CN102721320B - Anti-clogging method for heat exchanger and anti-clogging heat exchanger for acetonitrile purification - Google Patents
Anti-clogging method for heat exchanger and anti-clogging heat exchanger for acetonitrile purification Download PDFInfo
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- CN102721320B CN102721320B CN201210236366.XA CN201210236366A CN102721320B CN 102721320 B CN102721320 B CN 102721320B CN 201210236366 A CN201210236366 A CN 201210236366A CN 102721320 B CN102721320 B CN 102721320B
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Abstract
The invention provides an anti-clogging method for a heat exchanger and an anti-clogging heat exchanger for acetonitrile purification. The heat exchanger adopts a vertical fixed tube sheet type structure; a nozzle is placed in an upper channel box of the heat exchanger; partial cooled technological material subjected to heat exchange through the heat exchanger serves as washing fluid and is returned to an inlet of the heat exchanger; the washing fluid is mixed with a polymerization inhibitor at the inlet of the heat exchanger and sprayed in a heat exchange pipe through the nozzle; further the top of the heat exchange pipe adopts a zigzag structure, thereby facilitating the uniform distribution of the washing fluid in the heat exchange pipe; and the added washing fluid increases the total material quantity inside the heat exchange pipe, impact is increased, temperature is reduced, the blockage of the heat exchanger caused by prussic acid aggregation is effectively avoided, and the industrial application value is high.
Description
Technical field
The invention belongs to field of heat exchangers, especially relate to a kind of acetonitrile and purify with anti-blocking method and the anti-blocking heat exchanger of heat exchanger.
Background technology
Acetonitrile, as a kind of organic solvent of function admirable, is also the important source material of fine chemistry industry.Be widely used in the various fields such as petrochemical industry, medicine, agricultural chemicals, surfactant, dyestuff.The method of industrial production acetonitrile has direct synthesis technique (as reacting with acetic acid or propane or ethanol and ammonia) and indirect method, and indirect method mainly refers to from the ammoxidating propylene to produce acrylonitrile purification of the crude acetonitrile of by-product simultaneously and makes.At present, the latter is still the main source of industrial production acetonitrile, and its output accounts for 2%～3% of acrylonitrile output.
The crude acetonitrile being obtained by ammoxidating propylene to produce acrylonitrile is the water solution mixture that a kind of component is very complicated, and its main component is water and acetonitrile, also contains the impurity such as hydrogen cyanide, acrylonitrile simultaneously.At crude acetonitrile, enter in acetonitrile decyanation tower purification process, because the hydrogen cyanide containing in material has the feature of easy polymerization, and the hydrogen cyanide concentration ratio that tower top contains is higher, this just makes the structure of tower top heat exchanger of acetonitrile decyanation tower more crucial, as used traditional vertical tube-sheet heat exchanger (as shown in Figure 1), need to below heat exchanger, increase a return tank uses, increased arrangement space, and in traditional heat exchangers, the less turbulence of fluid in heat exchanger tube is low, be easy to cause heat exchanger tube build up of polymer, affect the heat transfer effect of heat exchanger, or even cause heat exchanger to stop up, the continuous operation of restriction heat exchanger, shortened the production cycle, if and frequent clean heat exchanger, its process may touch hydrogen cyanide, security risk also improves greatly thus.
Summary of the invention
The problem to be solved in the present invention is for for causing acetonitrile decyanation column overhead heat exchanger easily to stop up because polymerization easily occurs the hydrogen cyanide containing in crude acetonitrile in current acetonitrile purifying process, utilization rate of equipment and installations declines, the phenomenons such as security risk increase, provide a kind of practical acetonitrile to purify with anti-blocking method and the anti-blocking heat exchanger of heat exchanger.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of acetonitrile is purified with the anti-blocking method of heat exchanger, and described heat exchanger adopts vertical fixed tube sheet type structure, and the upper tube box of heat exchanger is built-in with shower nozzle; A part of process stream cooling after heat exchanger heat exchange is back to heat exchanger entrance as flushing liquor, and described flushing liquor sprays in heat exchanger tube by shower nozzle after heat exchanger entrance place is mixed with polymerization inhibitor.So, being equivalent to has increased one cold burden at heat exchanger entrance, has increased on the one hand total inventory in heat exchanger tube, increased impulsive force, also reduced feeding temperature, make hydrogen cyanide polymerization become difficult, and then effectively reduce the clogging producing because of hydrogen cyanide polymerization heat exchanger simultaneously.
Described shower nozzle can select solid-cone type shower nozzle etc. can form any shower nozzle pattern of solid circles spraying, and the minimum range of shower nozzle and tube sheet is 0.1D, and D is heat exchanger nominal diameter (mm).
Described polymerization inhibitor is selected from acetic acid, sulfuric acid or phosphoric acid, and the tower bottoms pH that its addition is assurance acetonitrile decyanation tower is at 3-5.
Preferably, the top of described heat exchanger tube adopts zigzag structure, is beneficial to flushing liquor being evenly distributed in pipe, is beneficial to heat transfer.
Preferably, the lower tube box of heat exchanger adopts autoclave structure, plays the effect of buffering and gas-liquid separation.
Preferably, in the lower tube box of described heat exchanger, be also provided with baffle plate, be beneficial to the effect of strengthening gas-liquid separation.Baffle plate is located at gaseous phase materials exit, goes out interruption-forming angle with gaseous phase materials.
Preferably, the flow that returns to the flushing liquor of heat exchanger entrance accounts for the 1/6-2/3 of process stream total mass flow rate cooling after heat exchanger heat exchange, choosing of flow within the scope of this, both can reach and play the effect of washing away, unlikelyly again because flow is excessive, cause that size of heat exchanger obviously increased therefrom.
Preferably, process stream (cooling material to be cooled) is walked tube side, and public work material (cooling material) is walked shell side.
Preferably, process stream is 0.5-6m/s at heat exchange velocity in pipes.
The present invention also provides a kind of heat exchanger for said method, comprises upper tube box, cylindrical shell and lower tube box; Upper tube box, cylindrical shell and lower tube box form vertical fixed tube sheet type structure, and the top of the heat exchanger tube in described cylindrical shell adopts zigzag structure;
Described upper tube box is built-in with shower nozzle and bobbin carriage is provided with process stream (process stream to be cooled) entrance and flushing liquor entrance, described flushing liquor entrance adds entrance with polymerization inhibitor and is communicated with, the entrance of described flushing liquor is communicated with described shower nozzle, makes flushing liquor by described shower nozzle, spray in the heat exchanger tube of heat exchanger;
Described cylindrical shell is provided with public work material inlet and public work material outlet;
Described lower tube box adopts autoclave structure, and described lower tube box is provided with liquid phase material (through the cooled liquid phase process material of heat exchange) outlet and gaseous phase materials outlet; Described liquid phase material outlet is communicated with flushing liquor entrance.
Preferably, in described lower tube box, be provided with baffle plate.
The present invention is not limited to and is applied in the heat exchanger block system causing because of hydrogen cyanide polymerization in acetonitrile purification process, can also be applied in any heat exchanger block system producing because of material polymerization simultaneously.
Advantage and good effect that the present invention has are:
1. for the feature of the easy polymerization of hydrogen cyanide, at heat exchanger entrance, the built-in shower nozzle by upper tube box draws one flushing liquor and enters heat exchanger tube in the present invention.The setting of built-in shower nozzle, is conducive to flushing liquor uniform fold in heat exchanger and arrives whole heat exchanger tube; Adding of flushing liquor also increased by total inventory of heat exchanger tube, and impulsive force increases, and makes polymer be difficult for being attached to exchanger tube wall, causes heat exchanger to stop up, and also guaranteed thus the heat-transfer effect of heat exchanger.
2. in heat exchanger of the present invention, heat exchanger tube top adopts broached-tooth design, is conducive to the Uniform Flow of flushing liquor in every heat exchanger tube, is beneficial to heat transfer.
3. the feature in the easier polymerization of alkali condition for hydrogen cyanide when increasing flushing liquor, adds the polymerization inhibitors such as acetic acid in flushing liquor simultaneously, makes material in sour environment, also can play the effect that stops hydrogen cyanide polymerization.
4. in the present invention, the low-temperature material of flushing liquor after by heat exchange forms, there is no the new chemical constituent of extra increase, and feeding temperature is reduced, cause hydrogen cyanide polymerization difficulty, the flow that returns to the flushing liquor of heat exchanger entrance is the 1/6-2/3 of overall process flow, and heat exchange velocity in pipes is 0.5-6m/s.
5. in the present invention, heat exchanger bottom adopts autoclave structure, plays buffering and gas liquid separating function, and has reduced the use of return tank, has reduced thus stringing, has saved space, and increased baffle plate in autoclave structure, has strengthened the effect of gas-liquid separation.
Accompanying drawing explanation
Fig. 1 is the structural representation of traditional vertical tube-sheet heat exchanger.
Fig. 2 is the structural representation of heat exchanger of the present invention.
Fig. 3 is the top structure schematic diagram of heat exchanger tube in heat exchanger of the present invention.
1, process stream import; 2, liquid phase material outlet; 3, flushing liquor entrance; 4, polymerization inhibitor adds entrance;
5, public work material inlet; 6, public work material outlet; 7, shower nozzle; 8, gaseous phase materials outlet;
9, baffle plate; 10, zigzag structure; 11, process stream outlet.
The specific embodiment
In traditional vertical fixed tube-sheet exchanger as shown in Figure 1, process stream from process stream import 1 enter, process stream outlet 11 goes out.Heat exchanger bottom increases return tank uses, and process stream enters return tank after heat exchanger process stream outlet 11 is discharged, and after gas-liquid separation, liquid phase material goes out from liquid phase material outlet 2; Gaseous phase materials goes out from gaseous phase materials outlet 8; Public work material from public work material inlet 5 enter, public work material outlet 6 goes out.
Because the less turbulence in pipe of material in traditional heat exchangers is low, in heat exchanger tube, be easy to cause the bonding of hydrogen cyanide polymer, affect heat-transfer effect, even cause heat exchanger tube to stop up.
Acetonitrile of the present invention is as shown in Figure 2 and Figure 3 purified and is comprised upper tube box, cylindrical shell and lower tube box with anti-blocking heat exchanger; Upper tube box, cylindrical shell and lower tube box form vertical fixed tube sheet type structure, and the top of the heat exchanger tube in described cylindrical shell adopts zigzag structure 10;
Described upper tube box is built-in with shower nozzle 7, and bobbin carriage is provided with process stream import 1 (being located at the top of upper tube box) and flushing liquor entrance 3 (being located at the sidewall of upper tube box), described flushing liquor entrance 3 adds entrance 4 with polymerization inhibitor and is communicated with, the entrance of described flushing liquor is communicated with described shower nozzle 7, and flushing liquor is sprayed in the heat exchanger tube of heat exchanger by described shower nozzle 7;
Described shower nozzle 7 can select solid-cone type shower nozzle etc. can form any shower nozzle pattern of solid circles spraying, and the minimum range of shower nozzle and tube sheet is 0.1D, and D is heat exchanger nominal diameter (mm).
Described cylindrical shell is provided with public work material inlet 5 (being located at the lower end of cylindrical shell) and public work material outlet 6 (being located at the upper end of cylindrical shell);
Described lower tube box adopts in autoclave structure and bobbin carriage and is provided with baffle plate 9.Described lower tube box is provided with liquid phase material outlet 2 (being located at the bottom of lower tube box) and gaseous phase materials outlet 8 (being located at the sidewall of lower tube box); Described liquid phase material outlet 2 is communicated with flushing liquor entrance 3.
Baffle plate 9 is located at gaseous phase materials and exports 8 places, forms angle with gaseous phase materials outlet 8.
Below in conjunction with specific embodiment, the invention will be further described, but do not limit protection scope of the present invention.
Embodiment 1
At crude acetonitrile, enter in acetonitrile decyanation tower purifying technique, use heat exchanger shown in Fig. 2 of the present invention, Fig. 3.Process stream from process stream import 1 enter, liquid phase material outlet 2 goes out, gaseous phase materials goes out from gaseous phase materials outlet 8; Public work material from public work material inlet 5 enter, public work material outlet 6 goes out.
The nozzle type of heat exchanger described in the present embodiment is as shown in table 1:
Table 1
| Major parameter | Parameter value |
| Nozzle type | Solid tapered shower nozzle |
| Nominal diameter | 600mm |
| Distance between shower nozzle and tube sheet | 300mm |
Process condition is: tube side fluid feeding temperature is 70-80 ℃, outlet temperature is 61-71 ℃, operating pressure is 0.001-0.009MPaG, the condensed liquid phase material (calling overall process material in the following text) of discharging from liquid phase material outlet 2 is separated to one built-in shower nozzle 7 from upper tube box in flushing liquor sprays into heat exchanger tube, flushing liquor flow accounts for 1/5 of overall process inventory, polymerization inhibitor adds entrance 4 from polymerization inhibitor and joins in spray liquid, and heat exchange velocity in pipes is 2.1m/s; Shell side cold in-water temperature is 30-34 ℃, and leaving water temperature is 40-44 ℃, and operating pressure is 0.4MPaG.Described polymerization inhibitor is selected from acetic acid, sulfuric acid or phosphoric acid, and the tower bottoms pH that its addition is assurance acetonitrile decyanation tower is at 3-5.
Described public work material is cooling water.
Continuously operation finds in heat exchanger tube, to only have fragmentary polymer during heat exchanger maintenance after 6 months.
Embodiment 2
At crude acetonitrile, enter in acetonitrile decyanation tower purifying technique, use heat exchanger shown in Fig. 2 of the present invention, Fig. 3.Process stream from process stream import 1 enter, liquid phase material outlet 2 goes out, gaseous phase materials goes out from gaseous phase materials outlet 8; Public work material from public work material inlet 5 enter, public work material outlet 6 goes out.
Heat exchanger described in the present embodiment, nozzle type is as shown in table 2:
Table 2
| Major parameter | Parameter value |
| Nozzle type | Solid tapered shower nozzle |
| Nominal diameter | 500mm |
| Distance between shower nozzle and tube sheet | 200mm |
Process condition is: tube side fluid feeding temperature is 70-80 ℃, outlet temperature is 61-71 ℃, operating pressure is 0.001-0.009MPaG, the condensed liquid phase material (calling overall process material in the following text) of discharging from liquid phase material outlet 2 is separated to one built-in shower nozzle 7 from upper tube box in flushing liquor sprays into heat exchanger tube, flushing liquor flow accounts for 1/2 of overall process inventory, polymerization inhibitor adds entrance 4 from polymerization inhibitor and joins in spray liquid, and heat exchange velocity in pipes is 4.2m/s; Shell side cold in-water temperature is 30-34 ℃, and leaving water temperature is 40-44 ℃, and operating pressure is 0.4MPaG.Described polymerization inhibitor is selected from acetic acid, sulfuric acid or phosphoric acid, and the tower bottoms pH that its addition is assurance acetonitrile decyanation tower is at 3-5.
Described public work material is cooling water.
Continuously operation finds in heat exchanger tube, to only have fragmentary polymer during heat exchanger maintenance after 6 months.
Embodiment 3
At crude acetonitrile, enter in acetonitrile decyanation tower purifying technique, use heat exchanger shown in Fig. 2 of the present invention, Fig. 3.Process stream from process stream import 1 enter, liquid phase material outlet 2 goes out, gaseous phase materials goes out from gaseous phase materials outlet 8; Public work material from public work material inlet 5 enter, public work material outlet 6 goes out.
Heat exchanger described in the present embodiment, nozzle type is as shown in table 3:
Table 3
| Major parameter | Parameter value |
| Nozzle type | Solid tapered shower nozzle |
| Nominal diameter | 450mm |
| Distance between shower nozzle and tube sheet | 100mm |
Process condition is: tube side fluid feeding temperature is 70-80 ℃, outlet temperature is 61-71 ℃, operating pressure is 0.001-0.009MPaG, the condensed liquid phase material (calling overall process material in the following text) of discharging from liquid phase material outlet 2 is separated to one built-in shower nozzle 7 from upper tube box in flushing liquor sprays into heat exchanger tube, flushing liquor flow accounts for 2/3 of overall process inventory, polymerization inhibitor adds entrance 4 from polymerization inhibitor and joins in spray liquid, and heat exchange velocity in pipes is 5.8m/s; Shell side cold in-water temperature is 30-34 ℃, and leaving water temperature is 40-44 ℃, and operating pressure is 0.4MPaG.
Described polymerization inhibitor is selected from acetic acid, sulfuric acid or phosphoric acid, and the tower bottoms pH that its addition is assurance acetonitrile decyanation tower is at 3-5.
Described public work material is cooling water.
Continuously operation finds in heat exchanger tube, to only have fragmentary polymer during heat exchanger maintenance after 6 months.
Above preferred embodiment of the present invention is had been described in detail, but described content is only preferred embodiment of the present invention, can not be considered to for limiting practical range of the present invention.All equalization variations of doing according to the present patent application scope and improvement etc., within all should still belonging to patent covering scope of the present invention.
Claims (4)
1. acetonitrile is purified with an anti-blocking method for heat exchanger, it is characterized in that: described heat exchanger adopts vertical fixed tube sheet type structure, and the upper tube box of heat exchanger is built-in with shower nozzle; A part of process stream cooling after heat exchanger heat exchange is back to heat exchanger entrance as flushing liquor, and described flushing liquor sprays in heat exchanger tube by shower nozzle after heat exchanger entrance place is mixed with polymerization inhibitor; The lower tube box of heat exchanger adopts autoclave structure; The flow that returns to the flushing liquor of heat exchanger entrance accounts for the 1/6-2/3 of process stream total flow cooling after heat exchanger heat exchange; The top of described heat exchanger tube adopts zigzag structure; In the lower tube box of described heat exchanger, be also provided with baffle plate; Process stream is walked tube side, and public work material is walked shell side; Process stream is 0.5-6m/s at heat exchange velocity in pipes.
2. for a heat exchanger for method described in claim 1, comprise upper tube box, cylindrical shell and lower tube box, it is characterized in that: upper tube box, cylindrical shell and lower tube box form vertical fixed tube sheet type structure, the top of the heat exchanger tube in described cylindrical shell adopts zigzag structure;
Described upper tube box is built-in with shower nozzle and bobbin carriage is provided with process stream entrance and flushing liquor entrance, and described flushing liquor entrance adds entrance with polymerization inhibitor and is communicated with, and described flushing liquor entrance is communicated with described shower nozzle;
Described cylindrical shell is provided with public work material inlet and public work material outlet;
Described lower tube box adopts autoclave structure, and described lower tube box is provided with liquid phase material outlet and gaseous phase materials outlet; Described liquid phase material outlet is communicated with flushing liquor entrance.
3. heat exchanger according to claim 2, is characterized in that: in described lower tube box, be provided with baffle plate.
4. the application of the heat exchanger described in claim 2 or 3 in the heat exchanger block system producing because of material polymerization.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210236366.XA CN102721320B (en) | 2012-07-10 | 2012-07-10 | Anti-clogging method for heat exchanger and anti-clogging heat exchanger for acetonitrile purification |
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|---|---|---|---|
| CN201210236366.XA CN102721320B (en) | 2012-07-10 | 2012-07-10 | Anti-clogging method for heat exchanger and anti-clogging heat exchanger for acetonitrile purification |
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| CA2036494C (en) * | 1990-05-11 | 1995-06-27 | Tai W. Kwok | Heat exchanger in an hf alkylation process |
| CN100334052C (en) * | 2005-01-20 | 2007-08-29 | 中国寰球工程公司 | System for preparing ethylene glycol from ethane via epoxyethane |
| CN100453948C (en) * | 2007-07-20 | 2009-01-21 | 中国石化扬子石油化工有限公司 | Vertical shell-and-tube heat exchanger and its block-proof method |
| JP5364884B2 (en) * | 2008-02-25 | 2013-12-11 | 三菱レイヨン株式会社 | Method for producing (meth) acrylonitrile |
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