Radiant tube combustion device

Abstract

The present invention discloses a radiant tube combustion device in the field of gas combustion technology, which includes a radiant tube, a gas burner, a gas pipe, a radiant tube heat exchange device, an ejector, an expansion joint connector, a swirler, a dual-electrode ignition electrode, and a staged air sleeve. One end of the radiant tube is installed with a radiant tube heat exchange device, and the other end of the radiant tube is installed with a gas burner. A gas pipe is installed on the body of the gas burner, and a swirler is installed at the outlet of the gas pipe. A staged air sleeve is installed on the outer wall of the swirler. One end of the dual-electrode ignition electrode is installed on the flange at one end of the gas burner body, and the other end of the dual-electrode ignition electrode passes through the gas pipe and is installed on the swirler. Beneficial effects: The present invention adopts the methods of preheated air staging and gas staging, so that air enters the radiant tube in two stages according to a certain ratio and mixes and burns with the gas divided into two stages according to the ratio, effectively solving the problem of large NOx generation in the furnace.

Description

Technical Field

[0001] The present invention relates to the technical field of gas combustion, and particularly relates to a radiant tube combustion device for heating furnaces and heat treatment furnaces in industries such as metallurgy, machinery, textile, and food. Background Art

[0002] The radiant tube heating device burns inside a sealed sleeve, and transfers heat to the object to be heated mainly in the form of thermal radiation through the heated sleeve surface. The combustion products do not contact the object to be heated, and will not cause pollution of the combustion atmosphere or affect the product quality. The furnace atmosphere and heating temperature are convenient to control and adjust. At present, the thermal efficiency of the radiant tube can reach more than 70%. Since the air is preheated to a relatively high temperature, the flame temperature can reach 1200°C. The relatively high flame temperature will generate a large amount of NOx, resulting in excessive NOx in the flue gas and causing serious air pollution. Therefore, for a double heat exchange type radiant tube burner, on the basis of relatively high combustion efficiency, how to reduce the NOx emission is a difficult problem.

[0003] The radiant tube burner in the prior art has a gas injection hole in the center and air nozzles on the outside. Although it can achieve the purpose of mixing and burning gas and air, there is no restriction on the angle of the air flow, which is not conducive to the full mixing of the gas. At the same time, local high temperature is likely to occur at the outlet, which will greatly increase the NOx emission in the radiant tube.

[0004] Moreover, this type of radiant tube burner only uses a primary heat exchanger, and there are problems such as poor heat exchange effect, high exhaust gas temperature, insufficient utilization of the waste heat of the flue gas, easy damage and difficult installation of the ignition electrode, and poor energy utilization. Summary of the Invention

[0005] In order to solve the problems of large NOx emission in the radiant tube, easy damage and difficult installation of the ignition electrode, and insufficient utilization of the waste heat of the flue gas in the prior art, the present invention provides a new radiant tube combustion device.

[0006] A radiant tube combustion device includes a radiant tube, a gas burner, a gas pipe, a radiant tube heat exchange device, an ejector, an expansion joint connector, a swirler, an ignition electrode, and a staged air sleeve. One end of the radiant tube is equipped with a radiant tube heat exchange device, and the other end of the radiant tube is equipped with a gas burner. One end of the expansion joint connector is connected to the radiant tube heat exchange device through an ejector, and the other end of the expansion joint connector is connected to the gas burner. A gas pipe is installed on the main body of the gas burner, and a swirler is installed at the outlet of the gas pipe. A staged air sleeve is installed on the outer wall of the swirler. The swirler includes a swirler sleeve, swirler vanes, an air staging disc, a primary gas nozzle, a secondary gas nozzle, and an air swirl groove. The inner wall of the swirler sleeve is provided with swirler vanes. The primary gas nozzle is arranged at the outlet of the swirler sleeve. The secondary gas nozzle is arranged on the front side wall of the swirler sleeve. The air staging disc is installed on the outer wall of the swirler sleeve, and the air swirl groove is provided on the air staging disc. One end of the ignition electrode is installed on the flange at one end of the main body of the gas burner, and the other end of the ignition electrode passes through the gas pipe and is installed on the swirler sleeve.

[0007] Further, the double-electrode ignition electrode includes a burner sleeve and a detachable ignition electrode. The detachable ignition electrode includes a ceramic sleeve, a negative electrode mounting plate, a negative electrode support, and a negative electrode ring. The ceramic sleeve wraps the electrode wire to form the positive electrode of the ignition electrode. The negative electrode mounting plate is installed on the outer wall at the end of the ceramic sleeve. The negative electrode mounting plate is connected to the negative electrode ring through a negative electrode support. The negative electrode ring is coaxial with the positive electrode of the ignition electrode, and the distance between the negative electrode ring and the positive electrode of the ignition electrode is 3.5 mm.

[0008] Further, the staged air sleeve includes a primary air pipe, a secondary air pipe, and support columns. The air staging disc is installed on the inner wall of the primary air pipe and the outer wall of the swirler sleeve, and the support columns are installed on the inner wall of the secondary air pipe and the outer wall of the primary air pipe.

[0009] Further, the diameter ratio of the primary air pipe to the secondary air pipe is 1:1.2 - 1.5.

[0010] Further, the length ratio of the primary air pipe to the secondary air pipe is 1:1.5 - 2.

[0011] Further, the shape of the air swirl groove is fan-shaped, rectangular, or circular.

[0012] Further, the axial angle between the primary gas nozzle and the secondary gas nozzle is 90°.

[0013] Further, the shape of the swirler vanes is trapezoidal or rectangular, and the number of the swirler vanes is 4 - 12.

[0014] Further, the number of the negative electrode supports is three.

[0015] Further, the angle formed by the swirl vane and the inner wall of the cyclone casing is 10° - 45°.

[0016] The radiant tube heat exchange device is introduced in detail in the utility model patent "High-efficiency Radiant Tube Heat Exchange Device" with the patent number CN2020230234589. The high-efficiency radiant tube heat exchange device uses a two-stage high-efficiency heat exchanger to recover the waste heat in the flue gas, thereby increasing the temperature of the combustion-supporting air to above 550°C and reducing the flue gas discharge temperature to below 500°C. Compared with the traditional combustion system with a combustion-supporting air temperature of 200 - 400°C, the energy utilization rate and combustion efficiency are greatly improved. At the same time, during the combustion process, the flue gas returns to the preheated air through the ejector chamber, diluting the preheated air, reducing the oxygen content, and reducing the generation of NOx. The NOx emissions are low, featuring both energy conservation and environmental protection. It is a safe, efficient, energy-saving, and environmentally friendly new type of combustion device, solving the problems of low combustion efficiency, poor energy utilization, and insufficient utilization of flue gas waste heat in existing industrial furnaces, and effectively solving the problem of large NOx generation in the furnace. The ejector chamber body in the high-efficiency radiant tube heat exchange device is connected to the ejector in the present invention, and the preheated air mixed with flue gas enters the gas burner through the ejector and the expansion joint connector.

[0017] A radiant tube combustion device disclosed by the present invention mainly adopts the methods of preheated air staging and gas staging, enabling the air to enter the radiant tube in two stages according to a certain proportion and mixing and burning with the gas divided into two stages according to the proportion.

[0018] Since the air enters the radiant tube in stages, the oxygen is insufficient in the mixing of the first-stage air and the gas. Therefore, the first-stage combustion temperature is only 600 - 700°C. The remaining gas enters the second-stage air pipeline and is mixed and burned with the air again, and the temperature can rise to 1000 - 1200°C. After two-stage progressive combustion like this, the gas is fully burned, and the combustion efficiency can reach 70%.

[0019] The beneficial effects achieved by the present invention are as follows:

[0020] 1. The radiant tube combustion device adopts the methods of preheated air staging and gas staging, enabling the air to enter the radiant tube in two stages according to a certain proportion and mixing and burning with the gas divided into two stages according to the proportion, effectively solving the problem of large NOx generation in the furnace.

[0021] 2. The two-stage heat exchange structure of the radiant tube combustion device greatly increases the air preheating temperature. By using the method of air staging combustion with flue gas preheating, each stage of combustion can be under-oxygen combustion, so the flame temperature is not high, all below 1200°C, reducing NOx emissions.

[0022] 3. The radiant tube combustion device adopts the method of two-stage air combustion, which makes the surface temperature of the radiant tube more uniform;

[0023] 4. The radiant tube combustion device has a compact structure, small size, and is easy to install and maintain;

[0024] 5. The negative electrode of the double-electrode ignition electrode can be disassembled just like the positive electrode, which is easy to replace without disassembling the burner and convenient for maintenance. The negative electrode of the double-electrode ignition electrode adopts a ring form and has no fixed discharge position, which reduces local electrode corrosion and prolongs service life.

[0025] 6. The double-electrode ignition electrode is installed with a limited position function under the designed electrode length. When the negative electrode support is against the burner sleeve outlet, it is installed in place to avoid the electrode wire being too short during the installation process and deviating from the flame center, affecting the fire detection effect. The ignition method of the double-electrode ignition electrode arranged in the center position is easy to ignite and has stable ignition performance. At the same time, the swirl blades of the cyclone play a fixing role on the double-electrode ignition electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the radiant tube combustion device of the present invention;

[0027] Figure 2 It is a left side view of the radiant tube combustion device of the present invention;

[0028] Figure 3 It is a structural schematic diagram of the graded air casing;

[0029] Figure 4 It is the right side view of the graded air casing;

[0030] Figure 5 is the front view of the cyclone;

[0031] Figure 6 It is the right side view of the cyclone;

[0032] Figure 7 It is a schematic diagram of the structure of a double-electrode ignition electrode;

[0033] Figure 8 It is a schematic diagram of the structure of a detachable ignition electrode;

[0034] The accompanying drawings are denoted as follows:

[0035] 1 - Radiation tube, 2 - Radiation tube heat exchange device, 3 - Ejector, 4 - Expansion joint connector, 5 - Primary air pipe, 6 - Dual - electrode ignition electrode, 7 - Secondary air pipe, 8 - Gas burner, 9 - Gas pipe, 10 - Swirler, 11 - Air staging disc, 12 - Support column, 13 - Swirl vane, 14 - Gas secondary nozzle, 15 - Gas primary nozzle, 16 - Air swirl groove, 17 - Swirler casing, 18 - Gas burner body, 19 - Burner casing, 20 - Removable ignition electrode, 21 - Ceramic casing, 22 - Negative electrode mounting plate, 23 - Negative electrode support, 24 - Negative electrode ring, 25 - Positive electrode of ignition electrode, A - Air inlet, B - Gas inlet, C - Flue gas outlet. Detailed implementation mode

[0036] Example 1

[0037] A radiation tube combustion device includes a radiation tube 1, a gas burner 8, a gas pipe 9, a radiation tube heat exchange device 2, an ejector 3, an expansion joint connector 4, a swirler, a dual - electrode ignition electrode 6, and a staged - air casing. One end of the radiation tube 1 is equipped with a radiation tube heat exchange device 2, and the other end of the radiation tube is equipped with a gas burner 8. One end of the expansion joint connector 4 is connected to the radiation tube heat exchange device 2 through the ejector 3, and the other end of the expansion joint connector 4 is connected to the gas burner 8. A gas pipe 9 is installed on the gas burner body 18, and a swirler 10 is installed at the outlet of the gas pipe 9. A staged - air casing is installed on the outer wall of the swirler 10. The swirler 10 includes a swirler casing 17, swirl vanes 13, an air staging disc 11, a gas primary nozzle 15, a gas secondary nozzle 14, and an air swirl groove 16. The inner wall of the swirler casing 17 is provided with swirl vanes 13. The gas primary nozzle 15 is arranged at the outlet of the swirler casing 17. The gas secondary nozzle 14 is on the front - end side wall of the swirler casing 17. The air staging disc 11 is installed on the outer wall of the swirler casing 17, and the air staging disc 11 is provided with an air swirl groove 16. One end of the dual - electrode ignition electrode 6 is installed on the flange at one end of the gas burner body 18, and the other end of the dual - electrode ignition electrode 6 passes through the gas pipe 9 and is installed on the swirler casing 17.

[0038] The double-electrode ignition electrode 6 includes a burner sleeve 19 made of metal and a detachable ignition electrode 20. The detachable ignition electrode 20 includes a ceramic sleeve 21, a negative electrode mounting plate 22, a negative electrode support 23, and a negative electrode ring 24. The ceramic sleeve 21 wraps the electrode wire to form the positive electrode 25 of the ignition electrode. The negative electrode mounting plate 22 is installed on the outer wall of the end of the ceramic sleeve 21. The negative electrode mounting plate 22 is connected to the negative electrode ring 24 through the negative electrode support 23. The negative electrode ring 24 is coaxial with the positive electrode 25 of the ignition electrode. The distance between the negative electrode ring 24 and the positive electrode 25 of the ignition electrode is 3.5 mm. The number of the negative electrode supports 23 is three. The detachable ignition electrode is inserted into the burner sleeve until the negative electrode support on the ignition side contacts the burner sleeve and cannot be inserted further, which plays a positioning role. The burner sleeve can control the length of the detachable ignition electrode inserted and fixed, ensure that the designed length extends into the flame, and improve the success rate of flame detection.

[0039] The staged air sleeve includes a primary air pipe 5, a secondary air pipe 7, and a support column 12. The air staging disc 11 is installed on the inner wall of the primary air pipe 5 and the outer wall of the swirler sleeve 17. The support column 12 is installed on the inner wall of the secondary air pipe 7 and the outer wall of the primary air pipe 5.

[0040] The diameter ratio of the primary air pipe 5 to the secondary air pipe 7 is 1:1.2, and the length ratio of the primary air pipe 5 to the secondary air pipe 7 is 1:1.5. The shape of the air swirl groove 16 is fan-shaped. The angle formed by the swirl vane 13 and the inner wall of the swirler sleeve 17 is 45°. The axial angle between the primary gas nozzle 15 and the secondary gas nozzle 14 is 90°. The shape of the swirl vane 13 is trapezoidal, and the number of the swirl vanes 13 is 4.

[0041] Example 2

[0042] A radiant tube combustion device, comprising a radiant tube 1, a gas burner 8, a gas pipe 9, a radiant tube heat exchange device 2, an ejector 3, an expansion joint connector 4, a swirler, a double-electrode ignition electrode 6, and a staged air sleeve. One end of the radiant tube 1 is equipped with a radiant tube heat exchange device 2, and the other end of the radiant tube is equipped with a gas burner 8. One end of the expansion joint connector 4 is connected to the radiant tube heat exchange device 2 through the ejector 3, and the other end of the expansion joint connector 4 is connected to the gas burner 8. A gas pipe 9 is installed on the gas burner body 18, and a swirler 10 is installed at the outlet of the gas pipe 9. A staged air sleeve is installed on the outer wall of the swirler 10. The swirler 10 includes a swirler sleeve 17, swirler vanes 13, an air staging disc 11, a gas primary nozzle 15, a gas secondary nozzle 14, and an air swirl groove 16. The inner wall of the swirler sleeve 17 is provided with swirler vanes 13. The gas primary nozzle 15 is arranged at the outlet of the swirler sleeve 17. The gas secondary nozzle 14 is on the front side wall of the swirler sleeve 17. The air staging disc 11 is installed on the outer wall of the swirler sleeve 17, and the air staging disc 11 is provided with an air swirl groove 16. One end of the double-electrode ignition electrode 6 is installed on the flange at one end of the gas burner body 18, and the other end of the double-electrode ignition electrode 6 passes through the gas pipe 9 and is installed on the swirler sleeve 17.

[0043] The double-electrode ignition electrode 6 includes a burner sleeve 19 and a detachable ignition electrode 20. The detachable ignition electrode 20 includes a ceramic sleeve 21, a negative electrode mounting plate 22, a negative electrode support 23, and a negative electrode ring 24. The ceramic sleeve 21 wraps the electrode wire to form the positive electrode 25 of the ignition electrode. The outer wall of the end of the ceramic sleeve 21 is installed with a negative electrode mounting plate 22. The negative electrode mounting plate 22 is connected to the negative electrode ring 24 through the negative electrode support 23. The negative electrode ring 24 is coaxial with the positive electrode 25 of the ignition electrode. The distance between the negative electrode ring 24 and the positive electrode 25 of the ignition electrode is 3.5 mm. The number of the negative electrode supports 23 is three.

[0044] The staged air sleeve includes a primary air pipe 5, a secondary air pipe 7, and a support column 12. The air staging disc 11 is installed on the inner wall of the primary air pipe 5 and the outer wall of the swirler sleeve 17. The support column 12 is installed on the inner wall of the secondary air pipe 7 and the outer wall of the primary air pipe 5.

[0045] The diameter ratio of the primary air pipe 5 to the secondary air pipe 7 is 1:1.5, the length ratio of the primary air pipe 5 to the secondary air pipe 7 is 1:2. The shape of the air swirl groove 16 is circular. The angle formed by the swirler vanes 13 and the inner wall of the swirler sleeve 17 is 10°. The axial angle between the gas primary nozzle 15 and the gas secondary nozzle 14 is 90°. The shape of the swirler vanes 13 is rectangular, and the number of the swirler vanes 13 is 12.

[0046] Example 3

[0047] A radiant tube combustion device, comprising a radiant tube 1, a gas burner 8, a gas pipe 9, a radiant tube heat exchange device 2, an ejector 3, an expansion joint connector 4, a swirler, an ignition electrode 6, and a staged air sleeve. One end of the radiant tube 1 is provided with the radiant tube heat exchange device 2, and the other end of the radiant tube is provided with the gas burner 8. One end of the expansion joint connector 4 is connected to the radiant tube heat exchange device 2 through the ejector 3, and the other end of the expansion joint connector 4 is connected to the gas burner 8. A gas pipe 9 is installed on the gas burner body 18, and a swirler 10 is installed at the outlet of the gas pipe 9. A staged air sleeve is installed on the outer wall of the swirler 10. The swirler 10 includes a swirler sleeve 17, swirl vanes 13, an air staging disk 11, a gas primary nozzle 15, a gas secondary nozzle 14, and an air swirl groove 16. The swirl vanes 13 are arranged on the inner wall of the swirler sleeve 17. The gas primary nozzle 15 is arranged at the outlet of the swirler sleeve 17, and the gas secondary nozzle 14 is arranged on the front side wall of the swirler sleeve 17. The air staging disk 11 is installed on the outer wall of the swirler sleeve 17, and the air swirl groove 16 is provided on the air staging disk 11. One end of the ignition electrode 6 is installed on the flange at one end of the gas burner body 18, and the other end of the ignition electrode 6 passes through the gas pipe 9 and is installed on the swirler sleeve 17.

[0048] The staged air sleeve includes a primary air pipe 5, a secondary air pipe 7, and a support column 12. The air staging disk 11 is installed on the inner wall of the primary air pipe 5 and the outer wall of the swirler sleeve 17, and the support column 12 is installed on the inner wall of the secondary air pipe 7 and the outer wall of the primary air pipe 5.

[0049] The diameter ratio of the primary air pipe 5 to the secondary air pipe 7 is 1:1.3, the length ratio of the primary air pipe 5 to the secondary air pipe 7 is 1:1.8, the shape of the air swirl groove 16 is rectangular, the angle formed by the swirl vanes 13 and the inner wall of the swirler sleeve 17 is 30°, the axial angle between the gas primary nozzle 15 and the gas secondary nozzle 14 is 90°, the shape of the swirl vanes 13 is rectangular, and the number of the swirl vanes 13 is 8.

Claims

1. A radiant tube combustion device, characterized in that: It includes a radiant tube, a gas burner, a gas pipe, a radiant tube heat exchange device, an ejector, an expansion joint connector, a swirler, an ignition electrode, and a staged air sleeve. One end of the radiant tube is installed with a radiant tube heat exchange device, and the other end of the radiant tube is installed with a gas burner. One end of the expansion joint connector is connected to the radiant tube heat exchange device through an ejector, and the other end of the expansion joint connector is connected to the gas burner. A gas pipe is installed on the gas burner body, and a swirler is installed at the outlet of the gas pipe. A staged air sleeve is installed on the outer wall of the swirler. The swirler includes a swirler casing, swirl vanes, an air staging disk, a primary gas nozzle, a secondary gas nozzle, and an air swirl groove. The swirl vanes are arranged on the inner wall of the swirler casing. The primary gas nozzle is arranged at the outlet of the swirler casing, and the secondary gas nozzle is arranged on the front side wall of the swirler casing. The air staging disk is installed on the outer wall of the swirler casing, and the air swirl groove is provided on the air staging disk. One end of the ignition electrode is installed on the flange at one end of the gas burner body, and the other end of the ignition electrode passes through the gas pipe and is installed on the swirler casing. The ignition electrode is a double-electrode ignition electrode, and the double-electrode ignition electrode includes a burner casing and a detachable ignition electrode. The detachable ignition electrode includes a ceramic casing, a negative electrode mounting plate, a negative electrode support, and a negative electrode ring. The ceramic casing wraps the electrode wire to form the positive electrode of the ignition electrode. The negative electrode mounting plate is installed on the outer wall at the end of the ceramic casing. The negative electrode mounting plate is connected to the negative electrode ring through the negative electrode support. The negative electrode ring is coaxial with the positive electrode of the ignition electrode, and the distance between the negative electrode ring and the positive electrode of the ignition electrode is 3.5 mm.

2. The radiant tube combustion device according to claim 1, wherein: The staged air sleeve includes a primary air pipe, a secondary air pipe, and a support column. The air staging disk is installed on the inner wall of the primary air pipe and the outer wall of the swirler casing. The support column is installed on the inner wall of the secondary air pipe and the outer wall of the primary air pipe.

3. The radiant tube combustion device according to claim 2, wherein: The diameter ratio of the primary air pipe to the secondary air pipe is 1:1.2 - 1.

5.

4. The radiant tube combustion device according to claim 2, wherein: The length ratio of the primary air pipe to the secondary air pipe is 1:1.5 - 2.

5. A radiant tube combustion device according to claim 1, characterized in that: The shape of the air swirl groove is fan-shaped, rectangular, or circular.

6. The radiant tube combustion device according to claim 1, wherein: The axial angle between the primary gas nozzle and the secondary gas nozzle is 90°.

7. A radiant tube combustion device according to claim 1, characterized in that: The shape of the swirl vanes is trapezoidal or rectangular, and the number of the swirl vanes is 4 - 12.

8. The radiant tube combustion device according to claim 1, characterized in that: The number of the negative electrode supports is three.

9. The radiant tube combustion device according to claim 1, wherein: The angle formed by the swirl vanes and the inner wall of the swirler casing is 10° - 45°.

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