Study On Rheological Properties And Combustion Characteristics Of Indonesia Lignite Sludge

Indonesian coal burned by Guohua Indonesia power plant has a moisture content of60%. By using steam tube rotary drying technology, the mixed coal wastewater with a temperature of40～60℃was produced, which become coal sludge which has a moisture of55%, with quantity of10-15t/h. The Indonesia lignite sludge has high moisture, high volatile content and high viscosity, resulting in difficulty in direct use and processing.Firstly, the paper using thermogravimetric-infrared analysis method to analyze pyrolysis and combustion experiments of Indonesia lignite sludge. Experiments show that the heating rate has positive effects on the characteristic temperature and other basic characteristic parameters of pyrolysis and combustion reaction. For the pyrolysis process, linear fitting tends to be a three-step distribution. In the same conversion range, the activation energy has little relation with heating rate; while under the same heating rate, the activation energy increases with the increase of the conversion rate. Different with pyrolysis reaction, kinetics parameters of the combustion reaction fits linearly well in the whole reaction. With heating rate of10℃/min,30℃/min, and50℃/min, the reaction magnitudes are2,1.5and1.5respectively. With the increase of heating rate, combustion activation energy decreases. Infrared analysis showed that pyrolysis components are mainly CO2, CO, and small amounts of aldehyde, ketone, and acid.The article used a screw pump and vertical pipeline loop device for the experiment of the rheological properties of the Indonesia lignite coal slurry, obtained the pressure drop of coal slurry under different flow rate. Calculation of rheological parameters and pipe flow resistance were carried out. Study found out that, Indonesia lignite coal slurry has a property of shear thinning in the test concentration range, which is from43.9%to50%. When the concentration increases from44.7%to45.8%the slurry changed from pseudo-plastic fluid to yield pseudo-plastic fluid. After fitting of the rheological characteristic parameters, we found that τ0、K、n changes in exponential rule with the concentration of slurry. Through contrast experiment with rotational viscometer, we found the characteristics of Indonesia lignite coal slurry flow was in consistent with the pipe flow tests. Because the slurry concentration is smaller in the rotational viscometer, the yield stress was an order of magnitude smaller than the pipe flow yield stress.Finally, the paper performed the combustion and emission tests on a pilot-scaled500×500mm2cycled fluidized boiler. The ignition curve was available under different conditions, and the slurry combustion was stable. Temperature of fluidized bed can reach more than850℃,which was relatively high. Pollutants concentration was lower than the national standard; and the combustion efficiency is very high, which was over98%. Then, the article designed a process to recycle the lignite sludge on an industrial scale. Thermodynamic calculation and type selection were also performed, providing scientific basis for the reuse of Indonesian lignite sludge.