US3152634A - Liquid fuel combustion apparatus with previous vaporization - Google Patents

Description

Oct. 13, 1964 J. SCHOTSMAN LIQUID FUEL COMBUSTION APPARATUS WITH PREVIOUS VAPORIZATION 2 Sheets$heet 1 Filed July 5. 1961 FIG.2

INVENTOR. J n fc/wfxman Oct. 13, 1964 J. SCHOTSMAN LIQUID FUEL COMBUSTION APPARATUS WITH PREVIOUS VAPORIZATION Filed July 5, 1961 2 Sheets-Sheet 2 United States Patent 3,152,634 LIQUID FUEL COMBUSTIQN APPARATUS WITH PREVIOUS VAPORIZATION Jan Schotsman, Dieren, Netherlands, assignor to N.V.

Emailleerfabriek De Ijsel, Dieren, Netherlands, a corporation of the Netherlands Filed July 5, 1961, Ser. No. 121,901 Claims priority, application Netherlands, July 12, 1960, 253,701 5 Claims. (Cl. 158-71) The invention relates to a liquid fuel combustion apparatus, in which fuel is first guided through a vapor chamber which is disposed near the heater but out of direct contact with flames whereby fuel is preheated. The device may be provided with a safety overflow.

Heating devices of this type are generally known, in these known apparatus the vapor chamber is kept away from direct contact with the flames to try to prevent the temperatures of the fuelfrom running up so high that it reaches the cracking point, or, when admixing air, to prevent a spontaneous ignition of the vaporized fuel.

In most constructions the vapor chamber is situated beside or under the burner and forms a unitary construction with it. Conduction heat, or a combination of radiation heat and conduction heat, is utilized.

A drawback of this construction is that the temperature can run up too high, so that additional measures are necessary. For instance, the vapor chamber may be partially filled or provided with a number of partitions, screen plates or cooling ribs.

However, various safety measures are necessary which render the apparatus not only much too expensive but also extremely vulnerable.

Further, it is known to provide a tube-shaped vapor chamber out of direct contact with the flames, by placing a ring or spiral winding placed beside the burner, but above it creating a danger of overheating.

From British Patent 133,688, a vapor chamber is known which is placed beside the flame base and comprises a plurality of spiral windings, so that while it is true that the lowermost winding lies within the range of the least intense radiation, there is a chance of overheating at the higher points which will cause an increase in the temperature of evaporation.

For starting a heating apparatus various devices for preheating the vapor chamber are used, for instance a spirit tablet, a fuse, an auxiliary burner, an electric element and the like. Starting with the aid of an electric element is very attractive, because of simplicity and ease of regulation. However, preheating should also be effected very gradually, because otherwise there would arise a risk of cracking out or of spontaneous ignition when air is admixed. In the generally known apparatus, in which, then, an electric heating element is applied, this latter extends over the entire length of the vapour chamber, so that the relatively cold inflowing fuel suddenly enters the heated zone.

For Swiss Patent No. 275,954, there is described a vapor chamber which is situated within direct range of the flames, and in this chamber an electric heating element is utilized, which does not extend over the entire length of the vapor chamber; however, the part which is not heated by this element is situated near the vapor- 3,152,634 Patented Oct. 13, 1964 "ice (gas-) outflow opening, so that at the other end the relatively cold fuel still suddenly enters the heated zone, and afterwards may condense before the exhaust the exhaust.

Finally, all heating devices with pre-vaporization (-gasification) have the additional drawback that, quite irrespective of the preheating method which is applied, the fuel supply must always be reduced until the burner is able to keep the evaporation going and it is only then that the fuel supply can be fully opened.

It is an object of the invention to eliminate the above described drawbacks and by applying a number of meas ures to obtain a reliable and safe heating apparatus.

It is another object to make use only of the laterally directed radiation of the flame while completely avoiding flame convection.

It is a further object to start the vaporization of the fuel with the aid of an electric heating element situated inside the vaporization chamber whereby the fuel supply can be completely opened immediately the heating element is switched on.

The means by which the objects of the invention are obtained are fully described with reference to the accompanying drawings which illustrate a preferred em- .bodiment of the invention.

FIG. 1 shows a front view of the combustion apparatus the front plate being removed.

FIG. 2 shows a transversal cross-section along the line IIII in FIG. 1.

FIG. 3 is an elevation, enlarged and in detail, of the right side of the apparatus, of FIG. 1.

FIG. 4 is an enlarged sectional view, showing the relationship of a burner, vaporization chamber and reflector in detail.

The combustion apparatus 1 is provided in a known way with a liquid level regulator 2, which is fed by conduit 3 coming from a liquid tank.

The liquid level regulator 2 is connected by the conduit 4 to the pro-vaporization chamber 5, which is provided with an overflow safety 6, the highest point of which just projects a little above the liquid level in the regulator 2, so that it is impossible for fuel to flow into the burner when the flame is extinguished. With reference to FIG. 3, it can be seen that if the burner were extinguished, liquid fuel will flow into the chamber and up into the overflow device but will not flow down conduit 8 which is disposed at the top of the safety and which in turn is located higher than regulator 2. Vaporization chamber 5 has a fuel entrance end 5a and a fuel exit end 5b and is positioned at a slight incline rising with the fuel flow so that the vaporized fuel may be allowed to flow freely away beyond the liquid section. A light metal gauze filling (not shown) can be provided in the vaporization chamber in a known way as an extension of the vaporization surface for the promotion of the successive evaporation and for neutralization of the occasional fluctuations in the velocity of the inflowing fuel. In the vaporization chamber 5 is provided an electrical heating element 7 over maximally three quarters of the length of the prevaporization chamber calculated from the vapor (gas) outflow opening. This makes a very gradual heating of the liquid fuel possible, whereby, moreover the fuel supply can be completely openedimmediately after the heating element is switched on. By the conduit 8 the vapor is guided to the injector 9, which is mounted in the air suction mouth-piece 10, which possesses a generatrix 11, slightly declining towards the mixing chamber 12 under the burner 13, which can be built up from porous incandescent bodies. The air suction mouth-piece 10 is connected to the double bottom 22 for the primary supply of air. Opposite the vaporization chamber 5 is provided a reflector 14. The overflow safety 6 is provided at the outside with a fireproof and heat insulating wall 15. The bottom of the pre-vaporization chamber is also provided with a local heat insulation 15, in order to prevent occasional cooling by the secondary air fanning past it. The combustion chamber is limited at the rear.

side in aknownway by a draught funnel 1;7-which serves to lead air of as low as possible a temperature to the cooling system 18.- Finally, the apparatus is providing in a known way with a chimney connection 19, containing amongother things an automatic draught regulator 20. and a draught cut-ofl 23. 21 is a double-walled screenagainst radiation on the liquid level regulator 2.

The burner Isis, placed in an oblique position in such a way that thewhole of the incandescent surface is visible through a window in the front wall not rendered in the drawing.

In the liquidfuel heating apparatus withgpre-vaporization (gasification), according to the invention not only are the aforedescribed drawbacks eliminated, but by applying a number of measures a reliable and safe heating apparatus is obtained, which in addition to this is of simple. construction.

In the disclosed construction use is made only of the laterally directed radiation of the flame, while completely avoiding flame convection. In addition to the ideal vaporization temperature being well maintainable at this position. of-the vapor chamber is relation to the burner plane, the said working temperature is only slightly reduced even at low positions of burner capacity because the radiation near the lower rim remains relatively high. Besides, the special manner in which the electric heating element is provided makes very gradual heating of the liquid. fuel. possible, whereby the fuel supply can be completely opened as soon as the heating element is switched on.

By positioning a thermostat in the combustion apparatus in a known way, which thermostat causes the, elecric preheating to be switched of when the working temperature is reached, it is possible to save current and the whole of the operation is restricted to the mere opening of fuel supply. and the switching on of the electric current, which is very important for a device intended for domestic use.

The vapor chamber is, positioned at a slight incline rising with the fuel flow so that the vapor (gas) of the most volatile components may be allowed to flow freely away beyond the liquid section ending before the middle of the length.

' With the combustion apparatus, according to the invention. vaporization is effected at the lowest possible temperature, that is to say near, but well below, the final boiling point of the fuel fractions burned, so that premixing with air is possible, without the risk of spontaneous ignition of the mists caused when mixing.

In addition to this, it is possible to provide the apparatus with a reflector which is mounted opposite the part of the vapor chamber which is not directly exposed to radiation, so that this part of the vaporizer does indeed receive radiation from the lower regions, but not from the higher regions of the burner flame. In this case a low flame effectively emits relatively more radiation, to the benefit of the. maintenance of the right temperature equilibrium. A slight readjustment of this reflector also offers the possibility of readjusting the working temperature if a somewhat heavier fuel should render this necessary. This measure is characterized in that a hollow cylindrical reflector is adjustably provided parallel to and opposite the part of the vapor chamber which is turned away from the flame base.

Although the vapor chamber is heated at the front side directly by the flame radiation and at the back side via a reflector, there still is a chance of the vapor chamber being locally cooled by secondary combustion air fanning past its bottom side, so that the temperature equilibrium can be disturbed. In order to prevent this inadvertent cooling, the bottom of the vapor chamber is provided with a heat insulating material.

Furthermore, a generally known overflow safety can advantageously be applied, so that it is impossible for fuel to flow into the burner when the flame is extinguished.

However, a special measure should be taken to take care that, on the one hand the temperature in this safety is maintained, but on the other hand cannot be influenced from the outside, because, naturally, the highest point of this safety should be at a level with or a little above the liquid level in the float chamber of the regulator and consequently can come with the flame range. For this purpose, this safety overflow is according to the invention characterized in that it is provided with a wall which is fireproof and insulates against heat.

Although by the application of the above-described measures it is effected that atv the start the heating is as gradual as. possible and the evaporation temperature is as low as possible, yet it is unavoidable, when starting, for a few drops of liquid fuel tocondense out and be carried away with the vapor (gas) flow and drip down when issuing from the injector. In order to prevent the possibility of these drops flowing away outside, the heating apparatus according to the present invention has provisions for guiding said drops to the bottom of the mixing chamber, where they evaporate later, on under the influence of the heat of the burner. I-his measure is characterized in that the air suction pipe which is connected to the, mixing chamber and in which the injection is mounted, has a generatrix which slightly declines towards the bottom, of the mixing chamber.

In the combustion apparatus according tothe invention a minimum amount of mixing air is guaranteed by the impulse from the vapor jet, which is amplified by the natural draught created in the heated body of the stove itself. Both are substantially identical to the fuel demand, so that over a fairly large regulation range there is little change in the composition of the mist.

Thev close connection to a draught-supplying chimney, so necessary in other combustion apparatus, in this construction is superfluous and'even undesirable. The rigid draught interrupter required in gas stoves will frequently suflice.

A second argument against draught aid'is based on the consideration, that no depression with respect to the immediate air-containing surroundings may be caused in the mixing chamber at any price.

This vagrant air immediately causes flareback combined with the forming of soot in the mixing chamber.

The combustion apparatus according to the invention is extremely simple to operate, is completely safe and practically makes no noise.

I claim:

1. Liquid fuel combustion apparatus comprising a burnerhaving a planar burner element, said planar element being inclined such that the, plane thereof is disposed at an angle relative to. a horizontal plane of the combustion apparatus, a tubular vaporization chamber having fuel exit and entrance ends and disposed adjacent the lowermost portion of said planar burner element and out of direct contact with a burner element flame, said tubular vaporization chamber being inclined at a slight angle with respect to a horizontal plane of the apparatus such that said fuel exit end is higher than said fuel entrance end, an electrical heating element disposed longitudinally of the tubular vaporization chamber and extending no more than three-fourths of the length of said tubular vaporization chamber calculated from the fuel exit end thereof, fuel injection means including an inlet for directing air and vaporized fuel to said burner element, and conduit means for conducting fuel from said vaporization chamber to said fuel injection means.

2. Liquid fuel combustion apparatus as claimed in claim 1 including liquid level regulating means to regulate the supply of fluid to said vaporization chamber.

3. Liquid fuel combustion apparatus as claimed in claim 2 including a safety overflow means provided at the fuel exit end of said tubular vaporization chamber.

4. Liquid fuel combustion apparatus as claimed in claim 3 including a reflector adjustably mounted parallel to the vaporization chamber on the side thereof opposite said 15 burner element.

References Cited in the file of this patent UNITED STATES PATENTS 238,634 Billings Mar. 8, 1881 1,175,493 Williams Mar. 14, 1916 1,238,003 Crook Aug. 21, 1917 1,741,725 McKeown Dec. 31, 1929 2,507,464 De Andrade So May 9, 1950

Claims (1)

1. LIQUID FUEL COMBUSTION APPARATUS COMPRISING A BURNER HAVING A PLANAR BURNER ELEMENT, SAID PLANAR ELEMENT BEING INCLINED SUCH THAT THE PLANE THEREOF IS DISPOSED AT AN ANGLE RELATIVE TO A HORIZONTAL PLANE OF THE COMBUSTION APPARATUS, A TUBULAR VAPORIZATION CHAMBER HAVING FUEL EXIT AND ENTRANCE ENDS AND DISPOSED ADJACENT THE LOWERMOST PORTION OF SAID PLANAR BURNER ELEMENT AND OUT OF DIRECT CONTACT WITH A BURNER ELEMENT FLAME, SAID TUBULAR VAPORIZATION CHAMBER BEING INCLINED AT A SLIGHT ANGLE WITH RESPECT TO A HORIZONTAL PLANE OF THE APPARATUS SUCH THAT SAID FUEL EXIT END IS HIGHER THAN SAID FUEL ENTRANCE END, AN ELECTRICAL HEATING ELEMENT DISPOSED LONGITUDINALLY OF THE TUBULAR VAPORIZATION CHAMBER AND EXTENDING NO MORE THAN THREE-FOURTHS OF THE LENGTH OF SAID TUBULAR VAPORIZATION CHAMBER CALCULATED FROM THE FUEL EXIT END THEREOF, FUEL INJECTION MEANS INCLUDING AN INLET FOR DIRECTING AIR AND VAPORIZED FUEL TO SAID BURNER ELEMENT, AND CONDUIT MEANS FOR CONDUCTING FUEL FROM SAID VAPORIZATION CHAMBER TO SAID FUEL INJECTION MEANS.

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