CFB boiler is a new type of furnace with high efficiency and low pollution developed after chain furnace and pulverized coal furnace.
Because of its advantages of high combustion efficiency, wide adaptability of coal, large load regulation range, low nitrogen oxide emission and easy desulfurization, it has been widely used and promoted in the world. However, the prominent wear problem seriously restricts the long-term economic operation of the furnace type.
1, circulating fluidized bed boiler wear
1) Wear problems in circulating fluidized bed boilers
Because the ash concentration in the circulating fluidized bed boiler is high, usually tens of times, hundreds of times, or even thousands of times that of the pulverized coal furnace, the wear of the circulating fluidized bed boiler is much more serious than that of other types of boilers, and the anti-wear problem of heating surface and refractory materials should be paid special attention. How to solve the wear problem is directly related to the success or failure of the CFB boiler design, and also directly affects the availability of CFB boiler units.
2) The form of wear
According to the different wear mechanism, wear can be divided into adhesive wear, abrasive wear, corrosion wear, contact fatigue wear, erosion wear, fretting wear and so on. The wear caused by the impact of fluid or solid particles on the surface of a material at a certain speed and Angle is called erosion (or impact wear). There are two basic types of erosion, respectively called erosion wear and impact wear, and the micro-morphology of the erosion surface loss process of these two kinds of wear is completely different.
The partial velocity of the particle perpendicular to the solid surface makes it wedged into the impacted object, and the partial velocity of the particle tangent to the solid surface makes it slide along the solid surface. The combined effect of the two partial velocities is a kind of planing effect. If the impacted object cannot withstand this effect, that is, a small piece is cut off, so after a lot of repeated action, the solid surface will wear.
Impact wear refers to the particle relative to the solid surface impact Angle is large, or close to the vertical, at a certain speed impact on the solid surface to produce a small plastic deformation of the microscopic crack, in the long-term a large number of particles repeatedly impact, gradually make the plastic deformation layer of the whole piece off and formed wear.
According to the different wear mode, wear can be divided into two objects wear, three objects wear. In the wear of two objects, the solid impinges and erodes the wall with its own momentum. In three-body wear, solid particles moving along the wall are impacted by particle clusters, and particle clusters use the former as the wear medium to wear the heating surface.