EP1031000B1 - Fuel combustion method and reactor - Google Patents

Abstract

The invention relates to a method for combustion of fuels of arbitrary state of aggregation, which are burnt with air, possibly with the addition of water, and a reactor therefore, which is intended to optimize the combustion method. A solid, liquid and/or gaseous fuel, possibly water and/or an oxidizing agent are introduced into a reaction chamber (2) in its axial direction under high pressure, the amount of injected pressurized air corresponding to the amount of air necessary for the complete combustion, and the introduced mixture is led to a deflection surface (7) in the interior of the reaction chamber (2), whereby it is atomized, sublimates and/or evaporates and burns explosively, before it can reach the wall or the bottom of the reaction chamber (2). The reactor (1) for this combustion method features a hyperboloidal reactor head (3), which is disposed adjacent to the outlet opening of the reaction chamber (2) and the cross-section of which widens from there, whereby the reactor (1) is shaped like a nozzle.

Description

The invention relates to a method for the combustion of Fuels, according to the preamble of claim 1.

A combustion process and a combustion reactor 6 are from the German published application DE 2 118 073 known. There will for the removal of contaminated liquids and sludge proposed two immiscible phases of the to be burned Fuel together via an atomizing device with atmospheric oxygen into a reaction chamber where a pseudo-homogeneous mixture is formed, which gasifies and burns. A recirculation movement should continue in the chamber to homogenize the mixture. Here part of the fuel is supposed to run along the chamber walls and absorb heat from them. With this procedure the fuel is placed in a cylindrical reaction chamber directed in the axial direction. The reaction chamber can a relaxation chamber downstream to cool down of the exhaust gases and for the separation of unburned dust particles serves.

In the case of combustion according to DE 2 118 073, it is essential the inner wall of the reaction chamber at a temperature to keep that of those in the gaseous reaction mass corresponds. This is especially true when starting up the burner Disadvantages, as flame retardant residues on the. Can form the bottom of the reaction chamber. The same applies to non-combustible constituents such as dust, due to the circulation movement in the reaction chamber difficult to get out of Reaction chamber is transported. The geometry of the In addition, the reactor does not allow high flow rates to.

A device and a method for the combustion of Oil with the addition of water are known from WO95 / 23942, where oil is introduced into a combustion chamber until has formed an oil bath, which is then heated to a temperature between 250 ° and 350 ° C is preheated. Then water will come on sprayed the surface of the hot oil bath, resulting in simultaneous Supply of air to the combustion chamber caused a flame eruption results. The level of the oil bath should be during the Combustion should not be less than 3 to 4 mm high to prevent the combustion from stopping. The one about this Purpose device essentially comprises one Combustion chamber in the shape of a truncated pyramid or cone lateral supply openings for oil and water from corresponding Storage containers. The oil bath is heated electrically. Air. reaches the interior of the combustion chamber together with the water. The 1200 ° to 2000 ° C hot flame is used for heating purposes passed into a furnace via a cylinder tube.

In particular in this known combustion process There is a temperature gradient in the oil bath from used oils proved to be disadvantageous towards the ground, since the ground temperatures heavier below the evaporation temperatures Fractions can be in the waste oil, with the result that the latter a not completely burning mass of oil on the floor form the combustion chamber. Injecting the oil turns out to be impractical because of residues and highly viscous components cause clogged nozzles in used oil. Still designed the entire device with its supply lines and preheating devices are structurally complex. The process control is particularly when switching off because of the remaining Residues are difficult to control. For continuous operation the system is therefore not suitable.

GB 765 197 describes a device for burning liquid and liquefiable fuels known from a cylindrical combustion chamber with one attached to it subsequent open fire chamber exists. The liquid Fuel is injected radially or tangentially into the interior of the Combustion chamber introduced, air is supplied separately tangentially, the fuel being the inner surface of the burner chamber touched and evaporated and burned there. The one in the firebox The resulting temperatures are between 1500 ° and 1800 ° C. The fuel is burned through incomplete reduced air supply with the help of supplied steam cracked, causing heavy oils into lower hydrocarbons, Hydrogen and carbon monoxide are broken down.

Also in this known combustion process the type of supply line is technically complex, moreover there is a risk that in certain wall areas the temperature for evaporating heavy waste oil fractions is not is sufficient, which is then at the bottom of the combustion chamber collect and there form a non-burning residue. Water vapor is here for the actual combustion not intended, but only for cracking Heavy oils.

In US 4,069,005 the combustion of a water / fuel / air mixture in the presence of a metal catalyst (Nickel) suggested being inside the burner several plates arranged one above the other are, which can also consist of the metal catalyst to to increase the effectiveness of the cracking caused thereby. In the device used for this purpose, liquid Fuels and water from above on top of each other arranged plates dripped from the metal catalyst, which have been heated to above 800 ° C in a preheating phase are. The rising vapors are on the metal catalysts led along, whereby easily flammable, gaseous Hydrocarbons are generated by cracking, which is further Burn course, causing combustion gases of 800 ° up to 1000 ° C.

To generate a long flame to heat a industrial boilers is US 3,804,579 oil and air together with the flame itself in a heat exchanger coil generated steam burned. The extended flame burns here at approx. 730 ° C.

Finally, from DE 39 29 759 C2 a system for Combustion of waste oil products known in which the waste oils with a known heating oil of lower viscosity are mixed so that an average product with constant viscosity is formed, which is then preheated and is injected into a boiler. On the opposite Side of the boiler are input devices for Air, for water and for common neutralizing agents. Air or water vapor is used to inject the oil mixture used. The control system for the mixing ratio of the Oils and the injection device for the oil mixture with the further supply lines for air and neutralizing agent require a structurally complex, difficult to control system, that cannot work efficiently because in addition to the actual one Incineration product waste oil also considerable amounts normal heating oil must be incinerated, which increases the disposal capacity severely limited. The simple combustion boiler cannot support the combustion process.

The object of the present invention is to provide a method for environmentally friendly combustion of any fuel Physical state, possibly with the addition of water and / or an oxidizing agent, in which the fuel completely and without residues with high energy yield is burned. The reactor suitable for this should be small constructive effort, as maintenance-free as possible and self-cleaning, optimize the combustion process in continuous operation.

(a) der mittels Druckluft zugeführte Brennstoff wird beim Eindüsen in die Reaktionskammer zerrissen und zerstäubt, wobei

(b) der bestehende Druck noch ausreicht, um den Brennstoff mit hoher Geschwindigkeit auf eine Ablenkfläche im Innenraum der Reaktionskammer zu leiten, wo ein Aufprall und eine Reflexion mit weiterer Verteilung und Zerstäubung bewirkt werden.

Zusätzlich mit Druckluft eingedüstes Wasser wird beim Eintritt in die Reakionskammer in Tröpfchen zerstäubt, die sich in Wasserdampf wandeln und von der Ablenkfläche in alle Richtungen im Innenraum der Reaktionskammer verteilt werden. Die durch die schlagartige Verdampfung hervorgerufene Expansion unterstützt eine Vermischung der Brennstoffe mit der vorhandenen Druckluft sowie dem Wasserdampf, was eine effektive Verbrennung, insbesondere schwer brennbarer Brennstoffanteile, zur Folge hat. Damit können noch effektiver ein Absetzen von Brennstoff an der Innenwand sowie eine Ansammlung von Rückständen am Boden verhindert werden, so daß der Reaktor sich selbst reinigt.This object is solved by the features of independent claims 1 and 6. Advantageous refinements result from the respective subclaims. The explosion-like combustion process can be explained by the high degree of surface enlargement of the mixture fed into the reaction chamber:

(a) the fuel supplied by means of compressed air is torn and atomized when it is injected into the reaction chamber, whereby

(b) the existing pressure is still sufficient to direct the fuel at high speed onto a deflection surface in the interior of the reaction chamber, where an impact and reflection with further distribution and atomization are brought about.

In addition, water injected with compressed air is atomized into droplets as they enter the reaction chamber, which converts to water vapor and is distributed in all directions in the interior of the reaction chamber from the deflection surface. The expansion caused by the sudden evaporation supports a mixing of the fuels with the existing compressed air and the water vapor, which results in an effective combustion, in particular of difficultly combustible fuel components. This more effectively prevents fuel from settling on the inner wall and accumulation of residues on the bottom, so that the reactor cleans itself.

The compressed air flow can be 2 to 10 bar, preferably with 3 to 5 bar, are injected into the reaction chamber. At these pressures is the combination of atomization on exit from the supply line with that caused by the impact particularly on the deflection surface in the interior of the reaction chamber effective.

The fuels, the water and / or the oxidizing agent are separated or as a mixture over a or several venturi tubes are introduced into the compressed air flow. More gaseous Fuel can enter the reaction chamber on its own be directed. This type of feeding allows a good dosing option with little constructive Effort and at the same time increases the atomizing effect when Entry into the reaction chamber. The injection into the reaction chamber takes place through a normal tube of small diameter without nozzle attachment, which clogs the nozzle when Burning used oils due to non-combustible residues or viscous components is prevented. The use of uniform Venturi tubes for the fuel supply and the water also reduces the design effort.

The temperature inside the reaction chamber is advantageous by means of thermally conductive reactor walls Keep axis of the reaction chamber. If through the baffle a symmetrical distribution of the mixture inside the reaction chamber takes place with symmetrical temperature distribution smoother combustion can be achieved.

With a given geometry of the reaction chamber can the inflow speeds of the mixture to be burned be set in the reaction chamber such that the resulting combustion flame at least at the speed of sound leaves the reaction chamber and the resulting thermal energy transported to the outside for further use. This can be done - as described below - by suitable geometry of the reactor further improve.

The ignition of the mixture in the reaction chamber will suitably with a pilot flame or by means of a generated Spark made. It can offer fuels, Water or air before introduction into the reaction chamber by preheating the waste heat generated during combustion. Heavy oil in particular is caused by this Reduced viscosity easier to transport. Through inserts that can be inserted into the interior of the reaction chamber the flow dynamics of the combustion process influence.

It is beneficial to burn the fuel additionally catalytically cracked, the catalyst being e.g. a nickel-containing material can be used.

The reactor according to the invention has a deflection surface and a hyperboloid-like one Reactor head on, which is located at the outlet opening of the reaction chamber connects and from there in cross section expanded. The combustion flame burns at this reactor head. The nozzle-like geometry of the reactor leads to an acceleration of the fuel gases with the formation of a corresponding one Negative pressure in the mouth area of the reaction chamber, what a further acceleration of the burned Substances inside the reaction chamber towards the outlet opening has a positive impact on combustion as well as the self-cleaning of the reactor.

The nozzle effect can be improved in that the reaction chamber at least in its upper part in the direction the outlet opening tapers, the tapering Part especially designed as a truncated pyramid or cone can be. On the other hand, the entire reaction chamber be hyperboloid-shaped, such that it faces towards the outlet opening tapers.

With the nozzle-shaped reactor geometry, it is advantageous the supply openings for the fuels (and water) in the bottom of the reaction chamber so that this are directed parallel to the axis of the reaction chamber. Hereby the axis of the reaction chamber becomes the preferred flow direction determined in the then for better distribution of the mixture to be burned arranged the deflecting surface is through which the mixture initially from the axis of the Reaction chamber is diverted to due again subsequently said nozzle effect of the reactor on this axis to become. In addition, due to the pressure conditions the outflow from the feed openings favors.

The deflection surface can be used to achieve a homogeneous distribution one with the tip against the flow direction of the Fuel-oriented cone or one arranged in the same way Pyramid made of a refractory material, the one or the inside the reaction chamber is arranged along its axis, be used. The combustion process can thus symmetrical distribution in the cross section of the reaction chamber physical quantities such as pressure, flow velocity, Turbulence and temperature can be optimized.

If the fuel is to be additionally cracked, offers itself, a metal catalyst, in particular containing nickel, for example in the inner walls of the reaction chamber, in refractory inserts inside the reaction chamber or also to be provided in the deflection surface. A high efficiency of the Catalytic cracking can be done by a scaly or achieve porous metal catalyst with a large surface area.

The reactor can be made of one material like Be made of stainless steel, but also at least partially a particularly heat-resistant and mechanically resilient Alloy such as a Ni-Mo-Cr-Co alloy ("Nimonic"). Farther The reactor can be made of ceramic fiber outer insulation or be surrounded by fiberglass to the emitted Reduce the amount of heat and the temperature in the reactor chamber to keep above about 1000 ° C.

Figur 1

zeigt einen erfindungsgemäßen Reaktor in Seitenansicht von schräg unten,

Figur 2

zeigt den Reaktor in Durchsicht von schräg oben, und

Figur 3

zeigt den Reaktor in Durchsicht von der Seite.

Based on the figures, the invention will be explained in more detail in an embodiment in the following.

Figure 1

shows a reactor according to the invention in a side view from obliquely below,

Figure 2

shows the reactor in an oblique view from above, and

Figure 3

shows the reactor viewed from the side.

The figures show the reactor 1 according to the invention a reaction chamber 2, at the outlet opening 4 of which Reactor head 3 connects. Feed lines 5 and 6 are in coaxial direction in the center of the bottom of the reactor 1. In this example, the deflection surface is one with the Cone pointing towards supply lines 5 and 6 7 attached inside the reaction chamber 2 along the axis.

The upper part of the reaction chamber 2 tapers in this embodiment hyperboloid-like in the direction of Outlet opening 4, from there hyperboloid-like in the reactor head 3 to continue. This geometry creates a nozzle effect, through the flowing gases due to the negative pressure in the area of the outlet opening and the reactor head from the inside the reaction chamber 2 are sucked, which additionally the supply pressure in the supply lines 5 and 6 is reduced can be. At the same time, this makes self-cleaning of the reactor, since non-combustible particles and Residues drawn from the inside of the reactor by the suction effect become. Such residues can be filtered separate the combustion gases.

In this embodiment, the reactor has one Volume of about 15 liters and is made of stainless steel. Partial production from a more temperature-resistant is advantageous and mechanically stronger material like a Nimonic alloy with the following composition: C = 0.057; Si = 0.18; Mn = 0.36; S = 0.002; Al = 0.47; Co = 19.3; Cr = 19.7; Cu = 0.03; Fe = 0.55; Mo = 5.74; Ti = 2.1; Ti + Al = 2.59 (in% by weight); ppm fractions of Ag, B, Bi and Pb; Rest of nickel. The elements contained therein bring about at the same time catalytic cracking of hydrocarbons. The reactor can be made of this material with wall thicknesses of 3 to 4 mm, this is 5 for stainless steel up to 7 mm. External insulation of the reactor 1 is advantageous made of a material consisting of ceramic fibers or fiberglass, that reduces heat radiation and thus the temperature increased inside the reactor.

Through the supply lines 5, the Venturi tubes with 3 to 7 mm in diameter becomes more fluid Fuel, namely waste oils and heavy oils of various types Composition, as well as solid fuel, such as in particular dried olive bagasse and sewage sludge, from compressed air from corresponding (not shown) storage containers sucked and with pressures of 3 to 5 bar inside the reaction chamber 2 transported. When leaving the Supply lines 5 tear the fuel flow, the fuel hits the deflection surface at high speed 7, from which the fuel is symmetrical in cross section is distributed to the reaction chamber. Through a supply line 5 atomized water atomizes and evaporates as it exits the reaction chamber 2, the water vapor is also symmetrical distributed in the reaction chamber 2. Via the supply line 6, in which the feed lines 5 are arranged if necessary, more compressed air can be fed in to the to provide the necessary amount of air for complete combustion.

About 30 to 40 l / h of water and 70 to 80 l / h of waste oil are introduced into the reaction chamber 2. Solid fuels such as dried biomass are fed at 110 to 130 l / h. If liquid and solid fuels are to be introduced together, the supply quantities must be reduced accordingly. The burner output is just under 1 MW _t . The pollutant emissions turn out to be slight to negligible.

The combustion process is regulated under Measurement of temperature, quantity and chemical composition the combustion gases. Accordingly, the supplied water, air and fuel quantities controlled.

The structure of the reactor shown results in a symmetrical one Distribution of the physical quantities of the combustion process, rotationally symmetrical in relation to axis points the reaction chamber 2. In a cross section of the reaction chamber 2 are the values of temperature, pressure, flow rate the gases are almost constant. The temperatures take from the bottom of the reaction chamber 2 to the outlet opening 4 towards, due to the heat-conducting reactor walls in A continuous flattening of the temperature gradient takes place.

The flow dynamics of the combustion process is at Change of the reactor geometry as well as the position and geometry the deflection surface adjustable.

The fuels are completely burned in the reactor. Any non-combustible residues are caused by the suction effect transported from the inside of the reactor and can by means of Filters are collected. The nozzle effect of the reactor 1 can be coordinated together with the feed speed in such a way that the combustion gases at the speed of sound the reactor head at a temperature of approx. 1,200 to approx. 1,500 ° C 3 leave.

Various industrial applications of the reactor and combustion process according to the invention. For example, with the hot combustion gases Liquid bed are operated in which sand is flowed through by hot gas becomes. Such liquid beds are mostly used for cleaning of objects (e.g. paint residues). There is also one for hazardous waste disposal Use. Biomass can be caused by a targeted lack of air on the Fluid bed undergo a pyrolysis process, whereby solid and gaseous fuels directly to the invention Processes can be obtained. The fuel gases generated can also be used directly in an internal combustion engine be used to generate electricity. Finally can the combustion method according to the invention for combined Generation of heat and electricity, i.e. used to operate both steam and gas turbines become.

The invention enables environmentally friendly combustion of waste products that are difficult to dispose of, such as waste oils of various types Composition, sewage sludge, olive bagasse, mineral coal and other combustible waste products.

Claims (12)

1. Method for the combustion of fuels, in which the fuels are introduced into a reaction chamber (2) in its axial direction by means of pressurized air and burnt, possibly with the addition of water,
      characterized in that

   (a) a solid and/or liquid and/or gaseous fuel are used, possibly with the addition of an oxidizing agent,

   (b) the amount of injected pressurized air corresponds to the amount of air required for the complete combustion, and

   (c) the introduced mixture is led to a deflection surface in the interior of the reaction chamber (2), whereby it is distributed, liquid and/or solid components are further atomized, liquid components evaporate, solid ones sublimate and the mixture burns explosively, before it car. reach the wall or the bottom of the reaction chamber (2).
2. Method of claim 1, characterized in that the pressurized air flow or the pressurized air flows are injected into the reaction chamber (2) at a pressure of about 2 to 10 bar, preferably at 3 to 5 bar.
3. Method of one of claims 1 or 2, characterized in that the inflow velocities into the reaction chamber (2) are adjusted so that the combustion flame leaves the reaction chamber (2) at least with the velocity of sound at a predetermined geometry of the reaction chamber.
4. Method of one of claims 1 to 3, characterized in that the interior space of the reaction chamber (2) is formed fluid dynamically by inserts introduceable into the reaction chamber.
5. Method of one of claims 1 to 4, characterized in that the hydrocarbons containing fluid is catalytically cracked in the combustion.
6. Reactor for a combustion method, in which fuels are burnt together with air, possibly with the addition of water and/or an oxidizing agent, said reactor having a reaction chamber with supply openings for the'fuel, the air, the oxidizing agent and/or the water and with an outlet opening for the combustion products, characterized in that the reactor (1) has a hyperboloidal reactor head (3), which is disposed adjacent to the outlet opening (4) of the reaction chamber (2) and the cross-section of which widens from there, and that a deflection surface (7) is disposed in the interior of the reaction chamber (2) in the influx direction given by the supply openings.
7. Reactor of claim 6, characterized in that the reaction chamber (2) tapers at least at the upper part in the direction of the outlet opening (4).
8. Reactor of claim 7, characterized in that the tapered part of the reaction chamber (2) is formed as a frustrum of a pyramid or a cone.
9. Reactor of claim 7, characterized in that the reaction chamber (2) is formed hyperboloidally.
10. Reactor of one of claims 6 to 9, characterized in that the openings of the supply leads (5, 6) are embedded in the bottom of the reaction chamber (2) and are directed parallel to the axis of the reaction chamber (2).
11. Reactor of one of claims 6 to 10, characterized in that the deflection surface (7) is formed by a cone or pyramid, the tip of which points in the direction of the supply openings.
12. Reactor of one of claims 6 to 11, characterized in that a metal catalyst is provided in the interior of the reaction chamber (2), for example in the reaction chamber walls, in fire-resistant inserts in the interior of the reaction chamber (2) or in the deflection surface (7).

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