Solid Moisture Research Articles

Self-heating of dried industrial wastewater sludge: Lab-scale investigation of supporting conditions

We studied the reactivity of dried sludge produced by treatment of wastewater, mainly from tanneries. The solids transformations have been first characterized with thermal analysis (TGA and DSC) proving that exothermic transformation takes place at fairly low temperature, before the total organic combustion that occurs in air above 400°C. The onset of low temperature reactions depends on the heating rate and it can be below 100°C at very small heating rate.Then, we reproducibly determined the conditions to trigger dried sludge self-heating at the laboratory scale, on samples in the 0.2–0.3kg size. Thermal insulation, some aeration and addition of water are key factors. Mastering the self-heating at this scale allows more detailed investigations as well as manipulation of conditions, to understand its nature, course and remediation. Here we report proves and discussions on the role of air, water, particle size, porosity and biological activity, as well as proving that also dried sludge from similar sources lead to self-heating.Tests demonstrate that air and water are simultaneously required for significant self-heating to occur. They act in diverging directions, both triggering the onset of the reactions and damping the temperature rise, by supporting heat loss. The higher the O2 concentration, the higher the solids heating rate. More added water prolongs the exothermic phase. Further additions of water can reactivate the material. Water emphasizes the exothermic processes, but it is not sufficient to start it in an air-free atmosphere. The initial solid moisture concentration (between 8% and 15%) affects the onset of self-heating as intuitive. The sludge particles size strongly determines the strength and extent of the heat release, indicating that surface reactions are taking place. In pelletized particles, limitations to water and air permeability mitigates the reaction course.

Experimental Investigation and Modeling of Plug-Flow Fluidized Bed Drying Under Steady-State Conditions

In this study, a model for a plug-flow fluidized bed dryer under steady-state conditions was presented. The model was based on differential equations; thus the bed of the dryer was divided horizontally and vertically into major and minor control volumes, respectively. Each control volume was composed of two thermodynamic systems: solid and gas. The mass and energy balances of the particles in the major control volume based on the axial dispersion were developed to derive the axial profiles of solid moisture content and temperature. To derive the variation of gas humidity and temperature along the bed height and hence the axial profiles of outlet gas humidity and temperature, the mass and energy balances in the gas over the minor control volume, considering the plug flow of gas through the bed, were developed. The model was validated by comparing the simulation results with the experimental data obtained by drying the long-grain rough rice under steady-state conditions in a laboratory-scale, plug-flow fluidized bed dryer. A very satisfactory agreement between the simulation and the experimental data of solid moisture content, solid temperature, and outlet gas humidity and temperature was achieved. Also, the effects of inlet gas temperature, weir height, and inlet dry solid mass flow rate on the simulated axial profiles of solid moisture content and temperature, humidity difference between inlet and outlet gas, and outlet gas temperature were investigated.

A full-scale house fly (Diptera: Muscidae) larvae bioconversion system for value-added swine manure reduction

Manure produced from confined animal farms can threaten public and environmental health if not managed properly. Herein, a full-scale commercial bioconversion operation in DeQing County, China for value-added swine manure reduction using house fly, Musca domestica L., larvae is reported. The greenhouse-assisted larvae bioreactor had a maximum daily treatment capacity of 35 m(3) fresh raw manure per day. The bioconversion process produced a fresh larvae yield of 95-120 kg m(3) fresh raw manure. This process provided an alternative animal foodstuff (having 56.9 and 23.8% protein and total fat as dry matter, respectively), as well as captured nutrients for agricultural re-utilization. Bioconversion reduced odour emission (characterized by 3-methylindole) and the Escherichia coli (E. coli) index by 94.5 and 92.0%, respectively, and reductions in total weight, moisture and total Kjeldahl nitrogen in solids were over 67.2, 80.0 and 76.0%, respectively. Yearly profit under this trial period ranged from US$33.4-46.1 per m(3). It is concluded that swine manure larvae bioconversion technology with subsequent production of value-added bio-products can be a promising avenue when considering a programme to reduce waste products in an intensive animal production system.

Simulation of Multiphase Flow of the Oil-Water Separation in a Rotating Packed Bed for Oil Purification

HIGEE (High Gravity Rotary Device) rotating oil purifier which consists of two parts: hydrocyclone separator and rotating packed bed (abbr. RPB) is considered to be capable of removing the solid particle contaminant, moisture and gas simultaneously. As the major unit of HIGEE, the RPB uses centrifugal force to intensify mass transfer. Because of the special structure of RPB, the hydraulic characteristics of the RPB are very important. In this study, the multiphase flow model in porous media of the RPB is presented, and the dynamical oil-water separation in the RPB is simulated using a commercial computational fluid dynamics code. The operating conditions and configuration on the hydraulic performance of the RPB are investigated. The results have indicated that the separation efficiency of HIGEE rotating oil purifier is predominantly affected by operating conditions and the configurations. The best inlet pressure is 0.002 MPa. When the liquid inlet is placed in the outside of the lower surface of RPB; oil outlet is placed in the upper surface, where it is near the rotation axis; and water outlet is placed in the middle of the RPB, where it is far away from the oil outlet, the separating efficiency is the best.

Effects of key structural parameters on solid–liquid separation behavior of hydrocyclone separator applied to hydraulic oil purification

Contamination control in fluid power system is a challenge due to the fact that it has been one of the major reasons of wear, failure, and the related downtime. A novel hydraulic oil purifier proposed in this study is considered to be capable of removing the solid particle contaminant, moisture, and gas simultaneously, which consists of two parts: hydrocyclone separator and rotating packed bed (i.e. Higee). A hydrocyclone separator used to be applied to chemical industry is tried to be designed according to experiential parameters in a typical fluid power system for the first time. And then, the mathematical model of the hydrocyclone separator has been established. The distribution of the hydraulic oil and solid particles in swirling flow field inside the base hydrocyclone separator has been simulated with the help of computational fluid dynamics software Fluent. The effects of the cone angle and cylindrical length on the separation performance of the hydrocyclone separator have been subsequently investigated. Based on the simulation results, the hydrocyclone separator with 25° cone angle and 60 mm cylindrical length has been considered as the most satisfied configuration. Simulation analysis of the optimal configuration flow field reflects a relatively pleasant solid–liquid separation performance considered to be beneficial to controlling the contamination level of fluid power system. The research outcome will lay a foundation for the development of the new hydraulic oil purifier proposed in this study.

A Hybrid Lumped Parameter/Neural Network Model for Spouted Bed Drying of Pastes with Inert Particles

The current study analyzed the suitability of a hybrid CST/neural network model to describe the highly coupled heat and mass transfer during paste drying in a spouted bed. In the present approach, the main information was the moisture content predictions in the powder. The model was based on global energy and water mass balances in the liquid and the gaseous phases. In this model, the inter-phase coupling term r, which reflects both water evaporation and particle coating, was described by an artificial neural network. Artificial neural networks are efficient computing models which are extensively used whenever theoretical models fail to properly represent a given phenomena and reliable data basis of the main variables involved is available. Simulations were done in MatLab. The drying experiments for model verification were carried out in a conical semi-pilot scale spouted bed, from which measurements of gas and solid phase moisture were done. The good agreement between calculated and measured powder moisture content suggested that the well-mixed hypothesis could be applied for paste drying in a spouted bed. The robustness of the model with respect to changes in feed flow rates and other operating conditions showed the merits of using a trained neural network.

Elaboração de farinha instantânea a partir da polpa de fruta-pão (Artocarpus altilis)

Objetivou-se elaborar uma farinha instantânea utilizando do mesocarpo de fruta-pão, variedade apyrena, e avaliar sua composição físico-química, bem como desenvolver um purê a base da farinha e determinar sua aceitação sensorial por consumidores potenciais utilizando o teste de consumidor. A fruta-pão in natura apresentou valores de umidade em base úmida, pH, teor de sólidos solúveis totais e acidez total titulável aproximadamente 74,58±2,84%, 6,01±0,04, 5,6±0,01Brix e 1,64±0,01%, respectivamente, e a farinha instantânea com umidade, pH, densidade, acidez álcool solúvel e atividade de água de 9,4±0,28%, 5,55±0,2, 0,61±0,01g mL-1, 2,098±0,01% e 0,538±0,14, respectivamente. A equação adaptada de Brooker, usada para ajustar o comportamento da secagem, foi eficiente para descrever o processo de secagem da polpa de fruta-pão cozida. O purê de fruta-pão apresentou boa aceitabilidade pelos consumidores para os atributos sensoriais avaliados, exceto para a cor, sendo que a maioria declarou comprar o produto.

CFD Modeling of Microwave-Assisted Fluidized Bed Drying of Moist Particles Using Two-Fluid Model

The drying behavior of moist spherical particles in a microwave-assisted fluidized bed dryer was simulated. The two-fluid Eulerian model incorporating the kinetic theory of granular flow was applied to simulate the gas–solid flow. The simulations were carried out using the commercial computational fluid dynamics (CFD) package Fluent 6.3.26. The effects of different levels of microwave power densities as well as initial gas temperature on the prediction of solids moisture content, gas temperature, and gas absolute humidity were investigated. The effect of microwaves was incorporated into calculations using a concatenated user-defined function (UDF). The simulation results were compared with experimental data obtained from drying of soybeans in a pilot-scale microwave-assisted fluidized bed dryer and reasonable agreement was found. The mean relative deviation for prediction of solids moisture content, gas temperature, and gas absolute humidity were less than 3, 10, and 5%, respectively. Further work is needed to validate the proposed model for large-scale plants.

Rotary Dryer Control Using a Grey-Box Neural Model Scheme

The application of a Grey-box Neural Model (GNM) in a nonlinear model predictive control scheme (NMPC) of a direct rotary dyer is presented in this work. The GNM, which is based on the combination of phenomenological models and empirical artificial neural network (ANN) models, was properly developed and validated by using experimental fish-meal rotary drying information. The GNM was created by combining the rotary dryer mass and energy balances and a feed forward neural network (FFNN), trained off-line to estimate the drying rate and the volumetric heat transfer coefficient. The GNM results allowed us to obtain the relation between the controlled variable (solid moisture content) and the manipulated variable (gas phase entrance temperature) used in the predictive control strategy. Two NMPC control strategies, one with a fixed extended prediction horizon and another with an extended range prediction horizon, were applied to a simulated industrial fish-meal drying process. The results showed that a correct rotary dryer representation can be obtained by using a GNM approach. Due to the representation capability of the GNM approach, excellent control performances of the NMPCs were observed when the process variables were subject to disturbances. As analyzed in this work, the fixed extended prediction horizon MPC surpassed recognized control methodologies (quadratic dynamic matrix control).

Development of microcontroller-based microwave system to measure solid content of hevea rubber latex

This paper describes the development of digital, portable, simple to operator, cheap and accurate microwave instrument to determine the total solid content (TSC) or moisture content (MC) of hevea rubber latex by using microcontroller, dual directional coupler, and open-ended coaxial probe. A low-cost stripline dual directional coupler and open-ended coaxial probe are simulated, designed and connected to microwave source and detectors. TSC parameter is obtained from the relationship between moisture content in the sample and the value of reflection coefficient from coaxial probe. Experimental results are presented and the empirical equation was implemented by the microcontroller for the calibration and followed the calculation setup. The whole system was tested by using diluted rubber latex with different TSCs at room temperature (25°C) and the results of standard oven drying method and this study were found with the accuracy and reproducibility at the level of less than 1%.

Effect of moisture content on dense-phase conveying of pulverized coal at high pressure

In dense-phase pneumatic conveying, the solid moisture content can significantly influence the conveying process, but there are very few studies in the open literature. In this study, the conveying experiments of two pulverized coals with various moisture contents were carried out at a 4MPa high pressure and dense-phase pneumatic conveying facility. Results show that the whole conveying system can be stably and controllably operated under the condition that moisture content below ∼8%. With the increase of moisture content up to ∼8%, the mass flow rate of 280 μm pulverized coal increases at first and then decreases, while that of 55 μm pulverized coal decreases continuously. The method of solid friction factor correlation is used to investigate pressure drop of the horizontal pipe, and non-dimensional parameters—Fr number, moisture content M and solid loading ratio µ—are investigated. The pressure drop predictions by this correlation are in good agreement with the experimental data. The solid friction factor correlations indicate that the fine coal is more sensitive to M, and µ plays a more important role for the coarse coal.

CARACTERÍSTICAS FÍSICO-QUÍMICAS DE EXTRATOS DE ARROZ INTEGRAL, QUIRERA DE ARROZ E SOJA

Hydrosoluble extracts are vegetable drinks with a commercial nutritional appeal, concerning health aspects, like absence of animal fats and high minerals contents. This study aimed to compare the physical and chemical characteristics of whole rice, broken rice, and soybean hydrosoluble extracts. The analyses (in triplicate) were pH, soluble solids content, moisture, ashes, proteins, lipids, total carbohydrates, calcium, magnesium, cupper, manganese, iron, zinc, and caloric value. The broken rice extract presented the highest carbohydrates content (3.17 g 100 g-1) and the lowest value for ashes (0.58 g 100 g-1), proteins (0.73 g 100 g-1), lipids (0.41 g 100 g-1), and caloric value (17.28 kcal 100 g-1), while the whole rice extract showed the highest pH (6.77) and intermediate values for calcium (1.2 mg 100 g-1) and magnesium (1.69 mg 100 g-1). The soybean extract presented the highest contents of all minerals, ashes (0.84 g 100 g-1), proteins (2.51 g 100 g-1), lipids (1.05 g 100 g-1), and caloric value (68.34 kcal 100 g-1), but the lowest value for carbohydrates (2.62 g 100 g-1). Despite its lower nutritional value, when compared to the soybean extract, the whole and broken rice extracts can be viable alternatives for replacing milk or soybean extract, by people with any kind of lactose intolerance or soybean protein allergy.

Changes in the response of viscoelastic solids to changes in their internal structure

The manner in which a viscoelastic body relaxes or creeps is determined by the viscoelastic body’s internal structure. In this paper, we are primarily interested in the changes in the body’s internal clock due to the changes in its structure. This internal clock’s working can be modified due to the effect of temperature, moisture, and electromagnetic fields, thereby degrading or enhancing the response of the viscoelastic body. Within a purely mechanical context, by degradation or enhancement, one means the decrease or increase in the load carrying capacity. Such degradation or enhancement due to the effect of moisture and temperature in elastic solids has been studied earlier. In this paper, we extend these ideas to the response of viscoelastic solids, particularly through the alteration of the viscoelastic body’s internal clock. To evaluate the efficacy of the model that we have developed, we study a very interesting problem, a biological application wherein the viscoelastic uterine wall’s stress relaxation characteristic changes significantly. The constitutive relation that is developed, and more importantly the methodology that is being put into place, can be used to describe a variety of problems in polymer mechanics and biomechanics and is not limited to the special example that is considered.

Physical Characterization and Biomass Fluidization (Fume Powder)

The development of big cities and industrialization has been causing environmental degradation problems, damaging natural and energetic resources, besides the bigger production of wastes. So, it is essential the use of renewable alternative fuels, and industrial wastes processing. Biomass can be used in direct combustion, thermo chemical and biological processes. The fume powder is an important waste of tobacco industries. This work makes a characterization of fume powder, originated from Souza Cruz (Uberlândia unit); the objective is to realize the fast pyrolysis in a bubble fluidized bed. Physical analyses of the powder were made to determine the size distribution, and the medium diameter; the solids density and moisture content (dry base). The elementary composition of the material was also determined. The powder fluidization in an acrylic bed (160 cm heights, 10 cm id), was realized to obtain the minimum fluidization velocity.

Effect of Particle Size Distribution on Ammonium Sulphate Dried in a Rotary Dryer

The aim of this work is to study theoretically, by mathematical model development, the effect of particle size distribution on the performance of rotary dryer to dry ammonium sulphate fertilizer assuming plug flow with axial dispersion pattern (PFDA model) for solid particle flow. The mathematical model development was carried out by combining the drying processes model with particle size distribution model. Particle size distribution models used are Rosin-Rommler model and Gamma distribution model. For simplicity, the model of drying processes of solid particles in the rotary dryer was developed by assuming of uniform air conditions (temperature and humidity) along the rotary dryer as in the entry conditions. The resulting differential equations were solved analytically under Matlab 6.1 facility.Since this model, solid hold up, and axial dispersion number were obtained from empirical correlations in the literatures. The drying rate of ammonium sulphate fertilizer in rotary dryer was estimated using isothermal diffusion model with effective diffusivity of moisture in the particle obtained from previous study [2]. Using Gamma function distribution, this research showed that for the value of the coefficient of variance (CV) less than 0.5, particle size distribution does not have significant effect on dryer performance. For the value of CV greater than 0.5, the dryer performance increase (or outlet solid moisture content decrease) with increasing the value of CV. The application of Rosin-Rammler model gives lower prediction of outlet solid moisture content compared to the application of Gamma function model.

Maturity effects on dielectric properties of apples from 10 to 4500 MHz

Dielectric properties of external surface, internal tissue and juice of Fuji apples during the last two months of tree-ripening were measured with an open-ended coaxial-line probe and a network analyzer at 24 °C from 10 to 4500 MHz. The firmness, soluble solids content (SSC), pH, moisture content and electrical conductivity were also measured to determine whether permittivity is related to apple quality. During the tree-ripening period, the permittivity and electrical conductivity did not reveal obvious trends. Moisture content and SSC remained essentially constant, while the firmness decreased and pH increased with maturity. No obvious correlations were found between permittivity and firmness, moisture content or pH. The linear relationship between surface permittivity and SSC was poor ( R 2 < 0.2). The best R 2 for linear regression between loss tangent of tissue and SSC and between dielectric constant of juice and SSC was 0.61 and 0.67, respectively, at 4500 MHz. Further studies are needed to assess the potential usefulness of dielectric properties for sensing apple maturity or internal quality.

Effects of Turning Frequency, Windrow Size and Season on the Production Of Dairy Manure/Sawdust Composts

On-farm composting offers the potential to significantly reduce problems associated with manure management including odors, pathogens, ground water pollution, and utilization costs. Three controllable variables that directly affect the efficiency of on-farm composting are weather, windrow size and windrow turning frequency. In temperate climates, low ambient temperatures and winter precipitation may lower composting temperatures and increase compost moisture contents, making composting rates harder to maintain. Windrow size directly impacts the depth of penetration of oxygen and the amount of compost exposed to high temperatures, potentially affecting composting rate. Windrow turning reduces moisture and temperature gradients within the compost windrows, but the benefits of frequent turning on composting rate have not been well documented. The objectives of this study were to understand the effects of these variables on composting rate, weight loss, volatile solids loss, moisture content, oxygen and temperature gradients, bulk density and particle size of unseparated dairy manure composted with hardwood sawdust (DM+S). Two composting windrow sizes (surface area to volume ratios of 0.9-1.1m2/m3 and 1.7-2.1m2/m3) and two turning frequencies (every three days and every ten days) in two different seasons (winter and summer) were evaluated. Results showed that the seasonal differences were primarily associated with compost moisture content, which varied as a function of ambient air temperature and humidity. Windrow size affected oxygen and temperatures in windrows. Before turning, the temperature averages (different depths) were significantly higher (p < 0.05) and oxygen concentrations averages were lower in the larger windrows (p > 0.1) than those observed in the smaller windrows. Turning frequency was positively correlated (r > 0.7) with bulk density, moisture and wet weight loss but not with volatile solid loss, particle size or oxygen and temperatures. Overall, the final compost properties (day 120) were very similar regardless of turning frequency, season or windrow size. In conclusion, dairy manure composted in larger windrows turned 3 times per month resulted in composts not significantly different than those made in smaller windrows turned 10 times per month.

The effect of frying conditions on moisture loss and oil uptake in yam slices (Dioscorea alata)

The effect of frying conditions on immersion on moisture loss and oil content were studied at different times in two yam varieties: Diamante 22 and Pico Botella. The experimental data adjusted itself to the first order exponential model for humidity transfer (r &gt; 0.9) for both cultivars. The humidity diffusion coefficient for the two varieties of yam fried at 140°, 160° and 180°C for 1 to 9 minutes were 8.11±0.76, 8.2±0.81, and 8.62 ±0.71*10-9 m2/s for the Diamante 22 variety, respectively, and 8.32±0.82, 8.38±0.78, 8.54±0.84*10-9 m2/s for the Pico de Botella variety. Activation energy was 24.43 kJ/mol for the Diamante 22 variety and 21.27 kJ/mol for the Pico de Botella variety. The results showed that there was higher oil absorption after 180 s and at 140°C while taking into account 0.377 kg water / kg solid moisture loss for Diamond 22 and 0.410 kg water / kg solid Pico de Botella at 180°C for 540 s.

Evaluation of the operational parameters' effect on mass transfer kinetics during osmosic dehydration of potato slices using sensitivity analysis based on artificial neural networks.

Osmotic dehydration, as a minimal processing method, has found increasingly wide prospects during the past few decades. This process involves mass transfer which is commonly modeled by applications of different procedures, mostly based on Fick's law. In this research, we approached the modeling process by first obtaining experimental measurement of potato’s solid gain, water loss and moisture content under different conditions of solution concentrations ( 5, 10 and 15% w/w), temperatures (30, 40 and 60oC) , potato to solution ratio (1:6, 1:8 and 1:10) as well as time intervals (1, 2, 3 & 4h). In order to evaluate the effect of changes in operational parameters on mass transfer kinetics, sensitivity analysis was performed. Artificial neural networks (ANN) was applied for modeling. The results exhibited how much powerful the model is in prediction of the system’s outputs, and high sensitiveness of these outputs to the ratio of potato to osmotic solution. Keywords: Potato, Osmotic dehydration, Sensitivity analysis, Artificial neural networks

Characterisation and composition of Municipal Solid Waste (MSW) generated in Sangamner City, District Ahmednagar, Maharashtra, India

This paper deals with the characteristics and composition of municipal solid waste (MSW) generated in Sangamner city. The composition of solid waste was studied by segregating it into different component, i.e., kitchen waste, paper, earth and fine material, slaughter house waste, leaves, metals, etc. These components were categorised into organic waste and inorganic waste. It was observed that Sangamner city produces around 61% organic waste, and the rest is inorganic waste. The characteristics of organic solid waste, i.e., pH, electrical conductivity, moisture content, organic carbon, nitrogen, phosphorus and potassium were evaluated. The analysis of organic content of MSW indicates that it is good source of nutrients for the agriculture sector whereas inorganic material can be used for landfill.