US3327770A - Rotary regenerative heat exchangers - Google Patents

Description

June 27, 1967 H. BRANDT 3,327,770

ROTARY REGENERATIVE HEAT EXCHANGERS I Filed 0012. 15, 1965 2 Sheets-Sheet l INVENTOR HERBERT BRANDT United States Patent 3,327,770 ROTARY REGENERATIVE HEAT EXCHANGERS Herbert Brandt, 5961 Rothernuhle uber Olpe, Westphalia, Germany Filed Oct. 15, 1965, Ser. No. 496,558 Claims priority, application Germany, Oct. 24, 1964,

4 Claims. (Cl. 165-9) This invention relates to rotary regenerative heat exchangers of the kind which includes a substantially cylindrical regenerative heat exchange member, hereinafter referred to as a regenerator, which is subdivided by radial partitions and by concentric cylindrical partitions to form chambers each of which receives a pack of plates, the packs of plates in all of the chambers providing the heat exchange mass of the regenerator.

The heat exchanger also includes means for leading hot gas to one axial end (the hot end) of the regenerator so that said gas will flow through the said mass and give up its heat thereto, the gas being withdrawn from the other axial end of the regenerator (the cold end) as cooled gas. There is also provided means for supplying cold air to the cold end of the regenerator so that said air will flow through the said mass, in counter-flow to the gas, and take up heat from the mass, the air being withdrawn from the hot end of the regenerator as heated air.

In some cases the regenerator rotates about its axis, Whilst the means for supplying said cold air and hot gas to the regenerator, and for withdrawing the cooled gas and heated air from the regenerator are stationary; in other cases the regenerator is stationary whilst the said air conducting means rotate about the projected axis of the regenerator. In either event, there is relative rotation between the regenerator and the air conducting means.

The air inlet and air outlet conducting means each includes a hood which is open at the end adjacent the axial end surface of the regenerator so that air may flow into and out of the regenerator from and to the said conducting means, and the said hood includes, around the periphery of the said open end, sealing means which slide over the end surfaces of the regenerator, during said relative rotation, to prevent undue leakage of air from the regenerator. The sealing means may make actual contact with the end surface of the regenerator, or there may be a gap of a predetermined dimension therebetween. Usually the said opening at the end of the air hood is of sector shape so that at any one period of time it covers a sector of the end of the cylindrical regenerator, and thus, during said relative rotation, sweeps over the whole of the end surface of the regenerator.

A frame around the periphery of the said open end of the air hood carries sealing strips which provide the actual sealing means, and the said frame is pressed towards the regenerator end surface by spring means which are adjustable to regulate the pressure of the sealing strips on to or towards the regenerator end surface.

The sealing strips usually are made of soft cast iron, and, at the outermost and innermost circumferential walls of the regenerator, ride upon substantially wide flanges on the edges of the said walls, and consequently at those places there is comparatively little wear of the sealing strips or of the said flanges. However, the radial partitions and the internal circumferential or arcuate partitions which form the chambers in the regenerator are comparatively thin, and consequently the movement thereover of the substantially radial sealing strips causes a comparatively large amount of wear at the edges of said partitions.

The object of the present invention is to provide improvements in the radial partitions and in the internal circumferential or arcuate partitions of the regenerator whereby to minimise wear of the edges thereof during relative rotation between the regenerator and the air conducting hoods, and also to improve the bedding-down of the said edges in the initial operating stages of the regenerator.

According to this invention, a partition for use in the forming of chambers in the regenerator of a rotary regenerative heat exchanger, each of the said chambers being adapted to contain a mass of heat exchange material, comprises a metal plate on to edges of which plate are superimposed at least two layers of metal, the metal layer contiguous with the metal plate being formed of hard metal whilst the outermost metal layer is formed of soft metal, the said edges of the plate being those edges which are to be disposed at the axial ends of the regenerator.

Referring to the accompanying drawings:

FIG. 1 is a diagrammatic sectional elevation of a rotary regenerative heat exchanger, wherein the regenerator is stationary.

FIG. 2 is a plan view, that is looking along the axis of the regenerator, of part of the regenerator and of the sealing strips on the sealing frame around the opening of an air duct;

FIG. 3 is a sectional elevation taken on line IIIIII in FIG. 2;

FIG. 4 is a fragmentary cross-section taken on lines IV-IV in FIGS. 2 and 3.

FIG. 5 is a side elevation of a portion at an edge of a regenerator partition made according to this invention; and

FIG. 6 is a cross-section taken on line VIVI in FIG. 5

Referring to FIG. 1, a casing 11 provides at its top end a chamber 12 into which hot gases, from a suitable source, are admitted by means not shown, and the casing also has at its bottom end a chamber 13 from which the said gases, after giving up heat to the regenerator hereinafter referred to, are withdrawn by means not shown.

Between the chambers 12 and 13 there is a stationary cylindrical regenerator 1 1 which is provided with plates or tubes which provide a mass 15 which forms passages which are open at the ends of the regenerator. Thereby, the hot gas from the chamber 12 may flow through the mass 15, give up heat to the said mass, and then pass on, as cool gas, to the chamber 13.

Within the chamber 12, and eo-axial with the regenerator 14, there is the open end 16 of an outlet air duct 17, whilst within the chamber 13 there is a similar open end 18 of an inlet air duct 19.

Below the generator 14 there is an air duct member 20 which has an axial neck 21 which is disposed in rotatable, air and gas tight, engagement with the end 18 of the air duct 19, and has ducts 22 and 23 which have sector-shaped openings 22a and 23a, respectively, at their upper ends near to the bottom end face of the regenerator 14.

Similarly, above the regenerator 14- there is an air duct member 24 which has an axial neck 25 which is disposed in rotatable, air and gas tight, engagement with the end 16 of the air duct 17, and has ducts 26 and 27 which have sector-shaped openings 26a and 27a, respectively, at their lower ends near to the upper end face of the regenerator 14.

The bottom openings 26a and 27a of the ducts 26 and 27 are opposed, in the axial direction of the regenerator, to the upper openings 22a and 23a of the ducts 22 and 23, respectively, that is, the openings 26a and 27a of the ducts 26 and 27 are disposed in mirror-image manner to the openings 22a and 23a of the ducts 22. and 23, so that air emitted from the ducts 26- and 2-7 will pass through the regenerator and into the ducts 22 and 23.

The two air duct members 20 and 24 are both secured to a driving shaft 28 which passes vertically through an axial opening 29 in the regenerator 14 to provide a rotation drive to the duct members in known manner.

'It is desirable that there be as little leakage of fluid as possible between the air ducts 22, 23, 26, 27 and the gas chambers 12, 13 and for this purpose sealing assemblies 30 are disposed around the peripheries of the openings 22a, 23a, 26a and 27a of the ducts 22, 23, 26, 27.

The sealing assemblies 30 comprise a frame 31 which is provided with sealing strips 32, 33 which slide over the axial end surfaces of the regenerator during rotation of the air duct members. The sealing frames 31 are pressed towards the end surfaces of the regenerator by spring devices 40 which are adjustable to regulate the said pressure.

As shown in FIG. 2, the sealing strips 32 and 33, when mounted on the sealing frame, have the shape of a quadrant. When the air ducts rotate relatively to the regenerator 14, the arcuate sealing strips 32 slide over the inner circumferential flange 34 and the outer circumferential flange 35 of the regenerator. As the sealing strips 32 are made of soft cast iron, and the flanges 34 and 35 are comparatively wide, there is comparatively little wear of the said flanges. If the sealing strips 32 and 33 do wear, they can be replaced comparatively easily.

The radial sealing strips 33 slide laterally over the edges of the radial and circumferential partitions 36 and 37 of the regenerator 14, which partitions form the chambers 38 which contain the mass of heat transfer material. As the said partitions 36 and 37 are comparatively thin, they are Worn down comparatively quickly.

A fragment of an improved partition 36 made according to one embodiment of the invention is shown in FIGS. and 6.

The partition comprises a mild steel plate 39 on to an edge of which is first attached a layer 41 of hard metal and then an outer layer 42 of soft metal. Both edges of the plate which are at the axial ends of the regenerator are so formed. The 'hard metal layer 41 may be of steel having a Brinell hardness of at least 50 more than the soft metal layer 42 which also may be of steel; for example, the hard layer 41 may have a Brinell hardness of 150 whilst the soft layer 42 has a Brinell hardness of 90. The thickness 43 (that is, in the axial direction of the regenerator) of the hard metal layer may be 4 mm., whilst the thickness 44 of the soft metal layer may be 6' mm. when initially attached to the plate 39. Before the plate 39 is assembled into a regenerator there may be deviations (which in some cases may amount to 2 mm. or 3 mm.) in the outer face of the soft layer 42 from an exact level, due to inaccuracies in manufacture; therefore, the soft layer 42 is machined down to approximately 4 mm. so as to give a combined thickness 45 of the two layers 41 and 42 measuring approximately 8 mm. Even so, the machined surface of the soft layer 4-2 may deviate approximately 0.5 mm. from an exact level.

When the plate 39 has been assembled, with other similarly formed plates, in the regenerator to provide the partitions 3-6 and 37 (FIGS. 2-4), and during the initial running-in or bedding-down period of the heat exchanger (or of a new or repaired regenerator 14), the rotary movement of the radial sealing strips 33 across the edges of the radial partitions 36 and along the edges of circumferential partitions 37 will gradually remove some of the soft metal of the edge layer 42 until a surface is produced to leave the combined thickness 46 of the two layers 41 and 42 measuring approximately 5 mm.; however, this bedding-down process will also take care of any differences (which may amount up to 1.5 mm.) in the sealing gaps between the radial sealing strips 33 and the 4 edges of the partitions 36, 37, which differences may be caused by thermal expansion during operation of the heat exchanger, with the result that after such bedding-down there are substantially no variations in the dimensions of the said sealing gaps.

During the said bedding-down process, and subsequent thereto if necessary, the spring pressure devices 4% over the whole of the area of each sealing frame 31 are adjusted to allow an optimum movement thereof during normal operation of the heat exchanger.

During the said bedding-down process the soft metal layer 42 becomes further bound on to the hard metal layer 41, and indeed some of the soft metal from the layer 42 may be pressed into pores of the hard metal in the layer 41 or be otherwise fused thereto, so that a substantially antifriction surface is produced (it being known that an intimate combination of hard and soft metal produces a good antifriction material). Further wear of the edges of the partitions thereby is minimised.

The layers of hard metal (41) and soft metal (42) may be applied to the plate 39 in any suitable manner. Preferably, however, the layers are applied by welding the appropriate metal on to the plate. The welding on of the metal may be effected by the use of appropriate filler rods or wires or powdered metal.

A suitable manner of welding the metal on to the plate 39 is shown in FIG. 6. Therein, copper plates 47 are applied to both sides of the plate 30 to form a channel into which the metal layers 41 and 42 are built up by welding. The copper plates 47 are removed from the plate 39 after the layers 41 and 42 have been formed.

There may be more than two layers of metal Superimposed on the edge of the plate 39, at least the layer contiguous with the plate being formed of hard metal whilst at least the outermost layer is formed of soft metal.

The invention may be applied to the renovation of worn partitions.

What I claim and desire to secure by Letters Patent is:

1. A partition forming chambers in the regenerator of a rotary regenerative heat exchanger, each of the said chambers being adapted to contain a mass of heat exchange material, comprising a metal plate on to edges of which plate are superimposed at least two layers of metal, the metal layer contiguous with the metal plate being formed of hard metal whilst the outermost metal layer is formed of soft metal, the said edges of the plate being those edges which are to be disposed at the axial ends of the regenerator.

2. A partition according to claim 1 characterised in that the said layers of metal are superimposed on the edge of the plate by built-up welding of appropriate metal.

3. A partition according to claim 2 wherein the appropriate metalfor a layer is provided in the form of a filler rod.

4. A partition according to claim 2 wherein the appropriate metal for a layer is provided in the form of powder.

References Cited UNITED STATES PATENTS 2,517,512 8/1950 Tigges et al. 16-59 2,674,442 4/1954 Hammond et al. 16'59 3,010,704 11/1961 Egbert 9 3,027,144 3/1962 Hess et al. 165-9 3,208,509 9/1965 Bloss et al 165-9 ROBERT A. OLEARY, Primary Examiner.

A. W. DAVIS, Assistant Examiner.

Claims (1)

1. A PARTITION FORMING CHAMBERS IN THE REGENERATOR OF A ROTARY REGENERATIVE HEAT EXCHANGER, EACH OF THE SAID CHAMBERS BEING ADAPTED TO CONTAIN A MASS OF HEAT EXCHANGE MATERIAL, COMPRISING A METAL PLATE ON TO EDGES OF WHICH PLATE ARE SUPERIMPOSED AT LEAST TWO LAYERS OF METAL, THE METAL LAYER CONTIGUOUS WITH THE METAL PLATE BEING FORMED OF HARD METAL WHILST THE OUTERMOST METAL LAYER IS FORMED OF SOFT METAL, THE SAID EDGES OF THE PLATE BEING THOSE EDGES WHICH ARE TO BE DISPOSED AT THE AXIAL ENDS OF THE REGENERATOR.

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