CN109945189B - A low-concentration gas pulsating burner with improved main pipe - Google Patents

Abstract

The invention discloses a low-concentration gas pulsation burner with an improved main pipe, which comprises a gas burner, wherein the gas burner is of a columnar cylinder structure, an inner cavity of the gas burner is a columnar combustion chamber, and two ends of the combustion chamber are respectively provided with a low-concentration gas inlet and a smoke exhaust outlet; the invention has simple structure, increases the enrichment structure, and periodically supplies pure methane to the combustion chamber in a state of relatively low gas concentration, thereby enriching the combustion chamber and solving the problem that the concentration is too low to continuously burn.

Description

A low-concentration gas pulsating burner with improved main pipe

technical field

The invention belongs to the field of gas combustion.

Background technique

As a special combustion method, pulse combustion is neither deflagration nor normal combustion but in between. Give it the excitation of certain conditions, so that the acoustic pulsation generated by it and the thermal pulsation generated in the combustion process achieve a certain acoustic-thermal coupling, and then periodic pulsating combustion can be generated. During the combustion process, the state parameters that characterize the combustion characteristics, such as pressure, temperature and heat release rate, change periodically with time, which has the advantages of high combustion efficiency, large heat transfer coefficient, small pollution emission, and self-priming supercharging. The use of pulse combustion technology can effectively deal with the combustion of low-concentration gas;

Since the concentration of the gas source is not a stable value, the low-concentration gas that is pressed into the combustion chamber from the main pipe may have the problem of too low methane concentration. It is impossible to maintain the continuity of multiple pulsation cycle combustion.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a low-concentration gas pulsation burner that can enrich the combustion chamber under the condition of low gas methane concentration.

Technical solution: In order to achieve the above object, an improved main pipe low-concentration gas pulsation burner of the present invention includes a gas burner, the gas burner is a columnar cylinder structure, and the inner cavity of the gas burner is a columnar combustion The two ends of the combustion chamber are respectively provided with a low-concentration gas inlet and a smoke exhaust outlet; the outer side of the gas burner is integrated with an annular methane enrichment box, and the annular methane enrichment box There is an annular pure methane pressure accumulator in the thick box; an annular methane enrichment cavity layer is arranged concentrically between the pure methane pressure accumulator and the combustion chamber; the pure methane accumulator The methane enrichment cavity layer is separated by a first ring wall, and the methane enrichment cavity layer is separated from the combustion chamber by a second ring wall; the two sides of the second ring wall are along the A number of methane enrichment holes are evenly distributed on the axis in a circular array, and each of the methane enrichment holes connects the methane enrichment cavity layer and the combustion chamber with each other;

A number of first air guide channels are distributed in a circular array on the first ring wall, and the inner ends of each of the first air guide channels are connected to the methane enrichment cavity layer, and the pure methane pressure storage chamber is also It includes a rotating gas distribution ring body, the rotating gas distribution ring body is rotatably socketed on the outside of the first ring wall, and the middle part of the inner ring of the rotating gas distribution ring body is integrated and coaxially provided with an annular flange. The inner wall of the annular flange blocks the outer ends of each of the first air guide channels, and a plurality of second air guide channels are distributed in a circular array on the annular flange, and the outer ends of each of the second air guide channels are connected to each other. In the pure methane pressure storage chamber, the inner ends of each of the second gas guide channels can be rotated synchronously with the annular flange to align with the outer ends of several first gas guide channels; The gas outlet end of the pure methane pressurized supply pipe communicates with the pure methane pressure storage chamber.

Further, each of the first gas guide channels is provided with a one-way valve to prevent gas backflow, and the one-way valve can prevent the gas in the methane-enriched cavity layer from flowing back through the first gas guide channel to pure In the methane pressure storage chamber; two bearings are installed symmetrically on both sides of the annular flange of the inner ring of the rotary gas distribution ring; The cavity is also fixedly installed with a motor, the output shaft of the motor is synchronously connected with an output gear, and the output gear is meshed with a ring of teeth on the rotating gas distribution ring body, and the motor drives the The rotating gas distribution ring body rotates along the axis.

Further, it also includes a long columnar gas distribution box, one side of the gas distribution box is vertically connected with the low-concentration gas inlets of the five gas burners, and the gas distribution box is far away from the five gas burners There is a low-concentration pulsating gas supply pipe vertically connected to one side of the gas distribution box; five of the gas burners are distributed in an array along the length of the gas distribution box, and the outlet of the low-concentration pulsating gas supply pipe is not aligned with any one of the gas The air inlet of the burner.

Beneficial effects: the structure of the present invention is simple, and this scheme adds a enriched structure, and in the state of relatively low gas concentration, it periodically supplies pure methane to the combustion chamber, and then enriches the combustion chamber, solving the problem of gas concentration Too low to burn continuously.

Description of drawings

Accompanying drawing 1 is the combined structure of the burner after transformation;

Accompanying drawing 2 is the CFD analysis speed nephogram of the combined structure of the combustor after transformation;

Accompanying drawing 3 is the CFD analysis local vector velocity nephogram of gas burner;

Accompanying drawing 4 is the structural representation after adding the methane enrichment box on the burner;

Accompanying drawing 5 is the first three-dimensional sectional view of accompanying drawing 4;

Accompanying drawing 6 is the second perspective sectional view of accompanying drawing 4;

Accompanying drawing 7 is the 3rd perspective sectional view of accompanying drawing 4;

Accompanying drawing 8 is the schematic diagram of the structure of the rotating gas distribution ring body.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in accompanying drawings 1 to 8, an improved main pipe low-concentration gas pulsation burner includes a gas burner 10, the gas burner 10 is a columnar cylinder structure, and the inner cavity of the gas burner 10 is columnar Combustion chamber 12, the two ends of the combustion chamber 12 are respectively provided with a low-concentration gas inlet and smoke exhaust outlet; the outer side of the gas burner 10 is integrally provided with an annular methane enrichment box 18, the The annular methane enrichment box 18 is an annular pure methane accumulator chamber 2; an annular methane enrichment chamber is coaxially arranged between the pure methane accumulator chamber 2 and the combustion chamber 12. Chamber layer 7; the pure methane pressure storage chamber 2 and the methane enrichment cavity layer 7 are separated by the first ring wall 1, and the methane enrichment cavity layer 7 and the combustion chamber 12 are separated by The second ring wall 9 is separated; both sides of the second ring wall 9 are evenly distributed with a number of methane enrichment holes 11 in a circular array along the axis, and each of the methane enrichment holes 11 enriches the methane cavity layer 7 communicate with the combustion chamber 12;

A plurality of first air guide channels 14 are distributed in a circular array on the first ring wall 1, and the inner ends of each of the first air guide channels 14 are connected to the methane enrichment cavity layer 7, and the pure methane storage The pressure chamber 2 also includes a rotary gas distribution ring body 6, which is rotatably socketed on the outside of the first ring wall 1, and the middle part of the inner ring of the rotary gas distribution ring body 6 is integrated and coaxial The center is provided with an annular flange 21, the inner wall of the annular flange 21 blocks the outer ends of each of the first air guide passages 14, and a plurality of second air guide passages 17 are distributed in a circular array on the annular flange 21. The outer ends of each of the second air guide passages 17 are connected to the pure methane pressure storage chamber 2, and the inner ends of each of the second air guide passages 17 can be rotated synchronously with the annular flange 21 to be respectively aligned and communicated with several first air guide passages. The outer end of a gas guide channel 14 also includes a pure methane pressurized supply pipe 8 , and the gas outlet end of the pure methane pressurized supply pipe 8 communicates with the pure methane pressure storage chamber 2 .

Each of the first gas guide channels 14 is provided with a one-way valve 13 to prevent gas backflow, and the one-way valve 13 can prevent the gas in the methane-enriched cavity layer 7 from flowing back through the first gas guide channel 14 into the pure methane pressure storage chamber 2; two bearings 16 are mounted on both sides of the annular flange 21 of the inner ring of the rotating gas distribution ring body 6 for symmetrical rotation; the outer ring of the rotating gas distribution ring body 6 is provided with a ring of teeth body 25, the pure methane pressure storage chamber 2 is also fixedly installed with a motor 5, the output shaft 4 of the motor 5 is synchronously connected with an output gear 3, and the output gear 3 is connected to the rotary gas distribution ring body 6 A ring of tooth bodies 25 is engaged and connected, and the motor 5 drives the rotating gas distribution ring body 6 to rotate along the axis through the output gear 3 .

It also includes a long columnar gas distribution box 91. One side of the gas distribution box 91 is respectively vertically connected with five low-concentration gas inlets of the gas burner 10. The gas distribution box 91 is far away from the five gas combustion chambers. One side of the device 10 is vertically connected with a low-concentration pulsating gas supply pipe 90; the five gas burners 10 are distributed in an array along the length direction of the gas splitter box 91, and the outlet of the low-concentration pulsating gas supply pipe 90 is incorrect It is the air inlet of any one of the gas burners 10 .

The pulsating combustion method, process and technical progress of our enrichment process:

The gas source is a mixed gas containing CH4, O2, N2, and CO2, where the concentration of O2 is sufficient for the combustion reaction of CH4:

When the concentration of CH4 in the gas source exceeds 4%, there is no need to enrich CH4 in the combustion chamber 22; at this time, the pure methane pressurized supply pipe 8 does not supply pure methane to the pure methane pressure storage chamber 2; at this time, the check valve 13 It can prevent the gas in the methane-enriched cavity layer 7 from flowing back into the pure methane pressure storage chamber 2 through several first gas guide channels 14; then, under the action of the gas pump, the gas is pulsated through the low-concentration pulsating gas supply pipe 90 Gas is continuously supplied to the gas distribution box 91 in the form of a period; then the inside of the gas distribution box 91 forms a continuous pulsating air pressure, and then the gas in the gas distribution box 91 is pulsating periodically to the combustion chamber 12 of each gas burner 10 Gas injection; after the gas in the combustion chamber 12 is ignited by the ignition device, a continuous pulsating flame is formed in the combustion chamber 12, and the high-temperature exhaust gas generated by combustion in the combustion chamber 12 continues to pass through the exhaust end of the combustion chamber 12 in the form of a tail flame. and then the tail flames ejected from each exhaust straight pipe 20 heat the heat-using equipment; thereby realizing the utilization of gas;

When the concentration of CH4 in the gas source is less than 4%, then under the action of the gas pump, the gas will be continuously supplied to the gas distribution box 91 in the form of pulsating cycle through the low-concentration pulsating gas supply pipe 90; Continuous pulsating air pressure is formed inside, and then the gas in the gas distribution box 91 is pulsating and cyclically spraying gas gas into the combustion chamber 12 of each gas burner 10; due to the CH4 concentration in the gas ejected through several gas gas guide holes 77 is less than 4%, the combustor 12 cannot be ignited smoothly or cannot maintain the continuity of multiple pulsation cycle combustion, it is necessary to enrich the CH4 in the combustor 12; at this time, the pure methane pressurized supply pipe 8 presses the pure methane into the pure methane storage In the pressure chamber 2, and the pure methane pressurized supply pipe 8 continuously maintains the air pressure in the pure methane pressure storage chamber 2, and ensures that the air pressure in the pure methane pressure storage chamber 2 is always greater than the air pressure in the combustion chamber 12. At this time, start the motor 5 , and then the motor 5 drives the rotating gas distribution ring body 6 to rotate along the axis through the output gear 3, and then the annular flange 21 rotates synchronously with the rotating gas distribution ring body 6, and the periodic rotation of the annular flange 21 makes each second guide The inner end of the gas channel 17 is periodically rotated to align with the outer ends of the first gas guide channels 14, so that the pure methane pressure storage chamber 2 and the methane enrichment cavity layer 7 are periodically connected to each other, Further, the methane in the pure methane pressure storage chamber 2 is periodically injected into the methane-enriched cavity layer 7 with pure CH4 through several first gas-guiding channels 14, so that pure CH4 is formed in the methane-enriched cavity layer 7 The pulsating air pressure, and then the CH4 pulsating gas in the methane enrichment cavity layer 7 passes through several methane enrichment holes 11 to pulsate and periodically press pure CH4 into the combustion chamber 12. By controlling the output gear 3 speed of the motor 5, and then control Rotate the gas distribution ring body 6 to make the period and pace of the pure methane pressure storage chamber 2 and the methane enrichment cavity layer 7 periodically communicate with each other and the cycle and pace of the gas distribution box 91 injecting gas into the combustion chamber 12 Consistent; further realize the enrichment of gas for each pulsating combustion cycle in the combustion chamber 12, to ensure continuous pulsating combustion in the combustion chamber 12; furthermore, the high-temperature exhaust gas generated by combustion in the combustion chamber 12 continues to pass through the exhaust smoke of the combustion chamber 12 end is ejected in the form of tail flame, and then the tail flame ejected from each exhaust straight pipe 20 heats the heat-using equipment; thereby realizing the utilization of gas; at the same time, methane enriches the gas in the cavity layer 7 The pure methane gas can absorb the heat generated after combustion in the combustion chamber 12 through the second ring wall 9, and then what the several methane enrichment holes 11 inject into the combustion chamber 12 is preheated pure CH4, thereby effectively improving the combustion chamber 12. internal combustion efficiency.

CFD numerical simulation method is used to verify the structural rationality and technical progress of the burner:

Use ANSYS Fluent16.0 to complete the numerical simulation under the grid. First, check the grid to ensure that there are no negative values in the grid area and volume, and the influence of gravity is not considered.

In the model, the flow process is set as a pressure-based steady-state flow, and since we are mainly concerned about the flow of low-concentration gas, it is assumed that the fluid is a mixture of CH4 and air, and the multi-component model is used to numerically calculate its flow in the burner pipe. The distribution of the flow field in .

Model settings: energy equation, standard turbulence equation, component transport equation;

Material settings: the fluid is methane-air, the solid wall is the default aluminum;

Boundary condition setting: inlet boundary condition: velocity inlet, set the supply velocity of the low-concentration pulsating gas supply pipe 90 to 1.5m/s; outlet boundary condition: the smoke exhaust outlet of the combustion chamber 12 is the atmospheric pressure outlet; turbulence index: turbulence intensity +hydraulic diameter;

Temperature: 300K;

Components: 4% CH4, 19.74% O2, 2.82% CO2, 73.44% N2;

Solution method: SIMPLE single precision, the gradient is based on the grid using the least squares method, the pressure uses the second-order upwind, the momentum uses the first-order upwind, the turbulent kinetic energy uses the first-order upwind, and the turbulent dissipation rate uses the first-order upwind;

Residual monitoring: the convergence accuracy of all parameters is set to 0.001;

Iteration step size: 1000;

Initialization, during the calculation process, at step 324, all indicators converge to the set accuracy;

The overall velocity cloud diagram of the burner obtained after the simulation is shown in Figure 2. From the velocity cloud diagram, it can be seen that the outlet of the low-concentration pulsating gas supply pipe 90 is not aligned with any one of the gas burner 10. A better velocity field, as can be seen from the local vector velocity cloud diagram of the CFD analysis of the gas burner in Fig. It is entrained to the root of the flame and transfers heat with the new gas. During the initial ignition period, the effect of the recirculation zone will be more obvious. The high-temperature flue gas will flow back to the root of the burner from the beginning, and its flow rate will increase. The recirculated flue gas is mixed with the medium in the main flow to carry out efficient momentum transmission, which promotes the exchange and mixing of old and new gas in the recirculation area, thereby further making the temperature distribution inside the combustion chamber more uniform; The unburned gas at the root of the combustion chamber will be reburned at the root together with the new gas, which plays an important role in the complete combustion of the gas.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (2)

1. An improved low-concentration gas pulsation burner for the main pipe, characterized in that it includes a gas burner (10), the gas burner (10) is a columnar cylinder structure, and the inner gas burner (10) The cavity is a columnar combustion chamber (12), and the two ends of the combustion chamber (12) are respectively provided with a low-concentration gas inlet and a smoke exhaust outlet; the outer side of the gas burner (10) is integrally provided with an annular methane enrichment box (18), the ring-shaped methane enrichment box (18) is a ring-shaped pure methane pressure storage chamber (2); the pure methane pressure storage chamber (2) and the An annular methane enrichment cavity layer (7) is also coaxially arranged between the combustion chambers (12); between the pure methane pressure storage chamber (2) and the methane enrichment cavity layer (7) Separated by the first ring wall (1), the methane enrichment cavity layer (7) is separated from the combustion chamber (12) by a second ring wall (9); the second ring wall (9) There are a number of methane enrichment holes (11) evenly distributed in a circular array along the axis on both sides of the side, and each of the methane enrichment holes (11) connects the methane enrichment cavity layer (7) with the combustion chamber (12) connected to each other; A number of first air guide channels (14) are distributed in a circular array on the first ring wall (1), and the inner ends of each of the first air guide channels (14) are connected to the methane enrichment cavity layer ( 7), the pure methane pressure storage chamber (2) also includes a rotating gas distribution ring body (6), and the rotating gas distribution ring body (6) is rotatably socketed on the outside of the first ring wall (1), The middle part of the inner ring of the rotating gas distribution ring body (6) is integrated and coaxially provided with an annular flange (21), and the inner wall of the annular flange (21) blocks each of the first air guiding channels (14 ), the annular flange (21) is distributed with a number of second air guide channels (17) in a circular array, and the outer ends of each of the second air guide channels (17) are connected to the pure methane storage The pressure chamber (2), the inner end of each second air guide channel (17) can rotate synchronously with the annular flange (21) to align with the outer ends of several first air guide channels (14); A methane pressurized supply pipe (8), the outlet end of the pure methane pressurized supply pipe (8) communicates with the pure methane pressure storage chamber (2); Each of the first gas guide channels (14) is provided with a one-way valve (13) to prevent gas backflow, and the one-way valve (13) can prevent the gas in the methane enrichment cavity layer (7) from passing through The first gas guide channel (14) flows back into the pure methane pressure storage chamber (2); the two sides of the annular flange (21) of the inner ring of the rotating gas distribution ring body (6) are also symmetrically rotated and installed with two bearings ( 16); the outer ring of the rotating gas distribution ring body (6) is provided with a ring of teeth (25), and the pure methane pressure storage chamber (2) is also fixedly installed with a motor (5), and the motor (5) The output shaft (4) is synchronously connected with an output gear (3), and the output gear (3) is meshed with a ring of teeth (25) on the rotating gas distribution ring body (6), and the motor ( 5) Drive the rotating gas distribution ring body (6) to rotate along the axis through the output gear (3); It also includes a long columnar gas distribution box (91), one side of the gas distribution box (91) is vertically connected with five low-concentration gas inlets of the gas burner (10), and the gas distribution box (91) The side away from the five gas burners (10) is vertically connected with a low-concentration pulsating gas supply pipe (90). 2. The low-concentration gas pulsation burner with improved main pipe according to claim 1, characterized in that: five said gas burners (10) are distributed in an array along the length direction of said gas distribution box (91), And the outlet of the low-concentration pulsating gas supply pipe (90) is not aligned with the air inlet of any one of the gas burners (10).