Rotary Drum Dryer Research Articles

Energy and exergy analysis of drying terebinth in a far infrared‐rotary dryer using response surface methodology

AbstractWater shows a strong tendency to absorb the energy of wavelengths of 3 and 6 µm, which are in the infrared (IR) range. Therefore, IR dryers are used to dry food and fruits that have a high‐water content. Thus, modeling and optimizing energy and exergy parameters of terebinth drying in an IR–rotary drum (RD) dryer were evaluated using the response surface methodology. Independent factors included IR power and rotary rotation speed, and response factors were specific energy consumption (SEC), energy efficiency (EFF), exergy efficiency (EXEFF), specific exergy loss (EXLOSS), and exergy improvement potential (EIP). According to the obtained results, the range of EFF and EXEFF was between 28.93%–9.11% and 0.88%–6.62%, respectively. As IR power and RD speed increased, SEC (123.75–39.21 MJ/kg), EXLOSS (3.97–2.97 MJ/kg), and EIP (3.62–1.009 MJ/kg) decreased, while EFF and EXEFF increased. The results obtained in this study showed that the optimal IR drying power is 616.39 W, and the optimal rotary rotation speed is 13.46 rpm.

Physicochemical and Sensory Properties of Arabica Coffee Beans of Arara cv. Dried Using Different Methods.

The coffee fruit is preferably harvested at the cherry stage, with high moisture and metabolic activity, and must then undergo a drying process for better preservation of the bean and its sensory attributes. In this context, this study aimed to characterize the final quality of the Arara cultivar Arabica coffee processed using the wet method and subjected to six drying methods: three conducted at the agro-industrial establishment (fixed-bed dryer, rotary drum dryer, and combined drying) and three laboratory-scale methods (convective oven, cast-tape drying, and suspended terrace). Drying was carried out to reduce the coffee's moisture content from an initial value of 46.2% on a wet basis (w.b.) to a final average value of 11.35% (w.b.). The fruits of in natura demucilaged coffee and the processed dry coffee beans were characterized for moisture, ash content, nitrogen compounds, lipids, total titratable acidity, organic acids, sugars, and the instrumental color of the beans. The sensory profile of the Arabica coffee was evaluated by five coffee specialists using the methodology proposed by the Specialty Coffee Association (SCA), and all the coffees were classified as a specialty.

Hazard and Operability Study of Rotary Drum Dryer in Hazardous Waste Management Industry

Abstract: The HAZOP study is distinguishing the Hazards related to process, equipment and working methods and evaluate the probability take control measures to protect the workers and company asset. in this project analysand details hazards and Operation failure modes to affect the production and legal requirements. Such as The Atmospheric gas monitoring equipment needs to be installed around the machines to detected LEL and TVOC compounds to eliminate environment concern and Worker’s health. the overall purpose of the study to identify the hazards and risks, then remove/minimize the hazards by providing recommendation control measures. And Create danger free zone workplace. In this paper I have used quantitative and quantitative methods used to find the Operation failures and Possible Hazards. I have analyzed and exam pined the work/process locations is has more hazards to work more difficult even though in good housekeeping and preventive measure.

Mathematical Modelling of Rotary Drum Dryers for Alfalfa Drying Process Control

Rotary drum dryers operating in co-current mode are commonly used for drying food and feed in leaf form, reducing the damage caused by the high air temperatures typical of these dryers, as well as providing advantages including reduced drying times and increased energy efficiency. However, drying control to ensure a desirable product exit moisture content is strongly based on empirical practices, which are usually jealously guarded by producers and users, grounded in simplified mathematical modelling. To overcome these uncertainties, in this work, a more complete mathematical modelling approach, based on the solution of ordinary differential equations (ODEs), is developed. The ODEs describe the drying process in the drum dryer, where the air is continuously cooled and humidified as the product dries. The mathematical model developed was experimentally verified in a drum dryer by drying alfalfa, and the maximum relative error was found to be only 2.4%. Finally, a comparison between the complete model proposed here and a simplified model was conducted, using both for drying control to keep the product exit moisture content constant (i.e., at 0.111). The results indicated that the simplified model provided values of air inlet temperatures erroneously higher, up to +8.2%, with a consequent higher energy consumption, lower dried alfalfa quality, and a greater risk of fire, given that the product exit temperature was dangerously increased.

Dual objectives of forage drying and insect disinfestation

Rotary drum dryers are used to dry forage crops prior to compacting the dried biomass into compressed bales. Compressed bales are desirable for long distances transport. In Canada, forage grown in the field may blend with agropyrons and wheat plants that are host to pupae stage of quarantine insect Hessian fly (Mayetiola destructor, Say). A few of the importing countries like Japan and The Republic of South Korea specify that a dryer could destroy the insect, provided that the material is maintained above a certain temperature and for a specific duration. A field trial on a commercial rotary drum dryer operating in a hay processing plant in Rolling Hills, Alberta, was conducted. The tests established that the biomass experienced a temperature larger than 90°C for a period of longer than 100 s when the chopped hay passed through the dyer. A longer residence time was predicted when a cascading model computed residence time in the dryer. A simple formula was developed to estimate the residence time from throughput and the holding mass capacity of the drum and the cyclone.

Design, development, and evaluation of rotary drum dryer for turmeric rhizomes (Curcuma longa L.)

AbstractTurmeric is a challenging crop to dry because of its heat sensitive volatile content and browning characteristics. In this study, a pilot scale biomass fired rotary drum dryer was developed for drying turmeric rhizomes. The drying experiments were conducted at 50, 60, and 70°C air temperatures at an air velocity of 2 and 3 m/s and the drum speeds of 6 and 9 rpm. The turmeric rhizomes dried at a faster rate at the operating conditions of 70°C air temperature, 3 m/s air velocity and 9 rpm drum rotational speed. Among the evaluated thin layer drying models, Page model comparatively gave higher R2 values (0.998), lower sum of square error (0.001), and root mean square error (0.01) values. The effective moisture diffusivity of turmeric in the rotary dryer ranged from 0.33 to 0.5 × 10−10 m2 s−1. The calculated activation energy of turmeric rhizomes was 19,338 kJ/kg mol−1. The higher curcumin, oleoresin, starch, and color values such as lightness, redness, and yellowness value of 4.92%, 16.5%, 58.09%, and 59.87, 28.43, and 74.21, respectively, was observed at 50°C, 9 rpm drum rotational speed and 3 m/s air velocity. The results indicated that the color of turmeric could be retained by drying at 50°C.Practical ApplicationsThe present scenario, turmeric has been considered as an important crop against COVID‐19 due to its antiviral properties and also food applications such as natural coloring agent and flavor enhancer. The unit operations involved in turmeric processing is washing, boiling, drying, polishing, and size reduction. The amount of curcumin content presents in turmeric decides its value. Drying is the time‐consuming process compared to other unit operations and has an impact over the quality parameters of turmeric. Sun drying is the main traditional drying method normally practiced by the farmers for bulk drying of turmeric rhizomes. However, the sun‐dried turmeric rhizomes lost its product value because of poor quality end product (dark yellowish brown color). This could be due to longer exposure of the product in sun causes change in the volatiles and color in turn degrades the market value and fetches lower price to the farmer. And also decreased drying rate, prolonged drying time, non‐uniformity, and lesser energy consumption are the other factors that degrades further the quality of the product. Hence, a drying technology should be identified to overcome the problems faced by the farmers and also to dry the bulk capacities of the turmeric rhizomes at low cost. Rotary dryers are capable of processing larger capacities of various agricultural products having wide range of thermophysical and aerodynamic properties. The current research focused on developing a rotary dryer to reduce the drying time and also to retain the quality that benefits both farmers and industries by providing good quality product.

An integrated gasification plant for electric power generation from wet biomass: toward a sustainable production in the olive oil industry

Abstract This research work proposes an integrated gasification plant for simultaneous generation of renewable electricity and drying of olive pomace, a thick sludge with a moisture content close to 60–70% (wet basis), which constitutes by far the most abundant by-product in the Spanish olive oil industry. Due to its massive rate of production and increasing associated transportation costs, olive pomace management currently represents a substantial expense for oil mills. The integrated gasification plant, which can be installed directly at oil mills, consists of a pelletizer, a downdraft gasifier under autothermal operation fueled with dried olive pomace pellets, a producer gas cooling and cleaning unit and a microturbine as power generation unit. The wet olive pomace continuously produced in oil mills is eventually dried in a co-current flow rotary drum dryer with the hot exhaust gases leaving the microturbine at temperatures close to 300 °C, allowing a self-sufficient operation of the integrated gasification plant. The integrated gasification plant was modeled using Aspen Plus® process simulator. The developed model was validated against experimental and simulation results of relevant works. Under optimum operating conditions, the electrical efficiency of the proposed plant is 18.8%, while the additional drying stage allows achieving an overall efficiency of 51.0%. Electricity consumption by the pelletizer and ancillary equipment represents 10–20% of the net electric power generation from the microturbine. However, since the integrated gasification plant is fueled with an inexpensive by-product of olive oil production that is massively produced on-site, the plant performance parameters are remarkably satisfactory.

A machine learning approach in drying of microalga Chlorella minutissima in a single rotary drum dryer for biodiesel production

Drying of Chlorella minutissima slurry was carried out in a single rotary drum dryer at varied drum surface temperature and rotational speed to achieve higher lipid yield for biodiesel conversion. Residual moisture content and lipid yield of the corresponding drum speed and drum surface temperature were mapped. Application of the machine learning tool classified the range of residual moisture content to be <10% (wet biomass) for high lipid recovery with an accuracy of 97%. Based on the drying time, lipid recovery, and energy consumption, drying at 80°C drum surface temperature with 0.3 rpm resulted ˃90% lipid recovery as compared to the bone-dried biomass. The energy consumption of 7.328 kWh for 1 kg of dried biomass was recorded with profound reduction in drying time as compared to oven and tray drying of algal slurry. The fatty acid methyl ester profile of C. minutissima biodiesel constituted higher proportion of saturated fatty acids followed by monounsaturated fatty acid and polyunsaturated fatty acids. Various fuel characteristics, namely, viscosity, density, free glycerin, triglycerides, diglycerides, monoglycerides, copper strip corrosion, flash point, cetane index, iodine value, calorific value, acid value, saponification value, phosphorous, sulfur, water, and ash contents were analyzed, and showed values within the specified limits of national and international biodiesel standards. Thus, considering the drying time, energy consumption, and lipid recovery with suitable fuel properties, the drum dryer could be recommended for drying the microalgal slurry for large-scale operation.

A computational approach to determine the residence time distribution of biomass particles in rotary drum dryers

Wood pellet manufacturing involves drying of wet biomass from 50% m.c. down to 5%–7% m.c. Rotary drum dryers are the most common dryers in pellet industry. Mis-prediction of biomass residence time leads to fires and low-quality products due to over drying or under drying. The current study uses a CFD and DEM modeling approach to determine the residence time of particles with properties similar to biomass feedstock in a rotating drum. The developed model uses a Lagrangian approach to track the 3D particle trajectory from drum inlet to the outlet. The novelty of the current model is that it includes the contribution of biomass interactions with drum wall and internal baffles, which is mostly missing in the published models. Particles with an increasing mass and aspect ratio stayed longer in the dryer than particles with an aspect ratio closer to unity.

A Novel Rotary Dryer Filled with Alumina Ceramic Beads for the Treatment of Industrial Wastewaters: Numerical Simulation and Experimental Study

In this study, a new type of rotary dryer filled with inert alumina ceramic bead (ACB) fillers was introduced to treat the industrial wastewater, e.g., the high-salt wastewater and landfill leachate. Numerical simulations based on the Discrete Element Method (DEM) on the motion trajectory of ACB fillers in the rotary dryer were conducted, and the parameters of flight structure, rotational speed, and filling degree on the dynamic behavior of ACB fillers were optimized. Under various rotational speeds and filling degrees, the experimental results fit the numerical-simulated results very well. The optimized flight configuration was the straight flights with a length of 65 mm, and the optimized rotational speed and filling degree were 35 rpm and 15%, respectively. Under the optimized condition, both the response variables, the mass of particles in the airborne phase (MAP) and the percentage of occupied area in the airborne region (OAR), have the optimal values, in which the dryer will have a better drying performance. Besides, the lower-right area of the drum is empty which is convenient for the installation of the inlet pipe. The drying experiments of industrial wastewaters were also studied using this ACB filled rotary drum dryer under the optimized conditions. Under the optimal operational conditions, the evaporation capacities of the high-salt wastewater and landfill leachate could reach as high as 49.7 kg/h and 90 kg/h, respectively. This study highlights the integration of evaporation and drying processes of this novel ACB filled rotary dryer and provides an efficient and zero-liquid-emission strategy for the thermal treatment of industrial wastewater.

A review on determining the residence time of solid particles in rotary drum dryers

Biomass material such as forest and agricultural residues are moist after harvest. Drying is an established operation to prepare them for pelletization. Wood pellet manufacturer involves drying wet biomass from mill residue or forest down to 5–7% wet-basis moisture content. Moisture reduction occurs conventionally in rotary drum dryers operating at high inlet temperatures of 300–600 °C. Although rotary dryers were initially designed to dry nonfibrous materials, these dryers have been used for drying grains, herbs, woody biomass, and agricultural wastes. Biomass materials have heterogeneous size, shape, and density properties, and their flow characteristics inside the drum are not a known phenomenon. This article reviews the researchers’ efforts to determine the residence time of solid material in concurrent rotary drum dryers. This review article analyzes the developed empirical correlations and solid cascading approximation to determine the residence time. The outputs of various empirical correlations are compared for a consistent operating condition.

Analysis and Comparison of Different Dewatering Methods On Salt Quality

The salt quality was studied by dewatering methods such as centrifugal hydro extraction, fixed bed dryer, and rotary drum dryer. The effect of different salt particle sizes was also analyzed. The centrifugal hydro extractor is found to be effective when reducing the high-water content of salt and suitable for reducing water content after the salt wash stage. Fixed bed dryers produce lower water content than rotary drum dryers. A water content lower than 1% can be achieved using fixed bed dryers. Finally, all dewatering methods such as centrifugal hydro extractors, fixed bed dryers, and rotary bed dryers are suitable for salt production methods. Reduced salt particle size from 30 to 60 mesh also improved the drying performance.

Flammability analysis of gaseous emissions from western red cedar and SPF (Spruce, Pine, Fir) sawdust

Western red cedar (WRC) is among the most valuable tree species in British Columbia. Application of WRC for pellet production is uncertain because unlike spruce/pine/douglas fir, WRC tends to combust in rotary drum dryers. The scientific reasons for the reported fire incident are not known. The goal of this research is to assess whether WRC has a higher tendency to emit combustible gases than SPF sawdust when these species of wood are heated. In controlled experiments, the composition of emitted gases during heating of WRC and SPF samples at 140 °C was measured. The GC-measured data showed that WRC released a lower amount of carbon monoxide, methane, and hydrogen than SPF. Flammability analysis showed that the concentration of the emitted gas mixture for WRC and SPF samples did not reach a flammable level. Theoretical calculations showed that the volumetric composition of carbon monoxide at 12%in the presence of ample oxygen is prone to combustion. This means that if the biomass smokes in the drum, the level of carbon monoxide might reach to flammable level.

Drying characteristics, specific energy consumption, qualitative properties, total phenol compounds and antioxidant activity during hybrid hot air-microwave- rotary drum drying of green pea

This study is aimed to investigate the effect of a hybrid hot air-microwave- rotary drum (HMRD) dryer on the thermal properties, quality and nutritional characteristics of green pea under different operational conditions. The experiments were conducted under different air temperatures (40, 55 and 70 °C), microwave power (90, 270, 450 and 630 W), and drum rotation speeds (5, 10 and 15 rpm). The thermal properties (e.g. drying time, effective moisture diffusion coefficient, activation energy, and specific energy consumption), quality features (color, shrinkage, and rehydration ratio) and nutritional properties (antioxidant activity and total phenol content) were determined. The results indicated that by increasing the microwave power, air temperature and drum rotation speed, the drying time will decline. The highest diffusion coefficient and energy consumption were determined as 5.04×10-11 m2/s and 109.91 MJ/kg, respectively. The lowest changes in the color, shrinkage, and rehydration were calculated as 41.34, 24.08% and 1.57. The highest total phenol (14.02 mg GAE/g d.w) and antioxidant (85.86%) were obtained. Thus the newly designed dryer can be employed for drying the granular products and lead to satisfactory results.

Development of Black Pepper Rotary Drum Dryer System

Rotary drum dryer has been identified as hygienic and practical method to dry black pepper. The quality of black pepper is defined based on the chemical properties and moisture content. This research aims to develop a control system for black pepper rotary drum dryer. The dried pepper should meet the specific 12% moisture content while the heating temperature must be kept below 550C. The requirement of 12% moisture content is equivalent to 30% of the remaining weight of the pepper (final weight). The developed system uses Arduino Mega 2560 REV board as a microcontroller. A type K thermocouple with MAX6675 thermocouple amplifier and S-type load cells (TAS501) with HX711 load cell amplifier are used as input sensor to microcontroller. The system keeps measuring the current weight until it hit the targeted final weight. Two set of experiments that are using 500 g and 1500 g of pre-treated pepper were conducted to verify the system. As a result, the dryer was successful to work within the desired temperature and it stop operating just after the samples reached 12% of the moisture content. The finding has proven a shorten of drying time from 4 to 7 days when using the traditional method to the current 3 – 5 hours only when using the developed system. Hence, this is an improved method achieved to a quick drying of the black pepper.

Life cycle assessment of low-temperature thermal desorption-based technologies for drill cuttings treatment

The life cycle impacts of treatment of typical oil-based drill cuttings (OBDCs) using three low-temperature thermal desorption (LTTD)-based systems, including thermomechanical cuttings cleaner (TCC), screw-type dryer (STD), and rotary drum dryer (RDD), were explored with a case study in British Columbia, Canada. Two energy supply scenarios, including diesel generator-based onsite (scenario i) and hydropower-based offsite (scenario ii) treatments, were considered in the assessment. The results show that RDD generated the lowest life cycle impacts in terms of damages to human health, ecosystems, and resources in scenario i. TCC-scenario ii generated the lowest impacts among all assessed cases, suggesting that using renewable energy can greatly reduce the impacts of LTTD-based OBDCs treatment. Also, net environmental benefits could be achieved considering the reuse of recovered oil, and the highest net environmental benefits were obtained in TCC-scenario ii. The process contribution analysis found that thermal desorption process accounted for 80–95 % of impacts in almost all impact categories. Energy consumption contours and linear regression models were also developed to help drilling waste managers estimate the life cycle impacts of using hydropower-driven TCC to treat OBDCs with different water and oil contents.

Starch gelatinization and drying of paddy using microwave rotary drum dryer: Optimization, kinetics, and cooking studies

The microwave-assisted starch gelatinization was carried out in a semi-pilot microwave rotary drum dryer. Gelatinization experiments were planned using a central composite design and the process was optimized. The effect of microwave power density, time of treatment, and water application rate on final moisture content, crystallinity percentage, and specific energy consumption was studied. The optimized conditions in the starch gelatinization process were found at 1 kW kg−1 power density, 60 min treatment time, and 90 mL/10 min water application rate. Microwave power density and treatment time significantly (p < 0.01) affected the crystallinity percentage and specific energy consumption. Further, the gelatinized paddy was dried in the same dryer at 0.25, 0.50, 0.75, 1.00, and 1.25 kW kg−1 microwave power density levels. The drying characteristics, milling yield, cooking characteristics and cooking kinetics of the milled rice were analyzed. Drying rates were increased with an increase in microwave power density. The head rice yield and specific energy consumption were lower in microwave drying compared with hot air drying. The crystallinity percentage of microwave dried rice was decreased with an increase in power density. At higher power density, the microstructure of starch granules showed formations of internal fissures as well as the effect on the color and cooking rate constants of the rice.

Heat transfer enhancement in rotary drum dryer by incorporating jet impingement to accelerate drying rate

The purpose of this study was to investigate experimentally the effects of impinging jets installed in a conventional rotary dryer for heat transfer enhancement. The metal drum had as insert a jet tunnel at the centerline, and the jets were arranged in an in-line configuration on the jet tunnel. A jet-to-jet (S) and a jet-to-target (H) distances were fixed at S/d = 6 and H/d = 4, respectively. Jet velocity (Vj ) was set at Vj = 5, 10 and 15 m/s, while jet temperature (Tj ) was 70, 80 or 90 °C. Drum rotation speed (N) was also investigated at N = 0.5, 1, and 3 rpm. The conventional rotary dryer was examined at the same mass flow rate of hot air to compare with the case having impinging jets. All experiments were conducted by batch drying 5 kg of fresh chilies for 8 hours. Results showed that installing jets gave more effective heat transfer, which accelerated water removal over that with the conventional rotary dryer, and the moisture contents were greatly reduced. On using impinging jets, the jet temperature had more influence on heat transfer enhancement than the jet velocity. In comparison, the effect of drum speed was small.

THE EFFECT OF THE FILLING RATIO ON THE OPERATING CHARACTERISTICS OF AN INDIRECT DRUM DRYER

This article investigates the effect of the filling ratio of the indirect rotary dryers on their operating characteristics. For moist biomass drying before combustion, the use of indirect drum dryers heated by a low pressure steam has proven to be highly suitable. Regarding the design of new dryers, it is necessary to experimentally verify the operating characteristics for specific materials and drying conditions. For this purpose, a set of experiments on a steam heated rotary drum dryer were carried out with green wood chips containing 60 to 66 wt% of moisture. The following operational characteristics of the dryer were experimentally determined: drying curves describing the process, square and volumetric evaporation capacities and drying heat consumptions. Based on the experimental results, the effect of various drum filling by dried material on the mentioned operating characteristics was analysed. On the one hand, higher drum filling ratio increases the drying time, on the other hand, the evaporation capacity also increases, while the specific energy consumption does not significantly alter. The maximum value of the evaporation capacity was reached when the drum was filled to 20 wt%. When the filling ratio was increased to 25 wt%, the evaporation capacity experienced almost no change.

Comparison of Drying Rates of Ground Western Red Cedar with Hemlock, Birch, Aspen, and Spruce/Pine/Douglas Fir

HighlightsWRC and SPF generate the largest fraction of small particles (&amp;lt;0.5 mm) during grinding.WRC is slightly low in total sugars, high in lignin content (should make durable pellets), and high in extractives.Aspen followed by WRC has the highest drying rate and the shortest drying time amongst all samples.Smoke point is similar for all wood species and is ~180°C.Abstract.Western red cedar () and yellow cedar () are among the most valuable tree species in British Columbia. These species make up about 20% of the coastal timber volumes and mostly are used as lumber for construction applications where resistance against decay is important. The use of red cedar for pellet production has been uncertain because it appears cedar has a tendency to cause fires in rotary drum dryers when compared to other wood species like pine and Douglas Fir. The scientific reasons for the reported fire incident are not known. The goal of the current study is to investigate the drying rates and the range of combustion temperature for western red cedar and five other wood species that either are used or have potential to be used for palletization purposes in British Columbia. Red cedar and Spruce/Pine/Fir (SPF) generate the largest fraction of small particles (&amp;lt;0.5 mm) during grinding. Almost 93% of cedar particles are less than 1 mm. Cedar has a high carbon content and low oxygen content that causes cedar has higher calorific value than other species. During a drying process, aspen following by cedar has the highest drying rate and the shortest drying time amongst all samples. The smoke point is similar for all wood species and is ~180°C. So, in the case of high temperature drying (beyond the smoke point) of mixed feedstocks with similar size, red cedar dries faster and starts smoking at dryer output. Keywords: Chemical composition, Drying rate, Physical characterization, Smoke point, Western red cedar.