(1) In the combustion process, the temperature of fuel layer is higher than the softening temperature of ash, which is an important reason for the formation of slag. At the ash deformation temperature, ash particles usually do not form slag, but when the softening temperature is reached, the eutectic formed by the melted ash can not be sufficiently cooled, so it will stick to the water-cooled wall and cause the formation of slag.

(2) The surface roughness of boiler wall tube is another important reason for the formation of slag. The rough surface is easy for ash bonding, so that the temperature of the combustion chamber and the temperature of the tube wall rise due to heating, and then reach the melting point temperature of the fuel ash, thus entering the state of melting or softening, and the adjacent high-temperature melt bond together, which will lead to slagging.

(3) In the process of combustion, there is insufficient air, and the ferric iron in the fuel layer is reduced to ferric iron, and the melting point of iron is lower than the existence of iron, and the form of iron exists in the form of iron +2, so the melting point of fuel ash is greatly reduced and coking results.

(4) Insufficient mixing of fuel and air, even if the air supply is sufficient, will still cause partial air shortage, reducing atmosphere, reduce the melting point of fuel ash and cause coking.

(5) Unreasonable wind speed leads to the flame in the furnace to one side, resulting in part of the temperature is too high, thus making the temperature of some fuel layers rise to the melting point of ash, if the cooling is slow, it will lead to coking.

(6) Overload operation of the combustion device, furnace temperature is too high, so that the temperature of the fuel layer increases, to reach the ash melting point of the fuel, the formation of slag.

(7) The large fuel diameter and thickness of the fuel layer in the furnace combustion furnace will lead to the excessively high local temperature in the combustion center of the furnace layer, and the ash melting point of the fuel will lead to the formation of slag.

Troubleshooting:

(1) The producer of biomass fuel pellets should control the impurities in the material and should minimize sand and other sundries.

(2) Adjust the compression ratio. Under the condition of ensuring the rate of particle formation, decreasing the compression ratio will increase the burning surface.