Low nitrogen premixed flue gas internal circulation gas burner

Abstract

The present invention provides a low-nitrogen premixed flue gas internal circulation gas burner, which is small in size, compact in structure, does not backfire, and has stable combustion. The burner comprises a shell having an air passage, a central gas pipe in the front end of the air passage, each premixing nozzle is arranged at the front end of a premixing nozzle, the rear end of each premixing nozzle is communicated with an air transition pipe and a gas transition pipe, the other end of each air transition pipe is communicated with the premixing air passage, and the other end of each gas transition pipe is communicated with the premixing gas passage; the conical flame tube is coaxial with the central gas tube and is located at the front of the air passage; there is an annular gap between the conical flame tube and the outlet of the air passage, and a plurality of premixing nozzles are evenly distributed at the annular gap; each outer ring nozzle is arranged on an outer ring gas pipe surrounding the outer circumference of the shell; the central gas pipe, the premixing gas passage, and the outer ring gas passage are connected to the gas source through an air supply pipeline provided with a regulating valve; the premixing air passage is communicated with a compressed air source; and the air passage is communicated with the outlet of the blower.

Description

Technical Field

[0001] This patent relates to a gas burner, in particular to a low-nitrogen gas burner. Background Art

[0002] Starting from April 1, 2017, the limit of nitrogen oxides emission concentration for new boilers is 30 mg / m 3 According to the statistical analysis results of the national gas-fired industrial boiler tests, NO X Emission mass concentration is less than or equal to 200 mg / m 3 Only 35% of boilers are operated in this sector. The excessive nitrogen oxide levels are mainly due to the gas burners not adopting low-nitrogen combustion technology or only using the most rudimentary staged combustion control technology.

[0003] In order to achieve low-nitrogen combustion, FGR flue gas circulation technology is often used to supply 15-25% of flue gas to the combustion process to reduce the flame temperature and thereby reduce the NOx value. The flue gas at the tail of the boiler is introduced into the entire air inlet path through the fan and re-entered into the burner for combustion. The surface temperature of the flame drops, and the increased flue gas will also absorb the temperature of the flame. Due to the large proportion of 15-25% flue gas, the thermal efficiency of the boiler is affected and energy consumption increases. Summary of the invention

[0004] The purpose of this patent is to provide a low-nitrogen premixed flue gas internal circulation gas burner with low nitrogen oxide emission concentration. It is small in size, compact in structure, will not flash back, and has stable combustion. It uses a specific structure instead of FGR technology to reduce the nitrogen oxide concentration.

[0005] The low-nitrogen premixed flue gas internal circulation gas burner described in this patent includes a shell with an air channel inside, a central gas pipe at the center of the front end outlet of the air channel, and it also includes multiple premixing nozzles and multiple outer ring nozzles; each premixing nozzle is arranged at the front end of a premixing nozzle, and the rear end of each premixing nozzle is communicated with the air transition pipe and the gas transition pipe at the same time, and the other end of each air transition pipe is communicated with the premixing air channel fixed at the rear end of the shell, and the other end of each gas transition pipe is communicated with the premixing gas channel fixed at the rear end of the shell; the tapered flame tube with a small front end and a large rear end is coaxial with the central gas pipe and is located at the front of the air channel; the diameter of the rear end of the tapered flame tube is smaller than the inner diameter of the air channel outlet, and there is an annular gap between the outer periphery of the rear end of the tapered flame tube and the inner periphery of the air channel outlet, and multiple premixing nozzles are evenly distributed at the annular gap;

[0006] Each outer ring nozzle is arranged on an outer ring gas pipe surrounding the outer periphery of the shell. The outer ring nozzle is located behind the premixing nozzle in the axial direction of the air channel outlet. The outer ring gas pipe is connected to the outer ring gas channel arranged on the outer periphery of the shell through an outer ring transition pipe passing through the refractory ring backwards. The refractory ring is arranged on the outer periphery of the front end of the shell.

[0007] The central gas pipe, premixed gas channel and outer ring gas channel are connected to the gas source through gas supply pipelines respectively, and each gas supply pipeline is provided with a regulating valve; the premixed air channel is connected to the compressed air source; the air channel is connected to the blower outlet; the gas pressure entering the premixed gas channel from the gas source is higher than the gas pressure in the central gas pipe and the outer ring gas channel.

[0008] As a further improvement of the above-mentioned low-nitrogen premixed flue gas internal circulation gas burner, it also includes a plurality of inner ring nozzles; each inner ring nozzle is arranged on an inner ring gas pipe surrounding the outer circumference of the shell, the inner ring nozzle is located between the outer ring nozzle and the premixing nozzle in the axial direction of the air channel outlet, and the outer ring nozzle is located on the outer circumference of the inner ring nozzle in the radial direction of the air channel outlet; the inner ring gas pipe is connected to the inner ring gas channel arranged on the outer circumference of the shell through an inner ring transition pipe that passes backward through the refractory ring; the central gas pipe, the premixing gas channel, the outer ring gas channel, and the inner ring gas channel are respectively connected to the gas source through gas supply pipelines.

[0009] As a further improvement to the above-mentioned low-nitrogen premixed flue gas internal circulation gas burner, the front end surface of the refractory ring is stepped, and the outer ring gas pipe and the inner ring gas pipe are arranged at different steps of the refractory ring.

[0010] As a further improvement to the above-mentioned low-nitrogen premixed flue gas internal circulation gas burner, an inner ring gas outlet serving as an inner ring nozzle is opened on the inner ring gas pipe.

[0011] As a further improvement to the above-mentioned low-nitrogen premixed flue gas internal circulation gas burner, an outer ring gas outlet serving as an outer ring nozzle is opened on the outer ring gas pipe.

[0012] As a further improvement to the above-mentioned low-nitrogen premixed flue gas internal circulation gas burner, the axis of the premixing nozzle is 35°-65° with the axis of the air channel outlet.

[0013] Beneficial effects of this patent:

[0014] High-pressure compressed air and premixed gas are premixed and sprayed out through the premixing nozzle through the annular gap for combustion. The mixed compressed air and premixed gas have a high pressure, and will inhale the surrounding air for combustion when sprayed out. Since the premixed gas and air are premixed, the temperature of the flame is uniform, which shortens the time the gas stays in the high-temperature zone and greatly reduces the combustion temperature. At the same time, the outer ring gas nozzle and the inner ring gas nozzle located on the outer periphery of the shell form many small airflows on the outer periphery of the shell, which increases the flame diffusion jet speed and can also have a suction effect on the low-temperature flue gas near the outer ring gas nozzle and the inner ring gas nozzle; the conical flame tube is small in front and large in the back, and the main flame generated by the combustion of the central gas sprayed from the front end of the central gas tube strengthens the suction capacity of the low-temperature flue gas around the front end of the conical flame tube, and can also evenly reduce the temperature peak of the flame. This patent can be said to be a premixed flue gas internal circulation technology. It adopts this structure to allow part of the flue gas to reflux and participate in combustion, reduce the flame temperature, effectively reduce the Nox value, and make the nitrogen oxide concentration less than 30 mg / m 3 .

[0015] The gas in the central gas pipe is sprayed out by the central nozzle. At the same time, the axis of the premixing nozzle is 35°-65° with the axis of the air channel outlet. The gas burner forms diffusion combustion, with small size, compact structure, no backfire, and stable flame, thus ensuring the stability of the entire combustion.

[0016] Of course, each gas supply pipeline is provided with a regulating valve, such as a pressure regulating valve, a flow regulating valve, or even a regulating valve whose opening can be controlled by a servo motor, so as to control the gas pressure and flow rate on the gas supply pipeline in the future. This belongs to the prior art and will not be described in detail. An adjustable damper can be provided at the blower outlet, and the blower motor can adjust the air flow in the air channel by means of the prior art such as an air volume servo motor.

[0017] Of course, the gas burner can also include a controller, and the shell can also be provided with an ignition device, a flame monitoring device, a temperature control device, etc., which belong to conventional technical means; the output end of the controller is connected to the input end of the ignition device, and is used to control the opening and closing of the ignition device; the output end of the above-mentioned flame monitoring device is connected to the input end of the controller, and is used to send the detected flame combustion signal to the controller; the output end of the above-mentioned temperature control device is connected to the input end of the controller, and is used to transmit the temperature signal in the shell to the controller. Each servo motor, each servo motor feedback, etc. are also connected to the controller respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a stereoscopic diagram of a low-nitrogen premixed flue gas internal circulation gas burner;

[0019] Figure 2 It is another stereoscopic view of a low nitrogen premixed flue gas internal circulation gas burner;

[0020] Figure 3 This is a top view of a low-nitrogen premixed flue gas internal circulation gas burner;

[0021] Figure 4 This is the main view of the low-nitrogen premixed flue gas internal circulation gas burner;

[0022] Figure 5 This is a side view of a low-nitrogen premixed flue gas internal circulation gas burner;

[0023] Figure 6 This is an enlarged view of the outer ring gas pipe, outer ring nozzle, etc.

[0024] In the figure, the shell 1, the conical flame tube 11, the annular gap 12, the refractory ring 2, the ignition device 7,

[0025] Central gas pipe 3, central gas inlet 36,

[0026] Premixing nozzle 41, premixing nozzle 4, air transition pipe 42, premixing air channel 43, gas transition pipe 44, premixing gas channel 45, premixing gas inlet 46, premixing air inlet 47,

[0027] Outer ring gas pipe 5, outer ring nozzle 51, outer ring transition pipe 52, outer ring hose 53, outer ring gas channel 55, outer ring gas inlet 56,

[0028] Inner ring gas pipe 6, inner ring nozzle 61, inner ring transition pipe 62, inner ring hose 63, inner ring gas channel 65, inner ring gas inlet 66,

[0029] Air channel 100 , air channel inlet 101 , air channel outlet 102 . DETAILED DESCRIPTION

[0030] See also Figure 1 , 2 4. A low nitrogen premixed flue gas internal circulation gas burner comprises a shell 1 having an air passage 100 therein, a refractory ring 2 arranged at the outer periphery of the front end of the shell; the front end surface of the refractory ring is stepped. The rear of the air passage 100 is an air passage inlet 101 opened at the side of the shell, and the air passage inlet 101 is connected to the blower outlet. At the front end of the air passage, an air passage outlet 102 is located at the front end of the shell.

[0031] The rear end of the central gas pipe 3 passes through the rear part of the shell, and the front end is located at the center of the air channel outlet 102.

[0032] See also Figure 2 , 35. Each premixing nozzle 41 is arranged at the front end of a premixing nozzle 4. The rear end of each premixing nozzle 4 is communicated with the air transition pipe 42 and the gas transition pipe 44 at the same time. The other end of each air transition pipe 42 is communicated with the premixing air channel 43 fixed at the rear end of the shell, and the other end of each gas transition pipe 44 is communicated with the premixing gas channel 45 fixed at the rear end of the shell.

[0033] The conical flame tube 11 with a small front end and a large rear end is coaxial with the central gas tube and is located in front of the outlet of the air passage.

[0034] The diameter of the rear end of the conical flame tube is smaller than the inner diameter of the air channel outlet. There is an annular gap 12 between the outer periphery of the rear end of the conical flame tube and the inner periphery of the air channel outlet. A plurality of premixing nozzles 41 are evenly distributed in the annular gap.

[0035] The outer ring gas pipe 5 and the inner ring gas pipe 6 are arranged at different steps of the refractory ring. The outer ring gas pipe 5 is provided with a plurality of outer ring gas outlets serving as outer ring nozzles 51 .

[0036] The inner ring gas pipe 6 is provided with a plurality of inner ring gas outlets serving as inner ring nozzles 61 .

[0037] Each premixing nozzle 41, each outer ring nozzle 51, and each inner ring nozzle 61 are evenly distributed in the circumferential direction with the air channel outlet axis as the center line. The outlet axis of the premixing nozzle 41 is about 45 degrees to the axis of the air channel outlet.

[0038] See also Figure 6 The inner ring nozzle 61 is located behind the premixing nozzle 41 in the axial direction of the air passage outlet, and the outer ring nozzle 51 is located behind the inner ring nozzle 61. The outer ring nozzle 51 is located on the outer periphery of the inner ring nozzle 61 in the radial direction of the air passage outlet.

[0039] See also Figure 2 , 3 The outer ring gas pipe 5 is connected to the outer ring gas channel 55 arranged on the outer periphery of the middle part of the shell through the outer ring transition pipe 52 and the outer ring hose 53 that pass through the refractory ring backwards.

[0040] The inner ring gas pipe 6 communicates with the inner ring gas channel 65 arranged on the outer periphery of the middle part of the shell through the inner ring transition pipe 62 and the inner ring hose 63 which pass through the refractory ring backwards.

[0041] See also Figure 1 , 2The central gas inlet 36, premixed gas inlet 46, outer ring gas inlet 56, and inner ring gas inlet 66 on the central gas pipe 3, premixed gas channel 45, outer ring gas channel 55, and inner ring gas channel 65 are respectively connected to the gas source through gas supply pipelines, and each gas supply pipeline is provided with a regulating valve. The gas pressures in the central gas pipe, outer ring gas channel, and inner ring gas channel are basically the same. The gas pressure entering the premixed gas channel from the gas source is higher than the gas pressure in the central gas pipe.

[0042] The premix air inlet 47 on the premix air passage 43 is in communication with a compressed air source.

[0043] This patent provides a low-nitrogen gas burner, which uses the induced reflux technology and the induced reflux technology to reduce the nitrogen oxide content in the exhaust gas to 30mg / m 3 The following purposes, and the damper and gas flow ratio, the fan and each regulating valve are automatically controlled separately, simple operation, convenient maintenance, long service life of parts, and energy saving.

Claims

1. A low-nitrogen premixed flue gas internal circulation gas burner, comprising a shell having an air passage inside, and a central gas pipe at the front end outlet center of the air passage, characterized in that: It also includes a plurality of premixing nozzles and a plurality of outer ring nozzles; each premixing nozzle is arranged at the front end of a premixing nozzle, and the rear end of each premixing nozzle is communicated with the air transition pipe and the gas transition pipe at the same time, and the other end of each air transition pipe is communicated with the premixing air channel fixed at the rear end of the shell, and the other end of each gas transition pipe is communicated with the premixing gas channel fixed at the rear end of the shell; the conical flame tube with a small front end and a large rear end is coaxial with the central gas tube and is located at the front of the air channel; the diameter of the rear end of the conical flame tube is smaller than the inner diameter of the air channel outlet, and there is an annular gap between the outer periphery of the rear end of the conical flame tube and the inner periphery of the air channel outlet, and the plurality of premixing nozzles are evenly distributed at the annular gap; Each outer ring nozzle is arranged on an outer ring gas pipe surrounding the outer periphery of the shell. The outer ring nozzle is located behind the premixing nozzle in the axial direction of the air channel outlet. The outer ring gas pipe is connected to the outer ring gas channel arranged on the outer periphery of the shell through an outer ring transition pipe passing through the refractory ring backwards. The refractory ring is arranged on the outer periphery of the front end of the shell. The central gas pipe, premixed gas channel and outer ring gas channel are connected to the gas source through gas supply pipelines respectively, and each gas supply pipeline is provided with a regulating valve; the premixed air channel is connected to the compressed air source; the air channel is connected to the blower outlet; the gas pressure entering the premixed gas channel from the gas source is higher than the gas pressure in the central gas pipe and the outer ring gas channel; the outer ring gas pipe is provided with an outer ring gas outlet serving as an outer ring nozzle; the axis of the premixed nozzle is at 35°-65° with the axis of the air channel outlet.

2. The low-nitrogen premixed flue gas internal circulation gas burner according to claim 1, characterized in that: It also includes a plurality of inner ring nozzles; each inner ring nozzle is arranged on an inner ring gas pipe surrounding the outer circumference of the shell, the inner ring nozzle is located between the outer ring nozzle and the premixing nozzle in the axial direction of the air channel outlet, and the outer ring nozzle is located on the outer circumference of the inner ring nozzle in the radial direction of the air channel outlet; the inner ring gas pipe is connected to the inner ring gas channel arranged on the outer circumference of the shell through an inner ring transition pipe passing backward through the refractory ring; the central gas pipe, the premixing gas channel, the outer ring gas channel, and the inner ring gas channel are respectively connected to the gas source through gas supply pipelines.

3. The low-nitrogen premixed flue gas internal circulation gas burner according to claim 2, characterized in that: The front end surface of the refractory ring is in a step shape, and the outer ring gas pipe and the inner ring gas pipe are arranged at different steps of the refractory ring.

4. The low-nitrogen premixed flue gas internal circulation gas burner according to claim 2, characterized in that: The inner ring gas pipe is provided with an inner ring gas outlet serving as an inner ring nozzle.

Images