Thermal conversion of household waste in Ghana using pyrolysis technology; im Projekt: Hybrid Energie aus Abfall als nachhaltige Lösung für Ghana

Abstract

The overarching aim of the project is to develop tailor-made solutions to tackle the problem of waste management as well as power management in particular in Ghana by converting the waste into useful energy. In the sub-project of the SRH Berlin, the pyrolysis technology is being applied and investigated for plastics in household waste. The output of the thermal conversion is pyrolysis oil, syngas and black carbon usable as secondary raw material and energy resources. Scientific results investigating the potential of household waste in Ghana for use as secondary raw materials and energy production have been achieved primarily by the two doctoral students employed in the project. The results have been presented and published at international conferences and in journals, see final report. The developed Pyrolysis system is characterized by the following technical achievements: The entire system was fabricated with stainless-steel material to prevent corrosion and material degradation. The installed system was a container solution that is mobile and easy to start up, the feeding hopper is scalable and was installed just outside the container to allow for easy material feed-in. The selected furnace is a Carbolite/ Gero TS1 12/125/1200 with a maximum temperature of 1200 °C. The auger screw design from 316 stainless steel that was implemented in the pyrolysis unit was found to offer several advantages such as:

feedstock residence time control – this provided for increased feedstock variability and improved process efficiency, the stainless steel alloy utilized for fabrication contributed to high-thermal strength and corrosion resistance, the batch feeding system provided for efficient and continuous loading of the feedstock while eliminating oxygen leak into the process. This state of the art design will guarantee continuous input of the feedstock and a seamless operation of the pyrolysis system, the char extraction batch design also provides for continuous extraction of the char during active operation of the system while inhibiting the penetration of oxygen, the digitally and manually operated variable speed controllers was designed to allow for real-time and adequate optimization of the process based on the feedstock utilized in the process, similarly, the manually operated flowmeter was utilized to ensure flexible and easy optimization of process parameters based on requirement, the single-zone oven heater would ensure uniform temperature distribution along the heated length of the auger. This would be crucial for consistent product quality and was necessary to avoid hot-spots that could lead to coking or undesired reactions, on-site production of nitrogen will ensure constant availability of the inert carrier gas which is required for efficient and uninterrupted pyrolysis process.