In the current coal-fired boiler bag dust removal equipment
, the cost of the bag of the dust
collector accounts for 1/3 of the total cost. Therefore, how to extend the life of the bag of the boiler dust collector and reduce the energy consumption of dust removal are particularly critical. Below we introduce some boiler bag dust collector Filter bag
ultra-high temperature protection measures:
1 High-temperature coal-fired boiler baghouse dust collector cooling air cooling This kind of protection is to set an automatic control valve for low-temperature air (generally the atmosphere) on the flue in front of the inlet baffle door of the boiler baghouse dust collector. Under normal circumstances, the valve is closed. When abnormal working conditions occur (smoke temperature exceeds the temperature that the filter bag can withstand), the valve opens automatically and the cold air is cooled to protect the dust bag
. The following points need to be paid attention to when adopting such protection and cooling measures:
(1) Generally, the position of the inlet cold air needs a certain distance from the bag filter of the boiler. Because the general smoke speed is relatively high, the hot and cold air must be fully mixed to achieve the effect of cooling. If the hot and cold air cannot be fully mixed, local overheating and dew condensation may occur, which is not conducive to the bag filter.
(2) The selection of air intake volume should be reasonable. The amount of incoming cold air is too large, and the capacity of the induced draft fan must be increased. A safety door with sufficient capacity must be provided on the outlet flue of the boiler dust collector. The amount of cooling air is large, which has a great impact on the negative pressure of the furnace, which is not conducive to the stable combustion of the boiler and the automatic control of the unit.
(3) Because the oxygen content in the flue gas is significantly increased after entering the cold air, some filter materials are very sensitive to the oxygen content in the flue gas, so it should not be used on bag filters using this filter material. Cooling protection measures.
2 Water spray mist cooling This protection measure is to install a set of atomizing nozzles for cooling in the flue of the inlet valve of the boiler bag dust collector, and the communication pipe of the nozzle is connected to the pressure water source through an automatically controlled solenoid valve. Under normal circumstances, the solenoid valve is closed. When abnormal working conditions (temperatures that the smoke filter can withstand) can occur, the solenoid valve opens automatically, and the pressure water is sprayed through the nozzle to be atomized, and the heat absorption is reduced when mixed with the flue gas. Smoke temperature protects the filter bag.
Pay attention to this measure:
(1) The farther the nozzle is from the bag filter, the better. Because the general smoke speed is relatively high, it is necessary to allow the atomized water droplets and the flue gas to fully mix and vaporize and absorb heat to achieve the effect of cooling. Otherwise, the phenomenon of local condensation and corrosion is easy to occur.
(2) If mechanical atomization is used, the nozzle selection and water source parameters should be selected to ensure that the diameter of the droplets after water atomization is as small as possible. In addition, the water quality should be good and free of impurities, otherwise a filter must be installed. When not spraying water, let a small amount of air continuously enter to prevent nozzle clogging.
(3) If the gas phase atomization is adopted, the problems of the particle diameter of water mist and the prevention of nozzle blockage are easier to solve, but it is necessary to avoid the occurrence of pressurized water entering the compressed air system.
(4) After spraying water in the flue gas, the particles of the water mist will adhere to and settle with the dust particles in the flue gas before being vaporized, or stick to the inner wall of the flue. Therefore, it is necessary to consider the design of inspection methods, and add ash or anti-corrosion measures if necessary.
After adopting the above-mentioned two types of cooling protection measures, due to special reasons, the smoke temperature cannot be reduced to the normal working range, which can only reduce the load urgently or stop the furnace to avoid unnecessary accidents.
3 Bypass protection Bypass protection is to set a bypass valve on the inlet and outlet flues of the boiler bag filter. When the smoke temperature exceeds the temperature range that the filter bag can withstand, or the pressure difference of the filter bag is greater than the set value and cannot be lowered, the bypass valve opens automatically, the inlet and outlet valves of the bag filter are closed, and the flue gas passes directly through the induced draft fan. To the chimney.
There are two types of bypass valve: internal and external. The built-in bypass valve is arranged on the inlet and outlet flues passing through the body of the bag filter, and has a compact structure. Although this kind of bypass valve protection measures can effectively protect the baghouse dust collector, the flue gas goes directly to the induced draft fan without dust removal, which causes severe abrasion of the induced draft fan and direct discharge is not allowed. Therefore, this protection measure can only provide instant protection when the smoke temperature exceeds the limit, and then the boiler should be shut down as soon as possible.
The tightness of the bypass valve is very important if this bypass protection is taken. Because as long as the bypass valve leaks a little, it doesn't take long, the sealing surface of the bypass valve will be severely damaged, the leakage will increase significantly, the discharge will exceed the standard, and the suction fan will be seriously worn and damaged. The built-in bypass valve is difficult to achieve long-term tightness in flue gas with temperature changes.