Reflux electromagnetic heating device and air-powder mixed preheating meet the boiler stable combustion system

Abstract

The present invention relates to a reflux electromagnetic heating device and an air-powder mixing preheating system that meets the requirements of boiler stable combustion. The air-powder mixing preheating system that meets the requirements of boiler stable combustion includes an air-powder mixer, a heat exchanger, a reflux electromagnetic heating device, and a boiler. The air inlet and medium inlet of the air-powder mixer are respectively connected to a fan and a pulverized coal bin. The outlet of the air-powder mixer, the tube-side inlet and outlet of the heat exchanger, the inlet and outlet of the heating channel, and the burner of the boiler are sequentially connected through pipelines. The shell-side inlet of the heat exchanger is connected to the flue of the boiler through a flue gas circulation pipeline. A flue gas circulation fan is provided on the flue gas circulation pipeline. A metal powder feeding pipeline is connected to the pipeline between the tube-side outlet of the heat exchanger and the inlet of the heating channel. Advantages: It can effectively heat the air-powder before entering the boiler burner. The use of electromagnetic heating avoids open flames and reduces safety hazards. The addition of metal powder better meets the requirements of electromagnetic heating and improves heating efficiency, so that the entire system can ensure good combustion in the boiler under different operating loads.

Description

Technical Field

[0001] The present invention relates to the field of thermal power generation, and in particular to a reflux electromagnetic heating device and an air-powder mixed preheating system for boiler stable combustion. Background Art

[0002] Renewable energy sources like solar and wind have experienced rapid growth in recent years. However, due to significant seasonal fluctuations, grid-connected renewable energy generation faces significant pressure to regulate peak loads. Thermal power generation, a common method for peak regulation, poses a greater challenge to its flexibility. This requires boilers to achieve high efficiency and stability under varying loads (especially at lower operating loads, where stable combustion is particularly problematic). Combustion issues on the boiler side are the primary concern, and achieving stable combustion is a key issue. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a reflux electromagnetic heating device and an air-powder mixed preheating device to meet the requirements of a boiler stable combustion system, thereby effectively overcoming the defects of the prior art.

[0004] The technical solution of the present invention to solve the above technical problems is as follows:

[0005] A reflux electromagnetic heating device includes a tubular heating channel, which is a magnetic metal component with one end as an inlet and the other end as an outlet. An electromagnetic coil is wound around the surface of the heating channel, and a turbulent structure is provided in the heating channel for obstructing the airflow and causing part of the airflow to reflux.

[0006] On the basis of the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the above-mentioned spoiler structure includes a spoiler blunt body, which is installed inside the above-mentioned heating channel through a bracket. The above-mentioned spoiler blunt body is a conical component with a smooth surface, which is arranged along the long axis direction of the above-mentioned heating channel, and the cone tail end of the above-mentioned conical component faces the interface of the above-mentioned heating channel.

[0008] The above-mentioned turbulent bodies are provided in plurality and are distributed at intervals along the long axis direction of the above-mentioned heating channel.

[0009] The above-mentioned heating channel includes multiple axially connected expansion sections and narrowing sections, and the above-mentioned expansion sections are distributed one-to-one between two adjacent narrowing sections. The cross-sectional area of ​​the above-mentioned expansion section is larger than the cross-sectional area of ​​the above-mentioned narrowing section. The multiple above-mentioned flow-turbine blunt bodies are respectively installed one-to-one at the connection between the above-mentioned narrowing section and the adjacent expansion section.

[0010] The above-mentioned spoiler structure also includes a return air hood, which is a tube shell structure with one end open. It is fixed to a position near the outlet inside the above-mentioned heating channel through a bracket, and the open end of the above-mentioned return air hood faces the inlet of the above-mentioned heating channel.

[0011] The beneficial effects are: the structural design is simple and reasonable, the heating channel and the interior are heated by the principle of electromagnetic induction, and the fluid entering the heating channel is effectively heated. At the same time, the turbulent structure can form a reflux zone in the heating channel, prompting part of the fluid entering the heating channel to reflux, increasing the disturbance of the fluid and the residence time of the fluid in the heating channel, thereby improving the heating effect.

[0012] A system for preheating an air-powder mixture to meet the requirements of stable combustion of a boiler is also provided, which includes an air-powder mixer, a heat exchanger, a reflux electromagnetic heating device and a boiler. The air inlet and the medium inlet of the air-powder mixer are respectively connected to the fan and the pulverized coal bin. The outlet of the air-powder mixer, the tube-side inlet and tube-side outlet of the heat exchanger, the inlet and outlet of the heating channel, and the burner of the boiler are connected in sequence through pipelines. The shell-side inlet of the heat exchanger is connected to the flue of the boiler through a flue gas circulation pipeline. A flue gas circulation fan is connected to the flue gas circulation pipeline. A feeding pipeline for feeding magnetic metal powder is connected to the pipeline between the tube-side outlet of the heat exchanger and the inlet of the heating channel.

[0013] On the basis of the above technical solution, the present invention can also be improved as follows.

[0014] Furthermore, a temperature measuring device is connected to the outlet of the heating channel.

[0015] Furthermore, a return line is connected in parallel between the inlet and outlet of the heating channel.

[0016] Furthermore, a flue gas denitrification and dust removal system is provided on the above-mentioned flue gas circulation pipeline.

[0017] Furthermore, the magnetic metal powder includes one or more ferromagnetic materials such as aluminum, iron, nickel, cobalt, and stainless steel.

[0018] The beneficial effects of the present invention are: it can effectively heat the air powder before entering the boiler burner, use electromagnetic heating to avoid open flames and reduce safety hazards, and at the same time the addition of metal powder can better meet the requirements of electromagnetic heating, improve heating efficiency, shorten preheating time, and further enhance the heating effect by combining with the turbulent structure design in the heating device. In addition, the use of flue gas recirculation can make full use of the flue gas heat, and the whole system can further regulate the temperature to meet the stable combustion requirements of the boiler. The entire system can ensure good combustion in the boiler under different operating loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a structural schematic diagram of the reflux electromagnetic heating device of the present invention;

[0020] Figure 2 It is a schematic structural diagram of the electromagnetic coil wound outside the heating channel in the reflow electromagnetic heating device of the present invention;

[0021] Figure 3 This is a structural block diagram of the air-powder mixed preheating system for boiler stable combustion according to the present invention.

[0022] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0023] 1. Heating channel; 2. Electromagnetic coil; 3. Flow-turbulating structure; 11. Expanding section; 12. Narrowing section; 13. Insulation layer; 31. Flow-turbulating blunt body; 32. Return air hood; 51. Air-powder mixer; 52. Heat exchanger; 53. Reflux electromagnetic heating device; 54. Boiler; 55. Fan; 56. Pulverized coal silo; 57. Flue gas circulation fan; 58. Delivery pipeline; 59. Temperature measuring device; 60. Return pipeline; 61. Flue gas denitrification and dust removal system; 62. Flow regulating device. DETAILED DESCRIPTION

[0024] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0025] Example 1

[0026] like Figure 1 and 2 As shown, the reflux electromagnetic heating device of this embodiment includes a tubular heating channel 1, which is a magnetic metal component with one end as an inlet and the other end as an outlet. An electromagnetic coil 2 is wound around the surface of the heating channel 1, and a turbulent structure 3 is provided in the heating channel 1 for obstructing the airflow and causing part of the airflow to reflux.

[0027] Here’s how it works:

[0028] When the air-powder mixture enters the inlet of the heating channel 1 and encounters the disturbance structure 3, a recirculation zone will be formed at the disturbance structure 3 (the area in front of the disturbance structure 3 corresponding to the direction of fluid flow), which increases the disturbance and residence time, resulting in a better heating effect. In a thermal power plant, the wind speed of the supply air usually reaches tens of meters per second, so the residence time of the air-powder mixture in the heating channel 1 is limited. Therefore, the disturbance structure 3 can make the fluid stay in the heating channel 1 for as long as possible, that is, extend the heating time in the heating channel 1 and improve the heating effect. In this embodiment, heating is performed using the principle of electromagnetic induction. Specifically, when the electromagnetic coil 2 is energized, an alternating magnetic field is generated. The heating channel 1 made of magnetic metal is in the magnetic field, and the surface cuts the alternating magnetic lines of force, thereby generating an alternating current (eddy current) on the heating channel 1. The eddy current causes the carriers in the metal material to move irregularly at high speed. The carriers collide and rub with each other to generate heat energy to heat the fluid in the heating channel 1.

[0029] As a preferred embodiment, the above-mentioned spoiler structure 3 includes a spoiler blunt body 31, which is installed inside the above-mentioned heating channel 1 through a bracket. The above-mentioned spoiler blunt body 31 is a conical component with a smooth surface, which is arranged along the long axis direction of the above-mentioned heating channel 1, and the cone tail end of the above-mentioned conical component faces the interface of the above-mentioned heating channel 1.

[0030] In the above embodiment, when the fluid flows from the inlet to the outlet in the heating channel 1 , it encounters resistance at the tapered tail end of the turbulent body 31 and flows back, forming a turbulent recirculation zone, thereby increasing the residence time of the fluid in the heating channel 1 .

[0031] Of course, in order to facilitate the fixation of the spoiler 31 during actual use, a short column is set at the tapered tail end of the spoiler 31, and the short column is installed on the inner wall of the heating channel 1 through a bracket. It should be emphasized that the size of the short column is only used to fix the spoiler 31. A thinner rod-shaped component can be used to avoid it affecting the flow of the fluid in the heating channel 1.

[0032] As a preferred embodiment, a plurality of the turbulent bodies 31 are provided and are distributed at intervals along the long axis direction of the heating channel 1 .

[0033] In the above embodiment, the design of multiple flow-turbulating bluff bodies 31 can cause the fluid to form backflow in multiple sections along the length of the tube in the heating channel 1, thereby increasing the heating time of the fluid in the heating channel 1 as much as possible.

[0034] As a preferred embodiment, the above-mentioned heating channel 1 includes multiple axially connected expansion sections 11 and narrowing sections 12, and the above-mentioned expansion sections 11 are distributed one-to-one between two adjacent narrowing sections 12. The cross-sectional area of ​​the above-mentioned expansion section 11 is larger than the cross-sectional area of ​​the above-mentioned narrowing section 12, and multiple above-mentioned flow-turbulating blunt bodies 31 are respectively installed one-to-one at the connection between the above-mentioned narrowing section 12 and the adjacent expansion section 11.

[0035] In the above embodiment, the conical tail of the flow-disturbing blunt body 31 is located in the narrowing section 12, and the tip of the cone extends straightly into the interior of the adjacent expansion section 11 at the rear. Such a design is conducive to maintaining the flow direction of the fluid in the heating channel 1. At the same time, the expansion section 11 and the narrowing section 12 adopt a "front and back" structure in order to cooperate with the flow-disturbing structure, so that the reflux effect is better and more obvious.

[0036] As a preferred embodiment, the above-mentioned spoiler structure 3 also includes a return air hood 32, which is a tube shell structure with one end open. It is fixed to a position near the outlet inside the above-mentioned heating channel 1 through a bracket, and the open end of the above-mentioned return air hood 32 faces the inlet of the above-mentioned heating channel 1.

[0037] In the above embodiment, the reflux hood 32 is provided at the outlet of the heating channel 1 , and the purpose is also to make the fluid at the cone tail reflux, further prolong the passage time of the fluid, and enhance the heating effect on the fluid.

[0038] As a preferred embodiment, the surface of the heating channel 1 is wrapped with a thermal insulation layer 13 , and the electromagnetic coil 2 is wound outside the thermal insulation layer 13 .

[0039] In the above embodiment, the design of the thermal insulation layer 13 reduces heat loss during heating, has a good energy-saving effect, and indirectly improves the heating effect.

[0040] In this embodiment, the electromagnetic coil 2 is equipped with an electromagnetic controller for controlling the load of the electromagnetic coil 2 .

[0041] Example 2

[0042] like Figure 3As shown, the air-powder mixing preheating system of this embodiment meets the boiler stable combustion requirement and includes an air-powder mixer 51, a heat exchanger 52, a reflux electromagnetic heating device 53 in Example 1 and a boiler 54. The air inlet and the medium inlet of the air-powder mixer 51 are respectively connected to the fan 55 and the pulverized coal bin 56. The outlet of the air-powder mixer 51, the tube-side inlet and tube-side outlet of the heat exchanger 52, the inlet and outlet of the heating channel 1, and the burner of the boiler 54 are connected in sequence through pipelines. The shell-side inlet of the heat exchanger 52 is connected to the flue of the boiler 54 through a flue gas circulation pipeline. A flue gas circulation fan 57 is connected to the flue gas circulation pipeline. A feeding pipeline 58 for feeding magnetic metal powder is connected to the pipeline between the tube-side outlet of the heat exchanger 52 and the inlet of the heating channel 1.

[0043] The usage process is as follows:

[0044] The fan 55 is running (the fan 55 is used to transport the primary and secondary air of the boiler) and operates according to the working conditions set by the boiler 54. The pulverized coal bin 56 also drops at a set coal drop rate. The wind carries the pulverized coal into the air-powder mixer 51 for full mixing. After being evenly mixed, it enters the heat exchanger 52 for convective heat exchange with the flue gas from the flue gas circulation pipeline to increase the temperature of the air-powder mixture. If the load of the boiler 54 is high, the air-powder temperature can be increased only by the heat exchanger 52 (the reflux electromagnetic heating device 53 does not need to be turned on); if the load of the boiler is low, the air-powder mixture after coming out of the heat exchanger 52 continues to enter the reflux electromagnetic heating device 53 for heating, using the principle of electromagnetic induction to generate heat. Before entering the reflux electromagnetic heating device 53, the metal powder is also mixed with the air-powder mixture and then enters the reflux electromagnetic heating device 53 together, further improving the heating efficiency and shortening the heating time. After passing through the reflux electromagnetic heating device 53, the temperature of the air-powder mixture sample is measured. If the temperature meets the preset requirements, it can enter the boiler for combustion. The entire system can effectively heat the air-powder before entering the boiler burner. The use of electromagnetic heating avoids open flames and reduces safety hazards. At the same time, the addition of metal powder better meets the electromagnetic heating requirements, improves heating efficiency, and shortens the preheating time.

[0045] As a preferred embodiment, a temperature measuring device 59 is connected to the outlet of the heating channel 1 .

[0046] In the above embodiment, by directly connecting the temperature measuring device 59 at the outlet of the heating channel 1 to measure the temperature of the air-powder mixture, the temperature of the air-powder mixture can be intuitively understood, so that the staff can flexibly adjust the heating conditions of the system.

[0047] In this embodiment, the temperature measuring device 59 can be a thermocouple of the prior art, which is connected to the control system of the boiler to realize the feedback of the intelligent thermometer data.

[0048] More preferably, a reflux line 60 is connected in parallel between the inlet and outlet of the above-mentioned heating channel 1. When the temperature of the air-powder mixture sample after being heated by the reflux electromagnetic heating device 53 is not satisfied (does not meet the standard), the pipeline leading to the boiler 54 is closed, and the air-powder mixture sample passes through the reflux line 60 and returns to the reflux electromagnetic heating device 53, and the temperature is further increased by extending the heating time. If the temperature of the air-powder mixture sample after reflux is still not satisfied, the heating temperature can be increased by increasing the output power of the reflux electromagnetic heating device 53 (that is, increasing the load of the electromagnetic coil). If the temperature of the air-powder mixture sample is still not satisfied after increasing the output power, the heating efficiency can be further improved by increasing the amount of metal powder added. The method is very flexible and can increase the temperature of the air-powder mixture sample from multiple operations.

[0049] It should be particularly emphasized that the fluid flow rate in the return pipeline 60 should be smaller than the flow rate of the main line connecting the reflux electromagnetic heating device 53 to the boiler 54 (that is, the return pipeline 60 should be smaller than the main line, and the flow rate can be faster), so that the reflux air powder can pass through the return pipeline 60 quickly, reducing the heat loss of the air powder passing through the return pipeline 60.

[0050] As a preferred embodiment, a flue gas denitrification and dust removal system 61 is provided on the flue gas circulation pipeline.

[0051] In the above embodiment, the flue gas after combustion in the boiler 54 is processed by the flue gas denitrification and dust removal system 61 to reduce the corrosiveness of the flue gas and thus reduce the damage of the flue gas to the pipeline.

[0052] In this embodiment, the flue gas denitrification and dust removal system 61 is a device of the prior art, which can be an existing combined device with two sets of functions of denitrification and dust removal, or separate denitrification and dust removal devices can be connected in series on the flue gas circulation pipeline.

[0053] In this embodiment, the magnetic metal powder is made of one or more ferromagnetic materials such as aluminum, iron, nickel, cobalt, and stainless steel.

[0054] As a preferred embodiment, a flow regulating device 62 is provided on the pipeline connecting the outlet of the heating channel 1 and the burner.

[0055] In the above embodiment, the flow rate of the pipeline that is ultimately delivered to the boiler 54 is adjusted by the flow regulating device 62, which makes the operation more convenient.

[0056] The flow regulating device 62 may be a flow control valve.

[0057] It should be noted that in the system of this embodiment, a damper or valve can be added to the pipeline according to actual usage requirements to control the flow rate of the fluid in the corresponding section of the pipeline. In addition, the various electrical components and valves in this embodiment are connected to the control system of the boiler 54 to achieve automatic control. At the same time, the reflux electromagnetic heating device 53 is also connected to the control system of the boiler 54.

[0058] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0060] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0061] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0062] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean 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 representations of the above terms do 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. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0063] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A reflux electromagnetic heating device, characterized in that: The invention comprises a tubular heating channel (1), wherein the heating channel (1) is a magnetic metal component, one end of which is an inlet and the other end is an outlet, an electromagnetic coil (2) is wound around the surface of the heating channel (1), and a turbulent structure (3) for obstructing airflow and causing part of the airflow to flow back is provided in the heating channel (1); The flow-disturbing structure (3) comprises a flow-disturbing blunt body (31), wherein a plurality of the flow-disturbing blunt bodies (31) are provided and are spaced apart and distributed along the long axis direction of the heating channel (1); The heating channel (1) comprises a plurality of axially connected expanding sections (11) and narrowing sections (12), wherein the expanding sections (11) are distributed one-to-one between two adjacent narrowing sections (12), the cross-sectional area of ​​the expanding section (11) is larger than the cross-sectional area of ​​the narrowing section (12), and the plurality of turbulent bluff bodies (31) are respectively installed one-to-one at the connection between the narrowing section (12) and the adjacent expanding section (11).

2. A reflux electromagnetic heating device according to claim 1, characterized in that: The spoiler (31) is installed inside the heating channel (1) through a bracket. The spoiler (31) is a conical component with a smooth surface, which is arranged along the long axis direction of the heating channel (1), and the cone tail end of the conical component faces the interface of the heating channel (1).

3. A reflux electromagnetic heating device according to claim 2, characterized in that: The spoiler structure (3) further comprises a return air hood (32), which is a shell-and-tube structure with one end open and fixed to a position near the outlet of the heating channel (1) via a bracket, with the open end of the return air hood (32) facing the inlet of the heating channel (1).

4. A system for preheating air-powder mixture to meet the requirements of boiler stable combustion, characterized by: It comprises an air-powder mixer (51), a heat exchanger (52), a reflux electromagnetic heating device (53) as described in any one of claims 1 to 3, and a boiler (54), the air inlet and the medium inlet of the air-powder mixer (51) are respectively connected to a fan (55) and a pulverized coal bin (56), the outlet of the air-powder mixer (51), the tube-side inlet and the tube-side outlet of the heat exchanger (52), the inlet and outlet of the heating channel (1), and the burner of the boiler (54) are connected in sequence through pipelines, the shell-side inlet of the heat exchanger (52) is connected to the flue of the boiler (54) through a flue gas circulation pipeline, a flue gas circulation fan (57) is connected to the flue gas circulation pipeline, and a feeding pipeline (58) for feeding magnetic metal powder is connected to the pipeline between the tube-side outlet of the heat exchanger (52) and the inlet of the heating channel (1).

5. The air-powder mixed preheating system for boiler combustion stabilization according to claim 4 is characterized in that: The outlet of the heating channel (1) is connected to a temperature measuring device (59).

6. The air-powder mixed preheating system for boiler combustion stabilization according to claim 5 is characterized in that: A return line (60) is connected in parallel between the inlet and outlet of the heating channel (1).

7. The air-powder mixed preheating system for boiler combustion stabilization according to claim 4 is characterized in that: The flue gas circulation pipeline is provided with a flue gas denitrification and dust removal system (61).

8. The air-powder mixed preheating system for boiler combustion stabilization according to claim 4 is characterized by: The magnetic metal powder includes one or more of aluminum, iron, nickel, cobalt, and stainless steel.

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