EP0071626A1

EP0071626A1 - Method for preparation of the cleaning of a burner pot and device for firing waste oil in a burner pot.

Info

Publication number: EP0071626A1
Application number: EP82900545A
Authority: EP
Inventors: Georg Stehr; Heinz Asbeck
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-02-17
Filing date: 1982-02-15
Publication date: 1983-02-16
Also published as: DE3105660A1; WO1982002933A1; DE3105660C2; DE3265506D1; EP0071626B1; JPS58500297A

Abstract

Le four dans lequel de l'huile usee combustible et a haute teneur de residus est allumee et brulee, comprend a sa base une cuvette de combustion (21) ouverte vers le haut et une chambre de combustion (30) eventuellement subdivisee et situee au-dessus de la cuvette. Une alimentation (2, 7, 8) permet d'amener l'huile usee en quantites dosees vers la cuvette (21). Avant l'allumage de l'huile usee, la cuvette vide (21) est chauffee au moyen d'une source de chaleur declenchable (23, 28) jusqu'a une temperature situee au-dessus de la temperature d'inflammation et d'evaporation. Ensuite, des quantites dosees d'huile usee sont amenees sur la cuvette chaude. Les residus de combustion (scories bitumineuses) peuvent etre pyrolyses dans la cuvette au moyen d'une source de chaleur supplementaire apres l'interruption de l'alimentation en huile et la combustion du reste de l'huile dans la cuvette.The oven in which combustible and high-residue used oil is ignited and burned, comprises at its base a combustion bowl (21) open upwards and a combustion chamber (30) possibly subdivided and located above above the bowl. A feed (2, 7, 8) allows the used oil to be brought in metered quantities to the bowl (21). Before ignition of the used oil, the empty bowl (21) is heated by means of a triggerable heat source (23, 28) to a temperature above the ignition temperature and evaporation. Then, metered amounts of used oil are brought to the hot bowl. The combustion residues (bituminous slag) can be pyrolyzed in the bowl by means of an additional heat source after the oil supply has been interrupted and the rest of the oil has been burned in the bowl.

Description

Method and device for igniting waste oils and removing slag.

Method and device for igniting or burning combustible waste oils in a brazier, and method for preparing the brazier for cleaning

The invention relates to a method for igniting or burning combustible, residue-rich waste oils in a furnace, the base with a brazier and above the brazier with a - optionally subdivided - combustion chamber, and with a device with which the waste oil of the brazier is metered can be supplied. The invention further relates to a method for preparing the cleaning of the brazier required for burning waste oil after the fuel supply has been interrupted and the combustible waste oil portion still present in the brazier has been burned out. Finally, the invention relates to a device for burning combustible waste oils in a brazier.

Waste oils are understood to mean, in particular, collected oil mixtures which are produced in the service station operation. The regeneration of these waste oils is possible in principle, but it requires energy and power, which is often not justified. In many cases, these waste oils are burned. They often contain a high proportion of dirt, for example highly viscous gear oil residues, grease, carbon particles, metal abrasion and the like. These "used oils" can also contain paint residues, wood pulp parts and water. Furthermore, waste oils of the type mentioned at the outset can also be understood to include those which contain coal dust, tar oils, bilge oils, refinery waste, chemical, combustible waste and coal-water-oil mixtures. It is essential that the mixture maintains itself in the combustion itself when heated accordingly and that it contains at least portions of a flammable liquid after evaporation. The quality of the waste oil, based on the calorific value of the fuel, can be between 0 and 10,000 kcal. 0 is practically pure water. A mixture of all components is therefore required in a storage tank in order to obtain a combustible waste oil consistency.

So-called "old oil stoves" are known, for example from CH-PS 368 255. The known combustion device has a columnar housing, at the base of which a brazier is arranged. The fuel is metered into the brazier via a feed line. The feed line ends above the brazier, so that the waste oil drops from its mouth into the brazier.

The device is ignited by first introducing egg-boiling fuel oil into the brazier and this with

With the help of an ignition wick ("torchon") is ignited. When the brazier has warmed up sufficiently, the flow of the actual used oil begins. It can be observed that a lot of smoke is developed both in the ignition phase and at the beginning of the actual combustion phase and that the flame blows for a relatively long time.

If the waste oil supply is switched off, the flame will continue to burn for a certain time until all vaporizable residues have burned out. Reached during burnout the temperature of the actual brazier about 350 to 400 ° C. This temperature, which is even fallen below during the burnout, leaves highly viscous, carbon-rich bitumen residues, carbon-rich "slag", etc. in the brazier, these substances being very intimate and heavy Make a connection with the brazier to be released. These residues, called "bitumen slag", have to be laboriously scraped out or beaten out of the shell after the combustion of approx. 30 to 80 liters of used oil.

It is therefore the task of specifying a method and a device for the combustion of waste oil to improve the known device, the use of which facilitates the ignition process and can be carried out in a controlled manner. The device or a method which can also be carried out with the device should open up the possibility of also simplifying the cleaning of the brazier after the waste oil has been burned.

These tasks are achieved with the same means with which the combustion of flowable waste oils is made possible, in that before the waste oil is ignited, the empty brazier is at least partially heated up to a temperature above the ignition and evaporation temperature of the waste oil by means of an additional heat source that can be switched off . Subsequently, used oil is placed on the heated dish and ignited there, preferably without the aid of further measures. However, it is also conceivable that additional ignition aids, for example glow igniters, are used.

After the ignition, the additional heat source is switched off; the combustion of the fuel that is fed in maintains itself. The brazier to be heated can also be used to prepare the cleaning required for waste oil combustion. For this purpose, after the fuel supply has been interrupted and the fuel still in the brazier has been burned out, the remaining fuel (the "bitumen slag") is pyrolyzed with the aid of the heat source which is switched on again.

The method for ignition and the device suitable for this, as well as the usual burner operation, can of course also be carried out with high-purity fuels, for example with heating oil EL, in which hardly any ash quantities are produced. The known stoves operated with heating oil, however, can in no case be operated with waste oil. Therefore, the technical effort for the device described below is primarily justified for the combustion of heavily contaminated waste oils.

Since the temperature of the brazier must reach both the ignition and the pyrolysis temperature, it must be possible to bring the brazier to a temperature higher than 400 ° C. The pyrolysis is carried out, for example, at a temperature of 700 to 800.degree. C., whereas an ignition and evaporation temperature of approx. 350 to 400.degree. Different temperatures can also be set by an appropriate thermostat control device, the brazier temperature T being between 400 ° and 800 ° C.

A device for performing the methods and for burning combustible waste oils in a brazier has a brazier at its base. Above the brazier is a - if necessary divided - Combustion chamber arranged. It is known to let the fuel drip into the bowl from above, or to let it flow in laterally or centrally with respect to the surface of the brazier. Basically, various known inflow options can be used. In order to be able to carry out the above-mentioned methods in addition to the usual burner operation, at least one additional heating device is preferably arranged below the brazier. These additional heating devices are preferably electrically operated

Heating coils or coils. Inductive heating of the brazier is also possible. For special cases it is also conceivable to use a switchable gas burner with a burning lance ending below the brazier. It is essential that the principle of the additional heating which can be switched on and off is observed.

In order to save energy and for faster heating before the ignition process, the brazier is equipped with a recess with a surface structure underneath the end of the waste oil supply line. This trough, which has, for example, a corrugation or a waffle structure, has a somewhat thinner base and is locally provided with an increased heating, so that it heats up in a shorter time than the rest of the brazier. The trough has an oval or kidney-shaped outline and takes up about a fifth to a third of the bottom surface of the brazier.

The brazier preferably has a relatively high heat capacity, it is therefore cast in particular from cast iron (DIN 1493) and then face-turned on its underside. On its upper side (flame side), the brazier is provided with concentric grooves, waffles or humps or some other surface-enlarging structure, similar to the trough area. This structure means that the suffering frost see phenomenon does not develop; on the contrary, such a surface structure means that good warm contact is quickly established between the old oil droplets and the surface. The size and diameter of the brazier depend on the capacity of the combustion device.

The oil supply line preferably ends at a distance of between 2 and 20 cm, preferably between 7 and 10 cm, above the brazier or trough. This arrangement has the advantage that the energy contained in the falling oil droplets breaks them up and thus enables a faster evaporation effect. The phenomenon of suffering which can be observed in the initial phase and which counteracts rapid evaporation of the droplets is then practically completely suppressed by the large number of relatively small droplets.

To increase the kinetic energy of the impinging droplets, the inflow nozzle, which forms the end part of the feed line, is arranged at an angle of inclination between 25 and 35 with the horizontal. The inflow nozzle also has a much larger clear cross-sectional area than the actual oil supply line, which ends at the inflow nozzle. This prevents the used oil in the end region of the oil supply line from filling the entire cross-section, which generally leads to undesirable afterflow phenomena when the oil flow is switched off.

Further features that are mentioned in the subclaims are explained on the basis of the description of exemplary embodiments which are illustrated in the drawing. The figures show: Figure 1 shows a device for the combustion of waste oils according to the invention, seen from the side;

Figure 2 shows the device of Figure 1 seen from the front;

FIG. 3 shows a detailed illustration with another ignition device;

Figure 4 is a plan view of part of the brazier with the trough;

Figures 5 and 6, an oil supply nozzle with cleaning device, seen from the side and from the front;

Figure 7 shows a special type of fresh air supply.

The device for the combustion of waste oil according to Figures 1 and 2 has the outer shape of a so-called warm air heater. In the base of the device, a storage container 1 is arranged, in the. the waste oil is filled. The storage container 1 has, for example, a capacity of 145 liters. A sump vessel 5 projecting downwards is attached to the side of the storage container 1, in which coarse deposits separate out. Above the sump vessel 5, but within the storage container 1., a cylindrical strainer 6 is placed around the sump vessel 5, which shields the entrance area of a metering oil pump. The oil pump 2 is usually a Zahnradpurαpe or another pump that can deliver and deliver the used oil in a metering manner.

As can be seen, the suction opening of the oil pump 2 is within the strainer 6 but above the sump level. The oil pump 2 is driven via a shaft 4 by a motor 3 which is arranged on a cover 9 above the storage container. A connecting to the oil pump 2 supply line 7 is from the The strainer basket 6 is led upwards and directs the pumped oil to an inflow nozzle 8. The oil pump 2 with its motor can be removed from the strainer basket 6 to enable cleaning after removing the cover 9. The inflow capacity in the illustrated embodiment is approximately between 0.5 to 3 kg of oil per hour. The pumped amount of used oil can be infinitely metered within this range.

Below the storage container 1, which is designed as a base, four carrying feet 17 are attached, which are height-adjustable for level compensation.

The actual device according to the invention, in the present case designed as a hot air-generating thermal bath 10, is externally similar in size to similar devices of the same purpose. The device has a housing 11 which is delimited on its base side 12 by the storage container 1. A heat exchanger 13 is attached to the head part of the housing 11. An exhaust pipe 14 leads into the atmosphere via a chimney. It is possible and appropriate to also install corresponding known filters in this chimney.

In the lower part of the housing 11, a burner box 14 is inserted, the rear wall of which forms part of the housing 11. This part of the housing is mounted on the storage container via intermediate feet 15. A burner pot 18 is provided within the burner box 14 and has a cylindrical wall which is at a distance which corresponds to approximately half the diameter of the burner pot. Distance from the wall of the burner box 14 has.

In the bottom of the burner pot 18 is a heating and insulating plate 19, on which a brazier 21 is placed. The brazier 21 has an approximately pan or plate shape. Your upright Standing walls open from the bottom 22 of the brazier 21, so that the bowl has a larger clear width at its upper edge than corresponds to the floor area. The brazier 21 consists of cast iron, the wall thickness being dimensioned according to professional experience and heat capacity so that there is a constant evaporation and combustion of the incoming liquid waste oil. In the heating and insulating plate 19, directly below the bottom of the brazier 21, an electrical resistance wire coil 23 is installed, the lead wires of which, taking into account the appropriate "heat protection conditions, lead to the outside. With the help of the coil 23, the brazier 21 can reach a temperature of 350 to 800 ° C. (red heat) In order to enable the brazier to be partially heated to a greater extent, the brazier is provided with an additional heating device, namely a further high-temperature coil 28, in the area directly below the mouth of the inflow nozzle 8 28 lies directly under a recessed bottom 27 in the bottom 22 of the brazier 21, which in the present case has an approximately kidney-shaped shape and occupies approximately 15% of the bottom surface of the brazier 21. The bottom recess 27 is provided with a corrugated structure the waste oil droplets that have fallen into the hollow 27 be smashed directly and find the most irregular, large-area contact with the heated surface. These measures serve to prevent the Leidenfrost phenomenon, that is, to form a vapor layer around the droplets, which prevents rapid evaporation. When ignited, the trough area also heats up significantly more than the rest of the brazier. A considerable amount of heat is therefore concentrated on a small amount of waste oil, so that this amount evaporates immediately. This gives the possibility that the first drop falling on the brazier 21 brings about the ignition, since it hits in the area of the hollow and bursts there and evaporates immediately. The ignition of this first droplet takes place in an environment in which there is excess air. No smoke occurs because the ignition is almost explosive.

A temperature sensor 37 is also installed below the brazier 21, which can also be connected directly to the brazier 21. This temperature sensor is used to monitor and control the processes as described below. As already indicated, the brazier 21 is surrounded by the burner pot 18. Above the edge of the brazier 21, the jacket of the burner pot 18 is provided with numerous air bores 20 through which the combustion air enters. Around the top third. of the burner pot 18, a support shoulder 38 is stamped into the jacket, on which a glow hood 40 rests at the edge. This cast steel hood 40, which can be heated to red heat, is also provided with perforations 41, so that the combustion gases, including those which have not yet been completely burned, can pass through the perforations 41 and burn in the area of the hood 40. The hood 40 has approximately the shape of a truncated cone, which has a further opening 42 at its upper end, into which a glow converter insert 43 can be inserted. The glow converter insert consists of thin wire coils, made of refractory wire. This glows after a short burning time, so that good afterburning is also guaranteed in its area. These parts ensure that all combustible components of the waste oil also burn, completely to form H ₂ O and CO ₂ .

The hot, partially still burning and burned gases are passed through a combustion chamber 30 through the lateral surfaces of the glow hood 40, which form an angle of approximately 30 to 60 ° with respect to the horizontal, which directly adjoins the burner box 14 upwards connects. The combustion chamber 30 is also cylindrical. The jacket 31 of the combustion chamber 30 is wing-like provided with numerous radiation fins 32 which improve the thermal contact with the air flowing past on the outside. The combustion chamber 3θ is closed at the top by a cover 33 and opens into an outlet opening 34, which is directly followed by the labyrinth heat exchanger 13.

In Figures 1 and 5 and 6, the inlet port 8 is shown. The mouth 50 of the inflow nozzle ends freely within the burner pot 18 above the brazier trough 27 at a height of approximately 15 centimeters above the surface. The inclination of the inlet connection 8 with respect to the horizontal is approximately between 25 and 35 °. It should also be noted that the clear cross-sectional area of the inlet connection 8 is substantially larger than that of the oil supply line 7, which ends at the inlet connection 8. The inlet connector is also equipped with the same clear cross-sectional area from the inlet opening 51 to its bottom opening 50. The cross section of the opening does not narrow. The oil pumped by the oil pump 2 through the inlet opening 51 therefore flows primarily on the lower, inner lateral surface of the inlet connection, increasing in speed, down to the mouth 50. There it emerges and is broken up into fine droplets at the edge. This flow principle largely prevents incrustation or clogging of the inlet connector 8. To prevent the inlet connector 8 from heating up too much, it is also arranged so that it extends from the front of the burner box 14 through the air-guiding space 16 and only on a relative short piece within the burner pot 18. In addition, the internal cavity of the inlet connector is in communication with the atmosphere. It is therefore not possible for the oil to flow back into the nozzle into the fuel line 6. Because of the very different quality of the used oil, it can also be deposited within the inlet connection 8 in difficult exceptional cases. In this case, a cleaning piston 52 which is displaceable within the nozzle cavity is provided, which, as shown in FIG. 6, has approximately the shape of a Maltese cross on average, with free spaces 54 being left between the arms 53 of the piston, through which the waste oil despite the installed piston can flow. The cleaning piston 52 is guided with a rod 55 out of a cover 56 of the connector 8 and ends in a knob 57. A helical spring 58 is installed between the knob and the cover. Against the force of the spring 58, the piston 52 must be pressed inwards, and after each impression it automatically moves out again into the old position. This ensures that the area of the mouth 50 is always exposed. The Maltese cross shape of the piston is therefore chosen so that scrapers or cutting edges can be attached to the heads touching the inside of the inflow nozzle 8.

Tilting and frequent cleaning work together to create an unhindered, accelerating oil flow within the inlet connection 8, which is divided into small droplets, the vertical velocity component largely communicating with the droplets and leading to an increase in the kinetic energy of these droplets. Parts that are scraped off by the piston 52 also fall into the brazier and are burned or pyrolyzed there.

The automatic program of the warm air heater is set so that the brazier is heated first before the first oil runs in. If, due to the high temperature of the brazier, automatic ignition usually occurs in the region of the trough, it must be ensured, however, that even waste oils with relatively high ignition levels can be reliably ignited. For this purpose, an ignition device 39 is provided, which is provided with an incandescent body 45, which is installed concentrically in the tubular housing of the ignition device 39. The filament consists of a perforated, ceramic tube with a built-in heating coil. The program control brings the incandescent body to red heat before the oil is admitted, so that the fuel-air mixture ignites immediately. The measures mentioned prevent the occurrence of smoke.

Instead of the incandescent body 45, the ignition can also be carried out with the aid of an infrared reflector igniter 46. In this igniter, a heating coil 48 is arranged within a reflector housing 47. The heat radiation is focused in the region of the trough 27 and also leads to an inflammatory point. In addition, it is possible to connect an air line 49 to the reflector igniter 46, which directs a flow of combustion air onto the ignition area at the moment of ignition.

The aforementioned devices serve to safely ignite the used oil.

In the wall of the burner box 14 and extending into the burner pot 18, a photocell arrangement 24, which monitors the burning process, is also installed, the associated photocell 25 essentially receiving the radiation emanating from the area of the trough 27 within the brazier. The photocell arrangement 24 takes over the continuous monitoring of the burning process. The photocell arrangement 24, which essentially consists of an eyepiece tube, is also provided with a cooling air nozzle 26 which is supplied with cooling air, which reaches the end of the eyepiece tube and also blows into the combustion area of the depression. This is ge ensured that the combustion area is always supplied with combustion air, so that as long as there is still unburned waste oil in the brazier 21, combustion is also maintained. The flame only extinguishes when there is no longer any combustible material, and this extinguishing is then also reliably observed by the photocell arrangement 24.

The air flow is explained on the basis of FIGS. 1 and 7. The suction openings for the room air to be heated and that of the combustion air are located above the floor at a height of around 1.40 meters. This arrangement has been chosen so that no vapors of low-boiling organic compounds are sucked into the floor area, which could possibly lead to a deflagration within the combustion chamber volume.

A suction opening 70 for the combustion air is shown in FIG. 7. Via a line 71, the sucked-in air is fed to a combustion air blower 72, which presses the combustion air, metered according to the corresponding heat output, into the burner box. The air is distributed within the burner box and is pressed through the perforations 20 into the burner pot, where the combustion takes place or the fuel gases are generated. The caching combustion then takes place within the combustion chamber 30. The burned gases enter the heat exchanger 13 and leave it as exhaust gas through the exhaust pipe 35.

At the same time, the room air or the fresh air to be heated is attracted through a larger opening 74 in cross section and fed through a guide channel 75 to a warm air blower 76 which guides the air to be heated upwards through the heat exchanger 13 to the thawing elements heated by the exhaust gases. The heated air arrives through the head 77 of the thermal bath 10 Different air outlets: air outlet 78 in the upper area and a lower air outlet 79 in the lower area. The air duct is isolated by correspondingly insulated walls of the housing 11. In particular, the hot burner parts inside the device 10 are prevented from coming into contact with the outside world at all. Burning on the outer parts of the device is therefore not possible.

Furthermore, as can be seen from FIG. 2, there is also a tank fill indicator 80 with a corresponding float 81 and an oil drain screw 82 on the sump 5. The brazier 18 including the additional heating device is arranged in a drawer 83 which can be pulled out relative to the housing.

Another fuse is also provided for safe operation. In the event that, despite the monitoring by the photocell arrangement 24, the flame should go out and the oil supply is not interrupted, unburned fuel runs over the edge of the brazier 21 after a certain time. To sense this malfunction, an overflow control sensor 87 is located in the lower part of the housing intended. The furnace function is controlled by an electronic control 58, which is attached to the side of the housing 11 in a switch box.

Functional description

At the beginning of the ignition and burning process, the brazier 21 is empty. After switching on the hot air heater, the heating coil 23 and the high-temperature coil 28 are acted upon by heating current. They let the bowl heat up to a total temperature of around 400 ° C and in the bowl area to 800 ° C. With the help of the temperature sensor 37, the temperature of the brazier 21 is continuously monitored. at When the temperature required for combustion and ignition is reached, the oil pump 2 is started. A thin stream of waste oil is brought into motion via the line and via the inlet connection 8 and flows in fine droplet form through the mouth 50 into the brazier 27. At this point in time, the ignition device 45 or 46 has also started to operate. The first drop that falls on the heated trough bursts there and is immediately vaporized intensively and briefly. As tests have shown, an ignition takes place immediately, so that the further waste oil flowing in is also set on fire immediately.

The resistance wire coil 23 remains switched on during this first ignition process, but is kept at a lower temperature. The other, falling drops of oil burst and immediately come into intensive contact with the surface of the racing bowl. Since the ignition temperature has been exceeded, the fuel-air mixture located above the brazier ignites immediately. As soon as the photocell arrangement 24 has observed the ignition, the blower 72 is also switched on, which ensures a constant flow of combustion air.

After a certain, adjustable time delay, the flame emanating from the brazier has heated the brazier to such an extent that the combustion maintains itself. It is assumed that the brazier has a relatively high heat capacity due to its material.

In the event that ignition does not take place after a certain time, for example four seconds, the oil pump 2 is switched off via a time delay relay and the fan 72 is also switched off after a further time delay. The ignition process can then be repeated after a certain time. Usually, however, an ignition Repeat required.

During the combustion, only the oil pulp 2 and the combustion air blower 72 are in operation to maintain the flame. The other heating and ignition devices mentioned in the description are switched off during this time. The incoming warm air blower pushes indoor or outdoor air through the various heat exchangers. The heated air never comes into direct contact with the exhaust gases.

The device 10 is switched off by interrupting the oil flow by switching off the oil pump 2. After a further time delay, the combustion air blower 72 is switched off. As long as there are flammable waste oil residues inside the bowl, they will be reduced by the small amounts of air created by the photo

Cell assembly 24 and the stationary combustion air blower 72 are sucked, still burned and the flame from the photocell 25 is observed. The resistance wire coil 23 is switched on and the pyrolyzing is initiated. After the combustion process had ended, a tough, solid bitumen slag had formed in the shell due to the relatively large amount of foreign substances in the waste oil, but this still largely contained carbon and other combustible substances. The resistance wire coil 23 heats the brazier up to a temperature of 600 to 700 ° C. The combustible residues are then pyrolyzed and burned on the heated pan. It can be seen that the solid bitumen slag disintegrates into residual dust during this pyrolysis process, which can be easily removed with the brazier after pulling out the box. The pyrolysis of the bituminous slag takes about five minutes. After this time, the coil 23 turns off again.

Since the heating unit including the brazier is located in a drawer 23, this part of the device can be pulled out. Maintenance and repair door work is much easier.

The device described above is suitable both for heating rooms and for generating steam or ice water. It can be kept in operation fully automatically. Their maintenance is largely problem-free. In particular, the ash quantities are reduced to a level not previously known in so-called waste oil stoves. During operation, it has also been shown that fly ash, which may contain environmentally harmful components of heavy metal, can be easily removed using filter devices.

An intensive heat exchange is also carried out by the lamellar-coated jacket of the combustion chamber 30. These fins are made of copper, for example. The air outlet openings are adjustable in direction and intensity. According to measurements, the exhaust gas temperatures are around 180 to 200 ° C. The CO ₂ content of the exhaust gases is measured at around 10% by volume. This results in an overall efficiency of 92%. Due to the meterability of the combustion air via the combustion air blower 72 and that of the waste oil via the oil pump 2, stoichiometric combustion can also be practically maintained. The soot content is extremely low. Only very small amounts of soot can be observed even at the beginning of the combustion process.

The device can easily be operated up to an amount of 0.5 kg of waste oil per hour. With this small supply, only one entertainment flame is practically maintained in the brazier. Even with these low throughputs, stoichiometric conditions can still be maintained. It is possible to restart the power in a short time.

Claims

P at en t claims

1.Procedure for igniting and burning combustible, residue-rich waste oils in a furnace, which has at its base an upwardly open brazier (21) and above the brazier with an - optionally subdivided - combustion chamber (30), as well as a device (2 , 7, 8), with which the used oil can be fed to the brazier (21) in a metered manner, characterized in that before the used oil is ignited, the empty brazier (21) by means of a switchable additional heat source (23, 2%) at least partially is heated to a temperature above the ignition and evaporation temperature of the waste oil, then waste oil is metered onto the heated brazier (21) and ignited.

2. A process for preparing the cleaning of the brazier (21) required in the case of waste oil combustion after the fuel supply has been interrupted and the combustible waste oil portion still present in the brazier has been burned out, characterized in that the remaining fuel residues (bitumen slag) are pyrolyzed in the brazier with the aid of an additional heat source (23, 28) which is to be switched on and which heats the brazier (21).

3. The method according to claim 1 or 2, characterized in that during the ignition and / or pyrolysis process, the brazier (21) is at least partially brought to a temperature T of 400 ° C ≤ T ≤ 800 ° C.

Device for burning combustible waste oils in a brazier, suitable for implementation of the method (s) according to claim 1 and / or 2, characterized in that at least one additional heating device (23; 27) is arranged in the region, preferably below, the brazier (21).

5. The device according to claim 4, characterized in that the brazier (21) has a bottom recess (27) below the end of an old oil inflow nozzle (8).

6. The device according to claim 5, characterized in that the bottom recess (27) has an oval or kidney-shaped outline and occupies about 1/5 to 1/3 of the bottom surface of the brazier (21).

7. The device according to claim 4-6, characterized in that below the brazier (21), preferably in the region of the trough (27), a further additional heating device (28) is arranged.

8. The device according to claim 4-7, characterized in that below the brazier (21) at least one electrical resistance heater, in particular a heating coil (22; 28) is arranged.

9. The device according to claim 4-7, characterized in that the brazier (21) is inductively heated.

10. The device according to claim 4, characterized in that the burner consists of cast iron according to DIN 1493.

11. The device according to claim 4 - 10, characterized in that the temperature of the Brennsohale (21) with a temperature sensor (37) can be monitored.

12. The apparatus according to claim 4-6, characterized in that the inflow nozzle (8) ends freely at a distance between 2 and 20 cm above the brazier (21) or the trough (27).

13. The apparatus of claim 4 and 12, characterized in that the feed nozzle (8) forms an inclination angle between 25 ° and 35 ° with the horizontal.

14. Device according to one of claims 4-13, characterized in that the inflow nozzle (8) has a substantially larger clear cross-sectional area than an oil supply line (7) which ends at the inflow nozzle (8).

15. The apparatus according to claim 14, characterized in that the inlet connector (8) from the inlet opening (51) of the oil supply line (7) to the bottom mouth (50) is equipped with the same clear cross-sectional area.

16. The apparatus according to claim 14 or 15, characterized in that the inner cavity of the feed connector (8) is in communication with the atmosphere.

17. Device according to one of the preceding claims 4-16, characterized in that the feed nozzle (8) is provided with a cleaning piston (52) which can be displaced within the nozzle cavity.

18. The apparatus according to claim 17, characterized in that the cleaning piston (52) with a plurality of peripherally spaced scraping or cutting heads (53) is provided.

19. The apparatus according to claim 17 or 18, characterized in that the cleaning piston (52) is displaceable with the aid of a piston rod (55) projecting from the connecting piece (8).

20. The apparatus according to claim 19, characterized in that the piston rod (55) against a spring (58) in the direction of the neck opening (50) is displaceable.

21. Device according to one of claims 4-16, characterized in that the inflow nozzle (8) is arranged at least over part of its length in the combustion air supply flow.

22. The apparatus according to claim 4, characterized in that a heatable to red heat incandescent body (45) is arranged as an additional ignition device above the brazier (21).

23. The device according to claim 22, characterized in that the incandescent body (45) consists of a perforated tube with a built-in heating coil.

24. The apparatus of claim 4 and 5, with a Brennvαrgang monitoring photocell arrangement, characterized in that the photocell (25) of the photocell arrangement (24) essentially receives the radiation emanating from the area of the trough (27) within the brazier (21).

25. The device according to claim 24, characterized in that the photocell arrangement is installed in a cooling air tube, which ends in the region of the trough (27), so that the cooling air flowing through the tube as

Combustion air emerges above the trough (27).

26. The apparatus according to claim 4, characterized in that a reflector igniter (46) is used as an additional ignition device, which generates a concentrated heat radiation in the region of the trough (27).

27. The apparatus of claim 22 and 26, characterized in that the ignition devices are connected to an air supply with which combustion air can be introduced into the region of the maximum heat.

28. The apparatus according to claim 4, characterized in that the combustion chamber above the brazier (21) is covered by a perforated glow hood (40) through which the combustion gases flow.

29. The device according to claim 28, characterized in that the glow hood (40) is designed as a truncated cone with an upper opening into which a tubular glow converter (43) is installed.

30. The device according to claim 4, characterized in that the brazier including the additional heating device is arranged in a pull-out drawer (83) relative to the overall device.