Alkane-water azeotropic distillation system for separating alcohol ketonic acid ester

Abstract

A small rectifying tower is concentrically assembled at the bottom of a first rectifying tower, the upstream end of a first circulating pipeline is connected with the bottom of the first rectifying tower, the downstream end of the first circulating pipeline is connected with a distributor and located on the top of the small rectifying tower, and the upstream end of a second circulating pipeline is connected with the bottom of a second rectifying tower. The upstream end of the first return pipeline is connected with the top of the first rectifying tower through the condenser, the downstream end of the first return pipeline is connected with a return port of the first rectifying tower, the upstream end of the second return pipeline is connected with the top of the second rectifying tower through the condenser, and the downstream end of the second return pipeline is connected with a feed port of the second rectifying tower; a second discharging pipeline is arranged at the tower bottom of the small rectifying tower to supply materials to the second rectifying tower and is provided with a second valve. The device is simple in structure and low in maintenance cost, can effectively reduce the energy consumption for separating the alkanol ketone water azeotrope, and is relatively high in separation purity.

Description

Technical Field

[0001] The utility model relates to the field of chemical industry, in particular to an alkane-water azeotropic distillation system for separating alcohol ketoesters. Background Art

[0002] Cyclohexane oxidation is the main method used in the production of adipic acid in the world. 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] The oxidation liquid obtained by the cyclohexane oxidation method is a mixture containing acids, esters, alcohols, ketones, cyclohexane, and impurities, which needs to be separated and purified. Since the oxidation liquid prepared by the cyclohexane catalytic oxidation method contains alcohol ketoesters, cyclohexane, and water at the same time, it is necessary to use more distillation towers in series to separate the target product alcohol ketoesters, resulting in high purification energy consumption.

[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] The purpose of the present invention is to provide an azeotropic distillation system for separating alcohol keto acid esters, which has a simple structure and low maintenance cost, can effectively reduce the energy consumption of separating alkanol ketone water azeotropes, and has high separation purity.

[0006] The technical scheme for achieving the purpose of the present invention is: an azeotropic distillation system of alkanol ketone water, comprising a first distillation tower, a second distillation tower, a small distillation tower, a first circulation pipeline, a second circulation pipeline, a first reflux pipeline, and a second reflux pipeline, wherein the inner diameter of the tower bottom of the small distillation tower is smaller than the inner diameter of the tower bottom of the first distillation tower, the small distillation tower is concentrically assembled at the bottom of the first distillation tower, and the top of the small distillation tower extends into the first distillation tower, so that an annular space is formed between the small distillation tower and the first distillation tower, the first distillation tower, the second distillation tower, and the small distillation tower are sequentially provided with a first reboiler, a second reboiler, and a third reboiler, the upstream end of the first circulation pipeline is connected to the bottom of the first distillation tower and is lower than the top height of the small distillation tower, and the lower end of the first circulation pipeline is connected to the bottom of the first distillation tower and is lower than the top height of the small distillation tower. The upstream end is connected to a distributor and is located at the top of the small distillation tower. The upstream end of the second circulation pipeline is connected to the bottom of the second distillation tower, and the downstream end is connected to the lower part of the side wall of the second distillation tower. A first discharge pipeline is set to discharge the downstream process, and a first valve is set. The upstream end of the first reflux pipeline is connected to the top of the first distillation tower through a condenser, and the downstream end of the first reflux pipeline is connected to the reflux port of the first distillation tower, and a first production port is set. The upstream end of the second reflux pipeline is connected to the top of the second distillation tower through a condenser, and the downstream end of the second reflux pipeline is connected to the feed port of the second distillation tower, and a second production port is set. A second discharge pipeline is set at the bottom of the small distillation tower to supply the second distillation tower, and a second valve is set.

[0007] The first distillation tower, the second distillation tower and the small distillation tower are all packed towers.

[0008] A third discharge pipeline is arranged on the first circulation pipeline to supply materials to the second distillation tower, and a third valve is arranged on the first circulation pipeline.

[0009] A fourth discharge pipeline is arranged at the bottom of the small distillation tower to discharge materials to the downstream process, and a fourth valve is arranged.

[0010] A first reflux tank is arranged on the first reflux pipeline, which is located downstream of the corresponding condenser. The light phase of the first reflux tank is self-circulated, and part of the cyclohexane is extracted and refluxed, and part of it is discharged externally. The heavy phase of the first reflux tank is self-circulated, and part of it is extracted and discharged externally as acid water.

[0011] A second reflux tank is arranged on the second reflux pipeline, which is located downstream of the corresponding condenser. The heavy phase of the second reflux tank is self-circulated and part of it is extracted to feed the second distillation tower. The light phase of the second reflux tank is self-circulated and part of it is extracted to feed the first distillation tower.

[0012] The feed inlet of the first distillation tower is located in the middle and upper part of the first distillation tower, and the light phase extraction outlet of the second reflux tank is connected to the middle part of the first distillation tower.

[0013] The above technical solution has the following beneficial effects:

[0014] 1. The device of the present invention sets a small distillation tower at the bottom of the first distillation tower, and uses the first circulation pipeline and distributor to feed from the top of the small distillation tower. Under the premise of ensuring the separation of cyclohexane and alcohol ketone, the energy consumption of the distillation tower can be effectively reduced. The specific principle is: the tower body of the first distillation tower forms a large tower, and azeotropic distillation separates most of the cyclohexane and water; the unseparated alcohol ketone and alkane water mixture are sent to the small distillation tower, and secondary azeotropic distillation is carried out in the small space of the small distillation tower to obtain the target product alcohol keto acid ester, and the energy consumption is relatively small. The first distillation tower and the small distillation tower share a set of condensation system, which minimizes the steam consumption and achieves energy saving effect.

[0015] 2. The present invention extends the top of the small distillation tower through the first distillation tower and forms an annular space to prevent the bottom liquid in the first distillation tower from entering the small distillation tower by overflow, causing uneven distribution of the bottom liquid and thus affecting the distillation efficiency of the small distillation tower; feed is supplied from the top of the small distillation tower through the first circulation pipeline and the distributor, and a small amount is extracted to the second distillation tower at the same time to prevent the heavy components in the oxidized liquid in the bottom of the first distillation tower from crystallizing or depositing, adhering to the tower wall or the first reboiler tube wall, affecting the heat exchange efficiency, and greatly extending the operation cycle of the distillation system. Compared with the traditional distillation tower, the continuous operation cycle of the distillation system of the present patent application exceeds one year.

[0016] 3. The present invention provides a method of arranging reflux tanks on the first reflux pipeline and the second reflux pipeline respectively, and performing stratification, and separately treating the stratified light phase and heavy phase, which can not only ensure that the purity of the separated cyclohexane is greater than 99.5%, but also effectively improve the utilization rate of the materials. The applicant's experimental verification shows that the product recovery rate reaches 100%.

[0017] Further description is given below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a connection diagram of the utility model.

[0019] In the accompanying drawings, 1 is the first distillation tower, 2 is the second distillation tower, 3 is the small distillation tower, 4 is the first circulation pipeline, 5 is the second circulation pipeline, 6 is the first reflux pipeline, 7 is the second reflux pipeline, 8 is the annular space, 9 is the first reboiler, 10 is the second reboiler, 11 is the third reboiler, 12 is the first discharge pipeline, 13 is the first production outlet, 14 is the second production outlet, 15 is the second discharge pipeline, 16 is the third discharge pipeline, 17 is the fourth discharge pipeline, 18 is the first reflux tank, 19 is the second reflux tank, a is the first valve, b is the second valve, c is the third valve, and d is the fourth valve. DETAILED DESCRIPTION

[0020] Example 1

[0021] The azeotropic distillation system of alkane ketone water comprises a first distillation tower 1, a second distillation tower 2, a small distillation tower 3, a first circulation pipeline 4, a second circulation pipeline 5, a first reflux pipeline 6, and a second reflux pipeline 7, wherein the first distillation tower 1, the second distillation tower 2, and the small distillation tower 3 are all packed towers, and the feed port of the first distillation tower 1 is located in the middle and upper part of the first distillation tower, and is connected to the oxidation liquid source prepared by the cyclohexane catalytic oxidation method. The inner diameter of the tower bottom of the small distillation tower 3 is smaller than the inner diameter of the tower bottom of the first distillation tower 1, the small distillation tower 3 is concentrically assembled at the bottom of the first distillation tower 1, and the top of the small distillation tower 3 extends into the first distillation tower 1, so that an annular space 8 is formed between the small distillation tower 3 and the first distillation tower 1, and specifically, the top of the small distillation tower is open, and the diameter is the same as the inner diameter of the small distillation tower, so that the tower bottom of the small distillation tower is straight. The first distillation tower 1, the second distillation tower 2, and the small distillation tower 3 are sequentially provided with a first reboiler 9, a second reboiler 10, and a third reboiler 11, and each reboiler is installed and connected according to the conventional setting method in the chemical industry. The upstream end of the first circulation pipeline 4 is connected to the bottom of the first distillation tower 1 and is lower than the top height of the small distillation tower 3. The downstream end of the first circulation pipeline 4 is connected to a distributor and is located at the top of the small distillation tower 3. Obviously, a circulation pump is provided on the first circulation pipeline. In this embodiment, a third discharge pipeline 16 is provided on the first circulation pipeline 4 to feed the second distillation tower 2, and a third valve c is provided. The third discharge pipeline 16 is connected to the first circulation pipeline and is located downstream of the corresponding circulation pump. The downstream end of the third discharge pipeline is connected to the top feed port of the second distillation tower. The upstream end of the second circulation pipeline 5 is connected to the bottom of the second distillation tower 2, and the downstream end is connected to the lower part of the side wall of the second distillation tower 2, and a first discharge pipeline 12 is set to discharge the downstream process, and a first valve a is set. Usually, the downstream process is a decomposition process. The upstream end of the first reflux pipeline 6 is connected to the top of the first distillation tower 1 through a condenser, and the downstream end of the first reflux pipeline 6 is connected to the reflux port of the first distillation tower 1, and a first production port 13 is set. In this embodiment, a first reflux tank 18 is set on the first reflux pipeline 6, which is located downstream of the corresponding condenser. The light phase of the first reflux tank 18 is self-circulated, and part of the cyclohexane is produced and refluxed, and part of the cyclohexane is produced and discharged externally. The heavy phase of the first reflux tank 18 is self-circulated, and part of the acid water is produced and discharged externally. The upstream end of the second reflux pipeline 7 is connected to the top of the second distillation tower 2 through a condenser, and the downstream end of the second reflux pipeline 7 is connected to the top feed port of the second distillation tower 2, and a second production port 14 is provided. In this embodiment, a second reflux tank 19 is provided on the second reflux pipeline 7, which is located downstream of the corresponding condenser. The heavy phase of the second reflux tank 19 is self-circulated and partially produced to feed the second distillation tower 2, and the light phase of the second reflux tank 19 is self-circulated and partially produced to feed the first distillation tower 1. Specifically, the light phase production port of the second reflux tank 19 is connected to the middle part of the first distillation tower 1.A second discharge pipeline 15 is provided at the bottom of the small distillation tower 3 to supply the second distillation tower 2, and a second valve b is provided. In order to meet the actual needs of the enterprise, a fourth discharge pipeline 17 is also provided at the bottom of the small distillation tower 3 to discharge the downstream process, and a fourth valve d is provided.

[0022] Example 2

[0023] The method for separating the oxidizing liquid using the system of Example 1 comprises the following steps:

[0024] 1) The oxidation liquid (the weight ratio of the components is acid: 0.1%, ester: 0.8%, peroxide: 0.9%, alcohol: 1.3%, ketone: 1.1%, alkane: 95.7%, others: 0.1%, and the flow rate is 150 t / h) enters from the middle and upper part of the first distillation tower, and the temperature of the tower bottom is controlled to be 83-85°C and the pressure is -(28-31) kPa (the parameters can float within the range). The top gas phase of the first distillation tower is partially refluxed after condensation, and the reflux ratio is 0.26. The remainder is discharged to obtain cyclohexane, with a flow rate of 116 t / h, a purity of 99.3%, and a yield of 100%;

[0025] 2) The bottom liquid of the first distillation tower is fed into the top of the small distillation tower through the first circulation pipeline and the distributor, with a flow ratio of 0.9, and the bottom temperature of the small distillation tower is controlled to be 90-93°C;

[0026] 3) The bottom liquid of the small distillation tower and part of the bottom liquid extracted from the first circulation pipeline are sent to the second distillation tower and enter from the upper part of the second distillation tower. The bottom temperature is controlled to be 85-88°C and the pressure is -(48-52) kPa (the parameters can float within the range). After the top gas phase of the second distillation tower is condensed, the heavy phase enters from the upper part of the second distillation tower and the light phase enters from the middle part of the first distillation tower;

[0027] 4) The bottom liquid of the second distillation tower is discharged to obtain an alcohol ketoester product, whose component weight ratio is acid: 0.16%, ester: 9.32%, peroxide: 0.17%, alcohol: 45%, ketone: 38%, alkane: 0.002%, and others: 7.3%.

[0028] The applicant's industrial application verification shows that the continuous operation period of the distillation system of Example 1 of the present invention exceeds one year. Compared with the traditional distillation system, the energy consumption is reduced by 15% and the operation period is extended by more than 6 months.

Claims

1. An azeotropic distillation system for separating alcohol ketoesters, characterized in that: The invention comprises a first distillation tower (1), a second distillation tower (2), a small distillation tower (3), a first circulation pipeline (4), a second circulation pipeline (5), a first reflux pipeline (6), and a second reflux pipeline (7). The inner diameter of the bottom of the small distillation tower (3) is smaller than the inner diameter of the bottom of the first distillation tower (1); the small distillation tower (3) is concentrically mounted at the bottom of the first distillation tower (1), and the top of the small distillation tower (3) extends into the first distillation tower (1), so that an annular space (8) is formed between the small distillation tower (3) and the first distillation tower (1). The first distillation tower (1), the second distillation tower (2), and the small distillation tower (3) are provided with a first reboiler (9), a second reboiler (10), and a third reboiler (11) in sequence. The upstream end of the first circulation pipeline (4) is connected to the bottom of the first distillation tower (1) and is lower than the top of the small distillation tower (3). The downstream end of the first circulation pipeline (4) is connected to a distributor and is located at the top of the small distillation tower (3). The upstream end of the second circulation pipeline (5) is connected to the bottom of the second distillation tower (2), and the downstream end is connected to the lower part of the side wall of the second distillation tower (2). A first discharge pipeline (12) is provided to discharge the downstream process, and a first valve (a) is provided. The upstream end of the first reflux pipeline (6) is connected to the top of the first distillation tower (1) through a condenser, the downstream end of the first reflux pipeline (6) is connected to the reflux port of the first distillation tower (1), and a first production port (13) is provided, the upstream end of the second reflux pipeline (7) is connected to the top of the second distillation tower (2) through a condenser, the downstream end of the second reflux pipeline (7) is connected to the feed port of the second distillation tower (2), and a second production port (14) is provided, A second discharge pipeline (15) is provided at the bottom of the small distillation tower (3) to supply materials to the second distillation tower (2), and a second valve (b) is also provided.

2. The azeotropic distillation system for separating alcohol ketoesters according to claim 1, characterized in that: The first distillation tower (1), the second distillation tower (2) and the small distillation tower (3) are all packed towers.

3. The azeotropic distillation system for separating alcohol ketoesters according to claim 1, characterized in that: A third discharge pipeline (16) is provided on the first circulation pipeline (4) to supply materials to the second distillation tower (2), and a third valve (c) is also provided.

4. The azeotropic distillation system for separating alcohol ketoesters according to claim 1, characterized in that: A fourth discharge pipeline (17) is provided at the bottom of the small distillation tower (3) to discharge materials to the downstream process, and a fourth valve (d) is provided.

5. The azeotropic distillation system for separating alcohol ketoesters according to claim 1, characterized in that: A first reflux tank (18) is provided on the first reflux pipeline (6) and is located downstream of the corresponding condenser. The light phase of the first reflux tank (18) is self-circulated, and part of the cyclohexane is extracted and refluxed, and part of it is extracted and discharged to the outside. The heavy phase of the first reflux tank (18) is self-circulated, and part of it is extracted and discharged to the outside for acid water.

6. The azeotropic distillation system for separating alcohol ketoesters according to claim 1, characterized in that: A second reflux tank (19) is provided on the second reflux pipeline (7) and is located downstream of the corresponding condenser. The heavy phase of the second reflux tank (19) is self-circulated and partly extracted to supply the second distillation tower (2). The light phase of the second reflux tank (19) is self-circulated and partly extracted to supply the first distillation tower (1).

7. The azeotropic distillation system for separating alcohol ketoesters according to claim 6, characterized in that: The feed inlet of the first distillation tower (1) is located in the middle and upper part of the first distillation tower, and the light phase extraction outlet of the second reflux tank (19) is connected to the middle part of the first distillation tower (1).

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