Apparatus and method for removing diethyl acetal from ethanol

Abstract

The present application relates to a kind of devices and refining methods for removing acetal in ethanol, device includes the light tower (2) of removal, acetal removal tower (3) and refining tower (4) connected in sequence by pipeline, the light tower (2) of removal is used to separate out light component in the system to be separated, the acetal removal tower (3) is used to separate out acetal, ethyl ester in the system to be separated, the refining tower (4) is used to separate out ethanol rectification and purify in the system to be separated.Compared with prior art, the present application is developed by special acetal removal tower, acetal is removed by using the method of negative pressure rectification, so that its content is reduced to 150ppm below, meet the quality requirements of high-purity ethanol.

Description

Technical Field

[0001] This invention relates to the field of ethanol production, and in particular to an apparatus and purification method for removing acetal from ethanol. Background Technology

[0002] Ethanol is an important basic chemical raw material, widely used in industries such as acetic acid, beverages, fragrances, dyes, and fuels. It also has extensive applications in defense, medical and health, organic synthesis, food processing, and industrial and agricultural production. With the rapid development of light industry, food, pharmaceuticals, and chemicals, the consumption of ethanol as an industrial solvent is constantly increasing, leading to a rapid rise in demand.

[0003] High-purity ethanol has wide applications in electronic chemicals, batteries, and pharmaceuticals. Developing efficient production technologies for high-purity ethanol is crucial, but challenges such as impurity contamination and vapor entrainment make it difficult to achieve separation and purification through a single operation. The key to purification lies in controlling the water content and the levels of byproducts such as methanol, ethyl acetate, and acetal.

[0004] The most difficult impurity to remove is acetal, which forms an azeotrope with ethanol and exists in the ethanol, affecting product quality. Currently, high-purity ethanol on the market generally requires an acetal content of below 150 ppm. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and purification method for removing acetal from ethanol, thereby addressing the problem of excessively high acetal content in ethanol. This invention utilizes a dedicated acetal removal tower and a negative pressure distillation method to remove acetal, reducing its content to below 150 ppm, thus meeting the quality requirements for high-purity ethanol.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An apparatus for removing acetal from ethanol includes a light acetal removal tower, an acetal removal tower, and a purification tower connected in sequence by pipelines.

[0008] The light component removal tower is used to separate the light components from the system to be separated.

[0009] The formaldehyde removal tower is used to separate acetal and ethyl ester from the system to be separated.

[0010] The purification tower is used to purify and separate the ethanol in the system to be separated by distillation.

[0011] Furthermore, the apparatus also includes a low-pressure fractionated ethanol storage tank, which is connected to the light-duty removal tower via a pipeline, and the connected pipeline is equipped with a raw material side delivery pump.

[0012] Furthermore, the light component removal column is a light component removal distillation column, used to separate the light components from the system to be separated;

[0013] The aldehyde removal tower is an acetal removal distillation tower, used to separate acetal and ethyl ester from the system to be separated;

[0014] The purification tower is an ethanol purification tower, used to purify and separate the ethanol in the system to be separated by distillation.

[0015] Furthermore, the top of the light-weight removal tower is equipped with a light-weight removal tower top condenser and a light-weight removal tower top reflux tank. The inlet of the light-weight removal tower top condenser is connected to the top of the light-weight removal tower through a pipe, the outlet of the light-weight removal tower top condenser is connected to the inlet of the light-weight removal tower top reflux tank through a pipe, the liquid phase outlet of the light-weight removal tower top reflux tank is connected to the reflux port of the light-weight removal tower through a pipe, and the light-weight removal tower top reflux tank is also equipped with a sampling outlet.

[0016] Furthermore, the pipeline connecting the liquid phase outlet of the light-light ...

[0017] Furthermore, the bottom of the light-light removal tower is connected to the side feed inlet of the aldehyde removal tower via a pipeline, and a bottom pump for the light-light removal tower is installed on the connected pipeline.

[0018] Furthermore, the top of the formaldehyde removal tower is equipped with a formaldehyde removal tower top condenser and a formaldehyde removal tower top reflux tank. The inlet of the formaldehyde removal tower top condenser is connected to the top of the formaldehyde removal tower through a pipe, and the outlet of the formaldehyde removal tower top condenser is connected to the inlet of the formaldehyde removal tower top reflux tank through a pipe. One liquid phase outlet of the formaldehyde removal tower top reflux tank is connected to the reflux port of the formaldehyde removal tower through a pipe. The other liquid phase outlet of the formaldehyde removal tower top reflux tank is equipped with a negative pressure protection tank. The inlet of the negative pressure protection tank is connected to the other liquid phase outlet of the formaldehyde removal tower top reflux tank through a pipe. The outlet of the negative pressure protection tank is connected to an external negative pressure device through a pipe. The formaldehyde removal tower top reflux tank is also equipped with a sampling outlet.

[0019] Furthermore, the pipeline connecting the liquid outlet of the formaldehyde removal tower top reflux tank to the reflux port of the formaldehyde removal tower is equipped with a formaldehyde removal tower top reflux pump, which is used to control the reflux of the top liquid.

[0020] Furthermore, the bottom of the formaldehyde removal tower is connected to the side feed inlet of the refining tower via a pipeline, and a formaldehyde removal tower pump is installed on the connected pipeline.

[0021] Furthermore, the refining column is equipped with a refining column top condenser and a refining column top reflux tank at its top. The inlet of the refining column top condenser is connected to the top of the refining column via a pipe, and the outlet of the refining column top condenser is connected to the inlet of the refining column top reflux tank via a pipe. One liquid phase outlet of the refining column top reflux tank is connected to the reflux port of the refining column via a pipe, and the other liquid phase outlet of the refining column top reflux tank is equipped with a molecular sieve dehydration device. The inlet of the molecular sieve dehydration device is connected to the other liquid phase outlet of the refining column top reflux tank via a pipe, and a refining column reflux tank collection pump is installed on the connected pipe. The outlet of the molecular sieve dehydration device is connected to a finished product collection tank via a pipe, and the finished product collection tank has a collection outlet.

[0022] The purification tower top condenser is used to condense the gas at the top of the purification tower, and the purification tower top reflux tank is used to store the ethanol produced by the purification tower.

[0023] Furthermore, a recirculation pump is installed on the pipeline connecting the liquid phase outlet of the recirculation tank at the top of the refining tower to the reflux port of the refining tower.

[0024] Furthermore, the condenser at the top of the refining tower is a total condenser.

[0025] Furthermore, the device also includes a refining collection tank, the bottom of the refining tower is connected to the side inlet of the refining collection tank via a pipe, a refining tower bottom pump is installed on the connected pipe, and the refining collection tank is provided with a sampling outlet.

[0026] Furthermore, the present invention also provides a purification method for removing acetal from ethanol, which uses the above-mentioned apparatus for removing acetal from ethanol, and the specific steps are as follows:

[0027] S1. The low-pressure fractionated ethanol in the low-pressure fractionated ethanol storage tank is separated by a light-light-removal tower to obtain top gas A and bottom liquid A.

[0028] S2. The bottom liquid A obtained in step S1 is transported into the formaldehyde removal tower by the bottom pump of the light light removal tower to separate the top gas B and the bottom liquid B.

[0029] S3. The bottom liquid B obtained in step S2 is transported into the purification tower by the action of the dealdehyde tower ground pump. The purification tower distills and purifies the ethanol in the bottom liquid B to obtain the overhead gas C and the bottom liquid C.

[0030] S4. The overhead gas C obtained in step S3 is condensed into liquid substance C by the overhead condenser of the refining column. Liquid substance C enters the refining column reflux tank for separation. A portion of liquid substance C is pumped out of the refining column reflux tank and enters the molecular sieve dehydration equipment. After dehydration, the ethanol liquid phase is entered into the finished product collection tank for storage.

[0031] Furthermore, in step S1, the overhead gas A mainly contains light components such as methanol and diethyl ether.

[0032] Further, in step S1, the top gas A is condensed into liquid substance A by the top condenser of the light-light-removal tower. Liquid substance A enters the top reflux tank of the light-light-removal tower for separation. A portion of liquid substance A is returned to the top of the light-light-removal tower by the top reflux pump of the light-light-removal tower, and the other portion of liquid substance A is extracted.

[0033] Furthermore, in step S1, the low-pressure fractionated ethanol is industrial-grade ethanol obtained by low-pressure separation of ethanol produced by hydrogenation of ethyl acetate.

[0034] Furthermore, in step S1, the top temperature of the light-weight removal tower is 55-65℃, preferably 60-63℃;

[0035] The bottom temperature of the light-weight removal tower is 50-77℃, preferably 70-75℃;

[0036] The pressure of the light-weight removal tower is 0.01–0.04 MPa, preferably 0.02–0.03 MPa;

[0037] The reflux ratio of the light-light-removal tower is 0.5-3, preferably 2.

[0038] Furthermore, in step S2, the overhead gas B mainly consists of acetal and ethyl ester.

[0039] Further, in step S2, the azeotropic component in the top gas B is condensed into liquid substance B by the top condenser of the dealdehyde removal tower. Liquid substance B enters the top reflux tank of the dealdehyde removal tower for separation. A portion of liquid substance B is returned to the top of the dealdehyde removal tower by the top reflux pump, and the other portion of liquid substance B is extracted through the sampling outlet.

[0040] Furthermore, in step S2, the temperature at the top of the formaldehyde removal tower is 65-80℃, preferably 70-75℃;

[0041] The bottom temperature of the formaldehyde removal tower is 50-65℃, preferably 58-63℃;

[0042] The pressure of the formaldehyde removal tower is -20kPa to -98kPa, preferably -50kPa to -90kPa;

[0043] The reflux ratio of the formaldehyde removal tower is 0.5-2, preferably 1.

[0044] Furthermore, in step S3, the main component of the overhead gas C is ethanol.

[0045] Furthermore, in step S3, another portion of the liquid phase substance C is returned to the top of the purification column by the action of the purification column top reflux pump.

[0046] Furthermore, in step S3, the bottom feed liquid C enters the refining collection tank after being pumped by the bottom pump of the refining tower. The main components of the bottom feed liquid C are heavy components with boiling points higher than ethanol.

[0047] Furthermore, in step S3, the temperature at the top of the refining tower is 70-85℃, preferably 75-80℃.

[0048] The bottom temperature of the refining tower is 75-90℃, preferably 80-85℃.

[0049] The pressure of the refining tower is 0.05-0.08 MPa, preferably 0.06-0.07 MPa.

[0050] The reflux ratio of the refining tower is 0.5-1, preferably 0.8.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] The distillation separation process of this invention operates under normal or slightly positive pressure, which can effectively reduce equipment investment, save investment, improve the safety of production and operation, and prevent the introduction of other impurities. It also features low energy consumption, short route, and low cost. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the device connection of the present invention.

[0054] The following are the reference numerals: 1. Low-pressure fractionated ethanol storage tank; 11. Raw material side transfer pump; 2. Light-light product removal tower; 21. Light-light product removal tower top condenser; 22. Light-light product removal tower top reflux tank; 23. Light-light product removal tower top reflux pump; 24. Light-light product removal tower bottom pump; 3. Formaldehyde removal tower; 31. Formaldehyde removal tower top condenser; 32. Formaldehyde removal tower top reflux tank; 33. Formaldehyde removal tower top reflux pump; 34. Formaldehyde removal tower bottom pump; 35. Negative pressure protection tank; 36. Negative pressure device; 4. Refining tower; 41. Refining tower top condenser; 42. Refining tower top reflux tank; 43. Refining tower top reflux pump; 44. Refining tower bottom pump; 5. Refining tower reflux tank outflow pump; 6. Molecular sieve dehydration equipment; 7. Finished product collection tank; 8. Refined product collection tank. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0056] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0057] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0060] Example 1

[0061] See Figure 1 This embodiment provides an apparatus for removing acetal from ethanol, comprising a light acetal removal tower 2, an acetal removal tower 3, and a purification tower 4 connected in sequence by pipelines.

[0062] The light component removal tower 2 is used to separate the light components from the system to be separated.

[0063] The formaldehyde removal tower 3 is used to separate acetal and ethyl ester from the system to be separated.

[0064] The purification tower 4 is used to purify and separate the ethanol in the system to be separated by distillation.

[0065] In this embodiment, the device further includes a low-pressure fractionated ethanol storage tank 1, which is connected to the light-duty removal tower 2 via a pipeline, and a raw material side conveying pump 11 is provided on the connected pipeline.

[0066] In this embodiment, the light component removal tower 2 is a light component removal distillation tower, used to separate the light components from the system to be separated;

[0067] The formaldehyde removal tower 3 is a acetal removal distillation tower, used to separate acetal and ethyl ester from the system to be separated;

[0068] The purification tower 4 is an ethanol purification tower, used to purify and separate the ethanol in the system to be separated by distillation.

[0069] In this embodiment, the top of the light-weight removal tower 2 is provided with a light-weight removal tower top condenser 21 and a light-weight removal tower top reflux tank 22. The inlet of the light-weight removal tower top condenser 21 is connected to the top of the light-weight removal tower 2 through a pipe, the outlet of the light-weight removal tower top condenser 21 is connected to the inlet of the light-weight removal tower top reflux tank 22 through a pipe, the liquid phase outlet of the light-weight removal tower top reflux tank 22 is connected to the reflux port of the light-weight removal tower 2 through a pipe, and the light-weight removal tower top reflux tank 22 is also provided with a sampling outlet.

[0070] In this embodiment, a top reflux pump 23 is provided on the pipeline connecting the liquid phase outlet of the top reflux tank 22 of the light-light removal tower to the reflux port of the light-light removal tower 2.

[0071] In this embodiment, the bottom of the light-light removal tower 2 is connected to the side feed port of the aldehyde removal tower 3 via a pipeline, and the connected pipeline is equipped with a light-light removal tower bottom pump 24.

[0072] In this embodiment, the top of the formaldehyde removal tower 3 is equipped with a formaldehyde removal tower top condenser 31 and a formaldehyde removal tower top reflux tank 32. The inlet of the formaldehyde removal tower top condenser 31 is connected to the top of the formaldehyde removal tower 3 via a pipe, and the outlet of the formaldehyde removal tower top condenser 31 is connected to the inlet of the formaldehyde removal tower top reflux tank 32 via a pipe. One liquid phase outlet of the formaldehyde removal tower top reflux tank 32 is connected to the reflux port of the formaldehyde removal tower 3 via a pipe. The other liquid phase outlet of the formaldehyde removal tower top reflux tank 32 is equipped with a negative pressure protection tank 35. The inlet of the negative pressure protection tank 35 is connected to the other liquid phase outlet of the formaldehyde removal tower top reflux tank 32 via a pipe, and the outlet of the negative pressure protection tank 35 is connected to an external negative pressure device 36 via a pipe. The formaldehyde removal tower top reflux tank 32 is also equipped with a sampling outlet.

[0073] In this embodiment, the liquid phase outlet of the formaldehyde removal tower top reflux tank 32 is connected to the reflux port of the formaldehyde removal tower 3 by a pipe equipped with a formaldehyde removal tower top reflux pump 33, which is used to control the reflux of the top liquid.

[0074] In this embodiment, the bottom of the formaldehyde removal tower 3 is connected to the side feed inlet of the refining tower 4 via a pipeline, and a formaldehyde removal tower pump 34 is installed on the connected pipeline.

[0075] In this embodiment, the top of the refining column 4 is equipped with a refining column top condenser 41 and a refining column top reflux tank 42. The inlet of the refining column top condenser 41 is connected to the top of the refining column 4 via a pipe, and the outlet of the refining column top condenser 41 is connected to the inlet of the refining column top reflux tank 42 via a pipe. One liquid phase outlet of the refining column top reflux tank 42 is connected to the reflux port of the refining column 4 via a pipe, and the other liquid phase outlet of the refining column top reflux tank 42 is equipped with a molecular sieve dehydration device 6. The inlet of the molecular sieve dehydration device 6 is connected to the other liquid phase outlet of the refining column top reflux tank 42 via a pipe, and a refining column reflux tank collection pump 5 is installed on the connected pipe. The outlet of the molecular sieve dehydration device 6 is connected to a finished product collection tank 7 via a pipe, and the finished product collection tank 7 has a collection outlet.

[0076] The purification tower top condenser 41 is used to condense the gas at the top of the purification tower 4, and the purification tower top reflux tank 42 is used to store the ethanol produced by the purification tower 4.

[0077] In this embodiment, a top reflux pump 43 is provided on the pipeline connecting the liquid phase outlet of the top reflux tank 42 of the refining tower to the reflux port of the refining tower 4.

[0078] In this embodiment, the condenser 41 at the top of the refining tower is a total condenser.

[0079] In this embodiment, the device further includes a refining collection tank 8. The bottom of the refining tower 4 is connected to the side feed port of the refining collection tank 8 via a pipe. A refining tower bottom pump 44 is installed on the connected pipe. The refining collection tank 8 is provided with a sampling outlet.

[0080] Furthermore, the present invention also provides a purification method for removing acetal from ethanol, which uses the above-mentioned apparatus for removing acetal from ethanol, and the specific steps are as follows:

[0081] S1. The low-pressure fractionated ethanol in the low-pressure fractionated ethanol storage tank 1 is separated by the light-light-removal tower 2 to obtain tower top gas A and tower bottom liquid A;

[0082] S2. The bottom liquid A obtained in step S1 is transported into the formaldehyde removal tower 3 by the bottom pump 24 of the light light removal tower to separate the top gas B and the bottom liquid B.

[0083] S3. The bottom liquid B obtained in step S2 is transported into the purification tower 4 by the action of the dealdehyde tower ground pump 34. The purification tower 4 distills and purifies the ethanol in the bottom liquid B to obtain the overhead gas C and the bottom liquid C.

[0084] S4. The overhead gas C obtained in step S3 is condensed into liquid substance C by the purification tower overhead condenser 41. Liquid substance C enters the purification tower overhead reflux tank 42 for separation. A portion of liquid substance C enters the molecular sieve dehydration equipment 6 after being pumped out of the purification tower reflux tank 5. After dehydration, the ethanol liquid phase is entered into the finished product collection tank 7 for storage.

[0085] In this embodiment, in step S1, the overhead gas A mainly contains light components such as methanol and diethyl ether.

[0086] In this embodiment, in step S1, the top gas A is condensed into liquid substance A by the top condenser 21 of the light-light removal tower. Liquid substance A enters the top reflux tank 22 of the light-light removal tower for separation. A portion of liquid substance A is returned to the top of the light-light removal tower 2 by the action of the top reflux pump 23, and the other portion of liquid substance A is extracted.

[0087] In this embodiment, in step S1, the low-pressure fractionated ethanol is industrial-grade ethanol obtained by low-pressure separation of ethanol produced by hydrogenation of ethyl acetate.

[0088] In this embodiment, in step S1, the temperature at the top of the light-weight removal tower 2 is 55-65°C;

[0089] The bottom temperature of the light-weight removal tower 2 is 50-77℃;

[0090] The pressure of the light-weight removal tower 2 is 0.01–0.04 MPa;

[0091] The reflux ratio of the light-light-removal tower 2 is 0.5-3.

[0092] In this embodiment, in step S2, the overhead gas B mainly consists of acetal and ethyl acetate.

[0093] In this embodiment, in step S2, the azeotropic component in the top gas B is condensed into liquid substance B by the top condenser 31 of the dealdehyde removal tower. Liquid substance B enters the top reflux tank 32 of the dealdehyde removal tower for separation. A portion of liquid substance B is returned to the top of the dealdehyde removal tower 3 by the top reflux pump 33, and the other portion of liquid substance B is extracted through the sampling outlet.

[0094] In this embodiment, in step S2, the temperature at the top of the formaldehyde removal tower 3 is 65-80℃;

[0095] The bottom temperature of the formaldehyde removal tower 3 is 50-65℃;

[0096] The pressure of the formaldehyde removal tower 3 is -20kPa to -98kPa;

[0097] The reflux ratio of the formaldehyde removal tower 3 is 0.5-2.

[0098] In this embodiment, in step S3, the main component of the overhead gas C is ethanol.

[0099] In this embodiment, in step S3, another portion of the liquid phase substance C is returned to the top of the purification column 4 after being acted upon by the purification column top reflux pump 43.

[0100] In this embodiment, in step S3, the bottom feed liquid C enters the refining collection tank 8 after being pumped by the bottom pump 44 of the refining tower. The main components of the bottom feed liquid C are heavy components with boiling points higher than ethanol.

[0101] In this embodiment, in step S3, the temperature at the top of the refining tower 4 is 70-85°C.

[0102] The bottom temperature of the refining tower 4 is 75-90℃.

[0103] The pressure of the refining tower 4 is 0.05 to 0.08 MPa.

[0104] The reflux ratio of the refining tower 4 is 0.5-1.

[0105] Example 2

[0106] This embodiment provides a purification method for removing acetal from ethanol, employing... Figure 1 The apparatus shown is used to remove acetal from ethanol, and the specific steps are as follows:

[0107] First, industrial-grade ethanol (95.47% ethanol, 0.87% methanol, 0.63% diethyl ether, 0.33% n-propanol, 0.57% sec-butanol, 1.76% ethyl acetate, and 0.37% acetal) obtained from low-pressure fractionation is fed into the light-duty removal tower 2 through the side of the low-pressure fractionated ethanol storage tank 1.

[0108] The heating temperature of the bottom of the light component removal tower 2 is set to 72℃, the temperature at the top of the tower is set to 62℃, and the pressure is set to 0.025MPa. The top of the light component removal tower 2 is kept under total reflux for 1 hour. After removing the light components by condensation at the top of the tower, the reflux ratio is controlled to 2. The ethanol fraction at the bottom of the tower is collected and fed into the aldehyde removal tower 3 through the side feed of the bottom pump 24.

[0109] The heating temperature of the bottom of the formaldehyde removal tower 3 is set to 59℃, the top temperature is 52℃, and the pressure is -80kPa. The top of the formaldehyde removal tower 3 is kept under total reflux for 1 hour. After condensing the azeotropic and similar boiling point components at the top of the tower, the reflux ratio is controlled to 1. The ethanol fraction at the bottom of the tower is collected and fed into the purification tower 4 through the side feed of the bottom pump 34.

[0110] The heating temperature of the reboiler of purification column 4 is set to 83℃, the top temperature to 76℃, and the pressure to 0.065MPa. Total reflux is maintained at the top of purification column 4 for 1 hour, with a reflux ratio controlled at 0.5. Heavy components with boiling points higher than ethanol are retained at the bottom of the column and transported to the purification column collection tank 8 via the bottom pump 44. The desired product, ethanol, enters the purification column top reflux tank 42 under the action of condensation at the top of the column.

[0111] The ethanol collected by condensation is transported by the reflux pump 5 of the refining tower into the molecular sieve dehydration equipment 6 for further dehydration, and finally enters the finished product collection tank 7.

[0112] The measurement results are shown in Table 1.

[0113] Table 1. Percentage content (%) of each component after distillation

[0114] methanol ethanol Diethyl ether n-Propanol sec-butanol Ethyl acetate Acetaldehyde 0.0019 99.99 0.0003 0.0022 0.00038 0.00122 0.004

[0115] Example 3

[0116] This embodiment provides a purification method for removing acetal from ethanol, employing... Figure 1 The apparatus shown is used to remove acetal from ethanol, and the specific steps are as follows:

[0117] First, industrial-grade ethanol (95.47% ethanol, 0.87% methanol, 0.63% diethyl ether, 0.33% n-propanol, 0.57% sec-butanol, 1.76% ethyl acetate, and 0.37% acetal) obtained from low-pressure fractionation is fed into the light-duty removal tower 2 through the side of the low-pressure fractionated ethanol storage tank 1.

[0118] The heating temperature of the bottom of the light component removal tower 2 is set to 70℃, the temperature at the top of the tower is set to 62℃, and the pressure is set to 0.02MPa. The top of the light component removal tower 2 is kept under total reflux for 1 hour. After removing the light components by condensation at the top of the tower, the reflux ratio is controlled to 2. The ethanol fraction at the bottom of the tower is collected and fed into the aldehyde removal tower 3 through the side feed of the bottom pump 24.

[0119] The heating temperature of the bottom of the formaldehyde removal tower 3 is set to 62℃, the top temperature is set to 55℃, and the pressure is set to -60kPa. The top of the formaldehyde removal tower 3 is kept under total reflux for 1 hour. After condensing the azeotropic and similar boiling point components at the top of the tower, the reflux ratio is controlled to 1. The ethanol fraction at the bottom of the tower is collected and fed into the purification tower 4 through the side feed of the bottom pump 34.

[0120] The heating temperature of the reboiler of purification column 4 is set to 80℃, the top temperature to 77℃, and the pressure to 0.06MPa. Total reflux is maintained at the top of purification column 4 for 1 hour, with a reflux ratio controlled at 0.5. Heavy components with boiling points higher than ethanol are retained at the bottom of the column and transported to the purification column collection tank 8 via the bottom pump 44. The desired product, ethanol, enters the purification column top reflux tank 42 under the action of condensation at the top of the column.

[0121] The ethanol collected by condensation is transported by the reflux pump 5 of the refining tower into the molecular sieve dehydration equipment 6 for further dehydration, and finally enters the finished product collection tank 7.

[0122] The measurement results are shown in Table 2.

[0123] Table 2. Percentage content (%) of each component after distillation

[0124] methanol ethanol Diethyl ether n-Propanol sec-butanol Ethyl acetate Acetaldehyde 0.0063 99.97 0.0009 0.0076 0.00049 0.0057 0.0046

[0125] Example 4

[0126] This embodiment provides a purification method for removing acetal from ethanol, employing... Figure 1 The apparatus shown is used to remove acetal from ethanol, and the specific steps are as follows:

[0127] First, industrial-grade ethanol (95.47% ethanol, 0.87% methanol, 0.63% diethyl ether, 0.33% n-propanol, 0.57% sec-butanol, 1.76% ethyl acetate, and 0.37% acetal) obtained from low-pressure fractionation is fed into the light-duty removal tower 2 through the side of the low-pressure fractionated ethanol storage tank 1.

[0128] The heating temperature of the bottom of the light component removal tower 2 is set to 74℃, the temperature at the top of the tower is set to 63℃, and the pressure is set to 0.03MPa. The top of the light component removal tower 2 is kept under total reflux for 1 hour. After removing the light components by condensation at the top of the tower, the reflux ratio is controlled to 2. The ethanol fraction at the bottom of the tower is collected and fed into the aldehyde removal tower 3 through the side feed of the bottom pump 24.

[0129] The heating temperature of the bottom of the formaldehyde removal tower 3 is set to 60℃, the temperature at the top of the tower is 50℃, and the pressure is -70kPa. The top of the formaldehyde removal tower 3 is kept under total reflux for 1 hour. After condensing the components with azeotropic and similar boiling points at the top of the tower, the reflux ratio is controlled to 1. The ethanol fraction at the bottom of the tower is collected and fed into the purification tower 4 through the side feed of the bottom pump 34 of the formaldehyde removal tower.

[0130] The heating temperature of the reboiler of purification column 4 is set to 84℃, the top temperature to 76℃, and the pressure to 0.07MPa. Total reflux is maintained at the top of purification column 4 for 1 hour, with a reflux ratio controlled at 0.5. Heavy components with boiling points higher than ethanol are retained at the bottom of the column and transported to the purification column collection tank 8 via the bottom pump 44. The desired product, ethanol, enters the purification column top reflux tank 42 under the action of condensation at the top of the column.

[0131] The ethanol collected by condensation is transported by the reflux pump 5 of the refining tower into the molecular sieve dehydration equipment 6 for further dehydration, and finally enters the finished product collection tank 7.

[0132] The measurement results are shown in Table 3.

[0133] Table 3. Percentage content (%) of each component after distillation

[0134] methanol ethanol Diethyl ether n-Propanol sec-butanol Ethyl acetate Acetaldehyde 0.0026 99.98 0.0025 0.0037 0.00294 0.00456 0.0037

[0135] As shown in Examples 2-4, industrial-grade ethanol (95.47% ethanol, 0.87% methanol, 0.63% diethyl ether, 0.33% n-propanol, 0.57% sec-butanol, 1.76% ethyl acetate, and 0.37% acetal) obtained by low-pressure fractionation is treated with the purification method for removing acetal from ethanol provided by this invention. The percentage content of acetal is less than 0.0045%, and the content is reduced to below 150 ppm, which meets the quality requirements of high-purity ethanol.

[0136] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A purification method for removing acetal from ethanol, characterized in that, The procedure was carried out using an apparatus for removing acetal from ethanol. The apparatus for removing acetal from ethanol includes a light acetal removal tower (2), an acetal removal tower (3), and a purification tower (4) connected in sequence by pipelines. The light component removal tower (2) is used to separate the light components from the system to be separated. The formaldehyde removal tower (3) is used to separate acetal and ethyl ester from the system to be separated. The purification tower (4) is used to purify and separate the ethanol from the system to be separated by distillation. The bottom of the light-light removal tower (2) is connected to the side feed port of the formaldehyde removal tower (3) by a pipeline, and the connected pipeline is equipped with a light-light removal tower bottom pump (24). The top of the refining tower (4) is provided with a refining tower top condenser (41) and a refining tower top reflux tank (42). The inlet of the refining tower top condenser (41) is connected to the top of the refining tower (4) through a pipe. The outlet of the refining tower top condenser (41) is connected to the inlet of the refining tower top reflux tank (42) through a pipe. One liquid phase outlet of the refining tower top reflux tank (42) is connected to the reflux port of the refining tower (4) through a pipe. The other liquid phase outlet of the refining tower top reflux tank (42) is provided with a molecular sieve dehydration device (6). The inlet of the molecular sieve dehydration device (6) is connected to the other liquid phase outlet of the refining tower top reflux tank (42) through a pipe. A refining tower reflux tank collection pump (5) is provided on the connected pipe. The outlet of the molecular sieve dehydration device (6) is connected to the finished product collection tank (7) through a pipe. The finished product collection tank (7) is provided with a collection outlet. The purification tower top condenser (41) is used to condense the gas at the top of the purification tower (4), and the purification tower top reflux tank (42) is used to store the ethanol produced by the purification tower (4). A top reflux pump (43) is installed on the pipeline connecting the liquid phase outlet of the top reflux tank (42) to the reflux port of the refining tower (4). The specific steps are as follows: S1. The low-pressure fractionated ethanol in the low-pressure fractionated ethanol storage tank (1) is separated by the light removal tower (2) to obtain the top gas A and the bottom liquid A; S2. The bottom liquid A obtained in step S1 is transported into the formaldehyde removal tower (3) by the action of the bottom pump (24) of the light removal tower to separate the top gas B and the bottom liquid B; S3. The bottom liquid B obtained in step S2 is transported into the purification tower (4) by the action of the dealdehyde tower pump (34). The purification tower (4) purifies and separates the ethanol in the bottom liquid B by distillation to obtain the overhead gas C and the bottom liquid C. S4. The top gas C obtained in step S3 is condensed into liquid substance C by the top condenser (41) of the refining tower. Liquid substance C enters the top reflux tank (42) of the refining tower for separation. A portion of liquid substance C enters the molecular sieve dehydration equipment (6) after being pumped out of the refining tower reflux tank (5). After dehydration, ethanol liquid phase is obtained and stored in the finished product collection tank (7). In step S2, the overhead gas B contains acetal and ethyl acetate; The azeotropic component in the top gas B of the tower is condensed into liquid substance B by the top condenser (31) of the dealdehyde removal tower. Liquid substance B enters the top reflux tank (32) of the dealdehyde removal tower for separation. A portion of liquid substance B is returned to the top of the dealdehyde removal tower (3) after being acted upon by the top reflux pump (33), and the other portion of liquid substance B is extracted through the extraction outlet. The temperature of the bottom of the formaldehyde removal tower (3) is 59°C and the temperature of the top of the tower is 52°C; or, the temperature of the bottom of the formaldehyde removal tower (3) is 62°C and the temperature of the top of the tower is 55°C; or, the temperature of the bottom of the formaldehyde removal tower (3) is 60°C and the temperature of the top of the tower is 50°C. The pressure of the formaldehyde removal tower (3) is -20kPa ~ -98kPa; The reflux ratio of the formaldehyde removal tower (3) is 0.5-2.

2. The purification method for removing acetal from ethanol according to claim 1, characterized in that, The device also includes a low-pressure fractionated ethanol storage tank (1), which is connected to the light removal tower (2) via a pipeline, and the connected pipeline is equipped with a raw material side conveying pump (11).

3. The purification method for removing acetal from ethanol according to claim 1, characterized in that, The top of the light-removal tower (2) is provided with a light-removal tower top condenser (21) and a light-removal tower top reflux tank (22). The inlet of the light-removal tower top condenser (21) is connected to the top of the light-removal tower (2) through a pipe. The outlet of the light-removal tower top condenser (21) is connected to the inlet of the light-removal tower top reflux tank (22) through a pipe. The liquid phase outlet of the light-removal tower top reflux tank (22) is connected to the reflux port of the light-removal tower (2) through a pipe. The light-removal tower top reflux tank (22) is also provided with a sampling outlet. A top reflux pump (23) is installed on the pipeline connecting the liquid phase outlet of the top reflux tank (22) of the light-light removal tower to the reflux port of the light-light removal tower (2).

4. The purification method for removing acetal from ethanol according to claim 1, characterized in that, The top of the formaldehyde removal tower (3) is equipped with a formaldehyde removal tower top condenser (31) and a formaldehyde removal tower top reflux tank (32). The inlet of the formaldehyde removal tower top condenser (31) is connected to the top of the formaldehyde removal tower (3) through a pipe. The outlet of the formaldehyde removal tower top condenser (31) is connected to the inlet of the formaldehyde removal tower top reflux tank (32) through a pipe. One liquid phase outlet of the formaldehyde removal tower top reflux tank (32) is connected to the reflux port of the formaldehyde removal tower (3) through a pipe. The other liquid phase outlet of the formaldehyde removal tower top reflux tank (32) is equipped with a negative pressure protection tank (35). The inlet of the negative pressure protection tank (35) is connected to the other liquid phase outlet of the formaldehyde removal tower top reflux tank (32) through a pipe. The outlet of the negative pressure protection tank (35) is connected to a negative pressure device (36) through a pipe. The formaldehyde removal tower top reflux tank (32) is also equipped with a sampling outlet. The liquid phase outlet of the formaldehyde removal tower top reflux tank (32) is connected to the reflux port of the formaldehyde removal tower (3) by a reflux pump (33) at the top of the tower. The reflux pump (33) at the top of the tower is used to control the reflux of the liquid at the top of the tower. The bottom of the formaldehyde removal tower (3) is connected to the side feed inlet of the refining tower (4) by a pipeline, and a formaldehyde removal tower ground pump (34) is installed on the connected pipeline.

5. The purification method for removing acetal from ethanol according to claim 1, characterized in that, The device also includes a fine collection tank (8), the bottom of the fine tower (4) is connected to the side feed port of the fine collection tank (8) by a pipe, a fine tower bottom pump (44) is provided on the connected pipe, and a sampling outlet is provided on the fine collection tank (8).

6. The purification method for removing acetal from ethanol according to claim 1, characterized in that, In step S1, the overhead gas A contains light components such as methanol and diethyl ether; The gas A at the top of the tower is condensed into liquid substance A after being condensed by the light-removal tower top condenser (21). Liquid substance A enters the light-removal tower top reflux tank (22) for separation. Part of the liquid substance A is returned to the top of the light-removal tower (2) after being acted upon by the light-removal tower top reflux pump (23), and the other part of the liquid substance A is extracted. The low-pressure fractionated ethanol is industrial-grade ethanol obtained by low-pressure separation of ethanol produced by hydrogenation of ethyl acetate. The temperature at the top of the light-light removal tower (2) is 55-65℃; The bottom temperature of the light-light removal tower (2) is 50-77℃; The pressure of the light-light removal tower (2) is 0.01 ~ 0.04 MPa; The reflux ratio of the light-removal tower (2) is 0.5-3.

7. The purification method for removing acetal from ethanol according to claim 1, characterized in that, In step S3, the main component of the overhead gas C is ethanol; Another portion of the liquid phase substance C is returned to the top of the purification tower (4) after being acted upon by the top reflux pump (43); The bottom feed liquid C of the tower enters the refining collection tank (8) after being pumped by the bottom pump (44). The main components of the bottom feed liquid C are heavy components with boiling points higher than ethanol. The temperature at the top of the refining tower (4) is 70-85℃. The bottom temperature of the refining column (4) is 75-90℃. The pressure of the refining tower (4) is 0.05 ~ 0.08 MPa. The reflux ratio of the refining tower (4) is 0.5-1.

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