CN109253630B - A two-stage heat exchange low NOx self-preheating burner - Google Patents

Abstract

The invention discloses a two-stage heat exchange low NOx self-preheating burner. The combustion-supporting air exchanges heat with the flue gas respectively at the air intake place and the mixed combustion place with the gas. It can efficiently utilize the waste heat of the flue gas and improve the combustion efficiency. To achieve the purpose of energy saving and emission reduction, reduce NOx emissions, at the same time, set up a graded gas supply structure, set up different combustion methods according to needs, and improve combustion efficiency; and the surface of the gas channel is sleeved with springs and fixed in the burner tube through the spring, which can be used in the burner When internal devices are displaced due to thermal expansion, the safety and stability of the gas system structure are ensured, thereby improving the practical life and safety of the overall equipment.

Description

A two-stage heat exchange low NOx self-preheating burner

Technical field

The invention relates to the field of self-preheating burners, in particular to a two-stage heat exchange low NOx self-preheating burner.

Background technique

Industrial production activities are the main cause of energy and environmental problems. Industrial furnaces and other equipment are the main source of air pollution and are also high-energy-consuming industrial equipment. As one of the most important devices of industrial furnaces, burners directly determine the energy consumption and pollutant emissions of industrial furnaces.

The self-preheating burner is a typical type of industrial furnace burner. The burner acts as both a combustion device and a smoke exhaust device at the same time. However, the conventional burner has a single combustion method and the heat exchange efficiency has always been low. The heat exchanger has a short life and requires high materials. At the same time, when the traditional structure is used in the conventional combustion mode with air preheating, the amount of NOx and other pollutants is generated, making it difficult to meet environmental protection standards.

Contents of the invention

In order to solve the above problems, the present invention provides a two-stage heat exchange low NOx self-preheating burner, which can efficiently utilize the waste heat of flue gas to reduce NOx emissions, realize diverse combustion modes, improve combustion efficiency, and achieve the purpose of energy saving and emission reduction. At the same time, it increases the life of the equipment and improves the safety of use.

In order to achieve the above object, one of the technical solutions adopted by the present invention is to provide a two-stage heat exchange low NOx self-preheating burner, including a burner tube, a combustion chamber, an air pipe, a gas channel, a smoke exhaust pipe, and an ignition device. , the surface of the rear end of the burner tube is sleeved with an air guide pipe and connected with the air pipe. The surface of the air guide pipe is sleeved with a smoke guide pipe and connected with the smoke exhaust pipe. One end of the combustion chamber is provided with a spout, and the combustion chamber is set in the burner pipe. And the nozzle extends to the outside of the front end of the burner tube, the gas channel is arranged in the burner tube and one end thereof is connected with the combustion chamber, the ignition end of the ignition device is arranged in the combustion chamber, and the smoke exhaust pipe is sleeved on the surface of the air pipe. It is characterized by: The front end of the burner tube is connected with a heat exchange tube. The inner and outer surfaces of the heat exchange tube are equipped with heat exchange fins. One end of the heat exchange tube is connected to the air guide tube, and the other end of the heat exchange tube extends to the spray outlet and the nozzle. An annular gap is formed between the outlets, and the other end of the gas channel is sleeved with a spring and fixed in the burner tube through the spring. There is a gas pipe in the gas channel. One end of the gas pipe is connected to the outside of the burner pipe, and the other end of the gas pipe is connected to a shunt. The diverter is arranged in the combustion chamber. One end of the diverter is connected to the main gas pipe and extends to the outlet. The surface of the diverter is provided with a diverter hole that connects the combustion chamber and the gas pipe. The outer surface of the air pipe is provided with heat exchange fins.

Preferably, it also includes a wind disk, which is sleeved on the surface of the manifold. The surface of the wind disk is provided with an air duct along the circumferential direction, and the air duct communicates with the combustion chamber and the burner tube.

Preferably, the air ducts include circular air ducts and strip-shaped air ducts, and the circular air ducts and strip-shaped air ducts are alternately distributed.

Preferably, a stopper is also provided in the air tube, and the stopper is arranged along the extending direction of the air tube.

Preferably, the surface of the stopper is provided with heat exchange fins.

Preferably, the surface of the spring is covered with a thermal insulation lining.

Preferably, the surface of the rear end of the burner tube is provided with a cooling air hole that communicates with the air guide tube and the inside of the burner tube.

Preferably, the diverter holes are distributed along the circumferential direction of the diverter with the gas channel axis as the center.

In order to achieve the above object, the second technical solution adopted by the present invention is to provide a two-stage heat exchange low NOx self-preheating burner, including a burner tube, a combustion chamber, an air pipe, a gas channel, a smoke exhaust pipe, and an ignition device. , the surface of the rear end of the burner tube is sleeved with an air guide pipe and connected with the air pipe. The surface of the air guide pipe is sleeved with a smoke guide pipe and connected with the smoke exhaust pipe. One end of the combustion chamber is provided with a spout, and the combustion chamber is set in the burner pipe. And the nozzle extends to the outside of the front end of the burner tube, the gas channel is set in the burner tube and one end of it is connected to the combustion chamber, the ignition end of the ignition device is set in the combustion chamber, the exhaust pipe is sleeved on the surface of the air pipe, and the burner tube The front end is sleeved with a heat exchange tube, and the inner and outer surfaces of the heat exchange tube are equipped with heat exchange fins. One end of the heat exchange tube is connected to the air guide tube, and the other end of the heat exchange tube extends to the outlet to form a ring. gap, the other end of the gas channel is sleeved with a spring and fixed in the burner pipe through the spring. There is a main gas pipe and an auxiliary gas pipe in the gas channel. The main gas pipe is set in the auxiliary gas pipe. One end of the auxiliary gas pipe is connected to the burner. The other end of the auxiliary gas pipe is connected to a diverter and is installed in the combustion chamber. The surface of the diverter is provided with a diverter hole that connects the combustion chamber and the auxiliary gas pipe. One end of the main gas pipe is connected to the outside of the burner pipe. The main gas pipe is connected to the outside of the burner pipe. The other end of the tube runs through the diverter and extends to the outlet. The outer surface of the air tube is provided with heat exchange fins.

The beneficial effects of the present invention are:

1. By setting heat exchange fins and heat exchange tubes at the front end of the burner tube, and setting heat exchange fins on the outer surface of the air tube, the high-temperature gas after burning in the burner flows back to the burner through the heat exchange fins and heat exchange tubes. The combustion air in the burner tube is heat exchanged, and then when it is discharged through the exhaust pipe, the combustion air entering from the air pipe mouth is heat exchanged through the heat exchange fins provided on the outer surface of the air pipe, that is, the combustion air is processed in two stages. Heat exchange effectively improves the efficiency of heat exchange, maximizes the temperature of preheated air, uses the waste heat of flue gas to fully preheat the combustion air, improves combustion efficiency, and reduces the production of NOx;

2. By setting a diverter in the combustion chamber and a diverter hole on the diverter, a single main gas pipe can be connected to the diverter or a main gas pipe and an auxiliary gas pipe can be set up at the same time according to the needs of the combustion method. The auxiliary gas pipe The pipe is connected to the splitter hole, and the main gas pipe is set in the auxiliary gas pipe for separate air intake. Different combustion modes are set according to needs to improve combustion efficiency, reduce the production of NOx, and achieve the purpose of energy saving and emission reduction;

3. Under the premise of gas classification and combined with air classification technology, most of the combustion-supporting air enters the burner tube from the air pipe and reaches the combustion chamber, and is mixed with the gas entering the combustion chamber. Some of the combustion-supporting air enters the heating space from the annular air gap and mixes with it. The gas near the nozzle, primary combustion products and part of the return flue gas in the heating space are mixed and then burned again to form a high-speed flame. The high-speed flame can entrain the surrounding flue gas to participate in the combustion, which can effectively reduce the flame combustion temperature. Thereby reducing the production of NOx;

4. By inserting a spring on the surface of the gas channel and fixing it in the burner tube through the spring, the safety and stability of the gas system structure can be ensured when the internal device of the burner is displaced due to thermal expansion, thus improving the practical life and stability of the overall equipment. Safety of use.

Description of drawings

Figure 1 is a cross-sectional view of the internal structure of Embodiment 1;

Figure 2 is an enlarged schematic diagram of point A in Figure 1;

Figure 3 is a schematic structural diagram of the wind disk;

Figure 4 is a schematic diagram of installation using direct open flame heating in Embodiment 1;

Figure 5 is an installation schematic diagram of indirect heating using radiant tubes in Embodiment 1;

Figure 6 is a schematic structural diagram of Embodiment 2.

Detailed ways

Embodiment 1

Please refer to Figure 1. This embodiment is about a two-stage heat exchange low NOx self-preheating burner, including a burner tube 1, a combustion chamber 21, an air pipe 14, a gas channel 11, a smoke exhaust pipe 3, an ignition In the device 23, the surface of the rear end of the burner tube 1 is sleeved with an air guide pipe 16. The air pipe 14 is arranged on the surface of the air guide pipe 16 and connected with it. An air port 4 is provided at the mouth of the air pipe 14. The surface of the air guide pipe 16 is sleeved with The smoke guide pipe 25 and the smoke exhaust pipe 3 are arranged on the surface of the smoke guide pipe 25 and connected with it. The side wall of the smoke exhaust pipe 3 is provided with a smoke exhaust port 5. One end of the combustion chamber 21 is provided with an ejection port 30. One end is fixedly arranged in the burner tube 1 through the support 20, and the nozzle 30 extends to the outside of the front end of the burner tube 1. The gas channel 11 is arranged in the burner tube 1 and one end thereof is fixed on the support 20. The ignition device 23 The ignition end is extended in the combustion chamber 21, and the exhaust pipe 3 is sleeved on the surface of the air pipe 14.

The front end of the burner tube 1 is connected to a heat exchange tube 17. The inner and outer surfaces of the heat exchange tube 17 are provided with heat exchange fins. One end of the heat exchange tube 17 is connected to the air guide tube 16, and the other end of the heat exchange tube 17 is connected with the air guide tube 16. An annular gap 32 is formed between the outlet 30 and the outlet 30. The other end of the gas channel 11 is sleeved with a spring 10 and fixed in the burner tube 1 through the spring 10. A gas shell 7 is provided outside the burner tube 1. , a gas port 6 is provided on the gas housing 7, and an external gas supply device is connected to the gas port 6 to provide gas. A gas pipe 35 is provided in the gas channel 11. One end of the gas pipe 35 is connected to the gas port 6, and the other end of the gas pipe 35 is connected to the gas port 6. One end of the diverter 34 is connected to a diverter 34 and is arranged in the combustion chamber 21. One end of the diverter 34 is connected to the main gas pipe 12 and extends to the injection port 30. The diverter 34 is provided with a diverter hole 13 on the surface that communicates with the combustion chamber 21 and the gas pipe 35. , heat exchange fins 36 are provided on the outer surface of the air tube 14.

During the specific application process of this embodiment, the burner can be directly fixed on the side wall of the heating space through the mounting flange 9, so that the burner can be extended into the heating space, that is, the installation method of direct open flame heating is used (as shown in Figure 4 (shown in Figure 5). At the same time, the radiant tube can also be sleeved on the surface of the burner, that is, it can be installed by indirect heating (shown in Figure 5).

The specific working principle of this embodiment is as follows:

A. Gas enters the gas pipe 35 from the gas port 6. The main gas passes through the main gas pipe 12 of the diverter 34. After being diverted through the diverter hole 13 of the diverter 35, it becomes the auxiliary gas. The main gas is sprayed from the nozzle 30 through the main gas pipe 12. out and into the heating space, and the auxiliary gas enters the combustion chamber 21;

B. The combustion-supporting air enters the air pipe 14 through the air port 4. When the combustion-supporting air travels, it passes through the heat exchange fins 36 on the outside of the air pipe 14 and exchanges heat with the flue gas in the exhaust pipe 3, and then enters the heat exchange pipe through the air guide pipe 16. 17. Secondary heat exchange is performed between the heat exchange fins on the inner and outer surfaces of the heat exchange tube 17 and the flue gas returning in the heating space. Then the combustion air is diverted in the combustion chamber 21, and one stream is the primary air, which flows back to the burner tube 1 The internal space then enters the combustion chamber 21 through the support 20 to mix with the auxiliary gas; the other is the secondary air, which enters the heating space through the annular gap 32 and mixes with the main gas (as shown in Figure 2);

C. After the primary air and auxiliary gas are mixed in the combustion chamber 21, they are ignited and burned through the ignition device 23 to form a first-level combustion product ejected from the nozzle 30; the main gas mixes with the first-level combustion product and the first-level combustion product in the annular gap 32 near the nozzle 30. The secondary air and part of the return flue gas in the heating space are mixed and then undergo secondary combustion. The overall process is a double-stage combustion mode.

D. The flue gas flows back from the heating space. After exchanging heat with the combustion air through the heat exchange fins on the outer surface of the heat exchange tube 17, it enters the smoke guide 25 and then passes through the exhaust pipe 3 and is discharged from the exhaust port 5. It flows through the exhaust During the smoke pipe 3 process, the heat exchange fins 36 on the surface of the air pipe 14 exchange heat with the combustion air.

Please refer to Figures 1 and 3. This embodiment also includes a wind disk 22. The wind disk 22 is sleeved on the surface of the diverter 34. The surface of the wind disk 22 is provided with an air duct along the circumferential direction. The air duct communicates with the combustion chamber 21 and Burner tube 1. After the combustion air is exchanged through the heat exchange tube 17, part of it flows back into the burner tube 1. The combustion air passes through the air duct of the air disk 22 and evenly enters the combustion chamber 21, which can effectively strengthen the interaction between the combustion air and the auxiliary gas in the combustion chamber 21. Mixing to improve combustion conditions, in order to further improve the mixing uniformity of gas and combustion air, the air ducts are alternately distributed in circular air duct B and strip air duct A.

Furthermore, in this embodiment, a limiter 15 is also provided in the air tube 14. The limiter 15 is arranged along the extending direction of the air tube 14. The top end of the limiter 15 is connected to the air port 4 through a fixed bracket 27. The air tube 14 passes through The bellows 28 is connected to the air port 4. The purpose of setting the limiter 15 is that when the combustion air enters the air pipe 14 from the air port 4, the incoming combustion air is diverted to the surroundings of the limiter 15 due to the action of the limiter 15. To improve the heat exchange efficiency of the combustion air, the limiter 15 can be set to be solid or hollow; in order to further improve the heat exchange efficiency of the combustion air, a heat exchanger can be provided on the surface of the limiter 15. Thermal Fin 36.

In this embodiment, the surface of the spring 10 is covered with a thermal insulation lining 26. Since the combustion air has a very high temperature after undergoing secondary heat exchange, and part of it will enter the burner tube 1, the surface of the spring 10 is covered with a thermal insulation lining 26. The thermal insulation lining 26 can protect the spring 10 from excessive high temperature and prevent it from being damaged.

Furthermore, the surface of the rear end of the burner tube 1 is provided with a cooling air hole 19 that communicates with the air guide tube 16 and the inside of the burner tube 1. The combustion-supporting air enters the air guide tube 16 after one heat exchange in the air tube 14, and a small part only passes through one heat exchange. The relatively low-temperature combustion air enters the burner tube 1 through the cooling holes 19, which can cool the spring 10, the thermal insulation lining 26, and the gas channel 11 in the burner tube 1 to prevent damage due to excessive temperature. In addition, This part of the combustion air then enters the combustion chamber 21 and mixes with the auxiliary gas in the combustion chamber 21 .

As a preferred embodiment, the diverter holes 13 in the diverter 34 are distributed along the circumferential direction of the diverter 34 with the axis of the gas channel 11 as the center, so that the auxiliary gas entering the combustion chamber 21 can be evenly distributed and better interact with the combustion air. Mixed to improve combustion efficiency.

Embodiment 2

The difference between this embodiment and the first embodiment is that the gas housing 7 is provided with a main gas port 61 and an auxiliary gas port 6 respectively, and an external gas supply device is connected to the main gas port 61 and the auxiliary gas port 6 to provide gas.

The gas channel 11 is provided with a main gas pipe 12 and an auxiliary gas pipe 121. The main gas pipe 12 is arranged in the auxiliary gas pipe 121. One end of the auxiliary gas pipe 121 is connected to the auxiliary gas port 6, and the other end of the auxiliary gas pipe 121 is connected. There is a diverter 34 arranged in the combustion chamber 21. The surface of the diverter 34 is provided with a diverter hole 13 that communicates with the combustion chamber 21 and the auxiliary gas pipe 121; one end of the main gas pipe 12 is connected with the main gas port 61, and the other end of the main gas pipe 12 is connected with the main gas port 61. One end passes through the diverter 34 and extends to the outlet 30 .

In this embodiment, the auxiliary gas pipe 121 and the main gas pipe 12 are respectively provided, and the auxiliary gas port 6 and the main gas port 61 are correspondingly provided in the gas housing 7. The structure can flexibly control the gas supply mode and form different combustion modes. modes to suit different combustion needs.

The principle is explained below through specific combustion modes.

According to the control method, three combustion modes can be formed: only auxiliary gas is fed, only main gas is fed, and main and auxiliary gas are fed simultaneously, which can correspond to three heating modes: low temperature mode, rapid heating, and high temperature mode.

low temperature mode

The ignition device 23 is turned on, the auxiliary gas port 6 is opened for air intake, the main gas port 61 is closed, the combustion air has not yet been preheated, and ignition is started in the cold state for heating, the combustion is sufficient, there is no high temperature zone, and the amount of NOx generated is small; it should be noted that, During the period from the initial operation of the low-temperature mode burner to normal combustion, the furnace temperature gradually rises from room temperature; NOx is divided into three categories: thermal type, rapid type and fuel type. Only thermal type NOx accounts for the largest proportion of NOx produced by gaseous fuel combustion. Dominant, accounting for 90%, thermal NOx is only related to the high temperature zone, that is, the combustion temperature is greater than 850 degrees.

Rapid heating mode: The ignition device 23 is turned on, both the main gas port 61 and the auxiliary gas port 6 are opened for air intake, the combustion air has been preheated, and when rapid heating is required, it is a double-stage combustion with sufficient combustion and low NOx generation; The dual-stage combustion is air classification and gas classification, which is consistent with the principle in Embodiment 1. The difference is that in this embodiment, the two gas inlets control the main and auxiliary gases respectively.

High temperature mode: The ignition device 23 is closed, the auxiliary gas port 6 is closed, and the main gas port 61 is opened. When the temperature in the heating space is higher than 850 degrees, the air-fuel mixture is directly sprayed into the heating space, and the overall flameless oxidation is performed, entering the flameless mode. In the combustion state, the temperature is uniform, there are no local high temperature areas, and the amount of NOx generated is small.

In this embodiment, the opening or closing of the main gas port 61 and the auxiliary gas port 6 can be controlled by the solenoid valve. The solenoid valve is controlled by an external control system. The ignition of the ignition device is also controlled by the external control system.

The above embodiments are only descriptions of preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, ordinary engineers and technicians in the art may make various modifications and modifications to the technical solutions of the present invention. Improvements should fall within the protection scope determined by the claims of the present invention.

Claims (9)

1. A two-stage heat exchange low NOx self-preheating burner, including a burner tube, a combustion chamber, an air tube, a gas channel, a smoke exhaust pipe, and an ignition device. The surface of the rear end of the burner tube is sleeved with an air guide tube and It is connected with the air pipe. The surface of the air guide pipe is sleeved with a smoke guide pipe and connected with the smoke exhaust pipe. One end of the combustion chamber is provided with a spout. The combustion chamber is arranged in the burner pipe and the spout extends to the outside of the front end of the burner pipe. The gas channel It is arranged in the burner tube and one end thereof is connected with the combustion chamber. The ignition end of the ignition device is arranged in the combustion chamber. The exhaust pipe is sleeved on the surface of the air pipe. The characteristic is that the front end of the burner pipe is sleeved with a heat exchange pipe. One end of the heat pipe is connected to the air guide pipe, and the other end of the heat exchange pipe extends to the spout to form an annular gap between the spout and the spout. The other end of the gas channel is sleeved with a spring and is fixed in the burner tube through the spring. In the gas channel A gas pipe is provided. One end of the gas pipe is connected to the outside of the burner pipe. The other end of the gas pipe is connected to a diverter and is installed in the combustion chamber. One end of the diverter is connected to the main gas pipe and extends to the outlet. The surface of the diverter is provided with a gas pipe. The split hole connects the combustion chamber and the gas pipe, and the outer surface of the air pipe is provided with heat exchange fins. 2. The two-stage heat exchange low NOx self-preheating burner according to claim 1, characterized in that it also includes a wind disk, the wind disk is sleeved on the surface of the diverter, and the surface of the wind disk is provided with a circumferential direction. The air duct connects the combustion chamber and the burner tube. 3. The two-stage heat exchange low NOx self-preheating burner according to claim 2, wherein the air duct includes a circular air duct and a strip-shaped air duct, and the circular air duct and the strip-shaped air duct are Alternating distribution of channels. 4. The two-stage heat exchange low NOx self-preheating burner according to any one of claims 1 to 3, characterized in that a limiter is also provided in the air pipe, and the limiter is arranged along the extension direction of the air pipe. . 5. The two-stage heat exchange low NOx self-preheating burner according to claim 4, characterized in that the surface of the limiter is provided with heat exchange fins. 6. The two-stage heat exchange low NOx self-preheating burner according to claim 4, characterized in that the surface of the spring is covered with a thermal insulation lining. 7. The two-stage heat exchange low NOx self-preheating burner according to claim 6, characterized in that the surface of the rear end of the burner tube is provided with a cooling air hole connecting the air guide tube and the burner tube. 8. The two-stage heat exchange low NOx self-preheating burner according to claim 1, characterized in that the diverter holes are distributed along the circumferential direction of the diverter with the gas channel axis as the center. 9. A two-stage heat exchange low NOx self-preheating burner, including a burner tube, a combustion chamber, an air tube, a gas channel, a smoke exhaust pipe, and an ignition device. The surface of the rear end of the burner tube is sleeved with an air guide tube and It is connected with the air pipe. The surface of the air guide pipe is sleeved with a smoke guide pipe and connected with the smoke exhaust pipe. One end of the combustion chamber is provided with a spout. The combustion chamber is arranged in the burner pipe and the spout extends to the outside of the front end of the burner pipe. The gas channel It is arranged in the burner tube and one end thereof is connected with the combustion chamber. The ignition end of the ignition device is arranged in the combustion chamber. The exhaust pipe is sleeved on the surface of the air pipe. The characteristic is that the front end of the burner pipe is sleeved with a heat exchange pipe. Heat exchange fins are provided on both the inner and outer surfaces of the heat pipe. One end of the heat exchange pipe is connected to the air guide pipe. The other end of the heat exchange pipe extends to the outlet and forms an annular gap between the outlet and the other end of the gas channel. There is a spring and is fixed in the burner pipe through the spring. There is a main gas pipe and an auxiliary gas pipe in the gas channel. The main gas pipe is set in the auxiliary gas pipe. One end of the auxiliary gas pipe is connected to the outside of the burner pipe, and the other end of the auxiliary gas pipe is connected to the outside of the burner pipe. One end is connected to a diverter and installed in the combustion chamber. The surface of the diverter is provided with a diverter hole that connects the combustion chamber and the auxiliary gas pipe. One end of the main gas pipe is connected to the outside of the burner pipe, and the other end of the main gas pipe runs through the diverter and extends to At the outlet, heat exchange fins are provided on the outer surface of the air tube.