US2037490A - Rotary heat exchanger - Google Patents

Description

' April 14, 1936.

H. VORKAUF ROTARY HEAT EXCHANGER Filed Jan. 9, 1953 3 Sheets-Sheet l .IZZarzzey.

April 1936. H. VO RKAUF 2,037,490

' ROTARY HEAT EXCHANGER Filed Jan. 9, 1933 3 Sheets-Sheet 2 April 1936- H. VORKAUF 2,037,490

ROTARxf HEAT EXCHANGER Filed Jan. 9, 1933 3 Shets-Sheet 3 Ilia: e.

Patented-"A 14, 1936 PATENT OFFICE 2.037.490 ao'rsay nan-r nxcmmcna Heinrich vomurf. Berlin, Germany, assignor to Herpen and Vorkanf, Ingcnieure, Berlin, Ger- I Application January 9, 1933, Serial No. 650,817

' In Germany January 9, 1932 19 Claims. (01. 251-235) This invention relates to steam or vapor generators of the revolving type, particularly such generators as rotate at sumciently highspeeds to be directly coupled to a turbine or the like. 1

Such an arrangement has been disclosed-in my copending application Ser. No. 611,849, flied May 17th, 1932 which has matured into Pat. No. 1,994,009.

The generator may be flred by any fuel such as gas, oil, coal, or powdered coal. Particularly in the latter case, it is unavoidable that a considerable amount of ashes and perhaps unbumt fuel is carried by the hot combustion gases over to the heat absorbing elements. In the generator according to my invention, heating surfaces revolve through the hot gases and cause a rotating movement also of the latter. The hot combustion gases are very light compared to the weight of the particles of ash or unbumt fuel which are carried along by the gases. This dust is therefore thrown outwards by centrifugal forces as soon as the gas with the therein suspended solid or molten particles revolves at suflicient speed. The dust can be collected in suitably arranged pockets or the like and removed.

Whereas in the usual steam generator or other combustion apparatus separate dust precipitators are arranged, which are entered by the gases after they have left the generator, an arrangement according to my invention combines vapor generator and dust preclpitator in one piece of equipment. A further advantage of my invention is that the dust or fly ash is removed from the gas while it is still very hot. At high temperatures the specific weight of the combustion gas is small compared to the weight of the dust or ash particles; this materially facilitates the removal of the dust by centrifugal action.

Preferably the combustion gases pass through my vapor generator in a direction substantially parallel to its axis of rotation. The heating elements apply a circular component of movement to the gases, so that each gas particle travels along a screwline through the apparatus. The

& dust particles.are thrown outwards in a radial direction and are collected in receptacles arranged for this purpose. To remove the dust from these receptacles, a certain amount of the celerate the removal and to arrange for a pneumatic further transportation of the ash at the same time. The gas is under a considerable presf sure at the circumference-of the revolving part of my generator and also in the pockets for receivgas is allowed to pass through the pockets to acing the fly ash, due to the high rotational speed; this pressure can advantageously be used for the removal and transportation of the ashes. The gas carrying the ash has still a high temperature and heat content, and it is desirable to conduct 5 these gases through a heat exchanger and transmit their heat e. g. to the fluid for feeding the generator or/and to the air for combustion.

.The fact that the main heating surfaces of. my boiler are revolving can also be utilized in 10 another way. If, e. g., the revolving evaporator is arranged at the bottom of a combustion chamber fired with pulverized fuel, unbumt material will fall on the revolving heating surfaces and are thrown back againand again into the com- 15 bustion chamber, thus securing a perfect combustion. How often the particles may be thrown back into the hot flame depends on the length of the combustion chamber and the revolving heat absorbing elements. The particles may also be 20 conducted into a collecting pocket from which they are removed.

At high speeds, the centrifugal forces set up high stresses in the construction materials of the heat transmitting surfaces; the heat absorbing 25 parts of the generator as well as the supply and discharge tubes for the feed water and steam respectively must be of a design suitable to withstand these stresses.

Designs have been conceived in which the gen- .80 e'ratin'g'or heat absorbing parts consist of rotating discs and a plurality of individual thimbles disposed on a hollow shaft. In such arrangements, the liquid to be evaporated enters from the center into the evaporating elements, and the 35 generated vapor must return through the same elements to the center, whereby feed fluid and vapor circulate in opposite directions to each otherthrough the same elements and obstruct each others free flow. According to the present invention, the evaporating elements are fed from one side with the fluid, and the vapor or mixture of fluid and vapor is withdrawn at the other side. To accomplish this, the evaporating elements are connected on their outer ends by means of headers, tubes. or the like. In the center the evaporating elements are either directly connected to the center conduit or they are connected to intermediate conduits arranged substantially around the center piece, shaft or conduit. The evaporating elements are preferably radially arranged with respect to the center piece, so that the materials are stressed parallel to the center line of the elements, and the centrifugal forces caused by 56 the outer connecting headers are absorbed by the spoke like evaporating elements.

It is desirable to form groups of evaporating elements by suitable connection of the elements to the headers at the circumference and at the center of the apparatus. These groups of radial elements should be parallel to the rotating axis of the device and may be inserted in grooves on the connecting headers which are also in an axial direction.

This invention further relates to arrangements for the supply of the fluid to and the withdrawal of the fluid, fluid-vapor mixture, or vapor from the heating elements.

- The design of a revolving vapor or steam generator according to my invention is suitable for high internal pressures and particularly adapted to withstand great stresses set up by centrifugal forces. Although it can be used for steam or any vapor, it, is especially well suited for evaporating matters of high specific weight, such as mercury.

Figs. l11 show by way of example embodiments of my invention.

Fig. 1 is a cross sectional view through the generator on the line 1-4 of Fig. 2.

Fig. 2 is a longitudinal section through the generator along line 2-2 of Fig. 1.

Fig. 3 shows an arrangement for further transport of ash by part of the combustion gases.

Fig. 4 is a detail drawing showing the plates connecting the heating elements and sootblowers.

Fig. 5 is another detail view of the plates and sootblowers.

Fig. 6 is a cross section through part of the heating elements.

Fig. '7 is a longitudinal section through the rotating shaft and part of the heating elements.

Fig. 8 is a, section through an individual heating element. 1

Fig. 9 is a detail section showing the connection of the rotating shaft with a header for the heating elements.

Fig. 10 is a cross sectional view through one end of the vapor generator and a turbine connected to it, showing particularly the connections between generator and turbine.

Fig. 11 is a cross section as is Fig. 10 but showing another method of conducting the steam from the generator to the turbine.

Referring more particularly to the drawings:

Figs. 1 and 2 show cross sections through a revolving steam generator, more particularly of such a generator adapted to use pulverized coal as fuel. The products of combustion or combustion gases enter the gene1;ator proper through an opening between the superheater elements, whereby the rotating heating elements accelerate the combustion gases in a circumferential direction. The gases also rotate within the heating surfaces at considerable speed, this speed, of course, being slower than the circumferential speed of the heating elements; the centrifugal force which is in proportional relation to the speed of rotation throws unbumt dust particles to the outside, either back into the combustion chamber 2 or into the pockets 3. Since the velocity necessary to precipitate the small particles is only gradually attained by the gas stream,

the separation will not be completed until the gases have traveled a certain distance in axial direction. It is necessary that the drum formed by the heating elements is left open to this point. As obvious from the drawings, the spaces between the headers 5 which connect the individual vapor generating tubes 4 are closed by means the combustion gas through the pocket 3.

of closing plates 6. Thus the tubesystem is closed on the outside and forms a drum through which the gases travel in a direction substantially parallel to the axis of the drum. The closing plates 6 may be provided with openings ll. It is advantageous to leave the system open on its outer circumference at th end where the gases enter to such an extent that an essential part of the dust particles carried along by the combustion gases is thrown out into pockets 3 which deliver it to collector l3.

The generator may be fired by means of a burner I4 as shown in Fig. 2. The flame travels through the chamber 2 before encountering the heating surfaces. Since the flame is above the drum formed by the heating elements, solid particles will fall on the rotating heating surface and will be carried along by the elements and either thrown back into the combustion chamber or out into the collecting pockets. The generator is surrounded by a casing l6. No dust collecting pockets are arranged along a certain part of the generator. For example, in the design disclosed in Fig. 2 there are only collectors at the far left and at the far right end of the heating elements 4. This is to allow unburntcoal particles which fall in between the heating elements through openings l1 to be completely burnt or to be thrown back into the combustion chamber 2 and to prevent unbui'nt coal particles from being thrown into the collectors. The funnels 3 receive only ash because the gases entering the heating elements at the far left side have traveled through the whole length of the combustion chamber and contain practically no unburnt matter. The same is the case with the gas leaving the system. Any unburnt material has been thrown back into the combustion chamber so often that it has plenty of chances to be burnt by the time the gases reach the outlet of the system. The collectors l2 at the gas outlet are separated from the burner and the combustion chamber.

The particles carried by the combustion gas have very high temperatures at the point where the gas leaves the combustion chamber and enters the superheater and are in a. liquid or paste like state. They must be cooled before entering the collecting funnel to facilitate their further transport. This cooling or granulating effect is assured in a construction as per Fig. 2 where the gases come in contact with the relatively cool heating surfaces of the tubes l in which the steam is superheated.

In order to effectively revolve the gases which enter close to the center of rotation where the circumferential speed is comparatively slow, vanes or guide plates l5 may be provided.

Whereas the collecting pockets l2 and 3 according to Figs. 1 and 2 discharge into closed receives l3 and I3 which may be emptied from time to time or from which dust may be with: drawn by hydraulic or other means, Fig. 3 shows a pneumatic dust removing system. The fast rotation of the heat absorbing elements causes an increase of gas pressure at the circumference which can be used to blow a'certain amount of y this gas the dust is carried through conduit 1 and conveyed into a receiver 8 which may contain water or the like, wherein the dust settles down or is floated away with the liquid. To avoid a loss of the heat still contained in the hot gases, conduit 1 may be arranged to go through a heat exchanger 9, where the heat contained in the the gases, and the possibility that unburnt comgas is transmitted, for example, to the feed water or the combustion air. In the former case, water would be supplied to the heat exchanger 9 through inlet l9 and would leave the exchanger at the outlet 26 and be conducted to the heating elements 4 via the hollow shaft 25. In the latter case, air would be forced through the heat exchanger 9 and would be conducted therefrom to the burner |4.

Figs. 4 and 5 show sootblowing arrangements. By these means, dust which collects on the inside of the plates 6 is removed and blown towards the gas outlet of the generator where it is thrown into the pockets |2 as shown in Fig. 2. For example, a blow pipe l0 may be welded to the plates 6 and provided with nozzles pointing in the axial direction of the gas flow and towards the gas outlet.

As before said, the plates 6 may be provided with openings l1 through which the fine dust circulates back to the combustion chamber. The

number and/or size of the openings may be reduced towards the outlet of the apparatus, because the amount of dust carried along by the gases becomes less and less along the path of bustibles would fall directly from the burners into a comparatively cold gas stream becomes greater.

It is obvious from the aforesaid that the invention is applicable to directly fired vapor gen-- erators, but it can also well be used for waste heat boilers; the application of the idea is particularly desirable where waste gases must be handled which contain large amounts of dust, such as those in cement or similar plants.

Fig. 6 represents a cross section through the revolving heat exchanger or evaporator. In this case the evaporating elements proper consist of tubes 2 I. The center lines of the tubes are radial, whereby the centrifugal forces cause only tensile stresses within the tubes, and the highest admissible stress can be applied to the tube material. The individual tubes 2| are connected on the outside by means of tubes 5 and at the circumference of the shaft 25 by means of hollow ledges 23.

Fig. '1 is a cross'sectional side view through a group of heat absorbing elements. The fluid may pass into the hollow ledge 23, through channels 21 and passes through the three tubes 2| at the right end of the group to the outer connecting header 5. It is then distributed from this header into the several heat absorbing tubes 2| whence it circulates back to the left part of the ledge 23' which is separated from the right part 23 by a partition 33.

,Fig. 8 shows a section through one individual tube element and a way of mounting it to the center piece.

In order to increase the strength of the heat absorbing tubes 2|, the tube walls may be made heavier towards the center of the apparatus and lighter towards the outside, thus taking care of the stresses caused by the centrifugal forces which increase towards the revolving center piece of the apparatus. This can be accomplished by giving the interior of the tubes a cone shaped configuration as shown in Fig. 3. One could also make the exterior of a cone shaped configuramachined from one piece in order to improve the strength. .Theconnecting header 6 may be attached tothe elements 2| by welding.

The hollow ledge 23 may be provided e. a T shaped or dovetailed extension 3, so that the whole group of heat absorbing elements can'be held in a. groove, which is parallel to the axis of the rotatingshaft. Since. due to its external heating and the steam circulatingthrough it, the ledge will attain higher temperatures the shaft which is cooled by the fluid, the supply of which is' advantageously arranged through a bore in the shaft, it is desirable to prevent a direct flow of the heat from the ledge to. I

shaft and the outside, whereas the threaded bushing 21' will sumclently tighten up ledge 23 against leakage to the outside. The threaded bushing 21' which will be well calked to prevent unscrewing, holds the ledge 23 in position and prevents its movement in an axial direction. The screwing in and calking of the bushing is facilitated by the bore 22 located opposite the bore for the bushing. Bore 22 is closed by the plug 28 with packing 23.

Figs. 10 and 11 show two examples as to how the vapor or superheated vapor may be conducted from superheating elements to the turbine diaphragm 3| which sits on thesame shaft as the evaporating elements 2| and the superheatlng elements I.

Fig. 10 shows an arrangement whereby the steam or vapor, or steam or vapor and fluid mixture passes from the headers 5 through the elements 2| to the bores 46' and to the super-heater elements I. The superheated steam or vapor is collected-in ring-headers 32. From ring-headers 32 it passes through a plurality of radial tubes 33 on to the axial collector 34 which is arranged .in the center of the shaft .25 and which iswell insulated against the shaft. Radial tubes 35 disposed within the hollow diaphragm 3|v conduct the vapor from the collector 34 to another circumferential or ring collector 36. From here the steam or vapor passes through the nozzles 31 and enters the turbine buckets 42. Ring 43 is stationary and serves with its faces 44 and 44 as guide for the steam or vapor. Ring43 may be 'provided with an exchangeable ring of special corrosion proof material, as its circumferential point 46 is directly exposed to the vapor which is discharged at high velocities from the nozzles Fig. 11 shows an alternative arrangement. Here the vapor coming from the bores 40 is conducted towards the turbine diaphragm 3| through tubes 38 which may be welded to the ledges 23.

The tubes 33 may be connected to the diaphragm by means of rolling in or in some other manner which is. suitable. Radial bores or openings 41 conduct the vapor towards the revolving turbin nozzles 31. What I claim is:

1. In a fast rotating heat exchangeapparatus. a shaft, a set of inner headers, heating elements and a set of outer headers, said inner headers being located adjacent to said shaft, said heat absorbing elements being connected to said inner headers and said outer headers.

2. In a fastrotating heat exchange apparatus, a shaft, a set of inner headers, heating elements and a set of outer headers, said inner headers being located adjacent to said shaft, said heat absorbing elements being connected to said inner headers and said outer headers, said heat absorbing elements lying in planes parallel with respect to said shaft.

3. In a fast rotating heat exchange apparatus, a shaft, a set of inner headers, heating elements and a set of outer headers, said inner headers being located adjacent to said shaft, said heat absorbing elements being connected to said inner headers and said outer headers, said headers having partitions, the heat absorbing elements connected to the headers between said partitions forming groups and a fluid within -said heating elements, said fluid circulating serially from one of said groups to the other-group.

4. In a fast rotating evaporataing apparatus, a shaft, tubular heat absorbing elements radially connected to said shaft, the cross sectional dimensions of said tubular heat absorbing elements being heavy adjacent to said shaft and becoming lighter with increasing distance from said shaft.

5. In a fast rotating evaporating apparatus, a hollow shaft, a set of hollow inner headers, heating elements and a set of outer headers, said inner headers being located adjacent to said shaft, bores in said inner headers and in said shaft, said bores connecting the hollow of said shaft with the hollow of said headers, said heating elements connecting said inner headers and v said outer headers.

6. In a fast rotating heat exchange apparatus, a hollow shaft, inner headers, tubular heat absorbing elements, outer headers, a ring shaped collector, radial conduits, and a drum shaped collector, whereby an operating fluid may flow from said hollow shaft into said inner headers, therefrom through said tubular heat absorbing ele-' ments to said outer headers, from said outer headers into said collector, and from said ring collector through said radial conduits into said drum shaped collector.

'7. In a fast rotating heat exchange apparatus, a hollow shaft, inner headers, tubular heat absorbing elements, outer headers, a ring shaped collector, radial conduits, and a drum shaped collector, whereby an operating fluid may flow from said hollow shaft into said inner headers, therefrom through said tubular heat absorbing elements to said outer headers, from said outer headers into said ring collector, and from said ring collector through said radial conduits into said drum shaped collector, a hollow connecting shaft directly connected to said first mentioned hollow shaft, said drum shaped collector being located within said hollow connecting shaft.

8. In a fast rotating heat exchange apparatus, a shaft, tubular heat absorbing elements mounted on said shaft, headers connecting said heat absorbing elements, and a plurality of conduits connected to said headers, said conduits being substantially parallel to said shaft.

9. In a fast revolving heat exchange apparatus, a shaft, heat absorbing elements, dovetails on said elements, grooves in said shaft, said dovetails fitting into said grooves.

10. In a heat exchanging apparatus rotating heat absorbing elements arranged around a center of rotation and heated by hot gases containing particles of greater specific weight than the specific weight of the gases, a closure around and connected to said heat absorbing elements, and openings in said closure adapted to permit the escape of the particles contained in the heating gases and thrown towards said enclosure under the influence of centrifugal forces set up in the hot gases and particles by said rotating heat absorbing elements.

11. In a heat exchanging apparatus rotating tubular elements radially arranged about a center of rotation, said elements being heated by hot gases, and forming passages for a heat absorbing medium and a closure around and connected to some of said heat absorbing elements, said closure forming a duct for the gases heating said elements within said duct.

12. In a heat exchanging apparatus rotating tubular elements radially arranged about a cen ter of rotation and heated by hot gases containing soot, a closure around and connected to some of said heat absorbing elements, said closure forming a duct for the gases heating said elements within said duct, and sootblowers within said closure.

13. In a heat exchanging apparatus rotating tubular elements radially arranged about a center of rotation and heated by hot gases containing soot, a closure around and connected to some of said heat absorbing elements, said closure forming a duct for the gases heating said elements within said duct, sootblowers within said closure, and nozzles on said sootblowers, said nozzles pointing substantially parallel to said center of rotation.

14. In a heat exchanging apparatus rotating heat absorbing elements arranged around a center of rotation and heated by hot gases containing particles of greater specific weight than the specific weight of said gases, an enclosure around a plurality of said heat absorbing elements, said enclosure together with said heat absorbing elements forming a substantially cylindrical body, openings at both ends of said cylindrical body, the hot gases entering through the opening at one end and leaving said body through the opening at the other end, pockets adjacent to said ends of said cylindrical body, said pockets adapted to receive particles moving outwards under the influence of centrifugal forces set up in the hot gases and particles by said rotating heat absorbing elements.

15. In a heat exchanging apparatus a rotating hollow shaft, tubular-heating elements substantially radially arranged around said shaft and heated by hot gases containing solidified particles and moving substantially parallel to said shaft, and vanes substantially parallel and connected to said shaft in between said tubular elements and rotating with said shaft, said vanes assisting I the rotating tubular elements in the promotion of a rotational movement of the heating gases and particles contained therein and throwing the particles out of the path of the gases.

16. In a quickly rotating heat exchange apparatus a hollow shaft, inner headers, tubular heat absorbing elements, outer headers, a ring-shaped collector, radial conduits, a drum-shaped collector whereby an operating fluid may flow from said hollow shaft into said inner headers, therefrom through said tubular heat absorbing elements to said outer headers, from said outer headers into said ring collector and from said ring collector through said radial conduits into said drum-shaped collector, a hollow connecting shaft directly connected to said first mentioned hollow shaft, said drum-shaped collector being located within said hollow connecting shaft, and a second set of radial conduits with one end connected to said drum-shaped collector, and

nozzles at the other ends of said'last mentioned radial conduits.

17. In a quickly rotating heat exchange apparatus a shaft, a. set of inner headers, heating elements and a set of outer headers, said inner headers being located adjacent to said shaft, said heat absorbing elements being connected to said inner headers and said outer headers and being heated by hot gases, said outer headers being paralled to said shaft and strips connected to and in between said outer headers, said strips together with said outer headers forming a cylindrical enclosure serving as a duct for the hot gases.

18.- The method consisting in conducting hot gases containing solid particles first over tubular heat absorbing surfaces which rotate arounci an axis substantially perpendicular to said tubes, in imparting a rotating motion to said gases by said surfaces, in simultaneously diverting the flow direction of said gases while they pass over said surfaces, in thereby positively diverting the direction of movement of said solid particles from that of said gases, and in throwing said particles into pockets, in splitting up part of the gases, and in using the centrifugal pressure set up in said gases by said rotating motion for blowing said particles out of said pockets.

- 19. The method consisting in conducting hot gases containing solid particles first over tubular heat absorbing surfaces which rotate around an axis substantially perpendicular to the tubes, in-

out of said pockets, and in transporting said solid particles by said part of the gases and said pressure from said pockets into and through a heat exchanger in which the heat still contained in the particles and gases is usefully absorbed by other media.

HEINRICH VORKAUI".

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