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Cyclone dust collector
It is a type of dust removal device. The dust removal mechanism is to make the dusty airflow rotate, use centrifugal force to separate and capture dust particles from the airflow, and then use gravity to make the dust particles fall into the ash hopper. The various components of a cyclone dust collector have a certain size ratio, and changes in each ratio relationship can affect the efficiency and pressure loss of the cyclone dust collector. Among them, the diameter of the dust collector, the size of the air inlet, and the diameter of the exhaust pipe are the main influencing factors. When using, it should be noted that when a certain threshold is exceeded, favorable factors can also be transformed into unfavorable factors. In addition, some factors are beneficial for improving dust removal efficiency, but they can increase pressure loss, so adjustments to each factor must be taken into account.
Industry standards
AQ 1022-2006 Bag Dust Collector for Coal Mines
DL/T 514-2004 Electric Dust Collector
JB/T 10341-2002 Filter cartridge dust collector
JB/T 20108-2007 Pharmaceutical Pulse Bag Dust Collector
JB/T 6409-2008 Wet electrostatic precipitator for gas use
JB/T 7670-1995 Tubular electrostatic precipitator
JB/T 8533-1997 Rotary Backblowing Bag Dust Collector
JB/T 9054-2000 Centrifugal Dust Collector
MT 159-1995 Mining Dust Collector
JC/T 819-2007 CXBC series bag filter for cement industry

JC 837-1998 Backblowing Bag Dust Collector for Building Materials Industry
advantage
According to the method of integrating the axial velocity with the flow area mentioned earlier, calculate the changes in the descending flow rate of a conventional cyclone dust collector after installing different types of drag reducing rods, and plot the percentage of the total processing flow rate of the descending flow dust collector at different cross-sections under various conditions to indicate the average value of the flow rate in the upstream and downstream flow zones, that is, the difference between the descending flow rate and the actual flow rate in the downstream flow zones. It can be seen that the short-circuit flow and descending flow of each model vary along the height of the dust collector.
Compared with conventional cyclone dust collectors, installing full-length drag reduction rods 1 # and 4 # increases the short-circuit flow rate, but installing non full-length drag reduction rods H1 and H2 reduces the short-circuit flow rate. The variation law of the flow rate along the process after installing 1 # and 4 # is basically the same as that of a conventional cyclone dust collector, showing a linear distribution, with three parallel decreasing lines. But after installing H1 and H2, the distribution shows a broken line instead of a straight line, and the inflection point is precisely the cross-sectional position where the drag reducing rod is inserted from bottom to top. From this, it can also be seen that the non full length drag reduction rod increases the downward flow rate of each section above the cross-section, which is greater than that of a conventional dust collector. However, after contacting the drag reduction rod, the downward flow rate decreases rapidly, reaching or below the value of a conventional dust collector at the bottom of the cone.
The reduction of short-circuit flow can improve dust removal efficiency, increase the descending flow rate of the cross-section, and also increase the residence time of dusty air in the dust collector, creating more separation opportunities for dust. Therefore, although the drag reduction effect of non full length drag reduction rods is not as good as that of full length drag reduction rods, it is more conducive to improving the dust removal efficiency of cyclone dust collectors. There is a short-circuit flow rate of up to 24% near the inlet section of the exhaust core pipe of a conventional cyclone dust collector, which will seriously affect the overall dust removal effect. How to reduce this short-circuit flow will be a research direction for improving efficiency. Although the drag reduction effect of non full length drag reduction rods is not as good as that of full length drag reduction rods, it will have more practical significance because it reduces the short-circuit flow rate of conventional cyclone dust collectors and increases the flow rate of cross-sectional descent, thereby improving the dust removal efficiency of cyclone dust collectors.
classification
① An efficient cyclone dust collector with a smaller cylinder diameter is used to separate finer dust, with a dust removal efficiency of over 95%;
② A high flow cyclone dust collector with a large cylinder diameter is used to handle large gas flow rates, and its dust removal efficiency is between 50-80%;
③ The universal cyclone dust collector has a moderate air processing capacity, but due to different structural forms, the dust removal efficiency fluctuates between 70-85%,
④ Explosion proof cyclone dust collector, equipped with explosion-proof valve, has explosion-proof function.
According to the structural form, it can be divided into long cone, cylindrical body, diffusion type, and bypass type.
According to the combination and installation situation, it can be divided into internal cyclone dust collectors, external cyclone dust collectors, vertical and horizontal cyclone dust collectors, and single tube and multi tube cyclone dust collectors.
According to the airflow introduction situation, the flow path of the airflow after entering the cyclone dust removal, as well as the form with secondary air, can be summarized into the following two types:
① Shear flow reverse cyclone dust collector ② Axial flow cyclone dust collector
Efficiency factors
Air intake
The air inlet of a cyclone dust collector is a key component that forms a rotating airflow and is the main factor affecting dust removal efficiency and pressure loss. The inlet area of tangential intake has a significant impact on the dust collector. When the inlet area is relatively small compared to the cross-section of the cylinder, the tangential velocity of the airflow entering the dust collector is high, which is beneficial for dust separation.
Diameter and height of cylindrical body
The diameter of the cylindrical body is the most basic size that constitutes a cyclone dust collector. The tangential velocity of a rotating airflow is inversely proportional to the centrifugal force generated by dust and the diameter of the cylinder. At the same tangential velocity, the smaller the diameter D of the cylinder, the smaller the radius of rotation of the airflow, and the greater the centrifugal force experienced by particles, making it easier for dust particles to be trapped. Therefore, a smaller cylinder diameter should be chosen appropriately, but if the cylinder diameter is chosen too small, the wall and exhaust pipe will be too close, and particles will easily escape; The diameter of the cylinder is too small and can easily cause blockage, especially for viscous materials. When dealing with high air volume, due to the small diameter of the cylinder, the dust containing air volume is limited. Therefore, several cyclone dust collectors can be operated in parallel to solve the problem. The air volume processed by parallel operation is the sum of the air volumes processed by each dust collector, and the resistance is only the resistance of the portion of air volume that a single dust collector is responsible for processing. However, parallel use is more complex to manufacture and requires more materials. Gas is easily blocked at the inlet, increasing resistance. Therefore, the number of units used in parallel should not be too large. The total height of the cylinder refers to the sum of the heights of the cylindrical and conical parts of the dust collector. Increasing the total height of the cylinder can increase the number of rotations of the airflow inside the dust collector, increasing the chances of separating dust from the airflow in the dusty airflow. However, as the total height of the cylinder increases, the radial velocity of the centripetal force in the outer vortex also increases the chances of some small dust entering the inner vortex, thereby reducing the dust removal efficiency. The total height of the cylinder is generally 4 times the diameter of the cylindrical body. For the conical cylinder part, due to its decreasing radius, the tangential velocity of the airflow continues to increase, and the distance for dust to reach the outer wall also decreases. The dust removal effect is better than that of the cylindrical part. Therefore, when the total height of the cylinder is constant, increasing the height of the cone cylinder appropriately is beneficial for improving dust removal efficiency. Generally, when the height of the cylindrical part is 1.5 times its diameter and the height of the cone cylinder is 2.5 times its diameter, ideal dust removal efficiency can be achieved.

Exhaust pipe diameter and depth
The diameter and insertion depth of the exhaust duct have a significant impact on the dust removal efficiency of the cyclone dust collector. The diameter of the exhaust duct must be chosen at an appropriate value. Reducing the diameter of the exhaust duct can reduce the rotation range of the internal vortex, making it difficult for dust to be discharged from the exhaust duct, which is beneficial for improving dust removal efficiency. However, at the same time, increasing the speed of the air outlet increases the resistance loss; If the diameter of the exhaust duct is increased, although the resistance loss can be significantly reduced, due to the close proximity of the exhaust duct to the cylindrical wall, it is easy to form a "short circuit" phenomenon between the inner and outer vortices, which causes some of the uncleaned dust in the outer vortices to directly mix into the exhaust duct and be discharged, thereby reducing the dust removal efficiency. It is generally believed that the diameter of the exhaust duct should be 0.5-0.6 times the diameter of the cylindrical body. Inserting the exhaust duct too shallowly can easily cause dusty airflow from the inlet to directly enter the exhaust duct, affecting dust removal efficiency; The deep insertion of the exhaust duct can increase the friction surface between the airflow and the pipe wall, resulting in increased resistance loss. At the same time, it shortens the distance between the exhaust duct and the bottom of the cone body, increasing the chance of secondary dust mixing and discharge. The insertion depth of the exhaust duct is generally slightly lower than the bottom of the air inlet. Due to the relatively high steel consumption per unit of cyclone dust collector, a better method in the design scheme is to gradually reduce the material thickness from the upper part of the cylinder downwards from thick to thin!
Operating process parameters
In the case of fixed size and structure of cyclone dust collectors, the key to their dust removal efficiency lies in the influence of operating factors.
velocity of flow
The cyclone dust collector uses centrifugal force to remove dust, and the greater the centrifugal force, the better the dust removal effect. The centrifugal force experienced by dust in circular motion (or curved motion) is F=ma, where F - centrifugal force, N; m - mass of dust, kg; a - centrifugal acceleration of dust, m/s2。 Because, a=VT2/R， In the formula, VT represents the tangential velocity of dust particles, m/s； R - the rotation radius of the airflow, m， So, F=mVT/R。 It can be seen that with a fixed structure (R constant) and the same dust (m stable) of the cyclone dust collector, increasing the airflow velocity of the cyclone dust collector will increase the centrifugal force of the cyclone dust collector.
The inlet air volume of the cyclone dust collector is Q=3600AVT, where Q represents the inlet air volume of the cyclone dust collector, m3/h； A - The inlet cross-sectional area of the cyclone dust collector, m2. Therefore, in the case of a fixed structure (R remains constant, A remains constant) and the same dust (m is stable), the airflow velocity of the dust collector is proportional to the inlet air volume, and the inlet air volume of the cyclone dust collector is determined by the intake air volume of the induced draft fan.
It can be seen that increasing the inlet airflow velocity can increase the tangential velocity of the airflow inside the dust collector, which increases the centrifugal force on the dust and is beneficial for improving its dust removal efficiency. At the same time, it can also increase the amount of dust treated. But as the inlet airflow velocity increases, the radial and axial velocities also increase, and the impact of turbulence increases. For each specific type of dust cyclone dust collector, there is a critical inlet airflow velocity. When this velocity is exceeded, the effect of turbulence increases faster than separation, causing some separated dust to be carried away again and affecting the dust removal effect. In addition, as the airflow increases, the dust removal resistance will also sharply rise, pressure loss will increase, and power consumption will increase. Taking into account the dust removal effect and economy of the cyclone dust collector, the airflow velocity at the inlet should be controlled between 12-20 m/s, with a maximum not exceeding 25m/s. Generally, 14m/s is recommended.
The condition of dust
The size of dust particles is a key factor affecting the outlet concentration. The dust outside the cyclone dust collector is subjected to two forces in the radial direction simultaneously. One is the centrifugal force generated by the tangential velocity of the rotating airflow, which causes the dust to be pushed outward; The other is the centripetal force generated by the radial velocity of the rotating airflow, which causes the dust to be pushed inward. At the interface between the inner and outer vortices, if the centrifugal force generated by tangential velocity is greater than the centripetal force generated by radial velocity, the dust will move towards the outer wall under the push of inertial centrifugal force and be separated; If the centrifugal force generated by tangential velocity is less than the centripetal force generated by radial velocity, the dust will enter the inner vortex under the push of centripetal force and finally be discharged through the exhaust duct. If the centrifugal force generated by tangential velocity is equal to the centripetal force generated by radial velocity, that is, the external force acting on the dust particles is zero, theoretically, the dust should rotate continuously at the interface. In fact, due to the turbulent airflow and various random factors, dust in this state has a 50% chance of entering the inner vortex and a 50% chance of moving towards the outer wall. The dust removal efficiency should be 50%. The critical dust particles separated at this time are called the segmented particle size. At this point, the interface between the inner and outer vortices is like a sieve with a divided particle size. Dust larger than the divided particle size is intercepted and captured by the sieve, while dust smaller than the divided particle size is discharged from the exhaust pipe through the sieve.
The smaller the particle size of the dust captured by the cyclone dust collector, the higher the dust removal efficiency of the dust collector. The magnitude of centrifugal force is related to dust particles, and the larger the particles, the greater the centrifugal force they are subjected to. When the particle size and tangential velocity of dust are larger, and the radial velocity and exhaust pipe diameter are smaller, the dust removal effect is better. The ash concentration in the gas is also a key factor affecting the outlet concentration. When the dust concentration increases, the dust tends to agglomerate, causing smaller dust particles to agglomerate and be captured. At the same time, larger particles will also be carried to the wall or separated by impact during their movement towards the wall. However, due to the high-speed downward rotation of the airflow inside the dust collector, the pressure at its top decreases. Some of the airflow also carries small dust particles and rotates upward along the outer wall to reach the top, then rotates downward along the outer wall of the exhaust pipe and is discharged through the exhaust pipe, resulting in the dust removal efficiency of the cyclone dust collector being impossible to reach 100%.
According to the formula for calculating dust removal efficiency, η=(1- So/Si) × 100%, where η - dust removal efficiency; So - the flow of dust at the exit, kg/h； Si - the inflow of dust at the inlet, kg/h。
Because the dust removal efficiency of a cyclone dust collector cannot be 100%, when the inflow of dust increases, although the dust removal efficiency improves, the absolute amount of dust discharged from the exhaust pipe will also greatly increase. So, to reduce the dust concentration at the discharge outlet, it is necessary to lower the dust concentration at the inlet. A multi-stage dust removal method using multiple cyclone dust collectors in series can be adopted to achieve the goal of reducing emissions.
Operating procedures
preparation
1. Check if all connection parts are securely connected.
2. Check the sealing of the joints between the dust collector and the flue, the dust collector and the ash hopper, the ash hopper and the ash discharge device, the ash conveying device, etc., and eliminate the phenomenon of ash leakage and air leakage.
3. Close the baffle valve, start the ventilation fan, and gradually start it after there are no abnormal phenomena.
technical requirement
1. Pay attention to changes in easily worn areas such as the inner wall of the outer cylinder.
2. Pay attention to the adhesion, blockage, and corrosion of dust when the temperature or humidity of dusty gases changes.
3. Pay attention to changes in pressure difference and the condition of smoke discharge. Because wear and corrosion can cause perforation of the dust collector and result in dust emissions, the dust removal efficiency decreases, the exhaust smoke color deteriorates, and the pressure difference changes.
4. Pay attention to the airtightness of each part of the cyclone dust collector, and check the changes in the gas flow rate and dust concentration of the cyclone tube.
The impact of operation
The tightness of the lower part of the cyclone dust collector is another important factor affecting the dust removal efficiency. After entering the cyclone dust collector, the dusty gas rotates in a spiral motion from top to bottom along the outer wall. This downward rotating airflow reaches the bottom of the cone and then turns upward, rotating upwards along the axis. The pressure distribution inside the cyclone dust collector is determined by the distribution of axial and radial velocities of the airflow, with relatively small pressure changes in each axial section and large pressure changes in the radial section (mainly referring to static pressure). The airflow moves in a circular motion inside the cylinder, with higher pressure on the outer side than on the inner side. The static pressure is highest near the outer wall and lowest at the axis. Even if the cyclone dust collector moves under positive pressure, the axis is still under negative pressure, and the negative pressure that extends all the way to the ash discharge port is the highest. If it is not tight enough, it will produce significant air leakage, and the dust that has settled will inevitably be carried out of the exhaust pipe by the rising airflow. So, in order to achieve the design requirements for dust removal efficiency, it is necessary to ensure the tightness of the ash discharge port, and timely remove the dust at the bottom of the dust collector cone while ensuring the tightness of the ash discharge port. If it cannot be continuously and timely discharged, high concentration dust will circulate at the bottom, causing excessive wear of the cone.
maintenance
Stable operating parameters
The operating parameters of a cyclone dust collector mainly include: the inlet airflow velocity of the dust collector, the temperature of the treated gas, and the inlet mass concentration of the dusty gas.
1) Inlet airflow velocity. For a cyclone dust collector with a certain size, increasing the inlet airflow velocity not only increases the processing capacity but also effectively improves the separation efficiency, but also increases the pressure drop. When the inlet airflow velocity increases to a certain value, the separation efficiency may decrease, wear may worsen, and the service life of the dust collector may be shortened. Therefore, the inlet airflow velocity should be controlled within the range of 18-23m/s.
2) Process the temperature of the gas. Due to the increase in gas temperature and viscosity, the centripetal force on dust particles increases, resulting in a decrease in separation efficiency. Therefore, dust collectors operating under high temperature conditions should have a larger inlet airflow velocity and a smaller cross-sectional flow velocity.
3) The inlet mass concentration of dusty gas. When the concentration is high, large particles of dust have a significant carrying effect on small particles of dust, resulting in improved separation efficiency.
Prevent air leakage
Once the cyclone dust collector leaks air, it will seriously affect the dust removal effect. It is estimated that when there is a 1% air leakage at the lower cone of the dust collector, the dust removal efficiency will decrease by 5%; When there is a 5% air leakage, the dust removal efficiency will decrease by 30%. There are three types of air leakage in a cyclone dust collector: the inlet and outlet connection flanges, the dust collector body, and the ash discharge device. The reasons for air leakage are as follows:
1) The air leakage at the connection flange is mainly caused by loose bolts, uneven thickness of gaskets, and uneven flange surfaces.
2) The main cause of air leakage in the dust collector body is wear, especially the lower cone. According to usage experience, when the dust concentration in the gas exceeds 10g/m3, a 3mm steel plate can be worn out in less than 100 days.
3) The main reason for air leakage in the ash unloading device is poor sealing of the mechanical automatic (such as heavy hammer) ash unloading valve.
Prevent wear and tear of critical parts
The factors that affect the wear of key parts include load, airflow velocity, and dust particles. The worn parts include the shell, cone, and dust outlet. The technical measures to prevent wear and tear include:
1) Prevent blockage of the dust outlet. The main method is to choose high-quality ash discharge valves and strengthen the adjustment and maintenance of the ash discharge valves during use.
2) Prevent excessive gas from flowing back into the ash discharge outlet. The ash discharge valve used should be tight and properly balanced.
3) Regularly check whether the dust collector leaks due to wear and tear, in order to take timely measures to eliminate it.
4) At the site of dust particle impact, use replaceable wear-resistant plates or add wear-resistant layers.
5) Minimize welding seams and joints as much as possible. Any necessary welding seams should be ground flat, and the inner diameter of flange stops and gaskets should be the same and maintain good alignment.
6) The tangential velocity of the airflow at the wall of the dust collector and the inlet airflow velocity should be kept within the critical range.
Avoid dust blockage and accumulation

The blockage and dust accumulation of cyclone dust collectors mainly occur near the dust outlet, followed by the intake and exhaust pipes.

1) Blockage of dust outlet and preventive measures. There are usually two reasons for the blockage of the dust outlet: one is that large pieces of material or debris (such as shavings, wood chips, plastic bags, shredded paper, torn cloth, etc.) remain in the dust outlet, and then dust accumulates around it; The second reason is that there is too much dust accumulation in the ash hopper, which cannot be discharged in a timely manner. The measures to prevent blockage of the dust outlet include adding a mesh at the suction port; Add a hand hole on the upper part of the dust outlet (cover with gasket and apply sealant).

2) Blockage of intake and exhaust ports and its preventive measures. The phenomenon of blockage in the intake and exhaust ports is often caused by improper design - slight roughness, right angles, and oblique angles in the intake and exhaust ports can lead to dust adhesion, thickening, and eventually blockage.

after-sale service:

（1）. Warranty service - Party A is responsible for the quality of the products provided during the warranty period. The warranty period for the product is twelve months from the date of manufacture

（2）. Installation and debugging - Install and debug according to the equipment layout plan and equipment foundation diagram confirmed by both parties.

（3）. Training service - The supplier sends technical personnel to assist in guiding installation, and during the trial operation period, trains the buyer's relevant operators.

（4）. Repair service - In the event of a major equipment malfunction that the buyer is unable to handle, the supplier shall arrive at the site for service within 2 days after receiving notification without special reasons.

（5）. Random files - provide product user manual and certificate of conformity.

（6）. Lifetime service - Upon expiration of the product warranty period, the seller will continue to provide lifetime service and offer discounted and paid vulnerable parts.