IL46077A - Rotary boiler-combustor - Google Patents

Description

a¾a»o nyaa-ηπ Aarotary Boilex-coa stor E. I. DU PQHT DE IBMOtJHS AKD GOHPAOT C. 43966 This invention relates to new and useful improvements in rotary boiler and combustor devices. The invention is ^ useful with any selected boiler fluid and particularly applicable to rotary boiler and combustor devices for use with organic high molecular weight power fluids. While useful for producing vapor for many purposes, the invention is especially adapted for use with rotary closed Rankine cycle engines such as, for example, shown and described in my U.S. Patents No. 3 , 613 , 368 issued October 19, 1971 and No. 3 , 7^4 , 246 issued July 10 , 1973 - Rotary boilers are known in the art. Rotary boilers such as shown in my aforesaid patents and patent application provide many advantages that offset the disadvantages of prior rotary boilers. For example, such a rotary boiler can be operated at a much higher heat flux due to the high centrifugal forces on the liquid, and nucleate boiling is suppressed and replaced by a very stable quiescent convectlve type of boiling. Also, the rotary boiler has a low pressure drop and no hot spots. Most important, however, is the simplified liquid pumping that occurs in a rotary boiler, and if the rotary boiler is arranged so that there' is a liquid leg between the condenser and the bolier, the centifugal force developed by the rotation acting on this liquid leg is able to develop the necessary boiler pressure. Thus, simple radical tubes in a rotary boiler take the place of a complex boiler feed pump in a non-rotating system, and the liquid is automatically supplied to the boiler as required, thereby eliminating the necessity for a control system to match the boiler feed pump rate to the fuel rate as in a stationary boiler. Still another advantage of a rotary boiler is that the radical feed tubes supplying liquid to the boiler also act as relief valves that prevent overpressuring the boiler.

Nevertheless, there are several problems present in a rotary boiler. For example, it is difficult to provide a suitable seal between the rotary boiler and the surrounding fixed non-rotating combustion chamber to prevent hot gas or flame leakage. Insulation of the combustor is another problem. When the combustor wraps around the rotary boiler, the sides and periphery of the combustor must be insulated. This leads to large size and undesirable heat losses.

Another problem is good heat transfer. Since the beam length for radiation is short, most of the heat transfer is by convection. Providing adequate convective heat coefficients or sufficient boiler surface area can be difficult.

With the foregoing in mind, an object of the present invention is to provide a rotary boiler-combustor of the type described and embodying novel features of design and construction to produce high quality vapor with steady flow of both vapor and liquid independent of the earth's gravity field and orientation and capable of producing heat fluxes well above a peak boiling level for normal gravity.

Another object of the invention is to provide a rotary boiler-combustor wherein the seal points between the stationary and rotating parts are constructed and arranged so that the ambient air leakage is inward to the combustion chamber .

Another object of the invention is to provide a rotary bolier-combustor that is constructed and arranged to require a minimum amount of insulation.

Another object of the invention is to provide a rotary boiler-combustor construction having a combustion chamber that provides a high degree of mixing so as to obtain a high convective coefficient, quiet combustion, high volymetric heat release, and compactness.

Another object of the invention is to provide a rotary boiler-combustor device that is self-pumping and does not require a separate blower to provide combustion air.

Another object of the invention is to provide a rotary boiler-combustor device that operates with a low pressure fuel pump and a wide variety of liquid fuels without adjustment and does not require an atomizer fuel nozzle.

Another object of the invention is to provide a rotary boiler-combustor design and construction that provides for heat removal from the combustion flame between the introduction of primary and secondary air, thus keeping the combustion temperature down and minimizing formation of nitrogen oxides so that there is very low pollution.

Another object of the invention is to provide a rotary boiler-combustor construction characterized by high combustion efficiency obtained by providing for the combustion gas just prior to venting to the exhaust chamber a heat transfer section having a high surface area and a high convective heat transfer coefficient.

A further object of the invention is to provide a rotary boiler-combustor device of a construction having a low stress level providing maximum safety.

These and other objects of the invention and the various features and details of the construction and opera-tion thereof are hereinafter set forth and described with reference to the accompanying drawings, in which: Fig. 1 is a side elevational view partially in section of one embodiment of a rotary boiler-combustor constructed in accordance with the present invention; Fig. 2 is an enlarged fragmentary vertical sectional view through Fig. 1 showing certain details of construction and arrangement of the rotary boiler-combustor; Fig. 3 is a side elevational view showing the construction and arrangement of the tubular boiler in the embodiment of the invention shown in Figs. 1 and 2; Fig. 4 is an end view of the boiler construction shown in Fig. 3; Fig. 5 is a view partially in section on line 5-5» Pig- 2; Fig. 6 is an enlarged fragmentary sectional view of a portion of Fig, 2 showing details of the construction of the rotary boiler-combustor; Fig. 7 is an enlarged fragmentary view partially in section on line 7-7, Fig. 2; Fig. 8 is an enlarged fragmentary view partially in section on line 8-8, Fig. 2; Fig. 9 is a schematic diagram Illustrating the flow of boiler liquid condensate through the heat exchange tubes of a rotary pre-heater prior to returning to the rotary boiler; Fig. 10 is an enlarged fragmentary vertical sectional view showing certain details of construction and arrangement of another embodiment of the invention; Fig. 11 is a side elevational view, partially in section, of the embodiment of the invention shown in Fig. 10; Fig. 12 is a schematic view on line 12-12, Pig. 10; Pig. 13 is a view similar to Pig. 6 showing still another embodiment of the invention; and Fig. 14 is another view similar to Pig. 6 showing a further embodiment of the invention.

Referring now to the drawings, and more particularly to Figs. 1 and 2 thereof, one embodiment of a rotary boiler-combustor made according to the present invention is shown in the form of a closed Ranklne cycle system comprising a rotary housing H and boiler B, and a rotary condenser C_ coupled to the housing and boiler for rotation therewith as a unit .

The housing H includes a coaxial central portion 1 having an axial hub 2 provided with a central bore 3 extending axially therein. Mounted in the bore 3 is a shaft 4 that is secured in the hub 2 for rotation therewith.

The shaft 4 projects axially outward from the housing portion 1 and is journalled in a bearing 5 that is mounted in a fixed standard or support 6. At the opposite side from the shaft 4 the housing H includes a coaxial shaft 7 that is rotatably mounted by means of a bearing 8 housed in a hub structure 9 supported coaxially of the rotary housing by means of radial spokes 10 from a fixed support 11.

In the embodiment of the invention illustrated, the boiler B is of tubular construction comprising a plurality of successively coiled tubes 12, 13, 14 and 15, respectively.

As shown in Figs. 3 and 4 of the drawings, the boiler B comprises a radially disposed section B' comprising a spirally coiled portion of each of the tubes 12, 13, 14 and 15, and an axially disposed section B" comprising the helically coiled remaining portion of each of said tubes. Each of the boiler tubes 12, 13 , l^ and 15 is of the same length and diameter ^ and the respective tubes are coiled so that the inlet ends 16, 17, 18 and 19 thereof are equally spaced circumferentially about the periphery of the radial section B' of the boiler and with the outlet ends 20, 21, 22 and 23 of said tubes similarly spaced circumferentially about the opposite end of the axial section B" of the boiler.

In Figs. 3 and 4 of the drawings, the radially and axially coiled portions of the several boiler tubes 12, 13, l4 and 15 are shown in spaced relation to one another to better illustrate the arrangement of said tubes, and it is to be understood that in actual construction the adjacent coil portions of the tubes are disposed in contiguous abutting relation to one another. Also, the boiler B is not limited to the precise number of coiled tubes shown and described, and a more or less number of tubes may be employed as desired or required for a particular rotary boiler-combustor unit.

The tube coils in the axially extending section B" of the boiler B are mounted on the outer surface of a cylindrical wall portion 25 of the rotary housing H and the radially disposed coils thereof are mounted on a radial wall portion 26 that projects outwardly from said axial wall portion 25. The cylindrical wall portion 25 is spaced radically outward from the outer furface 27 of the central portion 1 of the housing by means of a radial wall portion 28 to provide a thermal insulating air space 29 therebetween and the wall portions 25 and 26 are further thermally insulated by suitable insulation material 30.

The selected boiler liquid is supplied to the several tubes 12, 13, 14 and 15 of the rotary tubular boiler B through the inlet ends 16, 17, 18 and 19 of said tubes in the form of condensate from the condenser (2 as hereinafter described. The rotary housing H and boiler B are adapted to be driven about their axis at a predetermined speed of rotation calculated to create the centrifugal force necessary to maintain the coil portions of the tubes in the radial section B' of the tubular boiler entirely filled with the selected boiler liquid and to maintain the boiler liquid in the coil portions of said tubes in the axial section B" uniformly at the same depth ' circumferentially thereabout with a liquid/ vapor interface., indicated at , that is highly stable and essentially cylindrical and concentric with the axis of rotation with the boiler.

In the embodiment of the invention shown in Figs .1 and 2, the rotary boiler is rotationally driven at the desired predetermined speed by means of an electric motor M driving a pulley 32 fixed on the housing shaft 4 through a belt or chain 33, and the inventory of boiler liquid with which the boiler is charged is predetermined to insure that the coil portions of the tubes in the axially extending section B" of the boiler B are about half full, as shown, at full power output of the boiler and at least partially filled at minimum power. Essentially, the liquid/vapor interface x is disposed at a predetermined radius from the rotation axis of the boiler to provide high boiling heat fluxes in excess of those obtainable at ambient gravity.

The liquid in the tubular boiler is heated to the required boiling temperature to vaporize the same by the combustion of a suitable fuel-air mixture in an annular combustion zone 35 that surrounds the rotary boiler B and is defined by a circumscribing cylindrical stationary wall or partition 36. The wall or partition 36 is fixedly mounted in a stationary scroll-shaped hood structure 38 that encloses the rotary boiler B and said partition 36 and defines an exhaust plenum chamber 40 for the combustion gases. The hood structure 38 has a discharge outlet at 42 as shown in Pig. 5 of the drawings.

Preferably, and in the illustrated embodiment of the invention, the wall or partition 36 is in the form of a secondary combustion air plenum chamber 44 comprising a pair of radially spaced substantially parallel concentric outer and inner cylindrical plate portions 45 and 46. Secondary combustion air is applied to the annular plenum chamber defined between the plate portions 45 and 46 as hereinafter described, and a plurality of openings 47 is provided in the inner plate 46 for discharging the secondary combustion air from the plenum chamber 44 into the annular combustion zone 35 Mounted on the outer side of the radial wall portion 28 of the rotary housing H is an annular fuel distributor 50 that rotates with said housing and spaced axially outward from said distributor 50 and rotatable therewith is a fuel atomizing ring 1 having a peripheral discharge lip 52 extending axially inward toward the combustion zone 35· In the illustrated embodiment of the invention, the selected liquid fuel is supplied by a low pressure pump (not shown) to a fuel inlet tube 53 that has its discharge end 5^ disposed in confronting relation to the rotating fuel distributor 50 so that fuel discharged from the tube 53 impinges on said distributor 50 and is distributed uniformly circumferentially thereabout. The circumferentially distributed liquid fuel is discharged by centrifugal force from lip 52 of the atomizing ring 1 axially into the combustion zone 35 in the form of a spray or mist of very fine droplets or particles.

A combustion air chamber 55 is provided adjacent the fuel distributor 50 and atomizing ring 51 and is partially enclosed by a stationary annular plate 56 of the stationary hood structure 38. The annular plate 56 has a circular series of arcuate air inlet ports 57 formed therein, for example, as shown in Pig. 5 of the drawings and a similar annular plate 58 having a corresponding series of arcuate openings 59 therein is mounted outwardly adjacent the stationary plate 56 and is rotatably adjustable relative thereto. By rotary adjustment of plate 8 relative to plate 6 the size or area of the air inlet ports 57 in said plate 6 may be increased or decreased as desired to regulate and control the amount of air admitted therethrough to the combustion air chamber 55 and maintain the proper air/fuel ratio at the desired power level.

Prom the chamber 55 primary combustion air passes between the rotating atomizing ring 51 and a stationary cylindrical ring 60 directly into the combustion zone 35 and secondary combustion air passes into the cylindrical plenum chamber 44 from which it is discharged into the combustion zone 35 through the openings 7 provided in the inner plate portion 46 thereof. The primary and secondary combustion air and the finely divided mist of fuel are thoroughly mixed in the combustion zone 35 b the relative rotation of the boiler B and associated parts with respect to the stationary wall or partition 36.

The air/fuel mixture in the combustion zone 35 is ignited by a plurality of igniter devices 6l mounted at clrcumferentially equally spaced intervals in the plate 36 of the stationary hood structure 38 so that combustion of the fuel/air mixture takes place substantially clrcumferentially throughout the annular combustion zone 35· Alternatively, gaseous fuel instead of liquid fuel may be used in the boiler-combustor . Instead of liquid fuel distribution ring 50 and liquid fuel atomizer ring 51 the combustor can be provided with a plurality of fuel gas nozzles located in the same radial position as ignitors 6l but alternating with them around the side of the chamber.

High pressure vapor generated in the boiler B by combustion of the fuel/air mixture in the combustion zone 35 is discharged from the outlet ends 20, 21, 22 and 23 of the boiler tubes 12, 13, 14 and 15, respectively, through a plurality of radial vapor tubes 62 to an annular pressure vapor chamber 63 as provided in the rotary housing H. The vapor tubes 62 are arranged clrcumferentially in equally spaced relation to insure rotational balance in the unit, and one vapor tube 62 is provided for each tube in the boiler B and connected to the outlet ends thereof.

Pressure vapor generated in the boiler B is discharged into the annular housing chamber 63 and enters a condenser C_ where it is condensed and the condensate returned to the boiler B as hereinafter described. While any suitable form of rotary condenser may be employed for condensing the boiler pressure vapor, in the illustrated embodiment of the invention the condenser C comprises a coaxial array of radially disposed annular fins 65 having a plurality of heat exchange tubes 66 extending longitudinally therethrough. The condenser C is mounted at one side of the housing H concentrically of the shaft 7 and is secured to said housing for rotation therewith as a unit. The fins 65 consist of separate or independent annular disk elements supported and secured in predetermined equally spaced parallel relation with respect to one another and the fins 65 and tubes 66 are fabricated of metal having high thermal conductivity such as, for example, copper or aluminum, said fins prefer-ably being bonded to said heat exchange tubes by brazing, soldering or the like, to provide maximum thermal conductivity therebetween.

The tubes 66 are arranged in rotationally balanced spaced relation circumferentially of the fins 65 and are secured at their inner ends in corresponding openings 76 provided through the adjacent wall 68 of the housing H so that the interiors of the tubes 66 are in communication with the interior of the pressure vapor chamber 63 as shown in Fig. 2. As shown in Fig. 1, the outer ends of the tubes 66 are mounted and secured in recesses 69 provided in an annular end ring 70 that is disposed coaxially adjacent the outermost of the fins 65 and supported from the shaft 7 by circumferentially equally spaced radial spokes 71. Thus, the condenser C, housing H and boiler B are rotatable as a unit about their common axis.

The inner peripheral edges of the fins 65 define internally thereof a coaxial inlet chamber 72 for the cooling fluid to be discharged outwardly by and between the plurality of rotating fins 65 as hereinafter set forth.

The inner diameter of the ring 70 is substantially the same as the inner diameter of the adjacent group of fins 65 so as not to restrict the flow of fluid into the chamber 72 , and an outwardly flared or bell-shaped fluid intake member 73 is fixedly supported by the spokes 10 from the stationary support 11 in coaxial relation outwardly adjacent the end ring 70 as shown in Pig. 1.

The axial spacing or distance between the adjacent fins 65 and the ratio of the inner to outer radii thereof is critical and the fin spacing must be determined with relation to both the rotational speed at which the unit is designed to be driven and the kinematic viscosity of the condenser cooling fluid to have a Taylor number (-WFa) that is operable at the fin radii ratio to utilize the viscous properties of the cooling fluid and the shear forces exerted thereon by the rotating fins 65 to convey and accelerate the fluid spirally outward between said fins by viscosity shear forces. Taylor number is defined by the formula = d^w/v, wherein d is the distance between fins, w is the velocity in radians per second and v is the kinematic viscosity.

The boiler pressure vapor discharged to the chamber 63 passes into the heat exchange tubes 66 where the vapor is condensed by heat exchange with a cooling fluid, such as ambient air, discharged outwardly between the array of fins 65 as previously described. The condensate thus formed in the tubes 66 flows from the inner ends thereof across the cylindrical wall surface 7^ of the chamber 63 and enters a plurality of equally circumferentially spaced conduits 75 through which the condensate is discharged outwardly by centrifugal force generated by rotation of the housing-condenser unit and returned to the boiler B through a boiler liquid pre-heater arrangement generally designated P.

The boiler liquid pre-heater P comprises an annular series of a plurality of axially extending heat exchange tubes 76 arranged circumferentially in circumscribing relation about the combustion zone 35 outwardly adjacent the stationary partition 44 and within the stationary hood structure 38, for example, as shown in Pigs. 5 and 7 of the drawings.

Each of the tubes 76 has its opposite ends mounted in recesses 77 and 78 provided respectively in axially spaced circumfer-ential mounting rings 79 and 80 of the rotary housing H. The rotary housing H also includes circum erential rings 81 and 82 disposed outwardly adjacent said mounting rings 79 and 80, respectively.

In the illustrated embodiment of the invention there are provided, for example, four condensate return conduits 75 arranged circumferentially in equally spaced relation 90° apart within the rotary housing H. The outer end of each conduit 75 connects with a port 83 provided in the housing ring 8l, and each of the ports 83 in turn communicates with a registering port 84 in the adjacent housing ring 79· Each of the ports 84 is in communication with the adjacent end of one of several of the tubes 76, particularly designated 76'.

In the illustrated embodiment of the invention there are four such tubes 76' disposed at equally spaced intervals circumferentially of the housing H in the annular series of tubes 76. The opposite end of each of the several tubes 76' communicates through a port 85 in the mounting ring 80 with a continuous annular manifold 86 that is provided in the housing ring 82 and is common to and in communication with the adjacent ends of all of the series of tubes 76 as illustrated in the schematic diagram shown in Pig. 9.

The other ends of the tubes 76 opposite the common manifold 86 (except the tubes 76') communicate through passages 87 provided in the mounting ring 79 with one of four segmental arcuate manifold sections 88 formed in the housing ring 8l. Each of the manifold sections 88 is connected to the inlet end of one of the coiled tubes 12, 13, l^ or 15 of the boiler B, for example, the inlet end 19 of the tube 15 as shown in Pig. 9 of the drawings.

Thus, in the pre-heater construction shown and described, the boiler liquid condensed in the condenser C will be discharged radially through the several conduits 75 and flow in one direction axially through the pre-heater tubes 7β' to the common manifold 86 and then in the reverse direction through the remaining tubes 76 to one of the manifold sections 88 from which the pre-heated boiler liquid is returned to the boiler B as described.

Each of the tubes 76 including the several tubes 76' extends longitudinally through an array of a plurality of coaxial radially disposed closely spaced annular fins 90. The fins 90 and tubes 76 and 76' are fabricated of metal having high thermal conductivity and said fins 90 preferably are bonded to the tubes 76 and 761 to provide maximum thermal conductivity therebetween and optimum heat exchange between the combustion gases in the hood structure 38 and the boiler liquid condensate in the tubes 76 and 76' of the pre-heater P. As shown in Pig. 8 of the drawings, intermediate each tube 76, each of the fins 90 is slotted a predetermined distance radially from the inner edge thereof as indicated at 91 to accomodate differences in thermal expansion between the inner and outer peripheral edge portions of the. fins due to differences in temperature of the combustion gases passing outwardly between the fins 90 of the pre-heater P.

As previously described in connection with the particular illustrated embodiment of the condenser C and its fins 65, the axial spacing of the pre-heater fins 90 is determined with relation to the rotational speed at which the housing-boiler-condenser unit is driven and the kinematic viscosity of the combustion gases to have a Taylor number operable at the inner to outer radii ratio of said fins 90 to pump the combustion gases by viscostiy shear forces spirally outward between the fins 90 into the exhaust plenum chamber 40 defined by the stationary hood structure 38. Such shear force pumping is quiet, efficient and also provides a high convective heat transfer coefficient in the pre-heater P.

The combustion gases travel in a generally helical path through the combustion zone 35 and then pass about the lateral end of the stationary partition 44 to an annular transfer zone 92 between the said partition 44 and pre-heater P from which the gases are pumped by the rotating pre-heater fins 90 into the exhaust chamber 40. The predominant velocity of the combustion gases is tangential due to the relatively high rotational velocity of the boiler tubes 12, 13, 14 and 15 with respect to the fixed cylindrical partition 44. The very fine droplets of fuel discharged from the rotating fuel atomizing ring 51 Into the combustion zone are thoroughly mixed with the combustion air due to the high tangential velocity component of the combustion flame and the relatively long path of travel thereof through the cylindrical combustion zone 35 thereby providing a quiet, compact combustor charac- terized by a high volumetric heat release. Initially, the fuel from rotating atomizing ring 51 mixes with primary air entering through the annular space between rotating peripheral discharge lip 52 and stationary cylindrical ring 60. While traveling in its helical path the fuel rich flame gives off heat to boiler tubes 12, 13, 14, and 15. Simultaneously, the flame is mixed with secondary air admitted to the combustion chamber through holes 47 in cylindrical plate 46 of the fixed cylindrical partition 44. The loss of heat from the flame before the combustion is complete results in a lower combustion temperature which leads to a lower concentration of nitrogen oxides in the combustion products.

The opposite side portions of the stationary hood structure 38 surrounding the rotary boiler B are provided, respectively, with axially extending cylindrical sealing ring portions 94 and 95 that are disposed in circumscribing closely spaced relation with confronting cylindrical external surface portions of the rotary engine housing H. Thus, the sealing ring is disposed in closely confronting reltaion with the cylindrical outer peripheral surface 96 of the engine housing H, and the sealing ring 95 Is disposed in closely confronting relation with the cylindrical outer surfaces of the circumferential rings 81 and 79 of the rotary housing H. A plurality of circumferentially equally spaced tubes 98 are connected as shown in Fig. 6 between the sealing ring 95 and housing rings 8l and 79 and the combustion zone 35 and since the latter is below atmospheric pressure, the tubes 98 will conduct air from the ambient atmosphere and exhaust gas leakage at seal 95 to the combustion zone 35 thereby not only preventing exhaust gas leakage from the stationary hood structure 38 to the ambient atmosphere but also providing exhaust gas re-circulation to the combustion zone to substantially reduce the formation of pollutants, especially oxides of nitrogen.

In normal operation of the rotary boiler-combustor with the liquid in the rotary boiler B heated to the required temperature and pressure by combustion of the fuel/air mixture in the combustion zone 35, the pressure vapor generated in the boiler is discharged inwardly through the tubes 62 to the chamber 63 and thence into the heat exchange tubes 66 of the condenser C where it is condensed by the cooling fluid discharged outwardly between the fins 65 as previously described. The boiler liquid condensate flows inwardly and out of the condenser tubes 66 and over the housing surface 7 into the conduits 75· Condensate entering the conduits 75 is pumped by centrifugal force, through the heat exchange tubes 76 and 76' of the pre-heater P and returned to the boiler B as previously described whereupon the cycle is repeated.

The cooling fluid, such as air, discharged outwardly between the fins 65 of the condenser is heated to a substantially high temperature by heat exchange with the high temperature boiler vapor condensed in the condenser tubes 66 and the hot air discharged through the condenser may be used for space heating, for example, by enclosing the condenser C to collect said hot air and ducting it to hot air outlets suitably disposed in the space to be heated. Alternatively, the hot air discharged from the condenser may be used for heating and/or drying purposes in industrial processes and the like.

A typical design of a rotary boiler combustor embodying the construction shown and described has a boiler B comprising a plurality of coiled tubes 12, 13, 14 and 15 each having an outer diameter of 0.5 inch. The axial section B" of the boiler has an axial length of 2.5 inches and the tube portions therein are coiled on 18.0 inch diameter centers so that the liquid/vapor interface x is spaced 9-0 inches from the rotation axis of the boiler. The inner cylindrical plate portion 45 of the stationary partition 36 has an inner diameter of 19.84 inches and the outer plate 46 has an outer diameter of 20.03 inches. The pre-heater P comprises ninety heat exchange tubes 76, including the tubes 76' , each having an axial length of 2.5 inches and an outside diameter of 3/8 inch. The tubes are equally spaced circum-ferentially of the stationary partition 3 on 21.25 inch diameter centers. The array of annular fins 90 has an axial length of 2.5 inches and the fins each have a thickness of 1/32 inch and the spacing between adjacent fins is 1/16 inch. Each of the fins 90 has an inner diameter of 20.5 inches and an outer diameter of 22.0 inches. The design speed of rotation of the boiler is 2400 r.p.m.

Using as the boiler liquid a mixture of trichloro-difluorobenzene isomers as disclosed in Bechtold and Tullock U.S. Patent 3>774,393> and using, for example, kerosene, as the combustion fuel, the specifications of a typical operation of the foregoing boiler-combustor are as follows: Boiler feed liquid (°P.) 313- Fuel rate (lbs/hr) 9-6 Air/Fuel ratio 18.5 Boiler vapor (°F.) 620.

Boiler output (Btu/hr) 150,000.

Combustor efficiency (%) 88.

The invention is not limited to the embodiment shown in Pigs. 1 and 2 of the drawings, and the pressure vapor generated in the boiler B may be used advantageously, for example, to rotationally drive the rotary housing-boiler-condenser unit at the desired speed as well as to provide power for driving external equipment and machinery. One such embodiment is shown in Pigs. 10-12 of the drawings in which the same reference numerals are used to designate parts that are Identical to parts shown in Pigs. 1 and 2.

Referring to Figs. 10-12 of the drawings, the housing H includes a coaxial central portion 1' having an annular hub structure 2' provided with a central bore 3' extending axially therethrough. Mounted in the bore 3' is a shaft that is secured in the hub 2* for rotation therewith. The shaft 41 projects axially outward from the housing portion 1 and is journalled in a bearing 5' that is mounted in a fixed standard or support 6 ' of the rotary engine. As shown in Fig. 11, the opposite side from the shaft of the housing H' includes a radically extending coaxial circular plate 100 having an endwise extending coaxial tubular shaft 101 that is rotably mounted by means of a bearing 102 upon a coaxially extending stationary shaft 103- The outer end of the stationary shaft 103 is mounted in a bearing 104 housed in a hub structure 104a supported coaxially of the rotary engine by means of radial spokes 10' from a fixed support 11'. The shaft 103 is secured against rotation by means of a radial pin 103a.

An internal expander, such as a turbine mounted coaxially within the rotary housing H*. The turbine T shown, is of the single stage type comprising a rotor 105 having a series of turbine blades 106 arranged peripherally thereabout. The turbine rotor 105 is received within an annular recess 107 provided in the housing portion 1' and is mounted for coaxial rotation independently of the boiler B on a coaxial shaft 108 that is rotationally mounted in bearings 109. An annular series of nozzles 110 is provided in the housing portion 1' coaxially adjacent the turbine rotor 105 and in confronting relation to the blades 106 thereof. An annular high pressure vapor manifold 111 is provided in the housing portion 1* and leads to the nozzles 106.

High pressure vapor is supplied from the boiler B to the manifold 111 by a plurality of vapor tubes 112 and connecting passages 113 arranged in equally spaced relation circumferentially of the axis to insure rotational balance in the unit. The high pressure vapor is discharged from the manifold 111 through the nozzles 110 and impinges upon the blades 106 to drive the turbine rotor 105 and its shaft 108 at the desired speed of rotation. A seal 114 is provided on the shaft 108 inwardly adjacent the turbine rotor 105 to minimize migration of the pressure vapor from the turbine along said shaft 108.

An annular diffuser 115 is provided in the housing portion 1' to receive the exhaust vapor from the expander, such as turbine T, and the inlet opening thereto is disposed in confronting relation to the turbine blades 106 at the opposite ends thereof from the nozzles 110. Exhaust vapor entering the diffuser 115 is discharged into an annular exhaust chamber 116 in the rotary housing from which it passes into the condenser C, and the portions of the vapor tubes 112 that span the annular exhaust chamber 116 are enclosed within concentric sleeves 112* of larger diameter than said tubes 112 to thermally insulate the tubes 112 from the lower temperature of the exhaust vapor in the chamber 116. A plurality of axially extending radial partitions or baffles 117 provided in the exhaust chamber 116 are arranged in equally spaced relation circumferentially about the engine axis function to maintain the angular velocity of the exhaust vapor at that of the rotating housing-boiler-condenser unit and to direct the vapor toward and into the condenser C.

In the illustrated embodiment of the invention, after start-up of the engine and with the liquid in the boiler B heated to the required temperature and pressure by combustion of the fuel-air mixture in the combustion chamber 35, the housing-boiler-condenser unit is rotationally driven continuously by the primary power output generated by the engine by means of an internal occluded fixed-ratio gear train arranged coaxially of the engine axis within the housing Η' , for example, as shown and described in application for U.S. Patent of Max F. Bechtold, Serial No. 206,779, filed December 10, 1971, now patent 3,769,796, issued November 6, 1973.

As shown in Pigs. 10 and 12 of the drawings, the gear train is in the form of a planetary gear system comprising a sun gear 120 fixedly mounted on and driven by the turbine shaft 108. Meshed with the sun gear 120 is a plurality of planetary gears 121 that are also meshed with a circumscribing annular ring gear 122. The ring gear 122 is mounted on and carried by an annular flange 123 that is formed integral with and projects axially inward from the adjacent face of plate 100 of the rotary housing H' . In the present embodiment as shown in Pig. 12 of the drawings, three planetary gears 121 are provided and arranged in equally spaced relation circumferentially about the engine axis. Each of the planetary gears 121 is rotably mounted on a stub shaft 124 by means of a bearing 125 and each stub shaft 124 is fixedly mounted in a stationary spider portion 126 provided at the inner end of the stationary shaft 103 whereby the axes of the planetary gears 121 are fixedly positioned so that they do not rotate or move circumferentially relative to or about the engine axis. Thus, the full power output of the engine turbine T is transmitted from the driving sun gear 120 through the planetary gears 121 directly to the driven ring gear 122 and the rotary housing-boiler-condenser unit at the fixed-speed ratio of the particular gear train.

The turbine shaft bearings 109 and the bearings 102 of the stationary shaft 103 as well as the several gears in the gear train are lubricated by a force feed system utilizing a Pitot type pump as shown and described in my U.S. Patent 3,744,246 issued July 10, 1973- In the embodiment shown, the ring gear 122 of the fixed-ratio gear train is disposed in an annular lubricant sump 128 formed in the rotary housing H' as shown in Pig. 10 of the drawings. The Pitot pump comprises a radial passage 129 formed in the stationary spider 126 and having at its outer end an L-shaped tip 129_ the inlet end of which is immersed in an annular bath of lubricant 330 in the sump 128 with the inlet thereto facing opposite the direction of rotation of the engine. The inner end of the passage 129 is connected to a coaxial passage 131 formed in the spider portion 126 and extending into the adjacent end portion of the shaft 103 where it connects with a radial passage 132 that opens between the bearings 102. A coaxial passage 133 extends through the sun gear 120 and adjacent portion of the turbine shaft 108 where it connects with a radial passage 134 that opens between the axially spaced turbine shaft bearings 109. The connection between the non-rotating passage 131 and the passage 133 in the rotating sun gear 120 and turbine shaft 108 may be made by means of a connector tube 130 having one end fixed in the passage 133 and the other end mounted coaxially within the stationary passage 131 by means of a suitable seal, for example, as shown and described in my aforesaid patent.

In the operation of the engine, it will be apparent at start-up that there will be no pressure vapor generated by the boiler to drive the internal expander and in turn the rotary housing-boiler-condenser unit. Consequently, at startup it is necessary to independently drive the housing-boiler-condenser unit at the designed predetermined speed of rotation to establish and maintain the liquid/vapor interface x in the boiler B until the liquid in the boiler is heated to the temperature to produce the desired pressure vapor to drive the turbine T. This may be accomplished, for example, by means of a starter motor M' driving a pulley 32' fixed on shaft 4' through a belt or chain 33'· Means such as a clutch (not shown), can be provided for breaking the drive between motor M' and pulley 32' when the engine attains normal operation, or the motor can continue to be driven by the rotating housing-boiler-condenser unit and shaft 4' and function as a generator operable, for example, for charging a battery that powers accessories such as the starter motor, lights and the like.

A power take-off 136 or other suitable driving connection is provided at the outer end of the output shaft 4' which may be used to drive any selected equipment or machinery such as, for example, a wheeled vehicle, boat, or otherwise, as desired.

In normal operation of the rotary engine, with the liquid in the rotary boiler B heated to the required temperature and pressure by combustion of the fuel-air mixture in the combustion zone 35, the pressure vapor generated in the boiler is discharged inwardly through the tubes 112 and passages 113 to the manifold 111 and thence through nozzles 110 into impinging contact against the turbine blades 106 thereby driving the turbine rotor 105 and shaft 108 at the desired speed of rotation. The shaft 108, through the occluded fixed-ratio gear train previously described, drives the housing-boiler-condenser unit and the shaft 4' at a predetermined speed of rotation relative to the speed of shaft 108 determined by the fixed-ratio of the gear train. In the embodiment of the invention shown, the direction of rotation of the housing-boiler-condenser unit and the shaft 4' is opposite the direction of rotation of the turbine shaft 108.

The exhaust vapor from the turbine enters the diffuser 115 and is discharged through the exhaust chamber 116 into the heat exchange tubes 66 of the condenser C where it is condensed by the cooling fluid discharged outwardly between the fins 65 as previously described. The boiler liquid condensate flows inwardly and out of the condenser tubes 66 and over the housing surface 74 ' into the conduits 75' · Condensate entering the conduits 75' is conveyed therethrough by centrifugal force, through the heat exchange tubes 76 and 76' of the pre-heater P and returned to the boiler B as previously described, whereupon the cycle is repeated.

The embodiment of the invention shown in Pigs. 10-12 is not limited to use of an internal gear train as previously described to rotationally drive the housing-boiler-condenser unit directly from the internal power fluid expander. Thus, in some installations, it may be desirable to rotationally drive the housing-boiler-condenser unit continuously by means of an external electric motor M as in the embodiment shown in Figs. 1 and 2 of the drawings, and use the full power output of the turbine shaft 108 to drive other equipment. For example, the turbine shaft 108 may drive an electric generator or alternator mounted internally of the rotary housing coaxially thereof as shown and described in my copending U.S. patent application Serial No. 386,630, filed August 8, 1973· Such a generator or alternator may be used not only to supply electric current to the external drive motor but also to supply electric power for appliances, heating, lighting and other electrical equipment. Also, the turbine shaft 108 may be extended coaxially to the exterior of the engine and the full power output of the expander used to drive mechanical equipment either directly or through appropriate speed reduction gearing as required.

The invention is not limited to the particular construction and arrangement of the boiler B and pre-heater P previously described, and examples of modifications thereof are shown in Figs. 13 and 14 of the drawings, respectively, in which the same reference numbers are used to designate parts that are essentially the same as parts previously described and shown.

Referring to Fig. 13, as there shown, the pre-heater may consist of a plurality of radially spaced concentric sections, for example two sections, the outer section comprising a plurality of axially spaced radially disposed annular fins 90a having heat exchange tubes 76a extending longitudinally therethrough and the inner section comprising similarly arranged heat exchange tubes 76b and annular fins 90b. The outer end of each condensate return conduit 75a connects with a passage 83a in housing ring 8la and each of the passages 83a in turn communicate through passages 84a in the adjacent housing ring 79a with the adjacent ends of the tubes 76a of the outer pre-heater section. The opposite ends of the tubes 76a communicate through passages 85a in ring 80a with an annular manifold 86a in the ring 82a and the manifold 86a is also in communication, through passages 85b, with the adjacent ends of the tubes 76b of the inner pre-heater section. The other ends of the tubes 76b communicate through passages 84b in ring 79 _ with a manifold 83b in ring 8la to which are connected the inlet ends of several tubes of the boiler B. By this construction flow of condensate through the tubes 76a and 76b of the outer and inner sections of the pre-heater is in opposite directions to provide counterflow heat exchange with the combustion gases passing between the fins 90b and 90a of the pre-heater sections.

Referring to Fig. 14, a composite single chamber boiler l4l is provided in lieu of the coiled tube boiler B previously described. As shown in Fig. 14, the boiler l4l is of generally L-shape including a primary axially extending portion 142 and a radially extending smaller portion 143.

As in the case of the coiled tube boiler B, the radially disposed portion 143 of the single chamber boiler l4l provides adequate flame insulation and additional heat transfer to the liquid supplied to said boiler from the pre-heater.

From the foregoing, it will be apparent that the present invention provides a rotary boiler-combustor of novel design and construction capable of producing heat fluxes well above peak boiling level for normal gravity and characterized by a combustion chamber that provides a high degree of fuel-air mixing and produces a high convective coefficient, quiet combustion, high volumetric heat release ana pactness. The invention also provides a boiler-combustor in which ambient air leakage is inwardly to the combustion chamber and which is self-pumping. The boiler-combustor of the present invention also keeps the combustion temperatures down and minimizes the formation of nitrogen oxide so that there is very low pollution.

While certain embodiments of the invention have been shown and described, it is not intended to limit the invention to such disclosures and changes and modi ications may be made and incorporated as devised within the scope of the following, claims .

Claims (26)

1. A rotary boiler-combustor comprising: a cylindrical housing rotatable about its axis, a coaxial annular boiler extending circumferentlally of said housing and rotatable therewith, said housing and boiler adapted to be rotated at a predetermined speed to maintain in the boiler an annular body of boiler liquid having a liquid/vapor interface spaced a predetermined distance radially from said axis, means operable to rotationally drive the housing- boiler unit at said predetermined speed, means defining an annular combustion zone circumscribing said rotary boiler comprising a stationary annular partition spaced radially outward from the boiler, means for supplying combustion fuel and air to the combustion zone, rotation of said housing-boiler unit relative to the surrounding combustion zone being operable fuel air to mix said combustion afia and £u©l and provide the desired combustion fuel-air mixture in said zone , means to ignite said fuel/air mixture in said combustion zone and cause combustion thereof to heat the liquid in the boiler and generate pressure vapor therein, a stationary hood structure circumscribing the rotatable housing-boiler unit defining a combustion gas exhaust chamber surrounding the stationary partition member in radially spaced relation thereto, a pre-heater for liquid supplied to the boiler rotatable with said housing-boiler unit and comprising an array of a plurality of axially spaced coaxial annular fins having a plurality of parallel heat exchange tubes extending longitudinally therethrough, said pre-heater being disposed circumferentially of the housing in radially spaced circumscribing relation to said stationary partition member and operable at said predetermined speed of rotation to pump said combustion gases through the pre-heater to the surrounding combustion gas exhaust chamber, and means for supplying boiler liquid through said pre-heater heat exchange tubes to the boiler at a predetermined rate correlated to the rate of vaporization of the liquid in the boiler to maintain the liquid/vapor interface in the boiler at said predetermined distance from the rotation axis of said housing-boiler unit.

2. A rotary boiler-combustor as in Claim 1 wherein the boiler comprises an axially extending portion and a substantially radially extending portion disposed to provide flame insulation and additional heat transfer to the liquid supplied to the boiler.

3. A rotary boiler-combustor as claimed in Claim 1 wherein the boiler is of tubular construction comprising a plurality of tubes of equal length coiled sequentially and arranged circumferentially relative to each other so that their respective inlet and outlet ends are disposed at equally spaced intervals circumferentially about said boiler.

4. A rotary boiler-combustor as claimed in Claim 2 wherein the boiler is of tubular construction comprising a plurality of tubes of equal length coiled sequentially and arranged circum erentially relative to each other so that their respective inlet and outlet ends are disposed at equally spaced intervals circumferentially about said boiler, the inlet end portion of each of said tubes being disposed in the radial portion of the boiler and the remainder of each of said tubes and the outlet end thereof being disposed in the axial portion of said boiler.

5. · A rotary boiler-combustor as claimed in Claim 1 wherein the stationary annular partition defining the combustion zone comprises a plenum chamber for supplying secondary air to said combustion zone.

6. A rotary boiler-combustor as claimed in Claim 5 wherein the secondary combustion air plenum chamber is defined by inner and outer radially spaced concentric plate portions and said inner plate portion is provided with apertures for discharging secondary air from the plenum chamber to the combustion zone.

7. A rotary boiler-combustor as claimed in Claim 1 wherein the annular fins of the pre-heater have a predetermined inner and outer radii ratio and the axial spacing of said fins is correlated to the speed of rotation of the housing-boiler unit and viscous properties of the combustion gases to have a Taylor number operable at said fin radii ratio to convey and accelerate said combustion gases by viscosity shear forces spirally outward between said fins to the surrounding combustion gas exhaust chamber substantially at the velocity providing optimum heat exchange between said combustion gases and the boiler liquid in the heat exchange tubes of the pre-heater.

8. A rotary boiler-combustor as claimed in Claim 1 having a condenser for the vapor generated in the boiler mounted coaxially adjacent the housing and rotatable with said housing-boiler unit, and means for delivering said vapor to the condenser and for returning condensate therefrom through the pre-heater to the boiler.

9. A rotary boiler-combustor as claimed in Claim 8 wherein the housing includes means defining an annular coaxial chamber therein for receiving pressure vapor from the boiler, the condenser is connected to said chamber to receive pressure vapor therefrom and return boiler liquid condensate thereto, and means is provided for returning said condensate from the chamber to the pre-heater and boiler.

10. A rotary boiler-combustor as claimed in Claim 8 wherein the condenser comprises a plurality of annular axially spaced radial fins having a plurality of heat exchange tubes extending longitudinally therethrough.

11. A rotary boiler-combustor as claimed in Claim 10 wherein the condenser fins have a predetermined inner and outer radii ratio and the axial spacing between said fins is correlated to the speed of rotation of the housing-boiler unit and the viscous properties of the condenser cooling fluid to have a Taylor number operable at said fin radii ratio to convey and accelerate said cooling fluid by viscosity shear forces spirally outward between said fins to the velocity providing optimum heat exchange between the condenser cooling fluid and the vapor in the condenser heat exchange tubes .

12. A rotary boiler-combustor as claimed in Claim 11 wherein the annular fins of the pre-heater have a predetermined inner and outer radii ratio and the axial spacing between said fins is correlated to the speed of rotation of the housing-boiler unit and the viscous properties of the combustion gases to have a Taylor number operable at said radii ratio to convey and accelerate said combustion gases by viscosity shear forces spirally outward between said fins to the surrounding combustion gas exhaust chamber substantially at the velocity providing optimum heat exchange between said combustion gases and the boiler liquid in the heat exchange tubes of the pre-heater.

13. · A rotary boiler-combustor as claimed in Claim 1 wherein the means for discharging a combustible fuel into the combustion zone comprises an annular liquid fuel distributor and an atomizing ring rotatable with the housing-boiler unit, and said atomizing ring is constructed and operable to discharge a mist of fine droplets of said fuel axially into said combustion zone circum erentlally thereabout.

14. A rotary boiler-combustor as claimed in Claim 1 wherein axially spaced opposite sides of the stationary hood structure are provided with inwardly facing cylindrical sealing ring portions disposed in spaced confronting coopera-tive relation to cylindrical peripheral surface portions of the rotary housing.

15. · A rotary boiler-combustor as claimed in Claim 14 wherein the operating pressure in the combustion zone is below atmospheric pressure and ambient air leakage is axially inward between the confronting sealing ring portions of the hood structure and housing respectively, whereby rotation of the housing-boiler unit relative to the combustor operates automatically to pump combustion air from the ambient atmosphere into the combustion chamber.

16. A rotary boiler-combustor as claimed in Claim 15 wherein conduit means is provided connecting from at least one of the confronting sealing ring portions to the combustion zone for conducting to the latter inwardly leaking ambient air and outwardly leaking combustion gases thereby supplying air for combustion to said zone and recirculating thereto combustion exhaust gases to reduce formation of pollutants and prevent exhaust gas leakage.

17. A rotary boiler-combustor as claimed in Claim 1 wherein the boiler liquid pre-heater comprises a plurality of radially spaced concentric sections each comprising a plurality of axially spaced annular fins having heat exchange tubes extending longitudinally therethrough, the connections are provided between said concentric sections so that flow of condensate through the tubes of adjacent sections is in opposite directions providing counterflow heat exchange with the combustion gases.

18. A rotary boiler-combustor as claimed in Claim 1, having an expander mounted coaxially with the housing for extracting work from the pressure vapor generated in the boiler and including a coaxial driving member rotatably driven thereby at a second predetermined speed, and means is provided for conducting pressure vapor from said boiler to said expander to drive said driving member.

19. A rotary boiler-combustor as claimed in Claim l8 , having drive means connected between the driving member and the rotary housing-boiler unit operable to rotationally drive said unit at said one predetermined speed.

20. A rotary boiler-combustor as claimed in Claim 19 wherein the drive means connected between the driving member and the housing-boiler unit comprises an occluded fixed-ratio gear train mounted coaxially within the housing, and there is means cooperable with said gear train opposing the reaction torque generated thereby so that the full power output of the expander is transmitted directly to the rotary housing-boiler unit.

21. A rotary boiler-combustor as claimed in Claim 4 wherein the stationary annular partition defining the combustion zone comprises a plenum chamber for supplying secondary air to said combustion zone.

22. A rotary boiler-combustor as claimed in Claim 21 wherein the secondary combustion air plenum chamber is defined by inner and outer radially spaced concentric plate portions and said inner plate portion is provided with apertures for discharging secondary air from the plenum chamber to the combustion zone.

23. A rotary boiler-combustor as claimed in Claim 21 having a condenser for the vapor generated in the boiler mounted coaxially adjacent the housing and rotatable with said housing-boiler unit, and means for delivering said vapor to the condenser and for returning condensate therefrom through the pre-heater to the boiler.

24. A rotary boiler-combustor as claimed in Claim 23 wherein the condenser comprises a plurality of annular axially spaced radial fins having a plurality of heat exchange tubes extending longitudinally therethrough.

25. - A rotary boiler-combustor as claimed in Claim 24 wherein the condenser fins have a predetermined inner and outer radii ratio and the axial spacing between the adjacent condenser fins is correlated to the speed of rotation of the housing-boiler unit and the viscous properties of the condenser cooling fluid to have a Taylor number operable at said radii ratio to convey and accelerate said cooling fluid by viscosity shear forces spirally outward between said fins to the velocity providing optimum heat exchange between the condenser cooling fluid and the vapor in the condenser heat exchange tubes .

26. A rotary boiler-combustor as claimed in Claim 25 wherein pre-heater fins have a predetermined inner and outer radii ratio and the axial spacing of the annular fins of the pre-heater is correlated to the speed of rotation of the housing-boiler unit and the viscous properties of the combustion gases to have a Taylor number operable at said radii ratio to convey and accelerate said combustion gases by viscosity shear forces spirally outward between said fins to the surrounding combustion gas exhaust chamber substantially at the velocity providing optimum heat exchange between said combustion gases and the boiler liquid in the heat exchange tubes of the pre-heater.