Dust dust removal equipment

The equipment to separate dust from the flue gas is called dust collector or dust removal equipment. The performance of the dust collector is expressed by the amount of gas that can be treated, the resistance loss of the gas through the dust collector and the efficiency of the dust removal. At the same time, the price of dust collector, the cost of operation and maintenance, the length of service life and the difficulty of operation management are also important factors to consider its performance. Purpose: dust collector is a common facility in boilers and industrial production.

1, treatment of air volume (Q)

Processing air volume refers to the volume of purified gas in the 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.

When the bag type dust collector is designed or selected according to the air volume, the dust collector can not normally run under the condition of the prescribed air volume. Otherwise, the filter bag is easy to block, the life span is shortened, the pressure loss is greatly increased, the dust removal efficiency is also reduced; but the equipment investment and the area can not be increased if the air volume is too large. Reasonable selection of air volume is usually based on technological conditions and experience.

2. Use temperature

For the bag filter, its use temperature depends on two factors, the first is the highest temperature of the filter material, and the second is that the gas temperature must be above the dew point temperature. At present, because of the large selection of glass fiber filter material, the maximum use temperature can reach 280 degrees C. It must take the cooling measures to the gas above this temperature, and the temperature measures must be taken for the gas below the dew point temperature. For the bag filter, the relation between the use of temperature and the efficiency of dust removal is not obvious, which is different from the electrostatic precipitator. For the electrostatic precipitator, the change of temperature will affect the specific resistance of the dust and so on.

3. The dust concentration at the entrance

That is, the concentration of the entrance dust, which is determined by the technology of the dust point, is another important factor second only to the air volume when the bag type dust collector is designed or selected. It is represented by g/m3 or g/Nm3.

For bag filters, the dust concentration at entry will directly affect the following factors:

(1) pressure loss and ash clearing cycle. With the increase of inlet concentration, the ash deposition rate is fast and the pressure loss increases with the same filter area. The result is that the ash removal frequency has to be increased.

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

(3) whether it is necessary to collect dust. Pre dust collection is to add a level of dust removal equipment before the entrance of the dust collector, also known as the pre stage dust removal.

(4) the ash discharging capacity of the ash discharging device. The ash removal capacity of the ash removal device shall be based on the dust that can be discharged. The dust quantity is equal to the inlet dust concentration to be treated by the volume of air.

The mode of operation. The bag filter is divided into two operation modes: positive pressure and negative pressure. In order to reduce fan wear, the positive pressure operation mode is not suitable for large inlet concentration.

4. The dust concentration in the outlet

The dust concentration of the exit means the discharge concentration of the dust collector, indicating that the method is with the dust concentration at the entrance. The size of the export dust concentration should be based on the requirements of the local environmental protection or the requirements of the users, and the discharge concentration of the bag type dust collector can generally reach below 50 g/Nm3.

5, pressure loss

The pressure loss of bag type dust removal refers to the pressure drop or resistance of the gas from the inlet of the dust collector to the outlet. The pressure loss of bag dedusting depends on the following three factors:

(1) the pressure loss of the structure of the equipment.

(2) the pressure loss of the filter material. Relating to the properties of a filter (such as porosity, etc.).

(3) the pressure loss of the dust layer accumulated on the filter material.

6. Operation pressure

The operation pressure of the bag type dust collector is determined by the static pressure value and the installation position of the device before and after the dust collector and the installation position of the fan. It is also the design of the bag type dust collector.

7. Filtration speed

Filtering speed is an important factor in the design and selection of bag type dust remover, which is defined as the speed of filtering gas through filter material, or by the ratio of the air volume of filter material and the area of the filter material. The unit is represented by m/min.

When the filter area of bag filter is determined, the volume of air handling depends on the selection of filtration rate.

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

Q - handling air volume

V - filtering wind speed (m/min)

S - total filter area (M2)

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

The filter speed of the bag type dust collector consists of the speed of wool filtration and the net filtration rate. The so-called wool filtration speed refers to the total area of the treatment of the air volume divided by the bag dust collector, while the net filtration speed refers to the net filtration area of the treatment air quantity divided by the bag dust collector.

In order to improve the efficiency of cleaning and continuous work, the bag filter is divided into several rooms (or areas) in the design, and each chamber has a main valve to control the filter or stop filter state (online or off-line state). When a room is cleaned or repaired, its main valve must be closed in a stop filter state (off-line state). At this time the air volume is completely borne by the other chambers, and the total area of the other rooms is called the net filter area. That is to say, the net filtration area is equal to the total filtration area minus the total filter area that must be kept in operation and the number of maintenance rooms.

8. The ratio of length to diameter of filter bag

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

Anti - blow type - 30~40

Mechanical rocking type - 15~35

Pulse type - 18~23