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Process and apparatus for selective dielectrically heating a particulate bed using elongate electrodes

Country of Origin: Germany
Reference Number: TODE20180530001
Publication Date: 30 May 2018

Summary

A German environmental research centre developed a process and apparatus for selective dielectrically heating a particulate bed using elongate electrodes. The invention supports the warming up of soil beds and materials with the help of rod-shaped electrodes. The research centre is looking for partners in the field of remediation practice for validation, optimisation and adaption for to specific needs under technical cooperation agreement and commercial agreement with technical assistance.

Description

The German institution is one of the world’s leading research centres in the field of environmental research, enjoying high social recognition. It demonstrates ways in which a sustainable use of our natural resource base is possible for the benefit of both mankind and the environment.



Remediation of solids, which are contaminated with environmentally harmful substances has gained significance in the last 100 years, not only because of being more widespread, but also because of the increase in the spectrum of pollutants, such as, for example, organic solvents, mineral oil hydrocarbons and herbicides.

Mixed contaminations, for example, from heavy metals and hydrocarbons, which can generally not be treated with only a single remediation method, are particularly problematic. Extracting raw materials such as crude oil from rock formations has to be seen as an essential part in this context.



Remediation of soil beds and other contaminated materials can be thermally promoted by means of different heating methods. Within the process of cleaning soil beds, thermally supported soil vapour extraction and microbial soil bed cleaning have become well-established procedures. However, with the known methods in this field, it is not possible to combine different thermal and non-thermal effects of electromagnetic and electric fields independently of one another and in an optimal status. Furthermore, it is not possible to heat up highly contaminated layers in soil beds and solid material in a spatially selective way or to adapt the procedure during the process.   



The developed technology addresses these knowledge gaps by referring to processes and devices for cleaning soil beds and other contaminated materials with the use of different electrical heating procedures. The objective of the innovation refers to providing a method and a device for influencing biological, chemical and/ or physical parameters, which are important for the treatment of solids. 

The invention aims at specifying a method and an apparatus for spatially selective dielectrical heating and/or cleaning of contaminated soil beds with which a solid bed (e.g. a volume of ground) can be heated selectively and in a targeted manner with the help of rod-shaped electrodes. More specifically, it is anticipated to promote that the injection of electromagnetic waves into the material around the electrodes takes place in a way that certain parts of a ground or solid layer are preferentially heated, while other parts are not heated at all. Preferentially, heating is focused to highly contaminated soil parts in order to accelerate remediation. 



Furthermore, combining two frequencies allows homogenous heating of coexisting saturated and unsaturated zones. 



The RF technology allows the decontamination of a broad spectrum of contaminants, mainly for organic contaminants with boiling temperatures below 200°C, e.g.  volatile halogenated hydrocarbons, aromatic hydrocarbons, BTEX, petroleum-derived hydrocarbons or polycyclic aromatic hydrocarbons.



There are partners sought from industry and research for validation and technology optimisation under technical cooperation agreement and for application in products under commercial agreement with technical assistance.

Advantages and Innovations

The developed method and device is developed for cleaning solid beds and other contaminated materials with the use of different electrical heating methods. 

Especially for in-situ and on-site applications, electrical heating methods have many advantages. For example, no auxiliary means are required, which also become contaminated when passing through the contaminated medium. 

Observing not only ohmic heating (direct voltage or low-frequency application), but also dielectric heating (high-frequency application), all media and temperature ranges of up to 400°c and more are principally accessible. 

There are only a few methods, which are suitable for in-situ volumetric heating of soils and other solid media. While in current methods within this field, the heat transport has to take place over (boundary) surfaces of the soil particles, electrical heating methods provide the advantage of heat production within the soil volume.

The developed process and apparatus provides a tool to focus heating to the desired volume which is usually the contaminated soil fraction. Thus, the method is especially suitable for removal of hot-spot contamination or source treatment.

Stage Of Development

Field tested/evaluated

Stage Of Development Comment

The technology was successfully applied at different sites in Europe together with partners in the framework of third-party funded projects.

Requested partner

There are partners sought from industry and research, active in the field of soil remediation, for validation and technology optimisation under technical cooperation agreement and for application in products under commercial agreement with technical assistance.