For what purposes is a steam boiler needed: diagram and operation

Design and principle of operation of a steam boiler room

Boiler houses can be divided according to the method of heat supplied (hot water, steam, superheated water, thermal oil), by purpose (heating, process), by type of fuel used (gas, diesel, gas-diesel, fuel oil, gas-fuel oil, solid fuel), by design options ( block-modular, roof-mounted, stationary, attached, built-in). The goal of boiler houses is always the same - to generate heat for further use.

Steam boiler houses are boiler houses in which heat is released through the production of saturated or superheated steam by the boiler room. Steam boiler houses are basically always purely industrial boiler houses, in which the further use of steam for production needs is assumed, or for industrial heating, in which, along with the production load, there is a heating load.

A steam boiler room can be made in various versions, it can be a block-modular boiler room, a stationary boiler room, respectively, one or the other option can be made as a free-standing or attached boiler room, depending on the wishes of the Customer and the conditions of a particular enterprise.

A steam boiler house can also operate on different types of fuel, such as gas (natural gas, liquefied gas), diesel fuel, fuel oil, or have two types of fuel: main and reserve, or emergency (gas-diesel, gas-fuel oil). Also, various types of solid fuel (wood waste, coal, etc.) and possibly various types of alternative fuel can serve as fuel.

The boiler room containing steam boilers that use liquid fuel (fuel oil, diesel fuel, various types of oil, waste oil, etc.) must have appropriate fuel storage facilities and installations for preparing this fuel for combustion in the boiler. This basically comes down to heating the liquid fuel so that it can be atomized in the burners for complete combustion in the boiler firebox.

The boiler room containing boilers that use solid fuel (coal, peat, wood waste, etc.), in addition to storing fuel and preparing it for combustion, must have workshops or ash removal plants because It is not possible to burn completely solid fuel. In addition, great attention must be paid to cleaning flue gases from combustion products, or more precisely from products of incomplete combustion of fuel (soot, etc.). “Cuenod” France, “Ecoflam” Italy, “Weishaupt” Germany, “Saacke” Germany, “ Dreizler" Germany, "Cib Unigas" Italy; pumping and heat exchange equipment, automation and safety systems.

All supplied equipment has certificates of conformity and permits for industrial use in the Russian Federation.

Steam boiler houses produced by our company, at the request of the Customer, can be manufactured to operate in automatic mode and can be operated without the constant presence of maintenance personnel. Control of the operation of the boiler room is carried out directly by the boiler room automation (all information is displayed on the control panel installed in the boiler room) plus a general alarm signal or a group of signals is transmitted to the control panel located outside the boiler room via telephone, GSM or Internet connection.

A steam boiler should be understood as a special device that has a firebox in which fuel combustion occurs. The result of this process is heat generated to produce high pressure steam. This steam can be used for a variety of purposes.

What is a steam generator? For what purposes is it needed? And what is the operating principle of a steam boiler?

Why is it profitable to order steam boiler houses from Teplostroy LLC?

We provide a comprehensive solution to the issue, covering the design of the system according to the client’s specifications, production of the installation at our own enterprise, delivery, installation, configuration, and commissioning. In the production process of the steam boiler house, high-quality imported components are used. Our company takes care of all the hassle of handing over the ready-to-use installation to the supervised authorities.

By ordering the construction of a steam boiler house from us, the client receives the following benefits:

• free consulting support;
• high-quality performance of work by a team of experienced specialists;
• optimal prices for construction;
• strict adherence to order deadlines;
• warranty and post-warranty service.

Devices designed and manufactured by our company can operate on fuels such as liquefied or natural gas, fuel oil or diesel fuel. Steam boiler houses are capable of simultaneously operating on 2 types of fuel, of which one is the main one and the other is a reserve one. Gas-diesel or gas-oil mixed installations are in high demand. But due to the sharp rise in gas and fuel oil prices, steam boiler houses running on alternative fuel have become especially popular today. You can order models using solid fuels: peat, wood waste, coal.

A steam boiler is a device that is used in everyday life and industry. It is designed to convert water into steam. The resulting steam is subsequently used to heat housing or rotate turbomachines. What types of steam engines are there and where are they most in demand?

A steam boiler is a unit for producing steam. In this case, the device can produce 2 types of steam: saturated and superheated. Saturated steam has a temperature of 100ºC and a pressure of 100 kPa. Superheated steam is distinguished by high temperature (up to 500ºC) and high pressure (more than 26 MPa).

Note:

Saturated steam is used in heating private houses, and superheated steam is used in industry and energy. It tolerates heat better, so the use of superheated steam increases the efficiency of the installation.

Where are steam boilers used:

1. In a heating system, steam is an energy carrier.
2. In the energy sector, industrial steam engines (steam generators) are used to generate electricity.
3. In industry, superheated steam can be used to convert into mechanical motion and move vehicles.

Structural elements of a steam boiler and ensuring the safety of working with a steam boiler

The structural elements of a steam boiler include cylinders and vessels of various sizes and diameters, pipes connected to each other into an integral system by means of rolling and welding joints. Absolutely any steam boiler has pipelines, a drum and manifolds. Repair of a steam boiler, its inspection and cleaning are carried out through manholes - special technological openings.

The capacity of the steam boiler, which is filled with water and located inside, is called the water space. The vapor space should be understood as the space that is filled with the resulting steam. The vapor and water spaces are separated from each other by a surface called the evaporation mirror. The steam space contains equipment designed to separate steam and moisture.

The operation of a steam boiler is accompanied by constant and intensive cooling of the metal elements of the entire structure, which are exposed to high temperatures during operation. This allows for safe operation of the steam boiler. Cooling occurs as a result of regular circulation of the coolant through the heating pipes.

Heat from the gases that are formed as a result of fuel combustion enters the pipeline. Meanwhile, the coolant, without stopping, removes heat from the pipeline walls, thereby preventing overheating of the pipeline. If this whole process is not intense enough, the pipeline can overheat greatly, resulting in losing its strength characteristics. Overheating of the pipeline can lead to melting of the pipes or even their rupture. Such phenomena can cause an emergency shutdown of the steam boiler.

Steam boiler - operating principle

The operating principle of the steam generator is quite simple. The operation is based on the heat exchange of steam, water and flue gases. There is a classification of thermal boilers according to the method of movement of heat exchange media. There are two types of boilers: water-tube and fire-tube units. The operating principle of a fire tube boiler is as follows: the heated gas moves inside the pipes, and the water that will be heated is located outside the pipes.

The operating principle of water-tube steam boilers involves the movement of water through pipes. The water heats up as a result of the exposure of the pipes to external flue gases. Due to this effect, the water reaches a boiling state.

Boiler steam equipment is classified depending on the movement of water and steam in them. So, there are boilers with natural and forced circulation. Forced circulation involves the movement of coolants under the influence of pumps specially designed for this purpose. Steam boilers with natural circulation operate as a result of the difference in the densities of steam and water.

In general, the operation of a steam boiler is always approximately the same. It consists of the following: water is prepared in a deaerator, after which, using a pump, it is supplied to the water economizer system, where the water is heated as a result of exhaust gases. Next, the water moves into the upper drum and mixes with the boiler water. Part of the heated water from the boiler enters the lower drum through the boiling pipeline. Here a so-called steam-water mixture is formed. As a result, this mixture rises through the lifting pipeline into the upper drum.

The water remaining in the upper drum descends through lower pipes, which are located outside the furnace, to the collector system of screen pipes. In this case, the steam mixture again ends up in the upper drum of the boiler. The pipeline system that carries out the movement of the coolant should be called a circulation circuit.

The steam that is generated in the evaporators then passes through the so-called steam separators, which are an essential component of fire-tube steam boilers. This is where droplets of moisture are released from the steam. After the steam becomes dry, it flows to the superheater through a steam line. Here the steam is heated to the required temperatures.

Types of steam installations

Steam plants can be either multi-fuel or single-fuel. By type of fuel, steam boilers are classified as:

• coal-fired steam plants;
• steam plants running on fuel oil;
• steam plants running on gas;
• steam plants powered by electricity.

Steam boilers can also be divided into areas of their application. This list includes:

• industrial steam plants;
• steam plants that are focused on generating electricity;
• steam installations that are used in everyday life.

There are also recovery steam plants.

Steam installations also have design differences, and they can be divided into two types:

• water-tube steam plants;
• gas-pipe steam plants.

In gas-tube boilers, water is heated using hot gases that are formed during the combustion of any type of fuel. These gases heat the pipes containing water. The water in these pipes comes from the reservoir.

A water-tube steam plant operates on a slightly different principle. In these boilers, on the contrary, the heated gas moves inside a special pipeline, which is placed in a container of water. Water tube steam boilers are divided into several types:

• vertical water tube boilers;
• horizontal water tube boilers;
• radial water tube boilers.

All types of water tube boilers differ only in the internal arrangement of pipelines.

Boiler operation monitoring

Companies that produce steam boilers must equip the equipment with special control and measuring devices and instruments that allow monitoring the operation of the steam boiler.

The water level in the system can be adjusted using a water meter glass. The water meter glass is an important element of the control system. It is located on the front panel of the firebox casing. This glass is equipped with special taps: lower and upper. The lower one is located at the upper level of the fire box, and the upper valve is installed inside the steam space of the boiler. The taps are connected to each other by a special glass tube and flat glass. This glass is filled with water using the bottom tap and is always under steam pressure coming through the top tap. This device operates on the principle of the law of communicating vessels. This means that the water level in the boiler will always be equal to the water level in the glass vessel.

The water level during boiler operation should always be between the minimum and maximum levels. The minimum level is set to prevent overheating of metal elements. Many models imply a lower water level of at least 100 mm above the fire zone. To prevent water from entering the steam pipeline system, set the maximum level. If water does get into the steam line, it may experience water hammer, which will lead to a serious accident.

The operating principle of industrial and domestic boilers is approximately the same, and their design is very similar. The so-called waste heat boilers are slightly different. Such boilers heat water with the thermal energy of gases emitted by gas turbine units, diesel generators and other equipment. The design of such a boiler is noticeably different from a conventional steam boiler. Secondary gases in the waste heat boiler immediately flow to the heating surface. This boiler does not have an air heater or firebox. Gases with temperatures from 350 to 700 degrees Celsius enter the boiler. As a rule, such equipment is intended for industrial purposes and is installed in large energy-intensive industries.

Once-through boilers

In addition to boilers with natural and forced circulation, there are also so-called direct-flow boilers. The design of such boilers does not have a drum. The water passes through the evaporator line once, gradually turning into steam. In the transition zone, the process of converting water into steam is completed. The steam-water mixture from the evaporation pipeline enters the superheater, where the steam is heated to the required temperature. Some once-through boilers have an intermediate steam heater. It is designed to reheat the steam that came from the turbine unit. Having warmed up again, the steam returns to the turbine. A once-through boiler represents a so-called open hydraulic system. Such a boiler plant can operate at both subcritical and supercritical pressures.

Once-through steam boilers do not require specially equipped premises. They do not require regular operation and technical supervision.

The most important and undeniable advantage of a direct-flow steam boiler is the minimum time required to heat water and the short period of time required to bring the boiler into working condition. Due to all these advantages, once-through boilers serve as backup units, the use of which is necessary in case of failures and during loads of the main boiler equipment.

In addition, once-through boilers have other advantages. Firstly, they allow a higher thermal load. Secondly, there are no heavy and bulky collector installations; it is possible to freely arrange the heating surfaces. The heating surface is used most effectively. Once-through boilers have high efficiency and are quite compact, with high maneuverability.

Main and auxiliary equipment of steam boilers

The steam boiler unit includes the following basic elements and devices:

1. Combustion chamber;
2. Boiler shell (body);
3. Burner – for gas and liquid fuel boilers;
4. Heating surfaces – pipes, screens;
5. Heating elements or electrodes - for electric boilers;
6. Thermal insulation of the body;
7. External decorative cladding;
8. Control, security and automation system;
9. Feed pump.

The combustion chamber of solid fuel boilers is divided into two parts by a grate. Boiler bodies are made of heat-resistant steel.

Burner devices are most often equipped with air pressurization systems. Air is pumped to intensify combustion using a fan.

In electric steam generators, water is heated to boiling by heating elements or electrodes. A special type of steam boilers are induction electric boilers. Here heating is achieved through an induction field.

Thermal insulation of the housing protects the device from heat loss and ensures the absence of hot surfaces. The materials for insulation are modern insulating materials with increased heat resistance; traditional ones are also used - fire-resistant brick, fireclay clay, asbestos-containing fibers.

The automation system provides control over the operation of the device, safety of the mode and parameters, and blocks (interrupts) combustion when critical values ​​are reached.

The feed pump produces a dosed supply of feed water based on signals from level sensors. The device operates in cyclic mode.

Mandatory elements in the boiler design are safety valves, indicating instruments - pressure gauges and thermometers, visual indicators of the water level. The device for visual control is a level-gauging column with level-gauging glasses (at least two). Level sensors are built into the column.

Operation of the boiler is only permitted if both level glasses are in good working order.

Auxiliary equipment of the steam boiler are:

1. Water treatment system;
2. Water economizer;
3. Air heater;
4. Superheater;
5. Deaerator;
6. Separator;
7. Smoke exhauster.

The water treatment system ensures that the quality of make-up water is brought to the required parameters. The main type of water treatment is sodium cation exchanger filters. Water passes through the filler layer in the filter column, and hardness salt ions (Ca+, Mg+) are replaced by table salt ions.

Purification of source water from hardness salts is a prerequisite for normal operation of equipment. With an increased content of salts, they form a solid precipitate on heating surfaces. This significantly reduces the efficiency of heat transfer, ultimately leading to burning of metal surfaces.

In addition to this function, water treatment can dose various special components into the make-up line. These additives bind oxygen, reducing the corrosion rate, and maintaining the required pH level. The use of additional functions has a beneficial effect on the quality of operation of the device and increases its service life.

The water economizer is used to heat the feed water, the air heater is used to heat the air supplied to combustion. Both devices use the heat from the exhaust smoke. The use of these heat exchangers increases the overall efficiency of the boiler unit.

The superheater operates on the same principle (recovery of heat from flue gases). It heats the steam to higher temperatures.

It should be noted that the installation of heat exchange devices on the smoke path requires careful calculations. The devices have high aerodynamic resistance - this can interfere with the removal of smoke and disrupt the combustion process. If the total resistance value is significant, a smoke exhauster is installed.

The deaerator is used to remove air from the feed water. Separation devices are designed to remove the water component from the steam at the boiler outlet. This makes the steam drier, reduces the rate of corrosion processes in the consumption area, and prevents water hammer. Separation is achieved by changing the direction of flow and the diameter of the pipeline.

Steam boilers have high productivity and operate at high temperatures and excess pressure. These conditions complicate the overall design of the boiler unit; additional equipment is required. The principle of operation and operating conditions require the mandatory presence of maintenance personnel.

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Disadvantages of once-through boilers

The disadvantages of a direct-flow steam boiler include too frequent switching on of the burners compared to a fire-tube boiler. There are also no accumulating steam and water tanks here. Despite the fact that this problem can be solved with the help of controlled fuel supply, this can lead to the burners turning on even more often, and the load mode will fluctuate, which will lead to premature wear of the equipment.

In addition, as a result of constantly turning the burners off and on, soot is released, which is deposited on the heating surface and requires removal. In this case, much more fuel is consumed.

The choice of once-through boilers is now quite large. They differ in their power and models. The choice of a steam boiler should be based on the goals and objectives of the equipment.

The rapid development of agriculture and production requires modern high-tech equipment. However, in order to ensure a full production cycle and create comfortable working conditions for employees, specialized equipment for space heating is needed.

Steam boilers are designed to solve these problems. They are actively used in all areas of human life, where it is necessary to constantly maintain a given temperature.

Operating principle of the boiler

To understand what a steam boiler is, let's look at its structure and operating principle. The purpose of using the unit in question is to generate steam. The process occurs due to the formation of heat during the combustion of fuel or heating of tubular electric heaters, and the temperature of the steam boiler liquid reaches the desired level.

The working composition of a steam boiler is water. When it heats up, it goes into a vapor state. The industry produces small boilers with a productivity of up to 20 kg/h and industrial units producing up to 5 thousand tons of steam in one hour.

A steam boiler is a drum filled with water, under which there are lowering pipes necessary for the flow of water into the collectors.

The entire boiler system is technologically connected to each other by pipes. Due to the fact that they contain a mixture with a density lower than the density of water, it rises into the separator. In it, the mixture is divided into liquid and steam, while the steam enters the steam lines and water heater and is supplied to the turbine, and the liquid is returned back to the drum.

The unit consists of:

>Steam pipelines; >Water heater; >Hulls; >Economizer; >Sheathing.

All modifications of boilers have a furnace in which fuel is burned. The resulting heat is absorbed by water, which, upon reaching the desired temperature, evaporates. A process of natural circulation is observed. The products of fuel combustion cool down and are discharged through the chimney.

The body of the unit in question has external thermal insulation and casing in the form of a split steel casing. The water heater allows you to increase productivity and consists of smoke pipes in which water is heated due to the heat of exhaust gases.

There is a safety valve at the bottom of the unit that releases steam if the operating pressure exceeds the permissible limit. The boiler equipment also includes a manual and steam jet injector. The first is necessary for filling with liquid at the beginning of work, as well as for replenishment in the event of a breakdown of the steam jet injector.

To facilitate operation, steam boilers are equipped with automated control systems.

Classification of steam boilers

Depending on the method of heating the coolant, gas, solid fuel and electric steam boilers are distinguished.

Gas-fired steam boilers are characterized by the power to produce saturated steam, measured in kg/h. The main characteristics of the unit are temperature and steam pressure.

Steam gas boilers can use natural or liquefied gas as fuel. The fuel burns in a burner installed on the boiler lid. Flue gases increase the temperature of the water, as a result of which it turns into a vapor state and is supplied under pressure to consumers through an installed steam separator.

A steam hot water boiler can also use wood as fuel. The operating principle of wood-fired steam boilers is based on the heat exchange between the coolant and flue gases. Firewood burns in a firebox surrounded by a cooled water jacket. Flue gases overcome the heat exchanger and exit from the top of the unit. When the heated coolant evaporates, steam is formed. It accumulates on top of the boiler, in the steam collection chamber, and is sent to production needs through a steam pipeline.

Electric-type steam boilers differ from the other two types in their compact size. This allows the steam hot water boilers in question to be installed on the wall.

Currently, electric-type steam water-heating boilers are the most popular, since they do not require the organization of a separate boiler room with a chimney, do not burn oxygen, and have simple controls.

Operating principle and types of steam boilers

If the purpose of heating installations is to heat water to heat the house while preventing it from boiling in the boiler tank, then the operation of a steam boiler solves the opposite problem. It consists of directing all the thermal energy of burning fuel to boil water and evaporate it. Some technological processes require elevated steam temperatures, so the third stage of the unit’s operation is its heating to this temperature (overheating). The main operating indicators of steam generators are pressure and productivity, which is expressed in tons per hour.

The designs of this type of thermal power equipment are different, but the principle of operation of a steam boiler remains unchanged: when burning liquid fuel or natural gas in the furnace, transfer all the heat of combustion to water passing through the heat exchanger in order to evaporate it and send it to consumers. According to the method of heat transfer in steam generators, heat exchangers are used:

• fire tubes (smoke tubes);
• water tube

They have one common feature: they are pipes manufactured in various installations of different sections and shapes. One of the media participating in the heat transfer process moves inside the pipes, and outside they are washed by the second medium. In fire tube heat exchangers, hot combustion products pass inside, heating the water in the boiler tank to a state of steam formation. Everything happens the other way around in a water-tube unit, where water circulates through coils, and it is heated from the outside by a burner flame and flue gases.

Definition

As you already understand, a steam boiler is a unit that produces steam. In this case, boilers of this type can produce two types of steam: saturated and superheated. In the first case, its temperature is about 100 degrees, and the pressure is about 100 kPa. The temperature of the superheated steam rises to 500 degrees and the pressure to 26 MPa. Saturated steam is used for domestic purposes, mainly for heating private houses. Superheated steam has found application in industry and energy. It tolerates heat well, so its use greatly increases the efficiency of the installation.

What is this device?

A steam boiler can produce two types of steam:

• steam that is saturated with water;
• dry steam, which is also called “superheated”.

The first type of water steam is designed to work in systems with a working pressure of no more than 100 kiloPascals. Saturated steam is heated to a temperature not exceeding 100 degrees Celsius.

The second type of steam in a steam boiler is designed to work in systems with high pressure - more than 26 megaPascals. Dry steam has a higher temperature, and this temperature sometimes exceeds 500 degrees Celsius.

Basically, heating systems use saturated steam, where the pipelines are not designed for high pressure. Dry steam is used in power plants. Using superheated steam, powerful installations operate that rotate electric generators. In some types of vehicles, superheated steam is the main traction force.

Scope of application

There are three main areas of application for steam boilers:

1. Heating systems. Steam acts as an energy carrier. 2. Energy. Industrial steam engines, or steam generators as they are also called, are used to generate electrical energy. 3. Industry. Steam in industry is used not only to heat the “jackets” of devices and pipelines, but also to convert thermal energy into mechanical energy and move vehicles. Domestic steam boilers are used for heating residential premises. In simple words, their task is to heat water and move steam through the pipeline. Such a system is often installed together with a stationary stove or boiler. Typically, household appliances produce saturated, non-superheated steam, which is quite sufficient to solve the tasks assigned to them.

In industry, steam is overheated - it continues to be heated after evaporation in order to increase the temperature even more. Such installations are subject to special quality requirements, since if the steam overheats, the container runs the risk of exploding. Superheated steam obtained from the boiler can be used to generate electricity or mechanical movement.

An electric current is generated using steam as follows. Evaporating, the steam enters the turbine, where, thanks to the dense flow, it rotates the shaft. Thus, thermal energy is converted into mechanical energy, which, in turn, is converted into electrical energy. This is how power plant turbines work.

The rotation of the shaft, which occurs when large quantities of superheated steam evaporate, can be transmitted directly to the motor and wheels. This is how steam transport is set in motion. Popular examples of the operation of a steam engine include the steam generator of a steam locomotive or a ship's steam boiler. The principle of operation of the latter is quite simple: burning coal produces heat, which heats water and produces steam. Well, the steam, in turn, rotates the wheels, or in the case of a ship, the screws.

Let's take a closer look at how such boilers work. The source of heat required to heat water can be any type of energy: electric, solar, geothermal, heat from the combustion of gas or solid fuel. The steam generated during the heating process of water is a coolant, that is, it transfers thermal energy from the place of heating to the place of use.

Despite the variety of designs, the fundamental structure and operating principle of steam boilers are no different. The general scheme for heating water and then converting it into steam looks like this:

1. Purification of water using filters and its supply to the tank for heating using a pump. The reservoir is usually located at the top of the installation.
2. From the reservoir, through pipes, water enters the collector, located, respectively, below.
3. The water rises again, only now not through the pipes, but through the heating zone.
4. Steam is generated in the heating zone. Under the influence of the pressure difference between the liquid and gaseous substance, it will rise upward.
5. At the top, the heated steam is passed through a separator where it is finally separated from the water. The remaining liquid is returned to the tank, and the steam follows into the steam line.
6. If this is not an ordinary boiler, but a steam generator, then its pipelines are additionally heated. Methods for heating them will be discussed below.

Technological application of boiler steam plants

There are several industries where steam boilers are constantly used:

1. The first industry is thermal power engineering. Steam is used to heat large workshops, for example in the automotive industry. The steam heats the water to the required temperature, which is then driven by pumps along heating mains to multi-storey buildings and other objects.
2. The second industry is energy. Here, steam is used to spin a turbine, which produces electric current.
3. The third industry is the production of building materials. For example, concrete products are dried with steam.

In many industries, steam boilers are an integral part of the technology. This includes disinfection, drying of food products, culinary processing, preservation, etc.

Disposal of gaseous waste also involves the use of steam plants. In this process they act as coolers. Such a boiler takes thermal energy from gases coming out, for example, from high-temperature furnaces.

Device

Steam boilers are a container in which water is heated and produces steam. They are usually made in the form of pipes of various sizes. In addition to the water pipe, the boiler always has a fuel combustion chamber (furnace). Its design may vary depending on the type of fuel used. If it is firewood or hard coal, then a grate is installed in the lower part of the firebox, on which the fuel is placed. Air enters the combustion chamber from the bottom of the grate. And at the top of the firebox there is a chimney, which is necessary for effective draft - air circulation and fuel combustion.

The operating principle of solid fuel steam boilers is somewhat different from devices that use liquid or gaseous material as a coolant. In the second case, the combustion chamber involves a burner that operates similar to the burners of a household gas stove. A grate and a chimney are also used for air circulation, because regardless of the type of fuel, air is the most important condition for combustion.

The combustible gas obtained from the combustion of fuel rises to a container of water. It gives off its heat to the water and exits through the chimney into the atmosphere. When water reaches its boiling point, it begins to evaporate. It is worth noting that water evaporates earlier, but not in such quantities and not with the same vapor temperature. The evaporated steam enters the pipes on its own. Thus, the circulation of steam and the change in the state of aggregation of water occurs naturally. The operating principle of a natural circulation steam boiler requires minimal human intervention. All the operator needs to do is ensure stable water heating and control the process using special devices.

In the case of electric boilers, heating water is easier. It is heated using heating elements such as heating elements or acts as a conductor and is heated according to the Joule-Lenz law.

Operating principle

All types of steam boilers have common elements:

1. Drum.
2. Drop pipes.
3. Collector.
4. Flame tubes.
5. Separator.
6. Steam heater.

The drum is connected to the manifold by lowering and flame pipes.
The downpipes do not heat up. Flame tubes are placed in the firebox, and depending on the stage of fire development, a certain amount of steam is formed in them, which does not yet have operational characteristics. The separator is located in the drum, and the steam heater is attached to the drum. The operating principle of a steam boiler for heating a house is to produce steam with the required characteristics. The operation of the unit with automatic regulation of pressure balance and power development consists of the following stages:

1. Cold purified water enters the drum.
2. Afterwards it moves through the downpipes into the collector.
3. Then it enters the flame tubes. Fire with flue gases heats their outer surface, thereby heating the water to boiling point. Steam begins to form in it. Its characteristics are not yet working.
4. The liquid with steam, which still has non-working characteristics, is returned to the drum. The steam moves upward and, passing through the separator, is separated from the water.
5. The condensate is returned to the drum, and the steam is supplied to the superheater, where it receives increased characteristics. As a result, there is a significant increase in pressure, productivity, and the efficiency of the boiler installation increases.
6. Superheated steam at high pressure is supplied to the heating network.

The operating principle of an electric steam boiler is almost the same. It heats water to a temperature of 100 °C. Its structure does not have lowering or flame pipes because the drum is located in the middle of the collector. Manufacturers call the drum an internal chamber and the collector an external chamber.

During operation of the electric automatic unit, water first enters the outer chamber, and then into the inner one, at the top of which there is a separator. The water is heated by a plate electrode.

What is the difference between gas and water tube steam boilers?

The operating principle of boilers is based on heating a container of water. The container in which water turns into a vapor state is usually a pipe or several pipes. Devices in which fuel heats pipes by rising upward are called gas-tube boilers.

But there is another option - when flammable gas moves through a pipe located inside a container of water. In this case, the water tanks are called drums, and the boiler itself is called a water-tube boiler. In everyday life it is also called a fire tube boiler. Depending on the location of the water drums, boilers of this type are divided into: horizontal, vertical and radial. There are also models in which different directions of pipes are implemented.

The design and principle of operation of a fire-tube steam boiler is somewhat different from a gas-tube boiler. Firstly, this concerns the size of the water and steam pipes. Water-tube boilers have smaller pipes than gas-tube boilers. Secondly, there are differences in power. A gas-tube boiler produces a pressure of no more than 1 MPa and has a heat-generating capacity of up to 360 kW. The reason for this is large pipes. In order for sufficient steam and pressure to be generated in the pipes, their walls must be thick. As a result, the price of such boilers is too high. A water tube boiler is more powerful. Thanks to the thin walls of the pipes, the steam heats up better. And thirdly, water tube boilers are safer. They produce high temperatures and are not afraid of significant overloads.

Additional boiler elements

The operating principle of a steam boiler is quite simple, however, its design consists of a fairly large number of elements. In addition to the combustion chamber and pipes for circulating water/steam, boilers are equipped with devices to increase their efficiency (increasing steam temperature, pressure and quantity). Such devices include:

1. Superheater. Serves to increase the steam temperature above 100 degrees. Superheating the steam increases the efficiency of the device and its efficiency. Superheated steam can reach temperatures of 500 degrees Celsius. Such high temperatures occur in steam installations of nuclear power plants. The essence of overheating is that after evaporation, the steam moving through the pipe is reheated. To do this, the device can be equipped with an additional combustion chamber or a simple pipeline, which passes through the main firebox several times before releasing the steam for its intended use. Superheaters are either radiation or convection. The first ones work 2-3 times more efficiently.
2. Separator. Serves to “drain” steam - separating it from water. This allows you to increase the efficiency of the installation.
3. Steam accumulator. This device is designed to maintain a constant level of steam output from the installation. When there is not enough steam, it adds it to the system and, conversely, takes it away in case of excess.

Water preparation device. In order for the device to work longer, the water entering it must meet specific requirements. This device reduces the amount of oxygen and minerals in the water. These simple measures help prevent corrosion of pipes and the formation of scale on their walls. Rust and scale not only reduce the efficiency of the device, but also quickly render it unusable, especially in the case of active use.

Control devices

In addition, the boiler is equipped with auxiliary devices for monitoring and control. For example, a water limit indicator monitors the maintenance of a constant liquid level in the drum. The operating principle of a steam boiler limit switch is based on the change in the mass of special loads during their transition from the liquid phase to the vapor phase, and vice versa. In case of deviation from the norm, it gives a sound signal to alert the company employees.

For positional control of the water level, a level-measuring column of the steam boiler is also used. The operating principle of the device is based on the electrical conductivity of water. The column is a tube equipped with four electrodes that control the water level. If the water column reaches the lower level, the feed pump is connected, and if it reaches the upper level, the water supply to the boiler stops.

Another simple device for measuring the water level in a steam boiler is a water meter glass built into the body of the apparatus. The principle of operation of the water gauge glass of a steam boiler is simple - it is designed to visually monitor the water level.

In addition to the liquid level, temperature and pressure are measured in the system using thermometers and pressure gauges, respectively. All this is necessary for the normal functioning of the boiler and to prevent the possibility of emergency situations.

Steam generators

We have already examined the principle of operation of a steam boiler, now we will briefly get acquainted with the features of steam generators - the most powerful boilers equipped with additional devices. As you already understood, the main difference between a steam generator and a boiler is that its design includes one or more intermediate superheaters, which allows it to achieve the highest steam temperatures. At nuclear power plants, thanks to very hot steam, the energy of atomic decay is converted into electrical energy.

There are two main ways to heat water and convert it into a gaseous state in a reactor:

Water washes over the reactor vessel. In this case, the reactor is cooled and the water is heated. Thus, steam is generated in a separate circuit. In this case, the steam generator acts as a heat exchanger. Water pipes run inside the reactor. In this embodiment, the reactor is a combustion chamber from which steam is supplied directly to the electric generator. This design is called a boiling water reactor. Here everything works without a steam generator.

Areas of application of steam boilers and purpose

Steam boilers are actively used in the following industries:

1. Heating systems . There are industrial and domestic models of steam boilers that allow the use of steam as a coolant. The steam passes through the heating circuits and/or enters the heat exchangers of hot water supply devices, thereby transporting thermal energy. A household steam heating boiler is often combined with solid fuel heating devices. Industrial facilities use more powerful and reliable devices that produce superheated steam with increased heat transfer.
2. Energy . Steam engines allow you to convert heated steam into electrical energy. The working process looks quite simple: steam moves into the turbine and rotates the shaft, due to which electricity is generated. This principle has been successfully used in many power plants.
3. Industry . Steam devices may well provide mechanical movement of various system elements. The operating principle of an industrial steam boiler looks the same as in the previous case, but the generated energy is aimed at exerting a mechanical effect on the elements that must move.

Knowing what a steam boiler is for and where it is used allows you to use the device with utmost efficiency.