Technical improvement method for dust removal of cement enterprise bags

1 post personnel technical training

The rational design, elaborate production and precise installation of the dust collector are important prerequisites for ensuring efficient operation. High-quality, technically-savvy maintenance and management personnel are an important guarantee for the long-term stable operation of the dust collector. For newly added equipment, the relevant technical personnel of the supplier in the installation process need to start technical training and communication with the maintenance management personnel, so that the post personnel can track the whole process of equipment installation, and be familiar with the internal structure, working principle and various components of the dust collector. Functional, functional and maintenance matters, proficient in important components. Such as: the installation and replacement of the filter bag, proficient in how to adjust the parameters of the cleaning system, the pressure of the cleaning gas flow and the cleaning cycle, the pulse width of the cleaning pulse and other parameters have an impact on the life of the filter bag. Proficiency in the order of opening and stopping, familiar with the important matters that should be paid attention to before starting and before stopping, to avoid the accident of paste bag and burning bag caused by improper operation during start-up and shutdown. Before the equipment is operated, the staff instructing the post or working with the post personnel shall formulate equipment management rules, post operation procedures, safety management and operation systems, and emergency handling plans for accidents. After the equipment is in normal operation, the relevant technical personnel of the supplier shall establish a close communication channel with the equipment personnel to understand the operation status of the equipment at various stages, and timely correct the operation control parameters of the dust collector so that the dust collector can reach the standard operation under the optimal condition. For in-service equipment, if there is a lack of meticulous training for post work, this lesson should be completed as described above.

Control of key technical parameters of 2 bag dust collector

2.1 Filtering wind speed

The working principle of the bag filter is “filtering-cleaning-filtration”, which is repeated. The two actions of filtration and cleaning are the most important working processes of the bag filter. Filtration is to intercept the dust in the dusty gas by the filter bag, and the cleaning is to restore the filter performance of the filter bag again. Filtration wind speed is the most important technical parameter of bag filter. The size of filter wind speed directly affects the filter efficiency of filter bag, filter resistance, filter bag life, running energy consumption, size of dust removal equipment (first investment), etc. Whether the value is reasonable or not directly determines the future operating status of the dust collector.

Although the designer knows the influence of the filtered wind speed on the performance of the bag filter and the importance of filtering the wind speed, in practice, there is a mentality of “filtering the wind speed up” with the peers, and catering to the user’s excessive attention to the first investment is low. Demand, the filter wind speed value is too high, leaving a long-term standard operation of future equipment leaving a hidden trouble that is difficult to repair.

The first application of the gas box pulse bag dust collector introduced in 1988 was used in the cement factory for cement dust removal. The filtered wind speed was around 0.87m/min, achieving low resistance, high dust removal efficiency and low concentration discharge. American experts who came to China for technical guidance and acceptance gave affirmation of the value of the filtered wind speed. After that, the gas box pulse bag dust collectors were spread all over the country cement enterprises, which greatly changed the environmental appearance of cement companies. At the same time, the technical equipment is still a lot of iron and steel plant application, we designed for users of more than 400 000 ~ 1 000 000m? / H bag filter system for preparing slag powder, which are in the filtration velocity 0.9m / min or less, The life of the filter bag is basically 4 years, some more than 4 years, and the running resistance is low. In the first 3 years of the operation of the precipitator, the operating pressure difference is mostly below 850Pa. The filtered soot emission concentration is around 10mg/Nm?, and some are only 3.5mg/Nm?. From 2000 to 2003, the LMC long-bag pulse bag dust collector, which was widely used in the treatment of vertical kiln flue gas, was also recognized by the market. The author chose not to agree with the filtering wind speed of more than 0.9m/min or even more than 1.0m/min for the cement kiln head and the kiln tail bag filter. It still does not agree with the filtering wind speed above 0.9m/min.

The high filtration wind speed can only reduce the first investment of the equipment, but increase the power consumption of the fan, greatly shorten the service life of the filter bag, and increase the concentration of the export discharge, which brings long-term negative benefits.

For the equipment in operation, if the design of the filter wind speed is too high and there are frequent failures such as broken bags, excessive discharge, and high running resistance, it is recommended to change the filter unit and filter area.

2.2 Cleaning parameters

The cleaning is to restore the filtration performance of the filter bag. At present, the cleaning action of the pulse bag filter is to blow the compressed gas by the pulse valve and peel off the dust adhering to the filter bag. The cleaning parameters include the ash gas source gas volume, the ash cleaning pressure, the cleaning system (cleaning cycle, pulse width, cleaning order, etc.). Reasonable cleaning parameters can achieve the purpose of cleaning, and can retain the second filter layer on the surface of the filter bag to achieve efficient collection of fine particle dust. The test proves that the bag filter has the highest discharge concentration at the beginning of filtration and each pulse cleaning, and the filtration efficiency is the highest when it enters the stable filtration operation state. The design of reasonable cleaning parameters to achieve fine cleaning is the most important technical measure for the efficient discharge of bag dust collectors.

The gas source gas volume can be calculated according to the gas consumption of the pulse valve and the preset cleaning system to calculate the gas consumption required for cleaning. The cleaning pressure is the pressure after the pressure of the pressure source is adjusted by the pressure regulating device, and is the pressure of the pulse valve. The cleaning pressure is set according to the nature of the dust and the quality of the filter bag, which can meet the demand of cleaning. The reasonable cleaning pressure should be adjusted according to the change of the running resistance of the on-site precipitator, so that the filter bag always retains the second filter layer. Non-compliance emissions due to excessive ash pressure and excessive ash cleaning should be avoided. Low-concentration occasions such as cement plant packaging, warehouse tops, and trans-shipment points at the bottom of the reservoir, and dust collectors using membrane filter bags, the cleaning pressure is recommended to be less than 0.4 MPa. In actual engineering cases, too many low-concentration dust collectors have experienced excessive discharge of excessive dust.

Reasonable cleaning pressure and proper cleaning system (cleaning cycle, pulse width, cleaning order, etc.) are the key to achieving fine cleaning. To be refined, it is necessary to track the running state of the equipment in operation, the actual gas consumption of the pulse valve, the pressure drop of the cleaning dust during the cleaning, the pressure difference of the dust collector before and after the cleaning, the different cleaning pressure and the different cleaning. The key parameters such as the operating state of the equipment are monitored and compared, and the best cleaning parameters are found to achieve fine cleaning of the dust collector. At the same time, it also provides reference for the design of the same type of new equipment cleaning system.

3 Change the order of cleaning

The order of cleaning has an effect on the cleaning effect, the discharge concentration of the outlet, and the uniformity of the dust return dust. The influence of the air box pulse bag dust collector and the long bag line pulse bag dust collector is different.

Most of the air box pulse bag dust collectors are sequentially cleaned according to the order of the bag chamber. For the large air bag pulse bag dust collector, the traditional bag room cleaning method is used to change the gray color of the bag room by the staggered way of the front and rear bag rooms. The dust is evenly distributed in the process of returning to the ash, and the influence of the uneven thickness of the ash on the product quality is avoided. A slag powder production line in Shandong was coarse and fine at the beginning, which affected the quality of the product. At the beginning, I did not know why, and then solved the problem of uneven thickness by changing the order of cleaning, and then understood the reason.

The order of cleaning the bag bag pulse bag dust collector refers to the order of the bag room and the order of the filter bags in the bag room. The order of cleaning the bag room is the same as that of the air bag pulse bag dust collector. The order of cleaning the filter bags in the bag interior will affect the filtration efficiency of the filter bag. After the cleaning, the filter bag has good gas permeability, and it is easier to adsorb dust. The same bag is cleaned in order, and the dust cleared in the rear filter bag is again adsorbed on the filter bag in the front row of clear gray, especially The fine dust immediately cleared clears or blocks the front filter bag, reducing dust removal efficiency and cleaning efficiency. Change the order of cleaning, change the cleaning order to "jumping type" or "jumping type", which can greatly improve dust removal efficiency and cleaning efficiency.

4 change the opening speed of the offline valve

There are two types of bag dust cleaning methods: online cleaning and offline cleaning. Online cleaning is a working method of filtering and cleaning, and offline cleaning is a working method of stopping filtration and then cleaning. Since the dust removal effect of off-line cleaning is better than on-line cleaning, the bag dust collector adopts the majority of off-line cleaning. The offline cleaning process is: closing the off-line valve to clean the bag chamber - stopping the bag chamber filtration - jetting the compressed gas from the pulse valve - stripping the dust adhering to the filter bag - opening the off-line valve and re-entering the filter state. The test proves that the bag dust collector has the highest discharge concentration when cleaning, the main reason is that the filter bag is better in gas permeability after cleaning, and the bulging filter bag will quickly fold back to the bag cage when the offline valve is opened, more dust will be in the test. In a short time, the airflow is adsorbed on the surface of the filter bag, and more fine dust will pass through the filter bag and be discharged into the atmosphere with the airflow, so that the discharge concentration of the dust collector outlet increases.

Reducing the opening speed of the offline valve can reduce the folding speed of the bulging filter bag and the speed of the air flow to the filter bag again, thereby reducing the dust penetrating the filter bag and improving the filtering efficiency during cleaning. In practical applications, the off-line valve has two kinds of poppet valve and butterfly valve, which are mostly driven by the cylinder, and the cylinder is not variable speed. The off-line valve closing speed is the same as the opening speed, so the opening speed of the offline valve cannot be reduced. Replace the variable speed cylinder and select “fast-forward-slow-return cylinder”. After the pulse valve cleaning operation is completed, the offline valve will be slowly opened, the dusty airflow will flow slowly to the filter bag, and the bulging filter bag will be slowly folded back, which can greatly improve the cleaning. Time bag filter efficiency. The replacement gear cylinder can be used in the transportation equipment.

5 Replace the filter bag

At present, the filter bags used in the bag filter have the characteristics of film coating and non-film coating. The film filter material has the highest dust removal efficiency, and the newly added equipment is recommended to use the film filter bag. In the transportation equipment, for the structural design is reasonable, the cleaning parameters are reasonable, the running resistance is not high, the dust collector using the membrane filter material can meet the new national environmental protection standards; and the ordinary filter bag without the film is used, the dust collector The export emission concentration may exceed the national emission standard. For this type of dust collector, the ordinary filter bag can be directly replaced with a film filter bag. After replacing the filter bag, the cleaning parameters should be adjusted in time, that is, the pressure of the cleaned gas source is reduced. Extend the cleaning cycle and widen the pulse valve pulse width to extend the life of the filter bag and improve the filtration efficiency of the dust collector.

6 High-precision intelligent manufacturing and Internet technology

At present, there is no gap between the technical level of bag filter and foreign countries, but there is still a considerable gap between the equipment and means of processing and manufacturing. The manufacturing level gap between domestic peers is not small. This has high efficiency and low emission for bag dust collectors in China. Quite a big impact. Cultivate high-end industrial skilled workers, achieve high-precision intelligent manufacturing, eliminate backward workshop-style processing methods, truly improve the processing quality of baghouses, enable baghouses to achieve lower export emissions, meet the country's higher environmental requirements, and should be the future The focus of the work of environmental protection practitioners for several years is also the way out for practitioners.

In the next ten years, Internet technology can realize seamless communication between job workers and designers. Designers can directly observe the operation status and operation data of the on-site precipitator in the office and at home, and directly guide the post workers to manage and maintain the dust collector, which can improve The bag dust collector operates efficiently and improves the technical level of bag dust removal.

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