CN111018813B - Double-tower continuous rectification device and method for maleic anhydride refining process - Google Patents
Double-tower continuous rectification device and method for maleic anhydride refining process Download PDFInfo
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- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
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Abstract
The invention provides a double-tower continuous rectification device and a method for a maleic anhydride refining process. The method comprises the steps of heating crude maleic anhydride to 80-180 ℃, and then feeding the crude maleic anhydride into a light component tower to remove low-boiling-point substances under a vacuum condition. In the technical scheme, the top fractions of the light component tower and the refining tower partially reflux, and part of the top fractions is subjected to secondary flash evaporation to remove low boiling point substances and returns to the rectification system. The material at the bottom of the light component tower enters a refining tower, maleic anhydride products are extracted from the side line of the refining tower, heavy components at the bottom of the refining tower return to a system for rectification and purification again, and the maleic anhydride is completely recycled in the process flow, so that the loss of the product is effectively reduced. The purity of the maleic anhydride product as a side discharge is not lower than 99.98%, the acrylic acid content is not more than 5ppm, the product melting color number is not more than 10, and the storage time of the liquid product is more than 30 days.
Description
Technical Field
The invention relates to the field of chemical industry, in particular to a double-tower continuous rectification device and a double-tower continuous rectification method in a maleic anhydride refining process.
Background
Maleic Anhydride (MAH) is a commonly used basic organic chemical raw material, is the second largest anhydride raw material next to phthalic anhydride in the world, and is widely applied to a series of important organic chemicals and fine chemicals such as synthetic resins, lubricating oil additives, medicines, food additives, 1, 4-butanediol, gamma-butyrolactone, tetrahydrofuran, succinic acid, fumaric acid and the like.
At present, devices which take DBP as an absorbent at home and abroad adopt a batch rectification method to purify crude anhydride, wherein the fraction at the top of the batch rectification tower needs to be cut by 5-10%, and the tar generated by MAH due to high-temperature polymerization needs to be regularly cleaned at the bottom of the tower. The intermittent rectification has the defects of high MAH loss, high energy consumption, more acid-containing wastewater discharge and low automation degree.
Disclosure of Invention
The present invention addresses the above-mentioned problems, such as the increase in the melting color (platinum-cobalt color) of MAH from No. 10 to No. 25 or more after 24 hours storage, and the color number of MAH at a high temperature of 140 ℃ for 2 hours exceeding 250, which cannot satisfy the color requirements of the downstream unsaturated resins. The invention provides a double-tower continuous rectification device and a double-tower continuous rectification method for 3 maleic anhydride refining processes.
The purpose of the invention can be realized by the following technical scheme:
the invention provides a double-tower continuous rectification device for a maleic anhydride refining process, which comprises a stripping tower, a light component tower, a refining tower and a crude anhydride tank, wherein the stripping tower is sequentially connected with a condenser and a condensing tank at the top of the stripping tower through a pipeline a; the output end of the crude anhydride tank is connected with the middle part of the light component tower through a pipeline b,
the bottom end of the light component tower is connected with the middle part of the refining tower, the top end of the light component tower is connected with the light component tower top tank, one output end of the bottom of the light component tower top tank is connected with a pipeline a through a pipeline c, and the other output end of the light component tower top tank is connected with the upper part of the light component tower through a pipeline d;
the top of the refining tower is connected with a refining tower top tank, one output end of the bottom of the refining tower top tank is connected with the upper part of the refining tower through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a pipeline b through a pipeline f;
and the output end at the bottom of the refining tower is connected with the middle part of the stripping tower through a rich solvent tank.
The second double-tower continuous rectification device for the maleic anhydride refining process provided by the invention comprises the following steps: the device comprises a stripping tower, a light component tower, a refining tower and a crude anhydride tank, wherein the stripping tower is sequentially connected with a condenser and a condensing tank at the top of the stripping tower through a pipeline a; the output end of the crude anhydride tank is connected with the middle part of the light component tower through a pipeline b,
the bottom end of the light component tower is connected with the middle part of the refining tower, the top end of the light component tower is connected with the light component tower top tank, one output end of the bottom of the light component tower top tank is connected with the condensing tank through a pipeline c, and the other output end of the light component tower is connected with the upper part of the light component tower through a pipeline d;
the top of the refining tower is connected with a refining tower top tank, one output end of the bottom of the refining tower top tank is connected with the upper part of the refining tower through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a pipeline b through a pipeline f;
and the output end at the bottom of the refining tower is connected with the middle part of the stripping tower through a rich solvent tank.
The invention provides a double-tower continuous rectifying device for a third maleic anhydride refining process, which comprises the following steps: the device comprises a stripping tower, a light component tower, a refining tower and a crude anhydride tank, wherein the stripping tower is sequentially connected with a condenser and a condensing tank at the top of the stripping tower through a pipeline a; the output end of the crude anhydride tank is connected with the middle part of the light component tower through a pipeline b, and the output end of the bottom of the flash tank is connected with the crude anhydride tank;
the bottom end of the light component tower is connected with the middle part of the refining tower, the top end of the light component tower is connected with the light component tower top tank, one output end of the bottom of the light component tower top tank is connected with the flash tank through a pipeline c, and the other output end of the light component tower is connected with the upper part of the light component tower through a pipeline d;
the top of the refining tower is connected with a refining tower top tank, one output end of the bottom of the refining tower top tank is connected with the upper part of the refining tower through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a flash tank through a pipeline f;
and the output end at the bottom of the refining tower is connected with the middle part of the stripping tower through a rich solvent tank.
The technical scheme of the invention is as follows: the light component tower is connected with the light component tower top tank through a light component tower top condenser.
The technical scheme of the invention is as follows: the top of the refining tower is connected with a refining tower top tank through a refining tower top condenser.
The technical scheme of the invention is as follows: the bottom of the refining tower is connected with the lower part of the refining tower through a heat exchanger.
The technical scheme of the invention is as follows: the middle part of the refining tower is connected with a maleic anhydride product heat exchanger.
The technical scheme of the invention is as follows: the top output ends of the light component tower top tank and the refining tower top tank are connected with a vacuum system; the top condenser of the stripping tower is connected with a vacuum system of the stripping tower.
A utilizes the above-mentioned device to realize the double tower continuous rectification method of maleic anhydride refining process, said method comprises crude maleic anhydride in the crude anhydride pot is heated to 80-180 duC through the heat exchanger, under the vacuum condition, enter the light component tower and remove the low boiling point material, the bottom material of light component tower enters the refining tower, the maleic anhydride product outputs after passing the product maleic anhydride condenser heat exchange, the heavy component of tower bottom returns to the rich solvent pot; wherein the crude anhydride in the crude anhydride tank is heated to 140 ℃ by a crude anhydride tank heat exchanger, circulated back to the crude anhydride tank, and fed into the light component tower after circulating for 4-6 hours;
in some specific embodiments: the ratio of the flow through the line d to the flow through the line c is from 3:1 to 1: 1;
in some specific embodiments: the flow ratio of the pipeline e to the pipeline f is 30:1-20: 1;
in some specific embodiments: the absolute pressure in the light component tower is 5-35KPa, and the further preferable absolute pressure is 18-23 KPa;
in some specific embodiments: the bottom temperature of the light component tower is 140-150 ℃, and the top temperature of the light component tower is 135-145 ℃.
In some specific embodiments: the absolute pressure in the refining tower is 10-30KPa, and the further preferable absolute pressure is 16-18 KPa;
in some specific embodiments: the bottom temperature of the refining tower is 140-145 ℃, and the top temperature of the refining tower is 135-138 ℃.
The invention has the beneficial effects that:
the invention provides a double-tower continuous rectification process in a maleic anhydride refining process, which adopts double-tower continuous rectification, light components finally return to a crude anhydride tank for circulation, heavy components return to a rich solvent tank, and continuous production is realized without product loss and acid-containing wastewater discharge. The acrylic acid content in the maleic anhydride product is less than 5ppm, and the product purity is not lower than 99.98%; the storage time of the liquid maleic anhydride is more than 30 days, so that the storage problem of the liquid product is solved.
Drawings
FIG. 1 is a schematic view of a first double column continuous rectification apparatus provided in accordance with the present invention;
FIG. 2 is a schematic view of a second double column continuous rectification apparatus provided in accordance with the present invention;
FIG. 3 is a schematic diagram of a third double column continuous rectification apparatus provided in accordance with the present invention.
Wherein: 1 is a rich solvent tank; 2 is a stripping tower; 3 is a light component tower; 4 is a refining tower; 5 is a crude anhydride tank; 6 is a light component tower top tank; 7 is a refining tower top tank; 8 is a condenser at the top of a stripping tower; 9 is a light component overhead condenser; 10 is a refining tower top condenser; 11 is a crude anhydride tank heat exchanger; 12 is a vacuum system; 13 is a maleic anhydride product condenser; a stripping tower vacuum system 14, a heat exchanger 15, a condensing tank 16 and a flash tank 17.
Detailed Description
The invention is further illustrated by the following examples, without limiting the scope of the invention:
apparatus of example 1:
the device comprises a stripping tower (2), a light component tower (3), a refining tower (4) and a crude anhydride tank (5), wherein the stripping tower (2) is sequentially connected with a stripping tower top condenser (8) and a condensing tank (16) through a pipeline a; the output end of the crude anhydride tank (5) is connected with the middle part of the light component tower (3) through a pipeline b,
the bottom end of the light component tower (3) is connected with the middle part of the refining tower (4), the top end of the light component tower (3) is connected with a light component tower top tank (6), one output end of the bottom of the light component tower top tank (6) is connected with a pipeline a through a pipeline c, and the other output end of the bottom of the light component tower top tank is connected with the upper part of the light component tower (3) through a pipeline d;
the top of the refining tower (4) is connected with a refining tower top tank (7), one output end of the bottom of the refining tower top tank (7) is connected with the upper part of the refining tower (4) through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a pipeline b through a pipeline f;
the output end of the bottom of the refining tower (4) is connected with the middle part of the stripping tower (2) through a rich solvent tank (1). The light component tower (3) is connected with a light component tower top tank (6) through a light component tower top heat exchanger (9). The top of the refining tower (4) is connected with a refining tower top tank (7) through a refining tower top heat exchanger (10). The bottom of the refining tower (4) is connected with the lower part of the refining tower (4) through a heat exchanger (15). The middle part of the refining tower (4) is connected with a maleic anhydride heat exchanger (13). The top output ends of the light component tower top tank (6) and the refining tower top tank (7) are connected with a vacuum system (12); the stripping tower top heat exchanger (8) is connected with a stripping tower vacuum system (14).
Apparatus of example 2:
a double-tower continuous rectification device for a maleic anhydride refining process comprises a stripping tower (2), a light component tower (3), a refining tower (4) and a crude anhydride tank (5), wherein the stripping tower (2) is sequentially connected with a stripping tower top condenser (8) and a condensing tank (16) through a pipeline a; the output end of the crude anhydride tank (5) is connected with the middle part of the light component tower (3) through a pipeline b,
the bottom end of the light component tower (3) is connected with the middle part of the refining tower (4), the top end of the light component tower (3) is connected with a light component tower top tank (6), one output end of the bottom of the light component tower top tank (6) is connected with a condensing tank (16) through a pipeline c, and the other output end of the light component tower (3) is connected with the upper part of the light component tower (3) through a pipeline d;
the top of the refining tower (4) is connected with a refining tower top tank (7), one output end of the bottom of the refining tower top tank (7) is connected with the upper part of the refining tower (4) through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a pipeline b through a pipeline f;
the output end of the bottom of the refining tower (4) is connected with the middle part of the stripping tower (2) through a rich solvent tank (1). The light component tower (3) is connected with a light component tower top tank (6) through a light component tower top heat exchanger (9). The top of the refining tower (4) is connected with a refining tower top tank (7) through a refining tower top heat exchanger (10). The bottom of the refining tower (4) is connected with the lower part of the refining tower (4) through a heat exchanger (15). The middle part of the refining tower (4) is connected with a maleic anhydride heat exchanger (13). The top output ends of the light component tower top tank (6) and the refining tower top tank (7) are connected with a vacuum system (12); the stripping tower top heat exchanger (8) is connected with a stripping tower vacuum system (14).
Apparatus of example 3:
a double-tower continuous rectification device for a maleic anhydride refining process comprises a stripping tower (2), a light component tower (3), a refining tower (4) and a crude anhydride tank (5), wherein the stripping tower (2) is sequentially connected with a stripping tower top condenser (8) and a condensing tank (16) through a pipeline a; the output end of the crude anhydride tank (5) is connected with the middle part of the light component tower (3) through a pipeline b, and the output end of the bottom of the flash tank (17) is connected with the crude anhydride tank (5);
the bottom end of the light component tower (3) is connected with the middle part of the refining tower (4), the top end of the light component tower (3) is connected with a light component tower top tank (6), one output end of the bottom of the light component tower top tank (6) is connected with a flash tank (17) through a pipeline c, and the other output end of the light component tower (3) is connected with the upper part of the light component tower (3) through a pipeline d;
the top of the refining tower (4) is connected with a refining tower top tank (7), one output end of the bottom of the refining tower top tank (7) is connected with the upper part of the refining tower (4) through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a flash tank (17) through a pipeline f;
the output end of the bottom of the refining tower (4) is connected with the middle part of the stripping tower (2) through a rich solvent tank (1). The light component tower (3) is connected with a light component tower top tank (6) through a light component tower top heat exchanger (9). The top of the refining tower (4) is connected with a refining tower top tank (7) through a refining tower top heat exchanger (10). The bottom of the refining tower (4) is connected with the lower part of the refining tower (4) through a heat exchanger (15). The middle part of the refining tower (4) is connected with a maleic anhydride heat exchanger (13). The top output ends of the light component tower top tank (6) and the refining tower top tank (7) are connected with a vacuum system (12); the stripping tower top heat exchanger (8) is connected with a stripping tower vacuum system (14).
The following describes technical schemes 1 to 3 in detail, taking a continuous production device for producing 11.7 ten thousand tons of MAH every year as an example.
1. Temperature rise and vacuum build-up of the system
The light component column (3) and the refining column (4) and the line heat exchanger were heated to 90 ℃ by introducing hot air, the whole system was evacuated by an evacuation system, the pressure was evacuated to 15Kpa (absolute pressure), and the air in the system was replaced with nitrogen.
2. Light ends column feed
Heating crude anhydride in a crude anhydride tank (5) to 140 ℃ through a heat exchanger (11), circulating the crude anhydride to the crude anhydride tank (5), circulating the crude anhydride for 4-6 hours, feeding the crude anhydride to a light component tower (3), heating maleic anhydride to 148-150 ℃ through a bottom heat exchanger, controlling the temperature of the tower top to 143-145 ℃, controlling the pressure to 20-22Kpa (absolute pressure), condensing steam containing the maleic anhydride and the light component at the tower top through a light component tower top condenser (9), extracting low-boiling-point materials such as acrylic acid through a vacuum system, condensing the maleic anhydride to the light component tower top tank (6), returning liquid in the light component tower top tank (6) to the light component tower (3), returning part of the liquid to a stripping tower top condenser (8), or returning to a condensing tank (16) as shown in figure 2, or returning to a flash tank (17) for flash evaporation and returning the crude anhydride tank (5) as shown in figure 3. The ratio of the flow through line D to the flow through line c is from 3:1 to 1:1, and after circulation has been established, the feed to the refining column (D) is carried out.
3. Refining column feed
After feeding into the refining tower (4), heating the material by a heat exchanger (15), heating the tower bottom to 140-145 ℃, heating the tower top to 135-138 ℃, vacuumizing to 16-18Kpa (absolute pressure), condensing the maleic anhydride steam at the tower top into a refining tower top tank (7) by a refining tower top condenser (10), partially refluxing to the refining tower (4) by a pipeline e, and partially connecting with a pipeline a by a pipeline f, as shown in figure 1 and figure 2, or returning the obtained product to a crude anhydride tank (5) after flash evaporation through a back flash evaporation tank (17) through a pipeline f, controlling the flow ratio of the obtained product to the obtained product through a pipeline e to the obtained product f to be 30:1-20:1, returning the obtained tower bottom material to the rich solvent tank (1) through the pipeline, controlling the flow to be 0.1-1t/h, extracting the refined maleic anhydride product, and exchanging heat to 60-70 ℃ through a product maleic anhydride condenser (13).
The following is an analysis method of the control index
1. Purity and impurity determination of maleic anhydride product
1.1 Main instruments and devices
Gas chromatograph, Agilent Technologies 7890A, Agilent Technologies, Inc. of Agilent Technologies, USA
1.2 Primary reagents and materials
1.3 test procedure
Acid, alcohol, monoester impurities other than anhydrides and full esters in the maleic anhydride product all need to undergo a silylation reaction with an N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) reagent to ensure that peaks can be produced on the selected chromatographic column.
The quantification was done by internal standard method, where the internal standard was dodecane.
1) Preparation of internal standard liquid
Weighing 2g of dodecane with the accuracy of 0.0002g, placing the dodecane in a 1L brown volumetric flask, adding 200mL of silanization (BSTFA) reagent, adding an appropriate amount of acetonitrile, fully mixing, and then using the acetonitrile to perform volume fixing to the scale mark.
2) Preparation Standard
According to the quality index of the product, certain mass of Maleic Acid (MAC), Fumaric Acid (FAC), acetic Acid (ACET), acrylic acid (ACAD), Phthalic Acid (PAC), n-butyl alcohol (BuOH), dibutyl phthalate (DBP) and the like are weighed, a certain mass of solvent acetonitrile is added into a clean and dry distillation flask with a plug, and the mass percentage concentration of each component is calculated (the standard service life is within one month).
3) Sample processing
0.6g of the sample was weighed into a clean and dry 1.5mL autosampler vial, and 0.75mL of the internal standard was added accurately and silanized in an oven at 65 ℃ for 15 min.
4) Analytical testing
And (4) placing the automatic sample injection bottle on an automatic sample injector, calling a test method, and analyzing and testing according to set chromatographic conditions (the quantitative method is the percentage of the internal standard).
5) Chromatographic Condition setting
Sample inlet temperature: 280 ℃; the split ratio is as follows: 70: 1; temperature programming mode: keeping the temperature at 40 ℃ for 3min, heating to 110 ℃ at the speed of 70 ℃/min, keeping the temperature for 0.5min, heating to 210 ℃ at the speed of 20 ℃/min, and heating to 240 ℃ at the speed of 55 ℃/min; carrier gas (hydrogen) pressure: 31.7 kPa; sample introduction amount: 1.5. mu.L.
Detector temperature: 300 ℃; air flow rate: 300 mL/min; tail blow (nitrogen) flow: 28mL/min, gas (hydrogen) flow: 30 mL/min.
6) The test of the preparation standard was performed under the same conditions.
7) The content of each impurity component was calculated by chemical workstation software.
2. And (3) measuring the color number of the maleic anhydride at 65 ℃ and the high temperature of 140 ℃ for 2 hours.
Platinum-cobalt colorimetric liquids with different color numbers are prepared according to the national standard GB/T3143-82 of maleic anhydride. Pouring the refined maleic anhydride liquid into a 50ml colorimetric tube, comparing with a standard platinum-cobalt color scale colorimetric solution, observing the color scale according to the national standard GB/T3143-82, putting the liquid maleic anhydride in the colorimetric tube and the colorimetric tube into a constant-temperature heating furnace, wherein the constant-temperature heating furnace meets the requirements of GB/T3676-2008, setting the temperature at 140 ℃, taking out the colorimetric tube after 2 hours, observing the heated color scale, and observing the color scale according to the national standard GB/T3143-82.
Example 1-1.
In the prior art device for producing maleic anhydride by butane oxidation, maleic anhydride is produced by butane oxidation, and is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 1, the crude anhydride is heated to 120 ℃ by a crude anhydride tank heat exchanger (11), the retention time is 4 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride enters a light component tower (3), the tower pressure is 18Kpa (absolute pressure), the tower top temperature is 139 ℃, the tower bottom is 143 ℃, the flow of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and returning to a stripping tower top condenser (8) of a light component tower top tank (6) is 3:1, the tower top pressure of a refining tower is 16Kpa (absolute pressure), the tower top temperature is 136 ℃, the tower bottom temperature is 141 ℃, the ratio of liquid returning to the refining tower and returning to the light component tower (3) of the refining tower top tank (7) is 30:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.1t/h, and the analysis is carried out by the analysis method to obtain the following components:
table 1 shows the contents of the maleic anhydride products
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (p)pm) | Citraconic anhydride | Purity (wt%) |
| 0 | 2 | 75 | 38 | 99.98 |
Table 2 shows the melting and high temperature color numbers of the maleic anhydride products at different storage times
Examples 1 to 2.
In the prior art device for maleic anhydride by 11.7 ten thousand ton butane oxidation method, maleic anhydride is produced by butane oxidation, the maleic anhydride is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 1, the retention time is 5 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), crude anhydride is heated to 130 ℃ by a heat exchanger (11), the crude anhydride enters a light component tower (3), the tower pressure is 19Kpa (absolute pressure), the tower top temperature is 141 ℃, the tower bottom is 145 ℃, the flow rate of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and returning to a stripping tower top condenser (8) of a light component tower top tank (6) is 2.7:1, the tower top pressure of a refining tower is 17Kpa (absolute pressure), the tower top temperature is 137.7 ℃, the tower bottom temperature is 142 ℃, the ratio of the liquid returning to the refining tower and returning to the light component tower (3) of the refining tower top tank (7) is 28:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.3t/h, and the analysis is carried out by the analysis method to obtain the following components:
table 3 shows the contents of the maleic anhydride products
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride | Purity (wt%) |
| 0 | 4 | 145 | 50 | 99.98 |
Table 4 shows the melting and high temperature color numbers of the maleic anhydride products at different storage times
Examples 1 to 3
In the prior art device for maleic anhydride by 11.7 ten thousand ton butane oxidation method, maleic anhydride is produced by butane oxidation, crude maleic anhydride is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 1, the crude anhydride is heated to 140 ℃ by a crude anhydride tank heat exchanger (11), the retention time is 6 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride enters a light component tower (3), the tower pressure is 20Kpa (absolute), the tower top temperature is 142.6 ℃, the tower bottom temperature is 146.5 ℃, the flow of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and a condenser returning to the stripping tower top is 2.5:1, the pressure of a refining tower is 18Kpa (absolute), the tower top temperature is 139.2 ℃, the tower bottom temperature is 142.5 ℃, the ratio of liquid returning to the refining tower and returning to the light component tower (3) of a refining tower top tank (7) is 23:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.5t/h, and the analysis is carried out by the analysis method to obtain the following components:
table 5 shows the contents of the maleic anhydride products
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride (ppm) | Purity (wt%) |
| 0 | 5 | 156 | 38 | 99.98 |
Table 6 shows the melting and high temperature color numbers of the maleic anhydride products at different storage times
Example 2-1.
In the prior art device for producing maleic anhydride by butane oxidation, maleic anhydride is produced by butane oxidation, and is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 2, the crude anhydride is heated to 120 ℃ by a crude anhydride tank heat exchanger (11), the retention time is 4 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride enters a light component tower (3), the tower pressure is 18Kpa (absolute pressure), the tower top temperature is 139 ℃, the tower bottom is 143 ℃, the flow of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and a returning condensing tank (16) of a light component tower top tank (6) is 3:1, the tower top pressure of a refining tower is 16Kpa (absolute pressure), the tower top temperature is 136 ℃, the tower bottom temperature is 141 ℃, the ratio of liquid returning to the refining tower and returning to the light component tower (3) of the refining tower top tank (7) of the refining tower top to the light component tower (3) is 30:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.1t/h, and the analysis is carried out by the analysis method to obtain the following components:
table 7 shows the contents of the maleic anhydride products
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride | Purity (wt%) |
| 0 | 5 | 145 | 50 | 99.98 |
Table 8 shows the melting and high temperature color numbers of the maleic anhydride products at different storage times
Example 2-2.
In the prior art device for maleic anhydride by 11.7 ten thousand ton butane oxidation method, maleic anhydride is produced by butane oxidation, the maleic anhydride is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 2, the retention time is 5 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride is heated to 130 ℃ by a crude anhydride tank heat exchanger (11), the crude anhydride enters a light component tower (3), the tower pressure is 19Kpa (absolute), the tower top temperature is 141 ℃, the tower bottom is 145 ℃, the flow rate of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and returning to a condensing tank (16) of a light component tower top tank (6) is 2.7:1, the tower top pressure of a refining tower is 17Kpa (absolute), the tower top temperature is 137.7 ℃, the tower bottom temperature is 142 ℃, the ratio of the liquid returning to the refining tower and returning to the light component tower (3) of the refining tower top tank (7) is 28:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.3t/h, and the analysis is carried out by the analysis method to obtain the following components:
table 9 shows the contents of the maleic anhydride products
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride | Purity (wt%) |
| 0 | 2 | 145 | 50 | 99.98 |
TABLE 10 melting and high temperature color numbers of maleic anhydride products at different storage times
Examples 2 to 3
In the prior art device for maleic anhydride by 11.7 ten thousand ton butane oxidation method, maleic anhydride is produced by butane oxidation, crude maleic anhydride is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 2, crude anhydride is heated to 140 ℃ by a crude anhydride tank heat exchanger (11), the retention time is 6 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride enters a light component tower (3), the tower pressure is 20Kpa (absolute), the tower top temperature is 142.6 ℃, the tower bottom temperature is 146.5 ℃, the flow of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and a returning condensing tank (16) of the light component tower top tank (6) is 2.5:1, the refining tower top pressure is 18Kpa (absolute), the tower top temperature is 139.2 ℃, the tower bottom temperature is 142.5 ℃, the ratio of liquid returning to the refining tower and returning to the light component tower (3) of a refining tower top tank (7) is 23:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.5t/h, and the analysis is carried out by the analysis method to obtain the following components:
TABLE 11 substance content in maleic anhydride product
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride (ppm) | Purity (wt%) |
| 0 | 4 | 146 | 45 | 99.98 |
TABLE 12 melting and high temperature color numbers of maleic anhydride products at different storage times
Example 3-1.
In the prior art device for producing maleic anhydride by butane oxidation, maleic anhydride is produced by butane oxidation, and is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 3, the crude anhydride is heated to 120 ℃ by a heat exchanger (11), the retention time is 4 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride enters a light component tower (3), the tower pressure is 18Kpa (absolute pressure), the tower top temperature is 139 ℃, the tower bottom is 143 ℃, the flow of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and a returning flash tank (17) of the light component tower top tank (6) is 3:1, the tower top pressure of a refining tower is 16Kpa (absolute pressure), the tower top temperature is 136 ℃, the tower bottom temperature is 141 ℃, the ratio of liquid returning to the refining tower and the returning flash tank (17) of the refining tower top tank (7) is 30:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.1t/h, and the analysis is carried out by the analysis method to obtain the following components:
table 13 shows the contents of the maleic anhydride products
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride | Purity (wt%) |
| 0 | 0 | 55 | 35 | 99.99 |
TABLE 14 melting and high temperature color numbers of maleic anhydride products at different storage times
Example 3-2.
In the prior art device for maleic anhydride by 11.7 ten thousand ton butane oxidation method, maleic anhydride is produced by butane oxidation, the maleic anhydride is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 3, the retention time is 5 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), crude anhydride is heated to 130 ℃ by a heat exchanger (11), the crude anhydride enters a light component tower (3), the tower pressure is 19Kpa (absolute pressure), the tower top temperature is 141 ℃, the tower bottom temperature is 145 ℃, the flow rate of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and returning to a flash tank (17) of the light component tower top tank (6) is 2.7:1, the top pressure of a refining tower is 17Kpa (absolute pressure), the tower top temperature is 137.7 ℃, the tower bottom temperature is 142 ℃, the ratio of the liquid returning to the refining tower top tank (7) to the refining tower and returning to the flash tank (17) is 28:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.3t/h, and the analysis is carried out by the analysis method to obtain the following components:
TABLE 15 substances content in maleic anhydride product
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride | Purity (wt%) |
| 0 | 2 | 55 | 40 | 99.99 |
TABLE 16 melting and high temperature color numbers of maleic anhydride products at different storage times
Examples 3 to 3.
In the prior art device for maleic anhydride by 11.7 ten thousand ton butane oxidation method, maleic anhydride is produced by butane oxidation, crude maleic anhydride is absorbed by dibutyl phthalate, crude maleic anhydride is desorbed by a stripping tower after absorption, as shown in figure 3, the crude anhydride is heated to 140 ℃ by a crude anhydride tank heat exchanger (11), the retention time is 6 hours (the retention time is controlled by controlling the liquid level of a crude anhydride tank), the crude anhydride enters a light component tower (3), the tower pressure is 20Kpa (absolute), the tower top temperature is 142.6 ℃, the tower bottom temperature is 146.5 ℃, the flow of the crude anhydride entering the light component tower (3) is 15t/h, the ratio of liquid returning to the light component tower and returning to a flash tank (17) of the light component tower top tank (6) is 2.5:1, the top pressure of a refining tower is 18Kpa (absolute), the tower top temperature is 139.2 ℃, the tower bottom temperature is 142.5 ℃, the ratio of liquid returning to the refining tower top tank (7) and returning to the flash tank (17) is 23:1, the amount of the tower bottom returned to the rich solvent tank (1) through a pipeline is 0.5t/h, and the analysis is carried out by the analysis method to obtain the following components:
TABLE 17 substances content in maleic anhydride product
| Acetic acid (ppm) | Acrylic acid (ppm) | Maleic acid (ppm) | Citraconic anhydride (ppm) | Purity (wt%)) |
| 0 | 1 | 156 | 38 | 99.98 |
TABLE 18 melting and high temperature color numbers of maleic anhydride products at different storage times
Comparative example
In a prior art apparatus for maleic anhydride by butane oxidation method, maleic anhydride is produced by butane oxidation, and is absorbed by dibutyl phthalate, and crude maleic anhydride is desorbed by a stripping tower after absorption, for example, maleic anhydride in a crude anhydride tank (E) shown in fig. 3, and the crude anhydride is analyzed by the foregoing analysis method to obtain:
table 1 shows the contents of the maleic anhydride products
Table 2 shows the melting and high temperature color numbers of the maleic anhydride products at different storage times
Claims (8)
1. A double-tower continuous rectification method for a maleic anhydride refining process is characterized by comprising the following steps: the device for realizing the method comprises a stripping tower (2), a light component tower (3), a refining tower (4) and a crude anhydride tank (5), wherein the stripping tower (2) is sequentially connected with a stripping tower top condenser (8) and a condensing tank (16) through a pipeline a; the output end of the crude anhydride tank (5) is connected with the middle part of the light component tower (3) through a pipeline b,
the bottom end of the light component tower (3) is connected with the middle part of the refining tower (4), the top end of the light component tower (3) is connected with a light component tower top tank (6), one output end of the bottom of the light component tower top tank (6) is connected with a pipeline a through a pipeline c, and the other output end of the bottom of the light component tower top tank is connected with the upper part of the light component tower (3) through a pipeline d;
the top of the refining tower (4) is connected with a refining tower top tank (7), one output end of the bottom of the refining tower top tank (7) is connected with the upper part of the refining tower (4) through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a pipeline b through a pipeline f;
the output end at the bottom of the refining tower (4) is connected with the middle part of the stripping tower (2) through a rich solvent tank (1);
the method for realizing double-tower continuous rectification by utilizing the device is that crude maleic anhydride in a crude anhydride tank (5) is heated to 80-180 ℃ through a heat exchanger (11), the crude maleic anhydride enters a light component tower (3) to remove low boiling point substances under the vacuum condition, materials at the bottom of the light component tower enter a refining tower (4), a maleic anhydride product is output after heat exchange through a product maleic anhydride condenser (13), and heavy components at the bottom of the tower return to a rich solvent tank (1); wherein the crude anhydride in the crude anhydride tank (5) is heated to 140 ℃ through a crude anhydride tank heat exchanger (11), circulated back to the crude anhydride tank (5), and fed into the light component tower (3) after circulating for 4-6 hours;
the ratio of the flow through the line d to the flow through the line c is from 3:1 to 1: 1; the flow ratio of the pipeline e to the pipeline f is 30:1-20: 1; the bottom temperature of the light component tower (3) is 140-150 ℃, and the top temperature of the light component tower is 135-145 ℃; the temperature of the bottom of the refining tower is 140-145 ℃, and the temperature of the top of the refining tower is 135-138 ℃; the absolute pressure in the light component tower (3) is 18-23 KPa; the absolute pressure in the refining column is 16-18 KPa.
2. A double-tower continuous rectification method for a maleic anhydride refining process is characterized by comprising the following steps: the device for realizing the method comprises a stripping tower (2), a light component tower (3), a refining tower (4) and a crude anhydride tank (5), wherein the stripping tower (2) is sequentially connected with a stripping tower top condenser (8) and a condensing tank (16) through a pipeline a; the output end of the crude anhydride tank (5) is connected with the middle part of the light component tower (3) through a pipeline b,
the bottom end of the light component tower (3) is connected with the middle part of the refining tower (4), the top end of the light component tower (3) is connected with a light component tower top tank (6), one output end of the bottom of the light component tower top tank (6) is connected with a condensing tank (16) through a pipeline c, and the other output end of the light component tower (3) is connected with the upper part of the light component tower (3) through a pipeline d;
the top of the refining tower (4) is connected with a refining tower top tank (7), one output end of the bottom of the refining tower top tank (7) is connected with the upper part of the refining tower (4) through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a pipeline b through a pipeline f;
the output end at the bottom of the refining tower (4) is connected with the middle part of the stripping tower (2) through a rich solvent tank (1);
the method for realizing double-tower continuous rectification by utilizing the device is that crude maleic anhydride in a crude anhydride tank (5) is heated to 80-180 ℃ through a heat exchanger (11), the crude maleic anhydride enters a light component tower (3) to remove low boiling point substances under the vacuum condition, materials at the bottom of the light component tower enter a refining tower (4), a maleic anhydride product is output after heat exchange through a product maleic anhydride condenser (13), and heavy components at the bottom of the tower return to a rich solvent tank (1); wherein the crude anhydride in the crude anhydride tank (5) is heated to 140 ℃ through a crude anhydride tank heat exchanger (11), circulated back to the crude anhydride tank (5), and fed into the light component tower (3) after circulating for 4-6 hours;
the ratio of the flow through the line d to the flow through the line c is from 3:1 to 1: 1; the flow ratio of the pipeline e to the pipeline f is 30:1-20: 1; the bottom temperature of the light component tower (3) is 140-150 ℃, and the top temperature of the light component tower is 135-145 ℃; the temperature of the bottom of the refining tower is 140-145 ℃, and the temperature of the top of the refining tower is 135-138 ℃; the absolute pressure in the light component tower (3) is 18-23 KPa; the absolute pressure in the refining column is 16-18 KPa.
3. A double-tower continuous rectification method for a maleic anhydride refining process is characterized by comprising the following steps: the device for realizing the method comprises a stripping tower (2), a light component tower (3), a refining tower (4) and a crude anhydride tank (5), wherein the stripping tower (2) is sequentially connected with a stripping tower top condenser (8) and a condensing tank (16) through a pipeline a; the output end of the crude anhydride tank (5) is connected with the middle part of the light component tower (3) through a pipeline b, and the output end of the bottom of the flash tank (17) is connected with the crude anhydride tank (5);
the bottom end of the light component tower (3) is connected with the middle part of the refining tower (4), the top end of the light component tower (3) is connected with a light component tower top tank (6), one output end of the bottom of the light component tower top tank (6) is connected with a flash tank (17) through a pipeline c, and the other output end of the light component tower (3) is connected with the upper part of the light component tower (3) through a pipeline d;
the top of the refining tower (4) is connected with a refining tower top tank (7), one output end of the bottom of the refining tower top tank (7) is connected with the upper part of the refining tower (4) through a pipeline e, and the other output end of the bottom of the refining tower top tank is connected with a flash tank (17) through a pipeline f;
the output end at the bottom of the refining tower (4) is connected with the middle part of the stripping tower (2) through a rich solvent tank (1);
the method for realizing double-tower continuous rectification by utilizing the device is that crude maleic anhydride in a crude anhydride tank (5) is heated to 80-180 ℃ through a heat exchanger (11), the crude maleic anhydride enters a light component tower (3) to remove low boiling point substances under the vacuum condition, materials at the bottom of the light component tower enter a refining tower (4), a maleic anhydride product is output after heat exchange through a product maleic anhydride condenser (13), and heavy components at the bottom of the tower return to a rich solvent tank (1); wherein the crude anhydride in the crude anhydride tank (5) is heated to 140 ℃ through a crude anhydride tank heat exchanger (11), circulated back to the crude anhydride tank (5), and fed into the light component tower (3) after circulating for 4-6 hours;
the ratio of the flow through the line d to the flow through the line c is from 3:1 to 1: 1; the flow ratio of the pipeline e to the pipeline f is 30:1-20: 1; the bottom temperature of the light component tower (3) is 140-150 ℃, and the top temperature of the light component tower is 135-145 ℃; the temperature of the bottom of the refining tower is 140-145 ℃, and the temperature of the top of the refining tower is 135-138 ℃; the absolute pressure in the light component tower (3) is 18-23 KPa; the absolute pressure in the refining column is 16-18 KPa.
4. The method for the double-tower continuous rectification of the maleic anhydride refining process according to any one of claims 1 to 3, wherein: the light component tower (3) is connected with a light component tower top tank (6) through a light component tower top condenser (9).
5. The method for the double-tower continuous rectification of the maleic anhydride refining process according to any one of claims 1 to 3, wherein: the top of the refining tower (4) is connected with a refining tower top tank (7) through a refining tower top condenser (10).
6. The method for the double-tower continuous rectification of the maleic anhydride refining process according to any one of claims 1 to 3, wherein: the bottom of the refining tower (4) is connected with the lower part of the refining tower (4) through a heat exchanger (15).
7. The method for the double-tower continuous rectification of the maleic anhydride refining process according to any one of claims 1 to 3, wherein: the middle part of the refining tower (4) is connected with a maleic anhydride heat exchanger (13).
8. The method for the double-tower continuous rectification of the maleic anhydride refining process according to any one of claims 1 to 3, wherein: the top output ends of the light component tower top tank (6) and the refining tower top tank (7) are connected with a vacuum system (12); the stripper overhead condenser (8) is connected to a stripper vacuum system (14).
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