Rotor Construction

The present invention relates to a rotary regenerative heat exchanger including a rotor having a series of sector-shaped compartments of heat absorbent material that extends radially outward from a central rotor post. The rotor is rotated about its axis to simultaneously subject it to a flow of hot and cool fluid whereby the rotor may absorb heat from the hot fluid and transfer it to the cooler fluid flowing therethrough. More specifically, the invention relates to an arrangement by which the rotor construction of a regenerative heat exchanger is greatly simplified while the operational characteristics are greatly enhanced to produce a much improved heat exchanger at lower cost.

This invention therefore provides for a specific arrangement by which a rotor for a regenerative air preheater is greatly simplified while simultaneously the performance thereof is enhanced to provide improved resistance to the lateral flow of fluid between adjacent compartments. This arrangement is effected by reducing the number of radial diaphragms required for rotor support and replacing said structure with imperforate sheets that are arranged radially to preclude the lateral flow of fluid.

Other objectives and the particular means of operation will become more apparent from the specification and the accompanying drawing in which:

FIG. 1 is a perspective view of a rotor for a regenerative air preheater, partially broken away to show the invention,

FIG. 2 is a perspective view of a rotor for a regenerative air preheator of a slightly modified form, and

FIG. 3 is a perspective view of the rotor shown by FIG. 2 as enclosed in a simplified form of housing.

The arrangement illustrated by FIG. 1 of the drawing shows a rotary regenerative heat exchanger having a rotor comprised of a post 12 supported on suitable bearings carried by support plates 16 that extend diametrically across an opening in end plates 18 to form spaced openings for a heating fluid and for a fluid to be heated. The end plates 18 are carried at opposite ends of an annular housing 22 that encloses the rotor containing the mass of heat absorbent material.

The rotor is formed by a series of partitions or diaphragms 24 that are axially welded at one end to the rotor post 12 and adapted to extend radially outward to form a series of sectorial compartments therebetween that hold the heat absorbent material 38 that absorbs heat from hot gases passing through duct 20 and imparts the heat to cool gases passing through duct 21. The outer wall of the rotor comprises a circular shell formed from a series of arcuate segments 28 between diaphragms and having a radial flange 32 that is secured to the ends of adjacent diaphragms by bolts 34. The rotor is then rotated about its axis by any conventional prime mover such as motor and reduction gear 35 whereby the heating fluid and the fluid to be heated are alternately directed axially through the heat absorbent material of the rotor.

The axially remote edge of each radial partition 24 or an imperforate bar affixed thereto is adapted to rub against or in closely spaced relation with the adjacent face of end plate 16 whereby upon rotation of the rotor there can be little or no lateral flow between ducts carrying a high pressure fluid to be heated and a lower pressure heating fluid.

Inasmuch as the efficiency of operation of a heat exchanger as above defined is dependent to a great extent upon the efficiency with which the heating fluid and the fluid to be heated are maintained in their own independent passageways, it would appear that the efficiency of operation of the device is directly dependent upon the number of equally spaced radial diaphragms 24 that might be welded to the central rotor post 12 and the sealing relationship that results therefrom. However, it is also known that construction costs rapidly increase with the amount of welding required during construction of the unit. Therefore, construction costs would increase as the number of radial diaphragms would be increased . However, according to this invention there is provided a rotor arrangement for rotary regenerative heat exchanger requiring minimal amounts of welding so that the costs of construction are substantially reduced while operational advantages which result from the presence of additional diaphragms are, by contrast, greatly increased.

According to this invention a minimum number of diaphragms 24 are first welded radially to a central rotor post 12. The number of diaphragms used is not critical, but it is generally understood that small rotors require fewer fixed diaphragms than do units of a larger size so that, for example, only four to six diaphragms are required for a small sized preheater. To compensate for a reduced number of welded diaphragms, the heat absorbent material of each compartment includes several juxtaposed imperforate heat absorbent sheets 36 that are arranged radially at the approximate mid-point of each sectorial compartment. The sheets 36 are adapted to extend radially outward to segments 28, a distance somewhat less than the length of each diaphragm 24, while they are adapted to extend axially into close proximity with the imperforate surface of the adjacent end plate so as to preclude fluid flow therebetween. The sectorial space at each side of the parallel sheets is filled with an arrangement of radial or transverse heat absorbent material 38 that permits the axial flow of fluid through the compartments of the rotor, whereby said material is in a position to absorb heat from the hot fluid and then give it up to the fluid to be heated.

In a slightly modified form of the invention as shown in FIG. 2, the radial element sheets 36 do not extend axially to the plates 16 at the ends of the rotor. Instead, a radial sealing bar 42 in axial alignment with sheets 36 is welded to the rotor post and to the rotor shell in axial alignment with one or more of the sheets 32 whereby together they will form a barrier for the transverse flow of fluid.

An arrangement by which a rotor of the type shown by either FIG. 1 or FIG. 2 may be enclosed in a simplified cylindrical housing is shown in FIG. 3 where leakage of one fluid to the other is precluded by maintaining at all times the edge of a diaphragm 24, radial element 36 (FIG. 1), or bar 42 (FIGS. 2 and 3) in close proximity with the inner face of center beam 16.