Combustion performance measurement system of natural gas mixed with hydrogen based on gas mixer structure optimization

Abstract

The present invention discloses a natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization, characterized in that it includes a hydrogen blending module, a mixer performance measurement module, a gas supply module, a combustion performance measurement module and an exhaust gas treatment module, wherein the hydrogen blending module is used to mix H2 and CNG gas, the mixer performance measurement module is used to measure the mixing effect of the mixer, the gas supply module is used to mix the mixed gas with the outside air, the combustion performance measurement module is used to measure the combustion performance of the burner, and the exhaust gas treatment module is used to treat toxic gases. The beneficial effect of the present invention is that the test system optimizes the structure of the static gas mixer to obtain a mixer with the minimum pressure drop and the best mixing effect, fully mixes the natural gas and hydrogen, so that the mixed gas burns fully, releases less toxic gas, and improves the calorific value, thereby improving the utilization efficiency of the fuel, reducing pollution to the environment, and achieving the effect of energy saving and emission reduction.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrogen-blended combustion performance test systems, and in particular to a natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization. Background Art

[0002] As the growth of wind and solar energy provides more and more surplus electricity for the electrolysis of water to produce renewable hydrogen, the conditions and technical capabilities have been met to use renewable hydrogen as a new way to increase the proportion of renewable energy in natural gas. The transportation of HCNG through existing natural gas pipelines for gas stove combustion not only solves the problem of hydrogen transportation more conveniently, but also greatly improves the market's ability to absorb hydrogen. Due to the special combustion characteristics of hydrogen, the primary air coefficient, heat load, combustion stability, carbon monoxide content in flue gas and other combustion conditions of the burner of the gas appliance will change, so it is necessary to test the combustion performance of natural gas mixed with hydrogen.

[0003] On the one hand, due to the fast combustion speed of hydrogen, when the flow rate of the mixed gas is less than the flame propagation speed, the flame may propagate countercurrently into the fire hole, causing combustion inside the burner or at the nozzle to produce backfire. Backfire may cause damage to the gas stove, leading to burnout of the burner, cracking of glass panels and ceramic panels, blackening of stainless steel panels, damage to internal wiring and control devices, and other accidents. At the same time, due to incomplete combustion, a large amount of toxic gas is released, which not only causes property loss but also endangers the user's safety.

[0004] On the other hand, the degree of mixing of H2 and CNG will affect the combustion performance of the gas, releasing less CO, NO x Toxic gases such as HCNG can be removed to increase the calorific value, thereby improving the utilization efficiency of the gas, reducing pollution to the environment, and achieving the effect of energy conservation and emission reduction. Therefore, in order to achieve better mixed gas (HCNG) combustion utilization performance, it is critical to develop an efficient and convenient mixer structure.

[0005] Domestic and foreign scholars have also conducted a lot of research on the structure of mixers, mainly involving the types of mixers and the improvement and optimization of mixer structures. Some scholars use surge tanks to mix gases to form a stable mixed gas HCNG, which can not only reduce the instability of system control caused by pipeline pressure fluctuations, but also have sufficient surge tank volume to meet the test requirements. Although the surge tank can have the advantages of stable pipeline gas supply and not easy to backfire and deflagration in the process of supplying gas to residents on a large scale. However, due to its large size, it occupies a certain space, and the HCNG gas formed by the mixture of CNG and H2 is stored inside the container, which is prone to danger and is not suitable for long-term and large-scale use by urban residents.

[0006] Furthermore, some scholars have done a lot of work on the improvement and optimization of mixers, and studied the influence of the number of internal units of static mixers on the polymer mixing effect; some scholars have also studied gas-gas fast jet mixers, and analyzed the influence of factors such as momentum ratio, opening diameter, number of wall openings and mixer aspect ratio on the mixing effect.

[0007] The present invention designs a natural gas hydrogen-blended combustion performance test system based on gas mixer structure optimization. By optimizing the structure of the gas static mixer, the combustion performance of the burner under different components of HCNG under different structural mixers is measured. And according to the built-in anti-flashback device of the burner, the resistance value measured by the thermal resistor is compared with the threshold value of the controller to judge whether the burner flashes back and determine the critical value of the hydrogen blending ratio. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a natural gas hydrogen-blended combustion performance measurement system solution based on gas mixer structure optimization, which makes the measurement of relevant technical indicators of household gas stove product design more reasonable, convenient and accurate.

[0009] The technical solution of the present invention is as follows:

[0010] The natural gas hydrogen blending combustion performance measurement system based on gas mixer structure optimization is characterized in that it includes a hydrogen blending module, a mixer performance measurement module, a gas supply module, a combustion performance measurement module and an exhaust gas treatment module, wherein the mixer performance measurement module and the combustion performance measurement module are respectively connected to the hydrogen blending module, the gas supply module is respectively connected to the mixer performance measurement module and the combustion performance measurement module, and the combustion performance measurement module is connected to the exhaust gas treatment module; the hydrogen blending module is used to mix H2 and CNG gas, the mixer performance measurement module is used to measure the mixing effect of the mixer, the gas supply module is used to mix the mixed gas with the outside air, the combustion performance measurement module is used to measure the combustion performance of the burner, and the exhaust gas treatment module is used to treat toxic gases.

[0011] The natural gas hydrogen blending combustion performance measurement system based on gas mixer structure optimization is characterized in that the hydrogen blending module includes a pressure reducing station, a long tube trailer, a computer controller, a gas distribution cabinet and a pressure reducing valve; the pressure reducing station and the long tube trailer provide methane and hydrogen respectively, and the computer controller controls the gas distribution cabinet to distribute gas by inputting the hydrogen blending ratio, and adjusts the pressure of the mixed gas after distribution through the pressure reducing valve.

[0012] The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is characterized in that the mixer performance measurement module includes a pressure gauge, a static gas mixer, a rotational viscometer, a gas chromatograph and a flow meter; the pressure gauges are respectively installed at both ends of the static gas mixer, and the mixer pressure difference is obtained by the difference in the values ​​of the two pressure gauges, and the mixer performance is judged by the pressure difference value; the rotational viscometer is arranged on the bypass of the static gas mixer outflow pipeline, and the mixed gas passing through the rotational viscometer is measured by the gas chromatograph to measure its component content and flows into the pipeline; the flow meter measures the gas flow in the pipeline;

[0013] The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is characterized in that the gas supply module includes a first anti-backgas device, a first flame arrester, a filter, a U-tube pressure gauge and an air pump; the first anti-backgas device is provided with pure water, and the mixed gas enters through the air inlet pipe of the first anti-backgas device, is filtered in the water, and is discharged through the air outlet pipe of the first anti-backgas device, and the mixed gas is prevented from flowing back; the mixed gas flows through the first anti-backgas device and then enters the first flame arrester, and the function of the first flame arrester is to prevent the danger of explosion in the pipeline when the burner burns and backfires; the outside air enters and first passes through the air filter, and then passes through the U-tube pressure gauge to measure the pressure difference between the air inlet pipeline and the outside world, which plays a role in balancing the pressure difference, and then the outside gas is sent in through the gas pump to mix with the hydrogen-blended natural gas that passes through the flame arrester.

[0014] The natural gas hydrogen blended combustion performance measurement system based on gas mixer structure optimization is characterized in that the combustion performance measurement module includes a second anti-backgas device, a second flame arrester and a burner; the mixed gas that has passed through the static gas mixer and the mixed gas that has not passed through the mixer are respectively introduced into the burner for combustion; the gas that has not been mixed by the mixer flows through the second anti-backgas device and the second flame arrester and is mixed with the outside air before entering the burner for combustion; since hydrogen burns quickly, an anti-flashback device is built into the burner, and whether flashback occurs is determined by comparing the thermal resistance value with the threshold set by the controller, thereby measuring the impact of natural gas hydrogen blending on the combustion performance of the downstream equipment burner.

[0015] The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is characterized in that the exhaust gas treatment module includes a fume hood, and the toxic gas generated after the combustion of the burner is introduced into the fume hood for treatment, thereby reducing pollution to the environment and achieving energy conservation and emission reduction.

[0016] The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is characterized in that four bypass pipes are provided on the outflow pipeline of the static gas mixer, four different sampling points are selected on the four bypass pipes, and the viscosities of the four sampling points are measured respectively to obtain the mixing unevenness of the static gas mixer, thereby judging the mixing effect of the mixer.

[0017] The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is characterized in that the anti-flashback device includes a controller and a thermal resistor. When the burner flashes back, the flame flows back to the inside of the fire hole, causing temperature changes and the resistance of the thermal resistor increases. When it increases to a threshold value, the controller will feed back to the computer controller, and the computer controller will stop the gas distribution process by controlling the gas distribution cabinet to ensure the safety of the burner.

[0018] The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is characterized in that the four different sampling points are adjacent to each other at 90°.

[0019] The beneficial effects of the present invention are:

[0020] 1) The test system optimizes the structure of the static gas mixer to obtain a mixer with the smallest pressure drop and the best mixing effect, which fully mixes the natural gas and hydrogen, so that the mixed gas burns fully, releases less toxic gas, and increases the calorific value, thereby improving the utilization efficiency of fuel, reducing pollution to the environment, and achieving the effect of energy conservation and emission reduction;

[0021] 2) In order to study the combustion performance of the gas appliances under different hydrogen blending ratios and prevent flashback caused by excessive hydrogen blending ratio, the gas stove of the experimental system is equipped with a built-in anti-flashback device to protect the gas appliances. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the principle diagram of the measurement system of the present invention;

[0023] Figure 2 It is a schematic diagram of the anti-flashback device of the present invention;

[0024] Figure 3 It is a sampling point for the mixing effect of the mixer of the present invention;

[0025] In the figure: 1-pressure reducing station, 2-long tube trailer, 3-computer controller, 4-gas distribution cabinet, 5-pressure reducing valve, 6-pressure gauge, 7-gas mixer, 801-valve one, 802-valve two, 803-valve three, 804-valve four, 805-valve five, 806-valve six, 807-valve seven, 808-valve eight, 9-rotational viscometer, 10-chromatograph, 11-flow meter, 12-first anti-backgas device, 13-first flame arrester, 14-second anti-backgas device, 15-second flame arrester, 16-filter, 17-U-tube pressure gauge, 18-air pump, 19-burner, 191-controller, 192-thermistor, 20-fume hood. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, a natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization is composed of a hydrogen blending module, a mixer performance measurement module, a gas supply module, a combustion performance measurement module, and an exhaust gas treatment module, including a pressure reducing station 1, a long tube trailer 2, a computer controller 3, a gas distribution cabinet 4, a pressure reducing valve 5, a pressure gauge 6, a gas mixer 7, a valve 1 801, a valve 2 802, a valve 3 803, a valve 4 804, a valve 5 805, a valve 6 806, a valve 7 807, a valve 8 808, a rotational viscometer 9, a chromatograph 10, a flow meter 11, a first anti-backgas device 12, a first flame arrester 13, a second anti-backgas device 14, a second flame arrester 15, a filter 16, a U-tube pressure gauge 17, an air pump 18, a fuel appliance 19, and a fume hood 20.

[0028] The hydrogen blending module includes a pressure reducing station 1, a long tube trailer 2, a computer controller 3, a gas distribution cabinet 4, and a pressure reducing valve 5; the pressure reducing station 1 and the long tube trailer 2 provide methane (CH4) and hydrogen (H2) respectively; the computer controller 3 controls the gas distribution cabinet 4 to distribute gas by inputting the hydrogen blending ratio, and adjusts the pressure of the mixed gas after distribution through the pressure reducing valve 5.

[0029] The mixer performance measurement module mainly includes a pressure gauge 6, a static gas mixer 7, a rotational viscometer 9, a gas chromatograph 10, and a flow meter 11; the pressure gauges 6 are respectively installed at both ends of the static gas mixer 7, and the mixer pressure difference is obtained by the difference in the values ​​of the two pressure gauges 6, and the mixer performance is further judged by the pressure difference value; the rotational viscometer 9 is set on the bypass of the mixer outflow pipeline, four different sampling points are selected on the pipeline, and the viscosity of the four sampling points is measured respectively to calculate the mixing unevenness of the mixer, thereby judging the mixing effect of the mixer; the mixed gas passing through the rotational viscometer 9 is measured through the gas chromatograph 10 to measure its component content and flows into the pipeline; the flow meter 11 measures the gas flow in the pipeline.

[0030] The gas supply module includes a first anti-backflow device 12, a first flame arrester 13, a filter 16, a U-tube pressure gauge 17, and an air pump 18; the mixed gas enters the first anti-backflow device 12 through a flow meter 11. There is a certain amount of pure water in the first anti-backflow device 12. The mixed gas enters through the air inlet pipe of the first anti-backflow device 12, and after being filtered in the water, it is discharged through the air outlet pipe of the first anti-backflow device 12, and the mixed gas is prevented from flowing back; the mixed gas flows through the first anti-backflow device 12 and then enters the first flame arrester 13. The function of the first flame arrester 13 is to prevent the danger of explosion in the pipeline when the burner 19 burns and backfires; further, the outside air enters and first passes through the air filter 16, and then passes through the U-tube pressure gauge 17 to measure the pressure difference between the air inlet pipeline and the outside world, which plays a role in balancing the pressure difference, and then the outside gas is sent in through the gas pump 18 to mix with the hydrogen-blended natural gas passing through the flame arrester 13.

[0031] The combustion performance measurement module includes a second anti-backgas device 14, a second flame arrester 15, and a burner 19; the mixed gas that has passed through the static gas mixer 7 and the mixed gas that has not passed through the mixer are respectively introduced into the burner for combustion; further, the gas that has not been mixed by the mixer flows through the second anti-backgas device 14 and the second flame arrester 15 and is mixed with the outside air before entering the burner for combustion; since hydrogen burns quickly, an anti-flashback device is built into the burner, and whether flashback occurs is determined by comparing the thermal resistance value with the threshold set by the controller, thereby measuring the impact of natural gas hydrogen blending on the combustion performance of downstream equipment burners.

[0032] The waste gas treatment module includes a fume hood 20, into which toxic gases such as CO and NOx generated after combustion of the fuel appliance are introduced for treatment, thereby reducing pollution to the environment and achieving energy conservation and emission reduction.

[0033] like Figure 2 The figure shows a schematic diagram of a flashback prevention device of a "natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization". The burner has a built-in flashback prevention device, which is composed of a controller 191 and a thermal resistor 192. Thermal resistor temperature measurement is based on the property that the resistance value of a metal conductor increases with the increase of temperature. The temperature threshold is set inside the controller.

[0034] Furthermore, when the burner 19 backfires, the flame flows back into the fire hole, causing temperature changes and increasing the resistance of the thermal resistor. When it increases to a threshold value, the controller 191 will feedback to the computer controller 3, and the computer controller 3 will stop the gas distribution process by controlling the gas distribution cabinet 4 to ensure the safety of the burner 19.

[0035] like Figure 3The figure shows the schematic diagram of the sampling points for the mixer mixing effect measurement test of "a natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization". In order to ensure the airtightness of the pipeline, four different sections are selected at the outlet pipeline of the static gas mixer 7 for sampling (the four different sampling points are adjacent to each other at 90°). In order to measure the mixing effect of the mixer, a point is selected on each section, and the curvature radius of each point is and angle θ Each is different;

[0036] Furthermore, four sampling points of different cross sections are introduced into the rotational viscometer 9 for single-point measurement to measure the viscosity of different sampling points, that is, ;

[0037] Furthermore, the average viscosity The calculation expression is:

[0038] ;

[0039] Where: μ is the average viscosity, mPa∙s; μ 1~ μ 4 is the viscosity of a single sample, mPa∙s.

[0040] The calculation expression of standard deviation S is:

[0041] ;

[0042] Mixing unevenness The calculation expression is:

[0043] ;

[0044] Similarly, if the mixing unevenness is less than 5%, it can be proved that the mixing effect of the static mixer is good.

Claims

1. A natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization, characterized in that: It includes a hydrogen mixing module, a mixer performance measurement module, a gas supply module, a combustion performance measurement module and an exhaust gas treatment module. The mixer performance measurement module and the combustion performance measurement module are respectively connected to the hydrogen mixing module, the gas supply module is respectively connected to the mixer performance measurement module and the combustion performance measurement module, and the combustion performance measurement module is connected to the exhaust gas treatment module; the hydrogen mixing module is used to mix H2 and CNG gas, the mixer performance measurement module is used to measure the mixing effect of the mixer, the gas supply module is used to mix the mixed gas with the outside air, the combustion performance measurement module is used to measure the combustion performance of the burner, and the exhaust gas treatment module is used to treat toxic gases; The mixer performance measurement module comprises a pressure gauge (6), a static gas mixer (7), a rotational viscometer (9), a gas chromatograph (10) and a flow meter (11); the pressure gauges (6) are respectively installed at both ends of the static gas mixer (7); the pressure difference of the mixer is obtained by the difference between the values ​​of the two pressure gauges (6); and the performance of the mixer is evaluated by the pressure difference value; the rotational viscometer (9) is arranged on a bypass of the outflow pipeline of the static gas mixer (7); the mixed gas passing through the rotational viscometer (9) passes through the gas chromatograph (10) to measure the component content thereof and then flows into the pipeline; the flow meter (11) measures the gas flow rate in the pipeline; The gas supply module comprises a first anti-backflow device (12), a first flame arrester (13), a filter (16), a U-tube pressure gauge (17) and an air pump (18); the first anti-backflow device (12) is provided with pure water, the mixed gas enters through the air inlet pipe of the first anti-backflow device (12), is filtered in the water, and is discharged through the air outlet pipe of the first anti-backflow device (12), and the mixed gas is prevented from flowing back; the mixed gas flows through the first anti-backflow device (12) and then enters the first flame arrester (13), the function of the first flame arrester (13) is to prevent the danger of explosion in the pipeline when the burning appliance (19) burns back and generates fire; the outside air enters and first passes through the air filter (16), and then passes through the U-tube pressure gauge (17) to measure the pressure difference between the air inlet pipeline and the outside, which plays a role in balancing the pressure difference, and then the outside gas is sent in through the gas pump (18) to mix with the hydrogen-blended natural gas passing through the flame arrester (13); The combustion performance measurement module comprises a second anti-backgas device (14), a second flame arrester (15) and a burner (19); the mixed gas that has passed through the static gas mixer (7) and the mixed gas that has not passed through the mixer are respectively introduced into the burner for combustion; the gas that has not passed through the mixer flows through the second anti-backgas device (14) and the second flame arrester (15) to mix with the outside air and then enters the burner for combustion; since hydrogen burns quickly, an anti-flashback device is built into the burner to determine whether flashback occurs by comparing the thermal resistance value with a threshold value set by the controller, thereby measuring the effect of hydrogen blending of natural gas on the combustion performance of the burner of downstream equipment; The anti-flashback device comprises a controller (191) and a thermal resistor (192). When the burner (19) flashes back, the flame flows back into the fire hole, causing a temperature change and increasing the resistance of the thermal resistor. When the temperature increases to a threshold, the controller (191) will feed back to the computer controller (3). The computer controller (3) stops the gas distribution process by controlling the gas distribution cabinet (4) to ensure the safety of the burner (19).

2. The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization according to claim 1 is characterized in that: The hydrogen blending module comprises a pressure reducing station (1), a long tube trailer (2), a computer controller (3), a gas distribution cabinet (4) and a pressure reducing valve (5); the pressure reducing station (1) and the long tube trailer (2) respectively provide methane and hydrogen, the computer controller (3) controls the gas distribution cabinet (4) to distribute gas by inputting the hydrogen blending ratio, and adjusts the pressure of the mixed gas after distribution through the pressure reducing valve (5).

3. The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization according to claim 1 is characterized in that: The waste gas treatment module comprises a fume hood (20), and toxic gases generated after combustion of the burner are introduced into the fume hood (20) for treatment, thereby reducing pollution to the environment and achieving energy conservation and emission reduction.

4. The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization according to claim 1 is characterized in that: Four bypass pipes are arranged on the outlet pipe of the static gas mixer (7), and the four bypass pipes are connected to four different positions of the outlet pipe of the static gas mixer (7), so as to obtain four different sampling points. The viscosities of the four sampling points are measured respectively, and the mixing unevenness of the static gas mixer is calculated, so as to judge the mixing effect of the mixer.

5. The natural gas hydrogen-blended combustion performance measurement system based on gas mixer structure optimization according to claim 4 is characterized in that: The four different sampling points are adjacent to each other at 90°.

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