(19)
(11) EP 0 040 748 A1

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
02.12.1981 Bulletin 1981/48

(21) Application number: 81103592.2

(22) Date of filing: 11.05.1981
(51) International Patent Classification (IPC)3F01K 27/00, F24H 1/40, F24H 9/00
(84) Designated Contracting States:
CH DE FR GB LI

(30) Priority: 21.05.1980 IT 2223180

(71) Applicant: Scalfi, Bruno
I-25080 Muscoline Province of Brescia (IT)

(72) Inventor:
  • Scalfi, Bruno
    I-25080 Muscoline Province of Brescia (IT)

(74) Representative: Modiano, Guido, Dr.-Ing. et al
Modiano & Associati S.r.l. Via Meravigli, 16
20123 Milano
20123 Milano (IT)


(56) References cited: : 
   
       


    (54) High efficiency boiler structure


    (57) A boiler comprising, located above the combustion zone, a tube nest (3) wherethrough a high expansion primary thermal fluid is circulated. The tube nest extends between a lower manifold (4) and upper manifold (5) which is connected to the primary fluid inlet end of a counter-current heat exchanger (6) the outlet whereof is connected to said lower manifold (4). The heat exchanger (6) is provided at the bottom with an inlet fitting (10), and at the top with an outlet fitting (11) for the thermal exchange secondary fluid.
    Moreover, there is interposed in the circuit of said primary fluid a turbine (20) driven by the natural circulation flow of said primary thermal fluid, and operative to generate valuable power, such as electric power.




    Description


    [0001] This invention relates to a high or optimized efficiency boiler structure.

    [0002] As is known, a currently much felt problem is that of sparing energy, and this problem particularly affects the manufacture of boilers, which have had heretofore a considerably low thermal efficiency in that they could not make full use of the heating power of both the fuel and thermal exchange fluid.

    [0003] Accordingly the task of this invention is to eliminate the shortcomings of prior boilers by providing a boiler structure of optimized performance, which can favor, through simple and readily implemented means, a maximal delivery of heat by the flue gases to the thermal exchange fluid, and also enable the recovery of valuable power from the thermal exchange fluid.

    [0004] Within said task it is an object of the invention to provide an optimized performance boiler structure which is comparable, construction-wise, to traditional boilers, but has the advantage of exhibiting - operational features which appreciable improve its efficiency.

    [0005] Another object of this invention is to provide a boiler of small overall size and with low installation space requirements, thus enabling its utilization for standard domestic applications to interior space heating and the heating of water for sanitary use.

    [0006] Yet another object of the invention is to provide an optimized performance boiler structure which can be easily implemented from elements and materials readily available on the market, and is highly competitive from an economical standpoint.

    [0007] The aforesaid task and objects and other objects, such as will be apparent hereinafter, are achieved by an optimized performance boiler structure, characterized in that it comprises, located above the combustion zone, a tube nest wherethrough a high expansion primary thermal fluid is circulated, said tube nest extending between a lower manifold and upper manifold, said upper manifold being connected to the primary fluid inlet end of a counter-current heat exchanger the outlet whereof is connected to said lower manifold, said heat exchanger being provided at the bottom with an inlet fitting and at the top with an outlet fitting for a secondary thermal exchange fluid, in the circuit of said primary thermal fluid there intervening a turbine driven by the natural flow of said primary thermal fluid..

    [0008] Further features and advantages will be more clearly understood from the following description of a preferred but not limitative embodiment of an optimized performance boiler structure, as illustrated by way of example only in the accompanying drawing, the one figure whereof show a schematical layout of the boiler structure according to the invention.

    [0009] With reference to the drawing figure, the optimized performance boiler according to the invention comprises a body 1, preferably but not necessarily arranged to extend vertically, which has at its bottom portion a combustion zone which may be especially designed for either solid fuels, liquid fuels, gaseous fuels, or to provide a so-called combination boiler.

    [0010] The cited body 1 is equipped, at the upper or top portion thereof, with a conventional flue 2 for discharging smoke and combustion products.

    [0011] Inside said body 1, above the cited combustion zone, there is provided a tube nest including a plurality of tubes 3 which extend preferably parallel to one another in a substantially vertical direction.

    [0012] The cited tubes 3 extend from a lower manifold 4 to an upper manifold 5, which is accommodated, similarly to the manifold 4, within the body 1.

    [0013] Advantageously, both the lower manifold 4 and upper manifold 5 have a substantially spherical configuration, and the tubes 3 are connected to the upper hemisphere of the lower manifold 4 and to the lower hemisphere of the upper manifold 5.

    [0014] Through the cited tube nest, as well as through the manifolds 4 and 5, there is circulated a high expansion primary thermal fluid, which may be, as a non-limitative example, water.

    [0015] The upper manifold 5 is put into communication with a counter-current heat exchanger, indicated at 6. More in detail, the upper manifold 5 is connected to the inlet of a primary conduit 7, whereas the lower manifold 4 is connected to the the outlet of the cited primary conduit 7.

    [0016] The primary conduit 7 has on its outer surface fins 8 or other suitable elements for increasing the surface area of thermal exchange.

    [0017] The primary conduit 7 is located inside a container 9 for the passage of the secondary thermal exchange fluid. More specifically, the thermal exchange container 9 is provided, at the bottom portion thereof, with an inlet fitting 10 for the secondary thermal exchange fluid, and at the top, with an outlet fitting 11 for the secondary thermal exchange fluid; thus, a counter-current thermal exchange relationship is established between the primary fluid circulated through the conduit 7 and secondary fluid circulated through the container 9.

    [0018] Moreover, the provision of the fins 8 or other suitable elements for increasing the useful surface area of the conduit 7 greatly facilitates the exchange of heat, and may induce turbulent flow to further improve the delivery of heat from the primary fluid to the secondary fluid, which can be utilized for a standard home heating system or sanitary system.

    [0019] At the outlet of the primary conduit 7, located at the connection area to the lower manifold 4, there is provided an automatically operated one-way. check valve, indicated at 12, which serves the function of ensuring that the primary fluid is circulated in one direction.

    [0020] The direction of flow of the primary thermal fluid is dictated, first of all, by the arrangement of the manifolds within the.body 1, in that the lower manifold is obviously swept by hotter gases and thus generates a more powerful heating of the primary thermal fluid, which will tend to migrate toward the upper manifold; this direction of circulation is further enhanced by that the heat exchanger operates 'in counter-current, thereby upon cooling, the primary fluid will tend to flow down toward the outlet portion of the primary conduit 7, thus increasing the natural circulation velocity of the primary thermal fluid in the primary circuit.

    [0021] A peculiar feature of the invention resides in that the primary thermal fluid circulation circuit includes a turbine, indicated at 20, which is driven by the aforesaid natural circulation.

    [0022] More in detail, the turbine 20 is accommodated inside a plenum chamber 21 whereinto an inert gas is introduced from above which is at a higher or possibly equal pressure than the primary thermal fluid, thereby the turbine is swept by the flow of primary thermal fluid only at the bottom portion thereof, i.e. at the portion located below its axis of rotation, to thus ensure that the turbine can only rotate in one direction.

    [0023] The turbine 20 may be connected to a generating unit of conventional design, thus enabling the recovery of valuable energy, such as electric energy, from the thermal exchange fluid.

    [0024] Downstream of the plenum chamber 21, which advantageously intervenes between the upper manifold 5 and the inlet to the heat exchanger 6, there is located a vent 22, which constitutes a protection measure against any potential risk in the operation of the boiler.

    [0025] The operation and utilization of the boiler will be apparent from the foregoing description. In fact, the combustion or flue gases, in sweeping past the lower manifold 4, as well as the tube nest 3 and upper manifold 5, cause a considerable raise of the primary fluid thermal power, which primary fluid is conveyed by natural circulation into the counter-current heat exchanger 6, where it delivers its thermal energy to the secondary fluid.

    [0026] Furthermore, this same natural circulation, which is determined and enhanced by the primary fluid being a high expansion fluid, is also utilized to drive the turbine 20, which is thus enabled to generate high amounts of valuable power.

    [0027] From the foregoing description, it will be appreciated that the invention achieves its objects, ,and in particular the fact is stressed herein that by providing a turbine in the circuit of natural circulation of the primary thermal fluid, the efficiency or useful- output of the boiler according to the invention is substantially improved, through the exploitation, in practice, of the kinetic energy of the thermal exchange fluid, which energy, in conventional design boiler structures, is virtually wasted.

    [0028] The invention as described and illustrated is susceptible to many modifications and variations, without departing from the purview of the instant inventive concept.

    [0029] Moreover, all of the details may be replaced with other technically equivalent elements.

    [0030] In practicing the invention, the materials used, provided they are compatible with the specific application, and the dimensions and contingent shapes may be any ones, depending on individual requirements.


    Claims

    1. An optimized performance boiler structure, characterized in that it comprises, located above the combustion zone, a tube nest (3) wherethrough a high expansion primary thermal fluid is circulated, said tube nest extending between a lower manifold (4) and upper manifold (5), said upper manifold (5) being connected to the primary fluid inlet end of a counter-current heat exchanger (6) the outlet whereof is connected to said lower manifold (4), said heat exchanger (6) being provided at the bottom with an inlet fitting (10) and at the top with an outlet fitting (11) for a secondary thermal exchange fluid, in the circuit of said primary thermal fluid there intervening a turbine (20) driven by the natural flow of said primary therma" fluid.
     
    2. An optimized performance boiler structure according to Claim 1, characterized in that said tube nest comprises a plurality of tubes (3) extending parallel to one another in a substantially vertical direction.
     
    3. An optimized performance boiler structure according to the preceding claims, characterized in that said lower manifold (4) and upper manifold (5) have a substantially spherical configuration, said tube nest (3) extending from the upper hemisphere of said lower manifold (4) and being connected to the lower hemisphere of said upper manifold (5).
     
    4. An optimized performance boiler structure according to one or more of the preceding claims, characterized in that said heat exchanger (6) comprises a primary conduit (7) provided with fins (8) for increasing the heat exchange surface area thereof, said primary conduit (7) being enclosed within a container of the secondary thermal fluid.
     
    5. An optimized performance boiler structure according to one or more of the preceding claims, characterized in that said turbine (20) intervenes between said upper manifold (5) and said counter-current heat exchanger (6).
     
    6. An optimized performance boiler structure according to one or more of the preceding claims, characterized in that said turbine (20) is accommodated within a plenum-chamber (21) containing an inert gas at a higher, or at least equal, pressure than the pressure of said thermal exchange fluid to confine the contact of said thermal exchange fluid with said turbine (20) to an area included below the rotation axis of said turbine (20).
     
    7. An optimized performance boiler structure according to one or more of the preceding claims, characterized in that it comprises a venting valve (22) located downstream of said plenum chamber (21).
     




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