Biomass drag force model verification device and method

Abstract

The invention discloses a biomass drag force model verification device which comprises a shell, an air blower, a frequency converter, a feeder and a computer. The top of the shell is communicated with the feeder, and one side of the shell is communicated with the air blower; the shell is in a closed state, and a plurality of collecting grooves are formed in the bottom in the shell; the frequency converter is connected with the air blower, and the computer is connected with the feeding machine. The invention further discloses a biomass drag model verification method, actual operation is compared with a simulation result, and the accuracy of the model is verified. The method has the beneficial effects that the accurate verification of reliable data on the motion characteristics of the biomass particles is improved so as to support the development of a gas-solid two-phase kinetic model.

Description

Technical Field

[0001] The invention relates to the field of biomass fuel transportation, and in particular to a biomass drag model verification device and method. Background Art

[0002] Driven by the "dual carbon" goal, coal-fired units coupled with biomass direct combustion power generation have become a feasible way to fully utilize low-carbon emission biomass energy. However, at present, there are few related demonstration projects in China, and the technical maturity needs to be improved. There are multiple challenges such as fuel crushing and transportation, combustion control, and boiler heating surface corrosion.

[0003] During the combustion process, the particle trajectory directly affects its residence time, distribution and contact with oxygen in the furnace. Accurately obtaining the particle trajectory can help optimize the combustion conditions, ensure that the particles are fully burned in the furnace, and improve combustion efficiency. Computational fluid dynamics has become an important tool for optimizing the design and operation of energy and power devices. In this context, scholars have proposed various gas-solid two-phase dynamic models of non-spherical particles to improve the accuracy of the simulation of their trajectory and combustion process.

[0004] The background for developing the biomass gas-solid two-phase flow model is mainly based on the promotion of global energy transformation and the "dual carbon" goal, the potential and challenges of biomass energy utilization, the advantages of coal-fired units coupled with biomass power generation, and the application of computational fluid dynamics (CFD) in combustion process simulation. By developing a gas-solid two-phase flow model suitable for non-spherical biomass large particles, its motion trajectory and combustion process can be accurately simulated, combustion efficiency can be optimized, pollutant emissions can be reduced, and the efficient utilization of biomass energy and the development of clean combustion technology can be promoted.

[0005] In a dilute phase flow environment, the drag coefficient correlation of various typical non-spherical particles is obtained by numerical simulation, and a set of generally applicable dynamic models is constructed. In order to promote the application of the model, further devices are needed to verify it, so that it can play a role in industrial multiphase flow simulation, and then support the research on particle transport and thermal conversion in the direct combustion coupling process of biomass and coal powder.

[0006] However, there is currently a lack of reliable data verification in the simulation of the gas-solid two-phase kinetics of biomass particles, which makes it impossible to accurately simulate the movement trajectory of the particles and hinders the development of gas-solid two-phase kinetic models.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art known to a person skilled in the art. Summary of the invention

[0008] The technical problem to be solved by the present invention is how to solve the problem that the current gas-solid two-phase dynamics simulation of biomass particles lacks accurate data, cannot accurately simulate the movement trajectory of particles, and hinders the development of gas-solid two-phase dynamics models.

[0009] The present invention solves the above technical problems through the following technical means:

[0010] A biomass drag model verification device includes a shell, a blower, a frequency converter, a feeder, and a computer; the top of the shell is connected to the feeder, and one side of the shell is connected to the blower; the shell is in a closed state, and a plurality of collecting troughs are formed at the bottom of the shell; the frequency converter is connected to the blower, and the computer is connected to the feeder.

[0011] The present invention controls different wind speeds and wind temperatures of the blower through a frequency converter. After the feeder drops the material, it is dispersed in different collecting troughs under wind conditions. The accuracy of the biomass particle drag model is verified through the results of actual operation. The present invention can improve the accurate verification of the motion characteristics of biomass particles with reliable data to support the development of the gas-solid two-phase kinetic model.

[0012] Preferably, one side of the shell is connected to the blower through an air inlet pipe, and the other side of the shell is connected to the cyclone separator through an air outlet pipe. A sensor and an air valve are connected to the air inlet pipe, and the sensor is connected to the computer.

[0013] By closely monitoring the experimental conditions through sensors, the measurement accuracy of the particle drag characteristics is improved, which effectively helps to optimize the model parameters.

[0014] Preferably, a bypass valve is further included, and the bypass valve is connected to the intake pipe.

[0015] The bypass valve cooperates with the air valve to adjust the flow on the intake pipe, which can expand the adjustment range and accuracy.

[0016] Preferably, the shell includes a box body and a top cover, the top cover is connected to the top surface of the box body to form a closed state, and the shell also includes a plurality of air holes.

[0017] The air vents can stabilize the pressure difference between inside and outside.

[0018] Preferably, the bottom surface of the shell is connected to a plurality of partitions, and the plurality of partitions are cross-arranged to form a plurality of collecting tanks.

[0019] Preferably, a heating device is installed in the blower, and the heating device is connected to the frequency converter.

[0020] Preferably, a cyclone separator is further included; the other side of the shell is connected to the cyclone separator.

[0021] Preferably, the feeder comprises a funnel and a conveyor belt, the bottom of the funnel is connected to the conveyor belt, and the bottom of the conveyor belt is communicated with the shell.

[0022] The present invention also provides a biomass drag model verification method, using any one of the above-mentioned biomass drag model verification devices, comprising the following steps:

[0023] Turn on the blower, adjust the frequency converter, set the wind speed and wind temperature, and after stable operation, set the injection speed of the feeder. After stabilization, start injecting biomass and start timing. Then count the number or mass of biomass particles in each collection tank within time t, and perform operations under different wind speeds, wind temperatures and wind speeds according to the above steps;

[0024] The device is modeled through software, and the boundary conditions identical to the actual working conditions are set. The number or mass of particles in each collection tank in actual operation is compared with the number or mass of particles in the corresponding collection tank in the simulation results to verify the accuracy of the model.

[0025] Preferably, verifying the drag model of biomass with different particle sizes includes the following steps: preparing biomass with different particle sizes; setting the wind speed and temperature of the blower, counting the number or mass of particles in each collecting tank within t1, and performing the same operation multiple times after each change in the particle size of the biomass particles; and performing multiple operations on biomass with different particle sizes according to the above steps; setting the same boundary conditions as the corresponding particle size in the numerical simulation, counting the number or mass of particles in each collecting tank within t1, and comparing with the actual data to verify the accuracy of the drag model of biomass particles under different particle sizes.

[0026] Verifying the biomass drag model under different wind speeds includes the following steps: for biomass particles of the same particle size, setting the wind speed and wind temperature of the blower in actual operation, counting the number or mass of particles in each collecting tank within t2, and performing the same operation multiple times after each change of the wind speed; setting the same boundary conditions as the corresponding wind speed in numerical simulation, counting the number or mass of particles in each collecting tank within t2, and comparing with the actual data to verify the accuracy of the biomass particle drag model under different wind speeds;

[0027] Verifying the drag model of biomass particles under different wind temperatures includes the following steps: setting the wind speed and wind temperature of the blower, counting the number or mass of particles in each collecting tank within t3, and performing the same operation multiple times after each change of the blower wind temperature; setting the same boundary conditions as the corresponding wind temperature in the numerical simulation, counting the number or mass of particles in each collecting tank within t3, and comparing with the actual data to verify the accuracy of the drag model of biomass particles under different wind temperatures.

[0028] The advantages of the present invention are:

[0029] The present invention controls different wind speeds and wind temperatures of the blower through a frequency converter. After the feeder drops the material, it is dispersed in different collecting troughs under wind conditions. The accuracy of the biomass particle drag model is verified through the results of actual operation. The present invention can improve the accurate verification of the motion characteristics of biomass particles with reliable data to support the development of the gas-solid two-phase kinetic model.

[0030] By closely monitoring the experimental conditions through sensors, the measurement accuracy of the particle drag characteristics is improved, which effectively helps to optimize the model parameters.

[0031] The bypass valve cooperates with the air valve to adjust the flow on the intake pipe, which can expand the adjustment range and accuracy.

[0032] The air vents can stabilize the pressure difference between inside and outside.

[0033] The reasonable structural design, transparency and ease of operation of the device provide great convenience for monitoring and data collection during the verification process, and expand the potential value of the device in industrial applications.

[0034] A cyclone separator is provided to process the exhaust gas and collect the particles that did not fall into the collection tank during the experiment, which has environmental value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of the structure of a biomass drag model verification device according to an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of the distribution of biomass particles of the present invention;

[0037] Numbers in the figure:

[0038] 1. Shell; 2. Blower; 3. Frequency converter; 4. Feeder; 5. Computer; 6. Cyclone separator; 7. Sensor; 8. Air valve; 9. Bypass valve. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] The biomass drag model verification device includes a shell 1, a blower 2, a frequency converter 3, a feeder 4, a computer 5, a cyclone separator 6, a sensor 7, an air valve 8, and a bypass valve 9; the top of the shell 1 is connected to the feeder 4, one side of the shell 1 is connected to the blower 2, and the other side of the shell 1 is connected to the cyclone separator 6; the shell 1 is in a closed state, and a plurality of collecting tanks are formed at the bottom of the shell 1; the frequency converter 3 is connected to the blower 2, and the computer 5 is connected to the feeder 4. The sensor 7, the air valve 8, and the bypass valve 9 are all connected to the air outlet end of the blower 2, and the sensor 7 is connected to the computer 5.

[0042] Specifically, the shell 1 is made of transparent material, and the shell 1 includes a box 11 and a top cover 12. The top cover 12 is connected to the top surface of the box 11 to form a closed state, and has good heat preservation. The shell 1 also includes a plurality of air holes, which can stabilize the internal and external pressure difference. In this embodiment, the box 11 is a rectangular cavity, and a plurality of partitions 13 are installed at the bottom of the box 11. The partitions 13 can be connected to the bottom of the box 11 by snapping, or multiple partitions 13 can be installed in a cross frame outside and placed in the box 11. In this embodiment, fourteen partitions 13 are arranged in the horizontal direction of the initial velocity, and six partitions 13 are arranged in the horizontal direction perpendicular to the initial velocity. The partition 13 is made of transparent material, with a thickness of 0.01 meters and a height of 0.2 meters, so as to better collect biomass particles. The spacing between the partitions and the height of the gas pipeline from the bottom of the collecting tank are set as needed to ensure that the biomass particles have enough movement time in the air, and at the same time, each partition 13 is collected as much as possible to facilitate statistics.

[0043] The left side of the shell 1 is connected to the blower 2 through an air inlet pipe, and the right side of the shell is connected to the cyclone separator 6 through an air outlet pipe. The air inlet pipe is made of transparent material and has excellent thermal insulation performance.

[0044] The air inlet duct is connected to a sensor 7, an air valve 8, and a bypass valve 9, and the sensor 7 is connected to the computer 5. The sensor 7 is used to closely monitor the experimental conditions, and the measurement accuracy of the particle drag characteristics is improved, which effectively helps to optimize the model parameters.

[0045] The blower 2 has a built-in heating device, which is connected to the frequency converter 3, and the frequency converter 3 is used to control the heating device to adjust the wind temperature. The sensor 7 is used to measure the flow rate and temperature of the gas delivered by the blower 2 and transmit the data to the computer 5.

[0046] Since the flow range of the frequency converter 3 to adjust the blower 2 is limited, if the opening of the air valve 8 has reached the minimum flow rate, the bypass valve 9 needs to be opened to further reduce the flow rate, so that the flow valve 8 cooperates with the bypass pipe 9 to achieve precise regulation of the flow rate.

[0047] The feeder 4 includes a funnel and a conveyor belt, the bottom of the funnel is connected to the conveyor belt, and the bottom of the conveyor belt is connected to the shell. When the biomass particles fall from the conveyor belt, the blower 2 blows, so that different biomasses fall into different collection tanks due to their own quality and shape. The drag model of biomass particles is verified according to the results of actual operation.

[0048] In this embodiment, the frequency converter 3 is used to control the blower 2 to achieve different wind speeds and wind temperatures. After the feeder drops the material, it is dispersed in different collecting tanks under wind conditions. The accuracy of the biomass particle drag model is verified through the results of actual operation. This embodiment can improve the accurate verification of the movement characteristics of biomass particles by reliable data to support the development of the gas-solid two-phase kinetic model.

[0049] Embodiment 2:

[0050] like Figure 2 As shown, this embodiment provides a biomass drag model verification method, which adopts the biomass drag model verification device in the above-mentioned embodiment 1.

[0051] It can be seen from the first embodiment that the biomass particles are blown by the blower during the falling process. By analyzing the force of the particles moving in the fluid, the following equation can be obtained:

[0052]

[0053] C D =f(R e ,A r ,γ,θ)

[0054] In the formula, G is the resistance and gravity of the particle; m p Indicates the mass of the particles; C D is the dimensionless resistance coefficient; A * =A 0 cos(θ) represents the projected area perpendicular to the direction of motion during the particle falling process, where A 0 It is the projected area of ​​the particle facing the airflow direction at the beginning of the falling process; and are the velocities of the fluid and particles, respectively; θ is the angle between the direction of the fluid flow and the long axis of the particles in the measurement area, that is, the incident angle at different times; is the acceleration of the particle; R e Reynolds number; A r is the particle aspect ratio; γ is the ratio of particle temperature to air flow temperature.

[0055] The biomass drag model validation method includes the following steps:

[0056] The model verification process is to turn on the blower, adjust the frequency converter, set the wind speed and temperature, adjust the air valves on the gas pipeline and bypass pipe to make the gas flow rate reach the specified value, set the injection speed of the feeder and start injecting biomass particles. After the operation is stable, start timing, and then count the number or mass of biomass particles in each collection tank within a period of time. Perform the same operation multiple times according to the above steps. The simulation process is to model the device through ANSYS Fluent, EDEM and other software, set the same boundary conditions as the actual working conditions, count the number or mass of particles in each collection tank within a certain time t, and the statistical time length is consistent with the setting in the actual operation. Then compare the number or mass of particles in each collection tank in the actual operation with the number or mass of particles in the corresponding collection tank in the simulation results to verify the accuracy of the model.

[0057] Verifying the drag model of biomass with different particle sizes includes the following steps: preparing biomass with different particle sizes; setting the wind speed and temperature of the blower, counting the number or mass of particles in each collecting tank within t1, and performing the same operation multiple times after each change in the particle size of the biomass particles; and performing the above steps multiple times on biomass with different particle sizes; setting the same boundary conditions as the corresponding particle size in the numerical simulation, counting the number or mass of particles in each collecting tank within t1, and comparing with the actual data to verify the accuracy of the drag model of biomass particles under different particle sizes.

[0058] Verifying the biomass drag model under different wind speeds includes the following steps: for biomass particles of the same particle size, setting the wind speed and wind temperature of the blower in actual operation, counting the number or mass of particles in each collecting tank within t2, and performing the same operation multiple times after each change of the wind speed; setting the same boundary conditions as the corresponding wind speed in numerical simulation, counting the number or mass of particles in each collecting tank within t2, and comparing with the actual data to verify the accuracy of the biomass particle drag model under different wind speeds;

[0059] Verifying the drag model of biomass particles under different wind temperatures includes the following steps: setting the wind speed and wind temperature of the blower, counting the number or mass of particles in each collecting tank within t3, and performing the same operation multiple times after each change of the blower wind temperature; setting the same boundary conditions as the corresponding wind temperature in the numerical simulation, counting the number or mass of particles in each collecting tank within t3, and comparing with the actual data to verify the accuracy of the drag model of biomass particles under different wind temperatures.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Biomass drag model verification device, characterized in that: Including housing, blower, frequency converter, feeder, computer; The top of the shell is connected to the feeder, and one side of the shell is connected to the blower; The shell is in a closed state, and a plurality of collecting grooves are formed at the bottom of the shell; The frequency converter is connected to the blower, and the computer is connected to the feeder.

2. The biomass drag model verification device according to claim 1, characterized in that: One side of the shell is connected to the blower through an air inlet pipe, and the other side of the shell is connected to the cyclone separator through an air outlet pipe. The air inlet pipe is connected to a sensor and an air valve, and the sensor is connected to the computer.

3. The biomass drag model verification device according to claim 2, characterized in that: A bypass valve is also included, and the bypass valve is connected to the intake pipe.

4. The biomass drag model verification device according to claim 1, characterized in that: The shell comprises a box body and a top cover, wherein the top cover is connected to the top surface of the box body to form a closed state, and the shell also comprises a plurality of air holes.

5. The biomass drag model verification device according to claim 1, characterized in that: The bottom surface of the shell is connected to a plurality of partitions, and the plurality of partitions are arranged crosswise to form a plurality of collecting grooves.

6. The biomass drag model verification device according to claim 1, characterized in that: A heating device is installed in the blower, and the heating device is connected to the frequency converter.

7. The biomass drag model verification device according to claim 1, characterized in that: It also includes a cyclone separator; the other side of the shell is connected to the cyclone separator.

8. The biomass drag model verification device according to claim 1, characterized in that: The feeder comprises a hopper and a conveyor belt, the bottom of the hopper is connected to the conveyor belt, and the bottom of the conveyor belt is communicated with the shell.

9. Biomass drag model verification method, characterized in that: The biomass drag model verification device according to any one of claims 1 to 8 comprises the following steps: Turn on the blower, adjust the frequency converter, set the wind speed and wind temperature, and after stable operation, set the injection speed of the feeder. After stabilization, start injecting biomass and start timing. Then count the number or mass of biomass particles in each collection tank within time t, and perform operations under different wind speeds, wind temperatures and wind speeds according to the above steps; The device is modeled through software, and the boundary conditions identical to the actual working conditions are set. The number or mass of particles in each collection tank in actual operation is compared with the number or mass of particles in the corresponding collection tank in the simulation results to verify the accuracy of the model.

10. The biomass drag model verification device according to claim 9, characterized in that: Verifying the drag model of biomass with different particle sizes includes the following steps: preparing biomass with different particle sizes; setting the wind speed and temperature of the blower, counting the number or mass of particles in each collecting tank within t1, and performing the same operation multiple times after each change in the particle size of the biomass particles; and performing the above steps multiple times on biomass with different particle sizes; setting the same boundary conditions as the corresponding particle size in the numerical simulation, counting the number or mass of particles in each collecting tank within t1, and comparing with the actual data to verify the accuracy of the drag model of biomass particles under different particle sizes. Verifying the biomass drag model under different wind speeds includes the following steps: for biomass particles of the same particle size, setting the wind speed and wind temperature of the blower in actual operation, counting the number or mass of particles in each collecting tank within t2, and performing the same operation multiple times after each change of the wind speed; setting the same boundary conditions as the corresponding wind speed in numerical simulation, counting the number or mass of particles in each collecting tank within t2, and comparing with the actual data to verify the accuracy of the biomass particle drag model under different wind speeds; Verifying the drag model of biomass particles under different wind temperatures includes the following steps: setting the wind speed and wind temperature of the blower, counting the number or mass of particles in each collecting tank within t3, and performing the same operation multiple times after each change of the blower wind temperature; setting the same boundary conditions as the corresponding wind temperature in the numerical simulation, counting the number or mass of particles in each collecting tank within t3, and comparing with the actual data to verify the accuracy of the drag model of biomass particles under different wind temperatures.

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