“There is no best filter material, only filter material that is more suitable for its operating conditions.” The condition of working conditions refers to the external environment to which the dust filter bag is attached. What kind of material, what kind of filter material depends on working conditions, what kind of working conditions must choose the corresponding filter material to match. Only in this way can the service life of the dust filter bag be optimized. In the industrial flue gas dust removal, due to the differences in the characteristics of the steel, cement, power generation, waste incineration and other industries and the conditions of the company’s own working conditions, it is difficult to grasp the conditions of the use of the various manufacturers. Therefore, in addition to the quality of the filter itself, there are many factors affecting the service life of the filter bag in terms of the external environment, but the main factors are as follows:
Factors affecting the service life of the dust filter bag – Smoke volume
Because China’s raw coal has not been carefully classified prior to use, many types of hybrids are very heterogeneous, with mixed coal types and varying concentrations. The main reasons are that the calorific value, sulfur content, volatilization, and other indicators are difficult to distinguish. China’s high-quality coal, such as: raw coal, lean coal, white coal, etc., the calorific value of up to more than 5,000 kcal, volatile content of about 17%, small ash content; and the worst coal, such as: coal gangue, mud Carbon, the calorific value of 800-3000 calories, the volatility up to 50% -70%, large amount of carbon. This shows that the difference in coal breeds creates differences in calorific value, volatilization, and toner. After the coal is burned, the smoke is generated. The flue gas enters into the dust collector through the pipeline and is called the inlet flue gas. The amount of the inlet flue gas affects the service life of the dust filter bag. In the case of a large amount of inlet flue gas, if the filtration area is small and the filtration speed is large, the pressure of the dust collector will increase, causing the pressure of the dust removal filter bag to increase, which will intensify the damage of the dust filter bag. Because the choice of coal is good or bad, the amount of flue gas is determined, and the amount of flue gas directly affects the service life of the filter bag.
Factors affecting the life of dust filter bag II – Smoke content
Due to the different types of coal selected, the amount of dust contained in the flue gas is different. When the dust enters the dust collector, the dust with a large diameter falls or falls under the interception of the filter bag due to different dust diameters and different weights and weights. , And the small particle size of the dust generates kinetic energy under the influence of wind speed. When the dust is trapped by the filter bag, it is collected on the cloth bag. At this time, the kinetic energy is converted to zero, which will inevitably impact the filter bag. Under the action of kinetic energy, the dust will continuously wash away the filter bag. If the smoke contains large amount of dust, , filter wind speed, filter bag will withstand thousands of times friction and erosion, and the surface of the filter bag fiber can not withstand the erosion and fall off, damage filter bag filter efficiency. Therefore, for the working conditions with large smoke content, the wear resistance of the needle felt needs to be taken into account. The purpose is to prolong the service life of the filter material itself.
Three factors affect the dust filter bag service life – soot particles
The dust content in coal-fired flue gas is usually invisible to the naked eye because of its small particle size. When we look at the dust under a microscope, we can see that their shapes are different, they have no rules, they look like blades, and they have different diameters. Are not the same.
According to particle size classification can be divided into: coarse dust (particle size greater than 40um), fine dust (particle size in 10un-40nm), dust (lOun below). Because of their different particle sizes, the impact force on the dust filter bag is not the same, and the dust also contains a lot of acidic substances and alkaline substances, their diameters are very small, when intercepted by the bag, the role of the filter in the wind speed It still cannot fall off, remains on the surface of the filter or enters the interior of the filter. When combined with moisture, it will stick the filter bag and cause chemical changes in the filter material to cause corrosion. Therefore, when choosing the filter material, the size of the dust particle size can be considered as an indicator.
Factors Affecting the Life of Dust Filter Bags IV – Substance Types of Smoke
Due to different types of coal in soot, the proportion of dust is also different. The dust can be divided into organic dust, inorganic dust, and mixed dust according to the different composition of matter. The analysis of inorganic dust in the flue gas mainly includes elements such as Si02, FeA, CaO, MgO, Mn, etc. The SiO2 and Fe203 are mainly used for the scouring of the filter bag, and their particle size is very small under the action of wind speed. The high frequency of flushing the filter bag increases the damage of the filter bag. In front of the analysis of coal, different coal types Si〇2, FeA content will be different. For example, the content of Si02 in raw coal and plutonium coal is about 55%, but the content of Si02 in coal gangue is more than 60%. It can be imagined that their presence directly affects the service life of the filter bag.
Factors affecting the service life of the dust filter bag 5 – Extreme temperature indicator
Temperature is one of the important indicators for the use of filter media, and the temperature determines the service life of the filter media. Filters can be divided according to the temperature can withstand: normal temperature filter (less than 130 °C), medium temperature filter (130 °C -200 °C), high temperature filter material (greater than 200 °C). At present, our company’s filter material can withstand the maximum temperature of 300 °C, which is the positioning of our company’s high-temperature filter material temperature (200 °C -300 °C). The maximum temperature of glass fiber filter material is 300 °C, but the best use temperature is 260 °C. The filter material can only prolong its service life at the best use temperature. If the temperature is too high, it is easy for the filter material with relatively weak flame retardancy to cause burning and even fire. However, when the temperature is too low, condensation and corrosion may occur. Therefore, when using the filter, the temperature is usually increased by 10°C-20°C at the dew point temperature. The service temperature usually provided by the customer is displayed on the meter after the sensor test, and does not truly reflect the actual temperature of the dust. Generally speaking, when recommending filter materials to customers, it is better to increase the temperature parameter provided by the customer by 5°C-10°C to ensure the service life of the filter media.
Factors affecting the service life of dust filter bag 6 – Acid gas
In industrial dust removal, due to the delay of coal combustion, not only dust but also acid gases in the flue gas are dominated by SO2. Due to the presence of moisture in the flue gas, a strong acid is generated, and the strong acid is corrosive. The strong acid penetrates into the fiber, and the higher the working temperature, the faster the chemical corrosion occurs. Therefore, the content of SO2 is one of the essential elements in the analysis of working conditions.
Factors affecting the dust filter bag life factor 7 – alkaline corrosion
In the third element, we mentioned dust analysis. The smoke contains a large amount of alkaline substances such as CaO, MgO, etc. It belongs to deliquescent dust. The diameter is very small and it is a kind of dust. Under the effect of wind speed, it is very easy. Into the fiber, some directly discharged into the air, but part of the dust still remains in the fiber to plug the filter hole, while containing moisture in the flue gas, water vapor and deliquescent dust combined paste the filter hole so that the filter bag can not breathe, affect the filter bag Normal service life. Its molecular formula is as follows:
Factors affecting the service life of dust filter bag 8 – Oxygen content
It is not surprising that oxygen is contained in the flue gas, but for different media, we must consider: oxygen content, temperature. When the filter material is under the extreme temperature, if oxygen is present, oxygen slowly oxidizes the filter bag, making the filter bag green and brittle, and directly reducing the service life of the filter material, such as the PPS needle felt at 120°C-180°C. , And when used under conditions of high oxygen content and moisture content, the condition is very good. However, when the temperature is increased by 10°C, its antioxidant capacity is rapidly reduced by half, and its ability to resist acid and alkali is also reduced by half, which seriously affects its life span. Therefore, when customizing different filter media, the oxygen content is an indicator that cannot be ignored. The higher the oxygen content, the higher the moisture content.
Factors affecting the service life of dust filter bag 9 – Air distribution
The distribution of the air flow affects the normal use and service life of the dust filter bag. If the precipitator manufacturer’s design has an unreasonable distribution of the air flow and the local air flow is too large, the long-term operation of the dust filter bag under this condition may cause the filter bag to be damaged. For example, the filter material of one room is destroyed or several filters are The bag is partially damaged, so the distribution of air flow cannot be ignored. The usual solution is to design a deflector in the precipitator. The role is to change the direction of the airflow and avoid direct erosion of the filter bag.
In short, the analysis of operating conditions is difficult, and there are many uncertainties. Changes in any one factor will affect the service life of the filter bag. In the analysis of working conditions, the customer needs to provide detailed information to clarify the external environment in which the product is used, so as to manufacture and produce quality products that meet the environmental conditions of the specific working conditions.