A smoke exhauster for a boiler is equipment necessary for the efficient operation of a heating system, which is otherwise called "traction fans". In engineering networks of an industrial type, large-sized units of a similar action are mounted on thermal power plants: blast and traction units, which ensure the stability of the fuel combustion process.
Appointment of a smoke exhauster
The smoke exhauster for a solid propellant copper - the device of household and industrial function. It provides constant thrust and allows you to control the process of fuel combustion. Installation of a smoke exhauster for a furnace is necessary for several reasons:
- due to high-quality traction, smoke from the furnace does not penetrate into the boiler room through cracks, as well as when opening the door;
- the possibility of installing a heating system in the absence of traction;
- implementation of control over the amount of fuel burned and the intensity of combustion of fuel through traction control.
There is such a variety of equipment as smoke exhausters, dust collectors and firefighters. The former perform the function of cleaning the outgoing flue gases. The latter provide air purification from combustion products during fires and have the function of supplying fresh air (not all models). 
There are devices for removal of aerosols, fine powder suspensions, gases. The most powerful units are able to provide air purification within a few seconds. Such machines are equipped with a filter system that absorbs combustion products and other substances that enter them. Fire smoke exhausters can be small-sized and large-sized (trailed).
Types of smoke exhausters
There are several types of smoke exhausters, each of which has its own marking.
The marking of smoke exhausters consists not only of letters, there are also digital ones. The second indicates the diameter of the wheel of the apparatus or fan. There are three options for the design of smoke exhausters:
A smoke exhauster for a fireplace is a small-sized apparatus with a one-way draft, which is placed in a chimney pipe. In the places of installation of the device, all gaps are filled with heat-resistant sealant. To ensure efficient removal of smoke into the atmosphere and a stable flow of air into the fireplace or stove, equipment such as a centrifugal smoke exhauster is recommended.
Popular models of smoke exhausters for boilers:
Device
The smoke exhauster is a simple device in a constructive sense. It consists of several nodes, each of which has its own purpose.
The housing is made in the form of a "snail", which provides the required swirling of the air entering the unit. Made of heat-resistant steel, covered with thermal insulation.
The guide vane of the smoke exhauster is located on the suction pipe, it allows you to control the air pressure using a rotary mechanism that combines the fan blades. Each blade is curved to allow the air flow to rotate in the same direction as the rotor. With the help of a rotary mechanism, it is possible to block the lumen of the branch pipe to one degree or another.
The impeller of the smoke exhauster is the assembly on which the fan blades are located. They are attached to it by welding or rivets. In the central part of the wheel, when it rotates, a rarefied atmosphere is created. For this reason, the incoming air is drawn in here. Small-sized devices such as smoke exhausters for fireplaces work in a similar way.
The wheel coupling can be located on the motor shaft or on the countershaft, depending on the design of the unit. If this is a dust-collecting equipment, special filters with absorbents are included in the device. Thus, all fire-fighting units are equipped. Ash collectors can be included in the design of apparatus for boiler rooms. The device of the smoke exhauster determines its purpose.
The impeller can be provided with holes necessary for fixing the blades in a predetermined position. Balancing can be carried out manually or by an electric actuator. You can distinguish the direction of rotation of the fan blades if you look at the unit from the side of its electric motor. The axial guide apparatus of the smoke exhauster ensures the rotation of the blades, regardless of their number and direction of inclination, at an angle from 0 to 90 °.
A blower fan and a smoke exhauster have a similar design, but differ in purpose. Devices of the first type provide air injection into the boiler furnace. The second ones are designed to remove the products of fuel combustion and discharge them into the atmosphere outside the boiler room. 
Fans and smoke exhausters of boiler installations have the same principle of operation, they can be left- and right-handed, with direct and reverse draft. These machines are designed for long-term trouble-free operation in the temperature range from 0 °C to +250 °C. Smoke exhausters are marked as "D" and "DN", fans - as "VDN". The latter are produced with the landing of the impeller on the motor shaft.
Repair of smoke exhausters and fans is carried out by persons who have passed the appropriate certification and instructions on safety precautions for the operation of electrical appliances.
Advantages of furnaces with forced draft fans
The design of a modern draft fan for wood-burning and other types of boilers may include ash collectors. This equipment is of several types:
The latter are the most effective. The work of cyclones is based on the action of centrifugal forces. The products of fuel combustion are removed by the action of thrust in such a way that they are swirled with the precipitation of large particles into a special bunker. The scheme of cyclones may be different, but the principle of operation remains the same.
Smoke exhausters for domestic solid fuel boilers provide a stable air supply to the furnace. Therefore, heating equipment can operate smoothly even under adverse conditions for fuel combustion. This may be the increased moisture content of the lumber or the lack of sufficient oxygen to support combustion processes.
To ensure control over the operation of the boiler, a draft regulator is installed. This device may not be included with the unit and will need to be purchased separately. The thermostat for the boiler is of three types:
The design of any of them includes control and adjustment units, temperature-sensitive elements. The regulator works by reading the physical characteristics of the sensor (thermal sensing element). They (physical properties) change when heated, which detects the control unit and transmits a signal to the node that is included in the design, depending on its type:
- electromagnetic relay;
- electronic device;
- mechanical valve.
Smoke exhausters for boilers, equipped with thermostats, are more convenient to use devices. They allow you to automate the process of monitoring the combustion of fuel in the furnace. A machine without a temperature sensor can always be equipped with one by purchasing and installing additional equipment.
Fan - a device driven by an engine to create a flow of air or other gases. Fans are used in air conditioning, ventilation, heating, pneumatic transport systems, they organize the movement of air flows in boilers, cool the radiators of internal combustion engines, create traction in vacuum cleaners, cooling and drying systems.
Fans create a relatively low overpressure (vacuum), usually not exceeding 12 kPa. To create higher pressures, blowers and compressors are used instead of fans.
There are two most common types of fans:
a) centrifugal (radial);
b) axial.
There are also diametrical fans, diagonal fans, but to date they have not received wide distribution in industrial ventilation systems, therefore we will not consider them yet.
Centrifugal (or radial) fan has an impeller located in a spiral housing, during the rotation of which the gas entering through the inlet enters the channels between the blades, under the action of the emerging centrifugal force it moves into the spiral casing and is directed to the outlet. In this case, the direction of the gas flow changes by 90 0 .
Blades of centrifugal fans can be of three types: radial (straight), bent forward and bent back; Accordingly, the technical characteristics of the fans and, as a result, their purpose also differ.
Fans with radial blades are often used to move dusty gas-air media.
Fans with backward curved blades can operate at higher speeds.
Fans with forward curved blades provide greater (compared to other types) performance and pressure.
It is generally accepted that fans are divided according to several indicators:
By the magnitude of the total pressure created during the movement of air:
Low pressure fans (up to 1 kPa);
Medium pressure fans (up to 3 kPa);
High pressure fans (up to 12 kPa).
Depending on the composition of the transported medium and conditions:
Ordinary - for air (gases) with temperatures up to 80 ° C;
Corrosion-resistant - for aggressive environments;
Heat-resistant - for air with a temperature of 80-200 ° C;
Explosion-proof and spark-proof - for explosive environments;
Dust - for dusty air (solid impurities in the amount of more than 100 mg / m³).
Place of installation:
Conventional, mounted on a special support (frame, foundation, etc.);
Duct, installed directly in the duct;
Roof, placed on the roof.
Such a division is very conditional. For example, a low-pressure fan VTs 4-75 can create a total pressure of more than 2 kPa, and VTs 14-46 (medium pressure) does not always reach the same 2 kPa. And on the roof, you can install not only roof fans, but also any others, as long as the roof is strong enough. And dust fans work great with clean air.
Here design fans are strictly regulated. According to GOST 5976-90, centrifugal fans (except in-line fans) can be produced in 7 versions.
Most common (in descending order):
- version 1(the impeller is mounted directly on the motor shaft). The advantages are obvious: a minimum of parts, a minimum of assembly work, a minimum of acquisition costs, compactness. There are also disadvantages. The impellers of fans of large numbers (8 and above) have a sufficiently large mass and all this mass acts on the motor bearings. To do engine maintenance and get to its bearings, you need to completely disassemble (and then reassemble) the fan. This is not always easy to do in the workplace.
- version 5(the impeller is cantilevered on the propeller shaft, driven by a V-belt drive). Widely used to drive dust fans, high pressure fans, and large number fans (8 and above). Advantages: electric motor bearings perceive a smaller radial load, the ability to ensure the operation of the engine in the nominal mode by selecting the diameters of the pulleys. Disadvantages: increased dimensions and weight, increased labor intensity of maintenance and price.
- version 3(the impeller is cantilevered on the shaft of the propeller, coupling gear). It is mainly used to drive fans operating in specific conditions (elevated temperatures, aggressive environment, etc.). Advantages: radial loads are not transferred to the motor, it is possible to protect the bearings of the propeller from the influence of the medium being moved (temperature, humidity, aggressiveness). The disadvantages are approximately the same as in version 5, although there are fewer nodes (there is no tensioner, belts, the fence is simpler).
The same GOST 5976-90 and GOST 22270-76 establish direction of rotation and volute angle fan. 
By definition, fans can be right rotation(the wheel rotates clockwise when viewed from the suction side) and left rotation(the wheel rotates counterclockwise when viewed from the suction side).
It would seem that everything is clear and clearly defined. But no! There is a variety of fans for which both the direction of rotation and the angle of rotation are determined in a completely different way. These are forced-draught machines (smoke exhausters and blowers) that work mainly in boiler houses. For them, the direction of rotation is determined from the drive side, and the turning angle is 0 0 - the exhaust is directed towards the bottom. Why and who needed it is the question.
A few words about axial fans.
Axial fan has an impeller located in a cylindrical housing, consisting of a hub with blades fixed on it. When the wheel rotates, air (gas) moves along the axis of rotation.
Axial fans can have different designs of the impeller and casing (housing), and also differ in the shape and number of blades. In some cases (for example, a conventional room fan) there is no casing. The cross section of the blades can be profiled (volumetric), but in most cases the blades are flat or curved plates. make blades plastic, aluminum or steel.
Axial fans are structurally simpler than centrifugal fans, have higher efficiency, high performance, but do not provide high pressures.
By appointment Axial fans are divided into general purpose fans and special ones.
General Purpose Fans are designed to move clean or slightly dusty air, the temperature of which should not exceed 40 0 С. 40 0 C. The choice of general-purpose axial fans is small - the most widely used are fans of types B 06-300 and B 2.3-130, as well as their later modifications.
To special axial fans include fans used to move explosive and aggressive gas-air environments, mine fans and tunnel ventilation fans, ceiling fans, bird fans, cooling tower fans, fans built into process equipment, etc.
HOW TO ORDER A FAN?
In the ideal In this case, when ordering, you must specify the type of fan, its number, which electric motor to equip it with, the direction of rotation and the angle of rotation of the housing. And if everything is more or less clear with the last two questions, then the rest need to be dealt with a little.
First (as the simplest),fan number . The number specifies the diameter of the impeller in decimetres. That is, for a VC 4-75-3.15 fan, the impeller diameter is 315 mm, and for a DN-11.2 smoke exhauster - 1120 mm.
Fan type. If you need a fan to replace a failed one or you are building a system similar to the existing one, rewrite the plate on the old fan. If not, measure the impeller (outer diameter, number of blades, diameter and length of the bore in the hub). You can also specify the internal dimensions of the suction and discharge pipes. This is usually sufficient to determine the fan type.
In the case of designing (installation) of a new exhaust, supply or process ventilation system, it is necessary to know the capacity and total pressure that the fan must provide. Performance- this is the volume of air removed (injected) from a ventilated room or workplace. It is usually expressed in m 3 /hour. Full pressure in general, it must compensate for the resistance to air passage in air ducts and network equipment (valves, dampers, air heaters, filters, silencers, etc.). Total pressure unit - Pa.
In the reference literature and on almost all websites (including ours) of enterprises involved in fans, their aerodynamic characteristics.
Aerodynamic characteristics are a set of straight and curved lines. Simple with axes: horizontal axis - fan performance in m 3 /hour, vertical - total pressure in Pa. We find the required operating point (capacity-pressure) on the thick curve (which is the characteristic of the fan), then we determine the power of the electric motor, its speed and (rather for ourselves) the efficiency of the fan. The motor parameters (power and speed) are indicated on the nearest thin curves located above the fan characteristic. Fan efficiency - inclined straight lines.
All aerodynamic characteristics of fans are given for standard conditions.
The following are considered standard conditions (GOST 10616-90):
Air temperature - 293 K (20 0 C);
Atmospheric pressure - 101.34 kPa;
Air density - 1.2 kg/m 3 ;
Relative humidity - 50%.
Therefore, if the operating conditions of the fans differ from the standard ones (almost always), this must be taken into account.
It should be said that it is almost impossible to calculate networks and take into account all pressure losses with high accuracy, so it is better to choose fans with a pressure margin of 10-20%.
Abbreviation designation
L 3.5 doors 3*1500 Lv.90 sx.1 is decrypted as follows:
- D- a smoke exhauster (a device that, by its design, is an industrial fan, in the manufacture of which thicker metal is used; the purpose is to work at high temperatures);
- 3,5
- 3.5 DM or 350 millimeters - the size of the impeller, which traditionally affects the size of the entire unit;
- dv. – electric motor;
- 3
- 3 kilowatts, this is exactly the power of the electric motor;
- 1500
- 1500 revolutions (meaning the revolutions of the motor shaft);
- Lv.- left (meaning the turn of the snail);
- 90
– 90 degrees, snail turn;
- sch.1- diagram number 1 (design diagram in which the impeller is located on the same shaft with the engine).
The direction of rotation and the angle of rotation of the body (snail) of smoke exhausters, scheme No. 1, view from the side of the electric motor
Scheme of turns of cases of draft machines type D RIGHT rotation. Scheme of turns of the bodies of draft machines type D LEFT rotation.
The main elements of smoke exhausters, as well as centrifugal fans, are:
1. A snail is a stationary spiral casing made of metal, in which vortex flows are created.
2. Impeller. The second name of this element is “squirrel wheel”. The rotating part of this element consists of two disks: central (in the middle there is a sleeve designed for a rotating shaft), open (air intake blades are attached to it, which are bent at a certain angle).
3. Electric motor. It is the main drive for the installation. Smoke exhausters, depending on the recommended operating conditions, are equipped with different types of motors: asynchronous; two-speed asynchronous, allowing to work together with a guide vane, characterized by economical regulation; single-speed asynchronous type DAZO. In addition, engines can differ in different degrees of explosion hazard, different climatic modifications.
4. Frame - a metal, supporting frame, which may be modified or absent - it all depends on the specific design scheme. There are 6 schemes in total: schemes No. 5, 3 and 1 can be executed on a single pedestal with a vibration base or on a single pedestal without vibration generation. However, these ventilation units can also be installed in a non-standard way - it depends on the location, the project.
Again, depending on the design scheme, machines can be equipped with a “bearing shaft” (sh. 3), “V-belt drive” (sh. 5). At the request of the customer and a suitable size, it is possible to complete with a directing vane HA.
2. Appointment of smoke exhausters
An important installation in almost all areas of the boiler industry are smoke exhausters. The latter occupy the main, main place in the operation of the central heating system.
Equipment of this type is installed on large and small stationary hot water and steam boilers. They are suitable for almost all types of boiler rooms. They can also be used to move dust-smoke-air mixtures in other technological installations.
DN-type draft blowers are designed to move smoke, dust-gas-air mixtures that are not explosive with a dust content of not more than 2 grams per m / cu. In simpler, understandable words, such a device is a powerful fan designed to remove combustion products (smoke, steam, fumes) from combustion chambers with a temperature range from minus 30 to plus 200 degrees or up to plus 400 degrees (if we are talking about is a new, optimized, improved design). For more information about the latter, please call +7 4995023405.
3. Features of smoke exhauster D
DN-type draft blowers are manufactured in two types - right and left rotation, as indicated by the corresponding abbreviations in their abbreviation (Pr. and Lv.). In order to determine the direction of rotation, it is necessary to look at the wheel from the engine side: the left rotation will occur counterclockwise, the right one - clockwise. The angle of turn of the cochlea ranges from 0 to 270 degrees, while the rotation interval is every 15 degrees. The interfering stiffening ribs of the snail, if necessary, are finalized mechanically - they are cut.
Maintenance and inspection of the impellers should be carried out through small special openings - hatches provided in the wall of the volute. In addition, all snail housings have special buttons designed to drain condensate.
In Movez smoke exhausters (created according to scheme 5 or 3), large bearings are installed (on the impeller side), which increases the degree of reliability and durability of the entire product. For such fans, bearing units are made collapsible - this is important for maintainability. In addition, starting from the 9th size (i.e. DN 9, etc. up to DN 22), it is possible to complete with a cooling coil (optional; necessary to prevent possible overheating).
A guide vane is used to regulate the operating modes. The latter, by changing the aerodynamic characteristics, increases the efficiency and reduces the energy loss of the installation.
In order to prevent the ingress of large particles that can damage the working parts of the apparatus, suction pockets are used - they retain all solid fractions.
Fans are an integral part of ventilation, air conditioning and heating systems. They are used both in industrial premises and in residential buildings to ensure better air circulation or its extraction.
An example of a fan used in industrial premises
This device is a device consisting of a propeller and an electric motor that sets them in motion. According to the type of installation, they are divided into indoor and roof-mounted. How to determine in which direction the blades are spinning? How to change the direction of rotation? How to determine the frequency of the produced revolutions? This is what will be discussed further.
Determining the direction of rotation
Determining the direction of movement of the impeller is very simple. Often the direction of rotation is marked with an arrow. The arrow indicates the direction in which the impeller rotates. If for some reason there is no indication of the direction of movement, then determining the correct side will not be difficult without it.
An example of a snail direction indicator
To determine the direction of the blades, it is necessary to look at the structure from the side of the hole through which air is sucked in. If the impeller turns clockwise and the snail body is twisted clockwise, the movement is right. If the turns of the blades go counterclockwise, the side is left.
How to determine the fan speed?
The rotational speed shows its installation performance. In order to calculate the frequency of movement of the impeller, a device called a tachometer is used. For a more accurate determination, it is recommended to use tachometers of accuracy class 0.5 or 1.
Tachometers differ in the place of installation and are divided into:
- stationary;
- remote;
- manual.
Also, tachometers differ in the principle of operation. They are mechanical, magnetic, magnetic-induction and electronic.
Modern electronic tachometer in action
Consider the example shown in the picture. With the help of a laser beam directed at the wheel, the rotational speed (rpm) is measured. All data is displayed on a small display.
How to change the direction of rotation of the propeller?
Sometimes there are situations when you need to change the direction of rotation of the blades. For such purposes, reversible fans are used. Their main difference is that a reversible fan is designed for possible direction changes, while a conventional one is not.
Reversible model
Reversible models are widely used at mine enterprises. They serve both for supplying air and for extracting it.
Reversible axle models used in mines
Changing the direction of movement of axial models is carried out in two main ways:
- No change in direction of turn.
- With change of direction of rotation.
When using the second method without changing the position of the blades, the system does not work at full strength. The wheel works backwards, which reduces efficiency. In order to get 100% performance in reverse, you need to change the position of the blades.
In order to change the direction of rotation of the propeller, it is necessary to disassemble the engine and change the phases:
- On a single-phase motor, we have 4 wires at the output. 2 wires at the beginning of the winding and 2 from the end. To reverse, it is necessary to transfer the phase and zero from the beginning of the winding to the end.
- In the case of a three-phase motor, we have 6 wires at the output. 3 at the beginning of the winding and 3 at its end. To reverse in a three-phase network, we need to swap any two wires at the input.
- To reverse a three-phase electric motor with connection to a single-phase network through a starting capacitor, it is necessary to swap the cable going to the input of the capacitor with a cable that is not connected to it.
In order to change the direction of the propeller stroke of the exhaust hood (kitchen hood), there are two effective methods:
- If an asynchronous electric motor is installed in the design of the hood, the change is made by throwing wires (the method is described above).
- In the case of a phase-shifting capacitor, the change is made by rearranging it. For the correct execution of this method, it is recommended to contact the services of an experienced electrician.
exhaust hood
Summarize. The direction of the wheel travel is determined either by the arrow drawn on the housing or the impeller, or by the view from the side.
To measure the speed of the blades, a device called a tachometer is used. They are both old mechanical and modern, reading information using a laser beam.
To change the side of the direction of rotation of the blades, we just need to change the necessary contacts on the electric motor. If after changing the side of the direction it is not possible to change the position of the blades, then the efficiency and its performance will drop by about 30% of the norm (depending on the type).
All these procedures can be performed without much effort and with your own hands.
