JPS60226837A - Apparatus for producing absolute ethanol and production of absolute ethanol - Google Patents

Abstract

PURPOSE:To obtain absolute ethanol from an ethanol raw material with saved energy, by using combination of a distillation apparatus consisting of a concentration column, azeotropic distillation column and solvent recovery column with a decarbonation apparatus to remove previously gaseous carbon dioxide in the raw material. CONSTITUTION:An ethanol raw material 1 containing CO2 is fed to a deaeration column (A) decompressed by a vacuum generating device (H), decardonated and fed to a concentration column (B) to prevent trouble due to accumulation of CO2. The concentration column (B) and an azeotropic distillation column (C) are used as pressurized distillation columns, and overhead vapors 4 and 8 of both columns (B) and (C) are compressed by compressors (G1) and (G2) to heat bottoms 6 are 11 of the respective columns (B) and (C) with the compressed gases 4' and 8'. One condensed liquid 4' is partially fed to the column (C), and the other is returned to the column (B). The other condensed liquid 9 is separated into two layers in a decanter (F), and the upper layer is returned to the column (C). The lower layer is fed to a solvent recovery column (D). The overhead vapor 14 of the column (D) is cooled, condensed, and partially reluxed to the top of the column (D). The other is returned to the decanter (F) respectively, and water is taken out of the bottom 17 of the column (D) to give the aimed absolute ethanol advantageously from the bottom 7 of the column (B).

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 manufacturing method and apparatus capable of obtaining anhydrous ethanol from a dilute and muddy ethanol raw material in an energy-saving manner.

In a known apparatus for producing anhydrous alcohol from dilute raw materials, dilute raw materials are supplied to the concentrating column of the device, which consists of a concentrating column, an azeotropic distillation column, and a solvent recovery column connected in series, and the top vapor is each provided with an independent cooling source. It is designed to be cooled by

Therefore, the amount of heat consumed in the concentrating column is different from the amount of heat possessed by the absolute alcohol obtained by the known method, for example.
The cost has reached a level that cannot be ignored in today's energy-saving era. Japanese Unexamined Patent Publication No. 1983-
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 structure is such 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 1st and 2nd columns is approximately 172 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 84-95% alcohol, and rationalization of the heat source below the azeotropic column for obtaining absolute alcohol has not been achieved.

The inventors of the tree researched and completed two inventions in order to solve the problems left in Japanese Patent Application Laid-open No. 58-113717, and first published Japanese Patent Application No. 57-138244 and Japanese Patent Application No. 58-70708.
A patent application was filed as No. In the devices of these inventions, the first
Either one of the column (crude concentration column) and the second column (concentration column) is a pressure column, and the other one is a normal pressure column, and the top vapor of the normal pressure column is compressed with a mechanical compression pump. The compressed gas can be used to heat several reactors, and one can be used as a pressurized distillation column so that the top vapor can be used to heat the azeotropic distillation column and the solvent recovery column, both of which operate at normal pressure. By doing so, we aimed to rationalize the heat sources below the azeotropic distillation column.

In addition, he completed another invention for the same purpose and applied for a patent application in 1984-2.
A patent application was filed as No. 081184. In the apparatus of this invention, the top gas of either one of the first column (crude concentration column) and the second column (azeotropic column) is mechanically compressed by a steam turbine,
The compressed gas is used to heat the bottom liquid in the same column, and the top vapor of another column is used as an absorption heat pump (also known as a boiler).
The heat source was rationalized by condensing it in the same tower and using the back pressure steam used in the steam turbine as the heat source for the absorption heat pump. However, these improved technologies do not separate or are impossible to separate the non-condensable gas contained in the vapor at the top of the crude condensation column. When a gas containing carbon dioxide (CO2) based on Mixing into the top steam increases the compression ratio of the compressor, and since the compressed gas is not condensed in each repoiler, the heat transfer coefficient of the repoiler decreases, which ultimately increases the required heat transfer area of the boiler. It turns out.

Considering the situation in which C02 accumulates in the concentration column as described above, the situation is as follows.

■First of all, the amount of Cfh contained in the raw material moromi (containing 6 to IO% ethanol) is determined by the solubility of CO2, which is 0.6 B5 mJL/water tan.
(Chemical Handbook, published by the Chemical Society of Japan), so 1m of raw material
"0.8 B5

■Next, when this raw material is processed in a closed distillation system, the Cop is discharged to either (i) the distilled ethanol, the distilled ethanol, or the waste liquid. However, for reasons described later, the amount of CO2 transferred to ethanol is significantly smaller than the CO2 brought in from the raw materials, and almost no CO2 is transferred to the waste liquid.

Regarding the former, anhydrous ethanol gas condenses at 78°C, and the amount of C (h) that can be dissolved at this temperature is the same as the ratio of the C02 solubility in water at 15°C to that in water at 7!3°C. (1/3.8), for 1000 kg/hr of raw material containing 6% ethanol, +00
0X O, 08X 2.3X 1/3.8÷0.79=
0.048Nrrf/hr (2.3 is the solubility of CO2 in ethanol at 15°C, 0.78 is the specific gravity of ethanol). 7) It is significantly smaller than 0.eEi5Nm'/hr (amount of Cfh brought in from raw materials).

Next, regarding the latter (C02 transferred to waste liquid), the bottom liquid (note, a part of this is sequentially discharged) from the concentration tower (or crude concentration) is heated with water at 100°C (at normal pressure). can be,
The solubility of CO2 is essentially zero.

Co introduced into the distillation system for the reasons stated in ■■ and ■
2, most of it accumulates within the system, causing the above-mentioned trouble.

In order to solve this problem, Kikai Nagisa et al. developed an anhydrous ethanol production system consisting of a degassing tower, which will be described in detail later, as a device for preliminarily removing carbon dioxide residue contained in raw materials, a concentrating tower, an azeotropic distillation tower, and a solvent recovery tower. The above-mentioned trouble was solved by combining the decarboxylation device with the decarboxylation device so that the ethanol raw material treated with the decarbonation gas device could be supplied to the concentrating column.

As described above, the present invention aims to provide an energy-saving method and apparatus for producing anhydrous alcohol.

The configuration and effects of the present invention will be explained in detail below based on the flow sheet shown in the figure.

In the figure, an ethanol raw material such as moromi produced by a fermentation method (ethanol concentration 1 to 6 mo1%) is supplied to the middle stage of a degassing tower A through a pipe 1. The inside of the degassing tower A is 50 to 10
It is maintained at 0mmHgabs.

While the supplied ethanol raw material is arriving in the tower,
Decarbonation is performed as shown in the table below.

The temperature of the supplied ethanol raw material or the temperature inside the column is not limited, but is approximately 15 to 30°C. The internal structure of the degassing tower A is not limited, and may be, for example, a wet wall tower, a packed tower, or a plate tower. The ethanol raw material that has been decarbonized by flowing down inside the column is transferred to piping 3 and pump P-1.
It is supplied to the middle stage of concentration column B through .

The above-mentioned vacuum generating device is not limited in terms of device as long as the required degree of vacuum can be obtained, and for example, 1) a vacuum pump or water flow aspirator type, or 2) a vacuum flushing type can be adopted. The vacuum generator H shown in the figure is
In the latter, the steam ejector +, Ka and condenser L,
The combination of two stages in series of L2 is the top of degassing tower A and piping 2.
are connected by.

The required steam is sent to the steam ejector +, & to the condenser L
+, cooling water is supplied to L2 to generate the above-mentioned vacuum, and carbon dioxide gas in the ethanol raw material in the degassing tower A is degassed. The degassed carbon dioxide gas passes through piping 2, 2°, 2”,
It is discharged through the suigetsu tank M together with the condensed steam.

The quantitative relationship between the decarboxylated ethanol raw material supplied to the concentration column B and that before decarboxylation is as shown in the following table, for example.

Thus, for example, the raw material having the composition (3) above is distilled and concentrated in the concentration column B to 84.4% by weight of ethanol. The concentrated tower top vapor is led to the compressor Q through a pipe 4. On the other hand, the bottom liquid becomes water (containing fermentation lees) and is successively discharged from the pipe 7. The overhead vapor (at normal pressure) led to the compressor Q is compressed to 3 to 4 Kg/crn'G. The compressed vapor is led to the repoiler E-1 (heat exchanger) attached to tower B through piping 4°, where it heats the bottom liquid of tower B circulating through piping 6. As it evaporates, it cools and condenses itself. The condensation temperature of the aforementioned compressed vapor is 112°C when the compression pressure is 4 kg/cm'G, while the bottom liquid of column B is essentially water (boiling point 10
0℃). Therefore, even if the rise in the boiling point of the tower bottom liquid due to the dissolved matter in the tower bottom liquid and the loss of pressure inside the tower is taken into account, as long as tower B is operated at normal pressure, the above-mentioned compressed vapor can be used as a heating source for the tower bottom liquid in tower B. It is sufficient for the purpose.

A part of the condensate (concentrated ethanol) cooled and condensed by the repoiler E-1 is transferred to the pipe 4' by the condensate pump P-2.
, 5' to column B, and the other part is refluxed to column B through pipe 4',
5 near the upper stage of the azeotropic distillation column C.

Several groups C are an azeotropic distillation column that uses an azeotropic solvent (for example, benzene), and from the top of the column, vapor with an azeotropic composition (in this case, ethanol-water-benzene) is distilled out for 3 m, and from the bottom of the column is pipe 1.
Anhydrous ethanol (product) is discharged by 0. The 3-component azeotropic vapor from the top of the tower is led to the compressor Q by a pipe 8,
Compressed to 3-4Kg/crn'G. Now, set the compression pressure to 3
．． If it is 4Kg/cm'G, the applied pressure is 1i! The condensation temperature of the steam is 85°C. On the other hand, the bottom liquid in column C is anhydrous ethanol, and when column C is operated at normal pressure, its boiling point is 78°C.

Therefore, the above-mentioned compressed vapor has a temperature difference sufficient to heat the bottom liquid in column C, and this temperature difference is still sufficient even considering the rise in the boiling point of anhydrous ethanol due to the pressure loss inside the column. Therefore, the aforementioned vapor to be compressed is guided to the repoiler E-2 attached to the tower C through the pipe 8°, and is also guided to the repoiler E-2 attached to the column C.
The bottom liquid (anhydrous ethanol) from column C, which is led to repoiler E-2, is heated and evaporated, and itself is cooled and condensed. The condensate is sent to the decanter F through the condensate pump P-3 and piping 9. The condensate is collected in a decanter.
F is separated into two phases: a solvent-rich phase and a water-rich phase.

The former then returns to tower C via piping 12.

The latter (water-rich phase) is sent via line 12 from decanter F to the solvent recovery column. For several units, the top of the tower may be the piping 1
The azeotropic vapor of the three components ethanol-water-solvent is distilled out by means 4, and water is discharged from the bottom of the column through pipe 17. The azeotropic vapor enters the condenser E-3 via the pipe 14, is cooled and condensed with water, and the condensate is partially sent to the decanter F via the pipe 14', the pump P-4, and the pipe 15. A part of the liquid further passes through a 15-inch pipe and returns to the tower as a reflux liquid. In the present invention, the top steam (three component steam) of the tower is compressed,
The compressed gas can also be used as the heat source for the tower can. However, the amount of heat required for Repolar E-4 in the tower is different from that in the other tower B,
It is significantly less than that of C repolar, and ■
Since the temperatures of the top vapor and bottom liquid are high, it is not very advantageous to install a compressor in place of condenser E-3.

As is clear from the above explanation, the present invention provides the following steps when producing anhydrous ethanol using a distillation apparatus to which a heat pump is applied, using a dilute ethanol solution obtained by a fermentation method and containing carbon dioxide gas as a raw material. This has the effect of solving two problems. In other words, (1) the carbon dioxide scum contained in the raw material increases the compression ratio of the heat pump compressor, thereby increasing the power consumption for compressor operation, and (2) the carbon dioxide scum compressed by the heat pump becomes a non-condensable gas ( Note: Since the repoiler contains carbon dioxide gas, the problem is that the required heat transfer area of the repoiler increases compared to a case where the repoiler does not contain the gas.

Therefore, whether the heat pump described above is a mechanical heat pump or an absorption heat pump, the above-mentioned effects are brought about by removing carbon dioxide from the ethanol raw material.

[Brief explanation of the drawing]

The figure shows a flow sheet of an apparatus for producing anhydrous ethanol of the present invention. In the figure, A and H constitute a decarboxylation device,
The former is a degassing tower, and the latter is a vacuum generator (note: steam ejector). Moreover, B, C, and D are a concentration column, an azeotropic distillation column, and a solvent recovery column, which constitute a distillation apparatus, respectively. In addition, Gl and Gl are heat pump compressors, and E-1. E-2 and E-4 are repoilers attached to columns B, C and D, respectively; E-3 is a column condenser; F is a decanter attached to column C; P-1, P-2, P-3 and P-
4 indicates a pump, respectively. ”−

Claims (4)

[Claims] (1) In a distillation device consisting of a decarbonation sludge device, a concentration column, an azeotropic distillation column, and a solvent recovery column, which produce anhydrous ethanol from an ethanol raw material, the decarbonation gas device consists of a degassing column A, a raw material Supply pipe 1, ethanol vapor pipe 2
．． Degassed liquid piping 3. Degassed liquid pump P-1 and the piping 2
The concentrating column B consists of a vacuum generator H coupled with a
Degassing liquid piping 3, ethanol vapor piping 4, compressed air Q connected to several units B by said piping 4, ethanol condensate piping 4
' and a heat exchanger E-1 connected to the compressor G by the piping 4' and several units B by the can liquid piping 6, the can liquid piping 6 and the waste liquid extraction pipe 7. A concentrate pump P-2 connected to several units B is connected to a pipe 4° and a reflux pipe 5'', and the azeotropic distillation column C has a concentrate pipe 5, an azeotropic composition gas pipe 8. compressor aG!, which is connected to several units C!, azeotropic liquid piping 8', compressor G via said piping 8', and heat exchanger E-2, which is connected to several units C via boiler liquid piping 1]. 11 and a water drain pipe 10. A common liquid pump P-3 connected to a heat exchanger E-2 through piping 8 and a decanter F through piping 9, and a reflux liquid piping 12. Said piping 12
A decanter F connected to several units C is connected to the solvent recovery tower, and a pipe 13. Piping 14. Condenser E-3 connected to several condensers through the piping. Piping 14°, pump P-4 connected to condenser E-3 by piping 14° and decanter F by piping 15, piping 15, piping 15' connecting piping 15 to the top of the tower, and water extraction. An anhydrous ethanol production device in which piping 17 is connected. (2) The vacuum generator H consists of a combination of a steam ejector KI and a condenser LL connected in series, and a combination of a steam ejector and a condenser L2, in which + is connected to the degassing tower A through piping 2. is connected to the LI through a connecting pipe,
The manufacturing apparatus according to claim 1, wherein L1 and b are connected to a water seal M by drain pipes 2° and 2'', respectively. (3) In a method for producing anhydrous ethanol from ethanol raw material using a distillation apparatus consisting of a concentrating column, an azeotropic distillation column, and a solvent recovery column, a carbon dioxide removal device consisting of a degassing column and a vacuum generator is placed before the concentrating column. The concentrating column and the azeotropic distillation column are pressurized distillation columns, and the anhydrous ethanol raw material is supplied to the degassing column and subjected to reduced pressure treatment to decarbonate the decarbonated gas. The raw material is supplied to the concentrating column, the vapor at the top of several columns is compressed, the liquid in several columns is heated with the gas to be compressed to generate steam, and a part of the condensed liquid after the heating is sent to the azeotropic distillation column. The other part is used as the reflux liquid to the concentrating column, and the top vapor of the azeotropic distillation column is compressed and several bottoms are heated with the compressed gas to generate steam, and after the heating, The condensed liquid is sent to a decanter, the upper layer liquid separated into upper and lower layers by the decanter is refluxed to the azeotropic distillation column, anhydrous ethanol is extracted from the bottom of the column, and the lower layer liquid of the decanter is supplied to the solvent recovery column. Then, the vapor at the top of the solvent recovery column is cooled and condensed, a part of the condensed liquid is refluxed to the top of the column, the other part is refluxed to the decanter, and the bottom liquid is heated in a can to convert the vapor. generate,
A method for producing anhydrous ethanol, which comprises discharging a portion of the bottom liquid (water). (4) Supply diluted ethanol raw material to the degassing tower, and
The method according to claim 1 (3), in which decarbonation is carried out at a temperature of 5 to 40°C and an internal pressure of 20 to 200 mHg.