Abstract
In South Africa, Municipal Solid Waste (MSW) management is a challenge. This is due to a high solid waste generation and this is as due to population growth and urbanization. Chemical Looping Combustion (CLC) of MSW could serve as a potential treatment for the disposal of MSW and the recovery of energy because it can inhibit dioxins and furans formation that is associated with the traditional treatment (incineration). However, there is a need to determine the optimum ratio of paper and plastics in MSW that is required in the chemical looping combustion of MSW to meet an equivalent energy load with the lowest CO 2 emission scenario. This research evaluated the CLC of MSW composition (Paper + Plastics) at different ratios of 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1 using Chemcad® process simulation software. Ratio 0 means only paper and 1 means only plastics and ratios 0.2 to 0.8 means blend of paper and plastics. The process simulation was done for two different CLC processes namely Chemical Looping Oxygen Uncoupling (CLOU) and In-situ Gasification CLC (IG-CLC) and the results compared with South African coal. Plastic samples used include Polyvinyl chloride (PVC), High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), Polyethylene Terephthalate (PET), Polystyrene (PS) and Polypropylene (PP). The results showed a promising CO2 gas yield (higher degree of CO2 capture) with the IG-CLC process having higher CO2 gas yield than the CLOU process for the paper and plastic sample and the paper/plastic blends. This indicates CO2 gas yield was higher in IG-CLC than CLOU and presents a better opportunity for CO2 capture in IGCLC than CLOU. The optimum CO2 gas yield for the paper/plastic blend was at ratio 0.2 for all the different types of plastics for CLOU. For IG-CLC all the paper/plastic blends have the same CO2 yield. For combustion efficiency, the CLOU process was marginally higher than the IG-CLC process for all the plastics and the paper. A different trend was observed with the blends (paper and plastics) with the IG-CLC process having higher combustion efficiency than the CLOU process. The optimum combustion efficiency of paper/PVC, paper/PET, paper/LDPE, paper/HDPE, paper/PP and paper/PS was at a ratio of 0.5, 0.8, 0.4, 0.4, 0.4 and 0.4 respectively for both processes. The carbon conversion was the same for both processes. Paper, PVC, and PET had 100% carbon conversion and the remaining plastics (LDPE, HDPE, PP, and PS) having a conversion between...
M.Tech. (Chemical Engineering)