General information about boiler installations, types of boilers for building heat supply. What are the boiler rooms

1. Boiler plants

1.1 General information and concepts of boiler plants

The boiler plant is a complex of devices located in special rooms and serving to convert the chemical energy of the fuel into thermal energy couple or hot water. The main elements of the boiler plant are the boiler, the combustion device (furnace), feed and draft devices.

Boiler - heat exchange device, in which the heat from the hot combustion products of the fuel is transferred to the water. As a result, in steam boilers, water is converted into steam, and in hot water boilers it is heated to the required temperature.

The combustion device serves to burn fuel and convert its chemical energy into heat of heated gases.

Feeding devices (pumps, injectors) are designed to supply water to the boiler.

The draft device consists of blowers, a system of gas ducts, smoke exhausters and a chimney, with the help of which the supply of required amount air into the furnace and the movement of combustion products through the gas ducts of the boiler, as well as their removal into the atmosphere. Combustion products, moving through the gas ducts and in contact with the heating surface, transfer heat to the water.

To ensure more economical operation, modern boiler plants have auxiliary elements: water economizer and air heater, respectively, for heating water and air; devices for fuel supply and ash removal, for cleaning flue gases and feed water; thermal control devices and automation equipment that ensure the normal and uninterrupted operation of all parts of the boiler room.

Depending on the purpose for which thermal energy is used, boiler houses are divided into energy, heating and production and heating.

Power boilers supply steam to power plants that generate electricity and are usually part of a power plant complex. Heating and production boiler houses are built at industrial enterprises and provide thermal energy for heating and ventilation systems, hot water supply of buildings and technological production processes. Heating boiler rooms are intended for the same purposes, but serve residential and public buildings. They are divided into separate, interlocked, i.e. adjacent to other buildings, and built into buildings. AT recent times more and more often stand-alone enlarged boiler houses are being built with the expectation of serving a group of buildings, a residential quarter, a microdistrict.

The installation of boiler houses built into residential and public buildings is currently allowed only with appropriate justification and coordination with the sanitary supervision authorities.

Boiler houses low power(individual and small group) usually consist of boilers, circulation and make-up pumps and draft devices. Depending on this equipment, the dimensions of the boiler room are mainly determined.

Boiler houses of medium and high power- 3.5 MW and above - they are distinguished by the complexity of the equipment and the composition of service and amenity premises. The space-planning solutions of these boiler houses must meet the requirements of the Sanitary Design Standards for Industrial Enterprises (SI 245-71), SNiP P-M.2-72 and 11-35-76.

1.2 Classification of boiler plants

Boiler plants, depending on the nature of consumers, are divided into energy, production and heating and heating. According to the type of heat carrier produced, they are divided into steam (for generating steam) and hot water (for generating hot water).

Power boiler plants produce steam for steam turbines at thermal power plants. Such boiler houses are equipped, as a rule, with boiler units of large and medium power, which produce steam with increased parameters.

Industrial heating boiler plants (usually steam) produce steam not only for industrial needs, but also for heating, ventilation and hot water supply.

Heating boiler plants (mainly water-heating, but they can also be steam) are designed to service heating systems for industrial and residential premises.

Depending on the scale of heat supply, heating boiler houses are divided into local (individual), group and district.

Local boiler houses are usually equipped with hot water boilers with water heating up to a temperature of not more than 115 ° C or steam boilers with an operating pressure of up to 70 kPa. Such boiler houses are designed to supply heat to one or more buildings.

Group boiler plants provide heat to groups of buildings, residential areas or small neighborhoods. Such boiler houses are equipped with both steam and hot water boilers, as a rule, with higher heat output than boilers for local boiler houses. These boiler houses are usually located in specially constructed separate buildings.

District heating boiler houses are used to supply heat to large residential areas: they are equipped with relatively powerful hot water or steam boilers.

On fig. 1.1 shows a diagram of a boiler plant with steam boilers. The installation consists of a steam boiler 4, which has two drums - upper and lower. The drums are interconnected by three bundles of pipes forming the heating surface of the boiler. When the boiler is operating, the lower drum is filled with water, the upper drum is filled with water in the lower part, and saturated steam in the upper part. In the lower part of the boiler there is a firebox 2 with a mechanical grate for burning solid fuel. When burning liquid or gaseous fuel instead of a grate, nozzles or burners are installed through which fuel, together with air, is supplied to the furnace. Boiler limited brick walls- brickwork.

Rice. 1.1. Scheme of a steam boiler plant

The working process in the boiler room proceeds as follows. Fuel from the fuel storage is fed by a conveyor to the bunker, from where it enters the grate of the furnace, where it burns. As a result of fuel combustion, flue gases are formed - hot products of combustion.

Flue gases from the furnace enter the boiler gas ducts, formed by lining and special partitions installed in pipe bundles. When moving, the gases wash the bundles of pipes of the boiler and superheater 3, pass through the economizer 5 and the air heater 6, where they are also cooled due to the transfer of heat to the water entering the boiler and the air supplied to the furnace. Then, the significantly cooled flue gases are removed by means of a smoke exhauster 5 through the chimney 7 into the atmosphere. Flue gases from the boiler can also be discharged without a smoke exhauster under the action of natural draft created chimney.

Water from the source of water supply through the supply pipeline is supplied by pump 1 to the water economizer, from where, after heating, it enters the upper drum of the boiler. The filling of the boiler drum with water is controlled by the water-indicating glass installed on the drum.

From the upper drum of the boiler, water descends through pipes into the lower drum, from where it rises again through the left bundle of pipes into the upper drum. In this case, the water evaporates, and the resulting steam is collected in the upper part of the upper drum. Then the steam enters the superheater 3, where it is completely dried due to the heat of the flue gases, and its temperature rises.

From the superheater, steam enters the main steam pipeline and from there to the consumer, and after use it condenses and returns in the form of hot water (condensate) back to the boiler room.

Losses of condensate at the consumer are replenished with water from the water supply system or from other sources of water supply. Before entering the boiler, water is subjected to appropriate treatment.

The air necessary for fuel combustion is taken, as a rule, from the top of the boiler room and is supplied by fan 9 to the air heater, where it is heated and then sent to the furnace. In boiler houses of small capacity, air heaters are usually absent, and cold air is supplied to the furnace either by a fan or due to rarefaction in the furnace created by a chimney. Boiler plants are equipped with water treatment devices (not shown in the diagram), instrumentation and appropriate automation equipment, which ensures their uninterrupted and reliable operation.

Hot water boiler plants are designed to produce hot water used for heating, hot water supply and other purposes.

On fig. 1.2 shows a diagram of a district heating boiler house with hot water boilers 1 type PTVM-50 with a heat output of 58 MW. The boilers can run on liquid and gaseous fuels, so they are equipped with 3 burners and nozzles.

The air necessary for combustion is supplied to the furnace by 4 blowers driven by electric motors. Each boiler has 12 burners and the same number of fans.

Water is supplied to the boiler by pumps 5 driven by electric motors. After passing through the heating surface, the water heats up and enters the consumers, where it gives off part of the heat and returns to the boiler with a reduced temperature. Flue gases from the boiler are removed to the atmosphere through pipe 2.

Rice. 1.2. Scheme of a district heating boiler plant with hot water boilers


The layout of the semi-open boiler room: Bottom part boilers (up to about 6 m high) is located in the building, and their upper part is in the open air. Inside the boiler house there are blow fans, pumps, as well as a control panel. A deaerator 6 is installed on the ceiling of the boiler house to remove air from the water.

Boiler plant with steam boilers (Fig. 1.1) has a layout closed type when all the main equipment of the boiler house is located in the building.

UDMURT STATE UNIVERSITY

FACULTY OF PHYSICS AND ENERGY

Department of General Engineering Disciplines

On the topic “Boiler installations. Classification. The composition of boiler plants, the main design solutions. Layout and placement of boiler plants»

Completed by: Voronov V.N.

Student of the group FEF 54-21 "__" ________ 2012

Checked by: Karmanchikov A.I.

Associate Professor "__" ________ 2012

Izhevsk 2012

Boiler plants

Boiler plants are designed for heating working fluid, which then enters the heating and water supply systems. The working fluid is usually plain water. The transfer of the heated working fluid from the boiler plant to the heat supply system is carried out using a heating main, which is a pipe system.

Boiler plants basically have a hot water or steam boiler, in which a direct supply and heating of the working fluid is carried out. The choice of boiler parameters depends on many characteristics. The volume of the boiler is calculated based on the size and characteristics of the heating system.

Boiler plants can be located both inside the facility and outside it. Inside the facility, they can be installed in the basement, a separate room and even on the roof. If the building is a large object, then the boiler plants are made in the form of separate buildings with their own engineering system connected to the general engineering system of the facility.

Various types of fuel are used in the operation of boiler plants. Boilers operating on natural gas have become the most widespread today. Since our country is the leader in the reserves of this type of fuel, there is no need to fear that energy resources may run out. In addition to gas, boiler plants use petroleum products (fuel oil, diesel fuel), solid fuels (coal, coke, wood) as fuel. A number of boiler houses can use combined fuels. An important characteristic of any boiler house is the category of reliability of heat supply to consumers.

All existing boiler plants can be conditionally divided into separate paths, each of which performs its own function, ensuring normal safe work boiler and boiler room as a whole. So, boiler plants consist of the following paths: air, fuel, gas, ash and slag removal and steam water.

The main element of any boiler plant is the boiler. Its main elements are screens, consisting of bent pipes, which serve to transfer heat to a steam-water mixture, steam, water or air, which are also called working fluids. The water that enters the boiler plant is heated in the furnace to the boiling point, passing through the screens, it gradually heats up to the saturation temperature, is converted into steam, which, in turn, overheats to the required temperature.

Depending on the transformation of the working fluid, three processes of the heating surface of the boiler are distinguished: evaporative, heating and superheating. The heating surfaces, in turn, also differ depending on the method of heat transfer to the working fluid, into three groups:

convective - obtaining heat from a source using convective processes;

radiation - obtaining heat from thermal radiation of fuel combustion products;

radiative-convective - obtaining heat both due to convection and due to thermal radiation of the fuel.

The heating surfaces in boiler plants are economizers, in which the heating or partial vaporization of the feed water that enters the steam boiler takes place. Accordingly, economizers are of boiling and non-boiling types. They are located in zones of relatively low temperatures in convective drop shafts. Evaporation surfaces are most often located directly in the boiler furnace or in the flue gas directly behind the combustion chamber, where the highest temperatures are set.

There are several types of evaporative surfaces: scallops, boiler bundles and furnace screens. Furnace screens consist of pipes located in the same plane. They are located near the walls of the combustion chamber and protect them from overheating. If the screens are installed inside the furnace and are exposed to two-sided irradiation, then they are called double-light.

Once-through boilers up to critical pressure have furnace screens located in the lower part of the furnace, due to which they are called the lower radiation part. Boiler bundles and scallops are used in boilers of low capacity medium pressure boilers. The scallops are formed by pipes of the rear screen, which are separated from each other by a considerable distance by the formation of multi-row beams and represent semi-radiant heating surfaces.

Boiler installations is a set of equipment designed to convert the chemical energy of the fuel into thermal energy in order to obtain hot water or steam of specified parameters. There are various classifications of boiler houses, among which one can distinguish a classification by design options (roof, stationary, built-in, attached and modular boilers are distinguished here). Boilers according to the method of released heat are also divided into steam, hot water, thermal oil; If we talk about the used fuel, then boiler houses can be divided into solid fuel, fuel oil, gas and combined, according to their purpose, they are divided into heating and technological ones. The boiler plant consists of a boiler unit, auxiliary mechanisms and devices

Under each of these classifications, only transportable boiler plants are suitable, the demand for which is constantly increasing. First of all, this, of course, is due to their versatility. Of all the autonomous boiler houses on the market today, only these boiler houses include four systems: heating, gas, water heating and steam. This allows customers to solve several issues at once with a single installation, which significantly reduces the expenditure side of the budget. Savings can also be made by purchasing a boiler room with burners that can operate on a combined type of fuel.

Modular boiler rooms are economical in their transportation, installation and operation. Costs are also reduced due to the high automation of the boiler house, which for a long time is able to work offline, set at its start. If a large staff works at huge CHPPs, then one operator is enough to control the operation of a block-modular boiler house. Its work will become even less laborious if a microprocessor is built into the boiler room, which most accurately reads and transmits all information from all devices of the boiler room to a special remote control.

It is worth noting that a block boiler plant has the highest efficiency of all possible, this is combined with minimal costs for its maintenance and its immediate operation. Thus, by purchasing a block boiler plant, its owner will quickly recoup its cost and be able to earn income (this is if we are talking about the owners of industries and construction companies); and if a block-modular boiler room was purchased by an ordinary person, the owner own house, then he can be sure that during the entire operational life of the boiler plant he will not be left without heat and hot water.

Boiler equipment

Boiler equipment, which is part of boiler plants, ensures the implementation of the technological process of heating the working fluid in the boiler. The composition of the boiler equipment includes:

    hot water and steam boilers

  • water treatment plants

    boiler pipes, valves

    heat generators

    water level indicators

    sensors and controllers

    and much more

Boiler equipment is selected based on the operating conditions and the required technical characteristics for this boiler plant.

Gas boilers

Gas boilers are the most common type of boiler installations today. The obvious advantages are their low cost of construction and operation in comparison with other types of boiler plants. The country's extensive gas pipeline network, which is in constant development, allows gas to be supplied to almost any point. This leads to lower costs for the delivery of working fuel by conventional transport. In addition, gas has a higher heat capacity and heat transfer compared to other fuels, it leaves less harmful substances after combustion.

At industrial enterprises, gas-fired boilers are the main source of heat supply for technological processes and for providing heat to working personnel. However, in private residential buildings gas-fired boilers also began to appear more frequently. People appreciated the advantages of such installations.

Gas boilers are an indispensable source of energy, cheaper than electricity.

Modular boiler rooms

Modular boiler rooms are ready-made engineering systems that can be easily transported and installed anywhere. Using modular boilers, you can significantly save on design and installation, as these systems are usually mounted ready-made in a container and equipped with everything necessary equipment for work and process automation.

The modular boiler rooms include the following equipment:

    hot water boilers

    technological equipment

    automation systems

    water treatment systems

    and much more

The composition of the equipment included in modular boilers depends on the required power of boiler plants. The obvious advantage that modular boilers have is their mobility and cheaper installation and operation costs.

A boiler is a heat exchange device in which heat from hot fuel combustion products is transferred to water. As a result, in steam boilers, water is converted into steam, and in hot water boilers it is heated to the required temperature.

The combustion device serves to burn fuel and convert its chemical energy into heat of heated gases.

Feeding devices (pumps, injectors) are designed to supply water to the boiler.

The draft device consists of blowers, a system of gas ducts, smoke exhausters and a chimney, with the help of which the necessary amount of air is supplied to the furnace and the movement of combustion products through the boiler flues, as well as their removal into the atmosphere. Combustion products, moving along the gas ducts and in contact with the heating surface, transfer heat to the water.

To ensure more economical operation, modern boiler plants have auxiliary elements: a water economizer and an air heater, which serve to heat water and air, respectively; devices for fuel supply and ash removal, for cleaning flue gases and feed water; thermal control devices and automation equipment that ensure the normal and uninterrupted operation of all parts of the boiler room.

Classification.

Block modular boiler rooms with a capacity of 200 kW to 10,000 kW (model range)

There are individually designed boiler rooms of different types:

    Rooftop boilers

    Stand-alone boiler rooms

    Block and modular boiler rooms

    Built-in boiler rooms

    Attached boiler rooms

    Transportable and mobile boiler rooms

Each boiler house is designed on the basis of SNiP II-35-76 "Boiler plants". The calculation and design of the boiler house is carried out by certified specialists who have been trained at the boiler equipment manufacturers.

Control of all parameters of work is carried out by automated control systems without the presence of a person.

Compound boiler houses in basic version:

    Hot water boilers Reliability of heat release is guaranteed by the presence of boiler houses at least two boiler units, represented by steel fire-tube boilers of reliable and successfully proven German companies on the Russian market Buderus, Viessmann.

    Weishaupt burners Used in boiler rooms burners of the German company Weishaupt. Used to burn natural gas burners in LN version, providing a low content of harmful impurities in combustion products.

    Internal gas supply Gas supply system equipment boiler houses regulates the gas flow and controls the minimum and maximum gas pressure levels. In case of emergency situations, the flow of gas into boiler room stops automatically.

    Heating water temperature control Microprocessor programmable controllers are used that automatically control the network water temperature control system depending on the outdoor temperature and the needs of the Consumer.

    Pump equipment Boiler circuit pumps provide independent operation boilers. Dual circuit circulation pumps guarantee 100% redundancy.

    Water treatment and pressure maintenance in the heating system The water treatment plant reduces the hardness of the boiler water and prevents the formation of scale on the heat exchange surfaces of the equipment. The pressure maintenance device automatically feeds the boiler and network circuits with water, providing the required pressure level in the heating system.

    hydraulic separator Equipment for hydraulic decoupling of the boiler and network circuits makes it possible to ensure the stable operation of the boiler house in systems with a large volume of water with intensive dynamics of changes in flow rates, temperature and pressure.

    Signaling The boiler rooms are equipped with fire alarm and gas alarm systems for methane and carbon monoxide.

    Metering devices Control and measuring devices registered in the State Register of Measuring Instruments are used, which allow to carry out: - Accounting for the supplied thermal energy - Accounting for consumption cold water– metering of gas consumption – metering of consumed electricity – control of operating parameters of boiler room equipment.

    Integrated automation The integrated automation system ensures the stable operation of boiler rooms without the constant presence of maintenance personnel. remote control operation of the main equipment of the boiler room is carried out by means of a remote dispatching alarm panel (included in the scope of delivery).

    Modem communication for remote dispatching Boiler houses at the time of installation or any period of further operation can be connected to modern remote dispatching systems. The integrated automation system has a built-in block modem for transmitting data on the operation of boiler equipment via telephone channels or the Internet.

    Chimneys The outer and inner walls of the chimneys are made of of stainless steel and insulated with rigid mineral wool insulation. The chimneys used have a certificate of conformity fire safety. For each heating boiler is installed separate pipe. Chimneys with a height of 6 meters are included in the scope of delivery for boiler rooms from 200 kW to 10 MW. Upon request, the Buyer may refuse the chimney, and also has the opportunity to install chimneys of a different height.

Constructive decisions Boiler houses, depending on size and quantity boilers, consist of one or more blocks. Depending on climatic conditions, the metal frame of the modules is insulated with rigid three-layer sandwich panels with mineral wool insulation with a thickness of 80 to 150 mm. The characteristics of the enclosing structures of the modules comply with the regulatory requirements for fire resistance and fire safety.

Low-power boiler houses (individual and small group) usually consist of boilers, circulation and make-up pumps and draft devices. Depending on this equipment, the dimensions of the boiler room are mainly determined.

Boilers of medium and high power - 3.5 MW and above - are distinguished by the complexity of the equipment and the composition of service and amenity premises. The space-planning solutions of these boiler houses must meet the requirements of the Sanitary Design Standards for Industrial Enterprises (SI 245-71), SNiP P-M.2-72 and 11-35-76.

Classification of boiler plants

Boiler plants, depending on the nature of consumers, are divided into energy, production and heating and heating. According to the type of heat carrier produced, they are divided into steam (for generating steam) and hot water (for generating hot water).

Power boiler plants produce steam for steam turbines in thermal power plants. Such boiler houses are equipped, as a rule, with boiler units of large and medium power, which produce steam with increased parameters.

Industrial heating boiler plants (usually steam) produce steam not only for industrial needs, but also for heating, ventilation and hot water supply.

Heating boiler plants (mainly water-heating, but they can also be steam) are designed to service heating systems for industrial and residential premises.

Depending on the scale of heat supply, heating boiler houses are divided into local (individual), group and district.

Local boiler houses are usually equipped with hot water boilers with water heating up to a temperature of not more than 115 ° C or steam boilers with an operating pressure of up to 70 kPa. Such boiler houses are designed to supply heat to one or more buildings.

Group boiler plants provide heat to groups of buildings, residential areas or small neighborhoods. Such boiler houses are equipped with both steam and hot water boilers, as a rule, with higher heat output than boilers for local boiler houses. These boiler houses are usually located in specially constructed separate buildings.

District heating boiler houses are used to supply heat to large residential areas: they are equipped with relatively powerful hot water or steam boilers.

boiler plant with steam boilers. The installation consists of a steam boiler, which has two drums - upper and lower. The drums are interconnected by three bundles of pipes forming the heating surface of the boiler. When the boiler is operating, the lower drum is filled with water, the upper drum is filled with water in the lower part, and saturated steam in the upper part. In the lower part of the boiler there is a furnace with a mechanical grate for burning solid fuel. When burning liquid or gaseous fuels, nozzles or burners are installed instead of a grate, through which fuel, together with air, is supplied to the furnace. The boiler is limited by brick walls - brickwork.

Boiler plants located in specially designated areas, where unauthorized persons have no access. And already heating mains and heat pipelines connect boiler houses and consumers.

Classification of boiler rooms.

Modern boiler plants have a different classification. Each of them is based on a certain principle or certain meanings. To date, there are several main differences:

Location.

Depending on where the installation is located, there are:

  • built into the building;

    Block-modular;

In the system of each heating, its main element is the boiler. It performs the main function - heating. Depending on the basis on which the entire system and the boiler in particular work, there are the following types of boilers:

    steam boilers

    Water heating;

    mixed;

    Cauldrons for diathermic oil.

Any heating system works, as previously noted, from one or another type raw materials, fuel or natural resource. Depending on this, boilers are divided into:

    Solid fuel. For this, firewood, coal and other types of solid fuels are used.

    Liquid fuel - oil, gasoline, fuel oil and others.

  • Mixed or combined. Intended use various kinds and types of fuel.

Classification of boiler units

Boilers as technical devices for the production of steam or hot water are distinguished by a variety of design forms, operating principles, fuels used and performance indicators. At the same time, according to the method of organizing the movement of water and steam-water mixture, all boilers can be divided into the following two groups:

Boilers with natural circulation;

Boilers with forced movement of the coolant (water, steam-water mixture).

In modern heating and heating-industrial boiler houses for the production of steam, boilers with natural circulation are mainly used, and for the production of hot water - boilers with forced movement of the coolant, operating on the direct-flow principle.

Modern steam boilers with natural circulation are made of vertical pipes located between two collectors (drums). One part of the pipes, called heated "lifting pipes", is heated by a torch and combustion products, and the other, usually not heated part of the pipes, is located outside the boiler unit and is called "down pipes". In heated riser pipes, water is heated to a boil, partially evaporates and enters the boiler drum in the form of a steam-water mixture, where it is separated into steam and water. Through downcomer unheated pipes, water from the upper drum enters the lower collector (drum).

The movement of the coolant in boilers with natural circulation is carried out due to the driving pressure created by the difference in the weights of the water column in the downcomer and the column of the steam-water mixture in the riser pipes.

In steam boilers with multiple forced circulation, the heating surfaces are made in the form of coils that form circulation circuits. The movement of water and steam-water mixture in such circuits is carried out using a circulation pump.

In once-through steam boilers, the circulation ratio is one, i.e. feed water, heating up, successively turns into a steam-water mixture, saturated and superheated steam. In hot water boilers, when moving along the circulation circuit, water is heated in one revolution from the initial to the final temperature.

According to the type of heat carrier, boilers are divided into water-heating and steam boilers. The main indicators of a hot water boiler are thermal power, i.e. heat output and water temperature; The main indicators of a steam boiler are steam output, pressure and temperature.

Hot water boilers, the purpose of which is to obtain hot water of specified parameters, are used for heat supply of heating and ventilation systems, domestic and technological consumers. Hot water boilers, usually operating on a direct-flow principle with a constant flow of water, are installed not only at thermal power plants, but also in district heating, as well as heating and industrial boiler houses as the main source of heat supply.

Steam boiler - an installation designed to generate saturated or superheated steam, as well as to heat water (heating boiler).

According to the relative movement of heat exchange media (flue gases, water and steam), steam boilers (steam generators) can be divided into two groups: water-tube boilers and fire-tube boilers. In water-tube steam generators, water and a steam-water mixture move inside the pipes, and the flue gases wash the pipes from the outside. In Russia in the 20th century, Shukhov's water-tube boilers were predominantly used. In fire tubes, on the contrary, flue gases move inside the pipes, and water washes the pipes from the outside.

According to the principle of movement of water and steam-water mixture, steam generators are divided into units with natural circulation and forced circulation. The latter are subdivided into direct-flow and with multiple-forced circulation.

As a feed pump, a three-plunger pump is usually used. high pressure P21/23-130D or P30/43-130D series.

Boilers over critical pressure (SKP) - steam pressure over 22.4MPa.

The main elements of steam and hot water boilers

Furnaces for combustion of gaseous, liquid and solid fuels. When burning gas and fuel oil, as well as solid pulverized coal, as a rule, chamber furnaces are used. The furnace is limited by the front, rear, side walls, as well as the hearth and vault. Evaporative heating surfaces (boiler pipes) with a diameter of 50...80 mm are located along the walls of the furnace, perceiving the radiated heat from the torch and combustion products. When burning gaseous or liquid fuels under the chamber furnace, they usually do not shield, and in the case of coal dust, a “cold” funnel is made in the lower part of the combustion chamber to remove the ash falling from the burning torch.

The upper ends of the pipes are rolled into a drum, and the lower ends are connected to the collectors by rolling or welding. In a number of boilers, the boiling pipes of the rear screen, before being connected to the drum, are bred in the upper part of the furnace in several rows, arranged in a checkerboard pattern and forming a scallop.

To service the furnace and gas ducts in the boiler unit, the following headset is used: manholes, lockable doors, peepers, explosive valves, gates, rotary dampers, blowers, shot cleaning.

Closable doors, manholes in brickwork are designed for inspection and repair work when the boiler is stopped. To monitor the process of fuel combustion in the furnace and the state of convective gas ducts, peepers are used. Explosive safety valves are used to protect the lining from destruction during pops in the furnace and boiler flues and are installed in the upper parts of the furnace, the last gas flue of the unit, the economizer and in the roof.

To regulate the draft and overlap the hog, cast-iron smoke dampers or rotary dampers are used.

When working on gaseous fuels, in order to prevent the accumulation of combustible gases in the furnaces, chimneys and flues of the boiler installation during a break in work, a small draft must always be maintained in them; To do this, each separate flue of the boiler to the combined flue must have its own gate valve with a hole in the upper part with a diameter of at least 50 mm.

Blowers and shot cleaners are designed to clean heating surfaces from ash and soot.

Steam boiler drums. It should be noted the multi-purpose purpose of the drums of steam boilers, in particular, the following processes are carried out in them:

Separation of the steam-water mixture coming from the lifting heated pipes into steam and water and steam collection;

Feed water intake from the water economizer or directly from the feed line;

Intra-boiler water treatment (thermal and chemical water softening);

Continuous purge;

Drying of steam from droplets of boiler water;

Washing steam from salts dissolved in it;

Steam pressure protection.

Boiler drums are made of boiler steel with stamped bottoms and a manhole. The inner part of the volume of the drum, filled to a certain level with water, is called the water volume, and filled with steam during the operation of the boiler - the steam volume. The surface of boiling water in the drum, which separates the water volume from the steam volume, is called the evaporation mirror. In a steam boiler, only that part of the drum that is cooled by water from the inside is washed by hot gases. The line separating the surface heated by gases from the unheated one is called the firing line.

The steam-water mixture enters through lifting boiler pipes rolled into the bottom of the drum. From the drum, water is fed through downpipes to the lower collectors.

Emissions, ridges and even fountains occur on the surface of the evaporation mirror, while a significant amount of boiler water droplets can get into the steam, which reduces the quality of the steam as a result of an increase in its salinity. Drops of boiler water evaporate, and the salts contained in them are deposited on the inner surface of the superheater, impairing heat transfer, as a result of which the temperature of its walls rises, which can lead to their burnout. Salts can also be deposited in the fittings of the steam lines and lead to a violation of its tightness.

Various separation devices are used to uniformly supply steam to the steam space of the drum and reduce its moisture content.

To reduce the possibility of scale deposits on the evaporative heating surfaces, intra-boiler water treatment is used: phosphating, alkalizing, the use of complexing agents.

Phosphating aims to create conditions in the boiler water under which the scale formers are separated in the form of non-stick sludge. To do this, it is necessary to maintain a certain alkalinity of the boiler water.

In contrast to phosphating, water treatment with complexones can provide scale-free and sludge-free regimes of boiler water. It is recommended to use Trilon B sodium salt as a complexing agent.

Maintaining the permissible salt content in the boiler water is carried out by blowing the boiler, i.e. removing from it some part of the boiler water, which always has a higher concentration of salts than the feed water.

For the implementation of the staged evaporation of water, the boiler drum is divided by a partition into several compartments with independent circulation circuits. Feed water enters one of the compartments, called "clean". Passing through the circulation circuit, the water evaporates, and the salinity of the boiler water in the clean compartment rises to a certain level. To maintain the salinity in this compartment, part of the boiler water from the clean compartment is directed by gravity through a special hole - a diffuser in the lower part of the partition into another compartment, called "salt", since the salt content in it is significantly higher than in the clean compartment.

Continuous purging of water is carried out from a place with the highest concentration of salts, i.e. from the salt compartment. The steam generated in both evaporation stages is mixed in the steam space and exits the drum through a series of tubes located at the top of the drum.

With an increase in pressure, steam is able to dissolve some impurities in the boiler water (silicic acid, metal oxides).

To reduce the salinity of steam, some boilers use steam flushing with feed water.

Boiler superheaters. Obtaining superheated steam from dry saturated steam is carried out in a superheater. The superheater is one of the most critical elements of the boiler unit, since of all heating surfaces it operates under the most severe temperature conditions (overheating temperature up to 425 ° C). The superheater coils and headers are made of carbon steel.

According to the method of heat absorption, superheaters are divided into convective, radiation-convective and radiation. In boiler units of low and medium pressure, convective superheaters with vertical or horizontal pipes are used. To obtain steam with a superheat temperature of more than 500 °C, combined superheaters are used, i.e. in them, one part of the surface (radiation) perceives heat due to radiation, and the other part - by convection. The radiation part of the heating surface of the superheater is located in the form of screens directly in the upper part of the combustion chamber.

Depending on the directions of movement of gases and steam, there are three main schemes for including a superheater in a gas flow: direct-flow, in which gases and steam move in the same direction; countercurrent, where gases and steam move in opposite directions; mixed, in which in one part of the coils of the superheater gases and steam move in direct flow, and in the other - in opposite directions.

Optimal in terms of reliability of operation is a mixed scheme for switching on a superheater, in which the first part of the superheater along the steam flow is counterflow, and the completion of steam superheating occurs in its second part with direct flow of heat carriers. At the same time, in the part of the coils located in the region of the highest heat load of the superheater, at the beginning of the flue there will be a moderate steam temperature, and the completion of steam superheating occurs at a lower heat load.

Steam temperature in boilers with pressure up to 2.4 MPa is not regulated. At a pressure of 3.9 MPa and above, the temperature is controlled in the following ways: by injection of condensate into steam; using surface desuperheaters; using gas control by changing the flow rate of combustion products through the superheater or moving the position of the flame in the furnace using rotary burners.

The superheater must have a pressure gauge, a safety valve, a shut-off valve to disconnect the superheater from the steam line, and a device for measuring the temperature of the superheated steam.

Water economizers. In the economizer, feed water is heated by flue gases before being fed into the boiler by using the heat of the fuel combustion products. Along with preheating, partial evaporation of the feed water entering the boiler drum is possible. Depending on the temperature to which water is heated, economizers are divided into two types - non-boiling and boiling. In non-boiling economizers, according to the conditions of their reliability, water is heated to a temperature of 20 ° C below the temperature of saturated steam in a steam boiler or the boiling point of water at the existing operating pressure in a hot water boiler. In boiling economizers, not only water is heated, but also partial (up to 15 May.%) its evaporation.

Depending on the metal from which the economizers are made, they are divided into cast iron and steel. Cast iron economizers are used at a pressure in the boiler drum of not more than 2.4 MPa, while steel economizers can be used at any pressure. In cast iron economizers, boiling water is unacceptable, as this leads to hydraulic shocks and destruction of the economizer. To clean the heating surface, water economizers have blowers.

Air heaters. In modern boiler units, the air heater plays a very significant role, taking heat from the exhaust gases and transferring it to air, it reduces the most noticeable heat loss item with the exhaust gases. When using heated air, the combustion temperature of the fuel rises, the combustion process intensifies, and the efficiency of the boiler unit increases. At the same time, when installing an air heater, the aerodynamic resistances of the air and smoke paths increase, which are overcome by creating artificial draft, i.e. by installing a smoke exhauster and a fan.

The air heating temperature is selected depending on the combustion method and type of fuel. For natural gas and fuel oil burned in chamber furnaces, the temperature of hot air is 200...250°C, and for pulverized coal combustion of solid fuel - 300...420°C.

If the boiler unit has an economizer and an air heater, the economizer is installed first along the gas flow, and the air heater is installed second, which allows for deeper cooling of the combustion products, since the cold air temperature is lower than the temperature of the feed water at the economizer inlet.

According to the principle of operation, air heaters are divided into recuperative and regenerative. In a recuperative air heater, the transfer of heat from combustion products to air occurs continuously through a separating wall, on one side of which the combustion products move, and on the other - heated air.

In regenerative air heaters, the transfer of heat from the combustion products to the heated air is carried out by alternately heating and cooling the same heating surface.

Gas installations. The gas piston unit (GPU) is designed to supply electricity to three-phase consumers (380/220 V, 50 Hz) alternating current. Gas power plants are used as a source of constant and guaranteed power supply for hospitals, banks, shopping malls, airports, industrial and oil and gas producing enterprises. The motor resource of a gas engine is higher than that of gasoline generators and diesel power plants, which leads to a decrease in the payback period. The use of gas-fired power generators allows the owner to be independent from planned and emergency power outages, and often completely refuse the services of electricity suppliers.

The operation of gas piston engines (hereinafter referred to as GPE) is based on the principle of operation of an internal combustion engine. An internal combustion engine is a type of engine, a heat engine in which the chemical energy of a fuel (usually liquid or gaseous hydrocarbon fuels) that burns in the working area is converted into mechanical work.

At the moment, two types of piston engines operating on gas are produced in industry: gas engines - with electric (spark) ignition, and gas diesel engines - with ignition of the gas-air mixture by injection of pilot (liquid) fuel. Gas engines have become widespread in the energy sector due to the widespread trend to use gas as a cheaper fuel (both natural and alternative) and relatively more environmentally friendly in terms of exhaust emissions.

From GPU with heat exchangers, in principle, everything is similar, but a heat recovery system is additionally used.

The unit runs on multiple fuels, has a relatively low initial investment per kW, and has a wide range of power outputs.

Fuel for gas-piston installations. One of the most important points in choosing the type of gas turbine is the study of the composition of the fuel. Manufacturers of gas engines have their own requirements for the quality and composition of the fuel for each model.

Currently, many manufacturers are adapting their engines to the appropriate fuel, which in most cases does not take much time and does not require large financial costs.

In addition to natural gas, gas piston units can use as fuel: propane, butane, associated petroleum gas, chemical industry gases, coke oven gas, wood gas, pyrolysis gas, landfill gas, sewage gas, etc.

The use of these specific gases as fuel makes an important contribution to the conservation environment and furthermore allows the use of regenerative energy sources.

Gas control station. Gas control point - a system of devices for automatically reducing and maintaining a constant gas pressure in gas distribution pipelines. The gas control station includes a pressure regulator for maintaining gas pressure, a filter for trapping mechanical impurities, safety valves that prevent gas from entering distribution gas pipelines in case of emergency gas pressure in excess of permissible parameters, and instrumentation for accounting for the amount of passing gas, temperature, pressure and telemetric measurement these settings.

Gas control points are built on urban gas distribution pipelines, as well as on the territory of industrial and municipal enterprises with an extensive network of gas pipelines. Items mounted directly at consumers and designed to supply gas to boilers, furnaces, and other units are usually called gas control devices. Depending on the gas pressure at the inlet, gas control points are: medium (from 0.05 to 3 kgf / cm 2) and high (up to 12 kgf / cm 2) pressure (1 kgf / cm 2 \u003d 0.1 Mn / m 2).

Safety devices and instrumentation. For hot water boilers, bypass lines with check valves(fig.), passing water in the direction from the boiler to the pipeline of the heating system. With such a simple device, if the valves installed at the boiler for some reason turn out to be closed, then all the same, the connection with the atmosphere through the expansion vessel will not be broken.

If there are any other shut-off valves on the pipeline between the boilers and the expansion vessel, in addition to the valves indicated, then lever safety valves must be installed.

Steam boilers up to 70 kPa are equipped with a safety device in the form of a hydraulic seal

For safe and proper operation, steam boilers, in addition to safety devices, are equipped with water-indicating devices, plug valves and pressure gauges.

To account for the consumption of feed water supplied to the steam boiler, or water circulating in the water heating system, a water meter or diaphragms are installed. To measure the temperature of the water entering the water heating system and returning to the boiler, thermometers are provided in special cases.

Development of an optimal technical solution for the manufacture of a boiler house, taking into account all specifications provided by the Customer

  • Supply of boiler houses

    Production, delivery and installation of a boiler room on site

  • Maintenance of boiler rooms

    The complex is technologically related works I service your boiler room

    • About company

    Since the summer of 2004, our company has been producing modular boiler plants of the COMPACT container type. Boiler houses COMPACT with a heat output from 100 kW to 20,000 kW are designed for heating and hot water supply of residential, industrial and public facilities, as well as for providing hot water or steam technological needs of various industries

    What are the boiler rooms

    The energy industry requires the use of various types of boilers, classified according to various criteria: the type of fuel used and the coolant, the location, the principle of mechanization or automation, the goals and requirements of customers.

    Types of boiler houses by type of fuel:

    • gas boilers, their main advantage is efficiency and environmental friendliness. They do not require complex large-sized equipment and can work offline;
    • liquid fuel boilers - operate on fuel oil, oil, diesel fuel and waste oil, quickly put into operation and do not require permits for their use, connection and are not limited by fuel volumes;
    • solid fuel boilers - work on wood, peat, waste from the timber industry, coal. Their "trick" lies in the low cost of fuel and availability, but they require the installation of fuel supply systems and systems for removing ash and slag.

    Types of boiler rooms depending on the coolant:

    • hot water- boiler houses used in hot water supply and heating systems for residential and non-residential buildings. As a heat carrier, water is used, heated to a maximum of +95 ... + 110 ° С;
    • steam- steam is used as a coolant, and most often such boiler houses are equipped in industries;
    • combined- they use boilers of both types, moreover, hot water covers the load for ventilation and heating needs and water supply, and steam is used for technological processes;
    • oily– diathermic oil and other organic liquids heated up to +300°C are used as a heat carrier.

    Types of boiler rooms depending on their location

    1. Block-modular systems have a number of advantages compared to stationary boilers. They are characterized by quick installation and commissioning, the possibility of increasing capacity due to the addition of modular units and autonomy, high coefficient and mobility. They can be attached to the wall, built into it, placed on the roof and in the basement, stand separately from each other.
    2. Stationary boiler houses are used when a power of 30 MW or more is required or when it is impossible to build a block-modular system. They are capital, solid and require installation at the work site.

    Types of boiler houses according to the degree of mechanization or automation of work processes:

    • automated- fully automated and require little or no human intervention;
    • mechanized- equipped with mechanized elements - conveyor belts, coal crushers, chip catchers, etc., which greatly facilitates the work of the operator;
    • manual- equipped with manual fuel supply modules (trolley or hopper with an external loading system), ash and slag removal is also carried out manually.

    BOILER INSTALLATIONS.

    Steam is widely used in various industries, including factories, food processing plants. Steam production is one of the most developed industries. Steam is used for power generation, heating, ventilation of industrial enterprises and other needs. Steam is obtained in special devices - boiler plants.

    A boiler plant is a set of various devices and devices designed to obtain steam of specified parameters due to the chemical energy of the fuel.

    The working fluids in boiler plants are: fuel, oxidizer (air oxygen), water. In boiler plants, the chemical energy of the fuel is converted into the physical heat of the combustion products, which is transferred to water through the metal heating surfaces to generate steam, to overheat it, i.e. the following processes take place in boiler plants: 1) fuel combustion, 2) heat exchange between combustion products, water and steam, 3) the process of vaporization, consisting of water heating, its evaporation and steam overheating.

    Boiler plants are classified: by purpose, by steam capacity, by the parameters of the generated steam.

    According to the purpose, boiler plants are divided into energy, production and heating and mixed types.

    According to the steam capacity, boiler plants are divided into: low power plants (0.7 ÷ 5.5 kg / s) or (2 ÷ 20 t / h); medium power (up to 20 kg/s or up to 75 t/h) and high power (over 30 kg/s or 100 t/h).

    According to the parameters of the generated steam, the installations are: low pressure(up to 1.4 MPa), medium pressure (up to 4.0 MPa) and high pressure (up to 10.0 MPa).

    Superheated steam is produced in power boiler houses, which is used in steam turbine shops of thermal power plants.

    Production and heating boiler plants serve manufacturing enterprises, supplying them with steam for heating and ventilation, and for technological devices.

    Mixed-type boiler plants are designed to generate steam, both for the production of electricity and for technological purposes of production and heating.

    All major modern factories and food industry factories, as a rule, have their own boiler plants.

    According to the nature of heat consumption, food industry enterprises can be divided into three large groups.

    I. Enterprises using steam to generate electricity (in turbine generators) for technological needs, heating, ventilation of buildings. The enterprises of the first group are usually located at the places where raw materials are received. There is no external power supply to them, and therefore they have their own thermal installations equipped with mixed-type boiler plants. The first group includes sugar factories, distilleries, canning factories, etc.

    II. The second group of enterprises includes enterprises that use steam only for technological and heating needs. This largest group of enterprises includes bakery, pasta, confectionery, and dairy industries. The enterprises are located in cities and urban-type settlements and have production and heating boiler houses.

    With the development of large thermal power plants, there is a tendency for enterprises to switch to external heat supply from CHPPs.

    III. The third group of enterprises includes enterprises using mainly hot water as a heat carrier (tobacco factories, etc.).

    2.1. Elements of the boiler plant.

    The main device of the boiler plant is the boiler unit and a number of auxiliary equipment. There are several boiler units in the boiler room. A modern boiler unit is a complex device. It consists of a furnace, a steam generator, usually called a steam boiler, a superheater, a water economizer, an air heater, lining, a frame, fittings, and so on. To auxiliary equipment boiler plant includes devices and mechanisms designed for the preparation and transportation of fuel and water, draft devices, ash collectors, a headset, thermal control devices and automatic regulation.

    Fuel supply - mechanized devices for the preparation and supply of fuel in boilers.

    Water treatment plant - a system of various devices that provide water purification from all kinds of impurities and scale-forming salts, as well as water deaeration.

    The feed plant includes a tank and pumps for supplying feed water to the boiler unit.

    The blower installation consists of an air duct and a blower fan that supplies air to the furnace.

    The traction plant is used to remove flue gases from the boiler unit and consists of a smoke exhauster and a chimney.

    Figure 1 shows a diagram of the boiler unit

    Ash collecting device - designed to remove ash and slag from the boiler room. Control and measuring equipment ensures safety and uninterrupted work on the development of a pair of specified parameters.

    The furnace is used to burn fuel. Furnaces are classified as layer, chamber, cyclone.

    Steam generator (steam boiler) - is a closed metal heat exchanger, which serves to convert the water entering it into steam with a pressure above atmospheric. Boilers come in a variety of designs.

    On fig. 1 steam generator (boiler) consists of a drum, a screen and downpipes, collectors, a convective heating surface.

    Superheaters are designed to superheat the steam produced by the boiler. They are made in the form of coils from seamless pipes. In the gas ducts of the boiler, they are placed horizontally or vertically.

    Economizers are used to heat feed water before it enters the evaporative part of the boiler. They are divided into boiling and non-boiling. Economizers are a system of cast iron or steel pipes, smooth or ribbed, inside which water circulates. Outside, the pipes are heated by flue gases leaving the boiler.

    Air heaters are designed to heat the air supplied to the furnace for fuel combustion, and in case of pulverized combustion, also to dry the fuel in mills. The most widely used tubular air heaters. The air moves inside the pipes, and outside the pipes are washed by hot gases. When air is heated up to 300 ° C, single-stage heaters are installed, and when more high temperatures- two-stage.

    Brickwork is the external and internal brick walls of the boiler. It is made of red brick (construction).

    The lining is made with refractory bricks.

    Frame - a metal structure that serves as a support for the elements of the boiler unit.

    Armature ensures safe operation. It includes: safety valves(2 pcs.), supply shut-off valve (2 pcs.), pressure gauges (1 pc.), water gauge glasses (2 pcs.), steam intake valve and others.

    The main requirements for boiler plants include reliability and durability of operation at the given parameters, operational safety, easy adjustability, low cost generated steam and manufacture of the boiler unit.

    2.1..Fireboxes.

    A combustion device or furnace is both a fuel-burning and heat-exchange device that absorbs up to 50% of the heat released in the furnace and transferred by radiation to the heating surface.

    There are three main ways of burning fuel: in a layer, a torch and a whirlwind (cyclone). In accordance with this, fireboxes are classified as layered and chambered.

    Combustion of lumpy fuel in a layer on grates is called layered combustion, respectively, furnaces are called layered.

    The combustion of fuel in suspension (in the form of finely divided solid fuel, gas, liquid fuel) is called flare, and the furnaces are called chamber. Combustion of finely divided fuel in a strong tangential swollen air flow is called swirling combustion. Type of such furnaces are cyclone chamber furnaces.

    Layer fireboxes.

    According to the degree of mechanization, layer furnaces are divided into furnaces with manual maintenance, semi-mechanized, fully mechanized furnaces.

    With manual maintenance, the loading of fuel onto the grate, the skimming of fuel and the unloading of ash and slag is carried out manually.

    In semi-mechanized furnaces, any of the above operations is mechanized.

    In fully mechanized furnaces, all fuel combustion operations are mechanized. Fireboxes with manual operation are common in low power plants (0.5 ÷ 2 t/h). In installations of medium power, they find very rare use. In installations of medium and high power, semi-mechanized and fully mechanized furnaces are common.

    Chamber furnaces for burning coal dust, gas and fuel oil.

    Finely divided coal dust with primary air is supplied by a fan to the burner, where it is also fed hot air for complete combustion of the fuel.

    The combustion of coal dust in the furnace is carried out in a suspended state in a torch. The fuel ash is partially deposited in the ash bin and removed from it. Some of the ash is captured in cyclones installed in front of the chimney. The main part of the ash 80% is released into the atmosphere together with flue gases.

    Instead of pulverized coal burners, chamber furnaces can be equipped with gas combustion gas burners, and when burning fuel oil - with fuel oil nozzles. In addition, chamber furnaces for burning gas and fuel oil, unlike pulverized coal furnaces, do not have an ash bin and ash collectors.

    Thermal characteristics furnaces.

    The operation of combustion devices is characterized the following indicators:

    Specific thermal power of the combustion mirror (an indicator characterizing the operation of a layered furnace):

    kW/m2 (13)

    where: В – fuel consumption, kg/s

    Lower calorific value of fuel, kJ/kg

    R is the area of ​​the combustion mirror, that is, the surface of the burning fuel visible from above, m.

    Numerically, R is considered equal to the area of ​​the grate, because R=F.

    Optimal values The thermal stresses of the combustion mirror depend on the type of furnace and the characteristics of the fuel. They fluctuate between 800 - 2000 kW / m. With an increase in the value of q R in comparison with this nominal value, the heat loss (q 4) from mechanical incomplete combustion increases.

    The second characteristic is the specific thermal power of the furnace space

    , kW/m 3 (14)

    where is the volume of the combustion chamber, m. - lower calorific value of gaseous fuel kJ/m 3 .

    This value characterizes the operation of the chamber furnace.

    Sufficient volume of the combustion chamber and its sufficient height provide efficient combustion volatile substances released from the fuel. The values ​​of thermal stresses of the combustion chamber range from 140 to 500 kW/m. With an increase in this value, heat losses increase (q 3) from chemical incompleteness of combustion and (q 4) from mechanical incompleteness of combustion.

    The quantities q R and q v are important indicators necessary for calculating the dimensions of the furnaces.

    For all types of furnaces (layer and chamber), which determine their economy and work efficiency, the efficiency of the furnace is:

    % (15)

    where: q 3 - losses from chemical incompleteness of combustion,%,

    q 4 - losses from mechanical incompleteness of combustion,%.

    How better process combustion, the smaller q 3 and q 4 , the more perfect the firebox.

    The efficiency of chamber furnaces is higher than that of layer furnaces, since they have a smaller q 4 value.

    The last indicator that determines the operation of the furnaces is the coefficient of excess air in the furnace:

    where: - theoretical amount of air required for complete combustion of fuel, m / kg;

    The actual amount of air entering the furnace, m / kg.

    The value depends on the type of fuel burned and the type of combustion device.

    STEAM BOILERS.

    In modern boiler units, the actual steam boiler is understood as the whole set of elements (drums, screens, festoons, screens, boiler pipes) designed to form and collect saturated water vapor.

    The drum is filled to a certain level with water forming a water space. In the upper part (steam space) of the drum, the resulting moist saturated steam is collected. Separation devices are placed in the steam space of the drum, which serve to separate water and steam. With saturated steam leaving the boiler drum, some moisture is carried away in the form of small droplets of boiler water. The salts contained in these droplets, after evaporation of the droplets in the superheater, are deposited on the inner surface of the coils, as a result of which the heat transfer deteriorates in them and an undesirable increase in the temperature of the superheater tubes occurs. Salts can also be deposited in the fittings of steam pipelines, which can lead to a violation of its density, and once in the flow path of a steam turbine, salts reduce the efficiency of its operation.

    Complications caused by entrainment of boiler water require the reduction of moisture and salinity of the steam leaving the drums. Steam moisture reduction is achieved by installing special separators designed to separate water droplets from steam. Separator designs are built on the use of various mechanical factors of gravity, inertia, film effect and others.

    Inertial separation is carried out by creating sharp turns in the flow of the steam mixture entering the boiler drum from screen or boiler pipes (baffle shields, cyclones).

    Film separation is based on the fact that when wet steam hits a solid moistened surface, the smallest particles of moisture contained in the steam adhere to this surface, forming a continuous water film on it.

    Steam boilers are made as single-drum and double-drum.

    Screen pipes placed in the furnace space serve to heat and evaporate water mainly due to the absorption of radiant energy.

    The front, less heated screen pipes are downpipes of the natural circulation of water and steam-water mixture, and since the density of water in them is greater than in the more heated rear pipes, which are lifting. The boiler pipes, washed from the outside with hot flue gases, form a developed convective (evaporative ) boiler heating surface. The last rows of boiler pipes along the course of gases are downcomers. The flue gases between the boiler tube bundles can move vertically or in a horizontal-transverse direction with several turns (DE boilers).

    Circulation is understood as the process of repeated circulation of evaporated water in screens and boiler tubes of drum boilers. It can be carried out under the action of gravitational forces (due to the difference in the density of water and steam-water emulsion). This is the so-called natural circulation. But it can also be carried out forcibly, under the action of a special circulation pump (multiple forced circulation).

    There is no circulation circuit in once-through boilers. Complete evaporation of water in the evaporative heating surface occurs during a single, direct-flow passage of water in it (under the action of a feed pump).

    The ratio of the amount of water entering the evaporator system to the amount of steam that is produced during the same time by this system is called the circulation ratio. For boilers with natural circulation, the circulation ratio varies within m=8÷50 and more. In boilers with multiple forced circulation m=5÷10. In once-through boilers m=1.

    The main type of boiler units are vertical water tube boilers. Structurally, they are performed without drums, two-drum and one-drum.

    Drumless cylindrical vertical water tube boilers are produced with a steam capacity from 0.2 to 10 t/h for the production of wet saturated steam with a pressure of 0.88 MPa (9 atm). These boilers are installed in small businesses (bakery, confectionery).

    Double-drum vertical water-tube boilers are produced from 0.4 to 50 t/h for the production of low and medium pressure wet saturated or superheated steam. This boiler consists of two horizontal drums (upper and lower) located on the same vertical axis. The walls of the combustion chamber are covered with pipes. The upper ends of the pipes are rolled into the upper drum, and the lower ends into collectors. The collector is also connected by an unheated downpipe to the upper drum, moreover, the pipe is immured in a lining.

    The pipes covering the walls of the combustion chambers are called screens or the screen heating surface of the boiler.

    The pipes located in the gas ducts of the boiler and washed by the longitudinal or transverse flow of flue gases, which give off their heat to the water circulating through the pipes by convection, constitute the convective heating surface.

    The boiler is fed through the upper drum through the feed pipes. Boiler blowdown is used to maintain normal salinity. Purge is continuous and intermittent. Continuous blowing is carried out from the upper drum, from which water is continuously removed in the amount of 3÷5% of the boiler steam capacity. Periodic purging is carried out from the lower boiler once per shift and serves to remove sludge (dirt) from the boiler. When a solid fuel boiler is operating, ash is deposited on convective pipes. Ash is removed from the pipes using a blower pipe connected to the steam space of the drum.

    In the food industry, double-drum vertical water-tube boilers of the DE type (2.5; 4; 6.5; 10; 20 t / h) with a pressure of 1.4 MPa, manufactured by the Biysk boiler plant, are widely used. Other brands of double-drum vertical water-tube boilers: E-0.4/9t, E-1/9-1 G.M, GM 50-14, DE-25-2.4GM, E-1/9 g.m. steam capacity 1000 kg/h, operating pressure 0.9 MPa, fuel - gas, fuel oil.

    Single-drum vertical water-tube boilers with a steam capacity of 50 t/h and above, designed for the production of superheated steam of medium and high pressure, are made with highly developed screen heating surfaces, a chamber furnace and with an arrangement of elements in the form of the letter P. They operate with natural circulation water, solid pulverized, liquid and gaseous fuels are burned in their furnaces. In these boilers, the screening of the furnace is so significant that there is no need for developed boiling convective heating surfaces (therefore, these boilers are sometimes called screen boilers). convective surfaces heating in boilers of this type, only the superheater, water economizer and air heater remain. Single-drum boilers with a capacity of up to 75 t/h BKZ-75-3.9, GM are installed at sugar refineries. In addition to boilers with natural circulation, there are boilers with forced circulation. In boilers of this type, the movement of water and steam-water mixture in the boiler pipes is carried out due to the pressure created by the feed pump. The most widespread boilers with forced circulation are Ramzin L.K. boilers. so-called once-through boilers.

    Once-through boilers do not have drums, they consist of only pipes, and steam is produced in them in one pass of water through the pipes.

    Once-through boilers are made in the form of powerful boiler units and are designed to produce ultra-high pressure and high temperature steam.

    WATER TREATMENT.

    The condensate returning from the turbine condensers, process equipment heat exchangers and softened make-up water are used as boiler feed water. Natural (raw) water used as make-up water for boiler feed always contains suspended and dissolved solids, and dissolved gases. The main indicators characterizing the quality of water are: the content of suspended solids, dry residue, salt content, water hardness, alkalinity, the content of corrosive gases O 2 and CO 2 (in mg/kg). The content of suspended solids determines the contamination of water with solid insoluble impurities (sand, clay) and expressed in milligrams per kg.

    Dry residue is an indicator characterizing colloidal and dissolved inorganic and organic impurities in water (in mg / kg).

    Total water hardness W 0 - the total concentration of calcium and magnesium ions in solution, expressed in equivalent units, is measured in mg - eq / kg.

    The total alkalinity of water is Shch 0 - expressed in mg - eq / kg, the total concentration of OH anions contained in water - (Hydroxy ions) (bicarbonate ions), - (carbonate ions), (phosphate ions). In natural waters, of the listed ions, as a rule, bicarbonate ions are present in appreciable amounts. Suspended and dissolved solids contained in raw water, as well as dissolved corrosive gases, make it unsuitable for supply to boilers, since if there are solid mineral impurities in the water, the boiler unit quickly overgrows with scale and becomes clogged with slag, and corrosive gases cause corrosion of metal surfaces. Therefore, make-up water is purified from coarse colloidal impurities and scale-forming salts, as well as from dissolved air. Removal of coarse impurities from water is achieved by clarification e by settling and filtering.

    Inlet clarification by filtration consists in passing water through filters loaded with granular filter material (crushed anthracite, marble chips, quartz sand), which retains coarse impurities due to their small size.

    Colloidal impurities in water are removed by introducing water coagulants (aluminum and iron sulfates). As a result, colloidal impurities turn into coarse flakes, which are then separated from the water by settling or filtration.

    To reduce hardness and alkalinity, water is subjected to pretreatment precipitation method. At the same time, they are treated with lime or other reagents, as a result of which sparingly soluble calcium and magnesium compounds are released (precipitated) in the water, which are separated from the softened water by clarification.

    Currently, the most complete softening of natural water is achieved by ion exchange. With this method, the water to be softened is passed through a layer of special granular materials - ions that absorb cations (Mg, Ca) of scale-forming substances from the water, and ions of substances that do not violate the water regime of the boilers enter in an equivalent amount. This so-called chemical cleaning water in cationic filters.

    In these filters, filled to 3/4 of their volume with sulphugol (cation exchanger), the reaction of replacing calcium Ca 2+ and magnesium Mg 2+ cations contained in water with sodium cations (Na - cationization) proceeds.

    The release of water from the corrosive gases dissolved in it is carried out in deaerators. Deaeration of all water circulating in the cycle is carried out thermally.

    Maintaining the water regime of steam boilers.

    Even with the most thorough treatment of make-up water, it is not possible to remove all dissolved minerals from it. Getting into the boiler, these residual impurities gradually accumulate in the boiler water, since in the process of water evaporation they almost do not turn into steam. With the onset of the saturation state, an excess amount of impurities precipitates from the solution in the form of crystals.

    Substances that crystallize directly on the heating surface form scale.

    Substances that crystallize in the volume of boiler water (around suspended colloidal particles) form suspended particles called sludge. In this regard, the operation of a (drum) steam boiler should be carried out so that the concentration of scale-forming salts in the boiler water is below the critical concentration at which they begin to fall out of solution. To do this, they resort to blowing the boiler, that is, to draining a certain amount of boiler water from it in order to remove from the boiler together with this water the amount of salts that enters it along with the feed water. Since the salinity of the boiler water is many times higher than the salinity of the feed water, maintaining the permissible salt concentration in the boiler water is achieved by removing blowdown water from the boiler in an amount of only 0.5÷6% of its steam output.

    Purging is carried out due to the pressure difference in the boiler and the device where the purge water is directed (expander). Continuous and periodic blowdown of steam boilers is used.

    Continuous blowing is used to remove impurities soluble in boiler water and in drum boilers is carried out using water sampling pipes located in the drum at the place of their maximum concentration - when the steam-water mixture leaves the boiler pipes near the water level in the upper drum of the boiler (or from remote cyclones). Periodic blowdown is mainly used to remove sludge and is therefore carried out from the lower points of the circulation circuit, where the heavier sludge particles are most likely to settle, i.e. their lower drum and screen collectors.

    A boiler plant (boiler room) is a structure in which the working fluid (heat carrier) (usually water) is heated for a heating or steam supply system, located in one technical room. Boiler rooms are connected to consumers by means of a heating main and/or steam pipelines. The main device of the boiler house is a steam, fire-tube and / or hot water boilers. Boilers are used for centralized heat and steam supply or for local heat supply of buildings.


    A boiler plant is a complex of devices located in special rooms and serving to convert the chemical energy of fuel into thermal energy of steam or hot water. Its main elements are a boiler, a combustion device (furnace), feed and draft devices. In general, a boiler plant is a combination of a boiler (boilers) and equipment, including the following devices: fuel supply and combustion; purification, chemical treatment and deaeration of water; heat exchangers for various purposes; source (raw) water pumps, network or circulation pumps - for circulating water in the heat supply system, make-up pumps - to compensate for water consumed by the consumer and leaks in networks, feed pumps for supplying water to steam boilers, recirculating (mixing); nutritious, condensing tanks, hot water storage tanks; blow fans and air path; smoke exhausters, gas path and chimney; ventilation devices; systems of automatic regulation and safety of fuel combustion; heat shield or control panel.


    A boiler is a heat exchange device in which heat from hot fuel combustion products is transferred to water. As a result, in steam boilers, water is converted into steam, and in hot water boilers it is heated to the required temperature.


    The combustion device serves to burn fuel and convert its chemical energy into heat of heated gases.


    Feeding devices (pumps, injectors) are designed to supply water to the boiler.


    The draft device consists of blowers, a system of gas ducts, smoke exhausters and a chimney, with the help of which the necessary amount of air is supplied to the furnace and the movement of combustion products through the boiler flues, as well as their removal into the atmosphere. Combustion products, moving along the gas ducts and in contact with the heating surface, transfer heat to the water.


    To ensure more economical operation, modern boiler plants have auxiliary elements: a water economizer and an air heater, which serve to heat water and air, respectively; devices for fuel supply and ash removal, for cleaning flue gases and feed water; thermal control devices and automation equipment that ensure the normal and uninterrupted operation of all parts of the boiler room.


    Depending on the use of their heat, boiler houses are divided into energy, heating and production and heating.


    Power boilers supply steam to power plants that generate electricity and are usually part of a power plant complex. Heating and production boiler houses are found in industrial enterprises and provide heat for heating and ventilation systems, hot water supply of buildings and technological production processes. Heating boilers solve the same problems, but serve residential and public buildings. They are divided into separate, interlocked, i.e. adjacent to other buildings, and built into buildings. Recently, more and more often stand-alone enlarged boiler houses are being built with the expectation of serving a group of buildings, a residential quarter, a microdistrict.


    The installation of boiler houses built into residential and public buildings is currently allowed only with appropriate justification and coordination with the sanitary supervision authorities.


    Low-power boiler houses (individual and small group) usually consist of boilers, circulation and make-up pumps and draft devices. Depending on this equipment, the dimensions of the boiler room are mainly determined.

    2. Classification of boiler plants

    Boiler plants, depending on the nature of consumers, are divided into energy, production and heating and heating. According to the type of heat carrier obtained, they are divided into steam (for generating steam) and hot water (for generating hot water).


    Power boiler plants produce steam for steam turbines in thermal power plants. Such boiler houses are equipped, as a rule, with boiler units of large and medium power, which produce steam with increased parameters.


    Industrial heating boiler plants (usually steam) produce steam not only for industrial needs, but also for heating, ventilation and hot water supply.


    Heating boiler plants (mainly water-heating, but they can also be steam) are designed to service heating systems for industrial and residential premises.


    Depending on the scale of heat supply, heating boiler houses are local (individual), group and district.


    Local boiler houses are usually equipped with hot water boilers with water heating up to a temperature of not more than 115 ° C or steam boilers with an operating pressure of up to 70 kPa. Such boiler houses are designed to supply heat to one or more buildings.


    Group boiler plants provide heat to groups of buildings, residential areas or small neighborhoods. They are equipped with both steam and hot water boilers of greater heat output than boilers for local boiler houses. These boiler houses are usually located in specially constructed separate buildings.


    District heating boiler houses are used to supply heat to large residential areas: they are equipped with relatively powerful hot water or steam boilers.



    Rice. one.








    Rice. 2.








    Rice. 3.




    Rice. 4.


    Individual elements It is customary to conditionally show the schematic diagram of a boiler plant in the form of rectangles, circles, etc. and connect them with each other with lines (solid, dotted) denoting a pipeline, steam pipelines, etc. There are significant differences in the schematic diagrams of steam and hot water boiler plants. A steam boiler plant (Fig. 4, a) of two steam boilers 1, equipped with individual water 4 and air 5 economizers, includes a group ash catcher 11, to which the flue gases are supplied along the collecting hog 12. To suck the flue gases in the area between the ash catcher 11 and smoke exhausters 7 with electric motors 8 are installed in the chimney 9. Gates (flaps) 10 are installed for the operation of the boiler room without smoke exhausters.


    Steam from the boilers through separate steam lines 19 enters the common steam line 18 and through it to the consumer 17. Having given off heat, the steam condenses and returns to the boiler room through the condensate line 16 to the collection condensate tank 14. Through the line 15, additional water is supplied to the condensate tank from the water supply or chemical water treatment (to compensate for the volume not returned from consumers).


    In the event that part of the condensate is lost at the consumer, a mixture of condensate and additional water is supplied from the condensate tank by pumps 13 through the supply pipeline 2, first to the economizer 4, and then to the boiler 1. The air necessary for combustion is sucked in by centrifugal draft fans 6 partially from the room boiler room, partly from the outside and through air ducts 3 is supplied first to the air heaters 5, and then to the furnaces of the boilers.


    The hot water boiler plant (Fig. 4, b) consists of two hot water boilers 1, one group water economizer 5 serving both boilers. Flue gases leaving the economizer through a common collection hog 3 enter directly into the chimney 4. The water heated in the boilers enters the common pipeline 8, from where it is supplied to the consumer 7. Having given off heat, the cooled water is first sent through the return pipeline 2 to the economizer 5 and then back to the boilers. Water by closed circuit(boiler, consumer, economizer, boiler) is moved by circulation pumps 6.





    Rice. 5. : 1 - circulation pump; 2 - firebox; 3 - superheater; 4 - upper drum; 5 - water heater; 6 - air heater; 7 - chimney; eight - centrifugal fan(smoke exhauster); 9 - fan for supplying air to the air heater


    On fig. 6 shows a diagram of a boiler unit with a steam boiler having an upper drum 12. A furnace 3 is located in the lower part of the boiler. Nozzles or burners 4 are used to burn liquid or gaseous fuel, through which fuel is supplied to the furnace along with air. The boiler is limited by brick walls - brickwork 7.


    When fuel is burned, the released heat heats the water to a boil in tube screens 2 installed on the inner surface of the furnace 3, and ensures its conversion into water vapor.




    Fig 6.


    Flue gases from the furnace enter the boiler gas ducts, formed by lining and special partitions installed in pipe bundles. When moving, the gases wash the bundles of pipes of the boiler and superheater 11, pass through the economizer 5 and the air heater 6, where they are also cooled due to the transfer of heat to the water entering the boiler and the air supplied to the furnace. Then, the significantly cooled flue gases are removed by means of a smoke exhauster 17 through the chimney 19 into the atmosphere. Flue gases from the boiler can also be discharged without a smoke exhauster under the action of natural draft created by the chimney.


    Water from the source of water supply through the supply pipeline is supplied by pump 16 to the water economizer 5, from where, after heating, it enters the upper drum of the boiler 12. The filling of the boiler drum with water is controlled by the water-indicating glass installed on the drum. In this case, the water evaporates, and the resulting steam is collected in the upper part of the upper drum 12. Then the steam enters the superheater 11, where it is completely dried due to the heat of the flue gases, and its temperature rises.


    From the superheater 11, steam enters the main steam line 13 and from there to the consumer, and after use it condenses and returns in the form of hot water (condensate) back to the boiler room.


    Losses of condensate at the consumer are replenished with water from the water supply system or from other sources of water supply. Before entering the boiler, water is subjected to appropriate treatment.


    The air necessary for fuel combustion is taken, as a rule, from the top of the boiler room and is supplied by the fan 18 to the air heater 6, where it is heated and then sent to the furnace. In boiler houses of small capacity, air heaters are usually absent, and cold air is supplied to the furnace either by a fan or due to rarefaction in the furnace created by a chimney. Boiler plants are equipped with water treatment devices (not shown in the diagram), instrumentation and appropriate automation equipment, which ensures their uninterrupted and reliable operation.





    Rice. 7.


    For correct installation all elements of the boiler room are used wiring diagram, an example of which is shown in Fig. nine.



    Rice. nine.


    Hot water boiler plants are designed to produce hot water used for heating, hot water supply and other purposes.


    To ensure normal operation, boiler rooms with hot water boilers are equipped with the necessary fittings, instrumentation and automation equipment.


    A hot water boiler house has one heat carrier - water, in contrast to a steam boiler house, which has two heat carriers - water and steam. In this regard, in the steam boiler house it is necessary to have separate pipelines for steam and water, as well as tanks for collecting condensate. However, this does not mean that the schemes of hot water boilers are simpler than steam ones. Water-heating and steam boiler plants vary in complexity depending on the type of fuel used, the design of boilers, furnaces, etc. Both a steam and a water-heating boiler plant usually include several boiler units, but not less than two and not more than four to five . All of them are interconnected by common communications - pipelines, gas pipelines, etc.


    The device of boilers of lower power is shown below in paragraph 4 of this topic. To better understand the device and the principles of operation of boilers different power, it is desirable to compare the device of these less powerful boilers with the device of the larger boilers described above, and find in them the main elements that perform the same functions, as well as understand the main reasons for the differences in designs.

    3. Classification of boiler units

    Boilers as technical devices for the production of steam or hot water are diverse constructive forms, principles of operation, types of fuel used and production indicators. But according to the method of organizing the movement of water and steam-water mixture, all boilers can be divided into the following two groups:


    Boilers with natural circulation;


    Boilers with forced movement of the coolant (water, steam-water mixture).


    In modern heating and heating-industrial boiler houses for the production of steam, boilers with natural circulation are mainly used, and for the production of hot water - boilers with forced movement of the coolant, operating on the direct-flow principle.


    Modern natural circulation steam boilers are made from vertical pipes located between two collectors (upper and lower drums). Their device is shown in the drawing in fig. 10, a photograph of the upper and lower drum with pipes connecting them - in fig. 11, and placement in the boiler room - in fig. 12. One part of the pipes, called heated "lifting pipes", is heated by a torch and combustion products of fuel, and the other, usually not heated part of the pipes, is located outside the boiler unit and is called "down pipes". In heated riser pipes, water is heated to a boil, partially evaporates and enters the boiler drum in the form of a steam-water mixture, where it is separated into steam and water. Through downcomer unheated pipes, water from the upper drum enters the lower collector (drum).


    The movement of the coolant in boilers with natural circulation is carried out due to the driving pressure created by the difference in the weights of the water column in the downcomer and the column of the steam-water mixture in the riser pipes.





    Rice. ten.





    Rice. eleven.





    Rice. 12.


    In steam boilers with multiple forced circulation, the heating surfaces are made in the form of coils that form circulation circuits. The movement of water and steam-water mixture in such circuits is carried out using a circulation pump.


    In once-through steam boilers, the circulation ratio is one, i.e. Feed water, heating up, successively turns into a steam-water mixture, saturated and superheated steam.


    In hot water boilers, when moving along the circulation circuit, water is heated in one revolution from the initial to the final temperature.


    According to the type of heat carrier, boilers are divided into water-heating and steam boilers. The main indicators of a hot water boiler are thermal power, that is, heat output, and water temperature; The main indicators of a steam boiler are steam output, pressure and temperature.


    Hot water boilers, the purpose of which is to obtain hot water of specified parameters, are used for heat supply of heating and ventilation systems, domestic and technological consumers. Hot water boilers, usually operating on a once-through principle with a constant water flow, are installed not only at thermal power plants, but also in district heating, as well as heating and industrial boiler houses as the main source of heat supply.





    Rice. thirteen.




    Rice. fourteen.


    According to the relative movement of heat exchange media (flue gases, water and steam), steam boilers (steam generators) can be divided into two groups: water-tube boilers and fire-tube boilers. In water-tube steam generators, water and a steam-water mixture move inside the pipes, and the flue gases wash the pipes from the outside. In Russia in the 20th century, Shukhov's water-tube boilers were predominantly used. In fire tubes, on the contrary, flue gases move inside the pipes, and water washes the pipes from the outside.


    According to the principle of movement of water and steam-water mixture, steam generators are divided into units with natural circulation and forced circulation. The latter are subdivided into direct-flow and with multiple-forced circulation.


    Examples of placement in boiler boilers of different capacities and purposes, as well as other equipment, are shown in fig. 14-16.



    Rice. fifteen.








    Rice. sixteen. Examples of placement of household boilers and other equipment

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