1, flue gas flue gas temperature distribution is uneven lead to boiler economizer tube thermal fatigue. The traction force of the wind blower and the inertia of the flue gas flow cause the furnace outlet and the vertical flue there is a large rotating air flow, and the rotating air flow is superimposed to cause the rear wall side to be larger than the front wall side, so that the economizer Road smoke rate is different, resulting in flue shaft temperature distribution deviation, left and right side of the smoke temperature deviation of 40-80 degrees Celsius.
2, the sulfur in the gas on the erosion of the economizer tube. Due to blast furnace, coke oven gas in the presence of S, Cl and other harmful impurities, the combustion process of sulfur dioxide, sulfur dioxide, hydrogen sulfide, hydrogen chloride and other acid gases, a variety of chemical substances at high temperatures common wall corrosion, sulfur compounds In the high temperature to produce single-atom sulfur, sulfur and pipe iron reaction to produce iron sulfide, which causes corrosion of the pipe wall.
3, flue gas and ash particles impact corrosion. The flue gas in the middle of the boiler economizer connection pipe leads through the flue, there is eddy current, eddy current area on the connecting pipe between the static pressure distribution and branch pipe resistance coefficient have an impact, resulting in flue gas in the economizer tube bundle velocity is uneven, Flue gas corrosion and gray powder particles in the metal surface alternately, due to the economizer tube metal wear and flue gas flow rate is proportional to the power of the third, resulting in large smoke where the wall wear thinning serious, boiler operation The increase in the flue gas flow rate increases the wear rate, and the calculated excess air ratio increases from 1.2 to 1.3, and the economizer tube wear increases by about 25%.
4, economizer tube material quality is relatively poor, part of the existence of surface damage caused by leakage.
5, the installation of economizer pipeline process does not meet the requirements, resulting in increased internal stress, interface welding when slag, bubbles, oxidation and other phenomena did not find rework in time to put into use.