CN110822428A - Radiant tube low-nitrogen burner with multiple drainage - Google Patents
Radiant tube low-nitrogen burner with multiple drainage Download PDFInfo
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- CN110822428A CN110822428A CN201911262742.0A CN201911262742A CN110822428A CN 110822428 A CN110822428 A CN 110822428A CN 201911262742 A CN201911262742 A CN 201911262742A CN 110822428 A CN110822428 A CN 110822428A
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- injection
- air
- injection passage
- air inlet
- smoke outlet
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/20—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone
- F23D14/22—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone with separate air and gas feed ducts, e.g. with ducts running parallel or crossing each other
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C9/00—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/66—Preheating the combustion air or gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L15/00—Heating of air supplied for combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C2202/00—Fluegas recirculation
- F23C2202/30—Premixing fluegas with combustion air
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion Of Fluid Fuel (AREA)
Abstract
The invention relates to the field of flue gas recirculation combustors, in particular to a radiant tube low-nitrogen combustor with multiple drainage functions. Comprises a U-shaped pipe body, a burner, a fuel gas inlet end and a flue gas outlet end; the upper end of the smoke outlet end is provided with a smoke outlet, the lower end of the smoke outlet end is provided with a first injection passage and a second injection passage, the tail end of the second injection passage is communicated with the first injection passage, and the tail end of the first injection passage is communicated with a gas inlet end; the air inlet end is installed in the smoke outlet end, the lower end of the air inlet end is provided with two air nozzles, and the two air nozzles are respectively located in the first injection passage and the second injection passage. The invention adopts a multiple injection structure and combines a flue gas recirculation technology, increases the return flow of the flue gas, so that the preheated air and the flue gas are more efficiently mixed, and the purposes of increasing the temperature of the preheated air, saving energy, reducing the oxygen content in the air and reducing the emission of nitrogen oxides are achieved.
Description
Technical Field
The invention relates to the field of flue gas recirculation combustors, in particular to a radiant tube low-nitrogen combustor with multiple drainage functions.
Background
With the increasing degree of environmental pollution, nitrogen oxides are one of the main pollution sources causing atmospheric pollution, and bring damages to human bodies, animals and plants. Nitrogen oxides can also cause environmental pollution such as acid rain, acid mist, and photochemical smog. The research and the treatment of the emission of nitrogen oxides are a main direction of international pollution treatment at present, and China puts forward a new standard for the emission requirements of various industries.
In the field of combustion furnaces, the application furnace temperature of a radiant tube in a continuous heat treatment furnace is usually about 900 ℃, and the preheating temperature of air passing through a heat exchange device is usually about 500 ℃, so that the combustion temperature in the radiant tube is greatly increased. The local combustion temperature can exceed 1100 ℃, a local combustion high-temperature area is generated, and the generation of nitrogen oxides is intensified. Therefore, under the more strict requirement of the emission index of the nitrogen oxide, the emission of the nitrogen oxide adopting the radiant tube heating mode reaches the standard very difficultly.
At present, the novel combustion mode is the most direct method for realizing energy conservation and emission reduction. In the field of industrial burners, the application of flue gas recirculation technology in burners is beneficial to reducing the emission of nitrogen oxides and improving the combustion efficiency. The patent No. CN202281227U discloses a radiant tube heat exchanger with flue gas backflow, which has the advantages of reasonable structure, reduction of burner and combustion intensity, energy conservation and emission reduction, and flue gas backflow. The utility model discloses a be equipped with special induction apparatus between air hose, nozzle and exhaust port and flow back to the flue gas, reached energy saving and emission reduction's purpose. However, the injection amount of the smoke is limited by the fixed air channel, so that the injection amount is limited. Moreover, the pressure of the smoke exhaust channel is much smaller than that of the air channel under the suction action of a smoke exhaust draught fan. If the strength of the injection structure is not enough, the low pressure formed by the high-speed air can be higher than the pressure of the flue, and the flue gas cannot be injected.
Patent number CN209672324U a low NOx radiant tube combustion system of adjustable flue gas backward flow volume through setting up resistance adjusting device, can adjust flue gas backward flow volume according to equipment actual demand, effectively improves the interior burning condition of radiant tube, reduces NOx formation in the radiant tube by a wide margin. This technique effectively utilizes the flue gas waste heat through setting up the heat exchanger, improves radiant tube surface temperature homogeneity simultaneously, improves the interior temperature field homogeneity of stove, protection equipment and personnel, the life of extension equipment.
However, according to the scheme, when the ejector is fixed by the ejection inlet and the air nozzle, the ejection effect of the ejector is fixed when the working condition is not changed. Under the same state, the injection coefficient and the flow of the injected fluid can be increased along with the increase of the injected pressure. However, the added valve plate can only increase the flow resistance and reduce the pressure of the injected fluid, and the pressure of the injected fluid cannot be increased. Finally, the injection coefficient can be reduced and the injection strength can be reduced only on the basis of the original injection strength. And the injection coefficient is lower for original single injection structure, can't guarantee very high injection intensity, and the practicality is relatively poor, can't reach the requirement that reduces oxynitrides.
Disclosure of Invention
In order to overcome the technical problems in the prior art, the invention aims to provide a radiant tube low-nitrogen burner with multiple drainage functions, which can exchange heat between air and flue gas, recover waste heat of the flue gas, preheat the air, improve the combustion efficiency, reduce the temperature of flue gas emission and reduce the fuel consumption.
The invention combines the advantages of the flue gas recirculation technology and the preheating type burner, increases the flue gas reflux quantity to enable the preheated air and the flue gas to be mixed more efficiently, improves the temperature of the preheated air to achieve the purpose of saving energy, and simultaneously reduces the oxygen content in the air, the combustion high temperature and the emission of nitrogen oxides. According to the invention, the backflow amount of the flue gas is increased, and meanwhile, through multiple injection mixing, air and the flue gas can be well and fully mixed, so that the phenomenon that the oxygen concentration is unevenly distributed due to uneven mixing is avoided, and further, a local high-temperature area is caused by overhigh local oxygen concentration in combustion.
The technical scheme adopted by the invention for solving the technical problems is as follows: the radiant tube low-nitrogen burner with multiple drainage comprises a U-shaped tube body, a burner nozzle arranged in the U-shaped tube body, a fuel gas inlet end arranged at one end of the U-shaped tube body, and a flue gas outlet end arranged at the other end of the U-shaped tube body, wherein an air inlet end is arranged on the side surface of the flue gas outlet end, and the air inlet end is communicated with the fuel gas inlet end;
the smoke outlet end is designed to be of a cylindrical structure, a smoke exhaust opening is formed in the upper end of the smoke outlet end, a first injection passage and a second injection passage are formed in the lower end of the smoke outlet end, the tail end of the second injection passage is communicated with the first injection passage, and the tail end of the first injection passage is communicated with a gas inlet end;
the air inlet end is cylindrical, the air inlet end is installed in the smoke outlet end, the lower end of the air inlet end is provided with two air nozzles, and the two air nozzles are respectively positioned in the first injection passage and the second injection passage; and the air inlet end is communicated with the first injection passage and the second injection passage through an air nozzle.
Further preferred embodiments of the present invention are: the lower extreme of two air injection nozzles all is equipped with the necking down.
Further preferred embodiments of the present invention are: the second injection channel is a bent pipe and is connected with the first injection channel through an S-shaped bend, the lower end of the second injection channel is a reducing pipe, the reducing pipe penetrates through the first injection channel and is arranged in the first injection channel, and the outflow direction of gas in the reducing pipe is consistent with the flow direction of air in the first injection channel.
Further preferred embodiments of the present invention are: the smoke outlet end and the air inlet end are coaxial, and the smoke outlet end is sleeved on the air inlet end.
Further preferred embodiments of the present invention are: the right end of the smoke outlet end is communicated with the U-shaped pipe body.
Further preferred embodiments of the present invention are: the second injection channels can be arranged in a plurality of numbers, the second injection channels are dispersedly distributed by taking the first injection channels as centers, and the lower ends of the second injection channels are inserted into the first injection channels in an up-and-down staggered mode.
The invention adopts a multiple injection structure and combines a flue gas recirculation technology, increases the return flow of the flue gas, so that the preheated air and the flue gas are more efficiently mixed, and the purposes of increasing the temperature of the preheated air, saving energy, reducing the oxygen content in the air, reducing the high combustion temperature and reducing the emission of nitrogen oxides are achieved. According to the invention, the backflow amount of the flue gas is increased, and meanwhile, through multiple injection mixing, air and the flue gas can be well and fully mixed, so that the phenomenon that the oxygen concentration is unevenly distributed due to uneven mixing is avoided, and further, the generation of oxynitride can be improved due to local high temperature in a local high temperature area caused by overhigh local oxygen concentration in combustion.
Drawings
The invention is further illustrated by the following figures and examples.
FIG. 1 is a schematic view of the overall structure of a radiant tube low-nitrogen burner of the present invention;
FIG. 2 is a schematic view of a partial enlarged structure of an air inlet end, a flue gas outlet end and a fuel gas inlet end of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to specific embodiments below.
As shown in fig. 1-2, the radiant tube low-nitrogen burner with multiple drainage for this embodiment includes a U-shaped tube body 1, a burner 2 installed in the U-shaped tube body 1, a gas inlet end 3 installed at one end of the U-shaped tube body 1, and a gas outlet end 4 installed at the other end of the U-shaped tube body 1, wherein an air inlet end 5 is installed at a side surface of the gas outlet end 4, and the air inlet end 5 is communicated with the gas inlet end 3. The gas inlet end 3 is used for conveying gas, the air inlet end 5 is used for conveying air, the combustion nozzle 2 is used for mixing and combusting the gas and the air, and smoke generated by combustion of the combustion nozzle 2 flows along the U-shaped pipe body and is discharged from the smoke outlet end 4.
This embodiment carries out special design with gas entrance point 3, flue gas outlet end 4, air inlet end 5 for the air drives the flue gas and gets into gas entrance point, burns then. The high-temperature flue gas can preheat air to improve the temperature of mixed air, save energy, reduce the oxygen content in the air, reduce the combustion high temperature and reduce the emission of nitrogen oxides.
The design of this embodiment exit gas end 4 is cylindric structure, and exit gas end 4's right side intercommunication U type body 1. The upper end of the smoke outlet end 4 is provided with a smoke discharge port 41, the lower end of the smoke outlet end 4 is provided with a first injection passage 42 and a second injection passage 43, and smoke flows from the inside of the U-shaped pipe body 1 to the smoke discharge port 41, the first injection passage 42 and the second injection passage 43.
The first injection passage 42 is communicated with the gas inlet end 3 in a straight line, the second injection passage 43 is a bent pipe, and the second injection passage 43 is communicated with the first injection passage 42 through an S-shaped bend A. Specifically, the tail end of the second injection passage 43 is a necking pipe B, and the necking pipe B penetrates through the first injection passage 42 and is stored in the first injection passage 42. The insertion length of the necking tube B is ensured as follows: the outflow direction of the smoke in the necking pipe B is consistent with the flowing direction of the air in the first injection passage 42.
The air inlet end 5 in the embodiment is cylindrical, the air inlet end 5 is installed in the smoke outlet end 4, specifically, the smoke outlet end 4 and the air inlet end 5 are coaxial, and the smoke outlet end 4 is sleeved on the air inlet end 5. And the left side of the air inlet end 5 is communicated with an air source.
The lower end of the air inlet end 5 is provided with an air nozzle 51, and the two air nozzles 51 are respectively positioned in the first injection passage 42 and the second injection passage 43; the air inlet end 5 is communicated with the first injection passage 42 and the second injection passage 43 through an air nozzle 51. The lower ends of the two air nozzles are designed into necking structures.
This embodiment reforms transform based on U type radiant tube combustor, adds multiple drainage gas recirculation device. As shown in fig. 1, the integral structure of the radiant tube low-nitrogen burner is shown. Fig. 2 shows a connection structure diagram of the flue gas outlet end 4, the air inlet end 5 and the gas inlet end 3.
Two air nozzle all adopt the necking down to handle, increase air flow rate plays the effect of drawing the gas fume. The mechanism is as follows: the two air nozzles adopt necking treatment, the air flow cross section velocity is forced to increase, the hydrostatic pressure is converted into dynamic pressure, and a low-pressure area is formed at the rear part of the nozzle. Leading to the entrainment of the injected fluid (flue gas) into the low pressure area and improving the dynamic pressure of the flue gas. Finally, the dynamic pressure of the injection fluid (air) is transferred to the injected fluid (flue gas).
In this embodiment, divide into two dry individual less air nozzle with the bigger traditional nozzle in cross-section, draw and penetrate the effect and effectively strengthen. The jet flow of the two air nozzles in the embodiment can enable the injection fluid (air) and the injected fluid (flue gas) to be better mixed in the first short injection passage 42 and the second short injection passage 43 respectively, reverse backflow is avoided, the friction loss of the throat part of the air nozzle 51 is reduced, the outlet flow velocity distribution of the first injection passage 42 and the second injection passage 43 is improved, and therefore energy diffusion loss is reduced.
The junction of the first injection channel 42 and the second injection channel 43 is also connected by a drainage structure, and the principle that the residual pressure of the strong branch pushes the weak branch to advance together is utilized. As shown in fig. 2, the first jet channel 42 is called the first branch mixed with the air nozzle inside. The branch mixed by the first jet channel 43 and the air nozzle inside the first jet channel is changed into a second branch, and the first branch and the second branch are mixed to be called a third main flow.
When the residual pressure of the branch flow of the air flow channel I mixed with the flue gas is greater than that of the branch flow of the air flow channel II mixed with the flue gas, when the mixed gas of the branch flow I flows through the joint, the flow section is reduced, and a negative pressure area is formed around the outlet of the mixed gas. Generating a winding suction force to the II branch flow, and finally introducing the mixed gas of the II branch flow into the III main flow to be mutually dissolved and synthesized to reach the balance. And when the residual pressure of the I branch is less than that of the II branch, the II branch medium passes through the reducing section of the necking pipe B. Because the sectional area of the necking pipe B is reduced, the flow velocity of the medium is increased, the dynamic pressure is increased, the static pressure is reduced, an induced flow beam is formed, and finally, the I branch medium is introduced and mixed into the III main flow, thereby achieving balance.
This embodiment makes different pressure flow channels converge the back, gives weak tributary with strong tributary dynamic pressure transmission, reduces energy loss, reaches the automatic balance effect. This embodiment has both utilized the different residual pressure of two runners to reach the balanced purpose of two branches of strong, weak flow, can make again through the drainage mixing two strands of fluid mix, reach better mixed effect. The better mixture of this embodiment flue gas and air avoids local high temperature region that local oxygen concentration arouses during the burning to lead to the formation of heating power type nitrogen oxide.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.
Claims (6)
1. Radiant tube low NOx burner with multiple drainage, including U type body, install burner tip in U type body, install at the gas entrance point of U type body one end, install the flue gas exit end at the U type body other end, the side-mounting air inlet point of flue gas exit end, the air inlet point with the gas entrance point communicates with each other, its characterized in that:
the smoke outlet end is designed to be of a cylindrical structure, a smoke exhaust opening is formed in the upper end of the smoke outlet end, a first injection passage and a second injection passage are formed in the lower end of the smoke outlet end, the tail end of the second injection passage is communicated with the first injection passage, and the tail end of the first injection passage is communicated with a gas inlet end;
the air inlet end is cylindrical, the air inlet end is installed in the smoke outlet end, the lower end of the air inlet end is provided with two air nozzles, and the two air nozzles are respectively positioned in the first injection passage and the second injection passage; and the air inlet end is communicated with the first injection passage and the second injection passage through an air nozzle.
2. The radiant tube low-nitrogen burner with multiple flow diverters of claim 1, wherein: the lower extreme of two air injection nozzles all is equipped with the necking down.
3. The radiant tube low-nitrogen burner with multiple flow diverters of claim 1, wherein: the second injection channel is a bent pipe and is connected with the first injection channel through an S-shaped bend, the lower end of the second injection channel is a reducing pipe, the reducing pipe penetrates through the first injection channel and is arranged in the first injection channel, and the outflow direction of gas in the reducing pipe is consistent with the flow direction of air in the first injection channel.
4. The radiant tube low-nitrogen burner with multiple flow diverters of claim 1, wherein: the smoke outlet end and the air inlet end are coaxial, and the smoke outlet end is sleeved on the air inlet end.
5. The radiant tube low-nitrogen burner with multiple flow-guiding as claimed in claim 1 or 4, characterized in that: the right end of the smoke outlet end is communicated with the U-shaped pipe body.
6. The radiant tube low-nitrogen burner with multiple flow-directing according to claim 1 or 3, characterized in that: the second injection channels can be arranged in a plurality of numbers, the second injection channels are dispersedly distributed by taking the first injection channels as centers, and the lower ends of the second injection channels are inserted into the first injection channels in an up-and-down staggered mode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911262742.0A CN110822428A (en) | 2019-12-11 | 2019-12-11 | Radiant tube low-nitrogen burner with multiple drainage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911262742.0A CN110822428A (en) | 2019-12-11 | 2019-12-11 | Radiant tube low-nitrogen burner with multiple drainage |
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| Publication Number | Publication Date |
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| CN110822428A true CN110822428A (en) | 2020-02-21 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201911262742.0A Pending CN110822428A (en) | 2019-12-11 | 2019-12-11 | Radiant tube low-nitrogen burner with multiple drainage |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112524606A (en) * | 2020-12-04 | 2021-03-19 | 武汉科技大学 | Radiant tube burner capable of realizing flameless combustion by entraining smoke |
-
2019
- 2019-12-11 CN CN201911262742.0A patent/CN110822428A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112524606A (en) * | 2020-12-04 | 2021-03-19 | 武汉科技大学 | Radiant tube burner capable of realizing flameless combustion by entraining smoke |
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