JPS6055117B2 - Anhydrous ethanol manufacturing method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing absolute ethanol.

More specifically, the present invention relates to a production method and apparatus that can directly and energy-savingly obtain anhydrous ethanol from a dilute and muddy ethanol raw material.
In the known method and apparatus for producing anhydrous alcohol from dilute raw materials, a dilute raw material is supplied to a concentrating column of an apparatus consisting of a concentrating column, an azeotropic distillation column, and a solvent recovery column connected in series, and each column has an independent heat source. The air at the top of the tower is cooled by independent cooling sources.

For this reason, the amount of heat consumed in the concentrating column is almost equivalent to the amount of heat possessed by the absolute alcohol obtained by the known method, and the cost thereof cannot be ignored in today's energy-saving era. It is. Japanese Unexamined Patent Publication 1973-
No. 11317 deals with this problem by dividing the concentration column into a first column (crude concentration column) and a second column (concentration column), compressing and heating the top vapor of the second column, and using this vapor to feed the first column. The system is configured so that the steam necessary for heating is generated, a part of the condensate (94 to 95% alcohol) after heating is obtained (product), and a part is used as the reflux liquid of the second column. . As a result, the amount of heat required for the first and second towers is still about 11 times less than that of a known two-column concentrator, even if the electric power required for the compression is converted into steam. However, the product obtained by this method is 94-95% alcohol, and rationalization of the heat source below the azeotropic column for obtaining anhydrous alcohol has not been achieved.

The present inventors conducted extensive research to solve the problems left behind in JP-A No. 56-113717.

As a result, the gas to be compressed, which is the top vapor of the first concentrating column, is heated by heating the bottom liquid (100°C) of the first concentrating column and pressurizing the second concentrating column. ℃
), the above problem was solved by heating the cans of the azeotropic distillation column and the solvent recovery column, which are atmospheric pressure columns, and supplying the heated condensate to the second concentrating column. As described above, the present invention aims to provide an energy-saving method and apparatus for producing absolute alcohol. The configuration and effects of the present invention will be explained in detail below based on the drawings. In the figure, for example, ethanol raw material such as moromi produced by fermentation method (ethanol concentration 1 to
6n101%) is supplied to the middle stage of the crude concentration column A through pump p-1 and piping 1.

Meanwhile, the raw material is preheated through the heat-light exchanger E-1 (preheater). The internal pressure of tower A is operated at normal pressure. Heating is performed using a gas to be compressed at the top of the tower, which will be described later, through a heat exchanger E-2 (heating can) attached to the bottom of the tower. Now, if the distillate ethanol concentration in the tower top vapor is 24.1m0I%, the distillation temperature is 82.5% from the equilibrium relationship between ethanol and water at normal pressure.
℃. This tower top steam is transferred to pipe 2, compressor G1 pipe 2
'' and a heat exchanger (heating can) E-2, and a part of it is condensed via pump p-2, piping 3, pump p-3, and piping 4, and is transferred to the middle stage of the second concentrating column B. The remaining part is returned to the A column as reflux, and the bottom liquid of the A column is discharged through the pipe 17 and the heat exchanger E-1.The inside of the B column is pressurized to 2 to 6
k91c1tG, for example, is operated at 2.4k91dG.
Heating is performed using steam through a heat exchanger E-3 (heater) attached to the bottom of the column. Ethanol concentration 24.1m
The condensate from column A at 0.01% is concentrated in column B to bring the ethanol concentration of the column overhead vapor to 74.7m01%. This tower overhead vapor is condensed via pipes 5 and 6, heat exchange gases E-4 and E-6 of the azeotropic distillation column C and the solvent recovery column D,
Pipe 6″, condensate tank V1 pump p-4 and pipe 7
A part is refluxed to the second concentrating column B, and the other part is supplied to the azeotropic distillation column C via piping 8. The bottom of column A is water, and its boiling point is 100°C at normal pressure, while the temperature at the top of the column is 82°C, assuming the distillate concentration is 24.1m01% as mentioned above.
．． The temperature at the bottom of the tower is in the 10s, plus the temperature rise due to pressure loss inside the tower and the temperature difference required for heat conduction, which is 15°C.
Then, the condensation temperature of steam under pressure is 115° C., and its coefficient of performance η=11.9. When this coefficient of performance is expressed as a compression ratio, it becomes 2.0, but if you try to heat the bottom liquid with compressed steam in the same way in the case of a normal-pressure one-column type, then add the necessary 15℃ to the bottom temperature of 10CfC. 115℃ is the condensation temperature after vapor compression, and the corresponding coefficient of performance is 10.
．． &The converted compression ratio is 2.8. Therefore, the two-column type has a lower compression ratio and requires less power. The bottom liquid of the B column is supplied as a reflux liquid to the top of the A column via the pipe 23 as described above. Azeotropic distillation column C is operated at normal pressure. The column can (heat exchanger E-4) is B
It is heated by the steam of the column, and near the top of the column, the above-mentioned condensate of the B column vapor is supplied from pipe 8, an azeotropic solvent is supplied from pipe 10, and azeotropic solvent-ethanol from decanter F is supplied from pipe 12. Anhydrous ethanol is extracted from the pipe 11 at the bottom of the tower. The temperature of the column bottom liquid is 79'C (note: the boiling point of ethanol), and the temperature of the B column overhead vapor supplied to heat exchanger E-4 is, for example, 3.5C. ．． If the distillate is operated at 4at0 and the distillate concentration is 74.7m01% as described above, the temperature will be 110°C due to the equilibrium relationship between ethanol and water, so the temperature difference necessary for heat transfer is sufficient. From the top of the C tower, the three-component azeotropic vapor passes through the pipe 9 to the heat exchanger E-5 (condenser).
The condensate produced by cooling with cooling water is led to a decanter F. The condensate is separated in a decanter into an azeotropic solvent-rich layer and a water-rich layer, the former being returned to column C as described above, and the latter being fed via line 13 to the solvent recovery column. Solvent recovery column D is operated at normal pressure. The can of the column (heat exchanger E-6) is heated by the steam of the B column as described above, and near the top of the column, the water-rich layer liquid from the C column decanter is passed from the pipe 13 to the top of the column. Steam condensate (solvent) is supplied as a reflux liquid from pipe 16, and water is extracted from pipe 15 at the bottom of the column. The temperature of the bottom liquid is 100°C (note: the boiling point of water), and the temperature of the steam at the top of the B tower supplied to heat exchanger E-6 is 113'C, as mentioned above. The temperature difference is sufficient. A portion of the condensate from pipe 14 is returned to decanter F. As mentioned above, the heat source for the cans of the azeotropic distillation column C and the solvent recovery column D is the overhead steam of the B column.
No separate heating source is required as in the known method. Further, the present invention utilizes the above-mentioned Japanese Patent Application Laid-Open No. 56-1991, in which the concentration tower is of a two-tower type.
-113717, the latent heat of the top steam of the 4B tower is utilized to a high degree, and the compressed gas of @A tower top steam is completely ), the heat utilization is high as in case 4, and (c) the independent heating source is the can of tower B (heat exchanger E-3).
Heat management is easy because only the heat is required.

``The simple explanatory diagram of the drawing shows a flow sheet of the absolute ethanol production apparatus of the present invention.

Claims (1)

[Claims] 1. A method for producing anhydrous ethanol from an ethanol raw material using a distillation apparatus consisting of a concentrating column, an azeotropic distillation column, and a solvent recovery column, in which two concentrating columns are arranged in series and operated at normal pressure. The top vapor of the first concentrating column is compressed by a compressor attached to the column so that the compressed gas can be used to heat the can of the column, and a part of the condensate after heating is transferred to the second concentrating column. supply to the tower,
The other part is used as the reflux liquid at the top of the first concentrating column, and the second concentrating column is used as a pressurized distillation column, and the top vapor is heated in the cans of the azeotropic distillation column and the solvent recovery column, both of which are operated at normal pressure. A part of the condensate after heating is refluxed to the top of the second concentration column operated under pressure, and the other part is used as a feed liquid to the azeotropic distillation column. A method for producing anhydrous ethanol, characterized in that the bottom liquid of the concentrating column is used as the reflux liquid to the first concentrating column. 2. The method according to claim 1, in which the internal pressure of the second concentrating column is 2 to 6 kg/cm^2G. 3. The method according to claim 1, in which the top vapor of the first concentrating column is compressed to 2 to 4 kg/cm^2G. 4. In a distillation apparatus consisting of a concentrating column, an azeotropic distillation column, and a solvent recovery column, which produces anhydrous ethanol from an ethanol raw material, the concentrating column is an atmospheric pressure crude concentrating column A and the ethanol generated in the column is concentrated. Pressurized concentration tower B
It consists of a compressor G that compresses the ethanol vapor generated in the column A, an azeotropic distillation column C, and a solvent recovery column D. 1 and a bottom liquid extraction pipe 17, an ethanol vapor pipe 2 is connected between the column and the compressor G, and a compressed gas pipe 2', a heat exchanger E-2, and a rough It has a concentrate pipe 3, a condensate pump p-2 (boosting pump p-3), and a crude concentrate supply pipe 4, and a crude concentrate pipe 3 is provided between the crude concentration column A and the condensate pump p-2. The pressurized concentration tower B has a reflux liquid receiving pipe 7.
, ethanol steam piping 5 and 6, heat exchanger E-3, E
-4 and E-6, concentrate piping 6', concentrate tank V,
The azeotropic distillation column C has the heat exchanger E-4 and the anhydrous ethanol extraction pipe 11 at the bottom of the column, and is connected to the column C and the solvent recovery pipe. Between the column D are an azeotropic steam pipe 9, a heat exchanger E-5, a decanter F, and decanter effluent pipes 12 and 13.
has a heat exchanger E-6 and a water withdrawal pipe 15 at the bottom of the tower, and a solvent vapor pipe 14 between the top of the tower and the decanter F.
, the heat exchanger E-7 and the solvent pipe 16 are connected to the heat exchanger E-7.
An apparatus for producing anhydrous ethanol, characterized in that a solvent pipe 16 is also connected or installed between the and the solvent recovery column D. 5. An apparatus for producing anhydrous ethanol according to claim 4, characterized in that it has a heat exchanger E-1 at a position where the raw material supply pipe 1 and the water withdrawal pipe 17 intersect. 6 Heat exchangers E-2 and E- as heating cans are installed in the normal pressure crude concentration column, pressure concentration column B, azeotropic distillation column C, and solvent recovery column D, respectively.
3. The device according to claim 4, comprising: E-4 and E-6.