IE881683L

IE881683L - Pressure jet burner

Info

Publication number: IE881683L
Application number: IE168388A
Authority: IE
Original assignee: William Henry Deryk Morris; Michael Peter Walshe
Priority date: 1988-06-03
Filing date: 1988-06-03
Publication date: 1989-12-03
Also published as: IE56250B1

Description

■> '» 4 O 0 The present invention relates to improvements in pressure jet burners of the type which use oil/gas as fuel.

Various systems for burning oil fuel to release 5 useful heat have been in use for very many years. Some of these systems rely on vapourising oil from a heated surface or from a wick. These systems also use manual ignition and cannot be said to be fully automatic but they do have the virtue of silence. All other forms of 10 automatically controlled oil burners rely on the use of a fan to force the required quantity of air into a combustion chamber together with a pump to force the oil fuel, usually at a substantial pressure into the same area. Any such automatically-controlled oil burner will 15 also require a means of ignition, contain safety devices, and a suitable control system.

Known limitations of this type of oil burner, (which are generally classified as "pressure-jet" burners) include a relatively high noise level, a 20 tendency for the working parts of the burner including the oil pump and the fan to work at too hot a temperature, difficulty in achieving precise control of the airflow from the fan because the final expulsion of the air from the fan occurs at a distance that is much 25 less than the diameter of the fan, an unduly turbulent and fluctuating air supply, and an air supply with no means of receiving significant degree of preheating although it is well known that combustion conditions are improved when the incoming air is properly preheated. 30 It is an object of the present invention to mitigate the above problems. 3 According to the invention there is provided a pressure jet burner comprising a housing supporting a blast tube above an air supply means, the blast tube being disposed towards a front end of the housing and projecting 5 rearwardly, and means for supplying a fluid type fuel to the blast tube wherein the blast tube is inclined angularly upwardly.

An embodiment of the invention will now be described by way of example, with reference to the 10 accompanying drawings in which: Figure 1 is a perspective view of pressure jet burner according to the invention; Figure 2 is a diagrammatic sectional view of the burner of Figure 1 in a domestic cooker/boiler; and 15 Figure 3 is a diagrammatic cross-sectional view of the pressure jet burner of Figure 1.

Referring now to the drawings wherein similar numerals have been used to indicate like parts, there is shown therein, a pressure jet burner generally indicated 20 at 10 according to the invention. The burner 10 comprises a generally hollow housing 11 having a rear part 12 which contains a fan 13, a generally horizontal air duct 14 and an expansion chamber 5. The fan 13 is driven by a motor 16 mounted on the rear part 12, and 25 the motor 16 also drives a fuel pump 17. Fuel is supplied to the fuel pump 17 via a conduit 18 and the fuel is delivered from the pump 17 to a nozzel (not shown) in a blast tube or combustion chamber 19 via a feed line 20. As shown, the blast tube 19 is generally 30 cylindrical and is mounted adjacent the front end 22 of the housing of the expansion chamber 15 and is inclined angularly upwards and in the direction of the rear part 12 of the housing 11. The blast tube 19 projects upwardly at an angle of between 10® to 80° relative to 35 the horizontal and more preferably at an angle of between 25° to 60°. The rear part 12 of the housing 11 has a number of small apertures 21 to enable air to be 4 drawn into the housing 11.

The blast tube 19 also includes conventional ignition electrodes (not shown) to ignite the fuel/air mixture. The apparatus will also include a conventional 5 control system which is not shown in the drawing and which may include an on/off switch, thermostat control, power supply for the motor and ignition electrodes and a timer.

In Figure 2 the pressure jet burner is shown 10 located in the ash pit 30 of a conventional domestic solid fuel cooker. As shown, the burner 10 is located in the ash pit region 30 with the rear part 12 innermost so that the blast tube 19 is directed rearwards into the zone 31 to be heated. The burner 10 is shielded from 15 the heating zone 31 by means of a ceramic heat shield 32 which is supported on the horizontal air duct part 14. In addition, the ceramic heat shield 32 may be supported on a sheet of steel (not shown).

A slidable damper plate 42. is provided to control 20 the flow of air from the fan 13 to the expansion chamber 15. The damper 42. is provided to adjust the size of a variable aperture 41 between the rear part 12 and horizontal part 14 of the housing 11. The damper 4?— comprises a flat rectangular metal damper plate 25 having an upstanding boss 43 which has a threaded aperture 44 in which a threaded rod 45 is engaged. The threaded rod 45 is rotatably secured to the front and rear end walls 46, 47 respectively of the housing 11. The rear end 48 of the rod 45 passes through an aperture 30 49 in the rear end wall 47 of the housing 11 and has an enlarged end collar 50 to retain it in place. Similarly, the front end 51 of the rod 45 passes through an aperture 52 in the front wall 46 of the housing 11 and has an enlarged end collar 53 to retain it in place. The 35 front end 51 of the rod 45 also has an operating knob 54 fixed thereto to enable a user to readily rotate the rod 45. Thus, rotation of the rod 45 by rotating the knob 54, causes the rod 45 to drive the damper plate.42 forwards or rearwards to adjust the size of the aperture 41 and thus control the airflow from the fan 13. A 5 suitable stop member 60 is provided to limit the forward movenejt: of the damper plate 42.

In use, with the motor 16 energised, the pump 17 supplies fuel to the nozzle (not shown) in the blast tube from where it is emitted in the form of a fine 10 spray, and is ignited by the electrodes (not shown).

With the fan 13 in operation, air is drawn into the housing 11 via the apertures 21 and as the air must enter the ash pit area 30 via the ash^ait door 40, the air travels in the direction of the arrow A thus acting 15 to cool the motor 16. The air is also preheated in this way.

The air entering the apertures 21 is directed upwardly through the variable aperture 41, into the rear of the horizontal air duct 14 and into the expansion 20 chamber 15. The effect of the expansion chamber 15 is to reduce the velocity of the air flow while maintaining the static pressure. It has been found that this velocity reduction reduces the noise level from the combustion head or blast tuba 19.

Because of its low noise level and efficient use of fuel the invention may be used in cookers designed for oil firing or as a combustion unit designed to permit the use of oil fuel where solid fuel had previously been used. The invention can also be used to advantage for 30 any application where a particularly quiet and effective oil burner is needed. 3

Claims

CLAIMS:

1. A pressure jet burner comprising a housing supporting a blast tube above an air supply means, the blast tube being disposed towards a front end of the 5 housing and projecting rearwardly, and means for supplying a fluid type fuel to the blast tube wherein the blast tube is inclined angularly upwardly.

2. A burner as claimed in Claim 1, wherein the air supply means comprises a fan disposed rearwards of said 10 blast tube.

3. A burner as claimed in Claim 1 or 2, wherein the blast tube communicates with the fan via a generally horizontal air duct.

4. A burner as claimed in Claim 3 wherein the blast 15 tube communicates with the generally horizontal air duct via an expansion chamber, disposed adjacent a front end of the horizontal air duct.

5. A burner as claimed in Claim 3 or 4, wherein the fan is arranged to direct air upwardly through a variable 20 aperture into the rear end of the generally horizontal air duct.

6. A burner as claimed in Claim 5, wherein the variable aperture is adjustable in size by means of a slidable damper plate. 25

7. A burner as claimed in Claim 6, wherein the damper plate is engaged with a rotatable threaded rod passing through the housing such that the rotation of the rod causes linear movement of the damper plate.

8. A burner as claimed in Claim 7 wherein the rod has an operating knob at the front end of the housing.

9. A pressure jet burner substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. F. R. KELLY & 00., AGENTS FOR THE APPLICANTS.