BURNER FOR FOSSIL FUELS

Abstract: A burner for fossil fuels and comprising one or more nozzles or burner tubes (16) through which jets of fuel are injected in a combustion chamber and are ignited and combusted and in which the burner at a place between the outlet of the nozzle or burner tube (16) and a place at or adjacent the outlet (29) of the combustion chamber has a diffusion cup (26) with a centrally mounted diffusion body (27) the cross section area of which is less than the outlet area (29) of the diffusion cup (26) and which is intended to provide a heating of the central parts of the fuel-air jet and a deflection and scattering of the fuel particles and a decomposition of fuel particles. A diffusion body can be formed for instance with a concave meeting surface (37) and in a special embodiment the diffusion body may have several through channels (40) extending between the concave meeting surface (37) and the convex surface (39). At the rear side the diffusion cup (26) has several gas inlets (41) through which exhaust gases enter the diffusion cup providing a pre-heating of the fuel-air mixture.

Description: Burner For Fossil Fuels The present invention relates to an auxiliary device for apparatus for combustion fossil fuels like oil, gas, coal powder, coal powder suspension and other fuels. By burner or burner apparatus is ent, in this connection, any types of burners in which the fuel is injected in a burner chamber through one or more nozzles or burner tubes and in which the combustion takes place in the burner chamber and from which the exhaust gases are discharged. In such apparatus the fuel enters the burner chamber in a form of a more or less focused jet of finely dispersed drops, gas particles or a suspension of drops and particles. The ignition of the jet takes place at the outer portions of the jet, and the combustion successively follows to the center of the jets. At the center of the jet there is a lower temperature than at the outer portions thereof, and in order to get as complete combustion as possible also for the central portions of the flame an excess amount of air or oxygene is supplied. The central portions of the flame have a lower temperature than the outer portions thereof, and in spite of the excess of air or oxygene at the combustion there is often a rather an uncomplete combustion giving non-wanted amounts of unburnt exhaust gases, there is a deposite of carbon, coke or tar. Depending on the excess of air-oxygene during the combustion the flame is cooled down and this cooling gives a further impaired combustion. When combusting liquid fuels like oil or coal suspension the liquid is decomposed when passing the nozzle or the burner tube to form large or small drops. The relatively heavy large drops move mainly in the axial direction of the combustion chamber whereas the small drops are more easily spread diverging outwards from the nozzle or the burner tube. Therefore the large drops are collected at the center of the flame what also gives a less complete combustion at the center of the flame than at the outer portions of the flame. Various attempts have IjURE OMP been made to break down the drops before entering the combustion chamber, especially in connection to burner apparatus having burner tubes. For instance attempts have been made to design the burner tube so that the fuel is evaporized to an optimum degree and the fuel drops are broken down. So far it has not been possible to completely evaporize and break down the drops to exactly the same magnitude, and the problem is still remaining. Therefore it is established that there is an uncomplete combustion depending on several factors, for instance that the temperature at the center of the flame is too low, that the combustion does not follow equally through the entire fuel mass and with greater activity at the outer portions of the fuel jet, that the excess of air or oxygene causes a non-wanted cooling of the fuel and the flame, that large drops are collected at the center of the flame etc. The object of the invention therefore is to solve the problem of providing an improved combustion in a burner apparatus for fossil fuels both by breaking the drops at the central part of the fuel jet into pieces immediately in front of the place of ignition, and by providing an increased temperature at the central parts of the fuel jet and the flame respectively. By these measurements the excess of air or oxygene can be reduced and thereby a further improved combustion effenciency is obtained. The invention also relates to a burner for foss l fuels and comprising one or more nozzles through which the jet of fuel s injected in a burner chamber and is ignited and combusted. At a place between the outlet of the nozzle or the burner tube and the place where the fuel is ignited the burner is according to the invention formed with a centrally mounted diffusion body for heating the central portions of the fuel jet and for deflecting and spreading the fuel particles and for decomposing fuel particle. The diffusion body is mounted in an elongated flame cup so as to provide an obstacle for the innermost central portions of the fuel jet, whereas the fuel-air-mixture can freely pass on all OMPI sides round the diffusion body. The diffusion body further is provided and formed so as to be heated to a high temperature of the burning fuel-air-mixture, whereby said body is pre-heating and evapor zing the central 5 portions of the fuel jet and is cracking and breaking those fuel drops into pieces which hit the diffusion body. At the same time the diffusion.body provides a movement with a successive intimate mixture of fuel and air depending on the deflexion of parts of the fuel jet provided by the diffusion body. 10. Further features of the invention and characteristics thereof will be evident from the following detailed description in which reference will made to the accompanying drawings. In the drawings figure 1 shows an axial cross section through a preferred embodiment of a burner according to the 15 invention. Figures 2a, 2b and 2c show some differentembodiments of a- diffusion body, and figure 3 shows an axial cross section through a part of a burner having a still modified diffusion body. The burner shown in figure 1 comprises an oil burner having a nozzle carrier 11, which is mounted at a neck portion 12 of a 20 flame cup 13. The flame cup 13, in turn, is mounted substantially under sealed connections in the burner housing 14, which is connected to the wall 15 of the oil heater. A nozzle 16 is mounted in the nozzle carrier 11, and by a conduit 17 the said nozzle is connected to a diagram atically illustrated oil pump 5 20. As conventional an air pump 21 is connected to the burner housing 14 for the supply of combustion air. Likewise as conventional a turbulator 22 is mounted between the nozzle carrier 11 and the outlet 23 of the flame cup 13. By struts 24 and a slide ring 25 the turbulator 22 is mounted axially 0 displacable on the nozzle carrier 11. In the illustrated case the burner has only one nozzle 16, but it may also contain several nozzles, for instance two or more angularly mounted nozzles as shown in figure 3. The nozzle carrier 11 with the nozzle 16 is axially displacable inside the flame cup 13, ibr instance from the 5 illustrated normal position to a rear position or a front - mr K EA OMPI position. Likewise the turbulator 22 is axially displacable in relation to the nozzle carrier 11. Depending on the scattering angle of the nozzle, the air pressure from the fan or air pump 21 and other factors, the nozzle carrier 11 and the turbulator 22 are adjusted so that the oil jet from the nozzle substantially completely fills the outlet 23 of the flame cup 13, that is so that the outer periphery of the oil jet falls tangent to the outlet 23 of the flame cup 13. For providing the above mentioned function of heating the central parts of the fuel jets and for evaporizing and breaking fuel drops into pieces the flame cup 13 s extended by a diffusion cup 26, which s mounted in the flame cup 13 and which comprises a diffusion body 27 which over struts 28 is mounted centrally inside the cup. The diffusion body 27, which may be circular or of any other suitable form is mounted at a place in front of the outlet 29 of the diffusion cup 26. Thereby the diffusion body acts as an obstacle for the central portions of the fuel jet, which by the action of said diffusion body are deflected and thereby are mixed with the outer portions of the jet. By the combustion heat of the combustion chamber the diffusion body 27 is heated to a high temperature, and thereby the oildrops of the central portions of the fuel jet hitting or passing close to the diffusion body are heated at the same time as the drops are evaporized or cracked or torn into pieces. For standing the high temperature the diffusion body can be made of any material having a high melting degree, for intance a ceramic material. The turbulator 22 preferable is adjusted to such position between the nozzle 16 and the outlet 23 of the flame cup that the fuel jet is passing freely through the central hole 34 of the turbulator, and so that the turbulator wings 35 give the combustion air a screw movement which does not prevent the oil jet from passing. Further the nozzle carrier 11 and the turbulator 22 should be placed so that the fuel-air jet is passing freely through the outlet 23 of the flame cup and, after having passed the diffusion cup 26 with the diffusion body 27, is freely passing through the outlet 29 of the diffusion cup. In the embodiment of the invention shown in figure 1 the diffusion body is formed as a plane disc. In some cases such a d sc may provide a non-wanted turbulent flow at the rear side of the disc and for this purpose the disc may be formed as shown in figure 2a, whereby the central parts of the fuel jets are deflected more softly or as shown in figure 2b, in which the diffusion disc is almost ball formed providing a smoothly curved deflexion surface at the front side and a l kewise smooth deflexion surface at the rear side. For providing a special effect the diFfusion disc may be designed as shown in figure 2c, in which the front side is concave, and in which the central parts of the fuel jets bump on the front surface and deflect at an angle of more than 90°C and are thereafter passing the edges of the diffusion disc and mix with the other parts of the fuel jets. By the heavy deflexion oil drops are broken into pieces at the same time as the fuel jet is heavily heated in this part of the burner. A special embodiment of a diffusion body is shown in figure 3 in which the body is double-conical according to a so- called diabolo shape. One of the cones 36 is concave forming a surface 37 from which the oil particle bump back and are deflected round the edge of the cone 36. The second cone part 38 is substantially solid and has a convex surface 39 at the rear side giving a good clearance for the deflected parts of the fuel jet and elminating the risk for not-wanted turbulent flow. Several channels 40 extend through the solid cone portion 38, and some part of the fuel jet is passing said channels while being heated, evapor zed and cracked. The fuel jet portions passing said channels 40 and being ejected from said cone part 38 further eliminate the risk of non-wanted turbulent flow at the rear side of the diffusion body. As previously mentioned the burner can be formed with two or several nozzles, and in figure 3 is illustrated one example of a burner having two nozzles which are mounted angularly in relation to each other. Such angular mounting of the nozzles has proved to give a very good action. By raising the temperature of the central portions of the fuel jet and the flame respectively as described above the total ' B jK temperature of the burner apparatus is increased and a more complete combustion is obtained. Thereby the excess of air or oxygene can be reduced, and thereby a further increased combustion temperature and a more complete combustion is obtained. The invention also includes the possibility of providing two or even several diffusion bodies or heater bodies in series after each other. For raising the temperature of the outer portions of the flame or fuel jet gas inlets 41 are provided a the rear side of the diffusion cup 26, and through said gas inlets exhaust gases are taken in from the combustion chamber thereby raising the temprature of the fuel air mixture passing the diffusion disc and leaving through the outlet 29 of the diffusion cup. Similar gas inlets are provided round the neck 12 of the flame cup, and the temperature of the fuel air mixture thereby s raised according to two or even more successive steps while passing the flame cup and the diffusion cup or cups 26 formed like a kind of secondary combustion chamber. It is to be understood that the above description and the embodiments shown in the drawings are only illustrating examples of the invention and that many different modifications may be presented within the scope of the appended claims.

Claims: CLAIMS 1. Burner for fossil fuels and comprising one or more nozzles or burner tubes (16) through which jets of fuel are injected in a combustion chamber and are ignited and combusted, c h a r a c te r i z e d in that the burner is formed with one or more centrally mounted diffusion bodies (27) at a place between the outlet of the fuel nozzle or burner tube (16) and a place at or adjacent the outlet (29) of the combustion chamber for providing a heating of the central portions of the fuel jets or the flame and a deflecting and scattering and breaking into pieces of fuel drops. 2. Burner according to claim 1, c h a a c t e r i z e d in that the diffusion body (27) is mounted in a diffusion cup (26) through which the fuel -air mixture is passing after having passed a flame cup (13), and in that the diffusion body (27) is mounted centrally in the diffusion cup (26) with reference to the longitudinal axis of the burner and as a cross section area which is substantially less than the cross section area of the outlet (29) of the diffusion cup (26). 3. Burner according to claim 1 or 2, c h a r a c t e¬ r i z e d in that the diffusion cup (26) is formed with several gas inlets (41) at a rear part thereof as considered in the flow direction and through which exhaust gases flow into the diffusion cup (26) preheating the fuel -air mixture. 4. Burner according to claim 2 or 3, c a r a c t e¬ r i z e d in that the diffusion cup is a separate unit which is connected to a flame cup of an available burner. 5. Burner according to any of the preceding claims, c h a r a c t e r i z e d in that the diffusion body (27) is mounted in such position at the outlet (29) of the diffusion cup (26) that the diffusion body (27) is heated to a high temperature depending on radiation and convexion from the burning fuel -air mixture, whereby the diffusion body heats the central parts of the fuel -air jet when passing through the diffusion cup (26). 6. Burner according to any of the peceding claims, c h a r a c t e r i z e d in that the diffusion body (27) has a convex rear surface and/or a convex front surface. 7. Burner according to any of claims 1-5, c h a r c t e- r i z e d in the diffusion body (27) has a concave front surface and a convex rear surface. 8. Burner according to claim 7, c h a r a c t e r i z e d in that the diffusion body (27) is formed with several through channels (49) extending from the meeting surface (37). 9. Burner according to any of the peceding claims, c h a r a c t e r i z e d in that several diffusion bodies (5; 15) are mounted- in series after each other in one and the same diffusion cup (26) or in several successive diffusion cups.

Inventors: SANDSTROEM CHRISTER, SANDSTROEM, CHRISTER
Applicants: SANDSTROEM CHRISTER, SANDSTROEM, CHRISTER
Application year: 1984
Main classification: F23D11
IPC codes: F23D11