JP2005145841A - Installation, and method for producing diphenyl carbonate or aromatic polycarbonate by using the installation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an installation for distilling phenol or diphenyl carbonate, in whose piping the pool of a liquid and the solidification of the liquid are little caused. <P>SOLUTION: This installation for distilling the phenol or diphenyl carbonate is characterized in that the piping of the installation has such an inclination that the installation side for applying a pressure to the piping is lowered, and the total height of the rising portions of the piping is ≤1 m. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for distilling phenol and / or diphenyl carbonate.

In general, a method for producing an aromatic polycarbonate (PC) using diphenyl carbonate (DPC) and bisphenol A (BPA) is as follows.
First, diphenyl carbonate (DPC) is produced by subjecting carbonyl chloride and phenol (PL) to a gas-liquid reaction in the presence of a catalyst. Impurities such as phenol (PL) are removed from the solution obtained by neutralization washing in a distillation step, and purified diphenyl carbonate (DPC) is recovered.

  Next, bisphenol A (BPA) is dissolved in the above-mentioned diphenyl carbonate (DPC), a catalyst is added, and the mixture is heated and stirred under vacuum and reduced pressure to cause transesterification and distill out the by-produced phenol (PL). Polymerization proceeds while aromatic polycarbonate (PC) is produced.

  By the way, in these processes, there is an apparatus for distilling phenol (PL) and diphenyl carbonate (DPC). For example, in the process of producing diphenyl carbonate (DPC), diphenyl carbonate (DPC) is distilled and purified while refluxing, and in the process of producing aromatic polycarbonate (PC), phenol (PL) is converted to diphenyl carbonate (DPC). ) And distilled off. These distillation operations are performed under reduced pressure by providing a vacuum facility in order to lower the distillation temperature (see Patent Document 1).

JP 9-38402 A

  However, distillation under reduced pressure inevitably causes distillation components such as phenol (PL) and diphenyl carbonate (DPC) to be pulled by the vacuum equipment, resulting in a liquid pool in the middle of the pipe connected to the vacuum equipment. In some cases, the accumulated distillate component hardens, making it impossible to maintain the vacuum state. Moreover, when distilling components such as distilled phenol (PL) and diphenyl carbonate (DPC) are refluxed by a pump, the distilling components may be clogged due to solidification in the refluxing pipe.

  Therefore, an object of the present invention is to make it difficult to cause liquid accumulation and solidification in a pipe in an apparatus in which phenol (PL) or diphenyl carbonate (DPC) is distilled.

  The present invention relates to an apparatus for distilling phenol (PL) and / or diphenyl carbonate (DPC), wherein the piping has an inclination in which the equipment side that applies pressure to the fluid in the piping faces downward, and rises. The above problem has been solved by a device having a total height of the portions of 1 m or less.

  Distillate shifts to the vacuum facility by gravity by providing an inclination in the vacuum piping that connects the condenser that condenses the distillate composed of phenol (PL) and diphenyl carbonate (DPC) to the vacuum facility. And staying in the piping can be reduced. In addition, by adding a slope to the horizontal part of the reflux pipe for refluxing phenol (PL) and diphenyl carbonate (DPC) to the distillation column, the accumulated distillate can easily fall along the slope, making it difficult to stay in the pipe. It is possible to prevent the distillate from deteriorating while the operation of the entire apparatus is stopped.

  In addition, by making the total of the height of the part where the vertical direction rises opposite to the inclination of the pipe with such an inclination to be 1 m or less, the liquid and solids accumulated in the rising part are minimized, It can be avoided that the pipe is completely blocked or the pressure loss becomes too large.

Hereinafter, the present invention will be described in detail.
The apparatus according to the present invention is an apparatus for distilling phenol (PL) and / or diphenyl carbonate (DPC). As this apparatus, as shown in FIG. 1, a distillation column 1, a condenser 2 for condensing the substance to be distilled, a vacuum facility 12 for reducing the pressure in the system, and a vacuum connecting the condenser 2 and the vacuum facility 12. An apparatus having the pipe 11 is exemplified. Hereinafter, this apparatus is referred to as “distillation apparatus”.

  Moreover, when a reflux part is formed in the distillation apparatus, the distillation tower 1, the condenser 2 for condensing the substance to be distilled, the condensate tank 25, the liquid feed pump 22, and the liquid feed are formed. The reflux pipe 21 that connects the pump 22 and the distillation column 1 can also be handled as an apparatus according to the present invention. Hereinafter, this reflux portion is referred to as a “reflux device”.

  First, the distillation apparatus will be described using FIG. 1 as an example of diphenyl carbonate (DPC) distillation. In the distillation apparatus, a distillate obtained by distilling diphenyl carbonate (DPC) produced by phenol (PL) and carbonyl chloride is distilled from the distillation column 1 and condensed in the condenser 2. This diphenyl carbonate (DPC) contains phenol (PL).

  The vacuum facility 12 is a facility for sucking and discharging the gas to bring the distillation column 1 into a reduced pressure state. An example of such a vacuum facility 12 is a vacuum pump.

  The vacuum pipe 11 connected to the vacuum facility 12 has a downward slope from the condenser 2 side toward the vacuum facility 12 side. It is desirable that the above inclination extends over as long a section as possible in the horizontal portion of the vacuum pipe 11. Further, the above inclination may be greater than 0 ° downward from the horizontal direction and 90 ° or less, but when traveling 2 m in the horizontal direction toward the vacuum facility, it is desirable to proceed downward by 1 cm or more, It is more desirable if it goes down from 5 cm to 1 m. Further, it is more desirable that the inclined horizontal portion does not have a completely horizontal portion and a rising portion, and more desirably, the inclination is constant from end to end of the vacuum pipe 11. The horizontal portion refers to a horizontal state and a portion that is slightly inclined from the horizontal state. The completely horizontal portion is a portion perpendicular to the vertical direction.

  The slope may have the completely horizontal part or the rising part on the way, but the total height of the rising part is preferably 1 m or less, more preferably 10 cm or less, Most preferably, there is no part. If the total height of the rising portions exceeds 1 m, the pressure loss generated when the distillate accumulates in the rising portions becomes too large, and there is a possibility that the vacuum suction cannot be performed. Here, the above-described rising portion refers to a portion having an inclination upward from the condenser 2 toward the vacuum facility 12, contrary to the above-described inclination. Here, the distillate is likely to be stored as a liquid or a solid. If the distillate is stored, pressure loss is caused. If the distillate is excessively stored, the tube itself may be blocked. Therefore, it is more desirable if the above-mentioned inclination is only downward from the condenser 2 side toward the vacuum equipment 12 side.

  The condenser 2 condenses phenol (PL), diphenyl carbonate (DPC), and the like. The condensed distillate is withdrawn out of the system or sent to the condensate tank 25 of the reflux device for reflux to the distillation column 1.

  The pressure in the distillation column 1 is desirably 1 to 200 Torr, and more desirably 5 to 100 Torr. At that time, the vacuum-depressurized pressure in the vacuum pipe 11 for drawing the gas in the distillation column 1 is preferably close to or lower than the pressure in the distillation column 1, and more preferably 1 to 100 Torr.

  Furthermore, it is desirable that the piping structure from the top of the distillation column 1 to the condenser 2 satisfies the following conditions. The inner diameter of the pipe is desirably in a range where the actual gas linear velocity is 0.01 to 20 m / sec. The length of the pipe from the top of the distillation column 1 to the condenser 2 should be as short as possible, preferably 10 m or less, and most preferably 0 m. Furthermore, the smaller the number of bent portions of the piping, the better. From these conditions, it is most desirable that the condenser 2 is provided at the top of the distillation column 1 as a top condenser. When these conditions are satisfied, the vacuum reduced pressure state of the distillation column 1 by the vacuum equipment 12 is further stabilized.

  The distilled phenol (PL) or diphenyl carbonate (DPC) gas is desirably supplied so as to flow from the top to the bottom of the condenser 2. Moreover, it is desirable that the inside of the condenser 2 and the outlet portion have a large diameter so that the gas linear velocity is reduced. If the gas linear velocity is high, it may cause pressure loss, and the vacuum depressurization of the distillation column 1 may not be maintained.

  It is desirable that a mist catcher 15 for capturing mist is provided between the condenser 2 and the vacuum pipe 11. This is to prevent mist-like phenol (PL) and diphenyl carbonate (DPC) from being mixed into the vacuum pipe 11 and collecting or solidifying as much as possible.

  It is desirable that the vacuum pipe 11 has a facility or a method for heating and keeping the inside higher than the melting point of the distillate. As the equipment or method, for example, a method of making the vacuum pipe into a double pipe structure or a trace structure by steam or electricity can be mentioned. In addition, when the said distillate consists of a some component, it is desirable that it is more than melting | fusing point of the substance with the highest melting | fusing point in them. Moreover, although the inside of the said vacuum piping is a pressure reduction state, melting | fusing point is melting | fusing point in a pressure reduction state here. If the inside of the vacuum pipe 11 is equal to or higher than the melting point of the distillate, phenol (PL) or diphenyl carbonate (DPC) mixed in the vacuum pipe 11 without being fully condensed in the condenser 2 is liquid or gas without solidifying. Therefore, the possibility of clogging the inside of the vacuum pipe 11 can be further reduced. For this reason, it is desirable in terms of operation of the process that the melting point of diphenyl carbonate (DPC) is 80 ° C. or higher and is equal to or lower than the temperature at the top of the distillation column 1.

  Further, it is desirable that the vacuum pipe 11 is provided with at least one drainage port 14 toward the lower side. This is because the distillate that has been liquefied or dewed in the vacuum pipe 11 needs to be extracted without remaining in the vacuum pipe 11. It is desirable that at least one of the liquid discharge ports 14 is close to a portion connected to the vacuum equipment 12 of the vacuum pipe 11. This is because, since the vacuum pipe 11 has an inclination, the distillate may accumulate before the vacuum pipe 11 is extracted from a position as close as possible to the bottom of the inclination. Such extraction of the liquid may be performed while the entire apparatus is stopped, not during vacuum decompression by the vacuum facility 12. Furthermore, when the length of the vacuum pipe 11 exceeds 3 m, it is more desirable that the liquid drain port 14 is provided in the middle of the vacuum pipe 11 because it is easy to avoid liquid accumulation.

  Furthermore, it is desirable that the vacuum pipe 11 is provided with a supply port 13 capable of supplying a heating fluid on the condenser 2 side. The position where the supply port 13 is provided is preferably closer to the condenser 2, but when the mist catcher 15 exists between the vacuum pipe 11 and the condenser 2, the mist catcher 15 and the condenser 2 It is desirable that it is as close as possible to the place where the vacuum pipe 11 is connected to the mist catcher 15 rather than between them. By providing this supply port 13, the heating fluid can be poured from here and extracted from the liquid discharge port 14, and the vacuum pipe 11 can be washed. Therefore, it is desirable that the space between the supply port 13 and the liquid discharge port 14 occupy as long an area as possible in the vacuum pipe 11. Moreover, since there is an inclination, it is more efficient to supply from the one with higher potential energy. For this reason, it is desirable that the supply port 13 is open facing the upper side of the vacuum pipe 11.

  The heating fluid is a fluid that is fluid at the temperature in the vacuum pipe 11 and may be liquid or gas. Examples of the heating fluid include water vapor, phenol (PL), nitrogen, and the like, and water vapor or phenol (PL) vapor is more preferable. Use of phenol (PL) vapor is more desirable because it can be dissolved when diphenyl carbonate (DPC) is solidified inside the vacuum pipe 11. Only one of these or a plurality of mixtures may be used. However, it is desirable that the heating fluid does not react with the material of the vacuum pipe 11 or diphenyl carbonate (DPC) or the like under the temperature and pressure conditions in the vacuum pipe 11 and does not react at all. More desirable.

  Further, it is desirable that the vacuum pipe 11 is provided with valves 16 and 17 in a portion connected to the condenser 2, the vacuum equipment 12, the mist catcher 15, and the like. When cleaning with the heating fluid, if the valve is blocked by the valve, the heating fluid can be prevented from leaking out of the vacuum pipe 11.

  Furthermore, it is desirable that the vacuum pipe 11 is provided with a freeze capacitor. It is more desirable that two or more freeze capacitors are installed in parallel and can be switched. If the freeze condenser is installed, the distillate component that could not be captured by the condenser 2 can be forcibly solidified and collected, and the subsequent vacuum piping 11 can block or increase pressure loss. It can be suppressed and desirable.

  When distilling off low-boiling compounds such as phenol (PL) from diphenyl carbonate (DPC), two or more condensers 2 are connected in series to liquefy the evaporated gas flowing out from the distillation column 1. It is also effective to do. At that time, it is preferable that the temperature of each condenser 2 is gradually lowered as the temperature of each condenser 2 increases from the distillation column 1. In particular, the first condenser 2 is adjusted to 80 to 150 ° C. in order to actively condense high-boiling components such as diphenyl carbonate (DPC), and the liquefied condensate is circulated to the distillation column 1. Next, the uncondensed gas that has not been liquefied in the first condenser 2 is adjusted to 0 to 80 ° C. in the second and subsequent condensers 2 and is almost completely liquefied. A part of the liquefied condensate is refluxed to the distillation column 1 as necessary, and the remaining or the entire amount is distilled. If two or more condensers 2 are installed in this way, even if a large amount of diphenyl carbonate (DPC) is distilled from the distillation column 1, the operation can be continued without solidifying and blocking in the condenser 2, and stable for a long time. And can be distilled. Since the freezing point of diphenyl carbonate (DPC) is 80 ° C. and higher than the freezing point of phenol (PL) (40 ° C.), under the temperature condition of the condenser 2 for condensing only low boiling point compounds such as ordinary phenol (PL) If a large amount of diphenyl carbonate (DPC) is present, the diphenyl carbonate (DPC) may solidify in the condenser 2. Therefore, if two or more condensers 2 are installed and the high melting point diphenyl carbonate (DPC) is forcibly condensed and removed, then the non-condensed gas is condensed to prevent solidification. Can be stabilized. In addition to phenol (PL), as a light boiling component to be distilled off, it is more desirable to use this multi-stage condenser 2 when more low-boiling compounds than phenol (PL) are contained.

  Next, the above reflux apparatus will be described with reference to FIG. 1 and an example of reflux of diphenyl carbonate (DPC). In this example of the reflux apparatus, a distillate such as phenol (PL) or diphenyl carbonate (DPC) produced from phenol (PL) distilled from the distillation column 1 is condensed in the condenser 2 and condensed once. The liquid is stored in the liquid tank 25 and is refluxed to the upper portion of the distillation column 1 by the liquid feed pump 22 to increase the efficiency of the distillation separation while suppressing the evaporation of the high boiling point components.

  The horizontal portion of the reflux pipe 21 for refluxing the distillate to the distillation column 1 by the liquid feed pump 22 needs to have a downward slope from the distillation tower 1 side to the liquid feed pump 22 side. It is. It is preferable that there is no complete horizontal part or rising part in the middle of the horizontal part having this inclination, and it is more desirable if the inclination is constant. At this time, the inclination is preferably 1 cm or more and downward when traveling 2 m horizontally toward the liquid feed pump 22, and more preferably 5 cm to 1 m downward. If there is a completely horizontal part or a rising part, it is necessary that the height difference due to the inclination is larger than the total height difference of the rising part, and the total height of the rising part is 1 m or less It is desirable that it is 10 cm or less. In addition, here, said rising part means the part which inclines upward from the distillation tower 1 side toward the liquid feed pump 22 side contrary to said inclination.

  Further, although depending on the position of the liquid feed pump 22, as shown in FIG. 1, a vertical or nearly vertical gradient is provided between the horizontal portion of the reflux pipe 21 having the above-described inclination and the liquid feed pump 22. There may be parts. At this time, in order to extract the liquid accumulated before and after the liquid feed pump 22, liquid drain ports 23 and 24 may be provided in the pipes near the suction port and the discharge port of the liquid feed pump 22.

  It is desirable that the above-mentioned reflux pipe 21 has a facility for heating and keeping the temperature above the melting point of the distillate. In addition, when said distillate consists of a some component, it is desirable that it can heat and hold | maintain above the melting | fusing point of the substance with the highest melting | fusing point among them. If the reflux pipe is at or above the melting point of the distillate, the distillate remains liquid or gas without solidifying, so the possibility of clogging inside can be further reduced. Examples of the equipment for heating and heat insulation include those having a double tube structure, a steam or electricity trace structure.

  It is desirable that a supply port 27 is provided at a location near the distillation column 1 of the reflux pipe 21. When the operation of the entire apparatus is stopped, the reflux pipe 21 can be cleaned by flowing the heating fluid from the supply port 27 and extracting it from the liquid discharge port 24. At that time, it is desirable that a valve 26 is provided between the reflux pipe 21 and the distillation column 1 so that the heating fluid does not flow into the distillation column 1.

  In addition, the distillation apparatus for distilling phenol (PL) and diphenyl carbonate (DPC) as described above recovers purified diphenyl carbonate (DPC) by removing impurities such as phenol (PL) from diphenyl carbonate (DPC). In addition to the distillation process, the PC production process of polymerizing aromatic polycarbonate (PC) while recovering phenol (PL) by-produced by reacting diphenyl carbonate (DPC) and bisphenol A (BPA) under vacuum and reduced pressure And can be used to recover phenol (PL) or diphenyl carbonate (DPC). Furthermore, any process that distills phenol (PL) or diphenyl carbonate (DPC) can be used.

  In addition, the reflux apparatus for refluxing phenol (PL) and diphenyl carbonate (DPC) as described above returns phenol (PL) and diphenyl carbonate (DPC) distilled from the exemplified distillation column 1 to the distillation column 1. In addition to the process of suppressing the evaporation of high-boiling components contained in the supplied phenol (PL) and diphenyl carbonate (DPC) and increasing the distillation separation efficiency, it can be used as long as the process also requires reflux. is there. The high boiling point component is separately extracted from the lower part of the distillation column 1.

  Moreover, when these apparatuses are used for the production of diphenyl carbonate (DPC), there is a take-out port 28 for taking diphenyl carbonate (DPC) out of the system at a position other than the horizontal portion having the above-mentioned inclination in the reflux pipe 21. Good.

  Diphenyl carbonate (DPC) purified by such a process is used as a raw material for producing aromatic polycarbonate (PC) together with bisphenol A (BPA).

  Further, in these processes, by using each of the above-described devices, even when the inside of the pipe is blocked by the cleaning method of supplying the heated fluid from the supply ports 13 and 27 provided in the respective devices, the blockage is easily released. I can do it.

Arrangement example of apparatus according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Distillation tower 2 Condenser 11 Vacuum piping 12 Vacuum equipment 13 Supply port 14 Liquid discharge port 15 Mist catcher 16, 17 Valve 21 Reflux piping 22 Liquid feed pump 23, 24 Liquid discharge port 25 Condensate tank 26 Valve 27 Supply port 28 mouth

Claims (11)

In the apparatus for distilling phenol and / or diphenyl carbonate, the apparatus comprises a condenser for condensing the substance to be distilled, a vacuum facility for reducing the pressure in the system, and a vacuum pipe connecting the condenser and the vacuum facility. Have
The vacuum pipe has a downward slope from the condenser side to the vacuum equipment side, and the total height of the portions rising upward from the condenser side to the vacuum equipment side is A device that is 1 m or less.   The apparatus according to claim 1, wherein the vacuum pipe has a facility for heating and keeping the inside of the distillate from the distillation column above the melting point.   The apparatus according to claim 1 or 2, wherein at least one liquid discharge port is provided on the vacuum facility side of the vacuum pipe.   The apparatus in any one of Claims 1 thru | or 3 which provided the supply port which can supply a heating fluid in the said condenser side of the said vacuum piping.   An apparatus cleaning method, wherein the vacuum pipe is cleaned by supplying the heating fluid from the supply port provided in the apparatus according to claim 4.   The method for cleaning an apparatus according to claim 5, wherein the heating fluid contains at least one of water vapor, phenol, and nitrogen. In the apparatus for distilling phenol and / or diphenyl carbonate, the apparatus includes at least a distillation column, a condenser for condensing the substance to be distilled, a condensate tank, a liquid feed pump, and a condensate obtained from the condenser. It has a reflux pipe for circulating a part from the liquid feed pump to the distillation tower,
The horizontal portion of the reflux pipe has an upward slope from the liquid feed pump side to the distillation tower side.   The apparatus according to claim 7, wherein the reflux pipe has a facility for heating and keeping the temperature inside the condensate above the melting point.   The apparatus according to claim 7 or 8, wherein a liquid drain port is provided in a pipe near the suction port and / or the discharge port of the liquid feed pump.   The manufacturing method of diphenyl carbonate using the apparatus in any one of Claims 1 thru | or 4 or 7 thru | or 9.   The manufacturing method of an aromatic polycarbonate using the apparatus in any one of Claims 1 thru | or 4 or 7 thru | or 9.

Images