Bitumen recovery from Jordanian oil sand by froth flotation using petroleum cycles oil cuts

Jordan has huge reserves of energy sources such as oil sand, oil shale, and olive cake. This work presents a part of an ongoing project to develop an appropriate low cost beneficiation technology for Jordanian oil sand. This study presents the utilization of a modified fluidized froth flotation process for beneficiation and bitumen recovery from Jordanian oil sand. This modification includes fluidization technology to replace the agitation process found in a typical flotation technology. Results of this research show that the recovery of bitumen from Jordanian oil sand reaches its maximum of 86% during the addition of 0.35 wt% of a special cut of light cycle oil as a collector. The results show that the amount of hydrocarbon content (H.C) in oil sand has a minimal impact on floatability of oil sand. In addition, the results show that increasing the temperature enhances the bitumen recovery from Jordanian oil sand. The addition of NaOH is found to have a similar effect of increasing bitumen recovery. The results show that a special cut of cycle oil increases the bitumen recovery more than the normal cut of cycle oil.     

Experimental study of torrefied pine as a gasification fuel using a bubbling fluidized bed gasifier

Torrefied biomass has higher C/O ratio, resulting in improved heating value and reduced hygroscopic nature of the biomass, thus enabling longer storage times. In the southeastern United States, pine is has been identified as a potential feedstock for energy production. The objective of this study was to understand the performance of torrefied pine as a gasification fuel in a bench-scale bubbling fluidized bed gasifier. The gasification of torrefied pine was carried out at 790, 935 and 1000 °C and three equivalence ratios (ERs: 0.20, 0.25 and 0.30). The effect of process variables were studied based on i) products yield, ii) syngas composition iii) syngas energy content, and iv) contaminants. The mean concentration of CO increased with an increase in temperature, but was not statistically significant. On the other hand, H₂ concentration increased whereas CH₄ concentration decreased significantly with an increase in temperature from 790 to 935 °C. Further, with an increase in ER from 0.20 to 0.30, only CO₂ concentrations increased in the syngas. Results from torrefied pine were compared with raw pine gasification, and it was observed that torrefied pine gasification led to much higher char yield (more than twice) than pine; however, it produced less than half as much tar.     

An experimental study for a combined system of tar sand, oil shale, and olive cake as a potential energy source in Jordan

Jordan is an example of a third world country that is non-oil producing but contains huge reserves of other energy sources such as tar sand, oil shale, and olive cake. Some limited research is available about how to utilize these energy sources in pure form. However, available research does not deal with combinations of these energy sources. This experimental study investigates combinations of these energy forms as potential energy sources in Jordan. The experimental procedure involves characterization of samples by proximate analysis, calorific value determination of different combinations, and a compacting process of the different particles. The best combination, with respect to calorific value, is found to be 20% tar sand, 20% olive cake, and 60% oil shale. Compacting materials either with starch or with heated tar sand up to 110°C for 1 h indicates a feasible process for handling, packaging, and transporting.     

Combined-gasification of biomass and municipal solid waste in a fluidized bed gasifier

Due to the environmental problems associated with burning of fossil fuels and population growth, more attention has been paid to develop renewable energies in recent years. Among all options for renewable energy utilization, biomass gasification is more popular because of environmental benefits and economic issues. In the present study, a series of experiments were carried out to study the influence of blending ratio, reaction temperature, equivalence ratio (ER) on co-gasification characteristics of pine sawdust (SD) and municipal solid waste (MSW). By increasing the blending ratio from 100% SD to 100% MSW, CO and CH₄ respectively increased from 16.7 to 18.8 vol% and from 4.1 to 5.1 vol%, while an opposite trend was found for H₂ and CO₂. Over the ranges of the experimental conditions used, the tar content and gas yield varied from 5.4 to 10.1 g/Nm³ and 1.34 to 1.15 Nm³/kg, respectively.     

Experimental study on influence of operating parameters on tar components from corn straw gasification in fluidized bed

Gasification is a promising approach for converting solid fuel sources, including renewable ones like biomass, for use. The main problem in biomass gasification is the formation of condensable tars, including polycyclic aromatic hydrocarbons (PAHs). This paper investigated the conversion of tar components during corn straw gasification. It analyzed collected tar components using a gas chromatograph-mass spectrograph (GC-MS). Experimental results indicate that, with increasing temperature from 700°C to 900°C, the concentrations of benzene, indene, phenanthrene, naphthalene, acenaphthylene, fluorene, and pyrene increased whereas those of toluene, phenol, 1-methylnaphthalene, and 2-methylnaphthalene decreased. As the equivalence ratio (ER) increased from 0.21 to 0.34, the concentrations of indene and phenanthrene increased from 0.148% and 0.087% to 0.232% and 0.223%, respectively. Further, the phenol content increased as ER increased from 0.21 to 0.26 and then decreased as the ER increased further to 0.34. Other parameters like the steam/biomass (S/B) ratio and catalyst also played a critical role in tar reduction. This paper demonstrates the conversion of some tar components and elucidates their chemical properties during gasification.     

Biomass gasification in a 100 kWth steam-oxygen blown circulating fluidized bed gasifier: Effects of operational conditions on product gas distribution and tar formation

Biomass gasification is one of the most promising technologies for converting biomass, a renewable source, into an easily transportable and usable fuel. Two woody biomass fuels Agrol and willow, and one agriculture residue Dry Distiller’s Grains with Solubles (DDGS), have been tested using an atmospheric pressure 100 kWth steam-oxygen blown circulating fluidized bed gasifier (CFB). The effects of operational conditions (e.g. steam to biomass ratio (SBR), oxygen to biomass stoichiometric ratio (ER) and gasification temperature) and bed materials on the composition distribution of the product gas and tar formation from these fuels were investigated. Experimental results show that there is a significant variation in the composition of the product gas produced. Among all the experiments, the averaged concentration of H₂ obtained from Agrol, willow and DDGS over the temperature range from 800 to 820 °C was around 24 vol.%, 28 vol.% and 20 vol.% on a N₂ free basis, respectively. A fairly high amount of H₂S (∼2300 ppmv), COS (∼200 ppmv) and trace amounts of methyl mercaptan (<3 ppmv) on a N₂ free basis were obtained from DDGS. Due to a relatively high content of K and Cl in DDGS fuel, an alkali-getter (e.g. kaolin) was added to avoid agglomeration during gasification. Higher temperatures and SBR values were favorable for increasing the mole ratio of H₂ to CO and the tar decomposition but less advantageous for the formation of CH₄. Meanwhile, higher temperatures and SBR values also led to higher gas yields, whereas a higher SBR caused a lower carbon conversion efficiency (CCE%), cold gas efficiency (CGE%) and heating values of the product gas due to a high steam content in the product gas. From solid phase adsorption (SPA) results, the total tar content obtained from Agrol was the highest at around 12.4 g/Nm³, followed by that from DDGS and willow gasification. The lowest tar content produced from Agrol, willow and DDGS using Austrian olivine (Bed 1) as bed materials was 5.7, 4.4 and 7.3 g/Nm³, values which were obtained at a temperature of 730, 820 and 730 °C, SBR of 1.52, 1.14 and 1.10, and ER of 0.36, 0.39 and 0.37, respectively.     

A study of heat transfer in a circulating fluidized bed

An experimental investigation was carried out to study the effects of operating parameters on the local bed-to-wall heat transfer coefficient in a 4.5 m tall, 0.150 m diameter circulating fluidized bed with a bed temperature in the range of 65°C to 80°C, riser flow rate varying from 1400 litres/min to 2000 litres/min, bed inventory in the range of 15 kg to 25 kg of sand, and average sand sizes of 200 μm, 400 μm and 500 μm. A heat flux probe was attached to the riser wall at five different vertical locations for measuring the heat flux from the bed to the wall surface. From the present work, the heat transfer coefficient in the dilute phase was found to be in the range of 62 to 83 W/m²K, 51 to 74 W/m²K, and 50 to 59 W/m² K for sand sizes of 200 μm, 400 μm and 500 μm, respectively. Relevant mathematical correlations were developed to predict local heat transfer coefficient based on the results of the practical work.     

Recent experimental advances on the utilization of biochar as a tar reforming catalyst: A review

Biomass gasification to form syngas is a promising renewable energy production process. Here, biomass is exposed to high temperatures in an oxygen-controlled environment where volatiles react to form components of syngas that can be used for energy or chemical production. A limitation to the use of gasification is the generation of tars that condense in downstream equipment causing damage and halting production. Currently tars are removed by physical, thermal, or catalytic processes, all high-cost options. On the other hand, biochar is produced as a solid by-product of gasification, characterized by high surface area, desirable adsorption properties, and relatively low cost. This review details the use of biochar as a catalyst to reform tars, while highlighting recent experimental advances in evaluating the effects of biomass composition, gasification conditions, and pre-treatment and post-treatment options to improve catalytic function. It discusses tar degradation mechanisms and catalyst deactivation and recommends further areas for research.     

A study of solid circulation rate in a circulating fluidized bed

An experimental investigation under cold condition was made to study the effects of some operating/design parameters and non-mechanical L valve configuration on the solid circulation rate in a 4.5 m tall, 0.15 m diameter circulating fluidized bed with riser flow rate varying from 1400 litres/min to 2000 litres/min and bed inventory from 15 kg to 25 kg of sand of average sizes 200 μm, 400 μm and 500 μm. Solid circulation rate was estimated by measuring velocity of sand particle travelling through a vertical Perspex tube section at the bottom of the return leg. It was found to be in the range of 2.8 to 12.3kg/m²s, 0.07 to 9.1kg/m²s and 0.12 to 2.23kg/m²s for sand sizes of 200 μm, 400 μm and 500 μm, respectively for a horizontal L valve. Two mathematical correlations have been developed from the experimental results to predict solid circulation rate as a function of riser flow rate, aeration flow rate, total bed inventory and particle size used.     

A parametric study on isobaric adsorption process in a closed adsorbent bed

A numerical study on heat and mass transfer in an annular adsorbent bed filled with adsorbent granules for an isobaric adsorption process is performed. In order to reduce the number of independent parameters that influences heat and mass transfer in the bed, the governing equations and related initial and boundary conditions for the problem are non-dimensionalized and this yields two dimensionless parameters as G and Γ. The G dimensionless parameter is the ratio of heat of adsorption to sensible heat stored by adsorbent particle and Γ parameter compares mass diffusion within the adsorbent particle and heat diffusion in the radial direction of the adsorbent bed. The obtained results show that the total dimensionless time for an adsorption process can be reduced by increasing of Γ value. The total dimensionless time is independent from G for low values of Γ (i.e. Γ = 10^− 5). The results also show that the instantaneous equilibrium model can provide accurate results only for an adsorbent bed with a low value of Γ (i.e. Γ = 10^− 5). The present study is performed for Γ values from 10^− 5 to 1 and G value from 1 to 100.     

Influences of equivalence ratio,oxygen concentration and fluidization velocity on the characteristics of oxygen-enriched gasification products from biomass in a pilot-scale fluidized bed

The influences of equivalence ratio (ER), oxygen concentration (OC) and fluidization velocity (FV) on the gasification performance in a pilot-scale fluidized bed with capacity of 1 ton biomass (the mixture of agricultural residue) per day were investigated using oxygen-enriched air as gasification agent and high-alumina bauxite as bed material. The characteristics of syngas (lower heating value (LHV), gas yield (Y), carbon conversion (CC) and cold gas efficiency (CGE)), bio-char (LHV and Proximate analysis) and tar (tar yield and LHV) were used to evaluate the gasification performance in this study. The results showed that 0.161 was the optimal ER due to the high quality of syngas produced and relatively lower tar generation with ER changing from 0.115 to 0.243 at OC ≈ 40% and FV ≈ 1.20.29.7% was the optimal OC due to the highest Y and CC and relatively low tar generation when OC varied from 21% to 44.7% at ER ≈ 1.40 and FV ≈ 1.15. Although higher FV could improve syngas quality, it also resulted in the higher tar yield and heavier wear, therefore, the optimal gasification performance was achieved at moderate FV (FV = 1.13). This study proved that oxygen-enriched gasification in a large-scale fluidized bed was an effective option to produce gaseous biofuels with high quality.     

Experimental study on cotton stalk combustion in a circulating fluidized bed

This paper summarizes the results of an experimental study on cotton stalk (CS) combustion in a circulating fluidized bed. The mixing and fluidizing characteristics of binary mixture of CS with 10–100 mm in length and alumina bed material with a certain size distribution in a cold test facility were studied. The results show that CS by itself cannot fluidize, and adding inert bed material can improve the fluidization condition. CS can mix well with alumina at fluidization number N = 3–7. As N is more than 7, there will exist a little more segregation. The study concerning combustion characteristics of pure CS was performed on a circulating fluidized bed with a heat input of 0.5 MW. The effects of fluidizing velocity, secondary air flow and gas flow to the loop seal on the bed temperature profiles were investigated. Although there is a little more segregation at N higher than 7 in the cold tests, the hot experimental results indicate that slight segregation has little effect on the steady combustion of the dense region. In this study, the concentrations of major gaseous pollutants (CO, SO₂ and NO) in flue (stack) gas were measured.     

自激式脉动流化床流化脉动特性的试验研究

试验研究了基于Rijke管的自激式脉动燃烧流化床的流化脉动特性。是否激起以基波为主的压力、声音等脉动信号是脉动的判断依据，因此试验主要研究了脉动的基波特性。脉动的压力值是激起的各次谐波声压和炉膛的原有压力的叠加，通过傅立叶转变对压力进行了频谱分析。实验还研究了不同床层高度和流化风速对脉动特性的影响，并定性分析了优化流化脉动，减少声损失的途径。     

Hydrodynamics of air–sand flow in a conical swirling fluidized bed: A comparative study between tangential and axial air entries

Hydrodynamic regimes and characteristics of air–sand flow were studied in a cone-shape swirling fluidized bed for two types of air entry, or swirl generator: through a four-nozzle system (tangential entry) and using an annular-spiral air distributor (axial entry). Quartz sand of four particle sizes, 180–300, 300–500, 500–600 and 850–1180 μm, was used as the bed material in experimental tests on a cold model of a conical swirling fluidized bed combustor. During each test run, the pressure drop across the bed (Δp) was measured versus superficial velocity at the lower bed basis (u) for three static bed heights (20, 30 and 40 cm). Four regimes were found in the bed behavior for both swirl generators. The Δp–u diagrams were compared between tangential and axial air entries for different operating conditions. Mathematical models for predicting major hydrodynamic characteristics, the minimum fluidization velocity (u_mf) and corresponding pressure drop across the bed (Δp_mf), were empirically developed. The dimensionless dependency of Δp/Δp_mf on u/u_mf showed the apparent common trends and similarity for most of the test trials. For the two air injection systems, a Nomograph for assessment of Δp at any arbitrary superficial velocity and bed height was proposed as well.     

A cold model experimental study on the flow characteristics of bed material in a fluidized bed bottom ash cooler in a CFB boiler

IntroductionA fluidized bed bottom ash cooler is often used totreat high temperature bottom ash to reclaim heat andfine particles from the ash, and to have the ash easilytransported. Among the large CFB boilers in operation inthe world, there are many ash coolers that often workabnormally['-','].There are six fluidized bed bottom ash coolers in theimported 410im CFB boiler that was built and operatedin Gaoba power plant, Sichuan province, China in 1996N].High temperature slag-bond and jam …     

A numerical model of a fluidized bed biomass gasifier

A one-dimensional, steady state, numerical model was developed for a fluidized bed biomass gasifier. The gasifier model consists of a fuel pyrolysis model, an oxidation model, a gasification model and a freeboard model. Given the bed temperature, ambient air flow rate and humidity ratio, fuel moisture content and reactor parameters, the model predicts the fuel feed rate for steady state operation, composition of the producer gas and fuel energy conversion. The gasifier model was validated with experimental results. The effects of major mechanisms (fuel pyrolysis and the chemical and the physical rate processes) were assessed in a sensitivity study of the gasification model. A parametric study was also conducted for the gasifier model. It is concluded that the model can be used for gasifier performance analysis.     

A simple model for explosive combustion of premixed natural gas with air in a bubbling fluidized bed of inert sand

The combustion of premixed natural gas and air has been studied in a bubbling fluidized bed of inert particles. The temperature of the solids was carefully monitored, using 8 thermocouples, immersed in the bed at different heights. The observed temperature profiles were used to find the height above the distributor at which most of the combustion occurred and on this basis a clear distinction could be made between combustion above the bed and inside the bed. The region where most of the heat of combustion is evolved depends on the average bed temperature. If this temperature is low, the gases burn above the bed or just under its upper surface, but at higher temperatures the process is located close to the distributor. Rapid fluctuations in the measured temperature and pressure indicate that the process inside the bed is not a steady one. The model developed here assumes that combustion takes place inside bubbles of premixed gases, as they move through the bed. A detailed chemical kinetic model was used to calculate the induction period for ignition. The model can predict the height above the distributor at which bubbles should ignite and explode. Comparison of the experimental results with the modeling calculations indicates that the course taken by the process depends on temperature. At the lowest temperatures, the gases burn above the bed. In the high temperature range, where the bubbles ignite is determined by the induction period. At intermediate temperatures the location of the reaction is determined by the depth of the bed and bubble size, with ignition spreading from above the bed to bubbles, which are about to leave, but are still in the bed. That bubbles explode at different heights up the bed is reflected in the acoustic signals registered above and below the bed. The associated changes in the composition of the flue gases are also very characteristic.     

A study on heat transfer for immersed tube in internally circulating fluidized bed

INTRODUCTIONThemethodhowtodealwiththedomesticandindustrialwasteswithoutfurthercontaminationisoneofthemostimportantenvironmentalissues.Fluidizedbedcombustor(FBC)hasadvantagesofhighcombustionefficiency)lowpollution,convenienceinpreprocessingbeforefedin...     

A review on devolatilization of coal in fluidized bed

Devolatilization is an important step in fluidized bed combustion and gasification of coal. ‘Devolatilization’ is a general term that signifies the removal of volatile matters from the coal matrix. It is an extremely important step because the combustion of volatile matter can account for 50% of the specific energy of fluidized bed combustion of a high‐volatile coal. Significant insights into the complex physicochemical phenomena that occur during devolatilization have been obtained in the recent years. This review focuses on the devolatilization of coal in an inert gas, air, and oxygen‐enriched air, with emphasis on the effects of the operating parameters (e.g. temperature, heating rate, pressure, and gas velocity) on the yield of volatile matter. Particle size, oxygen content of the fluidizing gas, volatile content of coal and specific heat are some of the other important parameters for the devolatilization of coal. This review also explains the development and application of structural and empirical models. The structural models (e.g. FG‐DVC and CPD models) are fairly complex. However, they can accurately predict the yields of gas and tar. It is observed from the review of the literature that the mechanism of coal devolatilization needs further study. Although the shrinking‐core model can describe the devolatilization in the beginning and toward the end of the process, major deviations are often observed. The economic studies reveal that the capital cost of fluidized bed combustion reduces upon doubling the capacity. Some problems associated with bubbling fluidized bed combustion (e.g. the increase in freeboard temperature) have been explained with the present knowledge of devolatilization. Copyright © 2011 John Wiley & Sons, Ltd.     

A model of the dynamics of a fluidized bed combustor burning biomass

A dynamical model of an atmospheric, bubbling, fluidized bed combustor of biomass is presented. The model, based on one previously developed for the steady combustion of high-volatile solids, accounts for the fragmentation and attrition of fuel particles, the segregation and postcombustion of volatile matter above the bed, as well as thermal feedback from the splashing region to the bed. The model was used to assess how the dynamic behavior of the combustor varies with some of the operating parameters. To this end, a bifurcation analysis was first used to study the influence of selected parameters on the number and quality of steady state solutions. Moreover, direct integration of the governing equations provided a simulation of the dynamic behavior of the combustor after perturbing the parameters. Results of the bifurcation analysis indicated that extinction may take place through limit point bifurcations when varying the moisture content of the biomass and the flow rates of feed or air. Dynamic simulations showed that the bed temperature changes slowly when a stepwise change is imposed on one of the parameters. Either a new steady state or extinction eventually results, depending on the stepwise change. While relaxation of the bed temperature occurs rather slowly, the dynamics of the splashing region and of the freeboard are much faster, due to the shorter time-scales associated with homogeneous oxidation reactions. The relaxation time of the bed is determined by the heat capacity of the fluidized solids and by the fraction of the heat released recycling to the bed as thermal feedback.