US1935463A - Casing for steam or gas turbines - Google Patents

Description

NOV. 14, 1933. Q. A w G CASING FOR STEAM 0R GAS TURBINES Filed March 16, 1932 2 Sheets-Sheet 1 Fig.1 """o 1 /f 0 g g 2 a, A? 2 IL Law MAW 5 WW /,4.\\ A I J 2 2 Sheets-Sheet 2 o. A. WIBERG Filed March 16, 1932 QM Q. if tfimwu/yy Patented Nov. 14, 1933 Oscar Anton'Wiberg, Finspong, Sweden Application .MarchlG, 1932, Serial N o.n599,294 and in Germany March 13, 1931 11 Claims. (Cl.25316.5)

In steam or gas turbines the casing which encloses theblading is subjected todifferent temperatures at different points. This will give rise to high stresses in the material-of the casing,

.5 whereby fatiguing thereof and breakage may result. Especially in case vof radial flow turbines which operate on the counter pressure principle, and in which an outer casing and an inner casing are provided, such stresses most frequently .1 appear in the inner casing. The inner casing of such a turbine usually comprises two halves bolted together. ,In case of a turbine of this,

kind, having blades and discs rotating in opposite directions, each half of the inner casing com- 157: prises one annular lateral steam or gas chest at least, and is formed outside this chest or chests with a cupshaped wall, in such a Way that the cup shaped walls of both halves, when brought together to form the casing, will provide 29 an outer chamber 'to receivethe exhaust gas or steam-discharged from the turbine blading. In order totake care of the stresses in the material due to the different temperatures, said cup shaped walls are made yieldable; Nevertheless, the ma- Z terialwill-be subject to fatigue due to the continuously varying temperature, and breakage will, consequently, follow sooner or later. Said variations of temperature are due to the fact that the driving medium, suchas gasor steam, supplied toithe annular lateral chest is; normally, of a considerably higher temperature than that of the exhaust medium discharged fromthe blading.

The object of the invention is to overcome the 4 above said drawback without necessitating the .13 j manufactureof 'the'c'asing, subjected to the different temperatures, from an expensive material of sucha high quantity as to permit the action of such stresses. 3 w To .this'end said turbine casing, according to $9. the present-invention, comprises a: plurality of members steam or gas-tightly connected together .by expansion elements. This will permit the use of'a cheap material of moderate strength as material'for the-casing..- 4r, In-:the accompanying drawings is illustrated by way of example;

Fig. 1 is an axial section, taken on line I -I of Figs'p2 or 5, of the upper portion'of a radial flow turbinehavingblades and discs rotating in oppo- 5 site directions'and provided with an inner casing according to thisinvention. Fig. 2 is a cross section on a reduced scale taken online II-II of Fig.1,showing the inner casing of the turbine. Figs.z3 and iarecross sections on a larger scale the invention of variousforms of expansion elements used to are shaft packings 9, 9.- Each lateral member 2 pand and. contract independently of the memthe grooves receiving the ends of the rings. It is connect the members of the inner turbine casing to each other; Fig. ,5 is a cross section of an in ner turbine casing of a modified construction, Fig.6 is an axial section of a turbine similar to Fig. l, but having double expansion rings. 60.

With reference to Fig. 1,- the numeral 1 indicates the outer casing of a-turbine having also an innercasing comprising two lateral members 2, 2 and one intermediate member 3. 1 and 5 indi-. cate two oppositely rotating shaftswhich each carry a turbine disc 6 and. 7,-respectively, with the asociated blading 8. Inserted-between the shafts and the members 2, 2 of the inner casing of the inner turbine casing contains an annular chamber 10 and 11,.respectively, and the intermediate member 3 contains a chamber 12 surrounding-the blading 8. The members 2, 2-containing the lateral chambers 10 and 11 are carried by the outer casing 1 through theintermedium of rings13, 14 secured to said outer casing, and expansion elements. In addition, the members or walls ,2 are rigidly connected together by means of bolts 15 extending through annular outer flanges of the members 2. The member 3 of the inner casing is carried by the members 2, 2 through the aid of expansionelements 16, 16which comprise resilient rings connecting said outer flanges of the members 2, 2 to the inner periphery of the member 3. Said member 3 is provided with axially extending stays 17 through which the bolts 15 extend. The borings of said stays 1'7 to receive the'bolts 15 surround the bolts with a given play'so as to allow the members 2, 2 to ex-- ber-3. I v

I As shown in Fig. 2 the member 3 contains two chambers 12, .12 each surrounding half the periphery ofthe blading, and each provided with a separate outlet 18. The two outlets '18 are situated atdiametrically opposite points. The cross section of the stays 17 is of streamline form in order to afford a lowresistance to the exhaust steam or gas. 3

Fig. 5 illustrates another embodiment of an inner turbine casing constructed according tothis invention. The member 3 contains two chambers 12, but only one outlet 19 common to both chambers.

Fig. 3 shows an expansion ring 16 cut atright angles at both ends, Whereas Fig. 4 shows an expansion ring formed with rounded ends. In both of these figures packing material 20 isinserted between the. endsof the rings and the bottom of .curred in the expansion rings. i ring only or both rings need be replaced while,

to be noted, however, that the rings may also engage the grooves without interposed packing material. The rings 16 should be of a sufiicient axial length to allow the relative displacements of the members of the casing with respect to one another. It is to be noted that the larger the axial length of the rings, the higher is the elasticity of the rings, and the lower is the bending stress.

In the operation of a steam turbine having an inner casing constructed as described, the members 2, 2 of said casing, the chambers 10 and 11 of which contain steam of a higher temperature than that of the steam contained in the chamber 12 of the member 3, have a tendency of expanding to a higher degree than the member 3. The members 2, 2 when thus expanding, will carry the bolts 15 with them and, when thus acted on, the bolts may move freely in the borings of the stays 17. The expansion rings 16 due to the expansion of the members 2, 2 are now bent so as to assume a cup shape. As a result, said rings-will transmit a pressure to the member 3 to a certain degree. tured from a good material of high strength and high elasticity, the pressure transmitted through said rings will be very low, and it is, therefore, sufficient to use as material for the various mem bers of the turbine casing a cheap material of very low elasticity, because in such case said lastmentioned material need only satisfy moderate conditions as to strength and elasticity.

In case a breakage occurs it may be assumed that, in the most cases, said breakage has oc- In such case one hitherto, it was necessary to replace the entire casing.

Instead of the expansion rings 16 other expansion elements may, of course, be used without departing from the principle of the invention. In-

stead of single expansion rings between the intermediate and lateral members 3 and 2, 2 of the inner casing, double rings may be used, for instance, as shown in Fig. 6, where in additionto the ring 16, situated inside the set of connecting bolts 15 a similar ring is provided outsideof said set of bolts, as shown at 21.

The bolts 15 may be hollow in order that they may rapidly be heated to the temperature of the surroundings. The stays 1'7 are preferably uniformly distributed around the entire blading.

What I claim is:- 1. A casing for a radial flow elastic fluid turbine and its blading comprising, a plurality of separate members axially spaced apart, each of fluid turbine and its blading, of an outer casing and an inner casing comprising three separate members, viz. two lateral members positioned on opposite sides of the turbine blading and. one intermediate member situated axially between said lateral members, each of said lateral members containing at least one annular chamber to receive the driving fluid and distribute it to the blading, the intermediate member containing at least one chamber to receive the exhaust fluid discharged from theblading,

If, however, the rings 16 are manuiacexpansion elements to connect the lateral members to the outer casing, expansion elements to connect said intermediate member to said lateral members in such a way that said lateral members may carry the intermediate member by the aid of said expansion elements, and means acting independently of said intermediate member to press said lateral members against said expansion elements.

3. A casing for a radial flow elastic fluid turbine and its blading, comprising two separate lateral members positioned on opposite sides of the turbine blading and one intermediate separate member, axial bolts to connect said lateral members to each other for expansive movement independent of said intermediate member, and

expansion elements to connect said intermediate member to said lateral members and to form steam-tight joints therebetween, said lateral members each having at least one annular chamber in communication with the center of the blading, and'said intermediate member having separate chambers in communication with individual parts of the outer periphery of the blading.

4. A casing for radial flow elastic fluid turbines, comprising two separate lateral members on opposite sides of the turbine blading to receive driving fluid and distribute it to the blading, one separate intermediate member to receive the exhaustfluid discharged'fro'm the blading, axial stays in said intermediate member, bolts extending with play through holes in said stays to connect the lateral members to each other for expansive movement independent of said intermediate member, and expansion elements to connect said intermediate member to said lateral members. I a

5. A casing for a radial flow elastic fluid tur bine and its blading, comprising three separate 115 members displaced axially with relation to each other, these members consisting of two lateral members situated on opposite sides of the turbine blading and one peripheral member situated axially between said lateral members so as to surround the blading, axial stays of streamline section in said peripheral member, axial bolts extending with play through holes in said stays to connect said lateral members to each other for expansive movement independent of said peripheral member, and axial expansion rings to yieldingly connect said peripheral member to said lateral members and to form steam-tight joints therebetween.

6. A casing for radial flow elastic fluid turbines, comprising a peripheral member and lateral members displaced axiallywith relation to each other, each of said members containing independent fluid chambers, axial stays of streamline cross section in said peripheral member, 135 axial bolts to connect said lateral members for expansive movement independent of said peripheral memben'and axial elastic rings to connect said peripheral member to said lateral members in such a way that the lateral members 140 may carry the peripheral member by the aid of said elements.

7. A casing for radial flow elastic fluid'turbines, comprising a peripheral member to receive fluid that has expanded to a certain degree in the 145 turbine and two opposite lateral members, axial bolts to rigidly connect said lateral members to each other for expansive movement independent of said peripheral member, and expansion elements by means of which said lateral mem- 150.

each other for expansive movement independent of said peripheral member, and expansion elements by means of which said peripheral member is supported by said lateral members, and which elements form steam-tight joints between said members. i

9. A casing for radial flow elastic fluid turbines, comprising a peripheral member to receive driving fluid that has expanded to some degree in the turbine, and two opposite lateral members to receive fresh fluid and distribute it to the turbine, axial hollow stays of streamline cross section said peripheral member, axial bolts extending with pay through said hollow stays to ing fluid and distribute it to the blading and one intermediate peripheral member containing separate chambers each surrounding an individual portion of the circumference of the blading so as to communicate therewith, axial stays of streamline cross section in said peripheral member, axial bolts to connect said lateral mem- I bers to each other for expansive movement independent of said peripheral member, expansion elements by which said peripheral member is carried by said lateral members, and which elements form steam-tight joints therebetween,

and separate outlets leading from the chambers of said peripheral member.

11. In an elastic fluid turbine, the combination with a rotary blading for radial flow and an outer stationary casing of an inner stationary casing, comprising two lateral members on opposite sides of the blading, and each containing one annularchamber at least to receive the driving fluid and distribute it to the blading, and one intermediate peripheral member containing separate chambers each surrounding an individual portion of the circumference of the'blading, and communicating therewith so as to receive the exhaust fluid discharged therefrom, axial hollow stays of streamline cross section in said peripheral member, axial bolts to rigidly connect said lateral members to each other for expansive movement independent of said peripheral member, said bolts extending with play through said hollow stays, axial elastic rings'by which said peripheral member is connected to said lateral members so as to be supported thereby, and separate outlets in said peripheral member leading from the individual chambers thereof. 7

v OSCAR ANTON 'WIBERG.

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