Optimization of hydrogen and syngas production from PKS gasification by using coal bottom ash

Experimental Study of the Effect of CO/H2 Ratio and Release Pressure on Syngas Jet Flame Propagation and Overpressure

Syngas, composed of hydrogen and carbon monoxide, serves as an alternative fuel for hydrogen energy and a key raw material for chemical synthesis. However, due to its flammable nature, syngas poses risks of forming explosive mixtures in the event of a leak. This study explores potential accident scenarios in coal chemical environments involving syngas reaction vessels. Experimental investigations focus on the overpressure and propagation dynamics of jet flames resulting from syngas leakage, with CO volume fractions ranging from 50 to 80% and release pressures between 2 and 5 MPa. Results reveal that maximum flame overpressure occurs within a CO volume fraction range of 55-65%, with no consistent relationship observed between overpressure and CO fraction at fixed release pressures. During our experiments, the maximum recorded overpressure of 28.4 kPa was reached during vented explosions. Additionally, ignition outcomes categorize into three types based on flame propagation speed: combustion/flare, resembling normal deflagration; and high-velocity deflagration, characterized by rapid propagation and potential for steady jet fire formation. While shockwave-like features may be observed, these do not indicate true detonation. These findings offer insights for the safe handling and storage of syngas.

Optimization of syngas production from co-gasification of palm oil decanter cake and alum sludge: An RSM approach with char characterization

The study explores co-gasification of palm oil decanter cake and alum sludge, investigating the correlation between input variables and syngas production. Operating variables, including temperature (700-900 °C), air flow rate (10-30 mL/min), and particle size (0.25-2 mm), were optimized to maximize syngas production using air as the gasification agent in a fixed bed horizontal tube furnace reactor. Response Surface Methodology with the Box-Behnken design was used employed for optimization. Fourier Transformed Infra-Red (FTIR) and Field Emission Scanning Electron Microscopic (FESEM) analyses were used to analyze the char residue. The results showed that temperature and particle size have positive effects, while air flow rate has a negative effect on the syngas yield. The optimal CO + H2 composition of 39.48 vol% was achieved at 900 °C, 10 mL/min air flow rate, and 2 mm particle size. FTIR analysis confirmed the absence of C─Cl bonds and the emergence of Si─O bonds in the optimized char residue, distinguishing it from the raw sample. FESEM analysis revealed a rich porous structure in the optimized char residue, with the presence of calcium carbonate (CaCO3) and aluminosilicates. These findings provide valuable insights for sustainable energy production from biomass wastes.

A Critical Review of Data Science Applications in Resource Recovery and Carbon Capture from Organic Waste

Municipal and agricultural organic waste can be treated to recover energy, nutrients, and carbon through resource recovery and carbon capture (RRCC) technologies such as anaerobic digestion, struvite precipitation, and pyrolysis. Data science could benefit such technologies by improving their efficiency through data-driven process modeling along with reducing environmental and economic burdens via life cycle assessment (LCA) and techno-economic analysis (TEA), respectively. We critically reviewed 616 peer-reviewed articles on the use of data science in RRCC published during 2002-2022. Although applications of machine learning (ML) methods have drastically increased over time for modeling RRCC technologies, the reviewed studies exhibited significant knowledge gaps at various model development stages. In terms of sustainability, an increasing number of studies included LCA with TEA to quantify both environmental and economic impacts of RRCC. Integration of ML methods with LCA and TEA has the potential to cost-effectively investigate the trade-off between efficiency and sustainability of RRCC, although the literature lacked such integration of techniques. Therefore, we propose an integrated data science framework to inform efficient and sustainable RRCC from organic waste based on the review. Overall, the findings from this review can inform practitioners about the effective utilization of various data science methods for real-world implementation of RRCC technologies.

Optimization of thermal-alkaline pretreatment for dewatering of excess sludge followed by thermal/persulfate oxidation for the elimination of extracellular ARGs in TAP-treated filtrate

This study evaluated the dewatering of excess sludge and the removal of extracellular antibiotic-resistant genes (eARGs) from the treated filtrate by thermal-alkaline pretreatment (TAP) and thermal/persulfate (PS). The optimization of TAP and thermal/PS was investigated during excess sludge dewatering and removal of eARGs via response surface methodology (RSM). The results demonstrated that TAP could effectively decrease the water content of excess sludge (41%) at optimum operating conditions (such as temperature: 88 °C, operation time: 90 min, pH: 11.2). However, the increase in eARGs abundance in TAP-treated filtrate is probably due to the dissolved effluent of the intracellular matter during dewatering. Therefore, TAP-treated filtrate was subjected to thermal/PS, and the removal of eARGs after TAP was explored. The desirability function was used to optimize two kinds of removal efficiencies of eARGs, simultaneously. The optimal pH, persulfate concentration, and reaction temperature were 10.2, 0.039 M, and 75.12 °C, respectively. 6.28 log·copies/mL of tetA and 6.57 log·copies/mL of sulI were removed under the above-mentioned conditions. The process provided efficient dewatering of excess sludge and elimination of eARGs from the filtrate.

Combustion and Emission Characteristics of Gasoline Engine Blended Combustion Syngas

It is an effective way to introduce syngas fuel into gasoline engine for blending combustion to improve combustion and reduce emissions. In this paper, the combustion and emission characteristics of the direct injection engine under the condition of mixed combustion of syngas were analyzed by a numerical simulation method. The engine ran at 2000 rpm, and the mass fraction of syngas was from 0 to 20%. The results showed that with the increase in the mass ratio of syngas in the dual fuel, the average pressure and temperature in the cylinder increased first and then decreased. The maximum in-cylinder pressure and in-cylinder temperature increased by 27.5 and 2.97%, respectively. The instantaneous heat release rate also showed a law of first increasing and then decreasing, in which the peak value of the instantaneous heat release rate increased by 32.1% at the highest. In addition, with the increase in the ratio of syngas, the emission of nitrogen oxides in the cylinder gradually decreased, with a maximum reduction of 27.4%. The unburned hydrocarbons first decreased and then increased, with a maximum reduction of 7.6%. Meanwhile, the emission of carbon dioxide was negatively correlated with the ratio of syngas in the dual fuel. With the increase in hydrogen ratio in syngas, the carbon monoxide was gradually reduced, with a maximum reduction of 65%. The carbon dioxide increased first and then decreased, with a maximum addition of 4.8%. The ratio of hydrogen and carbon monoxide in syngas had little effect on the emission of unburned hydrocarbons.

Flame Propagation Characteristics of Syngas-Air in the Hele-Shaw Duct with Different Equivalence Ratios and Ignition Positions

In this paper, the effects of different ignition positions and equivalence ratios on the explosion characteristics of syngas in a half-open Hele-Shaw duct were investigated. The ignition points are set at distances of 0 and 500 mm from the closed end. Moreover, the research range of equivalence ratio is 0.8-1.2. The experimental results indicate that different ignition positions and equivalence ratios influence the flame front structure and the dynamic characteristics of flame propagation. When the ignition position is at the closed end, the flame front undergoes several typical propagation stages before eventually reaching the open end of the duct. The time required by the flame to reach the open end decreases as the equivalence ratio increases. Meanwhile, when the ignition is in the middle of the duct, the flame simultaneously spreads to the open and closed ends. The time required to reach both sides decreases with the increase in the equivalence ratio. The flame front structure and pressure are primarily affected by the ignition position and the equivalence ratio. At the same ignition position, flame propagation velocity and maximum overpressure increase with the equivalence ratio. The pressure oscillation becomes more intense when the ignition position is close to the open end. At IP₅₀₀, when the equivalence ratio is 0.8, multiple finger-shaped flame fronts emerge, accompanied by high-frequency flame oscillations. This study can provide guidance for the study of the flame propagation characteristics of syngas in millimeter-scale burners.

Effect of biomedical waste co-feeding in the steam gasification of Indian palm kernel shell in fluidized bed gasifier

Gasification is the thermo-chemical process that converts biomass into producer gas which is used for various applications like heat production, electricity, and hydrocarbon synthesis. In this present work, the steam gasification of biomedical waste such as glucose plastic bottle, syringe, and Indian palm kernel shell is gasified in fluidized bed gasifier. The mixture of palm kernel shell co-feeding with biomedical waste such as 100% palm kernel shell (PKS), 25% biomedical waste (BMW), 50% biomedical waste, and 100% biomedical waste using olivine as a primary catalyst is used. The influences of co-feeding of biomedical waste with palm kernel shell on the gas yield, char yield, tar yield, carbon conversion efficiency, tar composition, and gas composition are investigated. The co-feeding of biomedical waste with palm kernel shell for steam/feedstock mass ratio of 1, the tar content is decreased from 53.56 to 3.6 gNm^-3 and the char is reduced from 4.9 to 0.4 wt %. Heterocyclic, heavy polycyclic aromatic hydrocarbons and light aromatic compounds are reducing when compared to that of light polycyclic aromatic hydrocarbons at temperature 900 °C. The value of carbon conversion efficiency also increases for palm kernel shell is 78.7% and for biomedical waste is 98% respectively. Hence, the scope of the present study is to optimize the process parameters for the taken feedstock with respect to our environmental condition with the help of lab scale reactors. Later scale up can be done to utilize the product for practical applications.

A generic input-output approach in developing and optimizing an Aspen plus steam-gasification model for biomass

Steam-gasification is drawing great interests as it yields higher H₂ in syngas than any other gasification process. In this article, an equilibrium steam-gasification model developed in Aspen plus has been presented. The effect of the major input variables along with their synchronized effects on the response variables i.e., cold gas efficiency (CGE) and lower heating value (LHV) have been performed. Steam-gasification process optimization has been carried out employing response surface methodology (RSM) considering wide variety of biomass to get the best possible outcomes. The generic relations for both CGE and LHV as response variables have also been framed from obtained individual relations to estimate the response variables for considered biomass feeds at optimum operating conditions. The analysis reveals that the optimum response is obtained having almost 100% desirability (D) at the optimum operating condition (steam to biomass ratio of 0.7 and gasification temperature between 780 and 790 °C) of the steam-gasification model.

Sectoral-based CO2 emissions of Pakistan: a novel Grey Relation Analysis (GRA) approach

Global warming regarded as the major global issue over the past few decades, whereas carbon dioxide (CO₂) emissions have been cited as one of the main causes of this problem. Therefore, this study aims to investigate the effect of energy consumption, economic development, and population growth on high CO₂ emitting sectors of Pakistan such as transportation, industrial, and household. The data used in this study was taken from multiple databases from 2000 to 2018. We employed novel grey relational analysis (GRA) models to assess the connection between gross domestic product (GDP) per capita, population, energy consumption, and CO₂ emission. Furthermore, the Hurwicz method was used to analyze which factor contributing more to CO₂ emission. Result reveals that CO₂ emission, gross domestic product per capita, population, and energy consumption showed a strong association among all sectors. Whereas, population contributes more to intensifying CO₂ emissions in the transportation sector of Pakistan. This study provides useful insights for policymakers to take preventive and corrective measures to overcome CO₂ emissions as well as sustainable development.

Improving the environmental impact of palm kernel shell through maximizing its production of hydrogen and syngas using advanced artificial intelligence

Fossil fuel depletion and the environmental concerns have been under discussion for energy production for many years and finding new and renewable energy sources became a must. Biomass is considered as a net zero CO₂ energy source. Gasification of biomass for H₂ and syngas production is an attractive process. The main target of this research is to improve the production of hydrogen and syngas from palm kernel shell (PKS) steam gasification through defining the optimal operating parameters' using a modern optimization algorithm. To predict the gaseous outputs, two PKS models were built using fuzzy logic based on the experimental data sets. A radial movement optimizer (RMO) was applied to determine the system's optimal operating parameters. During the optimization process, the decision variables were represented by four different operating parameters. These parameters include; temperature, particle size, CaO/biomass ratio and coal bottom ash (CBA) with their operating ranges of (650-750 °C), (0.5-1 mm), (0.5-2) and wt% (0.02-0.10), respectively. The individual and interactive effects of different combinations were investigated on the production of H₂ and syngas yield. The optimized results were compared with experimental data and results obtained from Response Surface Methodology (RSM) reported in literature. The obtained optimal values of the operating parameters through RMO were found 722 °C, 0.92 mm, 1.72 and 0.06 wt% for the temperature, particle size, CaO/biomass ratio and coal bottom ash, respectively. The results showed that syngas production was significantly improved as it reached 65.44 vol% which was better than that obtained in earlier studies.

Microwave-assisted catalytic pyrolysis of moso bamboo for high syngas production

Microwave-assisted pyrolysis of moso bamboo with the activated carbon-supported iron(III) ion catalyst was carried out with the aim of obtaining high quality and quantity syngas(H₂ + CO). The effect of the catalyst on moso bomboo pyrolysis involving the temperature-rising characteristics, product distribution, tar conversion and gas compositions were investigated. The results indicated that the catalyst improved the microwave-absorption capability and increased the maximum reaction temperatures. The formation of gases was promoted by the catalyst mainly at the expense of the tar, indicating the catalyst had an excellent activity for the tar conversion .The catalyst had the positive influence on the formation of syngas with the maximum content reaching up to 81.14 vol% with H₂/CO being 1.04 and inhibited the production of CH₄ and CO₂. The loading of iron(III) ion into activated carbon exerted a significant influence on bamboo pyrolysis. The addition of the catalyst increased the thermal efficiency of the reaction system.

Evaluating oil palm fresh fruit bunch processing in Nigeria

Three routes of oil palm fresh fruit bunch (FFB) processing in Nigeria namely, industrial, small-scale and traditional were compared by means of determining fruit losses associated with each route. The fruits that are not recovered after each process were hand-picked and quantified in terms of crude palm oil (CPO), palm kernel (PK), mesocarp fibre (MF) and palm kernel shell (PKS). The energy value of empty fruit bunch (EFB), MF and PKS were used to determine the value of energy lost for each route. Additionally, the environmental implications of disposal of EFB were estimated, and socio-economics of the industrial and small-scale routes were related. The analysis showed that 29, 18, 75 and 27 kg of CPO, PK, MF and PKS were lost for every 1000 kg of FFB processed with the industrial route, whereas 5.6, 3.2, 1.4 and 5.1 g were lost with the small-scale route, respectively. Approximately 89 kWh and 31 kWh more energy were lost from MF and PKS with the industrial route than the other two routes, respectively. An equivalent of 6670 tonnes carbon dioxide equivalent of methane and nitrogen oxide was released due to the disposal of 29,000 tonnes of EFB from one palm oil mill. The monetary value of lost CPO per 1000 kg of FFB processed in the industrial route is more than the labour cost of processing 1000 kg of FFB in the small-scale route. The advantages of the industrial route are high throughput in terms of FFB processed per hour and high quality of CPO; however, high fruit loss is associated with it and therefore, the poorly threshed EFB is recommended to be fed into the small-scale route.

Biomass tar cracking and syngas production using rice husk char-supported nickel catalysts coupled with microwave heating

In the present work, biomass pyrolysis tar cracking and reforming for high quality syngas production using a rice husk char (RHC)-supported nickel catalyst (Ni/RHC) coupled with microwave heating was investigated. The Ni/RHC catalyst exhibited a high catalytic performance on tar removal and contributed well to the production of CO and H₂. The conversion efficiency could reach up to 97.3%, and the CO and H₂ yields were 274.0 ml g⁻¹ and 248.9 ml g⁻¹, respectively, at 700 °C, under microwave conditions, when the nickel loading amount was 10.42 wt% of the support. The tar conversion efficiencies and syngas yields significantly increased as the cracking temperatures increased from 500 °C to 700 °C and the nickel loading amount increased from 0 to 10.42 wt%. The Ni/RHC catalysts became more effective for tar removal and the production of syngas increased under microwave conditions compared to the results obtained under conventional conditions.

We explored the effect of Ni/RHC catalyst on tar removal and syngas production under microwave conditions.