Direct-current jet flow low-concentration gas flameless oxidation device and method

Abstract

The present application relates to a kind of direct current jet low concentration gas flameless oxidation device and method, including for realizing low concentration gas oxidation oxidation chamber, and ignition system is arranged in the oxidation chamber, one end of the oxidation chamber is provided with stable flame disc, the other end of the oxidation chamber is opened with high-temperature flue gas outlet, the oxidation chamber is opened with direct current jet nozzle along the circumference of the stable flame disc, the stable flame disc is provided with through hole, the direct current jet nozzle is communicated with main air inlet, the through hole is communicated with auxiliary air inlet, the total area of the through hole is greater than the cross-sectional area of the high-temperature flue gas outlet, by high-temperature flue gas outlet position forms cross section mutation, direct current nozzle can also realize the rapid oxidation of gas in oxidation chamber, form turbulent flow, realize the backflow of high-temperature flue gas, reach the purpose of gas flameless oxidation.

Description

Technical Field

[0001] This invention belongs to the field of efficient coal mine gas control and utilization technology, and specifically relates to a DC jet low-concentration gas flameless oxidation device and method. Background Technology

[0002] To effectively address mine safety issues, gas drainage is typically employed to reduce methane concentrations below 1%, ensuring a safe level. However, in my country's coal mine gas drainage processes, the limited variety of drainage methods, the incorporation of excessive air, and fluctuating drainage volumes result in a majority of the drained gas being low-concentration (below 30%). Specifically, over 70% of the drained gas has a concentration below 8%. This portion of methane, falling within the explosive concentration range, is difficult to stably and efficiently utilize using conventional combustion methods and is thus released into the atmosphere.

[0003] Gas's main component is methane, and its greenhouse effect is equivalent to that of CO2. 2 It is 24.6 times stronger than CO2, and its destructive power on the atmospheric ozone layer is equivalent to that of CO2. 2 Seven times that of natural gas. Every year, a large amount of low-concentration methane gas is released unusable, not only causing a serious waste of limited non-renewable resources but also exacerbating air pollution and the greenhouse effect. Methane gas, as a high-quality energy source, has a calorific value of approximately 35,000 kJ / Nm³. 3 Coalbed methane (CBM), comparable to conventional natural gas, can be used as fuel and chemical feedstock. However, the introduction of oxygen, a flammable additive, increases the explosion hazard of CBM, posing significant challenges to its processing and transportation. Currently, the types, proportions, utilization rates, and main utilization methods of extracted CBM are as follows: Medium-to-high concentration CBM (CCH4 > 30%) accounts for approximately 6%, with a utilization rate exceeding 90%. Low-concentration CBM accounts for approximately 94%, but its utilization rate is below 35%. Due to the extremely low concentration of CBM, its utilization is difficult, and its main utilization methods are regenerative thermal oxidation and co-combustion of high-concentration CBM for power generation. These methods also have relatively low utilization efficiency, resulting in most of the low-concentration CBM being directly released into the atmosphere, causing enormous resource waste and significant environmental damage.

[0004] Low-concentration methane gas, ranging from 4% to 10%, is extremely rare and near its explosive limit, making stable combustion and efficient utilization through conventional methods difficult. Therefore, it is typically released directly into the atmosphere, resulting in significant energy waste and severe environmental pollution. Current coal mine safety regulations prohibit direct combustion of methane gas with a concentration below 30%, and while supplementary explanations exist, this still limits the research, development, promotion, and application of low-concentration methane utilization technologies. Although some oxidation devices exist for low-concentration methane, their thermal efficiency is relatively low.

[0005] Therefore, designing a flameless oxidation device and method for low-concentration methane using swirling jets, achieving rapid oxidation of methane through high-temperature flue gas recirculation and methane oxidation via strong turbulence in the oxidation device, and disrupting the methane deflagration energy wave within the explosion limit to stabilize oxidation, thereby realizing flameless oxidation of low-concentration methane and improving thermal utilization, is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a DC jet low-concentration gas flameless oxidation device and method. By abruptly changing the cross-section of the high-temperature flue gas outlet in the oxidation device, strong turbulence is achieved in the gas within the oxidation chamber, thereby enabling the high-temperature flue gas to reflux and rapidly oxidize the gas. This also serves to disrupt the gas deflagration energy wave within the explosion limit and stabilize the oxidation process, thus achieving flameless oxidation of low-concentration gas.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A direct-current jet low-concentration methane flameless oxidation device includes an oxidation chamber for achieving low-concentration methane oxidation and an ignition system disposed within the oxidation chamber. A flame stabilizing plate is disposed at one end of the oxidation chamber, and a high-temperature flue gas outlet is opened at the other end of the oxidation chamber. A direct-current jet nozzle is opened on the oxidation chamber along the circumference of the flame stabilizing plate. A through hole is disposed on the flame stabilizing plate. The direct-current jet nozzle is connected to a main air inlet, and the through hole is connected to an auxiliary air inlet. The total area of ​​the through hole is larger than the cross-sectional area of ​​the high-temperature flue gas outlet.

[0009] Preferably, both the auxiliary air inlet and the main air inlet are equipped with flow controllers to control the gas flow rate.

[0010] Preferably, the system further includes an initial oxidation temperature monitoring system located inside the oxidation chamber near one end of the flame stabilizing plate, an oxidation body temperature monitoring system located near the middle of the oxidation chamber, and a flame monitoring system located inside the oxidation chamber.

[0011] Preferably, the outer periphery of the oxidation chamber is provided with a heat storage body and a heat insulation layer from the inside to the outside.

[0012] Preferably, there are two or more through holes, which are evenly distributed around the flame stabilizer plate. The distance between the two or more through holes and the center of the flame stabilizer plate is equal, and the angle between the extension line of the through hole along the gas inlet direction and the extension line of the flame stabilizer plate axis towards the oxidation chamber is an acute angle.

[0013] Preferably, the total area of ​​the through holes is 1 to 1.8 times the cross-sectional area of ​​the high-temperature flue gas outlet.

[0014] Preferably, there are two or more DC jet nozzles, and the DC jet nozzles are evenly distributed in the circumferential direction at the end of the oxidation chamber, with the distance between the DC jet nozzles and the center of the flame stabilizer being equal.

[0015] This invention also discloses a DC jet low-concentration gas flameless oxidation method, which uses the DC jet low-concentration gas flameless oxidation device as described above, and includes the following steps:

[0016] The gas enters the oxidation chamber through the auxiliary air inlet and the flame stabilizer in sequence, and is ignited by the ignition system.

[0017] When the temperature of the oxidation chamber rises, gas is introduced through the main air inlet and injected into the oxidation chamber through the DC jet nozzle, so that the gas is rapidly oxidized at high temperature.

[0018] Preferably, the ratio of the amount of gas entering the oxidation chamber from the DC jet nozzle to the amount of gas entering the oxidation chamber from the flame stabilizer is 1 to 6.

[0019] Preferably, air is introduced through the main air inlet after the temperature of the oxidation chamber exceeds 800°C.

[0020] The present invention achieves the following technical effects compared to the prior art:

[0021] By increasing the total area of ​​the through-holes to be larger than the cross-sectional area of ​​the high-temperature flue gas outlet and by setting a direct-flow jet nozzle, the area of ​​the air inlet can be increased, which helps to stabilize the airflow and reduce airflow fluctuations. Moreover, reducing the cross-sectional area of ​​the high-temperature flue gas outlet can create a sudden change in cross-section at the high-temperature flue gas outlet position in the oxidation chamber, enhancing the recirculation of high-temperature flue gas. Setting the jet nozzle can also achieve rapid oxidation of gas in the oxidation chamber, forming turbulence, further realizing the recirculation of high-temperature flue gas, and achieving the purpose of flameless gas oxidation. In addition, by setting the direct-flow jet nozzle on the circumference of the flame stabilizer, after ignition through the flame stabilizer and the temperature reaching the set value, gas is injected through the direct-flow jet nozzle. That is, the gas introduced from the direct-flow jet nozzle is ejected from the circumference of the flame stabilizer, which can increase the contact area between the gas ejected from the direct-flow jet nozzle and the burning gas ejected from the flame stabilizer, so that the gas can be oxidized instantly, thereby improving the gas oxidation effect. Furthermore, the thermal efficiency of the flameless oxidation device of the present invention can be increased by more than 10%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] AppendixFigure 1 This is a schematic diagram of the overall structure of the DC jet low-concentration gas flameless oxidation device and method disclosed in the embodiments of the present invention;

[0024] The components include: 1. Main air inlet; 2. DC jet nozzle; 3. Flame stabilizer; 4. Heat storage body; 5. Ignition system; 6. Initial oxidation temperature monitoring system; 7. Oxidation chamber; 8. Oxidation body temperature monitoring system; 9. High-temperature flue gas outlet; 10. Thermal insulation layer; and 11. Auxiliary air inlet. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The purpose of this invention is to provide a direct current jet low-concentration gas flameless oxidation device and method. By abruptly changing the cross-section of the high-temperature flue gas outlet 9 in the oxidation device, strong turbulence is achieved in the gas in the oxidation chamber 7, thereby realizing the rapid oxidation of the gas and the return of the high-temperature flue gas. It also serves to destroy the gas deflagration energy wave within the explosion limit and stabilize the oxidation, thus achieving flameless oxidation of low-concentration gas.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] refer to Figure 1The DC jet low-concentration gas flameless oxidation device disclosed in this embodiment of the invention includes at least an oxidation chamber 7 for achieving low-concentration gas oxidation. An ignition system 5 is installed inside the oxidation chamber 7. A flame stabilizing plate 3 is installed at one end of the oxidation chamber 7, and a high-temperature flue gas outlet 9 is opened at the other end. A DC jet nozzle 2 is opened circumferentially along the flame stabilizing plate 3 on the oxidation chamber 7. A through hole is provided on the flame stabilizing plate 3. The DC jet nozzle 2 communicates with the main air inlet 1, and the through hole communicates with the auxiliary air inlet 11. The total area of ​​the through hole is larger than the cross-sectional area of ​​the high-temperature flue gas outlet 9. By increasing the total area of ​​the through hole to the cross-sectional area of ​​the high-temperature flue gas outlet 9 and providing the DC jet nozzle 2, the area of ​​the air inlet can be increased, thereby helping to stabilize the airflow, reduce airflow fluctuations, and reduce high-temperature gas oxidation. The cross-sectional area of ​​the high-temperature flue gas outlet 9 can create a sudden change in cross-section at the high-temperature flue gas outlet 9 position in the oxidation chamber 7, enhancing the recirculation of high-temperature flue gas. The DC jet nozzle 2 can also achieve rapid oxidation of gas in the oxidation chamber 7, forming turbulence, further realizing the recirculation of high-temperature flue gas, and achieving the purpose of flameless gas oxidation. In addition, the DC jet nozzle 2 is set in the circumferential direction of the flame stabilizer 3. After ignition through the flame stabilizer 3 and the temperature reaches the set value, gas is injected through the DC jet nozzle 2. That is, the gas introduced from the DC jet nozzle 2 is sprayed out from the circumferential direction of the flame stabilizer 3, which can increase the contact area between the gas sprayed from the DC jet nozzle 2 and the burning gas sprayed from the flame stabilizer 3, so that the gas can be oxidized instantly, thereby improving the gas oxidation effect.

[0029] It should be noted that the axis of the flame stabilizer 3 coincides with the axis of the high-temperature flue gas outlet 9. The flame stabilizer 3 can be set as one or multiple. The oxidation chamber 7, the high-temperature flue gas outlet 9, the main air inlet 1, the auxiliary air inlet 11, etc. can be square or circular.

[0030] refer to Figure 1 As one implementation method, both the auxiliary air inlet 11 and the main air inlet 1 are equipped with flow controllers to control the gas flow rate. By installing flow controllers in the main air inlet 1 and the auxiliary air inlet 11, the intake volume and pressure of the main air inlet 1 and the auxiliary air inlet 11 can be changed to the ratio of the dynamic pressure of the variable jet.

[0031] refer to Figure 1As one implementation, it also includes an initial oxidation temperature monitoring system 6 installed inside the oxidation chamber 7 near one end of the flame stabilizing plate 3, an oxidation main body temperature monitoring system 8 installed near the middle of the oxidation chamber 7, and a flame monitoring system installed inside the oxidation chamber 7. By setting the initial oxidation temperature monitoring system 6 and the oxidation main body temperature monitoring system 8, the temperature at different locations inside the oxidation chamber 7 can be monitored, thereby providing signals for the opening and closing of the flow meter, the opening and closing of the main air inlet 1 and the auxiliary air inlet 11. The flame monitoring system can monitor both the flame inside the oxidation chamber 7 and the temperature inside the oxidation chamber 7. By monitoring the flame status inside the oxidation system in real time, once an abnormal flame or flame extinguishing is detected, corresponding measures can be taken immediately, such as alarm, stopping the gas supply, or activating the fire extinguishing device.

[0032] It should be noted that the flame monitoring system can monitor flame signals, temperature signals, or both simultaneously. The flame monitoring system can employ one or more of the following: ion probe, infrared, and ultraviolet.

[0033] refer to Figure 1 In one embodiment, a heat storage body 4 and a heat insulation layer 10 are arranged sequentially from the inside to the outside of the oxidation chamber 7. The heat storage body 4 is used to store heat in the oxidation chamber 7, and the heat insulation layer 10 can prevent heat loss. By placing the heat storage body 4 between the oxidation chamber 7 and the heat insulation layer 10, the heat storage effect can be greatly improved. No additional heat storage material is required, which can greatly improve the compactness of the device.

[0034] refer to Figure 1 In one implementation, multiple through holes are provided and evenly distributed around the flame stabilizer 3. The distance between each through hole and the center of the flame stabilizer 3 is the same. The angle between the extension line of the through hole along the gas inlet direction and the extension line of the axis of the flame stabilizer 3 towards the oxidation chamber 7 is an acute angle. Setting the angle between the through hole and the axial direction of the flame stabilizer 3 to an acute angle can ensure that the gas entering from the through hole can cross and collide, thereby slowing down the gas and ensuring that the gas is fully ignited in the oxidation chamber 7.

[0035] It should be noted that the center of the flame stabilizer 3 is provided with an outlet end that is coaxially arranged with the high-temperature flue gas outlet 9. The inner diameter of the outlet end is larger than the inner diameter of the through hole. The through hole is arranged in the circumferential direction of the outlet end, and the outlet end is in a closed state.

[0036] refer to Figure 1 In one implementation method, the total area of ​​the through holes is 1 to 1.8 times the cross-sectional area of ​​the high-temperature flue gas outlet 9.

[0037] refer to Figure 1In one embodiment, two or more DC jet nozzles 2 are provided, and the DC jet nozzles 2 are evenly distributed in the circumferential direction at the end of the oxidation chamber 7. The distance between the DC jet nozzles 2 and the center of the flame stabilizer 3 is equal. By providing multiple DC jet nozzles 2, oxidation stability and sufficient jet oxidation intensity can be ensured.

[0038] It should be noted that the jet angle and gas flow rate of the DC jet nozzle 2 are adjustable, thereby changing the jet intensity to adjust the entrainment and recirculation of high-temperature flue gas in the oxidation chamber 7. A flow guide device that can change the gas injection direction can be installed in the DC jet nozzle 2, thereby realizing the adjustment of the jet angle of the DC jet nozzle 2.

[0039] refer to Figure 1 The present invention also discloses a DC jet low-concentration gas flameless oxidation method, which uses the DC jet low-concentration gas flameless oxidation device described above, and its main steps are as follows:

[0040] Gas enters the oxidation chamber 7 after passing through the auxiliary air inlet 11 and the flame stabilizer 3, and is ignited by the ignition system 5.

[0041] After the initial oxidation temperature monitoring system 6 detects that the temperature of the oxidation chamber 7 is higher than the preset value, it introduces air through the main air inlet 1 and injects gas into the oxidation chamber 7 through the DC jet nozzle 2. The gas is rapidly oxidized at high temperature.

[0042] The heat storage body 4 and the heat insulation layer 10 are used to store heat and reduce heat loss. The high-temperature flue gas is discharged through the high-temperature flue gas outlet 9 to provide a heat source for heat users.

[0043] To ensure safety, the initial oxidation temperature monitoring system 6 and the oxidation main body temperature monitoring system 8 are interlocked with the gas intake regulating device;

[0044] By injecting a strong DC jet through the DC jet nozzle 2 and abruptly changing the flow cross section (high-temperature flue gas outlet 9), high-temperature flue gas entrainment is achieved, allowing the gas to oxidize in a very short time. The oxidation chamber 7 experiences intense turbulence with no obvious flame surface.

[0045] refer to Figure 1 In one embodiment, the ratio of the amount of gas entering the oxidation chamber 7 from the DC jet nozzle to the amount of gas entering the oxidation chamber 7 from the flame stabilizer 3 is 1 to 6, which can ensure stable oxidation and sufficient jet oxidation intensity.

[0046] refer to Figure 1 As one implementation method, after the temperature of the oxidation chamber 7 exceeds 800°C, air is introduced through the main air inlet 1, which can ensure the instantaneous oxidation of gas, thereby reducing the risk of gas explosion and improving production safety.

[0047] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0048] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A DC jet low-concentration gas flameless oxidation device, characterized in that, It includes an oxidation chamber for achieving low-concentration gas oxidation, and an ignition system disposed in the oxidation chamber. One end of the oxidation chamber is provided with a flame stabilizing plate, and the other end of the oxidation chamber is provided with a high-temperature flue gas outlet. A direct current jet nozzle is provided on the oxidation chamber along the circumference of the flame stabilizing plate. The flame stabilizing plate is provided with a through hole. The direct current jet nozzle is connected to the main air inlet, and the through hole is connected to the auxiliary air inlet. The total area of ​​the through hole is larger than the cross-sectional area of ​​the high-temperature flue gas outlet. It also includes an initial oxidation temperature monitoring system located inside the oxidation chamber near one end of the flame stabilizing plate, an oxidation body temperature monitoring system located near the middle of the oxidation chamber, and a flame monitoring system located inside the oxidation chamber. The angle between the extension line of the through hole along the gas inlet direction and the extension line of the flame stabilizer disk axis towards the oxidation chamber is an acute angle. The ratio of the amount of gas entering the oxidation chamber from the DC jet nozzle to the amount of gas entering the oxidation chamber from the flame stabilizing plate is 1 to 6.

2. The DC jet low-concentration gas flameless oxidation device according to claim 1, characterized in that, Both the auxiliary air inlet and the main air inlet are equipped with flow controllers to control the gas flow rate.

3. The DC jet low-concentration gas flameless oxidation device according to claim 1, characterized in that, The oxidation chamber is provided with a heat storage body and a heat insulation layer from the inside to the outside.

4. The DC jet low-concentration gas flameless oxidation device according to claim 1, characterized in that, The through holes are configured to be two or more, and the through holes are evenly distributed in the circumferential direction of the flame stabilizing disk, and the distance between the two or more through holes and the center of the flame stabilizing disk is equal.

5. The DC jet low-concentration gas flameless oxidation device according to claim 1, characterized in that, The total area of ​​the through holes is 1 to 1.8 times the cross-sectional area of ​​the high-temperature flue gas outlet.

6. The DC jet low-concentration gas flameless oxidation device according to claim 1, characterized in that, The DC jet nozzles are configured as two or more, and the DC jet nozzles are evenly distributed in the circumferential direction at the end of the oxidation chamber, with the distance between the DC jet nozzles and the center of the flame stabilizer being equal.

7. A direct-flow low-concentration gas flameless oxidation method, using the direct-flow low-concentration gas flameless oxidation device as described in any one of claims 1-6, characterized in that, Includes the following steps: The gas enters the oxidation chamber through the auxiliary air inlet and the flame stabilizer in sequence, and is ignited by the ignition system. When the temperature of the oxidation chamber rises, gas is introduced through the main air inlet and injected into the oxidation chamber through the DC jet nozzle, so that the gas is rapidly oxidized at high temperature.

8. The DC jet low-concentration gas flameless oxidation method according to claim 7, characterized in that, Once the temperature in the oxidation chamber exceeds 800°C, air is introduced through the main air inlet.

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