Background
It is well known that methane, the main component of gas, is a serious greenhouse gas, its greenhouse effect and CO 2 Compared with the water-soluble polymer, the water-soluble polymer is 24.6 times of the water-soluble polymer, and has higher capability of destroying the ozone layer of the atmosphere than CO 2 7 times of (3). Therefore, a large amount of low-concentration gas in mines is unavailable and discharged to the air every year, so that the limited non-renewable fossil energy is seriously wasted, and the greenhouse effect and the environmental pollution are aggravated. The combustion heat value of the gas is 35000-39000 kJ/m 3 Meanwhile, the natural gas can be used as a greenhouse gas and also plays a role of a high-quality energy source, and can be compared with the conventional natural gasThe material is used as a raw material in the energy chemical process.
However, the low-concentration gas has very low combustion content, the heat generated in the combustion process is far less than the heat dissipation in the environment, and the continuous combustion is very difficult, so that the combustion cannot be performed by adopting a conventional combustion device, and a special combustion mode and a corresponding burner are required for the low-concentration gas at the concentration.
Pulse combustion is a special combustion mode, and is not deflagration or abnormal combustion but is in between. The acoustic pulsation generated by the combustion device is stimulated under certain conditions to achieve certain acoustic-thermal coupling with the thermal pulsation generated in the combustion process, so that periodic pulsation combustion can be generated. The state parameters representing combustion characteristics such as pressure, temperature, heat release rate and the like in the combustion process periodically change along with time, and the method has the advantages of high combustion efficiency, larger heat transfer coefficient, smaller pollution discharge and self-priming supercharging, and can effectively treat the combustion of low-concentration gas by using a pulse combustion technology;
because the concentration of the gas source is not a stable value, the low concentration gas pressed into the combustion chamber from the main pipe may have a problem that the concentration of methane is too low, and even in the case of pulsating gas supply of the combustion chamber, the combustion chamber cannot be ignited smoothly or the continuity of combustion in a plurality of pulsation cycles cannot be maintained.
Disclosure of Invention
The invention aims to: in order to overcome the defects in the prior art, the invention provides the low-concentration gas pulse combustor with the wing pipe, which is more stable in combustion.
The technical scheme is as follows: in order to achieve the above purpose, the low-concentration gas pulsation burner with the wing pipe comprises a long columnar gas distribution box, wherein five gas burners are arranged on one side of the gas distribution box;
a gas pulsation supply pipe is further arranged at one side of the gas distribution box, which is far away from the plurality of gas burners, and the gas pulsation supply pipe and the gas distribution box are mutually perpendicular; the gas outlet end of the gas pulsation supply pipe is communicated with the middle part of a diversion cavity in the gas diversion box;
the two sides of the gas pulsation supply pipe are also symmetrically connected with a left wing pipe and a right wing pipe in a bypass way, and outlets of the left wing pipe and the right wing pipe are respectively communicated with two sides of a diversion cavity in the gas diversion box;
fifthly, the gas burners are distributed in an equidistant array along the axis of the gas distribution box; the axis of each gas burner is perpendicular to the axis of the gas distribution box; the gas burner is of a columnar cylinder structure, the inner cavity of the gas burner is a columnar combustion chamber, and the gas inlet end of each combustion chamber is communicated with a diversion cavity in the gas diversion box through at least five uniformly distributed gas guide holes; one end of each combustion chamber far away from the gas distribution box is a smoke exhaust end.
Further, a section of throat shrinkage channel with smaller inner diameter is arranged in the gas pulsation supply pipe, and the inner diameter of the throat shrinkage channel is half of the inner diameter of the left wing pipe/the right wing pipe; the bypass connection part of the gas pulsation supply pipe and the left wing pipe/the right wing pipe is a split flow part, and the throat shrinkage channel is positioned between the split flow part and the gas split flow box.
Further, the five gas burners sequentially comprise a first gas burner, a second gas burner, a third gas burner, a fourth gas burner and a fifth gas burner; the communication part of the outlet of the left wing pipe and the flow distribution cavity is positioned between the first gas burner and the second gas burner; the communication part between the outlet of the right wing pipe and the flow distribution cavity is positioned between the fourth gas burner and the fifth gas burner; the gas outlet end of the gas pulsation supply pipe and the third gas burner are coaxial with each other.
Further, an annular methane enrichment box body is integrally arranged on the outer side of the gas burner, and an annular pure methane pressure accumulation cavity is arranged in the annular methane enrichment box body; an annular methane enrichment cavity layer is also arranged between the pure methane pressure accumulation cavity and the combustion chamber in a coaxial way; the pure methane pressure accumulation cavity and the methane enrichment cavity layer are separated by a first annular wall, and a second annular wall is separated between the methane enrichment cavity layer and the combustion chamber; a plurality of methane enrichment holes are uniformly distributed on two sides of the second annular wall in a circumferential array along the axis, and each methane enrichment hole is used for communicating the methane enrichment cavity layer with the combustion chamber; the inner end of each first air guide channel is communicated with the pure methane pressure accumulation cavity, the inner end of each second air guide channel can synchronously rotate along with the annular flange to be respectively aligned and communicated with the outer ends of the first air guide channels; the pure methane pressure-accumulating cavity is communicated with the pure methane pressure-accumulating cavity through the gas outlet end of the pure methane pressure-accumulating supply pipe; a check valve for preventing the reverse flow of gas is arranged in each first gas guide channel, and the check valve can prevent the gas in the methane enrichment cavity layer from flowing back into the pure methane pressure accumulation cavity through the first gas guide channels; two bearings are symmetrically and rotatably arranged on two sides of the annular flange of the inner ring of the rotary gas distribution ring body; the outer ring of the rotary gas distribution ring body is provided with a circle of tooth body, the pure methane pressure accumulation cavity is fixedly provided with a motor, an output gear is synchronously connected to an output shaft of the motor, the output gear is in meshed connection with the circle of tooth body on the rotary gas distribution ring body, and the motor drives the rotary gas distribution ring body to rotate along the axis through the output gear.
The beneficial effects are that: the invention has simple structure, increases the wing pipe structure, effectively enhances the flame stability during the firing period in each combustion chamber, widens the upper limit of the flow velocity of the fuel gas entering the burner, can obtain a better velocity field, has uniform flow and greatly enhances the combustion stability under the optimized design scheme; meanwhile, the scheme also increases a thickening structure, and solves the problem that the concentration is too low to burn continuously.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
The low-concentration gas pulsation burner with the wing pipes as shown in the accompanying drawings 1 to 9 comprises a long columnar gas distribution box 79, wherein five gas burners 10 are arranged on one side of the gas distribution box 79;
a gas pulsation supply pipe 82 is further arranged on one side of the gas distribution box 79 away from the plurality of gas burners 10, and the gas pulsation supply pipe 82 and the gas distribution box 79 are mutually perpendicular; the gas outlet end of the gas pulsation supply pipe 82 is communicated with the middle part of the diversion cavity 78 in the gas diversion box 79;
the two sides of the gas pulsation supply pipe 82 are also symmetrically connected with a left wing pipe 84 and a right wing pipe 85 in a bypass way, and the outlets of the left wing pipe 84 and the right wing pipe 85 are respectively communicated with the two sides of the diversion cavity 78 in the gas diversion box 79;
fifthly, the gas burners 10 are distributed in an equidistant array along the axis of the gas distribution box 79; the axis of each gas burner 10 is perpendicular to the axis of the gas distribution box 79; the gas burner 10 is in a columnar cylinder structure, the inner cavity of the gas burner 10 is a columnar combustion chamber 12, and the gas inlet end of each combustion chamber 12 is communicated with a flow distribution cavity 78 in the gas flow distribution box 79 through at least five uniformly distributed gas guide holes 77; the end of each combustion chamber 12 far away from the gas distribution box 79 is a smoke exhaust end.
A section of throat shrinkage channel 88 with a smaller inner diameter is arranged in the gas pulsation supply pipe 82, and the inner diameter of the throat shrinkage channel 88 is half of the inner diameter of the left wing pipe 84/the right wing pipe 85; the bypass connection between the gas pulsation supply pipe 82 and the left wing pipe 84/right wing pipe 85 is a split portion 013, and the throat passage 88 is located between the split portion 013 and the gas split box 79.
The fifth gas burner 10 sequentially comprises a first gas burner 10.1, a second gas burner 10.2, a third gas burner 10.3, a fourth gas burner 10.4 and a fifth gas burner 10.5; the outlet of the left wing pipe 84 is located between the first gas burner 10.1 and the second gas burner 10.2 at the communication point of the split flow chamber 78; the connection between the outlet of the right wing pipe 85 and the diversion chamber 78 is located between the fourth gas burner 10.4 and the fifth gas burner 10.5; the gas outlet end of the gas pulsation supply pipe 82 and the third gas burner 10.3 are coaxial with each other.
An annular methane enrichment box 18 is integrally arranged on the outer side of the gas burner 10, and an annular pure methane pressure accumulation cavity 2 is arranged in the annular methane enrichment box 18; an annular methane enrichment cavity layer 7 is also arranged between the pure methane pressure accumulation cavity 2 and the combustion chamber 12 in a coaxial way; the pure methane pressure accumulation cavity 2 and the methane enrichment cavity layer 7 are separated by a first annular wall 1, and a second annular wall 9 is arranged between the methane enrichment cavity layer 7 and the combustion chamber 12; a plurality of methane enrichment holes 11 are uniformly distributed on two sides of the second annular wall 9 in a circumferential array along the axis, and each methane enrichment hole 11 is used for communicating the methane enrichment cavity layer 7 with the combustion chamber 12; a plurality of first air guide channels 14 are distributed on the first annular wall 1 in a circumferential array, the inner ends of the first air guide channels 14 are communicated with the methane enrichment cavity layer 7, the pure methane pressure accumulation cavity 2 further comprises a rotary air distribution ring body 6, the rotary air distribution ring body 6 is rotatably sleeved on the outer side of the first annular wall 1, the middle part of the inner ring of the rotary air distribution ring body 6 is integrally and coaxially provided with an annular flange 21, the outer ends of the first air guide channels 14 are blocked by the inner wall of the annular flange 21, a plurality of second air guide channels 17 are distributed on the annular flange 21 in a circumferential array, the outer ends of the second air guide channels 17 are communicated with the pure methane pressure accumulation cavity 2, and the inner ends of the second air guide channels 17 can synchronously rotate along with the annular flange 21 to be respectively aligned with the outer ends of the first air guide channels 14; the device also comprises a pure methane pressurizing supply pipe 8, wherein the air outlet end of the pure methane pressurizing supply pipe 8 is communicated with the pure methane pressure accumulation cavity 2; a check valve 13 for preventing the reverse flow of gas is arranged in each first gas guide channel 14, and the check valve 13 can prevent the gas in the methane enrichment cavity layer 7 from flowing back into the pure methane pressure accumulation cavity 2 through the first gas guide channels 14; two bearings 16 are symmetrically and rotatably arranged on two sides of an annular flange 21 of the inner ring of the rotary gas distribution ring body 6; the outer ring of the rotary gas distribution ring body 6 is provided with a circle of tooth bodies 25, the pure methane pressure accumulation cavity 2 is fixedly provided with a motor 5, an output gear 3 is synchronously connected to an output shaft 4 of the motor 5, the output gear 3 is in meshed connection with the circle of tooth bodies 25 on the rotary gas distribution ring body 6, and the motor 5 drives the rotary gas distribution ring body 6 to rotate along the axis through the output gear 3.
The structural rationality and technical progress of the burner are verified by adopting a CFD numerical simulation method:
numerical simulation under the grid was done using ANSYS fluent16.0, first checking the grid to ensure that its grid area and volume do not have negative values, regardless of gravity effects.
In the model, the flow process is set to be steady-state flow based on pressure, meanwhile, since the flow condition of low-concentration gas is mainly concerned, the flow field distribution of the fluid in the burner pipeline is calculated by adopting a multi-component model numerical value on the premise that the fluid is a mixed gas of CH4 and air.
Model setting: energy equation, standard turbulence equation, component transport equation;
the material setting: the fluid is methane-air, and the solid wall surface is default aluminum;
boundary condition setting: inlet boundary conditions: a speed inlet for setting the supply speed of the gas pulsation supply pipe 82 to 1.5m/s; outlet boundary conditions: the exhaust outlet of the combustion chamber 12 is an atmospheric pressure outlet; turbulence index: turbulence intensity + hydraulic diameter;
temperature: 300K;
the components are as follows: 4% ch4, 19.74% o2, 2.82% co2, 73.44% n2;
the solving method comprises the following steps: SIMPLE single precision, the gradient adopts a least square method based on grids, the pressure adopts second-order windward, the momentum adopts first-order windward, the turbulent kinetic energy adopts first-order windward, and the turbulent dissipation rate adopts first-order windward;
residual monitoring: all parameter convergence accuracy was set to 0.001;
iteration step length: 1000;
initializing, and converging each index to the set precision in the 324 th step in the operation process;
the CFD analysis speed cloud diagram of the burner combined structure with the wing pipe obtained after the simulation is finished is shown in fig. 2, the structure with the wing pipe can be seen from the speed cloud diagram, a better air inlet speed field can be obtained, the CFD analysis partial vector speed cloud diagram of the gas burner in fig. 3 can be seen, a double backflow area is generated in the combustion chamber 12, the partial speed vector diagram of the burner can be seen to obviously have two nearly symmetrical backflow areas in a flow field, the generation of the symmetrical double backflow areas enhances the gas combustion, and the following processes and phenomena are newly added in the process: the high-temperature smoke is continuously generated along with the combustion, and is sucked to the root of the flame along with the backflow phenomenon, so as to transfer heat with the newly-fed fuel gas. This means that a heat source is additionally arranged at the root of the burner, which has important significance for continuous combustion of gas; particularly during the initial ignition period, the effect of the reflux zone will be more pronounced; the high-temperature flue gas flows back to the root of the burner from the beginning, the flow speed of the high-temperature flue gas is larger and larger, the flue gas which flows back during the period is mixed with media in the main flow to carry out efficient momentum transfer, and the new and old fuel gases in the backflow area are mutually exchanged and mixed, so that the temperature distribution in the combustion chamber is further more uniform; part of unburned fuel gas flowing back to the root of the combustion chamber along with high-temperature flue gas can be re-combusted with the new fuel gas at the root, and the method plays an important role in complete combustion of the fuel gas. In summary, the comprehensive effect of the reflux zone is to make the gas in the burner burn stably and completely, promote the temperature in the combustion chamber to be uniform and the heat processing quality to be high; the flame stability during a fire at each pulse cycle is enhanced, widening the upper limit of the gas flow rate into the burner 10;
the method, the process and the technical progress of the enrichment mechanism of the scheme are as follows:
the gas source comprises CH 4、 O 2、 N 2、 CO 2 Wherein O is 2 Is of a concentration sufficient to CH 4 Is a combustion reaction of:
CH in gas source 4 At a concentration exceeding 4%, the combustion chamber 22 is not subjected to CH 4 Concentrating; at this time, the pure methane pressurizing supply pipe 8 does not supply pure methane into the pure methane pressure accumulation cavity 2; the check valve 13 can prevent the gas in the methane enrichment cavity layer 7 from flowing back into the pure methane pressure accumulation cavity 2 through the first gas guide channels 14; then continuously supplying the gas into the gas distribution box 79 in a pulse period mode through the gas pulse supply pipe 82 under the action of the gas pump; further, continuous pulsating air pressure is formed in the flow distribution cavity 78, and then the gas in the flow distribution cavity 78 is injected into the combustion chamber 12 through each gas guide hole 77 in a pulsating cycle; after the gas in the combustion chamber 12 is ignited by the ignition device, continuous pulsating flame is formed in the combustion chamber 12, and then high-temperature tail gas generated by combustion in the combustion chamber 12 is continuously ejected in the form of tail flame through the smoke discharging end of the combustion chamber 12, and then the tail flame ejected by each exhaust straight pipe 20 heats the heat utilization equipment; thereby realizing the utilization of the gas;
when the gas source is CH 4 When the concentration is less than 4%, continuously supplying the gas into the gas distribution box 79 in a pulse period mode through the gas pulse supply pipe 82 under the action of the gas pump; further, the inside of the diversion cavity 78 is continuously pulsed with air pressure, and the gas in the diversion cavity 78 is pulsed into the combustion chamber 12 through each gas guide hole 77Injecting gas; CH in the gas ejected through the gas holes 77 4 The concentration is less than 4%, and the combustion chamber 12 cannot be smoothly ignited or the continuity of combustion in a plurality of pulse cycles cannot be maintained, and CH needs to be performed on the combustion chamber 12 4 Concentrating; at this time, the pure methane pressurizing supply pipe 8 presses pure methane into the pure methane pressure accumulation cavity 2, the pure methane pressurizing supply pipe 8 continuously maintains the air pressure in the pure methane pressure accumulation cavity 2, the air pressure in the pure methane pressure accumulation cavity 2 is always ensured to be larger than the air pressure in the combustion chamber 12, the motor 5 is started at this time, the motor 5 drives the rotary valve body 6 to rotate along the axis through the output gear 3, the annular flange 21 synchronously rotates along with the rotary valve body 6, the periodic rotation of the annular flange 21 enables the inner ends of the second air guide channels 17 to periodically rotate to be aligned to the outer ends of the first air guide channels 14, the pure methane pressure accumulation cavity 2 is periodically communicated with the methane enrichment cavity layer 7, and then methane in the pure methane pressure accumulation cavity 2 periodically enters the pure CH into the methane enrichment cavity layer 7 through the first air guide channels 14 4 Thereby forming pure CH in the methane enrichment cavity layer 7 4 Pulsating gas pressure and thus methane enrichment of CH in the cavity layer 7 4 The pulsating gas is periodically forced into the combustion chamber 12 through a plurality of methane enrichment holes 11 4 The rotation speed of the output gear 3 of the motor 5 is controlled, and the rotary gas distribution ring body 6 is further controlled, so that the periodic mutual communication period and pace between the pure methane pressure accumulation cavity 2 and the methane enrichment cavity layer 7 are consistent with the period and pace of injecting gas into the combustion chamber 12 through the gas guide hole 77; so as to realize the gas enrichment of each pulse combustion period in the combustion chamber 12 and ensure the continuous pulse combustion of the combustion chamber 12; the high-temperature tail gas generated by combustion in the combustion chamber 12 is continuously ejected in the form of tail flame through the smoke exhaust end of the combustion chamber 12, and the tail flame ejected by each exhaust straight pipe 20 heats the heat utilization equipment; thereby realizing the utilization of the gas; at the same time, pure methane gas in the methane enrichment cavity layer 7 can absorb heat generated after combustion in the combustion chamber 12 through the second annular wall 9, so that a plurality of methane enrichment holes 11 are injected into the combustion chamber 12 to be preheatedIs of pure CH 4 Thereby effectively improving the combustion efficiency in the combustion chamber 12.
The foregoing is only a preferred embodiment of the invention, it being noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the invention.