Rotary Dryer Research Articles

The effect of rotary drying temperature on drying characteristic and antioxidant activity of Etlingera elatior Jack

The study was conducted to investigate the effect of drying temperature on a rotary type of dryer for drying characteristics and antioxidant activity of Etlingera elatior flower. This study used a lab-scale rotary dryer which was a modification of the commercial oven heater from the market. The research design was a Randomized Block Design (RCBD) with one factor, i.e. the drying temperature, which consisted of four temperature levels, 60oC, 70oC, 80oC and 90oC. All experiments were repeated six times. The results showed that the drying of Etlingera elatior flowers at three different temperatures (70oC, 80oC and 90oC) required a shorter drying time than that of 60oC. The drying rate of the samples at 70oC, 80oC and 90oC was drastically decreased before the 200th min, while 60oC took a long time to 380 mins. The drying rate pattern with the drying temperature of 60oC showed a significantly lower total phenolic content of Etlingera flowers compared to 70oC, 80oC and 90oC, while there was no significant difference in total phenolic content among 70oC, 80oC and 90oC. In addition, different drying temperatures did not give a significant effect on the antioxidant activity based on the DPPH (2,2-diphenyl-1- picrylhydrazyl radical) method. This study proposed the effectiveness of drying using a rotary dryer in maintaining the total phenolic content and antioxidant activity of Etlingera flowers.

Thermal analysis of hot air drying of chicken manure pellets in a modified portable horizontal rotary dryer

Thermal analysis of hot air drying of chicken manure pellets in a modified portable horizontal rotary dryer

Numerical simulation of optimal inlet air temperature of a forced convective fish cabinet rotary dryer

Computational fluid dynamics was applied in the prediction of the effect of inlet temperature on the drying time of fish in a cabinet rotary dryer. On completion of the simulation, the temperature distribution of the air (fluid domain) within the drier at different inlet air temperatures and time intervals was obtained. Inlet air temperatures ranging from 35oC to 55oC was simulated for a time interval of 10 minutes to 120 minutes so as to examine the influence of inlet temperature on the drying process of fish. Based on this temperature range, it was observed that the ideal drying time for the fish which satisfies the condition for efficient fish drying for all five inlet air temperatures of the fish is 70 minutes. Furthermore, it can be observed that it takes about 120 minutes for the inlet air temperature of 50 degrees Celsius to attain a cabinet drying temperature of 316K (43°C) while it takes only 70 minutes for the inlet air temperature of 55 degrees Celsius to attain the same temperature under the same condition.

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.

Efficiency analysis of citrus waste biomass valorization using rotary dryer

Citrus residue is a large-scale agro-industrial biowaste that can become a source of renewable energy through drying. Drying demands high power consumption due to the low energy efficiency of this process in the industries. In this work, the energy performance of the drying process in a semi-industrial rotary drum of 2.7 m length and 0.45 diameter was analyzed. The main objective was to find the operational condition for the lowest energy consumption and also the highest energy, drying and exergetic efficiencies. The experiments were performed under different solid mass flow rates (0.2 and 0.4 kg/min) inlet air velocities (1 and 2 m/s) and temperatures (135, 145, and 155 °C). The average energy efficiency was 13.1% with 25.1% of drying efficiency, 37291.3 kJ/kg of specific energy consumption, and 37.3% of exergy efficiency. The results showed that the drying technique can be an interesting alternative to add value to the citrus residue.

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.

Optimization Design Analysis of Boiler Blowdown Utilization on A Rotary Coal Dryer with Drum Tilt Angle Variations

Lignite coal has dominated the use of steam power plants in recent years. Despite the consequences, which cause many problems, lignite is cheap and easy to obtain. One of the problems was mitigated by reducing the moisture content using a rotary coal dryer. Coal dryer is deemed uneconomical with the current energy sources from turbine extraction steam, electric heaters, and exhaust gas using large-powered fans. The waste energy from boiler blowdown, a water-vapored fluid discharged from the boiler to maintain water and steam quality, is being conducted to improve. Blowdown investigated in a rotary coal dryer type. The compressed air absorbed the heat from the blowdown through the steam coil. The hot air mixed with the coal in the rotary drum. A rotary drum was tested with the tilt angles of 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°. The research steps were designing, preliminary modeling, numerical analysis, prototyping, and experimental performing. The result shows that the moisture content has decreased significantly from 35.37% to 21.28%, within an angle of 10°. Based on an economic assessment, this coal dryer also proves that dried lignite coal has increased 4.9% economic value than bituminous coal.

Study of Coal Drying Characteristics Using Boiler Blowdown in a Rotary Coal Dryer

Drying lignite coal to reduce its moisture content has become popular in the last decade. Previously, coal dryers used typical energy such as steam, fuel, or electrical as heat sources. Waste energy had never been implemented in a coal dryer while using it would reduce the cost of production and raise the economic value of the coal itself. An experimental study of drying low-rank coal was conducted using waste energy boiler blowdown in a rotary coal dryer. With variations of 0.595 mm, 1.18 mm, and 4.75 mm coal particle size and the flow's changes of 20 kg/hour, 30 kg/hour, and 40 kg/hour. The hot air temperature of 70 o C, mass flow rate of 36 kg/hour, and pressure of 0,03 MPa were the constant parameters on the 15 rpm rotary drum. The results found that the coal moisture decreased significantly at 0.595 mm particle size and 20 kg/hour of flow. The final coal moisture dropped by 20.685%, and the calorific value increased by 879.6 kcal/kg from its initial value. In addition, the efficiency of the rotary coal dryer is 81.8%.

Energy transfer analysis of the SH626 sheet rotary dryer on the production system perspective

The energy transfer process occurred at all stages of the production system and could demonstrate potential changes in the state of the system during production. The cut tobacco production process also would require a large amount of heat energy to make a high-quality product. Based on the energy balance analysis of the SH626 dryer, the energy consumption of the tobacco drying process was the highest unit, which accounts for approximately 60% of the energy consumption of the whole tobacco production process. The energy transfer efficiency of the sheet heating system was only 0.46 ∼ 0.58 and was mainly influenced by the working temperature of thin plates. The energy transfer efficiency of the hot air heating system was 0.24 ∼ 0.33 and was influenced by the hot air mass flow rate. The energy transfer system remained low levels of energy transfer efficiency and had great potential for saving energy. Those conclusions of this study could provide a theoretical basis to improve dryer system energy transfer efficiency by the thermal integrated system and the intelligent control system.

Model matematika pengeringan daun bunga kecombrang (etlingera elatior jack) pada pengering rotary skala laboratorium

Ginger torch (Etlingera elatior Jack) is an herbaceous plant that is used as a flavoring, deodorizing, anti-oxidant, and antimicrobial. The fresh ginger torch has a high moisture content so that it can’t be stored for a long time because it will rot quickly. Drying is needed to preserve the ginger torch so that it can last longer. The research was aimed to determine the mathematical model, effective moisture diffusion, and activation energy for drying the leaves of Etlingera elatior Jack on a rotary dryer. The method used in this research was an experiment with three times repeated then followed by data analysis with curve expert 2.3.0 and MS-excel software. This research was performed by using a rotary dryer at temperatures of 60 oC, 70 oC, 80 oC, and 90 oC. The ginger torch was chopped about 1 cm, with a mass of 400 grams for each sample. Measurement of moisture content was carried out every 20 minutes. The results showed that the most suitable drying model was the Rational model with the general form of

Experimental evaluation of nano-zinc oxide coating applying on inner surface of a rotary dryer to produce NaCl

Experimental evaluation of nano-zinc oxide coating applying on inner surface of a rotary dryer to produce NaCl

Modeling and Design of a Solar Rotary Dryer Bench Test for Phosphate Sludge

As an eco-friendlier way to manage mining waste, the use of solar energy to dry phosphate sludge in a rotary dryer is envisioned. As a first step toward this end, a design study for a bench-scale rotary dryer for phosphate sludge is detailed, using a one-dimensional mathematical model developed for this task. Using the Engineering Equation Solver (EES) software, a steady-state transport phenomena model was developed that enables an estimation of the moisture and temperature profiles for both gas and product in the dryer. A sensitivity analysis evaluated the effects and influence of different geometric parameters and operating conditions on the product moisture profile. Parameters involved include the diameter of the dryer, the residence time of the product to dry, inlet air temperature, and inlet product humidity. This allowed for the selection of suitable design parameters for the operation of a phosphate sludge dryer with a 1.5 m length and an internal diameter of 11.5 cm. The inlet air temperature of the rotary dryer was set at 200°C to achieve a reduction of moisture content in the product from 30% to 7%. The model was validated through literature and experimental datasets, with an error averaging 0.22% and 1.52%, respectively.

Designing and Manufacturing of Grain Dryer Machine using Coconut Shell Fuel as an Alternative Heat Energy

Many problems in the process of drying grain with a solar heat source. One of the factors is the erratic weather, where the rainy season comes along with harvest time. To overcome these obstacles, a grain dryer was designed that uses a rotary system that is simpler and more efficient and uses coconut shells as an alternative fuel. This study aims to obtain fast and affordable grain drying results by farmers using a rotary system dryer with coconut shell fuel. The benefit of this research is to provide an alternative solution for the community in dealing with harvesting in the rainy season by reducing land for drying grain. Equipment preparation was carried out in particular by using standard equipment to cut and connect the seat frame including the use of silencers and gasoline-fueled motors as propulsion and other supporting equipment. The components of each unit of grain drying machine are assembled and tested in stages according to procedures and functions. The test results show that the use of coconut shell can reach drying temperatures faster than the use of LPG, coconut shell fuel is better at reducing the moisture content of grain than the use of LPG. Testing of coconut shell fuel is done by drying 30 kg of grain for 20 minutes and 15 minutes. It can be concluded that the use of coconut shell as an alternative fuel can achieve a faster drying temperature than the use of LPG fuel. The use of coconut shell fuel to dry 30 kg of grain and reach a moisture content of up to 12% requires an effective time of 15 minutes.

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.

Temperature control for high-quality oil-free sweet potato CHIPS produced by microwave rotary drying under vacuum

Healthy and convenient foods have drawn consumers' attention and represent an opportunity for the food industry. This study is about the production of sliced sweet potato snacks by microwave vacuum drying (MWVD) in a rotary container with temperature control by power modulation. The average temperature of samples' surfaces was measured with an infrared sensor and controlled at 60 °C by a PID controller. The resulting product properties were compared to those from freeze- (FD), air- (AD), and conductive multiflash (KMFD) drying. Rotary container coupled to the temperature control guaranteed uniform heating and resulted in chips without burnt spots in MWVD.MWVD and KMFD produced sweet potato chips in less than 3 h, while AD and FD required 16 h. The drying method influenced chips' porosity: 58% (FD), 44% (MWVD), 39% (KMFD), and 18% (AD). AD chips had a compact structure, while FD chips were spongy with small pores. MWVD and KMFD expanded the material during fast water evaporation under vacuum, creating large and irregular pores. The puncture tests of these chips resulted in jagged force-penetration curves, typical of crispy products, with higher acceptance. Therefore, MWVD and KMFD have the potential for the industrial production of high-quality oil-free and crispy chips.

Energy and exergy analysis during drying in rotary dryers from finite control volumes: Applications to the drying of olive stone

• An exergy and energy analysis during drying is performed from finites control volumes. • A big thermal shock is produced in the first third of the trommel due to evaporation. • Heat loss and exergy destruction is very high at the beginning of the drying process. • The dryer works in optimum conditions at low-medium air flows and low-medium temperatures. • This study will help improve aspects like design and control in rotary dryers. Nowadays, the design, control and development of rotary dryers are based on the study of the complete equipment. Rotary dryers are treated as a black box where only inlet and outlet parameters are known. This implies the need to know the main interactions of mass, energy and exergy throughout the trommel to help improve the drying process. In this paper, we carried out an analysis of energy and exergy during drying of olive stone from finites control volumes in an experimental rotary dryer. Mass, energy and exergy balances are applied to each control volume in the drying air. The design of experiments is based on three initial drying air temperatures (210 °C, 180 °C and 150 °C) and three drying air flows (576 kg/h, 425 kg/h and 280 kg/h), with a by-product mass flow of 40 kg/h and a rotational speed of 5.5 rpm. The results indicated that olive stone moisture content was reduced to less than half in the first third of the trommel where a big thermal shock is produced due to the interaction between the by-product and the drying air flow at high moisture contents and high temperatures, respectively. This fact led to the highest exergy destruction values, thereby diminishing the flow exergies for the following control volumes. Heat losses were considerable in all equipment, especially in the first two control volumes. Furthermore, drying process was analyzed from the energetic, exergetic and drying efficiencies and the unit energy consumption.

Determination of Minerals of Cassiterite Tailings and its Recycling Potential Using Empirical Method at Plateau State Nigeria

The mineral potential of cassiterite fines from tailing dumps in the Jos Tin Mining Community Resource Centre (MCRC), Plateau State Nigeria, were studied through a wet concentration process and dry electrostatic and magnetic processes and then evaluated using empirical evidence. Three samples of the tailing dumps with the size of mineral smaller than 5 mm were collected at random through the “Tin Mining Community Resource Centre”. The huge pile of the tailing dumps may have an environmental impact in the area, so they need to be treated and recovered for the valuable heavy minerals and sand tailing for the local construction industry. The grade of the average tailing dumps as analyzed using XRF were 2.08% Sn, 3.51% Nb, 25.5% Fe, 14.91%Ti, 8.36% Zr, 12.99% Al, and 45.68% Si. The percentage compositions of the cassiterite tailings were expressed to its simplest genetic mineral forms using an empirical formula. The genetic mineral forms were ilmenite, zircon and sand. Since ilmenite has the highest concentration in the cassiterite tailings and the highest economic values, then recycling of ilmenite should be ascertained. After the wet processing by the screen, hydro cyclone, spiral concentrator, and shaking table, the concentrate consists the most of, ilmenite, zircon, and sand. The following dry processes used rotary dryer, screening, electrostatic separator, magnetic separator to separate cassiterite from the heavy minerals and sand. The final iron and titanium concentrate can be upgraded to 72% Fe and Ti using certain reagents such as fluoride acids which can be sold to the Iron ore smelting plant.

Effect of Drying Parameters on Drying Characteristics and Forskolin Content of Rotary Dried Coleus

Coleus (Coleus forskohli), a medicinal crop, contains a bioactive component forskolin, which is extracted and used in several ayurvedic medicines in India. Drying is the primary operation to extract forskolin. In this the study, Coleus was dried in a rotary drier by varying slice thickness (2.5, 5.0, 7.5 mm), drying air temperature (45, 55, 65 o C), and feed volume (50, 60, 70 percent); and the forskolin contents were assessed. The moisture content reduced to 16.55% (d.b.) from 464.97% (d.b.) after rotary drying. The drying time ranged from 300 min to 450 min. The effective moisture diffusivity and activation energy ranged from 1.02 ×10-7 mm2 .s-1 to 1.33 ×10-6 mm2 .s-1 and 5.39 kJ.mol-1 to 15.57 kJ.mol-1, respectively. Forskolin content in dried root varied from 0.14% to 1.87 per cent. High forskolin content was found in 2.5 mm thick slice dried at 55 o C and 70% feed volume. Analysis of variance showed that forskolin content in dried Coleus root was significantly (p<0.0001) affected by slice thickness and drying air temperature than feed volume (p<0.01).

Modelling and Simulation of a Rotary Grain Dryer

Modelling and Simulation of a Rotary Grain Dryer

Performance evaluation of a rotary dryer in both co-current and counter-current configurations

A mathematical model was developed to simulate the process of superphosphates fertilizers drying in a rotary dryer in both co-current and counter-current configurations. Besides, the performance of the rotary dryer, installed in a local industrial unit, was assessed using the concept of energy and exergy analysis. Matlab software was used to develop the mathematical model, which is based mainly on mass and energy conservation equations. Good agreement between the simulated results and the experimental results from literature was obtained. The simulation results showed that the product’s moisture content was reduced from an initial value of 0,14 kgH2O / kg dry solid to 0.0912 and 0.0862 kgH2O / kg dry solid at the dryer's outlet for the co-current and the counter-current configurations, respectively. A parametric study was carried out to evaluate the effect of the length of the dryer and the inlet drying air temperature on the moisture content to compare both configurations. Energetic and exergetic indicators were formulated and then computed based on the inlet operating conditions. The energy efficiency and the specific energy consumption for the co-current and the counter-current configurations were, respectively, found to be 13% and 24% and 5762 and 3502 kJ per kg of water evaporated. The exergy indicators, namely the exergy loss, the exergy destruction rate, and the exergetic efficiency, were 11.37 and 17.82 kW, 1.026 and 1.098 kW, 25.86 and 41.38% for the co-current and the counter-current configuration, respectively. A sensitivity analysis was used to investigate the effect of varying the inlet drying air temperature on energetic and exergetic performance parameters.