Device and method for preventing ash blockage by using heat pipe

Abstract

The invention discloses a device and a method for preventing ash blockage by using a heat pipe. The device comprises an ash hopper, an air preheating type spiral conveyer and an ash conveying pipeline which are connected in sequence, and an air compressor is connected with the ash conveying pipeline through a compressed air pipeline; the air preheating type spiral conveyor comprises a conveyor shell and a heat pipe type rotating shaft. Spiral conveying blades are arranged at one end of the heat pipe type rotating shaft, and air preheating pieces are arranged at the other end; the heat pipe type rotating shaft is internally vacuum and is provided with a low-boiling-point working medium; an air preheating bin is arranged on the compressed air pipeline, and the air preheating pieces are located in the air preheating bin. According to the invention, redundant heat in the fly ash is utilized to heat the compressed air, so that the energy consumption for repeatedly heating the compressed air and the fly ash in the system can be reduced under the condition that the overall heat capacity in the system is not changed; fly ash is stirred, loosened and prevented from hardening in the mechanical conveying process, so that the fly ash is more beneficial to pneumatic conveying.

Description

Technical Field

[0001] The invention relates to the technical field of coal-fired boilers, and in particular to an anti-ash blocking device and method utilizing a heat pipe. Background Art

[0002] Thermal power units occupy an important position in the electric power industry. Fly ash is a fine solid particle captured from the flue gas generated in the coal combustion process. Fly ash is composed of fine granular fly ash, which is glassy, ​​mainly spherical, with large voids and is not dense. It is loose and porous and has high adsorption activity.

[0003] There are three main ways to collect and transport fly ash generated by coal-fired units in thermal power plants: micro-positive pressure pneumatic conveying, positive pressure pneumatic conveying, and negative pressure pneumatic conveying. Through practical application, it is found that although positive pressure pneumatic conveying has obvious advantages, in pneumatic conveying systems, the gas source is usually generated by an air compressor or an air compressor, and enters the pneumatic conveying system after drying and filtration. However, it is difficult to avoid impurities in the gas source generated by this method, resulting in a high oil and water content in the gas source, which in turn causes the pneumatic conveying system to become blocked and agglomerated, and in severe cases, even the ash bin is blocked.

[0004] For pneumatic conveying systems, in order to reduce the impact of oil and water in the gas source on fly ash, the commonly used method is to use electric heating or steam heating in the ash hopper or silo pump to increase the temperature of the fly ash and reduce the humidity of the fly ash itself. However, this method can only initially alleviate the blockage of the ash conveying system. For pneumatic conveying situations where the gas source contains a large amount of oil and water and the conveying line is long, it is still easy to cause blockage of the ash conveying system.

[0005] For example, patent publication number CN117401448A "A pneumatic ash conveying device and method for preventing blockage" heats and dries the material in the ash conveying cylinder through a heating pipe arranged in the ash conveying cylinder to reduce the stickiness of the material, thereby effectively preventing the material from adhering to the inner wall of the ash conveying pipe; the above patent mainly performs secondary heating of fly ash by an external heater, which increases the power consumption of the system. At the same time, the ash conveying pipe is cleaned by blowing through the nozzle, which is prone to nozzle blockage and increases the gas consumption of the system.

[0006] For example, patent announcement number CN220334101U "A dense phase pneumatic conveying system" mainly realizes the transportation of powdered materials or small particle materials in long-distance pneumatic conveying pipelines through the pressurization means of a preset external air source, a control air circuit and a diaphragm pump combination. However, if the oil and water content in the air source is too high, it is still possible to cause the material in the conveying pipeline to become compacted, and the dust blockage of the pneumatic conveying system cannot be avoided.

[0007] For example, patent announcement number CN214891305U "A high-temperature fly ash waste heat recovery device" exchanges heat with the heat exchange medium in the tubular heat exchanger in the heat exchange bin. Based on the contact heat exchange method, it fully utilizes the waste heat of the fly ash in the economizer ash hopper; although the above patent discloses the use of a heat exchanger to exchange heat on fly ash, it does not disclose the technical inspiration of how to use the waste heat to dry the oil and water in the gas source.

[0008] Therefore, a method is needed to reduce the oil-water content in the compressed air without increasing power consumption and prevent the ash conveying pipeline from being blocked. Summary of the invention

[0009] The object of the present invention is to provide a device and method for preventing dust blockage using a heat pipe to solve the problems raised in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] An anti-ash blocking device using a heat pipe comprises an ash hopper, an air preheating screw conveyor and an ash conveying pipeline which are connected in sequence, and an air compressor is connected to the ash conveying pipeline through a compressed air pipeline;

[0012] The air preheating screw conveyor comprises a conveyor housing, a heat pipe shaft rotatably connected to the conveyor housing, one end of the heat pipe shaft is provided with a spiral conveying blade located in the conveyor housing, the other end of the heat pipe shaft is provided with an air preheating plate, the interior of the heat pipe shaft is vacuum and provided with a low boiling point working medium;

[0013] An air preheating bin is arranged on the compressed air pipeline, and the air preheating plate is located inside the corresponding air preheating bin.

[0014] Preferably, the low boiling point working fluid is ethanol or propane or ammonia or Freon.

[0015] Preferably, a silo pump is connected between the ash hopper and the air preheating screw conveyor; and a gate valve is provided between the silo pump and the ash hopper.

[0016] Preferably, the output end of the ash conveying pipeline is connected to an ash bin.

[0017] Preferably, an ash conveying check valve is provided between the air preheating screw conveyor and the ash conveying pipeline.

[0018] Preferably, the air preheating screw conveyor further comprises a variable frequency drive motor, and the variable frequency drive motor is transmission-connected to the heat pipe type rotating shaft via a transmission gear set.

[0019] Preferably, the spiral conveying blades are provided with uniformly distributed disturbance angles.

[0020] Preferably, the disturbance angle extends from the outer side wall of the spiral conveying blade along the material conveying direction and the pipe diameter gradually decreases.

[0021] Preferably, the air preheating fins are spiral fins.

[0022] A method for using a heat pipe anti-dust blocking device comprises the following steps:

[0023] When the ash conveying starts, the fly ash in the ash hopper enters the air preheating conveyor through the silo pump;

[0024] According to the change of fly ash temperature, the frequency of the variable frequency drive motor is adjusted accordingly to adjust the rotation speed of the heat pipe shaft, thereby adjusting the heat exchange time of the fly ash;

[0025] The fly ash enters the ash conveying pipeline under the conveyance of the spiral conveying blades, and the heat of the fly ash is transferred to the air preheating bin through the heat pipe rotating shaft to heat the compressed air;

[0026] The fly ash in the ash conveying pipeline is transported to the ash storage by using the heated compressed air.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Compared with the traditional pneumatic conveying system, the present invention utilizes the excess heat in the fly ash to heat the compressed air, and can reduce the repeated heating energy consumption of the compressed air and fly ash in the system without changing the overall heat capacity in the system, thereby ultimately reducing the energy consumption of the system;

[0029] Firstly, the fly ash is mechanically conveyed and then pneumatically conveyed. During the mechanical conveying process, the fly ash is stirred, loosened and prevented from compacting, making the fly ash after mechanical conveying more conducive to pneumatic conveying, further alleviating the fly ash compaction phenomenon that may occur during the pneumatic conveying process;

[0030] According to the temperature characteristics of fly ash itself, the frequency of the variable frequency drive motor can be adjusted to reasonably utilize the heat without causing the fly ash temperature to be too low and thus causing premature hardening.

[0031] The present invention takes into account waste heat recovery and material drying and transportation, and realizes the drying and transportation of ash at the silo pump outlet without an external heat source. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0033] Figure 1 It is a schematic diagram of the structure of the present invention;

[0034] Figure 2 It is a three-dimensional schematic diagram of the air preheating screw conveyor of the present invention;

[0035] Figure 3 It is a cross-sectional view of the air preheating screw conveyor of the present invention;

[0036] Figure 4 for Figure 3 A magnified schematic diagram of local A.

[0037] The reference numerals in the figure are as follows:

[0038] 1. Ash hopper; 2. Gate valve; 3. Bin pump; 4. Air preheating screw conveyor; 5. Air compressor; 6. Compressed air pipeline; 7. Air preheating bin; 8. Ash conveying check valve; 9. Ash conveying pipeline; 10. Ash storage;

[0039] 41. Variable frequency drive motor; 42. Heat pipe shaft; 43. Spiral conveying blade; 44. Disturbance angle; 45. Transmission gear set; 46. Air preheating fin; 47. Conveyor housing; 48. Feed inlet. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0041] The present invention is mainly applicable to pneumatic ash conveying, especially positive pressure pneumatic ash conveying. The currently commonly used pneumatic conveying system mainly increases the temperature of fly ash by means of external electric heating or steam heating to prevent the fly ash from condensing and solidifying in the ash hopper or silo pump. At the same time, heating, drying and filtering are used on the air source side to purify the air source and reduce the oil and water content of the air source. This method is affected by the process, and both the fly ash and the air source are heated, so the energy utilization rate is low and the heating energy consumption is high.

[0042] Example:

[0043] A device and method for preventing dust blockage using a heat pipe, as shown in the attached Figure 1-4 As shown, the ash hopper 1, the silo pump 3, the air preheating screw conveyor 4, the ash conveying check valve 8, the ash conveying pipeline 9 and the ash silo 10 are connected in sequence; the ash conveying pipeline 9 has two input ports, one of which is connected to the output end of the air preheating screw conveyor 4, and the air compressor 5 is connected to the other input port of the ash conveying pipeline 9 through the compressed air pipeline 6;

[0044] The part of the compressed air pipeline 6 close to the air preheating screw conveyor 4 is set as an air preheating chamber 7.

[0045] The air preheating screw conveyor 4 comprises a variable frequency drive motor 41, a heat pipe shaft 42, a screw conveying blade 43, a disturbance angle 44, a gear transmission group 45, an air preheating blade 46 and a conveyor housing 47;

[0046] The conveyor housing 47 has a feed port 48 for connecting to the output end of the bin pump 3, wherein a spiral conveying blade 43 is fixed at one end of the heat pipe shaft 42, and the spiral conveying blade 43 is located inside the conveyor housing 47. The outer wall of the spiral conveying blade 43 is provided with a uniformly distributed disturbance angle 44 along its axial direction, and an air preheating plate 46 is fixed at the other end of the heat pipe shaft 42, and the air preheating plate 46 is relatively arranged inside the air preheating bin 7.

[0047] The interior of the heat pipe shaft 42 is in a vacuum state and is filled with a low-boiling-point working fluid; the low-boiling-point working fluid refers to a liquid that can evaporate at a relatively low temperature, and any one of ethanol, propane, ammonia, and Freon can be used; in the working state, since the temperature on the side of the spiral conveying blade 43 is higher than that on the side of the air preheating plate 46, the heat pipe shaft 42 realizes the heat pipe function; the low-boiling-point working fluid is a good heat conductor, which can transfer the heat on the side of the spiral conveying blade 43 to the area on the side of the air preheating plate 46.

[0048] Fly ash material transportation path:

[0049] The fly ash is first transferred and stored in the ash hopper 1. The ash hopper 1 has heating and heat preservation functions, so that the fly ash in the ash hopper 1 is kept consistent with the original smoke temperature, about 100-140°C (if there is a low-temperature economizer at the front end, it is 100-110°C; if there is no low-temperature economizer at the front end, it is 120°C-140°C, or even higher). When the ash conveying starts, the gate valve 2 opens, and the fly ash in the ash hopper 1 enters the silo pump 3 and enters the conveyor housing 47 through the feed port 48; driven by the variable frequency drive motor 41, the transmission gear set 45 rotates with the heat pipe shaft 42, and the spiral conveying blades 43 and air preheating blades 46 at both ends of the heat pipe shaft 42 rotate together with the heat pipe shaft 42.

[0050] The fly ash inside the conveyor housing 47 moves forward slowly as the spiral conveying blades 43 rotate. At the same time, the disturbance angle 44 on the surface of the spiral conveying blades 43 also continuously stirs and loosens the fly ash as the spiral conveying blades 43 rotate. This increases the looseness of the fly ash and prevents the fly ash from agglomerating in the conveyor housing 47. At the same time, the disturbance angle 44 can fully release the heat in the fly ash and strengthen the heat exchange effect of the heat pipe shaft 42, thereby ensuring that the compressed air in the air preheating bin 7 is effectively heated.

[0051] When the fly ash is fully loosened during transportation in the air preheating conveyor 4, it enters the ash conveying pipeline 9 through the ash conveying check valve 8 and is transported to the ash storage 10 by hot compressed air.

[0052] Heat transfer path:

[0053] The fly ash entering the air preheating conveyor 4 is basically consistent with the smoke temperature due to the heating and heat preservation effect of the ash hopper 1, which is about 100-140°C (if there is a low-temperature economizer at the front end, it is 100-110°C; if there is no low-temperature economizer at the front end, it is 120-140°C, or even higher). At 30-80°C, the fly ash will be hardened. Therefore, as long as the temperature of the fly ash in the ash conveying system is higher than 80°C, the hardening of the fly ash can be prevented, and the excess heat can be effectively utilized. When the high-temperature fly ash moves forward in the air preheating conveyor 4, the heat of the fly ash is transferred to the air preheating bin 7 through the heat pipe shaft 42. The cold compressed air coming out of the air compressor 5 enters the air preheating bin 7 along the compressed air pipeline 6, and the cold compressed air is heated into hot compressed air in the air preheating bin 7, reducing the oil and water content in the compressed air and improving the pneumatic conveying efficiency.

[0054] When the temperature of fly ash changes, the frequency of the variable frequency drive motor 41 can be adjusted to adjust the rotation speed of the heat pipe type shaft 42, and then the heat exchange time of the fly ash in the air preheating screw conveyor 4 can be adjusted to transfer more heat to the air preheating bin 7. This ensures that the heat in the fly ash is fully utilized and prevents the fly ash from being hardened due to the low temperature of the fly ash.

[0055] like Figure 4 As shown, the disturbance angle 44 extends in a direction away from the air preheating plate 46 (consistent with the forward direction of the fly ash in the air preheating screw conveyor 4) and the outer diameter gradually decreases. The disturbance angle 44 mainly takes into account the forward conveying and stirring of the material. In order to facilitate the material conveying, it is normally required to be ±45° with the vertical plane of the rotating shaft.

[0056] like Figure 2 , 3As shown, the air preheating fins 46 use a large number of dense spiral fins to improve the heat transfer efficiency, ensuring that the heat absorbed by the heat pipe shaft from the fly ash heats the cold compressed air to raise the temperature by 3 to 5°C.

[0057] In order to ensure that the fin types at both ends of the heat pipe shaft 42 are consistent, it can be ensured that there is no heating dead zone in the air preheating chamber 7; the spiral fins are not easy to accumulate dust, which reduces the heat transfer resistance; the denser the spiral fins, the larger the heat exchange area, and the better the heating effect in the air preheating chamber 7.

[0058] The rotation of the air preheating fins 46 can also help the cold compressed air to contact the surface of the air preheating fins 46 more evenly, thereby improving the heat exchange efficiency.

[0059] The heat pipe type rotating shaft 42 is relatively located at the center of the conveyor housing 47, and the center temperature of the fly ash piled together is the highest. Therefore, this layout enables the heat pipe type rotating shaft 42 to absorb the heat of the fly ash more effectively.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0061] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An anti-ash blocking device using a heat pipe, comprising an ash hopper (1), an air preheating screw conveyor (4) and an ash conveying pipeline (9) connected in sequence, an air compressor (5) connected to the ash conveying pipeline (9) through a compressed air pipeline (6), characterized in that: The air preheating screw conveyor (4) comprises a conveyor housing (47), a heat pipe type rotating shaft (42) rotatably connected to the conveyor housing (47), one end of the heat pipe type rotating shaft (42) is provided with a spiral conveying blade (43) located in the conveyor housing (47), and the other end of the heat pipe type rotating shaft (42) is provided with an air preheating plate (46), and the interior of the heat pipe type rotating shaft (42) is vacuum and provided with a low boiling point working medium; An air preheating chamber (7) is provided on the compressed air pipeline (6), and the air preheating plate (46) is located inside the corresponding air preheating chamber (7).

2. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: The low boiling point working fluid is ethanol or propane or ammonia or freon.

3. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: A silo pump (3) is connected between the ash hopper (1) and the air preheating screw conveyor (4); and a gate valve (2) is provided between the silo pump (3) and the ash hopper (1).

4. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: The output end of the ash conveying pipeline (9) is connected to an ash storage (10).

5. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: An ash conveying check valve (8) is provided between the air preheating screw conveyor (4) and the ash conveying pipeline (9).

6. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: The air preheating screw conveyor (4) further comprises a variable frequency drive motor (41), and the variable frequency drive motor (41) is transmission-connected to the heat pipe rotating shaft (42) via a transmission gear set (45).

7. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: The spiral conveying blade (43) is provided with uniformly distributed disturbance angles (44).

8. The dust blocking prevention device using a heat pipe according to claim 7, characterized in that: The disturbance angle (44) extends from the outer side wall of the spiral conveying blade (43) along the material conveying direction and the pipe diameter gradually decreases.

9. The dust blocking prevention device using a heat pipe according to claim 1, characterized in that: The air preheating fins (46) are spiral fins.

10. A method for preventing dust blockage using a heat pipe according to any one of claims 1 to 9, characterized in that: The following steps are involved: When the ash conveying starts, the fly ash in the ash hopper (1) enters the air preheating conveyor (4) through the silo pump (3); According to the change of fly ash temperature, the frequency of the variable frequency drive motor (41) is correspondingly adjusted to adjust the rotation speed of the heat pipe type rotating shaft (42), thereby adjusting the heat exchange time of the fly ash; The fly ash enters the ash conveying pipeline (9) under the conveyance of the spiral conveying blades (43), and the heat of the fly ash is transferred to the air preheating chamber (7) through the heat pipe rotating shaft (42) to heat the compressed air; The fly ash in the ash conveying pipeline (9) is conveyed to the ash storage (10) by utilizing the heated compressed air.

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