Bag-type Dust Collecting Technology Applied on Zhongding Biomass Boiler
Zhongding Biomass Boiler is a single drum horizontal chain grate steam boiler with mixed water tube and fire tube. The smoke gas is tri-backhauling structure. The boiler body adopt the overhead drum, water wall tube and header in bilateral symmetry form. the spark wall is installed in the boiler furnace to increase the combustion efficiency. After the fuel burn in the furnace, the exhaust gas flow from the boiler barrel bottom to the smoke outlet, then enter the convection bank, then enter teh thread smoke tube through the front smoke box, pass the economizer, dust remover, and ID fan successively, and finally discharged to the atmosphere by chimney.
The efficiency of dust collection is significant related to the design of dust collector on biomass boiler. Zhongding boiler paid more attention to the collector design, to ensure the high dust collection efficiency, stable & safe operation, and long working time.
1. Design on first level cyclone dust collector. The dust collector can catch the dust with the particle size of more than 5μm, the dust collection efficiency is 50%~90%. The input is designed as strombuliform structure. The abrasion-proof material is used for the dust collector.
2. Design on protection system. The dust collector is protected when the boiler is operate abnormal. Bypass is set in the dust removal system, the exhaust gas flow through the bypass when the boiler is operate abnormal. Lift valve is installed at the access of the bypass, and the air door of valve plate is sealed, no air leakage when close. At the same time, pipe powder spraying device is equipped, to protect the filter bag of dust collector when spraying beforehand.
3. Design on pneumatic ash conveying system. Optimize the system to solve the problem of large air consumption and high failure rate. Rearrange the position of assist-blow valve and ash hole, solve the problem of pipe blocking. Reduce the number of bends, reasonable use reducer, and adopt large curvature radius bends, which can reduce energy consumption, increase efficiency and the dust transmission is stable.
4. Design on electric control. Based on the characteristics of biomass boiler dust catcher, the differential gage and temperature detector is equipped for control and protect. The electric heater device and temperature measuring point are set up at the dust hopper. When the temperature of dust hopper wall is higher than the design value, the electric heater device is off automatically, and when lower, the device is on automatically. Also, the system use PLC auto controller to ensure the safe operation.