How to achieve energy saving and consumption reduction with pulse bag dust collector

As the contradiction between ecological environment pollution and human health becomes increasingly serious, the national governance assessment of environmental pollution is becoming more and more intense, enterprises are investing more and more in environmental protection facilities, and the cost of equipment installation and operation is getting higher and higher, which seriously restricts the production cost of enterprises. Bag dust collector has several advantages, such as high dust removal efficiency, generally reaching 99%; simple structure, convenient maintenance and operation; under the premise of high dust removal efficiency, the cost is lower than that of electrostatic precipitator; wide range of applications, etc., and is widely used in coal-fired power plants, metal smelting, cement and other major heavy industrial enterprises.

More and more bag dust collector is put into use, and energy consumption is increasing. How to save energy and reduce consumption in equipment operation has become a key part of reducing enterprise production costs. According to the composition of bag dust collector, it can be summarized that energy saving and consumption reduction can be achieved from the following three major energy-consuming equipment.

1. Fan system

The fan system is the largest energy-consuming device in bag dust removal equipment. According to the fan motor power formula P=1.732*U*I*COSφ, it can be known that the motor power loss can be reduced by reducing the motor running current and increasing the motor power factor. Changing the motor running current can be achieved by dynamically adjusting the fan speed and fan valve opening according to the load demand.

1) Fan motor uses variable frequency control

The frequency converter can quickly respond to the control output according to the air volume demand of the on-site working conditions, and smoothly regulate the fan speed. It has stable and efficient energy-saving effects, but the frequency converter is expensive, and the installation of electrical equipment requires a special site and a good operating environment. The cost of later maintenance and spare parts is high. Generally, it will be selected based on the comparison between the investment cost and the energy-saving effect generated in the later period.

2) The fan uses a hydraulic coupling to adjust the speed

The hydraulic coupling has a lower one-time investment cost than the frequency converter, and the later maintenance cost is lower, but the speed regulation response speed is lower, and the mechanical parts cannot be frequently adjusted. Otherwise, it is easy to cause damage to the hydraulic coupling speed regulation parts, which is not suitable for use under frequent changes in working conditions. The energy-saving effect is not as good as variable frequency speed regulation.

3) Adjust the fan valve opening control

According to the on-site working conditions, the fan inlet valve opening can be manually adjusted to reduce the fan load and reduce the motor load loss. However, valve adjustment will cause turbulence, causing fan surge, increased equipment vibration, and the fan housing will be heated by air flow friction for a long time. The energy-saving efficiency is low, and this method is rarely used to save energy and reduce consumption.

4) Add power capacitor compensation equipment

By adding power capacitor compensation equipment to the power equipment in the distribution room, the power factor of the motor is improved, thereby improving the efficiency of the motor. This method has a low investment cost and has a good energy-saving effect on long-term inefficient operating equipment. In summary, choosing the appropriate energy-saving method according to actual use can greatly save energy and reduce consumption, and effectively reduce operating costs. At present, a small number of dust collectors of our projects use variable frequency speed control and hydraulic coupling speed regulation. However, since the on-site operating conditions are basically full-load operation, the speed regulation range of the dust collector equipment is not large. The hydraulic coupling speed regulation is mainly used for converters and molten iron dust removal fans, and is basically used for speed regulation during startup. It will occasionally adjust the speed according to on-site conditions, and has not achieved a good energy-saving effect. There is much room for improvement in energy saving and consumption reduction.

2. Cleaning system

Bag dust removal and cleaning system is mainly composed of air storage tank, compressed air pipeline, air distribution bag, pulse valve, cloth bag, etc.

The main working principle is to use the fan to generate power to bring the dust particles on site into the lower box of the dust collector through the pipeline. Large dust particles enter the large space and fall into the ash bin under their own gravity. Fine dust is blocked by the cloth bag. The filtered clean air passes through the clean room and is discharged into the atmosphere through the chimney. When the dust is increasing, the upper and lower boxes of the dust collector generate more and more resistance. When a certain resistance is reached, the pulse valve is required to control the compressed air for spraying and cleaning, and restore the normal resistance to meet the working conditions. At present, there are two main control methods for the cleaning system: regular cleaning and pressure difference cleaning.

Regular cleaning is to set the spraying interval and cycle time in the central control according to the dust amount of the on-site working conditions, and perform regular cleaning over and over again. Setting the appropriate spraying interval and cycle according to the actual working conditions and dust properties on site can improve the cleaning efficiency and reduce the loss of compressed air. This cleaning method is suitable for places with stable working conditions and stable dust volume.

Pressure differential cleaning is to convert the pressure difference according to the pressure detection of the inlet and outlet of the dust collector. When the pressure difference reaches the set high value (generally set to 1500Pa), the program automatically starts the cleaning system for spraying. When the pressure difference drops below the set low value (generally set to 1000Pa), the cleaning is automatically stopped. This cleaning method can make the compressed air reach the optimal state, but it requires accurate pressure detection value and the detection pressure pipeline is not frequently blocked. It is necessary to regularly check whether the pressure detection equipment is normal to prevent inaccurate pressure detection and long-term lack of cleaning from causing bag adhesion.

SINOBAGHOUSE's dust removal equipment combines two cleaning methods. After program improvement, it uses a linkage cleaning method that combines regular and pressure differential cleaning for cleaning: the cleaning cycle time is set to a longer cycle time according to the on-site working conditions. When the pressure detection is abnormal and the cleaning is not done for a long time, the system will clean according to the set cycle to ensure that the bag will not stick due to long-term lack of cleaning.

By optimizing the dust cleaning control system, the useless loss of compressed air can be reduced, thereby achieving the goal of energy saving and consumption reduction.

3. Ash conveying system

The ash conveying system of bag dust collector equipment is generally composed of ash hopper vibrator, ash discharge valve, scraper conveyor, bucket elevator or pneumatic ash conveying and other equipment. Since the cleaning system of bag dust collector equipment works intermittently, only when the cleaning system works, the ash hopper will drop a large amount of accumulated ash. The fallen ash needs to be promptly transported to the external ash storage bin through the scraper conveyor, bucket elevator or pneumatic ash conveying to avoid the ash hopper of the dust collector affecting the normal operation of the equipment due to excessive ash accumulation. In severe cases, the dust may be overloaded and the dust collector may be crushed. The traditional ash conveying system operates uninterruptedly for a long time. In this way, when there is no ash in the ash hopper, the ash conveying system equipment will run idle, wasting electricity. At the same time, it will cause dry grinding of the scraper chain and the guide rail, greatly shortening the service life of the ash conveying equipment and increasing the equipment spare parts loss cost and equipment maintenance cost.

Through long-term observation and practice, we designed and changed the program according to the ash conveying capacity of the ash discharge valve and the scraper, and realized two ways to improve the efficiency of the ash conveying system equipment, so as to achieve energy saving and consumption reduction.

The first way: design and modify the program and control screen, add the periodic automatic start and stop function of the ash conveying system, add the start delay time, stop delay time, ash discharge valve operation time, ash discharge valve interval time, ash discharge valve cycle interval time control parameter setting box on the screen, and set the ash conveying system operation time according to the on-site ash volume, so that the equipment can operate in a more efficient working state, and greatly reduce the energy consumption of the dust removal and ash conveying system equipment.

The second way: use the ash hopper level meter level detection function, when half of the silo is low, the level meter detects a low level signal, and automatically starts the ash conveying system to discharge ash. After running for a period of time, the low level signal disappears and the ash conveying system stops. This method can better improve the use efficiency of the equipment and save energy and reduce consumption to the greatest extent. However, this solution has not been applied in practice and needs to be implemented.

In today's rapidly developing economy, while pursuing efficiency first, more and more attention is paid to environmental protection. A large number of environmental protection equipment have been put into use. Only by continuously improving the efficiency of equipment use in various ways can we save energy and reduce consumption more effectively and reduce the production and operation costs of enterprises.

Energy saving and consumption reduction are the basic requirements for all energy-consuming equipment. As a high-energy consumption environmental protection equipment, bag dust collectors should start from the design to make the equipment perfect, both environmentally friendly and energy-saving. Starting from analyzing the resistance of bag dust collectors, detailed work is done in the three aspects of fan system, dust cleaning system, and dust conveying system. It will definitely effectively reduce the operating resistance of bag dust collectors, so that they can play a greater role under the premise of energy saving.

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