalytic reduction (SCR), selective catalytic reduction (SCR) combined with selective non-catalytic reduction (SNCR), activated carbon denitration and other technologies, although the denitrification efficiency can reach 70-90% , but it needs to be equipped with a complex flue gas denitrification treatment system, and additional reducing agents and catalysts need to be provided. The system is complex, the investment, operation and maintenance costs are high, and it will also cause secondary pollution, such as ammonia escape.

However, the structure of the new furnace is more complex, the cost of investment, development and operation is high, and it has higher requirements for the stability of boiler operation.

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