What are the advantages and disadvantages of dust collectors, cyclones?

A dust collection hood is set up in each ash place, and the dust-containing gas is transported to the dust removal device through the pipeline gas path, in which the dust is collected in the dust removal device after the gas-solid separation is carried out, and the clean gas is introduced into the main pipe or directly discharged into the whole set of equipment into the atmosphere, that is, the dust removal system, and the dust collector is an important part of the system. From the perspective of ventilation and dust removal, dust is all solid small particles that can float in the air for a long time, and is a dispersion system, called aerosol, in which air is the dispersed medium and solid particles are the dispersed phase. A dust collector is a device that separates these small solid particles from aerosols.

Cyclone dust collector is a type of dust removal device. The dust removal mechanism is to make the dust-containing air flow rotate, with the help of centrifugal force to separate the dust particles from the air flow and trap them on the wall, and then with the help of gravity to make the dust particles fall into the ash hopper. Each component of the cyclone dust collector has a certain size ratio, and the change of each proportion relationship can affect the efficiency and pressure loss of the cyclone dust collector, in which 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, it should be noted that when a certain limit is exceeded, the favorable factors can also be transformed into disadvantages. In addition, some factors are beneficial to improve the efficiency of dust collection, but will increase the pressure loss, so the adjustment of various factors must be taken into account.

The cyclone dust collector is composed of an intake pipe, an exhaust pipe, a cylinder, a cone and an ash hopper. Cyclone dust collectors have a simple structure, easy to manufacture, install and maintain management, and have low equipment investment and operating costs, and have been widely used to separate solid and liquid particles from gas streams, or from liquids. Under normal operating conditions, the centrifugal force acting on the particles is 5 2500 times that of gravity, so the efficiency of the cyclone is higher than that of the gravity settling chamber.

It is suitable for the removal of non-viscous and non-fibrous dust, mostly used to remove particles above 5 m, and the parallel multi-tube cyclone dust collector device also has a dust removal efficiency of 80 to 85% for particles of 3 m.

Cyclone dust collector.

Cyclone dust collector is mainly used in the industrial field to treat waste gas containing solid particles, such as dusty waste gas generated in the industrial production process of coal, cement, metallurgy, chemical industry, building materials and other industries. Cyclone dust collectors can effectively remove particles larger than 5 microns in diameter, and the removal effect of particles smaller than 5 microns is relatively poor, so they usually need to be used in conjunction with other dust collection equipment such as electrostatic precipitators or baghouses to achieve better dust removal results.

The dust collection efficiency of a cyclone dust collector is related to the particle size of the dust particles. The larger the particle size, the higher the efficiency, when the particle size is large to a certain value, the dust removal efficiency of the cyclone dust collector can reach 100%. So what are the main factors that affect the efficiency of cyclone dust collectors?

1. Inlet flow rate.

Increasing the flow rate of the inlet pipe within a certain range can improve the efficiency of dust removal. However, if the inlet flow rate is too high, some of the separated dust particles will be swept away by the inner swirl, resulting in a decrease in dust removal efficiency. In addition, the pressure loss is proportional to the square of the inlet velocity, and if the inlet flow velocity is too large, the pressure loss rises.

Thus. From the comprehensive consideration of technology and experience, the appropriate range of inlet flow rate is generally 12-20m s, and should not be less than 10m s, so as to prevent dust accumulation in the inlet pipeline.

2. The structural size of the dust collector.

The smaller the diameter of the simplified body, the greater the centrifugal force on the dust particles and the higher the dimensional efficiency at the same tangential speed. The change of the height of the simplified body has no obvious effect on the dust removal efficiency, and the appropriate lengthening of the height of the vertebral body is conducive to improving the dust removal efficiency.

3. Dust particle size and density Because the centrifugal force of dust particles is proportional to the cubic of particle size, and the radial gas resistance is only proportional to the primary square of particle size, large particle size is easier to capture than small particle size. The dust removal efficiency increases with the increase of the true density of dust particles, and the dust removal efficiency decreases when the density is small and difficult to separate.

4. Gas temperature and viscosity.

The gas viscosity increases with the increase of temperature, and the segmentation particle size is proportional to the square root of the viscosity again, so the dust removal efficiency of cyclone dust collector decreases with the increase of gas temperature and viscosity.

5. The air tightness of the lower part of the dust removal equipment.

The static pressure inside the dust collector gradually decreases from the outer wall to the center, and even if the dust collector is operated under positive pressure, the bottom of the cone may be in a negative pressure state. If the lower part of the dust collector is not strict and leaks air, the dust that has fallen into the ash hopper will be taken away again, so that the dust removal efficiency will be significantly reduced.

Principle: The cyclone dust collector is a dust removal device that uses the centrifugal force generated by the rotating air flow to separate the dust particles from the combined dust gas flow. It has the advantages of simple structure, small size, no special auxiliary equipment, low cost, medium resistance, no moving parts in the device, and convenient operation and maintenance.

The cyclone dust collector is generally used to capture particles above 5-15 microns, and the dust removal efficiency can reach more than 80, and the special cyclone dust collector that has been improved in recent years can have a dust removal efficiency of more than 5. The disadvantage of cyclones is that they are not very efficient at capturing particles smaller than 5 microns

Overview of the movement of air flow and dust particles in the cyclone dust collector:

The vast majority of the rotating air flow is from the circle along the wall of the vessel, moving from top to bottom to the bottom of the cone in a spiral shape, forming a descending external rotation dust-containing air flow, and the centrifugal force generated in the strong rotation process throws the dust particles with a density much greater than the gas to the wall of the vessel, and once the dust particles are in contact with the wall of the vessel, they lose their inertial force and fall along the wall surface by the momentum of the inlet velocity and their own gravity to enter the ash hopper. After reaching the bottom of the cone, the rotating descending airflow turns upwards along the axis of the dust collector to form an upward internal spiral airflow, which is discharged by the exhaust pipe of the dust collector.

Another small part of the air flow from the air inlet flows to the top cover of the cyclone dust collector, and then flows down the outside of the exhaust pipe, when it reaches the lower end of the exhaust pipe, that is, the reverse turn is discharged from the air pipe with the rising central airflow, and the dust particles scattered in it are also carried away.

According to the principle, the individual estimate of the drag is related to the diameter of the air inlet, the wind force, and the size of the fine dust.

There are several factors that affect the efficiency of a cyclone dust collector:

1. The size and specification of the cyclone dust collector design: the diameter and height ratio of the cyclone dust collector cylinder affect the efficiency of the dust collector; the influence of the diameter and depth of the ash discharge opening; Lengthening the cone appropriately is also beneficial to improving the efficiency of dust removal.

2. The tightness of the lower part of the cyclone dust collector will also affect its dust removal efficiency.

3. Inlet wind speed: generally the inlet wind speed is kept at 12-25m s, when it is lower than 12m s, its dust removal efficiency decreases, and when it is higher than 25m s, the dust removal efficiency is not significantly improved, but the resistance loss increases and the energy consumption increases.

4. The temperature of the gas: the viscosity of the gas increases with the increase of temperature, so that the centripetal force of the dust particles increases, and the separation efficiency decreases, so the efficiency of the dust collector of the cyclone dust collector decreases with the increase of gas temperature or viscosity.

The size of the cyclone dust collector (the diameter of the conical body) and the air inlet speed are comprehensively affected 1) At a certain wind speed, the smaller the diameter of the body, the higher the dust removal efficiency, but it should be noted that the diameter should not be too small, if it is too small, it will affect the rotation direction of the wind, but lead to low dust removal efficiency.

2) Under the condition of a certain body size, the higher the wind speed, the higher the dust removal efficiency, but it should also be noted that too high the wind speed will take away the dust that has been successfully separated again, affecting the dust removal efficiency.

The size of the dust particles.

The larger the dust particles, the easier they are to separate.

The air tightness of the dust collector must be done well.

The cyclone dust collector must be equipped with a receiving hopper, without a collecting hopper, the separated dust will easily be taken away again.

Pure hand-made, 30 years of experience in dust collector design.

1. Air intake. The air inlet is an important component in the whole dust collector, and it also affects the dust collection efficiency. The smaller the area of the air inlet, the greater the airflow velocity, and the higher the dust removal efficiency, which is more conducive to the separation of dust from other things.

2. The diameter and height of the cylinder affect the efficiency of the machine. The rotating air velocity is the same, and the larger the diameter of the cylinder, the smaller the centrifugal force of the air flow on the dust, and the lower the dust removal efficiency, which is not easy to be sucked into the machine. Therefore, the diameter of the air inlet of the dust collector is not easy to be too large, and the air inlet should not be too small, if the dust particles are large, the air inlet may be blocked.

3. The diameter and depth of the exhaust pipe also affect the dust removal efficiency. The diameter of the exhaust pipe mouth is small, the airflow is small, and it is difficult for dust to be discharged from the exhaust pipe, so it is necessary to speed up the air outlet and increase the diameter.