HIGH TEMPERATURE ALUMINUM COMBUSTOR FOR THE INCINERATION OF HAZARDOUS MATERIAL

摘要

The incineration of radioactive, chemical and mixed hazardous materials requires high temperature combustors. In addition to high temperature, the incinerator must produce clean combustion. Aluminum is a very energetic metallic fuel, more reactive than either magnesium or lithium. Aluminum may produce an adiabatic reaction temperature of up to 10,600 °C when it reacts with oxygen. The combustion product is aluminum oxide, which is a valuable product for many industrial applications. The process of aluminum combustion is emission free. The aluminum powder (97.5%) used for the reaction costs $0.0632 per gram. The value of the combustion products, aluminum oxide (alpha 99%), is $0.255 per gram. Thus, the combustion product, aluminum oxide, is worth four times the cost of the fuel, aluminum. However, there is problem with the direct burning of aluminum in air or water. The main problem is the high ignition temperature required and long delay time until ignition occurs. A lower ignition temperature (1300-1400°C) can be achieved by oxidizing the aluminum with steam from water. In an oxygen atmosphere (I.e. air), an aluminum particle is coated by a strong, dense layer of Al2O3. In order to ignite the aluminum, it is necessary to raise the particle temperature higher than the Al2O3 melting point (2000°C). Ignition delay time consists of the time needed to heat and melt the Al2O3 layer, plus the diffusion time required for the oxygen to each the aluminum surface to react. However, when Al vaporizes, the kinetics are extremely fast and no longer controls the combustion process. The sum of all these times are large, thus Al particles escape with the high-speed gas flow from the combustion chamber without chemical reaction. GVE and AB Technologies possess technology that can overcome the difficulties of burning aluminum. The technology uses a new mechanism for cracking the strong layer of Al2O3 covering the bare Al. The method was tested and used to burn Al in both air and water atmospheres. Observed combustion products were very fine, white aluminum oxide particles. The particles accumulated in the exhaust channel. No analysis of these aluminum oxide particles has been done. Among other useful and important applications of aluminum-air (water) combustion, GVE and AB Technologies are developing an aluminum-air combustor for high temperature incineration of hazardous materials. High temperature flow from the incinerator process can be harnessed to drive a conventional or low RPM turbine to generate power. The excess exhaust heat is recuperated into the main cycle or used in a cogeneration or bottoming cycle.