US2183893A - Fluid heater - Google Patents

Description

Dec. 19, 1939. N. c. PRICE FLUID HEATER vFiled Jap. 12,v 1937 mnmyy@ munmwn :Aulwll l l l l l l l l l l l I I l l l l l I I l l l l l ll Patented Dec. 19., 1939 UNITED sTATl-:s PATENT ol-Flcs Nathan C. Price, Berkeley, Calif., assignor to vSirius Corporation, a corporation of Cantornia"A IAppumiml January 12, 1931, serial 10.120,188 v is claims. (ci. 12a-zsm The invention relates to fluid heaters and particularly to vapor generators such as steam boilers employing liquid or gaseous fuel as the heating medium.

An object of the invention is to provide a vapor generator which is particularly applicable for uses where lightness and compactness is of importance, such as in moving vehicles.

Other objects which are to be satisfied comprise, first,l attainment of effective thermal counteriiow between gases of combustion and ythe working fluid for high efficiency, second, ability to pre-heat the air fed to the combustion chamber in a manner which will reduce the amount of boiler insulation required and which will entail v a minimum of structural material, third, ease of inspection of all heated-surfaces and simplicity of construction, fourth, properl support of the heated surfaces to allow free thermal expansion and contraction eliminating harmful temperature stresses, fifth, ability to withstand explosions in the combustion chamber without structural damage, sixth, proportioning of much 'greater heat transfer area to the gases of combustion than to the working fluid thereby reducing the weight per vapor output ratio of the boiler and lessening heat storage, seventh, convergence of combustion gas flow passages in the direction of ow to establish substantially constant heat transfer from the inlet to the -outlet c-f the boiler, and eighth, integration ofthe air supply system with the boiler# The invention possesses other advantageous features which are evident in the illustrated form accompanying the following specifications.

Figure 1 is a section through the principal axis of one form of the invention showing a cylindrical vapor generator integrally combined with its air preheater, fuel injector, fuel igniter, and air supply pump in,y a manner providing advantageous relationship between the various elements. /f/

Figure 2 is a quarter end view of Figure 1, re

vealing a fragment of section normal to the principal axis as designated bythe letter A in Figclose-wound superheater helical `coil Il, a convergent combustion gas conducting space I5, a convergent cylindrical combustion shroud Il, and a combustion chamber 3|.

Feed liquid is supplied to the inlet 4- of the economizer co'il I1, which comprises a tube 23 with numerous spaced circular fins thermally bonded thereto.

At a region 34 the coll I1 is serially joined to the coil I4 and conducts evaporating working iiuid thereto. Progressivesuperheating of th working fluid is accomplished in the coil I4 and in a serial close-wound coil I3, which is both conical and spiral. The conditioned working fluid is discharged from an outlet duct 5 to the con-- sumer. f

chamber i and vignition regulation for this boiler is fullyv shown in my Patent No. 2,064,494 entitled "Control system."

The heating system illustratedI in Figure 1 includes an electric motor I for rotating a centrifugal blower impeller 2. Supply air enters an inlet 5 and is discharged into a diffuser 3` for partial conversion of velocity head to pressure head.

The diffuser 3' is formed as a heat exchanging structure, which is integral with a series of flues I8. It also comprises a -boiler end plate 22 to which the'envelcpe I0 is mechanically joined.

The iiues I8 are shaped and angularly posi-I tioned to form a tangential and divergent arrangement of diffuser vanes for high efficiency.

Furthermore a structurally sound boiler end plate is produced since the iiues 'I8 act as stiftening webs. The blower imponer-2 is placed in an ideal position from the standpoints of directness of discharge and compactness.

The partially heated airleaving the diffuser 3'is directed along the air preheating duct l to extract more heat` from the envelope Ill, and finally passes at a relatively high temperature through s'orne ns Sinto the combustion chamber 3I.

The fins 9 are formed-tangent to a' ircle about the boiler principal axis B in order to impartv a twist to the incoming air as shown in Fig. 3. l

The resultant rotating mass of air strikes a fuel spray envelope 21 issuing frcmla mechanical atomizing burner nozzle 30 of centrifugal type. Integralwith the burner nozzle 30 are a fuel supply line 23, and an ignition plug 23 forllghting thc fire. y Preferably the'rotation af the fuel spray en velope is made opposite to that of the incoming' air, to produce thorough mixing. However, the

heater duct 1, the heated inner portions of theY boiler, such as the coil I4, the coil I1, and the moment of momentum 'ofthe air is greater .than that of all the fuel droplets. A net rotation of the mixture results. y,Large droplets of fuel which burn slowly tendto become forced centrifugally against the hot shroud Il, where they rapidly vaporize and do not reach the boiler tubing.

The gases of combustion issue from the slightly conical chamber 3| and are deflected by a sea1` ing disc I2 and the coil I3. Reversed direction flow along the space I5 results;

The space I5, bounded by the coil I4 and the shroud II, is made convergent in direction of flow in order to maintain approximately the same rate of heat transfer throughout the entire length of the inner side of the coil I4. L

When the gases of combustion reach the region 34, they are again reversed in direction of flow by a flange 35 of the shroud`II, and pass betweenthe ns 24, the coil I4, and the envelope I to be finally discharged from the ues I8. A naturally high heat transfer exists between the liquid inthe coil I1 and the inside of the tube 23 due to the -thermal conductivity characteristi'cs of liquids, while the gases of combustion on the otherhand have intrinsically poor heat conductive capabilities.

Therefore, there is a considerable economy realized in material and space by utilizing means for obtaining of a much greater heating surface to the gases of combustion than to the economizer liquid. This is aprimary function of the ns 24.

Furthermore, the fins serveas spacing means between adjacent loops of the coil I1, and between the coil I4 and the envelope I0.

Due to the free space constituting the air preenvelope I0, are able to expand radially as temperature changes occur.

, The combustion chamber shroud II is capable of expanding in all directions due to the space I5 surrounding it.

The various loops of the coil I3 are also `free to expand due to the conical shape of the spiral.

For supporting the inner portions of the boiler axially, some spacing blocks 32 mechanically iix the periphery of the coil I3, to the boiler end plate 22. Some studs I 9 threaded into the casing 8 serve with their nuts 20,and so'me coil springs 2| to hold a sealing slip-joint 33 between the casing 8 and the plate 22, at a minimum gap.

Accordingly the casing 8 producesaxial pressure through the tangential fins 9 upon the flange 35 of the shroud II. This flange bears upon the coil I1 and the coil I4 which in turn compress the periphery of the spiral coil I3.

The flange 35 is Vsealed to the envelope I0 by a slip-joint 26.

.Therefore, as the temperature of.-the inner portionof the boiler increases relative to that of the casing 8, differential expansion along the principal axis B is permitted by the resultant compression of the springs 2|.

Likewise in event of .delayed ignition in the combustion chamber and a subsequent explosion, the springs 2l act as energy absorbing members to prevent rupture of the boiler casing. Also it is provided that underthis condition the casing 8 may be moved so far axially from the plate 22, that direct pressure relief passages for gases are created through the slip-joint 26 and the slipjoint 33.

Above the broken Aline is revealed a section of Figure 1 taken at the letter A in Figure 1. Below the broken line an .external end view is presented.

In Figures 1, 2, and 3 I have illustrated one form of uid heater embodying my invention, but as set forth in the claims, it may be embodied in a plurality of forms.

I claim: 1. A boiler comprising a cylindrical envelope surrounding in substantially coaxial relationship and in the following sequence in the direction of the axis, an economizer tube helical coil having fins extending from the surface thereof, a smooth superheater tube helical coil, and a combustion chamber, said last named coil and said envelope defining a combustion gas flow path between said fins and parallel'to said axis, means for supplying feed liquid to said economizer coil, and said super heater coil being connected to said economizer coil for heating vapor of said liquid.

2. In apparatus of the character described in claim 1, said fins abutting said superheater tube coil and thereby aligning said superheater coil with respect to said economizer coil.

3. In apparatus of the characterdescribed in claim 1,. a. cylindrical refractory shroud surrounded by said superheater coil and bounding said` combustion chamber, an annular space lying between. said shroud and said superheater coil for conducting gases of combustion from said chamber in counterflow to the boiler working fluid in said superheated coil, and said space converging in the direction of ow of said gases thereby maintaining the heat transfer to said superheater coil substantially constant along th'e tubular length of said superheater coil.

4. In apparatus of the character described in claim l, said envelope being heat conductive, a cylindrical boiler .casing surrounding said envelope, an annular duct lying between said casing and said envelope for preheating air for said combustion chamber, and means for forcingsaid 'air' to flow in said duct counter toand in heat transferring relationship to the gases of combustion passing between said fins. l

5. In apparatus of the character described in claim l, said envelope beingheat conductive, a cylindrical boiler casing surrounding said envelope, an annular duct lying between said casing and said envelope for preheating air for said combustion chamber, a blower for forcing said air along said duct counter to and in heat transferring relationship to the gases of combustion passing between said fins, and means for imparting a rotary motion about the boiler axis to said air thereby increasing the absorption of heat from said gases of combustion.

6. In. apparatus of the character described in claim l, said envelope being heat conductive, a cylindrical boiler casing surrounding said envelope, an annular duct lying between said casing and said envelope for preheating air for said combustion chamber, a compressor' for forcing said air along said duct counter to and in heat bustion passing between said iins, and a tangential flow passage connecting said duct to said combustion chamber for producing an air swirl about the boiler axis in said chamber.

'7. In apparatus of the character described in claim 1, said envelope being heat conductive. an annular duct extending about said envelope for preheating air for said combustion chamber, a cylindrical boiler casing surrounding said duct,

a compressor for forcing said air along said duct in counterfiow to and in heat transferring-relationship to the gases of combustion passing between said lns, means for imparting a rotary motion `about the boiler axis to said air thereby increasing the heat transmission from said gases to said lair, and a tangentialilow passage communicating between said duct and said chamber coincident in direction tothe rotary motion in said duct. 1

8. A boiler tube comprising, a cylindrical boiler casing surrounding in substantially coaxial relationship and in sequence in the directionof the axis of said casing, an annular air preheating duct, a cylindrical heat lconductive envelope, a finned economizer tube helical coil,-a -smooth L y superheater tube helical coil having closely wound loops for heating vapor of said liquid, and a cylindrical combustion chamber, means for forcing feed liquid into said economizer coil, a flow passage extending from said chamber along said superheater `coil for heat contribution thereto,V

and an extension of said passage along said economizer coil and said envelope for heat contribution thereto.

` 9. In apparatus of the character described in claim 8, a centrifugal blower, a diffuser ,for said blower constructed of spaced plates, said plates having hollows, and means for conducting gases of combustion from said extension through the hollows in said plates.

10. A boiler comprising, a cylindrical boiler casing surrounding in substantially coaxial relationshipl and in sequence in the direction of the axis of "said casing, an annular air preheating duct, a cylindrical heat conductive envelope, a boiler tubehellcal coil, and a combustion chamber, a pump for forcing feed liquid into said coil, a centrifugal combustion airimpeiler at one end of said duct, said impelle'r having an axis of rotation coincident with the axis of said casing, a diffuser for said impeller constructed of spaced plates arranged tangentially about the periphery of said impeller, said plates having hollows, a iiow passage extending from said chamber along said coil for heat contribution thereto, and said passage being connected to said hollows.

11. A forced circulation boiler comprising a long once-through boiler tube having an inlet at one end thereof, an outlet at the other end theref, and a change of state zone intermediate'of said ends, said tube being directly` exposed to`I flow of gases of combustion along substantially the entire length thereof from said inlet endrto said outlet end, feed liquid alimentation means. at said inlet, working vapor disposal means atv said outlet, a cylindrical envelope encompassing said tube. a combustion chamber for producing said gases, said chamber communicating with the interior of said envelope, an air compressor connected to said chamber, said tube having a relatively constant internal diameter along its length from said inlet to said outlet, said liquid having a relatively high thermal conductivity, said vapor having a relatively low thermal conductivity, finlike projections on. the surface of said tube,` and said projections being substantially proportionate to th`e thermal conductivity of `the iluid being conveyed within said tube opposite thereto at each increment of the tube length.

` 12. kA boiler` comprising a first helical boiler tube having heat conductive fins on the external 7surface thereof, a ow passage between saidv fins.'-

for forcing said fluid along said passage, anda second helical boiler tube closely bounding said passage on one lateral side thereof.

13. A boiler comprising a boiler tube helical coil containing liquid and having a plurality Vof heat conductive i'lns extending from the external surface thereof, said fins being disposed trans-vl versely to the axis of Isaid tube, a cylindrical envelope abutting said ilns at one lateral side of the` edges of said fins, a boiler tube system containing vapor and abutting said iins at the'opposite'lateral side of the edges of said fins, means for proa tube and abutting the edges of said ilns atthe outward side of said fins, a combustion chamber,

ducing -a relatively hot fluid, and a displacer for;` v

an annular duct lying between said casing and said envelope for preheating combus n air for said chamber, a close-wound superhe ter tube helix encompassed byfsaid economizer tube and abutting the edges of said ns at the inward side ofl said fins, anair compressor connected to said duct, and said combustion chamber being connected to the space between said iins.

15. A boiler comprising. a'cylindrical combustion chamber,` a helical boilerA tube system surrounding said chamber, an annular air duct surrounding said system, an imperforate cup-shaped casing surroundingsaid duct and having a conoidal end projecting into said chamber, an air compressor connected to one end of said duct,

a disc-shaped passage connecting the oppositel end of said duct to said chamber, a plurality of tangential vanes in said passage, and a fuel injection nozzle facing into said .chamber at the center of said end. NATHAN C. PRICE.

means for producing a relatively hot iluid, a pump v

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