Emission Spectroscopy of CH₄/CO₂ Mixtures Processed in a Non-Thermal Plasma Augmented Burner

The need for energy resources that do not belong to the group of fossil fuels and a wide availability of various low-calorific gases leads humanity to search for solutions to adapt external sources of force that would allow for the use of these resources. One of such solutions is the usage of non-thermal plasma applications for pre-ignition stage, ignition, and, finally, combustion. Plasma assistance is a promising technology for improving processes of ignition and flame stabilization, as well as propagating flame speed. This study focuses on influence of the non-thermal plasma on both for CH4, CO2 gases, and their mixture in pre-ignition stage by performing emission spectroscopy, and determining tendency of excited species at different frequency rates for optimal plasma parameters to reduce NO formation and increase efficiency during combustion. The results obtained exhibit a non-linear dependence of radical’s emission from the frequency of plasma. As an example of possible profits from correctly choosing plasma parameters, the calorific value of gases increased from 2.86 times for BG25/75 to 4.78 times for BG30/70. However, the decomposition on higher frequencies causes higher rates of nitrogen-bands emissions, which would increase NOx emissions in the combustion process

An Intensification of Biomass and Waste Char Gasification in a Gasifier

Gasification is considered a clean and effective way to convert low quality biomass to higher value gas and solve various waste utilization problems as well. However, only 80% of biomass is converted through thermal processes. The remaining part is char, which requires more time for conversion and in that case reduces the efficiency of gasifier. Seeking to optimize the process of gasification, this work focuses on the intensification of residual char gasification in a gasifier. For this purpose, three different types of char prepared from wood, sewage sludge and tire were examined under different conditions in a lab-scale gasification setup. Results showed that the air flux increase from 0.11 kg/(m2s) to 0.32 kg/(m2s) intensified the gasification process and the gasification rate increased from 0.8 to 2.61 g/min with the decrease of duration of wood char gasification by 72%. An additional introduction of pyrolysis gas into the char gasifier led to decreased bed temperatures, but the gasification rate increased from 0.8 to 1.25 g/min and from 2.61 g/min to 2.83 g/min, respectively, for the wood char and the sewage sludge char. Moreover, the use of pyrolysis gas coupled with air as the gasifying agent enhanced the composition of produced gas from char, and the CO2 concentration decreased by 1.68 vol% while the H2 concentration increased by 2.8 vol%

Techno-Economic Analysis of Thermochemical Conversion of Waste Masks Generated in the EU during COVID-19 Pandemic into Energy Products

During the COVID-19 pandemic, more than 24 billion pieces of surgical mask waste (WM) were generated in the EU region, with an acute shortage of their management and recycling. Pyrolysis and gasification are among the most promising treatments that were proposed to dispose of WMs and convert them into pyrolysis oil and hydrogen-rich syngas. This work aimed to investigate the techno-economic analysis (TEA) of both treatments in order to assess the feasibility of scaling up. The TEA was carried out using a discounted cash flow model and its data were collected from practical experiments conducted using a fluidised bed pyrolysis reactor and bubbling fluidised bed gasifier system with a capacity of 0.2 kg/h and 1 kg/h, respectively, then upscaling to one tonne/h. The technological evaluation was made based on the optimal conditions that could produce the maximum amount of pyrolysis oil (42.3%) and hydrogen-rich syngas (89.7%). These treatments were also compared to the incineration of WMs as a commercial solution. The discounted payback, simple payback, net present value (NPV), production cost, and internal rate of return (IRR) were the main indicators used in the economic feasibility analysis. Sensitivity analysis was performed using SimLab software with the help of Monte Carlo simulations. The results showed that the production cost of the main variables was estimated at 45.4 EUR/t (gate fee), 71.7 EUR/MWh (electricity), 30.5 EUR/MWh (heat), 356 EUR/t (oil), 221 EUR/t (gaseous), 237 EUR/t (char), and 257 EUR/t (syngas). Meanwhile, the IRR results showed that gasification (12.51%) and incineration (7.56%) have better economic performance, while pyrolysis can produce less revenue (1.73%). Based on the TEA results, it is highly recommended to use the gasification process to treat WMs, yielding higher revenue

Fabrication and characterization of environmentally friendly biochar anode

Electrical power generation by means of electrochemical systems utilizing wastewaters is a global energy challenge tackling technique for which a creation of novel eco-friendly electrode materials is in high relevance. For this purpose a Rhodophyta algae derived activated biochar anode bound with a flaxseeds mucilage binder (5, 10, 20, 30 wt.%) was formed and characterized by thermogravimetric, Brunauer-Emmett-Teller (BET) analysis as well as conductivity and mechanical resistance determination. Activation technique with KOH prior to carbonization at 800 °C of algae was employed to obtain biocarbon with a large surface area. The highest specific surface area of 1298.49 m2/g was obtained with the binder-free sample and had a tendency to decrease with the increase of the binder content. It was estimated that biochar anodes are thermally stable at the temperature of up to 200 °C regardless of binder concentration. The concentration of the binder on the other hand had a significant influence in anodes mechanical resistance and electrical conductance: anode with 30 wt.% of the binder had the highest compressive strength equal to 104 bar; however, the highest conductivity was estimated in anode with 5 wt.% of the binder equal to 58 S/m. It is concluded that anode with 10 wt.% mucilage binder has the optimal properties necessary in MFC utilization

Investigation of Waste Biogas Flame Stability Under Oxygen or Hydrogen-Enriched Conditions

Increasing production rates of the biomethane lead to increased generation of waste biogases. These gases should be utilized on-site to avoid pollutant emissions to the atmosphere. This study presents a flexible swirl burner (~100 kW) with an adiabatic chamber capable of burning unstable composition waste biogases. The main combustion parameters and chemiluminescence emission spectrums were examined by burning waste biogases containing from 5 to 30 vol% of CH4 in CO2 under air, O2-enriched atmosphere, or with the addition of hydrogen. The tested burner ensured stable combustion of waste biogases with CH4 content not less than 20 vol%. The addition of up to 5 vol% of H2 expanded flammability limits, and stable combustion of the mixtures with CH4 content of 15 vol% was achieved. The burner flexibility to work under O2-enriched air conditions showed more promising results, and the flammability limit was expanded up to 5 vol% of CH4 in CO2. However, the combustion under O2-enriched conditions led to increased NOx emissions (up to 1100 ppm). Besides, based on chemiluminescence emission spectrums, a linear correlation between the spectral intensity ratio of OH* and CH* (IOH*/ICH*) and CH4 content in CO2 was presented, which predicts blow-off limits burning waste biogases under different H2 or O2 enrichments

Investigation of Optimal Temperature for Thermal Catalytic Conversion of Marine Biomass for Recovery of Higher-Added-Value Energy Products

The eutrophication process, caused by the uncollected seaweed and macroalgae, is a relevant and ongoing ecological issue. In case this biomass is collected from the seashores, it could be used as a potential feedstock for recovery of higher-added-value energy products. This paper aims to investigate the seaweed perspective of uses as a potential feedstock in the slow-pyrolysis process, using microthermal analysis combined with Fourier transform infrared spectrometry and experiments at the laboratory scale at different temperatures with two different types of zeolite catalysts. The primary investigation was performed using a micro-thermal analyser, and the results revealed that seaweed thermally decomposes in two stages, at 250 and 700 °C, while the catalyst slightly decreased the activation energy required for the process, lowering the temperatures of decomposition. Experiments on a laboratory scale showed that the most common compounds in the gaseous phase are CnHm, H2, CO, and CO2. Nevertheless, the most abundant liquid fraction derivatives are substituted phenolic compounds, pyridine, benzoic acid, naphthalene, d-glucopyranose, and d-allose. Furthermore, the catalyst decreased the amount of higher molecular mass compounds, converting them to toluene (71%), which makes this technology more attractive from the recovery of higher-added-value products point of view

Pyrolysis Kinetic Behaviour of Glass Fibre-Reinforced Epoxy Resin Composites Using Linear and Nonlinear Isoconversional Methods

Due to the increasing demand for glass fibre-reinforced epoxy resin composites (GFRC), huge amounts of GFRC waste are produced annually in different sizes and shapes, which may affect its thermal and chemical decomposition using pyrolysis technology. In this context, this research aims to study the effect of mechanical pre-treatment on the pyrolysis behaviour of GFRC and its pyrolysis kinetic. The experiments were started with the fabrication of GFRC panels using the vacuum-assisted resin transfer method followed by crushing the prepared panels using ball milling, thus preparing the milled GFRC with uniform shape and size. The elemental, proximate, and morphology properties of the panels and milled GFRC were studied. The thermal and chemical decomposition of the milled GFRC was studied using thermogravimetric coupled with Fourier-transform infrared spectroscopy (TG-FTIR) at different heating rates. Meanwhile, the volatile products were examined using TG coupled with gas chromatography–mass spectrometry (GC-MS). The TG-FTIR and TG-GC-MS experiments were performed separately. Linear (Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Friedman) and nonlinear (Vyazovkin and Cai) isoconversional methods were used to determine the pyrolysis kinetic of the milled GFRC based on thermogravimetry and differential thermal gravimetry (TG/DTG). In addition, the TG/DTG data of the milled GFRC were fitting using the distributed activation energy model and the independent parallel reactions kinetic model. The TG results showed that GFRC can decompose in three stages, and the main decomposition is located in the range 256–500 °C. On the other hand, aromatic benzene and a C-H bond were the major functional groups in the released volatile components in FTIR spectra, while phenol (27%), phenol,4-(1-methylethyl) (40%), and p-isopropenylphenol (34%) were the major compounds in GC-MS analysis. Whereas, the kinetic results showed that both isoconversional methods can be used to determine activation energies, which were estimated 165 KJ/mol (KAS), 193 KJ/mol (FWO), 180 KJ/mol (Friedman), 177 KJ/mol (Vyazovkin), and 174 KJ/mol (Cai)

Catalytic Pyrolysis Kinetic Behavior and TG-FTIR-GC–MS Analysis of Metallized Food Packaging Plastics with Different Concentrations of ZSM-5 Zeolite Catalyst

Recently, the pyrolysis process has been adapted as a sustainable strategy to convert metallized food packaging plastics waste (MFPW) into energy products (paraffin wax, biogas, and carbon black particles) and to recover aluminum. Usually, catalysts are used in pyrolysis treatment to refine pyrolysis products and to increase their yield. In order to study the effect of a catalyst on the formulated volatile products, this work aims to study the pyrolysis behavior of MFPW in presence of catalyst, using TG-FTIR-GC–MS system. The pyrolysis experiments were conducted with ZSM-5 Zeolite catalyst with different concentrations (10, 30, and 50 wt.%) at different heating rates (5, 10, 15, 20, 25, and 30 °C/min). In addition, TG-FTIR system and GC-MS unit were used to observe and analyze the thermal and chemical degradation of the obtained volatile compounds at maximum decomposition peaks. In addition, the kinetic results of catalytic pyrolysis of ZSM-5/MFPW samples matched when model-free methods, a distributed activation energy model (DAEM), and an independent parallel reaction kinetic model (IPR) were used. The TGA-DTG results showed that addition of a catalyst did not have a significant effect on the features of the TGA-DTG curves with similar weight loss of 87–90 wt.% (without taking the weight of the catalyst into account). Meanwhile, FTIR results manifested strong presence of methane and high-intensity functional group of carboxylic acid residues, especially at high concentration of ZSM-5 and high heating rates. Likewise, GC-MS measurements showed that Benzene, Toluene, Hexane, p-Xylene, etc. compounds (main flammable liquid compounds in petroleum oil) generated catalysts exceeding 50%. Finally, pyrolysis kinetics showed that the whole activation energies of catalytic pyrolysis process of MFPW were estimated at 289 kJ/mol and 110, 350, and 174 kJ/mol for ZSM-5/MFPW samples (10, 30, and 50 wt.%, respectively), whereas DAEM and IPR approaches succeeded to simulate TGA and DTG profiles with deviations below <1