Study On Operation Characteristics Of Pulverizing System In Thermal Power Plant

As an important system to provide the fuel for furnace,the milling system directly affects the fineness and uniformity of the pulverized coal,and it is a key equipment and source to ensure the stable combustion of the furnace,improve the combustion efficiency and reduce the pollutant discharge.At the same time,reducing its efficiency is also one of the most efficient means to increase the economy of the whole plant.Due to the difference of coal quality,boiler characteristics and operation mode of the thermal power unit,it is difficult to find a generic operating scheme for different thermal power units.The analysis of the characteristics of the pulverizing system for the thermal power unit can help to discover the defects of the system and find the efficient operation mode.Taking the pulverizing system of #1-#4 furnace of Guizhou Dafang power plant of China Huadian Corporation as the research object,the fineness,uniformity index and pulverized coal particle size distribution were studied.The main work and achievements of this thesis are as follows:1)The effect of the separator speed on the fineness of the pulverized coal was studied.The results show that the averaged R90 is 15%-20% for the mill D of #2 furnace,which is much higher than the others on the same working condition.It is clear that its coal separator,primary air or pulverized coal pipe has some problems or defects.When the separator speed of #4 furnace's mill A increase,the coal powder fineness has no significant difference,and the uniformity index randomly change.The results show that the separator performance of #4 furnace's mill A is poor,and it is necessary to maintain.2)The effect of the separator speed on the uniformity of the pulverized coal was carried out.The results showed that the homogeneity index of the mill A and D of #3 furnace was reduced to 0.72 and 0.77 respectively when their speeds were reached at 110 r / min.Since that,the separator speed of mill A and mill D should not exceed 100 r / min.3)Through the analysis of the relationship between pulverized coal output and pulverized coal fineness and homogeneity index,it is found that the R200 value of mill A of #2 furnace increase will cause the pulverized coal increases rapidly,that is,the large particles increase and the uniformity index decreases.For mill D of #3 furnace,with the increase of output,the R200 value and the uniformity index are randomness.For mill A of #4 furnace,the uniformity index decreased rapidly when its output exceed 27t/ h.It can be seen that the ratio of steel ball in these three mills need to be optimized.4)Through the above experimental data analysis and diagnosis,the optimization scheme of milling system was worked out.And the results of the operation demonstrate the effectiveness of the scheme.