EA005471B1 - Method for combusting natural gas in approach flow - Google Patents

Abstract

The invention can be used for industry, public service and other branches of national economy, which use natural gas as the energy vector. The natural gas delivery is carried out through gas-dividing orifices. The ratio between the orifices spacing and the diameter thereof is equal to 2-5. The use of the inventive method for combusting natural gas in an approach flow makes it possible to obtain an effective carburation, ensure an effective cooling of elements of a gas-fired burner with the aid of fuel. The invention also makes it possible to develop an ecological gas-fired burner.

Description

Technical field

The invention relates to industry, utilities, energy and other industries using natural gas as an energy carrier, in particular to methods of burning natural gas.

State of the art

Known methods of burning natural gas in a free flow of air formed quite a long time ago. When these methods are implemented, principles are implemented in practice that allow for the formation of turbulence and relatively uniform gas distribution to provide mixture formation for complete combustion of fuel. In this case, stabilization of combustion is carried out due to the recirculation of high-temperature flue gases (aerodynamic stabilization), a standby torch and a heated body. The main problem in organizing the working process of gas burner devices is the mixture formation and aerodynamic stabilization of the flow due to swirling of the air flow (“Theory and Practice of Gas Combustion”, T.6, edited by A. S. Isserlin and M. I. Pevzner, Leningrad, Nedra , Leningrad Branch, 1975, p. 10-18, 47-57, 79-83).

The main disadvantage of this method is the high hydraulic resistance, relatively low completeness of combustion and the unevenness of the temperature field, which causes overheating of the fire-fighting facility. The swirling of the flow does not solve most of the problems of mixture formation, and often worsens the economic and environmental performance of the gas burner device, causes combustion pulsations, etc.

A known method of burning natural gas in a free flow of air, adopted as a prototype, including the supply of natural gas, air supply, mixture formation, ignition, stabilization ("Theory and practice of gas combustion", T.6, edited by AS Isserlin and M. I. Pevzner, Leningrad, Nedra, Leningrad Branch, 1975, p. 10-18, 47-57, 79-83).

The disadvantage of this method is the insufficiently efficient combustion of natural gas.

SUMMARY OF THE INVENTION

The basis of the invention is the task of increasing the efficiency of burning natural gas through the use of a highly efficient method of burning natural gas in the incoming air stream by organizing the optimal flow structure and intensive mixture formation, which ensures complete combustion of the fuel.

The problem is solved in that according to the invention, in a method of burning natural gas in a free-flowing air stream, including air supply, supplying natural gas through gas-distributing holes of gas burner devices, mixing, igniting a mixture of natural gas and air, supplying natural gas through gas-distributing holes, distance ratio between which to their diameter is 2-5. Natural gas is supplied perpendicular to the incoming air flow.

The proposed method of burning natural gas in a free flow of air provides the maximum possible completeness of combustion of natural gas due to

1) optimization of gas distribution, which provides the necessary initial separation of the fuel flow;

2) effective mixture formation of air and natural gas;

3) the formation of a stable zone of recirculation flow by air flow from the outside and gas from the inside;

4) the possibility of effective cooling of the elements of the gas burner device.

To maximize the above possibilities, the combustion of natural gas in an oncoming air stream is carried out as follows: gas is supplied through gas-distributing openings located with a certain relative step, namely, a relative step constituting

2-5 dimensionless units. The relative step is the ratio of the distance between the axes of the gas distribution holes 8 to the diameter of the gas distribution holes b. Experimental and theoretical studies of the influence of a wide range of operating and design factors on the flow structure and composition of the mixture in the reverse current zone behind the stabilizer jets, which is located some distance downstream behind the single-row jets, revealed the main factor - the relative pitch of the gas-distributing holes and its optimal value. The value of the relative step, allowing to realize the optimal combustion mode of natural gas in the incoming air flow, ranges from 2-5. The use of a relative step outside this range negatively affects the process of burning natural gas due to a change in the average composition of the gas mixture in the reverse current zone and the deterioration of the aerodynamic structure of the flow. The aerodynamic structure of the gas-air mixture flow is considered optimal if the so-called reverse current zones that exist behind each gas mixture jet interact successfully. These individual reverse current zones are connected into a single reverse current zone behind the jet system. A reverse current zone is also formed when the stabilizer flows around a gas-air mixture. The average composition of the mixture in the reverse current zone behind the jet system and behind the stabilizer depends entirely on the relative pitch of the gas-distributing openings and does not depend on their diameter. The specified range of values of the relative pitch of the holes 8/6 = 2-5 shoes

- 1 005471 is explained by the fact that the authors conducted a study showing that starting from a relative step of 8/6 = 5 or less, a significant mutual influence of gas jets begins, a single zone of mutual influence of gas jets forms, a single zone of reverse currents behind jets forms, which contributes to the redistribution of the mixture beyond jets, which contributes to the redistribution of the mixture for jets over the cross section, equalization of concentrations. In addition, studies have shown that it is from a value of 8/6 = 5 that the gas concentration of the fuel-air mixture in the flame stabilization zone corresponds to the combustible limits.

The value of the relative step 8/6 = 2 corresponds to the minimum possible step at which combustion in the stabilization zone is possible, because a decrease in the relative step from 5 to 2 entails a change in the concentration limits of the gas in the fuel-air mixture from the lower concentration limit of ignition (8/6 = 5), at which the concentration in the stabilization zone is about 5% to the upper concentration limit of ignition (8 / 6 = 2), at which the concentration is about 20%.

The value 8/6 = 5 should be used in burner devices in which a short flame is required and the temperature of the combustion products is not higher than 1300-1400 ° C, and 8/6 = 2 should be used in devices in which a long glowing torch is required. In addition, it was found that it is in this range of relative steps that the recirculation zone formed by the system of jets interacts with the recirculation zone formed by the flame stabilizer, which leads to an increase in the size of the recirculation zone and, accordingly, to increased combustion stability, which, in turn, increases the efficiency of burning natural gas.

Thus, the method of burning natural gas in an oncoming air stream can be implemented in a gas burner device with various configurations of housing elements, including poorly streamlined ones.

Brief Description of the Drawings

The following is a more detailed description of the invention with examples of constructive implementation of the inventive method of burning natural gas in burners of fire-fighting facilities for various purposes and with reference to the accompanying drawings, where FIG. 1 is a diagram of the interaction of a natural gas stream with a reverse current zone formed by a rectangular recess;

FIG. 2 is a general view of a gas burner device with a rectangular recess;

FIG. 3 is a diagram of the interaction of a natural gas stream with a reverse current zone formed by a ledge;

FIG. 4 is a General view of the gas burner device with a ledge;

FIG. 5 is a diagram of the interaction of a natural gas stream with a zone of reverse currents formed by a cone;

FIG. 6 is a General view of the gas burner device with a cone;

FIG. 7 is a diagram of the interaction of a natural gas stream with a reverse current zone formed by a torus, FIG. 8 is a general view of a gas burner device with a torus;

FIG. 9 is a diagram of the interaction of a natural gas stream with a reverse current zone formed by a pylon;

FIG. 10 is a general view of a gas burner device with a pylon.

A gas burner device that implements this method includes a housing 1, gas-distributing holes 2 for the release of natural gas and the formation of a gas-air mixture 3 in the direction of the reverse current zone 4, made with a diameter of 6, located at a distance of 8.

In FIG. 1, 2 shows a diagram of a burner device, the stabilization of combustion in which is carried out by a recirculation flow in a niche made in the stabilizer body. This scheme is used in objects with high freestreaming speeds. An example is the lances of metallurgical furnaces, the combustion chambers of gas turbine engines.

In Fig 3, 4 presents a diagram of a burner device, the stabilization of combustion in which is carried out by a recirculation flow behind a ledge made in the stabilizer body. This scheme is used in facilities with high free-air velocities and stringent cooling requirements for the stabilizer. An example is the afterburning blocks of high-temperature combustion products.

In FIG. 5 and 6 show a diagram of a burner device, the stabilization of combustion in which is carried out by a recirculation flow in a conical cavity, made at the end of the stabilizer body. This scheme is used in round-shaped burners of small diameter. An example of dried, low-heat furnaces.

In FIG. 7 and 8 show a diagram of a burner device, the stabilization of combustion in which is carried out by a recirculation flow behind the end of the stabilizer body. This scheme is used in burners with large heat output. An example is rotary kilns, heating wells, etc.

- 2 005471

In FIG. 9 and 10 show a flat element of a burner device, the stabilization of combustion in which is carried out by a recirculation flow behind a rectangular end face. This scheme is used in general-purpose burner devices, which do not have special requirements for the speed of the incoming flow, temperature conditions, etc.

The above schemes can be considered both independently and in combination with each other.

Best of Embodiments

A gas burner device that implements the inventive method comprises a housing 1, gas-distributing holes 2 for the release of natural gas and the formation of a gas-air mixture 3 in the direction of the reverse current zone 4, made with a diameter of ά, located at a distance of 8 from each other.

G gas burner device operates as follows. Natural gas is fed into the housing 1 of the gas burner device and through gas-distributing holes 2 is directed into the oncoming air stream, mixed with it, forming a gas-air mixture 3. The incoming air stream directs the gas-air mixture 3 in the direction of zone 4 formed by the stabilizer of the housing 1. The resulting gas-air mixture ignites, and the flame is stabilized by the recirculation flow in the zone of reverse currents 4. In this case, the relative pitch of the gas-distributing holes 2 ensures that the mixture in the zone of reverse currents 4 stable ignition limits independent of the operating conditions of the burner device.

Thus, the combustion of natural gas with the supply of the latter through gas-distributing openings made with a relative step of 2-5 perpendicular to the air flow in front of the reverse current zone is a highly efficient method of burning natural gas in the oncoming air flow, which allows efficient mixture formation, which makes it possible to ensure ecological purity of the gas burner device and its reliability.

Claims (2)

CLAIM 1. A method of burning natural gas in the incoming air flow, including the supply of air, the supply of natural gas through gas distribution openings of gas-burning devices, mixing air and natural gas, igniting a mixture of air and natural gas, and stabilizing a torch, characterized by the supply of natural gas through gas distribution holes, the ratio of the distance between them to their diameter is the value of 2-5. 2. The method of burning natural gas in the incoming flow of air according to claim 1, characterized in that the natural gas is supplied perpendicular to the incoming flow of air.