Natural gas. Combustion process. Complete and incomplete combustion of gas Gas-air ratio for combustion
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Natural gas is the most common fuel today. Natural gas is called natural gas because it is extracted from the very depths of the Earth.
The process of gas combustion is a chemical reaction in which natural gas interacts with oxygen contained in the air.
In gaseous fuel there is a combustible part and a non-combustible part.
The main flammable component of natural gas is methane - CH4. Its content in natural gas reaches 98%. Methane is odorless, tasteless and non-toxic. Its flammability limit is from 5 to 15%. It is these qualities that have made it possible to use natural gas as one of the main types of fuel. A methane concentration of more than 10% is life-threatening; suffocation can occur due to lack of oxygen.
To detect gas leaks, the gas is odorized, in other words, a strong-smelling substance (ethyl mercaptan) is added. In this case, the gas can be detected already at a concentration of 1%.
In addition to methane, natural gas may contain flammable gases - propane, butane and ethane.
To ensure high-quality combustion of gas, it is necessary to supply sufficient air to the combustion zone and ensure good mixing of gas with air. The optimal ratio is 1: 10. That is, for one part of gas there are ten parts of air. In addition, it is necessary to create the desired temperature regime. In order for a gas to ignite, it must be heated to its ignition temperature and in the future the temperature should not fall below the ignition temperature.
It is necessary to organize the removal of combustion products into the atmosphere.
Complete combustion is achieved if there are no flammable substances in the combustion products released into the atmosphere. In this case, carbon and hydrogen combine together and form carbon dioxide and water vapor.
Visually, with complete combustion, the flame is light blue or bluish-violet.
Complete combustion of gas.
methane + oxygen = carbon dioxide + water
CH 4 + 2O 2 = CO 2 + 2H 2 O
In addition to these gases, nitrogen and remaining oxygen are released into the atmosphere with flammable gases. N2+O2
If gas combustion does not occur completely, then flammable substances are released into the atmosphere - carbon monoxide, hydrogen, soot.
Incomplete combustion of gas occurs due to insufficient air. At the same time, tongues of soot visually appear in the flame.
The danger of incomplete combustion of gas is that carbon monoxide can cause poisoning of boiler room personnel. A CO content in the air of 0.01-0.02% can cause mild poisoning. Higher concentrations can cause severe poisoning and death.
The resulting soot settles on the walls of the boiler, thereby impairing the transfer of heat to the coolant and reducing the efficiency of the boiler room. Soot conducts heat 200 times worse than methane.
Theoretically, 9m3 of air is needed to burn 1m3 of gas. In real conditions, more air is required.
That is, an excess amount of air is needed. This value, designated alpha, shows how many times more air is consumed than is theoretically necessary.
The alpha coefficient depends on the type of specific burner and is usually specified in the burner passport or in accordance with the recommendations for organizing the commissioning work being carried out.
As the amount of excess air increases above the recommended level, heat loss increases. With a significant increase in the amount of air, a flame may break off, creating an emergency situation. If the amount of air is less than recommended, combustion will be incomplete, thereby creating a risk of poisoning for boiler room personnel.
For more accurate control of the quality of fuel combustion, there are devices - gas analyzers, which measure the content of certain substances in the composition of exhaust gases.
Gas analyzers can be supplied complete with boilers. If they are not available, the corresponding measurements are carried out by the commissioning organization using portable gas analyzers. A regime map is drawn up in which the necessary control parameters are prescribed. By adhering to them, you can ensure normal complete combustion of the fuel.
The main parameters for regulating fuel combustion are:
- the ratio of gas and air supplied to the burners.
- excess air coefficient.
- vacuum in the furnace.
- Boiler efficiency factor.
In this case, the efficiency of the boiler means the ratio of useful heat to the amount of total heat expended.
Air composition
| Gas name | Chemical element | Contents in the air |
| Nitrogen | N2 | 78 % |
| Oxygen | O2 | 21 % |
| Argon | Ar | 1 % |
| Carbon dioxide | CO2 | 0.03 % |
| Helium | He | less than 0.001% |
| Hydrogen | H2 | less than 0.001% |
| Neon | Ne | less than 0.001% |
| Methane | CH4 | less than 0.001% |
| Krypton | Kr | less than 0.001% |
| Xenon | Xe | less than 0.001% |
The location of the automation device elements is shown in Fig. 7. It shows that the electromagnet is covered with a protective cap. The wires from the sensors are located inside thin-walled tubes. The tubes are attached to the electromagnet using union nuts. The body terminals of the sensors are connected to the electromagnet through the housing of the tubes themselves.
Now let’s look at the method for finding the above fault.
The check begins with the “weakest link” of the automation device - the traction sensor. The sensor is not protected by a casing, so after 6... 12 months of operation it becomes “overgrown” with a thick layer of dust. The bimetallic plate (see Fig. 6) quickly oxidizes, which leads to deterioration of contact.
The dust coat is removed with a soft brush. Then the plate is pulled away from the contact and cleaned with fine sandpaper. We should not forget that it is necessary to clean the contact itself. Good results are obtained by cleaning these elements with a special “Contact” spray. It contains substances that actively destroy the oxide film. After cleaning, apply a thin layer of liquid lubricant to the plate and contact.
The next step is to check the serviceability of the thermocouple. It operates in severe thermal conditions, since it is constantly in the flame of the igniter; naturally, its service life is significantly shorter than other elements of the boiler.
The main defect of a thermocouple is burnout (destruction) of its body. In this case, the transition resistance at the welding site (junction) increases sharply. As a result, the current in the Thermocouple - Electromagnet circuit
- The bimetallic plate will be lower than the nominal value, which leads to the fact that the electromagnet will no longer be able to fix the rod (Fig. 5).
To check the thermocouple, unscrew the union nut (Fig. 7), located on the left 
sides of the electromagnet. Then turn on the igniter and use a voltmeter to measure the constant voltage (thermo-EMF) at the thermocouple contacts (Fig. 8). A heated, serviceable thermocouple generates an EMF of about 25...30 mV. If this value is less, the thermocouple is faulty. To final check it, disconnect the tube from the electromagnet casing and measure the resistance of the thermocouple. The resistance of the heated thermocouple is less than 1 Ohm. If the resistance of the thermocouple is hundreds of Ohms or more, it must be replaced. A low value of thermo-EMF generated by a thermocouple can be caused by the following reasons: - clogging of the igniter nozzle (as a result, the heating temperature of the thermocouple may be lower than the nominal one). They “treat” such a defect by cleaning the igniter hole with any soft wire of a suitable diameter;
- shifting the position of the thermocouple (naturally, it may also not heat up enough). Eliminate the defect as follows - loosen the screw securing the liner near the igniter and adjust the position of the thermocouple (Figure 10);
- low gas pressure at the boiler inlet.
If the EMF at the thermocouple terminals is normal (while the symptoms of malfunction indicated above remain), then check the following elements:
- integrity of contacts at the connection points of the thermocouple and draft sensor.
Oxidized contacts must be cleaned. The union nuts are tightened, as they say, “by hand.” In this case, it is not advisable to use a wrench, since you can easily break the wires suitable for the contacts;
- integrity of the electromagnet winding and, if necessary, solder its terminals.
The functionality of the electromagnet can be checked as follows. Disconnect 
thermocouple connection. Press and hold the start button, then light the igniter. From a separate constant voltage source, a voltage of about 1 V is applied to the released electromagnet contact (from a thermocouple) relative to the housing (at a current of up to 2 A). For this, you can use a regular battery (1.5 V), the main thing is that it provides the necessary operating current. The button can now be released. If the igniter does not go out, the electromagnet and draft sensor are working;
- traction sensor. First, check the force of pressing the contact against the bimetallic plate (with the indicated signs of malfunction, it is often insufficient). To increase the clamping force, release the lock nut and move the contact closer to the plate, then tighten the nut. In this case, no additional adjustments are required - the clamping force does not affect the response temperature of the sensor. The sensor has a large margin of plate deflection angle, ensuring reliable breaking of the electrical circuit in the event of an accident.
General information. Another important source of internal pollution, a strong sensitizing factor for humans, is natural gas and its combustion products. Gas is a multicomponent system consisting of dozens of different compounds, including those specially added (Table.
There is direct evidence that the use of appliances that burn natural gas (gas stoves and boilers) has an adverse effect on human health. In addition, individuals with increased sensitivity to environmental factors react inadequately to the components of natural gas and its combustion products.
Natural gas in the home is a source of many different pollutants. These include compounds that are directly present in the gas (odorants, gaseous hydrocarbons, toxic organometallic complexes and radioactive radon gas), products of incomplete combustion (carbon monoxide, nitrogen dioxide, aerosolized organic particles, polycyclic aromatic hydrocarbons and small amounts of volatile organic compounds). All of these components can affect the human body either on their own or in combination with each other (synergy effect).
Table 12.3
Composition of gaseous fuel
Odorants. Odorants are sulfur-containing organic aromatic compounds (mercaptans, thioethers and thio-aromatic compounds). Added to natural gas to detect leaks. Although these compounds are present in very small, subthreshold concentrations that are not considered toxic to most individuals, their odor can cause nausea and headaches in healthy people.
Clinical experience and epidemiological data indicate that chemically sensitive people react inappropriately to chemical compounds present even at subthreshold concentrations. Individuals with asthma often identify odor as a promoter (trigger) of asthmatic attacks.
Odorants include, for example, methanethiol. Methanethiol, also known as methyl mercaptan (mercaptomethane, thiomethyl alcohol), is a gaseous compound that is commonly used as an aromatic additive to natural gas. The unpleasant odor is experienced by most people at a concentration of 1 part in 140 ppm, but this compound can be detected at significantly lower concentrations by highly sensitive individuals.
Toxicological studies in animals have shown that 0.16% methanethiol, 3.3% ethanethiol, or 9.6% dimethyl sulfide are capable of inducing coma in 50% of rats exposed to these compounds for 15 minutes.
Another mercaptan, also used as an aromatic additive to natural gas, is mercaptoethanol (C2H6OS) also known as 2-thioethanol, ethyl mercaptan. Strong irritant to eyes and skin, capable of causing toxic effects through the skin. It is flammable and decomposes when heated to form highly toxic SOx vapors.
Mercaptans, being indoor air pollutants, contain sulfur and are capable of capturing elemental mercury. In high concentrations, mercaptans can cause impaired peripheral circulation and increased heart rate, and can stimulate loss of consciousness, the development of cyanosis, or even death.
Aerosols. The combustion of natural gas produces small organic particles (aerosols), including carcinogenic aromatic hydrocarbons, as well as some volatile organic compounds. DOS are suspected sensitizing agents that are capable of inducing, together with other components, the “sick building” syndrome, as well as multiple chemical sensitivity (MCS).
DOS also includes formaldehyde, which is formed in small quantities during gas combustion. The use of gas appliances in a home occupied by sensitive individuals increases exposure to these irritants, subsequently increasing symptoms of illness and also promoting further sensitization.
Aerosols generated during the combustion of natural gas can become adsorption sites for a variety of chemical compounds present in the air. Thus, air pollutants can concentrate in microvolumes and react with each other, especially when metals act as reaction catalysts. The smaller the particle, the higher the concentration activity of this process.
Moreover, water vapor generated during the combustion of natural gas is a transport link for aerosol particles and pollutants as they are transferred to the pulmonary alveoli.
The combustion of natural gas also produces aerosols containing polycyclic aromatic hydrocarbons. They have adverse effects on the respiratory system and are known carcinogens. In addition, hydrocarbons can lead to chronic intoxication in susceptible people.
The formation of benzene, toluene, ethylbenzene and xylene during the combustion of natural gas is also unfavorable for human health. Benzene is known to be carcinogenic at doses well below threshold levels. Exposure to benzene is correlated with an increased risk of cancer, especially leukemia. The sensitizing effects of benzene are not known.
Organometallic compounds. Some components of natural gas may contain high concentrations of toxic heavy metals, including lead, copper, mercury, silver and arsenic. In all likelihood, these metals are present in natural gas in the form of organometallic complexes such as trimethylarsenite (CH3)3As. The association with the organic matrix of these toxic metals makes them lipid soluble. This leads to high levels of absorption and a tendency to bioaccumulate in human adipose tissue. The high toxicity of tetramethylplumbite (CH3)4Pb and dimethylmercury (CH3)2Hg suggests an impact on human health, since the methylated compounds of these metals are more toxic than the metals themselves. These compounds pose a particular danger during lactation in women, since in this case lipids migrate from the body’s fat depots.
Dimethylmercury (CH3)2Hg is a particularly dangerous organometallic compound due to its high lipophilicity. Methylmercury can be incorporated into the body through inhalation and also through the skin. The absorption of this compound in the gastrointestinal tract is almost 100%. Mercury has a pronounced neurotoxic effect and the ability to influence human reproductive function. Toxicology does not have data on safe levels of mercury for living organisms.
Organic arsenic compounds are also very toxic, especially when they are destroyed metabolically (metabolic activation), resulting in the formation of highly toxic inorganic forms.
Natural gas combustion products. Nitrogen dioxide can act on the pulmonary system, which facilitates the development of allergic reactions to other substances, reduces lung function, susceptibility to infectious lung diseases, potentiates bronchial asthma and other respiratory diseases. This is especially pronounced in children.
There is evidence that NO2 produced by burning natural gas can induce:
- inflammation of the pulmonary system and decreased vital function of the lungs;
- increased risk of asthma-like symptoms, including wheezing, shortness of breath and attacks. This is especially common in women who cook on gas stoves, as well as in children;
- decreased resistance to bacterial lung diseases due to a decrease in the immunological mechanisms of lung defense;
- causing adverse effects in general on the immune system of humans and animals;
- influence as an adjuvant on the development of allergic reactions to other components;
- increased sensitivity and increased allergic response to adverse allergens.
Natural gas combustion products contain a fairly high concentration of hydrogen sulfide (H2S), which pollutes the environment. It is poisonous in concentrations lower than 50.ppm, and in concentrations of 0.1-0.2% is fatal even with short exposure. Since the body has a mechanism to detoxify this compound, the toxicity of hydrogen sulfide is related more to its exposure concentration than to the duration of exposure.
Although hydrogen sulfide has a strong odor, continuous low concentration exposure leads to loss of the sense of smell. This makes it possible for toxic effects to occur in people who may be unknowingly exposed to dangerous levels of this gas. Minor concentrations of it in the air of residential premises lead to irritation of the eyes and nasopharynx. Moderate levels cause headache, dizziness, and coughing and difficulty breathing. High levels lead to shock, convulsions, coma, which ends in death. Survivors of acute hydrogen sulfide toxicity experience neurological dysfunction such as amnesia, tremors, imbalance, and sometimes more severe brain damage.
The acute toxicity of relatively high concentrations of hydrogen sulfide is well known, but unfortunately little information is available on chronic LOW-DOSE exposure to this component.
Radon. Radon (222Rn) is also present in natural gas and can be carried through pipelines to gas stoves, which become sources of pollution. As radon decays to lead (210Pb has a half-life of 3.8 days), it creates a thin layer of radioactive lead (average 0.01 cm thick) that coats the interior surfaces of pipes and equipment. The formation of a layer of radioactive lead increases the background value of radioactivity by several thousand decays per minute (over an area of 100 cm2). Removing it is very difficult and requires replacing the pipes.
It should be taken into account that simply turning off the gas equipment is not enough to remove the toxic effects and bring relief to chemically sensitive patients. Gas equipment must be completely removed from the room, since even a gas stove that is not working continues to release aromatic compounds that it has absorbed over the years of use.
The cumulative effects of natural gas, the influence of aromatic compounds, and combustion products on human health are not precisely known. It is hypothesized that effects from multiple compounds may be multiplying, and the response from exposure to multiple pollutants may be greater than the sum of the individual effects.
In summary, the characteristics of natural gas that cause concern for human and animal health are:
- flammable and explosive nature;
- asphyxial properties;
- pollution of indoor air by combustion products;
- presence of radioactive elements (radon);
- content of highly toxic compounds in combustion products;
- the presence of trace amounts of toxic metals;
- toxic aromatic compounds added to natural gas (especially for people with multiple chemical sensitivities);
- the ability of gas components to sensitize.
Section Contents
When organic fuels are burned in boiler furnaces, various combustion products are formed, such as carbon oxides CO x = CO + CO 2, water vapor H 2 O, sulfur oxides SO x = SO 2 + SO 3, nitrogen oxides NO x = NO + NO 2 , polycyclic aromatic hydrocarbons (PAHs), fluoride compounds, vanadium compounds V 2 O 5, solid particles, etc. (see Table 7.1.1). When fuel is incompletely burned in furnaces, the exhaust gases may also contain hydrocarbons CH4, C2H4, etc. All products of incomplete combustion are harmful, but with modern fuel combustion technology their formation can be minimized [1].
Table 7.1.1. Specific emissions from flaring combustion of organic fuels in power boilers [3]
Legend: A p, S p – respectively, the content of ash and sulfur per working mass of fuel, %.
The criterion for sanitary assessment of the environment is the maximum permissible concentration (MPC) of a harmful substance in the atmospheric air at ground level. MAC should be understood as a concentration of various substances and chemical compounds that, when exposed to the human body daily for a long time, does not cause any pathological changes or diseases.
Maximum permissible concentrations (MPC) of harmful substances in the atmospheric air of populated areas are given in table. 7.1.2 [4]. The maximum single concentration of harmful substances is determined by samples taken within 20 minutes, the average daily concentration - per day.
Table 7.1.2. Maximum permissible concentrations of harmful substances in the atmospheric air of populated areas
| Pollutant | Maximum permissible concentration, mg/m3 | |
| Maximum one-time | Average daily | |
| Dust is non-toxic | 0,5 | 0,15 |
| Sulfur dioxide | 0,5 | 0,05 |
| Carbon monoxide | 3,0 | 1,0 |
| Carbon monoxide | 3,0 | 1,0 |
| Nitrogen dioxide | 0,085 | 0,04 |
| Nitric oxide | 0,6 | 0,06 |
| Soot (soot) | 0,15 | 0,05 |
| Hydrogen sulfide | 0,008 | 0,008 |
| Benz(a)pyrene | - | 0.1 µg/100 m 3 |
| Vanadium pentoxide | - | 0,002 |
| Fluoride compounds (by fluorine) | 0,02 | 0,005 |
| Chlorine | 0,1 | 0,03 |
Calculations are carried out for each harmful substance separately, so that the concentration of each of them does not exceed the values given in the table. 7.1.2. For boiler houses, these conditions are tightened by introducing additional requirements on the need to sum up the impact of sulfur and nitrogen oxides, which is determined by the expression
At the same time, due to local air deficiencies or unfavorable thermal and aerodynamic conditions, incomplete combustion products are formed in the furnaces and combustion chambers, consisting mainly of carbon monoxide CO (carbon monoxide), hydrogen H 2 and various hydrocarbons, which characterize heat loss in boiler unit from chemical incomplete combustion (chemical underburning).
In addition, the combustion process produces a number of chemical compounds formed due to the oxidation of various components of the fuel and air nitrogen N2. The most significant part of them consists of nitrogen oxides NO x and sulfur oxides SO x .
Nitrogen oxides are formed due to the oxidation of both molecular nitrogen in the air and nitrogen contained in the fuel. Experimental studies have shown that the main share of NO x formed in boiler furnaces, namely 96÷100%, is nitrogen monoxide (oxide) NO. NO 2 dioxide and nitrogen hemioxide N 2 O are formed in much smaller quantities, and their share is approximately: for NO 2 - up to 4%, and for N 2 O - hundredths of a percent of the total NO x emission. Under typical conditions of flaring fuel in boilers, the concentrations of nitrogen dioxide NO 2 are usually negligible compared to the NO content and usually range from 0÷7 ppm up to 20÷30 ppm. At the same time, rapid mixing of hot and cold regions in a turbulent flame can lead to the appearance of relatively large concentrations of nitrogen dioxide in the cold zones of the flow. In addition, partial emission of NO 2 occurs in the upper part of the furnace and in the horizontal flue (with T> 900÷1000 K) and under certain conditions can also reach noticeable sizes.
Nitrogen hemicoxide N 2 O, formed during the combustion of fuels, is, apparently, a short-term intermediate substance. N 2 O is practically absent in combustion products behind boilers.
The sulfur contained in the fuel is a source of formation of sulfur oxides SO x: sulfur dioxide SO 2 (sulfur dioxide) and sulfur SO 3 (sulfur trioxide) anhydrides. The total mass emission of SO x depends only on the sulfur content in the fuel S p , and their concentration in the flue gases also depends on the air flow coefficient α. As a rule, the share of SO 2 is 97÷99%, and the share of SO 3 is 1÷3% of the total yield of SO x. The actual content of SO 2 in the gases leaving the boilers ranges from 0.08 to 0.6%, and the concentration of SO 3 - from 0.0001 to 0.008%.
Among the harmful components of flue gases, a large group of polycyclic aromatic hydrocarbons (PAHs) occupies a special place. Many PAHs have high carcinogenic and (or) mutagenic activity and activate photochemical smog in cities, which requires strict control and limitation of their emissions. At the same time, some PAHs, for example, phenanthrene, fluoranthene, pyrene and a number of others, are physiologically almost inert and are not carcinogenic.
PAHs are formed as a result of incomplete combustion of any hydrocarbon fuels. The latter occurs due to the inhibition of oxidation reactions of fuel hydrocarbons by the cold walls of combustion devices, and can also be caused by unsatisfactory mixing of fuel and air. This leads to the formation in the furnaces (combustion chambers) of local oxidative zones with low temperatures or zones with excess fuel.
Due to the large number of different PAHs in flue gases and the difficulty of measuring their concentrations, it is customary to estimate the level of carcinogenic contamination of combustion products and atmospheric air by the concentration of the most powerful and stable carcinogen - benzo(a)pyrene (B(a)P) C 20 H 12 .
Due to their high toxicity, special mention should be made of fuel oil combustion products such as vanadium oxides. Vanadium is contained in the mineral part of fuel oil and, when burned, forms vanadium oxides VO, VO 2. However, when deposits form on convective surfaces, vanadium oxides are presented mainly in the form of V 2 O 5. Vanadium pentoxide V 2 O 5 is the most toxic form of vanadium oxides, therefore their emissions are calculated in terms of V 2 O 5.
Table 7.1.3. Approximate concentration of harmful substances in combustion products during flaring of organic fuels in power boilers
| Emissions = | Concentration, mg/m 3 | ||
| Natural gas | Fuel oil | Coal | |
| Nitrogen oxides NO x (in terms of NO 2) | 200÷ 1200 | 300÷ 1000 | 350 ÷1500 |
| Sulfur dioxide SO2 | - | 2000÷6000 | 1000÷5000 |
| Sulfuric anhydride SO 3 | - | 4÷250 | 2 ÷100 |
| Carbon monoxide CO | 10÷125 | 10÷150 | 15÷150 |
| Benz(a)pyrene C 20 H 12 | (0.1÷1, 0)·10 -3 | (0.2÷4.0) 10 -3 | (0.3÷14) 10 -3 |
| Particulate matter | - | <100 | 150÷300 |
When burning fuel oil and solid fuel, emissions also contain solid particles consisting of fly ash, soot particles, PAHs and unburned fuel as a result of mechanical underburning.
The ranges of concentrations of harmful substances in flue gases when burning various types of fuels are given in table. 7.1.3.
The combustion of natural gas is a complex physical and chemical process of interaction of its combustible components with an oxidizer, during which the chemical energy of the fuel is converted into heat. Combustion can be complete or incomplete. When gas is mixed with air, the temperature in the furnace is high enough for combustion, and the continuous supply of fuel and air ensures complete combustion of the fuel. Incomplete combustion of fuel occurs when these rules are not observed, which leads to less release of heat (CO), hydrogen (H2), methane (CH4), and as a result, to the deposition of soot on heating surfaces, worsening heat transfer and increasing heat loss, which in turn, leads to excessive fuel consumption and a decrease in boiler efficiency and, accordingly, to air pollution.
The excess air coefficient depends on the design of the gas burner and furnace. The excess air coefficient must be at least 1, otherwise it may lead to incomplete combustion of the gas. And also an increase in the excess air coefficient reduces the efficiency of the heat-using installation due to large heat losses with exhaust gases.
The completeness of combustion is determined using a gas analyzer and by color and smell.
Complete combustion of gas. methane + oxygen = carbon dioxide + water CH4 + 2O2 = CO2 + 2H2O In addition to these gases, nitrogen and the remaining oxygen enter the atmosphere with flammable gases. N2 + O2 If gas combustion does not occur completely, then flammable substances are released into the atmosphere - carbon monoxide, hydrogen, soot. CO + H + C
Incomplete combustion of gas occurs due to insufficient air. At the same time, tongues of soot visually appear in the flame. The danger of incomplete combustion of gas is that carbon monoxide can cause poisoning of boiler room personnel. A CO content in the air of 0.01-0.02% can cause mild poisoning. A higher concentration can lead to severe poisoning and death. The resulting soot settles on the walls of boilers, thereby impairing the transfer of heat to the coolant and reducing the efficiency of the boiler room. Soot conducts heat 200 times worse than methane. Theoretically, to burn 1 m3 of gas, 9 m3 of air is needed. In real conditions, more air is required. That is, an excess amount of air is needed. This value, designated alpha, shows how many times more air is consumed than theoretically necessary. The alpha coefficient depends on the type of specific burner and is usually prescribed in the burner passport or in accordance with the recommendations of the organization of the commissioning work performed. As the amount of excess air increases above the recommended level, heat loss increases. With a significant increase in the amount of air, a flame may break off, creating an emergency situation. If the amount of air is less than recommended, then combustion will be incomplete, thereby creating a threat of poisoning to boiler room personnel. Incomplete combustion is determined by: