Fire tube boilers. Fire tube steam boilers for industrial boilers

In today's dynamically developing world, saving fuel resources is becoming one of the most important tasks in human life, including in the domestic sphere. Centralized system heating does not always cope with the tasks and has various shortcomings: energy loss, low efficiency, high costs resources. Fire tube boilers are ideal for creating a heating boiler house of small capacity and are the main alternative to outdated heat supply models.

Design and device

The range of fire-tube boilers is extensive, includes different forms and unit power. But according to the principle of the model are significantly different. Fire tube boilers are of two types:

• heat the coolant with steam;
• the coolant circulates in the inner chamber of the boiler and completely fills the space of the unit.

The structure of the steam boiler is horizontal housing, burner, combustion chamber and three-way flame tubes. The principle of operation is as follows: fuel enters the burner and burns, combustible gases move along three convolutions of the flame tubes, around which there is water. The heat from the pipes leads to the boiling of water and the formation of steam, then part of the steam condenses in the boiler, and part goes to heating.

The hot water fire tube boiler has housing, exhaust pipe, combustion chamber, flame tube. The water is heated by contact with the hot flame tube and transferred to the heating system.

The installation of fire-tube installations and the diagnosis of work are carried out by specialists, it is necessary to comply with the requirements of SNiP. For the operation of the boiler and compliance technical standards no need for constant supervision, many processes occur automatically (outlet temperature control, system pressure).

Carrying out technical calculations of fire-tube units

Before installing a fire-tube boiler, specialists carry out a lot of technical calculations based on the intended purpose, equipment model, fuel used, climatic and other operating conditions, and other parameters.

Read also: The principle of operation of the condensing boiler

The main types of technical calculations are:

• calculation of service life under specific conditions of use(water quality, duration heating season etc);
• calculation of fuel consumption and volume of combustion products. Each type of fuel has its own combustion coefficients, and depending on the power of the installation, the indicators of consumption and heat loss may be different;
• boiler heat balance- establishment of equality between the heat received during combustion and the sum of the used and lost heat;
• calculation of the combustion chamber, geometric parameters, diameter, length and volume of the furnace;
• other.

Carrying out plant diagnostics

The operation of a fire-tube installation in a boiler room requires certain diagnostics. The main requirement to ensure the uninterrupted operation of boiler equipment is the water regime. This mode includes the main principles - high quality feed water , since fire tube installations have powerful heat fluxes (about 1,300 kW / m3), and free movement of water– therefore, the dimensions and weight of the structure are relatively small.

Thermal calculations show that if the water regime is not observed scale quickly forms on the surface of the flame tubes and on the walls of the boiler(calcium deposits). This is due to the process of boiling water on the surface. steel pipes. The presence of deposits reduces the thermal conductivity of heat. Technical diagnostics of a fire-tube boiler house must necessarily include a study of water for hardness, the presence of impurities, salts. The methodology is based on chemical analyzes and sampling.

Analysis negative factors for technical diagnostics and thermal calculations modern fire-tube boilers have the following conclusions:

• when the pressure in the system decreases, the boiling process is much more active and scale forms faster, therefore, for such installations, it is necessary to comply with strict requirements for water softness;
• when the pressure in the system rises, the water may not boil, the temperature of the pipe walls can be significantly lower, resulting in less scale formation and lower fuel consumption, while the water quality can be average in terms of hardness.

Heating boilers of medium and large capacity according to the type of construction are divided into two large groups- water-tube and gas-tube (fire-tube).

Gas-pipe- a steam or hot water boiler, in which the heating surface consists of tubes of small diameter, inside which hot products of fuel combustion move. Heat exchange occurs by heating the coolant (water), which is located outside the tubes.

According to GOST 23172-78, there are fire tube, smoke-burning and fire tube-smoke boilers: combustion occurs in the flame tubes, combustion products only move in the smoke tubes. Flame tubes are usually thicker and fewer in number.

According to the direction of movement of flue gases, fire-tube boilers can be divided into span boilers, where hot gases passing through the fire chamber and flame tubes do not change their direction, and circulating boilers, where gases make a turn in the fire chamber.

The most common design of gas-tube boilers is a cylindrical body located horizontally. Inside the body of hot water boilers is hot water, have steam water and steam volumes. A fire tube is used as a furnace, located either in the center of the boiler or below. An inflatable burner is installed at the front end of the flame tube, designed to burn gaseous or liquid fuels. Above the furnace are bundles of smoke tubes, through which further movement of hot gases occurs, followed by exit into chimney.

Boilers of this design are two-way and three-way. Two-pass boilers use a reversible furnace. In a reversible furnace, flue gases are reflected from rear wall the furnaces turn 180°C and go to the front wall of the boiler. Further, hot gases again change the direction of movement, reflecting from the front wall, and passing through the fire tubes are removed from the boiler.

In a three-pass boiler, flue gases return to the front wall of the boiler through the second flame tube, or through the second stack of fire tubes. Further, hot gases again change the direction of movement, reflecting from the front wall, and passing through the fire tubes are removed from the boiler.

The advantages of a gas-tube boiler include the following:

• ease of manufacture;
• the possibility of using low-quality steel, which reduces the cost;
• compactness;
• ease of maintenance.

Gas-tube boilers have a number of operational "cons", crossing out all their "pluses". Namely:

• High requirements (compared to water tube boilers) to boiler water quality. More stringent requirements for the quality of feed water are explained by very low velocities (by an order of magnitude less compared to water-tube boilers) of the heat carrier in fire-tube boilers. In a fire-tube boiler, the water velocity is so low that it is practically a precipitating filter. Such boilers cannot be included in a single-circuit scheme with an old heating network that has many years of accumulation of sludge in the lower part of radiators and network pipelines. As a result of the sedimentation of suspended solids and their coating of a part of the fire tubes, the temperature of these tubes becomes higher, the pressure of the superheated tubes on the tube sheet and the stresses in the welds increase sharply. Which leads to deformation of the heat exchanger and rupture of the seams.
• Fire tube boiler is explosive . With a large volume of heated water, with a sudden decrease in pressure inside the boiler to atmospheric pressure (seam opening), a huge amount of steam is instantly released and an explosion occurs.
• Fire tube boilers have higher aerodynamic drag than water tube boilers.
• It is necessary to note one more, although far from the main problem of fire-tube boilers. The presence of a large volume of water makes the boiler “sluggishly” responsive to the need for heat. Typical for such boilers long time heating leads in practice to the need to maintain a high temperature of a large mass of water for a certain period of time in anticipation of the need for heat. And the cost of fuel used to maintain this "hot reserve" can reach a significant value.

By design, a gas-tube boiler is the opposite of a water-tube boiler.

Water tube boilers - a steam or hot water boiler, in which the heating surface (screen) consists of pipes (boiler tubes), inside which the coolant (water) moves. Heat exchange occurs by heating the pipes with hot products of the burning fuel.

The simplest water-tube heat exchanger is a structure of two parallel tubes connected to each other. large quantity cross pipes. This design is located in the boiler furnace and flue gases passing between the pipes heat the coolant. To increase the heating area, finned tubes are used.

An example is the radiator of a car cooling system. In fact, it is a secondary water-tube heat exchanger.

Distinctive features of water-tube boilers from gas-tube boilers are a smaller volume of water and a higher coolant flow rate. This results in the following benefits:

• low explosiveness;
• fast heating of water;
• lower weight of the boiler;
• improved heat removal;
• greater durability of the structure;
• lower water quality requirements.

The disadvantages of such boilers include:

• high quality requirements for connections;
• design complexity;
• difficulty in maintenance.

Most of the boilers on the Russian market are fire-tube boilers. This is due both to a simpler production technology and to the ease of maintenance of these boilers. Despite its advantages water tube boilers middle and large capacity less popular with consumers, but still occupy their part of the heating equipment market.

In water-tube units, water moves inside the pipes and is heated by hot flue gases. Fire-tube hot water boilers are arranged differently. Inside, in the water volume, there is a cylindrical furnace and flame tubes. Fuel is burned in the furnace and pipes. The generated heat is transferred to the water.

The popularity of fire tube hot water boilers is now increasing. They are used both in production and for heating residential buildings. The use of aggregates does not require special skills. In addition, they are easy to repair, which enables long-term operation. The cost is low. Manufacturers, both domestic and foreign, annually increase the output of boilers of this type.

Layout of fire-tube hot water boilers

• two-way
• Three-way

Boilers of the first type form two gas passes: the movement of combustion products in the furnace (first pass) and through the fire tubes (second pass).

Boilers of the second type have a third stroke, when the combustion products move in the opposite direction, turning one hundred and eighty degrees. These units have a higher efficiency compared to two-way units. They possess larger surface flame tubes, which means better heat transfer. An additional increase in the efficiency of the boiler can be provided by the installation of an economizer.

The disadvantage of fire-tube hot water boilers, experts call low speed movement of water in the internal volume of the unit. This leads to deposits of scale and sludge on the surfaces. Scale impairs heat transfer and leads to overheating of the pipe wall. There is an additional load on the welds, which reduces the service life of thermal equipment.

Features of fire-tube hot water boilers

Modern models fire-tube hot water boilers have been improved so much that there is no decrease in the efficiency of their work:

• Strengthening and equalization of heat transfer is provided by flow turbulators.
• Flame tubes are located high, which prevents the deposition of sludge.
• The design provides such a high speed of movement of the coolant that scale pollution does not have time to form.
• Unique casting and welding technologies from leading manufacturers allow extending the service life of heating equipment for decades.

For long term and effective work boilers with flame tubes required good cleaning water and careful monitoring of the entire system, in particular, the temperature of the outgoing gas mixture, pressure loss, leaks in heating networks, etc. Automatic system control and compliance with all operating rules declared by the manufacturer ensures uninterrupted operation of heat generators for a long time.

a-main mode; b-peak mode; 1-inlet and outlet collectors; 2-connecting pipes; 3-front screen; 4-convective tube bundle; 5, 6-left and right side screens; 7-back screen; 8-circuit collectors; - movement of water.

Water in the boiler circulates with pumps. Water consumption depends on the mode of operation of the heating boiler: when operating in winter period a four-way water circulation scheme is used according to the main regime, and in summer - a two-way scheme according to the peak regime.

With a four-way circulation scheme, water in the heating boiler from the heating network is supplied to one lower collector and sequentially passes through all elements of the heating surface of the boiler, overcoming ups and downs, after which the water is also discharged through the lower collector to heating network.

With a two-way scheme water in the boiler simultaneously enters the two lower collectors and, moving along the heating surface, heats up, after which it is discharged into the heating network. With a two-way circulation scheme, almost twice more water than with a four-way scheme. This is explained by the fact that at summer mode the operation of the boiler heats up more than in winter, the amount of water and it enters boiler with more high temperature(PO instead of 70 °C).

Fire tube boilers

By design, it is the opposite of a water-tube boiler. Gas-tube boiler- a steam or hot water boiler, in which the heating surface consists of tubes of small diameter, inside which hot fuel combustion products move. Heat exchange occurs by heating the coolant (usually water or oil), which is located outside the tubes. According to GOST 23172-78, there are fire tube, smoke-burning and fire tube-smoke boilers: in flame pipes are burning smoke-burning Only combustion products move. Flame tubes are usually thicker and fewer in number. The most common design of fire-tube boilers is a cylindrical body located horizontally.

Inside the body of hot water boilers there is hot water, for steam boilers there is water and steam volumes. At the front end of each flame tube, a pressurized burner is installed, designed to burn gaseous or liquid fuels. Thus, the flame tube is a combustion chamber in which almost all fuel burns. The unit consists of a cylindrical metal drum with a flame tube, in which a firebox is arranged. The gas heated inside exits the pipe and heats side surfaces boiler drum, then goes to the economizer or directly to the chimney. There are models with two pipes, extremely rarely - with three or more. Modern single fire tube boilers are manufactured with heating surfaces from 30 to 50 square meters, the heated plane of double fire tube boilers is from 80 to 100 square meters. Heating units of this type are easy to manufacture, and therefore the price for them is minimal. The device of fire-tube boilers allows them to be used in heating and water supply systems of residential facilities and industrial enterprises. maximum efficiency, high reliability functioning and good thermal performance, such equipment demonstrates when using gas fuel. However, there are also disadvantages: a significant heating of the nozzles of the burners, pulsating combustion can also be observed, which is accompanied by flame ejection and pops. As a rule, in most cases it is possible to eliminate these shortcomings. It is important to maintain the efficiency of the unit that the diameter of the nozzles structural features medium pressure injection burners, otherwise complete combustion of the gas cannot be achieved. Structural device A fire tube boiler requires a pressure reducing unit, since the unit is supplied with gas from medium or high pressure networks.

The disadvantages of the design of fire-tube boilers include:

§ large dimensions;

§ significant metal consumption;

§ high requirements of internal furnaces to fuel quality;

§ explosiveness.

However, strict adherence to the manufacturer's instructions for the operation of boilers and safety regulations completely eliminates the possibility of emergency situations.

Steam fire tube boilers. The lining of single-fire-tube and double-fire-tube boilers is carried out in the same way, changing only in its upper part, depending on whether the boiler operates as a steam or hot water boiler. This type of brickwork is recognized as the best; flues are cleanable and large enough that fly ash can be deposited in them without obstructing the path for gases. Flue gases, having passed the flame tubes, enter the rotary chamber, the dimensions of which in width should not be narrowed, since in this chamber most of fly ash. Bypassing the revolving chamber, the gases pass through the second flue, not reaching the front of the boiler, turn and go through the third-last gas flue, heading to the common collection hog. Within the rotary chamber, the gases pass through a special channel that separates the third gas duct from the space of the rotary chamber. The brick walls are laid out in 2 bricks. Top part flue does not reach 100 mm to the lowest water level in the boiler; this is a requirement of the Kotlonadzor.

AT last years on the Russian market There is a great interest in industrial heating boilers supplied by foreign companies. The cost of imported boilers is usually higher than the cost of similar boilers domestic manufacturers However, when completing industrial and large heating boiler houses, customers often prefer products from well-known European companies.

The main feature of industrial steam boilers supplied to the Russian market by manufacturers from Italy, Germany, Belgium and others European countries, consists in the fact that almost all boilers are fire-tube, more precisely, fire-tube-smoke. This applies not only to hot water boilers, but also to steam boilers with a superheater with a capacity of up to 30 t/h and more. The advantage of fire-smoke-tube boilers over water-tube boilers is simply explained: this design allows you to assemble the boiler completely in the factory and deliver the boiler to the customer in the form of a single block, which greatly simplifies the installation of equipment in the boiler room.

Fire tube-smoke boilers have, as a rule, a cylindrical body lying on its side. Even in those cases when the outside of the boiler looks like an elongated rectangle, there is no doubt that it has a cylindrical body inside ( rice. one). Inside the case of steam boilers - water and steam volumes.

Rice. one

In a large volume of water there is one, and sometimes two flame tubes. At the front end of each flame tube there is a pressurized, or, as they say, fan burner, designed to burn gas or liquid fuel. Thus, the flame tube is a combustion chamber in which almost all fuel burns.

The thermal stress of the furnace volume is usually 1‑1.2 MW/m 3 . depending on the diameter and overpressure smooth or wavy flame tubes are used. They are always located in the lower part of the water space, which increases heat transfer and improves the circulation of boiler water ( rice. 2).

Rice. 2

In Germany, there are regulations requiring the installation of two flame tubes with a boiler capacity of more than 10 MW. In other countries there is no strict requirement for the ratio of power and the number of flame tubes, so you can find more powerful boilers with one flame tube, as well as less powerful ones with two flame tubes.

If the manufacturers do not emphasize that their boiler is three-way, then this means that the burner is almost straight-through: it forms a long torch. The combustion products reach the opposite water-cooled wall, turn around and move towards the front wall. Here they enter the annular chamber, from which they move again through the smoke tubes towards the back wall, giving off heat to the boiler water ( rice. 3).

Rice. 3

More often in the name of the boiler there is the term "three-way". This means that the products of combustion after the flame tube are returned back through the fire tubes, which are located, as a rule, closer to the flame tube. At the front wall of the boiler, the flue gases make one more turn and pass through the smoke tubes of the third pass towards the back wall.

For a more complete use of the heat of flue gases, many manufacturers install special turbulators made of high-strength steel in the smoke tubes of the third pass. The same effect is sometimes achieved without inserts, due to the special shape of the tubes themselves. The turbulence of the flow increases the heat removal and thereby reduces the temperature of the flue gases, that is, increases the efficiency of the boiler.

In larger boilers, an increase in efficiency is ensured by installing an economizer after the third flue gas pass. On the rice. 3 shows a diagram of such a boiler with one important feature: a damper in the upper part of the smoke chamber allows some of the combustion products to pass directly by shunting the economizer. This makes it possible to maintain a constant flue gas temperature in the event of load changes or inadmissible drops in the boiler return temperature. When burning sulfur-containing fuels, this is especially important, since thanks to this simple device, it is possible to maintain a “dry” mode of operation of the economizer without falling below the dew point temperature.

The presence of an economizer in itself significantly increases the efficiency of the boiler. So, for example, the Borsig Energy Omnimat 16PG hot water boiler without an economizer has an efficiency of 93%, and the Omnimat 16PGA (with an economizer) has an efficiency of 95.6%. With equal useful thermal power of these boilers (8 MW), the first one consumes 929 m 3 / h at a rated load natural gas, and the second - only 904 m 3 / h. At the same time, both boilers have the same height and width, but the length of the boiler with an economizer is greater by ≈10% (4.81 m for 16PG and 5.30 m for 16PGA boiler).

In most cases three-pass boilers have a so-called smoke-fire chamber at the exit from the flame tube. Combustion products in this chamber turn 180° and enter the fire tubes of the second flue. The fire chamber is usually cooled by the boiler water surrounding it, although external fire chambers made of all-welded screen tubes are also found.

The flue gases are turned from the second pass to the smoke tubes of the third pass in the front fire chamber. This annular chamber is equipped with one or two hatches that allow access (of course, with the boiler stopped) to the fire tubes for their inspection and cleaning.

The cylindrical body of fire-tube boilers is always covered with highly efficient thermal insulation 100-120 mm thick. On top of the insulation, the body is usually sheathed on both sides with galvanized or aluminum sheets. Good insulation, combined with the compact design of the boiler itself, helps to reduce heat loss to the environment.

Fittings for return of water and for delivery of saturated steam are connected to the body of boilers. To drain the water there is a special fitting in the lower part at the rear end of the housing. On the upper part of the body there are also fittings for instrumentation. On the steam boilers water level indicators are required.

Most manufacturers supply steam boilers with an electric feed pump and a steam injector. On top of all large boilers, there is usually a platform for servicing fittings and instrumentation. Complete with the main equipment, manufacturers, as a rule, supply a control unit, which is sometimes called a "panel" or even a "cabinet" of control. This block on steam boilers includes a level controller that acts on feed pump. The control unit is connected to a manometer, to a limiting and safety pressure switch. There is also a switch from manual to automatic control pump, light and audible alarm activated in an emergency.

Combustion chambers in fire-tube boilers usually operate at excess pressure, so the installation of a smoke exhauster for evacuating gases is not required. Combustion air is usually supplied by a fan built into the burner block.

Automated boiler control allows you to minimize the employment of qualified personnel, even when servicing large steam or hot water boilers.

A few words must be said about the fuel for the industrial and heating boilers described above. These boilers are installed, as a rule, within the city or, in extreme cases, in the suburbs. Rigid protection standards environment force boiler owners to limit air emissions of toxic pollutants such as ash particles, nitrogen oxides (NO x), sulfur dioxide (SO 2) and carbon monoxide ( carbon monoxide- CO). Since the complete set of boiler plants with devices for cleaning flue gases from these toxic components would increase their cost several times, most economical option is the use of gaseous or liquid fuels. In the latter case, the use of diesel fuel or light fuel oils with a low sulfur content is mandatory. With this choice of fuel, nitrogen oxides NO x are practically the only atmospheric pollutant.

The main means of ensuring acceptable NO x emissions in industrial and heating boilers are low-toxic burners. In some cases, flue gas recirculation through the burner is also used. Due to the special design, low-toxic burners create a flame with a certain intensity of mixing of fuel with air, which reduces the rate of NO x formation. Combined with the moderate thermal stress of the combustion chamber, intensive heat dissipation and the three-pass scheme of most boilers, low-emission burners reduce NO x emissions to a level that meets the requirements of the Russian Federation.

Of course, manufacturers of industrial boilers could not ignore the fact that some customers are still forced to burn solid fuel: coal, wood waste, municipal solid waste, etc. For such customers, there is also a wide range of boilers, including steel fire-tube boilers. But such units are delivered to the customer already in the form of at least three blocks: the boiler itself, a remote furnace with a mechanical grate and an ash catcher, after which the flue gases enter the smoke exhauster. The combustion of wood or sorted industrial waste takes place on an inclined mechanical grate, and the combustion products are directed into the flame tube. Another option is less common: a chain mechanical grate is inserted directly into the flame tube of a cylindrical boiler.

The fire-tube boilers described above are in many respects similar to similar boilers of domestic manufacturers when it comes to the design of the boilers themselves. Therefore, the situation is becoming more and more common when a consumer prefers a fairly reliable and cheaper domestic boiler, but asks to install an imported burner on it - a more expensive one, but ensuring the operation of the boiler without attendants, starting the boiler by pressing a button and minimal emissions of toxic pollutants into the atmosphere (CO and NOx).

As an example, we will talk about fire-tube steam boilers of several foreign companies that are actively operating in the Russian market. One such company is B. abcock Wanson (France).

This company represents several series of fire-tube steam boilers on the Russian market. For small steam requirements B Abcock W anson offers compact steam boiler series bwb (from 160 kg to 3 t/h). Due to its small size, such a boiler can be used in the design of a modular boiler room. The boiler is two-pass, the placement of the flame tube in the center improves the distribution of stresses and increases the life of the heat exchanger unit of the boiler, especially during numerous cycles of starting and stopping the boiler. Access to the rear pipe panel is provided by rolling back the rear inspection door suspended on a cantilever rail. Thus, both boiler maintenance and mandatory periodic inspections by technical supervision authorities are facilitated.

For higher steam requirements, it is preferable to use a BWD boiler (1 to 10.4 t/h). The model of the BWD series is a three-pass boiler of special design, with a partially water-cooled furnace bottom, developed by B. Abcock W anson . Steam separator located inside the boiler body, as well as a short time burner adaptations ensure a guaranteed steam dryness of 99.5%.

For large industrial boiler houses by company B Abcock W anson series was developed BWR (12.5-30 t/h). These are steam three-pass fire-tube-smoke boilers of a special design with a tubular water-cooled furnace bottom ( rice. 4). These boilers combine the advantages of fire-tube and water-tube technology. The design provides the highest possible pressure in the hot water chamber (up to 25 bar) for fire-tube boilers. This design of the boiler provides the best level of safety at low water levels and eliminates the risk of sludge deposits on the bottom of the boiler. Optimization of the boiler design makes it possible to integrate a steam superheating module into the front smoke chamber.

Rice. 4

The efficiency of the boilers described above is optimized thanks to the special technical development of the company B Abcock W anson. Inside the smooth-walled smoke tubes, helical guides are placed, which impart rotational movement to the combustion products passing through the tube, as a result of which a significant improvement in heat transfer is achieved.. Company BAbcock Wanson uses his signature burners in everything model range fire tube boilers. Each individual burner is designed taking into account the characteristics of the combustion chamber, which saves fuel, thereby increasing efficiency. The burners operate both on gas and diesel fuel, and on fuel oil.

To further improve efficiency, reduce fuel and electricity consumption and achieve extremely low NO x , B Abcock W anson offers its customers an Ecosteam package that reduces the operating costs of these already inexpensive boilers. This package includes a system of water-to-water or/and water-to-air heat exchangers. The company also produces a series of boilers VAB-BP (from 160 to 5300 kg/h) with low steam pressure (<0,5 бара), которыене попадают под действие органов по надзору за безопасностью. Для утилизации же тепла, образующегося в технологических процессах, предлагаются жаротрубные паровые котлы-утилизаторы.

Consider another line - steam fire-tube boilers from Bosch Industriekessel GmbH (Germany). The most popular boilers of this company are known on the market under the brand Buderus. Range of boilers Buderus Logano SHD 815/ UL - S includes fire-tube-smoke-fired boilers with one flame tube (three-pass scheme) with steam output from 1.25 to 28 t/h.

Larger boilers (type series Buderus Logano SHD 915/ ZFR ) are equipped with two flame tubes, and their steam output ranges from 18 to 55 t/h. All series boilers Buderus Logano are equipped with low-toxic burners that ensure minimal emission of toxic nitrogen oxides. Losses to the environment of these boilers are reduced due to the use of high-quality heat-insulating mats and special heaters. At all loads, the boilers operate with a low noise level. The reduction in operating costs is ensured not only as a result of reduced fuel consumption, but also due to lower power consumption for own needs and a highly efficient boiler control system.

Depending on the requirements of the steam consumer, boilers for pressure from 0.5 to 30 bar can be installed in the boiler room.Boilers with elevated steam temperature are equipped with superheaters. Series boilers SHD 915/ ZFR have 2 flame tubes, but with reduced load they can work with one included flame tube. It is important to note that operation with one flame tube can significantly increase the efficiency of the boiler at reduced load (compared to operation with two burners).