Alcohol distillation and purification system

Abstract

The invention discloses an alcohol distillation and purification system, belongs to distillation and purification of alcohol in the technical field of alcohol production, and aims to solve the technical problems that in the prior art, the content of methanol and n-propanol in finished edible alcohol exceeds standard values, and the quality of the finished product is low. Comprising a crude tower, an aldehyde removal tower, a water washing tower, a rectifying tower, a methanol removal tower, a recovery tower, an industrial alcohol purification tower and an industrial alcohol storage tank, the crude tower, the aldehyde removal tower, the water washing tower, the rectifying tower and the methanol removal tower are sequentially connected, and impurity outlets of the crude tower, the aldehyde removal tower, the water washing tower, the rectifying tower and the methanol removal tower are all connected with the recovery tower; low-concentration industrial alcohol in the recovery tower is input into an industrial alcohol purification tower, pure high-concentration alcohol output from the upper part of the industrial alcohol purification tower is conveyed to an aldehyde removal tower and a rectifying tower, high-concentration industrial alcohol output from the upper part of the industrial alcohol purification tower is conveyed to an industrial alcohol storage tank, and hot water output from the bottom of the industrial alcohol purification tower is conveyed to a water washing tower. The system can reduce the content of isoamyl alcohol, isobutanol and n-propyl alcohol in a finished product and improve the quality of the finished product.

Description

Technical Field

[0001] The invention belongs to the technical field of alcohol production, relates to the distillation and purification of alcohol, and in particular to an alcohol distillation and purification system. Background Art

[0002] In the alcohol production process, differences in fermentation technology, control level and equipment will lead to differences in the yeast metabolites produced during the fermentation process and their yields, so they need to be distilled and purified.

[0003] The mainstream domestic premium alcohol distillation unit is mainly composed of six towers, namely, crude tower, aldehyde removal tower, water washing tower, rectification tower, methanol removal tower, and recovery tower. After the mature fermented mash extracts alcohol through the crude tower, it enters the aldehyde tower to remove low-boiling impurities, then enters the water washing tower to reduce the degree and extract the intermediate impurities, then enters the distillation tower for distillation and purification, and finally enters the methanol removal tower to remove methanol to reach qualified products. The recovery tower is used as an intermediate impurity extraction tower to extract the by-product fusel oil.

[0004] The invention patent application with application number 201910805633.2 discloses a distillation tower that does not require the extraction of industrial alcohol, which includes a crude tower, an aldehyde tower, a water washing tower, a fine tower, a methanol tower and a recovery tower. The crude tower, aldehyde tower, water washing tower, fine tower and methanol tower are connected in sequence, and the recovery tower is connected to the crude tower, aldehyde tower, water washing tower, fine tower and methanol tower. Some impurities in the crude tower, aldehyde tower, water washing tower, fine tower and methanol tower enter the recovery tower, and some impurities in the recovery tower are transported to the aldehyde tower and the water washing tower for further purification. At the same time, the height of each tower and the height of the wine taking port are increased, and the indicators of each tower and the feeding, wine collection, impurity extraction and impurity removal positions are accurately controlled, which solves the problem that in the existing alcohol production process, a certain amount of industrial alcohol needs to be extracted to meet national standards for the production of high-grade alcohol, which wastes alcohol and heat to a certain extent.

[0005] With the release and implementation of the new GBT10343-2023 edible alcohol standard, the quality requirements for edible alcohol have been raised again, and higher requirements have been placed on the physical and chemical indicators of the products (n-propanol) in the distillation section.

[0006] If the distillation tower of the invention patent application No. 201910805633.2 continues to be used, then in order to ensure product quality, the distillation device in the production workshop can only operate at a lower feed flow rate and reduce output. At the same time, it is necessary to produce ≤2% industrial alcohol to ensure that the physical and chemical indicators meet the standards (especially the content of n-propanol and methanol). Otherwise, the methanol and n-propanol content in the finished edible alcohol will exceed the standard value, and it will be difficult to meet the standard requirements of the new national standard GBT10343-2023.

[0007] Therefore, it is necessary to provide a new alcohol distillation and purification system to reduce the methanol content in the finished product and improve the quality of the finished product. Summary of the invention

[0008] The purpose of the present invention is to provide an alcohol distillation and purification system in order to solve the technical problems in the prior art that the contents of methanol and n-propanol in finished edible alcohol exceed the standard values ​​and the quality of the finished product is low.

[0009] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions: An alcohol distillation and purification system comprises a crude tower, an aldehyde removal tower, a water washing tower, a rectifying tower, a methanol removal tower and a recovery tower, wherein the crude tower, the aldehyde removal tower, the water washing tower, the rectifying tower and the methanol removal tower are connected in sequence, and impurity outlets of the crude tower, the aldehyde removal tower, the water washing tower, the rectifying tower and the methanol removal tower are all connected to the recovery tower; It also includes an industrial alcohol purification tower and an industrial alcohol storage tank; the low-concentration industrial alcohol in the distillation tower and / or the recovery tower is input into the industrial alcohol purification tower, the pure high-concentration alcohol output from the upper part of the industrial alcohol purification tower is transported to the dealdehyde tower and the distillation tower, the high-concentration industrial alcohol output from the upper part of the industrial alcohol purification tower is transported to the industrial alcohol storage tank, and the hot water output from the bottom of the industrial alcohol purification tower is transported to the water washing tower.

[0010] Furthermore, the industrial alcohol purification tower includes a skirt and a shell installed on the skirt. The shell includes a tower kettle, a distillation section, a rectification section, and a tower top head arranged in sequence from bottom to top. Low-concentration industrial alcohol is input into the distillation section.

[0011] Furthermore, the distillation section includes a plurality of tower plates stacked in the outer shell, a weir plate is arranged on one side of the tower plate, a number of holes are evenly distributed on the tower plate, a cofferdam is arranged at the position corresponding to each hole on the tower plate, and the cofferdam surrounds the corresponding hole; each hole is equipped with a float plug, and the float plug is supported on the hole of the tower plate through the cofferdam.

[0012] Furthermore, the floating plug is a frustum that is larger at the top and smaller at the bottom.

[0013] Furthermore, a plurality of air inlets are provided on the conical surface of the float plug, and a plurality of air outlets are provided on the top surface of the float plug, and the air inlets are connected to the air outlets in a one-to-one correspondence.

[0014] Furthermore, the high-concentration industrial alcohol (containing a large amount of impurities) output from the industrial alcohol storage tank is directly sold. The beneficial effects of the present invention are as follows: 1. In the present invention, an industrial alcohol purification tower is added on the basis of the original six towers. The high-concentration alcohol obtained in the industrial alcohol purification tower is mainly refluxed to the dealdehyde tower, and a small amount is refluxed to the distillation tower; by refluxing most of the high-concentration alcohol to the dealdehyde tower, the overall alcohol concentration of the solution in the dealdehyde tower can be greatly improved. The higher the alcohol concentration, the easier it is for low-boiling impurities such as acetaldehyde to gather in the high-concentration area, which is more conducive to separating low-boiling impurities such as acetaldehyde, ethyl acetate, and methyl acetate; by refluxing a small amount of high-concentration alcohol to the distillation tower, the alcohol concentration in the distillation tower is also improved. The higher the alcohol concentration, the more methanol is refined. The larger the distillation coefficient, the more methanol will accumulate at the top of the distillation tower, so that the methanol content of the semi-finished alcohol extracted from the top of the distillation tower will be lower, which is beneficial to the removal of methanol; the high-temperature wastewater at the bottom of the industrial alcohol purification tower returns to the top of the water washing tower, reducing the alcohol concentration of the alcohol solution at the top of the water washing tower. According to the separation characteristics of isoamyl alcohol and isobutanol, the lower the concentration, the easier it is to accumulate at the top of the water washing tower, which is more conducive to extracting fusel oil (the main components are isoamyl alcohol, isobutanol, and n-propanol) from the reflux liquid at the top of the water washing tower, reducing the content of isoamyl alcohol, isobutanol, and n-propanol in the finished product, reducing the methanol content in the finished product, and improving the quality of the finished product.

[0015] 2. In the present invention, a floating plug is provided on the hole on the tower plate of the stripping section, and a plurality of communicating air inlets and air outlets are provided on the floating plug; when the air pressure is low, the gas phase passes through the tower plate through the channel on the floating plug; when the air pressure is high, the floating plug is lifted up, and the gas phase can also pass through the tower plate through the gap between the floating plug and the hole; the floating plug can float according to the air pressure, thereby increasing the gas-liquid contact while avoiding liquid leakage, thereby improving the distillation efficiency and separation purity of the stripping tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a structural schematic diagram of the industrial alcohol purification tower in the present invention; Figure 3 It is a schematic diagram of the structure of the tower plate in the present invention; Figure 4 It is a schematic diagram of the structure of the tower plate in the present invention; Figure 5 It is a structural schematic diagram of the floating plug in the present invention.

[0017] Among them, the accompanying drawings are marked as follows: 1-crude tower; 2-aldehyde removal tower; 3-water washing tower; 4-distillation tower; 5-methanol removal tower; 6-recovery tower; 7-industrial alcohol purification tower; 8-industrial alcohol storage tank; 71-skirt; 72-bottom; 73-stripping section; 74-shell; 75-distillation section; 76-tower top head; 731-tower plate; 732-weir plate; 733-hole; 734-floating plug; 735-cofferdam; 736-air inlet; 737-air outlet. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0019] Therefore, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0020] Example 1 The present embodiment provides an alcohol distillation and purification system, which is used to purify a large flow of low-concentration industrial alcohol discharged from a recovery tower, thereby improving the quality of the final finished alcohol product to meet the relevant requirements of the new standard.

[0021] The system includes a crude tower 1, an aldehyde removal tower 2, a water washing tower 3, a distillation tower 4, a methanol removal tower 5, a recovery tower 6, an industrial alcohol purification tower 7, and an industrial alcohol storage tank 8. Among them, the crude tower 1, the aldehyde removal tower 2, the water washing tower 3, the distillation tower 4, and the methanol removal tower 5 are connected in sequence, and the crude tower 1, the aldehyde removal tower 2, the water washing tower 3, the distillation tower 4, and the methanol removal tower 5 are respectively connected to the recovery tower 6, and the recovery tower 6 is then connected to the industrial alcohol purification tower 7. First, the industrial alcohol purification tower 7 is connected to the aldehyde removal tower 2 and the distillation tower 4 to reflux high-concentration alcohol to the aldehyde removal tower 2 and the distillation tower 4, and second, the industrial alcohol purification tower 7 is also connected to the industrial alcohol storage tank 8 to transport the high-concentration industrial alcohol to the industrial alcohol storage tank 8 for storage.

[0022] Crude tower 1 is the first step of distilling alcohol. The mature mash passes through the heat exchanger and enters crude tower 1 for preliminary distillation, and the waste lees are discharged from the bottom of crude tower 1. At the same time, the wine is taken from the upper end of crude tower 1 through the condenser and enters the dealdehyde tower 2. Impurities with a boiling point higher than that of alcohol are discharged from the lower end together with the waste lees from the bottom of crude tower 1.

[0023] The aldehyde removal tower 2 is the second step of distilling alcohol. The crude wine from the crude tower 1 enters the aldehyde removal tower 2 after passing through the heat exchanger. The wine is taken from the bottom of the aldehyde removal tower 2 and enters the water washing tower 3. Impurities below the boiling point of alcohol, such as aldehydes, are discharged from the top of the aldehyde removal tower 2. The water washing tower 3 is the third step of distilling alcohol. The dealdehyde wine coming out of the dealdehyde tower 2 is passed into the water washing tower 3 after passing through a heat exchanger. During operation, dilution water is passed into the water washing tower 3 to dilute the alcohol and remove the fusel oil by dilution. Distillation tower 4 is the fourth step of distilling alcohol. Compared with crude tower 1 and dealdehyde tower 2, the temperature control in distillation tower 4 is more precise, so that the stripping section at the bottom can further separate impurities with a slightly higher boiling point than alcohol, and the condenser in the upper distillation section will discharge some impurities with a boiling point slightly lower than alcohol by condensing alcohol vapor. Alcohol is taken from the plates in the pasteurization zone at the top of distillation tower 4, so that relatively pure alcohol can be obtained.

[0024] The methanol removal tower 5 is used to remove the methanol contained in the alcohol. The alcohol from the distillation tower 4 is introduced into the methanol removal tower 5. Since methanol and ethanol have similar physical and chemical properties, they are difficult to remove. In the methanol removal tower 5, the temperature is controlled between the boiling point of methanol 64.7°C and the boiling point of ethanol 78°C, so that the methanol impurity can be effectively separated. The bottom of the methanol removal tower 5 is connected to a cooler to directly take out the finished alcohol product. The recovery tower 6 collects alcohol rich in impurities, mainly alcohol containing impurities in the dealdehyde tower 2 and the distillation tower 4.

[0025] Industrial alcohol purification tower 7 is used to purify the low-concentration industrial alcohol in the recovery tower 6, and it can be a tower plate or a packed tower. The impure wine (low-concentration industrial alcohol, whose n-propanol content is about 80,000 ppm) in the distillation tower 4 and / or the recovery tower 6 is transported to the industrial alcohol purification tower 7 for purification treatment, and pure high-concentration alcohol is extracted from the upper part of the industrial alcohol purification tower 7. The pure high-concentration alcohol extracted from the upper part of the industrial alcohol purification tower 7 will be transported to the dealdehyde tower 2 and the distillation tower 4 (wherein a large amount of pure high-concentration alcohol is transported to the dealdehyde tower 2, and a small amount of pure high-concentration alcohol is transported to the distillation tower 4), and the high-concentration industrial alcohol output from the upper part of the industrial alcohol purification tower 7 is transported to the industrial alcohol storage tank 8 for storage, and the hot water output from the bottom of the industrial alcohol purification tower 7 is transported to the water washing tower 3 for reuse. In addition, the diameter of the industrial alcohol purification tower 7 is designed to be 500-800mm according to the production capacity. It adopts indirect heating by a reboiler. The heat source can be flash heating of condensed water, flash steam or distillation wastewater. The power consumption of the feed pump is 1.5kw, the power consumption of the discharge pump is 1.5kw, the power consumption of the reflux pump is 3kw, the total power consumption is 6kw, and the circulating water volume is 50m³.

[0026] The industrial alcohol storage tank 8 is used to store the purified and separated industrial alcohol.

[0027] In this embodiment, in the distillation tower 4 and / or the recovery tower 6, the 3 / hour flow rate to extract impure wine (wherein, the n-propanol content is about 80,000 ppm), enter the industrial alcohol purification tower 7 for purification treatment, the alcohol concentration of the pure high-concentration alcohol extracted from the upper part of the industrial alcohol purification tower 7 is ≥96% (v / v), and the n-propanol content is ≤500ppm, and the purified high-concentration alcohol is returned to the dealdehyde tower 2 (main) and the distillation tower 4. After a large amount of high-concentration alcohol returns to the middle and lower part of the dealdehyde tower 2, the overall alcohol concentration of the solution in the tower is increased; according to research, when the alcohol concentration is 60% (v / v), the distillation coefficient of acetaldehyde is 3.08; when the alcohol concentration is 80% (v / v), the distillation coefficient of acetaldehyde is 3.34, that is, the higher the alcohol concentration, the easier it is for low-boiling impurities such as acetaldehyde (commonly known as head-level impurities) to gather in the high-concentration area (tower top), which is more conducive to the separation of low-boiling impurities such as acetaldehyde, ethyl acetate, and methyl acetate. A small amount of high-concentration alcohol returns to the middle of the distillation tower 4, which increases the alcohol concentration in the distillation tower 4; after research, when the alcohol concentration is higher than 40% (v / v), the higher the alcohol concentration, the greater the distillation coefficient of methanol, and methanol gathers at the top of the distillation tower 4. The methanol content of the semi-finished alcohol extracted from the top of the distillation tower 4 is lower, so it is beneficial to remove methanol. The impurity-rich material discharged from the bottom of the industrial alcohol purification tower 7 enters the circulation tank, and is repeatedly recycled and purified until the concentration is reduced to below 16% (v / v), and then industrial alcohol is extracted. The high-temperature wastewater at the bottom of the industrial alcohol purification tower 7 returns to the top of the water washing tower 3, reducing the alcohol concentration of the solution at the top of the water washing tower 3; after research, the lower the alcohol concentration, the easier it is to gather at the top of the water washing tower, and the more conducive it is to extract fusel oil (mainly composed of isoamyl alcohol, isobutanol, and n-propanol) from the reflux liquid at the top of the water washing tower, reducing the content of isobutanol and isoamyl alcohol in the finished product.

[0028] Example 2 On the basis of Example 1, this example provides an industrial alcohol purification tower 7 that specifically adopts a tray structure.

[0029] The industrial alcohol purification tower 7 includes a skirt 71, which can be placed on the ground. A shell 74 is installed on the skirt 71, and the shell 74 is cylindrical. The shell 74 includes a tower kettle 72, a distillation section 73, a rectification section 75, and a tower top head 76 arranged in sequence from bottom to top. Among them, low-concentration industrial alcohol is input into the distillation section 73, hot water is output from the bottom of the tower kettle 72, and high-concentration alcohol and high-concentration industrial alcohol are output from different height positions below the tower top head 76.

[0030] The stripping section 73 includes a plurality of tower plates 731 stacked in a shell 74, and the plurality of tower plates 731 are arranged on the left and right in the length direction of the shell 74. A weir plate 732 is arranged on one side of the tower plate 731, and a plurality of holes 733 are evenly distributed on the tower plate 731. A cofferdam 735 is arranged at a position corresponding to each hole 733 on the tower plate 731, and the cofferdam 735 surrounds the corresponding hole 733; each hole 733 is equipped with a floating plug 734, and the floating plug 734 is supported on the hole 733 of the tower plate 731 through the cofferdam 735.

[0031] The floating plug 734 is a round cone with a larger top and a smaller bottom.

[0032] A plurality of air inlets 736 are formed on the conical surface of the float plug 734 , and a plurality of air outlets 737 are formed on the top surface of the float plug 734 . The air inlets 736 are connected to the air outlets 737 in a one-to-one correspondence.

[0033] During use, when the gas phase pressure is relatively small, the gas phase below the tower plate will pass through the tower plate through the air inlet 736 on the float 734 and the air outlet 737 on the float 734; when the gas phase pressure increases, the strong air pressure will lift the float 734, and part of the gas phase can also pass through the tower plate through the gap between the float 734 and the hole 733 (under the action of strong pressure, the liquid phase will not leak down through the gap and cause leakage); when the gas phase pressure is greater, the gap between the float 734 and the hole 733 will also be larger, and no leakage will be caused during the escape of the gas phase.

[0034] The float can float according to the air pressure, increase the gas-liquid contact while avoiding leakage, and improve the distillation efficiency and separation purity of the distillation tower. In addition, this solution effectively solves the problem of separating intermediate impurities in the distillation tower, especially n-propanol, which is soluble in water and alcohol. It is difficult to separate in a mixed state and can only be carried out by isoamyl alcohol and isobutanol extraction. However, this method cannot completely solve the problem. If it accumulates too much in the system, it will affect the quality and production capacity; it can help reduce the methanol content in the finished product, which is more conducive to the extraction of fusel oil by the system; it can promote the removal of head-level impurities such as acetaldehyde and increase the oxidation time of the finished product; it can give full play to the production capacity of the device and reduce the unit consumption (water, electricity and gas) per ton of alcohol; it can create higher value and reduce the economic loss of industrial alcohol.

[0035] The adoption of this solution can generate huge economic benefits. Take a distillation and purification system with a production capacity of 100,000 tons as an example to illustrate: The existing process has a crude tower diameter of 3.2m, and an annual production capacity of 100,000 tons of edible premium alcohol based on 300 days. The extraction of industrial alcohol at 2% is 2,000 tons, and the alcohol consumption per ton is 1.95 tons.

[0036] After the improvement, the diameter of the crude tower is 3.2m, and the annual production capacity is 112,500 tons based on 300 days. The industrial alcohol extracted is 337.5 tons at 3‰, and the alcohol consumption per ton is 1.8 tons.

[0037] Creating value: Industrial alcohol reduced by 2000-337.5=1662.5 tons; The current market price of edible alcohol minus the value of industrial alcohol (5700-4500)*1662.5=1.995 million yuan; Steam saving: 0.15 tons * 130 yuan * 100,000 tons = 1.95 million; The value of the increase in output is 12,500*200 yuan (profit per ton of wine) = 2.5 million yuan; A set of 100,000-ton equipment will increase annual revenue by 6.445 million yuan, with significant economic benefits.

Claims

1. An alcohol distillation and purification system, comprising a crude tower (1), an aldehyde removal tower (2), a water washing tower (3), a distillation tower (4), a methanol removal tower (5) and a recovery tower (6), wherein the crude tower (1), the aldehyde removal tower (2), the water washing tower (3), the distillation tower (4) and the methanol removal tower (5) are connected in sequence, and impurity outlets of the crude tower (1), the aldehyde removal tower (2), the water washing tower (3), the distillation tower (4) and the methanol removal tower (5) are all connected to the recovery tower (6); characterized in that: The method further comprises an industrial alcohol purification tower (7) and an industrial alcohol storage tank (8); the low-concentration industrial alcohol in the distillation tower (4) and / or the recovery tower (6) is input into the industrial alcohol purification tower (7); the pure high-concentration alcohol output from the upper part of the industrial alcohol purification tower (7) is transported to the dealdehyde tower (2) and the distillation tower (4); the high-concentration industrial alcohol output from the upper part of the industrial alcohol purification tower (7) is transported to the industrial alcohol storage tank (8); and the hot water output from the bottom of the industrial alcohol purification tower (7) is transported to the water washing tower (3).

2. An alcohol distillation and purification system as claimed in claim 1, characterized in that: The industrial alcohol purification tower (7) comprises a skirt (71) and a shell (74) mounted on the skirt (71). The shell (74) comprises a tower kettle (72), a stripping section (73), a rectifying section (75), and a tower top cover (76) arranged in sequence from bottom to top. Low-concentration industrial alcohol is input into the stripping section (73).

3. An alcohol distillation and purification system as claimed in claim 2, characterized in that: The stripping section (73) includes a plurality of tower plates (731) stacked in a shell (74), a weir plate (732) being provided on one side of the tower plate (731), a plurality of holes (733) being evenly distributed on the tower plate (731), a cofferdam (735) being provided at a position corresponding to each hole (733) on the tower plate (731), and the cofferdam (735) enclosing the corresponding hole (733); each hole (733) is provided with a floating plug (734), and the floating plug (734) is supported on the hole (733) of the tower plate (731) through the cofferdam (735).

4. An alcohol distillation and purification system as claimed in claim 2, characterized in that: The floating plug (734) is a round table with a larger top and a smaller bottom.

5. An alcohol distillation and purification system as claimed in claim 4, characterized in that: A plurality of air inlets (736) are provided on the conical surface of the float plug (734), and a plurality of air outlets (737) are provided on the top surface of the float plug (734). The air inlets (736) are connected to the air outlets (737) in a one-to-one correspondence.

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