JP4143210B2 - Reboiler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reboiler provided integrally at the bottom of a distillation column.
[0002]
[Prior art]
In a distillation column for precision distillation, a reboiler integrated with a distillation column is generally employed in which a liquid reservoir in which condensate stays is provided at the bottom, and heating means for heating and condensing the condensate is provided here.
[0003]
[Problems to be solved by the invention]
However, in order to increase the reboiler's evaporation capacity in response to an increase in the size of the distillation column, etc., it is necessary to increase the heat transfer area in order to secure the necessary heat transfer amount. It was supported by increasing it. However, as the capacity of the liquid reservoir increases, the amount of condensate stay (hold-up) also increases, which increases the startup time. This is a serious problem in a precision distillation column that originally takes a long time to start up. In addition, boiling bubbles with a large diameter may be generated as the amount of evaporation increases, and this is a factor that causes severe pressure fluctuations and makes the operation state of the distillation column unstable, and is desirably avoided.
[0004]
The present invention has been devised to solve such problems of the prior art, and its main purpose is to expand the heat transfer area without increasing the condensate retention. Another object of the present invention is to provide a reboiler configured to suppress generation of bubbles having a large diameter and to ensure a stable operation state.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, in the present invention, in the reboiler integrally provided at the bottom of the distillation column, a liquid reservoir for retaining the condensate from the distillation column is directly connected to the distillation column; A plurality of heat transfer pipes hanging from the upper tank, a lower tank that collects the plurality of heat transfer pipes, and a downcomer (downcomer pipe) that circulates the condensate by connecting the upper and lower tanks. The condensate inside is heated by an external heat medium, and the heat medium is sealed in a heat medium tank provided in the liquid reservoir so that the liquid level is positioned below the liquid reservoir. The condensate in the liquid reservoir is heated by the condensation latent heat of the steam generated by the heating of the heater provided in the tank, and the steam of the heat medium and the condensate in the liquid reservoir are placed on the outer periphery of the downcomer. Of the heat medium generated by heat exchange of Condensed liquid is provided heat medium liquid retaining part for retention.
[0006]
According to this, the heat transfer area can be increased with respect to the condensate retention amount, and the required evaporation capacity can be realized with a small-capacity liquid reservoir, thereby shortening the startup time. Can do. 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 a relatively small pressure pulsation occurs, and they act to cancel each other out. The problem of making the operation state of the vehicle unstable can be solved.
[0007]
In the liquid reservoir having the above-described configuration, the condensate flows upward in the heat transfer tube by the action of the thermosiphon and the condensate flows downward in the downcomer to form a circulating flow. The principle is the same as that of a heat exchanger, and the downcomer is formed in a large diameter and the heat transfer tube is formed in a small diameter, so that the heat transfer area per cross-sectional area of the downcomer is made smaller than that of the heat transfer tube. As a result, a downward flow is formed in the downcomer, and on the other hand, in the heat transfer tube, the film thickness of the inner surface is reduced, and good heat transfer performance is obtained. In order to make the flow rate of the heat transfer tubes uniform, it is desirable to place the downcomer at the center.
[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 positioned below the liquid reservoir, and steam generated by heating of a heater provided in the heat medium tank. Since the condensate in the liquid reservoir is heated by the latent heat of condensation, it is not necessary to supply the heat medium from the outside, and the apparatus configuration can be simplified and the size can be reduced. And since it is indirect heating by a heat-medium vapor | steam, the effect of leveling can be acquired with respect to the fluctuation | variation of the emitted-heat amount of a heater, and the stability of driving | operation can be improved. In this case, a heat medium having a boiling point at the operating temperature may be employed, and a simple example thereof is the same substance as the distillation object.
[0009]
Further, the outer circumference of the downcomer, due to the provision of the heat medium liquid retaining part for condensate from staying in the heat medium generated by the heat exchange with the condensate in the reservoir the liquid and vapor of said heat medium, the downcomer The heat transfer medium condensate on the outer periphery acts as a heat insulation layer that reduces the heat that enters the downcomer, and suppresses the upward flow that occurs near the inner wall of the downcomer due to the intrusion heat. Thus, the upward flow in the heat transfer tube can be stabilized, the effect of reducing the film thickness in the heat transfer tube can be increased, and the heat transfer performance can be improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0011]
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 of room temperature or lower, and condenses the reboiler 1 according to the present invention, a plurality of distillation columns 2 filled with a filler, and a gas rising from the distillation column 2. The capacitor 3 is accommodated in the heat insulating container 4. The reboiler 1, the distillation column 2, and the condenser 3 are supported by the heat insulating container 4 through a support member (not shown).
[0012]
In the reboiler 1, a reservoir 6 of the condensate A flowing down from the distillation column 2 is integrally provided at the bottom of the distillation column 2. A heat medium tank 7 in which a heat medium is enclosed is provided below the liquid reservoir 6, and in this heat medium tank 7, the liquid surface of the heat medium liquid B is located below the liquid reservoir 6. A heater 9 is provided in the heat medium tank 7, and the heat medium liquid B is heated by the heater 9, and the condensate A in the liquid reservoir 6 is heated by the condensation latent heat of the generated steam. Yes. A heating medium whose boiling point is the operating temperature is employed.
[0013]
In the condenser 3, a condenser tube 10 provided at the upper end of each distillation column 2 is immersed in the refrigerant liquid in the condenser container 11, and condensable gas rising from the distillation column 2 is condensed. The condensate produced in the condensing tube 10 flows naturally down to the distillation column 2. The product to be distilled is fed into the middle stage of the distillation column 2, and the low boiling point components are extracted from the top of the condenser tube 10 and the high boiling point components are extracted from the liquid reservoir 6 of the reboiler 1.
[0014]
As shown in detail in FIG. 2, the liquid reservoir 6 of the reboiler 1 collects an upper tank 13 directly connected to the distillation column 2, a plurality of heat transfer tubes 14 suspended from the upper tank 13, and the plurality of heat transfer tubes 14. And a downcomer 16 that connects the upper and lower tanks 13 and 15 to each other and circulates the condensate. The downcomer 16 is formed to have a larger diameter than the heat transfer tube 14 and is disposed at the center thereof. On the outer periphery of the downcomer 16, a cylindrical trap 17 is provided as a heat medium liquid retaining portion for retaining the condensate of the heat medium. The upper part of the trap 17 is open.
[0015]
In the reboiler 1 configured 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 generated on the wall surfaces of the heat transfer tube 14 and the lower tank 15. Condensation latent heat is released to heat the condensate A inside. As a result, as indicated by an arrow in FIG. 2, the condensate A circulates upward in the heat transfer tube 14 by the action of the thermosiphon, and the condensate A circulates downward in the downcomer 16 to form a circulation flow. The 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 sealed heat medium tank 7. And condensation.
[0016]
Further, on the wall surface of the downcomer 16, the heat medium vapor entering from the upper opening condenses, and the heat medium condensate stays so as to surround the downcomer 16 in a cylindrical shape and functions as a heat insulating cylinder for the downcomer 16. The heat input into the downcomer 16 is reduced to suppress the upward flow generated in the vicinity of the inner wall surface.
[0017]
As described above, the example of the indirect heating method using the latent heat of condensation of the heat medium vapor has been described. However, as shown in FIG. 3, a method of directly heating with the 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 maintained at a predetermined temperature.
[0018]
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 tower, but other than this, such as a plate type. It can be widely applied to a distillation column of the type.
[0019]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the amount of condensate staying and shorten the required startup time, and to suppress the generation of bubbles having a large diameter and to ensure a stable operation state. In particular, by employing an indirect heating method that utilizes the latent heat of condensation of the heat transfer medium vapor, it is possible to simplify the device configuration and reduce the size, and to improve operational stability. Further, by forming a heat insulating cylinder made of the heat medium condensate on the outer periphery of the downcomer, the circulation 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 cross-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 cross-sectional view of the reboiler shown in FIG.
3 is a cross-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 Condensation pipe 11 Capacitor container 13 Upper tank 14 Heat transfer pipe 15 Lower tank 16 Downcomer 17 Trap 21 Reboiler 22 Heat medium tank 23 Supply pipe 24 Exhaust Tube A Condensate B Heat transfer fluid

Claims (1)

A reboiler provided integrally at the bottom of the distillation tower,
A liquid reservoir for retaining the condensate from the distillation tower is an upper tank connected to the distillation tower, a plurality of heat transfer tubes suspended from the upper tank, a lower tank for collecting the plurality of heat transfer tubes, It consists of a downcomer that connects the upper and lower tanks to circulate the condensate, and heats the condensate in the reservoir by an external heat medium ,
The heat medium is sealed in a heat medium tank attached to the liquid reservoir so that the liquid level is positioned below the liquid reservoir, and the latent heat of condensation of steam generated by heating of a heater provided in the heat medium tank To heat the condensate in the reservoir,
A reboiler characterized in that a heat medium liquid retention portion in which the condensate of the heat medium generated by heat exchange between the heat medium vapor and the condensate in the liquid reservoir is provided on the outer periphery of the downcomer. .

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