Dust removal equipment

A device that separates dust from flue gas is called a dust collector or dust collector. The performance of the dust collector is expressed by the amount of the treated gas, the resistance loss and the dust removal efficiency of the gas passing through the dust collector. At the same time, the price of dust collector, operation and maintenance costs, service life and the difficulty of operation and management are also important factors to consider its performance. Application: dust catcher is a common equipment in boiler and industrial production.

1, deal with air volume (Q)

Air handling volume refers to the amount of air that can be purified by dust removal equipment in unit time. The unit is cubic meter per hour (m3/h) or cubic meter per hour (Nm3/h). It is one of the most important factors in the design of bag filter.

According to the design or selection of air bag type dust collector, generally cannot make filter in air exceeds the specified operating conditions, otherwise, the bag is easy to plug, shorten the life span of the pressure loss increased substantially, the dust removal efficiency will decrease; but it cannot be selected volume is too large, or to increase investment in equipment and space. Reasonable choice to deal with air flow is often determined by process and experience.

2, use temperature

For the bag filter, its use temperature depends on two factors, the first is the highest filter material temperature, and the second is the gas temperature must be above the dew point temperature. At present, due to the large selection of glass fiber filter material, the maximum use temperature can reach 280 DEG C, and measures must be taken to cool the gas above this temperature, and measures must be taken to lower the dew point temperature. For the bag filter, the relationship between the use temperature and dust removal efficiency is not obvious. This is different from electrostatic precipitator. For the electrostatic precipitator, the change of temperature will affect the specific resistance of dust, and affect the dust removal efficiency.

3. Inlet dust concentration

That is to say, the concentration of inlet dust, which is determined by the process of dust removal, is another important factor after the design or selection of bag type dust collector. Represented by g/m3 or g/Nm3.

For a bag filter, the inlet dust concentration will directly affect the following factors:

The pressure loss and the cleaning cycle. As the inlet concentration increases, the ash deposition rate increases with the same filtration area, and the pressure loss increases with the result that the number of ash cleaning has to be increased.

The wear bag and box. In the case of strong abrasiveness, the amount of wear can be considered to be proportional to the concentration of dust.

The dust is necessary in advance. The advance is in front of the entrance of dust precipitator to increase the level of dust removal equipment, also known as the dust before.

The ash ash discharging device discharge ability. The ash removal capacity of the ash removing device shall be based on the total dust that can be discharged, and the amount of dust is equal to the inlet dust concentration multiplied by the treated air volume.

The mode of operation. Bag filter is divided into two modes of positive pressure and negative pressure, in order to reduce fan wear, large inlet concentration should not be used positive pressure operation.

4, the concentration of dust in the outlet

The outlet dust concentration refers to the emission concentration of precipitator, said method with the entrance of dust concentration, dust concentration of outlet size should be based on the local environmental protection requirements or user requirements as the standard, the emission concentration of bag type dust collector can usually reach below 50 g/Nm3.

5. Pressure loss

The pressure loss of a bag filter is the pressure drop, or resistance, from the inlet to the outlet of the dust collector. The pressure loss of bag dusting depends on the following three factors:

The pressure loss of equipment structure.

The pressure loss of the filter. Relating to the nature of the filter material (e.g. porosity, etc.).

The pressure loss of the accumulation of dust layer on the filter media.

6, operation pressure

The operating pressure of the bag filter is determined by the static pressure and the installation position of the device and the fan before and after the dust collector, as well as the design pressure value of the bag type dust collector.

7, filter speed

The filtration rate is an important factor in the design and selection of a bag filter. It is defined as the rate of filtration of the gas through the filter material, or the ratio of the air flow through the filter material and the area of the filter material. Units are represented by m/min.

The filter area of the bag filter is determined, and the size of the air handling depends on the selection of the filtration rate:

Q = V * s * 60 (m3/h)

Type: Q - dealing with air flow

V - filter wind speed (m/min)

S - total filtration area (M2)

Note: filter area (M2) = treatment air volume (m3/h) / (filtration rate (m/min) X60)

The filtration rate of bag type dust collector has hair filtration velocity and filtration rate of the net, the so-called gross filtration rate refers to the total volume of filtration area divided by the bag dust collector, and the net filtration rate refers to the volume divided by bag filter net filter area.

In order to improve the cleaning effect and continuous working ability, in the design of the bag filter is divided into several rooms (or area), each room has a main air valve to control the chamber in filtering state or stop filter state (online or offline). When cleaning or maintenance of a room, the main valve must stop and filter state (off-line), the air handling room completely by other burden, total filtration area of another chamber called the net filtration area. That is, the net filtration area equals the total filtration area minus the total number of cleaning rooms necessary to maintain the number of cleaning rooms and the number of maintenance rooms in operation.

8, the length and diameter ratio of the filter bag

The ratio of length to diameter of a filter bag is the ratio of the length and diameter of the filter bag. The ratio of length to diameter of the filter bag is as follows:

Blowback type - 30~40

Mechanical rocking type - 15~35

Pulse type - 18~23