US2977096A

US2977096A - Rotary regenerative heat exchanger

Info

Publication number: US2977096A
Application number: US724104A
Authority: US
Inventors: Ted C Evans
Original assignee: Air Preheater Co Inc
Current assignee: Alstom Power Inc
Priority date: 1958-03-26
Filing date: 1958-03-26
Publication date: 1961-03-28
Anticipated expiration: 1978-03-28

Description

A ML.

March 28, 1961 T. C. EVANS ROTARY REGENERATIVE HEAT EXCHANGER Filed March 26, 1958 United States Patent ROTARY REGENERATIVE H EAT EXCHANGER Ted C. Evans, Wellsville, N.Y., assignor to The Air P reheater Corporation, New York, N.Y., a corporation of New York Filed Mar. 26, 1958, Ser. No. 724,104

2 Claims. (Cl. 257-267) The present invention relates to rotary regenerative heat exchange apparatus and particularly to an improved arrangement for minimizing the thermo-elastic deformation of the structural parts of such apparatus.

A conventional regenerative heat exchanger includes a housing enclosing a rotor carrying heat absorbing material in the form of metallic plates that are first positioned in a hot gas stream to absorb heat therefrom and then moved into an air passageway to transfer the absorbed heat to air flowing therethrough. The rotor is surrounded by a housing having end plates formed with openings to provide for the flow of gas and air therethrough, and to preclude fluid flow through the clearance space between the rotor and housing in a way to bypass the heat transfer material it is customary to provide circumferential sealing means between the rotor and its surrounding housing. Also to prevent mingling of the two fluids, partitions which divide the rotor into sector shaped compartments are provided with radial seals that cooperate with the imperforate portions of the sector plates. To permit turning the rotor certain clearances are required between relatively movable sealing surfaces, however, because of the extreme temperature differentials that exist between the axially remote and diametrically opposite sides of the rotor, the rotor is subject to extreme thermal deformation that modifies the presumed clearances between the-relatively rotatable members.

Instead of attempting to attain more effective sealing means that maintains a constant clearance space, the present invention eliminates thermal deformation of the rotor so the sealing surfaces thereof are maintained within their predetermined relationship. p

The present invention therefore contemplates an improved structural arrangement for the rotor of'such heat exchange apparatus that substantially eliminates thermal deformation thereof.

The invention will be best understood upon considera tion of the following detailed description of an illustrative embodiment thereof when read in conjunction with the drawings in which:

Figure 1 is a sectional view of heat exchange apparatus constructed according to the invention. 7

a Figure 2 is a sectional view of the rotor as seen from 22 of Figure l. v

Figure 3 is a diagrammatic representation of thermal deformation usually present in therotor of a-rotary regenerative heat exchanger. I

In the drawings the numeral 10 designates a rotor having a cylindrical shell 12 divided into sector shaped compartments 14 by radial partitions 16 which connect to the rotor post 18 which is usually turned about its axis by a motor and reduction gearing-arrangement not here illustrated. The rotor compartments contain a regenerative heat exchange mass which first absorbs heat from hot gases entering the heat exchanger through a duct 20 from a combustor" or other source to .be dis-' charged after passing over the heat transfer "mass in 2,977,096 Patented-Mar. 28, 196 1 compartments 14 through a gas outlet duct 22. As the rotor turns slowly about its axis the heated heat exchange mass is moved into a stream of cool air admitted through a duct 24, and after passing through the heat exchange mass and absorbing heat therefrom, the then heated air is exhausted through an outlet duct 26 where it passes out to any predetermined point of usage.

A housing 28 enclosing the rotor 10 is provided with end plates 30 that are apertured to permit the flow of gas andair therethrough. In order that the stream of gas and air may not commingle, annular sealing means 32 are provided between the various ducts and the adjacent end faces of the rotor 10.

In a vertical heat exchanger in which the gas flows upward, in the manner disclosed in Fignlre 1, the rotor becomes dished as indicated in Figure 3 because of an essentially linear temperature gradient along the axial extent of the diaphragm. This distortion due to a differential in expansion varies the clearance spaces, between the rotor and the sealing means 32, in such a manner as to cause excessive leakage in some instances and excessive wear in other instances where the clearance space has been eliminated.

In accordance with the present invention the diaphragms 16 comprise cored or hollow members that are divided into axially spaced passageways by partitions 34 extending from the rotor post radially outward to a point spaced from the rotor shell 12 to provide axially spaced

passageways

36 and 38 in each diaphragm interconnected by an axial duct 42. The passageway 36 of each diaphragm is connected by means of a duct 44 to an annular cavity 56 in rotor post 18, and annular cavity 56 in turn is connected to inlet duct 20 by a port 46. Similarly passageways 38 are connected through ducts 52 to annular cavity 58 and port 54 to outlet duct 22.

Due to the ducting arrangement hot gas from inlet 20 is directed through port 46 to annular cavity 56 where it is channeled through circumferentially spaced ducts 44 to radial passageways 36. Since the gas in duct 36 exists at substantially the same temperature as that at inlet 20 it transmits heat to the cold or gas outlet side of each diaphragm 16 before flowing on through

passageways

42, 38 and 52 and port 54 to outlet duct 22.. By so flowing first through the cold end of the diaphragm the hot gases increase the temperature thereof and eliminate the excessive temperature gradient between the hot and cold ends of the diaphragm. By this expedient the diaphragms and depending rotor remain substantially fiat and the clearance spaces between the sealing means 32 and the adjacent surfaces of the rotor are maintained substantially constant. c

What I claim is:

1. Regenerative heat exchange apparatus or the like including a cylindrical housing having inlet and outlet duets for a heating fluid and a fluid to be heated, a rotor mounted concentrically within said housing including a cylindrical shell joined to a pivotally mounted rotor post by hollow diaphragrns to form sectoral compartments that carry heat transfer material, partition means in each diaphragm forming radial passagewaysadj-acent the inlet and outlet ducts connected at their radial outernecting each of said annular cavities to the radial passageways remote therefrom, and port means in the inlet and outlet ducts for'the heating fluid adapted to'permit communication with adjacent annular cavities whereby aiportion of the heating fiuid fl owing through the rotor iszdirected through the hollow diaphragm.

' I 2. Regenerative heat. exchange apparatus or the i including a cylindrical housing having inlet and outlet ducts for a heating fluid and a fluid to be heated, a rotor mounted concentrically within said housing including a cylindrical shell joined to a pivotally mounted rotor post by hollow diaphragms, means dividing each hollowdiard passageways in the diaphragms lying adjacent the outlet duct for the heating fluid at substantially the same temperatures as presented at the inlet duct therefor.

References Cited in the file of this patent UNITED STATES PATENTS 2,680,598 Trulsson et a1. June 8, 1954 FOREIGN PATENTS 671,717 Great Britain May 7, 1952 1,018,902 France Jan. 14, 1953