Compressed natural gas. Compression and rarefaction of gases Compressed natural gas methane

Article provided by the companyLLC "Gazprom transgaz Ekaterinburg", Ekaterinburg

According to economic, environmental, resource and technical criteria, compressed natural gas (CNG) will remain the best motor fuel for a long time.

Today, 14.7 million vehicles run on CNG, which is 1.5% of the world fleet (900 million units). IN last years The global fleet of natural gas vehicles is increasing by 25-30% (Fig. 1). According to the forecast of the International Gas Union, the growth of the gas-cylinder vehicle fleet will be 50 million units by 2020, and more than 100 million units by 2030. Today there are already 20,746 automobile gas filling compressor stations (CNG filling stations) in the world.

Gas station infrastructure already exists or is rapidly developing in a number of countries, such as Germany, Sweden, Switzerland, Austria, Italy. In South Korea, 95% of municipal buses run on CNG. In Rome, transport using alternative fuels is exempt from taxes for 3 years. In France, there is a ban on the use of petroleum fuel on municipal buses. In Sweden, gas cars are exempt from fees at paid parking lots. Today, many global automakers carry out serial production of cars using CNG (Audi, BMW, Cadillac, Ford, Mercedes-Benz, Chrysler, Honda, Kia, Toyota, Volkswagen and others).

Such rapid development of this area is quite understandable - currently, of all the commonly used motor fuels and technologies, natural gas provides the safest exhaust emissions from vehicles. Converting cars from gasoline to gas can reduce emissions by an average of five times harmful substances, and the noise impact is doubled.

CNG in Russia

Our country has already accumulated a wealth of experience in using natural gas as a motor fuel. OJSC Gazprom predicts an increase in consumption of CNG as a motor fuel at the end of 2011 by about 10% - up to 370 million m 3 versus 345 million m 3 in 2010 (Fig. 2). Today in the territory Russian Federation There are 255 CNG filling stations operating in 60 regions of Russia, 206 (93%) were built by Gazprom OJSC. The fleet of gasified vehicles currently numbers 86 thousand vehicles. The highest CNG consumption in the country is observed in the Stavropol and Krasnodar territories, Sverdlovsk, Chelyabinsk and Rostov regions, Kabardino-Balkaria and North Ossetia.

Fig.1. World fleet of CNG vehicles

(according to the National Gas Engine Association)

Rice. 2. CNG consumption in Russia, million m3

Natural gas is much cheaper than gasoline. Natural gas extracted from the subsoil is not subject to further processing. This ultimately guarantees its lower cost compared to petroleum products. World natural gas reserves significantly exceed oil reserves. Natural gas is not subject to seasonal price changes. In addition, in accordance with the resolution of the Russian Government, the price of natural gas for motor vehicles cannot exceed 50% of the price of A-80 gasoline. In 2011, the average retail price of CNG in the Russian Federation for motor vehicles was 8.5 rubles/m 3 .

The reasons for the methanization of vehicles in the Ural region are the same as in Russia, and, perhaps, throughout the world - the environmental and economic advantages of using natural gas as a motor fuel.

CNG in the Ural region

Currently, Gazprom Transgaz Ekaterinburg LLC operates a network of 30 (CNG filling stations) and 6 vehicle conversion points located in the Sverdlovsk, Chelyabinsk, Kurgan and Orenburg regions.

The main consumer of CNG in the Ural region is urban passenger vehicles. These are minibuses such as PAZ buses and Gazelle minibuses.

In addition to stationary CNG filling stations, we have the opportunity to refuel gas-cylinder vehicles using mobile automobile gas tankers (PAGZ) with a booster compressor. It is based on the KAMAZ-43118 vehicle with a gas engine. A small-sized block complex has been developed and is undergoing industrial testing, providing regasification of liquefied natural gas for refueling gas-cylinder vehicles.

Currently, in the Russian Federation, serial production of vehicles with gas engines is carried out by KAMAZ OJSC (RariTEK LLC) - NEFA3 buses, truck tractors, dump trucks. GAZ Group produces buses with a gas engine - LIAZ-6213, LIAZ-6212, LIAZ-5256, LIAZ 5293, PAZ 320302, etc.

In addition, it is possible to purchase gas cylinder equipment from foreign automakers - Iveco, Volkswagen, Mercedes, Opel, Toyota, etc.

Today, Gazprom Transgaz Ekaterinburg LLC operates 691 units. Vehicles using CNG as motor fuel. In 2011 the economic effect from replacing liquid motor fuel amounted to RUB 22.3 million.

As a result of trilateral cooperation with OJSC KAMAZ and OJSC NPO Geliymash, the following were created: a truck tractor and a city bus, equipped with gas engines with a cryogenic tank for refueling LNG. The first results showed their significant advantage in comparison with gas-cylinder vehicles using CNG. Thus, vehicle mileage without refueling has more than doubled.

In order to expand the use of CNG, in July 2011, within the framework of the international exhibition "INNOPROM - 2011", a tripartite "Agreement" was signed between the Government of the Sverdlovsk region, Gazprom Transgaz Ekaterinburg LLC and KAMAZ OJSC on the development of the use of natural gas as a motor fuel. The agreement, in particular, provides for delivery to the Sverdlovsk region. KAMAZ vehicles using both CNG and LNG as motor fuel. Gazprom Transgaz Ekaterinburg LLC provides CNG and LNG refueling of gas-cylinder vehicles, provides methodological assistance to third-party vehicle conversion points and directly converts the region’s existing vehicle fleet to use gas motor fuel.

In October 2011, on behalf of OJSC Gazprom, the Company organized and conducted a rally of factory-made gas-cylinder vehicles “Blue Corridor - 2011” along the route Ekaterinburg - Chelyabinsk - Ufa - Orenburg - Samara - Saratov - Volgograd - Tambov - Voronezh - Tula - Moscow. As part of this run, “Protocols of Intent” were signed between the governments of the Chelyabinsk and Orenburg regions and the Company, providing for the use of CNG as a motor fuel as a priority area of ​​activity for the parties.

In accordance with the Targeted Comprehensive Program for the development of a gas filling network and a fleet of equipment operating on natural gas for 2007-2015. In the area of ​​responsibility of Gazprom Transgaz Yekaterinburg LLC, six CNG filling stations have been identified for construction.

Expansion proposals
natural gas use

Gazprom Transgaz Ekaterinburg LLC proposes a number of measures, the adoption of which will increase the use of natural gas as a motor fuel.

At the federal level it is proposed:

1. Adopt the law “On the use of gas motor fuel”.

2. Develop and adopt by the Government of the Russian Federation a number of measures for economic stimulation of business entities and individuals engaged in the production, sale and use of natural gas as motor fuel.

At the level of the constituent entities of the Russian Federation it is proposed:

1. Development and implementation of regional programs for the use of gas motor fuel in vehicles.

2. Ensuring priority acquisition at the expense of budgetary funds of public transport and municipal equipment using gas engine fuel, in order to reduce budgetary fuel costs and improve the environmental situation in cities.

3. Inclusion of costs for retrofitting garage complexes of budgetary organizations when transferring vehicles to use gas engine fuel in municipal budgets.

4. The costs of operating gas engine equipment are reduced due to savings in fuel costs. REC, based on Federal Law No. 261-FZ “On energy saving and increasing energy efficiency and on introducing amendments to certain legislative acts of the Russian Federation” dated November 23, 2009, must keep transportation tariffs unchanged for 5 years.

OJSC Gazprom offers:

1. Continue work on the adoption of the Federal Law “On the Use of Gas Engine Fuel” and on the development and production of modern and efficient gas equipment.

2. Implement the program of OJSC Gazprom “Development of a gas filling network and a fleet of equipment operating on natural gas for 2007-2015.”

3. Organize the refueling of vehicles of potential consumers using mobile refueling trucks with the subsequent construction of a CNG filling station.

Conclusion

In April 2012, Vladimir Putin, while in Togliatti, proposed providing additional subsidies to Russian regions to update their bus fleet.

It is proposed to allocate funds to those regions that will transfer their bus fleet to a cleaner type of fuel - gas. It is preliminary planned to allocate 3.5 billion rubles for these purposes. from the budget of the Russian Federation.

Currently, more than 50% of the bus fleet is over 15 years old, and most of our European neighbors have their buses renewed every ten years for safety reasons.

The purchase of municipal transport using CNG and LNG as motor fuel must be synchronized with the construction of new CNG filling stations, vehicle conversion and maintenance points, cylinder re-examination points, and the commissioning of mobile automobile gas refueling stations. This will further ensure a real improvement in the environmental situation in large industrial cities, increase the economic efficiency of cargo and passenger transportation, reduce costs in budgets of all levels, and accelerate the formation of a new market for the use of natural gas in the Ural region.

Strategy

The production and sale of compressed and liquefied natural gas as motor fuel is one of the priority activities of Gazprom PJSC. For systematic work on the development of the gas engine fuel market, a specialized company has been created - Gazprom Gazomotornoye Toplivo LLC.

The most economical and environmentally friendly fuel

Today, natural gas is the most economical, environmentally friendly and safe fuel. Natural gas is essentially a finished motor fuel, so it is much cheaper than gasoline and diesel fuel. Moreover, the engine of such a vehicle meets the highest standards - Euro-5 and Euro-6. According to the classification of the Ministry of Emergency Situations, natural gas belongs to the safest class of flammable substances.

Two types of natural gas are used as motor fuel: compressed (CNG) and liquefied (LNG).

Target market segments:

• CNG - passenger, light freight, passenger transport and municipal vehicles;
• LNG – long-distance road, rail, water transport, quarry and agricultural machinery.

Russian gas motor fuel market

The consumption of natural gas as a motor fuel in Russia is steadily increasing.

The significant growth potential of the domestic gas engine fuel market is facilitated by:

• significant reserves of natural gas and a developed gas distribution network, allowing for the stability of supplies of gas motor fuel in the long term;
• introduction of energy-efficient fuels in transport, including the conversion of passenger transport and municipal equipment to natural gas in cities with a population of more than 100 thousand people;
• expanding the range of equipment running on natural gas and gas filling infrastructure;
• low price of gas motor fuel compared to traditional types of fuel.

As of December 31, 2018, there were 293 automobile gas filling compressor stations (CNG filling stations) owned by the Gazprom Group operating on the territory of the Russian Federation, of which 235 CNG filling stations were operated by Gazprom Gazomotornoye Toplivo LLC and 58 were operated by subsidiaries of Gazprom PJSC "

The volume of CNG sales through Gazprom's gas filling network in 2018 amounted to 598.2 million cubic meters. m.

Development of gas engine infrastructure

The strategic approach to creating a retail network in Russia provides for the development of gas engine infrastructure in 60 constituent entities of the Russian Federation.

Together with the Federal Road Agency, a General Scheme for the placement of gas filling infrastructure facilities on federal roads has been developed, which involves the construction of a support network of 181 facilities by 2030 and the creation of so-called “gas engine corridors” on key existing and future highways in Russia.

In 2018, 21 CNG filling stations and three sites for mobile gas filling stations were built and purchased from private investors; four CNG filling stations and two sites for mobile gas filling stations were reconstructed.

A program is being implemented to create a refueling infrastructure at the industrial sites of Gazprom PJSC subsidiaries for the period 2017-2019, which provides for the installation of 100 natural gas compression units for the needs of our own transport.

Work is underway to create infrastructure for the production and use of LNG as a motor fuel. A program for the development of small-scale production and use of LNG has been adopted, the implementation of which is planned for the period 2016-2032.

Foreign market of gas motor fuel

Expanding the use of natural gas as fuel for automobiles and water transport Gazprom is also active in foreign markets.

In Europe, in this segment, Gazprom is represented in the markets of Germany, the Czech Republic and Poland through the company Gazprom NGV Europe GmbH, as well as through the NIS company, part of the Gazprom Neft Group, which sells CNG on the Serbian market.

In 2018, the number of CNG filling stations and cryo-filling stations in European countries was 70. Sales of CNG and LNG through the Gazprom Group’s own stations in Europe in 2018 amounted to 12.9 million cubic meters. m.

The Gazprom Group also sells CNG through CNG filling stations in Armenia, Belarus, and Kyrgyzstan. In 2018, sales volume amounted to 42.3 million cubic meters. m.

Projects are being implemented to create gas engine infrastructure in Bolivia and Vietnam.

Gas, which is extracted from the bowels of the earth or is a product of the processing of other hydrocarbons, can subsequently be used in liquefied or compressed form. What are the features of both options for using the respective fuel?

What is liquefied gas?

Under liquefied It is customary to understand natural gas, which is transferred from its original gaseous state to liquid - by cooling to a very low temperature, about minus 163 degrees Celsius. The volume of fuel is reduced by approximately 600 times.

Transportation of liquefied gas requires the use of special cryogenic tanks that are capable of maintaining the required temperature of the corresponding substance. The advantage of the type of fuel in question is the ability to deliver it to places where it is difficult to install conventional gas pipelines.

Converting liquefied gas to its original state also requires special infrastructure - regasification terminals. The processing cycle of the type of fuel in question - production, liquefaction, transportation and regasification - significantly increases the final cost of gas for the consumer.

The fuel in question is used, usually for the same purposes as natural gas in its original state - for heating premises, ensuring the functioning of industrial equipment, power plants, as a raw material in some segments of the chemical industry.

What is compressed natural gas?

Under compressed, or compressed, it is customary to understand natural gas, which, like liquefied gas, is also presented in a liquid state, achieved, however, not by reducing the temperature of the fuel, but by increasing the pressure in the container in which it is placed. The volume of compressed gas is approximately 200 times less than that of the fuel in its original state.

Converting natural gas into liquid using high pressure- the process is generally cheaper than liquefying fuel by reducing its temperature. Transportation of the type of gas in question is carried out in containers that, as a rule, are less technologically complex than cryocankers. Regasification of the corresponding type of fuel is not required: since it is under high pressure, it is easy to remove from the containers - just open the valves on them. Therefore, the cost of compressed gas for the consumer is in most cases lower than that of liquefied fuel.

Compressed gas is most often used as fuel in various vehicles- cars, locomotives, ships, gas turbine engines of aircraft.

Comparison

The main difference between liquefied gas and compressed gas is that the first type of fuel is obtained by reducing the temperature of the original gaseous substance, which is accompanied by its conversion into liquid. Compressed gas is also a liquid fuel, but it is produced by placing it in a container under high pressure. In the first case, the initial volume of gas exceeds the processed one (converted into liquid) by approximately 600 times, in the second - by 200 times.

It is worth noting that liquefied gas is most often obtained by processing “classical” natural gas, mainly represented by methane. Compressed fuel is also made from many other types of gases of natural origin, such as propane or butane.

Having determined what the difference is between liquefied and compressed gas, we will reflect the conclusions in the table.

Table

Compressed flammable gases as motor fuels in road transport began to be used in our country back in the 30s of the last century. At first, they used compressed coke oven and lighting gases, which were used to operate GAZ-4A and ZIS-30 cars with a power reserve of up to 120 km at one refueling.

After the war, the discovery and development of large natural gas fields, as well as the construction of a number of main pipelines, made it possible to expand the use of gaseous fuels in road transport. But later, due to the sharp increase in oil production and the construction of large oil refineries, the use of compressed natural gas decreased and many gas filling stations were mothballed.

The GAZ, ZIL, LAZ factories have developed designs for gas-cylinder vehicles ZIL-138A, ZIL-53-27, LAZ-695N, etc. The supply of compressed gas on these vehicles is in carbon steel cylinders weighing 93 kg, with a capacity of 50 liters, at a pressure of 20 MPa. A fully filled cylinder contains about 10 m 3 of gas, which is equivalent to about 10 liters of gasoline. The characteristics of the LNG-fuelled gas turbine are given in Table. 4.3.

Table 4.3

Characteristics of the main models of gas-cylinder cars,

operating on compressed natural gas

Prototypes of passenger cars were also developed, for example based on the Moskvich. The cylinder was made of low-alloy steel, with a total weight of 63 kg and a wall thickness of 6 mm.

It is obvious that it is advisable to manufacture cylinders from light and durable polymer materials.

Compared to LPG, compressed natural gas when used in gas turbine units has the following advantages:

– There are much more explored and developed reserves of natural gas. It is already possible to convert the country's entire vehicle fleet to LNG;

– exhaust gases contain significantly less harmful substances;

– compressed gas with established production is cheaper than liquefied gas;

– LNG is lighter than air, so leaks do not create explosive structures, like LPG.

At the same time, compressed natural gas also has a number of disadvantages that hinder its widespread use:

– LNG must be stored in compressed form, since it is difficult to transform into a liquefied state – at a temperature of minus 82 °C and a pressure of at least 4.5 MPa;

– the large mass of cylinders significantly reduces the vehicle’s carrying capacity;

– small power reserve (Table 4.3);

– complexity of filling equipment for gas filling stations.

Natural deposits contain 82–98% methane, up to 6% ethane and 4–20% propane.

Natural compressed gas is obtained from flammable natural gas transported through main gas pipelines or city gas networks, removing impurities, drying and subsequent compression using technology that does not allow changes in the component composition. Compressed natural gas intended for refueling gas engines must meet the requirements of GOST 27577-87 “Compressed natural fuel gas for gas-cylinder vehicles.” Physico-chemical indicators of LNG for GBA are given in Table. 4.4.

Table 4.4

Physico-chemical indicators of compressed natural gas

according to GOST 27577-87

End of table. 4.4

Note. The indicator values ​​were established at a temperature of 20 °C and a pressure of 0.1013 MPa (1 atm).

Special attention When compressing compressed gas, it is given pre-drying. The maximum water content in one cubic meter of gas is allowed no more than 9 mg. This is due to the fact that a sharp decrease in gas pressure occurs in the high-pressure reducer. When there is excess water content, it crystallizes. In addition, before reducing the pressure, the gas is heated in a heater using the heat of the exhaust gases. The temperature after reducing the pressure remains within acceptable limits.

In gas-diesel engines, the temperature at the end of the compression stroke (500...780 °C) is insufficient for self-ignition of the gas-air mixture. The use of an ignition system with the installation of spark plugs in the holes for the injectors is technically complex and significantly increases the time when switching from one type of fuel to another. Therefore, a pilot dose limiter is installed on the high-pressure fuel pump. The fuel pedal changes the supply of gas only, and the portion of diesel fuel is constant and approximately equal to the supply volume at 15–20% of the maximum.

Much attention is paid to the use of gas fuel in agriculture. The Kirov Agricultural Institute developed and successfully tested the Universal - 445 tractor. Its engine runs on compressed gas. The tractor is intended for operation in rooms with limited air exchange (greenhouses, warehouses). Compressed gas is stored in 4 cylinders with a capacity of 50 liters, located on the sides of the engine compartment. The gas diesel engine is started using diesel fuel, and then the compressed gas supply is turned on and the tractor operates by regulating the gas supply. The dose of pilot diesel fuel is constant and amounts to 1.6 kg/h. Gas consumption at nominal mode does not exceed 53 m 3 /h. In this case, the power developed by the diesel engine is 33 kW at a crankshaft speed of 2400 rpm. The tractor operates reliably in all modes, providing diesel fuel savings while reducing the soot content in exhaust gases by 4–5 times.

The same institute also converted the T-16 MG self-propelled chassis to use LNG as fuel, where, like on a tractor, up to 80% of diesel fuel is replaced by gas. It is characteristic that the conversion of tractors and self-propelled carts to LNG does not require expensive equipment and can be carried out in specialized workshops.

Abroad, much attention is paid to the use of LNG as a fuel. This is primarily due to the ratio of prices for liquid and gas fuels, as well as taking into account the requirement to maximize the use of own fuel resources and minimize dependence on market conditions.

Italy occupies a leading place in this area. The cost of gas equipment in Italy is 2 times lower than, for example, in the USA. This is due to the wider use of this equipment. The composition of the Italian fleet of gas-cylinder vehicles running on LNG consists of passenger cars for individual use. Trucks have diesel engines.

In the USA, Ford has developed a special car model to run on natural gas. Work is underway on the use of medium-pressure gas cylinder units (2 MPa) using solid adsorbent. Currently, experimental adsorbents and cylinders have been created that, at a pressure of 2 MPa, contain a gas reserve equivalent to that in cylinders with a pressure of 15 MPa, i.e., they provide a filling factor of 7.5.

The fleet of LNG-powered vehicles in Canada is also growing. For gas-cylinder vehicles in Canada, the operating gas pressure is 21 MPa. Steel cylinders undergo inspection (hydraulic tests) once every three years. Installation of cylinders on the roofs of vehicles is not permitted.

A similar direction of development of GBA is being carried out in other countries.

The Italian company Landi Renzo produces gas equipment for operation on LNG (methane) and liquefied petroleum gas (LPG). Structurally, both types of equipment operate according to a universal scheme, i.e., they ensure full operation of the car on gas and gasoline. Characteristic of this company is the widespread use of solenoid valves and electrically commutated actuators. The company considers it inappropriate to produce universal gearboxes for working on compressed and liquefied gases and produces two types of gearboxes. The company also pays attention to improving fuel equipment for gas diesel engines.

Along with Landi Renzo products, gas-cylinder power supply equipment for gasoline engines from Tartarini is widely popular. The widespread use of electronics ensures the production of high-quality gas mixing equipment.

One of the leading companies producing gas cylinders is Faber.

Compressed compressed gas is obtained different ways: directly from gas wells, as a product of oil refining and by fractionation of gas condensate or associated petroleum gas. Compressed natural gas can not only successfully replace liquid motor fuels, but also surpasses them in a number of parameters. Its main advantage is that compressed natural gas can be used in road transport without expensive technological processing.

The composition of natural gases produced in domestic fields is quite similar. Basically (82-98%) it is methane CH4 with small impurities (up to 6%) ethane C2H6, up to 1.5% propane C3H8 and up to 1% butane C4H10. In associated gases produced from oil fields, depending on the production area, the methane content can range from 40 to 82%, and butane and propane - from 4 to 20%.

The main component, methane CH 4, is characterized by the highest critical temperature (-82°C). Therefore, when normal temperatures Even at high pressure, methane cannot be liquefied: this requires low temperature.

The properties of methane are determined by its molecular structure. Gas belongs to simple hydrocarbons. Its molecule contains a maximum of hydrogen per carbon atom. This is due to the high thermal conductivity of methane, a wide range of flammability and low content of toxic components. Due to the high hydrogen content in compressed gas, it burns more completely in the engine cylinders than HPG and gasoline. Compared to other hydrocarbon gases, methane is much lighter than air, so in the event of a leak, it accumulates in the upper part of the room. The high knock resistance of methane allows the engine to be boosted in terms of compression ratio (9.5-10.5).

In terms of energy parameters, 1 m3 of natural gas is equivalent to 1 liter of gasoline. At the same time, natural gas has a very low volumetric energy concentration. If the calorific value of 1 liter of liquid fuel is 31426 kJ, then for natural gas it is 33.52-35.62 kJ, i.e. almost 1000 times less. Therefore, natural gas must be compressed to high pressure.

At automobile gas filling compressor stations in Russia, the operating pressure is 20 MPa.

For compressed gas, gas cylinder units (cylinders, fittings, reducers, gas pipelines, etc.) are used, designed to operate at high pressure - 19.6 MPa (200 kgf/cm2). As the gas from the cylinder is consumed, the operating pressure in it continuously decreases.

CNG cylinders have a capacity of 34-400 liters and are designed for a pressure of 19.6 MPa.

Since cylinders for storing compressed gas are made of thick walls, a battery of eight such cylinders is quite heavy. Consequently, the payload capacity of the vehicles is also reduced. At the same time, the mileage of CNG vehicles becomes 2 times less than that of gasoline. Therefore, cryogenic technology for storing CNG on a car is considered more promising. In addition, this direction is considered a milestone on the path to creating hydrogen engines.

Compressed (compressed) natural gas (CNG) was previously called compressed natural gas (CNG) and is regulated by GOST 27577-2000 "Compressed fuel gas for engines" internal combustion" determines the physicochemical and operational indicators of CNG (Table 5.7).

Table 5.7 Physico-chemical indicators and operational indicators of CNG

Note. The indicator values ​​were established at a temperature of 293K (20 °C) and a pressure of 0.1013 MPa .

In accordance with GOST for CNG, the temperature of the gas filled into vehicle cylinders should be no more than 40°C. At ambient temperatures above 35°C, the temperature of the gas being charged should be no more than 5°C higher than the air temperature. The temperature of CNG during refueling is determined at the request of consumers.

CNG ignites at a temperature of 635-645°C in the engine combustion chamber, which is 3 times higher than the ignition temperature of gasoline.

This makes it difficult to start the engine, especially when low temperatures(below -5°C) ambient air. Therefore, cars have a backup gasoline power system. At the same time, in terms of ignition and fire hazards, CNG is much safer than gasoline.

TO positive factors Applications of CNG include the following:

The service life of engine oil increases by 1.5-2.0 times due to the absence of its dilution and reduced contamination; as a result, oil consumption is reduced by 30-40% compared to gasoline engines;

The service life of the engine increases by an average of 35-40% due to the absence of carbon deposits on the parts of the cylinder-piston group;

The service life of spark plugs increases by 40%;

The engine's overhaul mileage increases by 1.5 times;

The emission of harmful substances, especially CO, from exhaust gases is significantly reduced (up to 90%).

The engines of gas-cylinder vehicles running on CNG, if the gas is used up, can quickly switch to running on gasoline.

Along with the advantages, the following disadvantages can be noted:

The labor intensity of maintenance and repair increases by 7-8%, and the price of the car increases by an average of 27% due to the presence of additional gas equipment;

Engine power is reduced by 18-20%. The traction, dynamic and operational characteristics of cars are deteriorating: acceleration time increases by 24-30%; maximum speed decreases by 5-6%; the maximum angles of climbs overcome are reduced by 30-40%; operating a vehicle with a trailer becomes difficult; the driving range on one gas filling is reduced (does not exceed 200-250 km);

The vehicle's carrying capacity is reduced by 9-14% due to the use of high-pressure steel cylinders (their number and weight may vary);

The mileage utilization rate of gas-cylinder vehicles is reduced by 8-13% compared to gasoline vehicles;

Annual productivity when working in urban transport is reduced by 14-16% compared to gasoline.

The considered features of CNG as a fuel for cars make it possible to determine the rational area of ​​application of gas-cylinder cars: transportation in large cities and adjacent areas (a priority for improving the air quality).

The effectiveness of intra-city transportation on gas-cylinder vehicles when servicing trade, household, communications and other institutions is obvious.