This work aims at demonstrating the feasibility of replacing Indonesian coal (INC) with hydrothermally treated municipal solid waste (MSWH) in cocombustion with high ash Indian coal (IC). The combustion efficiencies and emissions (CO, NO) of MSWH, INC and their blends with IC for a series of tests performed under a range of temperatures and air conditions were tested in a drop-tube reactor (DTR). The results showed the following. The combustion efficiency of IC was increased by blending both MSWH and INC and CO emission was reduced with increasing temperature. For NO emission, the blending of MSWH led to the increase of NO concentration whereas the effects of INC depended on the temperature. The combustion behaviors of IC-MSWH blend were comparable to those of the IC-INC blend indicating it is possible for MSWH to become a good substitute for INC supporting IC combustion. Moreover, the CO emission fell while the NO emission rose with increasing excess air for IC-MSWH blend at 900°C and the highest combustion efficiency was obtained at the excess air of 1.9. The existence of moisture in the cocombustion system of IC-MSWH blend could slightly improve the combustion efficiency, reduce CO, and increase NO. 1. Introduction With the development of human civilization, municipal solid waste (MSW) turns out to be a great threat to the environment. Traditional MSW disposal methods such as open dumping, landfill, or composting are becoming less and less attractive due to less land available around cities and also much more stringent environmental regulations. Thermal treatment as incineration will therefore play an important role as an effective MSW treatment which enjoys the advantages of outstanding reduction in waste volume, thermal destruction of toxic organic constituents, and so forth. However, it is hard to recycle adequate energy from the incineration of MSW with high moisture content, heterogeneous characteristics, and low energy content. Recently, hydrothermal treatment (HT) is regarded to be an effective waste to energy technology for converting MSW into solid fuels with low moisture content, uniform characteristics, and high bulk/energy density [1–5]. On the other hand, we are running out of high-rank coals for power generations so that the utilizations of low-rank coals are inevitable especially in developing countries. For example, Indian coal (IC) is one kind of coal with high ash content which leads to difficulty in ignition and maintenance of flame stabilization, and so forth. In reality, Indonesian coal (INC) is blended with IC in power plants in
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