CN111981478B - Low nitrogen burner, low nitrogen combustion system and combustion method thereof - Google Patents

Abstract

The present invention provides a low-nitrogen burner, including an outer tube and an inner tube, one end of the outer tube is a fire outlet, and the other end is an air inlet, the air inlet is provided with a combustion-supporting gas interface, the inner tube is inserted into the outer tube, and a gas interface is provided on the inner tube, the low-nitrogen burner includes an exhaust gas re-inhalation structure, the exhaust gas re-inhalation structure includes an exhaust gas re-inhalation pipe cover and an exhaust gas exhaust device, the exhaust gas re-inhalation pipe cover is installed on the outer peripheral wall of the fire outlet of the outer tube, and an exhaust gas re-inhalation hole is opened thereon, the exhaust gas exhaust device is connected to the exhaust gas re-inhalation pipe cover, the exhaust gas exhaust device exhausts air, and the exhaust gas that swirls back to the rear of the fire outlet after combustion is sucked into the exhaust gas re-inhalation pipe cover and transmitted to the fire outlet of the outer tube, the transmitted exhaust gas is mixed with the combustion-supporting gas introduced by the outer tube and the fuel gas introduced by the inner tube, and burns in the fire outlet. The present invention also provides a low-nitrogen combustion system and a combustion method thereof. The low-nitrogen burner of the present invention has the advantages of energy saving and low nitrogen.

Description

Low nitrogen burner, low nitrogen combustion system and combustion method thereof

Technical Field

The present invention relates to the technical field of low-nitrogen combustion of gas boilers, and in particular to a low-nitrogen burner, a low-nitrogen combustion system and a combustion method thereof.

Background Art

A large amount of nitrogen oxides (NOx) will be produced during the combustion process, causing serious damage to the ecological environment.

At present, in industrial furnaces, heating in the furnace is achieved by installing a burner on the furnace body, with the burner nozzle facing the furnace body, inputting combustion-supporting gas through the burner's combustion-supporting pipe, and inputting fuel through the fuel pipe, mixing at the burner nozzle and igniting and burning, so as to achieve heating by burning flame in the furnace. The flame temperature is high, and the amount of nitrogen oxides generated is also high. Generally, when the combustion temperature exceeds 350°, more nitrogen oxides will be generated. At present, most local environmental protection bureaus have strict emission control requirements for the emission of nitrogen oxides, such as the emission standards for nitrogen oxides emitted by newly built boilers mentioned in the background technology of CN106594716. Flue gas recirculation technology is a technology that is currently commonly used to reduce flame temperature. It can reduce the generation of nitrogen oxides. That is, the exhausted exhaust gas is re-inhaled into the combustion chamber of the burner, thereby reducing the oxygen concentration and reducing the temperature during combustion. The above-mentioned flue gas recirculation technology has been disclosed in CN106594716 patent and many other patent technologies such as CN106287696. Its structural principle is mostly shown in Figure 1. By directly connecting an exhaust gas circulation pipe 2A to the exhaust port of the furnace 1A, a large amount of exhaust gas from the exhaust port is absorbed and introduced into the burner 3A. The exhaust gas is mixed with the combustion-supporting gas and the fuel gas for combustion. Since the oxygen content in the exhaust gas is low and the content of non-combustion-supporting carbon dioxide, nitrogen oxides, etc. is high, the oxygen concentration in the combustion-supporting gas in the combustion chamber will be reduced. In this way, the combustion temperature will be reduced during combustion, thereby reducing the generation of nitrogen oxides and controlling the emission of nitrogen oxides. In the above flue gas recirculation method, the exhaust gas circulation pipe connects the exhaust port at the rear end of the furnace and the burner at the front end of the furnace. The exhaust gas circulation pipe is very long and exposed to the external environment. When the outside temperature is low or the boiler is not in use, condensed water is easily formed in the water vapor in the exhaust gas in the pipe. Especially in winter in the north, the condensed water vapor condenses on the pipe wall and easily corrodes the pipe, and the exhaust gas circulation pipe often needs to be repaired and replaced. In addition, the layout of the exhaust gas circulation pipe requires a large site space. Some boilers are equipped with a large area of exhaust gas circulation pipelines, which makes the overall structure complicated, which not only increases the investment, but also is not convenient for construction and installation as well as maintenance and management after installation.

Summary of the invention

In view of the above, the present invention provides a durable low-nitrogen burner that does not require maintenance or replacement of the exhaust gas circulation pipe.

The technical solution involved in the present invention:

A low-nitrogen burner comprises an outer tube and an inner tube, one end of the outer tube is a fire outlet end, and the other end is an air inlet end, the air inlet end is provided with a combustion-supporting gas interface, the inner tube is inserted into the outer tube, and a gas interface is provided on the inner tube, so that the combustion-supporting gas introduced by the outer tube and the gas introduced by the inner tube are mixed in the fire outlet end of the outer tube and then ignited and burned. The low-nitrogen burner comprises an exhaust gas back-inhalation structure, the exhaust gas back-inhalation structure comprises an exhaust gas back-inhalation pipe cover and an exhaust gas exhaust device, the exhaust gas back-inhalation pipe cover is installed on the outer peripheral wall of the fire outlet end of the outer tube, and an exhaust gas back-inhalation hole is opened on it, the exhaust gas exhaust device is connected to the exhaust gas back-inhalation pipe cover, the exhaust gas exhaust device exhausts air, and the exhaust gas that swirls back to the rear of the fire outlet end after combustion is sucked into the exhaust gas back-inhalation pipe cover and transmitted to the fire outlet end of the outer tube, the transmitted exhaust gas is mixed with the combustion-supporting gas introduced by the outer tube and the gas introduced by the inner tube, and burns in the fire outlet end.

Furthermore, the exhaust gas re-inhalation structure includes an exhaust gas reflow pipe, which is inserted into the inner tube. The exhaust gas exhaust device is connected to the exhaust gas re-inhalation pipe cover through one end of the pipeline and the other end is connected to the exhaust gas reflow pipe.

Furthermore, the fire outlet end has a combustion space section, the inner tube has a gas outlet end, the outer peripheral wall of the gas outlet end is connected to a premixing tube, and the other end of the premixing tube extends to the combustion space section.

Furthermore, the gas outlet end of the inner tube extends to an adjacent position to the premixing tube, and the exhaust gas return pipe extends to an adjacent position to the combustion space section.

Furthermore, the premixing tube has an inner edge at one end that is fixedly connected to the outer circumferential wall of the inner tube outlet end, and an outer edge at the other end that is fixedly connected to the inner circumferential wall of the outer tube. An air vent is provided on the inner edge to allow the combustion-supporting gas portion that enters the outer tube to enter the premixing tube, and an air through hole is provided on the outer edge to allow the combustion-supporting gas portion that enters the outer tube to enter the combustion space section for combustion.

Furthermore, the air holes adopt a spiral channel structure.

Furthermore, the exhaust gas back-intake structure further includes a heat exchanger, the heat exchanger has a first air inlet interface, a first air outlet interface, a second air inlet interface and a second air outlet interface, the first air inlet interface is connected to the air outlet interface of the exhaust gas back-intake pipe cover, the first air outlet interface is connected to the exhaust gas exhaust device, a combustion-supporting gas delivery device is connected to the second air inlet interface, and the second air outlet interface is connected to the combustion-supporting gas interface.

A low-nitrogen combustion system includes a furnace body and a low-nitrogen burner installed on the furnace body. The furnace body has a furnace, a nozzle hole is opened on the front furnace wall of the furnace body, and a smoke window is arranged at the top of the furnace body adjacent to the rear furnace wall to discharge the waste gas in the furnace after combustion. The low-nitrogen burner adopts the low-nitrogen burner, which is installed on the front furnace wall of the furnace body, and the port of the fire outlet end of the outer tube extends into the furnace.

A combustion method using the low-nitrogen combustion system comprises the following steps:

Start the combustion-supporting gas delivery device, the fuel gas delivery device and the exhaust gas exhaust device, fill the fuel gas into the inner tube through the fuel gas interface, and fill the combustion-supporting gas into the outer tube through the combustion-supporting gas interface;

The fuel gas and the combustion-supporting gas are premixed, the premixed gas is ignited, and fully burned in the combustion space section at the fire outlet;

The flame generated by the combustion is ejected from the fire outlet end into the furnace of the furnace body, forming a waste gas reflux in the furnace that is opposite to the flame ejection direction and is formed after the flame burns. The waste gas reflux is sucked into the waste gas return suction pipe cover at the fire outlet end of the outer tube through the waste gas exhaust device, and is transported to the waste gas reflux pipe, and refluxes into the combustion space section of the fire outlet end of the outer tube.

A combustion method for a low-nitrogen combustion system comprises the following steps: when the low-nitrogen combustion system is equipped with a heat exchanger, a combustion-supporting gas conveying device conveys the combustion-supporting gas through the heat exchanger and then enters an outer tube, and the exhaust gas enters the exhaust gas return pipe after passing through the exhaust gas return suction pipe cover, so that the combustion-supporting gas and the exhaust gas achieve heat exchange.

Compared with the traditional low-nitrogen combustion device, the above-mentioned low-nitrogen burner can fully absorb and utilize the combustion swirling exhaust gas by arranging an exhaust gas re-inhalation structure at the fire end, so as to achieve the requirement of lowering the combustion temperature and meet the control of the generation of nitrogen oxides. It fully breaks through the traditional belief that exhaust gas must be concentrated at the smoke exhaust port and will not return to the vicinity of the fire end. Since the smoke exhaust port must be far away from the fire end, otherwise the smoke exhaust port will directly discharge the heat of combustion. Through observation and experimental summary, the applicant understands that part of the burned exhaust gas will swirl to the vicinity of the fire end (i.e. the outer periphery of the outer tube). In this way, the above-mentioned exhaust gas re-inhalation structure is designed to be arranged at the periphery of the fire end to re-inhale the exhaust gas in the furnace, which can also achieve the effect of suppressing the generation of nitrogen oxides and meet the temperature effect required by the furnace. Compared with the prior art, the use of the traditional exhaust gas circulation pipe for introducing the exhaust gas from the smoke window into the burner can be completely avoided, thereby avoiding the problem of exhaust gas circulation pipe being damaged due to condensation. The low-nitrogen combustion system using the low-nitrogen burner of the present application has a simple structure and does not require an exhaust gas circulation pipe placed outside. The overall structure is simple and compact, occupies little space, is easy to arrange, and reduces the overall manufacturing difficulty and cost of the boiler.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an existing low nitrogen combustion system;

FIG2 is a schematic cross-sectional view of a low nitrogen burner according to the present invention;

FIG3 is a partial cross-sectional enlarged view of a low nitrogen burner of the present invention;

FIG4 is a perspective view of a low-nitrogen energy-saving combustion system according to the present invention;

FIG5 is a partial cross-sectional schematic diagram of a low-nitrogen energy-saving combustion system of the present invention from a first viewing angle;

FIG6 is a partial cross-sectional schematic diagram of the low-nitrogen energy-saving combustion system of the present invention from a second viewing angle.

DETAILED DESCRIPTION

The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the protection scope of the present invention.

Please refer to Figures 2 and 3. The present invention provides a low-nitrogen burner, including an outer tube 1, an inner tube 2 and an exhaust gas re-absorption structure 3. The outer tube 1 is provided with a combustion-supporting gas interface 11, and the inner tube 2 is inserted into the outer tube 1. The inner tube 2 is provided with a gas interface 21, so that the combustion-supporting gas introduced by the outer tube 1 and the gas introduced by the inner tube 2 are mixed in the fire outlet and ignited and burned. The exhaust gas re-absorption structure 3 includes an exhaust gas re-absorption pipe cover 31 and an exhaust gas exhaust device 3 2. The exhaust gas return suction pipe cover 31 is sleeved on the outer peripheral wall of the outer tube 1, and an exhaust gas return suction hole 311 is opened on it. The exhaust gas exhaust device 32 is connected to the exhaust gas return suction pipe cover 31. The exhaust gas exhaust device 32 exhausts the exhaust gas that swirls back to the rear of the fire outlet after combustion, sucks it into the exhaust gas return suction pipe cover 31 and transmits it to the fire outlet of the outer tube 1. The transmitted exhaust gas is mixed with the combustion-supporting gas introduced by the outer tube 1 and the combustion gas introduced by the inner tube 2, and burns in the fire outlet.

One end of the outer tube 1 is a fire outlet end, and the other end is an air inlet end. The fire outlet end is for the combustion flame to be ejected, and has a combustion space section 101. The air inlet end port is closed and only allows the inner tube 2 to pass through. The outer peripheral wall of the air inlet end is provided with the said supporting combustion gas interface 11 for connecting the supporting combustion gas delivery device 35 to input the supporting combustion gas into the outer tube 1.

One end of the inner tube 2 is the air outlet end, and the other end is the air inlet end. The inner tube 2 extends into the outer tube 1 through the end wall of the air inlet end of the outer tube 1, and the air inlet end is exposed on the outer tube 1, and its air outlet extends to the combustion space section 101 of the outer tube 1. The port of the air inlet end of the inner tube 2 is closed, and the gas interface 21 is provided on the outer peripheral wall of the air inlet end. The outer peripheral wall of the air outlet end of the inner tube 2 is connected to the premixing tube 4. The diameter of the premixing tube 4 is larger than the outer diameter of the inner tube 2 and smaller than the inner diameter of the outer tube 1. One end of the premixing tube 4 is formed with an inner end edge fixedly connected to the outer peripheral wall of the air outlet end of the inner tube 2, and the other end is formed with an outer end edge fixedly connected to the inner peripheral wall of the outer tube 1. A vent hole 41 is provided on the inner end edge to allow the part of the combustion-supporting gas entering the outer tube 1 to enter the premixing tube 4, and the outer end edge is provided with an air hole 42 to allow the part of the combustion-supporting gas entering the outer tube 1 to enter the combustion space section 101 for combustion. Furthermore, in order to fully mix and burn the airflow in the combustion space section 101, the air holes 42 adopt a spiral channel structure, and several air holes 42 adopt the same spiral direction. In this way, the combustion-supporting gas entering the combustion space section 101 from the air holes 42 is in a spiral wind, which can improve the mixing effect and ensure sufficient combustion. The flame can spread farther outward from the combustion space section 101, which is more conducive to furnace heating.

First, part of the combustion-supporting gas is premixed with the fuel gas in the premixing pipe 4 and ignited to ensure that it is not easy to go out after ignition. Then, the combustion-supporting gas enters the combustion space section 101 and is fully mixed and burned with another part of the combustion-supporting gas entering the combustion space section 101.

It can be understood that the electric spark ignition device (not shown) is arranged in the premixing tube 4, and the premixed gas in the premixing tube 4 can be ignited by electronic sparks.

It can be understood that in order to fully premix the gas and the combustion-supporting gas entering the premixing tube 4, the end of the inner tube 2 accommodated in the premixing tube 4 should not be too long. Preferably, it can extend to the adjacent position of the premixing tube 4. In this embodiment, the inner tube 2 extends roughly to the adjacent position of the premixing tube 4 and slightly beyond.

The exhaust gas return suction pipe cover 31 is in the shape of a tube, which is sleeved on the outer peripheral wall of the fire end of the outer tube 1, including a tube part and ring plates formed at both ends of the tube part, and the ring plates are fixedly connected to the outer peripheral wall of the outer tube 1, wherein the exhaust gas return suction hole 311 is opened on the ring plate in the same direction as the fire end, so that the exhaust gas can enter the tube part of the exhaust gas return suction pipe cover 31; an air outlet interface is provided on the peripheral wall of the tube part, and the exhaust gas exhaust device 32 is connected to the air outlet interface to discharge the exhaust gas in the tube part and transport it to the combustion space section in the outer tube 1.

The exhaust gas re-inhalation structure 3 also includes an exhaust gas return pipe 33, one end of the exhaust gas return pipe 33 passes through the closed end of the inner tube 2, passes through the other end of the inner tube 2 and extends to the combustion space section 101, and the other end is connected to the exhaust gas exhaust device 32 so that the exhaust gas exhaust device 32 can guide the burned exhaust gas into the combustion space section 101 in the outer tube 1.

It can be understood that, preferably, in order to ensure that the premixed gas in the premixing tube is well ignited and not easily extinguished after ignition, the exhaust gas return pipe 33 passes through the premixing tube 4 to introduce the exhaust gas into the combustion space section, otherwise the exhaust gas return pipe 33 can be extended into the premixing tube 4. Further, a conical wall is provided at the port of one end of the inner tube 2 connected to the premixing tube 4 and fixedly connected to the outer periphery of the exhaust gas return pipe 33, and a vent hole 22 is opened on the conical wall, so that the combustion gas in the inner tube 2 can enter the premixing tube 4 through the vent hole 22.

The exhaust gas re-absorption structure 3 further includes a heat exchanger 34, which includes a heat exchange box and a heat exchange tube installed in the box, and the heat exchange box is provided with a first air inlet interface and a first air outlet interface, a second air inlet interface and a second air outlet interface, the first air inlet interface is connected to the heat exchange tube, and the first air outlet interface is connected to the heat exchange tube, so that the airflow entering from the first air inlet interface flows out from the first air outlet interface after passing through the heat exchange tube, and the airflow entering from the second air inlet interface flows out from the second air outlet interface after passing through the box. The first air inlet interface is connected to the air outlet interface of the exhaust gas re-absorption pipe cover 31, and the first air outlet interface is connected to the exhaust gas exhaust device 32, so that the exhaust gas exhaust device 32 transports the exhaust gas sucked from the exhaust gas re-absorption pipe cover 31 through the heat exchanger to achieve heat exchange of the exhaust gas. In addition, a heat exchanger 34 is arranged before the exhaust gas exhaust device 32 to reduce the temperature of the exhaust gas entering the exhaust gas exhaust device 32, thereby protecting the exhaust gas exhaust device 32 from being damaged by high temperature. Otherwise, the high-temperature exhaust gas directly enters the exhaust gas exhaust device 32, which may easily damage the exhaust gas exhaust device 32, and the motor of the exhaust gas exhaust device 32 may easily burn out in a high temperature environment.

Heat exchange can be carried out with the combustion-supporting gas delivered to the combustion-supporting gas interface 11 from the outside. Specifically, a combustion-supporting gas delivery device 35 is connected to the second air inlet interface, and the second air outlet interface is connected to the combustion-supporting gas interface 11. In this way, the delivered combustion-supporting gas can be heat-exchanged with the waste gas with higher temperature through the heat exchanger to preheat the delivered combustion-supporting gas, thereby making full use of the thermal energy of the combustion-supporting gas and achieving energy-saving effect.

In addition, in order to facilitate the processing of the low-nitrogen burner, the inner tube 2, the exhaust gas return pipe 33, the premixing tube 4 and the end edges of the premixing tube 4 are first processed into a whole, and then the inner tube 2 is installed on the outer tube 1. In order to facilitate the assembly of the inner tube 2 and the outer tube 1 of the low-nitrogen burner, a first flange is formed on the outer periphery of the air inlet end of the outer tube 1, and a second flange 7 is formed on the outer peripheral wall of the air inlet end of the inner tube 2. The inner tube 2 is inserted into the outer tube 1, and the two flanges are aligned and connected.

In addition, in order to facilitate the installation of the low-nitrogen burner on the boiler furnace body, a flange 5 is formed on the outer periphery of the exhaust gas re-intake pipe cover 31, which can conveniently fix the low-nitrogen burner to the boiler furnace body.

When applying the low-nitrogen burner, please refer to Figures 4 to 6 again, a low-nitrogen energy-saving combustion system, including a furnace body 6 and the low-nitrogen burner installed on the furnace body 6, the furnace body 6 has a furnace, and a burner hole 61 is opened on the front furnace wall of the furnace body 6. The aperture of the burner hole 61 roughly corresponds to or is slightly larger than the outer diameter of the exhaust gas return suction pipe cover 31, and the exhaust gas return suction pipe cover 31 of the low-nitrogen burner can be inserted. A smoke window 62 is provided at the top of the furnace body 6 adjacent to the rear furnace wall to discharge the exhaust gas in the furnace after combustion. The low-nitrogen burner is installed on the front furnace wall of the furnace body 6, and the port of the fire outlet end of the outer tube 1 extends into the furnace.

When the low-nitrogen energy-saving combustion system is in operation, the combustion-supporting gas delivery device 35 starts to deliver the combustion-supporting gas, and the gas device (not shown) delivers the gas, which passes through the heat exchanger 34 and is delivered from the combustion-supporting gas interface to the outer tube 1, and the gas is delivered from the gas interface to the inner tube 2, and then the gas enters the premixing tube 4, and part of the combustion-supporting gas enters the premixing tube 4 and is premixed with the gas, and the ignition device ignites the premixed gas in the premixing tube 4, and the flame is introduced into the combustion space section 101, and the combustion space section 101 is further supplemented with the combustion-supporting gas, and the combustion-supporting gas and the premixed gas are fully burned, and the flame is sprayed into the furnace to heat the furnace. When the flame sprays forward, the inventor has repeatedly observed and studied, combined with repeated experiments, and found that after the flame sprayed forward burns, a large amount of exhaust gas will be generated and swirled back to the periphery of the fire end of the outer tube 1, and a part of the exhaust gas is discharged to the smoke window 62. The exhaust gas exhaust device 32 is started, and the exhaust gas accumulated on the periphery of the fire end of the outer tube 1 enters the exhaust gas return suction pipe cover 31, and then passes through the heat exchanger 34, and then enters the exhaust gas return pipe 33, and is discharged into the combustion space section 101, and is mixed with the fuel gas and supporting combustion gas in the combustion space section 101 for combustion. Due to the low oxygen content in the exhaust gas, the oxygen density in the supporting combustion gas will be diluted, and the combustion temperature in the combustion space section 101 will be reduced, thereby effectively controlling the generation of nitrogen oxides and meeting the environmental protection control requirements.

By adopting the above-mentioned low-nitrogen burner, the exhaust gas can be circulated in large quantities into the combustion space section 101 to be mixed with the supporting combustion gas and the fuel gas, so as to maintain the combustion temperature below the temperature at which a large amount of nitrogen oxides are produced for a long time. Once the combustion temperature rises and more nitrogen oxides are produced, the concentration of nitrogen oxides in the exhaust gas is also high, and more nitrogen oxides are circulated into the combustion space section, which will reduce the combustion temperature.

Compared with the traditional low-nitrogen combustion device, the above-mentioned low-nitrogen burner can fully absorb and utilize the swirling exhaust gas of the combustion by setting the exhaust gas re-inhalation structure 3 at the fire end, so as to achieve the requirement of lowering the combustion temperature and meet the control of the generation of nitrogen oxides. It fully breaks through the traditional belief that exhaust gas must be concentrated at the smoke exhaust port and will not return to the vicinity of the fire end. Since the smoke exhaust port must be far away from the fire end, otherwise the smoke exhaust port will directly discharge the heat of combustion. Through observation and experimental summary, the present applicant understands that part of the burned exhaust gas will swirl to the vicinity of the fire end (i.e. the outer periphery of the outer tube). In this way, the above-mentioned exhaust gas re-inhalation structure 3 is designed to be set at the periphery of the fire end to re-inhale the exhaust gas in the furnace, which can also achieve the effect of suppressing the generation of nitrogen oxides and meet the temperature effect required by the furnace. Compared with the prior art, the use of the traditional exhaust gas circulation pipe for introducing the exhaust gas from the smoke window into the burner can be completely avoided, thereby avoiding the problem of exhaust gas circulation pipe being damaged due to condensation. The low-nitrogen combustion system using the low-nitrogen burner of the present application has a simple structure and does not require an exhaust gas circulation pipe placed outside. The overall structure is simple and compact, occupies little space, is easy to arrange, and reduces the overall manufacturing difficulty and cost of the boiler.

In addition, the present application can preheat the combustion-supporting gas sent from the outside by setting a heat exchanger. The combustion-supporting gas sent into the preheating tube is easier to ignite after preheating. At the same time, the exhaust gas itself reduces its temperature, so that the exhaust gas temperature entering the combustion space is relatively low, which is conducive to reducing the combustion temperature. Compared with the traditional low-nitrogen burner, the exhaust gas directly enters the fire outlet to burn and then is discharged into the furnace, and then most of it is discharged from the smoke window, which fails to fully utilize the heat of the exhaust gas. The low-nitrogen burner of the present application fully utilizes the heat of the exhaust gas, which is more energy-efficient. Moreover, the distance that the exhaust gas of the present application passes can be fully shortened, and there is no need for a long distance path from the furnace tail to the furnace head, which can avoid the loss of exhaust gas heat.

It can be understood that in the present application, the combustion-supporting gas is not limited to air, but may be other combustion-supporting media, and the combustion gas is not limited to natural gas, but may be other fuel media, even fuel oil, etc.

It can be understood that the low-nitrogen energy-saving combustion system includes a control box 8, which is arranged outside the boiler and is used to start and adjust the rotation speed of the combustion-supporting gas delivery device and the fuel gas delivery device, thereby controlling the amount of combustion-supporting gas and fuel gas delivered.

The combustion method of the low nitrogen combustion system of the present invention comprises the following steps:

Start the combustion-supporting gas delivery device 35, the gas delivery device and the exhaust gas exhaust device 32, fill the inner tube 2 with fuel gas through the gas interface 21, fill the outer tube 1 with fuel gas through the combustion-supporting gas interface, premix the fuel gas and the fuel gas, ignite the premixed gas, and the flame generated by the combustion is ejected from the ignition end into the furnace of the furnace body 6, and an exhaust gas reflux is formed in the furnace in the opposite direction to the flame ejection direction and after the flame burns, and the exhaust gas reflux is sucked into the exhaust gas reflux pipe cover 31 through the exhaust gas exhaust device 32, and is transported to the exhaust gas reflux pipe 33, and refluxes to the combustion space section 101 at the ignition end of the outer tube 1.

When the heat exchanger 34 is installed, the combustion-supporting gas conveying device 35 conveys the combustion-supporting gas through the heat exchanger 34 and then enters the outer tube 1, and the exhaust gas enters the exhaust gas return pipe 33 after passing through the exhaust gas return suction pipe cover 31, so that the combustion-supporting gas and the exhaust gas realize heat exchange.

The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims (5)

1. A low-nitrogen burner, comprising an outer tube (1) and an inner tube (2), wherein one end of the outer tube (1) is a fire outlet end and the other end is an air inlet end, the air inlet end is provided with a combustion-supporting gas interface (11), the inner tube (2) is inserted into the outer tube (1), and a gas interface (21) is provided on the inner tube (2) so that the combustion-supporting gas introduced by the outer tube (1) and the gas introduced by the inner tube (2) are mixed in the fire outlet end of the outer tube (1) and then ignited and burned, characterized in that the low-nitrogen burner comprises an exhaust gas re-inhalation structure (3), and the exhaust gas re-inhalation structure (3) comprises an exhaust gas re-inhalation pipe cover (31) and an exhaust gas exhaust device (32), wherein the exhaust gas return suction pipe cover (31) is installed on the outer peripheral wall of the fire outlet end of the outer tube (1), and an exhaust gas return suction hole (311) is opened on the exhaust gas return suction pipe cover (31). The exhaust gas exhaust device (32) is connected to the exhaust gas return suction pipe cover (31). The exhaust gas exhaust device (32) exhausts the exhaust gas that swirls back to the rear of the fire outlet end after combustion, sucks it into the exhaust gas return suction pipe cover (31) and transmits it to the fire outlet end of the outer tube (1). The transmitted exhaust gas is mixed with the combustion-supporting gas introduced by the outer tube (1) and the combustion gas introduced by the inner tube (2), and burns in the fire outlet end. The exhaust gas re-absorption structure (3) comprises an exhaust gas re-flow pipe (33), the exhaust gas re-flow pipe (33) penetrates into the inner tube (2), the exhaust gas exhaust device (32) is connected to the exhaust gas re-absorption pipe cover (31) through one end of the pipe, and the other end is connected to the exhaust gas re-absorption pipe (33); The fire outlet end has a combustion space section (101), the inner tube (2) has a gas outlet end, the outer peripheral wall of the gas outlet end is connected to a premixing tube (4), and the other end of the premixing tube (4) extends to the combustion space section (101); The gas outlet end of the inner tube (2) extends to a position adjacent to the premixing tube (4), and the exhaust gas return pipe (33) extends to a position adjacent to the combustion space section (101); The premixing tube (4) has an inner edge formed at one end, which is fixedly connected to the outer peripheral wall of the gas outlet end of the inner tube (2), and an outer edge formed at the other end, which is fixedly connected to the inner peripheral wall of the outer tube (1). An air vent (41) is provided on the inner edge to allow the combustion-supporting gas that has entered the outer tube (1) to enter the premixing tube (4), and an air hole (42) is provided on the outer edge to allow the combustion-supporting gas that has entered the outer tube (1) to enter the combustion space section (101) for combustion. The air passage hole (42) adopts a spiral channel structure. 2. The low-nitrogen burner according to claim 1 is characterized in that the exhaust gas back-suction structure (3) further includes a heat exchanger (34), the heat exchanger (34) has a first air inlet interface, a first air outlet interface, a second air inlet interface and a second air outlet interface, the first air inlet interface is connected to the air outlet interface of the exhaust gas back-suction pipe cover (31), the first air outlet interface is connected to the exhaust gas exhaust device (32), a combustion-supporting gas delivery device (35) is connected to the second air inlet interface, and the second air outlet interface is connected to the combustion-supporting gas interface (11). 3. A low-nitrogen combustion system, comprising a furnace body (6) and a low-nitrogen burner installed on the furnace body (6), the furnace body (6) having a furnace, a nozzle hole (61) being provided on the front furnace wall of the furnace body, and a smoke window (62) being provided at the top end of the furnace body adjacent to the rear furnace wall for discharging waste gas in the furnace after combustion, characterized in that: the low-nitrogen burner adopts the low-nitrogen burner described in claim 1 or 2, which is installed on the front furnace wall of the furnace body (6), and the port of the ignition end of the outer tube (1) extends into the furnace. 4. A combustion method using the low nitrogen combustion system according to claim 3, comprising the following steps: Starting the combustion-supporting gas conveying device (35), the fuel gas conveying device and the exhaust gas exhausting device (32), charging the fuel gas into the inner tube (2) through the fuel gas interface (21), and charging the combustion-supporting gas into the outer tube (1) through the combustion-supporting gas interface; The fuel gas and the combustion-supporting gas are premixed, the premixed gas is ignited, and is fully burned in the combustion space section (101) at the fire outlet end; The flame generated by the combustion is ejected from the fire outlet end into the furnace of the furnace body (6), forming a waste gas reflux in the furnace in the opposite direction to the flame ejection direction and formed after the flame burns. The waste gas reflux is sucked into the waste gas reflux pipe cover (31) at the fire outlet end of the outer tube (1) through the waste gas exhaust device (32), and is transported to the waste gas reflux pipe (33), and refluxes into the combustion space section (101) at the fire outlet end of the outer tube (1). 5. A combustion method for a low-nitrogen combustion system as claimed in claim 4, comprising the following steps: when a heat exchanger (34) is installed in the low-nitrogen combustion system, the combustion-supporting gas conveying device conveys the combustion-supporting gas through the heat exchanger and then enters the outer tube (1), and the exhaust gas enters the exhaust gas return pipe (33) after passing through the exhaust gas return suction pipe cover (31), and the combustion-supporting gas and the exhaust gas achieve heat exchange.