CN101691925A - Fuel gas radiating tube - Google Patents
Fuel gas radiating tube Download PDFInfo
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- CN101691925A CN101691925A CN200910209558A CN200910209558A CN101691925A CN 101691925 A CN101691925 A CN 101691925A CN 200910209558 A CN200910209558 A CN 200910209558A CN 200910209558 A CN200910209558 A CN 200910209558A CN 101691925 A CN101691925 A CN 101691925A
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- radiant tube
- heat
- foam metal
- porous foam
- radiating tube
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Abstract
The invention discloses a fuel gas radiating tube. A low temperature segment of the fuel gas radiating tube is filled with porous foam metal having an open celled structure. In the fuel gas radiating tube, the amount of radiation heat exchange between fume and the inner wall of the radiating tube is increased, an coefficient of convective heat transfer between the fume and the inner wall of the radiating tube is increased, and the heat-flow density and the temperature of the inner wall of the low temperature segment of the radiating tube are improved, so that the surface temperature uniformity and the heat efficiency of the radiating tube are improved.
Description
Technical field
A kind of gas fired radiant tubes that this patent relates to is particularly to the improvement of gas fired radiant tubes.
Background technology
Gas fired radiant tubes is a kind of heater of burning gases fuel; gaseous fuel is in the radiant tube internal combustion of sealing; by the tube-surface that is heated is that principal mode is delivered to heating object to heat with the heat radiation; combustion atmosphere does not contact with heating object with product; this is specially adapted to the demanding occasion of product quality just for to heat-treat the condition created under protective atmosphere.Gas fired radiant tubes has characteristics such as combustion thermal efficiency height, stable, equipment dependability height, is widely used in various heat-treatment furnaces and continuous annealing furnace etc.
According to the cast of radiant tube, can be divided into straight pipe type, thimble tube, U type, W type, three forked types, P type, double-P type etc.Radiant tube surface temperature distribution uniformity is its important performance indications, and surface temperature distribution is even more good more.
At present, combustion process in the gas fired radiant tubes is generally as follows: fuel is sprayed by burner, light rear section fuel and primary air generation combustion reaction through igniter, remaining fuel and auxiliary air reaction carrying out second-time burning, flame is diffusion flame, so that reduce the oxynitrides growing amount, increases the length of flame, the high-temperature flue gas that produces with the heat transferred radiant tube, and then carries out radiation heating by the radiant tube outer wall to material in the stove in the mode of radiation and convection current; Reflux along the radiant tube outer tube wall behind the high-temperature flue gas distribute heat, sub-fraction participates in burning once more, i.e. flue gas recirculation (EGR), and remainder is undertaken discharging after the exchange heat by heat exchanger and cold air.
No matter be the radiant tube of which kind of type, in combustion process, because higher in the flame zone flue-gas temperature, radiant heat flux density is big, and the radiant tube wall temperature is higher, forms the high temperature section of radiant tube; And flue gas and radiant tube are along in the journey heat transfer process behind flame zone, and flue-gas temperature reduces gradually, and radiant heat flux reduces, and the radiant tube temperature is lower, form the low-temperature zone of radiant tube, and the temperature distributing rule of this radiant tube has been tested and think tank confirms.Therefore inevitably cause the inhomogeneities of radiant tube surface temperature, thereby influence the heating efficiency and the heating quality of radiant tube, the service life of having reduced radiant tube.
Gas fired radiant tubes in use constantly is improved, main corrective measure as the exploitation of: (1) Britain from the preheating type radiant tube, utilize the waste heat of flue gas that air is carried out preheating, improved the efficiency of combustion and the capacity usage ratio of radiant tube; (2) in radiant tube, increase inner sleeve, adopt the second-time burning pattern, can increase the uniformity that the length of flame also can improve the radiant tube wall temperature; (3) in radiant tube, use pellet can improve the utilization rate of fuel significantly, control the air consumption coefficient preferably, strengthen the convection heat transfer' heat-transfer by convection between gas and the radiant tube tube wall, thereby improve the surface temperature distribution of radiant tube; (4) technology such as application of air sectional combustion, combustion gas premix and diffusion combustion, the steady flame of eddy flow, flame noise reduction on radiation pipe apparatus can increase the length of flame and reduce combustion noise; (5) many corrective measures are being proposed on the heat exchanger of preheating type radiant tube, as efflux heat-exchanger, have spiral fluted space gas heat exchanger, adopt the heat exchanger of partition jet flow sandwich, the injecting type heat exchanger, rifle formula heat exchanger, accumulation of heat and partition heat exchange composite construction, distort belt insert material heat exchanger etc.; (6) each component part at radiant tube is optimized design, such as at U type radiant tube weld welding reinforcing ring, supporting mechanism is drawn outside the stove, increases the radiant tube surface roughness, uses ceramic material and adopts oxygen-enriched combustion technology etc.But the corrective measure that low-temperature zone is carried out augmentation of heat transfer in radiant tube yet there are no report.
Foam metal is a kind of novel low-density functional structure material, has that bulk density is little, relative mass is light, specific area is big, than characteristics such as mechanics performance height, damping capacity be good.The notable feature of foam metal is that its inside has a large amount of holes, according to the branch that whether is linked with open-celled structure and hole-closing structure between each hole.Because the foam metal of open-celled structure has bigger accessible surface long-pending, higher hole wall pyroconductivity and smaller volume specific heat capacity, thereby makes it possess superior heat transfer potential.
Summary of the invention
The objective of the invention is to improve the radiation heat transfer ability of radiant tube low-temperature zone fume side, increase the radiation heat transfer amount between flue gas and radiant tube inwall, increase the convection transfer rate between flue gas and radiant tube inwall, improve the heat flow density and the tube wall temperature of radiant tube low-temperature zone, thereby improve the surface temperature uniformity and the thermal efficiency of radiant tube.
The technical solution adopted for the present invention to solve the technical problems is: a kind of gas fired radiant tubes, and the low-temperature zone of described gas fired radiant tubes is filled with porous foam metal, and described porous foam metal is an open-celled structure.
Technique scheme can further be improved to: described porous foam metal is resistant to elevated temperatures porous foam metal, and high temperature resistant limiting value is 1000～1400 ℃.
Technique scheme can further be improved to: described porous foam metal can carry out surface-coated by plasma spray technology to be handled, and sprayed on material is metal or pottery, to improve its blackness and radiance.
Technique scheme can further be improved to: described porous foam metal is that titanium is foam metal, blister steel or the foamed aluminium of matrix.
Beneficial effect of the present invention is: the porous foam metal of filling open-celled structure in the low-temperature zone of gas fired radiant tubes, flue gas is converted to the comprehensive heat radiation to inwall of flue gas and porous foam metal solid skeletal to the heat radiation of radiant tube inwall, be equivalent to increase the blackness of flue gas, will increase substantially the thermal radiation capability of radiant tube low-temperature zone fume side, the radiation heat transfer amount will double above according to a preliminary estimate; Simultaneously owing to increased the disturbance of air-flow in the radiant tube low-temperature zone and the equivalent thermal conductivity of flue gas, convection transfer rate also can obviously increase, therefore can be from the heat transfer resistance between heat radiation and two aspects minimizing flue gases of heat convection and radiant tube inwall, improve the heat flow density and the tube wall temperature of radiant tube low-temperature zone, thereby improve the surface temperature uniformity and the thermal efficiency of radiant tube.And this radiant tube is simple in structure, low cost of manufacture.
Description of drawings
Fig. 1 is the structural representation of heat accumulating type U type radiant tube burner.
Fig. 2 is the structural representation of heat accumulating type W type radiant tube burner.
Fig. 3 is the structural representation from preheating type gas fired radiant tubes burner.
The specific embodiment
Below in conjunction with accompanying drawing of the present invention specifically practicing laid down a definition.
Fig. 1 is applied to a kind of embodiment of heat accumulating type U type radiant tube burner for a kind of improved gas fired radiant tubes of the present invention.The gas fired radiant tubes that this heat accumulating type U type gas fired radiant tubes burner is cut valve 2, four-way change-over valve 3, heat storage 4 and the application soon by fuel burner nozzle 1, coal gas is formed.Wherein gas fired radiant tubes is made up of radiant tube body 5 and porous foam metal 6, and the low-temperature zone of gas fired radiant tubes is filled with porous foam metal 6, and porous foam metal 6 is an open-celled structure.
Its operation principle is: cold air enters heat storage 4 heating of the A end of U type radiant tube one end fuel burner nozzle 1 earlier through four-way change-over valve 3, burn with fuel mix, behind the heat storage 4 of the B end of the hot flue gas heating other end fuel burner nozzle 1 in the radiant tube, discharge by flue through four-way change-over valve 3.Switch through four-way change-over valve after the time of setting 3, change gas flow direction in the radiant tube, cold air is flowed into by the B end, and flue gas is discharged by the A end.Cold air and hot flue gas so alternately the flow through A of fuel burner nozzle 1, the heat storage 4 at B two ends, by the heat storage heat-shift, air can be preheated near the radiant tube tube wall temperature, and flue-gas temperature can be reduced to below 200 ℃, thereby the limit that realizes flue gas heat reclaims.The break-make of the conversion of air, flow of flue gas direction and burner fuel gas is cut valve 2, four-way change-over valve 3 and control system soon by coal gas and is realized.Heat accumulation type radiant tube air, flue gas in running need commutation regularly, its flow direction periodically-varied in radiant tube.
Before radiant tube half section since the fuel gas buring flame temperature very high, thermal radiation capability is strong, so the straight tube of radiant tube body 5 is a high temperature section for preceding half section, and straight tube second half section and bend pipe junction are because the temperature of flue gas is lower than flame temperature, and blackness less (being generally 0.1～0.3), thermal radiation capability is less, and straight tube second half section and bend pipe junction are low-temperature zone, and the temperature distributing rule of this radiant tube has been tested and think tank confirms.Fill the porous foam metal 6 of open-celled structure in the low-temperature zone of radiant tube, as titanium is foam metal, blister steel or the foamed aluminium (high temperature resistant behind the high-temperature oxydation) of matrix, can significantly improve blackness, equivalent heat conductivity and the convection transfer rate of flue gas, increase radiation heat transfer amount and heat convection amount between flue gas and radiant tube inwall, reduce the heat exchange thermal resistance, improve the heat flow density and the radiant tube temperature of low-temperature zone, thereby improve the surface temperature uniformity and the thermal efficiency of radiant tube.
Fig. 2 is applied to second kind of embodiment of heat accumulating type W type radiant tube burner for a kind of improved gas fired radiant tubes of the present invention.The operation principle of this W type radiant tube is with embodiment 1.Centre two straight tubes and the bend pipe junction thereof of radiant tube body 5 are low-temperature zone, in this section pipe, fill resistant to elevated temperatures porous foam metal 6, as titanium is foam metal, blister steel or the foamed aluminium of matrix, can significantly improve blackness, equivalent heat conductivity and the convection transfer rate of flue gas, increase radiation heat transfer amount and heat convection amount between flue gas and radiant tube inwall, promptly improve the radiant tube temperature of heat flow density and low-temperature zone, thereby improve the surface temperature uniformity and the thermal efficiency of radiant tube.
Fig. 3 is that a kind of improved gas fired radiant tubes of the present invention is applied to the third embodiment from the preheating type radiant tube burner.Its operation principle is: combustion gas is by burner 31 ejections, light rear section combustion gas and the burning of primary air reaction generation one-level through igniter, then with auxiliary air reaction carrying out second-time burning, so that reduce the oxynitrides growing amount, increase the length of flame, the high-temperature flue gas that produces passes to radiant tube body 5 with heat by internal lining pipe 7 in the mode of radiation and convection current, and then material in the stove is carried out radiation heating; High-temperature flue gas refluxes along the circumferential weld of radiant tube body 5 and internal lining pipe 7 compositions, wherein sub-fraction participates in combustion process once more, be flue gas recirculation (EGR), remainder is undertaken being discharged by smoke reflux device 8 after the exchange heat by heat exchanger 9 and cold air, reclaim fume afterheat, cold air can be preheated to more than 300 ℃.
Flue-gas temperature is lower in the circumferential weld that radiant tube body 5 and internal lining pipe 7 are formed, form low-temperature zone, in this low-temperature zone, fill resistant to elevated temperatures porous foam metal 6, as titanium is foam metal, blister steel or the foamed aluminium of matrix, can significantly improve blackness, equivalent heat conductivity and the convection transfer rate of flue gas, increase radiation heat transfer amount and heat convection amount between flue gas and radiant tube inwall, promptly improve the radiant tube temperature of heat flow density and low-temperature zone, thereby improve the surface temperature uniformity and the thermal efficiency of radiant tube.
Above-mentioned porous foam metal 6 preferred resistant to elevated temperatures porous foam metals, high temperature resistant limiting value is 1000～1400 ℃, occurrence is relevant with the environment for use of burner.
Above-mentioned porous foam metal 6 can carry out coating surface by plasma spray technology to be handled, to improve its blackness and radiance.Thermal spraying is a kind of sufacing that utilizes the powder of fusing or wire rod to realize, the material that sprays fusing by gas quickens and is transported on the surface that needs to apply.The energy of fusing can be electric arc or inert gas plasma.Sprayed on material can be metal or pottery.
Above-mentioned porous foam metal 6 preferred hole diameter are between tens microns to several millimeters.The diameter of hole need be determined according to the calculating and the experiment of heat transfer and resistance.
Above-mentioned porous foam metal is that titanium is foam metal, blister steel or the foamed aluminium of matrix.Can obtain by methods such as model casting, deposition or solid frameworks.
The present invention does not limit to above embodiment; can also be transformed into the radiant tube (as straight pipe type, thimble tube, three forked types, P type, double-P type etc.) of other shapes and version; no matter be conventional pattern; self-preheating type or heat accumulating type; but so long as gas fired radiant tubes; and filled and process metal in the radiant tube all falls into protection scope of the present invention.
Claims (4)
1. gas fired radiant tubes, it is characterized in that: the low-temperature zone of described gas fired radiant tubes is filled with porous foam metal, and described porous foam metal is an open-celled structure.
2. a kind of gas fired radiant tubes according to claim 1 is characterized in that: described porous foam metal is resistant to elevated temperatures porous foam metal, and high temperature resistant limiting value is 1000～1400 ℃.
3. a kind of gas fired radiant tubes according to claim 1 and 2 is characterized in that: described porous foam metal can carry out surface-coated by plasma spray technology to be handled, and sprayed on material is metal or pottery, to improve its blackness and radiance.
4. a kind of gas fired radiant tubes according to claim 3 is characterized in that: described porous foam metal is that titanium is foam metal, blister steel or the foamed aluminium of matrix.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910209558A CN101691925A (en) | 2009-10-29 | 2009-10-29 | Fuel gas radiating tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910209558A CN101691925A (en) | 2009-10-29 | 2009-10-29 | Fuel gas radiating tube |
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| Publication Number | Publication Date |
|---|---|
| CN101691925A true CN101691925A (en) | 2010-04-07 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200910209558A Pending CN101691925A (en) | 2009-10-29 | 2009-10-29 | Fuel gas radiating tube |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103453520A (en) * | 2012-06-04 | 2013-12-18 | 大连拓新能源有限公司 | Intelligent temperature control and energy saving combustion furnace |
| CN104456560A (en) * | 2014-10-22 | 2015-03-25 | 北京神雾环境能源科技集团股份有限公司 | Porous-medium radiation tube |
| CN105465784A (en) * | 2016-01-26 | 2016-04-06 | 佛山市科皓燃烧设备制造有限公司 | Regenerative radiant tube burner with flue gas recirculation |
-
2009
- 2009-10-29 CN CN200910209558A patent/CN101691925A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103453520A (en) * | 2012-06-04 | 2013-12-18 | 大连拓新能源有限公司 | Intelligent temperature control and energy saving combustion furnace |
| CN104456560A (en) * | 2014-10-22 | 2015-03-25 | 北京神雾环境能源科技集团股份有限公司 | Porous-medium radiation tube |
| CN104456560B (en) * | 2014-10-22 | 2017-06-27 | 北京神雾环境能源科技集团股份有限公司 | Porous media radiant tube |
| CN105465784A (en) * | 2016-01-26 | 2016-04-06 | 佛山市科皓燃烧设备制造有限公司 | Regenerative radiant tube burner with flue gas recirculation |
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Open date: 20100407 |