US2341281A

US2341281A - Method of and apparatus for condensing vapors

Info

Publication number: US2341281A
Application number: US364999A
Authority: US
Inventors: Frank J Mcgovern
Original assignee: Lummus Co
Current assignee: CB&I Technology Inc
Priority date: 1940-11-09
Filing date: 1940-11-09
Publication date: 1944-02-08
Anticipated expiration: 1961-02-08

Description

Feb. 8, 1944.

F. J. M GOVERN 2,341,281 METHOD OF AND APPARATUS FOR CONDENSING VAPORS Filed Nov. 9, 1940 INVENTOR 1 7 21% J 112-601??? ATTOR E asiiaai METHOD OF APPARATUS FER CONDENSING: VWQRS application November 9, 19a, sci-nine. states (or. zoa-im Claims.

, code requirements as to limited size openings and which has the particular advantage of simplicity without the possibility of leakage. In such construction, which has proved highly successful in operation, there isa fixed amount of condensing surface which is customarily de-' signed for operation with a particular type of crude or the like having a relatively constant percentage of overhead or low boiling material to be condensed by a predetermined amount of cooling water having a maximum. initial temperature. Difliculty in obtaining complete condensation is soon experienced, however, if the charge is changed or the water temperature rises, and the only cure for insufficient condensing surface is to slow down the unit.

The principal object of my invention is to provide a more flexible process and apparatus for condensing overhead vapors, particularly those from a petroleum distillation, in which the initial fixed condensing surface can be of the minimum required, and flexibility can be obtained by a supplemental condensing action.

Another object of my invention is to provide a condensing system for a vacuum distillation in which a fixed condensing surface is provided ,and is supplemented with a spray or direct contact cooling, which is preferablyaccomplished by appropriate pumping of subcooled condensate into the condensing zone.

A still further object of my invention is to provide for my improved condensing system an automatic thermally responsive control for the condensation of the vapors, in which the temperature ofthe resulting condensate is utilized to control the temperature or the amount of supplemental cooling action.

, Further objects and advantages of my invention will appear from the following description of a preferred form of embodiment thereof taken in connection with the attached drawing, in which Fig. 1 is a partial elevational view diagramalong the lin 2-4 of Fig. i;

matically showing the arrangement of the distilling column and associated parts; I,

Fig. 2 is a vertical section taken substantially Fig. 3 is a horizontal section taken substantially along the line 3-3 of Fig. l.

As described in my issued patent heretofore mentioned, the apparatus generally comprises a distilling column or bubble tower 6 having boiling cap decks I of any suitable form. For fractionation of the vapors, reflux is introduced on the top deck by a pipe 8. In the upper part=of the column the shell is provided with rectangular openings to receive the tubes of the condenser sections l0 and I2. The condenser section i9 is enclosed between vertical partitions Hi and the end plate 15, and the lower tube bundle I2 is enclosed between a short partition It on one side and an angle partition IT on the other side, the end' being closed by plate l6a. A space I B is provided between the sections for access to th tubes and this space is enclosed by removable cover plates 20.

Angles

22 and 25, extending across the column, serve as supports for the condenser sections during insertion or removal. The angle partition ll extends to a point considerably below the tube bundle i2 and has a horizontal pan l9 extending into the shell. The horizontal pan l9 and the partitions l4 and I! are preferably covered with an insulating material 25. t g

The condenser tubes of the section ID are connected with

headers

28 and 30, the former 'having connections 32 for circulating the cooling fluid. The tubes of the section 12 are similarly connected into

headers

34 and 36, of which the former has the cooling liquid connections 38.

The partition walls l4, l6, and I1, together with parts of the shell 8. form bifurcated

vapor conduits

39 and 39a around the condenser sections so that vapors of oil rising from above the boiling cap decks pass around the left side of the condenser sections, as indicated by the arrows in Fig. 1, into the vapor collecting chamber to at the top, and thence downwardly across the condensers; The uncondensable material then passes upwardly through the other bifurcated vapor space 39a at the right of the condensers, and finally through an outlet pipe ll. This path isdetermined by the wall 40 across the top of the right-hand vapor space 39a. The condensate drops on the partition l9, which serves as a collecting pan, and is withdrawn by a pipe 4! with the product removed at '2.

In the vertical space 30a leading to the outlet denser 45 and the vacuum jet equipment 46,

which are mounted on a bracket 48 extending from the shell and braced by an inclined strut 49.

In accordance with my present invention, which is an improvement over that described in my prior patent, I provide means to supplement the fixed condensing surface of the condenser sections Ill and I2. This is preferably accomplished by a recirculation of some of the condensate removed through the outlet 42 by the pump 53, which pumps it through the cooler 54. This cooler may be suitably water-jacketed as by the tank 55, hav ing the cooling inlet at 56 and the cooling outlet at 5'1, and the subcooled condensate is then passed through the pipe 58 to a spray head 50 mounted above the top of the upper condenser section Hi.

If, in operating the distilling column 6, it is found that the capacity of the condenser is insuflicient to adequately cool the overhead vapors, the condensate across the tubes in the condenser chamber will be in direct contact with the overhead vapors, which pass upwardly through the vapor space 39 and will cause complete condensation by cooling as well as by absorption.

It will, therefore, be possible to initially provide an overhead condenser with a minimum of fixed condensing surface, which is comparatively expensive, and provide for overload or supplemental loads or for the distillation of difierent crudes by the simple expedient of controlling the amount of cooled recirculated condensate. This may add as much as 20% excess capacity without materially extra cost and would still permit most efficient operation of the fixed capacity equipment under normal load conditions. The added cooling can be accomplished with the same source of cooling water, which would be inadequate to cool the vapors in the case of an overload operation. In such case, the condensate on pan l9 might be considerably higher in temperature than the initial cooling water, and subcooling would be accomplished in the tank 55. The spray of this condensate in the condensing chamber would immediately serve the purpose of additional cooling surface even though the cooling water would not be available for this purpose if passed through the condenser tubes.

The control of the amount of direct contact cooling can be readily accomplished by providing a thermally responsive control device 56in the condensate line and interconnecting such control with the power source '61 at-68. With an increase in condensate temperature, the pump 53 would be started or increased in speed to supply the necessary amount of condensate for subcooling.

It will be appreciated that a similar control can be effected by varying the amount of cooling water admitted at 56 in accordance with the temperature of the condensate at 66. In this way cooled condensate is controlled.

It will be apparent that supplemental cooling material may be introduced through the pipe 64 and that recirculation of the condensate may not always be desirable or essential although in many thetemperature instead of the volume of the sub cases it has the advantage of providing a similar quality of material and it does not materially increase the burden on the cooling apparatus.

operation supplemental cooling may be necessary.

It will also be apparent that the present apparatus has all the advantages of that shown in my prior patent inasmuch as it will always be convenient and possible to introduce a cleaning solution through the pipe 64 if tube cleaning is required during a shutdown of operations. In such case the cleaning material is readily withdrawn and there is no interference with the usual operations after the equipment is again placed in service.

Although I have shown my invention in combination with only one form of the apparatus described in my prior patent, it will be understood that I do not wish to be limited thereto. My invention is also applicable to a fractionation system in which the condensing section is independent of the distilling section.

While I have shown a preferred form of embodiment of my invention, I am aware that modifications may be made thereto, and I, therefore, desire a broad interpretation of my invention within the scope and spirit of the description herein and of the claims appended'hereinafter.

I claim:

1. The combination with a column having. a distilling section, of a condenser comprising a bundle of horizontal tubes of generally rectangular cross-section extending across the upper part of the column and having a fixed condensation area, fixed vertical partitions extending completely across the column alongside the tube bundle and forming vapor spaces between the tube bundle and the column wall whereby vapors from the distilling section are directed through one of the vapor spaces to the top of the condenser, a condensate pan below the condenser and connected with at least one of the partitions, headers for the tube bundle, means for removably supporting the tube bundle and headers independently of the partitions and condensate pan, means to remove condensate from said condensate pan, means to remove uncondensed vapors through the other vapor space, and means to reintroduce for supplemental cooling, a part of the condensate concurrently with the'vapors to the top of the condenser, said means including a cooling device in the condensate line to subcool the condensate, and a spray to distribute the condensate across the vapor inlet over the condenser tubes, and means to control the amount of spray by the temperature of the condensate removed from the condensate pan.

2. The method of fractionating a complex mixture, which comprises fractionating said mixture in the presence of a reflux liquid in a relatively high temperature fractionation zone to obtain overhead vapors, passing said vapors into a relatively low temperature condensation zone having a fixed condensation area, passing a cooling fluid in indirect heat exchange relation to said vapors direct heat exchange between the vapors and the recycled condensate, subcooling the condensate in the course of the recycling thereof, and controlling the amount of the condensate recycled in response to the temperature of the condensate after passage thereof through said heat exchange region. 1

3. The method of iractio'nating a complex mixture, which comprises iractionating said mixture in the presence of a reflux liquid in a relatively high temperature fractionation zone to obtain overhead vapors, passing said vapors into a relatively low temperature condensation zone having a fixed condensation area, passing a cooling fluid in indirect heat exchange relation to said vapors within the latter zone to condense at least a-part of said vapors, removing the uncondensed vapors from the condensation zone, separately removing condensate directly from the condensation zone, recycling a portion of the removed condensate to the condensation zone and discharging it in the immediate region of said indirect heat exchange to supplement the latter by,

direct heat exchange between the vapors and the recycled condensate, subcooling the condensate in the course of the recycling thereof, and controlling the amount or subcooling of the condensate recycled in. response to the temperature of the condensate after passage thereof through said heat exchange region.

4. In combination with a distillation columnhaving a distilling section therein, a tubular condenser having a plurality of tubes, means to pass a cooling fluid through the condenser tubes, said and condensation in the condenser, means for removing uncondensed vapors from said condenser, means for withdrawing condensate directly from said c0ndenser, means for recycling a portion of the withdrawn condensate to the condenser vapor inlet and including means for discharging the condensate upon the condenser tubes to supplement the condensing effect there of, means associated with said recycling means for subcooling the condensate in the course of the recycling thereof, and means responsive tothe temperature of the condensate after passage thereof over the condenser tubes to control the amount of the condensate recycled.

5. In combination with a distillation column having a distilling section therein, a tubular condenser having a plurality of tubes, means to pass a cooling fluid through the condenser tubes, said tubes having a fixed condensation area, means to passthe overhead vapors from the distilling section to said condenser for passage over said tubes and condensation in the condenser, means for removing uncondensed vapors from said condense, means for withdrawing condensate direct- 1y from said condenser, means for recycling a portion-of the withdrawn condensate to the contubes having a fixed condensation area, means to 35 pass the overhead vapors from the distilling section to said condenser for passage over said tubes denser vapor inlet and including means for discharging the condensate upon the condenser tubes to supplement the condensing effect thereof, means associated with said recycling means for subcooling the condensatein the course of the recycling thereof, and means responsive to the temperature of the condensate after passage thereof over the condenser tubes to control the amount of subcooling oi the recycled condensate.

FRANK J. MGGOVERN.