US2687843A - Gas pressure exchanger - Google Patents

Description

Aug 31, 1954 ALCQCK 2,687,843

. GAS "PRESSURE EXCHANGER Filed Jan. 5, 1951 3 Sheets-Sheet 5 Patented Aug. 31,, 1954 GAS PRESSURE EXCHANGER John Forster Alcock, North Lancing, England, as-

signor to George Jendrassik, London, England; Andre Gabor .Tihamer Baszormenyi and Clara J endrassik, executors of said George Jendrassik,

deceased Application January 5, 1951, Serial No. 204,666

H Claims priority, application Great Britain January 6, 1950 6 Claims. i 1 r This invention relates to gas pressure exchangers of the kind comprising a cell rotor drum, and in which, to minimise gas leakages, a criticalaxial clearance requires to be maintained ateach end of the drum between a surface on the end face of the drum and a surface on axially adjoining stator or rotor structure, which pair of surfaces will be hereinafter called mating surfaces.

' The maintenance of suitably small clearances between mating surfacesis a diflicult problem because of thermal expansion effects caused by the hot gases, but is important because if, to

allow for expansion, the clearances are made ex The present invention provides a gas pressure exchanger of the kind referred to, wherein the mating surfacesat each end of the rotor drum are of frusto-conical form, with the apices of the cones meeting substantially at a common point on the axis of rotation of the drum, and means are provided to locate the drum axially so that the effective point of such location cincides substantially with the common apex point ofthe cones.

The invention is applicable, tdmachines in which there is only one cell rotor drum, or to machines having a pair of substantially coaxial contra rotating rotor drums, whether these are separated by stator structor or not.

In this specification and in the claims the word cone and expressions derived therefrom, such as conical, or frusto-conical, is used to include the case of a fiat surface, which, is regarded asa cone of 180? apex angles.

Examples of pressure exchangers according to the invention will now be described with reference tothe accompanying drawings, in which: Figure 1 is an axial section through a pressure exchanger havingone cell rotor.

Figure 2 is a similar sectionof a machine having two contra-rotating cell rotors.

Fig. 3 is an enlargement of a part of Figure 2. The examples shown in the drawings will be described only so far as is necessary for the understanding of the present invention. It will be assumed that the machines described operate in known manner.

A pressure exchanger as shown in Figure 1 comprises a cell rotor consisting of inner and outer cylindrical members i, 2 connected by radial partitions 3 which divide the annular working spacebetween I and 2 into sector shaped cells. The rotor is mounted within a stator cas- .ihg comprising end covers 4, 5 of substantially circular section connected by a central cylindrileakage.

at circumferentially spaced points with ports such as 1 through which in operation there is afiow of gas to or from the rotor cells.

To prevent excessive gas leakage there should bea close working clearance between the pairs of mating surfaces 8, 9 and 10, ll respectively. The fulfillment of this condition is a practical difficulty due to thermal expansion so that if the cold clearance is too small rubbing will occur when the rotor heats up. Alternatively if the clearance is made sufficiently large to avoid this difliculty there is likely to be excessive gas In accordance with the present invention the surfacest, 9 I0, I I form part of the surfaces of two cones of which have their apex at the point A. The 'small working clearance between the mating surfaces is here ignored and each pair of lines such as 8, :9 are assumed to be coincident.

The rotor is attached to a central hub member 12 on a shaft lZa by a known type of radial pin connection comprising three or more radial pins l3, there being provision for relative sliding movement between each pin and one of the bosses in which it is carried. This arrangement permits the hot rotor to expand radially relative to the hub without the axial position of the rotor beingaii'ected. The axes of the pins l3 also pass through the point A.

The rotor is located axially by a ball or roller thrust bearing I4 so that the point of effective axial location coincides substantially with the apex point A. The nominal axis of rotation of each of the balls (or rollers) of the bearing M also passes through the point A. This may be seen more clearly in Figure 3 which so far as this feature is concerned is substantially the same as Figure 1.

Since the rotor is in effect located axially at the single point A it willbe obvious that if the rotor becomes hot and expands the resultant movement of any particular point on the rotor will be along a radial line of which A is the centre. Thus when the rotor expands any point on for example the surface 8 will move further out on the same cone, so that the clearance between B and 9will remain substantially unaltered in spite of differential expansion between the rotor and the stator ortions. The same applies to the location of the rotor by the radial pins l3, and the support of the hub l2 by the ball bearing M.

The support of the shaft Hat is completed by a second thrust bearing i5 and by journal bearings [6, H which position the shaft radially. A spring Ila imposes a light axial thrust in the direction of the bearing 14.

For the success of the arrangement described it is a necessary condition that there should be no substantial temperature differences between those parts of the stator structure which determine the position of the surfaces 9, H. In the example illustrated the stator casing is provided with passages l8, l9 forming a cooling jacket which contain a coolant for example water which is circulated through the jacket spaces.

Figures 2 and 3 illustrate the application of the invention to a pressure exchanger having two closely adjacent cell rotors which rotate in opposite directions. It will be seen that in this case small working clearances should be maintained at one end between the rotor and. stator elements (i. e. the surfaces 8, 9 and 10, H) and at the other end between the adjoining surfaces 20, 2| of the two rotors. As shown the surfaces 8, 10, H lie substantially on the surface of cones having a common apex point at A. The

mating surfaces 20, 2| lie substantially on a plane surface which passes through the point A at right angles to the rotor shafts. This plane surface is geometrically considered as a cone of 180 apex angle having its apex at A. It will be observed that in this construction the ins it require to be slanted somewhat so that their axes pass through A.

Each rotor is supported by a bearing arrangement substantially the same as that shown in Figure 1 and of which an enlarged view is given in Figure 3. In the construction of Figures 2 and 3, however, there is a difference that the bearings are not carried directly in the cover members 4, 5 but in subsidiary cylindrical members 22 which lie within cylindrical cavities in the cover plates 4, 5 and are located at one end relative thereto by conical surfaces 23. These surfaces form part of cones having apex at A. Each member 22 is urged inwardly by springs 24 and further supported by a radial pin arrangement comprising three or more pins 25'simi'lar to the pins I3 described above. Having regard to the manner in which the members 22 are supported, and in particularthe frusto-conical faces 23 it will be clear that there may be differential ex pansion between a member 22 and the cover plate t or 5 in which it is mounted, without the axial location of the rotor concerned being effected.

The members 22 each have their own cooling jacket 26 in which cooling liquid may be contained or circulated. Thus the outer stator structure may be maintained at a different temperature from the members 22. For example, the outer structure may be maintained at about 250 C. by the use of a coolant such as diphenyl oxide in order to reduce heat losses from the gas or to provide high temperature waste heat for auxiliary purposes. This temperature would be too high for the bearings and therefore the members 22 are jacketed with water and kept say at about to C.

The invention is also applicable to pressure exchangers similar to Figure 2 but in which the rotors are separated by central stator structure intervening between the surfaces '20, 2 I. In such a case the apex points A associated with each rotor would not-coincide as in Figure 2-but would be axially separated. The arrangement may be visualised by imagining a mirror image of Figure 1 being laid alongside Figure 1 on the left hand side thereof. The cover plate i'may be imagined as forming part of the central stator structure separating the two rotors. Thus each pair of mating surfaces would be defined by a cone of less than apex angle. Alternatively the pair of mating surfaces at one end of each rotor (either the inner or outer end )may be defined by a cone of 180 apex angle, and the mating surfaces at the other end by a cone of apex angle less than.180.

I claim:

-1. A gas pressure exchanger including a cell rotor drum, and structure axially adjoining each end face of said drum and having a surface required so to mate with a corresponding surface on the adjoining end face that in operation a small axial clearance of critical dimensions is maintained despite thermal expansion effects,

wherein the mating surfaces at each end of the rotor drum are of frusto-conical form with the apices of the cones meeting substantially at a common point on the axis of rotation of the drum, and means are provided to locate the drum axially so that the effective point of such location coincides substantially with the commo apex point of the cones.

2. A gas pressure exchanger according to claim 1, wherein the rotor drum, being axially adjoined at each end by stator structure, has its effective point of axial-location substantially central of the drum, and both pairs of mating surfaces are defined by cones of apex angle less than 180. '3. A gas pressure exchanger according to claim 1, wherein the rotor drum is axially adjoined at one end by stator structure and at the other end by the adjacent end of a second cell rotor drum substantially coaxial with the first and rotating oppositely thereto, and both drums have substantially a common effective point of axial location centrally of the two drums, the rotor-to-' rotor mating surfaces being defined by a cone of 180 apex angle, and the rotor-tostator mating surfaces by a cone of less than 180 apex angle, the apices of both cones substantially coinciding with the effective point of axial location of the drums.

4. A gas pressure exchanger according to claim 1, wherein there are two substantially coaxial contra-rotating rotor drums which are axially adjoined at their outer ends by stator structure, and at'their inner ends by stator structure'which separates the drums, and wherein, for each drum, both pairs of mating surfaces are defined by cones of which the apices meet substantially at the effective point of axial location of the drum.

5. A gas pressure exchanger according to claim 1, wherein the rotor drum is supported from a hub member by radial pins which permit free radial expansion of the drum.

6. A gas pressure exchanger according to claim 5, wherein the rotor drum is axially located by a bearing incorporating rolling elements in such manner that the nominal axis of rotation of each rolling element passes substantially through the common apex point of the cones which define the two pairs of mating surfaces.

Beferences Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,038,200 Rateau Sept. 10, 1912 1,877,345 Mattmann Sept. 13, 1932 1,905,521 Steiner Apr.'25, 1933 2,021,510 Jones Nov. 19, 1935 FOREIGN PATENTS Number Country Date 553,208 Great Britain 1943

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