Emission characteristics of flue gas during the chemical-looping combustion process for multi-component solid waste

Abstract

Solid waste has interactions with its flue-gas products during combustion, which offers the possibility of regulating its pollutant emissions. Especially, these interaction pathways would be clearer under anaerobic conditions when the chemical-looping combustion (CLC) process is used. The CLC experiments of multi-component solid waste were conducted on a homemade twin-bed reactor and the characteristics of flue gas were investigated for the effect of the mixing ratio of sewage sludge and polyvinyl chloride (PVC). The results indicated that the combustion efficiency was >99.9% for these CLC processes; the highest carbon-conversion rate was obtained at 96.3% for PVC with 60% sludge. The highest NO and SO2 emissions were 26% and 19%, respectively, when the sludge was mixed with 20% PVC. As the proportion of PVC blended into the sludge increased, the time when the concentration of NO in the flue-gas peaks moved backwards, while peak SO2 concentration moved forward. The general trend was to increase first and then decrease. In addition, there were multiple peaks in carbon emissions, corresponding to ~10%, 30% and ~70% of the carbon-conversion rate; nitrogen emissions reached 90% of total emissions before the carbon-conversion rate was 40%; sulphur emissions had a longer cycle and were mainly emitted between 10% and 60% of the carbon-conversion rate. The results are expected to provide a reference for solid-waste source suppressing to inhibit the generation of pollutants.