JPH057990B2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an ethanol purification device.

Ethanol purification equipment is used to obtain purified ethanol by removing various organic and inorganic solids from fermentation mash and crude distilled alcohol, and further separating water, fusel oil, aldehydes, methanol, and other trace impurities. Ru. Typical examples of such ethanol purification equipment include mortar towers, concentration towers,
It is well known that there are allospass and super allospass systems that consist of a large number of distillation columns, such as first and second extraction, rectification columns, purification columns, impurity treatment columns, etc. (Fermentation Association ``Alcohol Handbook'' published by Asakura Shoten, ``Distillation Engineering Handbook'' published by Asakura Shoten, etc.).

By the way, the above-mentioned ethanol purification equipment, for example,
To obtain 1Kl of 96V% purified ethanol, it takes about 4.5 to 5.0 tons of steam from waste precision fermentation mash.
It is also an energy-intensive device, requiring approximately 2.0 to 4.0 tons of steam from crude distilled alcohol. Therefore, for a long time, efforts have been made to save energy by taking general measures such as increasing the number of stages in each distillation column built into the apparatus and reducing the reflux ratio.

However, in reality, such general measures have almost been completed, and there is a strong demand in the industry for the emergence of ethanol purification equipment that takes drastic measures that can further save energy.

The present invention relates to an ethanol purification device that meets the above requirements.

<Prior art and its problems> Conventionally, in addition to the general measures described above, various energy saving measures have been proposed for ethanol purification equipment, such as the following, but each has its own problems.

First, there is the double or multiple effect method (Jikko Kosho 57
−2002). This is a method in which the ethanol-containing vapor at the top of the distillation column on the high pressure side is used as a heating source for the distillation column on the low pressure side. However, this method has the problem that the vapor-liquid equilibrium of ethanol/water changes in the pressurized distillation column, the azeotropic point shifts, the ethanol concentration in the distillate becomes diluted, and the separation of fusel oil etc. becomes poor. There is a point. Further, in a distillation column operated at low pressure, there are problems such as increasing the diameter and height of the column in order to prevent pressure loss and securing low-temperature cooling water, and requiring new installation of corresponding distillation equipment itself.

Next, there is the MVR (mechanical vapor recompression) method (Special Publication No. 1987-35877).
This is a method in which the ethanol-containing vapor at the top of the distillation column is directly pressurized and heated by a compressor, and this is indirectly heat-exchanged with the bottom liquid of the distillation column. However, this method requires a temperature difference of approximately 15°C between the top and bottom of the tower.
If this is the case, two-stage compression is required, which is uneconomical, and there are problems such as leakage of ethanol-containing vapor from the shaft seal and contamination.

Furthermore, there is an absorption heat pump method (magazine "Kagaku-ki", August 1984 issue). In this method, the first type is used. However, this method requires a large amount of cooling water, has problems such as corrosion caused by the heat medium lithium bromide, and heat balance measures for the evaporator and regenerator. Another example is a compression heat pump system, but this system uses an organic solvent such as chlorofluorocarbon under pressure as a medium, which poses safety problems.

All of the conventional methods exemplified above are
In principle, one system should be used for one distillation column, so applying this system to each of a large number of distillation columns, such as an ethanol purification device, requires
In terms of economic disadvantage and significant complexity of the overall device,
There is a limit.

<Problems to be Solved by the Invention and Means for Solving the Problems> The present invention solves the problems of the conventional method as described above, and provides an ethanol purification device that can meet the above-mentioned demands, that is, can achieve further energy savings. It is.

Therefore, the present invention provides an ethanol purification system using the Allospass method or the Super Allospass method, in which ethanol is discharged from the top of two or more distillation columns selected from a concentration column, a rectification column, a purification column, and the like. Relating to an ethanol purification device that collects reduced pressure steam that has indirectly recovered heat from contained steam, pressurizes and raises the temperature of the collected reduced pressure steam using a screw steam heat pump, and uses this as a heat source for the purification device. .

Hereinafter, the configuration of the present invention will be explained in more detail with reference to the drawings, while comparing it with a conventional typical example of the super allopath system.

FIG. 1 is an overall view illustrating a conventional ethanol purification apparatus using the super allopath system. Moromi tower A, initial distillation tower A ₁ , concentration tower A ₂ , hot water tower F, first extraction tower D, second extraction tower D ₁ , rectification tower B, de-alcoholic distillation tower B ₁ ,
The purification column C and the impurity treatment column G are connected as is well known, and for example, the fermented mash, which is the raw material supplied to the initial distillation column _A1 , passes through each of the above-mentioned distillation columns in turn and is gradually purified. The structure is such that purified ethanol is finally recovered from the purification column C. In the case of the drawing, water vapor, which is a heating source, is supplied from the bottom of each of the mortar tower A, hot water tower F, first extraction tower D, second extraction tower D ₁ , de-alcoholizing tower B ₁ and impurity treatment tower G. (S ₁ to _{S 6} in the figure). Then, a concentration column A ₂ , a second extraction column D ₁ , a rectification column B, a purification column C, and an impurity treatment column G
Condensers 11 to 15 are attached to the top of each of the towers, and the ethanol-containing vapor discharged from the top of each of these towers is appropriately condensed by indirectly exchanging heat with cooling water.

According to the conventional super allos pass method, the retained heat of the ethanol-containing steam discharged from the top of each tower is not fully utilized, and the previously proposed methods that attempt to utilize this have their own problems. This is as stated above.

The present invention solves this problem while appropriately using the above-mentioned retained heat as a heating source for each distillation column (S ₁ in Figure 1).
~S ₆ ) is to be utilized to the maximum.

FIG. 2 is an overall view showing an embodiment of the present invention. Moromi tower A′, initial distillation tower A ₁ ′, concentration tower A ₂ ′, hot water tower F′,
The mutual arrangement of the first extraction column D', the second extraction column _D1 ', the rectification column B', the de-alcoholic distillation column _B1 ', the purification column C', and the impurity treatment column G' is similar to that shown in Figure 1. However, in the case of this example, during normal operation of the ethanol purification equipment, the ethanol is discharged from the top of each of the concentration column _A2 ', rectification column B', purification column C', and impurity treatment column G'. Focusing on the fact that the temperature of the ethanol-containing steam is within a substantially constant range of about 75 to 79°C, the structure is such that the retained heat is collectively recovered by one system of the screw steam heat pump 31.

That is, condensers 21 to 24 whose cooling sides have a vacuum-resistant structure are installed at the top of each of the concentration column A ₂ ′, rectification column B′, purification column C′, and impurity treatment column G′. These condensers 21 to 24 are connected in parallel to a gas-liquid separation tank 32 which also has a decompression-resistant structure. The gas-liquid separation tank 32 can be replenished with water, and its upper portion is connected to the screw steam heat pump 31. This screw steam heat pump 31 may be one that is already commercially available (for example, manufactured by Maekawa Seisakusho Co., Ltd.), and as described later, it pressurizes and heats up the reduced pressure steam sucked from the gas-liquid separation tank 32 very effectively and without waste. It is. The water vapor pressurized and heated by the screw steam heat pump 31 is distributed and utilized as a heating source for each distillation column as described above via the adjustment tank 33 (S ₁ ' to S in the figure). ₆ ′).

Although not shown in the figure, the slightly low temperature (approximately 67°C during normal operation) discharged from the top of the _second extraction column D
℃) can be similarly heat-recovered by installing a small turbo compressor, and can also be recovered from the waste water from the bottom of the mortar tower A' or the de-alcoholizing distillation tower _B1 '. By replenishing the gas-liquid separation tank 32 with hot water that has been preheated by heat exchange, the present invention becomes even more effective, thus allowing almost complete heat recovery and utilization. Note that, depending on the scale of the ethanol purification apparatus, for example, two Roots blowers may be arranged in series together with the screw steam heat pump.

<Function> Next, the function of the present invention will be explained based on the embodiment shown in FIG.

When starting up the ethanol purification equipment, the boiler is operated in the same way as in the past, and each distillation column is heated by the steam, and when ethanol-containing steam is generated from the top of each distillation column, the screw steam heat pump 31 is activated. Activate.

Under normal conditions, if water is maintained at a reduced pressure of approximately 200 Torr in the gas-liquid separation tank 32, where the water level is controlled, the boiling point of water will be approximately 69°C under this reduced pressure, while water will be discharged from the top of each distillation column. Since the temperature of the ethanol-containing steam is 75 to 79°C, the water drawn from the bottom of the gas-liquid separation tank 32 to each condenser by the suction of the screw steam heat pump 31 is indirectly heated with the ethanol-containing steam. The ethanol-containing vapor is condensed and becomes reduced-pressure steam. This reduced-pressure steam is collected by suction into the gas-liquid separation tank 32, where it is separated from unevaporated water that may accompany it, and further suctioned from above to reach the screw steam heat pump 31. In this way, the reduced pressure steam whose heat was indirectly recovered from the ethanol-containing steam discharged from the top of each distillation column is pressurized and heated by the screw steam heat pump 31 (approximately 1.05 Kg/cm ² G x 110°C), The pressurized and heated steam is distributed to each distillation column via the adjustment tank 33. Therefore, the supply of steam from the boiler can be reduced by this amount (reduction amount is about 75% in terms of steam). In this case, if the adjustment tank 33 is also used as a heat storage tank, the boiler itself can be significantly downsized while providing convenience during startup. Note that water is supplied to the screw steam heat pump 31 in order to avoid generation of supersaturated steam due to adiabatic compression, but the amount of heat corresponding to this supplied water is recovered as pressurized and heated steam.

<Effects of the Invention> As explained above, the present invention has the following remarkable effects in summary.

1. It is possible to further save energy, reduce the pollution measures required when operating a boiler, and use a small boiler.

2. Since the working medium is water, there are no problems such as corrosion, leakage, or contamination.

3. Existing equipment can be used because the distillation column is not pressurized or depressurized.

4. Since one system can handle two or more distillation columns, the entire device is not unnecessarily complicated and is economical.

[Brief explanation of the drawing]

FIG. 1 is an overall view illustrating a conventional ethanol purification apparatus using the super allopath method, and FIG. 2 is an overall view showing an embodiment of the present invention. 11-15, 21-24... Condenser, 31... Screw steam heat pump, 32... Gas-liquid separation tank, 33... Adjustment tank, A, A'... Mortar tower, _A1 ,
A ₁ ′...first distillation column, A ₂ , A ₂ ′...concentration column, F, F'... hot water column, D, D'... first extraction column, D ₁ , D ₁ ′... second extraction column, B, B'... rectification column, C, C'... purification column, G,
G'... Impurity treatment tower.

Claims (1)

[Claims] 1 In an Allospass method or Super Allospass method ethanol purification equipment, indirect ethanol-containing vapor discharged from the top of two or more distillation columns selected from a concentration column, a rectification column, a purification column, etc. An ethanol purification system that collects reduced pressure steam whose heat is recovered, pressurizes and raises the temperature of the collected reduced pressure steam using a screw steam heat pump, and uses this as a heat source for the purification equipment.