A high-temperature smoke cooler-air heater system suitable for scr denitrification system

Abstract

The invention relates to a high-temperature flue gas condenser-air heater system applicable to an SCR denitration system. The high-temperature flue gas condenser-air heater system comprises a flue gas condenser, a primary fan, a primary cold air channel, a primary air heater, a primary hot air channel, a secondary fan, a secondary cold air channel, a secondary air heater, a secondary hot air channel and a pipeline. The high-temperature flue gas condenser-air heater system can be used for cooling high-temperature flue gas which is over 410 DEG C at an inlet of an SCR reactor to the temperature of about 380 DEG C, is conductive to make an SCR catalyst be in an optimal running temperature range, can reduce the conversion rate of SO2 / SO3 in the SCR reactor, can reduce the concentration of the SO3 in an air pre-heater and reduce emission of the SO3, and is conductive to increase the comprehensive temperature of a cold end of the air pre-heater and to improve the ammonium bisulfate blocking resistance of the air pre-heater.

Description

technical field [0001] The invention belongs to SO in thermal power plant SCR flue gas denitrification 3 The control field specifically relates to a high-temperature smoke cooler-air heater system suitable for SCR denitrification systems. Background technique [0002] In order to control NOx emissions of coal-fired units, an SCR flue gas denitrification device is arranged between the boiler and the air preheater. When the flue gas passes through the catalyst, part of the SO in the flue gas 2 is oxidized to SO 3 , and with increasing temperature, SO 2 / SO 3 The conversion rate increased rapidly, SO 2 / SO 3 The relationship between conversion rate and temperature see figure 1 . Some power plant boilers burning anthracite and lignite need higher primary and secondary air temperatures to ensure combustion stability. Heat, that is, the SCR catalyst will operate at a high temperature of more than 400 ° C, causing the following problems: SO in the SCR reactor 2 / SO 3 The ...

AI Technical Summary

Problems solved by technology

Some power plant boilers burning anthracite and lignite need higher primary and secondary air temperatures to ensure combustion stability. Heat, that is, the SCR catalyst will operate at a high temperature of more than 400 ° C, causing the following problems: SO in the SCR reactor 2 / SO 3 The conversion rate is high, and the SO in the outlet flue gas 3 Concentration increases, affecting SO 3 Control of emission concentration; SO in flue gas at air preheater inlet 3 The concentration increases, which worsens the blockage of ammonium bisulfate at the cold end; in order to reduce SO at high temperature 2 / SO 3 The conversion rate needs to reduce the activity of the catalyst, so the volume of the catalyst needs to be increased

[0003] The ultra-low emission operation of coal-fired units requires controlling the NOx emission concentration to 50mg / m 3 Below, it is necessary to increase the catalyst to increase the SCR denitrification efficiency to over 90%, which increases the difficulty of controlling the ammonia escape concentration, especially when the operating temperature exceeds 410°C, the SO in the flue gas 3 The concentration has increased significantly, which worsens the blockage of ammonium bisulfate in the air preheater, increases the resistance power consumption of the flue, and even affects the load of the unit.

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