Characterization of Fast Pyrolysis of Dry Distiller’s Grains (DDGS) and Palm Kernel Cake Using a Heated Foil Reactor: Nitrogen Chemistry and Basic Reactor Modeling

Abstract

In this paper, two residues of liquid biofuels production were tested: dry distiller’s grains with solubles and palm kernel cake. The fuels were tested in a heated foil reactor inserted in a Fourier Transform Infrared spectrometer under fast pyrolysis conditions: a heating rate of 600 °C/s and final temperatures ranging from 500 to 1300 °C. The fuels were also pretreated by water leaching to remove water-soluble inorganic compounds. A numerical model of the unloaded system was developed to gain better insight into the temperature and velocity profiles in the reactor and on the foil. The model allowed the detection of zones of high temperature and low velocity around the hot foil, indicating that secondary reactions are likely. Moreover, temperature validation with an InfraRed pyrometer indicated that the temperature measured by the control thermocouple is on average about 15% (in °C) lower than the actual foil temperature. The product composition and final yields of volatile species were measured at different final temperatures. The main volatile species was CO2 for temperatures lower than 1000 °C. At higher temperatures CO became the most abundant volatile species, likely because of tar cracking. HCN resulted to be the main volatile-N compound for all samples at all temperatures, while NH3 was detected in minor amounts. The mechanism of decomposition of proteins seems to have changed from deamination, at slow heating rates, to dehydration, followed by the formation of cyclic amides. These structures were released as tar-N and subsequently decomposed into HCN and NH3. The effect of the leaching was not relevant for weight loss and main species release, but it appeared to enhance tar-N decomposition for the DDGS sample.

Comprehensive Research on the Influence of Nonlignocellulosic Components on the Pyrolysis Behavior of Chinese Distiller’s Grain

“…Branca et al 10 studied the pyrolysis kinetics of DG by thermogravimetric analysis (TGA) and found that DG had lower activation energy than lignocellulose. Yao et al 11 and Giuntoli et al 12 studied the pyrolysis behavior of DG by rapid pyrolysis and found that pyrolyzing DG could easily produce pyrolysis oil.…”

Optimization of the Pyrolysis of Distillers Dried Grains with Solubles

“…The feasibility of using ethanol coproducts to provide energy for a 190 million L/y and a 380 million L/y dry grind ethanol plant was examined, and even if all the DDGS at each plant was used to generate process heat and energy for the facility, there would still be leftover energy which could be sold to the grid, increasing the rate of return on investment for the facility (Tiffany et al, 2007). This energy can be harvested from DDGS directly, by converting it to heat and power, or it can be converted into gaseous or liquid fuels to be used for energy production (Giuntoli et al, 2011). These conversions would most likely require some type of thermochemical conversion process, such as combustion, pyrolysis, or gasification (Wang et al, 2007).…”

Rotary kiln pyrolysis of straw and fermentation residues in a 3MW pilot plant – Influence of pyrolysis temperature on pyrolysis product performance

“…If a produced batch does not fulfill these regulations, it cannot be sold as an animal feed and has to be disposed, for example in a municipal waste combustor. Pyrolysis of DDGS has been investigated also by [19,20] with a focus on the high nitrogen content of this special fuel.…”