WO2022191228A1 - Dehydration system and dehydration method - Google Patents

Abstract

The present invention reduces the operating cost of a process that comprises membrane separation by enhancing the energy efficiency. A dehydration system for separating water from a fluid to be processed, said fluid containing water and a water-soluble organic compound. This dehydration system comprises: a plurality of distillation columns including a first distillation column and a second distillation column; a separation membrane unit that comprises one or more separation membrane module groups, each of which comprises one or more separation membrane modules each comprising a separation membrane that is selectively permeable to water; and one or more compressor units, each of which comprises one or more compressors. With respect to this dehydration system, the first distillation column, the second distillation column, at least one group among the separation membrane module groups, at least one compressor unit among the compressor units, and the first distillation column are sequentially arranged.

Description

Dehydration system and dehydration method

The present invention relates to a dehydration system and a dehydration method for separating water from a fluid containing water and water-soluble organic compounds.

Distillation is usually used as a method for removing only water from a mixture containing water-soluble organic compounds and water. However, when the water-soluble organic compound has the property of azeotroping with water, water is inevitably contained in the overhead steam of the distillation column, and it has been difficult to improve the purity.

As a purification method for obtaining a high-purity water-soluble organic compound azeotroping with water, most of the water contained in the water-soluble organic compound azeotroping with water is removed by distillation, followed by adsorption. A method of finally obtaining a highly pure water-soluble organic compound by removing the remaining water using a tower or the like is known (see Patent Document 1).

Also known is an energy-efficient method of removing water from a water-alcohol mixture by introducing the water-alcohol mixture into a multiple-effect distillation column for concentration, followed by membrane separation ( See Patent Document 2).

JP-A-2000-334257 WO2018/168651

However, due to the recent development of distillation technology, the difference between the energy required for the process combining the multiple-effect distillation column and the adsorption column and the energy required for the process combining the multiple-effect distillation column and membrane separation has narrowed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a dehydration system for separating water from a fluid to be treated which contains at least water and water-soluble organic compounds, which can reduce operating costs by further increasing the energy efficiency of processes using membrane separation. and

The gist of the present invention is as follows.

[1] A dehydration system for separating water from a fluid to be treated containing water and water-soluble organic compounds,
a plurality of distillation columns including a first distillation column and a second distillation column;
one or more separation membrane units;
one or more compressor units;
The separation membrane unit has one or more separation membrane module groups,
The separation membrane module group has a separation membrane module comprising one or more separation membranes that selectively permeate water,
The compressor unit comprises one or more compressors;
The first distillation column, the second distillation column, one or more of the separation membrane module groups, and one or more of the compressor units are arranged in order, and one or more of the compressor units is connected to the outlet side of the first distillation column,
dehydration system.

[2] The dehydration system according to [1], wherein the permeate sides of all the separation membrane modules included in the separation membrane module unit are connected to the inlet side of the compressor unit.

[3] the separation membrane unit includes a first separation membrane module group and a second separation membrane module group,
The dehydration system according to [1], wherein the permeation side of either the first separation membrane module group or the second separation membrane module group is connected to the inlet side of the compressor unit.

[4] The dehydration system according to [3], wherein the permeation side of the separation membrane module group that is not connected to the compressor unit among the separation membrane module groups is connected to a condenser.

[5] The dehydration system according to [3], wherein the permeation side of the separation membrane module group that is not connected to the compressor unit among the separation membrane modules is connected to the first distillation column.

[6] The separation membrane unit includes a first separation membrane module group and a second separation membrane module group, and the compressor unit has a first compressor unit and a second compressor unit, The permeate side of the first separation membrane module group is connected to the inlet side of the first compressor unit, and the permeate side of the second separation membrane module group is connected to the inlet side of the second compressor unit. The dehydration system according to [1].

[7] the outlet side of the first compressor unit is connected to the second distillation column, and the outlet side of the second compressor unit is connected to the first distillation column;
The dehydration system according to [6].

[8] The dehydration system according to [6], wherein the outlet side of the first compressor unit and the outlet side of the second compressor unit are connected to the first distillation column.

[9] Furthermore, a third compressor unit is provided, the outlet sides of the first compressor unit and the second compressor unit are connected to the inlet side of the third compressor unit, The dehydration system of [6], wherein the outlet side of the third compressor unit is connected to the first distillation column.

[10] The dehydration system according to any one of [1] to [9], wherein the compressor unit includes one or more compressors connected in series and/or one or more compressors arranged in parallel .

[11] The dehydration system according to any one of [1] to [10], wherein the operating pressure of the first distillation column is lower than the operating pressure of the second distillation column.

[12] The dehydration system according to any one of [1] to [11], wherein the first distillation column is a vacuum distillation column and the second distillation column is a high-pressure distillation column.

[13] A dehydration method for separating water from a fluid to be treated containing water and water-soluble organic compounds, wherein the operating pressure of the first distillation column is equal to or lower than the pressure on the outlet side of the compressor unit, [1 ] A dehydration method using the dehydration system according to any one of [12].

Provide a dehydration system that separates water from a fluid to be treated that contains at least water and water-soluble organic compounds, which can reduce operating costs by increasing the energy efficiency of processes using membrane separation.

It is a figure showing an example of a dehydration system concerning an embodiment of the present invention. FIG. 3 illustrates another example of a dehydration system according to an embodiment of the invention; FIG. 10 illustrates yet another example of a dehydration system according to an embodiment of the invention; It is a figure showing an example of a dehydration system concerning a comparative example of the present invention. FIG. 5 is a diagram showing another example of a dehydration system according to a comparative example of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the separation membrane unit of this invention, a separation membrane module row, a separation membrane module group, and a separation membrane module. It is a figure explaining the connection pattern of the compressor of this invention.

Although the present invention will be described in detail below, the present invention is not limited only to specific embodiments.

The present invention provides at least one separation membrane module group having at least one separation membrane module comprising a plurality of distillation columns including a first distillation column and a second distillation column, and a separation membrane module that selectively permeates water. and one or more compressor units comprising one or more compressors, wherein the first distillation column, the second distillation column, and one of the separation membrane module groups A dehydration system for separating water from a fluid to be treated containing water and a water-soluble organic compound, characterized in that at least one of the compressor units and the first distillation column are arranged in this order. .

[Fluid to be treated]
A fluid to be treated by the dehydration system of the present invention is a liquid containing at least water and a water-soluble organic compound. Water-soluble organic compounds to be concentrated by the concentration method of the present invention include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, n-butanol, acetonitrile, acetone, dioxane, DMF, pyridine, formic acid, ethyl acetate, and the like. However, from the viewpoint of sufficiently exhibiting the effects of the dehydration system of the present invention, it is preferably a water-soluble organic compound that azeotropes with water. More preferred water-soluble organic compounds are ethanol, n-propyl alcohol, i-propyl alcohol, n-butanol, acetonitrile, pyridine, formic acid and ethyl acetate.

The content of the water-soluble organic compound in the fluid to be treated, which is supplied to the nearest distillation column from the raw material supply side of the dehydration system of the present invention, is not specified, but is preferably 1 wt% or more, more preferably 1 wt% or more, 2 wt % or more is particularly preferred. 20 wt% or less is preferable, 15 wt% or less is more preferable, and 10 wt% or less is particularly preferable.

[Distillation column]
The dehydration system of the present invention includes multiple distillation columns including a first distillation column and a second distillation column.
From the viewpoint of efficient use of energy, the multiple distillation columns are preferably multi-effect distillation columns. When the plurality of distillation columns are multiple-effect distillation columns, they are more preferably multiple-effect distillation columns including a vacuum distillation column and a high-pressure distillation column, and a multiple-effect distillation column including a mash column for simultaneously separating water-soluble organic compounds and solid-liquid. More preferably, in the utility distillation column, the moromi column is operated under reduced pressure conditions and the other one or more distillation columns comprises a high pressure distillation column.

The multiple distillation columns include a first distillation column and a second distillation column. The first distillation column preferably has at least an operating pressure equal to or lower than the pressure on the outlet side of the compressor described later, and the operating pressure is equal to or lower than the pressure on the outlet side of the compressor and is a vacuum distillation column. It is more preferable to have
When the fluid to be treated contains bioethanol obtained from the fermenter and the fluid supplied to the first distillation column is a solid-liquid mixed fluid from the fermenter, from the viewpoint of removing solids contained in the fluid to be treated , the first distillation column is a moromi column, preferably a vacuum distillation column.

The plurality of distillation columns preferably further includes a distillation column other than the first distillation column and the second distillation column, and the distillation columns other than the first distillation column and the second distillation column include: Preferably, a third distillation column is included.

When the plurality of distillation columns consist of a first distillation column and a second distillation column, it is preferable that the first distillation column is a vacuum distillation column and the second distillation column is a high pressure distillation column. When the multiple distillation columns include a first distillation column, a second distillation column, and a third distillation column, the first distillation column is a vacuum distillation column and the second distillation column is a high pressure distillation column. and the third distillation column is preferably a medium pressure distillation column.

[Separation membrane unit]
The separation membrane unit of the present invention includes at least one separation membrane module. When the separation membrane unit contains a plurality of separation membrane modules, the number of separation membrane modules can be appropriately set according to the concentration of the fluid to be concentrated to be processed by the separation membrane module, the concentration of the target concentrated fluid, the processing amount, etc. is.

When a plurality of separation membrane modules are used, the arrangement method may be only serial arrangement, parallel arrangement only, or a combination of serial arrangement and parallel arrangement. When the series arrangement and the parallel arrangement are combined, it is preferable to line up a plurality of rows of modules in which a plurality of modules are connected in series arrangement in parallel arrangement. At this time, it is preferable to set the number of modules in each row to be the same, because this facilitates designing the degree of purification of the fluid to be concentrated and the control pressure of the modules.
When the separation membrane unit of the present invention includes a plurality of separation membrane modules, it has one or more separation membrane module groups.

The content of water-soluble organic compounds in the fluid to be concentrated supplied to the separation membrane unit is preferably 80 wt% or more, more preferably 85 wt% or more, and particularly preferably 88 wt% or more. 97 wt% or less is preferable, 95 wt% or less is more preferable, and 92 wt% or less is particularly preferable.

[Separation membrane module group]
The separation membrane module group is obtained by dividing a plurality of modules as a group of one or more separation membrane modules in order from the supply side of the fluid to be concentrated. This group is called a first separation membrane module group, a second separation membrane module group, . The number of separation membrane modules included in the separation membrane module group may be the same or different.

The separation membrane module group is defined as follows. When a separation membrane unit has a plurality of separation membrane modules, the permeate side piping of multiple separation membrane modules is usually used to reduce the cost of manufacturing piping and the mounting frame that supports the piping, and to simplify the control conditions for the entire process. , are combined into one collecting pipe. A plurality of separation membrane modules whose permeate sides are combined into one collecting pipe is defined as one separation membrane module group.

When arranging a plurality of rows of separation membrane modules in which a plurality of separation membrane modules are arranged in series in parallel, a separation membrane module group is set across different rows as illustrated in FIG. At this time, as shown in FIG. 6, each row included in one separation membrane module group may be divided so that the same number of separation membrane modules are included. preferred in doing so. In FIG. 6, the permeate sides of all the separation membrane modules in the first separation membrane module group are connected to the first collecting pipe, and the permeate sides of all the separation membrane modules in the second separation membrane module group are connected to the second collecting pipe. Connected.

When the separation membrane module group consists of the first separation membrane module group and the second separation membrane module group, the vacuum pressure of the first collection pipe to which the permeation side of the first separation membrane module group is connected is preferably 3 kPaA or more. , more preferably 5 kPaA or more, and even more preferably 10 kPaA or more. 150 kPaA or less is preferable, 100 kPaA or less is more preferable, and 50 kPaA or less is even more preferable. The vacuum pressure of the second collecting pipe to which the permeate side of the second separation membrane module group is connected is preferably 0.5 kPaA or higher, more preferably 1 kPaA or higher. 10 kPaA or less is preferable, 5 kPaA or less is more preferable, and 3 kPaA or less is even more preferable. By being above the lower limit value and below the upper limit value, a differential pressure between the feed side and the permeate side of the separation membrane can be generated, a sufficient permeation driving force can be secured, and the low temperature necessary for cooling and condensing the permeate side fluid. By reducing the flow rate of the refrigerant, an energy-saving effect can be realized.

[Separation membrane module]
The separation membrane module includes a separation membrane (membrane), a container shell (shell), a supply port for the fluid to be concentrated, an outlet for the concentrated fluid, and a permeate outlet separated by the membrane.

As a separation membrane module, a large number of tubular separation membranes are arranged in a container shell, a fluid to be concentrated is allowed to flow outside the tubular separation membranes, and water is permeated inside the tubular separation membranes, or It is preferable to allow the fluid to be concentrated to flow through the tubular separation membrane and allow water to permeate the outside of the tubular separation membrane, but the form of the separation membrane may be a honeycomb structure, hollow fiber structure, sheet structure, etc. is not.

As the tubular separation membrane, it is preferable to have a membrane that selectively permeates water on the inner peripheral surface and/or the outer peripheral surface of a tubular porous substrate.

[Porous substrate]
The porous substrate functions as a support that supports the molecular sieve membrane. Materials constituting the porous substrate are not particularly limited, and various materials such as glass, ceramics, metals, carbon moldings, and resins can be applied. In the case of the ceramic support, any porous inorganic material may be used as long as it is chemically stable such that zeolite can be crystallized in the form of a film on its surface. Specific examples include sintered ceramics such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride and silicon carbide. Among them, alumina such as α-alumina and γ-alumina and mullite are preferable, and alumina is particularly preferable. When these supports are used, partial zeolite formation is facilitated, so that the bond between the support and zeolite is strengthened, and a dense membrane with high separation performance can be easily formed.

In the present invention, the porous substrate itself need not have molecular sieving ability. The porous substrate has fine pores (voids, voids) that communicate between the outer wall side (outer peripheral surface) and the inner wall side (inner peripheral surface).

The porosity of the porous substrate is usually 20% or more, preferably 25% or more, more preferably 30% or more, and is usually 80% or less, preferably 60% or less, more preferably 50% or less, and the average The pore diameter is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and the upper limit is usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less. A porous substrate having such pores can appropriately support the molecular sieve membrane with sufficient strength, and can allow molecules that have passed through the molecular sieve membrane to permeate at a sufficient speed. Alternatively, it is possible to allow the molecules to reach the molecular sieve membrane at sufficient velocity. Incidentally, the porosity and pore size of the porous substrate can be easily specified by a mercury intrusion method, observation of a cross section with an SEM, or the like. Similar to the average pore diameter, it can also be calculated from volume and mass using true specific gravity.

The maximum diameter of the openings of the through pores extending from the outer peripheral surface to the inner peripheral surface of the porous substrate for forming the zeolite membrane as the molecular sieve membrane is usually 10 µm or less, preferably 8 µm or less. The lower limit of the maximum diameter is preferably 0.05 μm or more. In addition, all of the penetrating portions from the outer peripheral surface to the inner peripheral surface may have the same pore size. may be used.

In the tubular porous substrate, it is preferable that both the outer peripheral surface and the inner peripheral surface of the cross section perpendicular to the tube axis direction are circular. The thickness of the tubular porous substrate (the difference between the radius of the outer peripheral surface and the radius of the inner peripheral surface) is not particularly limited. For example, the thickness is preferably 0.5 mm or more, more preferably 0.8 mm or more, and even more preferably 1.0 mm or more, although it varies depending on the material, porosity, and the like.

The inner diameter of the tubular porous substrate is not particularly limited. For example, the ratio of the inner diameter (diameter) to the thickness of the porous substrate (inner diameter (mm)/thickness (mm)) is preferably 20 or less, more preferably 17 or less. , more preferably 13 or less, particularly preferably 9 or less. In the case of a ceramic sintered porous substrate, the inner diameter is preferably 3 mm or more, particularly 5 mm or more, and 20 mm or less, particularly 15 mm or less.

The length (axial length) of the porous substrate is not particularly limited.

[Molecular Sieve Membrane]
A molecular sieve membrane is formed on the surface of the porous substrate. When the porous substrate has a tubular shape, the molecular sieve membrane is formed on the outer peripheral surface and/or the inner peripheral surface. The form of the molecular sieve membrane is not particularly limited as long as it can exhibit molecular sieving ability appropriately.

The molecular sieve membrane may be either an organic membrane or an inorganic membrane, but an inorganic membrane is preferable. The inorganic membrane is preferably a zeolite membrane, a silica membrane, or a carbon membrane, or a combination thereof. Among them, a zeolite membrane or a silica membrane is preferred, and a zeolite membrane is particularly preferred from the viewpoint of separation performance, water resistance, and durability. is preferred.

Here, when a zeolite membrane is used as the molecular sieve membrane, the zeolite is preferably an aluminosilicate, but Ga, Fe, B, Ti, Zr, Sn, Zn, etc., can be used instead of Al as long as the performance of the membrane is not significantly impaired. may be used, and elements such as Ga, Fe, B, Ti, Zr, Sn, Zn, and P may be included together with Al.

In addition, the skeleton of the crystalline zeolite that forms the pores of the zeolite membrane is preferably an oxygen 8-membered ring or less, more preferably an oxygen 6- to 8-membered ring.

Examples of zeolite structures include AEI, AFG, ANA, CHA, DDR, EAB, ERI, ESV, FAR, FRA, GIS, ITE, KFI, LEV, LIO, LOS, LTA, LTN, MAR, MWF, PAU, RHO , RTH, SOD, STI, TOL, UFI, and the like. Among these, it is preferable to use a membrane composed of AEI, CHA, DDR, ERI, KFI, LEV, MWF, PAU, RHO, RTH, SOD, LTA, UFI-type zeolite, and CHA, DDR, MWF, RHO, It is more preferable to use a membrane composed of SOD-type zeolite. The n value of zeolite having n-membered oxygen rings indicates the largest number of oxygen atoms among the pores composed of the zeolite skeleton and T elements (elements other than oxygen constituting the skeleton).

When synthesizing a zeolite membrane as a molecular sieve membrane, an organic template (structure directing agent) can be used as necessary, but usually there is no particular limitation as long as the template can create the desired zeolite structure, and there is no template. It is not necessary to use if it is possible to synthesize with

Although the thickness of the molecular sieve membrane is not particularly limited, the lower limit of the thickness of the zeolite membrane is usually 0.01 μm or more. The upper limit of the thickness is preferably 30 μm or less, more preferably 10 μm or less. The silica film may be a film consisting of a single layer or a film consisting of two or more layers, and the thickness thereof is preferably 1 nm or more. The thickness is preferably 10 μm or less, more preferably 1 μm or less. The carbon film preferably has a thickness of 0.05 μm or more, and more preferably 0.1 μm or less. The upper limit of the thickness is preferably 5 mm or less, more preferably 500 μm or less.

The method of forming the molecular sieve on the surface of the porous substrate is not limited to the above-mentioned methods. For example, (1) a method in which a substance capable of forming a molecular sieve is adhered to the surface of a porous substrate with a binder or the like, and (2) a porous substrate is impregnated with a slurry or solution in which a substance capable of forming a molecular sieve is dispersed. and (3) a method of crystallizing a substance (especially zeolite) that can constitute a molecular sieve membrane on the surface of the porous substrate into a film. For example, see International Publication No. 2013/125660 pamphlet, etc.).

[Compressor unit]
The dehydrator of the present invention includes one or more compressor units. A compressor unit of the present invention includes one or more compressors.

[Compressor]
A compressor imparts energy to a fluid to change the pressure of the fluid. As the compressor, a positive displacement compressor that changes the pressure by reducing the volume of fluid is preferable. Among them, a vapor compressor, a vacuum pump, and an ejector are preferable from the viewpoint of being able to compress a fluid under negative pressure conditions. An ejector is more preferable from the viewpoint of high energy-saving performance. Among the ejectors, both the steam used as the driving force and the fluid drawn by the ejector can be directly introduced into the subsequent processing equipment, so that the energy loss can be minimized and transferred to the subsequent processing. A steam ejector is preferable from the viewpoint of efficiency. When the compressor is a steam ejector, the fluid that has passed through the compressor is a combination of the fluid that has passed through the compressor and the steam.

One compressor may be used alone, or a plurality of compressors may be connected and used. The connection pattern of the compressor is shown in FIG. FIG. 7 is a diagram when a steam ejector is used as a compressor. (a) is a diagram in which a single compressor is used, (b) is a diagram in which two compressors are connected in series, and (c) is a diagram in which two compressors are connected in series in parallel. It is a figure which connected two rows with. Reference numeral 9 indicates a separation membrane module, and reference numeral 12 indicates a steam ejector. When using a plurality of compressors, all may be arranged in series, all may be arranged in parallel, or a combination of series and parallel may be arranged. When arranging the compressors in series and in parallel, it is preferable to arrange in parallel a plurality of compressors in a row, each of which is a series connection of a plurality of compressors. At this time, it is preferable to set the number of compressors in each row to be the same, because this facilitates the design of the process for controlling each compressor.

When a steam ejector is used as a compressor, the value obtained by dividing the amount of steam supplied to one steam ejector by the total fluid amount of the steam amount and the fluid to be compressed supplied to the steam ejector is 0.65 or more. It is preferably 0.999 or less, more preferably 0.75 or more and 0.999 or less, and particularly preferably 0.75 or more and 0.98 or less. Within the above range, operation can be performed with the minimum amount of steam necessary for compressing the fluid to be compressed, and the fluid to be compressed can be efficiently compressed.

When a steam ejector is used as a compressor, the compression ratio obtained by dividing the discharge pressure of one steam ejector by the suction pressure of the fluid is preferably 1 or more and 20 or less, more preferably 1 or more and 15 or less, and particularly 1 or more and 10 or less. preferable. By being within the above range, efficient compression can be achieved while reducing energy loss due to heat radiation generated during compression.

[Dehydration system]
The dehydration system of the present invention comprises a separation membrane module group having at least one separation membrane module comprising a plurality of distillation columns including a first distillation column and a second distillation column, and a separation membrane module that selectively permeates water. , one or more separation membrane units, and one or more compressor units comprising one or more compressors, the first distillation column, the second distillation column, and the separation membrane module group , one or more of the compressor units, and the first distillation column are arranged in order.

　The permeation side of the separation membrane module group is connected to the inlet side of the compressor unit. The outlet side of the compressor unit is connected to a distillation column whose operating pressure is less than or equal to the pressure on the outlet side of the compressor unit and which is different from the distillation column that supplies the fluid to be enriched to the separation membrane module unit.

When the separation membrane unit has a plurality of separation membrane modules, the permeate sides of all the separation membrane modules may be connected to the inlet side of one compressor unit.

When the separation membrane unit includes the first separation membrane module group and the second separation membrane module group, the permeate side of either the first separation membrane module group or the second separation membrane module group is the compressor unit. and the outlet side of the compressor unit may be connected to the first distillation column.

At this time, of the first separation membrane module group and the second separation membrane module group, the permeate side of the separation membrane module group that is not connected to the compressor unit is condensed and cooled using refrigerant. It may be connected to a condenser that allows the gas to flow, or may be connected to the first distillation column.

From the viewpoint of efficiently recovering heat from the fluid on the permeate side, it is preferable to connect the permeate side of the second separation membrane module group to the compressor unit and connect it to the first distillation column. In this case, the permeate side of the first separation membrane module group is preferably connected to a condenser, and more preferably connected to a distillation column different from the first distillation column. and the fluid on the permeate side of the first separation membrane module group are combined and connected to the first distillation column.

When the separation membrane unit includes a first separation membrane module group and a second separation membrane module group, and has a first compressor unit and a second compressor unit as compressor units, the first separation membrane The permeate side of the module group may be connected to the inlet side of the first compressor unit, and the permeate side of the second separation membrane module group may be connected to the inlet side of the second compressor unit.

In this case, the outlet side of the first compressor unit may be connected to the second distillation column and the outlet side of the second compressor unit may be connected to the first distillation column,
Both the outlet side of the first compressor unit and the outlet side of said second compressor unit may be connected to the first distillation column.

The separation membrane unit includes a first separation membrane module group and a second separation membrane module group, and the compressor units include a first compressor unit, a second compressor unit, and a third compressor unit. If so, connecting the outlet side of each of the first compressor unit and the second compressor unit to the inlet side of the third compressor unit, the outlet side of the third compressor unit being connected to the first distillation It may be connected to a tower.

Although the following description will be made with reference to the drawings, the dehydration system described in the drawings or described below is an example and is not limited to this.

Regarding the dehydration of the fluid to be treated by the separation membrane module group below, the pervaporation method or the vapor permeation method may be used.

An example of a dehydration system and a dehydration method according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing one aspect of the dehydration system according to the present invention.

This dehydration system basically comprises a first distillation column 1a, a second distillation column 1b, a third distillation column 1f, a separation membrane unit including a first separation membrane module group 1c, and a steam ejector 1d, Distillation and membrane separation are used to separate water from a treated fluid containing a mixture of water-soluble organic compounds and water. In FIG. 1, the separation membrane unit includes a first separation membrane module group 1c, and the first separation membrane module group 1c includes one separation membrane module. A compressor (not shown) is connected to the top of the first distillation column 1a, and the compressed top fluid is heat-exchanged with water. Although a multiple-effect distillation column is used in which the overhead vapor of the second distillation column 1b is used as a heat source for the bottom reboiler of the first distillation column 1a, the multiple-effect process is not limited to this.

In the dehydration system shown in FIG. 1, a liquid, which is a fluid to be treated containing at least a water-soluble organic compound and water, is introduced as a raw material into the first distillation column 1a.

The first distillation column 1a separates the fluid to be treated into overhead vapor containing gaseous water-soluble organic compounds and bottoms consisting of liquid water. The overhead vapor is supplied to the second distillation column 1b and the third distillation column 1f. The type of the first distillation column 1a is not particularly limited as long as it is suitable for the distillation operation, such as a tray type. The operating pressure of the first distillation column is set to be equal to or lower than the pressure on the outlet side of the steam ejector 1d in order to prevent the fluid permeated from the separation membrane module group 1c from flowing back. The first distillation column 1a is preferably a vacuum distillation column. Also, when the fluid to be treated is supplied from a fermenter, it is preferably a moromi tower.

Part of the liquid at the bottom of the first distillation column 1a is a fluid introduced from the steam ejector 1e and a compressor (not shown) connected to the top of the first distillation column 1a. The vapor is heated by the water heated by the steam and the water heated by the overhead steam of the third distillation column 1f to become steam, and rises in the column while exchanging heat with the liquid flowing down the column. For this reason, most of the vapor component is water at the bottom of the column, but the concentration of water-soluble organic compounds increases near the top of the column. The rest of the liquid taken out from the bottom of the column is taken out as a bottom product.

The second distillation column 1b and the third distillation column 1f can carry out various distillations such as pressurized distillation, normal pressure distillation, vacuum distillation, etc. in order to utilize multiple effects. The number of stages of the second distillation column 1b and the third distillation column 1f is not particularly limited, and can be appropriately determined according to the required concentration specifications of the water-soluble organic compound. In addition, in the second distillation column 1b and the third distillation column 1f, it is preferable to concentrate the raw material to approximately 85.0% by mass or more of the water-soluble organic compound, for example, the required concentration specification (specification) is 99.0 When it is more than 99.9% by mass, it is preferably 85.0% by mass or more and less than 99.0% by mass, and when the required concentration specification is 99.9% by mass or more, 85% by mass Although it is preferable to concentrate the water-soluble organic compound to 0.0% by mass or more and less than 99.9% by mass, the range is not particularly limited.

The overhead vapors of the second distillation column 1b and the third distillation column 1f are introduced into the first separation membrane module group 1c as a fluid to be concentrated. The concentrated fluid discharged from the concentration-side outlet of the first separation membrane module group 1c is heat-recovered by a heat exchanger connected to the bottom of the second distillation column 1b, and is recovered as a product. The method used is not limited to this.

The permeate-side fluid coming out of the permeate-side outlet of the first separation membrane module group 1c is introduced into the steam ejector 1d, and introduced into the first distillation column 1a from the outlet side of the steam ejector 1d. The non-permeate side fluid coming out of the non-permeate side outlet of the first separation membrane module group 1c is heat-recovered in the second distillation column 1b via a heat exchanger and recovered in a product tank (not shown).

FIG. 2 is another example of an embodiment of the dehydration system and dehydration method of the present invention. In this aspect, the separation membrane unit comprises a first separation membrane module group 2c and a second separation membrane module group 2d.

This dehydration system includes a separation membrane unit including a first distillation column 2a, a second distillation column 2b, a third distillation column 2f, a first separation membrane module group 2c, a second separation membrane module group 2d, and A steam ejector 2e is used as a basic configuration.

In the dehydration system shown in FIG. 2, the first distillation column 2a is fed with a liquid, which is a fluid to be treated containing at least water-soluble organic compounds and water, as a raw material.

The first distillation column 2a separates the fluid to be treated into overhead vapor containing gaseous water-soluble organic compounds and bottoms consisting of liquid water. The overhead vapor is supplied to the second distillation column 2b and the third distillation column 2f. The type of the first distillation column 2a is not particularly limited as long as it is suitable for the distillation operation, such as a tray type. The operating pressure of the first distillation column 2a is set at the outlet side of the steam ejector 2e so that the mixed fluid in which the outlet side fluid of the steam ejector 2e and the permeation side fluid of the separation membrane module group 2c are mixed does not flow back. Keep under pressure.

The first distillation column 2a is preferably a vacuum distillation column. Also, when the fluid to be treated is supplied from a fermenter, it is preferably a moromi tower.

Part of the bottom liquid in the first distillation column 2a is the fluid introduced from the steam ejector 2e and the permeation side of the separation membrane module group 2c, and the compressor connected to the top of the first distillation column 2a. (not shown) and the water heated by the overhead steam of the third distillation column 2f is heated to become steam and heat exchange with the liquid flowing down the column. While ascending the tower. For this reason, most of the vapor component is water at the bottom of the column, but the concentration of water-soluble organic compounds increases near the top of the column. The rest of the liquid taken out from the bottom of the column is taken out as a bottom product.

Since the second distillation column 2b and the third distillation column 2f utilize multiple effects, various distillations such as pressurized distillation, normal pressure distillation, and vacuum distillation can be performed. The number of stages of the second distillation column 2b and the third distillation column 2f is not particularly limited, and can be appropriately determined depending on the required concentration specifications of the water-soluble organic compound. In addition, in the second distillation column 2b and the third distillation column 2f, it is preferable to concentrate the raw material to approximately 85.0% by mass or more of the water-soluble organic compound, for example, the required concentration specification (specification) is 99.0 When it is more than 99.9% by mass, it is preferably 85.0% by mass or more and less than 99.0% by mass, and when the required concentration specification is 99.9% by mass or more, 85% by mass Although it is preferable to concentrate the water-soluble organic compound to 0.0% by mass or more and less than 99.9% by mass, the range is not particularly limited.

The overhead vapors of the second distillation column 2b and the third distillation column 2f are introduced into the first separation membrane module group 2c as a fluid to be concentrated. The first concentrated fluid coming out of the concentration-side outflow port of the first separation membrane module group 2c enters as the fluid to be concentrated from the supply port of the fluid to be concentrated of the second separation membrane module group 2d. The second concentrated fluid discharged from the concentration side outlet of the second separation membrane module group 2d is heat-recovered by a heat exchanger connected to the bottom of the second distillation column 2b and recovered as a product. , the method of heat recovery is not limited to this.

The first permeate-side fluid concentrated in the first separation membrane module group 2c is introduced into the first distillation column 2a. The second permeate-side fluid concentrated in the second separation membrane module group 2d is introduced into the steam ejector 2e and introduced into the first distillation column 2a from the outlet side of the steam ejector 2e. The non-permeate side fluid coming out of the non-permeate side outlet of the second separation membrane module group 2d is heat-recovered in the second distillation column 2f via a heat exchanger and recovered in a product tank (not shown).

Note that in FIG. 2, the number of separation membrane modules included in the first separation membrane module group 2c and the number of the separation membrane modules included in the second separation membrane module group 2d are one each.

FIG. 3 shows a first comparative example. In this first comparative example, no membrane separation device is installed, and the fluid to be concentrated is dehydrated only by the PSA 3c, and the desorbed fluid of the PSA 3c is introduced into the first distillation column 3a via the condenser 3d. The concentrated fluid coming out of the PSA 3c is heat-recovered in the second distillation column 3f through a heat exchanger and recovered in a product tank (not shown).

In this method, one adsorption column and the other desorption column are operated while being switched, so the fluid to be desorbed becomes an intermittent flow that makes it difficult to establish a heat recovery process. Therefore, the desorbed fluid is intermittently condensed and cooled by the condenser 3d using refrigerant, temporarily stored in a tank (not shown), and then continuously fed by a liquid feed pump (not shown). After forming the stream, it is introduced into the first distillation column 3a. In addition, since the desorption process uses a fluid in which water-soluble organic compounds have been concentrated through the adsorption process, the concentration of the water-soluble organic compounds in the desorbed fluid can be determined using the membrane separation units shown in FIGS. It becomes higher than the concentration of water-soluble organic compounds in the permeated fluid on the permeation side. In this way, from the viewpoint of the concentration of the water-soluble organic compounds in the desorbed fluid and the viewpoint of intermittent operation, sufficient heat recovery is not possible, and a large amount of water-soluble organic compounds is accumulated in the first distillation column. Since it is returned to 3a, as will be described later, the result is a high CO ₂ emission amount per purified amount of water-soluble organic compounds.

FIG. 4 shows a second comparative example. In this second comparative example, the permeate side fluid of the separation membrane module group 4c is introduced into the first distillation column 4a through the condenser 4d. In this method, as compared with the process using PSA shown in FIG. (not shown)), and then introduced into the first distillation column 4a by a liquid feed pump (not shown).

Therefore, the heat of the permeate-side fluid of the separation membrane module group 4c cannot be sufficiently recovered, and energy for cooling the condenser is required. The required energy per refined amount is high.

FIG. 5 shows a third comparative example. In this third comparative example, the permeation-side fluids of the first separation membrane module group 5c and the second separation membrane module group 5d pass through the condensers 5e and 5g, respectively, to the first distillation column 5a. be introduced. The non-permeate side fluid coming out of the non-permeate side outlet of the second separation membrane module group 5d is heat-recovered in the second distillation column 5f via a heat exchanger and recovered in a product tank (not shown).

In the specific embodiment shown in FIG. 4, it was necessary to condense and cool the entire permeate-side fluid that permeated the separation membrane module unit with a low-temperature refrigerant, but in the specific embodiment shown in FIG. By dividing the module units into the separation membrane module group 5c and the separation membrane module group 5d, energy consumption can be reduced by reducing the amount of low-temperature refrigerant required for condensation and cooling. However, due to the condensation and cooling in the condensers 5e and 5g, the energy of the permeation-side fluid in the separation membrane module group 5c and the second separation membrane module group 5d is not recovered as heat. This results in a higher energy requirement per purified amount of water-soluble organic compounds than the process.

Further, in the above-described embodiment, there are three distillation columns, the first distillation column, the second distillation column, and the third distillation column, but only the first distillation column and the second distillation column may be used, Four or more distillation columns may be provided.

The present invention will be specifically described below based on examples, but the present invention is not limited to these.

[Basic conditions]
The raw material composition was EtOH:H2O=3.35:96.65 (wt/wt), and the product concentration was EtOH:H2O=99.7:0.3 (wt/wt). The raw material flow rate was 20,750 kg/h and the product flow rate was 693 kg/h.
The PSA inlet temperature was set equal to the separation membrane unit inlet temperature.

The first distillation column was a moromi column, the operating pressure was 8 kPaA, and the EtOH concentrations in the feed liquid, column top, and column bottom were 3.35 wt%, 26.82 wt%, and 100 ppm, respectively.

The second distillation column was a high-pressure distillation column, the operating pressure was 448 kPaA, and the EtOH concentrations in the feed liquid, column top, and column bottom were 26.82 wt%, 91.3 wt%, and 100 ppm, respectively.

The third distillation column was a medium-pressure distillation column, the operating pressure was 82.8 kPaA, and the EtOH concentrations in the feed liquid, column top, and column bottom were 26.82 wt%, 91.3 wt%, and 100 ppm, respectively.

The CO ₂ conversion factor for steam used as a utility was set at 2.71 tCO ₂ /kL, and the CO ₂ conversion factor for electricity used to produce electricity, cooling water, and low-temperature refrigerant was set at 0.00047 tCO ₂ /kWh.

The EtOH concentrations of the PSA supply liquid, concentrated liquid, and desorbed liquid were 91.3 wt%, 99.7 wt%, and 68.7 wt%, respectively.

When there is one membrane separation module group and the number of membrane separation modules included in the membrane separation module group is one, EtOH of the fluid to be concentrated (supply liquid), the concentrated fluid (concentrated liquid), and the permeate side fluid (permeate liquid) The concentrations were 91.3 wt %, 99.7 wt %, and 4 wt %, respectively.

When there are two membrane separation module groups, a first separation membrane module group and a second separation membrane module group, and the number of membrane separation modules included in each membrane separation module group is one, the first separation membrane module group The EtOH concentrations of the fluid to be concentrated (supply liquid), concentrated fluid (concentrated liquid), and permeate-side fluid (permeated liquid) were set to 91.3 wt%, 98.0 wt%, and 2 wt%, respectively. The EtOH concentrations of the to-be-concentrated fluid (supply fluid), concentrated fluid (concentrated fluid), and permeate-side fluid (permeated fluid) were 98.0 wt %, 99.7 wt %, and 11.7 wt %, respectively.

[Example 1]
A water-ethanol mixture is introduced into the first distillation column 2a, and overhead vapor is supplied to the second distillation column 2b and the third distillation column 2f. After obtaining crude alcohol in the second distillation column 2b and the third distillation column 2f, the entire amount of the crude alcohol is introduced into the first separation membrane module group 2c, and then concentrated in the first separation membrane module group 2c. The first concentrated fluid coming out of the side outlet is introduced into the second separation membrane module group 2d. The second permeate-side fluid coming out of the permeate-side outlet of the second separation membrane module group is introduced into the steam ejector 2e, and the fluid coming out of the outlet of the steam ejector 2e is introduced into the permeate-side of the first separation membrane module group 2c. It is introduced into the first distillation column 2a together with the first permeate side fluid coming out of the outlet.

An evaluation of the process using the dehydration system of FIG. 2 resulted in CO ₂ emissions per product flow rate for all utilities of 3.38×10 −4 tCO ₂ /kg-alcohol.

[Comparative Example 1]
A water-ethanol mixture is introduced into the first distillation column 3a, and overhead vapor is supplied to the second distillation column 3b and the third distillation column 3f. After obtaining the crude alcohol in the second distillation column 3b and the third distillation column 3f, the process using the dehydration system of FIG. CO ₂ emissions per unit amounted to 3.66×10 −4 tCO ₂ /kg-alcohol.

[Comparative Example 2]
A water-ethanol mixture is introduced into the first distillation column 5a, and overhead vapor is supplied to the second distillation column 5b and the third distillation column 5f. After obtaining crude alcohol in the second distillation column 5b and the third distillation column 5f, the entire amount of the crude alcohol is introduced into the first separation membrane module group 5c, and then permeated through the first separation membrane module group 5c. The first permeate-side fluid coming out of the side outlet is passed through the condenser 5e to be the first condensate. The first concentrated fluid coming out of the concentration-side outlet of the first separation membrane module group 5c is introduced into the second separation membrane module group 5d. The second permeate-side fluid coming out of the permeate-side outlet of the second separation membrane module group 5d passes through the condenser 5g and is used as the second condensate. Evaluated for a process using the dehydration system of _FIG . , 3.45×10 −4 tCO ₂ /kg-alcohol.

The process using the dewatering system of the present invention, shown in Example 1, compared to the process using PSA of Comparative Example 1 and the process without compressor of Comparative Example 2, _CO2 emissions per product flow rate quantity has decreased.

INDUSTRIAL APPLICABILITY The present invention can be advantageously used, for example, as a means for dehydrating and concentrating a high-concentration water-soluble organic compound from a mixture of a water-soluble organic compound such as ethanol and water. Extremely high.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2021-39347 filed on March 11, 2021, which is incorporated by reference in its entirety.

1a, 2a, 3a, 4a, 5a First distillation column 1b, 2b, 3b, 4b, 5b Second distillation column 1f, 2f, 3f, 4f, 5f Third distillation column 1c, 2c, 4c, 5c 1 separation module group 2d, 5d second separation module group 1d, 2e, 12 steam ejector 3c PSA
4d, 5e, 5f condenser 6 separation membrane unit 7 first separation membrane module group 8 second separation membrane module group 9 separation membrane module 10 first collection pipe 11 second collection pipe

Claims (13)

1. A dehydration system for separating water from a fluid to be treated containing water and water-soluble organic compounds,
   a plurality of distillation columns including a first distillation column and a second distillation column;
   one or more separation membrane units;
   one or more compressor units;
   The separation membrane unit has one or more separation membrane module groups,
   The separation membrane module group has a separation membrane module comprising one or more separation membranes that selectively permeate water,
   The compressor unit comprises one or more compressors;
   The first distillation column, the second distillation column, one or more of the separation membrane module groups, and one or more of the compressor units are arranged in order, and one or more of the compressor units is connected to the outlet side of the first distillation column,
   dehydration system.
2. the permeate sides of all the separation membrane modules included in the separation membrane module unit are connected to the inlet side of the compressor unit;
   A dewatering system according to claim 1 .
3. the separation membrane unit includes a first separation membrane module group and a second separation membrane module group,
   the permeate side of either the first separation membrane module group or the second separation membrane module group is connected to the inlet side of the compressor unit;
   A dehydration system according to claim 1 .
4. Of the separation membrane module group, the permeation side of the separation membrane module group that is not connected to the compressor unit is connected to a condenser.
   The dehydration system according to claim 3.
5. Among the separation membrane modules, the permeation side of the separation membrane module group that is not connected to the compressor unit is connected to the first distillation column.
   The dehydration system according to claim 3.
6. the separation membrane unit includes a first separation membrane module group and a second separation membrane module group,
   The compressor unit includes a first compressor unit and a second compressor unit,
   the permeate side of the first separation membrane module group is connected to the inlet side of the first compressor unit;
   the permeate side of the second separation membrane module group is connected to the inlet side of the second compressor unit;
   A dewatering system according to claim 1 .
7. the outlet side of the first compressor unit is connected to the second distillation column;
   the outlet side of the second compressor unit is connected to the first distillation column;
   A dehydration system according to claim 6 .
8. the outlet side of the first compressor unit and the outlet side of the second compressor unit are connected to the first distillation column;
   A dehydration system according to claim 6.
9. further comprising a third compressor unit;
   each outlet side of the first compressor unit and the second compressor unit is connected to an inlet side of a third compressor unit;
   the outlet side of the third compressor unit is connected to the first distillation column;
   A dehydration system according to claim 6.
10. A dehydration system according to any one of the preceding claims, wherein the compressor unit comprises one or more compressors connected in series and/or one or more compressors arranged in parallel.
11. The dehydration system according to any one of claims 1 to 10, wherein the operating pressure of the first distillation column is lower than the operating pressure of the second distillation column.
12. The dehydration system according to any one of claims 1 to 11, wherein the first distillation column is a vacuum distillation column and the second distillation column is a high pressure distillation column.
13. A dehydration method for separating water from a fluid to be treated containing water and water-soluble organic compounds,
    The operating pressure of the first distillation column is equal to or lower than the outlet pressure of the compressor unit.
    A dehydration method using the dehydration system according to any one of claims 1 to 12.
    
    
    

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