Method for removing hardened ash scale of boiler air preheater

Abstract

The invention provides a method for removing hardened ash scale of a boiler air preheater. The hardened ash scale of the air preheater can be more effectively removed on the premise of energy conservation and environmental protection. A heat exchange unit is disassembled under the shutdown state of the air pre-heater, soft dust on the surface is simply purged through compressed air, dry base powder is sprayed on the plate surface of the heat exchange unit to enable the base powder to cover the scaling area of the plate, auxiliary slurry is sprayed to enable the slurry to cover the base powder, then standing of a body plate of the heat exchange unit is carried out, finally, the scaling area of the body plate of the heat exchange unit is washed through high-pressure water, and air drying is conducted after washing is completed.

Description

technical field [0001] The invention relates to the technical field of ash removal for an air preheater, in particular to a method for removing ash and scale on a boiler air preheater plate. Background technique [0002] At present, coal-fired boilers in thermal power plants generally adopt the selective catalytic reduction (SCR) flue gas denitrification method. Under the ultra-low emission requirements of coal-fired units, it is more difficult to control flue gas denitrification SCR ammonia escape. At the same time, the oxidation of SO2 in the catalyst denitrification reaction process leads to an increase in the concentration of SO3 in the flue gas, and some air preheaters are blocked by ammonium bisulfate ABS. The amount of ammonium bisulfate produced is proportional to the product of NH3 and SO3 content. It reacts as follows: [0003] NH 3 +SO 3 +H 2 O→NH 4 HSO 4 (1) [0004] NH 4 HSO 4 +NH 3 →(NH 4 ) 2 SO 4 (2) [0005] 2NH 3 +SO 3 +H 2 O→(NH 4 ) 2 ...

AI Technical Summary

Problems solved by technology

[0010] The flushing methods of the air preheater in the prior art mainly include online cleaning and offline cleaning: online cleaning includes steam flushing, high-pressure water cleaning, etc., which can mainly wash away loose dirt on the surface and partially alleviate the problem of air preheater blockage; offline cleaning is The air preheater is seriously blocked. During the overhaul of the system, the pyrolysis unit is unpacked and washed. The washing method is high-pressure water washing, alkali washing, etc., and the continuous washing method is adopted, which consumes a lot of washing liquid and discharges waste water, and the economy is poor.