JPH04225783A - Opposed firing type rotary kiln - Google Patents

Abstract

PURPOSE: To provide an improved operation method of a rotary kiln and the rotary kiln without the fear of siutuations, where a refractory might be damaged and nitrogen oxide might be easily formed in which a larger throughput is obtainable compared with a conventional rotary kiln. CONSTITUTION: A flue pipe 6 is provided on an axial one end of a rotary cylinder 2, and first oxidant injection means is positioned on the other end. Second oxidant injection means is positioned on a flue pipe side end for injecting a fuel and an oxidant toward an opposite end of a combustion zone 5 to an end where the flue pipe is provided. The second oxidant injection means injects an oxidant into a rotary kiln with a moment enough to reach a distance equal to a length which is at least twice an inner diemeter of the rotary cylinder.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD This invention relates generally to rotary kilns, and more particularly to mobile rotary kilns.

0002

BACKGROUND OF THE INVENTION Rotary kilns are refractory lined cylindrical vessels commonly used for, for example, incineration of waste, calcining of cement, coke and other materials, firing of ceramics, and many other applications. In waste incineration, waste is put into a rotary kiln and burned,
The rotary kiln is conveyed by combustion fuel and oxidant injected into the rotary kiln from one end of the rotary kiln. Injection of combusted fuel and oxidant into the rotary kiln may be in co-current or counter-current flow with the flow of waste and other materials through the rotary kiln. Gas from within the rotary kiln is removed from a flue located at one end of the rotary kiln. After the waste passes through the rotary kiln, combustion waste ash is removed from the rotary kiln.

In countercurrent rotary kilns, the hot combustion gases and excess air carry the first volatile combustibles from the waste. These volatile combustibles are combusted to generate additional heat that flows opposite the flowing waste to further dry the waste. It is inevitable that the furnace gases containing sufficient mass will absorb the emitted heat and overheat, thereby damaging the furnace refractories or producing nitrogen oxides (NOx).
) is more likely to occur. Thus, the throughput of materials such as waste through a rotary kiln is determined by the amount of injected fuel and oxidant, by any volatile combustibles present, and also by the furnace gases transferred to the wet materials and other heat sinks. Limited by the rate of heat gained.

Another problem with co-current rotary kilns is that the heat released from the combustible volatiles escapes through the wet material heat sink. Auxiliary burners are generally required to provide extra heat to the drying zone to dry the wet materials to vaporize combustible volatiles. This increases the volumetric flow rate of gas exiting the flue, increases the amount of particulate matter carried and thereby increases the load on the air pollution device, ultimately limiting the throughput through the rotary kiln.

The mismatch between heat source and heat sink that limits the throughput of both counter-current and co-current rotary kilns is even more pronounced for long rotary kilns with length-to-diameter ratios (L/D) greater than 4. It will be tough. Rotary kilns are now widely used in the incineration of hazardous wastes. A particularly useful rotary kiln for such applications is a mobile or transportable rotary kiln. These rotary kilns are transported to hazardous waste sites and then removed after those hazardous waste sites have been cleaned. Unfortunately, mobile rotary kilns are necessarily smaller than stationary rotary kilns to allow for their transportation. Therefore, the throughput limitations discussed above are even more severe in the case of mobile rotary kilns.

[0006]

It is an object of the invention to provide a rotary kiln whose throughput exceeds that obtainable using conventional rotary kilns without fear of damage to the refractory or creating conditions susceptible to the formation of nitrogen oxides. An object of the present invention is to provide an operating method and a rotary kiln.

[0007]

[Means for solving the problem] According to the present invention, (A)
(B) a non-rotating wall at each end of the rotating cylinder; (C) a rotating cylinder having an inner diameter;
(D) a first oxidant jet positioned in the opposite end of the rotating cylinder from the end on which the flue means is provided; (E) a first oxidant injection means oriented to inject oxidant toward the end of the rotating cylinder provided with the smoke tube means; a second oxidant injection means positioned within the wall and oriented to inject oxidant toward an end of the rotating cylinder opposite the end at which the flue means is provided; a time sufficient to traverse a distance equal to at least twice the inner diameter of the rotating cylinder;
and said second oxidant injection means adapted to inject oxidant.

[0008] According to another aspect of the present invention, (A) providing a feeder containing combustible volatiles within a rotating cylinder; and (B) providing a smoke pipe at one end of the rotating cylinder. (C) injecting an oxidant from an end of the rotating cylinder opposite to the end provided with the smoke tube, and directing the oxidant toward the end provided with the smoke tube; and (D) oxidation from the flue-equipped end of the rotating cylinder toward the opposite end of the rotary cylinder toward the flue-equipped end. A method of operating a rotary kiln is provided that includes the steps of: injecting an oxidant with a moment at least equal to the body flow; and (E) volatilizing material from the feed body within a rotating cylinder. "Cylindrical" means tubular and generally, although not necessarily, has a circular radial cross section. "Waste" means any material intended for partial or complete combustion within a combustion zone. "Burner" means a device through which an oxidant and a combustible material are provided together, either separately or in a mixture, to a combustion zone. "Lance" means to pass an oxidant or combustible substance through it.
However, it refers to devices provided within the combustion zone rather than together. "Recirculation rate" means the ratio of the mass flow rate of material recirculated back around the injection to the mass flow rate of the total fluid injected into the combustion zone. "Flammable material" means a material that combusts under combustion zone conditions. "Non-flammable material" means a material that does not burn under combustion zone conditions. "Volatile material" means a material that passes into a vapor state under combustion zone conditions, such as the drying or decomposition of solid or liquid materials. Alternatively, it refers to vaporous substances produced by thermal dissociation. "Equivalent diameter" means that the diameter of the single orifice provides the same total area as the total area of the multi-orifice injection means.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention enables the throughput of a rotary kiln to be increased by maintaining a desired temperature profile throughout the rotary kiln. This reduces the large temperature gradients through the rotary kiln and reduces the need to heat parts of the rotary kiln to provide heat to other parts of the rotary kiln. Additionally, the need to burn auxiliary fuel to provide heat to the drying zone within the rotary kiln is also reduced. Throughput limitations caused by localized high temperatures or hot flue gas flows are thus alleviated. The present invention will be explained in detail below with reference to the drawings. Referring to FIG. 1, a rotary kiln 1 is illustrated and includes a rotating cylinder 2 and non-rotating walls 3 and 4. Non-rotating walls 3 and 4 are located at each axial end of the rotating cylinder and define a combustion zone 5. Preferably, the rotary kiln has a length to diameter ratio greater than 4 but less than or equal to 8.

A smoke pipe 6 is positioned at one end of the rotating cylinder 2 in the axial direction. Although shown in the horizontal direction in Figure 1,
The flue 6 can be provided in any suitable orientation, including vertically. A first oxidant injection means, such as a first burner 7, is connected to a smoke pipe 6.
It is positioned within the end opposite to the non-rotating wall 4 provided with. The first burner 7 is oriented to inject fuel and oxidant towards the end of the rotating cylinder 2 on the side within which the smoke tube is provided. A second oxidant injection means is positioned at the end of the non-rotating wall 3 opposite the flue and directs fuel and oxidant to the opposite end of the combustion zone 5 from the flue end. Oriented to inject oxidant toward the end. Alternatively, the first and second oxidant injection means may be lances, such as lance 12. In that case only oxidant is provided from the lance to the combustion zone.

[0011] The second oxidant injection means injects the oxidant in a direction away from the end of the rotary cylinder on the side where the smoke pipe is provided, and the oxidant is injected into the inner diameter of the rotary cylinder. It is adapted to be injected into the rotating kiln with a sufficient moment to reach a distance equal to at least twice the length, preferably equal to 50% of the length. One means of achieving such high moments is to use a diametrically restricted orifice, i.e., of equal diameter, the diameter of which is 1/2 of the inner diameter of the rotary kiln.
The multi-orifice does not exceed 30 and preferably does not exceed 1/100. The restricted orifice gives the oxidant a high velocity defined by Bernoulli's theorem, and such high velocity increases its moment since moment is the product of mass and velocity. Another way to achieve this high moment is to increase the mass of the second oxidant. However, this method is undesirable because it also increases the mass and momentum of the gas flow toward the flue-equipped end of the rotary kiln.

A second oxidant means is illustrated in FIGS. 4, 5 and 6. Referring to FIG. 4, a single orifice nozzle with a restricted diameter for oxidant injection is illustrated. FIG. 5 illustrates a multi-orifice nozzle. The multi-orifice nozzle has a limited equal diameter to enable the required high moments to be achieved. FIG. 6 illustrates a burner in which oxidant and fuel may be injected through a coaxial tube to create an oxidizing gas. Oxidant may be delivered through the center tube and fuel may be delivered through the outer annular passage. The reverse is also possible. The center tube can be fitted with a single orifice nozzle or a multi-orifice nozzle.

FIG. 7 illustrates another embodiment of the present invention. The embodiment allows the oxidant and some fuel to be drawn into and diffused into a recessed cavity within the kiln wall. The recessed cavity confines hot combustion products at a temperature close to the adiabatic flame temperature of the mixture to move away therefrom at high velocity. In this embodiment, the diameter of the recessed cavity at the point where it communicates with the rotary kiln is less than 1/10 of the inner diameter of the rotary kiln.

In operation, a feed such as waste 9 containing volatile materials is provided into the combustion zone 5 through such as a ram feeder 10 to form a fluidized bed through the combustion zone. Other feedstocks that may be used in the present invention include cement, coke, ceramics, and other materials that contain volatile components such as water. The method of the present invention will be explained in detail below. The method of the present invention is described as using a waste material as a feedstock, which may contain volatile combustibles and volatile non-combustibles. Waste must be handled according to the Resource Conservation and Recovery Act (RC).
RA) or in liquid and/or solid form as defined in the Toxic Substances Control Act (TSCA). These wastes are passed sequentially through a drying zone 13 where volatile non-combustibles such as water and some of the much lighter volatile combustibles are dried and additional combustibles are removed in a pyrolysis zone 14. The remaining solids are volatilized and burned in the carbon burnout zone 15. The resulting ash is removed from the combustion zone 5 through the ash removal door 11. As will be apparent to those skilled in the art, there is no clear division between these zones. In FIG. 1, the volatilization of incombustibles and combustibles in the drying zone 13 and the pyrolysis zone 14 is shown by arrows.

The fuel and oxidant are injected into the combustion zone 5 through the first burner 7 and are combusted there, thereby providing heat to the combustion zone for drying, pyrolyzing and burning out the previously mentioned wastes. Provided to. The oxidant is air,
It may be commercially pure oxygen with a concentration greater than 99.5% purity, or it may be oxygen enriched air with an oxygen concentration of at least 25% and preferably greater than 30%. The fuel may be any suitable fluid fuel such as natural gas, propane, fuel oil or liquid waste.

The combustion of the fuel, the injection of oxidant into the combustion zone 5 through the first burner 7 and the combustion of the volatile combustibles vaporized from the waste are carried out at the end of the rotating cylinder provided with a flue. Create a gas flow towards. Gas is discharged from the combustion zone 5 through a smoke pipe 6.

[0017] The fuel and oxidant are injected into the combustion zone 5 through the second burner 8, thereby forming an identical injection to the fuel and oxidant injected through the first burner 7. The fuel and oxidant injected through this second burner 8 have a moment at least equal to, preferably 200% greater than, the moment of gas flow towards the flue-equipped end of the rotary kiln. The gas flow towards the flue-equipped end comprises fuel and oxidant and their combustion products injected through the first burner 7, water vapor, combustion products of the substance injected through the second burner 8, and May contain volatile combustible combustion products. As is known, the moment of a fluid is equal to the product of mass and velocity. The combustion reaction stream injected from the second burner 8 thus reaches a significant distance inside the combustion zone 5, preferably a distance of at least twice the diameter of the rotary kiln. The heat released by the combustion of the fuel and oxidant injected from the second burner 8 serves to provide heat for drying, pyrolysis and burnout of the waste, as described above.

The mutually opposed burner flame arrangement of the present invention provides a much more uniform temperature within the combustion zone than that of a conventional rotating kiln arrangement. It means that the two jet flows are reversed as shown in Figure 1 by arrow 1.
6, since they recirculate each other to the combustion zone. Gas flow from the flue-equipped end of the rotary kiln is sufficient to successfully operate the invention. Furthermore, the high momentum of the combustion flow on the side with the flue increases the recirculation, as indicated by arrow 17. In this way, the temperature gradients inside the rotary kiln are better managed and therefore throughput limitations based on heat transfer rate considerations or fuel gas flow considerations are relaxed.

Preferably in the method of the invention, the oxidant stream injected through the first burner 7 and the second burner 8 provides a gas recirculation ratio of preferably greater than 4 in the combustion zone. It is injected at high speed to provide a flow. Preferably, the oxidant flow velocity is greater than 150 feet per second (about 45 meters per second). In this way, the temperature inside the combustion zone 5 is made uniform. This allows the oxidant from the first burner 7 to be recirculated into the combustion zone 5 one or more times, rather than simply passing the gas through the combustion zone 5 as shown in FIG. This is particularly the case when injected to further equalize the temperature within the recirculation zone of each of the two parts within the combustion zone by increasing the internal combustion rate and mixing therein.

In another embodiment of the invention, the injection end of the second burner is located at the flue-equipped end of the rotary kiln, but is flush therewith as shown in FIGS. rather than being disposed in the combustion zone, it is projected into the combustion zone as shown in FIG. Common elements in FIGS. 3 and 1 are designated by the same reference numerals. This establishes a plug flow zone just in front of the flue. There is very little gas backmixing or recirculation in this plug flow zone. In this much calmer plug flow zone, gas velocity is reduced due to lack of recirculation flow. Therefore, particulate matter entrained by the air tends to fall out of the gas flow. The gas also cools somewhat, thereby reducing its velocity. The protrusion distance of the second burner is a practical length, typically a diameter distance of the rotary kiln.

In countercurrent rotary kilns, it is desirable to inject additional oxidant, such as industrially pure oxygen, into the combustion zone from the flue-equipped end to further carry out the combustion in the drying zone. . This is particularly the case when large amounts of combustibles are volatilized from the feed and transported by the flowing gas to the drying zone, thereby creating a pyrolysis or fuel enrichment situation within the drying zone. Additional oxidant may be injected through the second burner 8 or through the lance 12, depending on which is used as the second oxidant injection means.

The present invention allows a rotary kiln operator to operate a combustion zone using two separate combustion control zones at each end of the kiln. In addition to stoichiometric operation, combustion control zones at each end of the rotary kiln control pyrolysis (fuel enrichment) or oxidation (oxygen enrichment) conditions, thus controlling rotary kiln design and combustion processes. Provides flexibility for control. For example, when processing waste with a particularly high BTU content, the combustion control zone at the flue-equipped end of the countercurrent rotary kiln may be operated in pyrolysis mode, thereby allowing the waste to be released from the combustion control zone. The resulting combustible gas is recirculated to the flue end where it is entrained in the high momentum stream injected from the burner, thereby consuming the oxidant. The remaining ash in the combustion control zone at the other end of the rotary kiln can be exposed to oxidizing conditions to completely burn it out.

The use of oxygen enrichment in the method of the invention
Reduces the momentum of the gas flow toward the flue, thereby facilitating injection of oxidant into the rotating kiln from the flue-equipped end, and reduces the volumetric flow rate of the gas flow through the flue, thereby increasing throughput. It acts to increase. Therefore, the lower the percentage of inert nitrogen that is introduced with the oxidant into the combustion zone, the more beneficial the operation of the process of the invention will be. To achieve maximum throughput, the most preferred oxidant is commercially pure oxygen, albeit with air contamination.

FIG. 2 illustrates waste incineration in a co-current rotary kiln to which the method of the present invention is applied. Common elements in FIGS. 2 and 1 are designated by the same reference numerals. In the embodiment shown in FIG. 2, the smoke pipe 20 is located at the end of the rotary kiln opposite the waste input end. A first oxidant injection means, such as a lance or burner 21, is positioned within the non-rotating wall 3 at the end opposite the flue. A second oxidant injection means, such as a lance or burner 22, is then positioned within the non-rotating wall 4 on the side provided with the flue. Burners 21 and 22 each inject oxidant in opposite directions from where they are positioned. The operation of the rotary kiln illustrated in Figure 2 is similar to that shown in Figure 1, except that the gas flow toward the smoked end is cocurrent rather than countercurrent, and the waste is dried flow sequentially through the pyrolysis zone, pyrolysis zone and ash burnout zone.

In conventional rotary kilns used for hazardous waste incineration, the hazardous gases emitted from the wastes do not always pass through the flame zone of the combustion zone. In conventional countercurrent rotary kilns, these harmful gases may not even be exposed to the high temperatures inside the rotary kiln. Conventional incineration systems using rotary kilns therefore rely heavily on secondary combustion chambers for the destruction of harmful components. However, in the system of the present invention, the opposed burners create extensive gas recirculation within the combustion zone, so that the hazardous gases vaporized from the waste pass through the flame zone multiple times, thereby ensuring efficient removal of hazardous components. Destruction is increased. This eliminates the need for a secondary combustion chamber in the incineration of hazardous wastes in some cases.

The present invention improves the operation of a rotary kiln by allowing independent adjustment of the injection of oxidant and fluid fuel at the flue-equipped end and at the opposite end. Improve controllability on top. This is particularly beneficial when the two oxidants have different oxygen concentrations, such as air and commercially pure oxygen. For example, in the present invention, the volumetric flow rate of gas removed through the flue can be determined. "Determine" here means to measure a certain value,
It means to know by calculation or estimation. The determined flow rate is then compared to a predetermined desired flow rate, and the oxidant flow rate can be adjusted or changed such that the determined flow rate changes in the direction of the desired flow rate. In contrast to traditional processes, the high momentum of the oxidant injected from the flue-equipped end of the rotary kiln delivers a significant gas flow through the rotary kiln in a direction away from the flue. Additionally, the desired temperature profile and furnace atmosphere can be maintained while the flue gas flow varies the flow rate of the injected oxidant.

In another example, the pressure inside the rotating cylinder can be determined. When incinerating waste, it is typically desirable for the internal pressure of the rotary kiln to be negative. The determined pressure is then compared to a predetermined desired pressure, thereby adjusting the oxidant flow rate so that the desired temperature profile and furnace atmosphere are achieved while such determined pressure is varied in the direction of the desired pressure. Adjustable to maintain.

Another method for improving the operational control of a rotary kiln is to reduce the heat demand in both the combustion zone at the flue end and the combustion zone at the opposite end. The flow of one or both of the oxidant and the fluid fuel can be adjusted to determine the amount and, if necessary, to accommodate the heat demand simultaneously.

As will be appreciated, any operational parameters may be determined by comparing them to predetermined desired values for those parameters, and the total oxidant flow rate and flow rate ratio may be determined. The values of the parameters determined may be adjusted to change the parameters in a direction toward desired values for those parameters. As mentioned earlier, this beneficial control is based on variations in the overall flow rate and flow rate of the oxidant, such that the oxidant injected from the chimney end of the rotary kiln has a high moment. This is due to This not only does not adversely affect the flue-equipped end of the rotary kiln as in conventional processes, but it also significantly increases the efficiency of gas flow within the rotary kiln. An important advantage of the present invention is that the temperature or heat release and atmosphere at both ends of the rotary kiln can be controlled separately, while the gas flow or pressure inside the rotary kiln can be controlled simultaneously.

By injecting water, especially a spray stream, into the rotary kiln, the temperature inside the rotary kiln can also be controlled or moderated.

The following examples are for illustrative purposes and the invention is not limited thereto. Example 1 A scaled down cooling flow model of a rotary kiln similar to that illustrated in FIG. 3 was used. This rotary kiln model was approximately 3.5 feet (approximately 1.05 meters) long and had a length to diameter ratio of 7. The volumetric flow rate of the gas injected from the nozzle toward the flue end of the rotary kiln is 7380 cubic feet per hour (CFH).
(approximately 208.9 m3). The flame from the burner was ejected at a high velocity and away from the flue end at a volumetric flow rate of 670 CFH (about 18.9 m3). The initial velocity of this jet is approximately 1000 feet per second (approximately 3
00 meters). The moment of flow from the burner is 10 times the moment of the gas flowing toward the flue.
It ranged between 0 and 500 percent. The flow from the flue end amounted to 63.3% of the length of the rotary kiln. Recycle gas flow within the rotary kiln was significant.

Example 2 A countercurrent rotary kiln similar to that illustrated in FIG. 3 was used. The rotary kiln was 45 feet (approximately 13.5 meters) long and had an inside diameter of 6.5 feet (1.95 meters). Flow rate: 4092 pounds per hour (approximately 1856
kg) of oxygen and a flow rate of 1066 lb/hr (approximately 483
．． 5 kg) of natural gas with a calorific value of 22,991 BTU/lb was injected at high momentum into the rotary kiln from the flue end through a burner that projected 5 feet (approximately 1.5 meters) into the rotary kiln. flow rate 11 per hour
,000 pounds of air and a flow rate of 613 pounds per hour of natural gas were injected into the rotary kiln from the end opposite the flue end. The rotary kiln is operated at negative pressure and the ambient air is
00 pounds (approximately 2494.7 kg) leaked into the rotary kiln. Waste containing hazardous waste and having a moisture content of 15 percent but no calorific value is produced every hour at 2
A quantity of 5 tons was charged into the rotary kiln from the flue side end. removed from the rotary kiln at a temperature of 900°F (500°C) at a flow rate of 42,494 pounds per hour and 29.777 pounds per hour.
flow rate (30,630 cubic feet per minute) of 1600
Gas was removed through the smoke tube at a temperature of °F (approximately 888.9 °C). The oxygen concentration of this gas was 3.1 percent.

[0033] When combusted with air only, 90
With the required ash temperature of 0°F (500°C), the maximum waste treatment rate was only 16 tons per hour. Then,
With oxygen enrichment at the discharge end and no oxygen burner toward the discharge end, the flame was shortened and the combustion gas temperature gradient was significantly increased, thereby increasing throughput. The waste was not held long enough to warm up to a temperature for detoxification reactions.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of one embodiment of the invention used in conjunction with waste incineration in a countercurrent rotary kiln.

FIG. 2 is a schematic cross-sectional view of another embodiment of the invention used in conjunction with waste incineration in a co-current rotary kiln.

FIG. 3 is a schematic cross-sectional view of another embodiment of the invention implemented using a plug flow zone.

FIG. 4 is a partial cross-sectional view illustrating a single orifice type oxidant injection means for injecting oxidant with high momentum into a rotary kiln from a flue-equipped end;

FIG. 5 is a partial cross-sectional view illustrating a multi-orifice type oxidant injection means for injecting oxidant with high momentum into a rotary kiln from an end provided with a flue;

FIG. 6 is a cross-sectional view of a burner that may be used in the practice of the present invention.

FIG. 7 is a cross-sectional view illustrating a means for reacting oxidant with fuel in a recessed cavity prior to injection into a rotary kiln.

[Explanation of symbols]

1 Rotary kiln 2 Rotating cylindrical body 3. Non-rotating wall 4. Non-rotating wall 5 Combustion zone 6 Smoke pipe 7 First burner 8 Second burner

Claims (40)

[Claims] 1. (A) providing a delivery body containing combustible volatiles within a rotating cylinder; (B) removing gas through a flue provided at one end of the rotating cylinder; (C) injecting an oxidant from an end of the rotating cylinder opposite to the end provided with the smoke tube to create a flow of oxidant toward the end provided with the smoke tube; D) oxidant from the flue-equipped end of the rotating cylinder toward the opposite end of the rotary cylinder with a moment at least equal to the oxidant flow toward the flue-equipped end; (E) volatilizing a substance from the feed body within a rotating cylinder. 2. A method of operating a rotary kiln according to claim 1, wherein the feed body is provided to the rotating cylinder from the same end from which gas is removed through the flue. 3. The method of operating a rotary kiln according to claim 1, wherein the feed body is provided to the rotating cylinder from an end opposite to the side from which gas is removed through the flue. 4. The method of claim 1, wherein the oxidant injected in step (D) is injected into the rotating cylinder at a distance equal to at least twice the diameter of the rotating cylinder. 5. The method of operating a rotary kiln according to claim 1, wherein the feed material is waste containing combustible materials. 6. The method of operating a rotary kiln according to claim 5, further comprising volatile combustibles from waste within the rotary cylinder. 7. The method of operating a rotary kiln according to claim 5, wherein the feed body contains water as a volatile substance. 8. The method of operating a rotary kiln according to claim 1, wherein at least one of the oxidants injected into the rotating cylinder in steps (C) and (D) is commercially pure oxygen. 9. The rotating apparatus of claim 1, wherein at least one of the oxidants injected into the rotating cylinder in steps (C) and (D) is oxygen-enriched air having an oxygen concentration of about 25%. How to operate a kiln. 10. The oxidant injected into the rotating cylinder in step (C) is air, and the oxidant injected into the rotating cylinder in step (D) is industrially pure oxygen. How to operate a rotary kiln in Section 1. 11. The method of operating a rotary kiln according to claim 1, wherein the oxidant injected into the rotating cylinder in step (D) is injected at the same height as the wall onto which it is injected. 12. The method of operating a rotary kiln according to claim 1, wherein the oxidant injected into the rotating cylinder in step (D) is injected from a position protruding from the wall where it is injected. 13. The method of operating a rotary kiln according to claim 1, wherein in step (C) the fuel is injected together with the oxidant. 14. The method of operating a rotary kiln according to claim 1, wherein in step (D) the fuel is injected together with the oxidant. 15. The rotary kiln according to claim 1, wherein the combustion is carried out under pyrolytic conditions at least one of the end of the rotary cylinder on which the flue is provided and the end opposite thereof. how to drive. 16. Operation of the rotary kiln according to claim 1, wherein the combustion is carried out under oxidizing conditions at least one of the end of the rotary cylinder provided with the flue and the opposite end thereof. Method. 17. Combustion is carried out under pyrolytic conditions at the end with the flue and under oxidative conditions at the end opposite the flue. A method of operating a rotary kiln according to claim 1, which is carried out. 18. Determine the volumetric flow rate of gas removed through the flue, compare this determined flow rate with a predetermined desired flow rate, and determine the oxidant injection in step (C) and the step (D).
2. A method of operating a rotary kiln as claimed in claim 1, including the step of adjusting the volumetric flow rate of the oxidant in ) so as to vary the volumetric flow rate of gas from the flue toward a desired flow rate. 19. Determining the pressure inside the rotating cylinder and comparing the determined pressure with a predetermined desired pressure, step (
2. The rotary kiln of claim 1, comprising the step of adjusting the oxidant injection in C) and the oxidant volumetric flow rate in step (D) so that the pressure inside the rotating cylinder varies toward a desired pressure. how to drive. 20. Determine the heat demand at the end of the rotating cylinder provided with the flue and at the opposite end, and determine the oxidant injected in step (C) and the amount of heat required in step (D). 2. A method of operating a rotary kiln as claimed in claim 1, including the step of adjusting at least one flow of oxidant injected in step ) to accommodate said determined heat demand. 21. The method of claim 1, wherein the oxidant injected in step (C) and the oxidant injected in step (D) have different oxygen concentrations. 22. Determining the values of operational parameters, comparing the determined parameter values with predetermined desired values for those parameters, and determining the oxidant to be injected in step (C) and the step 2. The method of claim 1, including the step of adjusting the volumetric flow rate of the oxidant injected in step (D) so that the determined parameter value varies toward the desired value. 23. The rotary kiln of claim 1, including the step of separately controlling the temperature and atmosphere at each end of the rotating cylinder while simultaneously controlling the gas flow into the rotating cylinder. how to drive. 24. The oxidant injected into the rotating cylinder in step (D) is introduced into a cavity which is set back from the wall into which it is injected, and is subsequently passed from this cavity into the rotating cylinder. 2. A method of operating a rotary kiln according to claim 1, wherein 25. The method of claim 24, wherein some of the oxidant is combusted with the fuel inside the cavity. 26. The method of claim 1, wherein the oxidant injected in step (D) is an oxidizing gas generated from a burner. 27. The method of operating a rotary kiln of claim 1, including the step of injecting water into the interior of the rotating cylinder. 28. (A) a rotating cylindrical body having an inner diameter; (B) a non-rotating wall at each end of the rotating cylindrical body;
C) flue means disposed in a non-rotating wall at one end of the rotating cylindrical body; and (D) a first oxidizer positioned within an end of the rotatable cylindrical body opposite from the end at which said flue means is disposed. (E) the first oxidant injection means is oriented to inject the oxidant toward the end of the rotating cylindrical body at which the smoke tube means is provided; a second oxidant injection means positioned within the non-rotating wall and oriented to inject oxidant toward an end of the rotating cylindrical body opposite to the end at which the flue means is provided; , said second oxidant injection means adapted to inject said oxidant for a time sufficient to traverse a distance equal to at least twice the inner diameter of said rotating cylindrical body. Claim 29: The rotating cylindrical body has a length to diameter ratio of 4.
29. The rotary kiln of claim 28, wherein the rotary kiln exceeds . 30. The rotary kiln of claim 28, further comprising means for providing a feed from the end of the rotary kiln on the side of the rotary kiln provided with the flue means. 31. The rotary kiln of claim 28, further comprising means for providing a feed from an end of the rotary kiln opposite the side on which the flue means is provided. 32. The rotary kiln is a movable rotary kiln, further comprising means for providing a feed body from the end of the rotary kiln opposite to the side on which the flue means is provided. 29. The rotary kiln of claim 28. 33. The rotary kiln of claim 28, wherein the second oxidant injection means has an injection end flush with the non-rotating wall. 34. The rotary kiln of claim 28, wherein the oxidant injection end of the second oxidant injection means extends beyond a non-rotating wall within which the second oxidant injection means is located. 35. The rotary kiln of claim 28, wherein at least one of the first oxidant injection means and the second oxidant injection means is a burner. 36. Claim 2, wherein at least one of the first oxidant injection means and the second oxidant injection means is a lance.
8 rotating kilns. 37. The second oxidant injection means is a restricted orifice having a diameter or 1/30 of the inner diameter of the rotating cylinder.
29. The rotary kiln of claim 28, including a plurality of orifices having equal diameters not exceeding . 38. The rotary kiln of claim 28, wherein the second oxidant injection means includes a cavity within the non-rotating wall that communicates with the rotating cylinder. 39. The rotary kiln of claim 38, wherein the cavity has a restricted diameter at a location where it communicates with the rotating cylinder. 40. The limiting diameter of the cavity at the location where it communicates with the rotating cylinder is 1 of the inner diameter of the rotating cylinder.
40. The rotary kiln of claim 39, wherein the rotary kiln is less than /10.