US2857325A

US2857325A - Reboiler

Info

Publication number: US2857325A
Application number: US447634A
Authority: US
Inventors: Patrick F Dougherty
Original assignee: Sun Oil Co
Current assignee: Sunoco Inc
Priority date: 1954-08-03
Filing date: 1954-08-03
Publication date: 1958-10-21
Anticipated expiration: 1975-10-21

Description

P. F. D OUGHERTY REBOILER Filed Aug. 5, 1954 INVENTOR. 1 PATRICK F. DOUGHERTY BY I " E-Kira nited States Patent 2,857,325 REBOILER Chester Heights, Pa., assiguor to Philadelphia, Pa., a corporation of Patrick F. Dougherty, Sun Oil Company, New Jersey This invention relates to heat exchange apparatus, and more particularly to heat exchange apparatus in which one fluid is at least partially vaporized.

Reboilers used in the petroleum industry represent one form of equipment to which the improvement of this invention is particularly adapted. As presently developed, one form of accepted reboiler provides a heat exchange section and a surge section. In the heat exchange portion the liquid to be vaporized is in close contact with the heating means, usually tubes, through which hotter fluids flow. The depth of the vaporizing liquid is maintained between weirs bounding this section. In operation, the liquid to be vaporized spills over the weir into the surge section where the vapors accumulate and from which they pass to additional equipment for further processing.

It is the present practice to immediately conduct the vapors from the surge section to the next processing step. A conduit connected to the outer shell of the heat exchanger, above the surge section, accumulates and conducts the vapors therefrom. There results, because of temperature change and unrestricted release of the heated vapors, a contrary flow of condensed and entrained material which greatly reduces the efiectiveness of the device.

The principal object of the present invention is therefore to provide an improved means for removing the vapor products from a reboiler and the resulting presentation to the next process step of a better prepared and controlled petroleum fraction.

Incidental to this principal object are the additional objects of providing better temperature control in effecting the vaporizing step, more efiicient separation of the vaporized and non-vaporized constituents of the heat receiving liquid, and more eflicient utilization of the space in which such reboilers are required to be nested between and adjacent other apparatus.

With the above and other objects in view, all of which will be fully disclosed in the course of the following description, the invention consists in combining the dual sectioned reboiler with an improved entrainment breaker to improve the quality and condition of the extracted vapor. By dimensioning and positioning a vapor withdrawing conduit within the reboiler shell and relative to the heat exchange and surge chambers, improved operation is secured.

The accompanying drawing is a longitudinal sectional view through such a dual chambered reboiler illustrating a practical example of the invention.

Referring more specifically to the figure of the drawing, the reboiler shell or casing 10, divided into the heat exchange section or chamber 12 and the surge chamber 14 by the weir 16, is provided with a tubular heater 18 in chamber 12. Inlet 20 and outlet 22 conduct the heating medium to and from heater 18 to heat the liquid 24. The liquid inlet 26 admits the liquid 24 to be vaporized to heating contact with tubular heater 18 where it reaches the depth of the weir 16, spills over and empties out of outlet 28. The agitation of spilling over the weir and. the heat transfer causes the desired vapors to release and rise in the surge chamber to the entrainment breaker 30,

2,857,325 Patented Oct. 21, 1958 A baffle section 32 forms the entrance of the entrainment breaker 30. This may be conventional baffles or vanes intended to change the direction of the entering vapors and present accumulating surfaces for entrained droplets, or it may be a commercially available element known to the art as demisters serving the same purpose. In either case the purpose is to remove the heavier liquid particles from the vaporized material in the vicinity of the surge chamber 14.

The entrainment breaker 30 is extended in the shell contrary to the direction of movement of the liquid 24 from which the vapors are desired. It passes through the surge chamber, over the weir and enters the heat exchange portion to exit there from the shell, as shown.

By thus positioning and dimensioning the entrainment breaker 30 an additional path of temperature controlled travel is available to the vapors freed of entrained liquid before it passes through the outlet 34 to the next step in the process. The temperature of the breaker 30 is higher throughout its length than the liquid supporting portion of the surge chamber because of elevation in the shell, and differs in temperature in its length because the outlet is in the heat exchange zone while the inlet is in the relatively cooler surge chamber.

The improved operation of the device will be evident at this point. After leaving the heat exchange contact with tubular heater 18, vaporizing liquid 24 spills over the weir 16 into the surge chamber 14, which is relatively cooler. Vapors released here because of absorbed heat and agitation move upward in the shell 10 to the inlet of entrainment breaker 30, shown as baffled section 32. The conduit forming the breaker 30 is of consistently higher temperature than the vapors it receives and is progressively warmer throughout its length from inlet 32 to outlet 34 because of position relative to heater 18. This initial and progressively higher temperature condition maintains the received vapors in the vapor stage and conditions them for transfer through the outlet 34.

What is claimed is:

In a reboiler for use in refining petroleum in which a casing is divided into heat exchange and surge sections by a transverse weir, said weir being of suflicient depth to provide a body of liquid petroleum in the heat exchange section, and inlet and outlet conduits for the heat exchange and surge sections respectively, the improvement for collecting vapors in the surge section and conducting them from the reboiler in better condition for further refining operations comprising a conduit arranged longitudinally within the casing having an inlet end above the surge section and an outlet end passing through the reboiler casing above the heat exchange section, said conduit being suspended in said casing to fully expose the complete periphery over the length thereof to the internal temperature of the reboiler, and baffle means positioned only at said inlet end of the conduit above the surge section to immediately intercept entrained liquid particles and return them to the surge section.

References Cited in the file of this patent UNITED STATES PATENTS 1,407,380 Chenard Feb. 21, 1922 1,646,449 DYarmett Oct. 25, 1927 2,032,546 McNeil et al Mar. 3, 1936 2,106,583 Webb Ian. 25, 1938 2,139,985 Tali Dec. 13, 1938 2,320,366 Leaf June 1, 1943 2,665,565 Parks Ian. 12, 1954 OTHER REFERENCES Kern: Process Heat Transfer, first edition (1950), pp. 471, 472.