CN106496069B - Energy-saving device and energy-saving method of acetonitrile refining system - Google Patents
Energy-saving device and energy-saving method of acetonitrile refining system Download PDFInfo
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- CN106496069B CN106496069B CN201510557614.4A CN201510557614A CN106496069B CN 106496069 B CN106496069 B CN 106496069B CN 201510557614 A CN201510557614 A CN 201510557614A CN 106496069 B CN106496069 B CN 106496069B
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- separation tower
- steam condensate
- reboiler
- chemical reaction
- separation
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- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 title claims abstract description 198
- 238000007670 refining Methods 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 title claims description 23
- 238000000926 separation method Methods 0.000 claims abstract description 103
- 238000006243 chemical reaction Methods 0.000 claims abstract description 50
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 238000001704 evaporation Methods 0.000 claims abstract description 7
- 230000008020 evaporation Effects 0.000 claims abstract description 7
- 238000000746 purification Methods 0.000 claims description 11
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 16
- 239000000126 substance Substances 0.000 description 11
- 239000000463 material Substances 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000012535 impurity Substances 0.000 description 5
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 230000005494 condensation Effects 0.000 description 4
- 230000018044 dehydration Effects 0.000 description 4
- 238000006297 dehydration reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 3
- ZCQWOFVYLHDMMC-UHFFFAOYSA-N Oxazole Chemical compound C1=COC=N1 ZCQWOFVYLHDMMC-UHFFFAOYSA-N 0.000 description 2
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 2
- 239000012295 chemical reaction liquid Substances 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 1
- 238000010533 azeotropic distillation Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- FVSKHRXBFJPNKK-UHFFFAOYSA-N propionitrile Chemical compound CCC#N FVSKHRXBFJPNKK-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Abstract
An energy saving device for an acetonitrile refining system, the device comprising: a first separation column reboiler; a second separation column reboiler; a third separation column reboiler; a steam condensate collection unit; and a chemical reaction kettle heating jacket, wherein the first separation tower reboiler, the second separation tower reboiler, and the third separation tower reboiler respectively generate evaporation amounts required for the first separation tower, the second separation tower, and the third separation tower using low pressure steam, and generate steam condensate, the steam condensate collecting unit collects the steam condensate, and supplies the steam condensate to the chemical reaction kettle heating jacket, and the chemical reaction kettle heating jacket supplies heat to the chemical reaction kettle using the steam condensate.
Description
Technical Field
The invention relates to an energy-saving device and an energy-saving method in a high-purity acetonitrile refining system.
Background
In the production process of acrylonitrile, acetonitrile and hydrocyanic acid are recovered as byproducts, and a combined process of a dehydrocyanate tower, chemical treatment, decompression and pressure azeotropic distillation is generally adopted to continuously recover the acetonitrile, so that water and impurities in the acetonitrile can be effectively removed.
For example, EP055920 discloses a process for continuously recovering acetonitrile, which adopts a method of rectifying to remove light components such as hydrocyanic acid, further removing hydrocyanic acid by chemical treatment, decompressing and rectifying to combine dehydration, improves the refining recovery rate of acetonitrile, and can obtain acetonitrile products with higher purity. CN1328994a also discloses a method for refining high-purity acetonitrile, which continuously recovers high-purity acetonitrile from crude acetonitrile containing acetonitrile, water, HCN, oxazole and heavy organics, improves the conventional process for continuously recovering acetonitrile, and smoothly discharges accumulated oxazole out of the system by adding a liquid phase extraction port at the upper part of the rectifying section of the first separation tower. CN1328993a also discloses a process for continuously recovering acetonitrile, which is to remove HCN by rectifying by adding alkaline compound locally in the rectifying section of the conventional vacuum rectifying tower and pressure rectifying tower, so as to achieve the purpose of removing trace HCN in acetonitrile.
In the prior art, the process of removing light components such as hydrocyanic acid and the like in a first separation tower and extracting impurities such as water and the like from a side line of a stripping section in a gas phase is adopted, and acetonitrile finished products are obtained after chemical treatment, decompression and pressurization dehydration of acetonitrile materials are extracted. Typically, in this process, the required amount of evaporation in the first, second and third separation columns, respectively, is from the respective bottoms reboilers, the heat required for the reboilers being provided by low pressure steam. On the other hand, the heating source in the chemical treatment is also low-pressure steam. As shown in FIG. 1, the chemical reaction kettle 2 is heated by jacket steam, steam 17 is added from the upper part of the jacket, and steam condensate 18 flows out from the bottom of the jacket.
Disclosure of Invention
In general, the chemical treatment carried out in the chemical reaction vessel 2 does not require an excessively high temperature, and is generally controlled to 40 to 70 ℃. The present inventors have made extensive studies and have found that steam condensate generated in the bottoms reboilers of the first, second and third separation columns is sufficient to meet the heat requirement of the chemical reaction kettle 2.
Therefore, the invention aims to provide an energy-saving device and an energy-saving method in a high-purity acetonitrile refining system. According to the invention, the steam condensate of the reboiler of each separation tower in the acetonitrile refining system is collected and reused as a heat source of the chemical reaction kettle, and the method has the characteristics of simple operation, easy control of reaction temperature and lower energy consumption when the chemical reaction is completed.
In one aspect, the present invention provides an energy saving device for acetonitrile refining system, the device comprising:
a first separation column reboiler;
a second separation column reboiler;
a third separation column reboiler;
A steam condensate collection unit; and
A heating jacket of the chemical reaction kettle, wherein,
The first separation tower reboiler, the second separation tower reboiler and the third separation tower reboiler respectively utilize low-pressure steam to generate evaporation amounts required by the first separation tower, the second separation tower and the third separation tower and generate steam condensate,
The steam condensate collecting unit collects the steam condensate and supplies the steam condensate to the heating jacket of the chemical reaction kettle, and
The heating jacket of the chemical reaction kettle supplies heat to the chemical reaction kettle by utilizing the steam condensate.
In the energy-saving device of the acetonitrile refining system of the present invention, preferably, the steam condensate collecting unit is a condensate tank or a condensate header pipe.
In the energy saving device of the acetonitrile purification system of the present invention, the temperature of the steam condensate is preferably 80 to 120 ℃.
In the energy-saving device of the acetonitrile purification system of the present invention, preferably, the temperature variation range of the chemical reaction vessel is ±3 ℃.
In another aspect of the present invention, an energy saving method for an acetonitrile refining system is provided, the method comprising the steps of:
The low-pressure steam is utilized by a first separation tower reboiler, a second separation tower reboiler and a third separation tower reboiler to generate evaporation capacity required by the first separation tower, the second separation tower and the third separation tower respectively, and steam condensate is generated;
collecting the steam condensate to the steam condensate collecting unit; and
And supplying the steam condensate in the steam condensate collecting unit to a heating jacket of the chemical reaction kettle so as to supply heat to the chemical reaction kettle.
In the energy-saving method of the acetonitrile refining system of the present invention, preferably, the steam condensate collecting unit is a condensate tank or a condensate header pipe.
In the energy-saving method of the acetonitrile purification system of the present invention, the temperature of the steam condensate is preferably 80 to 120 ℃.
In the energy-saving method of the acetonitrile purification system of the present invention, preferably, the temperature variation range of the chemical reaction vessel is ±3 ℃.
Drawings
FIG. 1 is a schematic diagram of a prior art acetonitrile purification system.
Fig. 2 is a schematic diagram of an acetonitrile purification system according to a first embodiment of the present invention.
Fig. 3 is a schematic diagram of an acetonitrile purification system according to a second embodiment of the present invention.
List of reference marks
1: First separation tower
2: Chemical reaction kettle
3: Second separation tower
4: Third separation tower
5: Reboiler of first separation tower
6: Heating jacket of chemical reaction kettle
7: Reboiler of second separation tower
8: Third separation column reboiler
10. 17, 20, 30: Low pressure steam
11. 18, 21, 31: Steam condensate
35: Water condensation tank
36: Condensate header pipe
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[ First embodiment ]
A schematic diagram of an acetonitrile purification system according to a first embodiment of the present invention is shown in fig. 2. Raw material crude acetonitrile 9 enters from a raw material inlet positioned in the middle of the first separation column. The feedstock may comprise partially purified acetonitrile and may be from any suitable source, such as from the top of an acrylonitrile plant acetonitrile stripping column, and may comprise, in weight percent, 20 to 80% acetonitrile, 1 to 4% hcn,0.1 to 0.3% acrylonitrile, and 20 to 79% water. After the gas phase material flow 12 at the top of the first separation tower is condensed by the condenser of the first separation tower, all condensate 14 flows back, and the non-condensable gas hydrocyanic acid and other light components 13 are discharged out of the system for removal. The water and heavy components 16 are partially removed from the tower bottom, and the water-containing acetonitrile 15 with light components removed is pumped out of the chemical reaction kettle 2 from the side line gas phase at the lower part of the stripping section of the dehydrocyanate tower 1.
The water-containing acetonitrile 15 from the side line of the first separation tower enters the chemical reaction kettle 2, and simultaneously sodium hydroxide solution is added for chemical treatment to remove impurities such as free hydrocyanic acid, a small amount of acrylonitrile and the like.
The reaction liquid 19 after chemical treatment enters from the middle part of the second separation tower 3, acetonitrile 22 for removing heavy components and most of water is distilled from the top of the tower, part of the reaction liquid after condensation and cooling flows in as reflux 23 from the reflux port of the top of the tower, and the rest 24 is sent to the third separation tower 4; water and heavy component impurities 25 are discharged from the column bottom.
The acetonitrile material 24 from the top of the second separation tower 3, from which most of water is removed, enters the third separation tower 4, the acetonitrile material 26 with more water at the top of the third separation tower is condensed and cooled, part of the material 27 is refluxed, and the rest of the material 28 is returned to the feed 19 of the second separation tower 3 or the feed 9 of the first separation tower 1; the material 32 containing heavy component acetonitrile at the tower bottom returns to the feed 19 of the second separation tower 3; the high-purity finished acetonitrile 29 is extracted from the gas phase side line at the lower part of the stripping section of the third separation tower 4.
In the above acetonitrile purification system, the evaporation amounts required for the first separation column 1, the second separation column 3, and the third separation column 4 are respectively from the first separation column reboiler 5, the second separation column reboiler 7, and the third separation column reboiler 8. The heat required for the three reboilers is provided by low pressure steam. As shown in fig. 2, low pressure steam 10, 20 and 30 enters the three separation column reboilers 5, 7 and 8, respectively, and steam condensate 11, 21 and 31 formed after condensation flows out of the separation column reboilers 5, 7 and 8, respectively, and is collected into the condensate tank 35 via connection pipes 37, 38 and 39. After cascade control adjustment of the temperature and the condensate flow rate of the chemical reaction kettle, the steam condensate 33 in the condensate tank 35 is conveyed to the heating jacket 6 of the chemical reaction kettle 2 to provide heat required by chemical treatment. Finally, return water 34 flows out from the upper portion of the heating jacket 6.
[ Second embodiment ]
Hereinafter, a second embodiment of the present invention will be described with reference to fig. 3. The same components in the energy saving system of the second embodiment as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in fig. 3, the second embodiment of the present invention is different from the first embodiment in that a condensate tank 35 is not provided, and instead, a jacketed condensate header 36 is provided. Specifically, steam condensate 11, 21 and 31 from the first separation column reboiler 5, the second separation column reboiler 7 and the third separation column reboiler 8 are respectively connected to a jacket condensate header 36 of the chemical reaction kettle through connecting pipelines 37, 38 and 39. After cascade control and adjustment of the temperature and the condensate flow of the chemical reaction kettle, condensate 33 required by steam condensate 33 in a condensate header pipe 36 is conveyed to a heating jacket 6 of the chemical reaction kettle 2 so as to provide heat required by chemical treatment. Finally, return water 34 flows out from the upper portion of the heating jacket 6.
Typically, the operating temperature of the chemical reaction vessel is in the range of 40-70 ℃. Therefore, in the above embodiment, the temperature of the steam condensate is preferably 80 to 120 ℃, more preferably 90 to 100 ℃. Also, according to an embodiment of the present invention, the temperature of the chemical reaction tank can be adjusted within a range of ±3℃.
The invention is further illustrated by the following examples.
Examples
[ Comparative example 1]
According to the acetonitrile refining system shown in FIG. 1, raw material crude acetonitrile containing acetonitrile 50% and hydrocyanic acid 1.5% by weight is added from the middle part of the first separation tower, the operation pressure is normal pressure, the tower top temperature is 50 ℃, the tower bottom temperature is 115 ℃, and the side extraction temperature of the stripping section is 92 ℃. Removing hydrocyanic acid at the tower top, removing chemical treatment of acetonitrile with 75% of concentration extracted from the side line of stripping section, and mixing the following components according to the molar ratio of total cyanogen to alkali: adding 40% NaOH solution 1:2.0 for reaction for 4-6 hours, controlling the steam consumption by the temperature of the chemical reaction kettle in series connection, wherein the steam consumption is about 0.07kg steam/kg acetonitrile, and the temperature change of the chemical reaction kettle can be controlled at 50+/-5 ℃. And (3) performing reduced pressure dehydration in a second separation tower and pressurized dehydration in a third separation tower after chemical treatment, wherein the tower top pressure of the second separation tower is 0.026Mpa, the top temperature is 40 ℃, the kettle temperature is 64 ℃, and removing water, allyl alcohol, propionitrile and other impurities from the tower kettle of the second separation tower. The top pressure of the third separation tower is 0.3MPa, the top temperature is 108 ℃, the kettle temperature is 125 ℃, and the finished acetonitrile is obtained from the side line of the third separation tower.
[ Example 1]
According to the acetonitrile purification system shown in fig. 2, steam condensate of reboilers of the first separation tower, the second separation tower and the third separation tower is collected in a condensate tank, and the steam condensate is supplied from the condensate tank to a heating jacket to heat a chemical reaction kettle. The temperature control mode of the chemical reaction kettle is changed from controlling the steam consumption to the condensation water consumption correspondingly, the temperature change of the chemical reaction kettle can be controlled at 50+/-2 ℃, the temperature control is more stable, the steam input of 0.07kg steam/kg acetonitrile is omitted, and the energy consumption is saved. After the transformation, qualified finished acetonitrile is obtained from the side line of the third separation tower.
[ Example 2]
According to the acetonitrile refining system shown in fig. 3, a condensate header pipe which is sent to a heating jacket of a chemical reaction kettle is added on a steam condensate discharge pipe of a reboiler of a first separation tower, a second separation tower and a third separation tower, the temperature control mode of the chemical reaction kettle is changed from the corresponding control of steam consumption to condensate consumption, partial condensate is adopted for heating the chemical reaction kettle, the temperature change of the chemical reaction kettle can be controlled to be 50+/-2 ℃, the temperature control is more stable, the steam input of 0.07kg steam/kg acetonitrile is omitted, and the energy consumption is saved. After the transformation, qualified finished acetonitrile is obtained from the side line of the third separation tower.
As described above, according to the invention, the steam condensate of the reboiler of each separation tower in the acetonitrile refining system is collected and reused as a heat source of the chemical reaction kettle, and the method has the characteristics of simple operation, easy control of reaction temperature and lower energy consumption when the chemical reaction is completed.
Claims (8)
1. An energy saving device for an acetonitrile refining system, the device comprising:
a first separation column reboiler;
a second separation column reboiler;
a third separation column reboiler;
A steam condensate collection unit; and
A heating jacket of the chemical reaction kettle,
Wherein the first separation tower reboiler, the second separation tower reboiler and the third separation tower reboiler are respectively connected to the first separation tower, the second separation tower and the third separation tower through connecting pipelines, and respectively utilize low-pressure steam to generate evaporation amounts required by the first separation tower, the second separation tower and the third separation tower and steam condensate,
The steam condensate collecting unit is connected to the first, second and third separation column reboilers via a connecting pipe to collect the steam condensate and supply the steam condensate to the chemical reaction kettle heating jacket via a connecting pipe, and
The heating jacket of the chemical reaction kettle supplies heat to the chemical reaction kettle by utilizing the steam condensate.
2. The energy saving device of acetonitrile refining system according to claim 1, wherein the steam condensate collecting unit is a condensate tank or a condensate header pipe.
3. The energy saving device of acetonitrile refining system according to claim 1, wherein the temperature of the steam condensate is 80-120 ℃.
4. The energy saving device for acetonitrile purification system according to any one of claims 1 to 3, wherein the temperature change range of the chemical reaction vessel is ±3 ℃.
5. An energy saving method of an acetonitrile refining system, comprising the steps of:
generating evaporation amounts required by the first separation tower, the second separation tower and the third separation tower by using low-pressure steam through the first separation tower reboiler, the second separation tower reboiler and the third separation tower reboiler respectively, and generating steam condensate, wherein the first separation tower reboiler, the second separation tower reboiler and the third separation tower reboiler are connected to the first separation tower, the second separation tower and the third separation tower respectively through connecting pipelines;
collecting the steam condensate into the steam condensate collecting unit through a connecting pipeline connecting the steam condensate collecting unit with the first separation tower reboiler, the second separation tower reboiler and the third separation tower reboiler; and
And supplying the steam condensate in the steam condensate collecting unit to a heating jacket of the chemical reaction kettle through a connecting pipeline so as to supply heat to the chemical reaction kettle.
6. The energy saving method of acetonitrile refining system according to claim 5, wherein the steam condensate collecting unit is a condensate tank or a condensate header pipe.
7. The energy saving method of acetonitrile refining system according to claim 5, wherein the temperature of the steam condensate is 80-120 ℃.
8. The energy saving method of acetonitrile refining system according to claim 5-7, wherein the temperature variation range of the chemical reaction kettle is + -3 ℃.
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| CN109704990B (en) * | 2017-10-26 | 2022-02-01 | 中国石油化工股份有限公司 | Refining method of high-purity acetonitrile |
| CN112441939B (en) * | 2019-09-05 | 2024-03-22 | 中石油吉林化工工程有限公司 | Acrylonitrile production system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1328993A (en) * | 2000-06-15 | 2002-01-02 | 中国石油化工集团公司 | Method for removing micro hydrocyanic acid in the course of refining high-purity acetonitrile |
| CN102633679A (en) * | 2012-04-01 | 2012-08-15 | 中国天辰工程有限公司 | Continuous purification method for crude acetonitrile |
| CN104203909A (en) * | 2012-03-26 | 2014-12-10 | 旭化成化学株式会社 | Method for purifying acetonitrile |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1328993A (en) * | 2000-06-15 | 2002-01-02 | 中国石油化工集团公司 | Method for removing micro hydrocyanic acid in the course of refining high-purity acetonitrile |
| CN104203909A (en) * | 2012-03-26 | 2014-12-10 | 旭化成化学株式会社 | Method for purifying acetonitrile |
| CN102633679A (en) * | 2012-04-01 | 2012-08-15 | 中国天辰工程有限公司 | Continuous purification method for crude acetonitrile |
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