JP2000271402A - Reboiler - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the amount of condensate retained and reduce the time required for starting up a reboiler integrated with a distillation column, and to suppress the generation of large-diameter bubbles to secure a stable operation state. It is configured to obtain. SOLUTION: A liquid reservoir 6 for retaining a condensate from a distillation column 2 is composed of an upper tank 13 connected to the distillation column, a plurality of heat transfer tubes 14 hanging down from the upper tank, and the plurality of heat transfer tubes. And a downcomer 16 which connects the upper and lower tanks and circulates the condensate. Then, the heat medium is sealed in a heat medium tank 7 attached to the liquid reservoir so that the liquid level is located below the liquid reservoir, and the heat medium vapor generated by heating of the heater 9 provided therein is filled in the liquid reservoir. Shall be heated. Further, on the outer periphery of the downcomer, there is provided a trap 17 in which the condensate of the heat medium generated by heat exchange between the vapor of the heat medium and the condensate in the liquid reservoir is retained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reboiler integrally provided at the bottom of a distillation column.

[0002]

2. Description of the Related Art In general, a distillation tower for precision distillation is provided with a liquid reservoir in which a condensate stays at a lowermost portion thereof, and a reboiler integrated with a distillation tower provided with heating means for heating and evaporating the condensate. Has been adopted.

[0003]

However, when it is desired to increase the evaporation capacity of the reboiler in accordance with the enlargement of the distillation column, it is necessary to increase the heat transfer area in order to secure a necessary heat transfer amount. Conventionally, this has been dealt with by increasing the capacity of the liquid reservoir. However, as the capacity of the liquid reservoir increases, the amount of condensate stagnation (hold-up) also increases, thereby increasing the time required for startup. This is a serious problem in a distillation column for precision distillation which originally requires a long time to start up. In addition, a boiling bubble having a large diameter may be generated with an increase in the amount of evaporation, but this causes a drastic pressure fluctuation, which is a factor of destabilizing the operation state of the distillation column, and is desirably avoided.

[0004] The present invention has been devised to solve such problems of the prior art, and its main objects are as follows.
To provide a reboiler configured to be able to increase the heat transfer area without increasing the amount of condensate retained and to suppress the generation of large-diameter bubbles to ensure a stable operation state. is there.

[0005]

In order to achieve the above object, according to the present invention, in a reboiler integrally provided at the bottom of a distillation column, a liquid reservoir for retaining condensate from the distillation column is provided with a distillation tank. An upper tank directly connected to the tower, a plurality of heat transfer tubes hanging down from the upper tank, a lower tank for collecting the plurality of heat transfer tubes, and a downcomer (down) for connecting the upper and lower tanks to circulate the condensate. Tube), and the condensate in the reservoir is heated by an external heat medium.

According to this, it is possible to increase the heat transfer area with respect to the amount of condensate retained, and it is possible to realize the required evaporation capacity with a small-capacity liquid reservoir. Can be shortened. In addition, by providing a large number of heat transfer tubes and reducing the diameter of the heat transfer tubes, even when a slag flow is formed, only relatively small pressure pulsations are generated, and they act so as to cancel each other. Can be eliminated.

In the liquid reservoir having the above-described structure, the condensed liquid flows upward in the heat transfer tube and the condensed liquid flows downward in the downcomer by the action of the thermosiphon to form a circulating flow. The principle is the same as that of the calandria heat exchanger. The downcomer is formed to have a large diameter and the heat transfer tube is formed to have a small diameter so that the heat transfer area per cross-sectional area of the downcomer is smaller than that of the heat transfer tube. This creates a downward flow in the downcomer, while in the heat transfer tube,
The boundary film thickness on the inner surface is reduced, and good heat transfer performance is obtained. Further, it is desirable to arrange the downcomer at the center in order to make the flow rate of the heat transfer tube uniform.

[0008] In particular, the heat medium is sealed in a heat medium tank provided adjacent to the liquid reservoir so that the liquid level is located below the liquid reservoir, and is generated by heating of a heater provided in the heat medium tank. Preferably, the condensed liquid in the liquid reservoir is heated by the latent heat of condensation of the vapor. According to this, it is not necessary to supply the heat medium from the outside, so that the device configuration can be simplified and the size can be reduced. Moreover, since the heating is performed indirectly by the heating medium vapor, the leveling effect can be obtained with respect to the variation in the calorific value of the heater, and the operation stability can be improved. In this case, a heat medium whose operating temperature becomes the boiling point may be employed, and a simple example thereof is the same substance as the distillation target.

Further, it is preferable that a heat medium liquid retaining portion for retaining the condensate of the heat medium generated by heat exchange between the vapor of the heat medium and the condensate in the liquid reservoir is provided on the outer periphery of the downcomer. . According to this, the heat medium condensate on the outer periphery of the downcomer acts as a heat insulating layer that reduces the heat entering the downcomer, and suppresses the upward flow generated near the inner wall surface of the downcomer due to the invading heat. It is possible to stabilize the downward flow in the comber, thereby stabilizing the upward flow in the heat transfer tube, increase the effect of reducing the film thickness in the heat transfer tube, and improve the heat transfer performance. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a precision distillation apparatus to which a reboiler according to the present invention is applied. This precision distillation apparatus performs a distillation operation under a temperature condition equal to or lower than ordinary temperature, and condenses a reboiler 1 according to the present invention, a plurality of distillation columns 2 filled with a filler, and gas rising from the distillation column 2. The condenser 3 is housed in a heat insulating container 4. Reboiler 1, distillation column 2 and condenser 3
Are supported by the heat insulating container 4 via a support member (not shown).

In the reboiler 1, a reservoir 6 of the condensate A flowing down from the distillation column 2 is provided integrally with the bottom of the distillation column 2. A heat medium tank 7 in which a heat medium is sealed is provided below the liquid reservoir 6.
In, the liquid surface of the heat medium liquid B is located below the liquid reservoir 6. The heating medium tank 7 is provided with a heater 9. The heating medium 9 is heated by the heater 9, and the condensed liquid A in the liquid reservoir 6 is heated by the latent heat of condensation of the vapor generated thereby. I have. A heat medium whose boiling point becomes the operating temperature is adopted as the heat medium.

In the condenser 3, a condensing tube 10 provided at the upper end of each distillation column 2 is immersed in a refrigerant liquid in a condenser vessel 11 to condense the condensable gas rising from the distillation column 2. The condensed liquid generated in the condensing tube 10 flows down to the distillation column 2 by natural flow. The material to be distilled is sent to the middle stage of the distillation column 2, and the low-boiling components are withdrawn from the top of the condenser tube 10 and the high-boiling components are withdrawn from the liquid reservoir 6 of the reboiler 1.

As shown in detail in FIG. 2, the liquid reservoir 6 of the reboiler 1 includes an upper tank 13 directly connected to the distillation column 2, a plurality of heat transfer tubes 14 hanging down from the upper tank 13, and a plurality of heat transfer tubes. The lower tank 15 which collects 14 and the upper and lower tanks 13.15
The downcomer 16 which communicates with each other to circulate the condensate
It consists of The downcomer 16 is formed to have a larger diameter than the heat transfer tube 14 and is arranged at the center thereof. On the outer periphery of the downcomer 16, a cylindrical trap 17 is provided as a heat medium liquid retaining section for retaining the condensed liquid of the heat medium. The upper part of the trap 17 is open.

In the reboiler 1 constructed as described above, the heat medium liquid B in the heat medium tank 7 is heated by the heater 9 as described above, and the heat medium vapor generated thereby is supplied to the heat transfer pipe 14 and the lower tank 15. The latent heat of condensation is released from the wall surface of the substrate to heat the internal condensate A. Thereby, as shown by an arrow in FIG. 2, the condensate A flows upward in the heat transfer tube 14 by the action of the thermosiphon, and the condensate A flows downward in the downcomer 16 to form a circulating flow. You. On the other hand, the heat medium condensate generated on the outer surface of the liquid reservoir 6 by heat exchange with the condensate A flows down and is heated again by the heater 9, and the heat medium evaporates in the closed heat medium tank 7. And condensation are repeated.

On the wall surface of the downcomer 16, the heat medium vapor entering from the upper opening is condensed, and the heat medium condensate stays so as to surround the downcomer 16 in a cylindrical shape, and the heat insulating cylinder of the downcomer 16 is formed. And reduces heat input into the downcomer 16 and suppresses upward flow generated near the inner wall surface.

The example of the indirect heating method using the latent heat of condensation of the heat medium vapor has been described above. As shown in FIG.
A method of directly heating with a heat medium liquid is also possible. In the reboiler 21, the heat medium tank 22 is filled with the heat medium liquid B, and a supply pipe 23 and a discharge pipe 24 for the heat medium liquid B are provided, and are maintained at a predetermined temperature.

In the above-described embodiment, a configuration in which a number of packed column type distillation columns are connected to a reboiler has been described as an example. However, the reboiler according to the present invention does not select the type of the distillation column, but uses a plate type. It can be widely applied to other types of distillation columns.

[0019]

As described above, according to the present invention, it is possible to reduce the amount of condensate retained and reduce the time required for startup, and to suppress the generation of large-diameter bubbles to ensure a stable operation state. it can. In particular, by adopting an indirect heating method using the latent heat of condensation of the heat medium vapor, the device configuration can be simplified and downsized, and the operation stability can be improved. Furthermore, by forming the heat insulating cylinder by the heat medium condensate on the outer periphery of the downcomer, the circulating flow in the liquid reservoir can be stabilized, and the heat transfer performance can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a distillation apparatus to which a reboiler according to the present invention is applied.

FIG. 2 is an enlarged sectional view of the reboiler shown in FIG.

FIG. 3 is a sectional view similar to FIG. 2, showing another embodiment of the reboiler according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reboiler 2 Distillation column 3 Condenser 4 Heat insulation container 6 Liquid reservoir 7 Heat medium tank 9 Heater 10 Condenser tube 11 Condenser container 13 Upper tank 14 Heat transfer tube 15 Lower tank 16 Downcomer 17 Trap 21 Reboiler 22 Heat medium tank 23 Supply pipe 24 Discharge Pipe A Condensate B Heat medium

Continued on the front page (72) Inventor Kenichi Haga 1-5-13 Hazawa, Nerima-ku, Tokyo (72) Inventor Shoji Tanaka 4-12-22, Okamura, Isogo-ku, Yokohama, Kanagawa Prefecture (72) Inventor Atsushi Uchiyama Tokyo (11) Inventor Tatsuharu Shimaoka 3-5-1 Kobuchi, Sagamihara-shi, Kanagawa F-term (reference) 4D076 AA22 AA24 BB04 BB05 BC06 CA14 CA19 DA02 DA10 DA22 DA36 FA31 FA37 JA03

Claims (3)

[Claims] 1. A reboiler integrally provided at the bottom of a distillation column, wherein a liquid reservoir for retaining a condensate from the distillation column is suspended from an upper tank connected to the distillation column and the upper tank. A plurality of heat transfer tubes, a lower tank that collects the plurality of heat transfer tubes, and a downcomer that connects the upper and lower tanks and circulates condensate, and condensate in the liquid reservoir is heated by an external heat medium. A reboiler characterized by heating. 2. The heating medium is sealed in a heating medium tank provided adjacent to the liquid reservoir so that a liquid level is positioned below the liquid reservoir, and is generated by heating of a heater provided in the heating medium tank. The reboiler according to claim 1, wherein the condensed liquid in the liquid reservoir is heated by the latent heat of condensation of the vapor. 3. A heat medium liquid retaining section in which a condensate of the heat medium generated by heat exchange between a vapor of the heat medium and a condensate in the liquid reservoir is provided on an outer periphery of the downcomer. The reboiler according to claim 2, wherein: