Effects of biodegradable- and non-biodegradable-rich waste separation on ash deposition behaviour during coal and refuse-derived fuel co-combustion.

The potential impact of ash deposition during the combustion of separated biodegradable- and non-biodegradable-rich waste of refuse-derived fuel (RDF) was evaluated in this study. Theoretical prediction, drop tube furnace experimental combustion, and ash observation were performed to comprehensively investigate their ash deposit behaviour. The results show that high CaO and Cl in RDFs result in severe sintering and rust in the metal surface. The high ash deposit weight and aggregated sticky particles are observed during single-firing RDFs. Furthermore, adding 5 wt% of biodegradable-rich RDF or mixed RDF to coal has a less significant effect on ash deposition. However, several aggregate particles and metal degradation are observed during the combustion of mixed coal with the addition of 5 wt% non-biodegradable-rich RDF. The high Cl in non-biodegradable-rich RDF affects the ash deposition behaviour significantly. This research provides valuable insights into optimising coal-RDF co-combustion, especially with separating biodegradable- and non-biodegradable-rich RDFs.

Investigation on combustion characteristics and ash-related issues of Calliandra calothyrsus and Gliricidia sepium using thermogravimetric analysis and drop tube furnace.

Calliandra calothyrsus and Gliricidia sepium are developed as wood energy forest plantations in degraded land. They have good survivability, are fast to be harvested, and have good calorific value to be utilized as biomass fuel. This study aims to investigate their combustion characteristics by thermogravimetric analysis and their ash-related issues by combustion experiments in drop tube furnace and ash observation. The results show that G. sepium has a better combustion performance with higher values of ignition index, comprehensive combustion index, and flammability index, while C. calothyrsus shows better ash-related issues with less risk in theoretical slagging prediction, clearer metal surface in the fouling area, and less ash deposit formation. The domination of K, Ca, and S elements in the ash deposits of both biomasses results in several sticky aggregate particles and low-melting minerals. This study provides an in-depth understanding of C. calothyrsus and G. sepium combustion for broader utilization.