US2840148A - Pressure oil burner for heavy oil - Google Patents

Description

June 24, 1958- l. w. AKESSON PRESSURE OIL BURNER FOR HEAVY OIL ATTORMX l VAR w41 DIF/'MR Al'ssqN June 24, 1958 w. AKl-:ssoN 2,840,148

PRESSURE OIL BURNER FOR HEAVY OIL Filed Dec. 6, 1955 5 Sheets-Sheet 2 nir.. n

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l VRR VANDEN/9K AKESSOIY /aadm ATTOR/VEK June 24, 1958 l. w. AKESSON 2,840,148

PRESSURE OIL BURNER FOR HEAVY OIL' Filed Deo. 6, 1955 3 Sheets-Sheet 3 INVEN TOR. VAR WMDSnARAKsssa/v daheim United States Patent 2,840,148 y PRESSURE oir BURNER Fon HEAVY OIL Ivar Waldemar Akesson, Goteborg, Sweden, assignor to Chalmers Products Aktiebolag, Goteborg, Sweden, a Swedish joint-stock company Application December 6,1955, Serial No. 551,428

7 Claims. '(Cl. 158-76) v This invention relates to heavy-oil consuming pressure oil burners of the type provided with an oil pump and a primary air fan which, during operation of the burner, generates a primary current of air through an air pipe in the front portion of which a `burner head with a spraying nozzle for the oil is essentially centrally `arranged. Such pressure oil burners are also provided with anv oil preheater, in which the oil is heated before being fed to the spraying nozzle in the burner head for distribution into the primary air current.

ln known heavy-oil burnersy of this type, `the preheater normally forms a separate unit placed outside the burner and connected to it by means of a complicated pipe systemy Besides complicating the mounting of the burner and increasing the space requirements, this location of the preheater outside the burner and the consequential, often rather long oil conduit between the preheater outlet and the burner nozzle; gives rise to a difcult problem, since the oil contained in this oil conduit will cool off during interruptions in the operation of the burner, so that it will become increasingly diliicult to light the llame yagain when re-starting, and much smoke will develop- Furthermore, .the oil also cools down inY an uncontrollable way during operation, on its way from the preheaterto the nozzle, so that it is diicult to obtain a uniform and complete combustion of the oil despite the preheating. f

Previous efforts to solve this problemfhave mainly been concentrated on theprovision of means for heating the pipe connecting the preheater outlet with the burner nozzle, such as, for example, by providing said pipe with al jacket through which hotwater is passed, but such means have always served to still further complicate the plant.

The main object of the present invention is to solve this problemin a way which ismoreA satisfactory from i several points of view, by the provision of a heavy-oil consuming pressure oil burner of the type comprising a primary air fan, which generates, during the operating of the burner, a primary air stream through an air pipe, in the front portion of which is substantially centrally arranged a burner head with a nozzle for spraying oil fed to it by an oll pump, and an oil preheater enclosed in the air pipe for heating the oilbefore it is distributed into the primary air streamby the spraying nozzle. The main feature of the invention is that the oil preheater consists of a spacious and elongated oil chamber of annular cross section, which is disposed centrally in the airpipe and supports, in its front end, the burner head, while its'rear end` is provided with an oil outlet, the oil chamber enclosing anV oil feed pipe, which is connected to the spraying nozzle and whose rear end is detachably connected with the oil outlet of the oil chamber, fand which can be pulled out together with the spraying nozzle rearwards through the oil chamber. This arrangement ensures that the oil cools off only in an inconsiderable degree while* passing from the fice preheater to the nozzle, and at the same time the-construction of the heavy-oil burnertis very much simplilied. Apart from this, all heat supplied to the preheaterk is utilized elfectively, as heat radiated from the preheater is absorbed by the primary air flowing to the burner head. The oil burner arranged as above has a compact design and the installation is simplified, while the shaping diiculties, which cannot be neglected, are at the same time reduced. Y In order that the invention may be moreY clearly, understood, one preferred embodiment'thereof will now be described by way of example with reference to the accompanying drawings in which: v

Fig. l is a longitudinal section through the air pipe, oil preheater and burner head of an oil burner embodying the invention,

Fig. 2 is a cross section through the air preheater along the line II--II in Fig. l, l

Figs. 3, 4, 5 and 6 are enlarged detail viewsof a portion of Fig. l illustrating the functioning of a valve device contained in the burner head, and

Fig. 7 is an enlarged detail view of another portion of Fig. l.

The heavy-oil burner shown in the drawings comprises a stand 1 carrying a casing 2, in whose upper part there are provided a primary air fan 3 and an oil pump connected to the latter and represented schematically at 49 on Fig. l, which are both driven by a common motor (not shown in the drawing). The fan 3 generates a primary air stream, which passes to the burner head through an air pipe 4 provided below the fan and continues into the boiler. An air turbulator 5 is tted around the burner head. The fuel oil is distributed in the primary air stream by means of a spraying nozzle 6 that-is likewise mounted at the burner head and to which the oil is fed by means of the-pump 49, Vso that the oil discharges from the nozzle 6 under a predetermined pressure. v 'f Placed centrally in the air pipe 4 is an oil preheater 7 of annular or approximately annular cross section. The rear end of the oil preheater 7 is connectedwith a rear end wall 8 of the air pipe 4, while the front end of the Vpreheateris connected with a tubular jacket 9, which forms the burner head where the nozzle 6 is flocated and where a suitable ignition device 10 is also placed. The jacket 9 has a constricted front portion kpipe and oil and suitable air holes 9' forming passages for admitting are arranged at the lower part of the rear end wall 8 Y of the air pipe. In the oil preheater 7, which serves as an oil chamber, the oil is heated by means of the-heating element 12 to a temperature that is regulated by means of suitable thermostats, for' instance of the type shown at 13. From the pump 49 the oil'is conveyed by a pipe 50 through the hole 14 in the end wall 8 Vand through a pipe 15 extending from the end wall 8 forwards through the oilV preheater 7 and opening near the front end of the oil preheater. After heating in the preheater 7 the oil ows through an outlet port 16 also located in the end wall S, where a spring-loaded ball valve 17 (Figs. 1 and 7) is provided to prevent oil discharge when the pump 49 is at rest.

Of courseit is also possible to let the oil pass in opposite direction through the preheater, the pipe 15 then being removed from the hole 14 and being mounted instead as an extension to the outlet 16, so that the heated oil enters the pipe 15 near the front end of the preheater for discharge through the outlet 16. Thus, the direction,

Patented June 24, s.

. 3' of flow of the oil through'the preheater is not critical, but it is-important that the oil be Amade to flow along a relatively long path and thus remain a substantial time in the preheaterso as to be thoroughly heated to the correct working" temperature.

""Insertedthrough the central axial"`hole`"or b'ore 18 of the'oilpreheater 7 `is `afnozzle tube 19, 'in the' front end o'fwhich thenozzle with oiljstrainer `6' (Fig. 3) is placed. JArrangedconcentrically in the'nozzle tube 19 is another tube 20, of substantially smaller diameter, that serves asareturn conduit for oil from the front end of theynozzle'tube '19 and anannular space 19a defined between tubes 19 and 20 serves as afeed conduit for the oil from the preheater 7 to the nozzle 6. In the front end'ofthenozzle tube 19 immediately' behind the nozzle 6 is provided a 'quick-action valve 21, which also serves as a reducing valve and cooperates with the point of an electro-magneticallyA controlledvalve `needle 22 which extends Vthrough the full length `of return tube 20, so that the oil can circulate through the preheater 7 and all the wayto the-nozzle 6and from the latter back to the pump `49, without passing out through the nozzle, until the properoperating-temperature of the oil is obtained.

Thisvalve arrangement willlbe fully described hereafter.

The rear endof the nozzle tube 19 is provided with a head 25 (Figu') having two spaced channels 26 and 27, which communicate with the ,space 19a `between the nozzle tube19and the return tube 20, and with the interior `of the return tube respectively. The mouths of the channels 26 `and 27 are adapted to seal against suitable connectionupieces 28 on the rear side of the end wall 8 when `thenozzle `tube 19 is inserted through the preheater, sothat the head substantially rests against the rear side of the end wall 8. In this way `the space 19a between nozzle tube 19 and return tube 2t) is connected, through the channel26, with the out1et16 of the preheater via therball valve 17, while the interior of the return tube120 `is connected through the channel 27 with an outlet `hole 29 fin the rearend Wall8 of the air pipe, whichahole 29 communicates with the suction side of the pumpfthrougha conduit 51. Thehead 25jalso carries the operating mechanism for the valve 'needle 22 and is held against thei outside ofthe end wall 8 by a clamp screw 30provided in araisable stirrup 31, which is hinged yin suitable manner `to the end wall 8. This arrangement` facilitates easy` detaching andwithdrawing of the nozzle `tube-19, so that thenozzle 6 and quick-action valve 2,1 in its frontend, can be inspected without dismantling the burner;-

Theval-ve needle' 22 is operated by means of a springloaded `electrornagnet.generally designated' by 32, which is` preferably controlledby a thermostat influenced by the oil: temperature in the preheater, Vfor instance, the thermostat 13. t

l The valvedevice 21 placed close behind the nozzle 6 serves both as-a Lquick-action valve to prevent oil with a pressure lower than a predetermined valueirom being fedloutV through` thernozzler, `and as a reducing valve to prevent therpressure of the oil fed to the nozzle from exceeding a predetermined value. VIn addition, the valve device 21 serves in combination with the electromagneticallyl-actuatedvalve needle 22, as a relief valve for the oil, so tha-t a circulation can be maintained through the oil ,preheater 7 until the` desired oil temperature is obtainedwhen startingthe `burnerand amomentary pressure drop can Vbe effected behind the nozzle `to ensure quick interruption of` the`,oil*feed through the nozzle and the effective prevention `of dripping of oil through the i nozzle after operation ofthe barrierV has halted.V The end `oflthevalve needle 22,'extending rearwardly from the head 25, is provided with a magnet armature 33, which `isdisplaceable in the forward directionby a` solenoid 37 against the action of a weak return spring 34 located ,inkapipe `cylinder 35. `The solenoid 37` isnlocated in a casing 36 wand: displaceably (mounted 1 about `the pipe t cylin- CIt , '4' der 35. The solenoid is movable in the rearward direction against the action of a compression spring 38. The pipe cylinder and the casing 36 for the solenoid 37 are supported by the head 25. When current is fed to the solenoid 37, the armature 33, and the valve needle 22, are displaced forwardly and, when the current is interrupted, the valve needle 22 is moved rearwards by the return spring` 34. The compression spring 38 permits the solenoid 37 to follow the movement of the armature 33 within narrow limits when the valve needle 22 is forced rearwards,.at the operation of the valve arrangement 21, in the manner explained below.

As is clearly apparent from Figs. 3-6, the valve arrangement 21 comprises a sleeve-shaped valve guide 40,

vwhich is rigidly connected to the front end of the return tube 20. A valve body 41 is displaceable in the valve guide 40 against the action of a compression spring 42. The front end of the valve body 41 cooperates with a seat 43' provided around a'flow inlet 44 in the rear end of the nozzle unit 6 which,I as already mentioned, is rigidly placed in the front end of the tube 19. The primary function of the valve arrangement is to prevent the oil conveyed bythe pump 49 through the space 19a between the tubes 19 and 20 past the valve guide 40, from flowing through the inlet 44 to the nozzle 6 until a predetermined oil pressure has been attained. This pressure is deter- Vmined by appropriate choice of the spring 42, and it will be obvious that the valve body 41 will be pressed rearwards when the appropriate oil pressure is obtained, and the inlet 44 thus laid'open (see Fig. 5).

The valve body 41 is provided'with a bore 45 extending diametrically therethrough with one end of bore 45 communicating, through a hole 46 in the valve guide 40, with the space 19a between the tubes 19 and 20, while its other end is adapted to communicate with a groove 47 in the valve Vguide 40 when the valve body 41 is forced far to the rear in the guide 40 by the oil pressure, as in Fig. 6, so that a part of the oil is restored to the oil pump `through the return tube 20. In other words, the valvearrangement `serves as a reducing valve ensuring that the pressure ofthe oil fed to the nozzle 6 is kept within certain predetermined limits, and this is of considerable importance for the good functioning of the burner as well as for good fuel economy.

The bore 45 in the valve body 41 also communicates with the rear side of the valve body 41 through an axial 'hole 48, about the mouth of which is provided a seat for the valve needle 22. The hole 48 serves as a direct connection betweenV the oil feed conduit to the nozzle,

' if. e. the space 19aV between the tubes 19 and 20, and the 'interior of the return tube 20, in order to permit a circulation through the oil preheater 7 before the llame of the A'burner is lighted' and also to provide an instantaneous pressure drop in the `oil feed conduit when the burner operation is discontinued.

In the illustrated embodiment, the valve arrangement is utilized as follows: the heating element 12 in the oil preheater 7'is adapted to work intermittently, asis the whole burner. The current circuit through the heating element 12' is closed only when the fan and pump motor ofthe burner 'is started, so` that the oil in the preheater 7 is heated. Until the oilV has` attained the necessary working temperature, which is controlled by the thermostat 13, the valve needle 22 is retained in its rearward unseated condition by thespring 34, and the oil will thus and, thus,'the oil pressure will be built up in the system until, as already described, the Avalve body 41 is forced back to layopen the discharge port 44 and so that a reduction will be eiected in case of too high oil pressure. In connection with the breaking of the current to fan and pump motor when interrupting the burner operation, the current to the solenoid 37 is also interrupted so that the valve needle 22 is pulled back by spring 34, and thereby an instantaneous pressure drop is obtained in the oil feed line to the nozzle so that the valverbody will quickly close the discharge port 44 to the nozzle.

The described embodiment of a heavy-oil burner equipped in accordance with the invention works very satisfactorily and gives complete combustion of all oil fed to it, even during intermittent operation. As the jacket 9 protects the nozzle 6 against being swept by large quantities of primary air and the free portion of the nozzle tube 19 is very short, the heavy oil is effectively prevented from being detrimentally cooled during its passage from the oil preheater to the nozzle. The electrical heating element 12 enclosed in the coiled pipe 12 need not be switched on when the burner is inoperative, and due to the permanent oil circulation taking place when the heating element is connected, whether oil is fed through the nozzle or not, the heating element can very easily be dimensioned to suit the actual heat requirements. Excess heat radiated from the preheater 7 is utilized by the primary air flowing through the surrounding air pipe 4.

Although an illustrative embodiment of the invention has been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to that particular embodiment, and that various changes and modifications may be effected therein Without departing from the scope and spirit of the invention, except asgdelined in the appended claims.

I claim:

l. In a heavy-oil consuming pressure oil burner; the combination of an air fan operative to produce a stream of primary air, an air pipe connected to said fan for conducting said air stream into a furnace, a burner head centrally located in said air pipe near the outlet end thereof, an oil pump, an oil spraying nozzle disposed in said burner head for distributing fuel oil in said air stream, means for conducting oil from said pump to said nozzle including an oil preheater supported within said air pipe for heating the fuel oil on its passage from said pump to said spraying nozzle, said oil preheater comprising a spacious, elongated oil chamber of annular cross section located centrally within said air pipe and having heat emitting means therein, said burner head being supported at the forward end of said oil chamber means defining an oil outlet in the rear end of said oil chamber, Vsaid annular oil chamber defining a central opening extending therethrough and an oil feed pipe passing through the central opening of said annular oil chamber and having said spraying nozzle attached to its forward end and its rear end detachably connected to said oil chamber outlet so as to permit withdrawal of said oil feed pipe and nozzle without dismantling of the burner.

2. In a heavy-oil consuming pressure oil burner; the combination as in claim l, wherein said heat emitting means in said oil chamber comprises a coiled pipe extending through said oil chamber and an electric heating element in said coiled pipe, and said oil chamber has means therein to cause the fuel .oil to pass through said oil chamber in the longitudinal direction thereof in heat transfer relationship with said coiled pipe.

3. In a heavy-oil consuming pressure oil burner; the combination as in claim l, wherein said means defining an oil outlet in the rear end of said `oil chamber includes a pressure responsive valve device preventing fuel oil oil feed pipe has ahead formed thereon,` and wherein the external -face of said rear end of said oil chamber of the oil preheater forms a seat for said head, said seat surrounding said oil outlet of the chamber and said head having passages therein connecting said feed pipe to said outlet, means being provided to detachably clamp said head to said seat. Y

5. In a heavy-oil consuming pressure oil burner, the combination of an air fan operative to produce a stream of primary air, an air pipe connected to said fan for con-V ducting the stream of primary air into a furnace, a burner head centrally located in said air pipe near the outlet end of the latter, an oil pump, a spraying nozzle disposed in said burner head, means for conducting oil from said pump to said nozzle for distribution by the latter into the stream of primary air including an oil preheater supported within said air pipe :and operative to heat the fuel oil during its passage from said pump to said nozzle, said oil preheater having means defining a spacious, elongated oil chamber of annular cross-section located centrally within said air pipel and heat emitting means in said oil chamber, said burner head being supported at the forward end of said oil chamber, means defining an oil outlet in the rear end of said annular oil chamber, said annular oil chamber dening :a central opening extending therethrough, an oil feed pipe passing through said central opening of the annular oil `chamber and having said nozzle attached'to its forward end, means detachably connecting the rear end of said oil feed pipe to said oil outlet, means forming a valve chamber located close behind said nozzle in the forward end portion of said oil feed pipe, a fuel discharge port located ibetween said valve chamber and said nozzle and opening from the latter into said oil feed pipe, a rearwardly facing seat around said discharge port, a valve member slidable in said valve chamber and projecting forwardly from the latter toward said seat so that the pressure of the oil in said oil feed pipe acts rearwardly on said valve member to urge the latter Vrearwardly away from said seat, spring means urging said valve member forwardly against said seat to close said fuel discharge port until the pressure of the oil in said oil feed pipe reaches a predetermined minimum value, a return conduit for fuel oil opening into said valve charnber in :back of said valve member and connected to the suction side of said oil pump, said means defining the valve chamber having passage defining means for communicating said oil feed pipe with said valve chamber in back of said valve member and being normally closed by the latter, said valve member having passages extending therethrough which communicate with said passage delining means when the valve member is displaced rearwardly by a pressure in said oil feed pipe exceeding a predetermined maximum pressure, thereby to permit return of oil from said oil feed pipe to said pump through said return conduit, said valve member further having an opening from said passages at the side of the valve member facing rearwardly toward said return conduit and forming a needle valve seat, land an electromagneti# cally actuated needle valve operatively associated with said needle valve seat to permit, when in open position, direct communication between said oil feed pipe and return conduit by way of said passages and `opening of the valve member so that the oil can be freely circulated from said pump through said oil preheater and back to said pump without therdischarge of oil from said nozzle.

6. In a heavy-oil consuming pressure oil burner, the combination as in claim 5; wherein said return 'conduit is located concentrically` within said oil feed pipe; and wherein said electromagnetically actuated needle valve includes a needle element extending axially through said return conduit into said valve chamber, the end of said needle element remote from said valve chamber projecting out of said concentric return conduit and oil feed pipe and carrying a magnetic armature, and a solenoid receiving said armature #and operative, when energized, to displace said needle element forwardly against said needle valve-seat.` A

7. In `a heavy-oil consuming pressure oil burner, the combination as-inclaim `yfurthercomprising a stationary casing, said solenoid being axially movable within said stationarycasing, and`spring `means yieldably resisting rearward axial movement of said solenoid relative to said casingso that; when said solenoid is energized,vsaidneedle element and solenoid can be displaced rearwardly to- References Cited `in `the file of this patent gether by rearward movement of said valve member sub- 10 2,577,238

jected ;to the pressure of oil in said oil feed pipe.

UNITED STATES PATENTS Voorheis .Apr. 14, Lanser June'24, Andler May 7, Williams Dec. 3, Senninger Apr. 9, Lum Mar. 2, Edvinson Dec. 4,

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