Treatment system and treatment method for acetic ether hydrogenation light component byproducts

Abstract

The invention discloses a treatment system and a treatment method for ethyl acetate hydrogenation light component byproducts, and the treatment system comprises a reactor used for receiving recycle hydrogen led out from a synthesis unit and extracted light components; the synthesis unit is used for preparing ethanol by hydrogenation of acetic ether; the heat exchanger is communicated with the synthesis unit and the reactor; the water cooler is communicated with the heat exchanger; the crude alcohol separation tank is communicated with the water cooler; and the ethanol buffer tank is communicated with the crude alcohol separation tank. According to the treatment method disclosed by the invention, a light component byproduct in ethyl acetate hydrogenation for preparing ethanol can be converted into a byproduct ethanol in a relatively small space with very low energy consumption, the cost of subsequent trade, storage and transportation links of the material can be greatly reduced, and the material is sold by using chemical raw materials, so that the value of the material is ensured; and the method has the advantages of low investment, simple control and no need of additional operation post, and is especially suitable for the treatment of by-products in the existing acetic ether hydrogenation light component enterprises.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a system and method for treating light component byproducts of ethyl acetate hydrogenation. Background Technology

[0002] Compared to traditional bio-fermentation and petroleum-based methods for ethanol production, the hydrogenation of acetate for ethanol production can make full use of my country's coal resources, avoiding reliance on grain or petroleum. It also has advantages such as mild reaction conditions, low-cost and efficient catalysts, and low-cost raw materials. In recent years, it has developed rapidly in the chemical industry, with a large number of acetate esterification plants and enterprises being built and put into operation, providing a good demonstration and application for the coal-to-ethanol route.

[0003] The existing process for producing ethanol from ethyl acetate mainly adopts a gas-phase circulating hydrogenation process. Hydrogen and ethyl acetate undergo a hydrogenation reaction in a fixed-bed reactor, and the acetate ester is converted into ethanol. The reaction equation is: CH3COOCH2CH3 + 4H2→2CH3CH2OH.

[0004] Because a small amount of ethyl acetate cannot completely react during the reaction process, a light component will remain in the subsequent ethanol refining process. This light component consists of ethyl acetate (approximately 60%), ethanol (approximately 30%), acetaldehyde, and other components (approximately 10%). Due to the presence of ethyl acetate and its low flash point, this light component is subject to strict legal and regulatory controls regarding storage and transportation. Therefore, the subsequent processing and sale of this material are restricted, increasing storage, sales, and management costs for enterprises. Some manufacturers utilize it as an energy source, which significantly reduces its value as a chemical raw material. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method for processing light component byproducts from the hydrogenation of ethyl acetate. This system can convert light component byproducts from the hydrogenation of ethyl acetate to ethanol into ethanol byproducts in a small space with very low energy consumption. This can greatly reduce the costs of subsequent trading, storage, and transportation of this material, allowing it to be sold as a chemical raw material and ensuring its value. Moreover, this method requires little investment, is simple to control, and does not require additional operating positions. It is particularly suitable for existing ethyl acetate hydrogenation light component enterprises to process byproducts.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A system for processing light component byproducts of ethyl acetate hydrogenation, the system comprising:

[0008] A reactor for receiving recycled hydrogen and extracted light components from a synthesis unit used for the hydrogenation of ethyl acetate to ethanol;

[0009] a heat exchanger, which is in communication with the synthesis unit and the reactor;

[0010] a water cooler, which is in communication with the heat exchanger;

[0011] a crude alcohol separation tank, which is in communication with the water cooler;

[0012] an ethanol buffer tank, which is in communication with the crude alcohol separation tank.

[0013] In one or more embodiments of the present application, the processing system further comprises a light-removing column in communication with the ethanol buffer tank, the light-removing column top being in communication with a first condenser, a first reflux tank and a first reflux pump in sequence, the first reflux pump being in communication with the light-removing column;

[0014] the light-removing column bottom being in communication with a feed pump and a product column in sequence.

[0015] In one or more embodiments of the present application, the product column top is in communication with a second condenser, a second reflux tank and a second reflux pump in sequence, the second reflux pump being connected to the product column, and the product column bottom being in communication with a discharge pump and a cooler in sequence.

[0016] In one or more embodiments of the present application, the light-removing column bottom is in communication with a first reboiler; and / or,

[0017] the product column bottom is in communication with a second reboiler.

[0018] In one or more embodiments of the present application, the ethanol buffer tank is provided with a feeding pipeline for being in communication with the synthesis unit.

[0019] Another specific embodiment of the present application provides a technical solution as follows:

[0020] A processing method of ethyl acetate hydrogenation light component byproduct, using a processing system of ethyl acetate hydrogenation light component byproduct, specifically comprising the following steps:

[0021] Separating circulating hydrogen and light components from the synthesis unit, and sending the circulating hydrogen and light components into a heat exchanger and then into a reactor for reaction to obtain crude alcohol gas;

[0022] Sending the crude alcohol gas in the reactor into the heat exchanger and the water cooler in sequence for treatment, and then into a crude alcohol separation tank for gas-liquid separation, and sending the liquid phase product, i.e. ethanol, into an ethanol buffer tank.

[0023] In one or more embodiments of the present application, the molar ratio of the circulating hydrogen and light components is (20-60): 1.

[0024] In one or more embodiments of the present application, the reactor internal reaction temperature is 150-250℃, the reactor internal temperature difference is less than or equal to 10℃; and / or,

[0025] The reactor internal pressure is 2.0-6.0 MPaG, and the reactor internal pressure difference is less than or equal to 0.1 MPaG.

[0026] In one or more embodiments of the present application, the product ethanol in the ethanol buffer tank is sent to a light-removing column, and the light-removing column overhead vapor is sent to a first condenser and a first reflux tank in sequence for treatment.

[0027] The liquid phase is taken from the light-removing column bottom, and the liquid phase is sent to a product column for treatment. The product column overhead vapor is sent to a second condenser and a second reflux tank in sequence for treatment, and the product ethanol is taken from the second reflux tank.

[0028] In one or more embodiments of the present application, the light-removing column overhead pressure is 0.05-0.1 MPaG; and / or,

[0029] The light-removing column overhead vapor temperature is 90-100℃; and / or,

[0030] After entering the first condenser, the light-removing column overhead vapor is condensed to 50-60℃; and / or,

[0031] The product column overhead pressure is 0.02-0.1 MPaG; and / or,

[0032] The product column overhead vapor temperature is 58-60℃; and / or,

[0033] After entering the second condenser, the product column overhead vapor is condensed to 40-50℃.

[0034] Compared with the prior art, the present application reprocesses the by-product light components generated by the hydrogenation of ethyl acetate, and the generated product ethanol can be sold again, achieving the purpose of turning waste into treasure. The tail gas generated in the treatment method of the present application is returned to the existing ethyl acetate hydrogenation reaction system after separation, no new waste gas is generated, and the environmental friendly effect is achieved. The process flow of the treatment method of the present application is simple, the equipment is less, no new compression equipment is needed, it is economical and practical, and the cost is reduced and the benefit is increased. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creating labor.

[0036] Figure 1 The structural schematic diagram of the synthesis unit in one embodiment of the present application;

[0037] Figure 2 The structural schematic diagram of the treatment system of the ethyl acetate hydrogenation light component by-product in one embodiment of the present application;

[0038] Figure 3 The structural schematic diagram of the further purification of the product ethanol in the ethanol buffer tank in one embodiment of the present application;

[0039] Figure 4 The structural enlarged view of the further purification of the product ethanol in the ethanol buffer tank in one embodiment of the present application;

[0040] Figure 5 The structural schematic diagram of the product ethanol returning to the synthesis unit in the ethanol buffer tank in one embodiment of the present application.

[0041] Main figure mark explanation:

[0042] 1, synthesis unit; 11, circulating compressor; 12, first heat exchanger; 13, first hydrogenation reactor; 14, first condenser; 15, first separator; 21, second heat exchanger; 22, second hydrogenation reactor; 23, second condenser; 24, second separator; 31, reactor; 32, heat exchanger; 33, water cooler; 34, crude alcohol separation tank; 35, ethanol buffer tank; 36, feeding pipeline; 41, light component removal column; 42, first condenser; 43, first reflux tank; 44, first reflux pump; 45, feeding pump; 46, first reboiler; 51, product column; 52, second condenser; 53, second reflux tank; 54, second reflux pump; 55, discharging pump; 56, cooler; 57, second reboiler. DETAILED DESCRIPTION

[0043] In order to make the person skilled in the art better understand the technical solutions in the present disclosure, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present disclosure.

[0044] As Figure 1As shown, the existing acetate hydrogenation process uses acetate and hydrogen as raw materials, and uses synthesis unit 1 to prepare ethanol by hydrogenation reaction, and the hydrogenation process is as follows: the acetate is pressurized by a high-lift pump and then divided into two streams, one stream of acetate is mixed with the circulating gas from the outlet of the circulating compressor 11 and then enters the first heat exchanger 12, and after heat exchange, enters the first hydrogenation reactor 13. The mixed raw gas reacts under the action of the catalyst to obtain the product ethanol crude reaction gas. The crude reaction gas is cooled by the first heat exchanger 12, condensed by the first condenser 14, and separated by the first separator 15 to obtain the first separation gas.

[0045] The first separation gas is mixed with the other stream of acetate and then enters the second heat exchanger 21, and after heat exchange, enters the second hydrogenation reactor 22. The second reaction raw gas reacts under the action of the catalyst to obtain the product ethanol crude reaction gas. The crude reaction gas is cooled by the second heat exchanger 21, condensed by the second condenser 23, and separated by the second separator 24 to obtain the second separation gas. The second separation gas is mixed with fresh hydrogen and then enters the circulating compressor 11 for pressurization.

[0046] As shown in Figure 2 A specific embodiment of the present application provides a treatment system for acetate ester hydrogenation light component by-product, which comprises a reactor 31, and the reactor 31 is connected with a heat exchanger 32 at the top.

[0047] Specifically, a stream of circulating hydrogen is introduced from the synthesis unit 1 of the acetate hydrogenation process, and a light component is extracted from the synthesis unit 1, and the circulating hydrogen and the light component are mixed and then enter the heat exchanger 32, and the reaction gas in the reactor 31 enters the heat exchanger 32, and the circulating hydrogen, the light component and the reaction gas are heat-exchanged in the heat exchanger 32 and then enter the reactor 31 for reaction.

[0048] Further, the reactor 31 is a temperature-controlled fixed bed reactor, which has a large amount of catalyst loading, a large gas flux, and can control the temperature in sections to ensure that the temperature of the reaction raw material in the catalyst bed layer is controlled within a reasonable range.

[0049] Further, the heat exchanger 32 is sequentially connected with a water cooler 33, a crude alcohol separation tank 34 and an ethanol buffer tank 35.

[0050] Specifically, the crude alcohol separation tank 34 is provided with a vent gas venting pipeline at the top, the crude alcohol gas generated in the reactor 31 is heat-exchanged in the heat exchanger 32 and then enters the water cooler 33 for cooling, and after cooling, enters the crude alcohol separation tank 34 for gas-liquid separation, the separated gas phase can return to the synthesis unit 1 for continuous reaction through the vent gas venting pipeline, and the separated liquid phase is the product ethanol. The separated liquid phase is temporarily stored in the ethanol buffer tank 35.

[0051] By setting the vent gas vent line at the top of the crude alcohol separation tank 34, the gas phase can be avoided in the synthesis system, which helps to keep the hydrogenation reaction efficient for a long time.

[0052] Further, in combination with Figure 3 and Figure 4 , the ethanol buffer tank is communicated with the light removal column 41, the top of the light removal column 41 is sequentially communicated with the first condenser 42, the first reflux tank 43, and the first reflux pump 44, and the first reflux pump 44 is connected to the light removal column 41; the bottom of the light removal column 41 is sequentially communicated with the feed pump 45 and the product column 51.

[0053] Specifically, the product ethanol in the ethanol buffer tank 35 can be further purified, specifically, the product ethanol in the ethanol buffer tank 35 is sent to the light removal column 41, and the light removal column 41 is used to separate the ethanol and light components in the product ethanol. The pressure at the top of the light removal column 41 is 0.05MpaG-0.1MpaG, and the vapor temperature at the top of the light removal column 41 is 90℃-100℃. The vapor at the top of the light removal column 41 is condensed to 50℃-60℃ by the first condenser 42 and then enters the first reflux tank 43. The liquid phase in the first reflux tank 43 is pressurized by the first reflux pump 44, part of which is returned to the top of the light removal column 41, and the other part is extracted and transported to the reaction section as the feed for light component hydrogenation. The liquid phase at the bottom of the light removal column 41 is sent to the product column 51 by the feed pump 45.

[0054] Further, the bottom of the light removal column 41 is communicated with the first reboiler 46 for heating the light removal column 41.

[0055] Further, the top of the product column 51 is sequentially communicated with the second condenser 52, the second reflux tank 53, and the second reflux pump 54, the second reflux pump 54 is connected to the product column 51, and the bottom of the product column 51 is sequentially communicated with the discharge pump 55 and the cooler 56.

[0056] Specifically, the product column 51 is used to process the liquid phase material extracted from the bottom of the light removal column 41 to separate the ethanol and heavy components. The pressure at the top of the product column 51 is 0.02MpaG-0.1MpaG, and the vapor temperature at the top of the product column 51 is 58℃-60℃. The vapor at the top of the product column 51 is condensed to 40℃-50℃ by the second condenser 52 and then sent to the second reflux tank 53. The liquid phase in the second reflux tank 53 is pressurized by the second reflux pump 54, part of which is returned to the top of the product column 51, and the other part is extracted as qualified ethanol. The heavy components at the bottom of the product column 51 are sent to the cooler 56 by the discharge pump 55 for cooling, and then transported to the outside after cooling.

[0057] Further, the bottom of the product column 51 is communicated with the second reboiler 57 for heating the product column 51.

[0058] Further, as Figure 5As shown, the ethanol buffer tank 35 is equipped with a feed line 36 for connecting to the synthesis unit 1, so that the product ethanol in the ethanol buffer tank 35 is returned to the synthesis unit 1 to continue to participate in distillation.

[0059] Another specific embodiment of the present invention provides a method for treating the light component byproduct of ethyl acetate hydrogenation, comprising the following steps:

[0060] Step 1: Separate recycled hydrogen and light components from synthesis unit 1. Send the recycled hydrogen and light components into heat exchanger 32 at a molar ratio of (20-60):1 and then into reactor 31 for reaction to obtain crude alcohol gas.

[0061] Specifically, the internal reaction temperature of reactor 31 is 150℃-250℃, and the internal temperature difference of reactor 31 is less than or equal to 10℃; the internal pressure of reactor 31 is 2.0MpaG-6.0MpaG, and the internal pressure difference of reactor 31 is less than or equal to 0.1MpaG.

[0062] Furthermore, reactor 31 is equipped with a catalyst to catalyze the reaction of circulating hydrogen and light components. The catalyst is of an existing type, such as the catalyst prepared in the examples of the method for hydrogenation of acetate to ethanol in patent CN102976892A.

[0063] Step 2: The crude alcohol gas in reactor 31 is sequentially sent to heat exchanger 32 and water cooler 33 for treatment, and then sent to crude alcohol separation tank 34 for gas-liquid separation. The liquid phase is the product ethanol.

[0064] The present invention will be further described in detail below with reference to specific embodiments.

[0065] Example 1

[0066] The method for treating the byproducts of ethyl acetate hydrogenation light component in this embodiment is as follows:

[0067] like Figure 2 As shown, a stream of circulating hydrogen gas is drawn from the outlet of the circulating compressor in the acetate hydrogenation synthesis unit as the hydrogenation feed gas. The molar composition of the hydrogenation feed gas is H2 97.9%, with the remainder being nitrogen, CO2, and other balance gases. The light components produced in the synthesis unit are mixed with the circulating hydrogen gas and then enter a heat exchanger to exchange heat with the reaction gas in the reactor before entering the reactor. The mixed feed gas reacts under the action of a catalyst. The reaction temperature in the reactor is 200℃, and the reaction pressure is 4 MPaG. The light components include the following molar percentages: ethyl acetate 46.96%, ethanol 34.23%, acetaldehyde 7.47%, methanol 3.47%, diethyl ether 2.96%, water 3.48%, and other components 1.43%. The light component feed rate is 875 kg / h, and the circulating hydrogen feed rate is 13324 Nm³. 3 / h.

[0068] The ethanol gas after reaction in the reactor is cooled by a water cooler, and then enters a crude alcohol separation tank for gas-liquid separation. The separated gas phase is returned to the inlet of the circulating compressor in the synthesis unit for pressurization, and is combined into the synthesis unit for reaction. The separated liquid phase, i.e. 95% ethanol, is temporarily stored in an ethanol buffer tank. This product can be directly sold.

[0069] The ethanol product obtained after separation is 876 Kg / h.

[0070] According to the analysis results, the conversion rate of the light component by-product of acetic acid ester hydrogenation is above 99%.

[0071] Example 2

[0072] The treatment method of the light component by-product of acetic acid ester hydrogenation in this example is basically the same as that in Example 1, except that the product ethanol is further rectified and purified in the ethanol buffer tank. The specific process is as shown in Figure 3 and Figure 4 .

[0073] The light component separation tower is used to separate ethanol and light components in the crude ethanol. The operating pressure at the top of the tower is about 0.1 MPaG, and the 90℃ vapor at the top is condensed to 60℃ by the first condenser at the top of the tower, and then enters the first reflux tank.

[0074] The liquid phase in the first reflux tank is pressurized by the first reflux pump, and then part of it is returned to the top of the light component separation tower, and the other part is taken out and transported to the reaction section as the feed for light component hydrogenation. The liquid phase at the bottom of the light component separation tower is pressurized by the feed pump, and then transported to the product tower.

[0075] The product tower is used to separate ethanol and heavy components from the material taken out from the bottom of the light component separation tower. The operating pressure at the top of the product tower is about 0.1 MPaG, and the 60℃ vapor at the top is condensed to 50℃ by the second condenser, and then enters the second reflux tank.

[0076] The liquid phase in the second reflux tank is pressurized by the second reflux pump, and then part of it is returned to the top of the product tower, and the other part is taken out as qualified ethanol. The heavy components at the bottom of the product tower are transported by the discharge pump to the cooler, cooled to 40℃, and then transported to the outside.

[0077] In this example, 99.5% product ethanol 832 kg / h can be obtained after double-tower rectification.

[0078] Example 3

[0079] The treatment method of the light component by-product of acetic acid ester hydrogenation in this example is basically the same as that in Example 1, except that the product ethanol is further rectified and purified in the ethanol buffer tank. The specific process is as shown in Figure 5The product ethanol in the ethanol buffer tank is returned to the synthesis unit to continue participating in rectification, and 99.5% concentration ethanol can be obtained.

[0080] In conclusion, the by-product light component hydrogenation process is adopted in the present application, which comprises a temperature-controlled reactor, a heat exchanger, a separation tank, a buffer tank, and the product is obtained after preheating, reaction, condensation and separation. The raw material gas is provided by the existing acetate hydrogenation process, and the circulating gas generated by the reaction is returned to the existing acetate hydrogenation device. The 95% ethanol product obtained finally can be sold, or it can be used as crude ethanol to obtain 99.5% ethanol product after rectification. The by-product of acetate hydrogenation can be reused by adopting the present process, realizing efficient treatment of hydrogenation light component, avoiding treatment of organic waste, and also generating economic benefits. Therefore, it is a very potential treatment method for acetate hydrogenation by-products.

[0081] It is apparent to those skilled in the art that the present disclosure is not limited to the details of the foregoing exemplary embodiments, and that the present disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of the present disclosure. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present disclosure is defined by the appended claims rather than the foregoing description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the elements of the claims. Therefore, the scope of the present disclosure should be interpreted by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the elements of the claims.

[0082] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A system for processing ethyl acetate hydrogenation light ends byproducts, comprising: The processing system comprises: a reactor for receiving recycled hydrogen and light components from a synthesis unit for synthesizing ethanol by hydrogenation of ethyl acetate; a heat exchanger connected to the synthesis unit and the reactor; a water cooler connected to the heat exchanger; a crude alcohol separation tank connected to the water cooler; an ethanol buffer tank connected to the crude alcohol separation tank.

2. The ethyl acetate hydrodeoxygenation light ends byproduct treatment system of claim 1, wherein, The processing system further comprises a light component removal column connected to the ethanol buffer tank, the light component removal column being connected in sequence to a first condenser, a first reflux tank and a first reflux pump connected to the light component removal column; the light component removal column being connected in sequence to a feed pump and a product column.

3. The ethyl acetate hydrodeoxygenation light ends byproduct treatment system of claim 2, wherein, the product column being connected in sequence to a second condenser, a second reflux tank and a second reflux pump connected to the product column, the product column being connected in sequence to a discharge pump and a cooler.

4. The system for processing ethyl acetate hydrogenation light ends byproducts of claim 2, wherein, the light component removal column being connected to a first reboiler; and / or, the product column being connected to a second reboiler.

5. The ethyl acetate hydrodeoxygenation light ends byproduct treatment system of claim 1, wherein, The ethanol buffer tank is provided with a feeding line for being connected to the synthesis unit.

6. A process for the treatment of ethyl acetate hydrogenation light ends by-products, characterized in that, The processing system for by-products of light components of ethyl acetate hydrogenation as claimed in claim 1 comprises the following steps: recycled hydrogen and light components are separated from the synthesis unit and sent into the heat exchanger and then into the reactor for reaction to obtain crude alcohol gas; the crude alcohol gas in the reactor is sent in sequence into the heat exchanger and the water cooler for treatment and then into the crude alcohol separation tank for gas-liquid separation, and the liquid phase, i.e. product ethanol, is sent into the ethanol buffer tank.

7. The process for the treatment of the ethyl acetate hydrogenation light ends by-products according to claim 6, characterized in that, The molar ratio of the recycled hydrogen to the light components is (20-60):

1.

8. The process for the treatment of the ethyl acetate hydrogenation light ends by-products according to claim 6, characterized by the fact that, The internal reaction temperature of the reactor is 150-250℃, and the internal temperature difference of the reactor is less than or equal to 10℃; and / or, The internal pressure of the reactor is 2.0-6.0MpaG, and the internal pressure difference of the reactor is less than or equal to 0.1MpaG.

9. The process for the treatment of ethyl acetate hydrogenation light ends by-products according to claim 6, characterized in that, The product ethanol in the ethanol buffer tank is sent into the light component removal column, and the vapor at the top of the light component removal column is sent in sequence into the first condenser and the first reflux tank for treatment; the liquid phase is discharged from the bottom of the light component removal column, sent into the product column for treatment, and the vapor at the top of the product column is sent in sequence into the second condenser and the second reflux tank for treatment, and the product ethanol is discharged from the second reflux tank.

10. The process for the treatment of ethyl acetate hydrogenation light ends by-products according to claim 9, characterized in that, The pressure at the top of the light component removal column is 0.05-0.1MpaG; and / or, The vapor temperature at the top of the light component removal column is 90-100℃; and / or, The vapor at the top of the light component removal column is condensed to 50-60℃ after entering the first condenser; and / or, The pressure at the top of the product column is 0.02-0.1MpaG; and / or, The vapor temperature at the top of the product column is 58-60℃; and / or, The vapor at the top of the product column is condensed to 40-50℃ after entering the second condenser.

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