Low-load stable combustion pulverized coal externally heated smoke-heat type swirl burner and heating method

Abstract

The present invention relates to a pulverized coal externally heated smoke-heated swirl burner for stable combustion at low loads and a heating method. The main problems on the boiler side in the prior art are that at low loads, the amount of coal burned in the furnace is low and the furnace temperature is low, resulting in unstable combustion. The composition of the present invention includes: a swirl burner, the swirl burner includes a central air passage (1), an air passage (2) for primary air is arranged outside the central air passage, a stable combustion tooth (13) is arranged at a position near the nozzle at the left end of the primary air passage, and the right end is connected to a primary air supply pipe. The outer layer of the right half section of the primary air passage is sequentially provided with a heating sleeve (4) and an air box (5). The left end of the heating sleeve is blocked by a heating sleeve end baffle (9), the upper side of the right end is connected to a heating sleeve flue gas inlet (3), and the lower side is connected to a heating sleeve flue gas outlet (15). The present invention is used for a pulverized coal externally heated smoke-heated swirl burner for stable combustion at low loads.

Description

Technical Field:

[0002] The present invention relates to the technical field of power station boiler combustion equipment, and particularly relates to a pulverized coal externally heated flue gas thermal type swirl burner for stable combustion at low load and a heating method. Background Art:

[0004] With the increasingly rapid development of clean energy such as wind power and photovoltaic power, the installed capacity has also increased rapidly. While providing a large amount of clean electricity, clean energy such as wind power and photovoltaic power also has characteristics such as intermittency, volatility, randomness, low reactive power supply performance, and weak short-circuit current supply ability in a short time, and cannot be completely absorbed by the power system in China, which brings huge challenges to the safety and stability of the power system;

[0005] The National Energy Administration requires flexible transformation of thermal power units to release their potential deep peak shaving capabilities, so as to improve the regulation ability of the power system in China and promote the consumption of renewable energy. However, when coal-fired units perform deep peak shaving, due to the low load operation state of the units, which is far from the designed load, many problems will occur. The main problem on the boiler side of the existing technology is that at low load, the coal combustion amount in the furnace is low, the furnace temperature is relatively low, and unstable combustion will occur. In order to alleviate this problem and improve the low load stable combustion ability of thermal power units, it is urgent to develop a burner suitable for stable combustion under low load conditions of boilers to meet the needs of deep peak shaving of coal-fired units. Summary of the Invention:

[0007] The purpose of the present invention is to provide a pulverized coal externally heated flue gas thermal type swirl burner for stable combustion at low load and a heating method, which have extremely strong stable combustion ability and the effect of facilitating the adjustment of heating quantity, and have broad application prospects in the flexible transformation of thermal power.

[0008] The above purpose is achieved by the following technical solutions:

[0009] A pulverized coal externally heated flue gas thermal type swirl burner for stable combustion at low load, which comprises: a swirl burner, the swirl burner includes a central air passage, an annular primary air passage is arranged outside the central air passage, a stable combustion tooth is arranged at a position near the nozzle at the left end of the primary air passage, and the right end is connected to a primary air supply pipeline. The outer layer of the right half section of the primary air passage is sequentially provided with a heating sleeve and an air box. The left end of the heating sleeve is blocked by a heating sleeve end baffle, the upper side of the right end is connected to a heating sleeve flue gas inlet, and the lower side is connected to a heating sleeve flue gas outlet. The inside of the heating sleeve is blocked by a heating sleeve flue gas baffle A, a heating sleeve axial flue gas baffle, and a heating sleeve flue gas baffle B to form a zigzag passage.

[0010] The described pulverized coal externally heated smoke-heated swirl burner for low-load stable combustion, the left end of the air box is provided with and is open at the right ends of the secondary air channel, the tertiary air channel, and the quaternary air channel. The left sides of the secondary air channel and the tertiary air channel are nozzles, and the right sides are connected to the air box. The left side of the quaternary air channel is provided with a conical nozzle, and the right side is connected to the air box.

[0011] The described pulverized coal externally heated smoke-heated swirl burner for low-load stable combustion, the central air channel, the primary air channel, and the flame stabilizer teeth are made of wear-resistant and heat-resistant alloy or ceramic. The connection methods between the secondary air pipeline, the tertiary air pipeline, and the quaternary air pipeline and the air box can be welding, flange connection, or integral casting. The conical nozzle is arranged on the outer edge of the quaternary air nozzle.

[0012] A pulverized coal externally heated smoke-heated swirl burner for low-load stable combustion and a heating method, the method includes the following steps:

[0013] First, a heating sleeve is arranged between the primary air channel and the air box. Hot flue gas can enter from the heating sleeve flue gas inlet on the upper side of its right end and flow out from the heating sleeve flue gas outlet on the lower side of its right end. During the working process, the heating sleeve can not only heat the pulverized coal air flow in the primary air channel but also heat the air in the air box.

[0014] The inside of the heating sleeve is blocked by the heating sleeve flue gas baffle A, the heating sleeve axial flue gas baffle, and the heating sleeve flue gas baffle B into a zigzag flue gas channel. The flue gas channel is divided into upper and lower parts with the heating sleeve axial flue gas baffle as the boundary. The upper side is a flue gas incoming flow channel with the same flow direction as the pulverized coal flow direction, and the lower side is a flue gas return channel with the opposite flow direction to the pulverized coal flow direction, ensuring that the hot flue gas flows more evenly in the heating sleeve and avoiding short-circuit phenomena.

[0015] The left end of the heating sleeve is blocked by the heating sleeve end baffle. A distance of 5 times the height of the flue gas channel housing needs to be maintained between the heating sleeve end baffle and the right-side inlets of the secondary air channel, the tertiary air channel, and the quaternary air channel. If the left end of the flue gas housing adopts a slope structure with an inclination angle not greater than 45°, this distance can be shortened by half, enabling the air in the air box to smoothly enter the secondary air channel.

[0016] By controlling the flue gas flow rate, the pulverized coal air flow in the primary air channel can be heated to a temperature close to the ignition point, causing the volatile matter of the pulverized coal to precipitate in the burner. The volatile matter is easier to ignite than the pulverized coal particles. At this time, the air in the air box also has a higher temperature, which is more conducive to the ignition process when the pulverized coal is ejected from the nozzle, enabling the pulverized coal air flow to easily catch fire when entering the furnace and stably burn even under very low load rates.

[0017] Beneficial effects:

[0018] 1. The present invention is a pulverized coal externally heated flue gas swirl burner applicable to low-load stable combustion and its heating method. A heating sleeve is arranged between the primary air passage and the air box. During normal operation, the heating sleeve can not only heat the pulverized coal air flow in the primary air passage, but also heat the air in the air box. By controlling the flue gas flow, the pulverized coal air flow in the primary air passage can be heated to a temperature close to the ignition point. At this time, the air in the air box also has a relatively high temperature. Such a design enables the pulverized coal air flow to catch fire very easily when entering the furnace, and can stably burn even under a very low load rate.

[0019] The present invention uses hot flue gas as the heating heat source, which can be directly extracted from a suitable place in the boiler tail flue, with good economy and cost savings.

[0020] The interior of the heating sleeve of the present invention is blocked into a zigzag flue gas passage by the heating sleeve flue gas baffle A, the heating sleeve axial flue gas baffle, and the heating sleeve flue gas baffle B, ensuring that the hot flue gas flows more uniformly in the heating sleeve, avoiding short-circuit phenomena, and making more full use of the heat of the flue gas.

[0021] The present invention can be connected to the solid fuel conveying pipeline by means of flange connection or welding, which can be straight pipe connection or elbow connection. It has a wide range of applications, is structurally compact, and is convenient for the installation, disassembly, operation and maintenance of the burner.

[0022] The structure of the present invention will greatly improve the low-load stable combustion performance of power station boilers. The characteristic of this new type of swirl burner is that a flue gas heating sleeve is arranged in the air box, using hot flue gas as the heat source, and having the advantages of strong economy and cost savings.

[0023] The heating sleeve of the present invention simultaneously heats the pulverized coal air flow in the primary air passage and the air in the air box, increasing the initial temperature of the pulverized coal and air (secondary, tertiary, and quaternary air) entering the furnace, making the heat required for the pulverized coal to catch fire lower, and thus having the ability of stable combustion.

[0024] The interior of the flue gas heating sleeve of the present invention is blocked into a zigzag flue gas passage by the flue gas baffle, ensuring that the hot flue gas flows uniformly in the heating sleeve, avoiding short-circuit phenomena, making the heating process more uniform. A certain distance is maintained between the end baffle of the heating sleeve and the right-side inlet of the secondary, tertiary, and quaternary air passages, enabling the air in the air box to smoothly enter the secondary air passage. The central air passage, primary air passage, and stable combustion teeth are made of wear-resistant and heat-resistant alloy or ceramics to ensure the normal operation of the burner and prevent overheating phenomena. Brief description of the drawings:

[0026] Attached Figure 1 is a schematic structural diagram of the present invention.

[0027] Attached Figure 2 is the attached Figure 1 top view.

[0028] Attached Figure 3 is the attached Figure 1 A - A sectional view.

[0029] Attached Figure 4 is the schematic structural view of the flue gas of the heating sleeve of this application with upward inlet and downward outlet.

[0030] Attached Figure 5 is the attached Figure 4 top view.

[0031] Attached Figure 6 is the attached Figure 4 A - A sectional view.

[0032] Attached Figure 7 is the schematic structural view of the flue gas of the heating sleeve of this application with downward inlet and upward outlet.

[0033] Attached Figure 8 is the attached Figure 7 top view.

[0034] Attached Figure 9 is the attached Figure 7 A - A sectional view.

[0035] Attached Figure 10 is the schematic structural view of the flue gas of the heating sleeve of this application with left - hand inlet and right - hand outlet.

[0036] Attached Figure 11 is the attached Figure 10 bottom view.

[0037] Attached Figure 12 is the attached Figure 10 A - A sectional view.

[0038] Attached Figure 13 is the schematic structural view of the flue gas of the heating sleeve of this application with right - hand inlet and left - hand outlet.

[0039] Attached Figure 14 is the attached Figure 13 bottom view.

[0040] Attached Figure 15 is the attached Figure 13 A - A sectional view.

[0041] Wherein: 1. Central air duct, 2. Primary air duct, 3. Flue gas inlet of heating sleeve, 4. Heating sleeve, 5. Wind box, 6. Heating sleeve flue gas baffle A, 7. Axial flue gas baffle of heating sleeve, 8. Heating sleeve flue gas baffle B, 9. End baffle of heating sleeve, 10. Secondary air duct, 11. Tertiary air duct, 12. Quaternary air duct, 13. Flame stabilizing teeth, 14. Conical nozzle, 15. Flue gas outlet of heating sleeve. Detailed implementation method:

[0043] Embodiment 1:

[0044] A pulverized coal externally heated flue gas hot swirl burner for stable combustion at low load, which comprises: a swirl burner, the swirl burner includes a central air duct 1, a primary air duct 2 is arranged outside the central air duct, flame stabilizing teeth 13 are arranged at the position near the nozzle at the left end of the primary air duct, the right end is connected to the primary air supply pipe, the right half of the primary air duct is sequentially arranged with a heating sleeve 4 and a wind box 5 outside, the left end of the heating sleeve is blocked by an end baffle 9 of the heating sleeve, the upper side of the right end is connected to a flue gas inlet 3 of the heating sleeve, and the lower side is connected to a flue gas outlet 15 of the heating sleeve. The inside of the heating sleeve is blocked by a heating sleeve flue gas baffle A 6, an axial flue gas baffle 7 of the heating sleeve, and a heating sleeve flue gas baffle B 8 to form a tortuous channel.

[0045] Embodiment 2:

[0046] The pulverized coal externally heated flue gas hot swirl burner for stable combustion at low load according to Embodiment 1, the left end of the wind box is provided with the right ends of a secondary air duct 10, a tertiary air duct 11, and a quaternary air duct 12 and is open. The left sides of the secondary air duct and the tertiary air duct are nozzles, and the right sides are connected to the wind box. The left side of the quaternary air duct is provided with a conical nozzle 14, and the right side is connected to the wind box.

[0047] Embodiment 3:

[0048] The pulverized coal externally heated flue gas hot swirl burner for stable combustion at low load according to Embodiment 2, the central air duct, the primary air duct, and the flame stabilizing teeth are made of wear-resistant and heat-resistant alloy or ceramic. The connection modes between the secondary air duct, the tertiary air duct, the quaternary air duct and the wind box can be welding, flange connection, or integral casting. The conical nozzle is arranged on the outer edge of the quaternary air nozzle.

[0049] Embodiment 4:

[0050] The pulverized coal externally heated flue gas hot swirl burner for stable combustion at low load and the heating method according to Embodiments 1-3, the method comprises the following steps:

[0051] First, a heating sleeve is arranged between the primary air passage and the air box. Hot flue gas can enter from the heating sleeve flue gas inlet on the upper side of its right end and flow out from the heating sleeve flue gas outlet on the lower side of its right end. During operation, the heating sleeve can heat both the pulverized coal airflow in the primary air passage and the air in the air box;

[0052] The interior of the heating sleeve is blocked by a heating sleeve flue gas baffle A, a heating sleeve axial flue gas baffle, and a heating sleeve flue gas baffle B into a zigzag flue gas passage. The flue gas passage is divided into upper and lower parts with the heating sleeve axial flue gas baffle as the boundary. The upper side is a flue gas incoming flow passage with the same rectification direction as the pulverized coal flow direction, and the lower side is a flue gas return flow passage with the rectification direction opposite to the pulverized coal flow direction, ensuring that the hot flue gas flows more evenly in the heating sleeve and avoiding short - circuit phenomena;

[0053] The left end of the heating sleeve is blocked by a heating sleeve end baffle. A distance of 5 times the height of the flue gas passage shell needs to be maintained between the heating sleeve end baffle and the right - hand inlets of the secondary air passage, the tertiary air passage, and the quaternary air passage. If the left end of the flue gas shell adopts a slope structure with an inclination angle not greater than 45°, this distance can be shortened by half, enabling the air in the air box to smoothly enter the secondary air passage;

[0054] By controlling the flue gas flow rate, the pulverized coal airflow in the primary air passage can be heated to a temperature close to the ignition point, causing the volatile matter of the pulverized coal to precipitate in the burner. Since the volatile matter is easier to ignite than the pulverized coal particles, and at this time the air in the air box also has a relatively high temperature, it is more conducive to the ignition process when the pulverized coal is ejected from the nozzle, enabling the pulverized coal airflow to easily catch fire when entering the furnace and stably burn even under very low load rates;

[0055] For the low - load stable - combustion pulverized - coal externally - heated flue - gas - heated swirl burner, the central air passage is located in the innermost layer of the entire burner, with a nozzle at the left end and connected to a pipe for transporting central air at the right end; the primary air passage is located outside the central air passage, with a stable - combustion tooth arranged near the nozzle at the left end and connected to a primary air supply pipe at the right end. The outer layer of the primary air passage is designed in two sections:

[0056] The outer layer of the left half of the primary air passage is successively arranged with a secondary air passage, a tertiary air passage, and a quaternary air passage. The outer layer of the right half of the primary air passage is successively arranged with a heating sleeve and a wind box. The left end of the heating sleeve is blocked by a heating sleeve end baffle, and the upper side of the right end is connected to a heating sleeve flue gas inlet, and the lower side is connected to a heating sleeve flue gas outlet. The inside of the heating sleeve is blocked by a heating sleeve flue gas baffle A, a heating sleeve axial flue gas baffle, and a heating sleeve flue gas baffle B into a zigzag passage. The left end of the wind box is connected to the right ends of the secondary air passage, the tertiary air passage, and the quaternary air passage, and the right end is open and can be directly connected to the air supply pipeline in engineering applications. The left side of the secondary air passage is a nozzle, and the right side is connected to the wind box. The left side of the tertiary air passage is a nozzle, and the right side is connected to the wind box. The left side of the quaternary air passage is provided with a conical nozzle, and the right side is connected to the wind box.

[0057] The described heating sleeve is arranged between the primary air passage and the wind box. Hot flue gas can enter from the heating sleeve flue gas inlet on the upper side of its right end and flow out from the heating sleeve flue gas outlet on the lower side of its right end. In this way, during the working process, the heating sleeve can not only heat the pulverized coal airflow in the primary air passage but also heat the air in the wind box.

[0058] The inside of the heating sleeve is blocked by a heating sleeve flue gas baffle A, a heating sleeve axial flue gas baffle, and a heating sleeve flue gas baffle B into a zigzag flue gas passage. The flue gas passage is divided into upper and lower parts with the heating sleeve axial flue gas baffle as the boundary. The upper side is a flue gas incoming flow passage with the same rectification direction as the pulverized coal flow direction, and the lower side is a flue gas reflux passage with the rectification direction opposite to the pulverized coal flow direction, ensuring that the hot flue gas flows relatively evenly in the heating sleeve and avoiding short-circuit phenomena. A certain distance needs to be maintained between the heating sleeve and the right-side inlets of the secondary air passage, the tertiary air passage, and the quaternary air passage so that the air in the wind box can smoothly enter the secondary air passage.

[0059] In the actual engineering application process, due to different installation positions, the positions of the heating sleeve flue gas inlets and outlets are random. The present invention is applicable to all cases of the positions of the flue gas inlets and outlets. The following combines the attached Figures 1-3 Examples are given for several cases of the heating sleeve flue gas entering from above and flowing out from below, entering from below and flowing out from above, entering from the left and flowing out from the right, and entering from the right and flowing out from the left of the present invention.

[0060] (1) In the case of the heating sleeve flue gas entering from above and flowing out from below, as shown in the attached Figures 4-6 The hot flue gas inlet is arranged at the upper part of the heating sleeve, and the outlet is arranged at the lower part of the heating sleeve.

[0061] (2) In the case of the heating sleeve flue gas entering from below and flowing out from above, as shown in the attached Figures 7-9 The hot flue gas inlet is arranged at the lower part of the heating sleeve, and the outlet is arranged at the upper part of the heating sleeve.

[0062] (3) In the case of the heating sleeve flue gas entering from the left and flowing out from the right, as shown in the attached Figures 10-12As shown, the hot flue gas inlet is arranged on the left side of the heating sleeve, and the outlet is arranged on the right side of the heating sleeve.

[0063] (4) In the case where the flue gas in the heating sleeve enters from the right and exits from the left, as shown in the appendix Figures 13-15 As shown, the hot flue gas inlet is arranged on the right side of the heating sleeve, and the outlet is arranged on the left side of the heating sleeve.

Claims

1. A pulverized coal externally heated smoke-heated swirl burner for stable combustion at low loads, its composition includes: A swirl burner, characterized in that: the swirl burner includes a central air passage, an annular primary air passage is arranged outside the central air passage, a stable combustion tooth is arranged at a position near the nozzle at the left end of the primary air passage, and the right end is connected to a primary air supply pipe. The outer layer of the right half of the primary air passage is sequentially provided with a heating sleeve and a wind box. The left end of the heating sleeve is blocked by a heating sleeve end baffle, the upper side of the right end is connected to a heating sleeve flue gas inlet, and the lower side is connected to a heating sleeve flue gas outlet. The inside of the heating sleeve is blocked by a heating sleeve flue gas baffle A, a heating sleeve axial flue gas baffle, and a heating sleeve flue gas baffle B into a zigzag passage.

2. The pulverized coal externally heated smoke-heated swirl burner for stable combustion at low loads according to claim 1, characterized in that: The left end of the wind box is provided with the right ends of the secondary air passage, the tertiary air passage, and the quaternary air passage and is open. The left sides of the secondary air passage and the tertiary air passage are nozzles, and the right sides are connected to the wind box. The left side of the quaternary air passage is provided with a conical nozzle, and the right side is connected to the wind box.

3. A heating method for the pulverized coal externally heated smoke-heated swirl burner according to any one of claims 1-2, characterized in that: This method includes the following steps: First, the heating sleeve is arranged between the primary air passage and the wind box. Hot flue gas can enter from the heating sleeve flue gas inlet on the upper side of the right end and flow out from the heating sleeve flue gas outlet on the lower side of the right end. During the working process, the heating sleeve can not only heat the pulverized coal air flow in the primary air passage but also heat the air in the wind box; The inside of the heating sleeve is blocked by a heating sleeve flue gas baffle A, a heating sleeve axial flue gas baffle, and a heating sleeve flue gas baffle B into a zigzag flue gas passage. The flue gas passage is divided into upper and lower parts with the heating sleeve axial flue gas baffle as the boundary. The upper side is a flue gas incoming flow passage with the same rectification direction as the pulverized coal flow direction, and the lower side is a flue gas return passage with the opposite rectification direction to the pulverized coal flow direction, ensuring that the hot flue gas flows more evenly in the heating sleeve and avoiding short-circuit phenomena; The left end of the heating sleeve is blocked by a heating sleeve end baffle. A distance five times the height of the flue gas passage shell needs to be maintained between the heating sleeve end baffle and the right-side inlets of the secondary air passage, the tertiary air passage, and the quaternary air passage. If the left end of the flue gas shell adopts a slope structure with an inclination angle not greater than 45°, this distance can be shortened by half to enable the air in the wind box to smoothly enter the secondary air passage; By controlling the flue gas flow rate, the pulverized coal air flow in the primary air passage can be heated to a temperature close to the ignition point, causing the volatile matter in the pulverized coal to precipitate in the burner. The volatile matter is more easily ignited than the pulverized coal particles. At this time, the air in the wind box also has a higher temperature, which is more conducive to the ignition process when the pulverized coal is ejected from the nozzle, enabling the pulverized coal air flow to easily catch fire when entering the furnace and stably burn even under very low load rates.

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