A separation system and method for oxidation liquid of cyclohexane catalytic oxidation process

Abstract

A separation system for oxidation liquid of cyclohexane catalytic oxidation method, wherein the feed port of a flash tank is connected to an oxidation liquid source, the top outlet feeds the flash tower and an overflow port is provided to feed the separator tank, the bottom outlet of the flash tank feeds the rectification tower, the light phase outlet of the separator tank feeds the extraction washing tower, and the heavy phase outlet feeds the rectification tower, the top of the extraction washing tower is provided with a water source inlet, the bottom outlet feeds the flash tank, and the top outlet feeds the rectification tower, the bottom outlet of the flash tower feeds the flash tank, a small rectification tower is provided at the bottom of the rectification tower, the bottom outlet of the rectification tower feeds the small rectification tower, the bottom outlet of the small rectification tower feeds the decomposition reactor, the decomposition reactor is provided with a catalyst inlet, and the decomposition reactor discharges alcohol ketone dibasic acid esters. The present invention can effectively avoid system blockage and ensure long-term normal operation of the system on the basis of separating the oxidation liquid prepared by cyclohexane catalytic oxidation method with low energy consumption and high yield.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a separation system and method for oxidation liquid of cyclohexane catalytic oxidation process. Background Art

[0002] Cyclohexane oxidation is the main method used in the production of adipic acid in the world. The world's major adipic acid manufacturers, including DuPont, Monsanto and Rhodia in France, all use this process technology. The main advantages of cyclohexane oxidation are mature technology, complete localization of catalysts and chemicals, high product yield and purity, but the process is complicated and requires a large amount of nitric acid. At present, there are two oxidation process routes for cyclohexane liquid phase oxidation in industrial production, one is a non-catalytic oxidation process and the other is a catalytic oxidation process. The catalytic oxidation process mainly uses cobalt salts, boric acid or metaboric acid as catalysts, and oxygen and cyclohexane react under the action of cobalt salt catalysts.

[0003] At present, the oxidizing liquid prepared by the cyclohexane catalytic oxidation method is usually separated and purified through the processes of oxidizing liquid decomposition system, waste alkali liquid separation system, waste alkali liquid flash tower system, alkane distillation system (five towers), and alcohol ketone refining (three towers). The overall energy consumption of the system is high, the yield of separated alcohol ketone dibasic acid esters is not ideal, and it is easy to cause blockage of the separation system.

[0004] Therefore, how to separate the oxidation liquid prepared by the cyclohexane catalytic oxidation method with low energy consumption and high yield is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] One of the purposes of the present invention is to provide a separation system for oxidation liquid prepared by cyclohexane catalytic oxidation method in view of the deficiencies in the prior art. On the basis of low energy consumption and high yield separation of oxidation liquid prepared by cyclohexane catalytic oxidation method, the system can be effectively prevented from being blocked and the normal operation of the system can be ensured for a long time.

[0006] The second purpose of the present invention is to use the above-mentioned separation system to separate the oxidizing liquid, which has low energy consumption and high yield and can effectively meet the actual needs of enterprises.

[0007] The technical scheme for achieving one of the purposes of the present invention is: a separation system for oxidation liquid of cyclohexane catalytic oxidation method, comprising a flash tank, a separator tank, an extraction washing tower, a flash tower, a distillation tower, and a decomposition reactor, wherein the feed port of the flash tank is connected to the oxidation liquid source, the top outlet of the flash tank feeds the flash tower, the flash tank is provided with an overflow port to feed the separator tank, the bottom outlet of the flash tank feeds the distillation tower, the light phase outlet of the separator tank feeds the extraction washing tower, the heavy phase outlet of the separator tank feeds the distillation tower, the top of the extraction washing tower is provided with a water source inlet, the bottom outlet of the extraction washing tower feeds the flash tank, the top outlet of the extraction washing tower feeds the distillation tower, the top outlet of the flash tower is condensed, The device is connected to the first reflux tank, the light phase outlet of the first reflux tank refluxes to the flash tower and discharges cyclohexane, the heavy phase outlet of the first reflux tank feeds the flash tank, and the bottom outlet of the flash tower feeds the flash tank. A small distillation tower is arranged at the bottom of the distillation tower, the bottom outlet of the distillation tower feeds the small distillation tower, and the bottom outlet of the small distillation tower feeds the decomposition reactor. The top outlet of the distillation tower is connected to the second reflux tank through a condenser, the light phase outlet of the second reflux tank sends cyclohexane to the outside and feeds the reflux port of the first distillation tower, the heavy phase outlet of the second reflux tank is connected to the water source inlet of the extraction washing tower, the decomposition reactor is provided with a catalyst inlet, and the decomposition reactor discharges alcohol ketone dibasic acid ester to the outside.

[0008] The top outlet of the separator tank supplies materials to the flash tower.

[0009] The water source inlet is also connected to a desalted water source.

[0010] The light phase outlet of the separatory tank is self-circulated and partially extracted to feed the extraction and washing tower, the light phase outlet of the first reflux tank is self-circulated and partially refluxed to the flash tower and the cyclohexane is discharged, the heavy phase outlet of the first reflux tank is self-circulated and partially extracted to feed the flash tank, the light phase outlet of the second reflux tank is self-circulated and partially refluxed to the distillation tower and the cyclohexane is discharged, and the heavy phase outlet of the second reflux tank is self-circulated and partially extracted to feed the water source inlet of the extraction and washing tower.

[0011] The decomposition reactor comprises a first decomposition reactor and a second decomposition reactor which are connected in series in sequence. The catalyst inlet is arranged on the first decomposition reactor. The material of the first decomposition reactor is sent to the second decomposition reactor through overflow. The bottom of the second decomposition reactor is provided with a discharge port which refluxes to the first decomposition reactor and the second decomposition reactor and discharges the alcohol ketone dibasic acid ester.

[0012] The technical solution for achieving the second object of the present invention is: a method for separating cyclohexane catalytic oxidation oxidized liquid using any of the above separation systems, comprising the following steps:

[0013] 1) The oxidized liquid obtained by the cyclohexane catalytic oxidation method is sent to a flash tank, and the gas phase obtained by flash evaporation enters a flash tower. The temperature of the oxidized liquid is 140-145°C, the oil phase in the flash tank overflows into a separator tank, and the water phase in the flash tank is sent to a distillation tower;

[0014] 2) The oil phase in the separator is separated into layers, the light phase is sent to the extraction and washing tower, and the heavy phase is sent to the distillation tower;

[0015] 3) The light phase entering the extraction and washing tower is extracted with water sent into the extraction and washing tower, the oil phase obtained by extraction is sent to the distillation tower, and the water phase obtained by extraction is sent to the flash tank;

[0016] 4) The gas phase entering the flash tower transfers mass and heat with the reflux liquid at the top. The gas phase at the top of the tower is condensed and sent to the first reflux tank for separation. The light phase refluxes to the flash tower and is partially discharged, and the heavy phase is sent to the flash tank;

[0017] 5) Control the alkane content of the distillation tower, circulate the bottom liquid and send it to the small distillation tower, condense the top gas phase and send it to the second reflux tank, separate the layers, reflux the light phase to the distillation tower and partially discharge it, and send the heavy phase to the extraction washing tower;

[0018] 6) Control the alkane content of the small distillation tower, and circulate the bottom liquid of the tower and send it to the decomposition reactor;

[0019] 7) The catalyst is cobalt acetate, the temperature is controlled to be 90-95°C for the reaction, and the alcohol-ketone dibasic acid ester is discharged from the bottom of the decomposition reactor.

[0020] Preferably, the temperature of the layering in step 2) is 75-85° C. and the time is 10-20 minutes.

[0021] Preferably, the extraction temperature in step 3) is 70-80° C., the extraction time is 40-50 minutes, and the ratio of the light phase to water entering the extraction washing tower is 100:5.

[0022] Preferably, in step 4), the layering temperature is 70-75°C, the time is 5-15 minutes, and the reflux ratio is 1:2; in step 5), the alkane content is controlled to be less than 10wt%, the layering temperature is 80-90°C, the time is 15-25 minutes, and the reflux ratio is 1:5.

[0023] Preferably, in step 6), the alkane content is controlled to be less than 200 ppm, and in step 7), the catalyst is added in a ratio of 2:1000000.

[0024] The above technical solution has the following beneficial effects:

[0025] 1. The present invention first flashes the oxidation liquid for the first time, separates most of the cyclohexane and water, and sends them to a flash tower for a second flash, so that as much cyclohexane as possible is discharged in the form of gas phase and recycled after condensation and stratification. The heavy phase obtained by the flash tank, flash tower and condensation and stratification is an aqueous phase (acid water) containing alcohol ketone dibasic acid esters, which is sent to a distillation system for separation, making full use of the heat of the oxidation liquid itself for preliminary separation and reducing energy consumption.

[0026] 2. The device of the present invention is provided with a water source inlet in the extraction washing tower, which is used to extract and wash the high-concentration oil phase (mainly alkanol ketone dibasic acid esters), and wash the dibasic acid esters therein into the water phase, so as to prevent the dibasic acid esters in the oil phase from being carried into the packing layer of the distillation tower and clogging the packing, thereby ensuring the operation effect of the distillation tower.

[0027] 3. The device of the present invention sets a small distillation tower at the bottom of the distillation tower, and uses the distillation tower to feed the small distillation tower. Under the premise of ensuring the separation of cyclohexane and alcohol ketone dibasic acid ester, the energy consumption of the distillation tower can be effectively reduced. The specific principle is: the tower body of the distillation tower forms a large tower, and the alkane-water azeotropic distillation separates most of the cyclohexane and water; the unseparated alcohol ketone ester and alkane-water mixture is sent to the small distillation tower, and the secondary azeotropic distillation is carried out in the small space of the small distillation tower to obtain the target product alcohol ketone dibasic acid ester, and the energy consumption is relatively small. The distillation tower and the small distillation tower each have a reboiler that heats up with steam to provide heat for the distillation system, and the distillation tower and the small distillation tower share a set of condensation system, which minimizes the steam consumption and achieves energy saving effect.

[0028] Further description is given below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the connection of the flash tank, the liquid separator, the extraction washing tower and the flash tower of the present invention;

[0030] Figure 2 It is a connection schematic diagram of the distillation tower of the present invention;

[0031] Figure 3 It is a connection schematic diagram of the decomposition reactor of the present invention.

[0032] In the accompanying drawings, 1 is a flash tank, 2 is a separatory tank, 3 is an extraction washing tower, 31 is a water source inlet, 4 is a flash tower, 5 is a distillation tower, 6 is a decomposition reactor, 61 is a first decomposition reactor, 62 is a second decomposition reactor, 63 is a catalyst inlet, 7 is a first reflux tank, 8 is a small distillation tower, and 9 is a second reflux tank. DETAILED DESCRIPTION

[0033] Example 1

[0034] See also Figure 1-3The separation system of the oxidation liquid of cyclohexane catalytic oxidation method includes a flash tank 1, a separator tank 2, an extraction washing tower 3, a flash tower 4, a distillation tower 5, and a decomposition reactor 6. The feed port of the flash tank 1 is connected to the oxidation liquid source. Usually, a buffer tank needs to be set upstream of the feed port. The top outlet of the flash tank 1 supplies the flash tower 4, and the feed interface is located at the lower part of the side wall of the flash tower. The flash tank 1 is provided with an overflow port to supply the separator tank 2, and the bottom outlet of the flash tank 1 supplies the distillation tower 5, and the feed interface is located at the lower part of the side wall of the distillation tower. The light phase outlet of the separator tank 2 feeds the extraction washing tower 3, and the heavy phase outlet of the separator tank 2 feeds the distillation tower 5. In this embodiment, the top outlet of the separator tank 2 feeds the flash tower 4, that is, the gas phase material is directly sent to the flash tower, and the light phase outlet of the separator tank 2 is self-circulated and partially extracted to feed the extraction washing tower 3. Usually, a pump body and a valve body are arranged on the self-circulation pipeline, and the valve body is arranged downstream of the pump body, and a connecting pipeline is arranged between the pump body and the valve body to feed the extraction washing tower. A water source inlet 31 is arranged at the top of the extraction washing tower 3, and the bottom outlet of the extraction washing tower 3 feeds the flash tank 1, and the top outlet of the extraction washing tower 3 feeds the distillation tower 5. The top outlet of the flash tower 4 is connected to the first reflux tank 7 via a condenser, and the light phase outlet of the first reflux tank 7 refluxes to the flash tower and discharges cyclohexane. Specifically, the light phase outlet of the first reflux tank 7 self-circulates and partially refluxes to the flash tower 4 and discharges cyclohexane. The heavy phase outlet of the first reflux tank 7 feeds the flash tank 1. Specifically, the heavy phase outlet of the first reflux tank 7 self-circulates and self-circulates and partially withdraws to feed the flash tank 1. The bottom outlet of the flash tower 4 feeds the flash tank 1. A small rectifying tower 8 is arranged at the bottom of the rectifying tower 5, and the bottom outlet of the rectifying tower 5 feeds the small rectifying tower 8, and the bottom outlet of the small rectifying tower 8 feeds the decomposition reactor 6. Specifically, the rectifying tower and the small rectifying tower are respectively equipped with reboilers, and the top of the small rectifying tower is connected to the bottom of the rectifying tower, that is, the rectifying tower and the small rectifying tower share a set of condensers. The top outlet of the distillation tower 5 is connected to the second reflux tank 9 through a condenser. The light phase outlet of the second reflux tank 9 sends out cyclohexane and supplies material to the reflux port of the distillation tower. The heavy phase outlet of the second reflux tank 9 is connected to the water source inlet 31 of the extraction washing tower 3. Specifically, the light phase outlet of the second reflux tank 9 self-circulates and partially refluxes to the distillation tower 5 and discharges cyclohexane. The heavy phase outlet of the second reflux tank 9 self-circulates and partially extracts and supplies material to the water source inlet 31 of the extraction washing tower 3. Usually, the water source inlet of the extraction washing tower is also connected to the desalted water source. Through two-way water supply, the stable water supply to the extraction washing tower is guaranteed.The decomposition reactor 6 is provided with a catalyst inlet 63, and the decomposition reactor 6 discharges alcohol ketone dibasic acid ester. In this embodiment, the decomposition reactor 6 includes a first decomposition reactor 61 and a second decomposition reactor 62 which are connected in series in sequence. The catalyst inlet 63 is provided on the first decomposition reactor 61. The material of the first decomposition reactor 61 is sent to the second decomposition reactor 62 through overflow. The bottom of the second decomposition reactor 62 is provided with a discharge port, which refluxes to the first decomposition reactor 61 and the second decomposition reactor 62, and discharges alcohol ketone dibasic acid ester.

[0035] Example 2

[0036] The method for separating cyclohexane catalytic oxidation oxidizing liquid using the separation system of Example 1 comprises the steps of:

[0037] 1) Oxidation liquid (acid: 0.1%, ester: 0.8%, alcohol: 1.3%, ketone: 1.1%, alkane: 95.7%, the rest is impurities, temperature is 140-145℃) feed 150m 3 / h, desalted water enters the extraction washing tower (1.5m 3 / h, room temperature), and enters the flash tank from the middle to form a dibasic acid ester aqueous solution, which is separated in the flash tank, and the water phase enters the bottom of the distillation tower kettle from the bottom of the flash tank, with a flow rate of 12m 3 / h, the cyclohexane, water and a small amount of alcohol ketone flashed from the top of the flash tank enter the flash tower, and the unflashed oxidized liquid enters the separator tank through overflow, with a flow rate of 40m 3 / h, temperature 80℃, stratification 15min;

[0038] 2) The light phase separated in the separator is circulated and enters the extraction washing tower through a pressure pump with a flow rate of 10m 3 / h, adding 1.5m3 of desalted water flow 3 / h, countercurrent washing of the dibasic acid ester in the oxidation liquid, the acid water returns to the flash tank, and the heavy phase separated in the separator tank is sent to the distillation tower;

[0039] 3) The washed oxidizing liquid enters the middle and upper part of the distillation tower. Under steam heating, the tower bottom temperature rises to 83-85°C and the pressure is -30KPa. The gas phase extracted from the top of the tower is condensed and sent to the second reflux tank. After stratification, the temperature is 85°C and the time is 20min. 90% of the separated light phase (cyclohexane) is separated and recycled. The separated heavy phase (water) is circulated and supplemented to the extraction washing tower. The tower bottom liquid is pumped to the small distillation tower for further separation. The tower bottom temperature of the small distillation tower rises to 90-93°C. The tower bottom of the small distillation tower obtains an alcohol ketone dibasic acid ester containing alkane <0.002%, a moisture content of 20%, and a flow rate of 7.5m 3 / h;

[0040] 4) After the gas phase entering the flash tower and the reflux liquid transfer mass and heat, it is condensed and sent to the first reflux tank. After stratification, the temperature is 72°C and the time is 10 minutes. The separated light phase (cyclohexane) refluxes the flash tower and is partially withdrawn. The separated heavy phase (water) is circulated and supplemented to the extraction washing tower;

[0041] 5) The alcohol-ketone dibasic acid ester obtained by the small distillation tower is sent to the first decomposition reactor, and 2 kg of cobalt acetate is added as a catalyst. The temperature is controlled to 90-95 ° C for reaction, and the alcohol-ketone dibasic acid ester is discharged at the bottom of the second decomposition reactor. After testing, the acid: 0.16%, ester: 9.32%, peroxide: 0.17%, alcohol: 45%, ketone: 38%, alkane: 0.002%, and others: 7.3%.

Claims

1. A separation system for cyclohexane catalytic oxidation oxidizing liquid, characterized in that: It comprises a flash tank (1), a liquid separation tank (2), an extraction washing tower (3), a flash tower (4), a distillation tower (5), and a decomposition reactor (6). The feed inlet of the flash tank (1) is connected to an oxidizing liquid source, the top outlet of the flash tank (1) supplies the flash tower (4), the flash tank (1) is provided with an overflow port to supply the liquid separator (2), and the bottom outlet of the flash tank (1) supplies the distillation tower (5). The light phase outlet of the separator tank (2) supplies material to the extraction washing tower (3), and the heavy phase outlet of the separator tank (2) supplies material to the distillation tower (5). A water source inlet (31) is arranged at the top of the extraction and washing tower (3), the bottom outlet of the extraction and washing tower (3) supplies materials to the flash tank (1), and the top outlet of the extraction and washing tower (3) supplies materials to the distillation tower (5). The top outlet of the flash tower (4) is connected to the first reflux tank (7) via a condenser, the light phase outlet of the first reflux tank (7) refluxes to the flash tower and discharges cyclohexane, the heavy phase outlet of the first reflux tank (7) supplies the flash tank (1), and the bottom outlet of the flash tower (4) supplies the flash tank (1). A small distillation tower (8) is arranged at the bottom of the distillation tower (5); the bottom outlet of the distillation tower (5) supplies the small distillation tower (8); the bottom outlet of the small distillation tower (8) supplies the decomposition reactor (6); the top outlet of the distillation tower (5) is connected to a second reflux tank (9) via a condenser; the light phase outlet of the second reflux tank (9) delivers cyclohexane to the outside and supplies the reflux port of the distillation tower; the heavy phase outlet of the second reflux tank (9) is connected to a water source inlet (31) of an extraction washing tower (3); The decomposition reactor (6) is provided with a catalyst inlet (63), and the decomposition reactor (6) discharges alcohol, ketone, dibasic acid, and ester to the outside.

2. The separation system of cyclohexane catalytic oxidation oxidizing liquid according to claim 1, characterized in that: The top outlet of the liquid separator (2) supplies material to the flash tower (4).

3. The separation system of cyclohexane catalytic oxidation oxidizing liquid according to claim 1, characterized in that: The water source inlet (31) is also connected to a desalted water source.

4. The separation system of cyclohexane catalytic oxidation oxidizing liquid according to claim 1, characterized in that: The light phase outlet of the liquid separation tank (2) is self-circulated and partially withdrawn to feed the extraction and washing tower (3); the light phase outlet of the first reflux tank (7) is self-circulated and partially refluxed to the flash tower (4) and discharged to the cyclohexane; the heavy phase outlet of the first reflux tank (7) is self-circulated and partially withdrawn to feed the flash tank (1); the light phase outlet of the second reflux tank (9) is self-circulated and partially refluxed to the distillation tower (5) and discharged to the cyclohexane; the heavy phase outlet of the second reflux tank (9) is self-circulated and partially withdrawn to feed the water source inlet (31) of the extraction and washing tower (3).

5. The separation system of cyclohexane catalytic oxidation oxidizing liquid according to claim 1, characterized in that: The decomposition reactor (6) comprises a first decomposition reactor (61) and a second decomposition reactor (62) which are connected in series in sequence. The catalyst inlet (63) is arranged on the first decomposition reactor (61). The material of the first decomposition reactor (61) is sent to the second decomposition reactor (62) through overflow. The bottom of the second decomposition reactor (62) is provided with a discharge port, which flows back to the first decomposition reactor (61) and the second decomposition reactor (62), and discharges alcohol, ketone, dibasic acid and ester.

6. A method for separating oxidation liquid from cyclohexane catalytic oxidation process using any separation system according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) The oxidized liquid obtained by cyclohexane catalytic oxidation is sent to the flash tank, and the gas phase obtained by flash evaporation enters the flash tower. The temperature of the oxidized liquid is 140-145°C. The oil phase in the flash tank overflows into the separator tank, and the water phase in the flash tank is sent to the distillation tower; 2) The oil phase in the separator tank is separated into layers, the light phase is sent to the extraction and washing tower, and the heavy phase is sent to the distillation tower; 3) The light phase entering the extraction and washing tower is extracted with the water sent into the extraction and washing tower, the oil phase obtained by extraction is sent to the distillation tower, and the water phase obtained by extraction is sent to the flash tank; 4) The gas phase entering the flash tower transfers mass and heat with the reflux liquid at the top. The gas phase at the top of the tower is condensed and sent to the first reflux tank for stratification. The light phase refluxes to the flash tower and is partially discharged, and the heavy phase is sent to the flash tank; 5) Control the alkane content of the distillation tower, circulate the bottom liquid and send it to the small distillation tower, condense the top gas phase and send it to the second reflux tank, separate the layers, reflux the light phase to the distillation tower and partially discharge it, and send the heavy phase to the extraction washing tower; 6) Control the alkane content of the small distillation tower, and circulate the bottom liquid of the tower and send it to the decomposition reactor; 7) The catalyst is cobalt acetate, and the temperature is controlled to be 90-95°C for the reaction, and the bottom of the decomposition reactor discharges alcohol, ketone, dibasic acid and ester.

7. The method according to claim 6, characterized in that Step 2) The temperature of the layering is 75-85°C and the time is 10-20 minutes.

8. The method according to claim 6, characterized in that Step 3) The extraction temperature is 70-80°C, the extraction time is 40-50 minutes, and the ratio of the light phase to water entering the extraction washing tower is 100:

5.

9. The method according to claim 6, characterized in that Step 4) the layering temperature is 70-75°C, the time is 5-15 minutes, and the reflux ratio is 1:

2. Step 5) the alkane content is controlled to be less than 10wt%, the layering temperature is 80-90°C, the time is 15-25 minutes, and the reflux ratio is 1:

5.

10. The method according to claim 6, characterized in that Step 6) controlling the alkane content to be less than 200 ppm, and step 7) adding the catalyst in a ratio of 2:1000000.

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