Features and organization of ventilation in production. What types of ventilation are used in modern industries Natural ventilation in production

Industrial production is characterized by specific working conditions, among which there may be toxic, gas, thermal emissions from process equipment into the environment. In order to eliminate such negative factors, industrial ventilation is organized inside the industrial workshop - a complex, multi-level system for normalizing microclimatic indicators. Designed to remove harmful heat and gas emissions from industrial equipment from the working area of ​​personnel.

Types of industrial ventilation

The classification of industrial ventilation is carried out according to the criteria of localization, direction and mode of operation. Let's consider in more detail.

According to the principle of operation

• Natural. It is based on the natural circulation of air flows with different temperatures, pressures, and densities. A heavy cold air stream displaces a lighter and warmer one. In an industrial premises, this process can occur through natural gaps, leaks in window doorways, or organized supply and exhaust openings, closed with gratings, deflectors.
  Depends on atmospheric conditions, strength and direction of the wind, season (in winter, ventilation is better due to strong draft). This method is not suitable for all industries, especially where there are harmful emissions from operating equipment. It can be installed, for example, in agricultural premises.

• Artificial ventilation. If production involves a side effect in the form of toxic heat and gas emissions, mechanical ventilation of production facilities is strictly required. The main function is to divert the exhaust air flow from the working area of ​​the personnel, prevent the penetration of harmful vapors into other rooms, compartments, as well as supply fresh outdoor air (purified or unpurified) by the general flow or by address.
  It is organized with the help of mechanical means of supply and removal of air masses (supply, exhaust fans, roof units). It is a more efficient way of cleaning, circulating the air flow inside the industrial workshop.

According to the principle of localization

• General exchange. It is designed for uniform cleaning of the entire workshop from harmful technological heat emissions, normalizing the temperature and humidity index, air speed. Quickly copes with a small percentage of air pollution.
• local ventilation. It is used when there is a localization of a large amount of toxins, vapors, smoke, etc. in a certain place. It is installed directly above the source of increased heat and gas emission. Hoods or a flexible duct connected directly to the equipment may be used. It is used in conjunction with the general ventilation system as an additional air-purifying equipment.
• Emergency. It is installed and used in the future in case of emergency, for example, fire, excessive release of toxic substances from industrial equipment, high levels of smoke, etc.

According to the principle of flow direction

• Supply ventilation installations. The principle of operation is based on the displacement of warm exhaust air by a cold influx through organized exhaust openings at the top of the workshop. They can be both natural organization and mechanical.
• Exhaust ventilation units remove the exhaust air flow together with burning particles, smoke, toxic fumes, excess heat, etc. Structurally, they can be general or local, most often with forced motivation, since it is rather problematic to remove polluted air naturally.
• The air handling unit is used most often, it provides the necessary circulation of air masses inside the industrial workshop. Most often with mechanical equipment (supply, exhaust fans).

Equipment for ventilation of industrial premises

The forced ventilation system consists of the following elements:

• air ducts;
• fan;
• air filters;
• air valves;
• air intake grilles;
• noise-absorbing insulation;
• air heater (air heating);
• automatic control unit if necessary.

The mechanical exhaust ventilation device is organized according to the same model, with the exception of the heater, filters, which are not needed for the exhaust air.

Local exhaust ventilation of industrial premises is organized by exhaust hoods, flexible air ducts connected to a common air exchange system.

In addition, supply and exhaust ventilation can be equipped with a heat recuperator to save energy during the heating of the incoming flow. The supply masses are heated by the heat of the exhaust air, without mixing with it.

Industrial ventilation requirements

Ventilation and air conditioning of industrial premises is regulated by the general requirements of SanPiN, as well as by the parameters specific to the given workshop of the enterprise. These include:

• mechanical ventilation of industrial premises must comply with fire safety rules;
• removal of substances hazardous to health, emissions without access to the work area of ​​personnel;
• obligatory hygienic and fire safety certificate of the materials from which the elements of the ventilation system are made;
• anti-corrosion coating of air ducts, or they must be made of materials resistant to such influences;
• the thickness of the coating of ventilation ducts with combustible paint should not exceed 0.2 mm;
• for personnel working areas located directly inside the workshop, the concentration of harmful substances should not exceed 30%;
• humidity, speed indicators of air flow are not standardized in the summer;
• in winter, the temperature indicator of the air inside the workshop with the personnel located there is at least 10⁰ C, in the absence of people - at least 5⁰ C;
• in summer, the temperature indicators of the internal and external air flows are equal, or the internal temperature does not exceed the external one by more than 4⁰ С;
• the requirements for industrial ventilation that are not used in the summer of the workshop are not regulated by the temperature indicator;
• the total noise level inside the industrial hall should not exceed 110 dBa, this includes the operating noise of the ventilation system.

The above list is quite general. In practice, the requirements for ventilation of industrial premises are supplemented by individual parameters of production, the design of the workshop, the specifics of products, etc. In addition, it is imperative to take into account how heating and ventilation interact inside the workshop. And it should also be taken into account that lighting and ventilation of industrial premises are also interconnected.

Ventilation device. Stages of work

According to SNiP, industrial ventilation and air conditioning must be installed in all rooms of the workshop, without exception.

Ventilation and air conditioning of industrial premises perform the following tasks:

• removal of air masses filled with excessive heat, toxic fumes, gas formations, burning particles, smoke, etc.;
• additional cleaning by the filtration system of the air flow coming from the process equipment and containing hazardous impurities;
• supply of personnel with a constant supply of fresh air, normalization of the temperature and humidity balance, which determines the sanitary and hygienic control.

Installation of a ventilation system for industrial premises takes place in several stages:

• preparatory - the initial stage at which the design is carried out, the corresponding calculations. Based on this, the optimal equipment is selected, components, main elements, assemblies are transported;
• assembly - there is a compilation of individual elements, air ducts into a single complex. The ventilation system is mounted, the electrical component is assembled, connected to the mains;
• commissioning - a test check of the correct functioning, quality, efficiency, signing the commissioning certificate.

Design of ventilation of industrial premises

The design of industrial premises ventilation is a complex, multi-component process that is best entrusted to professional design engineers with many years of experience in this field. The list of actions carried out in the design of the ventilation system of industrial premises:

• preparation of technical specifications for design, which includes the necessary requirements for the organization of air exchange, parameters of technological equipment;
• approval of the terms of reference;
• an aerodynamic calculation of general ventilation, local air exhausts in industrial premises is carried out, the purpose of which is to determine the optimal internal section of the air ducts;
• selection of ventilation equipment according to the calculated characteristics, parameters;
• selection of additional elements necessary for adjustment, balancing of the ventilation system;
• drawing up drawings of the future ventilation system using specialized programs;
• drawing up schemes for the distribution of key components of the system in accordance with the norms and requirements.

Ventilation of industrial buildings. Documentation

The required documentation for the design and installation of a ventilation system includes:

• basic information about the specifics of production, the design of premises, buildings;
• general scheme of the optimal location of ventilation equipment;
• specification of the ventilation system;
• a list of materials from which it is necessary to make elements of the future installation;
• documents on thermal, fire insulation of ventilation ducts;
• ventilation network drawings, including a building scheme, floor level marks, dimensions and diameter of ventilation ducts, intersection of air ducts with other structural elements and sections of their insulation;
• separate drawings of important nodal connections, joints;
• schemes of non-standard fasteners, if they will be used;
• schemes of atypical structures, elements, nodes.

To carry out the installation of the ventilation system, a technological map is required, which determines the list of parameters that must be performed:

• features of the installation work associated with the specifics of production;
• requirements for the transportation of materials, products, the quality of work performed, insurance work, etc.;
• schemes of production quality control of the work carried out;
• determination of the degree of quality of equipment, materials, work technology;
• a list of necessary transport, material, technological resources;
• installation work schedule;
• technical, economic costs.

Calculation of the ventilation system of the production room

Calculation of the ventilation of the industrial premises should be carried out only by highly qualified specialists. The process is quite complex, taking into account many nuances that need to be linked into an overall effective ventilation scheme so that it shows the necessary results.

At the same time, it must be remembered that the calculation always takes into account the types of ventilation of industrial premises that it is decided to install. As an example, we briefly present two calculation formulas.

The first of them is used for workshops in which there are no emissions harmful to human health:

L = I * n

L- the required flow of air masses for a particular workshop, room;

I- air consumption for one person, determined by sanitary and hygienic, building codes;

n- the number of personnel.

For premises where emissions of hazardous substances by process equipment are expected, another calculation formula is used:

L = Lm.v. +(mc.c. -Lm.v. (Su.v. - Sp.v.)) / (C1 - Sp.v.)

Lm.v.- air flow removed by local exhausts;

mc.c.– hazardous substances (mg/h) coming from outside;

Su.v.– amount of hazardous substances (mg/m³) in the exhaust air;

Sp.v.- the amount of toxic substances in the supply air;

C1– amount of hazardous substances (mg/m³) allowed by the regulations.

If several types of hazardous substances are released, for each of them calculations are made according to this formula, the results are summarized.

Industrial ventilation installation

Industrial exhaust, supply ventilation systems are launched into the installation process only after the project has been approved, all preliminary work has been carried out and agreed. The place of installation, the location of the main elements is determined at the design stage.

First, the main structural elements are mounted. After that, the air duct system is divorced from them. During installation, many features are taken into account, for example, the spatial orientation of ventilation ducts, their material, ceiling design, building elements, the presence of beams, etc.

All this directly matters for how the ventilation units, duct pipes will be attached. In industrial workshops, ventilation ducts are mounted to the ceiling. For commercial premises, it is preferable to use plastic channels due to their more attractive design. Most often, rigid or flexible air ducts are used, which have their own advantages and features.

Installation is carried out in strict accordance with the project, calculations, while observing the necessary requirements for ventilation of industrial premises.

Production control of ventilation

To monitor the quality of the microclimatic environment directly inside the working area of ​​the personnel, production control of ventilation is carried out. It is necessary to distinguish between checking the efficiency of the functioning of the ventilation system, air ducts and production control of ventilation systems.

In the first case, it is meant to check the air flow inside the ventilation ducts, distribution grilles, the compliance of these indicators with the design calculations is checked.

In the second, production control of ventilation means taking the parameters of the air environment in the working area of ​​the personnel, determining the level of humidity and temperature for compliance with sanitary standards. Also, the control of ventilation systems of industrial premises is designed to monitor the level of hazardous, toxic substances in the air flow, whether the designed air exchange rate is observed.

This procedure is quite expensive and is carried out by accredited laboratories. As a rule, production facilities with the release of hazardous substances into the air in the course of their activities are inspected, as well as healthcare institutions, other socio-cultural, socially important facilities that are subject to periodic inspections by the state.

Performs the following tasks:

• control of ventilation systems of industrial premises is designed to ensure safe working conditions, primarily for personnel;
• provides safe conditions for the production itself;
• monitor temperature and humidity indicators, air exchange rate parameters, concentration of harmful vapors in the working area for subsequent adjustment of the ventilation system (if necessary);
• minimize the occurrence of dangerous, emergency situations at work.

Ventilation in the production shop is a complex set of interrelated processes and devices, aimed at creating high-quality air exchange inside the production room.

The shop floor ventilation system plays a much more important role than a similar system in any other room. The main emphasis is that this is a whole system of engineering developments, which is designed to ensure uninterrupted air filtration from harmful and toxic impurities and its functional circulation, without disturbing the course of technological processes, but contributing to favorable conditions for their successful implementation.

Types of ventilation of industrial shops

Depending on the method of air movement, ventilation of production workshops can be:

• natural;
• mechanical.
  

In the first case, air exchange occurs due to the temperature difference and the difference in pressure of the air flows. This type of ventilation can be unorganized (based on elementary physical phenomena - for example, a draft) and organized (aeration). To do this, special structures are used (for example, boxes with barriers), which allow you to adjust the size and strength of the air flow.

Mechanical ventilation allows pre-treatment of supply air (cooling, heating, humidification) and filtration of polluted air before being released into the atmosphere.

* When creating a project for the ventilation of a workshop and determining the norms of air exchange for natural and mechanical ventilation, they are guided by SNiP 41-01-2003.

As an engineering and technological object, the ventilation of industrial workshops can be divided into 2 types, according to the method of organizing air exchange:

• local type;
• general type.

In the first case, the main task of local ventilation is the localization and subsequent removal of harmful and toxic substances and emissions, directly at the place of their occurrence. In practice, the source of pollution is covered from all sides by the so-called. shields, forming a kind of cap. Inside such a shelter, a vacuum occurs during the suction of air masses because the pressure inside is below atmospheric. This measure prevents the entry of harmful impurities into the room. The local ventilation system of the workshop is quite effective in purifying the air, and its organization is quite budgetary.

In cases where local ventilation cannot localize pollution sources in full, the general exchange type of ventilation is used. Its purpose is to comprehensively purify the air in all industrial premises (or a significant part of them), by diluting the concentration of harmful impurities, dust and dirt, thermal radiation, etc.

General exchange ventilation copes well with heat absorption and is mainly used in cases where there is no emission of harmful impurities into the atmosphere of industrial premises. If the specifics of production involve the release of gases, harmful vapors, carcinogens and dust, mixed ventilation is used: general exchange + local suction.

In some cases, enterprises whose production is associated with significant dust emission or the release of toxic impurities completely abandon general ventilation. This is explained by the fact that a powerful general exchange system can simply spread these hazards and dust throughout the workshop.

The key concept of building ventilation systems is to remove the maximum amount of harmful substances with the help of local suction (and this is the main basis on which industrial exhaust ventilation is built), and dilute the remaining impurities with fresh air, reducing their concentration to the maximum permissible level.

Classification of ventilation of industrial workshops according to the mode of action:

• forced ventilation of the workshop;
• exhaust ventilation of the workshop;
• supply and exhaust ventilation of the workshop.
  

Supply ventilation in the workshop Exhaust ventilation in the workshop

The supply ventilation system of the workshop is aimed at ensuring a free flow of fresh air in volumes that will be sufficient for the full functioning of the production. In supply-type systems, duct fans are mainly used, which take in air from the outside and then pass it through the heaters, where heating and humidification (if required) take place.

Such systems are able to fully ensure the forced flow of air masses into the workshop. At the same time, the air pressure increases in comparison with atmospheric pressure, which contributes to the natural (unorganized) extrusion of exhaust air into the street through slots, exits or holes.

Local supply ventilation can be of several types and include equipment such as:

• air shower (clean air flow directed to the workplace: stationary and mobile)
• air and air-thermal curtains (with and without heating)
• oases (serve entire sections of the workshop, where air moves at a calculated speed and temperature)

The exhaust system removes polluted/humid/hot/toxic air, and its replacement with clean air occurs in an unorganized way - through window and door openings, etc. Such ventilation of the workshop is very relevant in technological processes that involve a large release of heat, moisture, harmful with a significant staff involved in the production of employees.

All types of exhaust ventilation units of production workshops consist of several components:

• suction (open type - consisting of a protective cover, exhaust hood, hinged telescopic / side suction, air inlets; or closed type - which include fume hoods (for industries with increased emission of toxic gases and toxic fumes), chambers, shelter boxes (for work with especially toxic and radioactive substances), cabins)
• fan (centrifugal or axial);
• exhaust channel;
• filter;
• duct

Supply and exhaust ventilation of the workshop removes dirty air while simultaneously supplying fresh air masses. Thread allocation can happen in 2 ways:

• by stirring;
• by displacement.

For the first option, high-speed diffusers are installed in the ceiling or wall space, through which outdoor air is forced into the room. Inside, it naturally mixes with waste and is removed through a diffuse valve.

In the second option, air distributors are installed at the floor level, through which a forced influx of fresh air occurs. Cool air is distributed at the bottom of the room, while warm air rises and is naturally forced out through the ventilation grilles.

Features of calculations and ventilation devices in workshops for various purposes

Designing the ventilation of a workshop is a complex engineering task, which requires careful calculations, which largely depend on its purpose.Industrial ventilation must remove all hazards, including hot air, explosive impurities and toxic emissions, water vapor - everything that is released during the production process by products, equipment and personnel.

The calculation of the ventilation system of the workshop is carried out separately for each type of pollution:

For excess heat:

Q \u003d Q u + (3.6V - cQu * (Tz - Tp) / c * (T 1 - T p), where

Q u(m 3) - the volume that is removed by local suction,

V(Watts) - the amount of heat that products or equipment emit,

With(kJ) - heat capacity indicator = 1.2 kJ (reference data),

Tz(°C) - t of polluted air discharged from the workplace,

T p(°C) - t supply air masses,

T 1- t of air removed by general-exchange ventilation.

For explosive or toxic production:

With such calculations, the key task is to dilute toxic emissions and fumes to the maximum permissible level.

Q = Qu + (M - Qu(Km - Kp)/(Ku - Kp), where

M(mg * hour) - the mass of toxic substances released in one hour,

Km(mg / m 3) - the content of toxic substances in the air, removed by local systems,

K r(mg / m 3) - the number of toxic substances in the supply air masses,

K u(mg / m 3) - the content of toxic substances in the air, removed by general exchange systems.

Excess moisture:

Q \u003d Q u + (W - 1.2 (O m -O p) / (O1-Op)), where

W(mg * hour) - the amount of moisture that enters the workshop premises in 1 hour,

O m (gram * kg) - the volume of steam removed by local systems,

About r(gram * kg) - indicator of supply air humidity.,

About 1(gram * kg) - the amount of steam removed by the general exchange system.

From staff releases:

Q=N*m, where

N- number of employees,

m- air consumption based on 1 person * hour (according to SNiP it is 30 m 3 per person in a ventilated room, 60 m 3 - in an unventilated room).

Calculation of the exhaust ventilation of the workshop

The amount of exhaust air can be determined using the following formula:

L=3600*V*S, where

L (m 3)- air flow,

V- air flow rate in the exhaust device,

S- the area of ​​​​the opening of the exhaust type installation.

Features of ventilation of shops of various directions

Machine shop ventilation

Hazards: thermal emissions from electric motors, personnel, vapors of aerosols and coolants, oils, emulsions, dust - emery and mechanical.

Local suction: over grinding/grinding machines, machines without cooling, emulsion tanks, baths for washing parts.

General exchange: air flow from above; calculation of air by excess moisture and heat - at least 30 m 3 per 1 person.

Hazards: heat from presses, solvent vapors, glue, woodworking waste - dust, shavings, sawdust

Heating: air, combined with a ventilation system

Local suctions: floor and underground for wood waste, suction from machine tools; air purification occurs in bag filters, cyclones

General exchange: dispersed air inflow to the upper zone, through perforated type air ducts (mainly)

Hazards: evaporation of alkalis, acids, electrolytes, excess heat and moisture, dust, hydrogen cyanide

Heating: air, combined with a ventilation system

Local suctions: onboard for baths, independent exhaust systems above baths with cyanide and acid solutions, explosion-proof fans, mandatory equipment of suctions for acid baths of various types with backup fans. Mandatory filtration of exhausted air masses

General exchange: air ducts made of anti-corrosion materials or mandatory anti-corrosion coating of all air ducts; supply of 5% of the inflow to all adjacent premises; 3-fold air exchange in the compartments for the preparation of solutions and cyanide salts. Mandatory filtration of the extracted air masses.

Hazards: fluorine compounds, oxides of nitrogen, carbon, ozone

Heating: air, combined with a ventilation system

Local suctions: desirable (if possible)

General exchange: extract: 2/3 from the lower zone, 1/3 from the upper zone. Calculation of air for dilution of harmful emissions from welding to the maximum permissible level.

The calculation is based on the weight of the welding electrodes, which are consumed in 1 hour: for manual welding - 1500-4500 m 3 * h per 1 kg. electrodes, 1700-2000 m 3 * h for semi-automatic carbon dioxide, 2500-5400 m 3 * h - for welding using flux-cored wire.

Painting shop ventilation

Hazards : solvent/thinner fumes, paint particles

Heating: central or air, which is combined with ventilation

Local suction: at degreasing units, painting booths, jet dousing plants, drying booths, tables, stands, dipping baths.

General exchange: inflow to compensate for local exhaust + 1 fold, general exchange exhaust ventilation at least 1 fold from the upper zone.

Ventilation in foundries

The main task of ventilation of the foundry is to cope with the huge amount of heat that is released into the production rooms.

Hazards: radiant heat, a huge amount of heat, ammonia, sulfur dioxide, carbon monoxide

Heating: together with the ventilation system

Local suction : for almost all types of hot shop equipment

General exchange exhaust with mechanical stimulation in the upper area of ​​the workshop + aeration + dusting of workplaces + general exchange supply ventilation.

The creation and design of ventilation in production workshops for any purpose is entrusted exclusively to professionals who will ensure compliance with all necessary standards and perform calculations, taking into account the characteristics of your production.

With regard to industry, ventilation of industrial premises is a set of measures, equipment and organization of its maintenance, pursuing the goal of maintaining stable air exchange and moving air flows in the premises.

Ventilation systems are installed to maintain standard meteorological parameters in rooms of different functionality. The types of ventilation of industrial premises can be classified according to the following criteria:

• The way of organizing air exchange is natural and forced (mechanical) ventilation.
• Purpose: supply or exhaust ventilation.
• Service area: general exchange or local system.
• Structurally: channel or channelless ventilation system.

Types of industrial ventilation

Such natural ventilation of industrial premises is based on the natural draft of air, the appearance of which is influenced by the following factors:

• The difference between outdoor air temperature and indoor temperature (aeration).
• The difference in atmospheric pressure between the lower level in the room and the hood, which is mounted on the roof.
• Wind speed and pressure.

The organization of the work of natural ventilation of the premises will not require significant injections into the equipment. Installation of natural ventilation is the simplest of existing systems and does not require an electrical supply. Disadvantages - dependence on temperature, pressure, wind direction and speed. The exact calculation of the natural ventilation of industrial premises is carried out according to the formulas:

Air flow exchange options

The current ventilation standards for industrial premises are reflected in SNiP 41-01-2003 dated 06/26/2003. According to these regulations, general ventilation must ensure the exchange of air throughout the room. Properly installed general ventilation of industrial premises removes waste masses throughout the entire volume of the premises, and the supply equipment supplies clean air back.

• Supply exchange of air masses

Assimilation of excess moisture, heat and dilution of harmful emissions and impurities are the tasks of supply general ventilation. All this allows you to comply with sanitary and hygienic norms and standards for a comfortable stay at the work site.

If the room is cold, then the supply general ventilation also solves the problems of mechanical stimulation, purification and heating of the supply air masses.

• Hood of general exchange type

The simplest device for organizing a general exhaust ventilation system is a fan with an air vent through windows or into an exhaust duct. If the air duct is longer than 30-40 m and the pressure drops more than 30-40 kg/m2, the axial fan should be replaced with a central one. General exchange ventilation systems of industrial premises often work in tandem with other ventilation systems (more often it is natural or mechanical ventilation), since due to the heterogeneity of harmful impurities and different conditions for their formation, the use of any one system is ineffective.

• Air ducts for ventilation of premises

The use of ventilation systems in some cases implies the presence of a network of air ducts, that is, channel systems, for the effective movement of air. In the absence of ventilation ducts, such a system is called channelless. For example, the fan is installed in the ceiling or in the wall, in the presence of a natural ventilation system, etc. Any ventilation system has 4 main properties: functionality, volume of serviced areas, method of moving air masses and design.

The main purpose of exhaust ventilation is to remove exhaust air from the serviced premises. Exhaust ventilation, as a rule, works in conjunction with supply air, which, in turn, is responsible for supplying clean air.

In order for the room to have a favorable and healthy microclimate, it is necessary to draw up a competent design of the air exchange system, perform the appropriate calculation and install the necessary units in accordance with all the rules. When planning, you need to remember that the condition of the entire building and the health of the people who are in it depend on it.

The slightest mistakes lead to the fact that ventilation ceases to cope with its function as it should, fungus appears in the rooms, decoration and building materials are destroyed, and people start to get sick. Therefore, the importance of the correct calculation of ventilation cannot be underestimated in any case.

The main parameters of exhaust ventilation

Depending on what functions the ventilation system performs, existing installations are usually divided into:

1. Exhaust. Required for the intake of exhaust air and its removal from the room.
2. Supply. Provide supply of fresh clean air from the street.
3. Supply and exhaust. At the same time, old stale air is removed and new air is introduced into the room.

Exhaust units are mainly used in production, offices, warehouses and other similar premises. The disadvantage of exhaust ventilation is that without the simultaneous installation of a supply system, it will work very poorly.

If more air is drawn out of the room than it enters, drafts are formed. Therefore, the supply and exhaust system is the most efficient. It provides the most comfortable conditions both in residential premises and in industrial and working type premises.

Modern systems are equipped with various additional devices that purify the air, heat or cool it, humidify it and distribute it evenly throughout the premises. The old air is expelled through the hood without any difficulty.

Before proceeding with the arrangement of the ventilation system, you need to seriously approach the process of its calculation. Direct calculation of ventilation is aimed at determining the main parameters of the main components of the system. Only by determining the most suitable characteristics, you can make such ventilation that will fully fulfill all the tasks assigned to it.

During the calculation of ventilation, parameters such as:

1. Consumption.
2. Operating pressure.
3. Heater power.
4. Cross-sectional area of ​​air ducts.

If desired, you can additionally calculate the energy consumption for the operation and maintenance of the system.

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Step-by-step instructions for determining system performance

The calculation of ventilation begins with the determination of its main parameter - performance. The dimensional unit of ventilation performance is m³/h. In order for the air flow calculation to be carried out correctly, you need to know the following information:

1. The height of the premises and their area.
2. The main purpose of each room.
3. The average number of people who will be in the room at the same time.

To make the calculation, you will need the following devices:

1. Roulette for measurements.
2. Paper and pencil for notes.
3. Calculator for calculations.

To perform the calculation, you need to know such a parameter as the frequency of air exchange per unit of time. This value is set by SNiP in accordance with the type of premises. For residential, industrial and administrative premises, the parameter will vary. You also need to take into account such points as the number of heaters and their power, the average number of people.

For domestic premises, the air exchange rate used in the calculation process is 1. When calculating ventilation for administrative premises, use the air exchange value equal to 2-3, depending on specific conditions. Directly, the frequency of air exchange indicates that, for example, in a domestic room, the air will be completely updated 1 time in 1 hour, which is more than enough in most cases.

Performance calculation requires the availability of data such as the amount of air exchange by frequency and number of people. It will be necessary to take the largest value and, starting from it, select the appropriate exhaust ventilation power. The calculation of the air exchange rate is performed using a simple formula. It is enough to multiply the area of ​​\u200b\u200bthe room by the height of the ceiling and the multiplicity value (1 for household, 2 for administrative, etc.).

To calculate the air exchange by the number of people, the amount of air consumed by 1 person is multiplied by the number of people in the room. As for the volume of air consumed, on average, with minimal physical activity, 1 person consumes 20 m³ / h, with medium activity this figure rises to 40 m³ / h, and with high activity it is already 60 m³ / h.

To make it clearer, we can give an example of a calculation for an ordinary bedroom with an area of ​​​​14 m². There are 2 people in the bedroom. The ceiling has a height of 2.5 m. Quite standard conditions for a simple city apartment. In the first case, the calculation will show that the air exchange is 14x2.5x1=35 m³/h. When performing the calculation according to the second scheme, you will see that it is already equal to 2x20 = 40 m³ / h. It is necessary, as already noted, to take a larger value. Therefore, specifically in this example, the calculation will be performed by the number of people.

The same formulas are used to calculate the oxygen consumption for all other rooms. In the end, it remains to add up all the values, get the overall performance and select ventilation equipment based on these data.

The standard values ​​for the performance of ventilation systems are:

1. From 100 to 500 m³/h for ordinary residential apartments.
2. From 1000 to 2000 m³/h for private houses.
3. From 1000 to 10000 m³/h for industrial premises.

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Determination of heater power

In order for the calculation of the ventilation system to be carried out in accordance with all the rules, it is necessary to take into account the power of the air heater. This is done if, in combination with exhaust ventilation, supply ventilation is organized. A heater is installed so that the air coming from the street is heated and enters the room already warm. Essential in cold weather.

Calculation of the capacity of the air heater is determined taking into account such values ​​as the air flow, the required outlet temperature and the minimum temperature of the incoming air. The last 2 values ​​are approved in SNiP. In accordance with this regulatory document, the air temperature at the outlet of the air heater must be at least 18 °. The minimum outside air temperature should be specified in accordance with the region of residence.

Modern ventilation systems include performance regulators. Such devices are designed specifically so that you can reduce the rate of air circulation. In cold weather, this will reduce the amount of energy consumed by the air heater.

To determine the temperature at which the device can heat the air, a simple formula is used. According to her, you need to take the value of the power of the unit, divide it by the air flow, and then multiply the resulting value by 2.98.

For example, if the air flow at the facility is 200 m³ / h, and the heater has a power of 3 kW, then by substituting these values ​​​​in the above formula, you will get that the device will heat the air by a maximum of 44 °. That is, if in winter it will be -20 ° outside, then the selected air heater will be able to heat oxygen up to 44-20 = 24 °.

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Operating pressure and duct cross section

Calculation of ventilation involves the mandatory determination of parameters such as operating pressure and cross-section of air ducts. An efficient and complete system includes air distributors, air ducts and fittings. When determining the working pressure, the following indicators must be taken into account:

1. The shape of the ventilation pipes and their cross section.
2. Fan settings.
3. The number of transitions.

The calculation of a suitable diameter can be performed using the following ratios:

1. For a residential building, a pipe with a cross-sectional area of ​​​​5.4 cm² will be enough for 1 m of space.
2. For private garages - a pipe with a cross section of 17.6 cm² per 1 m² of area.

Such a parameter as the speed of the air flow is directly related to the cross section of the pipe: in most cases, the speed is selected in the range of 2.4-4.2 m / s.

Thus, when calculating ventilation, whether it is an exhaust, supply or supply and exhaust system, a number of important parameters must be taken into account. The efficiency of the entire system depends on the correctness of this stage, so be careful and patient. If desired, you can additionally determine the power consumption for the operation of the system being arranged.

Industrial ventilation is a set of measures aimed at organizing and maintaining stable air exchange in industrial premises. Operating equipment and production processes are often a source of airborne particles and toxic fumes, which can adversely affect human health. In addition, the lack of fresh air reduces productivity and the ability to endure physical activity.

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Solution

Ventilation of industrial facilities is essentially the supply of fresh air and the removal of exhaust air. And it includes a number of solutions.

The first stage is planning. And for this it is necessary to take into account several important conditions: the presence of harmful fumes in the premises, gas contamination and temperature conditions.

To solve the tasks set, it is necessary to take into account the necessary working conditions, as well as build on the parameters of the premises and its technical characteristics.

Most often, in large rooms, supply and exhaust ventilation with air cooling or heating is used.

Currently, there are many ventilation systems that differ in functionality and cost. Often this is a specific solution for each individual room. It is thanks to this that we get an efficient, economical, and ideally coping with the tasks set. It should be understood that the ventilation system is a very complex mechanism that not only provides clean and fresh air in the room, and therefore high performance not only of equipment, but also of employees, as well as their well-being, and also allows you to control many parameters to create optimal climatic conditions depending on the time or part of the room. The ventilation system can be controlled mechanically or electronically, but mixed types are also possible.

The task of industrial ventilation

The main task of industrial ventilation is to ensure the constant presence of clean air in the premises (without impurities, odor and harmful components). This is ensured in 2 ways: by removing polluted air masses from the workshops and by providing an influx of fresh air. The second task is to maintain a certain microclimate. This includes temperature and humidity requirements. These requirements are especially relevant for industries accompanied by a large release of heat, moisture and harmful fumes.

A professionally designed ventilation system contributes to the following benefits:

• staff get sick less
• labor productivity increases
• a favorable microclimate is maintained
• moisture does not accumulate on the equipment, the metal does not oxidize or corrode
• compliance with the requirements for production processes.

Exhaust aeration in production

Air ducts are mainly used for ventilation of local spaces inaccessible to infiltration flows. The movement and distribution of air occurs without external coercion, only under the influence of temperature differences and atmospheric pressure outside and inside the room. To increase the efficiency of aeration, deflectors are installed at the outlet, special expansion nozzles that draw the exhaust air out of the room. This is also facilitated by window transoms and ajar skylights.

In the summer, the role of supply air channels is performed by open gates, openings in the outer walls and doors. In the cold season, in warehouses up to 6 meters high, only openings are opened at a height of at least 3 meters from the zero mark. With a height of more than 6 meters, the bottom of the ventilation openings is designed at a distance of 4 meters from the floor level. All openings are equipped with water-repellent visors, which, moreover, deflect the supply air jets upwards.

Supply and exhaust aeration

Extraction of polluted air occurs due to transoms and ventilation shafts. Transoms act as a kind of thermal damper, the opening and closing of which regulates the air pressure in the ventilation streams. As an additional pressure regulator, special holes are designed, equipped with louvered doors:

• slightly above floor level - stimulating air flow,
• just below the ceiling level - optimizing its outflow.

The volume of circulating air is proportional to the area of ​​open transoms, openings and vents.

Note

1. If the concentration of harmful substances in the outdoor air exceeds the maximum allowable limits by 30%, natural ventilation is not used.
2. The elements of the upper hood are installed approximately 10-15 degrees below the ridge on the roof. This reduces the risk of their destruction.

Design and installation

To ensure the highest quality ventilation, it is necessary to carry out its design and installation already at the construction stage. This is the only way to take into account all safety measures, to properly design exhaust zones.

But it also happens that it is necessary to install a ventilation system in an already built building. In this case, all the conditions in which the system will be operated, as well as the purpose of the room itself, should be taken into account. The choice of equipment always depends on the explosion and fire hazard of the room.

As is known, general exchange and local ventilation is used for industrial premises. The first is responsible for air exchange and air purification of the entire room. But with the help of local suctions, it is possible to solve only local problems at the place of formation of those very harmful substances. But it is not possible to keep and neutralize such air flows completely, preventing their spread throughout the room. Here additional elements are needed, such as umbrellas.

The choice of equipment for the installation of ventilation of industrial premises is influenced by the type of production and the amount of harmful substances emitted, the parameters of the premises itself, and the design temperature for the cold and warm seasons.

Summing up, I would like to say that such a difficult task as the calculation, design and subsequent installation of ventilation should be performed by qualified specialists who have a wealth of knowledge and years of experience behind them.

Classification of industrial ventilation by type of action

There are different types industrial ventilation. They are classified according to the following parameters:

• the method of organizing the inflow and outflow of air masses (natural, forced);
• by functionality (supply, exhaust, supply and exhaust);
• method of organization (local, general exchange);
• design features (channelless, channel).

The simplest and most cost-effective is natural ventilation. It is based on the laws of physics, when the warmer layers of air, rising up, displace the cold ones. The main disadvantage of such systems is the dependence of the season, weather conditions and a limited scope (suitable for a limited range of industries). To organize natural ventilation in production shops, 3 levels of adjustable openings (windows) are arranged. The first 2 are arranged at a height of 1-4 m from the floor, the 3rd level is under a stream or in a light-aeration lamp. Fresh air enters through the lower openings, and dirty air is forced out through the upper ones. The intensity of air exchange is regulated by opening/closing the vents. Natural ventilation can only be used for one-story buildings.

Forced ventilation- a more efficient system, including a set of equipment and engineering networks. However, you have to pay for efficiency, as it is associated with the purchase of expensive equipment and the consumption of a large amount of electricity.

Only supply or only exhaust ventilation is used extremely rarely (mainly in industries where air pollution is low). Much more common supply and exhaust systems providing more uniform air exchange.

General ventilation organized in large industries. Depending on production processes and air composition, it can be used in combination with other systems. local ventilation, unlike the general exchange, monitors the purity of the air in certain areas - for example, above the welding or painting area. This type is selected if the general exchange cannot cope with ventilation in all rooms.

What gives a combination of local exhaust and supply general exchange systems? Taking in polluted air, the exhaust system does not allow it to spread throughout the room, and the supply system provides an influx of fresh air (it can be equipped with filters and a heating system).

duct ventilation involves the organization of boxes or pipes of large cross-section, designed to transport air. Channelless systems - a set of fans and air conditioners built into the openings of walls or ceilings.

Design of ventilation of production shops

Design industrial ventilation systems has its own specifics. There is no universal equipment that can meet the needs of all types of industries. When designing, a lot of data is taken into account. The algorithm for solving the problem is as follows:

1. Calculation of the required air exchange.
2. Selection of equipment that supports the calculated parameters.
3. Calculation of air ducts.

At the first stage of design, a technical task (TOR) is developed. It is compiled by the customer and includes requirements for air parameters, features of technological processes, and system tasks.

• architectural plan of the object with reference to the area;
• construction drawings of the building, including a general view and sections;
• the number of employees in one shift;
• facility operation mode (one-shift, two-shift, round-the-clock);
• features of technological processes;
• potentially dangerous zones with reference to the plan;
• required air parameters (temperature, humidity) in winter and summer.

The calculation of the required air exchange is carried out in the following areas:

• supply of fresh air according to sanitary standards (according to the norms per person 20-60 m³ / h);
• heat assimilation;
• moisture assimilation;
• dilution of air to the maximum permissible concentrations of harmful substances.

The largest air exchange obtained as a result of the calculations described above is taken as the basis.

Using the emergency ventilation system

According to SNiP ("Ventilation of special and industrial buildings") in hazardous industries, it is necessary to provide emergency ventilation system. An emergency situation may arise in the event of an emergency release of explosive or toxic gases, a fire. It is a completely independent exhaust type installation and is calculated in such a way that when working with a conventional system, 8 air changes are provided in 1 hour.

Ventilation systems management

Automation control of ventilation systems allows you to optimize the process and reduce operating costs. This approach allows minimizing human participation in management and reducing the risk of the "human factor". Automatic control involves the installation of sensors that record the temperature / humidity of the air, the concentration of harmful substances, the degree of smoke or gas contamination. All sensors are connected to the control unit, which, thanks to the specified settings, turns the equipment on or off. Thus, automation helps to comply with the requirements of sanitary standards, quickly respond to emergencies and save significant money.

Ventilation systems are one of the main consumers of electrical and thermal energy, so the introduction of energy saving measures allows to reduce the cost of products. The most effective measures include the use air recovery systems, air recirculation and electric / motors with no "dead zones".

The principle of recuperation is based on the transfer of heat from the displaced air to a heat exchanger, which reduces heating costs. The most widespread recuperators are plate and rotary type, as well as installations with an intermediate coolant. The efficiency of this equipment reaches 60-85%.

The principle of recirculation is based on the reuse of air after it has been filtered. At the same time, part of the air from the outside is mixed in with it. This technology is used during the cold season in order to save heating costs. It is not used in hazardous industries, in the air environment of which there may be harmful substances of hazard classes 1, 2 and 3, pathogens, unpleasant odors, and where there is a high probability of emergency situations associated with a sharp increase in the concentration of flammable and explosive substances in the air. .

Given that most electric motors have a so-called "dead zone", their correct selection allows you to save energy. As a rule, "dead zones" appear during start-up, when the fan is running in idle mode, or when the mains resistance is much less than what is required for its correct operation. In order to avoid this phenomenon, motors with the possibility of smooth speed control and with no starting currents are used, which saves energy at start-up and during operation.

Optimal air parameters for some industrial premises according to the conditions of work or storage of materials