Efthymios Kantarelis

Sustainable valorization of plastic wastes for energy with environmental safety via High-Temperature Pyrolysis (HTP) and High-Temperature Steam Gasification (HTSG)

In the present study the energetic valorization of electric cable shredder residues (mixed plastics) has been investigated. Thermochemical conversion by means of High-Temperature Steam Gasification (HTSG) and High-Temperature Pyrolysis (HTP) was studied. The effects of temperature and reaction time--process parameters--were investigated. Comparison of the results showed that HTSG seems a more suitable process in terms of produced syngas quality (64%, v/v and 13MJ/Nm(3)) than HTP because of higher H(2) yield and lower tar content.

Valorization of cotton stalks by fast pyrolysis and fixed bed air gasification for syngas production as precursor of second generation biofuels and sustainable agriculture.

In the present study, the potential of cotton stalks utilization for H(2) and syngas production with respect to CO(2) mitigation, by means of thermochemical conversion (pyrolysis and gasification) was investigated. Pyrolysis was conducted at temperature range of 400-760 degrees C and the main parametric study concerned the effect of temperature on pyrolysis product distribution. Atmospheric pressure, air gasification at 750-950 degrees C for various lambda (0.02-0.07) was also studied. Experimental results showed that high temperature favors gas production in both processes; while low lambda gasification gave high gas yield. Syngas (CO and H(2)) was increased with temperature, while CO(2) followed an opposite trend. By pyrolysis, higher H(2) concentration in the produced gas (approximately 39% v/v) was achieved and at the same time lower amounts of CO(2) produced, compared to air gasification.

Bioenergy production for CO2-mitigation and rural development via valorisation of low value crop residues and their upgrade into energy carriers: a challenge for sunflower and soya residues.

The present study concerns the energetic valorization of sunflower and soya residues by air fixed-bed gasification. The main process parameters that have been investigated were the temperature and air equivalence ratio. Experimental results indicated that the high temperature and air had a positive effect in gas yield for both residues by ensuring mild oxidative conditions. Gasification gas composition showed different trends of H(2)/CO ratio for the two residues at low equivalence ratios. The LHV of the produced gas from both residues varied from 6.84 to 12 MJ/Nm(3). The energy recovery achieved via gasification could reach 0.07 and 0.02 per acre of cultivated area for the sunflower and soya residues, respectively, in terms of tons of oil equivalent. Sunflower shown higher oil production and energy recovery than soya did. The results of the present study indicate the viability of alternative energy production from agricultural biomass by gasification. Such residues could comprise an attractive renewable source of energy for covering additional energy demands in agricultural regions through exploitation in small gasification systems.

Material and Energy Recovery from Waste of Electrical and Electronic Equipment: Status, Challenges, and Opportunities

Material and energy recovery from waste of electrical and electronic equipment status, challenges, and opportunities

Reduction of brominated flame retardants (BFRs) in plastics from waste electrical and electronic equipment (WEEE) by solvent extraction and the influence on their thermal decomposition

Consumption of electronics increases due to modern societys growing needs, which leads to increasing generation of waste electrical and electronic equipment (WEEE). Recycling of WEEE has been a global concern during the last few decades because of the toxic compounds that are produced during recycling. Different recycling techniques have been adapted on a commercial scale in order to overcome this issue, but the recycling of WEEE still lacks the technology to treat different kinds of feedstocks and to maximise the recycling rates. Pyrolysis is an alternative that has not been commercialised yet. One of the challenges for the implementation of this technology is the toxic brominated organic compounds that can be found in the pyrolysis oils. In this study, tetrabromobisphenol A (TBBPA), one of the major flame retardants, is reduced in three different WEEE fractions through solvent extraction as a treatment prior to pyrolysis. Two solvents have been experimentally investigated: isopropanol and toluene, the latter of which can be derived from pyrolysis oil. The results indicate that TBBPA was extracted during pre-treatment. Moreover, the total bromine content of WEEE material was reduced after the treatment with a maximum reduction of 36.5%. The pyrolysis experiments indicate that reduction of several brominated organic compounds was achieved in almost all the tested cases, and two brominated compounds (2,4,6-tribromophenol and 2,5-Dibromobenzo(b)thiophene) reached complete removal. Also, the thermal decomposition behaviour of the raw samples and the treated was investigated, showing that the reduction of TBBPA influences the decomposition by shifting the starting decomposition temperature.

Mechanically Assisted Low-Temperature Pyrolysis of Hydrocarbons

We report experimental setups and conditions leading to pyrolysis (cracking) of such gaseous hydrocarbons as methane, mixed propane and butane, at the temper-atures of the heater below 200oC. The p ...