Hazardous or toxic waste destruction or containment – Containment – Solidification – vitrification – or cementation
Reexamination Certificate
2001-01-24
2003-04-29
Silverman, Stanley S. (Department: 1754)
Hazardous or toxic waste destruction or containment
Containment
Solidification, vitrification, or cementation
C588S253000, C588S253000, C588S253000, C588S253000, C588S249000, C588S249000, C422S186220
Reexamination Certificate
active
06555727
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for the chemothermal conversion of fluid compounds or compounds which are convertible into a fluid state, and to a converter for the performance of the method.
BACKGROUND OF THE INVENTION
The protection of the environment gains more and more importance, and correspondingly, emission restrictions are becoming stricter and stricter. Incineration and other thermal processes are still the most common ways of eliminating waste or substances by means of thermal destruction. The efficiency rate of thermal destruction has therefore to become much higher, in order to meet the new demands.
As an example, according to the very common German regulation, not more than 1.5 nanogram of dioxins per m
3
is allowed as an average emission. In order to meet this regulation, thermal destruction has to have an efficiency rate of at least 99.9999985%. A maximum of 0.0000015% of the compounds is allowed to be incompletely destroyed in order to reach such a high efficiency rate.
At the same time, it is not only necessary to reach such a high rate of efficiency, but also, in order to open all of the molecular bonds, a high temperature is necessary. For example, fluoro-chloro-hydrocarbons are extremely temperature stable, and require a temperature higher than 1,900° to be cracked. To reach this aim, very often a temperature is chosen that can open all molecular bonds. The molecular structures are then replaced by an ionic structure or form called “plasma.” Such a structure can also be a mixture wherein some of the molecules are already in an ionic form and other, more stable molecular structures are still intact. In such an event, the structure will be called a “plasma-like structure” or form.
The highest temperature level or temperature is required for the initial opening of the molecular bonds, and must be achieved first.
To reach the required efficiency rate, the temperature has to be distributed in such as way that there is no colder zone where molecules could pass through without being cracked into atoms. Thus, a flame geometry ensuring sufficient heat distribution is also essential to obtaining a high efficiency rate.
In order to achieve efficient thermal destruction at an industrial scale and not just in a laboratory device, these three tasks: high efficiency rate, sufficient heat distribution, and sufficient high temperature, must be realized at reasonable cost.
There are certain physical phenomena and effects that limit reaction possibilities in burners, burner systems, or similar systems and devices. An exothermic chemical reaction creates a certain amount of energy. This energy is set free with the chemical reaction and at the location of the reaction. The energy leads to a specific temperature, depending upon the volume, mass, and distance to the point of the chemical reaction. The closer to the point of reaction, the higher is the temperature. The largest part of the energy is released in the form of radiation, especially infrared radiation, spreading from the point where the chemical reaction takes place. The temperature, as a function of the heat, can also be connected to this radiation. Thus, the temperature decreases exponentially with the exponential increase of the spherical surface of distribution of the heat radiation.
Only a complete exothermic chemical reaction leads to a complete conversion of the compounds. If other compounds or, for example, a feedstock, interferes with the exothermic chemical reaction, then part of the exothermic reaction will not take place. Normally, in a continuous exothermic reaction, a molecule or molecules which have just been converted in the exothermic reaction or have reacted, will send energy to the following molecules of the continuous exothermic reaction partner and will initiate or ignite another reaction. If the other compounds are mixed with the main one, the main reaction will be incomplete and/or insufficient. A feedstock might shield and partly interrupt the exothermic reaction. In such a case, the requested and targeted efficiency rate of 99.9999985% cannot be achieved.
Consequently, the exothermic chemical reaction and the feeding of the compound to be destroyed have to be carried out at different places or times. First, the exothermic chemical reaction must be completed, and only then the next compound that is in need of the exothermic energy may be added.
Burner systems intended to destroy compounds by means of an exothermic chemical reaction therefore feed the first compound to be destroyed after the first exothermic reaction, and afterwards feed the second compound or mixture of compounds. In this way, the reactions are completed by the various burner systems and the presence of residues of the basic reaction in their flue gases is avoided.
It can be seen in prior art references that it is an acknowledged necessity to complete the first exothermic reaction before further compounds or feedstock are introduced for thermal destruction. It is not important whether the thermal destruction is for the purpose of destroying substances or compounds, or whether it is intended to create new ones and the destruction of a molecular structure is only a necessary step of a more complex reaction or series of reactions.
In the drawings of U.S. Pat. No. 2,934,410 (G. H. Smith), it can clearly be seen that the two-zone burner is divided into an upper area wherein the exothermic reaction takes place and is completed, and a lower, secondary area wherein the stock or further compounds are fed into the burner.
The earlier U.S. Pat. No. 3,098,883 (O. Heuse), describes and shows that the reaction has a first, exothermic portion divided into several parts, which is followed by a second, also divided, step wherein the provided energy is used to open molecular bonds. In the case of the patent to Heuse, the energy is intended to create or produce new substances with the aid of the energy released at a high temperature from the primary reaction step. This patent also describes the need for short flames, in order not to cause a decrease of temperature by losing much of the energy.
A short flame is short because the exothermic reaction inside the flame is fast. Heuse also indicated that the exothermic reaction first has to be completely terminated before the secondary step is started. This is also clear from the drawings, wherein it can be seen that the first exothermic reaction takes place at a separate portion of the apparatus, and especially from the technical detail that the fuel and oxidizing gas are introduced separately into the apparatus. The apparatus of Heuse, therefore, also requires allowing the compounds of the exothermic reaction to react in the first portion, and only then adding the next compound in the further portion. The difference with respect to the more basic concept of Smith is that Smith divides the stream of introduced gases into several smaller streams, together with the option of giving these streams a spin to produce additional kinetic energy and introducing these gases tangentially, creating a rotation that assists in mixing the combustion gases of the first exothermic reaction with the compounds of, or for, the secondary reaction.
Both of these prior art U.S. patents clearly show a burner device and procedure having two steps following each other, involving a first, exothermic reaction followed by a secondary reaction. Overlapping of these reactions is not intended. Most known burners and burner devices use this principle.
In U.S. Pat. No. 4,007,002 (Robert M. Schirmer), describing combustors and methods of their operation, the same principle is used. A first reaction is completed and is even covered by an inner housing, in order to avoid contact of the gases of the first reaction with the compounds of the second reaction before the first reaction is completed.
Conventional burners and similar devices that use an exothermic reaction to gain energy have in common that they, by different means, complete the preliminary exothermic reaction first before they begin the next ste
Medina Maribel
Silverman Stanley S.
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