Coal powder boiler with high-temperature SNCR (selective non-catalytic reduction) denitration reactors

Abstract

A coal powder boiler with high-temperature SNCR (selective non-catalytic reduction) denitration reactors comprises a hearth, wherein a screen-type heating surface and a first convective heating surface are sequentially arranged on the upper part of the hearth in the moving direction of flue gas; one or more high-temperature SNCR denitration reactors are connected onto a connecting flue of a flue gas outlet of the hearth and an inlet of a tail flue, or arranged on the two sides of the flue gas outlet of the hearth; when the high-temperature SNCR denitration reactors are arranged on the two sides of the flue gas outlet of the hearth, the flue gas outlet of the hearth is connected with the inlet of the tail flue; a second convective heating surface, a coal economizer and an air preheater are sequentially arranged inside the tail flue in the moving direction of the flue gas; coal is burned inside the hearth, the generated flue gas exchanges heat with the screen-type heating surface and the first convective heating surface which are arranged at the upper part of the hearth, and then carries coal ash to enter the high-temperature SNCR denitration reactors, a part of the coal ash is separated out, and the flue gas carries a small amount of the coal ash to enter the tail flue. The coal powder boiler increases the denitration efficiency.

Description

technical field [0001] The invention relates to the technical field of pulverized coal boilers, in particular to a pulverized coal boiler with a high-temperature SNCR denitration reactor. Background technique [0002] According to the new "Emission Standards of Air Pollutants for Thermal Power Plants" (GB13223-2011): NOx emissions of new thermal power units will be lower than 100mg / Nm from January 1, 2012 3 ; The NOx emission of active W flame furnace and CFB unit is lower than 200mg / Nm 3 (6% O2). For pulverized coal boilers, denitrification devices are generally required to meet new environmental protection requirements. Some circulating fluidized bed boiler units that use high volatile matter also need to be equipped with denitrification devices to meet the new environmental protection requirements. [0003] The current denitrification methods of coal-fired boilers include low NO in the furnace x Combustion, selective non-catalytic reduction flue gas denitrification (a...

AI Technical Summary

Problems solved by technology

Studies have shown that the main reasons for the low denitrification efficiency of SNCR in pulverized coal boilers include: ①The contact time is short, and the residence time of reducing agent and NOx in the effective temperature range of 850-1150°C is short; ②The delivery temperature window is narrow, and the reducing agent usually The spraying temperature window of the solution is about 850-1150°C, that is, the convection area where the panel passer and reheater near the flame angle and the final superheater and reheater of the horizontal flue are located, due to the heat absorption of the heating surface Or the change of boiler load makes the temperature window on the flue gas flow narrow, which is not conducive to the reaction; ③The mixing uniformity is poor, and the NH in the reduction reaction range 3 The uniformity of distribution is mainly affected by the number of injection points, injection speed, atomization effect, atomization particle size, etc.

Reductant and NO x Uneven mixing will not only reduce the denitrification efficiency, but also cause local excessive ammonia slip

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