During the construction of the CFB boiler furnace, refractory castable is selected for large-area construction mainly due to its convenient construction and high service performance. However, CFB boilers themselves are prone to severe wear. What should be done if the wear-resistant refractory castable falls off due to serious wear in the worn areas? How to remedy it?
The shedding of wear-resistant refractory castable in the worn areas will cause the local heating surface to be directly scoured by high-temperature flue gas. This not only increases the thermal deviation of the heating surface but also rapidly accelerates the pipe wall wear, making pipe explosion accidents likely to occur. In addition, the shedding of wear-resistant refractory castable in the cyclone separator will lead to poor fluidization of bed material in the separator, and in severe cases, normal material return cannot be achieved, directly affecting the operation of the boiler.
The main reasons for the shedding and damage of wear-resistant refractory castable in the dense phase zone are as follows: unreasonable design during construction, such as improper density, height, and material selection of pins and studs; the composition of the selected wear-resistant refractory castable does not meet the requirements, affecting indicators such as stability, cold crushing strength, hot modulus of rupture, wear resistance, thermal shock resistance, and reheating linear change rate; poor construction technology, such as failure to construct in accordance with requirements regarding the quality, quantity, and temperature of mixing water, ambient temperature, curing, and formwork removal; insufficient reserved expansion joints; excessively fast temperature rise rate during boiler baking and insufficient constant temperature time; improper operation during operation, such as excessively fast temperature rise and fall during boiler startup and shutdown, and drastic fluctuations in bed temperature, which can all cause cracking and shedding of the wear-resistant refractory castable used in the worn areas.
Solutions for the shedding of wear-resistant refractory castable in CFB boilers:
Appropriate wear-resistant refractory castable should be selected according to the environment of the equipment. The material must be high-strength wear-resistant refractory castable with good hot modulus of rupture. A sufficient number of metal pins should be designed in the wear-resistant refractory castable, and their length should basically penetrate the wear-resistant refractory layer. Stainless steel fibers can also be added to the wear-resistant refractory castable according to construction requirements to ensure that large-area shedding does not occur when cracks form.
