CN201770662U - Cracking furnace tube based on field synergy effect - Google Patents
Cracking furnace tube based on field synergy effect Download PDFInfo
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- CN201770662U CN201770662U CN201020187218XU CN201020187218U CN201770662U CN 201770662 U CN201770662 U CN 201770662U CN 201020187218X U CN201020187218X U CN 201020187218XU CN 201020187218 U CN201020187218 U CN 201020187218U CN 201770662 U CN201770662 U CN 201770662U
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Abstract
The utility model relates to a furnace tube for an ethylene cracking furnace radiation section, which is characterized in that a plurality of inwardly projecting and axially spiral circular arc flow guide grooves are evenly distributed on the wall of the furnace tube, the furnace tube sequentially includes a guide section and a stabilizing section in the flowing direction of materials, the spiral angle of the guide section is gradually increased and ranges from 0 degree to 60 degrees, the length of the guide section is 5-50 times of the inner diameter of the furnace tube, the spiral angle of the flow guide groove in the stabilizing section is constant and is the same with that of the tail end of the guide section when the furnace tube reaches a certain angle and enters the stabilizing section, and the inwardly projecting height inside each flow guide groove is no more than 1/6 of the inner diameter of the tube. The furnace tube leads the materials to generate radially secondary flow inside the tube by the aid of the spiral flow guide grooves distributed on the tube wall, and forms concentration and density gradient favorable for cracking reaction under the action of the secondary flow so as to achieve the purposes of reducing tube wall temperature, improving ethylene yield and decreasing coking.
Description
Technical field
The present invention relates to a kind of boiler tube that is used for ethane cracking furnace or other tube cracking furnace radiation section, relate in particular to a kind of flow state that can improve material in the pipe, enhancement of heat transfer, mass transfer effect, and can promote scission reaction, improve the target product yield, reduce the cracking furnace pipe that coking produces.
Background technology
The tubular type cracking process is the main method of present ethylene production.Adopt the ethene of tube cracking furnace production to account for more than 99% of world Ethylene ultimate production.It is generally acknowledged that for the cracking of ethylene reaction, higher temperature, the short residence time, lower hydrocarbon partial pressure help the generation of target product (ethene, propylene) and suppress the generation of side reaction.Because the required heat of raw material cracking passes to the cracking material by tube wall, cracking temperature obviously is subjected to the restriction of radiator tube pipe surface temperature, and pipe surface temperature is subjected to the restriction of metallic substance resistance toheat.In recent years, because the effort of ethylene production enterprise and metallurgical technology research unit, the ethylene cracking tube tolerable temperature has been brought up to about 1150 ℃, but continues to improve very difficult.
Because in the Flow of Goods and Materials process, the material main body flows in the turbulent flow mode, temperature is even relatively, there is one with the mobile viscous flow thin layer of layer flow mode and press close to the tube wall place, heat mainly passes through with heat exchange pattern in the laminar flow, the intraductal heat transfer resistance overwhelming majority concentrates in the viscous flow thin layer, studies show that, in smooth pipe, tube wall place temperature and bodies of fluid temperature differ 200～300 ℃, and the consequence that causes is to press close to tube wall place temperature height, and flow velocity is slow, scission reaction speed is fast, but coking also takes place simultaneously easily; And the main part temperature is lower, and scission reaction is slower, causes target product yield low.
In order to address the above problem, numerous ethylene production enterprises and scientific research institution improve the ethane cracking furnace tubular construction, mainly start with from two aspects: the one, and the heat transfer area of increase boiler tube: as the single tube journey narrow tube of Kellogg company exploitation; The oval tube of MIT's exploitation; The 8 wing internal screw plum blossoms pipe of Lummus company; The straight type plum blossom pipe of Exxon company.The 2nd, adopt the flow-disturbing measure, destroy the detention layer of tube wall, reduce heat transmission resistance.Ethylene cracking tube as the built-in distortion sheet of LG Chemical Ltd., BeiJing, China chemical research institute exploitation.Its final purpose is an enhancement of heat transfer, makes the interior temperature of charge of pipe be tending towards even.
Though reduced the radial temperature difference in the pipe by increasing the intraductal heat transfer Method for Area, because heat-transfer surface also is the coking position simultaneously, the dwindling and caused coking more responsively of flow area, thereby coke cleaning period shortening is unfavorable for the operation of pyrolyzer.
By in pipe, increasing the method for turbolator, improved the turbulent extent of material in the pipe and, dwindled the radial temperature difference in the pipe to a certain extent, helped weakening the generation of coking the washing away of tube wall, but turbolator has occupied the useful volume in the pipe in the pipe, and resistance to flow enlarges markedly in the pipe.
Summary of the invention
The object of the present invention is to provide a kind of boiler tube that is used for the ethane cracking furnace radiation section, this boiler tube not only can improve the heat-transfer effect in the pipe, what is more important, by improving the Flow of Goods and Materials state, make in the pipe that reactant and product distribute according to the mode that meets the thermal load needs in the material, thereby improve target product yield, reduce coking, reduce pipe surface temperature, improve the boiler tube life-span.
Know-why of the present invention is: the cracking of ethylene raw material is in pipe in the flow process, press close to the tube wall place and form a viscous flow thin layer, in this viscous flow thin layer, heat can only be by the heat exchange pattern transmission, thereby temperature difference impellent that need be very big, thermal resistance in the pipe mainly concentrates in this viscous flow thin layer, ethene is in cracking process, macromolecular reactant is broken down into micromolecular product, thereby form the different fluid micellar of density in the part, under the effect of spiral stream guidance groove, Flow of Goods and Materials forms spiral secondary stream, helicoidal flow at first produces near tube wall, and then because the effect of inter gas drives the gas of whole runner flows in the shape of a spiral.Because the centrifugation that secondary stream produces, the fluid micellar that reactant concn is higher, density is bigger is to the motion of tube wall direction, and the fluid micellar that production concentration is higher, density is less has formed the concentration field with finite concentration gradient to the motion of pipe center position.Because the required heat of reaction is transmitted in pipe by tube wall, thereby it is higher near tube wall place temperature, help the carrying out that react, and it is lower away from tube wall place temperature, be unfavorable for reacting and carry out, therefore, the generation of volution secondary stream has promoted the carrying out of cracking of ethylene reaction, has promptly formed the field synergy effect in flow field, concentration field and temperature field.Simultaneously, the projection of diversion trench plays flow-disturbing, destruction to pressing close to tube wall mobile detention layer, has therefore reduced heat transmission resistance, makes the temperature of tube fluid more approach pipe surface temperature.
The present invention is achieved by the following technical solutions:
A kind of cracking furnace pipe based on field synergy effect, it is characterized in that, be evenly distributed with the cracking furnace pipe 2 of one or more inwardly protruded diversion trench 1 on one root canal wall, diversion trench 1 axially distributes twist along boiler tube, cracking furnace pipe 2 is along the Flow of Goods and Materials direction, be followed successively by boot segment L1 and stable section L2, boot segment L1 length is 5～50 times of bore, at boot segment L1, pitch angle alpha will (angle of spiral stream guidance groove and boiler tube axis) is gradually, increase continuously, its variation range between 0～60 degree, enter stable section after, pitch angle alpha will is a constant, and identical with the helix angle angle of boot segment end.
In the technique scheme, the bar number of diversion trench 1 is preferably 1～16.
In the technique scheme, the hand of spiral of diversion trench 1 can also can be dextrorotary to anticlockwise, and the spiral angle that is positioned at the diversion trench 1 of same radial section is identical.
In the technique scheme, the diversion trench cross-sectional shape is inwardly protruded circular-arc or oval arcuation, and its arc length is no more than circle or oval 1/2nd.The height of diversion trench 1 inside pipe wall projection is no more than 1/6 of bore.
In the technique scheme, inside pipe wall diversion trench 1 position that links to each other with tube wall is a smooth transition.
The purpose that diversion trench is set is: one, on tube wall, form spiral flow channel, when cracking stock gas passes through, under the effect of diversion trench, produce circinate secondary stream, under the centrifugation of secondary stream, the reactant micelle that density is bigger is assembled to tube wall, the less product micelle of density then is forced to the tube hub motion, form the concentration distribution that helps the cracking of ethylene reaction, when the reactant of pressing close to tube wall at high temperature is cracked into the product of light constituent, squeezed the pipe center by the bigger reactant micelle of density again, so go round and begin again, promote the carrying out of cracking of ethylene reaction.
Its two, diversion trench is to inner process, makes along tube wall mobile viscous flow thin layer destroyedly, reduced the generation of heat transmission resistance and coking.
The purpose that the diversion trench spiral angle increases gradually is: make the secondary flow of material have a process of strengthening gradually.When material just enters cracking furnace pipe, because material concentration is consistent everywhere, do not need to produce the intensive secondary stream, and after scission reaction begins, just form concentration difference, so need secondary stream to strengthen gradually.In addition, enter the stage at material, bigger helix angle can produce stronger flow-disturbing effect, destroys the formation of secondary stream, therefore, needs less helix angle in the initial stage.
The number of diversion trench (bar number) can be one, also can be a plurality of.In principle, more diversion trench has the effect that produces secondary stream preferably, but the diversion trench number is too many, and then the diversion trench height is too little, and effect reduces on the contrary, and therefore, the only number of diversion trench is at 1～16.
For fear of the Flow of Goods and Materials dead angle occurring, the inside pipe wall diversion trench position that links to each other with tube wall is a smooth transition.
Beneficial effect
Advantage of the present invention and progressive being: 1. by the guide functions of diversion trench, form the radial secondary stream, the distribution that promotes the cracking component is carried out to helping the direction that scission reaction further carries out, thereby helps improving the yield of target product.2. owing to destroyed detention layer in the pipe, reduce heat transmission resistance, therefore helped reducing pipe surface temperature, and then can reduce temperature difference impellent, can reduce fire box temperature, reduced fuel consumption.3. owing to the reduction of pipe surface temperature, reduced the generation of coking, thereby helped prolonging coke cleaning period, and because the destruction of detention layer, even coking takes place, burnt layer is also more loose, easier removing.4. because the reduction of pipe surface temperature, can prolong the work-ing life of boiler tube or reduce requirement furnace tube material.
Description of drawings
Fig. 1 is the front view with boiler tube of 4 diversion trenchs of the present invention.
Wherein, 1-diversion trench, 2-cracking furnace pipe, L1-diversion section, L2 stable section, alpha-helix angle, Flow of Goods and Materials direction in the F-pipe.
Fig. 2 is the radial section figure of the boiler tube of 4 diversion trenchs of the present invention.
Wherein, 1-diversion trench, 2-cracking furnace pipe.
Fig. 3 is the front view with boiler tube of 1 diversion trench of the present invention.
Wherein, 1-diversion trench, 2-cracking furnace pipe, L1-diversion section, L2 stable section, alpha-helix angle, Flow of Goods and Materials direction in the F-pipe.
Fig. 4 is the radial section figure with boiler tube of 1 diversion trench.
Wherein, 1-diversion trench, 2-cracking furnace pipe.
Embodiment
Below in conjunction with description of drawings concrete structure of the present invention
Fig. 1 is the front view of the ethylene cracking tube with 4 diversion trenchs that the present invention relates to, can understand the structure of patent of the present invention intuitively by Fig. 1.The ethylene cracking tube that the present invention relates to can be installed on separately in the ethane cracking furnace, also can with smooth boiler tube aggregate erection in ethane cracking furnace.
The boiler tube structure that the present invention relates to is divided into boot segment L1 and stable section L2, boot segment pitch angle alpha will (angle of spiral stream guidance groove and tube axis) is gradually, increases continuously, its variation range is between 0～60 degree, when increasing to a certain angle, enter stable section, at pipe stable section L2, the angle of spiral stream guidance groove and axis is a constant.Fig. 2 is radial section figure of the present invention, and structural pipe wall comprises diversion trench 1 and tube wall 2, and the diversion trench number can be one, also can be a plurality of, and number is 1～16, along tube wall circumference uniform distribution.The diversion trench cross-sectional shape is inwardly protruded circular-arc or oval arcuation, and its arc length is no more than circle or oval 1/2nd; The height of diversion trench inside pipe wall projection is no more than the sixth of bore; The fillet processing is carried out in tube wall curved surface turning point, and it all is level and smooth making inside pipe wall everywhere.As shown in Figure 1, Flow of Goods and Materials direction in F represents to manage.Material is entered the boot segment L1 of boiler tube by top, in boot segment, begin to take place scission reaction, and under diversion trench 1 effect, produce the volution secondary stream gradually, because the diversion trench helix angle increases gradually, therefore the spiral secondary stream that produces is more and more stronger, under the centrifugation of spiral secondary stream, heavy constituent in the material (mainly being the cracking stock component) are moved to tube wall, when the reactant of pressing close to tube wall at high temperature is cracked into the product of light constituent, squeezed the pipe center by the bigger reactant micelle of density again, then to the tube hub motion, so go round and begin again to have formed helps the concentration distribution that scission reaction is carried out to light constituent (mainly being split product), promotes the carrying out of cracking of ethylene reaction.At stable section, if the diversion trench helix angle continues to increase, then the flow-disturbing effect is too strong, disturbs the generation of secondary stream, and therefore, helix angle enters stable section L2 after increasing to certain angle, and pitch angle alpha will no longer changes.
Embodiment
According to know-why of the present invention, carried out the cracking of ethylene experiment test, and in same pyrolyzer He under the identical operations condition, compared test with smooth pipe, measuring temperature out, yield of ethene and tube drop.Operational condition sees Table 1, and test result sees Table 2, table 3.
Table 1 test operation condition
Table 2 test result 1 (initial operating stage)
| Project | Boiler tube of the present invention | Boiler tube of the present invention | Smooth pipe |
| The tube-surface temperature | 990℃ | 925℃ | 1015℃ |
| Temperature out | 855℃ | 809℃ | 812℃ |
| Tube drop | 62kPa | 57kPa | 43kPa |
| Yield of ethene | 33.6％ | 31.2％ | 30.5％ |
Table 3 test result 2 (moving 25 days)
| Project | Boiler tube of the present invention | Smooth pipe |
| The tube-surface temperature | 1032℃ | 1095℃ |
| Temperature out | 830℃ | 760℃ |
| Tube drop | 75kPa | 86kPa |
| Yield of ethene | 30.2％ | 26.2％ |
By table 2 as seen, at the test run initial stage, because the field synergy effect and the enhancement of heat transfer effect of boiler tube of the present invention, the pipe internal-external temperature difference reduces significantly, and under identical fire box temperature, the tube-surface temperature is low 25 ℃ than smooth pipe, and the material outlet temperature is high 43 ℃ in the pipe, promptly manage internal-external temperature difference and reduce by 68 ℃, yield of ethene brings up to 33.6% by 30.5%, improves 10% relatively.That is, under close tube-surface temperature, the yield of ethene height, and also temperature out is low, heat-transfer effect good (seeing Table the contrast of 2 first hurdles and third column data).
In table 2, for material in will managing compares under identical temperature condition, fire box temperature is suitably reduced, make interior material outlet temperature of boiler tube pipe of the present invention and the interior material outlet temperature of smooth pipe pipe approaching.Yield of ethene still is higher than smooth pipe in the boiler tube of the present invention at this moment.This shows, under the effect of field synergy effect, because reactant concn and temperature distribution in the pipe have adapted to the needs of scission reaction, thereby helps to improve yield of ethene.At initial operating stage, resistance to flow increases about 35% than smooth pipe in the boiler tube pipe of the present invention.(seeing Table the contrast of 2 second hurdles and third column data).
Usually, coking situation is estimated by resistance to flow in temperature of charge and the pipe in tube-surface temperature, the pipe.By table 3 as seen, move after 25 days, because the influence of coking, the smooth pipe surface temperature obviously rises, and the material outlet temperature descends in the pipe, and yield of ethene descends.Compare with smooth pipe, tube coking situation of the present invention is obviously improved, and yield of ethene brings up to 30.2% by 26.2%, improves 15% relatively.And because the coking degree significantly reduces, resistance is low than smooth pipe.
By the operation test as seen, boiler tube of the present invention is the Flow of Goods and Materials situation in improving pipe, and enhancement of heat transfer improves yield of ethene, and reducing the coking aspect all has obvious effect, and yield of ethene has 10%～15% raising.Though the interior resistance to flow of pipe is big than smooth pipe, owing to reduce the effect of coking, is lower than the resistance of smooth pipe on the contrary in the operation later stage, so does not occupy inferior position on resistance to flow.
Claims (6)
1. cracking furnace pipe based on field synergy effect, it is characterized in that, be evenly distributed with the cracking furnace pipe (2) of one or more inwardly protruded diversion trench (1) on one root canal wall, diversion trench (1) axially distributes twist along boiler tube, cracking furnace pipe (2) is along the Flow of Goods and Materials direction, be followed successively by boot segment L1 and stable section L2, boot segment L1 length is 5～50 times of bore, on boot segment L1, pitch angle alpha will increases gradually, the angle variation range of pitch angle alpha will 0～60 the degree between, enter stable section after, pitch angle alpha will is a constant, and identical with the helix angle angle of boot segment end.
2. a kind of cracking furnace pipe based on field synergy effect as claimed in claim 1 is characterized in that, the number of diversion trench (1) is less than or equals 16.
3. a kind of cracking furnace pipe based on field synergy effect as claimed in claim 1 is characterized in that, the spiral angle that is positioned at the diversion trench (1) of same radial section is identical.
4. a kind of cracking furnace pipe based on field synergy effect as claimed in claim 1 is characterized in that, diversion trench (1) cross-sectional shape is inwardly protruded circular-arc or oval arcuation, and its arc length is no more than circle or oval 1/2nd.
5. a kind of cracking furnace pipe based on field synergy effect as claimed in claim 1 is characterized in that, the height of diversion trench (1) inside pipe wall projection is no more than 1/6 of bore.
6. a kind of cracking furnace pipe based on field synergy effect as claimed in claim 1 is characterized in that, inside pipe wall diversion trench (1) position that links to each other with tube wall is that smooth transition links to each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201020187218XU CN201770662U (en) | 2010-05-07 | 2010-05-07 | Cracking furnace tube based on field synergy effect |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201020187218XU CN201770662U (en) | 2010-05-07 | 2010-05-07 | Cracking furnace tube based on field synergy effect |
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| CN201770662U true CN201770662U (en) | 2011-03-23 |
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| CN201020187218XU Expired - Lifetime CN201770662U (en) | 2010-05-07 | 2010-05-07 | Cracking furnace tube based on field synergy effect |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101824333A (en) * | 2010-05-07 | 2010-09-08 | 华东理工大学 | Field synergy effect-based cracking furnace tube |
| WO2017007649A1 (en) | 2015-07-09 | 2017-01-12 | Sabic Global Technologies B.V. | Minimizing coke formation in a hydrocarbon cracker system |
| CN109724445A (en) * | 2017-10-27 | 2019-05-07 | 中国石油化工股份有限公司 | Augmentation of heat transfer pipe and pyrolysis furnace |
| US11220635B2 (en) * | 2017-04-07 | 2022-01-11 | Schmidt + Clemens Gmbh + Co. Kg | Pipe and device for thermally cleaving hydrocarbons |
-
2010
- 2010-05-07 CN CN201020187218XU patent/CN201770662U/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101824333A (en) * | 2010-05-07 | 2010-09-08 | 华东理工大学 | Field synergy effect-based cracking furnace tube |
| CN101824333B (en) * | 2010-05-07 | 2013-01-09 | 华东理工大学 | Field synergy effect-based cracking furnace tube |
| WO2017007649A1 (en) | 2015-07-09 | 2017-01-12 | Sabic Global Technologies B.V. | Minimizing coke formation in a hydrocarbon cracker system |
| US10611968B2 (en) | 2015-07-09 | 2020-04-07 | Sabic Global Technologies B.V. | Minimizing coke formation in a hydrocarbon cracker system |
| US11220635B2 (en) * | 2017-04-07 | 2022-01-11 | Schmidt + Clemens Gmbh + Co. Kg | Pipe and device for thermally cleaving hydrocarbons |
| CN109724445A (en) * | 2017-10-27 | 2019-05-07 | 中国石油化工股份有限公司 | Augmentation of heat transfer pipe and pyrolysis furnace |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20110323 Effective date of abandoning: 20130306 |
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| RGAV | Abandon patent right to avoid regrant |