JPS62270537A - Recovery of butanol from butanol-containing waste water - Google Patents

Abstract

PURPOSE:To contrive energy saving and compaction of an apparatus, by removing water from a butanol-water based mixture by a reverse osmosis method and separating two layers by density difference between the water and butanol in recovering the butanol from butanol-containing waste water. CONSTITUTION:Water is removed from a butanol-water based mixture 53 as a permeated water 58 using a cellulose acetate membrane, etc., by a reverse osmosis method using a reverse osmosis module 56 to concentrate the butanol to above a solubility (7.8wt% at 20 deg.C) in water and separate the water and butanol into two layers by the density difference thereof (specific gravity of the butanol is 0.81 at 20 deg.C). Thereby the pure butanol 60 is advantageously recovered from the butanol-containing waste water. According to this method, running cost and initial cost can be reduced to 1/2 of those in a conventional method (distillation method). Furthermore, continuous operation can be performed if the mixture 53 in an amount equal to that of the permeated water 58 and recovered butanol 60 as raw water 51 is fed to a circulation tank 52.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for recovering butanol from butanol wastewater. [Prior Art] Conventionally, butanol is recovered from butanol wastewater by a distillation method.

Distillation is a method of separation and purification using the difference in component concentration between liquid and vapor, and distillation is used to recover butanol from an aqueous butanol solution, as shown in FIG.

A butanol aqueous solution (hereinafter referred to as stock solution) 1 is fed into the middle stage of the dehydration distillation column 5, and boiler steam 2 is introduced into the reboiler 4, where it is heated from the bottom of the column. The butanol component is concentrated as it reaches the upper stage of the distillation column 5. *The mixed vapor of the condensed butanol vapor and water vapor is condensed and cooled in the condenser 6, and then separated into two layers based on the difference in specific gravity in the decanter 9. The separated water 1° containing some butanol is returned (refluxed) to the top of the distillation column 5, and the separated butanol 11° is
will be collected. On the other hand, water in the stock solution 1 is separated from the bottom of the tower and discharged as waste water 8.

Incidentally, a distillation column is generally constructed by stacking a large number of trays (shelves) and separates components by bringing liquid and vapor into contact. The conventional distillation method involves a phase change, requires a large amount of energy, and is poor in energy saving.

In addition, the distillation method requires multi-stage equipment and is large in size, so there is a problem in that it lacks combustibility.

The present invention aims to provide a method for recovering butanol that is more energy efficient and more compact than a butanol aqueous solution.

[Means for solving problems]

The present invention removes water from a butanol-water mixture by reverse osmosis and concentrates it to a level higher than the solubility of butanol in water, thereby reducing the density difference Kj, ? This is a method for recovering butanol from butanol-containing wastewater, which is characterized by separation into two layers.

The membrane used in the reverse osmosis method of the present invention can be any of the reverse osmosis membranes used in this type of technology, such as cellulose acetate membranes, as well as polyamide-based, heterocyclic polymer-based,
Any synthetic membrane based on water-soluble polymer crosslinking or dipolymerizable monomer (crosslinking) may be used.

[Function] By removing only water from a butanol-water mixed solution by reverse osmosis and concentrating it to a level higher than the solubility of butanol in water, water and butanol can be separated into two layers due to the difference in density. As shown in FIG. 1, a butanol aqueous solution 53 (butanol + water-earth ionic impurities) in a circulation tank 52 is pressurized (usually 40 to 70 kg/Cdt) by a high-pressure pump 55.
G) and water is passed through the reverse osmosis module 56. The reverse osmosis module 56 uses a cellulose acetate membrane 2 synthetic membrane, etc., and this membrane separates the permeate water 58 into permeate water 58 and concentrated water 57 (butanol + water-soil ionic impurities).
The concentrated water 57, which can be drained because it is close to pure water, is depressurized by the pressure reducing valve 59 and returned to the circulation tank 52. lol
i'f In the JI tank 52, the butanol concentration gradually rises, and the butanol concentration reaches the solubility (7.a at 20°0).
wt%), it is separated into an upper layer in the circulation tank 52 (the specific gravity of butanol is 0.81 at 20°0) and can be recovered as pure butanol 54. In addition, in this treatment method, permeated water 58 and recovered butanol 60
Continuous operation is possible by supplying an amount equal to the raw water 51 to the circulation tank 52. [Example] The present invention was carried out according to the flow shown in FIG. 1. The raw water 51 is an aqueous solution with a butanol concentration of 2 wt%. Adashi,
10001 in circulation tank 52! It was continuously supplied at a flow rate of /H. 50kg of butanol aqueous solution 53 with high pressure pump 55
/a/IG, pmo-1o manufactured by Toshiku Co., Ltd.
oo membrane is supplied to the reverse osmosis module 56, α1w
t4 butanol-containing water as permeated water 58 and 975/
/H got it. Concentrated water 57 is depressurized with a pressure reducing valve 59 and returned to the circulation tank 52 as recovered butanol 60 with a water concentration of 2 g.
25//H of wt% butanol water was obtained.

The following table shows a rough comparison of costs when treating butanol-containing wastewater (butanol concentration: 2wt%) using the conventional method (distillation method) and the above embodiment of the present invention. By using the method of the present invention for the recovery method, the running cost and initial cost can be reduced to 1/2 compared to the conventional method (distillation method).
It becomes possible to

[Brief explanation of drawings]

FIG. 1 is a diagram showing the flow of one embodiment of the present invention, and FIG. 2 is a diagram showing the flow of a conventional distillation method. Explanation of the components in Figure 1 51-kai・φ raw water, 52-fist・-circulation tank, 53・111
1 Butanol aqueous solution, 54...Butanol-55...
・High pressure pump, 56-・Reverse osmosis module, 57...
・Concentrated water, 58...Water, 59...Reducing valve, 60@・
・Recovered butanol 0 Sub-agents 1) Meifuku agent Ryo Hagiwara − Sub-agent Atsuo Anzai

Claims (1)

[Claims] Recovering butanol from butanol-containing wastewater by removing water from a butanol-water mixture by reverse osmosis and concentrating it to a level higher than the solubility of butanol in water, which separates water and butanol into two layers due to the density difference. Law.