Types of smoke exhausters, their design, characteristics. Direction of rotation and angle of rotation of the fan The main elements of smoke exhausters, as well as centrifugal fans, are

Smoke exhauster for boiler - equipment necessary for efficient work heating system, which is otherwise called “traction fans”. IN engineering networks industrial type, large-sized units of similar action are installed on thermal power plants: blowing and traction, ensuring the stability of the fuel combustion process.

Purpose of the smoke exhauster

The smoke exhauster for a solid fuel boiler is an apparatus for domestic and industrial use. It ensures constant thrust and allows you to control the fuel combustion process. Installation of a smoke exhauster for a furnace is necessary for several reasons:

• thanks to high-quality draft, smoke from the firebox does not penetrate into the boiler room through cracks, as well as when the door is opened;
• the possibility of installing a heating system in conditions of no draft;
• implementation of control over the amount of fuel burned and the intensity of combustion by regulating draft.

There is such a variety of equipment as smoke exhausters, dust collectors and firefighters. The former perform the function of cleaning exiting flue gases. The latter ensure air purification from combustion products during fires and have the function of supplying fresh air(not all models).

There are devices for removing aerosols, small powdery suspensions, and gases. The most powerful units can 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 or 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 letter designations, there are also digital ones. The second ones indicate the diameter of the device or fan wheel. There are three possible design options for smoke exhausters:

A smoke exhauster for a fireplace is a small-sized device with a one-way draft, which is placed in the chimney pipe. Where the device is installed, all gaps are filled with heat-resistant sealant. To ensure effective 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 structurally simple device. It consists of several nodes, each of which has its own purpose.

The body is made in the form of a “snail”, which provides the required swirl of air entering the unit. Made of heat-resistant steel, covered with thermal insulation.

The guide apparatus of the smoke exhauster is located on the suction pipe, allowing you to regulate the air pressure using rotary mechanism, combining the fan blades. Each blade is curved, which allows the air flow to rotate in the same direction in which the rotor rotates. Using a rotating mechanism, you can block the lumen of the pipe to one degree or another.

The smoke exhauster impeller is the unit on which the fan blades are located. They are attached to it by welding or rivets. A rarefied atmosphere is created in the central part of the wheel as it rotates. For this reason, incoming air is drawn in here. Small-sized devices such as smoke exhausters for fireplaces work in a similar way.

The wheel docking unit can be located on the motor shaft or intermediate shaft, depending on the design of the unit. If this is dust collection equipment, the device includes special filters with absorbents. All fire-fighting units are equipped in this way. Ash collectors can be included in the design of boiler room equipment. The design of the smoke exhauster determines its purpose.

The impeller may have holes necessary to fix the blades in a given position. Balancing can be done manually or by an electrical 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 rotation of the blades, regardless of their number and direction of slope, 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 latter are designed to remove fuel combustion products and release them into the atmosphere outside the boiler room.

Fans and smoke exhausters of boiler installations have the same operating principle; they can be left- or right-handed, with forward and reverse draft. These machines are designed for long-term trouble-free operation in a 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 impeller mounted on the electric motor shaft.

Repair of smoke exhausters and fans is carried out by persons who have undergone appropriate certification and instruction in the safety precautions for operating electrical appliances.

Advantages of furnaces with forced-air fans

The design of a modern blower fan for wood-burning and other types of boilers may include ash collectors. This equipment comes in several types:

The latter are the most effective. The operation of cyclones is based on the action of centrifugal forces. The products of fuel combustion are removed by draft action in such a way that they swirl and large particles fall into a special bunker. The design of cyclones may be different, but the principle of operation remains the same.

Smoke exhausters for domestic solid fuel boilers provide stable supply air into the firebox. Therefore, heating equipment can operate uninterruptedly even under unfavorable conditions for fuel combustion. It could be high humidity lumber or 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. There are three types of boiler thermostat:

The design of any of them includes control and adjustment units, temperature-sensitive elements. The regulator operates by reading the physical characteristics of the sensor (temperature-sensitive element). They ( physical properties) change when heated, which is detected by the control unit and transmits a signal to the unit that is included in the structure, 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 fuel combustion in the furnace. A machine without a temperature sensor can always be equipped with one by purchasing and installing additional equipment.

For smoke removal in modern conditions not only ventilation is used, but also other design options created specifically for these purposes. A smoke exhauster, for example, is a fan that creates a powerful air flow and removes from the room all the harmful accumulations that are present in it.

Diagram of the smoke exhauster-dust collector: 1 – drive shaft, 2 – wheel, 3 – clean gas volute, 4 – pipe, 5 – inlet volute, 6 – additional impeller, 7 – control damper, 8 – cyclone, 9 – pipe, 10 – dust shutter, 11 – chimney, 12 – bunker.

Today, such devices have found application not only in everyday life, but also in industry. They are often used in boiler houses that run on solid fuel. This is worth talking about, but a little later.

The most important thing is to understand why such a fan is needed and how it works. Today there are several modifications of it, which differ in characteristics, size and shape. However, despite this, the smoke exhaust device is the same in all configurations.

Main components of the smoke exhauster

Today, the smoke exhauster is a centrifugal fan, which consists of a limited number of parts and assemblies. They all have their own purpose. So, such a fan consists of:

1. Snails. This is a kind of casing, which really resembles this simple insect in its structure. The snail is created in a special way from metal. It is in it that vortex air flows will circulate. This housing allows the unit to operate as efficiently as possible.
2. Impeller. It is sometimes called squirrel. Indeed, its design resembles where this animal runs. This wheel consists of two plates. The first one is mounted on the shaft. A bushing is provided here for these purposes. The second plate is used to fasten the blades, that is metal plates. They have a certain bend angle, which is done specifically to ensure that the air flow works as efficiently as possible.
3. Electric motor. This element is the main one for any fan. This also applies to the smoke exhaust device. Today, a wide variety of engine types are used in industry. As for the smoke exhauster or fan, it is best to use asynchronous models. They are able to work for a long time from a three-phase power supply network. In addition, such units are not that expensive.

Today it is not difficult to purchase them. They are distributed by many specialty stores. Of course, it is best to use smoke exhausters that have the ability to adjust engine rotation. For these purposes, an asynchronous three-phase motor can be equipped with special devices that can have both linear and nonlinear characteristics. Everything depends directly on the specific case.

Of course, when installing a fan or smoke exhauster that has high power ratings, additional protection must be connected. IN in this case This implies the use of an automation system. It is best if a separate circuit breaker is connected to the panel, which will turn off the motor in the event of an unforeseen situation.

The electric motor is thus protected from many unfavorable factors. Automatic machines are selected depending on engine power. In this case, their current strength should exceed the original smoke exhauster by several percent. Today, such protection devices are used everywhere. They allow you to save the unit if a short circuit or breakage of one of the working phases occurs.

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Some characteristics of the frame

It is most often made of metal. This unit is not standard. If necessary, you can even change its shape so that you can easily attach the fan to any base. The frame may be missing.

It all depends on the specific design of the smoke exhauster. They can be mounted in a non-standard way. In this case, everything directly depends on the specific project. There are 6 working schemes in total. Each of them is actively used in practice.

The execution system also affects other components of the unit. They can be additionally equipped with a bearing shaft or a belt drive. Often, manufacturers leave the choice of a specific option to the buyer. If necessary, he can add any working scheme with his innovations.

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Why do you need a smoke exhauster?

So, everything is clear with the fan structure. Now we can talk in more detail about the purpose of the smoke exhauster. In fact, there are several smoke exhausters, because such a device is universal. They are installed in almost all areas of heating systems.

Smoke exhausters occupy a central place in almost all boiler rooms. This is due to their structure and properties. Of course, such units, which have low power, can also be used in industrial enterprises.

Equipment of this type is installed not only on large, but also on small water heating boilers. They can be used in almost all types of boiler rooms known to mankind. However, the work of smoke exhausters is not limited to this area. Due to their versatility, they can be used in other sectors of the national economy where it is necessary to remove smoke from a room or from units.

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Device Features

Basically, all smoke exhausters that are present on the modern market can be produced in two versions, namely right and left rotation. In some situations, it can be quite difficult to determine which way the wheel is turning. However, any specialist can cope with this task.

First you need to approach the unit from the engine side. From here you should be able to see which direction it is spinning. Working wheel. Left rotation is carried out counterclockwise, and the right one – clockwise. The angle of rotation of the snail can be varied. It varies from 0 to 270°. The rotation interval is – 15°.

So, determining the direction of rotation is quite simple. Sometimes there are cases when, during an incorrect connection, the unit begins to work incorrectly, that is, it does not pull smoke out of the room, but drives all the worst out of the room. environment. This is simply unacceptable. This problem can be solved quite simply. It is worth transferring the phases either to circuit breaker, or directly on the engine. That is, you simply need to swap them.

Sometimes stiffening ribs interfere with the operation of smoke exhausters. In this case, some of them can simply be deleted. This is done mechanically.

Visual inspection and maintenance of the units must be carried out through special hatches or openings located on the volute. During operation, condensation may accumulate in the fan. Of course, you need to get rid of it immediately. Fortunately, the design of modern units provides for the presence of special drain holes on the volute. Excess moisture is removed through them.

If large bearings are mounted in the smoke exhauster, then it long years will serve faithfully.

The wear and tear of such units is insignificant. Often, collapsible bearings are used in such smoke exhausters. This is done to ensure that their maintainability is at its best. Large units are quite difficult to work with, but if they are understood, then this will not be a problem.

Some smoke exhausters or fans get quite hot. This also applies to large units. In this case, they can be equipped with an additional cooling coil. Today, many manufacturing companies offer this additional option.

Determining the direction of rotation of the fan scroll is very simple. You need to look at the fan from the suction port (as shown in the figure and photograph). If the impeller rotates clockwise and, accordingly, the casing of the “snail” is also twisted clockwise, then the direction of rotation is right. If counterclockwise - left. The angle of rotation is also not difficult to determine - the position of the outlet opening vertically upward is taken as the starting point, this is zero degrees. Next, clockwise for the right and counterclockwise for the left, with a multiplicity of forty-five degrees, the angles of rotation of the cochlea are measured. You should know that this definition of rotation is typical for general industrial fans. For example, for smoke exhausters and draft fans the opposite is true! You must be very careful when determining the direction of rotation. If you doubt the exact direction of rotation of your fan, consult our managers!
The direction of rotation of the impeller determines the “twist” of the fan casing; it can be right or left. Which direction is considered right and which is considered left is shown in the figure below.

It is very important to choose the right direction of rotation of the fan, since a fan of a certain direction of rotation and rotation angle is installed in the ventilation system. For small units, the direction of rotation may not be important; the angle of rotation of the volute is set when installing the fan in the ventilation system. The larger the fan, the higher value acquires the direction of rotation and the angle of rotation of the volute, since the volute of a large fan consists of two or more parts, installation and dismantling of a volute with an incorrect angle of rotation will be difficult, and in some ventilation systems it will be impossible. The volute of a large unit consists of several parts not only for ease of transportation, but also for ease of maintenance. The volute is uncoupled in such a way that when installing/dismantling the machine, you can first install part of the casing on the foundation, then install the impeller, and then install the second part of the volute. Thus, it is also not necessary to replace the impeller complete dismantling, it is enough to remove only one part of the cochlea body.

see also.

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 exhaust.

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. Based on the type of installation, they are divided into indoor and roof-mounted. How to determine which direction the blades rotate? How to change the direction of rotation? How to determine the frequency of revolutions produced? This is exactly what we will talk about next.

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 directional 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. If the impeller rotates clockwise and the snail-type housing is twisted clockwise, the movement is to the right. If the blades rotate counterclockwise, the side is left.

How to determine the fan speed?

The RPM 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 with accuracy class 0.5 or 1.

Tachometers differ in location of installation and are divided into:

• stationary;
• remote;
• manual.

Tachometers also differ in their operating principle. They are mechanical, magnetic, magnetic induction and electronic.

Modern electronic tachometer in action

Let's look at the example shown in the picture. Using a laser beam directed at the wheel, the rotation speed (rpm) is measured. All data is displayed on a small display.

How to change the direction of rotation of the propeller?

Sometimes situations arise when you need to change the direction of rotation of the blades. For such purposes, reversible fans are used. Their main difference is that the reversible fan is designed for possible changes directions, but the usual one does not.

Reversible model

Reversible models have become widespread at mining enterprises. They serve both to supply air and to exhaust it.

Reversible axle models used in mines

Changing the direction of movement of axial models is carried out in two main ways:

• Without changing the direction of rotation.
• With a change in direction of rotation.

When using the second method without changing the position of the blades, the system does not work at full capacity. The wheel works backwards forward, which reduces efficiency. In order to get 100% performance during reverse, it is necessary 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 at the end. To reverse, you need to transfer the phase and zero from the beginning of the winding to the end.
• In case of three-phase motor at the output we have 6 wires. 3 at the beginning of the winding and 3 at its end. For reverse in three-phase network we need to swap any two wires at the input.
• To reverse a three-phase electric motor connected to a single-phase network through a starting capacitor, it is necessary to swap the cable going to the input of the capacitor with the cable that is not connected to it.

In order to change the direction of travel of the exhaust hood propeller ( kitchen hood) there are two working methods:

1. If the hood design is equipped with asynchronous electric motor, the change is made by reversing the wires (the method is described above).
2. If there is a phase-shifting capacitor, the change is made by rearranging it. For correct execution this method It is recommended that you seek the services of an experienced electrician.

Exhaust hood

Summarize. The direction of wheel travel is determined either by an arrow drawn on the body or impeller, or by looking at it from the side.

A device called a tachometer is used to measure the speed of the blades. They come in both old mechanical ones and modern ones that read information using a laser beam.

To change the direction of rotation of the blades, we simply need to change the necessary contacts on the electric motor. If, after changing the direction side, 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 special effort and with your own hands.