Coal mine gas heat storage stable combustion device and combustion control method

Abstract

The invention belongs to the technical field of gas combustion, and discloses a coal mine gas heat storage stable combustion device and a combustion control method.The combustion device comprises a shell, a gas heat storage channel, a flue gas channel and a combustion chamber, the gas heat storage channel is located in the middle of the shell, gas is introduced upwards from the bottom, and the flue gas channel is located between the shell and the gas heat storage channel; and the combustion chamber is positioned at the upper part in the shell. Annular partition plates I are evenly distributed on the outer wall of the gas heat storage channel, and annular partition plates II are evenly distributed on the inner wall of the shell. Porous media are arranged in the combustion chamber, the smoke channel and the gas heat storage channel and used for heat storage. The low-concentration gas is fully preheated in a flue gas and low-concentration gas countercurrent mode, and stable combustion of the low-concentration gas in the combustion chamber can be effectively guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of gas combustion, and particularly to a coal mine gas regenerative stable combustion device and a combustion control method. Background Art

[0002] Coal mine gas drainage is an important safety guarantee for coal mining. Due to the low and fluctuating methane concentration in gas, most of the gas is difficult to be utilized and is mostly discharged into the air, causing the greenhouse effect. Combustion treatment is the most convenient and effective way to reduce methane emissions. Currently, gas with a methane concentration higher than 8% can be used for internal combustion engine power generation, while there is no mature and reliable high-efficiency utilization method for gas with a concentration lower than 8%. The low and fluctuating methane concentration is the main reason for the difficulty in burning and utilizing gas at present. The regenerative combustion method provides a good way for the combustion of low-concentration methane, that is, the heat in the flue gas is recovered through materials such as porous media and regenerative ceramics to preheat the fresh coal mine gas, so that the gas can reach a higher temperature before entering the combustion chamber, thereby making the reaction temperature higher than the adiabatic combustion temperature and realizing the combustion of low-concentration methane. In the prior art, the Chinese patent with the publication number CN113324247A discloses a high-temperature heat source of a small non-premixed burner with efficient preheating, which can not only preheat the oxidant but also effectively output the heat source. At the same time, the countercurrent of the oxidant and the fuel increases the disturbance, enabling rapid and uniform mixing, which is beneficial to the rapid progress of combustion and meets the requirements of the power heat source. The disadvantages of this technology are as follows: firstly, it only preheats the oxidant, and the temperature of the fuel before combustion is still low, so it cannot be used to burn low-calorific value gases; secondly, the preheating is carried out through the preheating channel, and the preheating effect is poor, and the oxidant cannot be heated to a high temperature; thirdly, the temperature of the flue gas after preheating decreases, and the heat utilization effect is not good. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: how to ensure the stable combustion of low-concentration gas.

[0004] The inventive concept of the present invention is: taking a porous medium with good heat storage effect as a medium, fully preheating the low-concentration gas with high-temperature flue gas in countercurrent, so that the gas can reach a higher temperature before entering the combustion chamber, and the combustion temperature can be higher than the adiabatic combustion temperature; by monitoring the temperature in the combustion chamber in real time, when the temperature is lower than the expected temperature, high-concentration gas is introduced to prevent the combustion from extinguishing.

[0005] Technical solution adopted by the present invention: In the first aspect, the present invention provides a coal mine gas heat storage and stable combustion device, which includes: a housing, a gas heat storage channel located in the middle of the housing, and a flue gas channel located between the housing and the gas heat storage channel. The bottom of the gas heat storage channel is a gas inlet, and a combustion chamber is located in the upper part of the housing; the flue gas outlet is located between the gas inlet and the housing; porous media are filled inside the gas heat storage channel, the flue gas channel and the combustion chamber; a baffle plate is arranged in the combustion chamber for guiding high-temperature flue gas.

[0006] As a further improvement of the present invention, a plurality of annular partition plates I are evenly distributed on the outer wall of the gas heat storage channel, and a plurality of annular partition plates II are evenly distributed on the inner wall of the housing, and the partition plates I and the partition plates II are arranged staggered.

[0007] As a further improvement of the present invention, the baffle plate is in a funnel shape, and the bottom of the baffle plate is fixedly connected to the upper opening of the gas heat storage channel; a plurality of diversion holes are evenly distributed on the baffle plate.

[0008] As a further improvement of the present invention, the porosity of the porous medium in the combustion chamber is greater than the porosity of the porous medium in the gas heat storage channel and the flue gas channel.

[0009] As a further improvement of the present invention, the porous medium is alumina balls.

[0010] As a further improvement of the present invention, a high-temperature flue gas extraction port is opened above the housing, and the baffle plate is located below the high-temperature flue gas extraction port.

[0011] As a further improvement of the present invention, it further includes a control device, which includes a computer, an electronic control valve, an electronic valve and a three-way valve. The electronic control valve is configured to open and close the high-temperature flue gas extraction port through the computer; the electronic valve is configured to control the opening and closing of the input of high-concentration gas through the computer; the three-way valve is connected to the electronic valve through a gas pipeline, and the three-way valve is configured to open and close the input of low-concentration gas and high-concentration gas through the computer; the temperature data collected by the thermocouple temperature sensor is input into the computer.

[0012] In the second aspect, the present invention also proposes a heat storage and stable combustion control method for coal mine gas, using the above-mentioned coal mine gas heat storage and stable combustion device, which includes the following steps:

[0013] Step S1: Use an electric heating wire to heat the porous medium in the gas heat storage channel to above 1000 °C, and then introduce low-concentration gas from the bottom through the three-way valve (1) into the gas heat storage channel for combustion;

[0014] Step S2: When the temperature in the combustion chamber is higher than 1000 °C, part of the high-temperature flue gas is extracted from the high-temperature flue gas extraction port at the upper part of the housing by opening the electronic control valve to cool down the combustion chamber, and the heat of the extracted high-temperature flue gas is used for heating and power generation;

[0015] Step S3: When the temperature in the combustion chamber is lower than 1000 °C but higher than 800 °C, the combustion chamber is in a state of about to go out. At this time, the electronic control valve is closed, and the temperature in the combustion chamber can rise by the combustion of the low-concentration gas itself;

[0016] Step S4: When the temperature in the combustion chamber is lower than 800 °C, the electronic valve is opened, and high-concentration gas is introduced into the combustion chamber (8) for combustion to prevent the combustion from going out.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] (1) In the present invention, the device is arranged such that the flue gas flows downward and the low-concentration gas flows upward. The high-temperature flue gas continuously preheats the low-concentration gas sufficiently. Before the low-concentration gas enters the combustion chamber, it has reached a relatively high temperature, thereby reducing the lean combustion limit of the low-concentration gas, enabling it to enter the combustion state and achieving stable combustion;

[0019] (2) The present invention is provided with a control device. The temperature in the combustion chamber is monitored by a temperature sensor. When the indoor temperature is less than 800 degrees, high-concentration gas is introduced to assist the combustion of the low-concentration gas, thereby ensuring stable combustion;

[0020] (3) On the one hand, the baffle plate enables the gas to fully occupy the space in the combustion chamber, extending the residence time. On the other hand, it enhances the gas disturbance, enabling the gas to burn fully;

[0021] (4) An annular partition I is provided on the outer wall of the gas heat storage channel, and an annular partition II is provided on the inner wall of the housing, which can extend the residence time of the high-temperature flue gas in the flue gas channel and, together with the porous medium, continuously and sufficiently preheat the low-concentration gas. Description of the Drawings

[0022] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0023] Figure 1 is a schematic structural diagram of the combustion device of the present invention;

[0024] Figure 2 is a cross-sectional view of the housing;

[0025] Figure 3 is a structural diagram of the gas heat storage channel;

[0026] Figure 4 is a structural diagram of the baffle plate;

[0027] Figure 5 is a flow chart of the combustion control method of the present invention;

[0028] In the figure, 1 - three-way valve; 2 - gas inlet; 3 - flue gas outlet; 4 - flue gas passage; 5 - gas heat storage passage; 6 - annular partition I; 7 - annular partition II; 8 - combustion chamber; 9 - thermocouple temperature sensor; 10 - deflector; 10-1 - deflector hole; 11 - high-temperature flue gas extraction port; 12 - electronic control valve; 13 - thermal insulation layer; 14 - computer; 15 - electric heating wire; 16 - housing; 17 - electronic valve; a - low-concentration gas; b - high-concentration gas. Specific embodiments

[0029] Please refer to Figure 1 , the coal mine gas heat storage and stable combustion device disclosed by the present invention mainly consists of the following components: housing 16, gas heat storage passage 5 and deflector 10. The housing 16 and the gas heat storage passage 5 are cylindrical. The gas heat storage passage 5 is located in the middle of the housing 16, and their axes coincide. The flue gas passage 4 is between the gas heat storage passage 5 and the housing 16. The housing 16 is composed of two identical parts connected by bolts, which facilitates the installation of the internal equipment of the housing 16. The shell wall of the housing 16 is a hollow layer, and a thermal insulation layer 13 is provided therein. The upper space inside the housing 16 is the combustion chamber 8, and the upper part of the gas heat storage passage 5 is located in the combustion chamber 8. This combustion device can be used to process 100 Nm 3Coal mine gas of / h. The height of the housing 16 is 1 m and the diameter is 0.3 m. Among them, the height of the combustion chamber 8 is 0.2 m, and the heights of the gas heat storage channel 5 and the flue gas channel 4 are 0.8 m. The diameter of the gas heat storage channel is 0.2 m. A porous medium is provided in the combustion chamber 8 to facilitate the uniform distribution of the combustion gas and make the combustion more complete. A porous medium is also provided in the flue gas channel 4 for heat storage. Specifically, the porous medium is selected as alumina balls. Among them, alumina balls with a diameter of 10 mm are filled in the combustion chamber 8, and alumina balls with a mixture of diameters of 10 mm and 3 mm are filled in the gas heat storage channel 5 and the flue gas channel 4. The advantages of using alumina balls as the porous medium are that it has a large specific heat capacity and good heat storage capacity; it is easy to fill; and it has a small density, reducing the weight of the entire burner. The reason for filling alumina balls with a diameter of 10 mm in the combustion chamber 8 is that it has a large porosity and a small thermal inertia. When the load of the combustion device changes, the response time is small, and at the same time, its pressure loss is small, which is beneficial to reducing the pressure drop of the entire burner. The reason for filling the mixture of 10 mm and 3 mm diameter balls in the flue gas channel 4 and the gas heat storage channel 5 is that it has a small porosity and a large thermal inertia, and the response time is long when the load of the combustion device changes. At the same time, the convective heat transfer coefficient between the gas and solid phases is large, which helps with heat storage. At the bottom of the flue gas channel 4 and the gas heat storage channel 5 is the gas inlet 2 for leading to low-concentration gas. Between the gas inlet 2 and the housing 16 is the flue gas outlet 3 for discharging high-temperature flue gas. During operation, the flow direction of the low-concentration gas is from bottom to top, and the flow direction of the high-temperature flue gas is from top to bottom.

[0030] Please refer to Figure 2 and Figure 3 , a plurality of annular partitions I6 are evenly distributed in the length direction of the outer wall of the gas heat storage channel 5, and a plurality of annular partitions II7 are evenly distributed in the length direction of the inner wall of the housing 16. The plane where each annular partition I6 is located is perpendicular to the axis of the gas heat storage channel 5, and all the annular partitions I6 are of the same size. The plane where the annular partition II7 is located is perpendicular to the axis of the housing 16, and all the annular partitions II7 are of the same size. The annular partition I6 and the annular partition II7 are arranged alternately, and the diameter of the annular partition I6 is larger than that of the annular partition II7, so that one side of the annular partition I6 extends into the space between the upper and lower two annular partitions II7. Since the direction of the high-temperature flue gas is from top to bottom, by setting the annular partition I6 and the annular partition II7, the downward route of the high-temperature flue gas can be changed, making it move slower in the curved path. On the one hand, it is convenient for the porous medium to store heat, and on the other hand, it can fully preheat the low-concentration gas introduced into the gas heat storage channel 5. The cooperation of the porous medium and the annular partition I6 and the annular partition II7 can better solve the preheating problem of the low-concentration gas a.

[0031] Please refer to Figure 4, a deflector plate 10 is provided in the combustion chamber 8. The deflector plate 10 is funnel-shaped, with a large upper opening and a small lower opening. The lower opening is threadedly connected to the upper opening of the gas regenerative heat storage channel 5. A number of deflector holes 10-1 are evenly distributed on the deflector plate 10. The deflector holes 10-1 are used for high-temperature flue gas to pass through. The inclination angle of the deflector plate is designed according to the structure of the combustion chamber 8. The deflector plate 10 can deflect the low-concentration gas a entering the combustion chamber 8 so that it can fill the combustion chamber, prolonging the residence time. And after the low-concentration gas a runs upward and contacts the top of the housing and turns back, it will collide with the inner wall of the deflector plate 10 and then run upward again, thus forming a circulation, enhancing the gas disturbance and contributing to the full combustion of the low-concentration gas a.

[0032] Please refer to Figure 1 , a high-temperature flue gas extraction port 11 is provided in the upper part of the housing 16. The deflector plate 10 is directly below the high-temperature flue gas extraction port 11. The function of the high-temperature flue gas extraction port 11 is to release a part of the high-temperature flue gas when the temperature in the combustion chamber 8 is too high, such as higher than 1000 degrees, to cool down the combustion chamber 8. At the same time, these extracted high-temperature flue gases can be used for heating and power generation.

[0033] This device also includes a control part, which includes a three-way valve 1, a thermocouple temperature sensor 9, an electronic control valve 12, a computer 14, an electric heating wire 15, and an electronic valve 17. Among them, the electric heating wire 15 is located inside the gas regenerative heat storage channel 5 and is used to ignite the preheated low-concentration gas a. The thermocouple temperature sensor 9 is located inside the deflector plate 109 and is used to measure the temperature in the combustion chamber 8 in real time. One of the channels of the three-way valve 1 is used to introduce the low-depth gas a, and a part is used to introduce the high-concentration gas b. The electronic valve 17 is connected to the computer 14 and is used for the switch of the high-concentration gas b. The electronic control valve 12 is connected to the computer 14 and is used for the switch of the high-temperature flue gas extraction port 11.

[0034] Through the mutual positional relationship among the housing 16, the gas regenerative heat storage channel 5 and the flue gas channel 4, and the flow direction of the low-concentration gas a and the flow direction of the high-temperature flue gas, this device can solve the problem of preheating the low-concentration gas a and contribute to the combustion of the low-concentration gas a. The annular partition I6 and the annular partition II7 can effectively reduce the flow rate of the high-temperature flue gas, cooperate with the porous medium heat storage, and preheat the low-concentration gas a for a long time to improve the preheating effect.

[0035] For the preheating of the low-concentration gas in the present invention, no external heat needs to be provided. Only the high-temperature flue gas after combustion can be used for continuous preheating, recycling the heat after combustion.

[0036] Please refer to Figure 5 , the present invention also proposes a method for controlling the heat storage and stable combustion of coal mine gas. This method includes the following steps:

[0037] Step S1: Use the electric heating wire 15 to heat the porous medium in the gas heat storage channel 5 to above 1000°C, and then introduce the low-concentration gas a from the bottom into the gas heat storage channel 5 through the three-way valve 1 for combustion.

[0038] Step S2: When the temperature in the combustion chamber 8 is higher than 1000°C, extract part of the high-temperature flue gas from the high-temperature flue gas extraction port 11 at the upper part of the housing 16 by opening the electronic control valve 12 to cool down the combustion chamber.

[0039] Step S3: When the temperature in the combustion chamber 8 is lower than 1000°C but higher than 800°C, the combustion chamber 8 is in a state of about to go out. At this time, close the electronic control valve 12, and the temperature in the combustion chamber 8 can rise by the combustion of the low-concentration gas a itself.

[0040] Step S4: When the temperature in the combustion chamber 8 is lower than 800°C, open the electronic valve 17 to introduce the high-concentration gas b into the combustion chamber 8 for combustion to prevent the combustion from going out.

[0041] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. All changes that can be made within the knowledge of those skilled in the art without departing from the spirit of the present invention are within the protection scope of the claims of the present invention.

Claims

1. A coal mine gas heat storage and stable combustion device, characterized in that Comprising: A housing (16), a gas heat storage channel (5) located in the middle of the housing (16), and a flue gas channel (4) located between the housing (16) and the gas heat storage channel (5). The bottom of the gas heat storage channel (5) is a gas inlet (2), and a combustion chamber (8) is located in the upper part of the housing (16); the flue gas outlet (3) is located between the gas inlet (2) and the housing (16); porous media are filled inside the gas heat storage channel (5), the flue gas channel (4), and the combustion chamber (8); a baffle plate (10) is provided in the combustion chamber (8) for guiding high-temperature flue gas.

2. The coal mine gas heat storage and stable combustion device according to claim 1, characterized in that, A plurality of annular partition plates I (6) are evenly distributed on the outer wall of the gas heat storage channel (5), and a plurality of annular partition plates II (7) are evenly distributed on the inner wall of the housing (16). The partition plates I (6) and the partition plates II (7) are arranged staggeredly.

3. The coal mine gas heat storage and stable combustion device according to claim 1, characterized in that, The baffle plate (10) is in a funnel shape, and the bottom of the baffle plate (10) is fixedly connected to the upper opening of the gas heat storage channel (5); a plurality of diversion holes (10-1) are evenly distributed on the baffle plate (10).

4. The coal mine gas heat storage and stable combustion device according to claim 1, characterized in that, The porosity of the porous medium in the combustion chamber (8) is greater than the porosity of the porous media in the gas heat storage channel (5) and the flue gas channel (4).

5. The coal mine gas heat storage and stable combustion device according to claim 4, characterized in that, The porous medium is alumina balls.

6. The coal mine gas heat storage and stable combustion device according to claim 1, characterized in that, A high-temperature flue gas extraction port is opened above the housing (16), and the baffle plate (10) is located below the high-temperature flue gas extraction port (11).

7. The coal mine gas heat storage and stable combustion device according to claim 1, characterized in that, It further includes a control device, which includes a computer (14), an electronic control valve (12), an electronic valve (17), and a three-way valve (1). The electronic control valve (12) is configured to open and close the high-temperature flue gas extraction port (11) through the computer (14); the electronic valve (17) is configured to control the opening and closing of the input of high-concentration gas (b) through the computer (14); the three-way valve (1) is connected to the electronic valve (17) through a gas pipeline, and the three-way valve (1) is configured to open and close the input of low-concentration gas (a) and high-concentration gas (b) through the computer (14); the temperature data collected by the thermocouple temperature sensor (9) is input into the computer.

8. A method for controlling the heat storage and stable combustion of coal mine gas, which uses the coal mine gas heat storage and stable combustion device described in any one of claims 1-7, and is characterized in that, Including the following steps: Step S1: Use an electric heating wire (15) to heat the porous medium in the gas heat storage channel (5) to above 1000 °C, and then introduce low-concentration gas (a) into the gas heat storage channel (5) from the bottom through the three-way valve (1) for combustion. Step S2: When the temperature in the combustion chamber (8) is higher than 1000 °C, open the electronic control valve (12) to extract part of the high-temperature flue gas from the high-temperature flue gas extraction port (11) in the upper part of the housing (16) to cool the combustion chamber (8), and use the heat of the extracted high-temperature flue gas for heating and power generation. Step S3: When the temperature in the combustion chamber (8) is lower than 1000 °C but higher than 800 °C, the combustion chamber (8) is in a state of being about to go out. At this time, close the electronic control valve (12), and the temperature in the combustion chamber can rise by the combustion of the low-concentration gas (a) itself. Step S4: When the temperature in the combustion chamber (8) is lower than 800 °C, open the electronic valve (17) to introduce high-concentration gas (b) into the combustion chamber (8) for combustion to prevent the combustion from extinguishing.

Images