US2540733A - Recovery of pressure fluid in heat exchangers - Google Patents

Description

Feb. 6, 1951 s. HoLM 2,540,733

RECOVERY 0F PRESSURE FLUID IN HEAT EXCHANGERS Filed April 10, 1948 2 Sheets-Sheet l Patented Feb. 6, 1951 YRECOVERY OFPRESSURE FLUID IN HEAT EXCHANGERS Sven Hohn, Wellsville, N. Y., assigner to The Air Preheater Corporation, New York, N. Y.

Application .April .10, 1948., Serial'No.. 20,220

The present invention relates to -heat exchange apparatus and particularly to improvements in apparatus such as regenerators for exchanging heat between the working medium and waste gases in a gas turbine cycle.

One form of heat-exchange apparatus that may be employed in gas Yturbine cycles is the familiar rotary regenerative heat'exchanger wherein a mass of heat storing -material'is carried in a rotor and-first exposed to hot gases directed through kthe latter and then subsequently `positioned in the pathof the stream of airor other umedium to be heated. However, because `the medium to be heated in a gas turbine cycle is compressed air, the rotor 4of a regenerative heat exchanger entrains part of the high pressure air when Vthe rotor leaves the air passages, and 'upon entering the low pressure gas compartment the trapped air expands into the gas. This results in losing a large portion of the work required to compress the air because one rotor -ffull of compressed air is llost for `each turn of the rotor.

It is the object of the present invention to provide rmeans for substantially reducing the amount of compressed air lost due Vto entrapment 'in the 3 Claims. (Cl. 257-6) rotor and at the same time reducing the direct leakage between the high pressure airstream and the low pressure -gas stream by providing zones of intermediate pressure between the two'stream's. The invention will be best understood upon consideration of the following detailed description of an illustrative embodiment thereof when read in conjunction with the accompanying drawing in which:

Figure 1 is a sectional elevational view taken along the axis of a'rotary heat exchanger embodying the present invention; l

Figure 2 is a partial vend View of the apparatus shown in Figure l;

Figure 3 is a fragmentary elevational view illustrating the means for turning the rotor;

Figures 4 and 5 are transverse sectional views through the rotor on the correspondingly desigthe centrally located circular wall I4. Inwall I4 there are formed ports I5 individual to each of the compartments I2 for admitting and discharging the air to be heated as well as the heating gas. In fact the wall I4 is made up mainly of webs I6 (Figs. 4, 5) located between the ports I5 and extending between the circular bands I1, I8 (Fig. l) near the ends and the band 20 at the center of the rotor. Located in the spacedened centrally of the yrotor by the ported wall I4 are a pair of distributing valves 2l, 22 which resemble plug valves in that each is formed with a passage 23 extending axially from thev open outer end 24 of the core to near the inner imperforate end 25. A large port 26 (Figs. 3, 4) in the side wall of the core is of great enough circumferential 'extent to simultaneously be in communication with a majority of the rotor compartments I2 for the admission or discharge of heating medium.

Spaced `circumferentially from either edge of the gas orifice 26 in the valves 2l, 22 by the imperforate ligaments 28 of the side wall of the core is an air port 30 opening into the lune shaped passage 32 formed by the axially extending arched partition 33 located in the valve at the side of its axis opposite the gas port 26. At opposite ends of the rotor axis the two distributing valves 2|, 22 are in direct communication with the inlet and outlet ducts 34 and 35 for gas. The air passages 30 in the distributing valves extend axially of the valves and are continued beyond the ends of the rotor as passages 36 formed within the ducts 34 and 35 at one side of their axes by the partitions 3l. The air is supplied to and taken from the passages 36 through ports 38 in the outer walls of the ducts 3'4, 35 which are in communication with the air inlet and outlet pipes 40 and 4I respectively. The circular bands il, I8 forming either end of the central wall III of the rotor and its middle band 2U 'bear against flanges 45-48 on the plugvalves which serve as sealing surfaces between the rotor and the distributing valves.

Theend plates at of the ret-or have mounted thereon discs 5i which ride upon the rotor supporting rollers 52 that are journalledin brackets 53 ,mounted on the supporting beams 5d that extend parallelly along opposite sides of a pit 55 that receives the lower portion of the rotor It. fit one end of the roter the supporting disc 5i (Fig. 3) has attached thereto a gear 5t meshing with a drive gear 5l driven by a motor 58.

The various compartments i2 of the rotor are divided into two parts designated IEA and I 2B inner wall I4 of the annular rotor and extending in the plane of its central axis outwardly to a point short of the outer wall I3 of the rotor so that a passage 43 is provided placing the two partments I2A and then through the end pas` sage 43 and in a radially inward direction through the compartment section |2B and through the port 26 of the valve 22 into its central passage and axially of the latter to the outlet duct 35. The compartments I2 contain heat storing material which may be in the form of metal plates or any other appropriate type spaced to permit fluid The heating gas flows outflow and capable of picking of heat from hot gases and storing it temporarily so that it maybe imparted to the air or other fluid. The air to be heated compressed to say, 60 lbs. passes from the supply duct pipe 4Q at the lower left of Fig. l through the stationary passage 355 in duct 35 into the alined lune shaped passage 32 of the valve 22 and through its side wall port 35 into the parts |2A of the several compartments I2 that are in alinement therewith. In the same manner as the gas, the compressed air hows in a radially outward direction through the compartment section IEA and in a radial inward direction through the compartment section IZB, being discharged into the passage 32 oi the other valves 2| and iiowing axially through the alined passage 36 in duct 34 to be discharged finally through the outlet pipe 4|. Instead of being actually cylindrical the rotor has tapered ends so as to provide a constantly proportional crosssectional area to the volume of flow in sections |2A and also to provide a large irontalarea for minimum pressure loss as the gasl and air enter the rotor.

As mentioned previously, the air which remains in any of the compartments I2 of the rotor as they pass from communication with the air ports 3!! in the distributing valves across the imperforate portions 28A of thesevalves is trapped and when the compartments become alined with the gas port 26 the air expands into the stream of gas with resultant loss kof the work required for air compression. To avoid this loss of compressed air the distributing valve 22 at the high pressure end of the exchanger (left in Fig. l) is formed with one or more passages (two being shown in Fig. 5) which extend back from aY position on the valve 22 beyond the leading imperforate portion 2SA to compartments I2 which have not yet come into registration with the air port 36 in the valve. These passages Si] and 6| are formed by arced plates E2 extending axially of the valve 22 bei tween the side edges of imperforate portions 28, 23A of the valve located at either side of the air port 3E). Thus while several compartments lI2 (two as shown in Figs. 4 and 5) are in communication with the air supply port 3i! in the valve 22, a compartment circumferentially spaced from this group in the direction of rotation and designated I2C in Fig. 5 is in direct communication through the passage 68 with another compartment I2D which has not yet moved into registration with the air port 30. When more than one return ow passage is provided, other compartments such as |2E still further forwardly of the i air port 30 and one |2H rearwardly thereof are in communication with each other through the passage 6|.

Thus, as the rotor turns, hot gas first flows through the greater number of compartments I2 in the rotor and imparts heat to the heat storing material therein. Compressed air flows over already heated material in the lesser number of compartments I2 then in registration with the ports 3U of the valves 22 and 2| and picks up heat from the packing. As each compartment leaves the air stream, compressed air is trapped therein as its port I5 is closed off by the imperforate portion 2BA located on the valve forwardly of its air port 3D. As. the rotor turns further the compartments in which air has been trapped then register one by one with the passage 6|) and the air which is at high pressure flows through "the latter as from the compartment I2C into the compartments I2D until pressure is equalized. Further turning of the rotor brings these partly evacuated compartments into the position designated |2E in Fig. 5 and places each in turn in communication through ythe passage 6| with the compartment |2II located further rearwardly beyond the compartment I2D and therefore at a lower pressure. This compartment I2H is at relatively low pressure since it has just moved from communication with the gas port 26 in which the pressure may be -of the range of. 15 lbs. Here also pressure equalization takes place between the two sectors |2E and I2H and a gradualldecrease in pressure is obtained as shown diagrammatically in Fig. 6. It will also be apparent that direct leakage between the air side of the heat exchanger and the gas side is reduced because the air volumes returned to compartments I2D and |2H are at pressures somewhat higher than in compartments rearwardly thereof. Thus, each forms a pressure zone creating a, fluid seal between the high pressure air stream and the Vlower pressure gas stream. A substantial portion of the air carried Ybeyond the air port 30 is returned to sectorial compartments in which a lower pressure exists since they have just moved from the gas stream and thus this amount of air is carried back into the main air stream. The heat imparted into this volume of air is recovered as is the work of compression;

The distributing valves 2|, 22 have their sealing surfaces 45, 48 and 45, 41 urged into contact with the sealing surfaces |8,-2U and I1, 25 on the rotary casing IIJ by air pressure acting against the piston 1|) and end Wall 1| of a piston cylinder 12 which is connected by a pipe 1S with the pressure sair inlet duct 4U. Force applied against the piston '10 draws the valve 2| to the left by means of the rod 14 which extends freely through the orifice 15 in the end wall 25 of the valve 22. It will be noted that the cylinder 12 is integral with the gas outlet duct 35 and hence the reaction of the air under pressure in the cylinder 22 against the end wall 1| forces the outlet pipe 35 to the right and the latter, engaging the outer end of the valve 22, presses the surfaces 45 and 41 thereof into contact with the sealing surfaces I1, 20 on the inner circular wall of the annular casing.

What is claimed is:

1. In heat exchange apparatus having a cylindrical casing divided by radial partitions into circumferentially spaced sector shaped compartments having inlet and outlet means for admission and discharge of fluids to flow over heat exchange material contained in said compartments; fluid distributing means having fluid admission and discharge ports in communication with a group of contiguous compartments for flow of a heating fluid therethrough and other ports circumferentially spaced and separated from the ports for said first fluid for flow of a fluid to be heated in communication with another group of adjacent compartments that are spaced circumferentially of said casing and separated from said ilrst group of compartments; means for rotating said casing and fluid distrib uting means relatively to each other for passing said two fluids in succession through each of said compartments; and means forming a passage disposed between said two sets of ports adapted to register with said compartments for placing a compartment circumferentially located beyond the admission port for said uid to be heated, in the direction of rotation, in communication with a compartment circumferentially located in advance of said port for returning volumes of the fluid to be heated from said first compartment to said other compartment upon movement of said one compartment from registration with the port for said fluid to be heated into registration with said passage.

2. In heat exchange apparatus; an annular casing formed by spaced circular wall members bridged by end closures; radial partitions dividing the interior of said casing into sector shaped compartments; inlet and outlet Vmeans for fluid admission formed in the inner circular wall of said casing for the flow of uids over heat exchange material contained in said compartments; fluid distributing valve means fitting the central space of said annular casing having a fluid distributing inlet and outlet ports for a heating fluid in simultaneous communication with a group of contiguous compartments and other ports spaced circumferentially from said rst ports for a fluid to be heated in communication with another group of adjacent compartments that are spaced circumferentially and separated in said casing from said first group of compartments; means for rotating said casing and valve means relatively to each other for passing said two fluids in succession through each of said compartments; and means forming a passage located in said valve means between said ports for placing arpair of compartments respectively located at opposite sides of said second group and disposed intermediate said two groups at either side of said second mentioned ports in communication With'each other for returning volumes of said fluid to be heated from one compartment of said pair to the other compartment upon movement of said one compartment from registration with said other port of said valve means.

3. In heat exchange apparatus having a casing divided internally by partitions into compartments having inlet and outlet means for admission and'discharge of fluids that flow over heat exchange material contained in said compartments, fluid distributing means movable relatively to said compartments having fluid admission and discharge ports in communication with a group of contiguous compartments for flow of a heating fluid therethrough and other ports spaced and separated from ports for said rst fluid for flow of a fluid to be heated in communication with another group of adjacent compartments that are spaced in said casing and separated from said ilrst group of compartments; means for moving said casing and fluid distrib uting means relatively to each other for passing said two fluids in succession through each of said compartments; and means forming a passage disposed between said two sets of ports adapted to register with said compartments for v'placing a compartment located beyond the admission port for'said uid to be heated, in the direction of movement, in communication with a compartment located in advance of said port for returningJ volumes of the fluid to be heated from said firstl compartment to said other compartment upon relative movement of said one compartment from registration with the port for said fluid .to be heated into registration with said passage.

SVEN HOLM.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,820,199 Riley Aug. 25', 1931 1,843,252 Toensfeldt Feb. 2, 1932 FOREIGN PATENTS Number Country Date 8,273 Great Britain of 1906 280,083 Germany Nov. 9, 1914

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