CN115400449B - Method for dehydrating alcohol-containing water-containing steam of polyester reaction kettle by utilizing dehydration tower - Google Patents
Method for dehydrating alcohol-containing water-containing steam of polyester reaction kettle by utilizing dehydration tower Download PDFInfo
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- CN115400449B CN115400449B CN202210887212.0A CN202210887212A CN115400449B CN 115400449 B CN115400449 B CN 115400449B CN 202210887212 A CN202210887212 A CN 202210887212A CN 115400449 B CN115400449 B CN 115400449B
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 167
- 230000018044 dehydration Effects 0.000 title claims abstract description 126
- 238000006297 dehydration reaction Methods 0.000 title claims abstract description 126
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 83
- 229920000728 polyester Polymers 0.000 title claims abstract description 57
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000009833 condensation Methods 0.000 claims abstract description 66
- 230000005494 condensation Effects 0.000 claims abstract description 66
- 230000000630 rising effect Effects 0.000 claims abstract description 66
- 238000011049 filling Methods 0.000 claims abstract description 19
- 208000005156 Dehydration Diseases 0.000 claims description 122
- 238000012856 packing Methods 0.000 claims description 26
- LYCAIKOWRPUZTN-UHFFFAOYSA-N ethylene glycol Natural products OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 19
- 230000001105 regulatory effect Effects 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 16
- 238000009835 boiling Methods 0.000 claims description 9
- 238000010793 Steam injection (oil industry) Methods 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 5
- 125000003827 glycol group Chemical group 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 3
- 230000008018 melting Effects 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims 1
- 230000000903 blocking effect Effects 0.000 abstract description 9
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 238000011144 upstream manufacturing Methods 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 17
- 239000002699 waste material Substances 0.000 description 12
- 239000002994 raw material Substances 0.000 description 9
- 239000000945 filler Substances 0.000 description 7
- 238000010992 reflux Methods 0.000 description 7
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 6
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- SLCVBVWXLSEKPL-UHFFFAOYSA-N neopentyl glycol Chemical compound OCC(C)(C)CO SLCVBVWXLSEKPL-UHFFFAOYSA-N 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 239000000498 cooling water Substances 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 235000011037 adipic acid Nutrition 0.000 description 3
- 239000001361 adipic acid Substances 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- SVTBMSDMJJWYQN-UHFFFAOYSA-N 2-methylpentane-2,4-diol Chemical compound CC(O)CC(C)(C)O SVTBMSDMJJWYQN-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 2
- 238000011143 downstream manufacturing Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 125000003158 alcohol group Chemical group 0.000 description 1
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 229940051250 hexylene glycol Drugs 0.000 description 1
- -1 neopentyl glycol) Chemical compound 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 239000012852 risk material Substances 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
The invention provides a method for dehydrating alcohol-containing water-containing steam of a polyester reaction kettle by utilizing a dehydration tower, and the dehydration tower is used for dehydrating the alcohol-containing water-containing steam, thereby being beneficial to reducing the risk of blocking downstream pipelines/equipment. The dehydration tower comprises a tower body, wherein the inner cavity of the tower body sequentially comprises a tower kettle, a filling area and a steam rising channel positioned above the filling area from bottom to top; a condensation space is formed between the outer wall of the steam rising channel and the inner wall of the tower body, a condensation pipe is arranged in the condensation space, a condensation water accommodating groove for accommodating condensation water obtained by condensation of the condensation pipe is formed at the bottom of the condensation space, and a condensation water backflow pipeline capable of enabling the condensation water in the condensation water accommodating groove to flow back to the filling area is connected to the condensation water accommodating groove; the bottom of the steam rising channel is open, the top of the steam rising channel is closed, and a plurality of steam jet ports corresponding to the position of the condensing tube are arranged on the side wall of the steam rising channel.
Description
Technical Field
The invention relates to the field of polyester dehydration, in particular to a dehydration tower for dehydrating alcohol-containing water-containing steam and a method for dehydrating the alcohol-containing water-containing steam of a polyester reaction kettle by using the dehydration tower.
Background
The polyester production field is generally to utilize dihydric alcohol and dicarboxylic acid to carry out dehydration polycondensation reaction under the action of a catalyst, and prepare a low-water-content polyester product through the operation process of dehydration dealcoholization. The existing polyester production technology generally has the problems of long batch operation period, large alcohol loss and the like, wherein the ratio of the dehydration time to the total operation time is 20% -60%, a certain amount of alcohol can be entrained in the dehydration process to enter the downstream, the problem of blockage of downstream pipeline equipment is caused, and a large amount of waste alcohol is generated. Therefore, there is a need to retrofit existing dewatering techniques in polyester processes.
Disclosure of Invention
In view of this, the present invention provides a dehydration column for dehydration of alcohol-containing aqueous vapor, and a method for dehydration of alcohol-containing aqueous vapor of a polyester reaction tank using the same. The dehydration tower is used for carrying out the dehydration treatment of the alcohol-containing water-containing steam of the polyester reaction kettle, thereby being beneficial to reducing the blockage risk of downstream pipelines/equipment, reducing the scaling phenomenon of a condensing pipe in the dehydration process, reducing the waste of raw materials and lowering the operation cost.
The invention provides the following technical scheme for achieving the purpose:
the invention provides a dehydration tower for dehydrating alcohol-containing water-containing steam, which comprises a tower body, wherein the bottom of the tower body is provided with a feeding and discharging port, the top of the tower body is provided with an air outlet, and the inner cavity of the tower body sequentially comprises a tower kettle, a filling area and a steam rising channel positioned above the filling area from bottom to top;
the material inlet and outlet is connected with a material inlet and outlet pipe, and the material inlet and outlet pipe is used for introducing the alcohol-containing water vapor into the tower kettle and outputting the liquid alcohol separated from the dehydration tower from the tower kettle; the air outlet is connected with an air outlet pipe;
a condensation space is formed between the outer wall of the steam rising channel and the inner wall of the tower body, a condensation pipe is arranged in the condensation space, a condensation water accommodating groove for accommodating condensation water obtained by condensation of the condensation pipe is formed at the bottom of the condensation space, a condensation water backflow pipeline capable of enabling the condensation water in the condensation water accommodating groove to flow back to the filling area is connected to the condensation water accommodating groove, and a water outlet pipe for outputting the condensation water in the condensation water accommodating groove to the outside of the tower body is also connected to the condensation water accommodating groove; the condensing space is communicated with an air outlet at the top of the tower body;
the bottom of the steam rising channel is open and is used for receiving steam from the lower part of the steam rising channel, the top of the steam rising channel is closed, and a plurality of steam jet ports corresponding to the position of the condensing pipe are formed in the side wall of the steam rising channel.
In some embodiments, the side wall of the steam rising channel is provided with a plurality of layers of steam jet ports from bottom to top, and the extension lines of the central lines of at least part of adjacent steam jet ports are intersected on the condensation pipe in the plurality of steam jet ports on the same layer;
preferably, in the plurality of steam injection ports located at the same layer, extension lines of center lines of two adjacent steam injection ports of every three adjacent steam injection ports intersect on the condenser pipe.
In some embodiments, in a cross section of the steam-rising channel perpendicular to an axial direction of the steam-rising channel, an angle between a radial direction of the steam-rising channel passing through a center of an inlet side of the steam-jet port and a center line of the steam-jet port is greater than 0 ° and equal to or less than 45 °.
In some embodiments, the air outlet pipe is connected with a vacuumizing device, and regulating valves are respectively arranged on the air outlet pipe, the air outlet pipe and the feeding and discharging pipe.
In some embodiments, a liquid distributor is disposed between the vapor riser and the packing region, and the condensate return conduit extends above the liquid distributor.
In some embodiments, the lower part of the dehydration tower is provided with a steam external coil pipe with a heating function.
The invention also provides a method for dehydrating alcohol-containing water-containing steam of a polyester reaction kettle by using the dehydration tower, which comprises the following steps:
introducing alcohol-containing water vapor output from an alcohol-containing water vapor outlet of the polyester reaction kettle into the dehydration tower through the material inlet and outlet pipe for dehydration treatment;
in the dehydration treatment process, the steam rising channel receives the steam rising from the filling area, the steam entering the steam rising channel is sprayed onto a condensing pipe in the condensing space through a steam jet opening formed in the side wall of the steam rising channel, condensed water is obtained by condensation under the action of the condensing pipe, and the condensed water is deposited in a condensed water accommodating groove and flows back to the filling area through a condensed water backflow pipeline;
when the steam temperature at the top of the steam rising channel reaches a preset temperature and is maintained for at least 10 minutes, a regulating valve on the water outlet pipe is opened to output part of condensed water to the outside of the tower body; wherein the preset temperature refers to a temperature at which the steam temperature is lower than a boiling point of water corresponding to an operating pressure of the dehydration tower in a range of 0 ℃ to 2 ℃;
and the liquid alcohol obtained after the dehydration treatment is refluxed to the polyester reaction kettle through the material inlet and outlet pipe.
In some embodiments, after the steam temperature at the top of the steam rising channel reaches the preset temperature and is maintained for 10-60 minutes, the regulating valve on the water outlet pipe is opened.
In some embodiments, when the adjusting valve on the water outlet pipe is opened to output part of the condensed water to the outside of the tower body, the condensed water can continuously flow back to the packing area in the condensed water accommodating tank.
In some embodiments, the alcohol in the alcohol-containing aqueous vapor is a glycol having a boiling point above 120 ℃ and a melting point within 200 ℃ at atmospheric pressure; the operation pressure of the dehydration tower is 2kPaA to normal pressure.
The technical scheme provided by the invention has the following beneficial effects:
the dehydration tower is used for carrying out dehydration treatment on alcohol-containing water-containing steam from a polyester reaction kettle, so that on one hand, the dehydration effect can be improved, the dehydration efficiency can be improved, and the waste of raw materials (alcohol) can be reduced; on the other hand, the phenomenon of blocking and scaling in the dehydration tower can be reduced, and the phenomenon of blocking of a downstream pipeline/device can be reduced. The method is based on the dehydration tower for dehydration treatment of alcohol-containing water vapor in the polyester reaction kettle, can extract condensed water at a relatively low temperature, and does not need an additional secondary condensing device; meanwhile, better dealcoholization effect can be obtained in a relatively short operation time, the utilization rate of raw materials is improved, and the risk of blocking of downstream pipelines/devices is reduced.
Drawings
FIG. 1 is a schematic diagram of a dehydration column in one embodiment;
FIG. 2 is a schematic view of an opening direction of a vapor injection port in one embodiment.
Fig. 3 is a schematic view of the dehydration column used in the comparative example.
Detailed Description
In order that the invention may be readily understood, a further description of the invention will be provided with reference to the following examples. It should be understood that the following examples are only for better understanding of the present invention and are not meant to limit the present invention to the following examples.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The term "and/or" as may be used herein includes any and all combinations of one or more of the associated listed items. Where specific experimental steps or conditions are not noted in the examples or comparative examples, they may be performed according to the operations or conditions of the corresponding conventional experimental steps in the art.
Terms of orientation such as up, down, left, right, front, rear, front, back, top, bottom, etc. mentioned or possible to be mentioned in the present specification are defined with respect to the configurations shown in the drawings, which are relative concepts, and thus may be changed according to different positions and different use states thereof. The words "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.
The invention provides a dehydration tower for dehydration of alcohol-containing water-containing steam. Referring to fig. 1, the dehydration column includes a column body 100. The bottom of the tower body is provided with a feeding and discharging port for feeding upstream alcohol-containing water-containing steam, and simultaneously outputting the water-removed liquid alcohol material obtained in the dehydration tower to an upstream device (such as a polyester reaction kettle). The top of the tower body is provided with an air outlet for discharging noncondensable gas and connecting with a vacuumizing device. The inner cavity of the tower body mainly comprises a tower kettle 13, a filling area 5 and a steam rising channel 2 positioned above the filling area 5 from bottom to top.
A material inlet and outlet port of the tower body is connected with a material inlet and outlet pipe 14, the upstream alcohol-containing water-containing steam is introduced into the tower kettle 13 through the material inlet and outlet pipe 14, and the liquid alcohol separated in the dehydration tower is simultaneously output from the tower kettle 13 to the outside, for example, to the upstream polyester reaction kettle; the material inlet and outlet pipe 14 is provided with a regulating valve 15. An air outlet pipe 10 is connected to the air outlet of the tower body, the air outlet pipe 10 is connected to a vacuumizing device (not shown in the figure), and an adjusting valve 12 is arranged on the air outlet pipe 10 and used for adjusting the operation pressure of the dehydration tower.
In the tower, a condensation space 7 is formed between the outer wall of the steam rising channel 2 and the inner wall of the tower 100. The condensation space 7 is internally provided with a condensation pipe 1, the condensation pipe 1 plays a role in condensation, the specific structure of the condensation pipe 1 can adopt a condensation structure which is conventional in the art, a conventional refrigerant can be used as a condensation medium, for example, circulating cooling water is adopted, and the circulating cooling water is introduced into the condensation pipe 1 through a circulating cooling water pipeline 16 in fig. 1. The bottom of the condensation space 7 is formed with a condensate water accommodating groove 3 for accommodating condensate water condensed by the condensation pipe 1, and specifically, the bottom of the condensation space 7 may be closed by connecting between the channel wall of the lower portion of the steam rising channel 2 and the inner wall of the tower body 100, forming the condensate water accommodating groove 3. A condensed water outlet is formed in the condensed water accommodating groove 3, and a condensed water return pipeline 8 is connected to the condensed water outlet; the condensed water in the condensed water accommodating tank 3 is refluxed to the filler region 5 through the condensed water reflux pipe 8. Further, a water outlet is further formed in the condensate water accommodating groove 3, a water outlet pipe 9 is connected to the water outlet, a regulating valve 11 is also arranged on the water outlet pipe 9, and condensate water in the condensate water accommodating groove 3 is output to the outside of the tower body through the water outlet pipe 9. The condensation space 7 is communicated with the air outlet at the top of the tower body 100, so that noncondensable gas which cannot be condensed in the condensation space 7 can be discharged out of the dehydration tower, and the operation pressure of the dehydration tower can be adjusted through a vacuumizing device communicated with the air outlet.
The bottom of the steam rising channel 2 in the tower body 100 is open, so that the inner cavity of the steam rising channel 2 is communicated with the space below the steam rising channel 2, the steam rising channel 2 is used for receiving steam from the space below the steam rising channel 2, the top of the steam rising channel 2 is closed, the side wall of the steam rising channel 2 is provided with a plurality of steam jet ports 22 corresponding to the position of the condensing pipe 1, and therefore steam cannot escape from the top and can only be jetted into the condensing space 7 from the steam jet ports 22 to be condensed by the condensing pipe 1.
In the dehydration tower provided by the invention, alcohol-containing water-containing steam sequentially passes through a tower kettle 13 and a packing region 5 in the ascending process of the tower body to carry out alcohol-water separation, steam escaping from the packing region enters a steam ascending channel 2, is sprayed onto a condensation pipe 1 through a steam spray hole 22 to carry out heat exchange and is fully cooled, and then enters a condensed water accommodating groove 3, condensed water partially flows back to the packing region 5 below to promote the alcohol-water mass transfer separation of the packing region 5, finally alcohol flows down to the tower kettle 13 and finally returns to an upstream polyester reaction kettle through a pipeline 14, and water is extracted in the dehydration tower. The dehydration tower is used for carrying out dehydration treatment on alcohol-containing water-containing steam from the polyester reaction kettle, so that on one hand, the dehydration effect can be improved, the dehydration efficiency can be improved, the possibility that alcohol is steamed out can be reduced, and the waste of raw materials can be reduced; on the other hand, the phenomenon of blocking and scaling in the dehydration tower can be reduced, the alcohol content in the effluent is reduced, and the phenomenon of blocking of a downstream pipeline/device is reduced.
Referring to fig. 1 and 2, in the preferred embodiment, the side wall of the steam rising channel 2 is provided with a plurality of layers of steam injection ports 22 from bottom to top. Referring to fig. 2, among the plurality of vapor injection ports 22 located at the same layer, extension lines of the center lines of at least part of the adjacent vapor injection ports 22 intersect on the condenser tube 1. Preferably, among the plurality of vapor injection ports 22 located at the same layer, extension lines of the center lines of two adjacent vapor injection ports of every three adjacent vapor injection ports 22 intersect on the condenser tube 1. By adopting the steam jet orifice with the preferable structure, the condensing tube 1 can be double-flushed by high-speed steam while condensing steam, so that the risk of scaling on the outer wall of the condensing tube is further reduced. Further preferably, see fig. 2, which is a partial cross-sectional view of the steam-rising channel in a plane perpendicular to the axial direction of the steam-rising channel; in the figure, O is the center of the section of the steam rising channel, and an included angle alpha between the radial direction L of the steam rising channel passing through the center of the inlet side of the steam jet orifice and the central line c of the steam jet orifice is more than 0 DEG and less than or equal to 45 DEG, wherein the inlet side of the steam jet orifice is positioned on the inner cavity side of the steam rising channel, and the center of the inlet side is the middle point of the connecting line of the two end points a and b of the inlet side of the steam jet orifice in the figure 2; the adoption of the preferred opening angle of the steam jet orifice can enable steam jetted from the steam jet orifice to generate better scouring effect on the outer wall of the condensing tube, avoid scaling on the outer wall of the condensing tube and simultaneously achieve good steam condensing effect.
In a preferred embodiment, a liquid distributor 4 is arranged between the steam rising channel 2 and the packing region 5, and a condensate return pipe 8 extends above the liquid distributor 4.
In some embodiments, the lower part of the dehydration tower is provided with a steam outer coil 6 with a heating function, but the steam outer coil is not necessarily provided; when the feed alcohol used in the upstream polyester reactor contains some readily coagulated feed alcohol (e.g., neopentyl glycol), the steam external coil may be used to assist in heating as desired.
The invention also provides a method for dehydrating alcohol-containing water vapor of the polyester reaction kettle by using the dehydration tower, and the related description of the dehydration tower is referred to in the previous text and is not repeated one by one. The dehydration method mainly comprises the following steps:
introducing alcohol-containing water vapor output from an alcohol-containing water vapor outlet of the polyester reaction kettle into a dehydration tower through a feed and discharge pipe 14 for dehydration treatment; the alcohol-containing water-containing steam entering the dehydration tower sequentially flows through the tower kettle 13 and the packing area 5, and the steam escaping from the packing area 5 enters the steam rising channel 2;
in the dehydration treatment process, the steam rising channel 2 receives the steam rising from the filling area 5, the steam entering the steam rising channel 2 is sprayed onto the condensation pipe 1 in the condensation space 7 through the steam jet orifice 22 arranged on the side wall of the steam rising channel 2, and condensed water is obtained by condensation under the action of the condensation pipe 1, deposited in the condensed water accommodating groove 3 and reflowed to the filling area 5 through the condensed water reflow pipeline 8;
when the steam temperature at the top of the steam rising channel 2 reaches the preset temperature and is maintained for at least 10 minutes, a regulating valve 11 on a water outlet pipe 9 is opened to output part of condensed water to the outside of the tower body; wherein the preset temperature is a temperature in a range of 0 ℃ to 2 ℃ below the steam temperature which is lower than the boiling point of water corresponding to the operation pressure of the dehydration tower; the steam temperature in relation to the top of the steam rising channel 2 can be monitored by providing a temperature sensing element;
the liquid alcohol obtained after dehydration is returned to the upstream polyester reaction kettle through the material inlet and outlet pipe 14 to continuously participate in the reaction.
According to the dehydration tower disclosed by the invention, the dehydration treatment of the alcohol-containing water vapor in the polyester reaction kettle is performed according to the method, so that the water in the polyester reaction kettle can be efficiently removed, the operation time and the raw material loss are reduced, and the high-quality polyester product can be prepared.
In the preferred embodiment, when the steam temperature at the top of the steam rising channel 2 reaches the preset temperature and is maintained for 10-60 minutes, the regulating valve 11 on the water outlet pipe 9 is opened. I.e. at the beginning of the dewatering process, the regulating valve 11 on the outlet pipe 9 is closed. In the dehydration treatment process, condensed water circulates in the tower in a reflux way, so that efficient mass transfer separation of alcohol and water in a packing area is promoted, the alcohol finally descends to a tower kettle 13 and finally returns to an upstream polyester reaction kettle, and the water is extracted up and down.
It is further preferred that when the regulating valve 11 on the water outlet pipe 9 is opened to output part of the condensed water to the outside of the tower body, the condensed water can be continuously returned to the packing area in the condensed water accommodating tank, that is, it is ensured that the condensed water is continuously returned to the packing area. Specifically, the condensed water accommodating groove 3 is specifically provided with a condensed water reflux port, and the condensed water reflux pipeline 8 is connected with the condensed water reflux port; the condensed water containing groove 3 is provided with a condensed water outlet which is connected with a water outlet pipe 9; preferably, the opening position of the condensate water reflux port is lower than the opening position of the condensate water outlet.
The alcohol in the alcohol-containing aqueous vapor is derived from a starting alcohol in an upstream polyester reactor that does not participate in the reaction, and in some embodiments the alcohol in the alcohol-containing aqueous vapor is a glycol having a boiling point at normal pressure of 120 ℃ or greater and a melting point within 200 ℃, such glycol being conventionally used in the art to perform polyester synthesis reactions, such as, but not limited to, ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, hexylene glycol, and the like. In some embodiments, the operating pressure of the dehydration column is 2kPaA to normal pressure, and the operating pressure in the dehydration column may be further reduced within this range to further improve the dehydration efficiency.
According to the invention, the dehydration treatment of rising steam containing alcohol and water generated in the polyester reaction kettle is performed based on the dehydration tower, condensed water circulates in the tower in the dehydration tower, so that efficient mass transfer separation of alcohol and water in a filler area is promoted, the alcohol finally descends to the tower kettle and finally returns to the polyester reaction kettle at the upstream, and the water is extracted in the dehydration tower at the upstream.
In some embodiments, the packing zone 5 of the dehydration column has a theoretical plate number of 2 to 6. The packing in the dehydration column is not particularly limited, and a dehydration column packing conventionally used in the art, such as a random packing θ ring, a structured packing CY, BX, and the like, may be employed.
In the dehydration method of the present invention, alcohol water vapor (for example, glycol+water) from a polyester reaction vessel is introduced into a dehydration column from the bottom of the dehydration column. At the beginning, a regulating valve on a water outlet pipe 9 in the condensate water accommodating groove is closed, rising steam in the dehydration tower is ejected at a high speed through a steam jet hole 22, and fully cooled on a condensation pipe 1 (for example, a multi-layer inner coil pipe) and then enters the condensate water accommodating groove 3; the condensed water in the condensed water containing tank 3 flows out through the condensed water return pipeline 8 and continues to flow downwards after passing through the liquid distributor 4, the condensed water and rising steam carry out sufficient vapor-liquid mass transfer in the packing area 5 below the liquid distributor 4, after a period of time (particularly after the steam temperature at the top of the steam rising channel 2 reaches the preset temperature and is maintained for at least 10 minutes, particularly for 10-60 minutes), stable concentration distribution is formed in the packing area 5, the upper layer of the packing area 5 is water, and the lower layer is alcohol+a small amount of water; at this time, the steam temperature at the top of the steam rising channel 2 is within 2 ℃ or less than the boiling point of water under the operating pressure, and at this time, the regulating valve 11 of the water outlet pipe 9 is opened again to start water collection. The water circulates in the tower, so that the efficient mass transfer separation of the alcohol and the water in the filler area is promoted, the alcohol finally descends to the tower kettle and finally returns to the polyester reaction kettle at the upstream, and the water is extracted in the light component removing tower, so that the purpose of efficient dehydration is realized.
The invention promotes the high-efficiency separation of alcohol and water by injecting steam into the condensation space 7 and refluxing condensed water into the tower to establish the internal circulation of water. Compared with the traditional polyester reaction kettle dehydration device, the scheme of the invention has the following advantages:
(1) Compared with the prior art, the invention can save the corresponding secondary condenser and reduce the operation cost and the process flow compared with the prior art which needs to add the secondary condenser for water cooling.
(2) Compared with the prior art, the invention can greatly shorten the batch operation time and improve the production efficiency of polyester.
(3) According to the dehydration scheme provided by the invention, the produced water hardly entrains alcohol, so that the blocking risk of downstream process pipeline equipment can be reduced, the waste alcohol emission is reduced, and the raw material utilization rate of an upstream reaction kettle is improved.
(4) The steam is sprayed to the condensing tube through the steam spray hole, so that the scaling phenomenon of the condensing tube can be reduced; in the preferred scheme, the steam jet hole is subjected to structural optimization, and through double flushing of high-speed steam from the steam jet hole, dihydric alcohol and the like are more difficult to coalesce on the outer wall of the condensing tube, so that the scaling risk of the condensing section can be further reduced.
The dehydration scheme of the invention is adopted to dehydrate the alcohol-containing water-containing steam of the polyester reaction kettle, so that the dehydration target can be reached in a short time to obtain qualified polyester products; meanwhile, the blocking risk and raw material waste of the process pipeline equipment are reduced, and the operation cost is reduced.
The present invention will be further described with reference to examples and comparative examples.
Examples:
the alcohol-containing and water-containing steam outlet of the upstream polyester reaction kettle is communicated with the feed inlet and the discharge outlet of the dehydration tower through a feed and discharge pipeline 14. The structure of the dehydration tower is shown in fig. 1-2, and the description of the dehydration tower is referred to above, and will not be repeated herein.
200g of ethylene glycol, 350g of neopentyl glycol and 900g of adipic acid are added into an upstream polyester reaction kettle, the raw materials are dissolved by heating, and 0.1g of catalyst (tetrabutyl titanate is used as the catalyst) is added; the reaction is carried out by heating to 110 ℃, alcohol-containing water-containing steam enters the dehydration tower in the reaction process, and specific steps of the method for dehydrating the alcohol-containing water-containing steam of the polyester reaction kettle are referred to in the description above and are not repeated one by one. The filler in the dehydration tower is theta-ring filler. The opening angle of the steam jet hole of the steam rising channel is as follows: referring to fig. 2, on a cross section of the steam-rising channel perpendicular to an axial direction of the steam-rising channel, an angle α of a radial direction L of the steam-rising channel passing through a center of an inlet side of the steam-injection port to a center line c of the steam-injection port is 45 °.
The operating pressure in the dehydration column is controlled by a regulating valve 12 on the outlet pipe 10 of the dehydration column, and the pressure set value is 90kPaA. The condensed water on the condensed water containing groove flows back to the filling area 5 through the condensed water backflow pipeline 8; when the steam temperature at the top of the steam rising channel 2 is the boiling point temperature of the corresponding water under the operating pressure of the dehydration tower and is maintained for 10 minutes, the regulating valve 11 on the water outlet pipe 9 is opened, and the condensed water continuously flows back to the filling area in the dehydration tower. In this embodiment, the temperature of the condensed water extracted from the water outlet pipe 9 is less than 60 ℃.
After dehydration is completed (dehydration completion can be judged when the water yield reaches the theoretical dehydration yield), the regulating valve 15 on the feed and discharge pipe 14 is closed. The upstream polyester reaction kettle is connected with a vacuum system (with a cold trap) for dealcoholization operation, and polyester products with performance indexes meeting requirements are obtained in the polyester reaction kettle.
Comparative example 1:
the alcohol-containing and water-containing steam outlet of the upstream polyester reaction kettle is communicated with the inlet and outlet of the dehydration tower 200 through a feed and discharge pipeline 201. Wherein the structure of the dehydration column 200 is shown with reference to fig. 3. The main difference between the dehydration column of fig. 3 and the dehydration column of fig. 1 of the present invention is that: there is no steam rising channel in the upper space of the packing area 203, but a condensing tube 202 is directly arranged above the packing area 203, after the steam rises to the condensing tube 202 from the packing area 203, alcohol is condensed down to enter the tower kettle, and the steam is discharged from the top outlet of the tower body to a downstream secondary condensing tube 204 through a pipeline 205 to be further condensed to obtain condensed water. The filler used in the filler zone was the same as in example 1.
200g of ethylene glycol, 350g of neopentyl glycol and 900g of adipic acid were charged into an upstream polyester reactor, and a reaction was carried out in the same manner as in example 1, and the resultant alcohol-containing aqueous vapor was introduced into a dehydration column in FIG. 3, followed by a secondary condenser 204. In the dehydration process, rising steam sequentially passes through a packing region 203 and a condensing pipe 202 from bottom to top in a dehydration tower 200, the water quantity of circulating cooling water of the condensing pipe 202 is regulated to control the tower top temperature to be 1-5 ℃ higher than the boiling point of water under the operating pressure of the light component removal tower, and gas phase extraction is carried out; the temperature of the extracted gas phase is high (the temperature is 97-98 ℃), so that the gas phase is inconvenient to recycle, and the gas phase needs to be condensed by a secondary condenser 204 to obtain wastewater (the temperature is less than 60 ℃).
The operating pressure in the dehydration column was controlled by a regulator valve on the vent line 205 connected to the top outlet of the dehydration column 200, with a pressure set point of 90kPaA.
After the dehydration is completed, the adjusting valve on the feeding and discharging pipe 201 of the dehydration column is closed. The upstream polyester reaction kettle is connected with a vacuum system (with a cold trap) to carry out dealcoholization operation (waste alcohol is obtained), and polyester products with performance indexes meeting requirements are obtained in the polyester reaction kettle.
Comparative example 2:
this comparative example was performed with reference to comparative example 1, except that: the feeding amount in the upstream polyester reaction kettle is increased: 250g of ethylene glycol, 400g of neopentyl glycol and 900g of adipic acid.
Process analysis and product index testing (as assessed by viscosity and acidity) were performed on example 1, comparative examples 1-2, and the specific results are shown in Table 1.
Table 1 examples and comparative examples analysis test results
Note that: the waste alcohol refers to waste alcohol obtained by vacuumizing and removing alcohol from a polyester reaction kettle after dehydration is finished.
The procedure of example 1, comparative example 1 and comparative example 2 was repeated three times to examine clogging. Results example 1 showed no blockage in all three experiments, and comparative examples 1 and 2 showed blockage of the condenser and/or the pipeline, and the experiment was continued after cleaning, wherein the time taken to clean the blockage in the three experiments for comparative example 1 was 1h and the time taken to clean the blockage in the three experiments for comparative example 2 was 1.5h.
As can be seen from Table 1, the comparative example 1 and example 1 are identical in the amount of the fed polyester reactor, but the obtained product quality and quality are significantly lower than those of example 1 of the present invention, and the amount of the produced waste alcohol is significantly higher than that of example 1; while comparative example 2 obtained a product of quality comparable to that of example 1 of the present invention by increasing the amount of raw material input, the amount of waste alcohol was significantly higher than that of example 1; example 1 has a shorter operation time, higher dehydration efficiency, and the produced condensate water has higher quality, which helps to reduce the risk of clogging of downstream processes, compared to comparative examples 1, 2.
As can be seen from Table 1, the dehydration tower and the dehydration method provided by the invention can obtain qualified polyester products in a shorter time, generate less waste alcohol, have no risk of blocking equipment and downstream pipelines, and are very suitable for the field of polyester production.
It will be readily appreciated that the above embodiments are merely examples given for clarity of illustration and are not meant to limit the invention thereto. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. The dehydration tower for dehydrating alcohol-containing water-containing steam is characterized by comprising a tower body, wherein the bottom of the tower body is provided with a feeding and discharging port, the top of the tower body is provided with an air outlet, and the inner cavity of the tower body sequentially comprises a tower kettle, a filling area and a steam rising channel positioned above the filling area from bottom to top;
the material inlet and outlet is connected with a material inlet and outlet pipe, and the material inlet and outlet pipe is used for introducing the alcohol-containing water-containing steam into the tower kettle and outputting the liquid alcohol separated in the dehydration tower from the tower kettle; the air outlet is connected with an air outlet pipe;
a condensation space is formed between the outer wall of the steam rising channel and the inner wall of the tower body, a condensation pipe is arranged in the condensation space, a condensation water accommodating groove for accommodating condensation water obtained by condensation of the condensation pipe is formed at the bottom of the condensation space, a condensation water backflow pipeline capable of enabling the condensation water in the condensation water accommodating groove to flow back to the filling area is connected to the condensation water accommodating groove, and a water outlet pipe for outputting the condensation water in the condensation water accommodating groove to the outside of the tower body is also connected to the condensation water accommodating groove; the condensing space is communicated with an air outlet at the top of the tower body;
the bottom of the steam rising channel is open and is used for receiving steam from the lower part of the steam rising channel, the top of the steam rising channel is closed, and a plurality of steam jet ports corresponding to the position of the condensing pipe are arranged on the side wall of the steam rising channel;
the side wall of the steam rising channel is provided with a plurality of layers of steam jet ports from bottom to top, and the extension lines of the central lines of at least part of adjacent steam jet ports are intersected on the condensing pipe in the plurality of steam jet ports on the same layer.
2. The dehydration column of claim 1, wherein,
the extension lines of the central lines of two adjacent steam jet ports in every three adjacent steam jet ports in the plurality of steam jet ports positioned on the same layer intersect on the condensing tube.
3. The dehydration tower according to any one of claims 1 to 2, wherein an angle between a radial direction of said steam rising channel passing through a center of an inlet side of said steam injection port and a center line of said steam injection port is greater than 0 ° and equal to or less than 45 ° in a cross section of said steam rising channel perpendicular to an axial direction of said steam rising channel.
4. The dehydration column according to any one of claims 1 to 2, wherein the air outlet pipe is connected with a vacuum pumping device, and regulating valves are respectively provided on the air outlet pipe, the air outlet pipe and the feed and discharge pipe.
5. The dehydration column according to any one of claims 1 to 2, wherein a liquid distributor is provided between the vapor riser and the packing region, and the condensate return conduit extends above the liquid distributor.
6. The dehydration column according to any one of claims 1 to 2, wherein a lower portion of the dehydration column is provided with a steam external coil having a heating function.
7. A method for dehydrating alcohol-containing aqueous vapor of a polyester reactor by using the dehydration column according to any one of claims 1 to 6, comprising the steps of:
introducing alcohol-containing water vapor output from an alcohol-containing water vapor outlet of the polyester reaction kettle into the dehydration tower through the material inlet and outlet pipe for dehydration treatment;
in the dehydration treatment process, the steam rising channel receives the steam rising from the filling area, the steam entering the steam rising channel is sprayed onto a condensing pipe in the condensing space through a steam jet opening formed in the side wall of the steam rising channel, condensed water is obtained by condensation under the action of the condensing pipe, and the condensed water is deposited in a condensed water accommodating groove and flows back to the filling area through a condensed water backflow pipeline;
when the steam temperature at the top of the steam rising channel reaches a preset temperature and is maintained for at least 10 minutes, a regulating valve on the water outlet pipe is opened to output part of condensed water to the outside of the tower body; wherein the preset temperature refers to a temperature at which the steam temperature is lower than a boiling point of water corresponding to an operating pressure of the dehydration tower in a range of 0 ℃ to 2 ℃;
and the liquid alcohol obtained after the dehydration treatment is refluxed to the polyester reaction kettle through the material inlet and outlet pipe.
8. The method of claim 7, wherein the regulating valve on the outlet pipe is opened again after the steam temperature at the top of the steam rising channel reaches the preset temperature and is maintained for 10-60 minutes.
9. The method of claim 7, wherein the condensate holding tank is continuously provided with condensate back-flowing to the packing area when the regulating valve on the water outlet pipe is opened to output a part of condensate to the outside of the tower body.
10. The method of claim 7, wherein the alcohol in the alcohol-containing aqueous vapor is a glycol having a boiling point of 120 ℃ or more and a melting point of 200 ℃ or less at normal pressure; the operation pressure of the dehydration tower is 2kPaA to normal pressure.
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| CH214160A (en) * | 1940-03-29 | 1941-04-15 | Berger Fritz | Still. |
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| CN206444584U (en) * | 2016-11-21 | 2017-08-29 | 肇庆福田化学工业有限公司 | A kind of condensate separation system of suitable polyester synthesis reaction |
| CN210495288U (en) * | 2019-09-05 | 2020-05-12 | 江苏美阳科技有限公司 | Integrated ethylene glycol refining equipment |
| CN111171962A (en) * | 2020-03-20 | 2020-05-19 | 鲁南制药集团股份有限公司 | Novel volatile oil extractor |
| CN211487097U (en) * | 2019-11-06 | 2020-09-15 | 黑龙江建龙化工有限公司 | Debenzolization tower |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH214160A (en) * | 1940-03-29 | 1941-04-15 | Berger Fritz | Still. |
| US3589984A (en) * | 1968-11-21 | 1971-06-29 | Laurance S Reid | Apparatus for dehydrating organic liquids |
| CN2353428Y (en) * | 1998-01-06 | 1999-12-15 | 河北工业大学 | Fully-condensed type distilled water device |
| CN206103386U (en) * | 2016-08-29 | 2017-04-19 | 河北健民淀粉糖业有限公司 | Stills for it is novel |
| CN206444584U (en) * | 2016-11-21 | 2017-08-29 | 肇庆福田化学工业有限公司 | A kind of condensate separation system of suitable polyester synthesis reaction |
| CN210495288U (en) * | 2019-09-05 | 2020-05-12 | 江苏美阳科技有限公司 | Integrated ethylene glycol refining equipment |
| CN211487097U (en) * | 2019-11-06 | 2020-09-15 | 黑龙江建龙化工有限公司 | Debenzolization tower |
| CN111171962A (en) * | 2020-03-20 | 2020-05-19 | 鲁南制药集团股份有限公司 | Novel volatile oil extractor |
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| CN115400449A (en) | 2022-11-29 |
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