Return feeder blockage has the following several reasons:
1. The insufficient fluidization air volume control causes large amount of recycling materials to accumulate and jam.
2. Circulating ash cokes due to high temperature at returns device.
3. The refractory shedding causes the return feeder not to be fluidized and be blocked.
4. Return feeder fluidization vent is blocked.
5. Fluidization fan is in failure, so the fluidization air disappears.
6. Carbon content of recycling materials is too high, so the secondary combustion happens in the return product.
7. The loose air duct on the riser duct is blockage or not opened.

Processing methods:
1. Improve the fluidization air pressure appropriately, in order to guarantee the materials in return feeder to be always in a good state. But it shall be noticed that the fluidization air pressure shall not be too high.
2. The temperature of the return product shall be controlled, especially, when the coal with large content of ash and with low melting point are burnt, special attention shall be paid.
3. During actual operation, the shedding of refractory material of returns feeder is more difficult problem of return feeder, which will not only cause return feeder blockage, but also will easily cause burning accidents of the outer wall and partition of the return feeder. To solve this problem, attention shall be paid to the links of construction, baking, and daily maintenance of operation of the refractory materials.
4. The stable operation of the fluidized air blower shall be ensured in order to prevent disappearing of fluidization air and vent blockage accident.
5. The best environment shall be established for the combustion of coal particles in the chamber of as far as possible, in order to reduce the carbon content of recycling materials.
6. Measures shall be taken to unclog the loose duct or open the corresponding loose damper according to the height of material level.