US2803438A

US2803438A - Regenerative heat exchangers

Info

Publication number: US2803438A
Application number: US327627A
Authority: US
Inventors: Hryniszak Waldemar
Original assignee: CA Parsons and Co Ltd
Current assignee: CA Parsons and Co Ltd
Priority date: 1952-06-23
Filing date: 1952-12-23
Publication date: 1957-08-20
Anticipated expiration: 1974-08-20

Description

2 Shets-Sheet ,Filed. Dec. 25, 1952 Aug. 20, 1957 Filed Dec. '23, 1952 W. HRYNISZAK REGENERATIVE HEAT EXCHANGERS 2 Sheets-Sheet 2 "INVENTOR. Wawzsmze HEM/529K.

BY I

' ATTO vs.

Unite tates 2% REGENERATIVE HEAT EXCHANGERS Waldemar Hryniszak, Newcastle-upon-Tyne, England, assignor to C. A. Parsons & Company Limited, Newcastle-upon-Tyne, England Application December 23, 1952, Serial No. 327,627

Claims priority, application Great Britain June 23, 1952 9 Claims. (Cl. 257-6) This invention relates to regenerative heat exchangers particularly in connection with gas or other combustion turbines.

More especially the invention relates to a regenerative heat exchanger the rotor of which consists of a number of discs arranged in parallel.

It is known to incorporate in a gas, that is combustion turbine unit a single-disc type of regenerative heat exchanger tor the purpose of preheating the air before it is heated to its final temperature in the combustion chamber.

Regenerative heat exchangers with both single-disc and multiple-disc rotors are known. In the latter case the discs are usually assembled behind each other on a com mon shaft, or--in technical terms-in series.

Where a high degree of heat recovery in the heat exchanger is demanded, a number of discs are assembled on a shaft so as to form a single heat exchanger. Such a heat exchanger has the disadvantage that it is fairly bulky, and that the distribution and collection of the gases exchanging heat in the discs is difiicult and involves complicated ducts. Because of this, the parasitic losses of the gases are increased and the efiiciency of the gas turbine unit reduced.

It is known that the incorporation of an air preheater in a combustion turbine unit involves several inconveniencesin addition ducts, extra space required by the combustion turbine unit, and the like. When the preheater is built up from several elements, however, and especially when the latter are self-contained, that is independent of each other as regards their actuation, that prehe ter can be individually shaped and arranged so as to interfere as little as possible with the general make-up of the turbine.

When heat exchangers of the disc type are used as air preheaters in a combustion turbine unit, several disadvantages are known to exist. Some of these drawbacks are concerned mainly with the ducting between the compressor and the turbine on the one hand, and the air preheater on me other. Both the hot and cold gases leave the turbine and compressor respectively distributed in annular form. it an air preheater with a single disc is used, bcfn the hot and the cold gas sides are assembled over one and the same annulus, and this means that the ducts carrying the two heat-exchanging gases have to be arranged alongside each other. The number of these hot and cold gas sides must be kept as small as possible so as to prevent excessive clearance losses between the rotor and stator of the air preheater. This involves the use of complicated ducts between the compressor and turbine cutlets the inlets on the hot and cold gas sides of the air prebeater in order to transfer the gases from two scpcr te annular areas assembled alongside other. Efiicient air preheaters require a large matrix area, that is frontal area, in term of flow. The areas forrnin the gaps between the rotor and stator, that is the areas responsible for the clearance losses, are proportional to this matrix area. The greater this area, the

Patented Aug. 20, 1957 greater the amount of distortion set up in the areas forming the gaps, and the greater the amount of clearance necessary between these areas This increases the clearance loss. The .greater the matrix area, the less chance there is of using a rubbing seal because of the distortion mentioned above and the fact that the speed of the disc has to be increased when the matrix area is increased. when rubbing seals are used, this means an increase in the wear of the sealing materials.

Attempt have been made to overcome these difliculties by using more than one disc and so reducing the frontal area of each disc.

Air preheaters of the multiple-disc type have a rotor formed by a number of similar discs assembled behind each other in space on a common shaft. This type of air preheater is known to have the disadvantage of involving even more complicated systems of ducting between the turbo-machines and the air preheater. The problem of ducting is made more difficult still by the need for getting the hot .and cold gases into and out of the spaces between the discs. An arrangement of this .kind necessitates not only a fairly complicated rotor, but

an even more complicated stator. Although the distortions in the discs themselves are smaller in extent because of the reduction in their size, the sealing problem is still a diflicult matter owing to complications in the make-up of the stator and the rotor.

The object of the present invention is to provide an improved regenerative heat exchanger and more particularly an assembly of two or more of regenerative heat exchanger elements such, for instance, as described in British application No. 15,782/52 in a manner suitable for forming a composite regenerative heat exchanger, es-

ecially one used as a preheater for combustion turbine units, mainly in the direction of arrangement, efliciency, behaviour in service and simplification.

Referring to the accompanying diagrammatic drawings:

Figure 1 is a front elevation partly in section, and

Figure 2 a sectional elevation or cross section of one form of the present invention called a frontal form.

Figure 1 is made from a series of sections as follows namet the top left hand quadrant is a section on the line A-A of Figure 2; the top right hand quadrant is a section on the line C-C of Figure 2; the bottom left hand quadrant i a section on the line B-B of Figure 2, and the bottom right hand quadrant is a section on the line X-X of Figure 2, all the sections being taken in the direction indicated by the arrows.

Figure 3 is a front elevation partly in section of a form of the invention in which the discs are arranged polygonally.

Figure 4 is a section on the line 4-4 of Figure 3.

In carrying the invention into eifect in the form illustrated by way of example in Figures 1 and 2 of the accompanying diagrammatic drawings, four small similar disc-type rotors 1 are arranged in a single plane of the stator Z of the single-disc type. The rotors are arranged so that the cold gas sides 3 and the hot gas sides 4 are incorporated in an inside and an outside annulus respectively. The outside annulus 5 may incorporate the cold gas sides, the inside annulus 6 the hot gas sides of the air preheater, but the position of these two annuli may be reversed to suit the arrangement and types of the other components of the turbine.

The cold gas is conducted from the compressor of the gas turbine (not shown, but situated on the left-hand side of Figure 2) through ducts 7 in the stator to the inlet of the cold gas side. These ducts are arranged in the free spaces between the rotors so that the cylindrical arrangement of the stator is not affected. The air leaving the ducts is collected in an annular chamber '8 and distributed over the inlets of the cold gassides. 1

The rotors may consist of a cylindrical central portion 9 having an outside ring 9a and an inside ring 9b. These rings are connected by ribs 10 to form a number of equally spaced compartments 11 in which a matrix 12 .is embedded. The inlet and outlet areas of the compartmentsare smaller than the matrix area. The area 13 on the large-volume side is larger than the area 14 on the small-volume side. The seal is provided by two plates on either side. One of these plates 15 is fixed to the rotor, Q

such, forinstance, as some ceramic material.

' The rotors revolve on an axis-pin by means of bear- .ings 21'. Gear teeth 22 are provided on the cold end of the rotor and mesh with the teeth'on a central pinion 23 which is rotated by a shaft 24 mounted in bearings 25 and 26 and a further set of gears 27 by a prime mover,

say, for instance a hydraulic, electric or pneumatic motor.

The hot gases are collected in an annular chamber 28 'at the outlet of the hot gas side of the air preheater.

Figure 3 shows the discs arranged polygonally; the discs being of identical construction to those described in connection with Figures 1 and 2. The figure shows an arrangement of six such discs, but the ducting is not shown. The discs are shown housed in a casting 30 forming a solid casing, but each rotor housing may of course be made separately.

Figure 4 is a section on the line 44 of Figure 3 but details of the two angularly displaced disc housings 31 and 32 have not been shown. Hot exhaust gas from the turbine could enter through opening 33, flow through 'the disc and leave by exit opening 34 to exhaust. Cold gas or air from the compressor could enter through opening 35, fiow through the disc and leave through outlet 36 to the combustion chamber. By such an arrangement the hot gas ducts are arranged on the inner annulus and the cold ducts on the outer annulus.

, Whether a frontal arrangement or a polygonal arrangement be selected, it must be kept in mind that usually the maximum circle into which the air preheater for instance the elements can be accommodated is fixed by the same limitations as the turbine unit. The question then arises how to fit into the given diameter the maximum possible matrix area, which means the number of elements of a given size.

With a frontal arrangement comparing the total matrix area taken up by different numbers of elements accommodated in a given circle, the matrix area being compared with the area of the circle, the total matrix area is always smaller than the circle area, and the ratio of these two areas attains a maximum for about four elements. The

annulus may bound an area equal to the total area of the matrix.

The polygonal arrangement gives a different result. Here the totalmatrix area of the elements up to about nine is largerf than the area of the circumscribing circle. The area ratio reaches a maximum for three elements. As the number of elements in a given circle increases, the length of the composite preheater decreases. If four elements are used in the case of the polygonal arrange ment, the matrix area is twice the circle area. With the frontal arrangement, however, the matrix area is only aboilt percent of the circle area.

Among the advantages of a composite preheater made as described above are the following, namely:

(1) Arrangement.0neof the drawbacks of' an air preheater is that long and large ducts are required to join the preheater with the other gas turbine components. The preheater is usually fairly bulky, especially when high efiiciencies are required. Matters can be improved considerably by dividing the regenerative preheater into several self-contained elements, which being small can be 'be easily'connected with the outlet annuli of the turbomachines and the inlet annuli of the combustion chamher and. exhaust ducting respectively.

(2) Ejficiency.The efiiciency of the preheater may be varied by varying the number of its elements. The usual type of preheater can generally be used only for one particular turbine unit, whereas the composite type can be fitted into any combustion turbine independently of the shape and arrangement of its components. In addition, one and the same turbine can easily be fitted with composite preheaters built up of different numbers of elements to suit the purpose for which the turbine is used. It is therefore comparatively easy and inexpensive to develop such a unit for the purpose of improving fuel consumption and increasing efficiency.

(3) Behaviour in service. -As there are several ele ments ina composite air preheater, the failure of one will only temporarily reduce the efficiency of the turbine slightly, as the remainder will still function properly. The

. elements of such a preheater can readily be replaced, and

the elements may be mass produced.

(4) Simplification of development w0rk.Development costs can be reduced because only one element need be built and tested, and the single element means lower costs for making and testing the experimental preheater with reduced cost of fuel and air supplies, smaller space required and the like.

I claim:

1. A regenerative heat exchanger comprising, in combination, a plurality of disc type rotors, a common stator for the rotors, means mounting the rotors in the stator spaced from each other and for rotation about respective axes symmetrically disposed with reference to a predetermined axis, drive means for rotating the said rotors about their respective axes, and fluid supply and discharge connections for hot and cold fluids, the said connections comprising annular ducts symmetric about the said predetermined axis, common to all the said rotors and including for each rotor opposed duct means communicating with opposite faces of the rotor for circulating a hot gas therethrough and opposed duct means communicating with opposite faces of the rotor for circulating a cold gas therethrough in parallelism to its axis of rotation, the two last said means being fixed in position, whereby as each rotor rotates, each segmental area thereof is subjected alternately to flow of hot gas and of cold gas.

2. A regenerative heat exchanger comprising, in combination, a plurality of disc type rotors, a common stator for the rotors, means mounting the rotors in the stator spaced from each other and for rotation about respective axes symmetrically disposed with reference to a prede termined axis, drive means for rotating the said rotors about their respective axes, fluid supply and discharge connections for hot and cold fluids, the said connections comprising annular ducts symmetric about the said predetermined axis, common to all the said rotors and including for each rotor opposed duct means communicating with opposite faces of the rotor for circulating a hot gas therethrough and opposed duct means communicating with opposite faces of the rotor for circulating a cold gas therethrough in parallelism to its axis of rotation, the two last said means being fixed in position, whereby as each rotor rotates, each segmental area thereof is subjected alternately to flow of hot gas and of cold gas, and rubbing sealing means between the said connections and the rotor.

3. A regenerative heat exchanger comprising, in combination, a plurality of disc type rotors, a common disc type stator for the rotors, means mounting the rotors in the stator for rotation about respective axes symmetrically disposed with reference to, spaced from and parallel to the stator axis, drive means for rotating the said rotors about their respective axes, and fluid supply and discharge connections for hot and cold fluids, the said connections comprising annular ducts symmetric about the stator axis, common to all the said rotors and including for each rotor opposed duct means communicating with opposite faces of the rotor for circulating a hot gas therethrough and opposed duct means communicating with opposite faces of the rotor for circulating a cold gas therethrough in parallelism to the stator and rotor axes, the two last said means being fixed in position, whereby as each rotor rotates, each segmental area thereof is subjected alternately to flow of hot gas and of cold gas.

4. A regenerative heat exchanger comprising, in combination, a plurality of disc type rotors, a common disc type stator for the rotors, means mounting the rotors in the stator for rotation about respective axes symmetrically disposed with reference to, spaced from and parallel to the stator axis, drive means for rotating the said rotors about their respective axes, fluid supply and discharge connections for hot and cold fluids, the said connections comprising annular ducts symmetric about the stator axis, common to all the said rotors, and including for each rotor opposed duct means communicating with opposite faces of the rotor for circulating a hot gas therethrough and opposed duct means communicating with opposite faces of the rotor for circulating a cold gas therethrough in parallelism to the stator and rotor axes, the two last said means being fixed in position, whereby as each rotor rotates, each segmental area thereof is subjected alternately to flow of hot gas and of cold gas, and rubbing sealing means between the said connections and the rotor.

5. A regenerative heat exchanger comprising, in combination, a plurality of disc type rotors, a common an nular drum type stator for the rotors, means mounting the rotors in the stator for rotation about respective axes symmetrically and radially disposed with reference to the stator axis, drive means for rotating the said rotors about their respective axes, and fluid supply and discharge connections for hot and cold fluids, the said connections comprising annular ducts symmetric about the stator axis, common to all the said rotors and including for each rotor opposed duct means communicating with opposite faces of the rotor for circulating a hot gas therethrough and opposed duct means communicating with opposite faces of the rotor for circulating a cold gas therethrough in parallelism to its axis of rotation, the two last said means being fixed in position, whereby as each rotor ro tates, each segmental area thereof is subjected alternately to flow of hot gas and of cold gas.

6. A regenerative heat exchanger comprising, in combination, a plurality of disc type rotors, a common annular drum type stator for the rotors, means mounting the rotors in the stator for rotation about respective axes symmetrically and radially disposed with reference to the stator axis, drive means for rotating the said rotors about their respective axes, fluid supply and discharge connections for hot and cold fluids, the said connections comprising annular ducts symmetric about the stator axis, common to all the said rotors, and including for each rotor opposed duct means communicating with opposite faces of the rotor for circulating a hot gas therethrough and opposed duct means communicating with opposite faces of the rotor for circulating a cold gas therethrough in parallelism to its axis of rotation, the two last said means being fixed in position, whereby as each rotor rotates, each segmental area thereof is subjected alternately to flow of hot gas and of cold gas, and rubbing sealing means between the said connections and the rotor.

7. A regenerative heat exchanger according to claim 3, in which the said connections comprise radially inner and outer annular conduits for the respective two fluids.

8. A regenerative heat exchanger according to claim 7, in which one of the said annular conduits comprises a duct for connecting to the outlet of a gas turbine.

9. A regenerative heat exchanger according to claim 8, in which another of the said annular conduits comprises a duct for connecting to the outlet of a compressor.

References Cited in the file of this patent UNITED STATES PATENTS 1,741,225 Dyrssen Dec. 31, 1929 2,469,758 Alcock May 10, 1949 2,503,651 Alcock Apr. 11, 1950 2,631,870 Hodson Mar. 17, 1953 FOREIGN PATENTS 649,265 Great Britain Jan. 24, 1951