US2373759A - Heater for liquids - Google Patents

Description

April 17,. 1945.v A. HoURvl'rz 2,373,759*

r HEM/ER FOR LIQUIDSV Filed March l5, 1941 3 'Sheets-Sheet 1 n 5b L 12a 1f l 14a 16;5/ IY. '15a im a 4 Y O /|I'T 4 la Y L7 #El l l 40 1 f" :i 59 i f?" F1 2 1 H 5a 12 2..'/2` 59a.' B 41y '5a A 5a, 20 f 2z 4 Ic l fc 15 f, /22 ak, l; A 5&5 I

' INVENTOR.. 46 BY f ma April 17, 1945. 1 A. HoUm/n'z HEATER, FOR LIQUIDS Filed March 15, 1941 3 Sheets-Sheet2 NVENToR.

BY 77500K/ ATTORNEYS.

April 17, 1945.

` i A. HoURvlrz HEATER FOR LIQUIDS `Filed March l5, 1941 3 Sheets-Sheet 3 IN1/gro. BY* Ix/0M Y ATTORNEYS.

Patented Apr. 17, 1945 HEATER FOR LIQUIDS Avlnoam Hourvltz, Alexandria, Egypt Application March 15, 1941, Serial No. 383,520 In Palestine April 4, 1.940

6 Claims.

This invention relates to automatic heaters for water or other liquids, operated by means of a burner Whose fuel may be either liquid or gaseous.

It is an object of this invention to provide an improved construction of such water heaters in the form of a self-contained, fully automatic unit, adapted to instantaneously supply hot water for domestic use, hot water or steamfor central heating plants as well as for certain industrial applications, and is adapted more particularly for heating liquids of any kind in smaller workshops, but it is to be understood that the possibilities of application are not limited by the foregOing.

The known heaters used for the various purposes in view can be classified in two dis-- tinct categories:

l. Domestic apparatus of the circul'ating'type, the constructionrof which is especially adapted for the quick heating of water for domestic purposes. 'I'he function of this apparatus is never fully automatic for reasons hereinafter stated, and therefore is limited to such installations as are under the direct supervision of the operator.

2. Apparatus devised for heating plants of buildings and for smaller workshops. These apparatus have generally all the full automatic outfit and security appliances required but these involve bulky devices of industrial scale,l arranged one beside the other, which do not permit the obtaining of a really self-contained unit with desirable configuration such as is necessary for certain applications.A Moreover, their cost is high.

A common feature of all these apparatus is that the burner is maintained at a pressure substantially equal to the surrounding atmospheric pressure, the burner communicating with the surrounding atmosphere either directly by apertures provided in the combustion chamber in order to decrease the danger of possible explosion, or indirectly through the air inlet ports or through a hood arranged between the apparatus and the chimney for the purpose of avoiding the return of smoke or fire.

Whil 'the known apparatus can-be built in a light manner from thin metal sheets in the case of domestic' apparatus of the circulating type or from fragile materials such as cast metal or rebacks. These'drawbacks result from the relatively large volumeof the combustion chamber and of the circuit of burnt gases and from the apparatus itself that is from the return-of the (Cl. 15S- 28) flame at the moment of igniting before the natural draught has come into existence, this drawback making itself especially felt with appaL ratus undergoing frequent igniting as in the case 5 with automatic apparatus; and from the return of burnt gases under the action of wind which causes a flickering of the flame or even its complete extinction. Anyone of these drawbacks leads in practice to a decrease of the efficiency of the apparatus and to an increase of the dangers of fire and suffocating due to the return of the flame or of burnt gases as well as of fresh gases after the extinction of the flame. This results in the condition that the security appliances and automatic devices are frequently rendered inefficient -which makes it necessary to place the apparatus under the direct supervision of the operator as stated above.

By the present invention all these drawbacks ratus are provided which include the various security appliances and automatic devices so as to form self-contained, fully automatic units of a simple and pleasant construction and low cost and being suitable for all the applications mentioned above from domestic hot water supply to the most varied needs of small industry.

According to this invention, the com-bustion chamber is maintained at a pressure substantially higher than thel surrounding atmospheric pressure. 'I'he flow of fresh air land gas are completely and hermetically separated from the room where the apparatus is located so that the combustion takes place within a. chamber which is completely sealed from said room.

The heat exchange may be performed by means of a mono-tubular heating body which is either prismatic or, preferably, cylindrical and in accordance with the invention described in co-pending application No. 383,521.

The admission of 'fresh air into, and the maintenance of the requiredv pressure in the combustion chamber are secured by a ventilator, the start of which coincides with the opening of the 45 fuel supply and/or with the beginning of circulation of the liquid to be heated. Advantageously a shutter is provided which falls back by its own weight as soon as the ventilator ceases aspirating, in order to shut off the admission of fresh air and 60 to prevent any air circulation in the apparatus with a view to avoiding the cooling of the air Y during the period of the apparatus idling.-

A special control device for starting the ventilator and/or the burner will be described here- Il inafter.

are overcome and eliminated, and heating appal For interrupting the current of the electric priming resistance of the liquid fuel burner after igniting the latter, a device is provided which comprises a switch :fcntrolled by an elastic membrane influenced :by the pressure prevailing in the combustion chamber. The function of this device is based upon the diierence of the pressures existing in the combustion chamber before and after igniting; before igniting, this pressure corresponds to the drop of pressure caused by the flow through the apparatus of fresh air aspirated by the ventilator. After lgniting, this drop of pressure -increases substantially owing to the increase of volume of the hot gases. The resulting increased pressure acts on themelastic membrane and brings about the interruption of the` current of the priming resistance.

other features of the invention will Aappear from the following detailed description in which a preferred embodiment of an automatic domestic circulating water heater with liquid fuel burner is set out by way of example with reference to the accompanying drawings.

Fig, 1 is a right side elevational view in section of an embodiment of the heater,

Fig. 2 is a front elevation in section of the lower portion of the heater,

Fig. 3 is a sectional view along line III-III of Fig. l,

Fig. 4 is a detail sectional view of the automatic burner ignition switch.

Fig. 4a is a diagrammatic view showing the wiring diagram used in connection with this invention.

Figs. 5 and 6 are fragmental detail views of the lower part of the heater.

With reference to the drawings, the heating body I has ribs Ia formed on its inner face, said ribs having the grooves Ib formed therebetween. These ribs which are of trapezoidal cross section extend only substantially along the upper half of the heating body I.

The space 2 of the heating body where no ribs are to be found forms the combustion chamber, the volume of which is calculated to correspond to the size of the flame, the latter depending in turn on the fuel and air supply as well as on the pressure existing in the chamber.

A core 3, made of steel or a refractory material, is inserted in the empty space of the heating body extending between the ribs Ia. This core is seated on the upper edges of the said ribs by means of a shoulder 3a. The diameter of the core is slightly smaller than between the inner edges of diametrically opposite ribs, thus forming an annular space l between the ribs and the core. The core directs the gases into the grooves Ib in order to make contact with the surface of the ribs. The annular space 4 secures a good distribution of the gases in the area of the ribs in the event that there is a poor initial distribution of the gases due to bad centralization of the flame or to any other reason.

The heating body I has at both its ends buiges Ic and Id each having an annular groove in which rings 5a and 5b consisting of a compressible material (rubber or the like) and being of a diameter slightly larger than the outer'diameter of the buiges are inserted. These rings are devised to tighten the heating body I against an outer casing member 8 in which it is accommodated.

The outer diameter of the lower bulge Ic is substantially larger than that of the upper bulge iso Id which permits the easy insertion of the heating body I in the casing member i.

A clamping ring l is screwed on the top of heating body and secures the casing member O to the former, the lower edge of the said casing member resting in a groove provided in bulge Ic.

An elbow 8 and pipe 9 drain ofi the waste gases to outside the room where the apparatus is located.

Fresh air is introduced through tube I0. This tube has at its inner end a shutter II capable of falling back on Vits seat by gravity and of being opened by the draught of the ventilator (with which the burner is provided as described hereinafter) in order to admit the air.

The casing 6 has two tubular sockets 8a and 6b for the inlet and outlet of the water.

The entire unit is mounted on the wall A of the room by fixing means which comprise two wall brackets I2 and I2a, the correct distance between which, corresponding to the distances between the two tubular sockets 8a and Bb, is maintained by a tube Il. Through these sockets pass the water inlet and outlet conduits I4 and Ha, and these in turn communicate with the main pipesy by means of screwed recording pieces Il and lia.

These arrangements facilitate the assemblage of the apparatus since the masonry work required for fixing the wall brackets on the wall A can be carried out without difficulty from the side of the apparatus itself which will be mounted on the brackets when the masonry work is finished.

Where the apparatus serves as a circulating water heater for instantaneous heating, it can be iltted with a device reducing the loss of heat by radiation and decreasing the time required for bringing the water up to the desired temperature.4

This device comprises a deflectorformed by concentric cylinders guiding the water and compelling it to ow in annular concentric layers, succeeding one another from the periphery towards the'centre. As an example, the drawings show a device of this kind which has two cylinders I6 and Ita whereby three concentric water layers are formed. Cold water enters from below, rises upwards and circulates at first between the wall of casing 8 and cylinder I8 and is thereafter conducted downwards between the two cylinders I8 and I6a in order to pass finally upwards between the heating body I and the cylinder Ita.

The heat which ig radiated from the center of the apparatus outwardly is thus collected by the successive concentric water layers which grow colder from inside the apparatus outwardly. In this way,the losses due to radiation are reduced. Moreover, the quantity of water which is to be heated at the moment'of opening the apparatus is only a fraction of that contained between the heating body and the casing, and thus this fraction is brought more rapidly up to the desired temperature.

In order to avoid the formation of air pockets in the space Ib above cylinder I6, some small outlet ports (not shown) are provided there.

The burner B, here shown by way of example, is a self-contained unit assembled in a casing Il which forms a downwardly continuation of casing 6. It has a raising fuel duct I9 rotated by an electromotor I8 of which duct I9 forms the shaft. Duct I9 dips intoa fuel container 23 and is provided at its upper end with a. funnelshaped cup 20 by which the fuel, raised in duct I9 by the rotation thereof, is centrifugally pro- :,svavso The air` is suckedv through the air inlet l0 by a Y' fan 22 keyed on duct I9, and guided into cup 2i through appropriate channels and apertures,

f thereby maintaining the required pressure in the combustion. chamber 2. An electric priming. de-

vice is provided in the burner beneath cup 20.

This is an incandescent resistance wire 42.

The fuel container 23 which is mounted within casing I1, is air-tight and is of the barometric feed-type. It has an axial sleeve 24 perforated by-a hole 24a located at the level which it is desired to maintain within the said sleeve into which the hollow shaft il dips.

A gauge tube 2l permits the following of the variations of level of the fuel within sleeve 24 with which it is in communication by means of a conduit 2l and a socket 21 which has a stumng box 2l. The upper end of the gauge tube opens freely'in the lower part of asocket 29 and communicates with the surrounding atmosphere by apertures which are not shown in the drawings.

Fig. 5 is an' axial section corresponding to Fig. l, with the' difference, however, that two devices are shown which have been omitted in Fig. l. fox-,the sake of greater simplicity of the latter. 'I'he two devices in question are first, a means for simplifying the refilling of the container thereby that no tight filling stopper need be provided which otherwise would be indispensable, since the container is of the barometric feed-type in which the air contained in the fuel container must 'not communicate with' the outer air during the operation of the burner.

The desired result is obtained by means of two. concentric tubes of which the innermost one 2l is 'soldered and welded into the bottom of a cup I4 and passes through this bottom so as to communicate with the air contained in the fuel container. The outer tube 3B is sealed at its top and rests on the bottom of cup 34 on several points of its base.

Filling is done through the neck 30 of socket 29 into which the fuel is poured after removing the cup 3| slid over this socket. The fuel flows through a conduit yl2 onto the inclined cover of the container and through the'sleeve 24 into the interior of the container. On its way it tllls the cup 34, the contents of which forms a liquid seal between the outer air andthe air contained in the fuel container. During the filling action the fuel arriving in the container compresses the air contained therein, drives it out through tubes 3l and l! and causes it to bubble through the liquid joint formed by the fuel in cup 34.

After starting the burner, the level in sleeve 24 adjusts itself atthe heightof hole 24a`while the level in the container drops as the fuel is consumed. A drop in pressure4 corresponding to maximum height. Fig. 5 snows the admissible level of .fuel in the fuel container and the level (correspondingto the drop in pressure mentioned abovellfwhich the liquid column assumes' in the annular space between tubes I3 and 35 at the moment whenthe consumption of fuel by the burner begins to drop the level in the container vwhich was supposed to have been filled upto its highlevel.

'Ihe other device shown inFig. 5 relates to the return of unburnt fuel which-may leave the burner and would collect in a groove 36. The

`return pipe l1 which, with the type .of burner selected, leads the fuel towards the fuel container, yis shown to be surrounded by another tube 38 sealed at its base and having an aperture at 24a.' 4Under 'these conditions, the returned fuel must, prior to being poured onto the inclined cover of the fuel container, pass through tube Il which had been nlled previously up to the level -of aperture 26a. ,In this way a liquid seal is formed, which-while admitting the return of the unburnt fuel to the container, prevents the out- If it is desired to have a store of fuel larger I than that contained in thecontainer, a supplementary tank could be arranged in parallel with container 23, provided that this supplementary tank be closed all round and be connected to the container 22 in an appropriate manner so as to allow the flow of fuel towards container 23 and the free ilow of air between the air space of the fuel container 22 and that of the supplementary tank.

In order to start the burner without disturbing the hermetic seal of the apparatus, a special device has been provided which is shown in v greater detail in Fig. 4. This device principally This liquid column prevents communication be,-

tween the outer air and the air enclosed in they container.

The length of tubes I2 and 35 is such as to exceed the maximum height of said liquid column. The volume of cup 24 is made substantially larger than that of the liquid column at its comprises a cylindrical metal tube 39 whose thickness, diameter and length are so chosen as to impart to it a suitable transverse flexibility. This tube is inserted with its end 39a in the bracket I2. In its ropposite end, vthere is inserted the end of a rigid conical rod 40 projecting outside tube 39 by a knob 40a. At its lower end this rod bears a ball 4I, forming a valve which in its normal position of rest is applied on its seat at the mouth of the water inlet conduit I4.

When, upon opening a cock in the water main, water begins to circulate in the apparatus, the ball is lifted from its seat in the flowing direc- -tion of the water. Owing to the exibllity of tube 38. the knob 40a of rigid-rod 4l is displaced accordingly, but in the opposite direction. Such displacement is Vutilized for closing the electric circuitof the-electric motor i8 and of the priming resistance 42 o f the burner. For this purpose.

-a switch 43 of suitable construction is arranged in this circuit the latter being shown byFig. 4a. in the drawings. The wiring diagram disclosed in Fig. 4a`reilects the relative positions of the various switches etc. appearing in Fig. 1. The letter A denotes the master switch, B, B' denote two fuses, C the leadsto the electric main. The system .can be grounded at E by connecting it to the metal body of the apparatus. This switch has a leaf spring 43a bearing one of the contact pieces of the switch, the free end of said leaf spring being in contact withknob 40a. In the position of rest shown in Fig. 4, the knob 40a holds the switch open, but during the displacemovement of the knob until contact is established between the contact points of the switch. The electric motor thus begins running at the moment of opening the water cock and is stopped only when the said cock is closed, whereby the ball valve, and thereby the rod 40, are allowed to return into their position of rest.

The burner ceases operating when the water pressure in tube I4 is not great enough to sumciently deflect the tube 38. the rod 40 and projecting knob 40a to permit the closing of the switch 43. Another function of ball 4I is to prevent a return flow of the water within the apparatus when the said apparatus is not in operation.

In order to automatically interrupt the current of the priming resistance 42 as soon as the fuel is ignited, and for actuating this current again in case of an accidental extinction of the name, a device for controlling the igniting operation has been shown in Figs. 1 and 6. The acf tion of this control device is based, as already mentioned above, on the diierence of pressure in the combustion chamber before and after igniting This control device has an elastic membrane 44 clamped at its circumference between rings 45 and 46 which form the base of the apparatus. This membrane is stressed with its center upwards by means of a leaf spring 41 which tends to lift an adjustable screw 4l. By this stress, a switch 49 inserted in the circult (Fig. 4a) of the priming resistance 42 is held closed. The space beneath the underside of the elastic membrane 44 communicates with the surrounding air through apertures 50a in the bottom 50 closing up the lower end of the casing i1 while the room above its upper side is in communication with the zone within the casing I1 where the same pressure exists as in the combustion chamber with which this zone is connected by conduits 52 and 53 (see Fig. 2).

As soon as the electric motor is started, the membrane is downwardly deflected by the pressure created by the fan in the combustion chamber, but this pressure is not sufficient to overcome the stress of spring 41 which maintains the switch 49 closed. But as soon as the combustion is primed, the pressure which comes into being in the combustion chamber presses the membrane further downwardly whereby the switch 49 is opened and the current of the klndling resistance is interrupted. The said membrane remains in this position during the period of combustion whereas it returns into its position of rest which corresponds to the closed position of the switch 49, when the flame is extinguished accidentally, or when the burner is stopped.

In order to obtain an appreciable displacement of the membrane even if the dierent of pres' The apparatus described hereinbefore need not be heat-insulated. There is no danger of a return of burnt gases nor of a loss of unbumt gas.

Its operation is fully automatic, and its operation is infallible. Additional security results from the fact that if for any reason a dangerous excess pressure arises in the circuit of the liquid within the apparatus, this pressure acts on the ball 4I in a direction opposite to that of the innowing liquid, whereby the burner switch 43 is interrupted. 0n the other hand, an excessive rise of temperature in the combustion chamber increases the gas pressure in this chamber, thereby forcing back the fuel in hollow shaft la which results in a diminution of the thermal output of the heater, thus resulting in anautomatic regulation.

If the apparatus according to this invention is to be used for central heating plants of buildings or for the supply of hot water or steam, it may be advantageous to dispense with the defiector Il, lia and to provide for an external heat insulation in order to comply with the necessity of providing for an accumulation of hot water or steam. The starting device according to Fig. 4 could also be replaced by any known device, or it could act solely as a' safety device.

I claim: y

1. lA heater of the character described, comprising in combination: a heat exchange casing; a combustion chamber within said heat exchange casing and a liquid fuel burner and an electric resistance igniter for same inside said combustion chamber; a second casing co-axial with the firstnamed casing and built together therewith; a blower and a fuel container and an electric motor adapted to feed fuel from said container to said burner and to operate said blower inside said second casing to feed air to said burner, said igniter being connected in a branch of the-circuit of said motor; a switch connected in series with said igniter, and means adapted to open and close said switch in response to the differences of pressure in the combustion chamber after and before ignition respectively and before and after extinction of the name respectively, said switch and pressure responsive means being located inside said second casing; both casings being sealed from the room where the heater is located and communicating with each other and forming between them and with the aforesaid parts enclosed in them a self-contained unit.

2. A heater of the character described, comprising in combination a cylindrical casing; a heat exchanger within said casing; a combustion chamber within said heat exchange casing and a liquid fuel burner and an electric resistance igniter for same inside-said combustion chamber; a second casing coaxial with the first-named casing and builttogether therewith; a blower and a fuel container and an electric motor adapted to feed fuel from said container to said burner and to operate said blower inside said second casing to feed air to said burner, said igniter being connected in a branch of the circuit of said motor; a switch connected in series with said igniter, and means adapted to open and close said switch in response to the differences of pressure in the combustion chamber after and before ignition respectively and before and after extinction of the flame respectively, said switch and pressure responsive means being located inside said second casing; both casings being sealed from the room where the heater is located and communicating with each other and forming between them and with the aforesaid parts enclosed in them a self-contained-unit; and a nowcontrolled switch connected in. the circuit of said motor l'and igniter and adapted to be autoheat exchange casing, and to be automatically opened upon the cessation of such tiow.

3. Afheater as claimed in claim 1, wherein the pressure responsive means comprise an elastic membrane fastened valong its circumference and stretching substantially over the whole cross section ofv said second casing beneath saidfuel container.l I

4. A heater as claimed in claim i, comprising a fresh-air; duct connected to the second casing at a level not above said blower and opening outside the room in .which the heater 'is arranged, and a iue connected tothe top end of the heat exchange casing and opening outside said room.

5. A heater as claimed in claim 1, comprising a fresh-air duct connected to the second casing at a level not above said blower andopening outside the room in which the -heater is arranged', and a ilue connected to the top end ot-,theheat exchange casing and opening4 outside said room; a nap valve being arranged in conjunction with said fresh-*air duct, saidu valve being adapted to automatically shut off said duct while the blower lis not in operation. and to automatically open said duct upon the blower being operated.

. 6. A heater as claimed in claim 1, characterized by a re-tueling system comprising a cup'iormed with the interior of said container through an opening in the bottom 'of `Said cup; a second tube concentricallyA surrounding the 4former, said.

. second 'tube being sealed at its top end at a distance from the top end of the first-named tube andbeing xed within said cup with its lower end being abovethe bottom of the latter but bepipe leading through the wall of lowk the top of. said container; and a iuel supply the secondcasing towards said cup.

i. AVINOAM HOURVITZ.

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