10 PLASMA GASIFICATION
The Upgrading of Human Waste Materials to Syngas
Microwave generated plasma gasiďŹ cation
Syngas conversion
The TU Delft approach of waste treatment centres on small-scale gasification by means of a microwave generated plasma. By applying energy in this form, lower residence times are required and heat losses can be compensated for, so that processing facilities can be scaled down considerably, enabling decentralized treatment.
Very intense processing conditions can be reached under plasma. High temperatures and the occurrence of highly reactive radicals accelerate the destruction of waste materials, converting them into syngas, which can be used as a raw material in chemical processing or as a source of energy. As compared to more conventional thermal gasification, plasma gasification in principle can provide a more robust and flexible process to generate a higher quality product.
Eiciency
Syngas production testbed
The process was investigated with a series of short duration, continuous flow experiments. Biomass was fed into the plasma zone of the reactor where it was converted into fuel gas. An energy recovery of 184% at a feedstock conversion of ~20% was observed. The results indicate that a tailored reactor that reaches full conversion will provide much higher energy recovery.
To demonstrate the feasibility of self-sustained, continuous waste destruction, an experimental plasma gasification unit has been built and incorporated in our waste treatment miniplant. Stable operation and continuous syngas production have been demonstrated; research into understanding and optimizing the process are ongoing. In a following stage the setup will serve as a testbed for tailored plasma reactor designs.
Next steps Increase performance by either using a secondary radio plasma generator at a lower frequency that is in the radio wave spectrum or by replacing the current generator for a lower frequency version. Both solutions employ longer wavelengths, therefore both solutions enable a more flexible process with a wider operating window in terms of throughput and residence time.
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