CN110394134B - Cooling system - Google Patents
Cooling system Download PDFInfo
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- CN110394134B CN110394134B CN201910794253.3A CN201910794253A CN110394134B CN 110394134 B CN110394134 B CN 110394134B CN 201910794253 A CN201910794253 A CN 201910794253A CN 110394134 B CN110394134 B CN 110394134B
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- rearrangement
- cooling liquid
- cooling
- reaction kettle
- reaction
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- 238000001816 cooling Methods 0.000 title claims abstract description 88
- 239000000110 cooling liquid Substances 0.000 claims abstract description 163
- 230000008707 rearrangement Effects 0.000 claims abstract description 128
- 238000006243 chemical reaction Methods 0.000 claims abstract description 67
- 238000006462 rearrangement reaction Methods 0.000 claims abstract description 66
- 238000006146 oximation reaction Methods 0.000 claims abstract description 44
- 239000012295 chemical reaction liquid Substances 0.000 claims abstract description 20
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 claims description 18
- 239000002826 coolant Substances 0.000 claims description 13
- PVNIIMVLHYAWGP-UHFFFAOYSA-N Niacin Chemical compound OC(=O)C1=CC=CN=C1 PVNIIMVLHYAWGP-UHFFFAOYSA-N 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 12
- 229960003512 nicotinic acid Drugs 0.000 claims description 7
- 239000011664 nicotinic acid Substances 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 235000001968 nicotinic acid Nutrition 0.000 claims description 6
- 238000004891 communication Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 4
- 238000007599 discharging Methods 0.000 abstract description 3
- 230000009467 reduction Effects 0.000 abstract description 3
- VEZUQRBDRNJBJY-UHFFFAOYSA-N cyclohexanone oxime Chemical compound ON=C1CCCCC1 VEZUQRBDRNJBJY-UHFFFAOYSA-N 0.000 description 16
- 239000012809 cooling fluid Substances 0.000 description 4
- 238000006237 Beckmann rearrangement reaction Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920002292 Nylon 6 Polymers 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 150000002923 oximes Chemical class 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001603 reducing effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0006—Controlling or regulating processes
- B01J19/0013—Controlling the temperature of the process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
- B01J2219/00094—Jackets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
- B01J2219/00103—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor in a heat exchanger separate from the reactor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00117—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with two or more reactions in heat exchange with each other, such as an endothermic reaction in heat exchange with an exothermic reaction
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00159—Controlling the temperature controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
Abstract
The invention relates to a cooling system comprising: the oximation reaction kettle is provided with a reaction kettle jacket at the periphery, and the reaction kettle jacket is provided with a first cooling liquid inlet and a first cooling liquid outlet; the rearrangement reaction kettle is provided with a first rearrangement feed port and a first rearrangement discharge port, and the first rearrangement feed port is communicated with the discharge port of the oximation reaction kettle; the first rearrangement discharging port is communicated with the feeding port of the rearrangement heat exchanger, the rearrangement heat exchanger is provided with a second cooling liquid inlet and a second cooling liquid outlet, the second cooling liquid inlet is communicated with the first cooling liquid outlet, so that cooling liquid flows into the rearrangement heat exchanger after being subjected to heat exchange cooling in the jacket of the reaction kettle, and the reaction liquid discharged after the reaction of the rearrangement reaction kettle is subjected to heat exchange cooling. According to the invention, the cooling liquid is sequentially introduced into the oximation reaction and the rearrangement reaction according to the reaction sequence to carry out endothermic cooling, so that the reutilization of the oximation reaction cooling liquid is realized, the utilization rate of the cooling liquid is improved, and the energy saving and consumption reduction effects are improved.
Description
Technical Field
The invention relates to the technical field of chemical energy conservation, in particular to a cooling system.
Background
Cyclohexanone oxime is an intermediate for synthesizing caprolactam, which is an important raw material for preparing nylon 6 and engineering plastics. At present, cyclohexanone oxime is mainly prepared by cyclohexanone TS-1 catalytic ammoximation reaction, the reaction is exothermic, and in the cooling process, reaction heat is taken away by means of cooling liquid and then directly flows back to a water return main pipe; the rearrangement reaction mainly generates Beckmann rearrangement reaction, and a large amount of heat is discharged, and the heat of reaction is carried away in a rearrangement cooler by means of cooling liquid and then directly flows back to a water return main pipe. The cooling systems of the ammoximation reaction and the rearrangement reaction independently operate and do not interfere with each other, so that the waste of cooling liquid is caused.
Disclosure of Invention
In view of the foregoing problems of the prior art, an aspect of the present invention is to provide a cooling system, so as to achieve recycling of cooling liquid and improve energy saving and consumption reduction effects.
In order to achieve the above object, the present invention provides a cooling system for cooling a process for preparing caprolactam, comprising:
the oximation reaction kettle is provided with a reaction kettle jacket at the periphery, and the reaction kettle jacket is provided with a first cooling liquid inlet and a first cooling liquid outlet;
The rearrangement reaction kettle is provided with a first rearrangement feed port and a first rearrangement discharge port, and the first rearrangement feed port is communicated with the discharge port of the oximation reaction kettle;
The rearrangement heat exchanger is provided with a second cooling liquid inlet and a second cooling liquid outlet, and the second cooling liquid inlet is communicated with the first cooling liquid outlet so that cooling liquid flows into the rearrangement heat exchanger after being subjected to heat exchange cooling in the reaction kettle jacket, and the reaction liquid discharged after the rearrangement reaction kettle is subjected to heat exchange cooling.
In some embodiments, the cooling system further comprises a cooling fluid inlet manifold connected to the first cooling fluid inlet and a cooling fluid return manifold connected to the second cooling fluid outlet.
In some embodiments, a coil is arranged in the reaction kettle jacket, an inlet of the coil is communicated with the first cooling liquid inlet, an outlet of the coil is communicated with the first cooling liquid outlet, and the coil is coiled in the reaction kettle jacket and fixedly connected with the reaction kettle jacket through a fixing piece.
In some embodiments, the second cooling liquid inlet is communicated with the first cooling liquid outlet through a first pipeline, and a first control valve is arranged on the first pipeline; and a second control valve is arranged on the cooling liquid return main pipe.
In some embodiments, the first cooling liquid outlet of the reaction kettle jacket is communicated with the cooling liquid return main pipe through a second pipeline, and a third control valve is arranged on the second pipeline.
In some embodiments, the cooling system further comprises a cooling liquid tank, one end of the cooling liquid tank is communicated with the cooling liquid return main pipe, the other end of the cooling liquid tank is communicated with the cooling liquid inlet main pipe, the reaction kettle jacket, the rearrangement heat exchanger and the cooling liquid tank are sequentially communicated along the cooling liquid flow direction to form a cooling circulation loop, and a circulating water pump is further arranged on a connecting pipe between the cooling liquid tank and the cooling liquid inlet main pipe.
In some embodiments, the cooling system further comprises a cooler for cooling the coolant flowing back to the coolant tank, the cooler being disposed within the coolant tank.
In some embodiments, the rearrangement reaction kettle further comprises a second rearrangement feed inlet, the second rearrangement feed inlet is a circulating liquid feed inlet, the feed inlet of the rearrangement heat exchanger is communicated with the first rearrangement discharge outlet of the rearrangement reaction kettle, and the discharge outlet of the rearrangement heat exchanger is communicated with the second rearrangement feed inlet, so that the reaction liquid in the rearrangement reaction kettle flows into the rearrangement heat exchanger to be subjected to heat exchange and cooling, and then is circulated into the rearrangement reaction kettle.
In some embodiments, the cooling system further comprises a rearrangement circulation pump, the rearrangement circulation pump is arranged on a connecting pipeline between the first rearrangement discharge port of the rearrangement reaction kettle and the feed port of the rearrangement heat exchanger, the first rearrangement discharge port is communicated with an inlet end of the rearrangement circulation pump, an outlet end of the rearrangement circulation pump is communicated with the feed port of the rearrangement heat exchanger, and the inlet end of the rearrangement circulation pump is further connected with a nicotinic acid feed liquid pipeline.
In some embodiments, the cooling system further comprises a three-way valve disposed on a line communicating the feed inlet of the rearrangement heat exchanger with the rearrangement circulation pump, an inlet end of the three-way valve being in communication with the outlet end of the rearrangement circulation pump, a first outlet end of the three-way valve being in communication with the feed inlet of the rearrangement heat exchanger, a second outlet end of the three-way valve being in communication with the circulation liquid feed inlet of the rearrangement reaction kettle.
Compared with the prior art, the cooling system provided by the embodiment of the invention has the advantages that after the cooling liquid absorbs the reaction heat of the oximation reaction, the cooling liquid enters the rearrangement heat exchanger to absorb the rearrangement reaction heat, so that the reutilization of the cooling liquid of the oximation reaction is realized, the energy loss can be effectively reduced, the utilization rate of the cooling liquid is improved, and the energy saving and consumption reducing effects are improved.
Drawings
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar components. The accompanying drawings illustrate various embodiments by way of example in general and not by way of limitation, and together with the description and claims serve to explain the inventive embodiments. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Such embodiments are illustrative and not intended to be exhaustive or exclusive of the present apparatus or method.
FIG. 1 is a schematic diagram of a cooling system according to an embodiment of the present invention;
Reference numerals:
101-a cooling liquid inlet main pipe, 102-a cooling liquid return main pipe, 103-a first pipeline and 104-a second pipeline;
1-oximation reaction kettle, 11-reaction kettle jacket, 111-first cooling liquid inlet, 112-first cooling liquid outlet;
2-rearrangement reaction kettle, 21-first rearrangement feed inlet, 22-first rearrangement discharge outlet, 23-second rearrangement feed inlet, 24-second discharge outlet, 201-reaction liquid heat exchange channel and 202-bypass channel;
3-rearrangement heat exchanger, 31-second cooling liquid inlet, 32-second cooling liquid outlet, 33-feeding port, 34-discharging port and 301-nicotinic acid liquid inlet pipeline;
41-first control valve, 42-second control valve, 43-third control valve;
5-a rearrangement circulation pump; 6-a three-way valve;
7-a cooling liquid tank; 8-a circulating cooling pump.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.
Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
In order to keep the following description of the embodiments of the present invention clear and concise, the detailed description of known functions and known components thereof have been omitted.
FIG. 1 is a schematic diagram of a cooling system according to an embodiment of the present invention, wherein the dashed arrows indicate the flow direction of the cooling liquid and the solid arrows indicate the flow direction of the reactants and the products. As shown in fig. 1, an embodiment of the present invention provides a cooling system for cooling a caprolactam preparation process, the cooling system comprising:
the oximation reaction kettle 1 is provided with a reaction kettle jacket 11 at the periphery, and the reaction kettle jacket 11 is provided with a first cooling liquid inlet 111 and a first cooling liquid outlet 112;
A rearrangement reaction kettle 2, which is provided with a first rearrangement feed port 21 and a first rearrangement discharge port 22, wherein the first rearrangement feed port 21 is communicated with the discharge port of the oximation reaction kettle 1;
The rearrangement heat exchanger 3 is arranged at the downstream of the rearrangement reaction kettle 2 and used for cooling the reaction liquid of the rearrangement reaction, the first rearrangement discharge port 22 is communicated with the feed port 33 of the rearrangement heat exchanger 3, the rearrangement heat exchanger 3 is provided with a second cooling liquid inlet 31 and a second cooling liquid outlet 32, the second cooling liquid inlet 31 is communicated with the first cooling liquid outlet 112, so that the cooling liquid flows into the rearrangement heat exchanger 3 after being subjected to heat exchange cooling in the reaction kettle jacket 11, and the reaction liquid discharged after the reaction of the rearrangement reaction kettle 2 is subjected to heat exchange cooling.
According to the cooling system provided by the embodiment of the invention, the cooling liquid is sequentially introduced into the oximation reaction and the rearrangement reaction according to the reaction sequence to absorb the reaction heat for carrying out endothermic cooling, the reaction liquid of the rearrangement reaction is cooled by the cooling liquid with a certain temperature in the oximation reaction, so that the reutilization of the cooling liquid of the oximation reaction is realized, the energy loss can be effectively reduced, the utilization rate of the cooling liquid is improved, and the energy saving and consumption reduction effects are improved.
Further, the cooling system further comprises a cooling liquid inlet main pipe 101 and a cooling liquid return main pipe 102, wherein the cooling liquid inlet main pipe 101 is connected with the first cooling liquid inlet 111 and is used for providing cooling liquid; the cooling liquid return header pipe 102 is connected with the second cooling liquid outlet 32 and is used for recovering cooling liquid after cooling, so that the environment is prevented from being polluted, and meanwhile, energy is saved and consumption is reduced.
Specifically, the oximation reaction kettle 1 is used for performing oximation reaction to synthesize cyclohexanone oxime, and is provided with a feed inlet and a discharge outlet, wherein the feed inlet is an oximation raw material inlet, and the discharge outlet is an oximation product outlet. The reaction kettle jacket 11 is arranged on the periphery of the oximation reaction kettle 1 in a coating mode, the reaction kettle jacket 11 is of a hollow structure and is used for forming a cooling channel, and cooling liquid enters the cooling channel from the first cooling liquid inlet 111 to cool the oximation reaction kettle 1 and then flows out from the first cooling liquid outlet 112.
In some embodiments, as shown in fig. 1, the reaction kettle jacket 11 has a U-shaped structure, the first cooling liquid inlet 111 is disposed at the bottom of the reaction kettle jacket 11, the first cooling liquid outlet 112 is disposed on the side wall of the reaction kettle jacket 11, and the cooling liquid enters the cooling channel from the bottom of the reaction kettle jacket 11 to cool down the oximation reaction kettle 1 and flows out from the side wall of the reaction kettle jacket 11. During the reaction, the temperature of the bottom of the oximation reaction kettle 1 is higher, so that the cooling liquid is introduced into the oximation reaction kettle 1 in a bottom liquid inlet mode, thereby being beneficial to quickly cooling the oximation reaction kettle 1 and improving the cooling efficiency; in addition, the oximation reaction is reversible exothermic reaction, so that the temperature of the oximation reaction is reduced as quickly as possible, the reaction is facilitated to move towards the direction of generating cyclohexanone oxime, and the product rate is improved.
In some embodiments, a coil (not shown in the figure) is disposed in the reactor jacket 11, an inlet of the coil is communicated with the first cooling liquid inlet 111, an outlet of the coil is communicated with the first cooling liquid outlet 112, and the coil is coiled in the reactor jacket 11 and fixedly connected with the reactor jacket 11 through a fixing piece. In some embodiments, the coil is spirally coiled in the reaction kettle jacket 11, so that the flow area of the cooling liquid can be increased, and the heat exchange cooling efficiency and the heat exchange effect can be improved. In addition, the coil pipe is arranged to enable the cooling liquid to flow along the coil pipe in a directional manner, so that the problems of long heat exchange time, low heat exchange efficiency and the like caused by unordered flow of the cooling liquid are solved, and the heat exchange efficiency is further improved.
In some embodiments, the height of the reaction kettle jacket 11 is at least half the height of the oximation reaction kettle 1, so that the cooling of the upper part of the oximation reaction kettle 1 with lower temperature can be reduced, and the cost can be reduced.
In this embodiment, as shown in fig. 1, a first cooling liquid outlet 112 of the reaction kettle jacket 11 is communicated with a second cooling liquid inlet 31 of the rearrangement heat exchanger 3 through a first pipeline 103, and a first control valve 41 for adjusting the flow rate of the cooling liquid is arranged on the first pipeline 103. The coolant return manifold 102 is provided with a second control valve 42, and the second control valve 42 is disposed near the rearrangement heat exchanger 3 for adjusting the flow rate of the coolant flowing out from the second coolant outlet 32.
In some embodiments, as shown in fig. 1, the first cooling liquid outlet 112 of the reactor jacket 11 is communicated with the cooling liquid return manifold 102 through a second pipeline 104, and a third control valve 43 is arranged on the second pipeline 104. When the rearrangement reaction kettle 2 does not participate in the reaction, namely, when the rearrangement heat exchanger 3 does not perform heat exchange cooling, the first cooling liquid outlet 112 of the reaction kettle jacket 11 is communicated with the cooling liquid return main pipe 102 through the second pipeline 104, and after the oximation reaction kettle 1 is cooled by cooling liquid, the cooling liquid directly flows back through the cooling liquid return main pipe 102, so that the flowing path of the cooling liquid is shortened, and the cooling efficiency of a cooling system is improved.
The rearrangement reaction kettle 2 is used for carrying out rearrangement reaction, and as shown in fig. 1, the rearrangement reaction kettle comprises a first rearrangement feed port 21, a first rearrangement discharge port 22, a second rearrangement feed port 23 and a second rearrangement discharge port 24, wherein the first rearrangement feed port 21 is used as a raw material feed port, cyclohexanone oxime generated by oximation reaction enters the rearrangement reaction kettle 2 from the first rearrangement feed port 21, oxime rearrangement is carried out in the rearrangement reaction kettle 2 by reacting with nicotinic acid, so as to obtain rearrangement product caprolactam, and caprolactam overflows from the second rearrangement discharge port 24 arranged at the upper part of the rearrangement reaction kettle 2.
The first rearrangement discharge port 22 is a circulating liquid discharge port, the second rearrangement feed port 23 is a circulating liquid feed port, the first rearrangement discharge port 22 is arranged at the bottom of the rearrangement reaction kettle 2 and is used for discharging reaction liquid in the rearrangement reaction kettle 2, the rearrangement heat exchanger 3 is provided with a feed port 33 and a discharge port 34, the feed port 33 of the rearrangement heat exchanger 3 is communicated with the first rearrangement discharge port 22 of the rearrangement reaction kettle 2, the discharge port 34 of the rearrangement heat exchanger 3 is communicated with the second rearrangement feed port 23 of the rearrangement reaction kettle 2, so that the reaction liquid in the rearrangement reaction kettle 2 can flow into the rearrangement reaction kettle 2 again after flowing into the rearrangement heat exchanger 3 for heat exchange and cooling, and a circulating reaction liquid loop is formed.
As shown in fig. 1, the cooling system further comprises a rearrangement circulation pump 5 arranged between the rearrangement reaction kettle 2 and the rearrangement heat exchanger 3, and the rearrangement circulation pump 5 is used for providing power for conveying the circulating reaction liquid. Specifically, the rearrangement circulation pump 5 is arranged on a connecting pipeline between the first rearrangement discharge port 22 and the feed port 33 of the rearrangement heat exchanger 3, the first rearrangement discharge port 22 is communicated with the inlet end of the rearrangement circulation pump 5, the outlet end of the rearrangement circulation pump 5 is communicated with the feed port 33 of the rearrangement heat exchanger 3, and the inlet end of the rearrangement circulation pump 5 is also connected with the nicotinic acid feed line 301, so that the nicotinic acid can be pumped into the rearrangement reaction kettle 2 together with the reaction liquid through the rearrangement circulation pump 5. The reaction liquid in the rearrangement reaction kettle 2 is conveyed to the rearrangement heat exchanger 3 through the rearrangement circulating pump 5 for heat exchange and cooling, so that the output efficiency of the cooling liquid can be improved, and the circulating cooling efficiency of the cooling liquid can be further improved.
As shown in fig. 1, the cooling system further comprises a three-way valve 6 arranged on a pipeline for communicating the feed port 33 of the rearrangement heat exchanger 3 with the rearrangement circulating pump 5, wherein the inlet end of the three-way valve 6 is communicated with the outlet end of the rearrangement circulating pump 5, the first outlet end of the three-way valve 6 is communicated with the feed port 33 of the rearrangement heat exchanger 3, and the discharge port 34 of the rearrangement heat exchanger 3 is communicated with the second rearrangement feed port 23 to form a reaction liquid heat exchange channel 201; the second outlet end of the three-way valve 6 is directly communicated with the second double-discharge feed inlet 23 of the rearrangement reaction kettle 2 to form a bypass channel 202, and the reaction liquid does not exchange heat when flowing through the bypass channel 202.
The bypass channel 202 is used for maintaining the overall circulation balance of the reaction solution at the initial stage of the rearrangement reaction, the temperature of the reaction solution is lower at the initial stage of the rearrangement reaction, the reaction solution in the rearrangement reaction kettle 2 flows out from the first rearrangement discharge port 22 and is pumped into the rearrangement reaction kettle 2 through the rearrangement circulation pump 5 by the bypass channel 202 to react, nicotinic acid is added from the inlet of the rearrangement circulation pump 5 to be mixed with the reaction solution and enter the rearrangement reaction kettle 2, and is mixed with cyclohexanone oxime added from the first rearrangement feed port 21 to react in the rearrangement reaction kettle 2, a large amount of heat is discharged along with the progress of the reaction, a part of the reaction solution flows out from the first rearrangement discharge port 22 at the bottom, enters the rearrangement heat exchanger 3 through the reaction solution heat exchange channel 201 to exchange heat and cool, the heat generated by the reaction is removed, and then circulates into the rearrangement reaction kettle 2 to react to form a reaction solution circulation loop, so that the reaction temperature in the rearrangement reaction kettle 2 is maintained within a certain range.
Because the temperature required by the rearrangement reaction is higher, the heat exchange cooling is performed by using the cooling liquid (for example, 60 ℃) with a certain temperature after the oximation reaction, so that the reaction heat generated by the rearrangement reaction can be quickly absorbed, the temperature in the rearrangement reaction kettle 2 is kept in a certain range, the temperature difference of the cooling liquid when the cooling liquid (for example, 0 ℃) is used for absorbing heat is reduced, the energy loss is reduced, and the utilization rate of the cooling liquid is improved. In addition, after the rearrangement cooling is changed into heat exchange by hot water with a certain temperature, the temperature difference at two sides of the tube array of the rearrangement heat exchanger is reduced, the tube array scaling phenomenon caused by long-term operation of the rearrangement heat exchanger is avoided, and the product quality is improved.
In some embodiments, as shown in fig. 1, the cooling system further includes a cooling liquid tank 7, one end of the cooling liquid tank 7 is communicated with the cooling liquid return header pipe 102, the other end of the cooling liquid tank 7 is communicated with the cooling liquid inlet header pipe 101, the reaction kettle jacket 11, the rearrangement heat exchanger 3 and the cooling liquid tank 7 are sequentially communicated along the cooling liquid flow direction to form a cooling circulation loop, so that direct discharge of cooling liquid can be avoided, the environmental impact is avoided, and meanwhile, water resources are effectively saved.
Further, the cooling system further comprises a circulating cooling pump 8 arranged between the cooling liquid tank 7 and the cooling liquid inlet header pipe 101, wherein the circulating cooling pump 8 is used for providing power for cooling liquid, and the cooling liquid is pumped into the reaction kettle jacket 11 for cooling.
Further, the cooling system further comprises a cooler (not shown) for cooling the cooling liquid flowing back to the cooling liquid tank 7, the cooler is arranged in the cooling liquid tank 7, and the cooling liquid flowing back to the cooling liquid tank 7 after cooling can flow into the oximation reaction kettle 1 again after being cooled by the cooler to participate in circulating cooling.
In addition, the cooling liquid inlet manifold 101 can be connected with an external cooling liquid source, and when the cooling liquid in the cooling circulation system is insufficient, the cooling liquid is timely supplemented.
In the embodiment of the invention, the oximation reaction and the rearrangement reaction are cooled by taking the cooling liquid as a cooling medium, wherein the cooling liquid can be cooling water or any other liquid of any proper type so as to absorb the reaction heat and transport the absorbed heat away; in other embodiments, the cooling medium may be any other suitable type of gas to absorb the heat of reaction and transport the absorbed heat away, and the invention is not particularly limited.
In some embodiments, when the cooling liquid is a corrosive liquid, such as an alkaline liquid, it is preferable to provide a coil within the reactor jacket 11. Because the cooling liquid is positioned in the coil pipe in the reaction kettle jacket 11, even if the coil pipe is corroded and damaged, the cooling liquid only flows into the reaction kettle jacket 11 and cannot flow into the oximation reaction kettle 1, so that the oximation reaction kettle 1 cannot be damaged, and the safety accident risk is reduced.
In some embodiments, the cooling system further includes a controller (not shown in the figures) electrically and/or signally connected to the first control valve 41, the second control valve 42, the third control valve 43, the rearrangement circulation pump 5 and the circulation cooling pump 8, respectively, and the controller can control the circulation of the cooling liquid and regulate the flow rate by controlling the control valves and pumps, thereby improving the control accuracy.
In some embodiments, the cooling system further includes temperature sensors (not shown in the figure) electrically connected to the controller, where the temperature sensors are respectively disposed in the oximation reaction kettle 1 and the rearrangement reaction kettle 2, and are used for monitoring temperatures in the oximation reaction kettle 1 and the rearrangement reaction kettle 2 in real time, transmitting temperature information to the controller, and the controller can control components such as a control valve and a pump in a connecting pipeline according to the temperature information transmitted by the temperature sensors, so as to control the operation of the whole cooling system.
According to the cooling system provided by the embodiment of the invention, the cooling liquid for the oximation reaction of the caprolactam is reused according to the reaction sequence, so that the cooling liquid absorbs the heat released by the oximation reaction and then enters the rearrangement heat exchanger to absorb the heat released by the rearrangement reaction, and the cooling liquid is recycled, so that the cooling liquid resources (such as water resources) are recycled in the cooling process of caprolactam preparation, and the production cost is reduced while the energy is saved and the consumption is reduced.
In the cooling process of the cooling system provided by the embodiment of the invention, firstly, the oximation reaction kettle 1 is cooled by using cooling liquid to obtain cooling liquid with a first temperature; next, the cooling liquid at the first temperature is introduced into the rearrangement heat exchanger 3 to cool the reaction liquid discharged from the rearrangement reaction kettle 2.
The first temperature mentioned above represents a temperature within a certain temperature range, which is a dynamic temperature, and changes in real time as the oximation reaction proceeds. The cooling liquid absorbs heat and cools the oximation reaction to obtain cooling liquid with a first temperature, wherein the first temperature is higher than the temperature of the cooling liquid entering from the cooling liquid inlet main pipe 101 and is lower than the temperature of the reaction liquid in the rearrangement reaction kettle 2, so that the cooling liquid with the first temperature can absorb heat and cool the reaction liquid in the rearrangement reaction, the temperature in the rearrangement reaction kettle 2 is maintained in a certain range, and the product quality of the rearrangement reaction is improved.
In the present invention, a crude caprolactam product can be obtained by performing a Beckmann rearrangement reaction using cyclohexanone oxime. In the present invention, the steps and conditions for carrying out the Beckmann rearrangement reaction of cyclohexanone oxime may be carried out according to conventional technical means in the art, and the present invention is not particularly limited thereto.
The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, the scope of which is defined by the claims. Various modifications and equivalent arrangements of this invention will occur to those skilled in the art, and are intended to be within the spirit and scope of the invention.
Claims (8)
1. A cooling system for cooling a process for the preparation of caprolactam, the cooling system comprising:
the oximation reaction kettle is provided with a reaction kettle jacket at the periphery, and the reaction kettle jacket is provided with a first cooling liquid inlet and a first cooling liquid outlet;
The rearrangement reaction kettle is provided with a first rearrangement feed port and a first rearrangement discharge port, and the first rearrangement feed port is communicated with the discharge port of the oximation reaction kettle;
The first rearrangement discharge port is communicated with the feed port of the rearrangement heat exchanger, the rearrangement heat exchanger is provided with a second cooling liquid inlet and a second cooling liquid outlet, the second cooling liquid inlet is communicated with the first cooling liquid outlet, so that cooling liquid flows into the rearrangement heat exchanger after being subjected to heat exchange cooling in the reaction kettle jacket, and the reaction liquid discharged after the rearrangement reaction kettle is subjected to heat exchange cooling;
the cooling system further comprises a cooling liquid inlet main pipe and a cooling liquid return main pipe, wherein the cooling liquid inlet main pipe is connected with the first cooling liquid inlet, and the cooling liquid return main pipe is connected with the second cooling liquid outlet;
The reaction kettle jacket is internally provided with a coil pipe, an inlet of the coil pipe is communicated with the first cooling liquid inlet, an outlet of the coil pipe is communicated with the first cooling liquid outlet, and the coil pipe is coiled in the reaction kettle jacket and fixedly connected with the reaction kettle jacket through a fixing piece.
2. The cooling system of claim 1, wherein the second coolant inlet communicates with the first coolant outlet through a first conduit, the first conduit having a first control valve thereon; and a second control valve is arranged on the cooling liquid return main pipe.
3. The cooling system according to claim 2, wherein the first cooling liquid outlet of the reaction kettle jacket is communicated with the cooling liquid return header pipe through a second pipeline, and a third control valve is arranged on the second pipeline.
4. The cooling system of claim 1, further comprising a cooling liquid tank, wherein one end of the cooling liquid tank is communicated with the cooling liquid return main pipe, the other end of the cooling liquid tank is communicated with the cooling liquid inlet main pipe, the reaction kettle jacket, the rearrangement heat exchanger and the cooling liquid tank are sequentially communicated along the cooling liquid flow direction to form a cooling circulation loop, and a circulating water pump is further arranged on a connecting pipe between the cooling liquid tank and the cooling liquid inlet main pipe.
5. The cooling system of claim 4, further comprising a cooler for cooling the coolant flowing back to the coolant tank, the cooler disposed within the coolant tank.
6. The cooling system of claim 1, wherein the rearrangement reaction kettle further comprises a second rearrangement feed port, the second rearrangement feed port is a circulating liquid feed port, the feed port of the rearrangement heat exchanger is communicated with the first rearrangement discharge port of the rearrangement reaction kettle, and the discharge port of the rearrangement heat exchanger is communicated with the second rearrangement feed port, so that the reaction liquid in the rearrangement reaction kettle flows into the rearrangement heat exchanger for heat exchange and cooling, and then is circulated into the rearrangement reaction kettle.
7. The cooling system of claim 6, further comprising a rearrangement circulation pump disposed on a connection line between the first rearrangement discharge port of the rearrangement reaction kettle and the feed port of the rearrangement heat exchanger, the first rearrangement discharge port being in communication with an inlet end of the rearrangement circulation pump, an outlet end of the rearrangement circulation pump being in communication with the feed port of the rearrangement heat exchanger, the inlet end of the rearrangement circulation pump being further connected with a nicotinic acid feed line.
8. The cooling system of claim 7, further comprising a three-way valve disposed on a line communicating the feed port of the rearrangement heat exchanger with the rearrangement recycle pump, an inlet end of the three-way valve communicating with the outlet end of the rearrangement recycle pump, a first outlet end of the three-way valve communicating with the feed port of the rearrangement heat exchanger, and a second outlet end of the three-way valve communicating with the recycle liquid feed port of the rearrangement reaction kettle.
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