US3869242A - Process for vaporizing fuel oil - Google Patents

Abstract

A process for vaporising fuel oil employs a cylindrical porous heating element through which the oil is passed from the axis, radially outwards. The element is of polycrystalline metal whiskers. The oil feed is in excess of that which the element is capable of vaporising, the excess being returned to the oil source, and the vapour being used for combustion.

Description

United States Patent [191 Schladitz [451 Mar. 4, 1975 PROCESS FOR VAPORIZING lFUEL OIL [76] Inventor: Hermann J. Schladitz, Plantschwez 74, Munich, Germany [22] Filed: Dec. 21, 1973 [21] Appl. No.; 427,319

[30] ForeignApplication Priority Data 3/1966 Bottrill 431/11X 5/1973 Murase et a1. 431/208 X Primary Eraminer-Edward G. Favors Attorney, Agent, or FirmKane, Dalsimer, Kane, Sullivan and Kurucz [57] ABSTRACT A process for vaporising fuel oil employs a cylindrical porous heating element through which the oil is passed from the axis, radially outwards. The element is of polycrystalline metal whiskers. The oil feed is in excess of that which the element is capable of vaporising, the excess being returned to the oil source, and the vapour being used for combustion.

5 Claims, 1 Drawing Figure PROCESS FOR VAPORIZING FUEL OIL The invention relates to a process and a devise for vaporising fuel oil. It employs a porous cylindrical body that is traversed by the fuel oil. The body consists of polycrystalline metal whiskers connected metallically with one another at the points of contact, and heated directly or indirectly, for preference by electric power.

In a known heating element of this type, as described in German Pat. No. 1,288,705, the medium being heated is passed through the porous body in its longitudinal direction. The medium becomes progressively heated as it flows through the porous body until it emerges at one end, heated to the desired temperature or possibly in the form of vapour. Although this known heating element has a very large inner surface and thereby makes possible considerable and instantaneous heating of the medium flowing through, it can give rise to problems with the heating or the vaporisation of hydrocarbons with greatly differing vaporisation temperatures between 60 and 320C. These often have impuritiesor additives with high temperatures of vaporisation or decomposition, and it may happen that outbreaks of vapour will occur in the heating element prematurely and in an uncontrolled manner. Residues will remain and choke the pores. Since the vapour has a very much larger volume than the liquid, the pores of the porous body may become filled with vapour inadmissibly far from the outlet end, and this can lead to overheating, since the vapour in the pores has a lower heat capacity than the liquid. Overheating can lead to the local destruction of the porous body and further the formation of residues.

The object of this invention is to provide a process for vaporising fuel oil by means of a heated porous body of this type, but to reduce as far as possible the risk of the formation of residues from the fuel oil.

According to one aspect of the present invention there is provided a process for vaporising fuel oil by passing liquid oil through a heated, porous, substantially cylindrical body consisting of polycrystalline metal whiskers connected with one another metallically at their points of contact, whereby the improvement comprises passing the oil radially, from inside to outside, through the body and supplying more fuel oil to the porous body than is vaporised.

Assuming that the pore size of the porous body is largely uniform, owing to the radial flow from inside to outside, a pore volume that becomes progressively larger is made available, which is in agreement with the increase in volume of the fuel oil which is being transformed into vapour during its passage. As oil emerges as vapour from the outer peripheral surface of the porous body, it has the maximum number of pores to pass through. If just sufficient fuel oil is supplied to the porous body that can be evaporated by the electric power or other form of heat supplied, in the oils vapour will form only in a relatively thin layer or zone on the outer peripheral surface of the porous body where the maximum pore volume is available, although this is hardly attainable in practice. If, however, less fuel oil is supplied vapour can continue to penetrate into the interior of the porous body where a smaller volume of pores is available. This can lead to local overheating, with formation of residues which may choke the pores. Therefore, in the present process excess fuel oil is supplied than can be vaporised, so that the layer of vapour remains confined to the extreme outer zone of the porous body, i.e. the zone in which the largest volume of pores is available, and any deposits forming there can be tolerated.

According to another aspect of the invention there is provided a device comprising a substantially cylindrical porous body consisting of polycrystalline metal whiskers connected with one another metalically at their points of contact, and formed with a central longitudinal duct, means for heating said body, an oil supply pipe communicating with said duct, a housing surrounding said body with a space therebetween for receiving the oil vapour, means placing said housing in communication with a mixing chamber for mixing the oil vapour with air for combustion, and a discharge pipe from a low point of the housing for discharging fuel oil that has not evaporated.

For a better understanding of the present invention, one constructional form thereof will now be described, by way of example, with reference to the accompanying drawing, in which the single FlGURE is a diagram of a device for vaporising fuel oil.

The main component of this device is a porous,cylindrical body 1, which consists of polycrystalline metal whiskers connected metallically with one another at their points of contact. Polycrystalline metal whiskers (vide for instance Zeitschrift fur Metallkunde Volume 59 (1968) No. 1,pages 18 to 22 can be made with exactly determined diameters from about 0.1 pm in likewise predetermined lengths of up to several centimetres. These whiskers are distinguished by their extremely high strength so that they can stand up to high liquid and vapour pressures. Owing to the metallic connection of these whiskers at their points of contact, for instance by deposition of metal through thermal decomposition ofa metal compound, by currentless metal separation, by electric beam or ultrasonic welding, or similar well known processes, a rigid, highly porous skeleton can be produced, which can have a pore volume of over percent and possesses good heat conductivity.

Theporous body 1 is formed in this example as an electrical resistance heating element, and it is provided at its ends withcontact plates 2 and 3 for connection to a voltage source. It has a centrallongitudinal duct 4 which can be formed for instance by a perforated metal tube. This is sealed at oneend 5 and at its other end 6 is connected with anoil supply pipe 7. Thesupply pipe 7 is connected via anoil pump 8 with anoil supply tank 9.

Theporous body 1 is arranged in ahousing 10 in such a way that anannular space 11 remains for receiving the oil vapour. The inner space of thehousing 10 is connected via atube 12 with amixing chamber 13, which communicates with apipe 14 for the supply of air for combustion. In themixing chamber 13 the oil vapour passes out radially throughopenings 12a in the side of thetube 12 and mixes with the combustion air supplied through holes 13a. Themixing chamber 13 connects with the combustion chamber of the heating boiler.

At the lower end of thehousing 10 is arranged adischarge pipe 15, which communicates via asecond pump 16 with thesupply tank 9.

The fuel oil is delivered from theoil tank 9 by theoil pump 8, at a pressure of a few atmospheres excess, into thecentral duct 4 of theporous body 1, and it flows from there radially through thebody 1 outwards to theouter surface 17 of theporous body 1. At the same time the fuel oil is heated so strongly by the electric power supplied to theporous body 1 that it emerges into theannular space 11 principally in the form of vapour. From there, the oil vapour flows through thepipe 12 into themixing chamber 13, where it mixes with the combustion air. The mixture emerges through afilter 18 and is ignited by an ignition device (not shown). A blue, non-sooting flame is produced.

The oil which has not vaporised collects in the bottom of the tank and is returned by thepump 16 to theoil supply tank 9.

In a modification of the example described, fuel oil can be supplied to the centrallongitudinal duct 4 from both ends, i.e., also from theend 5. Theporous body 1 can also have a diameter which is equal to or greater than the length.

[n the example described the heating of theporous body 1 takes place by direct passage of current. However, 'this heating can also be provided by an insulated electrical heating coil arranged on the inner peripheral surface, i.e., around the centrallongitudinal duct 4, or on the outerperipheral surface 17 or even inside theporous body 1. In these cases heating takes place by heat convection. The same effect is obtained if, instead of an electrical heating coil, a heating coil traversed by a liquid or gaseous heating medium is provided.

I claim:

1. A process for vaporising fuel oil by passing liquid oil through a heated, porous, substantially cylindrical body consisting of polycrystalline metal whiskers connected with one another metallically at their pointsv of contact, whereby-the improvement comprises passing the oil radially, from inside to outside, through the body and supplying more fuel oil to the porous body than is vaporised.

2. A process as claimed inclaim 1, wherein the body is electrically heated.

3. A process as claimed inclaim 2, wherein the body is directly heated by electric current passing therethrough.

4. A process as claimed inclaim 1, wherein the body is indirectly heated by a heating element in contact therewith.

5. A device for vaporising fuel oil, comprising a substantially cylindrical porous body of polycrystalline metal whiskers connected with one another metallically at their points of contact, and formed with a central longitudinal duct, means for heating said body, an oil supply pipe communicating with said duct, the oil adapted to pass radially from the duct through the heated body to vaporize the oil, means for supplying more fuel oil to the body than is vaporised, a housing surrounding said body with a space therebetween for receiving the oil vapour, means placing said housing in communication with a mixing chamber for mixing the oil vapour with air for combustion, and a discharge pipe from a low point of the housing for discharging fuel oil that has not evaporated.

Claims (5)

1. A PROCESS FOR VAPORISING FUEL OIL BY PASSING LIQUID OIL THROUGH A HEATED, POROUS, SUBSTANTIALLY CYLINDRICAL BODY CONSISTING OF POLYCRYSTALLINE METAL WHISKERS CONNECTED WITH ONE ANOTHER METALLICALLY AT THEIR POINTS OF CONTANT, WHEREBY THE

2. A process as claimed in claim 1, wherein the body is electrically heated.

3. A process as claimed in claim 2, wherein the body is directly heated by electric current passing therethrough.

4. A process as claimed in claim 1, wherein the body is indirectly heated by a heating element in contact therewith.

5. A device for vaporising fuel oil, comprising a substantially cylindrical porous body of polycrystalline metal whiskers connected with one another metallically at their points of contact, and formed with a central longitudinal duct, means for heating said body, an oil supply pipe communicating with said duct, the oil adapted to pass radially from the duct through the heated body to vaporize the oil, means for supplying more fuel oil to the body than is vaporised, a housing surrounding said body with a space therebetween for receiving the oil vapour, means placing said housing in communication with a mixing chamber for mixing the oil vapour with air for combustion, and a discharge pipe from a low point of the housing for discharging fuel oil that has not evaporated.

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