Types of gas burners. Classification of gas burners
GAS-BURNERS
Classification of gas burners
All stages of the combustion process (mixture formation, heating, combustion) are carried out in a gas burner and a combustion chamber (combustion chamber). The main functions of the gas burner are as follows:
1. Supply of gas and air to the furnace space;
2. Mixture formation;
3. Stabilization of the ignition front at all permissible loads.
The burner device contains three main elements. The first element is mixing device. With the kinetic method, a homogeneous gas-air mixture is created in the mixing device with a coefficient α ≥ 1. With the diffusion method, the mixing device creates only the necessary prerequisites for the mixing process to proceed. The very process of mixture formation proceeds completely in the combustion chamber or partially begins in the gas burner. The second element of the burner - head with one or more fire holes. The head provides DHW outlet to the combustion chamber or to open space. The main purpose of the head is to stabilize the ignition front, prevent flashover and flame separation. The third element of the burner - firing unit. The fire part is a loophole or tunnel made of refractory material, where the combustion process partially or completely takes place. The firing section additionally stabilizes the combustion front. In many burner devices, there is no firing section.
The main classification of burners is based on the way the gas is burned, i.e. what method of gas combustion is implemented in the burner. According to the method of gas combustion All burners are divided into four groups:
1. Burners for complete preliminary mixing of gas with air (kinetic combustion is realized);
2. Burners for preliminary mixing of gas with part of the air necessary for combustion (kinetic-diffusion combustion is implemented);
3. Burners with incomplete preliminary mixing of gas with air (diffusion-kinetic combustion is realized);
4. Burners without preliminary mixing of gas with air (diffusion combustion is realized).
By way of air supply burners are divided into:
1. Ejection (injection) - air is supplied due to the energy of the gas jet;
2. Blow-free - air enters the furnace due to rarefaction;
3. Blast - air is supplied to the furnace by a fan.
By gas pressure there are burners of low pressure (up to 5 kPa) and medium pressure (from 5 kPa to 0.3 MPa). High pressure burners are rarely used.
In addition, burners are distinguished by their location in the furnace (arched and hearth), by type of fuel (gas-oil), by the emissivity of the flame (infrared radiation), by the type of field superimposed on the flame (acoustic, electrical) and other characteristic differences.
Gas equipment requires proper selection and installation, which must comply with accepted standards. In this case, it will work correctly. To choose the optimal type of such devices, it is necessary to consider the classification of gas burners. There are several main characteristics that distinguish this equipment. burners will be discussed next.
Advantages of gas equipment
Considering the characteristics and classification of gas burners, it should be noted that such equipment is very popular today. This is due to a host of benefits. Gas is one of the available types of fuel for the population. Its cost remains acceptable for most consumers. If a gas main passes near the dwelling, it is not advisable to use other types of energy for domestic needs.
There are many types of gas burners. They are used in various fields of human activity. You can choose a device that will optimally match the existing operating conditions. The power of the unit may be different.
To choose the best option, you need to consider in detail the classification and characteristics of the burners. Their device is quite simple. It does the presented equipment reliable in use. According to this indicator, gas appliances are an order of magnitude superior to liquid fuel heaters.
Modern equipment of the presented type is produced using innovative technologies. Their work is automated. This guarantees high comfort during the operation of the burner, the absence of failures and malfunctions. This greatly increases the safety of equipment operation.
Burner features
To select the right type of equipment, it is necessary to consider the general purpose of gas burners. Classification allows you to select several groups among the variety of equipment. A gas burner is a device that mixes oxygen and gas, and then delivers this mixture to the outlet. When ignited, a stable torch is formed.
How gas burners are arranged, the mixture is supplied through pipelines under pressure. Air and oxygen are combined into a single substance in a special device. When it leaves the system, the fuel mixture ignites. A constant, steady flame is formed. Such equipment is used for domestic and industrial purposes. It is installed in various boilers.
There are two main types of burners on the market today. They are separated according to the principle of preparation of a combustible composition. There are atmospheric and inflatable devices. The first type of burners is also called injection burners. Inflatable varieties can be called ventilation.
Injector varieties are almost always part of the heating unit. They are supplied with it in the kit, are included in the price of the boiler. Inflatable burners are sold separately. They are more efficient, since the air supply to the structure is carried out using a fan.
Gas burner systems perform 4 functions. They mix gas with air in the correct proportion and then feed them to the combustion front. Also an important function of the apparatus is the stabilization of the ignited torch. It should not deviate from the established level. The burner provides the necessary intensity of heat release. Therefore, the choice must be made, focusing on the power requirements of the equipment.
Main differences
Classification of gas boilers and burners is carried out according to various criteria. Such equipment differs in its power. To do this, take into account the features of the operation of the burner. The larger the volume you need to heat, the more powerful the burner will be.
Gas equipment differs in the way air and fuel are mixed. This affects the efficiency of the equipment. Supercharged models are more efficient. Their level of efficiency is higher.
In different models, the flow of the mixture is not the same. Therefore, you need to familiarize yourself with the main performance characteristics of the device before buying.
Burners are made from different materials. Most often these are alloys or metals. They must be of appropriate quality.
Also, certain changes can be made to the design of many burners, which must comply with the manufacturer's instructions. They are carried out with the help of accessories for adjustment. When buying, pay attention to them. The choice must be made according to personal preference. Adjustment should be comfortable.
Main varieties
There is a classification of gas burners by purpose. They are divided into two groups. These can be special or universal devices. The first category includes burners that can only be used in boilers of a certain design. For other ovens, this equipment will not work. Universal burners have a wide range of applications. They are mounted on most modern designs of furnaces and boilers.
According to the method of creating a fuel mixture, three categories of burners are distinguished. In addition to gas, oxygen is always present in the fuel mixture. The equipment can mix these ingredients in different ways. There are blast, injection and diffuse burners. The first category includes equipment in which air is supplied by the injection method. In injection burners, the air to create the fuel mixture is supplied by suction. Diffuse structures are characterized by a natural influx of air that comes from the environment.
In such equipment, gas can be supplied in thin streams, flowing at a certain angle to the air flow. Also, in some designs, the technology of dividing the fuel into many small streams or twisting them is used.
Other classifications
Considering the types and principle of operation of gas burners for boilers, other classifications should be distinguished. The presented equipment may differ in terms of the calorific value of the fuel that is burned in the unit.
The first group on this basis includes high-calorie burners. Their heat of combustion is maximum. Such equipment releases a lot of energy, allowing you to heat large volumes. The minimum calorific value of fuel in such equipment is 20 MJ/m³. the presented category of equipment is designed to operate on natural gas or associated products of petroleum gaseous substances.
The second group includes medium calorie burners. They are designed for coconut gas or its equivalents. The heat of combustion in such equipment is 8-20 MJ/m³.
Low-calorie burners include appliances in which the calorific value of fuel does not exceed 8 MJ / m³. They are used in the processes of combustion of blast furnace or producer gas.
In addition, the equipment is overpressure. It can be low, medium and high. The latter option is quite rare. The excess pressure of such units is more than 30 kPa. Medium and low pressure burners are much more commonly used. They are suitable for high calorific gases. The overpressure of medium burners is 5-30 kPa. Low pressure devices are characterized by this indicator, which is at a level of less than 5 kPa.
Flame localization
Considering the classifications and designs of gas burners, one more principle of equipment difference should be noted. Such devices may have different localization of the flame. Fire can form in a free torch. In some designs, the flame is localized in a granular, porous or perforated mass. This material is non-flammable.
Flame localization can also be observed in a special tunnel or combustion chamber made of refractory material. There are designs of burners in which the fire appears directly on the refractory surface.
Depending on the type of such a device, the scope of the equipment is also determined. So, burners in which the flame is formed in a refractory tunnel and a free flame are installed in boilers for heat carriers (water, special liquids based on antifreeze, air, etc.).
If the device burns gas in a porous mass or on a surface of refractory material, they are installed in heaters of a different type. The principle of their work is based on infrared radiation for heating.
Knowing the existing classifications, you can choose the right type of equipment for a particular boiler. At the same time, the operating conditions of the heater are taken into account. A properly selected burner will operate for many years without requiring repair or replacement.
burner requirements
The existing classifications of gas burners for heating boilers allow you to choose the right equipment. You also need to know the basic requirements that are put forward for such products. You can only purchase a burner if the product has the appropriate certificate. Their main types are mass-produced, they must comply with existing standards.
Gas in them must be passed in a certain amount. It must be completely burned. The air flow rate for most types of burners is minimal. During operation, the equipment must ensure the amount of emissions at the minimum allowable level.
Considering the classification of burners and the basic requirements for such equipment, it should be noted that the noise level during operation should not exceed 85 dB. The flame should not slip, separations are also unacceptable.
If the system operates on the principle of full premixing, the feed rate of the mixture must exceed the flame propagation speed. It is also worth paying attention to the design. It should be simple. This allows you to carry out an audit or repair if necessary.
Diffuse burners
Having studied the classification of gas burners for boilers, we can distinguish the main three groups of equipment presented. One of the popular types is a diffuse type product. In this device, air is supplied to mix with the gas from the environment. This process is provided by diffusion.
Diffuse burners are often installed in household appliances. This type of equipment allows the flame to be distributed over a large area. Air does not enter the burner body. It mixes with the gas outside the equipment. Therefore, the second name for diffuse varieties is "external mixing burner".
A simple design consists of a pipe in which holes are drilled at a certain distance. The thermal power of such a design is small. Diffuse type burners are designed to burn natural gas. They are installed in small water heaters that are used in everyday life. More complex designs are used in the industrial heating process.
Injection burners
In the classification of gas burners, an important place belongs to injection varieties. The gas-air mixture is formed in this case under the influence of a jet of fuel. The main element of the design is the injector. It sucks in air from the environment.
The main structural elements are the nozzle, the primary air regulator, as well as the collector and mixer. Each of these elements performs a specific function. So, the nozzle is needed to convert potential energy into kinetic energy. The regulator controls the amount of primary air supplied to the burner.
Air leakage and vacuum creates an injector. The confuser is the narrowest part of the mixer. It serves to equalize the jet of the mixture. The final mixing of its ingredients takes place in a diffuser. By reducing the speed, its pressure increases.
The collector distributes the mixture over all the openings of the system. The shape of this part and the distance between the holes depend on the purpose of the equipment.
Blast burners
In the classification of gas burners, the most economical are blast designs. They are distinguished by the ability to smoothly adjust the power level. This allows you to increase the efficiency. Gas in this case is spent more rationally. Such equipment is quite noisy, but for consumers, one of the main requirements is the efficiency of the burner. Therefore, it is the blast varieties that are most popular today.
There are three types of blower burners. In the first group, complete pre-mixing of gas and air is used. The second type of blast burners has partial premixing. The third category is equipment without pre-mixing.
Having considered the classification of gas burners, you can choose the best type of equipment for your needs.
Gas burners are devices designed for the formation of combustible gas-air mixtures and stable combustion at the required thermal power. In accordance with GOST 17357-71, gas burners are classified according to the method of supplying air for combustion, the nominal pressure of gas and air, the calorific value of the gas, the rated heat output, the length of the torch and the method of torch stabilization. According to the method of air supply, burners are distinguished: with air supplied to them from the environment due to rarefaction or convection; providing mixture formation due to the injection of air with gas or gas with air; with forced air supply, including without its preliminary mixing with gas and with preliminary mixing. According to the nominal gas pressure, there are burners of low (up to 500 kg / m 2), medium (over 500 to 10,000 kg / m 2) and high (over 10,000 kg / m 2) pressure. Accordingly, the nominal pressure of the air supplied to the burner is divided into low (up to 100 kg / m 2), medium (over 100 to 300 kg / m 2) and high (over 300 kg / m 2). The main indicators of the burner are: the luminal heat output, the nominal gas and air pressures corresponding to it, and the burner control limits for heat output. Additionally, the burner is characterized by the nominal length of the flame (relative to the caliber of the outlet), specific metal content, pressure (vacuum) in the combustion chamber and noise qualities.
Consider some designs of individual burners, which are typical representatives of the above groups. A low-pressure hearth burner (Fig. X.9) is a pipe plugged at one end 1 with two rows of holes located at 90° to each other. The pipe is placed in the slot 3, formed by refractory bricks. The gas coming out of the holes is switched over with the air entering the gap due to rarefaction in the furnace. The adopted spacing between the holes ensures sufficient air flow to the torches and the movement of the flame from one hole to another. The incandescent walls of the slot reliably stabilize the combustion process, and for directed air flow into the slot, the side parts of the grate 5 covered with bricks 4.
The series of hearth burners developed by Ukrgiproinzhproekt for nominal natural gas flow rates from 5 to 75 m e / h stably operates at a gas pressure of 20 to 200 kgf / m 2, with a rarefaction in the furnace of 1.5-2 kgf / m 2 and an air flow rate of a = = 1.25 1.35. Despite the high air flow rate, hearth burners, due to their simple design, stability and quiet operation, are often used in boilers, dryers and other thermal units with low thermal power and large furnace volumes. Hearth burners can operate with both forced air supply and medium gas pressure. In these cases A decreases to 1.15.
In injection multi-torch low-pressure burners of Mosgazproekt (Fig. X.10), a gas jet flowing at high speed from a nozzle 2 , sucks into the burner 40-60% of the air necessary for complete combustion of the gas. In a mixer consisting of a confuser 3 , throat 4 and diffuser 5, the gas is mixed with air and the velocity field of the mixture is equalized along the burner cross section. At the same time, mixture formation is not only completed in the diffuser, but the transformation of kinetic energy into static pressure is carried out, which is necessary to overcome the resistance at the outlet of the mixture from the holes 6 burner nozzle. Primary air intake is controlled by an air washer 1. Combustion of the mixture occurs in torches of blue-violet color, placed from each other at distances that ensure the supply of secondary air from the furnace to the fire and mutual ignition of the mixture.
Shown in Fig. X.10 GKS burners are welded for nominal natural gas flow rates from 4.7 to 6.1 m 3 /h. They operate quite stably at gas pressures from 10 to 180 kgf / m 2 and are used in small cast-iron sectional boilers and other installations with a furnace height of at least 600 mm.
1 - collector; 2 - centering glass; 8 - horizontal tunnel (slit); 4 - brickwork; G, - grate
lattice; c - air regulator; 7 - viewing window.
In injection single-flare burners of Stalproekt (type B) for medium pressure gas with Q H^ 8500 kcal / m 3 (Fig. X.11-) due to the high energy of the gas flowing out of the nozzle, all the air necessary for complete combustion of gas at a pressure in the furnace up to 2 kgf / m 2 is sucked in as primary. Stabilization
Rice, H.I., Stalproekt Medium Pressure Injection Burner, Type B. A- no nozzle cooling; b - with a water-cooled nozzle.
The combustion process is usually ensured by the use of refractory tunnels. To operate on natural gas (() and - = 8500 m 3 /h) without air heating, 20 standard sizes of such burners have been developed for nominal flow rates from 0.7 to 180 m 3 / h at a nominal gas pressure of 5000 kgf / m 2. Due to the absence of forced air supply and ensuring the completeness of combustion with small excesses of air, burners are widely used in heating and thermal furnaces of ferrous metallurgy, as well as in other units operating on a cold gas-air mixture.
Burners of the GGV Mosgazproekt type with forced air supply (Fig. X.12) are designed to burn natural gas of low and medium pressure in boilers, furnaces, dryers and other thermal installations with a small volume of furnaces. The gas supplied to the gas distribution manifold 5 exits
G- posik; 2 - fitting for a manometer; h- viewing hole; 4 - frame; 6 - gas distribution manifold; b - swirler; 7 - holes for gas outlet.
from it through radial holes 7 and mixes with the forced air flow, twisted by guide vanes 6 swirler. A well-mixed gas-air mixture burns in a transparent flame of relatively small length. Stabilization of combustion is provided by a refractory tunnel. Nominal gas flow rates - 50-500 m? / h, nominal pressure - 130 (low) and 3000 (medium) kgf / m 2, nominal air pressure, regardless of gas pressure - 100 kgf / m 2. Complete combustion of the gas occurs at a to 1.05.
Wind-resistant burners for infrared radiation GIIV-1 (Fig. X.13) and GIIV-2, developed by GSKTB Gas Apparatus - one of the varieties of radiation burners. Low pressure gas through nozzle 4 enters the mixer, sucking in all the air necessary for its combustion. From the mixer, the gas-air mixture exits into a distribution chamber covered with ceramic perforated tiles 2. The size of each tile is 65x45x12 mm, the diameter of the holes in them is 1 mm. The gas-air mixture enters the channels of the ceramic nozzle and, burning in them, heats the surface of the nozzle to 800-940 ° C. Heated to a cherry-red color, the surface of the nozzle emits 40-60% of the heat obtained during gas combustion by radiation. There are slits on the front of the reflector for wind resistance. 6 equalizing the pressure inside and outside the burner. Small hole diameters of ceramic tiles
1 - frame; G- a panel of ceramic tiles; 3 - net; 4 - nozzle; 5 - bracket; 6 - thin out in the reflector.
eliminate the slippage of the flame into the burner, and the high temperature of the nozzle virtually eliminates chemical underburning.
Infrared burners of various designs from GiproNIIgaz, Mosgazproekt and other organizations are widely used for drying plaster and paint coatings, heating, heating frozen materials, heating livestock farms, greenhouses, etc.
The gas-oil (combined) burner GMG, developed by TsKTI (Fig. X.14), is designed for alternate combustion of gas and fuel oil. Low pressure gas enters through the gas supply device 2 into the burner embrasure 3 through the outlet holes around the circumference of the end part of the device. The main part of the combustion air is supplied through the secondary air connection and after swirling in the swirler guide vanes 1 mixes with gas to form a gas-air mixture. Some
Rice. X.14. Oil-gas burner type GMR, part of the air, which serves mainly to cool the steam-mechanical oil burner 4 , enters through the primary air connection and passes through the swirler 5.
When operating on fuel oil, the latter is sprayed at boiler loads above 70% of the nominal mechanically, due to the high pressure of fuel oil (up to 20 kgf / cm 2). At lower loads, steam is used with a pressure of 1-2 kgf / cm 2. The pressure of the primary (turbulent) and secondary (main) air is assumed to be the same, so both air pipes are connected to a common air duct from the blower fan.
Rated power of GMG burners - from 2 to 7 Gcal / h, nominal gas pressure - 300-350 mm of water. Art., air pressure - 80-120 kgf / m 2. Burners are widely used for installation on heating and industrial water-heating boilers operating on gas and reserve oil fuel.
The above are just some examples of gas burner designs. A list of modern designs of gas burners with technical characteristics and recommendations for the conditions for their use is given in the Mosgazproekt album "Gas burners for the combustion of natural and liquefied gases, recommended for use" (1969).
A gas burner is a device that provides the supply of a certain amount of combustible gas and an oxidizer (air or oxygen), the creation of conditions for mixing them, and the transportation of the resulting mixture to the place of combustion and combustion of gas. There are burners in which only gas or gas and air are supplied to the combustion site, but without their preliminary mixing inside the burner.
Requirements for burners:
creation of conditions for complete combustion of gas with a minimum excess of air and the release of harmful substances in the combustion products;
ensuring the necessary heat transfer and maximum use of the heat of gas fuel;
· the presence of control limits, not less than the required change in the thermal power of the unit;
absence of strong noise, the level of which should not exceed 85 dB;
simplicity of design, ease of repair and safety of operation;
Possibility of using automatic control and safety;
Compliance with modern requirements of industrial aesthetics.
The main functions of gas burners are: supply of gas and air to the gas combustion front, mixture formation, stabilization of the ignition front, ensuring the required intensity of the gas combustion process.
According to the gas combustion method, all burners can be divided into three groups:
· without preliminary mixing of gas with air - diffusion;
· with incomplete preliminary mixing of gas with air - diffusion-kinetic;
· with full preliminary mixing of gas with air - kinetic.
In addition, burners can be classified according to the method of air supply, the location of the burner in the furnace space, the emissivity of the burner, and the gas pressure.
The classification of burners according to the method of air supply is widespread. On this basis, the burners are divided as follows:
Blow-free, in which air enters the furnace due to rarefaction in it;
injection, in which air is sucked in due to the energy of the gas jet;
blast, in which air is supplied to the burner or furnace using a fan.
The burners can operate at various gas pressures: low - up to 5000 Pa, medium - from 5000 Pa to 0.3 MPa and high - more than 0.3 MPa. The most common are burners operating at low and medium gas pressures.
An important characteristic of the burner is its thermal power, kJ / h:
where QN is the net calorific value of the gas, kJ / m3; VCh - hourly gas consumption by the burner, m3 / h.
There are maximum, minimum and nominal thermal power of gas burners. The maximum thermal power is achieved during long-term operation of the burner with high gas flow and without flame separation. The minimum thermal power occurs with stable operation of the burner at the lowest gas flow rates without flashover. The rated heat output of the burner corresponds to the operating mode with the nominal gas flow rate, i.e., the flow rate that provides the highest efficiency with the highest completeness of gas combustion. In the passports of the burners indicate the rated thermal power.
The maximum heat output of the burner must exceed the rated output by no more than 20%. If the rated thermal power of the burner according to the passport is 10,000 kJ / h, then the maximum should be 1 2,000 kJ / h.
Another important characteristic of the burner is the thermal power control limit n = 2 ... 5:
n = Qr min / Qr max,
where Qr min is the minimum heat output of the burner; Qr max - maximum heat output of the burner.
A large number of burners of various designs are in operation. General requirements for all burners: ensuring the completeness of gas combustion, stability with changes in thermal power, reliability in operation, compactness, ease of maintenance.
There are many different classifications of gas burners, which we can see in Table 1.
Table 1. Classification of gas burners
|
Classification sign |
Characteristics of the classification feature |
|
Component supply method |
Air supply by free convection |
|
Air supply due to rarefaction in the working space |
|
|
Air gas injection |
|
|
Forced air supply from an external source |
|
|
Forced air supply from the built-in fan (block burners) |
|
|
Forced air supply due to gas pressure (turbine burners) |
|
|
Gas injection with air (forced supply of air injecting gas) |
|
|
Forced supply of gas-air mixture from an external source |
|
|
The degree of preparation of the combustible mixture |
Without pre-mixing |
|
With partial primary air supply |
|
|
With incomplete premix |
|
|
With full premix |
|
|
Expiration rate of combustion products, m/s |
Up to 20 (low) |
|
St. 20 to 70 (medium) |
|
|
St. 70 (high, speed burners) |
|
|
The nature of the flow flowing from the burner |
Direct flow |
|
Twisted non-open |
|
|
twisted open |
|
|
Nominal gas pressure in front of the burner, Pa |
Up to 5000 (low) |
|
Average pressure (up to critical pressure drop) |
|
|
High pressure (critical or supercritical differential pressure) |
|
|
Possibility of regulation of characteristics of a torch |
With non-adjustable flame characteristics |
|
With adjustable flame characteristics |
|
|
The need to regulate the coefficient of excess air |
With unregulated (minimum or optimum) excess air ratio |
|
With adjustable (variable or increased) excess air ratio |
|
|
Burning zone localization |
In the refractory tunnel or in the combustion chamber of the burner |
|
H of the catalyst surface, in the catalyst bed |
|
|
In granular refractory mass |
|
|
On ceramic or metal nozzles |
|
|
In the combustion chamber of the unit or in open space |
|
|
Ability to use the heat of combustion products |
Without air and gas heating |
|
With heating in an independent heat exchanger or regenerator |
|
|
With air heating in the built-in heat exchanger or regenerator |
|
|
Heated air and gas |
|
|
Degree of automation |
Manual |
|
semi-automatic |
|
|
The source of energy in most heat engineering processes is the chemical heat of fossil hydrocarbon fuels: coal, oil with its derivatives, natural gas, as well as peat, shale, etc. The chemical heat of the fuel is released during its combustion in a mixture with an oxidizing agent, in most cases - with atmospheric oxygen, less often - with pure (technical) oxygen. Various burners are used to burn fuel. Burner classification For efficient fuel combustion, the burner performs the following functions: Prepares fuel and air for combustion, giving them the required directions and speeds of movement (in some cases, gas or air is preheated in the burner); Prepares a combustible mixture (mixes gas fuel and air or atomizes liquid fuel and mixes it with air); Carries out the supply of the prepared combustible mixture into the working space or furnace; Stabilizes ignition. Depending on the type, the burner device may be designed to perform only part of the listed functions. The combustion process of gaseous fuel can be divided into three main stages: Mixing fuel with combustion air; Heating the air-fuel mixture to the ignition temperature; The actual combustion process, i.e., the oxidation reaction of combustible fuel components with atmospheric oxygen, which proceeds almost instantly. The first two stages require much more time, and for this reason, the organization of mixing largely determines the entire combustion process, the characteristics of the flame, and, consequently, the temperature distribution in the working space of the combustion chamber. Since in the development of heating systems preference is given to the requirements of technology, the classification of burner devices is based on the degree of development of the process of mixing fuel with combustion air, methods of supplying fuel and air, the nature of the outflowing flows and other technological features. The classification features of burners and their characteristics, regulated by the standard, can be represented as follows: 1. Burners are divided according to the method of supplying air and fuel. There are injection heaters, in which gas jets inject air, and blast (or pressure) heaters, in which air is forced, using an autonomous draft fan or a built-in fan (in the so-called block burners). In very rare and specific cases (for example, in drum dryers at cement or metallurgical enterprises), there are burners in which air is supplied due to rarefaction in the working volume (in a drum dryer). However, in heating and industrial boilers, as a rule, blast or injection (atmospheric) burners are used. 2. According to the degree of preparation of the combustible mixture, all burners can be divided into burners without pre-mixing (air is mixed with fuel after leaving the burner, in the volume of the combustion chamber; in Europe they are called jet type burners), with incomplete pre-mixing (only part of the air, called primary) and with complete pre-mixing (already mixed gas-air mixture enters the furnace; premix). It is clear that in the latter case we are talking only about gas burners, and all types of liquid fuels involve the use of burners without prior mixing. 3. Burners differ in the nature of the flow flowing into the combustion chamber. This flow may be straight or swirling. In the latter case, a non-open and open flame is distinguished, in which there is a paraxial zone of recirculating combustion products. In addition, vortex heaters differ in the type of nozzle openings: there are burners with central, peripheral and combined gas supply. 4. The ability (or lack of opportunity) to regulate the characteristics of the torch (its length, twist, etc.) can also be considered a classification feature of the burner. 5. Most designs of large burners for industrial boilers allow for the possibility of changing the excess air ratio (i.e. air-fuel ratio). However, heating boilers of low power are equipped, as a rule, with burners with an unregulated (optimal according to combustion conditions) excess air coefficient. This parameter (i.e., the ability or inability to regulate excess air) is also an important classification feature of burners. 6. Together with the fuel, air is supplied to the burners, which can be cold (when it is supplied directly from a blower fan) or heated (when it is also supplied from a high-pressure blower fan, but only through a tubular or regenerative air heater). Thus, burners can also be classified according to the air temperature at the inlet. 7. Another classification feature is the degree of automation of the burner. We can talk about fully automated devices, on which all starting operations are performed by pressing a button; about burners with manual control, when the operator must perform all the operations for starting and stopping the boiler independently, in a strictly defined sequence; and about semi-automatic burners, where the amount of manual control is reduced to a minimum, but still exceeds the simple pressing of the “start” or “stop” button. 8. And of course, the main classification feature of any burner is the type of fuel for which it is designed. Small heating boilers are most often equipped with gas or diesel burners. Oil burners are installed on larger heating and industrial boilers. Often there are dual-fuel burners (for example, diesel oil-gas or fuel oil-gas). Large industrial and energy boilers are equipped not only with gas or oil burners, but also with pulverized coal, through which crushed solid fuel (coal, peat, shale) enters the furnace. Technical requirements for the design of burners Burner devices are selected taking into account the maximum satisfaction of the requirements of the technology and the general requirements for devices for fuel combustion. Therefore, the opinions sometimes expressed about the universality of any one type of burners and the absolute superiority of this type over the others are erroneous ... Share:
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