AC FOX

Activated Carbon Facilitated Oxidation

Technology Review

December 2005

 

AC FOX:  Activated Carbon Facilitated Oxidation

Low Temperature Oxidation Technology Overview

 

 

The core technology is a novel oxidation regime where a bed of granular activated carbon facilitates the oxidation of organics by adsorbing the organics into the carbon internal surfaces and promotes the reactions with the surface bound oxygen present within the activated carbon. This method can be used to continuously oxidize organics or remove adsorbed organics from spent activated carbon, thereby regenerating the carbon. Both applications convert the adsorbed organics into useable energy.

 

For those applications directed at the regeneration of spent activated carbon, the principal criterion is that the adsorbed material be capable of participating in an oxidation reaction with oxygen as the oxidant. The activated carbon chemisorbs oxygen from the vapor phase and facilitates the oxidation of the organics within the internal adsorption sites of the activated carbon. The most reactive bond appears to be the carbon-hydrogen bond found in hydrocarbons and most organics. It is not known whether the carbon-chlorine bond and other carbon-halide bonds are similarly reactive under the AC FOX conditions.

 

For the regeneration of spent activated carbon, the reaction rate varies depending on the adsorbed organics. In general, adsorbed organics equaling ½ to 2 percent of the carbon’s weight can be oxidized per hour under AC FOX conditions. Most liquid-phase adsorption applications will load GAC up to levels that will allow the heat of combustion of the adsorbed organics to provide the bulk of the energy required to evaporate the residual moisture in the drained spent activated carbon. Techniques are available for regenerating carbons with high loadings and fuel values that generate excess heat during regeneration. For liquid-phase carbons that are lightly loaded, such as potable water treatment carbons, the reactor design is modified to allow additional heat input during regeneration.

 

 

What are the major problems that AC FOX may solve? The following areas are likely candidates:

 

1. AC FOX technology will address multiple disposal issues that currently face many operating industries – disposal of waste liquids, abatement of smog-generating vapors and the disposal of spent activated carbon. Furthermore, it will address these current cost centers in a manner that will produce a valuable source of heat, principally in the form of medium pressure steam (250 to 1000 psi steam) or some other heat transfer media at 400-600°F. Thus, the energy produced by the AC FOX  destruction of unwanted industrial byproducts will be utilized as a further cost savings to the industrial operation.

2. AC FOX technology features total elimination of internal temperature fluctuations within the reaction zone. These temperature fluctuations result in the formation of unwanted side products during destruction of hazardous liquids using combustion processes featuring open flames – the most notorious being the de novo formation of Dioxin in municipal waste burners. Since activated carbon provides five square miles of surface area per cubic foot of reactive volume, significant molecular level temperature fluctuations are non-existent. With AC FOX technology, unwanted oxidation reactions are eliminated. As such, down stream reactor effluent treatment requirements are dramatically reduced, as are the regulatory oversight due to concerns for the fence-line receptors.                     

3. Most technologies that utilize oxidation to convert hydrocarbons to water vapor and carbon oxides utilize thermal combustion. Thermal combustion processes typically involve open flames and localized temperatures above 1000°C, which requires specialized materials of construction such as refractory linings and exotic metals. In contrast, the AC FOX technology temperatures are suitable for carbon steel, which is the least expensive and most versatile fabrication material available. Compared to alternate available technologies, this translates into much lower capital costs for the installation of a given industrial capacity

4. AC FOX technology exhibits broad operational flexibility in terms of stopping, starting and operating temperature. The AC FOX reactor can be essentially “stopped in its tracks” by halting the air supply, and restarted with minimal delay upon resuming the airflow.  The operating temperature is controlled by adjusting the rate of heat removal independent from the rate of heat production, which is controlled by the supply of air. This results in an industrial process that is available when it is needed, but does not require significant “idling” costs when it is not being utilized.

5. Finally, the AC FOX technology can be implemented on a wide variety of sizes of applications. The technology can be “scaled” (the engineering term) to a wide range of mechanical packages. This allows small applications to be located close to the point of utility, yet the technology does not have any apparent requirements or restrictions that prevent it from being implemented on very large applications. From a manufacturing perspective, this simplifies the equipment fabrication and support of the operating systems once installed. Nothing is worse than a custom design for each application.