Low-nitrogen premixed flue gas internal circulation gas burnerTechnical Field
This patent relates to gas burners, in particular low nitrogen gas burners.
Background
The limit value of the emission concentration of the atmospheric pollutants of the newly built boiler is 30 mg/m3 from the 1 st 4 th 2017, and according to the detection statistical analysis result of the national gas industrial boiler, the boiler with the emission mass concentration of NOX less than or equal to 200mg/m3 only accounts for 35%, and the exceeding of the nitrogen oxides is mainly that the gas burner does not adopt a low-nitrogen combustion technology or only adopts a staged combustion control technology of an initial step.
In order to achieve low nitrogen combustion, FGR flue gas recirculation techniques are often used, whereby 15-25% of the flue gas is fed to the combustion process to reduce the flame temperature and thereby the Nox value. The tail smoke of the boiler is introduced into the whole air inlet path through the fan and is thrown into the burner again for combustion, the surface temperature of flame is reduced, the increased smoke can absorb the temperature of flame, and the heat efficiency of the boiler is affected and the energy consumption is increased due to the 15-25% large-proportion smoke.
Disclosure of Invention
The purpose of this patent is to provide a low nitrogen premix flue gas inner loop gas burner that nitrogen oxide emission concentration is lower, and it is small, compact structure, can not tempering, and the burning is stable, and it adopts specific structure rather than adopts FGR technique to reduce nitrogen oxide concentration.
The low-nitrogen premixed gas internal circulation gas burner comprises a shell, a plurality of premixing nozzles and a plurality of outer ring nozzles, wherein an air channel is arranged in the shell, a central gas pipe is arranged at the center of an outlet at the front end of the air channel, the premixing nozzles are arranged at the front end of one premixing spray pipe, the rear end of each premixing spray pipe is simultaneously communicated with an air transition pipe and a gas transition pipe, the other end of each air transition pipe is communicated with a premixing air channel fixed at the rear end of the shell, the other end of each gas transition pipe is communicated with a premixing gas channel fixed at the rear end of the shell, a conical flame pipe with a small front end and a large rear end is coaxial with the central gas pipe and is positioned at the front part of the air channel, the diameter of the rear end of the conical flame pipe is smaller than the inner diameter of the outlet of the air channel, an annular gap is reserved between the periphery of the rear end of the conical flame pipe and the inner periphery of the outlet of the air channel, and the premixing nozzles are uniformly distributed at the annular gap;
The outer ring gas pipe is communicated with the outer ring gas channel arranged at the periphery of the shell through an outer ring transition pipe passing through the refractory ring backwards;
The central gas pipe, the premixed gas channel and the outer ring gas channel are respectively communicated with a gas source through gas supply pipelines, regulating valves are arranged on the gas supply pipelines respectively, the premixed air channel is communicated with a compressed air source, the air channel is communicated with an outlet of a blower, and the pressure of gas entering the premixed gas channel from the gas source is higher than the pressure of gas in the central gas pipe and the outer ring gas channel.
The low-nitrogen premixed flue gas internal circulation gas burner further comprises a plurality of inner ring nozzles, wherein each inner ring nozzle is arranged on an inner ring gas pipe encircling the outer periphery of the shell, the inner ring nozzle is positioned between the outer ring nozzle and the premixed nozzle in the axial direction of an air channel outlet, the outer ring nozzle is positioned at the outer periphery of the inner ring nozzle in the radial direction of the air channel outlet, the inner ring gas pipe is communicated with an inner ring gas channel arranged at the outer periphery of the shell through an inner ring transition pipe penetrating through the fireproof ring backwards, and the central gas pipe, the premixed gas channel, the outer ring gas channel and the inner ring gas channel are respectively communicated with a gas source through gas supply pipelines.
As a further improvement on the low-nitrogen premixed flue gas internal circulation gas burner, the front end face of the fireproof 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 fireproof ring.
As a further improvement on the low-nitrogen premixed flue gas internal circulation gas burner, an inner ring gas outlet serving as an inner ring nozzle is formed in the inner ring gas pipe.
As a further improvement on the low-nitrogen premixed flue gas internal circulation gas burner, an outer ring gas outlet serving as an outer ring nozzle is formed in the outer ring gas pipe.
As a further improvement to the low nitrogen premix flue gas internal recycle gas burner described above, the premix nozzle axis is 35 ° -65 ° from the axis of the air passage outlet.
The beneficial effect of this patent:
The high-pressure compressed air and the premixed gas are premixed and sprayed out through the annular gap through the premixing nozzle for combustion. The pressure of the mixed compressed air and the premixed gas is larger, and the air around the mixed compressed air and the premixed gas can be sucked for combustion when the mixed compressed air and the premixed gas are sprayed out, and the premixed gas and the air are premixed, so that the temperature of flame is uniform, the stay time of the gas in a high temperature area is shortened, and the combustion temperature is greatly reduced. The outer ring air tap and the inner ring air tap on the outer periphery of the shell form a plurality of small airflows on the outer periphery of the shell, the flame diffusion jet flow speed is improved, the entrainment effect can be achieved on low-temperature smoke near the outer ring air tap and the inner ring air tap, the front part and the rear part of the conical flame tube are large, the entrainment capability of main flame generated by central gas combustion sprayed from the front end of the central gas tube on the low-temperature smoke around the front end of the conical flame tube is enhanced, and the temperature peak value of the flame can be uniformly reduced. This patent can be said to a premixing flue gas internal recycle technique, it adopts this structure for some flue gas backward flow participates in the burning, reduces flame temperature, effectively reduces the Nox value, makes nitrogen oxide concentration be less than 30 mg/m3.
The gas in the central gas pipe is sprayed out from the central nozzle, and meanwhile, the axis of the premixing nozzle and the axis of the air channel outlet form 35-65 degrees.
Of course, each air supply pipeline is provided with a regulating valve, such as a pressure regulating valve and a flow regulating valve, even the regulating valve capable of controlling the opening of each regulating valve through a servo motor, and then controlling the gas pressure, the flow and the like on the air supply pipeline, which belongs to the prior art and is not repeated. An adjustable air door can be arranged at the outlet of the air blower, and the air blower motor can adjust the air flow in the air channel by the prior art means such as an air quantity servo motor.
Of course, the gas burner can also comprise a controller, an ignition device, a flame monitoring device, a temperature control device and the like which belong to the conventional technical means can be arranged on the shell, the output end of the controller is connected with the input end of the ignition device and used for controlling the ignition device to be turned on and off, the output end of the flame monitoring device is connected with the input end of the controller and used for sending the detected flame burning signal to the controller, and the output end of the temperature control device is connected with the input end of the controller and used for transmitting the temperature signal in the shell to the controller. Each servo motor, feedback of each servo motor and the like are also respectively connected with the controller.
Drawings
FIG. 1 is a perspective view of a low nitrogen premixed flue gas internal recycle gas burner;
FIG. 2 is another perspective view of a low nitrogen premixed flue gas internal recycle gas burner;
FIG. 3 is a top view of a low nitrogen premixed flue gas internal recycle gas burner;
FIG. 4 is a front view of a low nitrogen premix flue gas internal recycle gas burner;
FIG. 5 is a side view of a low nitrogen premix flue gas internal recycle gas burner;
fig. 6 is an enlarged view of the outer ring gas pipe, outer ring nozzle, etc.
In the figure, a housing 1, a conical flame tube 11, an annular gap 12, a refractory ring 2, an ignition device 7,
A central gas pipe 3, a central gas inlet 36,
Premix nozzle 41, premix nozzle 4, air transition duct 42, premix air passage 43, gas transition duct 44, premix gas passage 45, premix gas inlet 46, premix air inlet 47,
An outer ring gas pipe 5, an outer ring nozzle 51, an outer ring transition pipe 52, an outer ring hose 53, an outer ring gas channel 55, an outer ring gas inlet 56,
An inner ring gas pipe 6, an inner ring nozzle 61, an inner ring transition pipe 62, an inner ring hose 63, an inner ring gas channel 65, an inner ring gas inlet 66,
An air channel 100, an air channel inlet 101, and an air channel outlet 102.
Detailed Description
Referring to fig. 1,2 and 4, the low-nitrogen premixed gas burner comprises a shell 1 with an air channel 100 inside, a fire-resistant ring 2 is arranged on the periphery of the front end of the shell, and the front end surface of the fire-resistant ring is in a stepped shape. The rear of the air passage 100 is an air passage inlet 101 opened at the side of the housing, and the air passage inlet 101 communicates with the blower outlet. At the front end of the air passage an air passage outlet 102 is located at the front end of the housing.
The rear end of the central gas pipe 3 passes through the rear of the housing and the front end is located in the central portion of the air passage outlet 102.
Referring to fig. 2,3 and 5, each premix nozzle 41 is disposed at the front end of one premix nozzle 4, and the rear end of each premix nozzle 4 is simultaneously communicated with an air transition pipe 42 and a gas transition pipe 44, the other end of each air transition pipe 42 is communicated with a premix air passage 43 fixed at the rear end of the housing, and the other end of each gas transition pipe 44 is communicated with a premix gas passage 45 fixed at the rear end of the housing.
A conical flame tube 11 with a small front end and a large rear end is coaxial with the central gas tube and is positioned in front of the air passage outlet.
The diameter of the rear end of the conical flame tube is smaller than the inner diameter of the air channel outlet, an annular gap 12 is arranged between the outer periphery of the rear end of the conical flame tube and the inner periphery of the air channel outlet, and a plurality of premixing nozzles 41 are uniformly distributed at the annular gap.
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.
The inner ring gas pipe 6 is provided with a plurality of inner ring gas outlets serving as inner ring nozzles 61.
The premix nozzles 41, the outer ring nozzles 51, and the inner ring nozzles 61 are uniformly distributed in the circumferential direction around the air passage outlet axis. The outlet axis of the premixing nozzle 41 is about 45 degrees to the axis of the air passage outlet.
Referring to fig. 6, the inner ring nozzle 61 is located behind the premix 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 at the outer periphery of the inner ring nozzle 61 in the radial direction of the air passage outlet.
Referring to fig. 2 and 3, the outer ring gas pipe 5 communicates with an outer ring gas passage 55 provided at the outer periphery of the middle portion of the casing through an outer ring transition pipe 52, an outer ring hose 53, etc. passing through the refractory ring rearward.
The inner ring gas pipe 6 communicates with an inner ring gas passage 65 provided at the outer periphery of the middle portion of the housing through an inner ring transition pipe 62, an inner ring hose 63, etc. passing back through the refractory ring.
Referring to fig. 1 and 2, the central gas pipe 3, the premixed gas passage 45, the outer ring gas passage 55, and the central gas inlet 36, the premixed gas inlet 46, the outer ring gas inlet 56, and the inner ring gas inlet 66 on the inner ring gas passage 65 are respectively communicated with a gas source through gas supply pipelines, and each gas supply pipeline is provided with a regulating valve. The gas pressure in the central gas pipe, the outer ring gas channel and the inner ring gas channel is basically the same. The pressure of the gas entering the premix gas passage from the gas source is higher than the pressure of the gas in the central gas pipe.
Premix air inlet 47 in premix air passage 43 communicates with a source of compressed air.
The patent provides a low nitrogen gas burner, adopts drainage backward flow technique, draws the purpose that the nitrogen oxide in the exhaust gas made to reach below 30mg/m3 such as penetrating backward flow technique, and air door and gas flow ratio, fan and each governing valve are independent automatic control respectively, easy operation, easy maintenance, part life height, energy saving.