1. Filter bag problem
The progress of bag filter is mainly reflected in the innovation of filter media and the change of cleaning methods. The filter bag is the heart of the bag filter. The maintenance cost of the filter bag is the largest proportion in the maintenance cost of the filter. , up to 70% of the maintenance costs. The filter bag is the most critical factor in determining the performance of the filter. The main factors causing filter bag damage are: high temperature burn, corrosion, mechanical damage, installation quality, product quality, operation, management and other reasons.
1.1 High-temperature smoke damage to the filter bag
(1) High temperature burned
High temperature damage to the filter bag is fatal. For example, in a pulverized coal drying kiln in Heilongjiang, because the pulverized coal particles after drying are very fine and sticky, the cleaning is not ideal, leaving a large amount of dried pulverized coal on the surface of the filter bag, and the pulverized coal after drying is very flaming. Low, when the high-temperature flue gas enters the dust collector, it will rapidly ignite the coal powder on the surface of the filter bag, causing the filter bag and skeleton of the entire dust collector to be completely destroyed. As can be seen from FIG. 1, a large amount of dried pulverized coal remains on the surface of the filter bag, and it can be seen from the upper left corner that the box is burned.
(2) Mars burning through
In addition to high-temperature burning, Mars in the flue gas damages the filter bag is also very serious. Such as coke oven, drying kiln, chain furnace, cupola furnace, electric furnace, blast furnace, mixed iron furnace, etc. in the production process will have a large amount of Martian mixed into the flue gas, such as the Mars processing is not timely, especially the filter bag surface dust layer When thin, Mars will burn through the filter bag, forming an irregular round hole (Figure 2). However, when the dust layer on the surface of the filter bag is thick, Mars will not directly burn the filter bag, but it will cause deep color baking marks on the surface of the filter bag.
(3) high temperature shrinkage
Another high temperature flue gas filter bag damage is the high temperature shrinkage, although the use of each filter temperature is different, but when the flue gas temperature exceeds its use temperature, such as the warp shrinkage is too large, will make the filter bag in the length The dimension becomes shorter in the direction, and the bottom of the filter bag is tight against the skeleton and is damaged by the force (see Figure 3). If the heat shrinkage of the filter bag is too large, the filter bag will become smaller in the radial direction, and the filter bag will be tightly clamped on the frame, and even the frame cannot be pulled out. So that the filter bag has been under stress, resulting in shrinkage of the filter bag, hardened, brittle, and accelerate strength loss, shorten the life of the filter bag. Because the filter bag will be tightly hooped on the skeleton after deformation, the filter bag will be difficult to deform during the cleaning process, which is unfavorable for cleaning and cleaning, resulting in high filter bag resistance.
(4) ash bucket heat storage burned filter bag
After high-temperature dust is collected in the ash bucket, if it is not discharged in time, the dust will accumulate in the ash hopper for a long time and cause the temperature in the ash bucket to rise continuously. The filter bag will become brittle and harden under high-temperature baking for a long time, and when it is serious, it will Burned, especially the flammable substances contained in the dust, will burn in the ash bucket and burn the filter bag. [6]
1.2 filter bag corrosion
Corrosion is one of the most common causes of filter bag damage. Because the smoke contains a variety of corrosive substances, and the corrosive effect is greater in a high-temperature environment, the filter bag may be damaged. The main causes of corrosion are hydrolysis, oxidation, acid and alkali corrosion. Among them, the main causes are hydrolysis and oxidation, while the acid corrosion is less and the alkali corrosion is less.
1.3 mechanical damage
Because the filter material factory pays more attention to the quality of the product, the filter material generally does not cause mechanical damage and other quality problems before leaving the factory. Mechanical damage is mainly caused by wear during transportation, installation, and operation. [7]
1.4 Design issues
Reasonable design is the premise to ensure the life of the filter bag, but in the design process of the bag filter is often over-focused on various economic indicators, and it is easy to overlook the rationality of the airflow field distribution in the filter box. Due to the unreasonable distribution of the air flow, the speed between the bags may be too fast, and the phenomenon of damaging the filter bag occurs from time to time. The most typical is the early mechanical revolving flat bag dust collector. The density of the filter bags inside the filter box is the largest among the existing dust filters, which causes the air flow to damage the filter bags. Unreasonable length and diameter ratio of the filter bag may also cause the bag mouth to be too fast and wear the filter bag.
2. Measures
Timing cleaning boiler dust collector is to sample the pressure difference between the inlet and outlet of the dust collector and convert it into electric signal by differential pressure transmitter. The working process is as follows: The pressure transmitter and outlet of the inlet and outlet pressure equipment Ash Controller Relay Solenoid Valve Cylinder Lift Switch Valve In addition to the above two control methods, a manual control mechanism is also provided to manually perform normal dust removal control. The
For the convenience of operation and management, it is recommended to use the timing method of cleaning. The
Take the following measures in the dust collector system:
(1) Insulation measures must be taken at the air intake duct, body and ash hopper of the dust collector to prevent dew condensation.
(2) A temperature detection and automatic alarm device is installed at the inlet and exhaust ports of the dust collector, and a cold air inlet device is installed at the air inlet. Once the flue gas exceeds the use temperature range of bag dust removal, an alarm occurs and automatic temperature control measures are taken to ensure safe operation of the dust collector. The
(3) An electric heating and rapping device was installed on the ash bucket to avoid the problem of ash formation caused by low temperatures. Boiler dust remover is suitable for dust removal and desulphurization, featuring low resistance, flexible installation, high desulfurization efficiency and long service life.