Single-stage, two-stage and modulating burners for heating boilers. Review

Single-stage, two-stage and modulating burners for heating boilers. Review.

When choosing burners, consumers face a difficult task– which burner to choose . This choice allows them to make a small comparison of burners from different manufacturers by type of regulation and level of automation of the burner device.

We invite you to familiarize yourself with the opinion of our company’s specialists, based on the experience of using combined, liquid fuel and gas burners from Weishaupt, Elco, Cib Unigas and Baltur.

Let's determine the basic requirements for burners, depending on the application. Depending on the area of ​​application, burners can be divided into groups.

Group 1. Burners for individual heating systems (in this group we include burners with a power of up to 500 - 600 kW, which are installed in boiler rooms of private houses, small industrial and commercial and administrative buildings).

When choosing burners for this group of consumers, it is necessary to take into account the buyer’s wishes in the level of automation of an individual boiler room:

· if you do not have high technical requirements for the installed equipment and want to have a reliable boiler room that does not require large initial financial investments, then you can opt for burners with single-stage, two-stage operating modes;

· if as a result you want to build a heating system with a high level of automation, weather-dependent regulation, as well as low fuel and energy consumption, then it is better for you to use modulating burners or burners with smooth two-stage regulation, which will provide the ability to program power and a wide operating range of burner control.

Group 2. Burners for heating systems of large residential complexes (in this group we include burners with a capacity of more than 600 kW for the needs of housing and communal services, central heating, as well as for heat supply of large industrial and commercial and administrative buildings).

· Smooth two-stage or modulating burners are ideal for this group. This is due to: high power boiler rooms, the customer’s wish to build a boiler room with a high level of automation, the desire to ensure the lowest possible fuel and electricity consumption (use frequency control of fan power), as well as use equipment for automatic control of residual oxygen in flue gases (oxygen control).

Group 3. Burners for use on process equipment (this group can include burners of any power, depending on the power of the process equipment).

· Preferred for this group modulating burners. The choice of these burners is determined not so much by the wishes of the customer, but by the technological requirements of production. For example: in some production processes it is necessary to maintain a strictly defined temperature schedule and prevent temperature changes, otherwise this may lead to a violation technological process, product damage and, as a result, significant financial losses. Burners with step control can also be used in process plants, but only in cases where minor temperature fluctuations are acceptable and do not entail negative consequences.

Brief description of the operating principle of burners with different types of regulation.

Single stage burners They operate only in one power range, they operate in a mode that is difficult for the boiler. When single-stage burners operate, frequent switching on and off of the burner occurs, which is controlled by the automatic control of the boiler unit.

Two stage burners , as the name suggests, have two power levels. The first stage typically provides 40% of the power, and the second 100%. The transition from the first stage to the second occurs depending on the controlled boiler parameter (coolant temperature or steam pressure), the on/off modes depend on the boiler automation.

Smooth two-stage burners allow for a smooth transition from the first stage to the second. This is a cross between a two-stage and modulating burner.

Modulating burners heat the boiler continuously, increasing or decreasing power as necessary. The range of combustion mode changes is from 10 to 100% of the rated power.

Modulating burners are divided into three types according to the operating principle of modulating devices:

1. burners with a mechanical modulation system;

2. burners with pneumatic modulation system;

3. burners with electronic modulation.

Unlike burners with mechanical and pneumatic modulation, burners with electronic modulation allow for the highest possible control accuracy, since mechanical errors in the operation of burner devices are eliminated.

Price advantages and disadvantages

Of course, modulating burners are more expensive than stepped models, but they have a number of advantages over them. The mechanism for smooth power control allows you to reduce the cycle of turning on and off boilers to a minimum, which significantly reduces mechanical stress on the walls and components of the boiler, and therefore prolongs its “life”. Fuel savings are at least 5%, and with proper tuning you can achieve 15% or more. And finally, installing modulating burners does not require replacing expensive boilers if they are functioning properly, while increasing the efficiency of the boiler.

Against the background of the disadvantages of stepped burners, the advantages of modulating burners are obvious. The only factor forcing managers to choose step models is their more low price. But savings of this kind are deceptive: wouldn’t it be better to spend a large sum at a time on more advanced, economical and environmentally friendly burners? Moreover, the costs will pay off in the next few years!

Many buyers understand the benefits of using modulating burners, and now they only have to choose the necessary models. Which manufacturers are best to contact? Even with a superficial study of prices for imported and domestic burners, it is clear that the difference is quite significant. Some models from foreign manufacturers are more than twice as expensive as Russian-made products.

A detailed analysis of the market for burner manufacturers shows that Russian equipment is significantly inferior to imported analogues in terms of automation level. In order to achieve a high level of automation of Russian-made burners, it is necessary to invest quite a lot Money for the purchase of the necessary automation systems and installation and commissioning of equipment. Based on the results of all the work, it turns out that the cost of retrofitted Russian-made burners is close to the cost of imported burners. But at the same time, you will not have a 100% guarantee that a fully equipped Russian burner will provide you with the desired result.

Conclusion of our experts

Choosing the right burner is an important step in the construction or modernization of a boiler room. The further operation of the heating equipment depends on how responsibly you approach this issue. Stable operation of the burner, compliance with environmental standards, longer service life of boilers and the ability to fully automate the operation of a thermal power plant indicate significant advantages of using modulating burners in boiler houses. And if the benefit from their operation is obvious, not taking advantage of it is simply unreasonable.

Burners Weishaupt / Germany Elco/ Germany , Cib Unigas / Italy, Baltur / Italy have proven themselves to be reliable and quality equipment. By choosing these burners, you get confidence and profit! In turn, we are ready to provide you with reasonable prices and the shortest delivery time for equipment.

Heating gas boilers have a complex structure. Their design includes combustion chambers, gas burners for boilers, and they are equipped with automation. Double-circuit equipment also includes boilers that heat water for household needs. Regardless of the brand and model of a gas boiler, its most important part is the burner. The efficiency of the entire heating system at home, as well as saving fuel resources, largely depends on it.

Classification of gas burners

In a device called a gas burner, the process of mixing the supplied gas and the intake or forced air occurs, followed by combustion of the combustible composition in the combustion chamber. It can operate under conditions of main gas supply, as well as from a cylinder or a special tank. The process itself depends on the characteristics of the burner and the ability to customize it to certain conditions.

Depending on the method of air supply, gas burners are divided into two types:

• atmospheric - an air-gas mixture is obtained due to the natural absorption of air from the surrounding space and mixing it with the supplied gas;
• supercharged, using a fan to force air;
• combined.

In the first case we are talking about boilers with open combustion chambers, and in the second - with closed ones. Also, gas burners for heating boilers have different types of power control:

• single-stage – the simplest and most affordable;
• two-stage – with two automatically switching operating modes;
• smooth two-stage - with soft flame adjustment between two stages;
• modulated - the most efficient and reliable, with precise and quick adjustment depending on changes temperature regime coolant. It is characterized by high cost.

What to look for when choosing

When purchasing, you should take into account the operating conditions of the heating equipment, the features of its operation and capabilities. Maintenance. Dimensions gas burner must be in accordance with the dimensions of the boiler furnace, otherwise, instead of reliability and durability, you will get a burnt-out combustion chamber.

Each of the burners has its own characteristics, thanks to which one or another model is chosen for each specific case.

When choosing a gas burner, the following is of particular importance:

• manufacturer;
• characteristics;
• model;
• price;
• equipment compatibility.

Atmospheric burners

This design is a perforated tube with a profile cross-section into which gas is supplied. A reduced pressure is created in the tube, due to which air is sucked into it directly from the room where the boiler is located. As a result, a flammable substance is formed that supports the combustion process after ignition of the wick using a piezo or electric element. Such burners have another name - injection.

Atmospheric burners are quite often called gas burners, designed for heating boilers equipped with open combustion chambers.

The gas burner option under consideration is perfect for small houses, up to 100 square meters. meters. An atmospheric gas burner for a boiler is usually cheaper than its forced-air counterparts. But the cost of modern models with automation is high.

Advantages

Atmospheric burners are widely used among owners of private houses. Their positive characteristics include:

• noiselessness;
• compactness;
• independence of most models from power supply;
• reliability due to design simplicity;
• low operating costs;
• reasonable price.

Flaws

ABOUT weaknesses we can say the following:

• low power;
• low efficiency (no more than 90%);
• sensitivity to frequent changes in pressure of the supplied gas (the need to install additional automation, in particular, a control relay that responds to changes in pressure);
• maintaining a high level of cleanliness of the room where the boiler is located to avoid clogging the burner with dust.

Pressure surges can lead to burnout of the gas burner nozzle when the gas supply is reduced, or to burnout of the heat exchanger when the flame height is too high.

Pressurized burners

Pressurized or blown burners are designed to work with boilers equipped with a closed combustion chamber. The air here is forced by fans. In this case, there is an additional possibility of flexible regulation of the power of the flow of the gas-air mixture, and therefore, a real achievement appears high performance Efficiency

Pressurized burners have a more complex design. It is noteworthy that air is supplied to this device in parts, but it mixes with gas almost instantly. Gas boilers, in turn, also have their differences from those that work in tandem with atmospheric burners.

Schematically, the boiler is represented by barrels of different diameters and depths inserted into each other so that their bottom is at the top. A coolant circulates between the walls, heated by the burner torch from several sides at once - on top and on the sides. This design ensures high performance of the equipment.

A significant difference between forced-air burners and atmospheric burners is that the former are considered not an integral part of boilers, but additional equipment, which is purchased separately.

Modern pressurized burners are necessarily equipped with automatic equipment, ensuring uninterrupted and reliable operation of heating equipment. Externally, they look like a block, inside of which there is the burner itself with a built-in electric fan.

The devices under consideration are divided into:

• vortex, equipped with round outlets. Provide powerful air flow and stable combustion;
• direct-flow, supplying a combustible mixture through outlets of various shapes (circle, slot, rectangle).

Advantages

It should be rightly noted that forced-air gas burners:

• safe - the combustion process occurs in an isolated space;
• highly productive and highly efficient, thanks to their design features, the efficiency is about 95%;
• insensitive to pressure changes - a decrease in the indicator is compensated by the presence of a fan;
• environmentally friendly;
• have the ability to replace with other types of burners.

Flaws

It is not so easy to find equipment that is free of shortcomings. They are also present in blower burners:

• the presence of noise during operation dictates the need to install the boiler in a separate room;
• dependence on electricity requires the presence of a UPS in the system;
• the volumetric dimensions make it impossible to install heating equipment in small rooms;
• the high cost of the device prevents its use by all categories of consumers.

Combination burners

Available for combined heating boilers that can operate on both gas and liquid fuel(fuel oil, diesel fuel). Such devices do not require replacement when switching from one combustible mixture to another. But the switching process itself is quite complex and requires the presence of a professional.

The burners in question are fully automated, which minimizes the human factor. They have functions for controlling flame power, combustion mode and other equally useful processes.

Combination burners have not gained popularity among homeowners due to their complex design and high price, combined with low efficiency.

Proper care is the key to long-term operation

During operation, the gas burner needs timely cleaning of soot. It appears during operation and, if accumulated in large quantities, can lead to sudden ignition. Scheduled equipment inspection and regular maintenance will help you avoid troubles. heating device and a gas burner.

If you are cleaning it yourself, we recommend that you read the included instructions. But a more prudent decision would be to contact specialists who have experience in this field. In this case, the work will go much faster and better, with the least amount of dirt.

A gas burner is a device for mixing oxygen with gaseous fuel in order to supply the mixture to the outlet and burn it to form a stable torch. In a gas burner, gaseous fuel supplied under pressure is mixed in a mixing device with air (air oxygen) and the resulting mixture is ignited at the outlet of the mixing device to form a stable constant flame.

Gas burners have a wide range of advantages. The design of the gas burner is very simple. Its startup takes a fraction of a second and such a burner operates almost flawlessly. Gas burners are used for heating boilers or industrial applications.

Today there are two main types of gas burners, their division is carried out depending on the method used to form the combustible mixture (consisting of fuel and air). There are atmospheric (injection) and supercharged (ventilation) devices. In most cases, the first type is part of the boiler and is included in its price, while the second type is most often purchased separately. A pressurized gas burner is more efficient as a combustion tool, since they are supplied with air by a special fan (built into the burner).

The purposes of gas burners are:

– supply of gas and air to the combustion front;

– mixture formation;

– stabilization of the ignition front;

– ensuring the required combustion intensity.

Types of gas burners:

Diffusion burner – a burner in which fuel and air are mixed during combustion.

Injection burner – a gas burner with preliminary mixing of gas and air, in which one of the media necessary for combustion is sucked into the combustion chamber of another medium (synonym: ejection burner)

Hollow Premix Burner – A burner in which the gas is mixed with a full volume of air before the outlets.

A large group of burners of varying designs and performance are classified as burners with incomplete preliminary mixing of gas and air. With burners of this type, the mixture formation process begins in the burner itself and is actively completed in the combustion chamber. As a result, the gas burns with a short and non-luminous flame. Due to the fact that the gas-air mixture was partially prepared before entering the furnace, where the combustion process begins, the combustion rate is determined by diffusion and kinetic factors. Consequently, these burners use a diffusion-kinetic method of gas combustion. Burners of the type considered consist of systems for separate supply of gas and all the air necessary for combustion, as well as devices in which the process of mixture formation begins. A gas-air mixture enters the furnace, which is a turbulent flow with uneven fields of fuel and oxidizer concentrations in the cross section. Once in a high temperature zone, the mixture ignites. Sections of the flow in which the concentration of gas and air are in a stoichiometric ratio burn out kinetically, and zones in which the mixture formation process is not completed burn out by diffusion. The mixing process in the firebox is controlled by the burner mixing device, since the structure of the flow and the movement of its individual particles determine the conditions for its exit from the mixer. The mixing of gas and air in these burners occurs as a result of turbulent diffusion, therefore such burners are called turbulent mixing burners. To increase the intensity of the gas combustion process, the mixing of gas with air should be intensified as much as possible, since mixture formation is the inhibiting link in the entire process. Intensification of the mixture formation process is achieved by: swirling the air flow with guide blades; tangential supply or device of snails; supplying gas in the form of small jets at an angle to the air flow by dividing the gas and air flows into small flows in which mixing occurs. Turbulent mixing burners are widely used. The main positive qualities of such burners are: a) the ability to burn a large amount of gas with relatively small burner dimensions (especially important for powerful boilers); b) wide range of burner performance control; c) the ability to heat gas and air to temperatures above the ignition temperature, which is of great importance for some high-temperature furnaces; d) relatively simple implementation of structures with combined combustion of fuel (gas - fuel oil, gas - coal dust). Disadvantages of the burners under consideration: forced air supply and combustion of gas with chemical incompleteness, greater than with kinetic combustion. Turbulent mixing burners have different capacities from 60 kW to 60 MW. They are used to heat industrial furnaces and boilers.

Turbulent mixing burners GNP designed by Teploproekt with a capacity of 7 ... 250 m3/h at a gas and air pressure of 0.4 ... 2 kPa are shown in Fig. 16.10. The burners are produced in nine standard sizes with two types of gas nozzle tips. Tip A provides a short flare, and tip B produces a long flare. Gas enters the burner through the nozzle and flows out at a certain speed from the nozzle. Air is supplied to the burner under pressure; it is twisted before entering the burner spout. The mixing of gas with air begins inside the burner when the gas exits the nozzle and is intensified by a swirling air flow. With a multi-jet gas supply (with tip A), the process of mixture formation proceeds faster and the gas burns in a short torch. The burner is installed together with a ceramic tunnel, which serves as a combustion stabilizer. The burners ensure combustion of gas in the absence of chemical incompleteness with an excess air coefficient α= 1.05 ... 1.1. At a gas pressure of 4 kPa, the length of the torch for burners with a tip of type A, depending on the size of the burner, varies from 0.6 to 2.3 m. The main dimensions of the GNP burner series are as follows: the diameter of the outlet varies within the range D = 25...142 mm; the diameter of the gas holes at the tip of type A is: d=3.2 ... 15.5, and their number varies from 4 to 6; the diameter of the gas hole at the tip of type B is: di = 5.5 ... 31 mm (designations are shown in Fig. 16.10). Based on the results of state tests, the burners are recommended for use. Their main positive qualities are: simplicity and compactness of design, the ability to operate at low gas and air pressures, and wide limits of performance control. Burners of this type are designed for heating forging and thermal furnaces, dryers.

Rice. 16.10. Turbulent burner type GNP 1 - body, 2 - nozzle, 3 - nozzle tip type A, 4 - nozzle tip type B, 5 - spout

Non-hollow premix burner – a burner in which the gas is not completely mixed with air before the outlets. Atmospheric gas burner – injection gas burner with partial preliminary mixing of gas with air, using secondary air from the environment surrounding the torch.

An atmospheric burner designed for installation in the furnace of four- and five-section cast-iron boilers (VNIISTO-Mch) is shown in Fig. 16.8. The burner head has 142 holes with a diameter of 4 mm and is placed on the ejection tube. The head has no holes where the gas-air mixture exits the ejector. If holes are placed here, the flame above them will be significantly higher than above other holes, since when gas flows out of these holes, the dynamic pressure of the gas-air mixture flow moving from the ejection tube to the burner head will be used. In addition, due to the increased exit speed, the flame above these holes may not be stable enough. The thermal load of the burner is 20 kW (0.2 m3/h at QCK == 36 MJ/m3). The burner is designed to burn gas with a calorific value QCH = 25,000...36,000 kJ/m3, and the nozzle diameter is changed depending on the QCH value. When burning natural gas with a calorific value of 36,000 kJ/m3, the nozzle diameter is 4 mm, and the required gas pressure is 1.3 kPa. The burner primary air ratio can be adjusted with an air washer. The ejection tube has a flow part with low hydraulic resistance. The burner head is designed in such a way that secondary air approaches each row of holes from one side. The flame height when the burner is operating at normal heat load is approximately 100 mm. The burner is simple in design and reliable in operation. When operating in cast iron sectional boilers, atmospheric burners ensure complete combustion of gas with a relatively low content of nitrogen oxides in the combustion products. The NO X concentration usually does not exceed 0.12 g/m3. This is due to the dispersion of the flame and the staged combustion of gas (with primary and secondary air).

Rice. 16.8. Atmospheric burner for cast iron boiler 1 - air regulator, 2 - nozzle, 3 - ejection tube; 4- burner head with fire holes

An atmospheric burner with one outlet is shown in Fig. 16.9. The peculiarity of this burner is that its head does not have a manifold with a large number of small holes, but a conical tube with one hole of large diameter (40 mm). As a result, the burner flame lengthens significantly. Due to the vacuum in the furnace, secondary air flows through the annular gap between the burner and the special casing to the root of the torch. The burner has the ability to regulate the amount of primary and secondary air. Such burners are used when converting to gas fuel restaurant stoves and food boilers (the stove may have one burner or a block consisting of two or three burners). The heat load of the burner is 18.6 kW, gas pressure is 1.3 kPa. The burner is designed to burn gas with a calorific value Q with n = 36,000 kJ/m3. Depending on the heat of combustion of the gas, a nozzle of the appropriate diameter is installed in the burner.

Rice. 16.9. Atmospheric burner with one outlet 1 - burner head, 2 - ejection mixer, 3 - regulator, 4 - nozzle, 5 - primary air regulator

Special purpose burner – a burner, the principle of operation and design of which determines the type of thermal unit or the features of the technological process.

Recuperative burner – burner equipped with a recuperator for heating gas or air

Regenerative burner – a burner equipped with a regenerator for heating gas or air.

Automatic burner – burner equipped automatic devices: remote ignition, flame control, fuel and air pressure control, shut-off valves and controls, regulation and alarm.

Turbine burner – a gas burner in which the energy of escaping gas jets is used to drive a built-in fan that forces air into the burner.

Pilot burner – auxiliary burner used to ignite the main burner.

The most applicable classification of burners today is based on the method of air supply, which are divided into:

– blowless – air enters the furnace due to rarefaction in it;

– injection – air is sucked in due to the energy of the gas stream;

– blowing – air is supplied to the burner or furnace using a fan.

Block ejection (injection) burners type B and G, developed by Promenergogaz. Burners of this type are a series of burners of different configurations and performance, assembled from standard elements. A standard burner element consists of a set of single mixers of the same type 2 (Fig. 16.4, a), fixed in a common manifold - gas chamber 3. A single mixer is a pipe with a diameter of 48X3 mm and a length of 290 mm. In the initial part of the pipe, which is located inside the gas manifold, there are four holes with a diameter of 1.5 mm each, the axes of which are located at an angle of about 25° to the burner axis. These holes act as peripheral nozzles through which gas flows into the ejection pipe and ejects air entering through the open end of the pipe. The design of the ejection part is designed in such a way that at a vacuum in the furnace of 20 Pa, the gas ejects all the air necessary for combustion with an excess coefficient a = 1.02...1.05. High velocities of gas jets located along the periphery help create a velocity profile that prevents flame penetration. The burner blocks are lined with a refractory mass (see Fig. 16.4, b), and at their outlet there is a stabilizer tunnel 100 mm deep. It prevents the flame from coming off. The burners are completely located within the 510 mm thick boiler lining. The nominal gas pressure in front of the burner is 80 kPa (average pressure), the depth coefficient of capacity control is 3.4...3.8. Depending on the layout (number of individual elements), the burner productivity varies from 10 to 240 m3/h. BIG burners operate without chemical incomplete combustion with small excess air. The content of nitrogen oxides is 0.15 .. 0.18 g/m3. Burners are arranged in the form of standard sets (see Fig. 16.4, c), consisting of single ejection tubes assembled into one row of G standard sizes), two rows of F standard sizes) and three rows of B standard sizes). The burners are intended for equipping boiler units located in the lining of the boiler walls and on the hearth instead of the grate. Boilers equipped with BIG burners have a higher efficiency (by 2%) than when equipped with ejection burners with centrally located nozzles.

Gas burners are used at different gas pressures: low - up to 5000 Pa, medium - from 5000 Pa to 0.3 MPa and high - more than 0.3 MPa. Burners are used more often, of great importance thermal power gas burner, which can be maximum, minimum and nominal.

During long-term operation of the burner, where gas is consumed large quantity without flame separation, maximum thermal power is achieved.

The minimum thermal power occurs with stable burner operation and the lowest gas consumption without flame slip.

When the burner is operating at nominal, providing maximum efficiency at the highest combustion completeness, the gas flow rate reaches the rated thermal power.

It is allowed to exceed the maximum thermal power over the nominal by no more than 20%. If the rated thermal power of the burner according to the passport is 10,000 kJ/h, the maximum should be 12,000 kJ/h.

Another important feature of gas burners is the range of heat power control.

Today, a large number of burners of various designs are used.

The burner is selected according to certain requirements, which include: stability under changes in thermal power, reliability in operation, compactness, ease of maintenance, ensuring complete combustion of gas.

The main parameters and characteristics of the gas burner devices used are determined by the requirements:

– thermal power, calculated as the product of the hourly gas consumption, m 3 / h, by its lower calorific value, J / m 3, and is main characteristic burners;

– parameters of the burned gas (lower calorific value, density, Wobbe number);

– rated thermal power, equal to the maximum power achieved during long-term operation of the burner with a minimum “excess air coefficient a and provided that the chemical underburning does not exceed the values ​​​​established for this type of burner;

– nominal gas and air pressure corresponding to the rated thermal power of the burner at atmospheric pressure in the combustion chamber;

– nominal relative length of the torch, equal to the distance along the axis of the torch from the outlet section (nozzle) of the burner at rated thermal power to the point where the carbon dioxide content at α = 1 is equal to 95% of its maximum value;

– coefficient of limit control of thermal power, equal to the ratio of the maximum thermal power to the minimum;

– coefficient of operating regulation of the burner in terms of thermal power, equal to the ratio of the rated thermal power to the minimum;

– pressure (vacuum) in the combustion chamber at rated burner power;

– thermal technical (luminosity, emissivity) and aerodynamic characteristics of the torch;

– specific metal and material consumption and specific energy consumption, related to the rated thermal power;

– sound pressure level created by a working burner at rated thermal power.

Burner requirements

Based on operating experience and analysis of the design of burner devices, it is possible to formulate the basic requirements for their design.

The design of the burner should be as simple as possible: without moving parts, without devices that change the cross-section for the passage of gas and air, and without complex-shaped parts located near the burner nose. Complex devices do not justify themselves during operation and quickly fail under the influence of high temperatures in the working space of the furnace.

The cross sections for the exit of gas, air and gas-air mixture should be worked out during the creation of the burner. During operation, all these sections must remain unchanged.

The amount of gas and air supplied to the burner should be measured by throttling devices on the supply pipes.

The cross sections for the passage of gas and air in the burner and the configuration of the internal cavities should be selected in such a way that the resistance to the movement of gas and air inside the burner is minimal.

The gas and air pressure must mainly provide the required speeds in the outlet sections of the burner. It is desirable that the air supply to the burner be adjustable. Unorganized air supply as a result of vacuum in the working space or through partial injection of air by gas can only be allowed in special cases.

Gas supply to buildings

Gas supply to buildings- gas supply using a gas pipeline system, through which gas from the city distribution network is supplied to gas appliances installed at consumers. Gas supply system includes: subscriber branches connected to the city distribution network and supplying gas to the building; intra-house gas pipelines that transport gas inside the building and distribute it between individual gas appliances.

The subscriber branch consists of a gas inlet to the consumer's territory, in-yard gas pipelines and gas inlets into the building. At the gas inlet to the consumer, at a distance of at least 2 m from the building line, a valve or tap is installed in the well. One disconnecting device is installed for a group of residential buildings served by one input.

Rice. Building gas supply diagram: 1 - street low-pressure gas network; 2 - yard gas pipeline; 3- condensate collector; 4 - gas input; 5 - shut-off valves; 6 - gas distribution pipeline; 7 - risers; 8 - floor wiring; 9 - gas appliances; 10-carpet; 11 - valve

Entrances to consumer premises and the yard gas network are usually laid in the ground. The conditions for their installation do not differ from the conditions for laying underground urban gas pipelines. Inputs of gas pipelines into residential and public buildings can be carried out: in each stairwell; directly into the kitchens of residential buildings or into the premises of societies, buildings where gas is consumed; in the basements of buildings with technical equipment. corridors. For dry gas, it is advisable to make inlets through walls above the foundations. Entry device into the building through technical equipment. corridors are allowed under the following conditions: with a corridor height of at least 1.6 m; if there are at least two entrances to the corridor from the outside, not connected to other parts of the building; with natural exhaust ventilation in the corridor, providing at least one air exchange; electric corridor lighting must be explosion-proof; for fire resistant ceilings. The installation of inputs directly into residential premises, elevator machine rooms, pump rooms, ventilation chambers, etc. is not allowed.

Intra-house gas pipelines are divided into risers that transport gas in a vertical direction, and intra-apartment gas pipelines that supply gas from the risers to individual gas appliances. Gas risers are usually installed in staircases and kitchens. Laying risers in residential premises and in bathrooms and toilets is prohibited. To shut off individual sections of gas pipelines, taps are installed: at the entrances to the building, in apartments in front of each gas appliance.

Bronze (brass) and combination taps with tension plugs are placed in front of meters and gas appliances. Bronze or cast iron plug tension taps or valves are installed at the entrances to the building. On risers, branches to apartments and in front of each gas appliance after the taps, counting as the gas flows, downpipes necessary for repair work are installed.

Gas pipelines inside buildings are made of steel pipes. The pipes are connected by welding or threading. The use of pipes made of plastics (vinyl plastic, polyethylene, etc.) is promising. Gas pipelines in buildings are laid openly at a height of at least 2.0 m from the floor to the bottom of the pipe; when supplied with wet gas - with a slope of at least 0.002 from the meter to the riser and from the meter to gas appliances. When crossing staircase floors and hollow or filled-in walls, gas pipelines are enclosed in cases made of steel pipes.

The main appliances used for gas supply: stoves, water heaters, food boilers, ovens and boilers. Household gas stoves and water heaters are installed in apartments. The same devices are used by public and small utility consumers. Food and beverage enterprises are equipped with more powerful restaurant-type gas stoves, cooking boilers, ovens, boilers and water heaters. In low-rise buildings with stove heating, gas can also be used to heat stoves. Gas meters are used to measure gas consumption among consumers. Gas meters are not installed in new residential buildings.

Most gas appliances must have flue gases vented through chimneys into the atmosphere. In newly designed buildings, flue gases are removed from each appliance through a separate chimney. In existing buildings, it is allowed to connect three gas appliances to one chimney, located on the same or different floors. Combustion products are introduced into the chimney at different levels, at a distance of at least 500 mm from each other. Gas appliances are connected to chimneys using roofing steel pipes, the diameter of which is determined depending on the thermal load of the appliance: up to 10,000 kcal per hour - from 100 to 125 mm, up to 20,000-25,000 kcal per hour - from 125 to 150 mm. The vertical section of the connecting pipes from the gas appliance nozzle to the first turn of the pipe must be at least 0.5 mm. In rooms with a height of up to 2.5 m it is allowed vertical section 0.3 m. The total length of the horizontal section of the pipe is no more than 3 m, and in existing buildings no more than 6 m, and there should be no more than three turns along the entire length of the connecting pipe. Pipes are laid with a slope of at least 0.01 towards the gas appliance and only in non-residential premises. Chimneys, as a rule, are installed in the internal main walls of buildings. Chimneys should not have horizontal sections, and below the entrance of the connecting pipe into the chimney, it is necessary to arrange a pocket with a depth of at least 250 mm with a hatch for cleaning it.

During normal operation of gas appliances, the vacuum value at the point where combustion products exit the draft breaker should be 0.4-0.7 mm of water. Art.

depending on the type of device. At low vacuum, some of the combustion products escape into the room, and in some cases the draft overturns. The cross-section of the chimney is determined by calculation. For water heaters with a heat load of 20,000-25,000 kcal/hour, the cross-section should be no less than 150 cm2.

Liquefied hydrocarbon gases are used for gas supply. Liquefied gas is stored in cylinders, which, depending on the size, are installed directly in the kitchen, in a metal container. cabinet outside near the wall of the building or buried in the ground. In the first two cases, gas flows through short connecting pipes directly to gas appliances, and in the latter, underground in-yard gas pipelines run from a tank located in the ground, transporting gas to one or more buildings.

Gas pipelines are tested with air after an external inspection and elimination of all visible defects. External gas pipelines - customer branches - are tested similarly to city gas pipelines. The internal gas network of residential and public buildings is checked for strength and density. The strength test of low pressure gas pipelines is carried out at a pressure of 1 am. Gas pipelines of residential buildings are tested for density at a pressure of 400 mm of water. Art. with an installed meter and connected gas appliances.

Gas appliances

In residential and public buildings gas is used for cooking and hot water. The main appliances used to supply gas to buildings are stoves, water heaters, boilers, digesters, ovens and refrigerators. The operation of gas appliances is characterized by the following indicators: 1) thermal load, or the amount of heat in the gas that is consumed by the appliance, in kW; 2) productivity, or the amount of useful heat that is transferred to the heated body, in kW; 3) Efficiency, which is the ratio of performance to the thermal load of the device. The nominal load is considered to be the load at which the gas appliance operates most efficiently, i.e. with the least chemical underburning of gas, the highest efficiency, and develops rated productivity. At rated load in structural elements The device should not experience dangerous thermal stresses that shorten its service life. The maximum (maximum) thermal load is considered to be a load exceeding the nominal load by 20%. At this load, the performance of the device should not noticeably deteriorate. Gas appliances installed in residential and public buildings operate at low pressure and are equipped with atmospheric ejection burners. Household gas stoves are made with two, three and four burners with or without ovens. They consist of the following main parts: a body, a worktop with burner inserts, an oven, gas burners (top burners, as well as for the cabinet), a gas distribution device with taps. The parts of household stoves are made from thermally resistant, corrosion-resistant and durable materials. The surface and parts of the stove (except for the back wall) are covered with white enamel. The height of the working table of household stoves is 850 mm, and the width is at least 500 mm. The distance between the centers of adjacent burners is 230 mm. The burners have the following rated loads: normal power 1.9 kW, increased power - 2.8 kW. Four-burner stoves may have one high-power burner. The rated load of the burners should ensure uniform heating of the oven to a temperature of 285...300 °C in no more than 25 minutes. By current GOST The efficiency of burners must be at least 56%, and the efficiency of stoves with combustion products discharged into the chimney must be at least 40%. The content of carbon monoxide in combustion products when operating burners at rated load should not exceed 0.05% in terms of dry flue gases and excess air equal to one (a = 1). Adjusted burners must operate stably, without flame separation or slippage, when the heat of combustion of gas changes within ±10% and the heat load is from the maximum to 0.2 nominal. Household gas stoves are equipped with atmospheric burners with combustion products vented directly into the kitchen. Part of the air required for combustion (primary air) is ejected by gas flowing from the burner nozzles; the rest (secondary air) enters the flame directly from the environment. Air enters the oven burners through special slots and holes in the stove. The combustion products of the burners pass through the gap between the bottom of the cookware and the work table of the stove, rise along the walls of the cookware, heating them, and enter the surrounding atmosphere. Combustion products heat the oven and enter the kitchen through holes in the side walls or rear wall of the stove. The removal of combustion products directly into the room places high demands on the design qualities of the burners, which must ensure complete combustion of the gas. The main reasons causing chemical incomplete combustion of gas in hotplate burners are: a) the cooling effect of the walls of the cookware, which can lead to incomplete flow chemical reactions combustion, formation of CO and soot; b) unsatisfactory mixing of gas with primary air in the flow part of the ejector; c) poor organization of the supply of secondary air and removal of combustion products. To eliminate these reasons, it is necessary to design the gas burner devices of the stove so that the following conditions are met: a) the burners must operate with the maximum primary air coefficient, ensuring a stable flame at all capacities; b) the location of the burner in relation to the bottom of the cookware should ensure good washing of combustion products and exclude the possibility of the internal cone of flame coming into contact with its bottom; c) the distance between the bottom of the cookware and the burner must be optimal, since as this distance increases, excess air increases and the efficiency of the burner decreases, and with a decrease, the chemical incompleteness of combustion increases. The optimal distance depends on the heat load, the primary air coefficient, the size of the burner hole and the bottom of the cookware. For burners with a heat load of 1.75...1.9 kW with a burner hole diameter of 200...220 mm, the optimal distance is approximately 20 mm; d) the profile shape of the flow part of the ejection tube must be optimal; e) the removal of combustion products through the gap between the bottom of the cookware and the work table is ensured (the gap must be at least 8 mm). In order for the stoves to operate on gaseous fuels with different calorific values, several replaceable nozzles with hole diameters corresponding to the calorific value of the gas and the nominal pressure are used. To prevent accidental opening, the taps of all burners must have locking position locks. The oven tap handle must be different from other handles in shape or color. The walls of the oven must have thermal insulation in the form of an air gap or layer insulating material so that the temperature on the surface of the plate does not exceed 120 °C. A four-burner PGU stove has a work table with four vertical burners, shown in Fig. 19.3.

Rice. 19.3. Atmospheric gas burner for a household stove 1 - ejection tube. 2 - cap, 3 - damper for regulating primary air, 4 - nozzle

The stove has a frying and drying cabinet. A viewing glass is built into the oven door. The oven is insulated with slag. The stove table is closed and equipped with rod burner grates. The oven is located in the middle part of the stove and is heated by an atmospheric burner, the head of which is made in the form of a ring tube. In a vertical burner, the holes in the head have exit sizes and pitches that prevent the flames from merging. To spread the flame along the fire holes, the stamped steel cover has a flange, which is located above the burner torches. It provides ringing of the flame, creating conditions for the ignition of adjacent torches and ensuring combustion stability with respect to flame breakthrough. Instantaneous and capacitive water heaters are heat exchangers used for local hot water supply. For instantaneous water heaters, the hot water preparation mode corresponds to the consumption mode. They heat water to 50...60 °C and dispense it 1...2 minutes after turning on the device. They are often called fast-acting. For cylinder water heaters, the water preparation mode may not correspond to its consumption mode. The water in tank water heaters is heated to 8O...9O°C. Water heaters must meet the following requirements: 1) Their efficiency must be at least 82%. Water heaters should operate normally at a tap water pressure of 0.05 to 0.6 MPa. A constant temperature of hot water should be created within 1...2 minutes after turning on the device. In cylinder water heaters, water heats up in 60... 70 minutes. Water heaters have draft breakers and backdraft preventers. The temperature of combustion products in front of the draft breaker must be at least 180 °C. The outer surface of the water heater is covered with white enamel; the surface temperature when the device is operating at rated load should not exceed the ambient temperature by more than 50 °C; 2) water heaters must be equipped with main and pilot burners. The pilot flame instantly ignites the gas on the main burner. Its maximum flow rate through the ignition burner at nominal pressure is 35 l/s. The main burner flame should be steady. The flame height of instantaneous water heaters should not exceed 80 mm at rated load and 150 mm at maximum load. Burners must ensure stable gas combustion without flame separation or flashover when the heat load changes from 0.2 to 1.25 nominal. When operating at maximum load, the content of carbon monoxide CO in combustion products should not exceed 0.1% of the volume of dry products at a theoretical air flow rate a=1; 3) each water heater must be equipped with blocking and safety devices that allow gas to flow to the main burner only when the pilot light is lit and stop supplying it when the pilot goes out. Instantaneous water heaters are equipped with safety devices, thanks to which the main burner turns off if the hot water supply stops or if its pressure drops below the set limit. Capacitive water heaters are equipped with automatic hot water temperature control, which ensures that the main burner is turned off when the water is heated above a predetermined value. Instantaneous water heaters consist of the following main parts: 1) a heat exchanger, including a fire chamber, a coil and a heater; 2) gas burner with igniter; 3) a gas exhaust device with a draft breaker and a reverse draft fuse; 4) blocking, safety and regulating devices; 5) outer metal enameled casing; 6) water system with taps and shower net. An automatic instantaneous water heater VPG, designed for multi-point water supply, is shown in Fig. 19.5. Nominal

The thermal load of water heaters of the VPG type is 21...23 kW.

Selecting a burner correctly is an important step in the construction or repair of a boiler room. The further operation of the heating equipment depends on how responsibly the managers and organizers approached this issue.

Modernization of the heating sector is the most important task facing managers of housing and communal services. Choosing a partner for the design, supply, installation and commissioning of equipment is not a problem, but the question of the efficiency of operation of boiler houses after their conversion remains open. A limited budget forces you to find the most simple solutions– purchase cheap, short-lived equipment that requires constant attention. But now there are fully automated systems, for the selection and maintenance of which it is best to contact highly qualified specialists who have a complete understanding of how a modern boiler room should function.

When choosing burners, consumers are faced with a difficult task: what to give preference to - domestic or foreign equipment. And here sellers of imported burners often use a cunning trick: they compare smooth two-stage burners of foreign production with modulated burners of domestic production. Even with a significant difference in prices for “similar” products, they insist on German, Finnish, Italian quality, trying to persuade buyers to purchase these particular burners. However, any specialist working with boiler equipment understands what to compare different types burners only in terms of the price component is at least incorrect. Therefore, it is necessary to know the difference between them technical characteristics and opportunities.

The most widespread in boiler houses are two-stage, smoothly two-stage and modulating burners. Two-stage burners, as the name suggests, have two power levels. The first stage provides 40% of the power, and the second - 100%. The transition from the first stage to the second occurs depending on the controlled boiler parameter (direct water temperature or steam pressure), the on/off modes depend on the boiler automation.

Smooth two-stage burners allow a smooth transition from one stage to the second. This is a cross between a two-stage and modulating burner. Modulating burners heat the boiler continuously, increasing or decreasing power as needed. The range of combustion mode changes is from 10 to 100% of the rated power.

Of course, modulating burners are more expensive than stepped models, but they have a number of advantages over them. The mechanism for smooth power control allows you to reduce the cycle of turning on and off boilers to a minimum, which significantly reduces mechanical stress on the walls and components of the boiler, and therefore prolongs its “life”. Fuel savings are at least 5%, and with proper tuning you can achieve 15% or more. And finally, installing modulating burners does not require replacing expensive boilers if they are functioning properly. When staged burners operate, the boiler experiences significant loads, which eventually destroy the unit.

Against the background of the disadvantages of stepped burners, the advantages of modulating burners are obvious. The only factor forcing managers to choose step models is their lower price. But savings of this kind are deceptive: wouldn’t it be better to spend a large sum at a time on more advanced, economical and environmentally friendly burners, especially since these costs will pay off in the next few years?

Smart managers understand the benefits of using modulating burners, and now all they have to do is select the necessary models. Which manufacturers are best to contact? Even with a superficial study of prices for imported and domestic burners, it is clear that the difference is quite significant. Some models from foreign manufacturers are more than twice as expensive as Russian-made products. And yet, stereotypes that quality goods come only from abroad force people to pay more. However, a more detailed analysis of the market for burner manufacturers shows that we also have high-quality competitive products. For more than 15 years, the Starorussian Instrument-Making Plant has been producing various models of burners that are successfully installed on all types of domestic and imported boilers. Modulating block burners from this manufacturer comply with all environmental standards for fuel combustion, have a wide range of power control (from 10 to 100%), while ensuring maximum efficiency. When looking for reliable, economical burners for boiler rooms, it’s simply impossible not to pay attention to them. Easy installation equipment is already producing tangible results, and if experienced burner adjustment specialists are involved in the process, fuel savings can amount to more than 15%. With the use of modulating burners from Staroruspribor, managers will be able to temporarily forget about another cost item - replacing the boiler. Switching to a “gentle” operating mode allows you to double its service life. Those who know how expensive such equipment is (prices are calculated in millions of rubles) will appreciate the possibility of replacing these units more rarely.

Selecting a burner correctly is an important step in the construction or renovation of a modernized boiler room. The further operation of the heating equipment depends on how responsibly the customers approach this issue. If, for example, you use modulating burners produced by JSC Staroruspribor Plant, then after two or three heating seasons the costs will more than pay off. Stable operation, compliance with environmental standards, longer service life of boilers and the ability to fully automate the operation of a thermal power plant indicate significant advantages of using modulating burners in boiler houses. And if the benefit from their operation is obvious, not taking advantage of it is simply unreasonable.

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Life far from the equator dictates its own laws. As the outside temperature drops, the houses inside also cool down. In this review, we will consider a solution to the problem by choosing the best gas heaters - from portable ones (for a tent) to convectors for a home or cottage, which can replace a gas boiler.

Types of gas heaters

Gas convectors

Such heaters can have a closed or open combustion chamber. Closed-type models for gas combustion take air from the street and discharge combustion products there through a special pipe laid through the wall. They are well suited for a home or cottage and can become an alternative to a gas boiler. Models with an open combustion chamber are not very suitable for residential premises or require the use of a vertical chimney.

Catalytic gas heaters

Devices of this type operate by oxidizing substances on the surface of the catalyst, which releases a large amount of heat. The process occurs almost silently and without flame. The catalytic combustion method is more reliable, efficient and safe compared to conventional combustion methods. infrared heaters.

Ceramic gas heaters

By analogy with their electric counterparts, such heaters operate due to directed thermal radiation and heat not the air, but the surfaces of walls, objects, and also people present in the room. The only heating source is a gas burner. The use of ceramic plates allows for complete combustion of fuel and eliminates harmful emissions.

Thermal gas guns

They have a cylindrical shape and operate on the principle of a fan heater, in which the role heating element performed by a gas heat generator. They are powered by bottled gas, and the power is usually regulated by a gearbox.