US 3085626 A
Description (OCR text may contain errors)
April 16, 1963 E. BOGNAR ET AL 3,035,626
HEAT TRANSFER APPARATUS Filed March 20, 1956 ZB r /8 /3 1 & =4
, /5 T INVENTORS. 12m 5W BY W Mm 7mm 5mm J ATTORN Y5 United States Patent 3,085,626 HEAT TRANSFER APPARATUS Etienne Bognar and Michel Antoine Maistre, Paris, France, assignors to Compagnie de Saint-Gobain, Paris,
France Filed Mar. 20, 1956, Ser. No. 572,714 Claims priority, application France Mar. 21, 1955 1 Claim. (Cl. 16511) This invention relates to heat exchange apparatus for transferring heat energy from one fluid to another and more particularly for making efficient, practical use of heat energy, such as that released by exothermic reactions at high temperatures.
It is known that calories or heat energy released by certain exothermic reactions may be utilized to vaporize substances, such as mercury, having high boiling points thereby storing the heat energy in the vapor. The latter may then be employed as a source of heat in a heat exchanger wherein the vapor is condensed and the heat energy converted to a useful purpose such as the heating of water to produce steam under pressure. In practice difficulties have been encountered in constructing suitable heat exchange apparatus in which the high temperature condensable vapor and the water to be converted to steam are in contact with opposite surfaces of the same wall. In such constructions, the walls are subject to deformation by reasons of differences in term peratures, difienences in the vapor tensions of the two fluids and the like, thus causing ruptures and creating leaks which permit penetration of one fluid into the circuit of the other, a condition which cannot be tolerated. Heretofore, efforts have been made to avod this latter difliculty by providing bulky apparatus which are expensive to build and require considerable space for installation. In some prior known equipment an inert intermediate fluid has been employed as the caloric vehicle between the heated vapor and the fluid to be heated, but the operation of such equipment has been found to be inefficient because of unavoidable heat losses entailed in the multiple exchange-s necessary and hence expensive to operate.
Accordingly, it is one of the objects of the present invention to provide a novel apparatus whereby the toregoing difiiculties and disadvantages of prior known devices are overcome.
Another object of the invention is to provide a novel recuperative boiler or heat exchange apparatus whereby the vapors of a liquid under pressure, such as water, is efiected directly by utilizing the heat of condensation of a fluid at high temperature and under comparatively low pressure. p
A further object is to provide novel heat exchange apparatus of the above type'which is capable of functioning with high efiiciency.
Still another object is to provide a heat exchanger which is novelly so constructed as to effectively eliminate the danger .of any mixing of the heat releasing and heat absorbing fluids in the event of a rupture in the apparatus and to facilitate inspection servicing and repair.
A still further object is to provide a simply constructed heat exchange apparatus wherein the transfer of heat takes place by both convection and radiation, principally the latter in an elficient manner.
The above and further objects and novel features of the present invention will more fully appear from the following detail description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawngs are for the purpose of illustration only and are not intended as a definition of the limits of the invention.
The single FIGURE of the drawing is a schematic, vertical sectional view illustrating the construction of one form of heat exchange apparatus embodying the invention.
The single embodiment of the invention illustrated in the drawing, by way of example, comprises two principal separable sections, the upper section B being herein referred to as the boiler section, and the lower section C being called the condenser section. In the form shown, boiler section B, which contains Water and steam or other fluid to be heated, comprises a casing 1 having a perforated bottom plate 7, a removable cover 3 for a manhole, and the customary accessories such as a pressure gauge 5 and a water level indicator 4. Water is fed into section B through a conduit 20* under control of a suitable valve 21 and steam is released through a conduit 2 under control of a suitable valve 22.
Secured within each of the perforations in plate 7 in a gas-tight manner and extending downwardly therefrom is a tube 6. Each such tube is closed at its lower end and opens into casing 1 at its upper end. Within each tube is a downflow pipe or conduit 23 which is preferably centrally disposed in said tube and terminates short of the bottom or closed end of the latter. Pipes 23 may be sup ported by plate 7 or tubes 6 in any suitable known manner such as by one or more spiders (not shown) and the same preferably extend above plate 7 into the boiler chamber. When the device is operating, the heated Water in the 'outer annular passage of each tube system 6, 23 rises and cooler water descends through central conduit 26 to replace it as indicated by arrows.
The condenser'section C, in the form illustrated, comprises a cylindrical casing member 8 having an upper p ate 9 and a lower plate 10, said plates having aligned perforations. Sections B and C are spaced apart by 'a ring 12 and may be sepa ablyv secured together by any suitable known means such as clamps, bolts or the like (not shown). The space within casing 8 is divided or partitioned by a plurality of tubes or cylinders 11, one of the latter surrounding each of the double wall water pipes 6, 23. The ends of cylinders 11 fit into the perforations or openings in plates 9 and 10 and are securely fastened to said plates in a gas tight manner.
" annular chamber or space 16 which is in communication through openings 17 with the annular spaces 18 in cylinders 11' around tube 6 and, hence, with the space between plates 7 and 9. The conduit 15 serves both as an inlet for high temperature vapors to the space 14 surrounding cylindrical partitions 11 and as an outlet for the condensate from such vapors.
It will thus be seen that the annular spaces 18 between walls 11 and tubes 6 are interconnected at their upper ends by the space between plates 7 and 9, and are interconnected at their lower ends by conical annular chamber 16. To facilitate the transfer of heat energy from walls 11 to the walls of tubes 6, the adjacent surfaces thereof, i.e., the surfaces within space :18 are delustered or coated with a suitable agent or treated in any other known manner so as to render the heat radiation factor thereof as high as possible. As will hereinafter more fully appear, the exchange of heat between walls 11 and 6 is effected by convection currents of a gaseous medium, such as air, enclosed in the intermediate spaces 18 and by radiation. The transmission by radiation can be of particular importance in view of the comparatively high temperatures which may be involved. The quantity of heat transmitted by the radiation is, in fact, proportional to the diflerence between the 4th powers of the absolute temperatures of the walls 11 and 6.
In the event of any internal leakage of steam, water or other fluid from the boiler section or of the mercury, vapor or similar fluid from the condenser section, such leakage will take place into the intermediate space 18 and will accumulate in chamber 16 from .which the same may be drained through a valve 19. The pressure within space 16, 18 may also be carefully regulated through valve 19 or in any other desired manner. In the event of any serious rupture which results in any considerable leakage from one of the fluid circuits into space 16, 18, the same may be readily located and repaired by separating the boiler and the condenser sections at ring 12.
In the operation of the above described apparatus, a vapor at high temperature, such as mercury vapor, is created in any suitable known type of device by the utilization of heat energy from any suitable source, such as the heat generated by an exothermic reaction, and is conducted through a pipe 15 into condenser chamber 14 around cylinders 11. The boiler section including tubes 6, 23 is filled to a suitable level with Water or with other fluid to be heated. Upon contact with cylindrical walls 11, the mercury vapor condenses and the condensate drains out through pipe 15. The heat energy released by the condensation of the vapor is transmitted chiefly by radiation from walls 11 through space 18 to the walls of tubes 6 and, thence, to the water or other fluid therein. To a lesser degree some of such heat energy is transferred by convection in the currents of the gaseous medium, which may be air, in the spaces 18.
In some successful apparatus built and operated in accordance with the invention herein described, it has been possible to recuperate substantially all of the heat energy from mercury vapor at an absolute pressure of 3.5 kg. and a temperature of 430 C., with an average input of about 10,000 kg. of mercury per hour. Using a heat exchanging surface of 90 square meters 1000 kg. of steam have been generated under a pressure of 12 kg. Under the same conditions, .but with an exchange surface of 96 square meters, 950 kg. of steam have been generated at a pressure of 20 kg. With the same input of mercury at 8 kg. absolute pressure and a temperature of 500 C. the energy of the heat of condensation has been substantially fully recovered in a boiler constructed in accordance with the invention and having a heat exchange surface of 56 square meters and generating 1000 kg. of steam at a pressure of 12 kg.
There is thus provided a practical and elficient heat exchange apparatus adapted for use in converting the heat of condensation of the vapors of liquids having comparatively high vaporization temperatures. Additionally, said apparatus is of simplified construction and small size in comparison with prior apparatus of comparable capacity and yet, even more reliable in operation. The apparatus of the invention is also comparably inexpensive to manufacture, install and operate.
Although only a single embodiment of the invention is illustrated in the accompanying drawing and described in detail in the foregoing specification, it is to be specifically understood that the invention is not limited thereto, but that various changes may be made in the details of construction and in the design and arrangement of the parts illustrated without departing from the spirit and scope of the invention.
What is claimed is:
A boiler, adapted to be partially filled with a liquid to be vaporized, heated by the condensation heat of a substance such as mercury vaporized in recuperating the heat released by exothermic reaction, said boiler including an inlet below and an outlet above the liquid level in a closed upper boiler section comprising a casing having a bottom wall, a plurality of parallel tubes sealed to and projecting vertically downwardly from said bottom wall and communicating with the interior of said casing, the lower ends of said tubes being closed, and a pipe extending into each of said tubes from said casing and terminating short of the closed lower end of the tube, the closed space within the boiler section being made up of the space within the casing and the spaces within the tubes communicating therewith, and a closed lower condenser section having an upper wall, said tubes of the boiler section extending through openings in the said upper wall of the condenser into the interior thereof, partition means extending a substantial distance within said condenser casing, said partition means having their upper ends sealed to said upper wall and creating in the condenser chamber a vapor chamber and annular gas containing spaces around said tubes sealed from said vapor chamber and from the interior of said tubes and from the interior of the tubes of the boiler section, means removably securing the lower wall of the boiler and the upper wall of the condenser together in confronting relationship, the condenser section having a common header space adjacent the bottom thereof connecting the lower ends of said annular spaces, and means selectively to open the bottom of the header space and to close said header space, whereby to detect and drain any leakage of fluid from either the boiler section or the condenser section into any of said annular spaces.
References Cited in the file of this patent UNITED STATES PATENTS 710,608 Prat Oct. 7, 1902 1,419,337 Werner June 13, 1922 1,628,736 Oliver May 17, 1927 1,761,035 Govers June 3, 1930 2,225,634 Houdry Dec. 24, 1940 2,658,728 Evans Nov. 10, 1953 2,669,435 Cord et al. Feb. 16, 1954 FOREIGN PATENTS 588,214 Great Britain May 16, 1947