JP2651072B2 - Recovery method for ethylene glycols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering ethylene glycols and solids by solid-liquid separation of an evaporation residue of ethylene glycol waste liquid using an organic solvent.

[0002]

2. Description of the Related Art Ethylene glycol is a useful chemical obtained by petrochemicals, and a waste liquid containing ethylene glycol is subjected to a dehydration treatment, and then ethylene glycol is recovered by distillation. Alternatively, it was discarded as industrial waste. However, useful components such as ethylene glycol are contained in the evaporation residue, and incineration or disposal is not economical in terms of resources, and is becoming a serious environmental problem.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been intensively studied in order to recover ethylene glycols and other useful components by a simple method from the evaporation residue of the incinerated or discarded ethylene glycol waste liquid. As a result, they have found that by adding a specific organic solvent to the evaporation residue of ethylene glycol waste liquid, solid-liquid separation is possible, and a solid product consisting of ethylene glycols and sodium formate can be recovered, and the present invention has been achieved. .

[0004]

According to the method for recovering ethylene glycol of the present invention, an organic solvent such as alcohols, ethers or ketones is added to the evaporation residue of ethylene glycol waste liquid at a weight ratio of 0 to 1 for the evaporation residue. 0.2 to 1.0 were added and stirred, the resulting mixture was subjected to solid-liquid separation, and the filtrate was distilled to separate an organic solvent and ethylene glycols.

Further, the method of recovering a solid material comprising sodium formate according to the present invention is characterized in that an organic solvent such as alcohols, ethers or ketones is added to the evaporation residue of ethylene glycol waste liquid in a weight ratio with respect to the evaporation residue. 0.2 to 1.0 were added and stirred, and the resulting mixture was subjected to solid-liquid separation.

Further, the present invention relates to a method of using the solid product thus obtained as an alkali source for neutralizing waste water.

Hereinafter, the present invention will be described in more detail with reference to FIG.

[0008] The dehydrated ethylene glycol waste liquid is distilled and separated into ethylene glycol, diethylene glycol and triethylene glycol by a distillation column 1, and the evaporation residue, which is a viscous liquid containing solids, is withdrawn from an evaporator and stirred. Is transferred by a pump to the dissolving tank 2 provided with Generally, the evaporation residue consists of 45-55% of ethylene glycols and 55-45% of non-volatile components (solids).

By adding an organic solvent to the evaporation residue in the dissolving tank 2, ethylene glycol is dissolved and its viscosity is reduced to facilitate solid-liquid separation. The weight ratio of the evaporation residue to the organic solvent is 0.2-1.0, preferably 0.3-0.7. If it is less than 0.2, it is difficult to dissolve ethylene glycols.

As the organic solvent used in the present invention, those which dissolve ethylene glycols and do not dissolve solids are used. Specifically, alcohols such as methanol, ethanol and isopropyl alcohol, and acetone such as acetone are used. Ketones and ethers such as diethyl ether are used. In particular, lower alcohols such as methanol and ethanol are preferred because the yield of the solid product is good, the loss is small, and good results are obtained.

As for the dissolution conditions, it is preferable to dissolve the residue and the organic solvent while mixing them under stirring at normal pressure, and the temperature may be either room temperature or heating, and is generally carried out at 40-60 ° C. In some cases, it may be performed under pressure. The dissolution time is preferably 0.5-2 hours, more preferably 1.0-1.5 hours.

The thus obtained mixture of the organic solvent and the evaporation residue of the ethylene glycol waste liquid is separated into an organic solvent containing ethylene glycols and a solid by a filter 3 with a pump. As the filter, any type may be used as long as it can separate the solid matter and the organic solvent containing ethylene glycol, and a normal filter press, a centrifugal separator, and a filter such as a reduced pressure filter are used. In particular, a centrifuge is preferred. Filtration is performed under ordinary filtration conditions, and solid-liquid separation into an organic solvent containing ethylene glycols and a solid is performed.

The separated solid product 4 contains sodium formate
Sodium formate, sodium carbonate and sodium bicarbonate can be recovered by an appropriate method from this, but it can be dissolved in water as it is at 20-30% and used as an alkaline source for neutralizing wastewater. can do. Since the solid product of the present invention contains sodium formate as a main component as described above, it does not cause a eutrophication phenomenon of wastewater as in conventional neutralization treatment with ammonia water as an alkaline source for wastewater neutralization. Is an environmentally preferred alkali source.

The organic solvent containing ethylene glycol is once stored in the recovery liquid tank 5 and sent to the distillation column 6, where the organic solvent and ethylene glycol are separated by distillation. The organic solvent is distilled from the upper part of the tower, collected in the organic solvent tank 8, sent to the dissolving tank 2 again, and used repeatedly. The organic solvent which became insufficient due to the loss is replenished here. Ethylene glycols 7 are recovered from the lower part of the column and separated as ethylene glycol, diethylene glycol and triethylene glycol by another distillation column. In the reboiler 9, solid matter mixed in the liquid part is obtained in the form of a concentrated residue, which is collected and collected in the dissolving tank 2.
And recovered again as a solid by solid-liquid separation.

The distillation conditions vary depending on the solvent used,
Vacuum distillation is preferably 200-400 torr, more preferably 25 torr.
Performed at 0-350 torr. For example, the distillation temperature of methanol is preferably 150 ° C. at the bottom of the column and 45 ° C. at the top of the column.

According to such a method, for example, methanol 5 is added to 100 parts by weight of the evaporation residue of ethylene glycol waste liquid containing 45-55% of ethylene glycols and 55-45% of solids.
When 0 parts by weight are added and solid-liquid separation is performed, about 43 parts by weight of methanol is recovered, and 3-7 parts by weight of ethylene glycol, 14-30 parts by weight of diethylene glycol, and 7-16 parts by weight of triethylene glycol can be recovered. 25-35 parts by weight during filtration and separation, 16
-20 parts by weight, a total of 40-55 parts by weight can be obtained, and resources can be effectively recovered.

Hereinafter, the present invention will be specifically described with reference to examples.

[0018]

EXAMPLES Example 1 Evaporation residue from ethylene glycol waste liquid after recovering ethylene glycol in a distillation column contains 7.4% by weight of ethylene glycol, 30.7% by weight of diethylene glycol, 16.4% by weight of triethylene glycol, and 45.2% by weight of non-volatile components. At room temperature -80 ° C.

This evaporation residue was transferred by a pump to a dissolution tank equipped with a stirrer. To 100 parts by weight of the evaporation residue, 50 parts by weight of methanol as an organic solvent was added, and mixed by stirring at room temperature and normal pressure for 1.0 hour to dissolve sufficiently.
Solid-liquid separation was performed at rpm. As a solid product, 26 parts by weight of a powdery product which was smooth after centrifugation was obtained. As a result of analysis, this solid product was found to contain about 90% by weight of sodium formate, and also contained a small amount of sodium carbonate and sodium bicarbonate.

The filtrate was recovered in an amount of 102 parts by weight except for handling loss. This filtrate was once stored in a recovery liquid tank, and then separated into methanol and ethylene glycol by a distillation operation. The distillation was performed under reduced pressure at 300 torr at 42 ° C., and 43 parts by weight of methanol was recovered from the top of the column, sent again to the dissolution tank, and used for dissolution. Ethylene glycols were obtained from the lower part of the column, and 3.4 parts by weight of ethylene glycol, 14.2 parts by weight of diethylene glycol, and 7.6 parts by weight of triethylene glycol were recovered by another distillation operation.
Further, an evaporation residue containing 16.6 parts by weight of a solid was obtained from the reboiler, sent to a dissolving tank again, subjected to a dissolving operation, and collected as a solid.

The evaporation residue of the ethylene glycol waste liquid, which had to be discarded or incinerated by the above operation, was separated into a solid and a liquid, and could be effectively used except for the loss.

Example 2-5 The same procedure as in Example 1 was carried out using an organic solvent as shown in Table 1 to obtain the results shown in Table 1.

[0023]

[Table 1]

[0024]

According to the present invention, a specific organic solvent is added to the evaporation residue of ethylene glycol waste liquid, which has been conventionally incinerated or discarded as industrial waste, to separate it into a solid and a liquid, and to distill the liquid portion to obtain ethylene glycol. Diethylene glycol and the like could be easily recovered. The solid part can be effectively used as an aqueous solution for neutralizing general wastewater. Since this solid product contains sodium formate as a main component, it does not cause eutrophication of waste water unlike neutralization with ammonia water generally used for waste water treatment. As described above, useful substances can be separated and used from the evaporation residue of the ethylene glycol waste liquid that has been discarded as waste, and its industrial merit is great.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing one embodiment of the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distillation tower of ethylene glycol waste liquid 2 Dissolution tank 3 Filtration machine 4 Solid matter 5 Recovery liquid tank 6 Distillation tower 7 Ethylene glycols 8 Organic solvent tank 9 Reboiler

Continuation of the front page (72) Inventor Sugaku Tsuguo 312-5 Takayama, Onahama, Iwaki-shi, Fukushima Prefecture Onahama Distilling Co., Ltd. (56) References JP-A-57-169437 (JP, A) JP-A-53-25504 (JP) , A) JP-A-50-35105 (JP, A) JP-B-44-28882 (JP, B1)

Claims (3)

(57) [Claims] An organic solvent such as an alcohol, an ether or a ketone is added to an evaporation residue of ethylene glycol waste liquid in a weight ratio of 0.2 to 1.0 with respect to the evaporation residue, and the mixture is stirred. A method for recovering ethylene glycol, wherein the mixture is subjected to solid-liquid separation, and the filtrate is distilled to separate an organic solvent and ethylene glycol. 2. An organic solvent such as alcohols, ethers or ketones is added to the evaporation residue of the ethylene glycol waste liquid in a weight ratio of 0.2 to 1.0 with respect to the evaporation residue 1 and the mixture is stirred and obtained. A method in which a mixture is subjected to solid-liquid separation to recover a solid product composed mainly of sodium formate. 3. A method of using the solid obtained in claim 2 as an alkali source for neutralizing waste water.