Micro-fuel continuous supply method applied to laboratory reactor

Abstract

The invention discloses a trace fuel continuous supply method applied to a laboratory reactor, which comprises the following steps: S1, placing micron particle solid fuel in a storage bin, keeping turning by a stirring rod and a spiral blanking piece driven by a driving motor, and outputting pulverized coal in the storage bin to the central position of a disc; water molecules in the pulverized coal particles form steam under the action of microwave heating, and the steam is separated from the micrometer particle solid fuel; s2, the micrometer particle solid fuel piles located in the center of the disc rotate along with the disc and are evenly dispersed into thin layers from the center of the disc to the circumferential direction under the action of centrifugal force, and then the thin layers are scraped into a feeding port of the laboratory reactor through a scraper; dry fuel is supplied to the center position of the disc, the dry fuel is uniformly dispersed on the surface of the disc through the centrifugal force of rotation of the disc, and uniformly dispersed micron-sized fuel particles which are continuously supplied to the edge position from the center position on the surface of the disc are supplied to a laboratory combustor in cooperation with the scraper.

Description

Technical Field

[0001] The invention relates to the field of combustion technology, in particular to a method for continuously supplying trace fuels applied to a laboratory reactor. Background Art

[0002] In the laboratory, in order to study the application of coal powder or other substances in combustion experiments, catalytic reaction tests and material synthesis, the feed rate needs to be strictly controlled to ensure the accuracy of the test data and the repeatability of the experiment. However, traditional coal powder feeding equipment is mainly evaluated in industrial production and is usually not suitable for laboratory use. Traditional equipment has problems in feed rate, stability and anti-clogging. Especially when the coal powder particles are fine and micro-feeding is required, problems such as blockage, deviation and agglomeration are prone to occur, resulting in uneven feeding. In order to meet the special needs of the laboratory, it is extremely important to develop a micro-coal powder feeding device suitable for laboratory use.

[0003] The main feeding methods currently used include screw, ejector, and roller types. The lower limit of the feeding amount of these existing micro-feeders is relatively high, usually a few kg / h. For lower feeding amounts, there are usually problems such as low feeder speed, powder sticking, and discontinuous feeding. Existing feeding devices are difficult to meet the lower feeding rates required by small laboratory reactors, and the feeding amount of grams per hour is even more technically difficult in the industry. In laboratory research systems, especially experimental devices using sedimentation furnaces and fluidized beds, quantitative, stable, and precise feeding is often required to ensure the smooth progress of the experiment. In order to obtain the combustion characteristics of coal powder, biomass, or a mixture of coal powder and biomass, it is first necessary to ensure continuous and stable powder feeding to meet the sustainability of the experiment and the repeatability of the rules; more importantly, it is necessary to ensure micro-powder feeding to achieve a fully stable reaction of the sample in the reactor.

[0004] As for China's energy situation, coal is still the most used primary energy. As for the burning of coal, more and more people are paying attention to NO x , volatile organic compounds and other emission problems. Current studies have shown that the mixed combustion of coal powder and biomass can not only reduce the emission of pollutants, but also alleviate the dependence on coal resources to a certain extent, which is of great significance to changing my country's energy structure. Although there is a certain industrial basis for the mixed combustion of coal and biomass, most of it is still in the experimental research stage. The dropper furnace is an important reaction kinetics experimental device for studying the synergistic effect, coupling mechanism and solid fuel reaction process of the mixed combustion of coal and biomass. Accurate and stable control of the feeding rate of coal powder and the mixed feeding of coal powder and biomass is an important prerequisite for studying the coupling mechanism and combustion reaction characteristics. Maintaining stable and uniform feeding is particularly important.

[0005] Taking a dropper furnace as an example, within the entire dropper furnace flow system, the feeder is responsible for continuously delivering the solid fuel particles required for the reaction into the furnace. Commonly used solid fuels for laboratory research (pulverized coal or a mixture of coal and biomass) typically have a particle size of around 100µm or smaller, and the feed rate is typically around 1g / min or less. Due to the fine fuel particles and small feed rates, the entire reaction system is prone to flow degradation and pipe blockage during the actual feeding process. Therefore, ensuring the normal output of solid fuel during the feeding process, and further achieving stable operation and reliable regulation, is a major challenge currently facing domestic developers. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for continuously supplying trace fuel for laboratory reactors. The present invention supplies dry fuel at the center of a disc, utilizes the centrifugal force of the disc's rotation to evenly disperse it on the disc surface, and cooperates with a scraper to continuously supply evenly dispersed micron-sized fuel particles from the center to the edge of the disc surface to supply the laboratory burner.

[0007] To solve this technical problem, the technical solution of the present invention is: a method for continuously supplying trace fuels to a laboratory reactor, comprising the following steps: S1. Micronized solid fuel particles are placed in a storage bin. A stirring rod and a spiral feeder are sequentially arranged in the storage bin from top to bottom. The spiral feeder is located in a pipe connected to the lower end of the storage bin. The pipe corresponds to the center of a rotating disc. The stirring rod and the spiral feeder are driven by a drive motor to rotate and discharge the coal powder in the storage bin to the center of the disc. At the same time, the storage bin is also equipped with a microwave heating unit to heat and dry the coal powder in the storage bin; Water molecules in the pulverized coal particles form steam under the action of microwave heating and separate from the micron particle solid fuel. As the micron particle solid fuel continues to tumble, the water vapor separates from the pulverized coal and moves upward to leave the storage bin. S2. The micron particle solid fuel pile at the center of the disk is evenly dispersed into a thin layer from the center of the disk to the circumference under the action of centrifugal force as the disk rotates, and then scraped into the inlet of the laboratory reactor by a scraper.

[0008] The scraper preferably delivers the micron particle solid fuel on the disc to the feed port at a rate of Q. ; in, is the effective feeding area; R is the radius of the disk; ρ is the bulk density of the material; k is the average stacking thickness of the material; L is the actual length of the scraper; n is the disc rotation speed; The effective working width of the scraper; .

[0009] The blanking amount Q of the present invention is introduced by As a correction factor, quantify the effect of centrifugal force on the material layer.

[0010] The present invention controls the length of the scraper and the inclination angle relative to the turntable in coordination with the bulk density and thickness of the material, thereby effectively and accurately controlling Q and obtaining an accurate and continuous trace fuel supply.

[0011] The preferred rate Q of feeding micronized solid fuel particles into the feed port is 0.5 g / min≤Q≤2 g / min. The present invention ensures material stability during the feeding process by synchronously controlling the particle size of the solid fuel particles and the degree of dryness in real time, thereby ensuring stable feeding under the combined action of the disc and scraper.

[0012] Preferably, the radius R of the disk is 30 mm, the disk speed n is 10 rpm to 180 rpm, and the speed V of the stirring rod and the spiral feeder in S1 is 0.36 rpm ≤ V ≤ 5.6 rpm. The rotation speed of the spiral feeder in the present invention is mainly to match the rotation speed of the disk and control the stability of Q.

[0013] Preferably, the micron-sized solid fuel in the storage bin in S1 is heated by microwaves to maintain a temperature within the bin of 95°C to 105°C. The present invention ensures effective evaporation of moisture by maintaining a stable drying temperature. While maintaining a uniform particle size, the viscosity of the fuel particles is also effectively controlled, thereby accommodating the dispersion of the disc and the coordination of the scraper and disc, achieving a continuous supply of trace fuel.

[0014] Preferably, the top of the storage bin is covered with a cover plate; The upper portion of the storage bin is also provided with an air outlet for discharging water vapor.

[0015] Preferably, the angle between the scraper and the disc is θ, wherein 30°≤θ≤60°.

[0016] Preferably the inner diameter of the tube is 1 cm.

[0017] Preferably, the storage silo is made of polypropylene.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are: The present invention controls the dryness of the fuel particles and maintains the dispersion of the material through stirring and centrifugal force during the transportation process. By increasing the gap between the particles, the particles overcome the mutual adhesion and aggregation into larger agglomerates due to the electrostatic force and van der Waals force between the particles, thereby reducing the agglomeration of the fuel. The relative fixed position between the scraper and the disc and the fixed area swept are effectively guaranteed to ensure the stability of continuous feeding. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of the continuous feeding device implemented in the present invention; Figure 2 This is a schematic diagram of the structure of the disc and scraper cooperating to feed materials in the present invention; Figure 3 The effect of microwave conditions on the stability of the present invention at a feeding rate of 1 g / min is compared.

[0020] Reference numerals:

[0021] Storage bin 1; pipeline 2; drive motor 3; disc 4; magnetic levitation motor 5; stirring rod 6; spiral feeding piece 7; scraper 8; discharge port 9; microwave heating unit 10; exhaust hole 11; cover plate 12. DETAILED DESCRIPTION

[0022] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0023] Example 1

[0024] This embodiment discloses a method for continuously supplying trace fuel to a laboratory reactor. The device for implementing the method is as follows: Figure 1 and Figure 2 As shown, the following steps are included: S1. Micronized solid fuel particles are placed in a storage bin 1. A stirring rod 6 and a spiral feeder 7 are sequentially arranged in the storage bin 1 from top to bottom. The spiral feeder 7 is located in a pipe 2 connected to the lower end of the storage bin 1. The pipe 2 corresponds to the center of a rotating disc 4. The stirring rod 6 and the spiral feeder 7 are driven by a drive motor 3 to rotate and discharge the coal powder in the storage bin 1 to the center of the disc. At the same time, the storage bin 1 is also provided with a microwave heating unit 10 to heat and dry the coal powder in the storage bin 1; Water molecules in the pulverized coal particles form steam under the action of microwave heating and separate from the micron particle solid fuel. As the micron particle solid fuel continues to tumble, the water vapor separates from the pulverized coal and moves upward to leave the storage bin. S2. The micron particle solid fuel pile at the center of the disk 4 is evenly dispersed into a thin layer from the center of the disk 4 toward the circumference under the action of centrifugal force as the disk 4 rotates, and then scraped into the inlet of the laboratory reactor by the scraper 8.

[0025] In this embodiment, the speed at which the scraper delivers the micron-sized solid fuel on the disc to the feed port is Q. ; in, is the effective feeding area; R is the radius of the disk, in mm; ρ is the bulk density of the material, g / cm 3 ; k is the average accumulation thickness of materials within the scraper range, mm; L is the actual length of the scraper, mm; n is the disc speed, rpm; L⋅sinθ is the effective width of the scraper; .

[0026] The blanking amount Q of the present invention is introduced by As a correction factor, the influence of centrifugal force on the material layer is quantified; the above process parameters are shown in Table 1.

[0027] The present invention controls the length of the scraper and the inclination angle relative to the turntable in coordination with the bulk density and thickness of the material, thereby effectively and accurately controlling Q and obtaining an accurate and continuous trace fuel supply.

[0028] The rate Q of feeding micron particle solid fuel to the feed port in this embodiment is shown in Table 1. The present invention ensures the stability of the material during the feeding process by synchronously controlling the particle size of the solid fuel particles and the degree of dryness in real time, thereby stabilizing the discharge of the material under the combined action of the disc and the scraper.

[0029] In this embodiment, the radius R of the disk is 30 mm, and the rotation speed n of the disk, the rotation speed V of the stirring rod and the spiral blanking member in S1 are shown in Table 1. The rotation speed of the spiral blanking member of the present invention is mainly to match the rotation speed of the disk and control the stability of Q.

[0030] In this embodiment, the micron-sized solid fuel in the storage bin S1 is heated by microwaves to maintain a temperature of 100°C, and the moisture content of the micron-sized solid fuel is less than 0.5%. This invention ensures effective evaporation of moisture by maintaining a stable drying temperature. While maintaining a uniform particle size, the viscosity of the fuel particles is also effectively controlled, thereby facilitating the dispersion of the disc and the coordination of the scraper and disc, achieving a continuous supply of trace fuel.

[0031] The top of the storage bin in this embodiment is covered with a cover plate; the upper portion of the storage bin is also provided with an air outlet for discharging water vapor.

[0032] The inner diameter of the pipe in this embodiment is 1 cm.

[0033] The storage bin is made of polypropylene. The storage bin made of polypropylene used in the present invention is suitable for microwave heating.

[0034] The entire fixture is screwed onto the tube furnace or above the desired feed port. The feed port and storage bin are placed on the fixture, and the feeder discharge pipe is secured with a fixing bracket. The drive motor is fixed above the storage bin via an L-shaped fixing bracket. The spiral feeder is inserted into the discharge pipe and adjusted to the desired height.

[0035] During operation, pulverized coal is first added to storage silo 1. The power is then turned on. The drive motor 3 for screw 2 and the magnetic levitation motor 5 for rotating disc 4 can be controlled separately. Silo 1 is made of highly transparent polypropylene, allowing microwaves to pass through. Before the actual feeding process, the fuel particles in silo 1 are heated with microwaves to remove moisture from the sample. A temperature sensor is installed within silo 1, providing real-time feedback on temperature changes within the silo. This feedback is then fed back to microwave heating unit 10. Microwave heating unit 10 adjusts the heating power in real time based on the temperature signal from the thermocouple, maintaining a temperature of approximately 100°C within silo 1 to dry the fuel. Silo 1 is equipped with a vent 11, through which water vapor from the drying process escapes. During the actual feeding process, the drive motor 3 for stirring rod 6 and the magnetic levitation motor 5 for spiral feeder 7 are controlled via stepless speed regulation, causing disc 4 and spiral feeder 7 to rotate at a constant rate. The upper portion of the spiral feeder is equipped with a stirring rod 6, which stirs the pulverized coal within silo 1. A thermocouple is mounted at the end of stirring rod 6 to monitor the material temperature in the silo in real time. The pulverized coal in the storage silo is continuously stirred during the rotation and drying process to prevent lumping or sticking. A spiral feeder 7 continuously transports and guides the pulverized coal downward, delivering it to the center of disc 4 via pipe 2. To mitigate the continuous and unstable nature of the spiral feeder, the disc below the feeder is driven by a magnetic levitation motor. Active magnetic levitation control utilizes real-time feedback to adjust the electromagnetic force, precisely controlling the rotor speed. This precise rotor speed control allows for precise control of the feeder's feeding speed. Electromagnetic levitation of the rotor completely eliminates friction losses in the mechanical bearings, making it suitable for long-term operation. The rotation of the disc causes the pulverized coal falling into the center of the disc to be subjected to centrifugal force. From there, the pulverized coal continuously moves toward the edge, where it is eventually scraped by scrapers 8 at the edge into the discharge port 9. This ensures continuous and stable feeding, ensuring even pulverized coal falls into the experimental reactor.

[0036] Micro-feeding equipment currently includes screw type, ejector type and roller type. The lower limit of the feeding amount of these micro-feeders is relatively high, usually measured in kg / h. For lower feeding amounts, problems such as low feeder speed, powder sticking and discontinuous feeding usually occur. Existing feeding devices are difficult to meet the lower feeding rates required by small laboratory reactors, and the feeding amount of grams per hour is a technical difficulty in the industry. In laboratory research systems, especially experimental devices using sedimentation furnaces and fluidized beds, quantitative, stable and accurate feeding is often required to ensure the smooth progress of the experiment. In order to obtain the combustion characteristics of coal powder, biomass or a mixture of coal powder and biomass, it is necessary to ensure continuous and stable powder feeding first, to meet the sustainable progress of the experiment and the repeatability of the rules; more importantly, to ensure micro-powder feeding, so as to achieve a fully stable reaction of the sample in the reactor. The continuous micro-feeding of the present invention is achieved by accurately controlling the rotor speed of the magnetic levitation motor and controlling the rotation speed of the spiral tube of the drive motor to achieve precise control of sample transportation and control of a wide range of feeding speeds. Synchronous stirring in a pipe connected to the lower end of the storage bin ensures uniformity and continuity of the pulverized coal within the bin, preventing uneven feeding. Microwave heating is used to dry the sample before delivery, ultimately delivering the pulverized coal to the discharge port in a trace and stable manner, completing the feeding required for the experiment.

[0037] Example 2

[0038] The main differences between this embodiment and embodiment 1 are shown in Table 1.

[0039] Example 3

[0040] The main differences between this embodiment and embodiment 1 are shown in Table 1.

[0041] Comparative Example The main difference between this comparative example and Example 1 is that the storage bin is not equipped with microwave drying.

[0042] Table 1 Parameters of solid fuel particles in Examples 1 to 3 and the comparative example

[0043] Table 2 Parameter control and feeding rate of the disc and scraper of Examples 1 to 3 and the comparative example

[0044] Figure 3 The changes in the proportion of the mass of the first loading and the 20th loading of the sample in Example 1 and the comparative example are shown. Figure 3As can be seen, the present invention effectively controls the fluidity of fuel powder particles through drying. Combined with the centrifugal action of the fuel powder on the rotating disk surface, it stabilizes the thickness of the scraper coverage area and thus the fuel supply. The most common phenomenon of deteriorating flow is unstable feeding caused by the adhesion of fuel particles. Severe particle agglomeration can even lead to pipeline blockage. The factors affecting powder feed flow are complex, and currently the primary focus is on the physical properties of the powder itself. It is believed that pulverized coal flow is driven by multiple factors, including particle size, shape, surface structure, and moisture content. Generally, as pulverized coal particle size decreases, it exhibits increasing viscosity, and adhesion and agglomeration become increasingly severe. The present invention employs a feed rate of 0.5g / min to 2g / min. To prevent agglomeration and clumping within the storage bin, mechanical dispersion is employed, with spiral stirring and microwave drying technology used within the bin to ensure that the sample within the bin is constantly dry. The present invention utilizes a low feed rate to minimize feed fluctuations caused by uneven distribution of pulverized coal. This feed method minimizes the viscous interaction between the spiral and the pulverized coal, improving feed continuity. The pulverized coal is pushed out of the discharge port by the scraper feeder and then carried into the furnace by the gas.

[0045] The feeding speed of the present invention is determined by the rotation speed of the screw and the disc and the angle of the scraper. The spiral unloading part is connected to a stepper motor, and the motor speed can be accurately adjusted by a stepless speed regulator. The stepper motor is 90-1400rpm and equipped with a reducer 1:250, so that the screw speed range is 0.36-5.6rpm. The disc diameter is 60mm, and the rotation speed control range is 10rpm-180rpm. Controlling the speed of the disc can control the speed of the material at the center of the disc to evenly disperse the surface of the disc, and finally it is scraped into the discharge port by the scraper. The angle of the scraper is set between 30-60 degrees. The change in the angle of the scraper has little effect on the feeding speed. Except for slight changes in the speed requirements, the scraper angle is generally fixed at 45 degrees.

Claims

1. A method for continuously supplying trace fuel to a laboratory reactor, characterized in that: The following steps are involved: S1. Micronized solid fuel particles are placed in a storage bin. A stirring rod and a spiral feeder are sequentially arranged in the storage bin from top to bottom. The spiral feeder is located in a pipe connected to the lower end of the storage bin. The pipe corresponds to the center of a rotating disc. The stirring rod and the spiral feeder are driven by a drive motor to rotate and discharge the coal powder in the storage bin to the center of the disc. At the same time, the storage bin is also equipped with a microwave heating unit to heat and dry the coal powder in the storage bin; Water molecules in the pulverized coal particles form steam under the action of microwave heating and separate from the micron particle solid fuel. As the micron particle solid fuel continues to tumble, the water vapor separates from the pulverized coal and moves upward to leave the storage bin. S2. The micron particle solid fuel pile at the center of the disk is evenly dispersed into a thin layer from the center of the disk to the circumference under the action of centrifugal force as the disk rotates, and then scraped into the inlet of the laboratory reactor by a scraper.

2. The method for continuous supply of trace fuel according to claim 1, characterized in that: The scraper delivers the micron particle solid fuel on the disc to the feed port at a rate of Q. ； in, is the effective feeding area; R is the radius of the disk; ρ is the bulk density of the material; k is the average stacking thickness of the material; L is the actual length of the scraper; n is the disc rotation speed; The effective working width of the scraper; 。 3. The method for continuous supply of trace fuel according to claim 1, characterized in that: The rate Q at which the micron particle solid fuel is fed into the feed port is 0.5 g / min≤Q≤2 g / min.

4. The method for continuous supply of trace fuel according to claim 3, characterized in that: The radius R of the disk is 30 mm, the rotation speed n of the disk is 10 rpm to 180 rpm, and the rotation speed V of the stirring rod and the spiral feeding piece in S1 is 0.36 rpm≤V≤5.6 rpm.

5. The method for continuous supply of trace fuel according to claim 1, characterized in that: The micron particle solid fuel in the storage bin in S1 is heated by microwaves to maintain the temperature in the storage bin at 95°C to 105°C.

6. The method for continuous supply of trace fuel according to claim 1, characterized in that: The top of the storage bin is covered with a cover plate; The upper portion of the storage bin is also provided with an air outlet for discharging water vapor.

7. The method for continuously supplying trace fuel according to claim 1, characterized in that: The angle between the scraper and the disc is θ, wherein 30°≤θ≤60°.

8. The method for continuously supplying trace fuel according to claim 1, characterized in that: The inner diameter of the pipe is 1 cm.

9. The method for continuously supplying trace fuel according to claim 1, characterized in that: The storage bin is made of polypropylene.

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