What is included in the built in bypass system of boiler bag filter

If it is built-in, it is generally a sealed fan. However, due to installation reasons, when the temperature of the boiler rises after operation, there will be a certain deformation leading to leakage, and there is no good way at present.

If it is bypassed, the material cost will increase a lot.

Bypass protection is to set a bypass valve on the inlet and outlet flue of the bag filter. When the flue gas 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 is automatically opened, the inlet and outlet valves of the bag filter are closed, and the flue gas is directly discharged to the chimney through the induced draft fan. There are two types of bypass valves: built-in and external.

The built-in bypass valve is set on the inlet and outlet flue through the bag filter body, and the structure is compact.

Although this bypass valve protection measure can effectively protect the bag filter, the flue gas is directly to the induced draft fan without dust removal, and the wear and tear of the induced draft fan is very serious; And direct emissions are also not allowed. Therefore, this protective measure can only play a momentary protective role when the flue gas temperature exceeds the limit, and then the boiler should be shut down as soon as possible.

If this bypass protection is to be taken, it is very important that the bypass valve is tight. Because as long as there is a little leakage of the bypass valve, it will not take long for the sealing surface of the bypass valve to be seriously blown and damaged, the leakage will increase significantly, the discharge will exceed the standard, and the suction fan will be seriously worn and damaged. It is difficult to achieve long-term tightness in flue gases with variable temperatures with built-in bypass valves.

In order to solve the leakage problem, foreign countries have designed and manufactured double shutter baffle doors. This baffle valve has two layers of louvers, between which low-pressure compressed air is always filled and heated so that the double louvered baffle valve does not leak smoke.

Generally, boiler bag filters have off-line valves and bypass valvesOff-line valvesIt is one for each silo chamber, and when the pulse valve is cleaned, it plays a role in closing a silo to achieve off-line cleaning. The bypass valve is the self-protection of the dust collector under the boiler ignition oil injection and flue gas temperature abnormalities and other boiler accident conditions, and can timely alarm and send a signal through the control system to open the bypass valve in time, so that the high temperature abnormal flue gas is directly discharged from the flue without passing through the filter bag, so as to avoid damage to the filter bag. The off-line valve is equipped with one in each chamber of the boiler dust collector, so that the boiler dust collector has the functions of offline cleaning and offline maintenance.

The poppet valve is a thin plate structure. Controlled by the cylinder, the valve cylinder seal is imported products, and the voltage level of the two-position five-way solenoid valve is 24V. The whole set of valves is simple and reliable, the opening and closing speed is fast, and one or more silos can be controlled to work at the same time through PLC, and one or more silos can be closed for off-line ash cleaning and off-line maintenance.

When the poppet valve and the manual switching valve are closed, it can ensure that the silo is completely offline, and realize the single-bin maintenance under the working condition of the dust collector (the manual switching valve can also be used to adjust the air intake), and the limiting device on the poppet valve can enable the operator to detect its operation status in time. The boiler dust collector off-line valve (or poppet valve) adopts the form of pneumatic quick-opening gland, which is a simple and reliable linear motion to avoid the trouble caused by the high rotation failure rate. The sealing ring is made of acid-alkali resistant and high-temperature resistant fluoroelastomer, and the general temperature resistance reaches 250 degrees.

Boiler bag filter bypass valve (or bypass valve).It adopts the form of pneumatic quick-opening gland, which is a simple and reliable linear motion and avoids the trouble caused by the high rotation failure rate. The cylinder controls the up and down movement of the valve plate, and the sealing ring is made of acid-alkali resistant and high-temperature resistant fluorine rubber, and the general temperature resistance reaches 250 degrees, which ensures zero leakage, ensures the self-protection of the dust collector under the boiler ignition oil injection and flue gas temperature abnormalities and other boiler accident conditions, and can alarm in time through the control system. The bypass valve is a thin plate structure.

Controlled by the cylinder, the valve cylinder seal is imported products, and the voltage level of the two-position five-way solenoid valve is 24V. The whole set of valves is simple and reliable, and the opening and closing speed is fast. The bypass flue of the boiler dust collector, when the boiler (or incinerator) is started, the bypass flue is opened to prevent the oil from burning badly during ignition, the oil sticks to the filter bag, and the filter bag is burned in case of open flame.

When the boiler has an accident, when the exhaust gas temperature exceeds the allowable temperature of the filter bag, the bypass is opened and discharged directly.

Most of the possible impact of limited or cancelled bypass openings has not been realized, that is, there has not been a situation where the main engine has been forced to shut down due to the maintenance of the desulfurization equipment; The boiler MFT, unit RB, and inlet flue gas temperature are also turned on when the inlet flue gas temperature is high, and the resulting flue gas system instability and the risk of damage to the internal components of the absorption tower do not exist for the time being. The inlet flue gas temperature is low, the occurrence is not much, the duration is short, the sulfur content of the coal type is generally not very high this year, and the capacity of the bag filter system of the boiler of the desulfurization equipment can still be buffered, so for these two situations, the power plants can basically not open the bypass. In the start-stop stage of the boiler, Zhejiang gives each furnace of the power plant 12 hours a year as the bypass can be turned on, which includes the regular test of the baffle and the abnormal opening time of the baffle during the unit network. In response to this requirement, the current power plant adopts the mode of synchronization between electrostatic precipitator operation and boiler ignition, and desulfurization operation and unit grid connection (10MW) synchronization.

When the boiler bag filter equipment is turned on, the power supply of the control equipment should be turned on first, the gas storage tank should be connected, and the ash discharge device should be turned on. If there are other system devices, the downstream devices need to be started first.

2. When stopping the boiler bag filter equipment, there is no need to cut off the compressed air, when the fan is working, in order to ensure that the poppet valve is open, it is necessary to provide compressed air to the poppet valve.

3. If the solenoid valve of the equipment fails, the fault should be eliminated immediately. The inside of the magazine, moisture, etc., should be cleaned immediately, and the diaphragm should be replaced if the diaphragm is damaged.

4. The oil-water separator (in the air storage tank and air source triplet) should be cleaned once in 3-6 months, and the oil storage of the lubricator should be checked at any time.

5. The boiler dust collector cannot stop the ash discharge device when it is working normally.

There is no harm, just that it is harmful to the air environment and increases dust.

There is no harm to the boiler for the bypass of the bag filter, but it is currently forbidden to install a bypass for environmental protection equipment.