System and method for detecting burn-off rate of pulverized coal under hydrogen-coal-oxygen mixed injection condition

Abstract

The invention discloses a system and a method for detecting the burn-off rate of pulverized coal under a hydrogen-coal-oxygen mixed injection condition. The system comprises a double-cylinder structure mixed spraying burner, a hot blast stove, a pulverized coal collecting device, a gas supply system and a temperature control system. The inner cylinder of the burner is provided with a hydrophobic coating and an ultrasonic transducer array, and the adhesion rate of pulverized coal is reduced by more than 80% by combining cooling water circulation. A gas supply system adopts graded oxygen supply, normal-temperature high-pressure oxygen carries pulverized coal to be conveyed at a high speed, high-temperature low-pressure oxygen preheats the pulverized coal to an ignition point in advance, and the peak temperature of a reaction area is increased by 100-200 DEG C when the volume fraction of hydrogen is 5-20%. According to the detection method, the volume fractions of CO2, CO, H2 and O2 are measured through a gas analyzer, the carbon content of unburned coal powder is combined, a burn-off rate calculation formula is established, and the error is smaller than or equal to + / -3%. Experiments show that the system can accurately evaluate the improvement effect of mixed hydrogen injection on the burn-off rate of pulverized coal, the burn-off rate is improved from 85% to 92%-95%, CO2 emission is reduced by 40%-60%, and key support is provided for engineering optimization of the hydrogen energy collaborative combustion technology.

Description

Technical Field

[0001] The invention relates to combustion technology in the field of energy, and in particular to a system and method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection. Background Art

[0002] The burnout rate of pulverized coal is an important indicator to measure the efficiency of pulverized coal combustion, which is directly related to the thermal efficiency of the combustion system, the utilization rate of coal, and the emission level of environmental pollutants. During the combustion process, the higher the burnout rate of pulverized coal, the more complete the energy release of coal, the more efficient the combustion process, and the lower the emission of harmful gases such as carbon dioxide. Therefore, improving the burnout rate of pulverized coal not only helps to improve the efficiency of thermal energy utilization and reduce coal waste, but also effectively reduces the emission of greenhouse gases and pollutants. It is an important measure to promote energy structure optimization and environmental protection.

[0003] The current research field mainly improves the combustion environment of pulverized coal (adjusting furnace temperature, oxygen supply and pulverized coal injection method), designs more complex burners and furnace structures, adds combustion aids or catalysts (such as bauxite, calcium salt, etc.), controls the fineness of pulverized coal or uses flue gas recirculation (FGR) and other technologies to improve combustion efficiency. Although these methods have made some progress in improving the burnout rate of pulverized coal, there is still room for optimization, especially in terms of emission reduction and combustion efficiency.

[0004] As a highly efficient reducing agent and clean energy, hydrogen can effectively reduce the combustion starting temperature of coal powder and shorten the combustion reaction time due to its high combustion calorific value and rapid reaction characteristics, thus promoting the complete combustion of coal powder. By using hydrogen-coal-oxygen mixed injection technology, the injection ratio of hydrogen, coal powder and oxygen can be precisely controlled to optimize the furnace temperature distribution, enhance combustion stability, and reduce the generation of unburned coal powder and intermediate products.

[0005] Therefore, those skilled in the art are committed to developing a system and method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection. Summary of the invention

[0006] To achieve the above-mentioned purpose, the present invention first provides a detection system for the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection, characterized in that it includes a mixed injection burner, a hot blast furnace and a pulverized coal collecting device; a cooling water circulator, which is respectively connected to the front and rear ends of the hot blast furnace and the mixed injection burner, and is used for equipment temperature control; a gas supply system, which includes an oxygen source and a hydrogen source, the oxygen source is connected to the hot blast furnace through a high-temperature and low-pressure oxygen storage chamber on the one hand, and is mixed with high-pressure hydrogen through a normal-temperature and high-pressure oxygen storage chamber on the other hand; the mixed gas is connected to the pulverized coal hopper; the pulverized coal hopper is connected to the mixed injection burner; a temperature control system, which is connected to the mixed injection burner and the hot blast furnace, and is used to adjust the temperature and provide real-time feedback through a thermocouple; a vacuum pump, which is connected to the pulverized coal collecting device, and is used to remove air in the device; a gas analyzer, which is connected to the outlet of the pulverized coal collecting device, and is used to detect CO in the combustion generated gas 2 , CO, H 2 and O 2 volume fraction.

[0007] Furthermore, the mixed-injection burner includes two sleeves, an inner sleeve and an outer sleeve, and cooling water flows between the inner and outer sleeves. At the same time, an ultrasonic transducer array is circumferentially arranged between the inner and outer sleeves. The ultrasonic transducer array is a piezoelectric ceramic ultrasonic vibrator, which transmits ultrasonic vibration to the inner sleeve through cooling water, and utilizes the incompressibility of water to evenly transmit ultrasonic vibration to the entire inner sleeve to remove coal powder adhering to the wall of the inner sleeve.

[0008] Furthermore, the ultrasonic transducer array is a piezoelectric ceramic ultrasonic vibrator.

[0009] Furthermore, the inner wall of the inner cylinder is lined with a hydrophobic and oleophobic coating.

[0010] The present invention also provides a method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection using the detection system as described above, comprising the steps of:

[0011] (1) Start the cooling water circulation system;

[0012] (2) Heating the mixed-injection burner and the hot-air furnace to a preset temperature;

[0013] (3) evacuating the coal powder collection device using a vacuum pump;

[0014] (4) Grinding, sieving and drying the coal powder and then adding it into the coal powder hopper;

[0015] (5) filling the normal temperature high pressure oxygen gas storage chamber with high pressure oxygen, filling the normal temperature high pressure hydrogen gas storage chamber with high pressure hydrogen, and filling the high temperature low pressure oxygen gas storage chamber with high temperature low pressure oxygen;

[0016] (6) opening the outlets of the normal temperature high pressure oxygen gas storage chamber, the high temperature low pressure oxygen gas storage chamber and the normal temperature high pressure hydrogen gas storage chamber at the same time, so that the hydrogen, pulverized coal and oxygen are mixed and sprayed into the mixed spray burner;

[0017] (7) Detect CO in the post-combustion gas using a gas analyzer 2 , CO, H 2 and O 2 Volume fraction of

[0018] (8) Collect unburned coal powder and calculate the burnout rate.

[0019] Furthermore, the operating frequency of the piezoelectric ceramic ultrasonic vibrator is 25kHz, and the amplitude is 5-10μm.

[0020] Furthermore, the preset temperature in step (2) is 1000-1500° C., which is achieved by heating with a silicon-molybdenum rod.

[0021] Furthermore, the pressure of the high-pressure oxygen is 0.5-1.5 MPa, the temperature of the high-temperature low-pressure oxygen is 800-1200° C., and the pressure is 0.1-0.3 MPa.

[0022] Furthermore, in step (6), the volume fraction of hydrogen in the mixed gas is 5%-20%, and the mass ratio of oxygen to coal powder is 1.2-1.8:1.

[0023] Furthermore, the burnout rate calculation formula in step (8) is:

[0024]

[0025] Where m is the initial coal powder mass, c is the C content in the coal powder, n is O2 is the initial oxygen mole number, α, β and γ are CO 2 , CO and O 2 volume fraction.

[0026] The present invention achieves high precision, high efficiency and high reliability of coal powder burnout rate detection through structural innovation (ultrasonic anti-sticking, graded oxygen supply), process optimization (hydrogen-oxygen premixing, precise temperature control) and model upgrade (multi-parameter burnout rate calculation), providing key support for the engineering application of hydrogen energy synergistic combustion technology. The concept, specific structure and technical effects of the present invention will be further explained in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a principle diagram of the detection system of the coal powder burnout rate under the condition of hydrogen-coal-oxygen mixed injection of the present invention;

[0028] Figure 2 It is a cross-sectional view of the mixed injection burner of the present invention. DETAILED DESCRIPTION

[0029] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0030] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0031] The present invention provides a novel combustion method that improves the combustion efficiency of coal powder and reduces pollutant emissions through the synergistic effect of hydrogen, coal powder and oxygen. The method utilizes the high calorific value and rapid combustion characteristics of hydrogen, and sprays it into a combustion device together with coal powder and oxygen, and optimizes the combustion process by adjusting the ratio of the three. During the combustion process, the introduction of hydrogen not only reduces the combustion starting temperature of coal powder, but also significantly accelerates the combustion reaction, promotes the complete combustion of coal powder, and reduces the generation of incomplete combustion products.

[0032] In order to achieve the above object, the present invention adopts the following technical solution:

[0033] like Figure 1 As shown, firstly, a detection system for the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection is provided, including a mixed injection burner, a hot blast furnace and a pulverized coal collecting device; a cooling water circulator, respectively connected to the front and rear ends of the hot blast furnace and the mixed injection burner, for equipment temperature control; a gas supply system, including an oxygen source and a hydrogen source, the oxygen source is mixed with high-pressure hydrogen through a normal temperature high-pressure oxygen storage chamber, and is passed to the hot blast furnace through a high-temperature low-pressure oxygen storage chamber, and the mixed gas is passed to the pulverized coal hopper, and the pulverized coal hopper is connected to the mixed injection burner; a temperature control system, connected to the mixed injection burner and the hot blast furnace, for adjusting the temperature and providing real-time feedback through a thermocouple; a vacuum pump, connected to the pulverized coal collecting device, for removing air from the device; a gas analyzer, connected to the outlet of the pulverized coal collecting device, for detecting CO in the combustion generated gas 2 , CO, H 2 and O 2 volume fraction.

[0034] The experiment found that part of the coal powder injected during the combustion process would adhere to the wall of the mixed injection burner, affecting the final test results. Figure 2As shown, the mixed-injection burner includes two sleeves, an inner tube 2 and an outer tube 1, cooling water is passed between the inner and outer sleeves, and an ultrasonic transducer array 5 is circumferentially arranged between the inner and outer tubes. The ultrasonic transducer array 5 is a piezoelectric ceramic ultrasonic vibrator, which transmits ultrasonic vibration to the inner tube 2 through cooling water, and utilizes the incompressibility of water to uniformly transmit ultrasonic vibration to the entire inner tube 2. During the combustion process, it vibrates at an operating frequency of 25kHz and an amplitude of 5-10μm to prevent coal powder from adhering. At the same time, a hydrophobic and oleophobic coating 3 is lined on the inner wall of the inner tube 2 to reduce coal powder adhesion.

[0035] Based on the above detection system, the present invention proposes a method for detecting the burnout rate of pulverized coal during hydrogen-coal-oxygen mixed injection, which comprises the following steps:

[0036] (1) Open the cooling water circulation system in the multi-channel mixed injection combustion system;

[0037] (2) Heating the burners in the multi-channel mixed injection combustion system and the hot air furnace of the air supply system to a preset temperature;

[0038] (3) Using a vacuum pump to evacuate the coal powder collection device in the multi-channel mixed injection combustion system;

[0039] (4) Adding pulverized coal required for the combustion reaction in the experiment into the multi-channel mixed injection combustion system;

[0040] (5) Filling the multi-channel mixed injection combustion system with normal temperature high-pressure oxygen and high-pressure hydrogen to blow the pulverized coal required for the combustion reaction into the burner;

[0041] (6) Filling the multi-channel mixed injection combustion system with high-temperature, low-pressure oxygen to preheat the reactants and improve the combustion reaction efficiency;

[0042] (7) Spraying hydrogen, coal powder and oxygen into a burner for combustion reaction;

[0043] (8) Using a gas analyzer to measure the composition and content of the gas generated after the combustion reaction;

[0044] (9) collecting the unburned coal powder after the combustion reaction in a coal powder collecting device;

[0045] (10) Calculate the burnout rate of pulverized coal based on the composition and content of the gas generated after the combustion reaction;

[0046] (11) Experimental characterization of unburned coal powder can reveal the macroscopic changes in the increase of coal powder burnout rate after hydrogen enrichment.

[0047] Among them, the circulating cooling water is connected to the front and rear ends of the hot air furnace and burner of the air supply system respectively, in order to avoid material damage caused by excessive internal temperature of the hot air furnace and burner, and to extend the service life of the equipment.

[0048] Among them, the burner in the multi-channel mixed injection combustion system and the hot air furnace of the air supply system are respectively connected to the temperature control system. The burner and the hot air furnace are heated by silicon-molybdenum rods. When current passes through the silicon-molybdenum rods, due to its certain resistance (usually determined by the characteristics of the alloy material), according to Joule's law, heat will be generated when the current flows inside the silicon-molybdenum rods. At the same time, the thermocouple will promptly feed back the temperature of the burner and the hot air furnace to the temperature display of the temperature control system.

[0049] Among them, the coal powder collection device in the multi-channel mixed injection combustion system is connected to the vacuum pump, and the vacuum pump is used to remove the air in the coal powder collection device to ensure that the generated gas after the combustion reaction is not contaminated in the process of passing through the coal powder collection device to reach the gas analyzer, thereby ensuring the accuracy of the generated gas composition and content.

[0050] The coal powder used in the experiment was ground and passed through a 200-mesh sieve to ensure its uniformity and combustibility. The ground coal powder was placed in a 105°C oven for 2 hours to fully remove moisture, and the coal powder of the mass used in the experiment was weighed on a scale and placed in the hopper of the multi-channel mixed injection combustion system.

[0051] Among them, the gas supply system includes two gas sources of oxygen and hydrogen. The oxygen cylinder is connected to the inlet of the normal temperature and high pressure oxygen storage chamber and the inlet of the high temperature and low pressure oxygen storage chamber respectively, and the hydrogen is connected to the inlet of the normal temperature and high pressure hydrogen storage chamber. The inlets of the normal temperature and high pressure oxygen storage chamber, the high temperature and low pressure oxygen storage chamber and the normal temperature and high pressure hydrogen storage chamber are all controlled by solenoid valves.

[0052] Among them, the outlet of the normal temperature and high pressure oxygen gas storage chamber and the outlet of the high temperature and low pressure oxygen gas storage chamber merge at the front end of the hopper filled with coal powder, so that the mixed gas of normal temperature and high pressure oxygen and high temperature and low pressure oxygen carries the coal powder in the pipeline at a very high flow rate and merges with it at the outlet of the high temperature and low pressure oxygen gas storage chamber, where the coal powder begins to undergo incomplete combustion reaction, and then hydrogen, coal powder and oxygen are evenly sprayed into the burner. The outlets of the normal temperature and high pressure oxygen gas storage chamber, the high temperature and low pressure oxygen gas storage chamber and the normal temperature and high pressure hydrogen gas storage chamber are all controlled by solenoid valves.

[0053] The burner outlet is connected to the inlet of a coal powder collecting device in the multi-channel mixed injection combustion system, and the other end of the inlet of the coal powder collecting device is connected to a gas analyzer.

[0054] Among them, the gas CO generated after the combustion reaction is analyzed by a gas analyzer. 2 , CO, H 2 and O 2 The content was measured, and then the pulverized coal burnout rate under different hydrogen injection conditions was calculated to verify that the addition of hydrogen can effectively improve the pulverized coal burnout rate.

[0055] In a specific embodiment, the following steps are followed:

[0056] S1) Turn on the cooling water circulation system switch in the multi-channel mixed injection combustion system.

[0057] S2) Turn on the burner heating switch in the multi-channel mixed injection combustion system to heat the burner to a temperature under a preset condition.

[0058] S3) Turn on the heating switch of the hot air furnace of the air supply system to heat the hot air furnace to a temperature under a preset condition.

[0059] S4) Turn on the vacuum pump to evacuate the coal powder collection device in the multi-channel mixed injection combustion system.

[0060] S5) Grind the coal powder used in the experiment and pass it through a 200-mesh sieve.

[0061] S6) putting the coal powder that has passed through a 200-mesh sieve into an oven for drying.

[0062] S7) Use a balance to weigh the coal powder required for the combustion reaction and put it into the hopper of the multi-channel mixed injection combustion system.

[0063] S8) Open the electromagnetic valve switch at the entrance of the normal temperature and high pressure oxygen storage chamber to fill the high pressure oxygen storage chamber with a preset amount of high pressure oxygen, and close the electromagnetic valve switch at the entrance of the normal temperature and high pressure oxygen storage chamber.

[0064] S9) Open the electromagnetic valve switch at the entrance of the normal temperature and high pressure hydrogen gas storage chamber to fill the high pressure hydrogen gas storage chamber with a preset amount of high pressure hydrogen, and close the electromagnetic valve switch at the entrance of the normal temperature and high pressure hydrogen gas storage chamber.

[0065] S10) Open the electromagnetic valve switch at the entrance of the high-temperature low-pressure oxygen storage chamber to fill the high-temperature low-pressure oxygen storage chamber with a high-temperature oxygen amount under preset conditions, and close the electromagnetic valve switch at the entrance of the high-temperature low-pressure oxygen storage chamber.

[0066] S11) The outlet electromagnetic valve switches of the high-temperature low-pressure oxygen gas storage chamber, the normal-temperature high-pressure hydrogen gas storage chamber and the high-temperature low-pressure oxygen gas storage chamber are opened simultaneously, so that hydrogen, pulverized coal and oxygen are sprayed into the burner in a uniform mixture for combustion reaction.

[0067] S12) Open the burner outlet switch, and the gas-solid mixture generated by the reaction enters the coal powder collecting device, and the generated gas continues to enter the gas analyzer, and the unburned coal powder remains in the coal powder collecting device to be taken out later.

[0068] S13) Measure CO through gas analyzer 2 , CO, H 2 and O 2 The volume fraction can be used to calculate the pulverized coal burnout rate under the above conditions.

[0069] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A system for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection, characterized in that: It includes a mixed-injection burner, a hot-blast furnace and a pulverized coal collection device; a cooling water circulator, which is respectively connected to the front and rear ends of the hot-blast furnace and the mixed-injection burner, and is used for equipment temperature control; a gas supply system, which includes an oxygen source and a hydrogen source, wherein the oxygen source is connected to the hot-blast furnace through a high-temperature and low-pressure oxygen storage chamber on the one hand, and is mixed with high-pressure hydrogen through a normal-temperature and high-pressure oxygen storage chamber on the other hand; the mixed gas is connected to the pulverized coal hopper; the pulverized coal hopper is connected to the mixed-injection burner; a temperature control system, which is connected to the mixed-injection burner and the hot-blast furnace, and is used for adjusting the temperature and providing real-time feedback through a thermocouple; a vacuum pump, which is connected to the pulverized coal collection device, is used for removing air from the device; The gas analyzer is connected to the outlet of the coal powder collecting device and is used to detect the volume fractions of CO2, CO, H2 and O2 in the combustion generated gas.

2. The system for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 1, wherein: The mixed-injection burner includes two sleeves, an inner sleeve and an outer sleeve. Cooling water flows between the inner and outer sleeves. At the same time, an ultrasonic transducer array is arranged circumferentially between the inner and outer sleeves. The ultrasonic transducer array is a piezoelectric ceramic ultrasonic vibrator. The ultrasonic vibration is transmitted to the inner sleeve through cooling water, and the incompressibility of water is used to evenly transmit the ultrasonic vibration to the entire inner sleeve to remove the coal powder adhering to the wall of the inner sleeve.

3. The system for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 2, wherein: The ultrasonic transducer array is a piezoelectric ceramic ultrasonic vibrator.

4. The system for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 3, wherein: The inner wall of the inner cylinder is lined with a hydrophobic and oleophobic coating.

5. A method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection using the detection system as claimed in claim 4, characterized in that: Includes steps: (1) Start the cooling water circulation system; (2) Heating the mixed-injection burner and the hot-air furnace to a preset temperature; (3) evacuating the coal powder collection device using a vacuum pump; (4) Grinding, sieving and drying the coal powder and then adding it into the coal powder hopper; (5) High-pressure oxygen is filled into the normal-temperature high-pressure oxygen storage chamber, and high-pressure hydrogen is filled into the normal-temperature high-pressure hydrogen storage chamber. Filling the high-temperature and low-pressure oxygen into the high-temperature and low-pressure oxygen storage chamber; (6) opening the outlets of the normal temperature high pressure oxygen gas storage chamber, the high temperature low pressure oxygen gas storage chamber and the normal temperature high pressure hydrogen gas storage chamber at the same time, so that the hydrogen, pulverized coal and oxygen are mixed and sprayed into the mixed spray burner; (7) Detecting the volume fractions of CO2, CO, H2 and O2 in the post-combustion gas by a gas analyzer; (8) Collect unburned coal powder and calculate the burnout rate.

6. The method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 5, wherein: The operating frequency of the piezoelectric ceramic ultrasonic vibrator is 25kHz and the amplitude is 5-10μm.

7. The method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 6, wherein: The preset temperature in step (2) is 1000-1500° C., which is achieved by heating with a silicon-molybdenum rod.

8. The method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 7, wherein: The pressure of the high-pressure oxygen is 0.5-1.5 MPa, the temperature of the high-temperature low-pressure oxygen is 800-1200° C., and the pressure is 0.1-0.3 MPa.

9. The method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 8, wherein: In step (6), the volume fraction of hydrogen in the mixed gas is 5%-20%, and the mass ratio of oxygen to coal powder is 1.2-1.8:

1.

10. The method for detecting the burnout rate of pulverized coal under the condition of hydrogen-coal-oxygen mixed injection as claimed in claim 9, wherein: The burnout rate calculation formula in step (8) is: Where m is the initial coal powder mass, c is the C content in the coal powder, and n is O2 is the initial molar number of oxygen, α, β and γ are the volume fractions of CO2, CO and O2 respectively.

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