Does anyone know what the particle size of pulverized coal in a pulverized coal boiler is?

　　The particle size of pulverized coal in pulverized coal boilers should be called pulverized coal fineness according to the standard. 　　The percentage of the amount of pulverized coal separated by a standard sieve according to the prescribed method to the total amount of pulverized coal is called the fineness of the pulverized coal. 　　The fineness of pulverized coal can also be expressed by the percentage R of the remaining pulverized coal remaining on the sieve and the total pulverized coal. That is, R=a/(a+b)×100% where a——the mass of remaining pulverized coal remaining on the sieve, kg ； 　　b——The total mass of pulverized coal passing through the sieve, kg. 　　It can be seen that the more mass of remaining pulverized coal remaining on the sieve, the greater the R value of pulverized coal fineness, indicating that the coarser the pulverized coal is. 　　The sieves used for screening are of certain specifications. Commonly used pulverized coal screen specifications are shown in the table below. 　　　　　　　　　　　　　　　Specifications of commonly used pulverized coal sieves Screen number Number of sieve grids per centimeter of length Number of sieve holes per square centimeter Mesh width (μm) Wire diameter (μm) 10 10 100 600 400 30 30 900 200 130 50 50 2500 120 80 70 70 4900 90 55 80 80 6400 75 50 100 100 1000 60 40 In the past, the fineness of coal powder was expressed by screen number, such as R30 and R70. Nowadays, the mesh width is used to express the fineness of pulverized coal, such as R30 is changed to R200, and R70 is changed to R90.