Shell Gasification Research Articles

Thermodynamic Study of Palm Kernel Shell Gasification for Aggregate Heating in an Asphalt Mixing Plant

This study evaluated thermodynamically the performance of conversion of palm kernel shells into combustible gas through gasification technology for aggregate heating in a hot-mixed asphalt production plant by developing a thermodynamic model using licensed Aspen Plus v.11 software. The effects of the equivalence ratio (ER) in the gasification process and the amount of combustion air to combustible gas to attain the required aggregate temperature were investigated. The thermodynamic model showed a good agreement with the experimental results based H2 and CO contain in producer gas which provided by maximum root mean square errors value of 8.82 and 6.42 respectively. Gasification of 30–35 kg of palm kernel shells in a fixed-bed gasifier reactor using air as a gasifying agent at an ER of 0.325–0.350 generated gaseous fuel for heating 1 ton of aggregate to a temperature of 180–200°C with combustion excess air 10%–20%.

Gasification of Oil Palm Shells and Empty Fruit Bunches to Produce Gas Fuel

National energy needs have been met by non-renewable energy resources, such as natural gas, petroleum, coal and so on. However, non-renewable energy reserves are depleting and there will be an energy crisis. Conversion of biomass into energy is one solution to overcome this. Indonesia, with its biodiversity, has enormous biomass potential, especially from oil palm plantations and also sugar cane plantations. From the oil palm plantation point of view, oil palm shells and oil palm empty fruit bunches are side products. These wastes can be treated with gasification technology to produce gas fuel. The gasification tool model used in this study is a downdraft gasifier equipped with a cyclone to separate gases with solids or liquids resulting from the gasification process. The results of the gasification process show that the more feeds are introduced, the more syngas is produced during the gasification process. The more feeds, the longer the syngas release time. The two variables have a correlation, that is, between the weight of syngas and the time for syngas removal to increase in line with the addition of the amount of feed entered. Syngas analysis of oil palm empty fruit bunches contains 4.959% H2 and 5.759% CO. Whereas the analysis of syngas of oil palm shells contained 2.524% H2, 6.391% CO, and 0.895% CH4.

Subcritical water gasification of lignocellulosic wastes for hydrogen production with Co modified Ni/Al2O3 catalysts

Nickel-based catalysts with different supports and cobalt loadings were synthesized for hydrothermal gasification of cellulose at 350 °C. The activity of Ni catalysts was found in the order of Al2O3 > spent bleaching clay ash > SiO2 with H2 yield of 80.6%, 69.0% and 57.0%. When 6 wt. % Co was added, 10Ni-6Co/Al2O3 showed the highest H2 yield of 88.4% i.e., 1.44 times that without Co addition. Catalysts were characterized by NH3-TPD, TPR, XRD, BET and XPS, showing that Ni-Co alloy formation promoted H2 production. Single-factor experiments were conducted to study variables in the presence of 10Ni-6Co/Al2O3 with the selected conditions of 0.5 g biomass and 20 min at 350 °C (achieving 94.9% H2 yield from cellulose) for gasification of rice straw, peanut shell and cotton straw with the increase in H2 yield by 51.4, 76.0 and 67.8 times. Ni-Co/Al2O3 catalysts enhanced hydrothermal gasification of actual agricultural residues.

Biomass gasification of candlenut shell and coconut coir with the updraft gasifier method being alternative fuel

Lately, the use of fossil fuels has caused many environmental problems such as global warming as a result of greenhouse gas emissions, which has led to increased fuel prices and erratic availability. These encouraged the interest of researchers to find alternative fossil fuels sourced from renewable raw materials. Candlenut shells and coconut fiber are high-potential plantation and agricultural commodities in East Nusa Tenggara. Statistical data shows that candlenut production reached 1,262.38 tons, while coconut reached 68,496 tons in 2016. The by-products of shells and coir can be used as a good raw material for the gasification process into alternative fuels. One of the established gasification processes in the industry is updraft gasifier. This research has varied the use of candlenut shells and coconut coir in the range of 0-100% to study the characteristics of its gasification products. The purpose of this study was to determine the effect of variations of candlenut shells and coconut coir on syngas ignition time; the effective time of the gasification process, remaining charcoal and ash, the efficiency of the gasification process and to find out the best variation between candlenut shells and coconut fiber on gas products (syngas) updraft gasifier. The results obtained indicate that the process of gasification of candlenut shells and coconut coir using updraft gasifier was very influential at the time of ignition of syngas, and the effective time of gasification. The highest syngas ignition time was obtained in a variation of 50% candlenut and 50% coconut husk which was 43.14 minutes and the lowest was a variation of 0% shells and 100% coconut husk which was 39.75 minutes. While the highest effective time of the gasification process was obtained by variations of 100% candlenut and 0% coconut husk which was 33.13 minutes and the lowest in variations of 75% shells and 25% coconut husk which was 37.40 minutes. The best gasification process was shown in a variation of 50% candlenut shells and 50% coconut husk.

Gasification of walnut shells in an open core downdraft gasifier for the producer gas generation

ABSTRACT This research work depicts the results obtained during the experiment performed for walnut shell gasification process. In order to carry out the gasification process, a downdraft gasifier has been installed in a Thermal Engineering Laboratory of National Institute of Technology, Kurukshetra, India for the purpose of generating a combustible gas popularly known as “Producer gas.” The walnut shells have been gasified with air used as a gasifying agent. In this experimental work equivalence ratio Φ varied from 0.170 to 0.251; subsequently, feedstock consumption rate also varied from 68 to 77 kg/h. Results publicized that at an equivalence ratio Φ of 0.251, cold gas efficiency and calorific value of producer gas has its maximum value of 83.07% and 7.59 MJ/Nm3, respectively. The percentage of methane (CH4) in producer gas reached its maximum value of 7.04% at Φ equals to 0.251. Further, oxidation zone temperature varied in between 700 and 1000°C during this study.

Life cycle analysis of palm kernel shell gasification for supplying heat to an asphalt mixing plant

The Government of the Republic of Indonesia states that the thermal energy for hot-mixed asphalt production shall be supplied by the direct combustion of fossil fuels in the form of diesel oil, natural gas, or fuel gas from coal gasification which may generate GHG emission. Biomasses are able to substitute the fossil fuels through gasification technology. Gasification converts the biomass using limited air into gaseous fuel containing mainly CO and H2 that are subsequently combusted to produce heat, carbon dioxide, and water. It is obvious that the CO2 is then absorbed by the plants for photosynthesis, maintaining a balanced closed cycle. This study examines the level of global warming potential of this system for supplying heat based on the openLCA v1.9 software. The analysis used a gate-to-gate approach to evaluate scenarios of shell gasification to produce 1 metric tonne of hot-mixed asphalt. The scope covers raw material supply and transportation, palm kernel shell gasification, and products. The evaluation concludes that gasification could potentially reduce CO2 emissions. Environmental impact analysis and interpretation of the results using the openLCA database of Traci 2.1 recommend that greater CO2 emission reduction is possible using palm kernel shell gasification, not only for supplying heat but also for electricity generation to operate all electrical equipments.

Theoretical and experimental feasibility study of groundnut shell gasification in a fluidized bed gasifier

Gasification is one of the most efficient options among the different thermochemical methods to utilize the energy potential of biomass. The energy density of biomass is increased by converting it into concentrated fuel gas. The feasibility of utilizing groundnut shell in a fluidized bed gasifier is assessed in this study. In the present work, a modified stoichiometric equilibrium model is developed based on the assumption that the species and the reaction are in thermodynamic equilibrium. The developed model can predict the gas composition at different operating conditions like operating temperature and equivalence ratio. The detailed parametric studies with the assistance of the model help in preliminary design and development of the gasifier. Investigations on air gasification with groundnut shell as biomass feed have been taken up. The model-predicted compositions of producer gas at different operating temperatures were compared with experimental values at the same temperature, and an RMS error of 6.11 has been obtained. With the validated model, the gas composition at different equivalence ratios is also predicted. The obtained results clearly indicate that groundnut shell is a potential feedstock for gasification.

Effects of temperature on the chemical composition of tars produced from the gasification of coconut and palm kernel shells using downdraft fixed-bed reactor

Tar is derived from the gasification of cellulose and hemicellulose-rich coconut shell (CS) and lignin rich-palm kernel shell (PKS) using a downdraft fixed-bed reactor at 700 °C–900 °C. The tar yields and higher heating values from both biomass decrease with the increase in temperature, but high tar yields and higher heating values are obtained from PKS. Fourier transform infrared showed a similar pattern between the wavenumbers of 1500 cm−1 and 4000 cm−1, thereby indicating that the main chemical groups in CS and PKS tars are similar. The ultraviolet–visible spectroscopy shows that the aromatic content of tars increases with the increase in temperature, and CS tars show higher fluorescence intensity than PKS tars at >800 °C. Proton nuclear magnetic resonance shows that the tars from CS and PKS exhibit highly aromatic and phenolic protons, respectively. Gas chromatography–mass spectrometry results reveal that the total relative content of compounds in PKS tars is slightly higher than that in CS tars, and phenol group is the most abundant compound at all temperatures. Overall, the formation of aromatics and light PAHs are higher with CS tars, but PKS tars are more stable for the formation of heterocyclic and heavy PAHs.

Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells

In the present scenario, due to atrocious rise in energy demand interest has been grown in extracting energy from renewable sources such as waste biomass. In this study, preparation of producer gas from walnut shell gasification has been done for the purpose of partially substituting diesel with producer gas for VCR dual fuel (DF) diesel engine working in dual mode. Experiments have been conducted at different brake power and compression ratio for predicting the engine performance and emission characteristics. A comparative result analysis has been done for both diesel and dual mode. The results revealed that maximum fuel saving of 58.18% was achieved in dual mode operation. Brake thermal efficiency (ηbth) attained a maximum value of 25.63 and 21.61% in diesel and dual mode respectively. At brake power of 3.44 kW for diesel mode, NOX emission was 16.09–45.23% more as compared with dual mode. With dual mode CO and hydrocarbon emission were increased in the range of 62.21–72.53% and 83.25–87.60% correspondingly as compared to diesel mode. Further, diesel mode maximum CO2 fraction was 2.13% and 3.41% for dual mode.

Estimation of potential hydrogen production from palm kernel shell in Norte de Santander, Colombia

This work sought to estimate the economic and environmental potential of palm kernel shell for hydrogen production as energy vector in Norte de Santander, Colombia. A field research determined that the department generates monthly 14082 t of palm biomass of which 12501 of palm kernel shell remain available for their use. The proximate and ultimate analyses of the palm kernel shell report high heating value (19.53 MJ/kg) compared with other agro-industrial biomasses, high content of volatile material (69.82% w/w) and fixed carbon (21.68% w/w), promoters of chemical reactions in pyrolysis and gasification processes, respectively. In the Aspen Plus® simulation process of the palm kernel shell gasification at 900 °C and steam/biomass ratio of 1.5, a yield is obtained of hydrogen production of 40.7%, equivalent to a monthly production in Norte de Santander of 51.6 t. Using H2 in the generation of electric power permits producing 470.9 MWh/month that represent theoretical utilities of US$27734.5. In another scenario, 55848.8 gal/month of gasoline are substituted, equivalent to US$11708.6 through the sale of carbon credits. Regarding diesel, 45905.1 gal are replaced per month, which add US$9725.4 through the commercial transaction in the carbon market. It is concluded that using palm kernel shell as primary source to obtain H2, has, in principle, a favorable economic and environmental impact for sustainable development of the department of Norte de Santander, besides contributing to the knowledge base on the penetration of this vector in Colombia’s energy matrix; however, more detailed technical and economic studies are needed to conclude regarding the economic viability of this energy conversion process.

A Downdraft Fixed-Bed Biomass Gasification System with Integrated Products of Electricity, Heat, and Biochar: The Key Features and Initial Commercial Performance

Biomass, as a renewable and clean energy resource, plays a vital role in energy security and greenhouse gas reduction across the world. This paper reports on our newly established technology: a downdraft fixed-bed biomass gasification system using nut shells (mainly apricot kernel shells) for electricity generation, heating and partially activated carbon production at the same time. Particularly, the key features of the gasification reactor will be presented in detail. In the commercial plant (3 MW scale) located in Hebei province, China, the typical energy conversion from apricot kernel shell gasification is as follows: 47% syngas, 44% char (partially activated carbon), 5% hot water, and 4% energy loss. The main gasification temperature is 600–800 °C, while the activation zone is 850–900 °C. The commercial system has currently been in operation for 4 years. Considering the partially activated carbon as a stable carbon carrier, the whole system features negative CO2 emissions.

Parametric analysis and optimization for the catalytic air gasification of palm kernel shell using coal bottom ash as catalyst

The air gasification of palm waste specifically palm kernel shell has been performed in the fixed bed gasifier using coal bottom ash as a potential catalyst. Effect of the process variables (temperature, catalyst loading, and airflow rate) has been investigated on the product gas composition. The design of experiments was accomplished using the Design Expert v11® with a Central Composite Design approach. Moreover, the parametric study and optimization of the entire process have been carried out using Response Surface Methodology within the specific range of variables. The results suggested that the temperature has been found as the most influencing parameter for increment of H2 and CO production. Whereas, airflow rate was more sensitive for CH4 and CO2 production. Catalyst loading was found very effective for the amplified amount of H2 and CO production and the reduction in the amounts of CO2 and CH4, caused by the catalytic activity of coal bottom ash (CBA). Optimized parameters are found to be the temperature of 850 °C, catalyst loading of 14.50 wt%, and airflow rate of 2.50 L/min, which predicted the composition for H2 of 31.38 vol%, CO of 26.44 vol%, CH4 of 15.67 vol%, and CO2 of 25.59 vol%.

Simulation of biomass gasification in a BFBG using chemical equilibrium model and restricted chemical equilibrium method

Biomass gasification in fluidized beds is a promising thermo-chemical conversion technology. Bubbling fluidized bed gasifier (BFBG) is considered in the present study, to specify an appropriate model for almond shell gasification. Therefore, the chemical equilibrium model (CEM) and restricted chemical equilibrium method (RCEM) are developed using Aspen Plus. Then, the accuracy of the results obtained from these two modelling approaches is evaluated by comparing with the experimental data. More consistent results are obtained by using RCEM. A sensitivity analysis study is also performed with the specified modelling approach (RCEM) to investigate the effect of operating parameters on the gasification performance. For this purpose, the range of the gasification temperature and steam to biomass ratio are extended and a new parameter (biomass moisture content) is incorporated into the parametric study. Increasing temperature is shown to have a positive effect on cold gas efficiency (CGE) while it has a negative effect on lower heating value (LHV). There is no considerable change in gas heating value and CGE above 850 °C. Both steam to biomass (S/B) ratio and biomass moisture content have a favorable effect on H2 production. However, these parameters have adverse effect on gas heating value and CGE. LHV and CGE reach maximum values for S/B ratio of 0.5 and moisture content of 0.

Process analysis of hydrogen production from biomass gasification in fluidized bed reactor with different separation systems

Gasification is one of the most effective and studied methods for producing energy and fuels from biomass as different biomass feedstock can be handled, with the generation of syngas consisting of H2, CO, and CH4, which can be used for several applications. In this study, the gasification of hazelnut shells (biomass) within a circulating bubbling fluidized bed gasifier was analyzed for the first time through a quasi-equilibrium approach developed in the Aspen Plus environment and used to validate and improve an existing bubbling fluidized bed gasifier model. The gasification unit was integrated with a water-gas shift (WGS) reactor to increase the hydrogen content in the outlet stream and with a pressure swing adsorption (PSA) unit for hydrogen separation. The amount of dry H2 obtained out of the gasifier was 31.3 mol%, and this value increased to 47.5 mol% after the WGS reaction. The simulation results were compared and validated against experimental data reported in the literature. The process model was then modified by replacing the PSA unit with a palladium membrane separation module. The final results of the present work allowed comparison of the effects of the two conditioning systems, PSA and palladium membrane, indicating a comparative increase in the hydrogen recovery ratio of 28.9% with the palladium membrane relative to the PSA configuration.

Effect of particle size and temperature on gasification performance of coconut and palm kernel shells in downdraft fixed-bed reactor

Gasification of coconut shell (CS) and palm kernel shell (PKS) is conducted in a batch type downdraft fixed-bed reactor to evaluate the effect of particle size (1–3 mm, 4–7 mm, and 8–11 mm) and temperature (700, 800, and 900 °C) on gas composition and gasification performance. The response surface methodology integrated variance-optimal design is used to identify the optimum condition for gasification. Gas composition, which is measured using the biomass particle size of 1–11 mm at 700–900 °C, are 8.20–14.6 vol% (H2), 13.0–17.4 vol% (CO), 14.7–16.7 vol% (CO2), and 2.82–4.23 vol% (CH4) for CS and 7.01–13.3 vol% (H2), 13.3–17.8 vol% (CO), 14.9–17.1 vol% (CO2), and 2.39–3.90 vol% (CH4) for PKS. At similar conditions, the syngas higher heating value, dry gas yield, carbon conversion efficiency, and cold gas efficiency are 4.01–5.39 MJ/Nm3, 1.50–1.95 Nm3/kg, 52.2–75.9%, and 30.9–56.4% for CS, respectively, and 3.82–5.09 MJ/Nm3, 1.48–1.92 Nm3/kg, 59.0–81.5%, and 33.0–57.1% for PKS, respectively. Results reveal that temperature has a greater role than particle size in influencing the gasification reaction rate.

Simulation of the gasification process of palm kernel shell using Aspen PLUS

This research sought to simulate gasification of palm kernel shell (PKS) in stationary state by using Aspen PLUS®. The model can predict the syngas composition with 1.6% absolute error. Biomass is defined as a non-conventional component from its proximate and ultimate analyses. The gasification process was divided into four stages: drying, pyrolysis, oxidation, and reduction, simulated in two R-Yield and R-Equil reactors, specified through the physicochemical characterization of the PKS and the chemical reactions in equilibrium intervening in the gasification. Simulation results were validated with experimental results from other investigations with similar operating conditions. Production of H2 and CO2 increases by increasing temperature from 700 to 900°C, contrary to what occurs with CO that diminishes at higher temperatures. The steam/biomass (S/B) ratio has a significant effect on the proportion of H2 in the syngas, given that it diminishes significantly by 20.3% upon increasing the S/B ratio from 1.5 to 2.5, showing the same trend for the CO and CO2 gases.

Gasification of lignocellulosic biomass to produce syngas in a 50 kW downdraft reactor

Lignocellulosic biomass gasification shows a pronounced prospective to replace fossil fuels. In this study, the gasification of coconut shell with charcoal using a 50 kW downdraft reactor was investigated. The controlling parameter of temperature and pressure were used to verify the production of gas during the gasification process with air. The higher contents of cellulose and hemicellulose than lignin in the sample were found to gasify better, as evident from structural analysis. The gasifier produces a combustible gas with a H2, CO, CO2 and CH4 concentrations of 8.44, 15.38, 5.38 and 1.62 mol.% respectively, at a total flow of air of 30 m3 h−1. The results revealed that 30 wt% charcoal in the feedstock was effectively gasified to generate syngas comprising over 30 mol.% of syngas with a lower heating value of 3.27 MJ/Nm3. Thus, the co-gasification of lignocellulosic biomass with charcoal may contribute to affordable and environmentally friendly syngas energy.

Thermal behavior and pyrolytic kinetics of palm kernel shells and Indian lignite coal at various blending ratios

The study presents the effect of heating rate on thermal degradation kinetics of gasification and cogasification of palm kernel shell (PKS) and low-grade Indian coal (LC) at various blends. The thermogravimetric analysis (TGA) and pyrolytic kinetics of PKS and LC were investigated by heating up to 1000 °C at a different heating rate of 10, 20, 30, 40 and 50 °C/min. With the increase of heating rate, the TG profile of both PKS and LC were found different. For the gasification kinetics of PKS and LC, the activation energy (E) was 56.92 and 74.69 kJ/mol along with the exponential factor (A) as 9.391 × 103 and 6.740 × 103 min−1 respectively. In case of cogasification studies, the activation energy for the blends of PKS and LC at various ratios were found lowered to the range of 56–66 kJ/mol. This study could propose the appropriate blending ratio of PKS with LC for co-gasification at ease.

Artificial neural network approach for the steam gasification of palm oil waste using bottom ash and CaO

Abstract The Artificial Neural Network (ANN) modelling is presented for the steam gasification of palm kernel shell using CaO adsorbent and coal bottom ash as a catalyst. The effect of the parameters such as; temperature, CaO/biomass ratio and Coal bottom ash wt.% at fixed steam/biomass ratio and steam/biomass ratio at the fixed temperature on product gas composition of H2, CO, CO2, and CH4 are modelled using ANN. The effect of parameters is used as an input, while the gas compositions, syngas yield, LHVgas and HHVgas of gas as the output of the network. Back propagation algorithm has been used for the training with 7 neurons in the hidden layer. Hence, the selected ANN architecture was (2-7-1). The gas composition predicted by the ANN model are compared with experimental results obtained from pilot scale gasification system that has been reported in our previous study. The ANN predicted results show high agreement with the published experimental values with the coefficient of determination R2 = 0.998 for almost all the cases, i.e., the effect of parameters. RMSE, MAD, and AARE have been reported to be very insignificant for the predicted and experimental values.

Groundnut shell gasification performance in a fluidized bed gasifier with bubbling air as gasification medium

ABSTRACTThis work was focused on finding the groundnut shell (GNS) gasification performance in a fluidized bed gasifier with bubbling air as gasification medium. GNS in powder form (a mixture of different particle size as given in table 8 in the article) was gasified using naturally available river sand as bed material, top of the bed feeding, conventional charcoal as bed heating medium, and two cyclones for proper cleaning and cooling the product gas. Experiments were performed using different operating conditions such as equivalence ratio (ER) between 0.29 and 0.33, bed temperature between 650°C and 800°C, and feedstock feeding rate between 36 and 31.7 kg/h. Different parameters were evaluated to study the gasifier performance such as gas yield, cold gas efficiency, carbon conversion efficiency (CCE), and high heating value. The most suitable ER value was found to be 0.31, giving the most stable bed temperature profile at 714.4°C with 5–10% fluctuation. Cold gas efficiency and CCE at optimal ER of 0.31 was found to be 71.8% and 91%, respectively.