Investigation of Hydrodynamics, Kinetics, Energetic and Exergetic Aspects of Fluidized Bed Drying of Rough Rice

2014 ◽  
Vol 10 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Majid Khanali ◽  
Shahin Rafiee
Keyword(s):  
Fluidized Bed ◽  
Air Temperature ◽  
Initial Moisture Content ◽  
Experimental Conditions ◽  
Fluidization Velocity ◽  
Solid Holdup ◽  
Increase With Increase ◽  
Rough Rice ◽  
Energy And Exergy ◽  
Fluidized Bed Drying

Abstract The hydrodynamics, kinetics as well as energy and exergy analyses of fluidized bed drying of rough rice under various experimental conditions were investigated. Drying experiments were conducted at drying air temperatures of 55, 60, and 70°C, superficial fluidization velocities of 2.3, 2.5, and 2.8 m/s, solid holdups of 0.66 and 1.32 kg, and rough rice initial moisture content of 0.25 d.b. Various popular drying models were used to fit the drying data. It was found that the fluidized bed hydrodynamics of the rough rice was uniform and stable. The drying rate was found to increase with increase in drying air temperature and superficial fluidization velocity, while decreased with increase in solid holdup. Statistical analyses showed that the Midilli et al. model was the best model in describing fluidized bed drying characteristics of the rough rice. The results showed that the values of energy efficiency were higher than the corresponding values of exergy efficiency during the entire drying process. Furthermore, at initial stage of drying, the energy and exergy efficiencies were higher than those at the end of drying. It was also found that both the energy and the exergy efficiencies increased with increasing drying air temperature and solid holdup, whereas decreased with the increase in superficial fluidization velocity.

scholarly journals Challenges and Opportunities Associated with Drying Rough Rice in Fluidized Bed Dryers: A Review

2020 ◽  
Vol 63 (3) ◽  
pp. 583-595 ◽  
Author(s):  
Kaushik Luthra ◽  
Sammy S. Sadaka
Keyword(s):  
Developing Countries ◽  
Moisture Content ◽  
Fluidized Bed ◽  
Airflow Rate ◽  
List Type ◽  
Rice Quality ◽  
Drying Temperature ◽  
Rough Rice ◽  
Energy And Exergy ◽  
Fluidized Bed Drying

Highlights Fluidized bed drying of rice has several advantages that outweigh its disadvantages. Increasing the drying temperature above 60°C could reduce rice quality. Research related to energy and exergy efficiencies in fluidized bed dryers of rice is needed. Abstract. Rice (Oryza sativa L.) is a staple food for more than half the world’s population. World rice production reached approximately 740 million metric tons (MMT) in 2018 due to the ever-increasing demand driven by population and economic growth. Rice producers face challenges in meeting this demand, especially in developing countries where rice is prone to spoilage if the moisture content is not reduced to a safe level shortly after harvest. Rice producers, particularly in developing countries, typically use conventional drying methods, i.e., sun drying and natural air drying. These methods are time-consuming and environmentally dependent. On the other hand, fluidized bed drying, which is a well established technology, could provide rice producers with an effective drying technique that is quick, practical, affordable, and portable. Several innovative designs for fluidized bed dryers have been developed that could be installed on-farm or off-farm at a reasonable cost. Some studies have mentioned that the main advantage of fluidized bed drying is the increase in drying rate and the reduction of rice spoilage after harvest. Conversely, other studies have raised alarms regarding low rice quality, which is seen as a significant flaw of fluidized bed drying. Due to this lack of consensus, there is a great need to review this drying technology objectively. Therefore, this review article explores fluidized bed drying and details its advantages and disadvantages related to rice drying. It also sheds light on the effects of the operating parameters involved in fluidized bed drying, i.e., rice moisture content, drying temperature, airflow rate, air velocity, drying duration, and tempering duration, on dryer performance and rice quality. Several fluidized bed numerical models are also reviewed and evaluated. Additionally, this review explores the energy and exergy efficiencies of fluidized bed dryers and suggests opportunities for research associated with fluidized bed drying of rice. Keywords: Energy, Exergy, Fluidized bed drying, Fluidized bed modeling, Moisture content, Rice quality, Rough rice, Tempering.

Energy and Exergy Efficiencies of Fluidized and Fixed Bed Rice Drying

2021 ◽  
Vol 64 (6) ◽  
pp. 1943-1954
Author(s):  
Kaushik Luthra ◽  
Sammy Sadaka
Keyword(s):  
Fluidized Bed ◽  
Fixed Bed ◽  
Ambient Air ◽  
Exergy Efficiency ◽  
Energy Utilization ◽  
Rough Rice ◽  
Energy And Exergy ◽  
Fluidized Bed Drying ◽  
Drying System ◽  
Rice Drying

HighlightsFluidized bed drying of rough riceat 40°C with or without ambient air dehumidification worked best based on the energy and exergy utilization.The dryer lost exergy in the exit air, which was the primary cause of thermal inefficiency; recirculation of the exit air could improve the exergy efficiency.Ambient air dehumidification did not reduce the dryer’s energy utilization and exergy efficiency for rough rice.Abstract. Fluidized bed drying of rough rice in the U.S. has not been used to its full potential due to a lack of research to address rice quality impacts and energy consumption. Little research has been done to analyze the energy and exergy of fluidized bed drying of rough rice. Thermal analysis allows using the drying air’s energy better and improving the drying system’s thermal efficiency. In this study, energy utilization and energy utilization ratio were calculated using the first law of thermodynamics, while exergy loss and exergy efficiency were determined using the second law. Drying air temperature (40°C, 45°C, or 50°C), drying bed condition (fluidized or fixed), drying duration (30, 45, or 60 min), and ambient air dehumidification (yes or no) were the tested factors. A lab-scale drying system designed in a previous study was used. Three replicates were performed to minimize any bias or human errors. All factors significantly affected the energy and exergy of the drying process, except dehumidification and replication. The minimum and maximum energy utilization values were 0.01 and 0.55 kJ s-1 for fixed bed drying at 40°C for 30 min with dehumidification and fluidized bed drying at 50°C for 60 min without dehumidification, respectively. The minimum and maximum exergy efficiency values were 13.46% and 49.14% for fixed bed drying at 45°C for 45 min with dehumidification and fluidized bed drying at 40°C for 60 min with dehumidification, respectively. The primary cause of thermal inefficiency was attributed to the energy and exergy losses in the exit air, while the secondary source was the exergy and energy losses from the drying chamber and inlet air pipes. Costly solutions could be recirculation of the exit air and better insulation of the drying chamber and inlet pipes. However, using the optimal drying conditions for the energy and exergy utilization of the drying air is suggested. This study found that fluidized bed drying was better than fixed bed drying overall. At the primary drying stage, fluidized bed drying had a higher exergy efficiency, energy utilization, and energy utilization ratio than fixed bed drying. At 40°C, fluidized bed drying with or without ambient air dehumidification worked best based on the energy and exergy utilization of the drying system. Keywords: Dehumidification, Energy, Exergy, Fixed bed, Fluidized bed, Rice drying.

Solid Holdup Dynamics of a Step Change in Liquid Fluidization Velocity within a Liquid–Solid Fluidized Bed

2006 ◽  
Vol 39 (8) ◽  
pp. 798-806
Author(s):  
Di Li ◽  
Kei Mizuta ◽  
Kazuki Ishihata ◽  
Toshihiko Kamiya ◽  
Hidetomo Shirai ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Step Change ◽  
Fluidization Velocity ◽  
Solid Holdup ◽  
Liquid Fluidization

Study of Fluidized Bed Drying Method Used For Safe Storage of Rice And Its Analyais

2015 ◽  
Vol 3 (2) ◽  
Author(s):  
Rakesh Verma ◽  
Bharat Raj Singh
Keyword(s):  
Fluidized Bed ◽  
Air Temperature ◽  
Flow Rate ◽  
Material Flow ◽  
Rice Production ◽  
Rice Starch ◽  
Drying Rate ◽  
Drying Method ◽  
Safe Storage ◽  
Fluidized Bed Drying

Rice is used as a staple food by more than 60 percent of world population. The method used for Cooking of rice for eating purpose is most common and popular. Rice starch is used in making ice cream, custard powder, puddings, gel, distillation of potable alcohol, etc. It is used in confectionery products like bread, snacks, cookies and biscuits. The defatted bran is also used as cattle feed, organic fertilizer (compost), and medicinal purpose and in wax making. Rice is used as animal feed, fuel, mushroom bed, for mulching in horticultural crops and in preparation of paper and compost. Rice yields have been increasing since the 1960s, but since the 1990s, growth in rice production has been slower than population growth. Indeed, it is anticipated that rice production will need to increase by 30% by 2025 in order to sustain those who need it for sustenance. In the present work fluidized bed drying method used for safe storage of rice and analysis of rice conditions and we find that inlet air temperature has the most important effect on the drying rate of material, increasing the inlet air temperature increases the drying rate of the material. Inlet material flow rate has the most important effect on thermal efficiency. Increasing the inlet material flow rate increases the efficiency but decreases the drying rate. At lower flow rate of material, efficiency is low.

Energy and exergy analysis of industrial fluidized bed drying of paddy

Energy ◽  
2015 ◽  
Vol 84 ◽  
pp. 131-138 ◽  
Author(s):  
Md. Sazzat Hossain Sarker ◽  
Mohd Nordin Ibrahim ◽  
Norashikin Abdul Aziz ◽  
Mohd Salleh Punan
Keyword(s):  
Fluidized Bed ◽  
Exergy Analysis ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Fluidized Bed Drying

Experimental Research on Granule Moisture Measurement by Microwave Resonance Technology in a Fluidized Bed Dryer

2013 ◽  
Vol 544 ◽  
pp. 466-470 ◽  
Author(s):  
Yun Hui Xie ◽  
Lan Chen ◽  
Chun Hua Lin ◽  
Song Du
Keyword(s):  
Product Quality ◽  
Real Time ◽  
Fluidized Bed ◽  
Air Temperature ◽  
Flow Rate ◽  
Particle Density ◽  
Infrared Light ◽  
Microwave Resonance ◽  
Fluidized Bed Dryer ◽  
Fluidized Bed Drying

Drying is one of the most important methods for industrial processing while the granule moisture is a critical quality attribute (CQA) which has a significant influence on the finished product quality. In-line measurement of granule moisture during fluidized bed drying is getting more imperative to meet more stringent product quality specifications. Nowadays, several methods have been applied to measuring the granule moisture in-line. Comparing to other methods, microwave resonance (MR) technology provides more representative results due to its independency of both the particle density and the bed density. In the current study, one MR sensor was mounted onto an industrial fluidized bed dryer to monitor the real-time moisture of granules. The drying experiments were performed at different drying air temperatures and flow rates. The comparison between the results of in-line and off-line granule moisture measurements, namely MR technology and loss on drying caused by infrared light (LOD/IR), was presented. Furthermore, the influences of inlet air temperature and flow rate on the performance of the MR sensor were investigated. As a conclusion, the MR method, which is independent of the drying air temperature and flow rate, provided more accurate results when the granule moisture was below 25% (wet basis). Therefore, it is a promising method to be applied in real-time measurement of the granule moisture and predict the end-point in fluidized bed drying processes as well.

Fluidized bed drying of Loy Yang brown coal with variation of temperature, relative humidity, fluidization velocity and formulation of its drying rate

Fuel ◽  
2013 ◽  
Vol 105 ◽  
pp. 415-424 ◽  
Author(s):  
Hyun-Seok Kim ◽  
Yohsuke Matsushita ◽  
Motohira Oomori ◽  
Tatsuro Harada ◽  
Jin Miyawaki ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Fluidized Bed ◽  
Brown Coal ◽  
Drying Rate ◽  
Fluidization Velocity ◽  
Fluidized Bed Drying

scholarly journals Drying tea in a kilburn vibro fluid bed dryer

2014 ◽  
Vol 11 (1) ◽  
pp. 153-158 ◽  
Author(s):  
M Akhtaruzzaman ◽  
MR Ali ◽  
MM Rahman ◽  
MS Ahamed
Keyword(s):  
Moisture Content ◽  
Fluidized Bed ◽  
Dynamic Equilibrium ◽  
Initial Moisture Content ◽  
Drying Time ◽  
Fluidized Bed Dryer ◽  
Moisture Contents ◽  
Fluid Bed ◽  
Fluidized Bed Drying ◽  
Drying Curve

The fluidized bed drying principles for drying of tea in Bangladesh is thoroughly studied. The experiments were conducted to determine the drying curve, drying time, drying constant and dynamic equilibrium moisture contents of tea at the Bangladesh Tea Research Institute. Drying of tea in a fluidized bed dryer (Kilburn Vibro Fluid Bed Dryer) takes only 20 min for drying from an initial moisture content of 69.1% to a final moisture content of 2.8%. Temperatures of drying air were recorded to be 130°C at the inlet and 90°C at the outlet. The drying constant was found to be 31.05 h-1 and the dynamic equilibrium moisture contents were in the range of 18.3 to 2.0%. Finally the principle of fluidized bed drying was compared with the principle of conventional endless chain pressure type drying. DOI: http://dx.doi.org/10.3329/jbau.v11i1.18227 J. Bangladesh Agril. Univ. 11(1): 153-158, 2013

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