US1614159A - Air-cooling apparatus - Google Patents

Description

Jan. 11 1927. A. R. SMITH AIR 000mm APPARATUS Filed June 6. 1925 Inventor Arthur" R. SmLth W H La Attorngy Patented Jan. 11, 1927.

UNITED STATES PATENT OFFICE.

ARTHUR R. SMITH, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW, YORK.

AIR-COOLING APPARATUS.

Application filed June 6, 1925. Serial No. 35,400.

The present invention relates toair cooling apparatus, such as surface air coolers and air cooling sections of surface condensers, and more particularly it relates to the cooling tubes used in such apparatus, which, as is well understood, are usually mounted in groups or banks between common supporting headers or tube sheets, and which must be individually removable in case of leakage or other fault without disturbing other tubes in the bank.

The use of finned tubes in air cooling paratus of the type above mentioned has well recognized advantages, but has heretofore carried with it the disadvantage that in order to permit the removal of a faulty tube from a tube sheet carrying other tubes, removable thimbles or packing rings were required about the tube joint with one of the tube sheets to provide an opening thereat of suflicient diameter to pass the tube fins when the tube was withdrawn. This construction is objectionable because it introduces additional joints through which leakage may occur and materially increases the cost of construction and maintenance of apparatus in which it is used. For this reason it has heretofore been considered impractical touse finned tubes in the air cooling sections of surface condensers and in certain other types of coolers.

It is the object of the present inventionto be novel and the invention, attention is now directed to the accompanying drawing, the description thereof and the appended claims.

In the drawing, Fig. 1 is a side view, partly in section, of a finned air-cooling tube embodying the invention and applied to a double tube sheet mounting for a surfa e air cooler Fig. 2 is a similar View sl awing a modification applied to a single tube sheet mounting for a surface condenser, and-Fig. 3 is an end view, partly in'section and on a greatly reduced scale, .of a surface condenser provided with an air cooling section comprising a bank of tubes concurrent of air' to be cooled is circulated and through which a stream of cooling water flows from an inlet water box 6 to an outlet water box 7. ing to the usual practice between the water boxes with its ends expanded tightly into tube shees 8 and 9 which form end heads for said water boxes.

The tube is provided with suitable cool ing fins 10, which in the present example are formed by a spiral metallic ribbon, preferably of copper, tightly wound edgewise thereon and soldered in place. The ribbon is shouldered along its inner edge tobprovide good thermal contact with.the to e.

At one end, the tube is expanded or belled,

as indicated at 11, to increase its'external at the belled end as well as the plain unbelled end, thus providing a very simple con-' struction and eliminating in the tube sheet through which it is designed to be inserted and withdrawn, the additional joints ordi narily provided by a packing ring about the tube end, together with the additional complication andf possibilities of leakage which such packing ring introduces. This advantage for the belled tube becomes of great importance when the large number of tubes used in any one piece of cooling apparatus is considered.

It has been found that the belled tube can be made to the desired diameter without internal metal stresses and without any sign of destructive action on the metal fibres.

Thus the belled tube is as sound as the straight tube now used in surface condensers The tube is mounted accordtance.

and surface air coolers and makes it possible to use cooling fins in practically any place where a ain tube may be used and in many places where a finned tube has heretofore been cdnsidered impracticahbecause of the additional packings required for one end of each tube. I

An example of this is the double tube sheet construction used in surface air coolers where the prevention of cooling water leakage .-i nto the air spaces is of impor- Tube sheets 8 and 9 are of the double construction providing a leakage space or chamber 12 into which leakage about the tubeor tubes from the respective water boxes must pass before reaching'the inner' tube sheet. Leakage flow from the chamber 12 is easily detected and remedied before it becomes serious. The'faulty tube joint or joints are located by removing the water box at the end where leakage occurs and applying water pressure to the chamber 12 while observing the'tube ends. The tube or tubes about which leakage is indicated are then rerolled or expanded more tightly into the tube sheets.

Thus the double tube sheet provides a leakage chamber which separates the water boxes from direct leakage communication with the air spaces and facilitates testing for leaks.

It is therefore desirable to provide the double tube sheet in surface air coolers, but heretofore the use of finned tubes with the double tube sheet has not been considered to be practical because of the large number of additional joints introduced by the double sheets in conjunction with the removable packing rings required for the removal of the finned tubes. With the belled tube however, the use of finned tubeswith double tube sheets is made practically possible and opens up for new uses this desirable combination. Heretofore, with the use of finned tubes limited in practice tosingle tube sheets for thereason abovestated, it was very diflicult to locate a faulty tube joint in a surface air cooler because it is not desirable to fill the shell or air space thereof with water as it is in the case of a surface condenser. This generally necessitated repacking or rerolling all of the tubes in the event of one or a few tube leakages.

Referring nowto Fig. 2. 13 is a cooling tube like that of Fig. 1, provided with similar cooling fins 14 and mounted at its ends in single tube sheets 15 and 16 of'a surface condenser. To provide. for the greater expansion due to heating, the plain end of the tube in'tube sheet 16 .isnot expanded tightly into engagement therewith, but is provided with a packing therein comprising a ring 17 surrounding the tube end with a tight sliding fit and threaded into a counterbored ecess 18' in the tube sheet to compress packing materia1 19 contained in said recess tightly about the tube end. The latter extends into the recess through a central opening 20 at the rear thereof, which opening serves to center the tube end in the recess, The belled end of the tube'is expanded into engagement with tube sheet 15, while the plan end is thus permitted to move in the packing as the tube expands or contracts.

Midway between the tube ends a perforated supporting wall 21 is provided through which the tube passes. The wall forms a guide to prevent the tube fromdropping down, and becoming entangled with the fins of other tubes when being withdrawn or inserted and prevents the tube from sagging in use.

The single tube sheets shown are used in surface condensers because leakage is not as serious as in a surface air cooler, such as a surface air cooler for an electric generator for example, and a leak may be located without rerolling all of the tube ends, by

filling the shell or space surrounding theL tubes. with water and observing the tube. ends.

Referring to Fig. 3, 22 is the shell of a surface condenser provided with a top inlet 23, a vapor chamber 24 in which is located a bank of water tubes 25, and a hot well 26. Separated from the vapor chamber by a double sloping wall 27 is an air cooler section 28 through'which noncondensable vapors and air pass from the vapor chamber to a side outlet 30. The air cooler section is provided with a bank of uniformly spaced, finned water tubes 29. A gutter 31 is provided at the lower edge of the sloping wall, from which gutter one or more gutter pipes 32 lead downwardly toward the hot well. An opening 33 is provided in the lower end of each gutter pipe and a double wall 27 provided with a heat insulating space 34 serves to separate the vapor chamber and the air cooler section 28.

The water tubes 29 of the air cooling sections are constructed and mounted in accordance with the showing in Fig., 2, and because of the belled end construction, permit the use of cooling fins without complicating the tube mounting to the extent of rendering the use of finned tubes impractr. cal in a condenser air cooling section as has heretofore been the case with tubes of ordinary construction.

It. should be understood that the invention is not limited to the use of cooling tubes with spiral fins, such as that shown, but may be carried out in connection with other finned tube structuresin other types of air cooling apparatus.

\Vhat I claim as newand desire to secure .by Letters Patent of the United States, is:

1. A thin-walled tube having a main portion of uniform cross-section and an end portion of enlarged cross-section, and a spiral ribbon surrounding said main portion of the tube in contact therewith,said ribbon being secured to the tube to form anhaving a shouldered inner edge secured to the tube and forming an air cooling fin therefor of smaller overall size than the belled end.

3. In combination, a thin-walled tube having an enlarged belled end, said tube being of uniform cross-section throughout the remainder of its length, a spiral ribbon surrounding said tube, said ribbon being secured to the tube to form a thin air cooling fin-therefor of smaller overall size than the belled end of the tube, spaced walls in which the tube ends are secured, and an intermediate supporting wall forthe tube having a guide opening through which the tube passes, said guide opening and wall serving to reduce the sag of the tube between i-ts ends and to facilitate the removal of said tube through -one of said spaced Walls. 7

In witness whereof, I have hereunto set my hand this 5th day of June, 1925.

- ARTHUR R. SMITH.

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