The important role of cement in the construction industry is something that no one can deny. However, cement dust is very toxic to both its producers, users and the outside environment. Therefore, in parallel with the promotion of cement production for construction, businesses operating in this industry need to immediately apply effective dust treatment methods to protect our life.
I. Treatment of fine dust emitted from the factory:
1/ Demand for cement: When the country is having strong changes, developing rapidly in both economic and other fields, the need to build physical facilities, industrial parks , bridges, roads, houses... are increasing day by day. Therefore, the demand for raw materials, especially cement, is extremely large.
According to preliminary statistics in 2020, our country's demand for cement is up to 112 million tons. In recent years, the cement industry has contributed a significant part to Vietnam's economic growth, averaging 10 - 12% of GDP. Therefore, the Government identifies cement as a strategic development industry to support socio-economic development.
When the demand for cement is increasing, the manufacturing companies are forced to increase their operating capacity or build more new factories. The large supply of cement promotes economic growth but also leaves many consequences for environmental pollution arising from cement dust, putting our lives in danger.
2/ Hazards from cement: If you look at it with the naked eye, you will see that the cement dust particles seem to be very small, but the danger from those dust particles is very large for people, animals, plants and animals. object.
- Animals breathing cement dust did not cause any acute or chronic pathological changes. However, dust on leaves and stems makes plants unable to photosynthesize.
- Cement dust in very fine form (particle size less than 3μm) suspended in the exhaust gas, when inhaled and lung easily causes respiratory diseases. In particular, when the free SiO2 content is greater than 2%, it is likely to cause lung silicon disease, a disease considered the most common and dangerous occupational disease of cement production technology.
- Dust is dispersed by the wind very far, settling on the ground and water, gradually damaging the soil and degrading the flora. Dust in the air is the most difficult problem in the cement industry.
3/ Methods of treating cement dust: Removing cement dust is an urgent task of cement factories, ensuring a healthy environment for people. Currently, the dust treatment system from these service providers is operating very effectively, providing customers with many different methods from the nature and size of dust particles. Some of these methods include:
3.1. Dry dust filter method
The dry dust collector works based on different settling mechanisms: gravity (dust settling chambers), inertia (dust settling by changing the direction of air flow or thanks to baffles) and centrifugation (dust collectors). single, group and combined cyclones, mechanical and dynamic dust collectors). The above dust collection devices are simple to manufacture and operate, and are widely applied in industry. However, the dust collection efficiency is not always satisfactory, so it often plays the role of preliminary treatment.
In this method, the dust treatment service provider will conduct it with many different specific equipment depending on the type of dust.
3.1.1. Dust settling chamber
The principle of operation of this device is to take advantage of the gravity of dust particles when the dust-containing gas stream moves horizontally in the device, then the dust particles are under the simultaneous effect of two forces. The force acting in the horizontal direction due to the motion of the gas stream and the force of gravity. If the horizontal force is small, dust particles may be deposited on the surface of the dust collector. To achieve that, the movement speed of dust particles must be small and the size of the dust settling chamber must be large so that the dust retention time is as long as possible.
* Advantages:
- Simple crafting
- Low equipment operation and maintenance costs
* Defect:
- The dust settling chamber is large in size and takes up a lot of space
- Performance is not high
3.1.2. Cyclone
Cyclone equipment is widely used in industry with high efficiency when the particle size is > 5μm. Dust collection in the cyclone takes place under the action of centrifugal force.
The principle of operation is as follows: The dust-contaminated gas stream is brought into the upper part of the cyclone, the body of the cyclone is usually a cylinder with a truncated bottom. The dirty air inlet pipe is usually rectangular in shape, arranged in a tangent to the cyclone body.
The air entering the cyclone performs helical motion, moves downward and forms an external vortex. At that time, dust particles under the action of centrifugal force splash into the cyclone wall. Approaching the base of the apex, the airflow begins to reverse and move upwards forming an internal vortex.
The dust particles that reach the wall move downwards by the force of the eddy current and gravity from there, out of the cyclone, through the dust exhaust pipe. Clean air after treatment is delivered at the top of the unit by the central tube.
* Advantages:
- There are no moving parts, increasing the durability of the device
- Can work at high temperature (up to 500oC)
- Dust collection in dry form
- Impedance is almost fixed and not great (250 - 1500N/m)
- Working at high pressure
- High yield, cheap
- Capable of recovering abrasives without protecting the cyclonic surface
- Performance independent of dust concentration changes
- Simple fabrication.
* Defect:
- Poor performance when dust is < 5 μm
- It is not possible to recover the adhesive dust.
3.1.3 Cloth bag filter device
The most common of these devices, the majority of cloth filters have a cylindrical sleeve filter material that is secured to the pipe mesh and is equipped with a dust collector.
There are some other methods of filtering fine dust, see details at: https://ximang.vn/kinh-nghiem-van-hanh/cac-phuong-phap-xu-ly-bui-cho-nha-may-xi-mang-13942.htm
The downside of this line is that the dust will go up a bit when the scanner is scanning, but it will settle down right away, the container is a bit small, need a gathering point or a truck if any. Very suitable for outdoor scanning, or spacious warehouse, high roof. The type of vacuum cleaner has many layers of filter: The advantage of this type is very large, it can sweep all indoor and outdoor locations, sweep very clean, no dirt comes out, the container is big (Indoor type has a small container). ). The downside is the initial investment cost is very high. The small type is 1.0 - 1.5 billion, the large size 3 - 4m3 is from 3.5 - 5.0 billion is normal, and the scanning cost of this type is high, the requirements are complicated, the damage to find things will be difficult and long. Large dust collector for outdoor Small dust collector - suitable for the house Each type has different advantages and disadvantages, it is important that you choose which criteria to suit your plant most effectively. Note that it is necessary to carefully study the type of material to be scanned to choose the right machine. For example, don't use a vacuum cleaner to remove dirt, ore, wood chips... because it's almost impossible to do, it's only suitable for sweeping leaves or simple materials. Second, to be effective, you must consider the factory area, the common aisle, the area to be scanned, to choose the machine size that can meet the smallest to the largest. If you still have doubts, please call us for the most accurate advice, we have practical programs for customers to choose the right machine for their difficulties. HOTLINE 0914 555 247/0913 888 247 In the case of small and narrow locations that cannot be accessed by large machines to perform work, or small maintenance and repair projects, cement factories, iron and steel factories, ports... Can be used to clean the required location. Although it is a bit small, it is convenient, the cost is very low, consumables are low, and the risk of failure is low. |
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