An Investigation on Co-Combustion Behaviors of Hydrothermally Treated Municipal Solid Waste With Coal Using a Drop Tube Reactor

Liang Lu,Kunio Yoshikawa,Marco J Castaldi,Yuqi Jin,Masato R Nakamura

doi:10.1115/power2011-55353

Liang Lu, Kunio Yoshikawa + Show 3 more

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https://doi.org/10.1115/power2011-55353

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Abstract

This work aims at demonstrating the feasibility of replacing Indonesian coal (INC) with hydrothermally treated municipal solid waste (MSWH) in co-combustion with high ash Indian coal (IC). Combustion behaviors of MSWH, INC and their blends with IC were tested in a laboratory-scale drop tube reactor (DTR). The combustion efficiency and emissions such as CO, NO for a series of tests performed under a range of temperatures and air conditions were evaluated and the main results derived from this study can be concluded as the followings: the combustion efficiency of IC is increased by blending both MSWH and INC and CO emission is reduced in the meanwhile with the temperature rising. With regards to NO emission, the blending of MSWH leads to the increase of NO emission whereas the blending of INC results in either the increase or decrease of NO emission compared with IC only combustion depending on the temperature. The combustion behaviors of IC-MSWH blend are comparable to that of the IC-INC blend indicating it is possible for MSWH to become a good substitute for INC in the co-combustion with IC. The CO emission falls while the NO emission rises with the increase of the excess air in the case of IC-MSWH blend at 900 °C and the highest combustion efficiency is obtained at the excess air of 1.9. The existence of moisture in the co-combustion system of IC-MSWH blend can slightly improve the combustion efficiency, reduce CO emission and increase NO emission. The results of this work are expected to be a good instruction for the application of MSWH for co-combustion with coal.

Highlights

With the development of human civilization, municipal solid waste (MSW) turns out to be a great threat to the environment
At lower temperature (800◦C), the temperature and the other factors such as oxygen diffusion might come to play important roles on the combustion especially in the case of Indonesian coal (INC) whose η at 800◦C was extremely low compared to the others indicating that the high content of volatile matter (VM) of INC might discourage the diffusion of air which prohibits the oxygen from reaching the fixed carbon (FC)
MSWH contained much more VM than INC, its η at 800◦C was still well controlled by the temperature because the burning of VM was mainly responsible for the combustion of MSWH whereas on the other hand in the case of coal, the combustion of FC dominated

Summary

Introduction

With the development of human civilization, municipal solid waste (MSW) turns out to be a great threat to the environment. Thermal treatment as incineration will 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. It is hard to recycle adequate energy from the incineration of MSW with high moisture content, heterogeneous characteristics, and low energy content. 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 [1,2,3,4,5]. We are running out of high-rank coals for power generations so that the utilizations of lowrank coals are inevitable especially in developing countries. Experiments were carried out with thermogravimetric analysis (TGA) and the results proved that hydrothermally treated MSW (MSWH) has the capability to promote the combustion of low-quality IC and Journal of Combustion

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