EA012054B1 - Personal gas-balloon unit for producing propane-butaneair gas mixture for optimum heat combustion in domestic and public utilities - Google Patents

Abstract

The invention relates to producing gaseous fuel mixed with air having optimum combustion heat at units of personal gas-balloon unit systems for domestic needs and public-purpose utilities. Production of gas-air mixture using the personal gas-balloon unit permits to increase the volume of commercial gas and more rational use of propane and butane fractions as Supplier has usually propane deficit and butane excess. Air-gas mixtures (liquefied air-gases) have the following advantages compared to undiluted hydrocarbons under definite conditions: interchangeability with natural gases in gas combustion domestic appliances; expands geographical borders of liquefied gases use, especially in cold climate countries; increasing abilities to use liquefied gas with butane higher content (up to 60%), an additional economy is provided due to full gas use stored in the balloon, continuous operation of gas-balloon units is increased and reducing expenditures for purchasing an additional stock thereof. The use of air-gas mixture as fuel for domestic and public gas utilities can be facilitated by mixing vapor phase of liquefied gas with air in ratios providing exceeding explosiveness upper limit at least by two times. The claimed invention provides pre-mixing of vapors of liquefied gas and air for obtaining optimum heat of gaseous mixture combustion resulting in substantial reduction of excess air factor which leads to raise the economic effectiveness of the unit operation, improves a heat engineering feature of domestic gas appliances and environmental indices.

Description

The invention relates to the field of production of gaseous fuel in a mixture with air of optimum calorific value at the nodes of the gas supply systems of an individual gas-cylinder installation and can be used for population and household purposes.

Liquefied gases must comply with the requirements of GOST 20448-80 - “Liquefied fuel gases for household consumption. Technical conditions ”, which envisage the following gas brands and areas of their use: SPBTZ - a mixture of propane and butane technical winter, the mass fraction of propane components is at least 75%; SPBTL is a mixture of propane and butane summer, propane is not standardized and butane is at least 60%; BT - technical butane, not more than 60%.

Combustible gases, in addition, can be classified according to the lower calorific value - O ,, and the combustion temperature - T _max (Ravich MB Gas and its use in the national economy. M .: Nauka, 1077, p. 357).

According to lower heat value of combustion - О ,, with increased heat of combustion (high-calorific) - О,,> 31.40 MJ / m ³ (natural, incidentally oil and liquefied);

with an average heat of combustion p _n = 12.6-31.40 MJ / m ³ (coke, shale and generator, obtained by gasification with steam-oxygen blowing under pressure);

with low heat value - 0 ,, + 12.6 MJ / m ³ (blast-furnace, generator, mixed and gases of underground gasification of coal).

According to the combustion temperature (max) with T _max = 2000 ° С - natural, oilfield, liquefied, coke, shale gases, which are expedient to use for high-temperature processes;

T _Tax = 1700-1500 ° C - mixed (50% of coke and 50% of the domain), generator gases from bitumen fuels, which are used for medium-temperature processes;

with Тmax = 1400-1500 ° С - domain and some generator gases, which are used for medium-temperature and low-temperature processes;

with T _max = 750-1400 ° C - numerous waste gases (cupola, carbon black plants, purge gases, which are often not utilized);

with T _max <750 ° C - these gases are not used as fuel.

Gas fuel is used in all industries and public utilities. At the same time non-renewable organic fuel raises the question of its rational and efficient use. When designing gas supply systems for settlements and individual objects, it is necessary to provide the most advanced technical solutions to ensure the rational use of gas fuel.

On 01/01/1990, the number of gasified flats based on the use of individual gas cylinder installations in Russia and the CIS countries is more than 36 million, including 16 million in Russia.

Consumption of liquefied gas for this period, respectively, amounted to 5.8 million tons, including Russia - 2.6 million tons.

Analysis of the structure of consumption of liquefied gas (cooking food, hot water for household and sanitary needs, public catering enterprises and household facilities) dictates the need for us to switch to the gas consumption mode of an individual LPG installation mixed with air with optimal heat of combustion.

The use of an individual LPG installation in a mixture with air of optimum heat of combustion and the tasks of their wide consumption in everyday life and in the domestic economy, especially in winter periods with a high content (up to 60%) of butane, creates the possibility to expand the geographical boundaries for uninterrupted use gas mixture, as well as increase the time spent in operation of a single unit with a capacity of 50 l or two cylinders with a capacity of 27 l each for at least 2-3 months.

It should also be noted that SNiP 11-37-76 as a regulatory material for determining the estimated performance of a single-cylinder installation was taken 0.43-0.22 m ³ / h for a cylinder with a capacity of 50 liters. In the case of their mixture with air, the capacity will be determined in the volume of 6.10-0.31 m ³ / h.

Production of gas-air mixtures should be organized taking into account the interchangeability of gases, and use as fuel for the population and household appliances is permissible, provided that the gas content in the gas-air mixture is equivalent to at least two upper explosion limits.

For an interchangeable mixture of liquefied gases, it is necessary to prepare a mixture of butane-air containing 47% butane and 53% air, and for a mixture of propane-air - 58% propane and 42% air. Such mixtures have a calorific value of 55902 and 2080 kJ / m ^3, respectively.

The cost of gas-air mixture produced at individual gas installations will be less than 40% of its ratio to the purchase price of commercial liquefied gas at gas stations, as air is drawn into the mixer from the surrounding atmosphere of the kitchen, where the individual gas-balloon installation is located without the use of an air-blowing device.

Combustible gas with different densities and heat of combustion is fed to the gas-burning device of a gas device, where it is autonomously mixed with air before being fed to the combustion.

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The processes and conditions for the formation of gas-air mixtures, as a rule, occur in gas-burning device devices. There are numerous gas-burning devices with various ways of mixing gas with air, which practically do not provide fast and complete combustion of fuel. The resulting gas-air mixture in the mixing chamber of these gas-burning devices does not have a constant composition, density and calculated heat of combustion, which leads to a change in thermal power, the deterioration of the technical and economic indicators of the installations.

Known installation for obtaining a mixture of combustible gas with air based on the use of liquefied gas propane-butane fraction from ground tank installations (NA Staskevich, PB Mayzels, D.Ya. Vigdorchik. Handbook of liquefied petroleum gases, L .: Nedra, 1964, pp. 395-398).

The installation includes gas storage tanks, gas drying heaters, air compressors, ejectors to form a gas / air mixture. Gas consumption during the day is uneven, therefore the installation is equipped with three or four ejectors, which are automatically switched on and off depending on the magnitude of gas consumption. The unit is equipped with expensive air compressors and sophisticated instrumentation, which increases the cost of fuel.

As a result of using such a gas-air mixture, part of the gas (10-15 vol.%) Is not oxidized to CO ₂ and in the form of unsaturated hydrocarbons (Cn H2p) and carbon monoxide (CO) enters the atmosphere as part of the combustion products. At the same time, part of the valuable hydrocarbon fuel is lost, the atmosphere of the combustion zone (industrial and domestic premises) is polluted, as well as the rapid deterioration of gas burner devices.

A disadvantage of the known gas mixing and gas distribution systems is that the heat of combustion and density of gas-air mixtures delivered to the consumer, in contrast to GOST 5542-87 "Natural combustible gases for industrial and domestic purposes", GOST 20448-90 "Gases hydrocarbon liquefied fuel for household consumption ", GOST 27577-87" Compressed natural fuel gas for gas-filled vehicles and GOST 27578-57 "Liquefied hydrocarbon gases for road transport" are different in heating value and density, and consequently incomplete combustion gas occurs in gas burner devices, disturbed operation mode of gas appliances, but also reduced plant productivity, increased specific fuel consumption of the gas per unit of output.

The economic efficiency, reliability and safety of gas appliances operation is characterized by complete combustion of gas and stable operation of gas-burning devices.

Installed gas appliances are designed for a specific heat output and, therefore, it is very important that they are operated at normal thermal load.

In practice, it is not always possible to strictly ensure the supply of combustible gas fuel with certain parameters; air supply in quantities sufficient for complete combustion of the gas, as well as good pre-mixing of the gas with the primary air sucked in by the gas stream into the burner; ignition of the gas-air mixture and maintaining in the combustion zone temperatures that are sufficient to ignite the combustible components of the mixture that have not yet burnt down; timely removal of combustion products from the combustion zone without disturbing the processes of gas combustion.

Failure to comply with even one of these conditions will necessarily lead to abnormal operation of the gas-burning device of household gas appliances.

Thus, the main indicators of the perfection of the operation of gas appliances are their efficiency and the completeness of the combustion of liquefied gas.

Device and principle of operation

The design of the ejector is shown in figure 1. The ejector is made according to the scheme with a central supersonic nozzle of the active gas. The active gas is supplied through nipple 1. A passive stream is fed through the nozzle 6. A non-return valve 11 prevents gas from entering the air line when the ejector is disturbed (for example, if gas is abruptly stopped). The gas flow, passing through the nozzle 2, accelerates to supersonic speeds with a decrease in pressure. The minimum pressure P in the design modes of operation is achieved in the inlet part of the mixing chamber 7. Under the action of the differential pressure P _atm- P, atmospheric air flows through the nozzles, filter 9, 4 and nozzle 6 into the mixing chamber, where the active and suction flows are mixed. The pressure along the length of the mixing chamber gradually increases. A further increase in pressure occurs in the subsonic diffuser and reaches the pressure P _out in the branch pipe.

The operating modes of the ejector depend on the pressure ratio on the ejector P = P _I / P _out , the ejection ratio n = (passive gas consumption / active gas consumption). Connecting parts 3, 5, 8, 10, 12 are components of the device ejector.

2. The change in the degree of compression of the ejector ε = P _out / P _o and the required minimum pressure ratio P = P _in / R _out depending on the volume ejection coefficient (m ³ / m ³ ) is shown. When the compression ratio P _out / P _o = 1.8 ejector provides ejection ratio 0.45-0.55. The ratio of the pressure on the ejector should be P> 2.8.

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When the pressure ratio at the nozzle of air suction B / P _o > 1.2, a critical flow is established in the throat of the nozzle. A further decrease in the pressure P _o in the receiving chamber does not lead to an increase in the flow through the air suction nozzle.

If the overpressure of the mixture at the outlet of the ejector does not exceed 0.4-0.5 atm, an increase in the pressure of the active gas will lead to a decrease in the ejection coefficient (decrease in the air content in the mixture). A decrease in the pressure of the active gas in comparison with the nominal value, on the contrary, leads to an increase in the ejection coefficient.

Installation of the ejector

The ejector is connected to the gearbox on the propane-butane gas cylinder using the union nut of the ejector. The output of the ejector is connected to the gas device using a standard welding sleeve DN 10. The sleeve on the output nipple 8 must be secured with a clamp.

It is possible to mount the ejector directly on the stop valve of a cylinder with a propane-butane mixture.

Ejector performance check

FIG. 3. Testing the ejector is carried out in compressed air. Assemble the circuit according to FIG. 3 a. Connect a vacuum gauge M2 to the suction line of the ejector through a welding hose. The exhaust from the ejector is carried to the atmosphere. Gear 2 to gradually increase the pressure of the active gas. When the minimum pressure is reached, note the pressure value of the active gas. This pressure should be 2.7-3 atm. The compression ratio should be 8-10.

Check the operation of the check valve. Assemble the circuit of FIG. 3b. Open valve 5; create pressure reducer 3, pressure 2-5 atm. Slowly close the valve 5. At a certain pressure on the M3 gauge, the air will stop. Further covering of the valve 5 causes the check valve to close. Record the mixture pressure limit resulting in a check valve.

The objective of this technical solution is to eliminate the above disadvantages in the system of an individual gas-cylinder installation by obtaining and submitting to the gas-air mixture system an optimum calorific value.

The solution of the problem is carried out by introducing into the system a gas cylinder installation of an adjustable device for obtaining a gas-air mixture of partial mixing for supplying it to a gas burner device.

The invention of an ejector device for an individual gas balloon installation of optimum calorific value is illustrated in FIG. 1 and a brief explanation of the device and principles of operation.

Claims (2)

CLAIM 1. Individual gas cylinder installation containing a cylinder for liquefied gas, connected by a pipeline, equipped with a control and stop valves, with a gas device, characterized in that an ejector gas-air mixer is built into the pipeline. 2. Installation according to claim 1, characterized in that the ejector gas-air mixer contains a supersonic nozzle oriented in the direction of the gas device, an insert is installed behind the supersonic nozzle with a gap, forming a mixing chamber, a check valve with a nozzle for supplying passive gas is mounted above the gap, the outlet which communicates with the said gap.