Pneumatic Drying Research Articles

Valorization of waste graphite in spent lithium-ion batteries to graphene via modified mechanical exfoliation and the mechanism exploration

In the electrodes of spent lithium-ion batteries, graphite, due to its layered structure and crystalline composition, presents significant recyclable value, yet it has not been fully utilized. This study proposes a modified mechanical exfoliation method (MEM), which employs leaching-drying pretreatment to transform waste graphite into two-dimensional graphene. Three drying methods were evaluated, among which freeze drying was found to be the most conducive for exfoliation. Pneumatic drying, being basic and simple, did not exhibit any special effects that benefit exfoliation. XRD results showed that leaching restores the lamellar structure of graphite, with peak intensity ( × 105) increasing from 6.5 to 8.9–10.1. XPS analysis revealed that vacuum roasting drying leads to dehydration condensation of hydroxyl groups between layers, resulting in the obtained graphite having the best dehydration effect and the lowest oxygen content, at only 1.89%, but this enhances interlayer forces, which is counterproductive for exfoliation. In contrast, freeze drying, through the volumetric expansion caused by the freezing of water, disrupts the interlayer forces, achieving an interlayer spacing of 337.5 nm, which facilitates the exfoliation of graphene. This was confirmed by TEM results. This method effectively overcomes the problem of impurity contamination in waste graphite, providing a new approach for the high-value utilization and green recycling of graphite in spent lithium batteries.

Optimum design of an acetylated starch plant from Manihot esculenta Crantz, variety INIVIT-Y-93-4

Considering the applicability and added value of acetylated starches, it is necessary to find technological variants to obtain them with favorable technical-economic results and energetic and environmental compatibility. The objective of the work is to optimize economic and dynamic indicators of profitability of acetylated starch production, by considering as optimization criteria the productive capacity, the degree of substitution and the temperature of the drying air, establishing the design of the installation in optimal conditions. Technologies adopted from the mechanized native starch processes were selected, and the design and development of the slurry heating, acetylation, and pneumatic drying stages were proposed. A composite central experimental design was generated for profit (P), net present value (NPV), and internal rate of return (IRR), and the quadratic models obtained through the Response Surface Methodology were optimized. For the evaluation of the indicators, the economic indexes of the process were determined, after technological selection, material and energy balances, and technological design. The optimum operating parameters are achieved at a production capacity of 12.57 tcassava/d, degree of substitution of 0.505 and 124.98 °C in the air supply to the pneumatic dryer. Under these conditions, the production of acetylated starch requires larger volume acetylators than for acetylated gelatinized starch process, but the technological requirements of gelatinized pulp are eliminated, achieving remarkable energy efficiency with pneumatic drying.

Research and modeling of the ecological efficiency of drying refractory and building materials in vertical shaft furnaces

Based on the hypothesis of the dominant effect on the environmental efficiency of drying materials in shaft furnaces of the concentration, median diameter, dispersion, temperature and humidity of dust particles at the outlet of the dryer, a device for thermal aeration separation of dust is proposed. The analysis of mathematical modeling of aerothermodynamic processes in a two-phase medium asbestos dust ‒ gas flow confirmed the conclusions of industrial studies on the influence of aerothermodynamic parameters of direct flow on the temperature and humidity of asbestos dust in the pneumatic dryer. Based on the principle of additive classification, a mathematical model of aeration separation of dust particles directly in the dryer of the shaft furnace is constructed, depending on the parameters of the heat carrier and the proposed device.

Extensive experimental validation of a model for pneumatic drying of cassava starch

A pneumatic drying model, developed in a previous work, was tested and validated based on a series of 56 experiments of cassava starch drying conducted on a pilot-scale pneumatic dryer. After fitting two parameters, the average diameter of starch particles and a heat loss factor, the model predicted the effects of main operating conditions with a level of accuracy comparable to that of the experimental measurements. Transient phases with sudden variations of product feed rate were also successfully simulated. The model is therefore suitable for equipment design purposes. The experimental results showed that the size of starch particles considerably decreases with increasing air velocity. As a result, at high air velocity, despite the shorter residence time in the drying pipe, the overall drying performance is improved due to the smaller particle size. It is therefore possible to increase air velocity, and hence product feed rate and production capacity, without detrimental effect on the drying efficiency.

Numerical simulation of soda ash drying process in pneumatic drying system with industrial scale

In this paper a mathematical model for the soda ash drying process in a pneumatic dryer was presented. The model presents a macroscopic aspect of the drying process, for a two-phase, gas-solid system. The model is based on mass and heat transfer between the gas phase and the particle, movement of air and particles through the system, and geometric characteristics of the drying system (fan, air heater, pneumatic dryer, and cyclone). The effects of the process parameters, such as airflow, inlet air temperature, and relative humidity, temperature at the inlet of the dryer, etc., have been studied by solving the model. Also, the model was tested for different values of the capacity of wet soda and different values of the operating parameters of the heating medium. The model was implemented in MATLAB and solved with a nonlinear equations solver. Data obtained by the model were compared with industrial pneumatic dryer data for drying wet soda ash particles with good agreement.

Effect of various drying methods on the physical characteristics of arrowroot powder

Arrowroot (Maranta arundinacea) is a large herb found in rainforest habitats. In Indonesia, Arrowroot (or known locally as Ubi garut) is usually processed into a powder ingredient for many foods such as puddings and cookies. One of the crucial processes in producing arrowroot powder is drying. In this study, the effect of various drying methods on the characteristics of arrowroot powder was evaluated. They were solar drying (SD), cabinet drying (CD), and pneumatic drying (PD). The pneumatic dryer used was self-made with a total dimension of 1600×500×2500 mm. It was made from stainless steel plate with 3 mm thickness and equipped with heater, blower, feeder, cyclone, and drying chamber (heater fins of 4,500 watts). The moisture content showed that the CD sample has the lowest moisture content than other methods. The PD has a great potential to be used to produce arrowroot powder while retaining its color and nutritive values.

Effect of various drying methods on the physical characteristics of purple yam powder

Purple yam (Dioscorea alata) is a type of plant that grown in almost all regions of Southeast Asia. In Indonesia, purple yam is one of the most popular types of sweet potatoes compared to other types of the genus Dioscorea. Purple yum is usually consumed directly as a side dish, or processed into a powder. One important process of making purple yam powder is drying. In this study, the characteristics of purple yam powder were evaluated from several drying methods, namely sunlight drying (SD), cabinet drying (CD), and pneumatic drying (PD). The pneumatic dryer used was self-made with a stainless steel plate (3 mm thickness) and has total dimension of 1600x 500x 2500 mm. The results showed that the CD sample had the lowest water content. The purple yam powder by CD and PD can produce brighter powder compared to that with SD method. From the FM test, the smallest FM value was obtained from CD sample. CD sample proven to be able to retain purple yam nutritive values after drying process.

Effect of various drying methods on the physicochemical characteristics of pumpkin powder

Pumpkin, one of the most famous cultivars from Cucurbita moschata, is a rich source of carotenoid. However, having high water content (above 80%) makes pumpkin extremely perishable, and difficult to be processed and stored. Therefore, pumpkin needs a dehydration process in which could remove moisture content from the product but still able to uphold its natural color and minimum nutrient losses. We have carried out a comprehensive study to investigate the effect of different methods; sunlight drying (SD), cabinet drying (CD), and pneumatic drying (PD) on the physicochemical properties of pumpkin powder. The pneumatic dryer used was self-fabricated with a stainless steel plate (3 mm thickness) that has a total dimension of 1600x 500x 2500 mm. The physicochemical properties evaluated include final moisture content, the color difference (ΔE), carbohydrate, fat, protein, and β-carotene. CD produced powder with the lowest final moisture content. The mean value of ΔE of PD was the lowest as compared to SD and CD. The SD sample has the lowest mean FM value. Pneumatic drying exhibit good potential to produce pumpkin powder while retaining its color and nutritive values.

Comparative Study between Current Practices on Cassava Drying by Small-Size Enterprises in Africa

Small-size enterprises drying cassava in Africa mostly use fixed-bed dryers or pneumatic dryers. The objective of this study was to determine which of those two dryers is the best choice for this operation. Energy performance, product quality and costs were measured and analysed using a comparative experiment design. Each dryer was considered as a treatment and experiments were performed in quintuplicate at a cassava processing small-size enterprise in Ghana. The energy performance of the pneumatic dryer was superior because of the better contact between the cassava grits and the drying air, resulting in greater heat and mass transfer. The cassava flour obtained from the fixed-bed dryer had a higher Whiteness Index, but the same level of lightness, and the staff responsible for managing product quality was not able to visually distinguish them. As a result of the pneumatic dryer’s better energy performance, its operating cost was lower. The capital cost of this dryer was higher, but to recover the additional investment only 194 days of operation were needed. Therefore, it was concluded that pneumatic dryers are a better choice of equipment for cassava drying by small-size enterprises in Africa.

Erratum to: Evaluation Performance of Pneumatic Dryer for Cassava Starch [18 (4): 216-223

Correction to: Reaktor (2018), 18 (4): 216-223 (doi: https://doi.org/10.14710/reaktor.18.04.216-223) An error appeared in the article entitled “Evaluation Performance of Pneumatic Dryer for Cassava Starch” published in Reaktor. In the published article the acknowledgement was:The authors would like to thank Widiantara, Maria Agustin Taolin and Dea Endah, Y. for supporting in preparation of materials this research. The acknowledgement of the article is corrected to be: none The original article can be access online at: https://doi.org/10.14710/reaktor.18.04.216-223 How to Cite This Article: Suherman and Hidayati, N. (2018), Evaluation Performance of Pneumatic Dryer for Cassava Starch, Reaktor, 18(4), 216-223,http://doi.org/10.14710/reaktor.18.04.216-223. Permalink/DOI: http://doi.org/10.14710/reaktor.20.03.159-159

Influence of process parameters in superheated steam drying on fire and explosion parameters of woody biomass

Studying of the drying kinetics and fire and explosion characteristics of biomass is a fundamental aspect in designing material drying systems based on superheated steam, and proper selection of explosion and fire protection systems. The paper presents studies on osier willow (Salix viminalis) drying kinetics under isothermal conditions (120 °C, 140 °C, 160 °C, 180 °C) and their use for process calculations of the proposed one-dimensional model of superheated steam pneumatic dryer. The model included empirical parameters in order to describe the volumetric heat transfer and specific surface of the wood particles of irregular shapes.In addition, a 20-L spherical explosion chamber, Hartmann tube apparatus, hot plate apparatus and Godbert-Greenwald furnace apparatus were used to investigate the explosion and fire characteristics of willow dusts. Based on the studies it was confirmed that the operating parameters of superheated steam drying system for woody biomass have a major impact on the explosion and fire characteristics of the formed dust. The results indicate that the lower the moisture content in the willow, the more likely the dust cloud to be ignited, the faster the explosion flame propagation, and the greater the explosion severity. Despite the fact that the superheated steam drying system for woody biomass is considered safe, the probability of occurrence of fire or explosion incidents related to the dust and air biomass mixture is high. The maximum temperature for superheated steam drying equipment covered with up to 5 mm thick layer of osier willow dust should not exceed 215 °C.

Experimental and numerical investigation of specific energy consumption of the two-stage pneumatic-fluidized bed drying of suspension-grade polyvinyl chloride

The multistage drying system is one of the novel methods that has small specific energy consumption (SEC) compared to the conventional single drying systems. Rotary and fluidized bed dryers are the conventional drying systems of suspension-grade polyvinyl chloride (S-PVC). This article describes the energy consumption characteristics of a two-stage pneumatic fluidized bed drying system for drying of S-PVC. Computational Fluid Dynamics is used to anticipate the hydrodynamics and drying mechanisms with Eulerian–Lagrangian and Eulerian–Eulerian approach in the pneumatic dryer and fluidized bed dryer, respectively. The experimental study is accomplished using spiral pneumatic and a fluidized bed dryer. The investigation of the SEC and influence of a two-stage drying system on S-PVC drying has been set as the main target. The result shows that by using the two-stage pneumatic-fluidized bed drying in certain conditions, the SEC is reduced up to 8255 kJ/kg and an average of 5260 kJ/kg compared with fluidized bed single-stage drying.

The Mathematical Analysis of the Drying of Cassava Grater by Using Pneumantic (flash) Dryer with Heat Recirculation Method

The abundance of cassava cultivation production in Indonesia needs to be balanced with the use of cassava itself to be a source of alternative food as rice subtitute. In this research was done the drying of tubers grater which was cassava to be dried into flour. This drying used a mechanical dryer which was a pneumatic (flash) dryer by using the heat recirculation method (the heat produced from drying was reused). The drying in this research was carried out with a variation of 2 air openings, which were openings for air speed (blower) and openings in the heat recirculation pipe. For openings in the blower, this research used 2 variations of openings, which were openings 50% (air speed 0.0603 m/s) and openings 75% (air speed 0.0768 m/s). For openings in the recirculation pipe, 4 variations of openings were used, which were openings 0% (without recirculated the heat), openings 25% (the heat returned was only 25%), 50% and 75%. The drying time was based on how long the material was in the duct drying. The results showed that, by doing heat recirculation, the value of heating and drying efficiency would increase. The drying in air recirculation 25% could increase the value of drying efficiency for about 5-6%, while in air recirculation 50% could increase the efficiency value for about 3-4%. The value of the heating efficiency of this research ranged from 57-86%. The drying rate constant of the cassava grater moisture content ranged between 0.16 to 0.194%/second.

Rapid Drying of High-Moisture Paddy Using a Pneumatic Dryer with Corrugated-Surface Drying Column

Combination of corrugated-surface drying column and multipass drying concept (first-pass and second-pass drying) was made to increase the performance of a pneumatic dryer for high-moisture paddy. In this study, different characteristics of the drying column, which could be characterized by the ratio between the corrugated-surface length (C) and the total length (L) of the drying column (or C/L), were proposed. The influences of drying temperature (120oC, 150oC, and 180oC) and value of C/L (0, 0.5 and 1.0) on the dryer performance and energy utilization of the drying process were disscussed. The drying column with a higher value of C/L had higher potential for increasing dryer performance. For the first-pass drying, the drying system using the drying column with corrugated surface could reduce the energy consumption by 14% to 44% compared with the drying system using the drying column without corrugated surface. For the second-pass drying, the drying system using the drying column with corrugated surface consumed more energy, however. The moisture reduction of paddy could also be significantly increased after the second-pass drying.

Drying efficiency and product quality of biomass drying: a review

Drying is an energy-intensive pretreatment process of biomass for production of biofuels by thermo-chemical conversion. The efficiency and quality during biomass drying have a significant impact on the economy and sustainability of bioenergy plants. In this review, recent development of conventional dryers, including rotary drum dryer, fluidized bed dryer, pneumatic dryer, agitated drum dryer and fixed or moving bed dryer were described. Progress in the study of advanced drying technologies, such as solar drying, microwave-drying and far-infrared drying in laboratory and pilot-plant scale were summarized as well. In order to reduce the energy consumption of drying system, multistage drying, self-heat recuperation and process integration were introduced in the bioenergy plant. Theoretical performance of these energy-saving processes is represented in this review, along with some experimental findings in the pilot plants.

The Effect of Dryer Air Temperature on The Moisture Content of Cassava Flour in The Pneumatic Drying Process

Drying method that is applied in flour manufacturing industry, one of which is pneumatic drying. Variable types of both the properties of the dried material and the conditions of the drying process greatly affect the quality of the results of drying. Water content is an important variable in determining the quality of flour. The purpose of this study was to find the effect of drying air temperature on the moisture content of cassava flour under the conditions of the pneumatic drying process. Drying of cassava flour at desiccant air temperatures of 145oC and 160oC with 2 drying cycles produced a moisture content of 11.3 and 8.7% wb and had fulfilled SNI for flour water content, which was a maximum of 12% wb. The higher the temperature of the drying air, the lower the moisture content.

Evaluation Performance of Pneumatic Dryer for Cassava Starch

In small and medium industries, cassava starch is dried using conventional method by drying it directly under the sun. However, the main drawback of conventional method is low drying rate. Therefore, in this study, cassava starch with a water content of 40% (wet basis) was dried using a pneumatic dryer to a moisture content below 13% (wet basis). The aim of this research is to analyze the influence of drying air temperature, drying air flow rate and rate of feeding in relation to drying rate and energy analysis. Energy analysis was performed to determine the performance of pneumatic dryer. The energy analysis itself is done in the form of energy utilization and energy efficiency. The energy analysis shows that the increase of dryer temperature from 60 to 100oC will increase the utilization of energy from 0.34 to 0.76 J/s, while the energy efficiencies ranged between 30-40%. Proximate analysis shows that the dried cassava starch has an ash content of 0,24, grain fiber of 0,12, and degree of whiteness of 98%, which fulfills the SNI standard of cassava starch.Keywords: cassava starch; energy analysis; pneumatic dryer

Performance, Energy, and Product Quality Aspects of a Modified Pneumatic Dryer for Rapid Drying of High-Moisture Paddy

The application of surface roughness on the drying column was combined with a multipass drying concept (first-pass and second-pass drying) to improve the performance and energy utilization of a conventional pneumatic dryer during rapid drying of high-moisture paddy. The surface roughness on the drying column was characterized by the ratio of the corrugated surface length (C) to the total length (L) of the column (i.e., C/L). The effects of drying temperature (120°C, 150°C, and 180°C) and C/L value (0, 0.5, and 1.0) on the dryer performance, energy utilization of the drying process, and rice milling quality were determined. The drying column with a higher C/L value had higher potential for improving the dryer performance and energy utilization of the drying process. For first-pass drying, a drying column with C/L values of 0.5 and 1.0 could reduce energy consumption by 14% to 17% and by 41% to 44%, respectively, compared with a column without a corrugated surface (C/L = 0). However, for second-pass drying, the drying system that used a drying column with a corrugated surface consumed more energy. The moisture content reduction of paddy could also be significantly increased after second-pass drying. For both first-pass and second-pass drying, a higher drying temperature and higher C/L value resulted in a lower head rice yield from the milled rice, while the effects of drying temperature and C/L value on the whiteness value of the milled rice were found to be insignificant.HighlightsCharacteristics of the drying column had more significant effects on the dryer performance and energy utilization than the drying temperature.A drying column with C/L = 1 (totally corrugated surface) showed significant potential for increasing the dryer performance and energy utilization of the drying process.A drying column with a higher C/L value may not be necessary for paddy with a small amount of surface moisture.Multipass drying of paddy using a pneumatic dryer is not suggested due to the significant reduction in head rice yield. Keywords: Drying column, Energy utilization, Milling quality, Multipass drying, Pneumatic dryer, Surface roughness.

Experimental Study of Moisture Content Stability on the Low-speed Pneumatic Drying Process of Cut Stem

According to the principle of moisture control at outlet of the cut stem low-speed pneumatic drying equipment of SH23, we studied the relationship between the mixing air valve’s opening and moisture content stability of products and the relationship between the main equipment controllable process parameters and the mixing air valve’s opening by regression analysis. It provides the following basis for improving the moisture content stability by controlling the technological parameters of the equipment, the average value of the mixing air valve’s opening has a significant effect on the stability of moisture content , for each reduction of 1% moisture content in the low-speed pneumatic drying process, it is necessary to turn down the mixing air valve’s opening by about 8.175% and the influence degree of the main control parameters related to the mixing air valve’s opening is arranged.

Experimental and numerical study of the effects of pre-drying of S-PVC using a pneumatic dryer

ABSTRACT Pneumatic conveying drying (PCD) has been widely used in industrial processes because it is regarded as a highly efficient technique in heating, and mass transfer of product operation. Despite the fact that the use of multi-stage drying techniques is now justifiable, many industrial complexes still use older single-stage systems. The purpose of this article is to investigate the effects of using a pneumatic dryer as a pre-dryer in PVC suspension production line at Bandar Imam Petrochemical Complex (BIPC). The current operating system in PVC suspension production line is fluidized bed drying. In the present work, computational fluid dynamics (CFD) is utilized to predict the hydrodynamics and drying mechanisms of a three-dimensional, dilute-phase, gas-solid turbulent flow in the laboratory-scale. The experimental study is carried out in two pilot-scale spiral pneumatic conveying dryers of diameter 5 cm and 13.45 m length and diameter 10 cm and 7.2 m length. As the main goals of this research, the influence of diameter and length of the dryer are investigated in two pilot-scale vertical pneumatic conveying dryers. In addition, the effects of gas velocity and temperature, particle temperature, mass flow rate and initial moisture content on the dryer performance are examined. The variations in the air velocity, air temperature, air pressure and particle moisture content are investigated along the length of the dryer. The results of energy analysis show that by using the pneumatic dryer as a pre-dryer, the specific energy consumption is reduced about 23.1%.