1. Introduction to LCMD pulse bag filter
LCMD pulse bag filter; It is a type of offline low-pressure pulse bag filter, designed and manufactured by our unit using technology for negative pressure operation, low-pressure pulse, and long bag large-scale dust collectors.
The LCMD bag filter combines the advantages of various types of dust collectors, such as large-scale blowback, high-pressure air box pulse, and low-pressure pipe spray pulse. It has a compact structure, dual dust removal principle, good dust cleaning effect, stable operation, and long filter bag life. It is widely recognized as a large-scale dust collector and is an excellent dust removal equipment for industries such as metallurgy, power, and building materials.
2. Main structure and working principle of LCMD pulse bag filter
2.1 Main Structure
The LCMD type compartment stop air duct low-pressure pulse bag filter is mainly composed of a bag chamber (box), ash hopper, clean gas chamber, filter bag and skeleton, pulse spraying system, inlet and outlet air box, outlet air valve, ash discharge valve, bracket, and stair platform.
2.2. Box body
The offline low-voltage pulse bag filter has changed the conventional on-site panel assembly structure to a single box on-site combination structure, which not only reduces the on-site installation workload but also improves the overall quality of the equipment. The lower part of the middle box is equipped with a blocking device at the air inlet. When the dusty gas enters the ash hopper in the air inlet box, the dust collides with the baffle due to its velocity inertia, and most of it falls into the ash hopper. The remaining small amount of fine dust enters the filter bag chamber for filtration with the airflow according to the direction guided by the blocking device.
2.3 Ash hopper
The wall panels of the ash hopper are welded with 4mm thick steel plates, and the outer surface is welded with sufficient strength angle steel as reinforcement bars. The lower part of the ash hopper is also welded with a large hole grille. When repairing and replacing bags, the filter bag can be directly placed into the ash hopper from above, dropped onto the grid, and then uniformly removed from the ash hopper through the hole door. This not only reduces the labor intensity of workers, but also achieves cleaning operations, which is highly welcomed by maintenance personnel.
2.4 Filter bag
Due to the presence of SO2 and water in boiler flue gas, corrosive acidic liquids are produced. In order to meet the emission standards for filtration performance, PPS needle punched felt with acid and alkali resistance is used as the filter bag for the dust collector. Its performance must meet the following indicators:
Weight: 500g/m2
Thickness: 1.9mm
Breathability: 10m3/m2/min
Fracture strength: Radial>600 N/5 × 20cm, latitudinal>1000 N/5 × 20cm
Continuous use temperature: 190 ℃
Short term use temperature: 220 ℃
Acid and alkali resistance:
The material of the spring expansion ring in the saddle rubber ring is 65Mn, with a thickness of 0.4mm
There is an elastic expansion ring at the mouth of the filter bag, which is molded into a crescent shape and placed into the flower plate hole. It is sealed, firm, and does not fall off, making installation, maintenance, and bag replacement extremely convenient. There are cross shaped airflow channels between the filter bags. Facilitate the uniform rise and diffusion of dusty gases, achieve load balance of filter bags, and extend their service life.
2.5. Filter bag skeleton
The support frame of the filter bag is made of cold drawn steel wire spot welding (resistance welding), with a smooth surface without welding slag, welding spots, or burrs, and then galvanized.
2.6. Clean the gas box
Above each bag chamber (box), there is a corresponding clean gas box, which is equipped with multiple rows of spray pipes inside. The inlet end of the spray pipe is fixed to the wall panel with a quick connect fitting, and the terminal is fixed to the bracket with a pressure plate. This structural type is convenient for the installation and adjustment of the jet pipe, and its blowing port can be concentric with the filter bag to achieve the blowing effect.
2.7. Manhole doors and inspection doors
The manhole inspection doors on the top of the dust collector and the ash hopper both adopt a quick opening structure. Workers can quickly open and close them without carrying tools during maintenance. The handle used for tightening is a cam type structure, which can be manually tightened and firmly pressed down. After lifting and rotating a few times, it can be opened, which is extremely convenient.
2.8. Electromagnetic pulse valve
The electromagnetic pulse valve produced by our company has achieved a high level of performance and service life. Its type is submerged, with main technical parameters:
Membrane service life:>1 million cycles
Adapt to environmental humidity: -35-90 ℃
Spray air source pressure: 0.2-0.6Mpa
Spray time: 0.2s
Spray volume: ≥ 500L
Working power supply: DC24V 20W
3. Working principle of LCMD pulse bag filter
The dusty gas enters the LCMD pulse bag filter and folds into the lower part of the middle box after entering the air box. It first hits the blocking device, causing most of the coarse dust particles to fall directly into the ash hopper, playing a pre dust collection role. The airflow enters the filter bag chamber. Under the negative pressure of the system, when the dusty gas passes through the filter bag with the supporting skeleton inside, the dust is trapped on the outer surface of the filter bag. It is discharged into the chimney through the fan and enters the atmosphere. When the dust on the filter bag accumulates to the upper limit of the equipment resistance, the dust cleaning control device sends a command to gradually open the pulse valve of the chamber and spray clean and dry compressed air of 0.2-0.6MPa into the filter bag, causing the filter bag to swell and shake off the dust on the surface, which falls into the ash hopper. The room cleaning is completed. After the dust falls into the ash hopper, the cleaning of other rooms is carried out alternately according to the procedures of each room.
4. Technical characteristics of LCMD pulse bag filter
4.1. Good dust cleaning effect, dust removal, can achieve the above. Export emissions below 100mg/Nm3.
4.2. The filter bag layout is reasonable, with reasonable air channels between the filter bags. The filter bag has a uniform filtration load and a long service life, generally up to 1-2 years.
4.3. The lower part of the middle box is equipped with a blocking device at the inlet end, which can not only intercept most of the coarse dust particles that directly fall into the ash hopper, but also distribute the airflow and prevent the dust from directly washing the filter bag, thereby extending its service life.
4.4. The filter bag structure adopts Fule technology, making disassembly and assembly extremely convenient and hygienic.
5. Electrical control and automation instruments
5.1 System Control
5.1.1 Dust removal control of dust collector
The three dust cleaning control modes of bag filter, including dust cleaning setting, constant pressure difference, and mixing mode, can be selected through the switch located on the control cabinet panel. When selecting the timed cleaning mode, when the cleaning cycle reaches the given time limit, the control cabinet sends a cleaning signal, and the dust collector starts cleaning. After one week of cleaning, it enters the cleaning waiting program; When selecting the constant pressure difference dust cleaning mode, the dust removal control is based on the filter resistance (total pressure difference) of the dust collector. When the resistance rises to the set value, the dust cleaning program is started. When the resistance drops below the set value and one cycle of dust cleaning is completed, the dust removal of the dust collector is completed and the dust cleaning waiting program is entered; When selecting the hybrid mode, timing should be prioritized and pressure difference should be given priority.
5.1.2 Dust collector unloading and ash conveying control
The dust collector has two ash hoppers and is equipped with a star shaped ash discharge valve to form a manual external ash discharge system.
5.1.3 Control of Release Valve
To prevent emergency situations but not to affect production, automatic opening and closing of the relief valve and pipeline butterfly valve are implemented, and the two valves are interlocked.