A boiler suitable for full-load scr denitrification and its working method

Abstract

The invention discloses a boiler suitable for full load SCR denitration. Water-cooled walls and superheaters are arranged at a hearth and a boiler high-temperature flue gas section; a first flue gas condensation water heat exchanger, an SCR denitration device and a second flue gas condensation water heat exchanger are arranged at the tail of the boiler; the SCR denitration device is arranged between the first flue gas condensation water heat exchanger and the second flue gas condensation water heat exchanger; a condensation water outlet of the second flue gas condensation water heat exchangeris connected with a condensation water inlet of the first flue gas condensation water heat exchanger; a condensation water inlet of the second flue gas condensation water heat exchanger is connected with a condensation water pump; a by-pass is arranged at the condensation water inlet of the first flue gas condensation water heat exchanger and is connected with a condensation water outlet of the first flue gas condensation water heat exchanger; a bypass valve is arranged on the by-pass; and an outlet of a feed pump and an outlet of the first flue gas condensation water heat exchanger are connected with the water-cooled walls. The disadvantages arising from the arrangement of a traditional boiler economizer and an air preheater are overcome, and the stabilization of an SCR flue gas inlet temperature and a high-temperature air temperature can be realized.

Description

technical field [0001] The invention belongs to the technical field of boilers, and in particular relates to a boiler suitable for full-load SCR denitrification. Background technique [0002] In traditional boilers, an air preheater is usually used on the heating surface at the rear of the boiler. The inlet air temperature of the air preheater is determined by the atmospheric environment and is usually not adjustable. Since the air heat capacity flow rate is smaller than the flue gas heat capacity flow rate, it is necessary to ensure Sufficient heat transfer temperature difference, the reduction of exhaust gas temperature is inherently limited, and high exhaust gas temperature will inevitably increase the water consumption of the subsequent wet desulfurization system. In addition, due to the low air inlet temperature, in the traditional air preheater of air-flue gas heat exchange, the temperature of the heat exchange surface is usually around the middle value of the flue gas...

AI Technical Summary

Problems solved by technology

[0002] In traditional boilers, an air preheater is usually used on the heating surface at the rear of the boiler. The inlet air temperature of the air preheater is determined by the atmospheric environment and is usually not adjustable. Since the air heat capacity flow rate is smaller than the flue gas heat capacity flow rate, it is necessary to ensure Sufficient heat transfer temperature difference, the reduction of exhaust gas temperature is inherently limited, and high exhaust gas temperature will inevitably increase the water consumption of the subsequent wet desulfurization system

In addition, due to the low air inlet temperature, in the traditional air preheater of air-flue gas heat exchange, the temperature of the heat exchange surface is usually around the middle value of the flue gas temperature and the air temperature, resulting in inevitable low-temperature corrosion and plugging Ash and other adverse effects

For the boiler system used in the traditional thermodynamic cycle, when the load decreases, the flue gas temperature will also decrease, and the heating temperature of the air will decrease, which will lead to insufficient fuel combustion and affect the boiler efficiency; under different loads, SCR denitrification is usually affected by the temperature at the location of the SCR catalyst. Changing effects, difficult to control

Therefore, in summary, traditional boilers have the problems of limited exhaust gas temperature, insufficient air temperature heating at low load, low temperature corrosion and ash plugging, and unfavorable SCR operation

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