US1768222A - Heat transferrer - Google Patents

Description

June 24, 1930. R. UHDE 1,768,222

HEAT TRANSFERRER v Filed Dec. 19, 1928 2 Sheets-Sheet 1 l v 23 i,

June 24, 1930. R. UHDE I HEAT TRANSFERRER Filed Dec. 19, 1928 2 Sheets-Sheet 2 Patented June 24, 1930 UNITED STATES PATENT OFFICE ROBERT UHDE, OI KASSEL-WILHELMSHOHE, GERMANY, ASSIGNOR T0 SCHMIDT SCHE HEISSDAEPF-GESELLSOHAFT MIT BESCHRKNKTER HAFTUNG, OF KASSEL-WIL HELMSHOHE, GERMANY, A CORPORATION OF GERMANY HEAT TRANSFERRER.

Application filed December 19, 1928, Serial No. 327,033, and in Germany December 29, 1927.

The invention relates to heattransferrers' and while generally applicable is specially designed for the superheating. of steam.

The object of the invention is to construct a heat transferrer, such that when applied, e. g., to the superheating of interstage steam, large quantities of steam can be highly superheated without the interstage superheater attaining undesirable large dimensions.

In the interstage superheaters of modern steam power plants, the high-pressure steam which serves as the heating'medium is led through heating elements arranged in a container through which passes the steam to be superheated.

According to the present inventi0n, each of a series of like heating elements arranged side by side consists of two or more tubes connected in parallel, which for a part of their length. are .formed as helical coils and are so assembled that they provide a continuous coil'sub-divided to correspond with the number of tubes in the individual elements.

With the new heat transferrer, large quantities of steam can be passed through not only the heating elements, but also through the container in which they are arranged, and'the latter steam superheated to. a high degree.

By. reason of the fact that all the heating elements are alike and that each single heat- .ing element consists of two or more tubes arranged in'parallel, which together form a continuous coil, a very large heating surface is provided and as, in addition, the steam in all the tubes passes over only the same comparatively short length of path, its heat content is utilized under the most favourable conditions.

Referring to the accompanying drawings, different forms of the invention are shown by way of example; 7 I

Figure 1 is a vertical central section of a heat-transferring device according to my invention, the heating elements, in the central row only being shown for the sake of clearness;

Figure 2 is a horizontal section on line IIII of Fig. 1;'

Figures 3 and 4 show one form of heating element in side elevations respectively at right angles to one another; I

Figure 5 shows a modified form of heatingelement in side elevation;

Figure 6 being a cross-section on ,line VI-.VI of Figure 5, and

Figure 7 shows another form of heating element in side elevation.

Referring first to Figures 1 and 2, the

casin 18 containin the heatin elements is closed at the top by a plate, 19, and at the bottom .by a plate, 20. To the plate, 19, a

cover, 21, is fastened, provided with chamber, 22, and a branch, 23, leading to that chamber. A similar cover, 24, provided 'with a chamber, 25, and a branch, 26, is secured to the bottom of the casing, 18. The inlet and outlet ends of the heating elements are secured into corresponding holes in the plates, '19, and 20, and communicate with the chambers, 22, and 25, respectively. The superheating medium enters through the branch 23 into the chamber, 22, passes through the heating elements arranged side by side and leaves the device through chamber, 25, and branch, 26. The medium to be superheated enters the casing, 18, through the connection, 27, and leaves the casing through the connection, 28.

The heating elements. arranged in the casing, 1, are formed partly as helical coils and partly as straight lengths, assembled as shown by way of example in the drawings.-

The heating element shown'in Figures 3 and 4 consists of two tubes, 1, 2 and 3, 4, connected in parallel. 1

Theone tube as regards its upper half is wound into a helical coil, 1, and at the middle point in the length of the heating element changes over to a straight length of tube 2, by means of a short bend, 5, running inwards to the axis of the element.

The, second tube, 3,, 4, on the contrary, is

straight as regards the 'upper half, 3, of the running outwards from the axis of the ele- V ment, changes over to a helical coil, 4. In

each case, the straight length of the one tube. lies within the helical convolutions of the tube. At the upper and lower ends of the heating element, the two tubes are respectively connected by the Y -pieces, 7 and 8.

The heating element' shown in Figures 3 and 4 is of somewhat similar construction as those arranged in the casing, 18, of Figures 1 and 2. This element is composed of three tubes connected in parallel. The first tube consists of the upper helically-wound coil, 9, and the straight length of tube, 10, connected to it below; the second tube comprises the lower coil, 11, and the straight length of tube, 12, connected to it above; and the third'tube is formed into helically-wound middle part, 13, and the straight lengths, 14, 15, connected to it respectivelyabove and below.

At their upper ends the tubes are connected to the three-limbed Y-piece, 16, and at their lower ends to the similar Y-piece, 17, the tubular stems of the Y-piece serving to connect the heating elements to the header or the like to or from which the heat carrier is led. By the use of such Y-pieces, an undue multiplication of connections is avoided.

The straight lengths of tube in the modifications described are all arranged within the helical convolutions of the heating element. In some cases it might be preferable to have a part of the straight lengths lying outside the convolutions. The heating element of Figure 7, which is composed of three tubes connected in parallel, has, for example, the straight lengths of tube 12" and 15' arranged outside the convolutions.

In Figures 1 and 2 the individual heating elements, connected in parallel, are arranged in a circle side by side in the container, 18. Instead of the circular arrangement shown, the heating elements may also be disposed in rows, for example, in parallel formation.

The essential requirement is that all the individual heating elements are connected in parallel so that the highly-superheated steam serving as heat carrier fiows through all'the elements under the same conditions.

By the sub-division of the like individual heating elements into tubes connected in parallel and helically wound for only a part of their length, the resistance to flow which,

the heat carrierhas to overcome is substantially less than if each tube were formed as a coil for its whole length; thus, the resistance to flow in the form of the invention shown in Figures 1 and 2 is approximately one-half and in the form of the invention shown in Figures 3 and 4, one-third as much as in a single helical coil of the same length.

Transfer of heat, which occurs for the most part in the helical coils, is comparatively large as these coils, notwithstanding their sub-division, extend continuously over the length of the heating element.

In addition, the straight lengths of tube I lying within the helical convolutions contribute to the quantity of heat transferred "lengths, and are so assembled that they provide a coil sub-divided to correspond with the number of tubes of the individual elements.

' 2. In a heat-transferrer of the class described the combination of a casing, an inlet. to and an outlet from said casing, a plural- 1 ity oflike heating elements arranged side by side in said casing and an inlet connection and an outlet connection communicating with said heating elements, each of which elements consists of two or more tubes arranged in parallel, which are formed partly as helical coils and partly as straight lengths,

and are so assembled that they provide a U coil sub-divided to correspond with the number of tubes of the individual elements, said straight lengths of'the tubes passing through the convolutions of the helical coils.

3. In a heat-transferrer as defined in claim 1, the said tubes forming the compound coil being connected at each end-of. the'heatingelement to a common Y-piece.

In testimony whereof I have aflixed my signature.

ROBERT UHDE.

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