Tower top distillate ethanol purification system

Abstract

The utility model belongs to the technical field of purification, and relates to a tower top distillate ethanol purification system which comprises a tower top distillate storage tank, a material transfer pump and an ethanol recovery tower which are communicated in sequence, the side wall of the ethanol recovery tower is externally connected with an alcohol ester discharge pipe, a side extraction pipe and a blow-down pipe respectively; the blow-down pipe, the side extraction pipe and the alcohol ester discharge pipe are distributed from top to bottom; a check valve is arranged between the transfer pump and the ethanol recovery tower; and a first control valve and a third control valve are sequentially arranged between the check valve and the ethanol recovery tower. According to the utility model, tower top distillate is introduced into the ethanol recovery tower for secondary rectification through the material transfer pump, so that the recovery waste is avoided, and the recovery rate of an ethanol product is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of purification, and relates to an overhead distillate ethanol purification system, which is used for purifying overhead distillate of an ethanol dehydrogenation tower. Background Art

[0002] Ethanol purification is to remove impurities and improve the purity of ethanol, so that it can be used in a wider range of applications; the principle of ethanol extraction is to use ethanol as a solvent to separate and purify substances by utilizing its solubility.

[0003] In the existing ethanol purification, the permeation vaporization membrane section is to use the permeation vaporization membrane technology to break the azeotropic process of ethanol and water in the crude ethanol with a water content within the range of 15%, and separate the water in the raw material and ethanol and methanol from the raw material side of the membrane to the permeation side. The crude ethanol dehydration steam with a water content of ≤0.5wt% on the raw material side of the membrane directly enters the middle of the ethanol light removal tower in the form of saturated gas without condensation. The ethanol light removal tower adopts normal pressure continuous operation, and the reboiler heats and vaporizes the material. The methanol vapor containing a small amount of ethanol and DMC is extracted from the top of the ethanol light removal tower, and is condensed and refluxed before being transported to the middle of the ethanol light removal tower. After cooling, part of it flows back to the top of the ethanol removal tower, and part of the top distillate enters the temporary storage tank. After accumulating to a certain amount, it is transported to the mixed alcohol ester tank; the ethanol removal tower extracts ethanol product steam that meets the requirements from the side line, exchanges heat with the membrane system ethanol raw material in the preheater, condenses through the side line condenser and cools through the side line cooler, and then enters the ethanol product temporary storage tank. After passing the inspection, it is transported to the ethanol tank in the intermediate tank area; the bottom of the ethanol removal tower discharges the tower bottom waste liquid containing a small amount of ethylene glycol into the tower bottom waste liquid temporary storage tank by gravity self-flow, and after accumulating to a certain amount, it is transported to the mixed alcohol ester tank.

[0004] However, in the existing purification, in order to ensure that the quality purity of the purified anhydrous ethanol product is 99.5%, it is necessary to increase the extraction of impurities from the top of the ethanol de-lightness tower and the bottom of the ethanol de-lightness tower. The distillate extracted from the top of the ethanol de-lightness tower is about 2 tons / day, and the ethanol content in the distillate is about 60%. However, the top distillate is directly discharged into the mixed alcohol ester tank, resulting in extraction waste and low ethanol product recovery rate. Utility Model Content

[0005] In order to solve the technical problems that the distillate from the top of the existing ethanol light removal tower is directly discharged, resulting in waste of production and low recovery rate of ethanol products, the utility model provides an ethanol purification system.

[0006] In the utility model, the distillate from the top of the tower is led to the ethanol recovery tower for secondary distillation through a material transfer pump, thereby avoiding extraction waste and improving the recovery rate of the ethanol product.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0008] A tower top distillate ethanol purification system comprises a tower top distillate storage tank, a material transfer pump and an ethanol recovery tower which are connected in sequence; the side walls of the ethanol recovery tower are also externally connected with an alcohol ester discharge pipe, a side extraction pipe and a vent pipe; the vent pipe, the side extraction pipe and the alcohol ester discharge pipe are distributed from top to bottom.

[0009] It is further defined that a check valve is provided between the transfer pump and the ethanol recovery tower.

[0010] It is further defined that a first control valve and a third control valve are sequentially arranged between the check valve and the ethanol recovery tower.

[0011] It is further defined that the overhead distillate ethanol purification system also includes a heat exchanger, the top of the heat exchanger is connected to the tower side of the ethanol recovery tower, and the bottom of the heat exchanger is connected to the bottom of the ethanol recovery tower.

[0012] It is further defined that the heat exchanger is also externally connected to a steam inlet pipe and a steam outlet pipe communicating with the steam inlet pipe.

[0013] It is further defined that the overhead distillate ethanol purification system also includes a cooler and a methanol discharge pipe; one end of the cooler is connected to the ethanol recovery tower, and the other end of the cooler is respectively connected to the tower side of the ethanol recovery tower and the methanol discharge pipe; the ethanol recovery tower is connected to the vent pipe via the cooler.

[0014] It is further defined that the overhead distillate ethanol purification system also includes a reflux tank and a reflux pump; the cooler is connected to the ethanol recovery tower side, the methanol discharge pipe and the vent pipe respectively through the reflux tank and the reflux pump.

[0015] It is further defined that a side production pump is provided on the side production pipe, and a discharge pump is provided on the alcohol ester discharge pipe.

[0016] The beneficial effects of the utility model are:

[0017] 1. In the utility model, the distillate from the top of the tower is led to the ethanol recovery tower through a transfer pump for further distillation and purification. After distillation and purification, a plurality of fractions containing different components are obtained, which are respectively transported to each recovery tank through a vent pipe, a side extraction pipe and an alcohol ester discharge pipe, so as to realize component reuse, avoid waste of extracted distillate and improve the recovery rate of ethanol product.

[0018] 2. In the utility model, by arranging the check valve, the first control valve and the third control valve, it is convenient to control the flow rate of the top distillate flowing into the ethanol recovery tower, and at the same time, the check valve is used to prevent the top distillate from flowing back, which is easy to operate.

[0019] 3. In the utility model, a heat exchanger is provided, and the top of the heat exchanger is connected to the side of the ethanol recovery tower, and the bottom of the heat exchanger is connected to the bottom of the ethanol recovery tower, so that a circulation loop is formed, which is convenient for heating and refluxing the heavy components at the bottom of the ethanol recovery tower, thereby improving the distillation and purification efficiency in the ethanol recovery tower; further, a steam inlet pipe and a steam outlet pipe connected to the steam inlet pipe are externally connected to the heat exchanger, and 1.0MPa steam is used to heat the heavy components, saving electricity resource consumption. At the same time, the 1.0MPa steam comes from the ethanol production pipeline network, thereby realizing the reuse of steam heat.

[0020] 4. In the utility model, a cooler is provided to cool the light components discharged from the top of the ethanol recovery tower, and the recovered components are transported to the outside of the system from the methanol discharge pipe to avoid the methanol components being discharged along with the light components, so that the components after distillation and purification are fully recovered. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of an ethanol purification system provided by the utility model;

[0022] in:

[0023] 1-tower top distillate storage tank; 101-tower top distillate inlet pipe; 2-transfer pump; 3-check valve; 4-first control valve; 5-second control valve; 6-third control valve; 7-ethanol recovery tower; 701-distillate inlet; 702-tower top gas outlet; 703-side sampling port; 704-condensate return port; 705-alcohol ester discharge port; 706-tower bottom outlet; 707-tower side return port; 8-heat exchanger; 9-steam inlet pipe; 10-steam outlet pipe; 11-cooler; 12-reflux tank; 13-reflux pump; 14-alcohol ester discharge pipe; 15-discharge pump; 16-side sampling pipe; 17-side sampling pump; 18-vent pipe; 19-methanol discharge pipe. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0025] Example 1

[0026] See also Figure 1 The overhead distillate ethanol purification system provided in this embodiment includes an overhead distillate storage tank 1, a material transfer pump 2 and an ethanol recovery tower 7 which are connected in sequence; the side walls of the ethanol recovery tower 7 are also externally connected with an alcohol ester discharge pipe 14, a side extraction pipe 16 and a vent pipe 18; the vent pipe 18, the side extraction pipe 16 and the alcohol ester discharge pipe 14 are distributed from top to bottom.

[0027] Specifically, the ethanol recovery tower 7 is provided with a distillate inlet 701, a tower top gas outlet 702, a side sampling port 703 and an alcohol ester discharge port 705. The distillate inlet 701 is located at the middle of the tower side of the ethanol recovery tower 7. The tower top distillate storage tank 1 is connected to the distillate inlet 701 through a transfer pump 2, so as to facilitate the delivery of the tower top distillate (with an ethanol content of 60%) produced by the ethanol dehydrogenation tower to the ethanol recovery tower 7 for rectification and purification. The tower top gas outlet 702 is located at the top of the ethanol recovery tower 7, and the tower top gas outlet 702 is externally connected to the tower top gas outlet 702. The vent pipe 18 is convenient for discharging and venting the light components produced in the distillation and purification process; the side sampling port 703 is located between the distillate inlet 701 and the tower top gas outlet 702 and close to the tower top position, and the side sampling port 703 is connected to the side extraction pipe 16, and the components extracted from the side of the ethanol recovery tower 7 are discharged and transported to the ethanol dehydrogenation tower for purification; the alcohol ester discharge port 705 is located below the distillate inlet 701, and the alcohol ester discharge port 705 is connected to the alcohol ester discharge pipe 14, which is convenient for transporting the alcohol ester mixed components produced by distillation and purification to the alcohol ester tank for storage. By setting up a plurality of fractions containing different components obtained by distillation and purification, they can be transported to each processing section respectively, so as to achieve component reuse, avoid waste of extracted distillate, and improve the recovery rate of ethanol products.

[0028] In order to facilitate the delivery of the top distillate to the ethanol recovery tower 7, a check valve 3 is arranged between the transfer pump 2 and the ethanol recovery tower 7, and a first control valve 4 and a third control valve 6 are arranged in sequence between the check valve 3 and the ethanol recovery tower 7.

[0029] In this embodiment, a branch is also connected to the pipeline for transporting the top distillate to the ethanol recovery tower 7. The branch is located between the first control valve 4 and the third control valve 6. A second control valve 5 is also provided on the branch. This branch leads to the alcohol ester tank as a backup.

[0030] In this embodiment, a side sampling pump 17 is provided on the side sampling pipe 16, and the delivery flow rate of the side sampling components inside the ethanol recovery tower 7 is controlled by the side sampling pump 17; a discharge pump 15 is provided on the alcohol ester discharge pipe 14, and the delivery flow rate of the alcohol ester components inside the ethanol recovery tower 7 is controlled by the discharge pump 15.

[0031] Example 2

[0032] See also Figure 1 On the basis of Example 1, the overhead distillate ethanol purification system provided in this embodiment further includes a heat exchanger 8, the top of the heat exchanger 8 is connected to the tower side of the ethanol recovery tower 7, and the bottom of the heat exchanger 8 is connected to the bottom of the ethanol recovery tower 7.

[0033] Preferably, the heat exchanger 8 is also externally connected with a steam inlet pipe 9 and a steam outlet pipe 10 connected to the steam inlet pipe 9. Steam of 1.0 MPa is introduced into the steam inlet pipe 9. Since the heat exchanger 8 is a shell-and-tube or shell-and-tube structure, the steam and the material (heavy components from the bottom of the ethanol recovery tower 7) in the heat exchanger 8 are respectively passed through different shell-and-tube channels, and the material is heated by steam. The heated material is then returned to the middle of the ethanol recovery tower 7 for further distillation and purification. During implementation, the 1.0 MPa steam is generated by the steam network in the ethanol production system. It is heated by steam to achieve heat reuse, without the need for electric heating, thus saving electricity and reducing consumption.

[0034] Preferably, a bottom outlet 706 and a tower side return port 707 are respectively provided on the ethanol recovery tower 7; the bottom outlet 706 is located at the bottom of the ethanol recovery tower 7, and the tower side return port 707 is located between the distillate inlet 701 and the alcohol ester discharge port 705. The heat exchanger 8 is placed in parallel with the ethanol recovery tower 7, and the top end of the heat exchanger 8 is connected to the tower side return port 707, and the bottom end of the heat exchanger 8 is connected to the bottom outlet 706. In this way, the bottom outlet 706 is connected to the bottom outlet 706 through the heat exchanger 8 to form a circulation loop.

[0035] In this embodiment, the overhead distillate ethanol purification system also includes a cooler 11 and a methanol discharge pipe 19; one end of the cooler 11 is connected to the ethanol recovery tower 7, and the other end of the cooler 11 is respectively connected to the tower side of the ethanol recovery tower 7 and the methanol discharge pipe 19; the ethanol recovery tower 7 is connected to the vent pipe 18 via the cooler 11.

[0036] Preferably, a condensate return port 704 is also provided on the ethanol recovery tower 7, and the condensate return port 704 is located between the distillate inlet 701 and the side sampling port 703, and is close to the side sampling port 703. The cooler 11 is connected to the tower side of the ethanol recovery tower 7 through the condensate return port 704.

[0037] Specifically, the structure of the cooler 11 is a shell and tube type or a tube-in-tube type. The ethanol recovery tower 7 is connected to one end of the cooler 11 through the top gas outlet 702. The light components on the top of the tower enter the cooler 11. At the same time, circulating water is introduced into the cooler 11 to cool the light components on the top of the tower. The light components on the top of the tower and the circulating water go through different shell and tube channels. After the light components on the top of the tower are cooled, condensate and gaseous light components are obtained. The gaseous light components are discharged and emptied through the vent pipe 18. The condensate is divided into two paths. One path returns to the ethanol recovery tower 7 from the tower side through the condensate return port 704, and the other path is discharged into the methanol tank through the methanol discharge pipe 19 for storage and reuse.

[0038] In this embodiment, the overhead distillate ethanol purification system further includes a reflux tank 12 and a reflux pump 13; the cooler 11 is connected to the tower side of the ethanol recovery tower 7, the methanol discharge pipe 19 and the vent pipe 18 respectively through the reflux tank 12 and the reflux pump 13.

[0039] Specifically, the condensate cooled by the cooler 11 enters the reflux tank 12 for further cooling and separation, and the separated light components are passed into the vent pipe 18 for venting; after the condensate is separated again, it passes through the reflux pump 13, one way is returned to the ethanol recovery tower 7 from the tower side of the ethanol recovery tower 7 through the condensate return port 704 to further recover ethanol, and the other way is discharged to the methanol tank through the methanol discharge pipe 19 for storage and reuse, thereby improving the separation effect of the light components on the top of the tower.

[0040] To sum up, in the utility model, the distillate (i.e., ethanol mixture) produced from the top of the ethanol lightness removal tower is sent to the ethanol recovery tower through a transfer pump, and is subjected to secondary distillation to separate water, methanol and ethanol through the ethanol lightness removal tower; and then returned to the ethanol purification system through a side sampling pipe, so as to recover more ethanol, avoid the waste of ethanol in the produced distillate, and improve the ethanol recovery rate and purity.

[0041] The above description is only an embodiment of the present invention, and does not limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A tower overhead distillate ethanol purification system, characterized in that: The invention comprises a tower top distillate storage tank (1), a material transfer pump (2) and an ethanol recovery tower (7) which are connected in sequence; the side walls of the ethanol recovery tower (7) are also externally connected with an alcohol ester discharge pipe (14), a side extraction pipe (16) and a vent pipe (18); the vent pipe (18), the side extraction pipe (16) and the alcohol ester discharge pipe (14) are distributed from top to bottom.

2. The overhead distillate ethanol purification system according to claim 1, characterized in that: A check valve (3) is provided between the material transfer pump (2) and the ethanol recovery tower (7).

3. The overhead distillate ethanol purification system according to claim 2, characterized in that: A first control valve (4) and a third control valve (6) are arranged in sequence between the check valve (3) and the ethanol recovery tower (7).

4. The overhead distillate ethanol purification system according to any one of claims 1 to 3, characterized in that: The overhead distillate ethanol purification system further comprises a heat exchanger (8), the top of the heat exchanger (8) being connected to the tower side of the ethanol recovery tower (7), and the bottom of the heat exchanger (8) being connected to the bottom of the ethanol recovery tower (7).

5. The overhead distillate ethanol purification system according to claim 4, characterized in that: The heat exchanger (8) is also externally connected to a steam inlet pipe (9) and a steam outlet pipe (10) communicated with the steam inlet pipe (9).

6. The overhead distillate ethanol purification system according to claim 4, characterized in that: The overhead distillate ethanol purification system further comprises a cooler (11) and a methanol discharge pipe (19); one end of the cooler (11) is connected to the ethanol recovery tower (7), and the other end of the cooler (11) is respectively connected to the tower side of the ethanol recovery tower (7) and the methanol discharge pipe (19); the ethanol recovery tower (7) is connected to the vent pipe (18) via the cooler (11).

7. The overhead distillate ethanol purification system according to claim 6, characterized in that: The overhead distillate ethanol purification system further comprises a reflux tank (12) and a reflux pump (13); the cooler (11) is connected to the tower side of the ethanol recovery tower (7), the methanol discharge pipe (19) and the vent pipe (18) respectively via the reflux tank (12) and the reflux pump (13).

8. The overhead distillate ethanol purification system according to claim 1, characterized in that: The side extraction pipe (16) is provided with a side extraction pump (17), and the alcohol ester discharge pipe (14) is provided with a discharge pump (15).

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