Combustion – Process of combustion or burner operation – Flame shaping – or distributing components in combustion zone
Reexamination Certificate
2000-08-17
2003-06-10
Bennett, Henry (Department: 3743)
Combustion
Process of combustion or burner operation
Flame shaping, or distributing components in combustion zone
C431S181000, C431S350000, C060S749000, C060S723000
Reexamination Certificate
active
06575733
ABSTRACT:
This applications claims the priority of international patent application number PCT/EP98/07175, filed Nov. 10, 1998, and of German patent application number 197 49 688.1, filed Nov. 10, 1997, both of which are incorporated herein by reference.
The invention is related to a method for the combustion of fuels, in which the fuels are burnt together with air, possibly with the addition of water and/or an oxidizing agent, and a reactor for such a combustion method with a reaction chamber having supply openings for the fuel, the air, possibly the water and/or an oxidizing agent and an outlet opening for the combustion products.
An apparatus and a method for the combustion of oil with the addition of water are known of WO95/23942, in which oil is introduced into a combustion chamber until an oil bath has formed, which is then preheated to a temperature between 250° C. and 350° C. Then water is sprayed onto the surface of the hot oil bath, which results in a flame eruption with the simultaneous supply of air into the combustion chamber. The level of the oil bath should not remain under a height of 3 to 4 mm during combustion in order to prevent an interruption of the combustion. The apparatus used to this purpose includes in general a combustion chamber in the form of a frustrum of a pyramid or a cone with lateral supply openings for oil and water from corresponding reservoirs. The oil bath is electrically heated. Air enters along with the water into the interior of the combustion chamber. The flame with a temperature of 1200° C. to 2000° C. is introduced into an oven via a cylindrical tube for heating purposes.
In this known method of combustion especially of waste oils the temperature gradient appearing in the oil bath in the direction to the bottom has proved to be disadvantageous, because the bottom temperature can be lower than the evaporation temperatures of heavy fractions in the waste oil the result of which is that the latter form a not completely burnable oil mass at the bottom of the combustion chamber. Injecting the oil via a nozzle is not practical, because residues and highly viscous components in the waste oil will lead to a clogging of the nozzles. Moreover the entire apparatus with its feeding and preheating means gets constructively complex. Because of the remaining residues the process control is hard to perform, especially when shutting down. Therefore the facility is not suited for a continuous operation.
From GB 765 197 an apparatus for the combustion of liquid and liquefiable fuels is known, which consists of a cylindrical combustion chamber with an adjacent fire space, which is open to the top. The liquid fuel is radially or tangentially introduced into the interior of the combustion chamber, and air is separately introduced tangentially, while the fuel is contacting the inner surface of the combustion chamber and is evaporated and burnt there. Temperatures appearing in the fire space are between 1500° C. and 1800° C. With incomplete combustion by reduced air supply the fuel is cracked with the aid of supplied vapour, whereby heavy oils are decomposed into lower hydrocarbons, hydrogen and carbon monoxide.
Also in this known combustion method the way of supply is technically demanding, and moreover the danger exists that in certain wall regions the temperature is not sufficient for evaporation of heavier waste oil fractions, which then gather at the bottom of the combustion chamber and form a non-burnable residue there. Water vapour is here not provided for the actual combustion but only for cracking of heavy oils.
In U.S. Pat. No. 4,069,005 the combustion of a water/fuel/air mixture in the presence of a metal catalyst (nickel) is proposed, wherein in the interior of the burner several stacked plates, which may also consist of the metal catalyst, can be disposed, to increase the efficiency of the resulting cracking. In the apparatus serving this purpose liquid fuels and water are respectively dropped upon the catalyst from above, the plates having been heated to a temperature above 800° C. in a preheating phase. The rising vapours are led along the metal catalysts, whereby easily burnable, gaseous hydrocarbons are generated by cracking, which burn in the further process, whereby combustion gases of 800° C. to 1000° C. are generated.
For the generation of a long flame for heating an industrial boiler in U.S. Pat. No. 3,804,579 oil and air are burnt together with water vapour, which is generated in a heat exchange coil by the flame. Here the extended flame burns at about 730° C.
Finally from DE 39 29 759 C2 a facility for burning waste oil products is known, in which the waste oils are mixed with a usual heating oil with a known smaller viscosity, such that an average product with constant viscosity is, formed, which is then preheated and injected into a tank. On the opposite side of the tank input devices for air, water and common neutralizing agents are provided. For injecting the oil mixture air or water vapour is used. The control facility for the mixing ratio of the oils and the injection apparatus for the oil mixture with additional supply leads for air and neutralizing agents lead to a constructively complex facility, which is hard to control, and which cannot work efficiently, because apart from the actual combustion product of waste oil considerable amounts of normal heating oil have, to be burned additionally, which largely limits the disposal capacity. The simple combustion tank cannot support the combustion process.
It is an object of the present invention to provide a method for the environmentally friendly combustion of fuels of an arbitrary state of aggregation, possibly with the addition of water and/or an oxidizing agent, in which the fuel is burnt without residues with a high energy efficiency. The reactor suitable for this is intended to optimize the combustion process in continuous operation with a low constructive effort, and it should be as maintenance-free as possible, and it should be self-cleaning.
According to the invention the solid and/or liquid and/or gaseous fuel, possibly the water and/or an oxidizing agent are introduced into a reaction chamber under high pressure in axial direction by pressurized air, the amount of injected pressurized air corresponding to the amount of air, which is necessary for the complete combustion, the introduced mixture is led to a deflection surface in the interior of the reaction chamber, whereby it is further atomized, liquid components evaporate, solid ones sublimate and the mixture burns explosively, before it can reach the wall of the bottom of the reaction chamber. The explosive combustion process can be explained by the high degree of the surface increase of the mixture introduced into the reaction chamber:
(a) the fuel supplied by pressurized air is disintegrated and atomized, when it is injected into the reaction chamber,
(b) the existing pressure is still sufficient to lead the fuel with high velocity to a deflection surface in the interior of the reaction chamber, where an impingement and a reflection with a further distribution and atomization are caused.
Additional water injected with pressurized air is atomized into droplets, when entering the reaction chamber, the droplets changing into water vapour and being distributed into all directions in the interior space of the reaction chamber by the deflection surface. The expansion caused by the sudden evaporation supports a mixing of the fuels with the present pressurized air and the water vapour, which leads to an efficient combustion, especially of hardly burnable fuel components. This way a precipitation of fuel at the inner wall and a concentration of residues at the bottom can be more efficiently abided, so that the reactor cleans itself.
The pressurized air flow can be injected at 2 to 10 bar, preferably at 3 to 5 bar into the reaction chamber. At these pressures the combination of the atomization at the exit from the supply lead with the one caused by the impact onto the deflection surface in the interior space of the reaction chamber is
Bennett Henry
Cocks Josiah
Gourmeli International N.V.
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