Quantitative and kinetic TG-FTIR study of biomass residue pyrolysis: Dry distiller's grains with solubles (DDGS) and chicken manure

Abstract

New energy policies all over the world are trying to tackle high oil prices and climate change by promoting the use of biomass to produce heat, electricity and liquid transportation fuels. In this paper we studied two different secondary fuels: dry distiller's grains with solubles (DDGS) and chicken manure. These materials have high content of nitrogen and ashes which limit their usage in thermal applications due to potential excessive NO x emissions and problems of slagging, fouling, corrosion and loss of fluidization. The fuels tested here were received from industrial partners. In order to reduce the ash content the fuels were pre-treated using water leaching pre-treatment. Pyrolysis of these fuels has been monitored through a TG-FTIR set-up. Quantification of the following volatile species was possible: CO, CO 2, CH 4, HCN, NH 3, HNCO, H 2O. The water leaching appeared to decrease the amount of ashes in both samples and remove some of the troublesome compounds like Cl, S and K. The DDGS thermogravimetric curve showed three main peaks at 280 °C, 330 °C and 402 °C with a total weight loss of around 79%wt a.r. (on an “as received” basis). NH 3 is the main N-compound released at low temperatures with a peak at 319 °C. HNCO and HCN were detected at higher temperatures of around 400 °C. Chicken manure reacted in four stages with peaks at 280 °C, 324 °C, 430 °C and 472 °C with a total average weight loss of 66%wt a.r. The main N-compound was HNCO, released at 430 °C. Ammonia was detected during the whole measurement, while HCN presented peaks of reactivity at 430 °C and 472 °C. Kinetic analysis was applied using a distributed activation energy method (DAEM) using discrete and Gaussian distributions and data for further modeling purposes were retrieved and presented.