JPH1190361A - Removal of deposit of irregular packing material in distillation column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove foreign matter adhered to irregular packing materials without imparting a change in the packing materials by rotating the irregular packing materials together with water while bringing the packing materials in contact with the water in a mixer of a rotary type. SOLUTION: The inside of the distillation column which is packed with the irregular packing material (pole rings) of one inch and the operation of which is made no longer possible as a result of an increase in the difference pressure in the column by continuous operation for four months is washed by water washing and steaming and, thereafter, the packing materials of 100L adhered with the brown dried foreign matter are withdrawn and are charged together with 150L water into a concrete mixer. When the packing materials are rotationally washed for 10 minutes at 100 revolutions/minute and are further washed with the water, the foreign matter of the packing materials is approximately completely removed. While the concrete mixer includes a non-inclining type mixer (drum mixer) and a tiltable mixer, both are usable. In the case the packing materials adhered with the polymers and the foreign matter are washed with the water in the concrete mixer, the ratio of the apparent volume of the packing materials to the volume of the mixer is usually 0.1 to 0.5 times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing extraneous matter from a distillation column irregular packing. More specifically, the present invention relates to a method for removing deposits of irregular packing used in a distillation column used in a production process of 1,4-butanediol using butadiene as a raw material. ADVANTAGE OF THE INVENTION According to this invention, the foreign material adhering to the irregular packing used in the distillation column can be easily removed, and the packing can be reused effectively.

[0002]

2. Description of the Related Art Distillation is used in many chemical plants because simple equipment can be used to obtain high-purity products. A tray type is used in a large distillation column, and a packing is generally used in a relatively small distillation column. However, recently, packing or dispersing equipment has been improved, and packing towers capable of obtaining a large amount of processing even with the same column diameter have been reviewed. The problem with the packed tower is that when handling a polymerizable substance or the like, polymerization or adhesion of foreign substances may occur in the packed material, and operation may not be possible. In such a case, it is necessary to replace the packing, which increases the cost. Therefore, it is difficult to employ a packed tower in a distillation column handling a polymerizable substance. The method of removing foreign substances such as polymers adhered to the packing of the distillation column is important in practical use,
Little or no effective means has hitherto been known, and only a slightly known method of removing foreign substances by calcining a soiled filler is known.

[0003]

However, when the metal filler is calcined, the crystal structure changes, the strength decreases due to oxidation, the corrosion resistance decreases, or the substance changes during distillation. For example, there is a high possibility of causing coloring, decomposition, and the like. Therefore, the filler to which the foreign matter has adhered is often discarded as it is. An object of the present invention is to provide a method for easily removing foreign substances adhering to an irregular packing used in a distillation column without changing the material.

[0004]

The present inventors have studied the use of a distillation column packed with a polymerizable substance to advantageously produce 1,4-butanediol by the butadiene method.
Easily remove deposits by rotating the polymer or metal irregular packing with foreign substances in contact with water in a rotary mixer, for example, a mixer such as a concrete mixer. They found what they could do and completed the present invention.

[0005] That is, the gist of the present invention is a method for removing adhering substances of an irregular packing in a distillation column, which comprises contacting the irregular packing used in the distillation column with water in a rotary mixer. is there. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Butadiene is oxidized with oxyacetic acid in acetic acid in the presence of a catalyst supporting palladium and tellurium on a carrier to obtain diacetoxybutene, and hydrogen reduction, hydrolysis,
Methods for producing 1,4-butanediol and tetrahydrofuran (THF) by cyclization are known (for example,
JP-A Nos. 50-4011, 51-29426 and 5
Nos. 2-7909 and 52-65208). The acetoxylation reaction step of reacting butadiene with oxygen and acetic acid to produce diacetoxybutene is performed at 50-100 ° C. under pressure (usually 4-10 MPa) using acetic acid as a solvent.
The reaction is carried out at a temperature of The reaction solution contains 70-9 acetic acid.
After separating unreacted oxygen and butadiene, which contain 0%, acetic acid and products are separated. Separation of acetic acid and product is accomplished by distillation under reduced pressure. The separated acetic acid is sent to the acetic acid recovery step, is distilled together with the water acetic acid supplied from the hydrolysis step and the THF conversion step, and is separated and recovered into water and acetic acid.

[0007] The product mainly composed of diacetoxybutene is separated into high-boiling substances by distillation and then sent to a hydrogenation step to convert unsaturated compounds such as diacetoxybutene into saturated compounds such as diacetoxybutane. Change. The product after hydrogenation is sent to the hydrolysis step, where it is hydrolyzed at 40 to 60 ° C. using a strongly acidic ion exchange resin as a catalyst. Since hydrolysis is an equilibrium reaction, it is carried out in a countercurrent multistage hydrolysis. It is efficient to implement. The hydrolysis reaction solution was placed under reduced pressure (0.07
To 0.01 MPa) to distill water and acetic acid from the top of the column to obtain a product from the bottom. The product is 1,4-diacetoxybutane unreacted with 1,4-butanediol, 1
-Hydroxy-4-acetoxybutane, and the mixture was subjected to reduced pressure (0.02-0.005MP
a), 1,4-diacetoxybutane unreacted with the product 1,4-butanediol, 1-hydroxy-4-
Acetoxybutane and small amounts of high boilers are separated.

The unreacted product containing a small amount of 1,4-butanediol is circulated to a hydrolysis process to form butanediol, or supplied to a THF process to be used as a raw material for synthesizing THF. In the THF conversion step, hydroxyacetoxybutane, which is a hydrolysis product of diacetoxybutane, and 1,4-butanediol are used as raw materials, and strongly acidic ion exchange resin is used as a catalyst to produce THF by deacetic cyclization or dehydration cyclization. Then, after being separated from unreacted substances in the unreacted substance separation tower, THF is separated from acetic acid and water in the THF separation tower. The separated acetic acid and water are sent to an acetic acid recovery step. T
Since the unreacted product in the HF conversion step contains a high-boiling substance such as acetate ester of dibutylene glycol, the high-boiling substance is separated and then supplied to the hydrolysis step to recover 1,4-butanediol. Since high-boiling substances separated by acetoxylation, hydrolysis and THF formation contain acetic ester, acetic acid is recovered by hydrolysis. This method is disclosed in
As disclosed in JP-A-321846, 100 to 5000 ppm of a mineral acid is used as a catalyst for a high boiling substance,
Perform the hydrolysis reaction at ~ 150 ° C. The hydrolysis reaction is
Water and acetic acid are distilled off by distillation, and the distillate is supplied to an acetic acid recovery step to recover acetic acid.

The distillation of a reaction solution obtained by hydrolyzing a high-boiling substance contains a large amount of an unsaturated compound having an unknown structure. Therefore, distillation by a tray column is usually employed. Using a tower. The packing is preferably an irregular packing, and a metal Raschig ring, pole ring, mini ring, bell saddle, metal interlock saddle, or the like is suitably used. Distillation was performed under reduced pressure (0.07 to 0.01 M
Pa), the reaction is carried out at a bottom temperature of 180 ° C. or lower, preferably 150 ° C. or lower. If the temperature is too high, the adhesion of the polymer becomes noticeable in the packing or at the lower part of the distillation column including the reboiler, and the operation cannot be performed. However, even if the operation is performed at a temperature of 150 ° C. or less, accumulation of the deposits on the packing cannot be prevented, and the replacement of the packing is required in the operation for 3 to 6 months. This deposit is made of a common solvent such as TH
Since it does not dissolve in F, acetic acid or the like, it is difficult to wash it in the distillation column. After steaming and washing with water, this packing is taken out of the distillation tower, and rotated with water in a concrete mixer. Was not recognized, and it could be refilled as it was.

[0010] Distillation using the recovered packing could be operated without any abnormality in separation or the like. The rotary mixer used in the present invention is a mixer in which the container itself rotates, and specific examples thereof include a concrete mixer. Concrete mixers include an inclining mixer (drum mixer) and a tilting mixer, and both can be used. Also, in a concrete mixer,
In the case where the polymer or the foreign matter is washed with water, the ratio of the apparent volume of the filler to the volume of the mixer is usually 0.1 to 0.5 times, preferably 0.2 to 0.4 times. ,
The number of rotations of the mixer is usually 20 to 100 rpm
m, preferably 30 to 50 rpm, the amount of water used is usually 1 to 1 hour per hour based on the apparent volume of the packing.
20 times, preferably 5 to 10 times, the processing temperature is usually 1
The temperature is 0 to 60 ° C, preferably 30 to 40 ° C.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention.

Example 1 A method for cleaning a distillation column packing in a process for producing butanediol and tetrahydrofuran from butadiene and acetic acid raw materials shown in FIG. 1 will be described. In a reactor 1 filled with a palladium-supported catalyst, butadiene 1.6 t / hr, air 11
100 Nm ³ / hr, acetic acid 30 t / hr, 9MP
a, Reaction was carried out at 100 ° C. After solid-liquid separation (not shown) of the reaction solution, acetic acid, water and other light-boiling components were distilled off in a distillation column 2 and diacetoxybutene was distilled off in a distillation column 3. The bottoms of the distillation column 3 are distilled by a thin film evaporator 4 which is operated at a temperature lower than the bottom pressure of the distillation column 3.
And high-boiling substances were extracted from the bottom of the column at 150 kg / hr. Next, the diacetoxybutene flowing out of the distillation column 3 was subjected to a hydrogenation reaction at a reaction pressure of 1 MPa and a temperature of 90 ° C. in a reactor 5 filled with a palladium catalyst under a hydrogen flow. Next, the reaction solution was distilled in the distillation column 6 to elute diacetoxybutane. The bottom product of the distillation column 6 is
Was distilled in a high-boiling matter separation column 7 operated at a temperature lower than the bottom pressure of the above, and the distillate was circulated to the distillation column 7 to extract high-boiling matter from the bottom of the column at 30 kg / hr. Next, the diacetoxybutane distilled from the distillation column 6 is converted into a strongly acidic ion exchange resin (SK).
Reactors 8, 10 packed with 1BH, manufactured by Mitsubishi Chemical Corporation
In the middle, two-stage hydrolysis was performed at 50 ° C. to obtain a reaction mixture containing butanediol, hydroxyacetoxybutane, and diacetoxybutane as main components. The hydrolysis solution is
Acetic acid, water and other light-boiling substances were distilled off in the distillation column 9 or 11. The bottom product of the distillation column 11 was supplied to the distillation column 12, and a low-boiling component was discharged from the top of the column, diacetoxybutane and hydroxyacetoxybutane were discharged from the upper stream, and butanediol was discharged from the middle stream. Then, butanediol was rectified in the distillation column 13 and recovered as a product stream of butanediol. The bottom liquid of the distillation columns 12 and 13 is
High boiling substance separation column 1 operated at a temperature lower than the bottom pressure of column 13
The distillate was circulated to the distillation column 12 and high boiling substances were extracted from the bottom of the column at 50 kg / hr. In addition, distillation column 1
The upper side stream of No. 2 is a strongly acidic ion exchange resin (SK1BH,
Into a reactor 15 filled with Mitsubishi Chemical Corporation).
After the acetic acid cyclization at 80 ° C., the reaction solution was sent to a distillation column 16 to distill off tetrahydrofuran. Was recovered. As described above, 230 kg / hr of a waste oil mixture composed of high-boiling substances collected from each of the steps of acetoxylation of butadiene, hydrogenation of diacetoxybutene, hydrolysis of diacetoxybutane, and deacetic acid cyclization was used. %: Value analyzed by gas chromatography for the alkaline hydrolyzate), 150 kg / hr of water and 0.1% of 60% by weight nitric acid.
The solution preliminarily mixed with 5 kg / hr was supplied to a hydrolysis reactor 17 made of SUS-304. Hydrolysis reactor 17
Is conducted at a temperature of 92 ° C., and the reaction solution is distilled in a distillation column 18 operated at a top pressure of 0.013 MPa and a bottom temperature of 148 ° C., and contains water, acetic acid, and other light boilers from the top. An effluent of 180 kg / hr was distilled off, and 200 kg / hr of a high-boiling substance was discharged from the bottom of the column. The distillation column 18 is a distillation column filled with 1 inch of irregular packing (pole ring), but the continuous operation for four months caused the pressure difference in the column to increase, so that the operation became impossible. After the inside of the distillation column was washed with water and washed by steaming, the packing was extracted. Brown dry foreign matter adhered to the packing. 100 L of the packing material to which the foreign matter was attached was charged into a concrete mixer together with 150 L of water, and was washed by rotating at 100 rpm for 10 minutes. After the washing, the contents were taken out and further washed with water. As a result, foreign matters in the filler were almost completely removed. The washed packing was charged into the distillation column 18 again, and distillation was restarted. However, the pressure difference in the column was restored, and the operation could be performed smoothly.

[0013]

According to the present invention, it is possible to easily clean and reuse an irregularly-packed material having foreign substances adhered thereto, which has been difficult to reuse in the past. And can be operated economically.

[Brief description of the drawings]

FIG. 1 is a flow sheet of Example 1.

[Explanation of symbols]

1,5,8,10,15 Reactor in each process 2,3,6,9,11,12,13,16,18 Distillation column 4 Thin film evaporator 7,14 High boiling matter separation column 17 Hydrolysis reactor

Claims (3)

[Claims] 1. A method for removing adhering substances on an irregular packing of a distillation column, wherein the irregular packing used in the distillation column is brought into contact with water in a rotary mixer. 2. The method according to claim 1, wherein the random packing is made of metal. 3. The method according to claim 1, wherein the random packing is used in a distillation column used in a process for producing 1,4-butanediol using butadiene as a raw material.