What Is a Dust Separator?

The dust collector is a device that separates dust from the flue gas, called a dust collector or a dust removal device. The performance of the dust collector is expressed by the amount of gas that can be processed, the resistance loss when the gas passes through the dust collector, and the dust removal efficiency. At the same time, the price, operation and maintenance costs, length of service life and ease of operation and management of the dust collector are also important factors to consider its performance. Dust collector is a commonly used facility in boilers and industrial production.

The dust collector is a device that separates dust from the flue gas, called a dust collector or a dust removal device. The performance of the dust collector is expressed by the amount of gas that can be processed, the resistance loss when the gas passes through the dust collector, and the dust removal efficiency. At the same time, the price, operation and maintenance costs, length of service life and ease of operation and management of the dust collector are also important factors to consider its performance. Dust collector is a commonly used facility in boilers and industrial production.

Dust extraction hoods are set up in each ash-emitting place, and the dust-containing gas is sent to the dust removal device through the pipeline gas path. After the gas-solid separation is performed therein, the dust is collected in the dust removal device, and the clean gas is introduced into the main pipe or The whole set of equipment directly discharged into the atmosphere is the dust removal system, and

According to the principle of action, the dust collector can be divided into the following types:

1.Dry type mechanical dust collector mainly refers to the dust removal equipment designed by applying the inertia effect of gravity and gravity, such as high concentration dust collector such as sedimentation chamber, inert dust collector, cyclone dust collector, etc., mainly for high concentration coarse particle diameter dust For separation or concentration.

2. Wet type dust collectors rely on hydrophilicity to remove and collect dust particles, such as spray towers, scrubbers, impact dust collectors, venturi tubes, etc., which process high concentrations and large air volumes that occur during the production process. More dusty gas occasions are used. The separation efficiency of coarser, hydrophilic dust is higher than that of dry mechanical dust collector.

3. The particle layer dust collector uses the stacked layers of granular materials of different sizes as filter materials to block the dust contained in the gas solution. It is mainly used for dust extraction in the production process of building materials and metallurgy. It is often used to filter dusty flue gas with high concentration, coarse particles and high temperature.

4.

AQ Bag Dust Collector for Coal Mine

DL / T 514-2004 electrostatic precipitator

JB / T 10341-2002

The work of the dust collector not only directly affects the reliable operation of the dust removal system, but also relates to the normal operation of the production system, the environmental hygiene of the workshop and the surrounding residents, the wear and tear of the fan blades, and the life of the fan blades. Recycling issues. Therefore, the dust collector must be properly designed, selected and used. When selecting a dust collector, you must fully consider the one-time investment and operating costs, such as dust removal efficiency, pressure loss, reliability, one investment, floor space, maintenance management, and other factors, according to the physical and chemical properties, characteristics, and production of the dust

The technical performance indicators of the dust collector mainly include dust removal efficiency, pressure loss, processing gas volume and load adaptability. ^[3]

Negative pressure back blow filter bag dust collector

Negative pressure back-blow filter bag dust remover to treat industrial boiler exhaust gas pollution. Practice has shown that the filter bag dust collector has a low investment, a small footprint, a large filtering area, stable work performance, high purification efficiency, reliable use, and convenient recycling of dry soot, which effectively protects the environment and has a good performance. It can meet the requirements of the current environmental protection law and a reliable and efficient dust removal device.

In order to effectively control the boiler exhaust gas pollution, the plant based on a comprehensive inspection and study of filter bag dust removal technology, combined with horizontal quick loading

Bag filter

The working principle of the dust collector is as follows: the dust-containing gas enters the filter room from the open flange at the lower part, and the coarse particles directly fall into the ash bin. The dust-containing gas is filtered by the filter bag, and the dust is retained on the surface of the bag. The clean room is exhausted into the atmosphere by a fan. When the dust on the surface of the filter bag continues to increase, the program controller starts to work, and the pulse valve is opened one by one, so that the compressed air is blown through the nozzle to clean the filter bag, so that the filter bag suddenly expands. The dust quickly leaves the filter bag and falls into the ash bin, and the dust is discharged from the ash discharge valve.

The dust collector is mainly composed of an upper box body, a middle box body, an ash hopper, an air inlet equalizing pipe, a support filter bag, an injection device, and an ash discharge device. Dust-containing gas enters the ash hopper of each compartment from the air inlet equalizing pipe of the precipitator, and under the guidance of the ash guide device, the large particles of dust are separated and directly fall into the ash hopper, while the finer dust enters uniformly. The middle box is adsorbed on the outer surface of the filter bag, and the clean gas passes through the filter bag and enters the upper box, and is discharged into the atmosphere through the off-line valves and exhaust pipes. With the progress of the filtering conditions, the dust on the filter bag accumulates more and more. When the equipment resistance reaches a limited resistance value (generally set to 1500Pa), the dust cleaning control device sets the differential pressure or the dust cleaning time After the set value automatically closes the off-line valve in the first room, the electronically controlled pulse valve is opened according to the set procedure to stop the air blowing. The compressed air is instantly blown to increase the pressure in the filter bag, and the dust on the filter bag is shaken off. (Even if sticky fine dust can be cleaned thoroughly), it will be discharged into the ash bucket by the ash discharge mechanism.

Cyclone

The dust removal effect of the bag dust collector depends on ten major factors, which directly affect the purification effect and life of the bag dust collector. So what is 10 o'clock? Ten factors affected

(1) Selection of filter bag: The filter bag should be selected from abrasion-resistant and high-temperature-resistant materials, such as fiberglass cloth / felt, Nomex, needle felt, P84 needle felt, etc., taking into account the wear resistance, durable high temperature and Cost and other factors, the copper industry generally chooses NOMEX needle felt.
(2) Temperature control: Generally the filter bag withstands a temperature of 200 , so the inlet temperature of the processing facility should be controlled below 200 . When the flue gas that has passed through the long smoke pipe reaches the dust collector box, the temperature can be reduced to 200 Below , under special circumstances, water cooling can be performed, and a cooler should be installed at the main smoke pipe.
(3) Fan selection: Induced fan is better than blower.
(4) Mechanical dust removal is more convenient and cleaner than manual dust removal, but the cost of mechanical dust removal is high, and most of the current methods use pulse dust removal.
(5) Air leakage and resistance: Theoretical calculation of the dust removal efficiency of the bag filter reaches 99%, but it is not achieved in the actual measurement, mainly due to the effect of air leakage and resistance. The lower the air leakage rate, the better the dust removal effect; resistance has a certain effect on the dust removal Impact, often empty the filter bag, reduce the resistance, and improve the dust removal effect.
(6) The dust collection hood should be as close as possible to the furnace head to make it easier for dust to enter the hood, increase the amount of dust collection, and reduce fugitive emissions pollution.
(7) Equipment maintenance: Instruments and equipment and cloth bags are easily damaged. Repair and replace the cloth bags in a timely manner.
(8) Airflow speed: The dust removal effect is best under the airflow speed of 1 ~ 3m / s, and the general wind speed is controlled at 2 ~ 4m / s.
(9) Filtration area: The larger the filtration area, the higher the dust removal efficiency, but the cost will increase accordingly. Therefore, the air volume should be calculated in advance, and then the corresponding dust collector model should be selected.
(10) Secondary dust removal: a settling chamber is installed in front of the dust collector box to form secondary dust removal. The sedimentation chamber can remove a part of large particles of dust, reduce the temperature and reduce the pressure of the dust collector.

Bag dust collectors have been used for more than 100 years, and their biggest advantages are high dust removal efficiency (over 99.99%), emission concentration can reach below 10mg / m³, and high classification efficiency. Fine particles also have a good collection efficiency, so they are widely used. However, after many years of operation, the bag filter has also exposed some problems, such as easy damage to the filter bag, dew condensation, high running resistance, failure in cleaning, and poor ash bucket discharge. There are many factors that cause problems in the operation of bag dust collectors. In addition to the factors of the dust collector itself, improper operation and management are also important reasons for problems in operation. This article analyzes and discusses the problems that often occur during the operation of the bag filter at present.

1 filter bag problem

The progress of bag dust collectors is mainly reflected in the innovation of filter materials and the change of dust cleaning methods, and the filter bag is the heart of bag dust collectors. The maintenance cost of filter bags accounts for the largest proportion of dust collector maintenance costs. , Up to more than 70% of maintenance costs. The filter bag is the most critical factor in determining the performance of the dust collector. The main factors causing filter bag damage are: high temperature burnout, corrosion, mechanical damage, installation quality, product quality, operation, management and other reasons.

1.1 Damage of filter bag by high temperature flue gas

(1) High temperature burnout

Damage to the filter bag due to high temperature is fatal. For example, a pulverized coal drying kiln in Heilongjiang Province, because the pulverized coal particles are very small and particularly sticky after drying, the ash cleaning is not ideal, so that a large amount of dried pulverized coal remains on the surface of the filter bag. Low, when the high-temperature flue gas enters the dust collector, it will quickly ignite the coal powder on the surface of the filter bag, causing the filter bag and the skeleton of the entire dust collector to be burned. It can be seen from Fig. 1 that a large amount of dried coal powder remains on the surface of the filter bag, and the box body is also burnt from the upper left corner.

(2) Mars burns through

In addition to high-temperature burnout, the damage to filter bags from Mars in the smoke is also very serious. For example, coke ovens, drying kilns, chain furnaces, cupolas, electric furnaces, blast furnaces, iron mixing furnaces, etc., a large amount of Mars will be mixed into the flue gas during the production process. When thin, Mars will burn through the filter bag, forming irregular round holes (Figure 2). However, when the dust layer on the surface of the filter bag is thick, Mars will not burn the filter bag directly, and it will cause dark colored baking marks on the surface of the filter bag.

(3) High temperature shrinkage

Another kind of damage caused by high-temperature smoke to the filter bag is high-temperature shrinkage. Although the use temperature of each filter material is different, when the temperature of the smoke gas exceeds its use temperature, if its warp shrinkage rate is too large, the filter bag will be at the length. The size becomes shorter in the direction, and the bottom of the filter bag is tightly supported by the frame and damaged by force (see Figure 3). If the filter bag's thermal contraction in the latitudinal direction is too large, the filter bag will become smaller in the radial dimension, the filter bag will be tightly hooped on the frame, and even the frame cannot be pulled out. As a result, the filter bag is always under stress, which causes the filter bag to shrink, deform, harden, and become brittle, accelerates strength loss, and shortens the life of the filter bag. Because the filter bag is tightly hooped on the frame after deformation, the filter bag is difficult to deform during dust cleaning, which is not conducive to spraying dust cleaning, resulting in high filter bag resistance.

(4) Ash bucket dust heat storage burnt filter bag

After the high-temperature dust is collected in the ash hopper, if it cannot be discharged in time, the dust will accumulate in the ash hopper for a long time, causing the temperature in the ash hopper to rise continuously, and the filter bag will become brittle and hard under long-term high temperature baking. Burning, especially the flammable substances contained in the dust, will burn in the ash hopper, which will destroy the filter bag. ^[6]

1.2 Filter bag corrosion

Corrosion is one of the most common causes of filter bag damage. Because the flue gas contains a variety of corrosive substances and is more corrosive in high temperature environments, it can cause filter bag damage. The main causes of corrosion are hydrolysis, oxidation, acid and alkali corrosion. Among them, the damage is mainly caused by hydrolysis and oxidation, while the acid corrosion is less and the alkali corrosion is less.

1.3 Mechanical damage

Because filter material manufacturers pay more attention to product quality, the filter material generally does not have quality problems such as mechanical damage 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 prerequisite to ensure the life of the filter bag. However, in the design process of the bag filter, too much attention is paid to various economic indicators, and it is easy to ignore the rationality of the air flow field distribution in the filter chamber. Due to the unreasonable airflow distribution, the speed between the bags will be too fast, causing damage to the filter bag from time to time. The most typical is the early mechanical rotary flat bag dust collector. The density of the filter bag in the filter box is the largest among the existing dust collectors, which causes the air bag to scour the filter bag. The selection of the length-to-diameter ratio of the filter bag is not reasonable, which will also cause the bag mouth speed to be too fast and wear the filter bag. ^[7]