US2643097A - Regenerative heat exchanger - Google Patents

Description

June 23, 1953 Filed March 8. 1949 A. T. BowDl-:N ETAL REGENERATIVE HEAT EXGHANGER 3 sheets-sheet 2 June 23, 1953 A. T, BQWDEN TAL 2,643,097

` REGENERATIVE HEAT EXCHANGER Filed March 8, 1949 3 SheetvsTSheet 3 Patented June 23, 1953 2,643,097 REGENERATIVE HEAT EXCHANGER Andrew Thomson Bowden, Newcastle-upon-Tyne, and Waldemar I-Iryniszak and liaulV Kolb, Whit=` ley Bay, England, assignors ofYone-fourth to C. A. Parsons & Company Limited, Newcastle upon-Tyna England Application March 8, 1949, S'erial No. 80,244 In Great Britain December 12, 1947 4 Claimsr (Cl. 257-6) This invention relates to combustionl turbines of all types embracing those in which the Working fluid may be obtained from .a solid, liquid, er gaseous source, for instance, gas, oil, or coal, and which may be produced either internally or externally.

rlhe invention particularly relates to sealingdevices in exchangers of the rotary heatacculnulative type, sometimes called the regenerative type. Such exchangers are used in combustion turbine power units for transferring the heat between the hot gases and the compressed air beu fore it is heated in the combustion. chamber.

In a heat exchanger cf this type the heat is transferred by passing the hot gases through one half of a rotating drum containing heatA transfer. surfaces and by passing the air to which, the heat is to be transferred through the other half of the drum. It is usual :for` the air to pass through one half of the exchanger after delivery from the compressor and it is therefore, at a high pressure, while the gases are passed through the other half of the exchanger after exhausting from a turbine and are, therefore, at a loWe pressure than the air.

The object of this inventionk is to provide a` method of sealing between the tvvov parts of theA exchanger as the rotating drum passes from the low pressure gas side to the high pressure air side, and vice versa.

Referring to the accompanying diagrammatic drawings: l

Figure 1 is a longitudinal sectionalelevation of a regenerative heat exchanger of the rotating drum type;

Figure 2 is a transverse section on the line 2-'2 of Figure l. looking in the direction of the' ar= rows; i

Figure 3 illustrates forces acting on the shoes when a chamber passes underneath them, the yposition being one of maximum pressure;

Figure 4 is similar to FigureV 3 with the drum moved a certain distance on, theposition being one of intermediate pressure, and

Figure 5 is similar to Figures 3 and 4 With the rum still further moved forward, the pressure being the condition of minimum pressure;

Figure 6 is a diagram showing the relationship between periodicity` onY the horizontal' axis and, on the vertical axis force or pressure at different times;

Figure 7 illustrates diagrammatically a control system for use according to one form of the present invention.

In carrying the invention into effect in one form by way' of' example and referring iirst more particularly to Figures 1 and 2, the exchanger consists oiv an outside casinga which is. divided into two parts by seals b. There is a gas' inlet connection at c and an air outletV connection at d; Inside this casing an annular drum c is rotated. A second and internal casing f is iitted inside the drum e so that the interior space is divided into two sections byseals g in such a Way as to provide axial openings at the ends of the casings for the air inlet andl gas outlet'conn'ecu tions, The drum e which is supported by means of'ball bearings h on the inner casing fis divided into several separate axial chambers bythe ribs The chambers are iilled with suitable heat transfer surfaces 7, such as wire gauzes, and holes are provided in the inside and outside Walls of the drum so that the gases and air can flow through the drum. The seals b and g, between the air and gas sides of the drum, consist of shoes of such a shape' that they slide on the outside and inside surfaces of the drum, and are oi' sufficient width to cover one complete chamberpf the drum. The shoes are pressed up against the surface of the drum by'push rods'lc and Z to which pressure is applied by means of flexible n'letalY tubes m and n which are iilled with oilV or other substantially incompressible fluid. The tubes are supported in the outsideV and'inside' casings c and f respectively.

l The tubes m and n, which are of similar construction, consist, in one form, of thin gauge tube of approximately oval section extending over the entire length of the shoes. The two ends`A of the tubes are tightly closedv in such a manner thatl the end" pieces do not affect the flexibility oi theA tube at" the position of 'theends of the shoes. If the ends 'areoi a typev which are incapable oiflexbility they can be connected to the iie'xible part of the tube by means of a bel lov/s connection or similar flexible joint.

In the operation ci the exchanger the drum is rotated by an external means'so that givenchambers ofthe drum will, at on'e'stage; be completely covered' by the external and internal shoes bear'- ing on thedrumV surfaces;

Referring now'toFigures 3, 4 and 5 which show the forces acting on the sho'eswhensuch a cham"- ber passes underneath them, inY Figure 3 the" one rib of the chamberhas just cleared the shoes onv the high pressure side ofthe exchanger, thereby exposing the chamber to the air pressure in this side. The pressure in the chamber, therefore, rises immediately to the air pressure and acts on the portion of the shoes covering the chamber.

As the drum rotates, for instance until it reaches the position shown in Figure 4, the portion of the chamber subjected to the high pressure air and exerting a high force on the shoes, is decreased while the portion of the neighbouring chamber', which has been exposed to the low pressure gas, and is, therefore, exerting a low force on the shoes, is increasing. Finally, the position shown in Figure 5 is reached in which the rib between these two chambers reaches the edge of the shoes on the high pressure side of the exchanger and no further influence is exerted on the shoes by the high pressure air. The force, P min, then acting on the shoes, is -given by the pressure of the low pressure gases. This cycle is th-en repeated as each chamber passes under the shoes.

Two periods o and p are illustrated in Figure 6. The maximum pressure occurs at the point q. Intermediate pressure is indicated by the line 1' and minimum pressure by the horizontal line s.

ln order that the shoes should provide a seal between the high pressure and low pressure parts of the exchanger, a force must be provided equal to that exerted by the air or gas pressure in the chambers under the shoes. If a constant external pressure is supplied, it would have t be equal to that necessary to counteract the greatest force P max exerted by the high pressure air, but as the pressure exerted on the shoe by the air or gases in the chambers decreased, the remainder of the constant external force would produce a very high friction force, so that considerable power would be required to drive the drum. This invention reduces the power required to drive the drum by inuencing the external pressure on the shoes to correspond with that being exerted by the air or gases in the chambers passing under the shoes.

The oil tubes m and n are, to this end, connected to a suitable control system and oil pressure supply, such as a pump, supplying a constant pressure to the system.

Referring to Figure 7, the control system consists of a pump q supplying oil, at a pressure which is maintained constant by a relief valve r to non-return valves whence the oil is divided in the flexible sealing oil tubes m and n. The oil in the tubes is also connected through orifice valves t back to the supply side of the non-return valves s.

In operation, oil of comparatively low pressure ows through the non-return valve during the part of the cycle when the force on the shoes is smallest, that is during the period when the force is P min (Figure 5), thereby filling the oval tubes m and n andbringing the shoes into contact with the drum e. As soon as the gas loading on the shoe increases, the tubes m and n tend to be compressed and displace oil back into the supply system. When the oil pressure in the tubes m and n rises above that set according to the relief valve r, the non-return valves s close and the oil pressure in the tubes then increases according to the applied force on the shoes. The orifice valves t are provided for the purpose of draining a small quantity of oil out of the system to allow for changes in volume of the tubes due to changes in dimensions of the casing and the drum under operating pressures and temperatures. When the non-return valve is closed, there is a bleed through the orifice valves from the tubes to the supply side of the non-return valves, and, therefore, the shoes can lift from the drum. The bleed is adjusted so that the degree of lift is very small, and does not materially affect the sealing properties.

We claim:

1. In a regenerative heat exchanger having an annular rotor with longitudinal partitions dividing it into ciroularly arranged matrix holding chambers and stationary elements for defining two separated passages for gas iiow through the rotor, the said chambers Ibeing open for gas flow between the said partitions both on the inner and outer peripheral surfaces of the rotor and in combination, sealing devices between the said stationary elements and the inner and outer peripheral surfaces of the rotor for sealing the two said passages from each other, each said sealing device comprising a sealing shoe for forming a seal between the two said passages, the sealing shoe having a rotor-engaging surface of arcuate extent suincient to cover a complete rotor chamber, means mounting ythe shoe for radial movement toward and away from the rotor, and means for holding the shoe in sealing engagement with the rotor, the last said means comprising a Aflexible tube, means supporting the tube and compressing it against the shoe for forcing the shoe toward the rotor, and means for keeping the tube full of incompressible liquid and varying the pressure of the said liquid in accordance with variation in gas pressure against the surface of the shoe as the rotor compartments pass the same, whereby the force exerted against the shoe by the said tube maintains a substantially constant and relatively small sealing pressure of the shoe against the rotor.

2. The combination according to claim 1, in which the said tube is a thin Walled metal tube.

3. The combination according to claim l, in which the means for keeping the shoe filled with liquid and varying the pressure of the said liquid comprises a source of supply of incompressible liquid under substantially constant pressure, a non-return valve connecting the tube to the said source of supply and a restricted orice also connecting the tube to the said source of supply.

4. The combination according to claim 3, in which the said tube is a thin walled metal tube.

ANDREW THOMSON BOWDEN. WALDEMAR HRYNISZAK PAUL KOLB.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 632,442 Byle et al Sept. 5, 1899 1,516,108 Ljungstrom et al. Nov. 18, 1924 1,772,210 Dale Aug. 5, 1930 1,843,252 Toensfeldt Feb. 2, 1932 2,013,499 Meckenstock Sept. 3, 1935 2,224,787 Horney Dec. 10, 1940 2,367,174 Rankin Jan. 9, 1945 2,446,620 Swallow et al Aug. 10, 1948 2,480,248 Karlsson et al Aug. 30, 1949 2,483,954 Weiss Oct, 4, 1949 FOREIGN PATENTS Number Country Date 543,093 Great Britain Feb. 10, 1942 620,602 Great Britain Mar. 28, 1949

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