Process and apparatus for combustion of waste, such as household and other waste, and afterburning of residues from the combustion

This invention describes a process and apparatus for the combustion of wastes, wherein the wastes are combusted in a combustion chamber and the temperature of the combustion chamber is controlled by changing the amount of combustion air as a function of the slag flow rate. The combustion can be carried out substoichiometrically in a reducing atmosphere because of additives which are introduced into the slag in the form of fine dusts. On account of the substoichiometric operation, the requirement for fluid wastes and/or supplemental fuel is drastically reduced, the capacity of the rotary tubular kiln is increased and nitrogen oxides formation is reduced.

REFERENCE TO RELATED APPLICATION 
This application is related to International Application PCT/DE90/00005 
filed on Jan. 3, 1990 designating the U.S. which claims priority from 
Federal Republic of Germany Patent Application No. P 39 00 285.3 filed on 
Jan. 5, 1989, and No. P 39 31 280.1 filed on Sept. 20, 1989. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a process and apparatus for the combustion of 
special wastes and the vitrification of fine dusts in a rotary tubular 
kiln. Combustion installations with rotary tubular kilns are primarily 
designed and constructed to burn solid, pasty, sludgy and viscous special 
wastes, i.e. extremely heterogeneous mixtures of waste materials which can 
be delivered continuously, but which are delivered primarily in batches, 
and frequently only in containers. Combustion of such wastes in 
conventional household waste combustion installations would be 
problematic, and therefor special combustion facilities are needed. 
2. Background Information 
German Laid Open Patent Appln. No. 28 08 637 discloses the combustion of 
special waste substances in installations with rotary tubular kilns in 
which the rotary tubular kiln empties directly into an afterburner. The 
molten slag produced in the rotary tubular kiln is transported to a wet 
slag removal device positioned at the end of the rotary tubular kiln, 
underneath the afterburner chamber. 
From the afterburner chamber or from the kiln charging side, a lance can be 
used to blow fine dust in an air current into the molten slag bath of the 
rotary tubular kiln. This bonds the fine dusts containing heavy metals 
into the slag during the burning of the waste. An alternative proposal is 
that the fine dusts be pelletized by means of water and binders, and then 
transported in containers to the rotary tubular kiln, as is done with the 
waste substances. An auxiliary burner which is operated with waste oil can 
be used to assist the combustion process in the rotary tubular kiln or in 
a molten slag bath inside the afterburner chamber. 
This method, however, has several disadvantages. First, the combustion can 
be conducted only superstoichiometrically, and second, to the extent that 
fine dusts are introduced by an air current, a great deal of polluted air 
is forced through the installation, and the thermal conditions in the 
rotary tubular kiln allow only a very limited integration of the dusts 
into the slag. 
On account of the various waste materials, solid, pasty, sludgy and 
viscous, of which the composition and combustion behavior vary greatly, 
extremely heterogeneous waste gases are generated in the rotary tubular 
kiln, both with regard to the gas composition and the gas combustion 
temperature. 
The requirements for such rotary tubular kilns are: 
1. absolute burning of the remaining solid residues which is possible in 
practice only with molten slags; and 
2. the greatest possible burning of the waste gases, so that, in an 
afterburner chamber located behind the rotary tubular kiln, the burning 
limits for the allowable air pollution standards can be met. 
In the past, the simultaneous fulfillment of these two requirements has 
been possible only by using large amounts of fluid waste which has a high 
caloric value and which also can be sprayed into the furnace via burners. 
The proportion of these wastes which can be atomized, however, should be 
kept as low as possible for economic reasons, since such wastes can be 
processed more economically or can be disposed of in installations with 
combustion chambers. Frequently, the ratio of liquid to solid waste is out 
of balance, so that without additional fuels such as heating oil or 
natural gas, it is impossible to simultaneously meet both these 
requirements. 
In practice, the combustion air that is not delivered by means of burners, 
is generally kept constant. Many attempts have been made to control the 
combustion air as a function of the oxygen requirement for optimal 
combustion, but none have ever fulfilled expectations. In batch operation, 
and in particular for container operation, the energy content and the 
combustion behavior of the wastes cannot be sufficiently estimated because 
the parameters; energy content, proportion of inorganic material and 
water, pellet size, melting behavior, degasification, reaction surface, 
flammability and other characteristics, can seldom be adequately 
determined in advance. 
Moreover, the current proportion of solid matter, and thus the amount of 
material actually contained in a batch, may vary on account of the 
changing composition. 
Batch operation of a combustion facility produces peak loads, and the 
amount of oxygen in the combustion air must be set accordingly. 
To achieve a sufficient burning of the waste gas in the rotary tubular kiln 
even with the above-mentioned peak loads, the following minimum combustion 
air excesses have proven effective in practice: 
greater than 1.35 for liquid waste with delivery via burners; 
greater than 2.00 for continuously delivered, sludgy and pasty wastes; 
greater than 3.00 for waste delivered in batches as bulk material; and 
greater than 3.00 for waste delivered in batches in containers. 
The average combustion air excess is generally set at a value in the 
neighborhood at 2.5, to meet all the requirements. 
Operation with viscous slags is possible at waste gas temperatures between 
1050 and 1300 degrees C, with a tendency to 1300 degrees C, as a function 
of the composition of the inorganic waste components and possible 
additives. An optimal burning of the solid residues is possible only with 
molten slags. 
For a theoretically average combustion air excess of 2.75, in relation to 
solid and semi-solid waste, it can be calculated that with a waste gas 
temperature of 1250 degrees C, only approximately 22% of the energy 
resulting from the waste, in relation to the lower combustion value Hu, 
can come from solid, sludgy and pasty waste, with the remainder having to 
come from liquid waste or supplementary fuel. This is not economical. 
As a result of the extremely heterogeneous waste material and the high 
combustion air excesses, heterogeneous waste gases are formed and a 
correspondingly poor burning of the waste gas is achieved in the rotary 
tubular kiln. 
In general, these rotary tubular kiln waste gases are transported directly 
into an afterburner chamber, where, if necessary, the temperature is then 
raised by the addition of liquid or gaseous fuels, and a remaining 
oxidation of the waste gases is conducted at low waste gas velocity and 
during a long hold time. This process and the construction of such 
furnaces with afterburners directly connected to the kilns, do not allow 
an intensive mixing of the waste gases. Because a good mixture of the 
waste gases is not achieved in the afterburner chamber and thus only a 
limited burning of the waste gases is occurring, the waste gases must be 
burned as much as possible in the rotary tubular kiln before they get to 
the afterburner. In relation to the above-mentioned conditions, such as 
combustion air excess, waste gas temperature, ratio of solid and liquid 
wastes, and with a typical diameter to length ratio of the rotary tubular 
kiln of 1:3.2, for example, approximately 100,000 to 150,000 Kcal/m.sup.3 
h (approximately 420,000 to 640,000 kJ/m.sup.3 h) can be processed. 
This value is a function of: 
a) the amount of waste gas, the waste gas temperature and the resulting 
velocity of the waste gas, 
b) the hold time in the rotary tubular kiln, determined by the kiln 
inclination, the speed of rotation, angle of repose of the waste material, 
the melting behavior of the waste and the slag and the viscosity of the 
liquid slag, 
c) the reaction surface area, determined for example by the grain size of 
the waste, the density of the waste, the content of inorganic material, 
the waste melting behavior and the charging of the individual kiln zones, 
i.e. the drying, degasification, combustion and afterburning zones, 
d) and additional control variables, e.g. the number and size of the 
containers and waste charges delivered, the proportion of skin-forming 
substances in the slag, the concentration of salts and salt forming 
substances in the waste, and the possibility of adding the waste to the 
kiln in a uniformly-dosed manner. 
In the installations of the prior art, the control of the molten slag flow 
and thus the vitrification of the slag is even more difficult than 
controlling the amount of the combustion air oxygen. 
On account of the extremely high combustion air excesses in the rotary 
tubular kiln, a great deal of polluted air is forced through the system 
and needs to be heated. The efficiency of the furnace is thereby 
drastically reduced. With primarily solid waste material with a low 
caloric value, therefore, a great deal of heating oil or natural gas must 
be added to maintain the required minimum temperatures. 
OBJECT OF THE INVENTION 
Therefore, the object of the invention is to propose a process and 
apparatus for the combustion of special waste and the vitrification of 
fine dusts, in which simultaneously the efficiency of the furnace is 
increased and the afterburning of the waste gases is optimized. 
SUMMARY OF THE INVENTION 
The object is achieved according to the invention by the addition of a 
turbulence zone between the rotary kiln and the afterburner. This 
turbulence zone allows for more efficient mixing of the waste gases and 
therefor, more efficient burning of the waste gases after they leave the 
rotary kiln. Since the waste gases in this invention are more efficiently 
burned after they leave the kiln, the kiln combustion chamber no longer 
needs extremely high combustion air excesses and thus, greater efficiency 
is achieved because a smaller volume of air needs to be heated. Therefor, 
since excess heat is not needed for heating the air, the temperature in 
the combustion chamber can be controlled for the most economical burning 
of the solid waste as determined by the flow of waste slag from the kiln. 
By means of the process control according to the invention, fine dusts are 
introduced directly into the molten slag in the rotary tubular kiln from 
the discharge side of the kiln, and thus, are added separately from the 
waste. In the prior art, these fine dusts had to be expensively stored in 
special dumps, while according to the present invention they can be melted 
with the rotary tubular kiln slag and become practically insoluble in 
water, thus producing a valuable filler material instead of waste. 
The rotary tubular kiln is operated by means of a controlled dosing of 
combustion air to guarantee that the inorganic waste components, together 
with additives and also with the additional fine dusts, are obtained as a 
viscous, vitrified mass. To optimize the slag melting process, suitable 
inorganic additives can be mixed in directly with the material to be 
incinerated and the fine dusts to be melted. By means of the melting, the 
absolute burning of the slag is guaranteed, and the vitrification and the 
accompanying integration of pollutants, such as heavy metals, into the 
glass matrix minimizes the solubility in water as far as possible. Fine 
dusts, in addition to the abovementioned inorganic additives, are bonded 
by additional suitable organic additives, e.g. waste substances such as 
waste oil, tar, oil sludge and other materials to be disposed of 
containing hydrocarbons. These bonded fine dusts are introduced from the 
transition housing directly into the rotary tubular kiln slag. 
As a result of preparing the fine dusts with inorganic and organic 
additives, the fine dusts melt all at once, and bond any volatile heavy 
metals into the silicate matrix of the molten products. The preparation of 
the dusts with inorganic and organic additives and the simultaneous spot 
addition of combustion air prevents the "freezing" of the slag when cold 
dusts are added. 
The kiln rotation also causes a rapid mixing and binding of the fine dusts 
into the glassy slag. Since the integration of the fine dusts takes place 
at the furnace discharge, the hold time of the slag with the bound dust, 
at the high temperatures of the kiln, is short. The vaporization of heavy 
metals is also thereby minimized. 
When operation is conducted with the melt as the regulating variable, as 
per the present invention, the combustion of wastes with a low caloric 
value takes place slightly superstoichiometrically, and the combustion of 
wastes with a high caloric value takes place substoichiometrically, with 
the substoichiometric operation being preferred. 
Depending on the composition of the solid, sludgy and pasty wastes, the 
inflammability and quantities of these wastes added, and the size of the 
kiln and similar control parameters, only approximately 1.5 to 3 (Gcal/h) 
Gigacalories per hour (approx. 6.0 to 12.5 (GJ/h) Gigajoules per hour) of 
atomizable liquid wastes or appropriate supplementary fuels need to be 
added via burners for additional combustion energy. 
Also, with substoichiometric combustion, smaller quantities of nitrogen 
oxides are produced during the combustion of the wastes. 
By means of the process according to the invention, the combustion air 
excess can be drastically reduced, so that there is significantly less 
pollution. This has the decisive advantage that, with the same apparatus, 
higher waste throughputs can be achieved, or, with the same throughput, 
smaller facilities can be constructed. 
It is also advantageous that the proportion of the liquid fuels which must 
be added or burned in simple combustion chambers is drastically reduced. 
For waste gas temperatures greater than 1200 degrees C, special waste 
combustion installations of conventional construction require the 
following conditions, in relation to the energy content (the product of 
quantity times minimum caloric value) of the waste being provided: 
22 to 30% solid and pasty wastes to 
78 to 70% liquid waste atomized via burners. 
According to the present invention, the following significantly better 
values can be attained: 
60 to 70% solid and paste wastes to 
40 to 30% liquid waste atomized via burners. 
The burning of the waste gases from the rotary tubular kiln takes place in 
a rotary tubular kiln transition housing and a downstream afterburner 
chamber. Both the transition housing and the afterburner have one or more 
portions with narrow cross sectional areas for generating extremely high 
turbulence to produce optimal mixing of the waste gases. In the transition 
housing, activated combustion air, which has been activated and preheated 
to approximately 700 degrees C, can be blown in to intersect the kiln 
waste gas current and thus further optimize the mixing action. Thus, an 
optimal oxidation of the waste gases can be achieved even in the first 
turbulence zone. 
With the pre-firing of wastes with low caloric values, it is recommended 
that oxygen instead of air be blown into the transition housing to 
guarantee that the required minimum oxygen content is present in the 
chimney exhaust air. 
This forced mixing is more effective than the establishment of low waste 
gas velocities and higher temperatures, as is done in the prior art, since 
without the mixing a meeting of oxygen and the components to be oxidized, 
and thus the burning, is not possible. 
Finally, according to the invention it is possible to further optimize the 
burning of the rotary tubular kiln waste gases in a round afterburner 
chamber, which burns additional waste via tangentially located burners. 
The arrangement, according to the invention, of the rotary tubular kiln, 
the transition housing and the afterburner chamber, makes it possible to 
accelerate the waste gas stream in an area having a narrow cross section, 
and to introduce activated combustion air perpendicular to it. The 
transition housing therefore acts like a turbulence zone, and is effective 
up to the afterburner chamber for the burning of the waste gas. This type 
of construction has the advantage that it does not require optimization of 
the burning of the waste gas in the rotary tubular kiln itself, thereby 
allowing the combustion chamber temperature to be regulated as a function 
of the desired slag melt flow. 
The orientation of the rotary tubular kiln on a different longitudinal axis 
from that of the afterburner chamber makes it possible to introduce a 
molten slag burner into the discharge of the rotary tubular kiln through 
an opening in the transition housing. This slag burner operates with 
pre-heated combustion air, and thus there is an additional capability of 
controlling the molten slag flow, primarily with changing melt behavior, 
without influencing the combustion process in the rotary tubular kiln. 
To increase the burning of the waste gas, the afterburner can also have 
additional sections with narrowed cross sectional areas, which improve the 
mixing effect between the waste gas and introduced air, or between the 
waste gas and other additional substances to be burned. A tangential 
introduction of the waste gases into the afterburner chamber can also 
improve the mixing. The first turbulence zone and burner array in the 
afterburner chamber of the present invention is significantly lower, in 
terms of the height of the installation, than the last burner level in 
conventional special waste incinerator installations. As a result of this 
height difference, the combustion installations according to the invention 
are not much more expensive than conventional combustion installations, in 
spite of the additional transition housing. 
Along with the molten slag burner and combustion air inlet, monitoring 
devices for measuring the combustion chamber temperature, the oxygen 
content of the waste gases, the slag viscosity and flow rate, the slag 
volume and transition housing temperature may also be mounted at the 
discharge end of the kiln in the transition housing. These monitoring 
devices may be remotely monitored at a remote monitoring and control 
station positioned a safe distance from the kiln and burning chambers. 
Such a monitoring and control station may be manually operated or 
programmably computer controlled. By monitoring the slag flow, an operator 
or the computer control can determine if the kiln is operating efficiently 
and make adjustments as necessary. Upon receipt of a signal that the slag 
flow is low, the controller can send a signal to the air pump or valving 
to increase the combustion air being let into the combustion chamber, 
thereby increasing combustion of the waste. Likewise, upon receipt of a 
signal that the slag flow is too fast, the controller can send a signal to 
the air pump or valving to decrease the combustion air being let into the 
combustion chamber, thereby decreasing the rate of combustion of the 
waste. 
Monitoring devices for temperature and gas content may also be positioned 
in or near the afterburner chamber for control of the burning of the waste 
gases and for monitoring the exhaust gas being emitted from the 
afterburner to insure that it meets environmental standards. Such 
monitoring devices may also be manually or computer controllable from the 
monitoring and control station. 
One aspect of the invention is a process for the combustion of waste in a 
combustion apparatus, the process comprising the steps of, conducting the 
waste to the combustion apparatus, the combustion apparatus having a 
loading end, a discharge end, and a combustion chamber between said 
loading end and said discharge end, loading the waste into the loading end 
of the combustion apparatus, combusting the waste in the combustion 
chamber at a combustion chamber temperature at which at least a portion of 
the waste forms a molten slag, flowing the molten slag from the combustion 
chamber of the combustion apparatus, out the discharge end of the 
combustion apparatus and into a molten slag cooling area, monitoring the 
flowing of the molten slag, and adjusting the combustion chamber 
temperature relative to the flowing of the molten slag.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 is a cross section of a rotary tubular kiln 1 and an afterburner 
chamber 3 on a different longitudinal axis. The kiln 1 and the afterburner 
chamber 3 are connected to one another by a transition housing 2 and a 
transition passage 2a with a narrower cross section than the transition 
housing. The rotary tubular kiln waste gases travel through the housing 2 
to the narrowed chamber section 2a. There, the waste gases are accelerated 
by the injection of activated combustion air through the opening 4 and 
turbulence is produced, so that they are thoroughly mixed together in the 
narrowed cross section of passage 2a and are burned in the afterburner 
chamber. A burner can also be installed in the inlet opening 4. Additional 
burners and combustion air inlets can be located in the tangential inlet 
openings 5 of the afterburner chamber 3. An additional opening 6 has a 
double function. First, the fine dust delivery apparatus and an additional 
burner can be installed in the opening 6 of the rotary tubular kiln 1 and 
second, if necessary, an air intake for additional combustion air can be 
installed in this opening 6. Below the transition housing 2 is a wet slag 
removal device 7 of conventional design, to receive and cool the rotary 
tubular kiln slag. 
FIGS. 2 and 3 illustrate an alternative construction of an afterburner 
chamber. 
In FIG. 2, the waste gases from a rotary tubular kiln (not shown), are 
conducted through a transition housing 12 into the afterburner chamber 13. 
Tangentially located input devices 15 make it possible to introduce 
additional fuel (heating oil, natural gas) and/or additional liquid wastes 
into the afterburner chamber 13. 
FIG. 3 shows a cross section through the afterburner chamber 13 along Line 
III--III in FIG. 2. Waste gases emerging from the mouth 11 of the 
transition housing 12 are subjected to afterburning in the chamber 13 with 
the addition of additional fuels, if necessary, through the input device 
15 and combustion air through the ring main 9 and nozzles (not shown) 
which empty into the afterburner chamber 13. An additional narrowed cross 
section 14, i.e. a second turbulence zone, with a transition to the waste 
gas ducts 10 and/or 16, guarantees that an additional intensive mixing 
takes place, and that coarse flyash and molten ash are deposited in the 
container 8. 
FIG. 4 is a cross section of a further embodiment of the combustion 
installation of FIG. 1. FIG. 4 shows a cross section of the rotary tubular 
kiln 1 connected to the afterburner chamber 3 by the transition housing 2 
and transition passage 2a. Additionally, a series of monitoring devices 
17, 17a are present preferably at the discharge end of the rotary tubular 
kiln 1 preferably inside the transition housing 2. These monitoring 
devices 17, 17a are for monitoring at least one temperature in the 
combustion chamber, air oxygen content and the slag volume, viscosity and 
flow rate as the slag flows out of the kiln 1 into the slag bath 7 below. 
The monitoring devices 17, 17a, in one embodiment, can be remotely 
monitored by an operator at monitoring and control station 18 which 
receives signals from monitoring devices 17, 17a by means of electrical 
cable 20. From the station 18, an operator can adjust the input of 
combustion air flowing into the kiln 1 by transmitting a signal along 
electrical cable 21 to air pump or valving 22 to increase or decrease the 
flow of combustion air through nozzle 19. In a second embodiment, a 
programmable computer can be installed at monitoring and control station 
18 for receiving signals and appropriately responding to them. 
Along with the opening 6 which may contain a molten slag burner, a 
combustion air inlet or a dust inlet monitoring devices 17, 17a for 
measuring the combustion chamber temperature, the oxygen content of the 
waste gases, the slag viscosity and flow rate, the slag volume and 
transition housing temperature may also be mounted at the discharge end of 
the kiln 1 in or near the transition housing 2. These monitoring devices 
17, 17a may be remotely monitored at a remote monitoring and control 
station 18 positioned a safe distance from the kiln 1 and burning chambers 
2, 3. Such a monitoring and control station 18 may be manually operated or 
programmably computer controlled. By monitoring the slag flow, an operator 
or the computer control can determine if the kiln 1 is operating 
efficiently and make adjustments as necessary. Upon receipt of a signal 
that the slag flow is low, the controller can send a signal to the air 
pump or valving 22 to increase the combustion air being let into the 
combustion chamber of the kiln 1, thereby increasing combustion of the 
waste. Likewise, upon receipt of a signal that the slag flow is too fast, 
the controller can send a signal to the air pump or valving 22 to decrease 
the combustion air being let into the combustion chamber of the kiln 1, 
thereby decreasing the rate of combustion of the waste. 
Monitoring devices for temperature and gas content 17b may also be 
positioned in or near the afterburner chamber 3 for control of the burning 
of the waste gases and for monitoring the exhaust gas being emitted from 
the afterburner 3 to insure that it meets environmental standards. Such 
monitoring devices 17b may also be manually or computer controllable from 
the monitoring and control station 18. Upon receipt of signals at control 
station 18, the controller can send appropriate signals along cable 25 to 
the burner apparatus 23 and air injection devices 24 positioned in 
openings 5 to control the burner apparatus 23 and air injection devices 24 
to adjust the burning of the waste gases as needed. All of the openings 25 
are preferrably connected to burner apparatus 23 and/or air injection 
devices 24. 
The temperatures needed for the combustion of the waste gases may, for 
example, be in the range of 900.degree. C. to 1500.degree. C. or 
alternately of 925, 950, 975, 1000, 1025, 1050, 1075, 1100, 1125, 1150, 
1175, 1200, 1225, 1250, 1275, 1300, 1325, 1350, 1375, 1400, 1425, 1450 or 
1475.degree. C. or any range defined by any two or even one of these 
temperatures. 
The combustion temperatures, and possibly other temperatures, may be the 
same as the temperatures and temperature ranges indicated in the 
immediately above paragraph or they may possibly be above or below those 
temperatures and temperature ranges, if required, for ordinary and special 
operating conditions of the process and apparatus of the present 
embodiment of the invention. 
A monitoring device for monitoring the temperature may be of the type 
specified in U.S. Pat. Nos. 4,821,219 entitled "Method for Contactless 
Measuring of Temperature with a Multi-channel Pyrometer," 4,533,243 
entitled "Light Guide for Transmitting Thermal Radiation from Melt to 
Pyrometer and Method of Measuring Temperature of Molten Metal in 
Metallurgical Vessel with the Aid of said Light Guide" and 4,235,107 
entitled "Method and Arrangement for Measuring the Physical Temperature of 
an Object by Means of Microwaves." 
A monitoring device for monitoring the viscosity and level of slag in a 
container may be of the type specified in U.S. Pat. No. 4,934,561 entitled 
"Container Discharge Apparatus and Method Employing Microwaves", or may be 
of the type which monitors only the slag viscosity as specified in U.S. 
Pat. No. 4,723,442 entitled "High-Temperature, High-Shear Capillary 
Viscometer". 
A monitoring device for the slag flow rate may be of the type specified in 
U.S. Pat. Nos. 4,608,568 entitled "Speed Detecting Device Employing a 
Doppler Radar", 4,184,156 entitled "Doppler Radar Device for Measuring 
Speed of Moving Objects" and 3,896,435 entitled "Simple Radar for 
Detecting the Presence, Range and Speed of Targets". 
A monitoring device for the gas oxygen content may be of the type specified 
in U.S. Pat. Nos. 4,606,807 entitled "Probe for measuring the Carbon 
Potential of Endothermic Gas", 4,351,182 entitled "Oxygen Sensor for 
monitoring exhaust Gases", and 4,162,889 entitled "Method and Apparatus 
for Control of Efficiency of Combustion in a Furnace". 
The types of waste which may be burned in an installation as per the 
invention may be of the types specified in U.S. Pat. Nos. 4,934,931 
entitled "Cyclonic Combustion Device with Sorbent Injection," 4,925,389 
entitled "Method and Apparatus for Treating Waste Containing Organic 
Contaminants," 4,640,203 entitled "Method and Apparatus for Burning 
Combustible Waste Materials". 
The advantages of the invention lie in the ability to optimally vitrify 
slag and fine dusts, to optimally burn waste gases from the combustion 
installation, to minimize the formation of nitrogen oxides in the waste 
gas, to increase the throughput capacity of the rotary tubular kiln, and 
to drastically reduce the requirement for liquid waste and/or additional 
fuels. 
In summary, one feature of the invention resides broadly in the process for 
the combustion of special wastes and vitrification of fine dusts in a 
rotary tubular kiln to which the wastes are conducted and from which, at 
the discharge side, non-gaseous wastes are transported into a molten slag 
bath and waste gases, which are produced during combustion of the waste in 
the rotary tubular kiln, are burned in an afterburner chamber and, if 
necessary, any of the combustion chambers of the kiln and afterburner are 
equipped with auxiliary burners, wherein the process is characterized by 
the fact that in the rotary tubular kiln 1, the combustion chamber 
temperature is controlled as a function of the molten flow of the slag by 
changing the amount of combustion air, allowing for possible 
substoichiometric combustion. 
Another feature of the invention resides broadly in the process 
characterized by the fact that the formation of nitrogen oxides is 
minimized by the addition of additives with substoichiometric combustion 
in a reducing atmosphere. 
Yet another feature of the invention resides broadly in the process 
characterized by the fact that bonded fine dusts are used as the additive 
substances. 
A further feature of the invention resides broadly in the process 
characterized by the fact that inorganic additive substances are added to 
the rotary tubular kiln as a function of the slag development and the 
melting behavior of the fine dust, and vitrification agents are added to 
the fine dusts if necessary. 
A yet further feature of the invention resides broadly in the process 
characterized by the fact that the fine dusts are bonded and made to melt 
more rapidly by reaction or wetting with one or more of the substances 
from the group consisting of: waste oil, oil sludge, resins, tar and other 
binders which can be used as energy sources. 
Yet another further feature of the invention resides broadly in the process 
characterized by the fact that the fine dusts are delivered from the 
output side of the rotary tubular kiln through an opening 6 in a 
transition housing 2 directly into the molten slag bath. 
An additional feature of the invention resides broadly in the process 
characterized by the fact that the molten slag flow is controlled by 
additional burners at the outlet of the rotary tubular kiln 1. 
A yet additional feature of the invention resides broadly in the process 
characterized by the fact that the burning of the waste gases is 
intensified in at least one turbulence zone, and, if appropriate by the 
injection of preheated combustion air and/or oxygen which produce 
turbulence in the waste gas stream. 
A further additional feature of the invention resides broadly in the 
process characterized by the fact that additional wastes and/or combustion 
air are introduced into the afterburner chamber 3, 13. 
A yet further additional feature of the invention resides broadly in the 
apparatus for the combustion process which includes, a rotary tubular kiln 
and a rotary tubular kiln discharge with a wet slag removal device, a fine 
dust input device, auxiliary burners, an afterburner chamber, air 
introduction devices and kiln control devices, wherein the apparatus is 
characterized by the fact that, ahead of the afterburner chamber 3, 13, 
there is a turbulence zone 2a, 12, which does not lie on the axis of the 
rotary tubular kiln. 
Another further additional feature of the invention resides broadly in the 
apparatus characterized by the fact that there is a transition housing 2 
between the rotary tubular kiln 1 and the afterburner chamber 3, 13 with 
openings 4, 6 for means to control the combustion process. 
A yet another additional feature of the invention resides broadly in the 
apparatus characterized by the fact that the waste gas inlet 12 from the 
transition housing 2 into the afterburner chamber 13 is oriented 
tangentially, and the afterburner chamber 13 is divided into zones 13, 14, 
and 16 having different cross sections. 
Another yet further feature of the invention resides broadly in the 
apparatus characterized by the fact that there is an inlet device 9 for 
combustion air in the chimney section 14 between the zones. 
A still further feature of the invention resides broadly in the apparatus 
characterized by the fact that, beyond the narrow transition cross section 
2a, 12, in the afterburner chamber 3, 13, there are additional waste 
burners and combustion air injection openings 5, 15 tangentially 
positioned at the level of the waste gas inlet 11. 
A still further additional feature of the invention resides broadly in the 
use of a rotary tubular kiln 1 with downstream waste gas combustion for 
the joint combustion of special wastes and for the vitrification of fine 
dusts, to which are added oxidizing substances and/or substances to 
control the molten slag flow from the outlet side. 
All, or substantially all, of the components and methods of the various 
embodiments may be used with at least one embodiment or all of the 
embodiments, if any, described herein. 
All of the patents, patent applications and publications recited herein, if 
any, are hereby incorporated by reference as if set forth in their 
entirety herein. 
The details in the patents, patent applications and publications may be 
considered to be incorporable, at applicant's option, into the claims 
during prosecution as further limitations in the claims to patentably 
distinguish any amended claims from any applied prior art. 
The invention as described hereinabove in the context of the preferred 
embodiments is not to be taken as limited to all of the provided details 
thereof, since modifications and variations thereof may be made without 
departing from the spirit and scope of the invention.