Progress in biomass gasification technique – with focus on Malaysian palm biomass for syngas production

Synthesis gas, also known as syngas, produced from biomass materials has been identified as a potential source of renewable energy. Syngas is mainly consists of CO and H2, which can be used directly as fuel source for power generation and transport fuel, as well as feedstock for chemical production. Syngas is produced through biomass gasification process that converts solids to gas phase via thermochemical conversion reactions. This paper critically reviews the type of gasifiers that have been used for biomass gasification, including fixed bed, fluidized bed, entrained flow and transport reactor types. The advantages and limitations of these gasifiers are compared, followed by discussion on the key parameters that are critical for the optimum production of syngas. Depending on the biomass feedstock, the properties and characteristics of syngas produced can be varied. It is thus essential to thoroughly characterise the properties of biomass to understand the limitations in order to identify the suitable methods for gasification. This paper later focuses on a specific biomass – oil palm-based for syngas production in the context of Malaysia, where palm biomass is readily available in abundance. The properties and suitability for gasification of the major palm biomass, including empty fruit bunch, oil palm fronds and palm kernel shells are reviewed. Optimization of the gasification process can significantly improve the prospect of commercial syngas production

Experimental evaluation and empirical modelling of palm oil mill effluent steam reforming

The current work describes a novel application of steam reforming process to treat palm oilmill effluent (POME), whilst co-generating H2-rich syngas from the treatment itself. The effects of reaction temperature, partial pressure of POME and gas-hourly-space-velocity (GHSV) were determined. High crystallinity 20 wt%Ni/80 wt%Al2O3 catalyst with smooth surface was prepared via impregnation method. Baseline runs revealed that the prepared catalyst was highly effective in destructing organic compounds, with a two-fold enhancement observed in the presence of 20 wt% Ni/80 wt%Al2O3 catalyst, despite its low specific surface area (2.09 m2 g−1). In addition, both the temperature and partial pressure of POME abet the COD reduction. Consequently, the highest COD reduction of 99.7% was achieved, with a final COD level of 73 ± 5 ppm from 27,500 ppm, at GHSV of 40,000 mL/h.gcat and partial pressure of POME equivalent to 95 kPa at 1173 K. In terms of gaseous products, H2 was found to be the major component, with selectivity ranged 51.0%–70.9%, followed by CO2(17.7%–34.1%), CO (7.7%–18.4%) and some CH4 (0.6%–3.3%). Furthermore, quadratic models with high R2-values were developed

A review on the modeling and validation of biomass pyrolysis with a focus on product yield and composition

Article reviewing the modeling and verification of products derived from biomass pyrolysis and discussing the possible solutions towards more accurate modeling of biomass pyrolysis

Production of pyrolyzed oil from crude glycerol using a microwave heating technique

Crude glycerol, a by-product of biodiesel production created via transesterification was pyrolyzed using a microwave heating technique in an oxygen-deficient environment. Coconut shell-based activated carbon was used as a catalyst to assist in the heat transfer and the cracking of glycerol into gaseous and liquid products. Investigation into the product yield was conducted by varying the pyrolysis temperature between 300°C and 800°C. The result revealed that liquid and gaseous pyrolysis products yield fell in the range of 15-42% and 55-82% by mass, respectively. An analysis of the liquid product using gas chromatography mass spectrometry (GC-MS) shows that glycerin (C3H8O3), methanamine (CH5N), and cyclotrisiloxane (C6H18O3Si3) were among the highest derived compounds in the pyrolyzed liquid yield. The derived pyrolysis products can potentially be used as alternative fuels in combustion systems

Growth media derived from solid waste for orchid Dendrobium kingianum culture

Food waste and diaper waste contribute to top three ranking solid wastes in Malaysia. Many studies show that urine and food waste can be used as plant fertilizer but less attention has been given to the recycling of used diaper. Therefore, this study was conducted to formulate Dendrobium kingianum growing media by utilizing diaper waste and selected food waste: banana peels, coffee waste and eggshells. The chemical composition in diaper waste and food waste were determined by using ICP-OES method. Biochar derived from oil palm waste, sugarcane and sawdust were tested to reduce and neutralize the high ammonium content from diaper waste. Biochar derived from oil palm waste showed the best reduction of ammonium in diaper waste. Survival and growth performance of Dendrobium kingianum was observed and recorded. Results show that orchid in diaper formulated growth media T3 showed the best adaptation and growth performance with highest percentage of healthy leaves and number of absorption roots within 3 weeks observation period. These results revealed that diaper waste could be recycled as orchid growing media by formulating with food waste and biochar

Esterification of Microwave Induced Pyrolytic Oil from Sago Bark Waste

In this study, microwave induced pyrolytic oil from sago bark (SB) was subjected to esterification to improve its properties. Improvement on properties of the pyrolytic oil was performed via esterification with ethanol and the presence of sulfuric acid as a catalyst. The optimum esterification condition was studied using general factorial design. The esterified oil (EO) showed improved properties with pH (4–6), reduced moisture content (2.95–3.45%), density (0.9–1.1 g cm−3), and acid value (39.3–123.4 mg KOH−1 g−1), and maintained the CV (20.2–21.6 MJ kg−1). GC–MS analysis showed that EO was sulphur free, and low in carboxylic acid and oxygenated compounds. The optimal esterification condition with optimum quality of EO was at 65 °C temperature, 60 min reaction time and 1:1 ethanol to oil volume ratio. Results indicated that the EO can be potentially used in robust combustion engines upon properties refinement

Oil palm waste: An abundant and promising feedstock for microwave pyrolysis conversion into good quality biochar with potential multi-applications

Oil palm waste (OPW), comprising mainly of empty fruit bunch, mesocarp fiber, frond, trunk, and palm kernel shell generated from palm oil industry, was collected, characterized, and then pyrolyzed to evaluate their potential to be converted into biochar with desirable properties for use in multi-applications. The OPW was detected to have considerable amounts of carbon (43–51 wt%) and fixed carbon (30–39 wt%), showing potential to be converted into carbon-rich biochar. Microwave pyrolysis of palm kernel shell as the selected OPW produced a biochar with zero sulphur content and high heating value (23–26 MJ/kg) that is nearly comparable to conventional coal, thus indicating its potential as an eco-friendly solid fuel. The biochar obtained was also showed low moisture (<3 wt%) and ash (3 wt%), and a highly porous structure with high BET surface area (210 m2/g), indicating the presence of many adsorption sites and thus showing desirable characteristics for potential use as pollutant adsorbent in wastewater treatment, or bio-fertilizer to absorb nutrient and promote plant growth. Our results demonstrate that OPW is a biowaste that shows exceptional promise to be transformed into high-grade biochar rather than simply disposed by landfilling or burned as low-grade fuel in boiler

Pyrolysis recovery of waste shipping oil using microwave heating

This study investigated the use of microwave pyrolysis as a recovery method for waste shipping oil. The influence of different process temperatures on the yield and composition of the pyrolysis products was investigated. The use of microwave heating provided a fast heating rate (40 °C/min) to heat the waste oil at 600 °C. The waste oil was pyrolyzed and decomposed to form products dominated by pyrolysis oil (up to 66 wt. %) and smaller amounts of pyrolysis gases (24 wt. %) and char residue (10 wt. %). The pyrolysis oil contained light C9-C30 hydrocarbons and was detected to have a calorific value of 47-48 MJ/kg which is close to those traditional liquid fuels derived from fossil fuel. The results show that microwave pyrolysis of waste shipping oil generated an oil product that could be used as a potential fue

Morphology and growth of carbon nanotubes catalytically synthesised by premixed hydrocarbon-rich flames

Synthesis of carbon nanotubes (CNTs) was performed by using a laminar premixed flame burner at open atmospheric condition. The growth of CNTs on the substrate was supported catalytically by a transition metal under high temperature, hydrocarbon-rich environment. Analysis of the CNTs using high resolution electron microscope reveals the structure of synthesised nano-materials in disarray, clustered and tubular form. The graphitic structure of the CNTs are rather similar for all fuel-rich equivalence ratios tested, with an average diameter of ∼11–13 nm. Removal of the amorphous carbon and catalyst in the CNTs was performed via purification treatment using H2O2 and HCl solutions. Detail characterisation indicates the oxidation temperature of purified CNTs ranges between 497 and 529 °C. Deconvolution of the Raman spectra in the range of 900–1800 cm−1 shows the distinct characteristic bands of CNTs with IG/ID ratio of 0.66–0.72 for all the samples tested. In addition, the high level carbon concentration and sp2 Csingle bondC bond in the CNTs is shown by X-ray photoelectron spectroscopy analysis. The present study demonstrates that CNTs can be effectively synthesised from fuel-rich hydrocarbon flames at ϕ = 1.8–2.0 supported by nickel-based substrate

Numerical simulation and experimental validation of microwave torrefaction for empty fruit bunches pellet

This study investigates the microwave heating and torrefaction process of empty fruit bunch (EFB) pellets. Finite element based COMSOL Multiphysics software was used to predict the microwave heating behaviour of EFB pellets during the torrefaction process. The simulated temperature data from multimode microwave system at 2.45 GHz frequency was used to compare and validate the experimental results. Quantitative validation of 10 min temperature profiles between 25-300 °C was performed by comparing the simulated and experimental results. RMSE and maximum different temperature profile were 16.42 and 38°C respectively which may cause by the moisture of pellet, exothermic reaction and placement of the thermocouple during microwave torrefaction process. The simulation work has successfully identified the hot spots of EFB pellets during microwave torrefaction. Hot spot happened in the temperature range of 250-450 °C and was observed near the waveguide and centre of the EFB pellets bed. This study provided a framework and required model parameters to predict temperature profile and hot spot location for a specific geometry of microwave cavity