The bag-filter is widely used in boiler flue gas treatment of thermal power plants because of its high dust removal efficiency, low energy consumption, simple process principle and adaptability to different types of coal.In the process of dust removal using bag-filter for boiler in thermal power plant, it is necessary to pay attention to the maintenance of equipment during operation, and analyze the factors affecting the service life of bag-filter, so as to effectively improve the service life of bag-filter by means of inspection, maintenance and maintenance.This paper mainly introduces the factors that affect the service life of cloth bag filter and its operation and maintenance.
Factors affecting the service life of dust remover
The life of the cloth bag filter is a comprehensive index, but the filter bag is said to be the core of the comprehensive index of the filter, so the maintenance and maintenance of the filter bag is very important, and the life assessment is mainly to test the performance of the filter bag itself, such as temperature resistance, acid and alkali resistance, oxidation resistance and so on.Therefore, the discussion on the life of the bag filter is limited to the analysis of the filter bag and related factors.
The effect of filter bag material
Normal temperature dust removal filter bag includes: polyester needle-felt filter bag, anti-static polyester needle-felt filter bag, easy-to-remove gray polyester needle-felt filter bag, polyester film-coated needle-felt filter bag and other materials.These can be used at room temperature for a long time.There is another kind of high-temperature dust removal filter bag, which mainly includes: meitas needle-felt filter bag, flumese filter bag, glass fiber needle-felt filter bag, PPS acid-alkali needle-felt filter bag and other high-temperature resistant materials.
Damage of high temperature to filter bag
When the temperature of the smoke is more than 160 ℃, the temperature has a significant effect on life of filter pocket, with the increase of temperature wreck a gradually increasing life of filter bag, filter material reaches a certain temperature to have burned (determined according to the filter bag material), and because the coal mixed with other chemicals, when high temperature smoke will accelerate chemical reactions, filter material easy to oxidation, the intensity is abate, easily broken, the life of the wreck will more and more serious, resulting in corrosion of filter bag.Therefore, the smoke exhaust temperature should be strictly controlled during operation to prevent the occurrence of long-term overtemperature operation and sudden temperature rise within a short time.
Effect of low temperature condensation on filter bag
Early winter point when the boiler furnace or low load operation, flue gas temperature is lower, and the factors of local air leakage, prone to local temperature below the dew point temperature, so there will be a condensation phenomenon, and the reaction with SO2 in flue gas to form acid dew, acid mist, causing corrosion of filter bag, the characteristic parameters of filter bag down, serious when can cause massive harden and filter bag reaches a certain weight will cause the filter bag, the serious influence the service life of filter bag.In addition, the north of winter cold, if the insulation is not good, easy to cause dust bucket inner wall, cause dust bucket blocking phenomenon.And the point furnace at the beginning of the dust bucket for negative pressure, the lower hydraulic ash removal moisture will be brought into the dust bucket, also easy to cause dust hanging walls of the inner wall of the dust bucket, causing serious consequences.
The influence of filter wind speed on filter bag
The filter wind speed is an important factor to determine the performance of dust remover.Too high, will cause excessive pressure loss, making filter bag clogging and rapid damage.Generally speaking, for the dust concentration of high, fine particles, wear large dust smoke, the filter wind speed should be smaller, on the contrary, choose the wind speed is larger.Because the filter wind speed value of the cloth bag filter will increase the resistance, dust layer due to compression porosity reduction, airflow will break through from the dust bag weak place, "perforation" phenomenon, the larger the filter wind speed dust bag "perforation" phenomenon is more serious, so it is necessary to control the filter wind speed.
Destructive effect of ash removal on filter bag
In order to keep the pressure difference of the filter bag running at the design value, the fly ash attached to the surface of the filter bag should be cleaned regularly, but the ash cleaning mode or parameters of the ash cleaning system have a great impact on the life of the filter bag.For vibrating, vibration type or high, medium voltage pulse inverse blow type ash removal system effect is not very big, and low pressure pulse blowing ash removal system is different, its destruction mechanism is mainly due to the outside using a filter filter, filter bag inside the bag cage, and thus the relative games between the filter bag and bag cage wear, coupled with the frequent blowing soot cleaning, filter bag and bag cage contact closely, with spacing and twists and turns the magnitude of the changes are directly affect the service life of filter bag.
Influence of air inlet mode on filter bag
What kind of air inlet mode is adopted will directly affect the service life of filter bag. It is necessary to ensure that the pressure difference of several Chambers is relatively average.Once the differential pressure increases in one chamber, most of the flue gas enters other Chambers, balancing the differential pressure.However, if some filter bags leak in one chamber, the resistance of flue gas passing through the filter bag will be reduced, and the pressure difference of the chamber will be reduced. Therefore, most of the flue gas will enter the chamber, increasing the flow flux and aggravating the wear of the filter bag at the same time.Therefore, the choice of reasonable air inlet mode is also an aspect that affects the life of filter bag.
Operation and maintenance of dust remover
1. Pre-coating after filter bag replacement
After replacing the filter bag, pre-coating must be carried out before putting it into operation, or if it is out of service for a long time, it should be carried out again, so as to establish a surface filter bed on the surface of the filter bag and reduce the pollution of oil or other substances on the filter bag.Pre-coating should be done by using suction fan before boiler spot. After pre-coating, check whether the coating of filter bag is uniform and whether the differential pressure of each chamber is average.
2. Maintenance of ash cleaning gas source system
Control of ash cleaning pressure: control the air pressure of ash cleaning between 0.08 and 0.1mpa in operation, so that it can not only reduce the damage of backblowing to filter bag, but also not affect the effect of ash blowing.
Setting value of ash cleaning pressure difference and adjustment of ash cleaning frequency: three ash cleaning modes (slow, medium and fast) under different dust load of filter bag body.The setting of switching point parameters must consider the service life of the filter bag to control the difference pressure of the dust collector within a reasonable range.In practical operation, the pressure difference should be kept within a reasonable range and the frequency of ash cleaning should be lowered as far as possible.
When the pulse valve or pipeline leakage phenomenon, causes the ash cleaning pressure drop, the way of ash cleaning from slow to fast, the system pressure difference increases.At this time, it is necessary to find out the leakage point in time, judge the leakage position, disentangle the leakage chamber operation if necessary, and contact with it to prevent serious consequences caused by unstable system parameters.
3, before the point of the furnace to heat the bottom of the ash bucket in advance, to ensure the temperature of the ash bucket to reach 80℃, to prevent the steam in the flue gas encountered the cold inner wall of the ash bucket, resulting in condensation will not hang the wall phenomenon.
4, the filter bag should take measures to check regularly, through the window, pressure difference change, solution room inspection and other means, timely find the filter bag leakage phenomenon, and immediately replace the wear filter bag, prevent the smoke into the clean air room caused by large area of filter bag blockage, damage and other accidents, affect the service life of the dust collector.
