An apparatus and method for producing anhydrous alcohol using MVR and an atmospheric recovery column

Abstract

The application discloses a device and method for producing anhydrous alcohol by using MVR and an atmospheric recovery tower, and relates to the technical field of anhydrous alcohol preparation. The application introduces MVR vapor compression technology on the basis of an atmospheric recovery tower and a molecular sieve adsorption device, compresses and heats alcohol vapor generated at the top of the atmospheric recovery tower by using an MVR vapor compressor, so that the alcohol vapor forms superheated alcohol vapor meeting the requirements of molecular sieve adsorption dehydration, and the superheated alcohol vapor directly enters a molecular sieve adsorption system for dehydration treatment, thereby replacing a superheater device in a traditional process, reducing the use amount of external high-quality steam, enabling the recovery tower to operate under atmospheric pressure, and reducing steam consumption and operation cost of the system. Meanwhile, the application returns desorption dilute wine generated in a desorption regeneration process to the atmospheric recovery tower, so that the atmospheric recovery tower can not only evaporate and recover 95% alcohol, but also can perform re-purification treatment on low-concentration dilute wine generated after molecular sieve desorption.

Description

Technical Field

[0001] This invention relates to the field of anhydrous alcohol preparation technology, and in particular to an apparatus and method for producing anhydrous alcohol using an MVR and an atmospheric pressure recovery tower. Background Technology

[0002] Currently, with the adjustment of the global energy structure and the expansion of the domestic fuel ethanol market, anhydrous ethanol, as an important basic chemical raw material and clean fuel additive, has attracted widespread attention regarding its production scale and technological upgrading. Traditional anhydrous ethanol production processes often employ azeotropic distillation, extractive distillation, or molecular sieve adsorption dehydration methods. Among these, molecular sieve adsorption is widely used due to its advantages of good separation effect and high product purity. However, in conventional molecular sieve adsorption processes, it is usually necessary to heat the 95% (v / v) alcohol vapor at the top of the column through a superheater before it enters the molecular sieve adsorption system. For example, CN121422509A discloses an alcohol dehydration device, including an alcohol evaporator, a superheater, and a molecular sieve adsorption device connected in sequence. This process has high requirements for steam quality, and the overall distillation system has low thermal efficiency, resulting in significant energy waste. Therefore, reducing energy consumption and improving thermal efficiency in the anhydrous ethanol production process is key to achieving green and low-carbon production of anhydrous ethanol.

[0003] Mechanical vapor recompression (MVR) technology has gradually become a key path for energy-saving upgrades in anhydrous ethanol production in recent years due to its ability to compress and heat the vapor at the top of the column, improve its heat grade, and achieve energy recycling. Among existing technologies, CN120094230A discloses a fuel ethanol system combining MVR with three-tower differential pressure distillation. This patent mainly targets fermented mash as raw material, using differential pressure distillation and multi-stage thermal coupling between a negative pressure mash tower, an atmospheric pressure mash tower, and a pressurized refining tower to produce fuel ethanol while reducing the consumption of fuel steam and circulating water. Specifically, ethanol is gradually concentrated in the pressurized refining tower. When the ethanol reaches a concentration of 95% (v / v), it enters the pressurized refining tower MVR for compression, obtaining pressurized compressed alcohol vapor. This vapor then enters a molecular sieve adsorption device for adsorption and dehydration, and finally, after heat exchange in the negative pressure mash tower reboiler and mash preheater, fuel ethanol is obtained. Directly using this system to generate anhydrous ethanol would not only increase the number of towers, pressure equipment levels, and operational control complexity, but also make it difficult to match the heat recovery components, such as the negative pressure mash tower reboiler and mash preheater, with a separate anhydrous ethanol dehydration section. Furthermore, in existing molecular sieve dehydration processes, the low-concentration distillate produced by molecular sieve desorption and regeneration typically requires separate recovery, and the heat carried by the anhydrous ethanol vapor after dehydration cannot be recovered and utilized. This results in problems such as high steam consumption, long equipment processes, insufficient simplification of distillate recovery, and inadequate utilization of waste heat from the finished product vapor during anhydrous ethanol production.

[0004] Therefore, developing an energy-saving anhydrous alcohol production process that can effectively integrate MVR technology, reduce steam consumption, simplify the light alcohol recovery process, and adapt to lower steam quality requirements has significant technical necessity and industrial application value. Summary of the Invention

[0005] To address the aforementioned limitations of existing technologies, the present invention aims to provide an apparatus and method for producing anhydrous alcohol using an MVR (Mechanical Vapor Reduction) system and an atmospheric pressure recovery tower. Based on an atmospheric pressure recovery tower and a molecular sieve adsorption device, this invention introduces MVR vapor compression technology. The MVR vapor compressor compresses and heats the alcohol vapor generated at the top of the atmospheric pressure recovery tower, transforming it into superheated alcohol vapor that meets the dehydration requirements of molecular sieve adsorption. This superheated alcohol vapor then directly enters the molecular sieve adsorption system for dehydration, replacing the superheater equipment in traditional processes. This reduces the amount of external high-quality steam used, allowing the recovery tower to operate under atmospheric pressure, thus lowering system steam consumption and operating costs. Simultaneously, this invention recirculates the dilute alcohol produced during the desorption and regeneration process back to the atmospheric pressure recovery tower. This enables the atmospheric pressure recovery tower to not only evaporate and recover 95% alcohol but also to further purify the low-concentration dilute alcohol produced after molecular sieve desorption.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an apparatus for producing anhydrous alcohol using an MVR and an atmospheric pressure recovery tower, comprising an atmospheric pressure recovery tower, an MVR vapor compressor, and an adsorption unit connected in sequence. The bottom of the atmospheric pressure recovery tower is connected to a reboiler, the top of the adsorption device is connected to the reboiler, and the lower part of the reboiler is connected to the finished product storage tank via a condenser.

[0007] Preferably, the adsorption device includes a first adsorption device and a second adsorption device, which are arranged in parallel.

[0008] Furthermore, both the first adsorption device and the second adsorption device are molecular sieve adsorption devices, and both the first adsorption device and the second adsorption device are equipped with a superheated alcohol vapor inlet, a desorption vapor outlet and an anhydrous alcohol vapor outlet.

[0009] Furthermore, the superheated alcohol vapor inlet is connected to the outlet of the MVR vapor compressor via a pipeline. The pipeline is equipped with a desorption switching valve and a steam inlet switching valve, which are used to control the first adsorption device and the second adsorption device to alternately be in the adsorption dehydration state and the desorption regeneration state.

[0010] Furthermore, both the first adsorption device and the second adsorption device are molecular sieve adsorbers.

[0011] Furthermore, the anhydrous alcohol vapor outlet is connected to the inlet of the reboiler.

[0012] Furthermore, the outlet of the desorbed vapor is connected to the desorbed vapor condenser, and the condensate outlet of the desorbed vapor condenser is connected to the desorbed distillate reflux port in the middle of the atmospheric pressure recovery tower.

[0013] Furthermore, the steam inlet switching valve and the desorption switching valve are connected to the DCS control system, which is used to control the switching between the first adsorption device and the second adsorption device in the adsorption dehydration state and the desorption regeneration state.

[0014] A second aspect of the present invention provides a method for producing anhydrous alcohol using the above-described apparatus, comprising the following steps: After preheating, the alcohol is sent to an atmospheric pressure recovery tower for evaporation and recovery. The alcohol vapor generated at the top of the atmospheric pressure recovery tower is sent to an MVR vapor compressor for heating and pressurization to obtain superheated alcohol vapor. Superheated alcohol vapor is fed into an adsorption device in an adsorption and dehydration state to adsorb water and obtain anhydrous ethanol vapor. The anhydrous ethanol vapor is then fed into a reboiler for heat exchange treatment. After heat exchange, the anhydrous ethanol vapor enters a condenser for condensation treatment to obtain anhydrous alcohol product, which is then sent to a finished product storage tank. While the adsorption unit is adsorbing moisture, the adsorption unit in the desorption and regeneration stage is also desorbing and regenerating, generating low-concentration alcohol vapor. This vapor is then sent to the desorption vapor condenser for condensation to obtain dilute alcohol. The dilute alcohol is then fed into an atmospheric pressure recovery tower and mixed with preheated alcohol for further evaporation and recovery.

[0015] Preferably, the alcohol concentration is 92%-96% (v / v), and the temperature after preheating the alcohol is 70-90℃.

[0016] Preferably, the MVR vapor compressor heats the alcohol vapor to 120-140°C and pressurizes it to 0.2-0.3 MPa.

[0017] Preferably, the regeneration is performed at -0.094 MPa to -0.10 MPa.

[0018] The beneficial effects of this invention are: 1. This invention, based on an atmospheric pressure recovery tower and a molecular sieve adsorption device, introduces MVR vapor compression technology. The MVR vapor compressor compresses and heats the alcohol vapor generated at the top of the atmospheric pressure recovery tower, transforming it into superheated alcohol vapor that meets the dehydration requirements of molecular sieve adsorption. This superheated alcohol vapor then directly enters the molecular sieve adsorption system for dehydration. This replaces the superheater equipment in traditional processes, reduces the amount of external high-quality steam used, allows the recovery tower to operate under atmospheric pressure, and lowers system steam consumption and operating costs.

[0019] 2. This invention recirculates the dilute alcohol produced during the desorption and regeneration process to an atmospheric pressure recovery tower. This allows the atmospheric pressure recovery tower to not only evaporate and recover 95% alcohol but also to further purify the low-concentration dilute alcohol produced after molecular sieve desorption. Compared to the process of treating dilute alcohol using MVR combined with membrane separation, this invention eliminates the need for a separate, complex membrane separation system. Alcohol evaporation and dilute alcohol recovery can be completed solely using the atmospheric pressure recovery tower, thereby reducing equipment requirements and lowering system investment and maintenance costs.

[0020] 3. This invention introduces the anhydrous alcohol vapor obtained after dehydration via molecular sieve adsorption into the reboiler of the recovery tower. Through indirect heat exchange between the reboiler and the material at the bottom of the atmospheric pressure recovery tower, the anhydrous alcohol vapor provides an evaporation heat source for the atmospheric pressure recovery tower while simultaneously condensing the finished product. This method achieves heat recovery and utilization of the high-temperature anhydrous alcohol vapor after dehydration, reduces the reboiler's demand for external steam, and further improves the system's thermal efficiency. Attached Figure Description

[0021] Figure 1 Diagram of an apparatus for producing anhydrous alcohol using MVR and an atmospheric pressure recovery tower.

[0022] In the diagram, 1-atmospheric pressure recovery tower, 2-MVR steam compressor, 3-first adsorption unit, 4-second adsorption unit, 5-reboiler, 6-condenser, 7-desorption steam condenser. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0025] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0026] Example 1: This embodiment provides an apparatus for producing anhydrous alcohol, such as... Figure 1 As shown, it includes an atmospheric pressure recovery tower 1, an MVR steam compressor 2, and an adsorption device connected in sequence; the bottom of the atmospheric pressure recovery tower 1 is connected to a reboiler 5, the top of the adsorption device is connected to the reboiler 5, and the lower part of the reboiler 5 is connected to the finished product storage tank via a condenser 6. The top of the atmospheric pressure recovery tower 1 is provided with a steam outlet, which is connected to the inlet of the MVR steam compressor 2 through a pipeline; The adsorption device includes a first adsorption device 3 and a second adsorption device 4, which are arranged in parallel. Both are molecular sieve adsorption devices. The first adsorption device 3 and the second adsorption device 4 are each provided with a superheated alcohol vapor inlet, a desorption vapor outlet and an anhydrous alcohol vapor outlet. The superheated alcohol vapor inlets of the first adsorption device 3 and the second adsorption device 4 are connected to the outlet of the MVR steam compressor 2 through pipelines. The pipelines are equipped with a desorption switching valve and a steam inlet switching valve. The desorption switching valve and the steam inlet switching valve are connected to the DCS control system to control the first adsorption device 3 and the second adsorption device 4 to alternately be in the adsorption dehydration state and the desorption regeneration state. The anhydrous alcohol vapor outlets on the first adsorption device 3 and the second adsorption device 4 are connected to the reboiler 5 via pipes; the desorption vapor outlet is connected to the desorption vapor condenser 7, and the condensate outlet of the desorption vapor condenser 7 is connected to the desorption distilled liquor reflux outlet in the middle of the atmospheric pressure recovery tower 1.

[0027] Example 2: This embodiment provides a method for producing anhydrous alcohol using the apparatus in Embodiment 1, including the following steps: After 95% (v / v) alcohol is preheated to 80°C, it is fed into the upper part of atmospheric pressure recovery tower 1. Under the action of the indirect heat source provided by reboiler 5, it is evaporated and recovered. The alcohol vapor generated in atmospheric pressure recovery tower 1 is discharged from the top steam outlet and sent into MVR steam compressor 2 through the inlet of MVR steam compressor 2. It is pressurized to 0.25MPa and heated to 130°C to obtain superheated alcohol vapor. Under the action of the steam inlet switching valve, superheated alcohol vapor enters the first adsorption device 3, which is in the adsorption and dehydration state, through the hot alcohol vapor inlet to adsorb water and obtain anhydrous ethanol vapor. At the same time, under the action of the desorption switching valve, the second adsorption device 4 is in the desorption and regeneration state. The desorption switching valve and the steam inlet switching valve are connected to the DCS control system to control the first adsorption device 3 and the second adsorption device 4 to alternately be in the adsorption and dehydration state and the desorption and regeneration state. The desorption and regeneration is carried out at -0.098MPa. Anhydrous ethanol vapor enters reboiler 5 through the anhydrous ethanol vapor outlet of the first adsorption device 3. The anhydrous ethanol vapor provides part of the evaporation heat source for the atmospheric pressure recovery tower while cooling and condensing itself. The condensed anhydrous ethanol is discharged through the lower part of reboiler 5 and sent to condenser 6 for further cooling before entering the finished product storage tank to obtain the finished anhydrous ethanol product. The adsorbed water and a small amount of alcohol in the second adsorption device 4 are desorbed and regenerated to produce low-concentration alcohol vapor. The low-concentration alcohol vapor is discharged through the desorbed vapor outlet and enters the desorbed vapor condenser 7, where it is condensed to obtain dilute alcohol. The generated dilute alcohol is sent to the atmospheric pressure recovery tower 1 through the condensate outlet of the desorbed vapor condenser 7 and the desorbed dilute alcohol return port of the atmospheric pressure recovery tower 1, where it is mixed with the preheated alcohol and further evaporated and recovered. Calculations show that, compared to the superheater equipment in traditional processes, the device of this invention, which uses MVR and an atmospheric pressure recovery tower to produce anhydrous alcohol, can reduce steam consumption by 100-200 kg per ton of anhydrous alcohol.

[0028] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An apparatus for producing anhydrous alcohol using MVR and an atmospheric pressure recovery tower, characterized in that, It includes an atmospheric pressure recovery tower, an MVR steam compressor, and an adsorption unit connected in sequence; the bottom of the atmospheric pressure recovery tower is connected to a reboiler, the top of the adsorption unit is connected to the reboiler, and the lower part of the reboiler is connected to the finished product storage tank via a condenser.

2. The apparatus for producing anhydrous alcohol using MVR and an atmospheric pressure recovery tower as described in claim 1, characterized in that, The adsorption device includes a first adsorption device and a second adsorption device, which are connected in parallel. Both the first and second adsorption devices are molecular sieve adsorption devices, and both are equipped with a superheated alcohol vapor inlet, a desorption vapor outlet, and an anhydrous alcohol vapor outlet.

3. The apparatus for producing anhydrous alcohol using MVR and an atmospheric pressure recovery tower as described in claim 2, characterized in that, The superheated alcohol vapor inlet is connected to the outlet of the MVR vapor compressor via a pipeline. The pipeline is equipped with a desorption switching valve and a steam inlet switching valve. The desorption switching valve and the steam inlet switching valve are used to control the first adsorption device and the second adsorption device to alternately be in the adsorption dehydration state and the desorption regeneration state.

4. The apparatus for producing anhydrous alcohol using MVR and an atmospheric pressure recovery tower as described in claim 3, characterized in that, The anhydrous alcohol vapor outlet is connected to the reboiler inlet; The outlet of the desorbed vapor is connected to the desorbed vapor condenser, and the condensate outlet of the desorbed vapor condenser is connected to the desorbed distillate reflux port in the middle of the atmospheric pressure recovery tower.

5. The apparatus for producing anhydrous alcohol using MVR and an atmospheric pressure recovery tower as described in claim 2, characterized in that, Both the first adsorption device and the second adsorption device are molecular sieve adsorbers.

6. A method for producing anhydrous alcohol using the apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: After preheating, the alcohol is sent to an atmospheric pressure recovery tower for evaporation and recovery. The alcohol vapor generated at the top of the atmospheric pressure recovery tower is sent to an MVR vapor compressor for heating and pressurization to obtain superheated alcohol vapor. Superheated alcohol vapor is fed into an adsorption device in an adsorption and dehydration state to adsorb water and obtain anhydrous ethanol vapor. The anhydrous ethanol vapor is then fed into a reboiler for heat exchange treatment. After heat exchange, the anhydrous ethanol vapor enters a condenser for condensation treatment to obtain anhydrous alcohol product, which is then sent to a finished product storage tank. While the adsorption unit is adsorbing moisture, the adsorption unit in the desorption and regeneration stage is also desorbing and regenerating, generating low-concentration alcohol vapor. This vapor is then sent to the desorption vapor condenser for condensation to obtain dilute alcohol. The dilute alcohol is then fed into an atmospheric pressure recovery tower, where it is mixed with preheated alcohol and evaporated and recovered again.

7. The method for producing anhydrous alcohol as described in claim 6, characterized in that, The alcohol concentration is 92%-96% (v / v), and the temperature of the alcohol after preheating is 70-90℃.

8. The method for producing anhydrous alcohol as described in claim 6, characterized in that, The MVR vapor compressor heats the alcohol vapor to 120-140℃ and pressurizes it to 0.2-0.3MPa.

9. The method for producing anhydrous alcohol as described in claim 6, characterized in that, The regeneration was performed at -0.094 MPa to -0.10 MPa.

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