A method for online removal of ammonium bisulfate ash plugging in air preheater of coal-fired power plant
An ammonium hydrogen sulfate, coal-fired power plant technology, applied in the combustion method, removal of solid residue, combustion product treatment and other directions, can solve the problem of differential pressure rise, increase the risk of corrosion and blockage of air preheater heat exchange elements, pollution and fouling And other issues
Active Publication Date: 2018-07-20
STATE GRID HEBEI ENERGY TECH SERVICE CO LTD +2
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Problems solved by technology
fugitive ammonia and SO 3 When the temperature is low, it reacts to form highly viscous ammonium bisulfate, which adheres to the surface of the air preheater, which is easy to cause pollution and dust accumulation, and increases the risk of corrosion and blockage of the heat exchange elements of the air preheater
[0003] With the introduction of the concept of ultra-low emissions, the escape concentration of ammonia at the denitrification outlet of coal-fired power plants often exceeds the design value, which inevitably forms ammonium bisulfate in the air preheater, resulting in serious blockage of the air preheater, increased differential pressure, and unit operation. Increased risks and costs
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[0014] The present invention will be described in detail below in conjunction with specific examples.
[0015] See attached figure 1 , flush the A-side air preheater online, the steps are as follows:
[0016] (1) When the unit load reaches 50%, slowly reduce the output of the fan A to be sent by 70%.
[0017] (2) Adjust the opening of the induced draft fan A so that the exhaust gas temperature of the air preheater A rises to 190°C at a rate of 2°C / min, and purge the air preheater A with steam for 60 minutes without interruption.
[0018] (3) Slowly increase the output of blower A and reduce the exhaust gas temperature to 120°C.
[0019] (4) Flush the cold end of air preheater A with high-pressure alkaline water with a pressure of 35MPa and a pH value of 12. The flue gas volume on side A is 270t / h, the flushing water volume is 3t / h, and the flushing time is 70min. During the flushing period, adjust the opening of the induced draft fan on the side of the air preheater to be c...
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The invention discloses a method of removing ammonium bisulfate ash clogging in an air preheater of a coal-fired power plant online. According to the method, on a low load condition, through adjusting openings of a forced draft fan and an induced draft fan, the exhaust gas temperature of the air preheater is controlled. On the one hand, high temperature is used to facilitate mode transformation of ammonium bisulfate, and the influence is eliminated through steam blowing. On the other hand, online high-pressure alkaline liquor is used to wash, and decomposition of ammonium bisulfate is facilitated, thus the clogging is eliminated. With the adoption of the method, the resistance of the air preheater can be reduced effectively. The method has important practical significances in improving the operating stability of a unit and reducing the operating cost.
Description
technical field [0001] The invention relates to the field of air preheaters in coal-fired power plants, in particular to an online method for removing ammonium bisulfate clogged ash in the air preheaters in coal-fired power plants. Background technique [0002] According to the "Emission of Air Pollutants from Thermal Power Plants" (GB13223-2011), the NOx concentration of coal-fired power plants will be 100mg / Nm 3 emission limits. In accordance with this requirement, most power plants have installed selective catalytic reduction (selectivecatalytic reduction, SCR) denitrification devices. The principle of the device is to spray a reducing agent (generally ammonia) into the flue gas at a lower temperature range (280-420°C) in the presence of a catalyst and oxygen, and selectively blow the flue gas. NOx in the air is reduced to N 2 and water to reduce NOx emissions. If too much ammonia is injected, ammonia escape will occur at the denitrification outlet. fugitive ammonia ...
Claims
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IPC IPC(8): F23J3/02
CPCF23J3/02
Inventor 陈崇明李振海宋国升郁金星
Owner STATE GRID HEBEI ENERGY TECH SERVICE CO LTD