What are the reasons for insufficient burning in the coal chain grate boilers?

The first reason is unreasonable structural design.

In the operation of chain grate boiler, uneven distribution of short coal seams in grate, improper adjustment of coal feeder, unreasonable control of coal seams and poor regulation performance of air supply volume in air chamber will all lead to insufficient burning of coal.

The second reason is unreasonable setting of secondary air.

If the primary wind speed is too high, the air volume is too large, and the air rate is too large, the pulverized coal concentration is obviously low, and insufficient preheating will cause the ignition point of pulverized coal to increase, and successive flames cannot be formed. Improper selection of secondary air distribution will greatly reduce the flame temperature.

The third reason is coal quality.

The basic requirements of the boiler for fuel are very high. The coal with the particle size of 25mm-40mm is less than 30%, the large particle size is less than 40mm, the moisture is 12%-20%, the volatile matter is greater than 18%, the calorific value is greater than 4200 kcal/kg, and the ash melting point is not lower than 1100℃. If the ash content in coal increases and the evaporation content is low, it is not conducive to the dispersed combustion of pulverized coal.