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You are here: Home » Information Center » Dust Removal Equipment-Dedusting Treatment in Production Workshop

Dust purification equipment-dust removal treatment in production workshop

作者: 人气: Article Source: Author: Popularity: Issuing time: 2017-6-24 10:58:45



Dust purification equipment-dust removal treatment in production workshop



Various types of dust pollution exist in the building design of various types of factories, including chemical and pharmaceutical, food processing, metallurgy, casting, carbon materials, mechanical processing, building materials and other industries, especially in pharmaceutical production lines, tablet presses, manufacturers Granulators, mixers, ingredients, mixes, shakers, pulverizers, weighing, capsules, traditional Chinese medicine pretreatment and other pharmaceutical processes require dust removal and purification of the air. A complete dust removal system should include the following processes:

1. Use the dust extraction hood to capture the dusty gas generated during the process.
2. The captured dust-containing gas is transported to the dust removal equipment along the air duct under the action of the fan.
3. Separate the dust in the dust removal equipment.
4. The purified gas is discharged to the atmosphere.
5. Collect and dispose of the separated dust.

Therefore, the dust removal system of industrial buildings is mainly composed of dust extraction hoods, air ducts, fans, dust removal equipment, dust conveying devices and so on. In other words, the dust removal system is a local mechanical exhaust system that connects the dust extraction hood, fan, and dust removal equipment by the air duct.

In the design of HVAC dust removal pipelines in pharmaceutical plants, the selected dust collector is mainly for the partial dust removal of dust generated during the production of process equipment. According to the characteristics of dust generation. In general, the dust removal equipment used in pharmaceutical factories is a filter type dust collector. The following types of dust collectors are commonly used.

1.Bag type dust collector

The dust removal efficiency is high, and the efficiency of fine dust can reach more than 99%.
It is not suitable to purify dusty gas containing oil mist, condensed water and dust, and there is a risk of explosion or smoke with sparks.
When the dust concentration is greater than 10g / m3, it is advisable to add a pre-purification dust collector.

See recommended flow rates for bag filters.
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The bag type dust collector is a dry type high-efficiency dust collector, which utilizes the filtering effect of a porous bag filter element to remove dust. Because it has high dust removal efficiency (for 0.1um dust, the efficiency is as high as 98% ~ 99%), strong adaptability, flexible use, simple structure, stable work, easy dust recycling, and simple maintenance. Therefore, bag dust collectors have been widely used in different industrial sectors such as metallurgy, chemistry, ceramics, cement, and food. Among various high-efficiency dust collectors, they are the most competitive dust removal equipment.

The working principle of the bag filter: The filter material used in the bag filter has a larger mesh, generally 20 ~ 50um, and the filter material on the surface is about 5 ~ 10um. Therefore, the dust removal efficiency of the new filter bag is only about 40% (1um dust). When the dust-containing air passes through the filter material, due to the sieving, interception, collision, diffusion, and static effects of the fiber, the dust is retained on the filter material to form a preliminary layer. Compared with filter media, the porous primary layer has higher dust removal efficiency. Therefore, the filtering effect of the bag filter mainly relies on this initial layer and the dust layer that gradually builds up later. With the thickening of the dust collecting layer, the pressure difference between the two sides of the filter bag becomes larger, which increases the resistance loss of the dust collector and reduces the amount of processed gas. At the same time, because the speed of air passing through the pores of the filter material is accelerated, the dust removal efficiency is reduced. Therefore, after the dust collector runs for a period of time, the dust is cleaned to remove the dust collecting layer, but the initial layer is not damaged, so as not to reduce the efficiency. Filtration process of filter material

2.Filter cartridge dust collector

Cartridge sub-micron filtration, create clean space, automatic offline ash cleaning, local collection, convenient local operation and maintenance, suitable for various independent or multiple dust production points

The working principle of the filter cartridge dust collector: After the fan is turned on, the dust-containing air enters the cabinet from the dust source through the dust removal hood, air duct, and air inlet. Due to the sudden expansion of the air flow, the flow rate suddenly decreases, and the large particles pass through the powder under its own weight. The dusty air is separated and settled into the ash drawer. The remaining dust particles are trapped on the outer wall of the filter element due to the filtering, collision, hooking, static electricity and other effects of the filter element. The purified air is discharged from the outlet through the fan.


As for wet dust collectors, electrostatic precipitators can also be applied in the dust removal systems of pharmaceutical plants, but they are rarely used in actual production. Therefore, the above two types of dust collectors are commonly used for the dust removal systems of pharmaceutical factories.

Division of dust removal system:

For pharmaceutical companies, they may encounter dust removal for different substances. At this time, we must pay attention to the division of them. For example, in the decoction pieces workshop, you may encounter a toxic depot piece with a divided area. At this time, it is necessary to separate the dust removal of the toxic depot piece into a system separately from other workshop and workshop dust removal systems.

The division of the dust removal system should meet the following requirements:

1. When the dust points of the same production process and working at the same time are not far apart, they should be combined into a system.

2. Dust spots that work at the same time but have different types of dust. When the process allows different dusts to be mixed for recycling or the dust has no recycling value, a system can also be set up.

3. For dust-containing gases with different temperature and humidity, when mixing may cause condensation in the air duct, separate systems should be installed.

Pay attention to the following points when designing the dust removal system:

1. The exhaust point of the dust removal system should not be too many, in order to balance the resistance between the branches. If there are too many exhaust points, a large-section collecting pipe can be used to connect the branches. The collecting pipe flow rate should not exceed 3m / s.

2. In order to prevent dust from being deposited in the air duct, the air duct of the dust removal system should be laid vertically or obliquely. When inclined, the angle with the horizontal plane should be greater than 45 °. If it must be laid horizontally, a cleaning port should be provided.

3. Due to the high wind speed of the dust removal system, the duct is usually a circular duct with a smaller diameter. However, in order to prevent clogging of the air duct, the diameter of the dust removal air duct should not be smaller than the following data;
Discharge fine dust (mineral dust) 80mm
Discharge coarse dust (such as sawdust) 100mm
Discharge coarse dust (such as shavings) 130mm
Distribute wood chips 150mm

4. The hydraulic balance required by the duct of the dust removal system is good. For hydraulic calculation of parallel pipes, the general ventilation system requires that the pressure loss difference between the two pipes does not exceed 15%, and the dust removal system requires that the pressure loss difference between the two pipes does not exceed 10% to ensure that the air volume of each pipe meets the design requirements.

5. The size of the wind speed in the duct of the dust removal system, in addition to considering the impact on the economics of the system, it must also consider that the excessive wind speed in the duct will accelerate the wear of equipment and air ducts; too small a wind speed will cause dust deposition and blockage pipeline. In order to prevent dust deposition and blockage in the pipeline, the wind speed in the pipeline must not be lower than the minimum air velocity listed in the table below.


Dust removal system Minimum air velocity in the duct (m / s) Dust properties Vertical pipe Horizontal pipe Dust properties Vertical pipe Horizontal pipe Powdery clay and sand 11 13 Iron and steel (chips) 19 23 Refractory mud 14 17 Lime, sand and dust 16 18 Heavy Mineral dust 14 16 Sawdust and shavings 12 14 Light mineral dust 12 14 Large dry wood dust 14 15
Dry sand 11 13 Dry dust 8 10 Coal ash 10 12 Dye dust 14 ~ 16 16 ~ 18 Wet mud (less than 2% moisture) 15 18 Large wet wood chips 18 20 Iron and steel (dust) 13 15 Grain dust 10 12 Cotton wool 8 10 hemp (short fiber dust, impurities) 8 12 cement dust 8 ~ 12 18 ~ 22


In practical applications, the following problems are commonly encountered in dust removal systems:


1. In the design of the workshop of a pharmaceutical factory with relatively much dust, due to the large number of dust production points, the dust removal pipeline is too long during the layout, which affects the dust removal effect. Therefore, in the initial layout, try to arrange the dust removal equipment near the dust production point. If it is restricted by conditions, it is best to use other forms of dust removal, such as a mobile dust collector, or a direct exhaust system to directly discharge the points with less dust production.


2. In order to ensure the normal operation of the dust removal system and prevent the environment from being polluted again, the dust collected by the dust collector should be properly disposed of. Its treatment principle is to reduce secondary dust, protect the environment and recycle, turn harm into profit, turn waste into treasure, and improve economic benefits. Depending on the conditions of the production process, the nature of the dust, the value of recycling, and the amount of dust to be processed, local recycling, centralized recycling, and centralized disposal can be used.