Arshad Adam Salema

Microwave induced pyrolysis of oil palm biomass

The purpose of this paper was to carry out microwave induced pyrolysis of oil palm biomass (shell and fibers) with the help of char as microwave absorber (MA). Rapid heating and yield of microwave pyrolysis products such as bio-oil, char, and gas was found to depend on the ratio of biomass to microwave absorber. Temperature profiles revealed the heating characteristics of the biomass materials which can rapidly heat-up to high temperature within seconds in presence of MA. Some characterization of pyrolysis products was also presented. The advantage of this technique includes substantial reduction in consumption of energy, time and cost in order to produce bio-oil from biomass materials. Large biomass particle size can be used directly in microwave heating, thus saving grinding as well as moisture removal cost. A synergistic effect was found in using MA with oil palm biomass.

Pyrolysis and combustion kinetics of date palm biomass using thermogravimetric analysis

The present research work is probably the first attempt to focus on the kinetics of pyrolysis and combustion process for date palm biomass wastes like seed, leaf and leaf stem by using Thermogravimetric Analysis (TGA) technique. The physical properties of biomass wastes were also examined. Proximate and ultimate analysis of the date palm biomass was investigated. FT-IR analysis was conducted to determine possible chemical functional groups in the biomass. Results showed that date palm seed and leaf can be characterized as high calorific values and high volatile content biomass materials as compared to the leaf stem. Kinetic analysis of this biomass was also given a particular attention. It is concluded that these biomasses can become useful source of energy, chemicals and bio-char.

Pyrolysis of oil palm empty fruit bunch biomass pellets using multimode microwave irradiation

Oil palm empty fruit bunch pellets were subjected to pyrolysis in a multimode microwave (MW) system (1 kW and 2.45 GHz frequency) with and without the MW absorber, activated carbon. The ratio of biomass to MW absorber not only affected the temperature profiles of the EFB but also pyrolysis products such as bio-oil, char, and gas. The highest bio-oil yield of about 21 wt.% was obtained with 25% MW absorber. The bio-oil consisted of phenolic compounds of about 60-70 area% as detected by GC-MS and confirmed by FT-IR analysis. Ball lightning (plasma arc) occurred due to residual palm oil in the EFB biomass without using an MW absorber. The bio-char can be utilized as potential alternative fuel because of its heating value (25 MJ/kg).

A new technique to pyrolyse biomass in a microwave system: effect of stirrer speed

A new technique to pyrolyse biomass in microwave (MW) system is presented in this paper to solve the problem of bio-oil deposition. Pyrolysis of oil palm shell (OPS) biomass was conducted in 800 W and 2.45 GHz frequency MW system using an activated carbon as a MW absorber. The temperature profile, product yield and the properties of the products were found to depend on the stirrer speed and MW absorber percentage. The highest bio-oil yield of 28 wt.% was obtained at 25% MW absorber and 50 rpm stirrer speed. Bio-char showed highest calorific value of the 29.5 MJ/kg at 50% MW absorber and 100 rpm stirrer speed. Bio-oil from this study was rich in phenol with highest detected as 85 area% from the GC-MS results. Thus, OPS bio-oil can become potential alternative to petroleum-based chemicals in various phenolic based applications.

Fluidized bed combustion of rice husk to produce amorphous siliceous ash

This paper presents research work on producing amorphous siliceous ash with low carbon content through combustion of rice husk in a fluidized bed combustor. Preparation of high-purity amorphous siliceous ash through the conventional alkaline extraction method is time-consuming and costly. Various drawbacks are associated with the preparation of siliceous rice husk ash via thermal treatment of rice husk in existing thermal treatment technologies, the main being the formation of crystals, high residual carbon in ash and long reaction time. Fluidized bed technology is capable of producing amorphous rice husk ash with very low carbon content in a very rapid reaction time due to its high combustion intensity and good mixing behaviour. The achievements and potential areas for development of the current research are also presented. Lastly, the quality of ash has been given particular attention in terms of amorphous nature and carbon content.

Pyrolysis of corn stalk biomass briquettes in a scaled-up microwave technology

Pyrolysis of corn stalk biomass briquettes was carried out in a developed microwave (MW) reactor supplied with 2.45GHz frequency using 3kW power generator. MW power and biomass loading were the key parameters investigated in this study. Highest bio-oil, biochar, and gas yield of 19.6%, 41.1%, and 54.0% was achieved at different process condition. In terms of quality, biochar exhibited good heating value (32MJ/kg) than bio-oil (2.47MJ/kg). Bio-oil was also characterised chemically using FTIR and GC-MS method. This work may open new dimension towards development of large-scale MW pyrolysis technology.

Heating characteristics of biomass and carbonaceous materials under microwave radiation

Proper understanding of microwave and material interaction is important to design effective microwave treatment system. Therefore, this paper aims to reveal the basic heating characteristics of biomass and carbonaceous materials subjected to microwave radiation at 2.45 GHz frequency. This was done in a single mode microwave system of 1 kW power capacity. The effect of microwave cavity design on the heating characteristics of oil palm shell (OPS) biomass and activated carbon was studied. A particular attention was also given to the effect of OPS biomass particle size on the temperature profiles. Biomass materials were found to be poor absorber of microwaves and the increase in temperature of biomass was found to be because of its moisture content. On the other hand, activated carbon is very good microwave absorber and can become efficient microwave susceptors for low loss materials such as biomass. Proper design of cavity is necessary to achieve high temperature values. Large size particles can be heated using microwaves but the temperature remains low which was not enough to carry out the thermo-chemical process.

SIMULATION STUDIES OF GAS-SOLID IN THE RISER OF A CIRCULATING FLUIDIZED BED

A numerical parametric study was performed on the influence of various riser exit geometries on the hydrodynamics of gas-solid twophase flow in the riser of a Circulating Fluidized Bed (CFB). A Eulerian continuum formulation was applied to both phases. A two fluid framework has been used to simulate fully developed gas-solid flows in vertical riser. A two dimensional Computational Fluid Dynamics (CFD) model of gas-particle flow in the CFB has been investigated using the code FLUENT. The turbulence was modeled by a k-e turbulence model in the gas phase. The simulations were done using the geometrical configuration of a CFB test rig at the Universiti Teknologi Malaysia (UTM). The CFB riser column has 265 mm (width), 72 mm (depth) and 2.7 m height. The riser is made up of interchangeable Plexiglas columns. The computational model was used to simulate the riser over a wide range of operating and design parameters. In addition, several numerical experiments were carried out to understand the influence of riser end effects, particle size, gas solid velocity and solid volume fraction on the simulated flow characteristics. The CFD model with a k-e turbulence model for the gas phase and a fixed particle viscosity in the solids phase showed good mixing behaviour. These results were found to be useful in further development of modeling of gas solid flow in the riser. However, computational fluid dynamics (CFD) is emerging as a very promising new tool in modeling hydrodynamics. While it is now a standard tool for single-phase flows, it is at the development stage for multiphase systems, such as fluidized beds [3]. Many researchers have used commercial CFD codes for simulating multiphase problems and similar simulations were performed by Taghipour [4] in fluidized bed with the presence of air and sand using FLUENT 4.56. The research was carried out at various velocities. The performance of the code was better at higher gas velocities. Many researchers have simulated three-dimensional two fluids CFD model of gas particle flow in the CFB using the code CFX4.3. The turbulence was modeled by k-e turbulence model in the gas phase and a fixed particle viscosity model in the solid phase. This CFD model showed good agreement with the experiments [5]. A similar study of gas/particle flow behavior in the riser section of a circulating fluidized bed (CFB) was done using FLUENT 4.4. Fluid Catalytic Cracking (FCC) particles and air were used as the solid and gas phases, respectively. The computational results showed that the inlet and outlet design have significant effects on the overall gas and solid flow patterns and cluster formations in the riser [6].

Bio-oils characteristic from oil palm biomass from different fast pyrolysis techniques

Pyrolysis is one of the effective ways to convert biomass into energy and value added products. Till date, no comparative study has been done on the characteristic of bio-oils of oil palm shell (OPS) and empty fruit bunch (EFB) from various fast pyrolysis techniques. This includes fluidized bed, fixed bed, rotating cone, microwave and others. Thus, the main objective of this paper was to analyze the characteristics of OPS and EFB bio-oils obtained from these processing techniques. Temperature was found to be the key parameter for the quality of bio-oils. Besides the various pyrolysis techniques, the lignocellulosic constituents of oil palm biomass also influence the chemical composition of the bio-oils. Overall, chemical analysis of OPS and EFB bio-oil through GC-MS has shown variation in the amount of phenol and its derivatives.

Influence of bed height on the quality of rice husk ash in a fluidised bed combustor

The purpose of this study was to investigate the effect of bed height on the quality of rice husk ash in a 210-mm diameter pilot scale fluidised bed combustor. The degree of rice husk burning in the fluidised bed could be deduced from the temperature of the combustor and the particle size of the resulting ash. The turbulence in the bed would break down the char skeleton of the rice husk into finer size. From this study, the bed height of 0.5 Dc was found to give the lowest residual carbon content in the ash (1.9%) and the highest bed temperature (670°C). Moreover, the problem of contamination of amorphous rice husk ash with sand increased as the bed height was increased. Nevertheless, the results from the current study need to be validated in larger-scale fluidised beds to determine whether the bed height of 0.5 Dc is still applicable.