Papers by Keyword: Fluidized Bed

Abstract: The solid waste produced from urban area is an urgent issue to be addressed. A fluidized bed (FB) gasification technology has been widely applied and proven effective to convert waste into clean energy and environmentally friendly. Co-gasification is a technique of mixing two or more fuels that aims to improve calorific value of the gas production. A FB gasifier reactor is designed using some previous experiments and available literature as well as from the internal experience of the research group. The gasification reactor pilot plant scale using data input of waste and biomass fuels has been fabricated with diameter of 0.7 m and a height of 1.5 m. The Tests have been performed showing that the FB gasifier is very feasible to be developed.

Abstract: A continuous membrane-less anaerobic fluidized bed microbial fuel cell was used to investigate the effects of fluidization parameters on the electro-genesis capacity of the microbial fuel cell. The experimental results indicated that active carbon particles could significantly decrease the start-up time and increase the output voltage of the fluidized bed microbial fuel cell. At steady state operating conditions, the microbial fuel cell output voltages were 700~900 mV and 600~700 mV for with and without the active carbon particles, respectively. The fluidization behavior of the active carbon particles in the microbial fuel cell reactor is one of the key parameters that influences the generation of electricity. The experimental results indicated that to obtain the optimal electric production performance, an appropriate flow velocity should be determined. The fluidized bed microbial fuel cell could be operated in large-scale wastewater treatment processes with high Chemical Oxygen Demand removal efficiencies that reached 93%.

Abstract: The fast pyrolysis is an efficient and promising process of thermal decomposition. The process consists in the reaction of organic materials in the total or partial absence of oxygen to produce condensable vapor, non-condensable gases and char. Bio-oil is generated after vapor condensation and it can be converted into fuels and/or chemicals. Fast pyrolysis of soy hulls was conducted in a batch reactor fluidized bed, made of stainless steel, with internal diameter of 78 mm and 1069 mm height. The fast pyrolysis of soy hulls, mixed with inert (sand), was carried out at approximately 550 °C. Atmosphere with high nitrogen concentration was used. The present study aimed to investigate the chemical composition of the soy hulls bio-oil using gas chromatography and mass spectrometry techniques.

Abstract: One of the unresolved issues in using the gasifier is the inability to determine the occurrence of the transition regime of fluidized bed. In modeling gas-solid phase, drag force is one of the main mechanisms for inter-phase momentum transfer. Thus, a simulation of fluidized bed was developed to study the effect of using various drag models over different bed height of H/D ratio such as 0.5, 1 and 2. A two dimensional model using Eulerian-Granular Multiphase Model (EGM) based on two fluid models have been used to simulate hydrodynamics of a bubbling fluidized beds. Gas-solid interactions are modeled via inter-phase of a drag model. The drag correlations of Gidaspow, Wen Yu, Syamlal-O'Brien, Hill Koch Ladd (HKL) and Representative Unit Cell (RUC) were implemented to simulate the interaction between phases. From this study, we found that different H/D ratio such as 0.5, 1 and 2 yields different volume fraction as increasing bed height slows kinetic transport of particle sand to the upper side of the bed. Besides that, different H/D ratio also resulted in different velocity vector. The results also show that Wen Yu and Syamlal-O'Brien are sufficient enough in detecting the change from one regime to another regardless of the bed height.

Abstract: The experiments were carried out to investigate combustion characteristics of RBL droplets (RBLD) and RBL particles (RBLP) in fluidized bed. The combustion experiments were focused on the influence of six different bed temperatures in the ranging from 530 to 780°C on gas production rates, yields of product, carbon and hydrogen conversions, releases of Na, K and Cl and emissions of NO_x and SO₂. The experiments results indicate that the combustion behaviors of RBLD and RBLP mainly depend on bed temperatures. The conversions and emissions have linear relation with bed temperature, respectively. And denitrification and desulfurization processes must be had during incinerate RBL in industry application.

Abstract: Consider a two-phase liquid-solid coupling effect, using Euler - Euler two-fluid model is solved using standard viscous term with k-ε model and the velocity pressure coupling a simple algorithm to simulate liquid-solid two-phase flow characteristics of the fluid flow method bed, the applicability of the model to assess the drag. Different effects of a two-stage flow characteristics of fluidized bed flow characteristics, fluid and operating conditions affect the physical properties of the paper. We found from the simulation is the use of different drag coefficient models will greatly affect the results, which drag force model Syamlal - O'Brien is more suited to study the coupling characteristics of liquid flow in a fluidized bed of solid than Gidaspow. And velocity of the inert particles increase with the viscosity of the liquid increase. Further, the maximum speed of the inert particles in a fluidized bed by a central, which means the settling velocity in the fluidized bed of inert particles is the slowest; increasing liquid density and lead to increased speed of the inert particles; volume of the inert particles Score changes can also affect the speed of the particle velocity distribution, and there is no linear relationship.

Abstract: This study investigates the effect of pyrolysis temperature on the yields of char, organic compounds, water and gas. Fast pyrolysis was carried out in a fluidized bed reactor of 108 mm in internal diameter operated at 400, 450, 500 and 550 °C with nitrogen gas with flow rate of 25 L(NTP)/min. In specific the effect of temperature on the yields of known and unknown organics in bio-oil is discussed. For higher total organics, 500 oC was favorable. But higher phenol and acetic acid yields, 450 oC was preferable. The major organics include acetic acid, phenol and furfural. The minor ones include 2-methylphenol, 4-methylphenol, 4-methylnaphthalene, benzene, toluene and THF.

Abstract: The focal intention of this research was to investigate the factors influencing the coating thickness of urea granule by using modified biopolymer which performed in a tangential fluidized bed. The effects of inlet air temperature, disc rotation speed and spraying rate on coating thickness of urea granule were investigated. In this study, the results showed that the significant process parameters which effect the coating thickness was spraying rate (58.585%), followed by disc rotation speed (21.579%) and inlet air temperature (18.883%). The optimized process parameters in this work were 40⁰C for inlet air temperature, 40 rpm for disc rotation speed and 2 rpm for spraying rate. The confirmation run for this work had verified the conclusion from the variance analysis.

Abstract: This study investigates the effect of biomass size on the yields of char, liquid (organic compounds and water) and gas for fast pyrolysis of palm kernel shell (PKS). Fast pyrolysis was carried out in a fluidized bed reactor of 108 mm in internal diameter operated at 450 °C using three different sizes of palm kernel shell (0.325, 0.75 and 1.5 mm). In specific the effect of biomass size on the yields of known and unknown organics in bio-oil was mainly investigated. The major organics include acetic acid, phenol and furfural. The minor ones include 2-methylphenol, 4-methylphenol, 2-methylnaphthalene, benzene, toluene and tetrahydrofurane (THF). Smaller biomass sizes were favorable for higher bio-oil yields.

Abstract: To study the fluidization properties and mixing properties of binary mixtures of quartz sand and coal char, the experiments were carried out in fluidized bed with an inner diameter of 50 mm. The pressure drop lines and mixing index were obtained under different operating conditions with changing the static bed height and the volume fraction of coal char. A new formula of mixing index was proposed to consider the difference of horizontal mixing behavior. The result showed that the static bed height does not make an appreciable influence to minimum fluidization velocity and fluidization status. However, the volume fraction of coal char affected the minimum fluidization velocity obviously, and the minimum fluidization velocity decreased monotonously with decreasing the volume fraction. Although the small volume fraction of coal char was good for mixing, the effect was limited by the height of bed and the mixing index becomes constant almost at 80mm static bed height when the volume fraction was less than 0.4.