Ventilation of industrial premises: types, requirements, design and control

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Designing industrial premises ventilation is quite a difficult task. The creation of schemes is carried out taking into account the specifics of the enterprise. Consider further what constitutes the ventilation of industrial premises. Its types and requirements for it will also be described in the article.

Classification

The main task of the industrial premises ventilation system is to promptly "capture" all impurities and remove them. These or other settings are selected depending on the specific operating conditions. The air in the units can move mechanically or naturally. There is also a classification according to the principle of work. Ventilation can be supply, exhaust or mixed. Each group has its own subgroups of equipment. So, supply ventilation can be local. It is presented as an air shower, veil or oasis. General ventilation of industrial premises providesdispersed or directed inflow.

Natural filtration

The supply and exhaust ventilation in the production room functions due to the difference in pressure and temperature in the street and in the workshop. The driving force in this case will be thermal or wind pressure. Due to the pressure drop, the expanded masses are forced out of the workshop. In their place, in turn, are drawn cold - clean. An area of high pressure is formed in the windward section. It enhances the flow of outside air. On the leeward side, the pressure is always reduced. This contributes to the outflow of waste masses. Ventilation systems and equipment, the functioning of which is based on physical laws, are used, as a rule, in enterprises with intense heat generation. However, not always a powerful exchange will ensure the formation of proper working conditions for employees. The stronger the temperature difference between the ceiling and the floor, the higher the workshop itself, the more efficient the natural ventilation of production facilities. If there are gaps in windows and walls, doors or gates are frequently opened, drafts may appear. This helps to reduce the temperature in the shop. In the summer, in areas far from windows and doors, ventilation standards are significantly violated.

Aeration

It uses a flexible duct. Aeration is carried out according to the principle of natural draft. In some cases, during the construction of a building, the calculation of the ventilation system of the industrial premises is not carried out, the installations are not mounted. In such cases, channels and shafts operating from thermalhead. The flexible air duct is covered with a deflector. The wind blows it, due to which a rarefaction area is formed. Such ventilation ducts are widely used in agricultural and livestock farms, in small bakeries, in forges. They are installed on the highest section of the roof. Aeration is considered one of the most effective methods of natural ventilation. It is often used in factories where a large amount of heat, poisons and gases are generated.

Device

Natural ventilation of industrial premises involves the arrangement of three levels of openings with vents of a specific design. The first 2 rows are located from the floor at a height of 1-4 m. Light-aeration lamps equipped with adjustable vents are mounted in the roof. In summer, clean streams pass through the lower transoms, while dirty streams go up. When calculating the system, the area of openings and vents is determined. Windless weather is considered the worst conditions for the operation of the installation. It is taken as a starting point. In case of wind, such ventilation of industrial premises works effectively. However, with a certain strength and direction of the wind, reverse thrust may appear. As a result, air mixed with gases and dust is sent to rooms where people are. To prevent the spread of harmful substances, lanterns with wind protection are installed. In summer, the supply masses are cooled by spraying cold water into them. It comes from nozzles that are located at the vents. Atthis cooling slightly increases the humidity.

SNiP: ventilation and air conditioning

The Rules set out a number of regulations for buildings that use a natural filtration scheme. In particular, it is necessary that the perimeter of the structure be open to air. The Rules also state that workshops with a height of no more than 1 floor or those located on the top floors of buildings are aerated. In multi-span rooms, the installation of natural ventilation is significantly difficult. If the width of the workshop is more than 100 m, there is practically no clean flow to its center. In such cases, special Baturin lights (non-blown) are mounted. They have separate channels for inflow and exhaust. However, in winter, such an installation can provoke an undesirable decrease in temperature in the workshop. To prevent such consequences, forced (artificial) ventilation of industrial premises is installed.

Advantages and disadvantages of aeration

Ventilation elements are controlled mechanically. One of the main advantages of the aeration scheme is the low cost of components. In this case, the installation can provide a sufficiently powerful air exchange. Meanwhile, it also has several drawbacks. First of all, the functioning of the system depends on weather conditions. In addition, as mentioned above, it does not ensure the delivery of clean streams to remote areas of the shop. Another disadvantage is the complexity of management. Aeration is not used at enterprises where technologies are used that imply the spread of harmfulsubstances.

Forced ventilation of industrial premises

It allows you to bring the indicators of the flows supplied to the workshop to the normative ones. The required parameters are defined in SNiP. Forced ventilation and air conditioning have the following advantages:

1. The operation of the units is not related to the temperature outside the workshop.
2. You can delete streams, as well as submit them from any site.
3. System calculation is accurate.
4. It is allowed to change the multiplicity in any range. It is calculated based on the diameter and speed of the grinding/grinding wheel.

Most Popular Installations

Exhaust ventilation is now widespread. The installation restricts the spread of polluted streams and removes them directly from the source. The quality of ventilation depends on the correct selection of equipment, the degree of rarefaction of the atmosphere, the shape of the receivers. The key elements of the settings are:

1. Sucking.
2. Fan.
3. Retraction.
4. Filters.
5. Exhaust duct.

The entire volume of dirty streams should be captured by the receiver and transmitted further through other elements.

Specific blowjobs

Air inlets are of closed and open type. Latest include:

1. Protective cover.
2. Exhaust hood.

Protective cover eliminates the flow of dust, which is generated, for example, in a carpentry shop whenpolishing, grinding, etc. It is equipped with a visor and is installed across the movement of particles. The exhaust hood reduces the area of distribution of hot air containing harmful impurities and rising according to the principle of convection, and removes it. It must be of such a size as to completely cover the source. The umbrella can be equipped with overhangs. They are made of dense canvas or rigid sheets. It is more convenient to use open umbrellas. In them, overhangs do not interfere with the access of employees of the enterprise. In hazardous production, the speed of the flow entering the umbrella is from 0.5 m / s, if it is free of impurities, then 0.15-0.25 m / s.

Onboard/Articulated-Telescopic Suctions

They are installed directly at the workplace on galvanic or pickling baths. The air moves over them and draws in the harmful vapors of acids and alkalis before they begin to spread through the shop. With a small (up to 70 cm) bathtub width, single-sided suctions are installed, if this parameter is greater than the specified value, double-sided elements are mounted. In addition, the latter are equipped with structures that blow off vapors from the surface of the liquid. The volume of flow passed through these installations will depend on the level of toxicity of the steam, temperature. The size of the liquid surface is also important. Since vapors quickly destroy metal, suctions are made of PVC and other resistant materials. Articulated-telescopic receivers are quite common. Ventilation pipes for this type of hood are equipped with retractable elements. They can be brought directly tosource of pollution. In workshops with soldering irons and welding machines, suctions are installed directly into the tools.

Closed receivers

These include:

1. Cabins.
2. Fume hoods.
3. Cameras.
4. Shelter boxes.

The latter are used in enterprises with highly toxic and radioactive substances, where workers carry out all manipulations with gloves or using mechanical devices. Cabinets are mounted in workshops with intensive emission of harmful gases. Exhaust ventilation pipes with complete isolation of the source of pollution are considered the most efficient.

Electrical installations

Ventilation systems for industrial premises of forced type are equipped with special units. They are electric fans. As a rule, axial or radial models are installed. The latter are also called "snails" because of the shape of the body. A wheel with blades is built into it. In the process of movement, the flows enter the body, change direction and are fed into the outlet under pressure. The sucked-in masses are often saturated with aggressive and dangerous compounds, and sometimes with explosive substances. Depending on the impurities, the enterprises install fans:

1. Standard. They are designed to capture streams with a low content of dust, the temperature of which is up to 80 degrees.
2. Anti-corrosion type. Such installations are used to capture acid fumes andalkalis.
3. Having protection against sparks. They are used for explosive mixtures.
4. Dusty. These units are designed to filter streams containing particles greater than 100 mg/m3.

Axial fans include inclined blades mounted in a cylindrical housing. During operation, the flows move parallel to the axis. These units are usually installed in mines, emergency channels, etc. The advantage of such devices is that they can supply air in opposite directions.

Dust collectors

The current norms and standards determine the requirements for ventilation of industrial premises. Installations must operate in such a way that the content of harmful impurities is within the permissible value. Accordingly, one of the key parameters is the cleaning efficiency. In some cases, one dust collector is enough to filter the air. In this situation, cleaning is called single-stage. If air pollution is significant, multi-stage filtration is organized. The type of treatment plant will depend on the shape, chemical composition and volume of impurities. The simplest design of a dust collector is considered to be a dust settling chamber. It significantly reduces the intensity of the flow, due to which harmful impurities settle. However, this setting can only be used for primary filtration. Dust settling chambers can be labyrinthine, simple, with a baffle.

Cyclones

They are inertial dust collectors and are used to filter air withparticle content, more than 10 microns. The cyclone is made as a cylindrical metal container, tapering downwards. Air is supplied from above. Under the influence of centrifugal force, dust particles hit the walls and fall. Purified air exits through the pipe. To increase the amount of trapped dust, water is sprayed inside the housing. These installations are called cyclones-washers. Recently, rotoclons and rotary dust collectors have gained the most popularity.

Filters

They are also used to purify the air. Filters can run on electricity. In this case, positively charged particles are attracted to the negative electrodes. High voltage passes through the filter. For subsequent cleaning of the electrodes from dust, periodic automatic shaking is carried out. The collected dust is sent to the storage tanks. In practice, coke and gravel filters are also used. Fine and medium cleaning devices are made of a special material. It can be synthetics, felt, porous fabrics, nets. They capture not only dust, but also small particles of oils. However, such materials quickly become clogged and require regular cleaning or replacement. If it is necessary to filter the air from explosive compounds or gases, as well as aggressive substances, ejection systems are used. They have 4 chambers: diffuser, neck, confuser and for discharge. The streams enter them under high pressure. The direction is set by the compressor or fan. Dynamic pressure indiffuser is converted to static. After that, the flow is directed to the outside.

Alternative

Before sending the air into the room, it must be processed: warm or cool, filtered. In some cases, it also requires moisture. For these purposes, forced ventilation is used. It consists of:

1. Intake.
2. Taps.
3. Filters.
4. Heaters.
5. Fans.
6. Distributors.

Installation of installations is carried out according to certain rules. A supply chamber is provided for the fan, filter and heater. Receivers should be located at a height of 2 meters from the ground, in places remote from pollution sources. In some cases, installation above the roof of the structure is allowed. The direction of the wind must be taken into account when choosing the installation location. From the outside, the air intakes are covered with umbrellas, blinds or grilles. Filters in installations can be of various types. As a rule, devices made of non-woven materials are used. In winter, air heating is carried out with the help of heaters or heaters. Electricity or water acts as a heat carrier. For humidification, special irrigation chambers are installed. In them, a finely dispersed air fraction is sprayed. Cooling is carried out in the same way.

Field settings

These include air souls. They are pure streams directed to the working areas. The purpose of such a shower is to enhance the heat transfer of the employee's body to preventoverheating. Installations can be mobile or stationary. Hot shops are equipped with showers, as well as rooms with infrared radiation more than 350 W / m2. The norms depend on the temperature, the severity of the work, as well as the intensity of the radiation. Average t in the shower - + 18 … + 24 degrees. The flow moves at a speed of 0.5-3.5 m/s. Its indicator is directly proportional to the radiation intensity and air temperature.

Oases and veils

These devices are often used in large enterprises. Oases serve a section of the workshop, fenced off from the rest of the area with the help of light screens. Within its limits, the air moves at a certain speed and has a given temperature. Curtains are used to prevent hypothermia of workers and cooling down the workshop through openings or open doors. They can be unheated or heated.

Preventive supervision

Such sanitary control of ventilation systems of industrial premises is carried out when:

1. Reconstruction, planning, building or changing the technology/profile of an enterprise, site, workshop.
2. Starting up installed or repaired treatment plants.
3. The introduction of new technological units, processes or chemicals that can have a harmful effect on the environment or humans.

Reconstructed or newly built ventilation systems are launched by the commission in the prescribed manner. It includes a representative of the sanitary and epidemiological service. Assessment and inspection of the ventilation system can be carried out aftercompletion of all construction and installation activities. In this case, before the inspection, it is necessary to establish all technological processes in accordance with the regulations. During the survey, production facilities must operate with the planned load, ventilation devices must reach the specified performance. Preventive supervision is performed in the form:

1. Drawing up conclusions on the design materials on the correct selection of the ventilation scheme. Working and technical drawings serve as documents for verification.
2. Observation of the process of installation of ventilation units.
3. Participation in the reception and execution of conclusions on the compliance of the units with the current sanitary and hygienic regulations.

Current survey

It is carried out in the form of selective control:

1. The state of the environment in the areas where intake devices are located. Inspection can also be carried out directly at the workplace.
2. Work, condition, operation of ventilation systems.

The frequency and volume of sampling is established by the sanitary doctor. This takes into account the degree of likely negative impact of the production environment at a particular enterprise on personnel.