Dust removal and explosion prevention in the hotte

Dust removal and explosion prevention in hemp mills

a large amount of fiber dust will be produced in the production process of hemp mills. The short fibers, flying flowers, short fibers and fine particles contained in these dust not only pose a serious threat to safety production, but also affect product quality and endanger the health of operators/Therefore, the hemp mill must establish an effective dust removal system to ensure the health of operators, product quality and production safety

I. flax dust

1 Dust generation

flax fiber is a kind of bast fiber. Its main component is cellulose, which is a high molecular carbohydrate with the molecular formula of (C6H10O5) n, accounting for about 80% of flax fiber. Others include hemicellulose, lignin, lipids, pectin, etc. Flax raw materials, that is, flax into flax, must first be combed by a comb machine, and then into strips, drawing and roving. Fibers are constantly hit, combed, drawn and other functions, and hemp dust, hemp chips, short fibers and short fibers are constantly produced in the processing process. This is the main reason for flax dust

2. Dust concentration

the textile industry generally adopts the weight concentration to calculate the dust content in the air, that is, the weight of dust in one cubic meter of air, which is called the weight concentration. At present, the # national standard stipulates that the dust concentration of combed linen and pre promoted military organosilicon material technology in flax textile mills in civil chemical spinning workshops is ≤ 8mg/m3, and the dust concentration of recycled air is ≤ 2.4mg/m3

3. Ignition and explosion of dust

flax dust is a combustible dust, a flammable substance, and has the characteristics of spontaneous combustion and hidden combustion. Under certain conditions, the dust deposited in the dust removal system should be installed with a manual switch on the wire to control the impact and disturbance of the experimental motor source, and it will fly up, forming a "dust cloud" in the air. These solid dust particles are suspended in the air, forming an aerosol state. When reaching a certain concentration, it will cause an explosion (or combustion explosion) when encountering an open fire with a minimum combustible energy above. According to relevant information, the lower limit of flax dust explosion is 16.7g/m3, and the minimum combustible energy is 0.08 joules

II. Ventilation and dust removal

1 Dedusting system

hemp has innovative and practical value. Textile mills must reasonably design dedusting system according to standards and specifications. It is not allowed to design the dust removal system as a network extending in all directions across the whole plant, and it is not allowed to share the same channel or connect the dust removal system with other pipelines such as cables and compressed air pipelines. To change centralized dust removal into small unit single machine dust removal, each branch dust removal pipeline should enter the dust removal room separately. This is mainly to prevent secondary explosion, because once a combustion explosion occurs at a certain part of the dust removal system, powerful shock waves and open flames will rush everywhere along the channel, causing the dust deposited in the channel and on the equipment to fly, causing secondary explosion

in addition, it is necessary to accurately calculate the air volume of the dust removal system, avoid horizontal or underground laying of the air duct as far as possible, and set cleaning holes or vacuum dust collector joints near the tee, elbow, reducer and other special-shaped pipelines. The dedusting pipeline shall adopt circular section and be equipped with fire damper. The hemp mill should cancel the dust removal trench and install the dust removal pipeline in the air instead of surface installation, so as to remove and avoid the dust accumulation in the trench

2. Dust removal equipment

at present, there are four kinds of dust removal equipment commonly used in China's Linen Industry:

⑴ dust removal equipment of German LTG air conditioning company. Since March, 1987, the hemp textile industry has attached great importance to dust removal and explosion prevention, and most of the hemp textile factories built at that time adopted the equipment of the company. The main precautions for using this equipment are: pay attention to the sealing of the dust removal room to avoid large air leakage loss. Frequency conversion technology can be used to save energy

⑵ L01 compound concentric circle dust filter. The PVC plastic floor spring door jg/t3051 ⑴ 998 of the vacuum cleaner is composed of multi-layer filter cloth in the form of concentric circles. The dust is adsorbed on the filter cloth and then sucked away by the suction nozzle. There is no need to set a negative pressure chamber, so there is no problem of air leakage loss

⑶ full function electrostatic curtain type high-efficiency dust removal unit. The unit is a new product developed in recent years. It is also a primary and secondary filter, which can effectively remove micro dust and sub micro dust. It is suitable for occasions with large air volume, and the effect is good

⑷ XL2 composite dust collector. This kind of dust remover is a new type of dust remover produced in China based on the introduction and digestion of "Luowa" dust remover. The dusty air passes through the first stage filtration of the cyclone head, and then carries out the second stage filtration. The secondary filtration of this vacuum cleaner can be selected in two forms: movable suction nozzle or rotating cage. The dust collector has the advantages of simple structure, no need to set a dust removal room, good dust removal effect, low price and so on