Prilling Process Research Articles

Power law liquid jets’ trajectories and instability during centrifugal spinning

Nanofibers are produced using a revolutionary technique called centrifugal jet spinning. This technique is known as an industrial prilling process, where small droplets are performed from breaking up of a thread liquid jet. Therefore, It has been used the curved jet to control the size of these small droplets and the break-up length. In this study, the linear instability of a power law liquid jet is investigated in the presence of centrifugal forces, gravity and surface tension. Furthermore, an asymptotic method has been applied to simplify the system of governing equations into a set of one-dimensional equations. Therefore, the trajectory of the power law liquid jet during the centrifugal spinning has been determined using the Roung-Kutta method. Further investigation has been done into wavenumber and the growth rate of the most unstable mode for various flow index numbers. From the linear instability results, it can be observed that when the rotation rate and gravitational force are high, shear thickening is more stable than shear thinning jets. We have also found that more viscous becomes longer jets and it produces larger droplet which is a crucial finding.

Characterization of sulphur particles: prills vs. granules

The oil and gas industry produces sulfur as a by-product when the feed constitutes of sulfur compounds. In the sulfur finishing process, two processes are used to convert molten sulfur to solid particles namely granulation and prilling. The prilling process for sulfur involves molten sulfur being pumped into perforated trays and then poured into an agitated water bath dropwise. This is the wet-prill process. This paper proposes to examine three samples of sulfur, one of which in the prilled form and the other two in granule form produced via two different granulation processes. The characterization tests included particle size distribution, strength measurement, structure analysis, and thermal calorimetry measurements. It was found that there are major differences between sulfur prills and granules when looking at physical and mechanical properties such as size, strength, and thermal properties. The three samples have been tested and analyzed to conclude the best process. The average strength of the prills is 2.4 N in comparison to the average strength of the normal and mixed granule being 3.26 N and 4.7 N, respectively. It is concluded that the granules were stronger than the prills but the prills were more uniform than both samples of granules.

The Mathematical Model for the Secondary Breakup of Dropping Liquid

Investigating characteristics for the secondary breakup of dropping liquid is a fundamental scientific and practical problem in multiphase flow. For its solving, it is necessary to consider the features of both the main hydrodynamic and secondary processes during spray granulation and vibration separation of heterogeneous systems. A significant difficulty in modeling the secondary breakup process is that in most technological processes, the breakup of droplets and bubbles occurs through the simultaneous action of several dispersion mechanisms. In this case, the existing mathematical models based on criterion equations do not allow establishing the change over time of the process’s main characteristics. Therefore, the present article aims to solve an urgent scientific and practical problem of studying the nonstationary process of the secondary breakup of liquid droplets under the condition of the vibrational impact of oscillatory elements. Methods of mathematical modeling were used to achieve this goal. This modeling allows obtaining analytical expressions to describe the breakup characteristics. As a result of modeling, the droplet size’s critical value was evaluated depending on the oscillation frequency. Additionally, the analytical expression for the critical frequency was obtained. The proposed methodology was derived for a range of droplet diameters of 1.6–2.6 mm. The critical value of the diameter for unstable droplets was also determined, and the dependence for breakup time was established. Notably, for the critical diameter in a range of 1.90–2.05 mm, the breakup time was about 0.017 s. The reliability of the proposed methodology was confirmed experimentally by the dependencies between the Ohnesorge and Reynolds numbers for different prilling process modes.

THE BEST MANUFACTURING PROCEDURE FOR THE COMMERCIAL PRODUCTION OF UREA, USING AHP BASED TOPSIS

Nitrogen is one of the most significant nutrients needed for the proper growth and development of crops and other plants. In synthetic nitrogen fertilizers, solid urea is the largest source of nitrogen (N) as a nutrient. Prilling, granulation, and hybrid systems are the commercial processes used for the production of urea. One of the biggest challenges involved in the determination and implementation of those alternatives is rationalized decision making. The objective of this research study is to evaluate these processes by considering some of the significant attributes like profit, environmental friendliness, process flexibility and reliability to determine which process is the most optimal. The results show that the prilling process is the best technology for urea production. It is the most optimal process in terms of profitability and reliability, and is therefore widely used in the fertilizer industry. Prilling is not the best option when it comes to the environment when compared to granulation. The granulation process is not the best fit for the commercial production of urea because it is not a reliable process, especially for high agricultural demands and market competition. The results show that it would be very difficult to keep up with the rapid growth of the population using the granulation process. If the environmental and urea quality concerns are considered, the hybrid system is the highest priority and may be preferred.

Behavior of poly(d,l-lactic-co-glycolic acid) (PLGA)-based droplets falling into a complex extraction medium simulating the prilling process

HypothesisPrilling process is one of advanced techniques for manufacturing microspheres of controlled and uniform size. In this process, homogenous polymer droplets fall into an extraction medium. The aim of this study was to identify the key parameters influencing the behavior of PLGA polymer-based droplets falling into a complex extraction medium, to select appropriate conditions for prilling. ExperimentsPolymer solutions and extraction media were characterized by determining their viscosity, density and surface tension. A simple model simulating the prilling process was developed to study droplet behavior. Particle shape and velocity at the air-liquid interface and during sedimentation in the container were analyzed step by step. The correlations between the variables studied were visualized by principal component analysis (PCA). FindingsDroplet deformation at the interface greatly affected the recovery and final particle shape. It depended on the viscosity ratio of polymer solution/extraction medium. The particle shape recovery depended on the viscosity and density of extraction media and polymer solutions. The solidification speed is also an important parameter. In media which the solvent diffused slowly, particles were able to relax and recover their shape, however, they can also deform during sedimentation and collision with the bottom of the cuvette.

Production of Fish Feed from Soy Residue and Shrimp Waste using Tapioca as Binding Agent

The most used fish feed in cultivation activities is commercial feed that spends most of total cultivation cost. One of the effort to solve this problem is providing homemade fish food. The pellet based on local waste raw materials can reduce dependency of commercial fish feed. One of the local wastes that can be used is soy residue and shrimp waste. Tapioca is used as a binding agent for fish pellet. The aim of the research was to study the effect of raw material composition and binding agent concentration on proximate value, performance and mechanical strength. The research was conducted in several steps such as raw materials pretreatment, the experiment of raw materials and binding agent formulation, mixing, extrusion, prilling process, drying process, and product analysis (proximate and performance analysis). There are five formulations of raw materials and three different of formulation on binding agents. The drying process was done in 50°C and the product was then analyzed. The result shows that formulation with 30% soy residue, 60% shrimp waste and 10% binding agent resulted in a product with good proximate value (11.23% moisture content, 17.64% ash, 1.33% fat, 25.10% fiber, 29.54% protein). Increasing the percentage of binding agents resulted in higher mechanical strength and higher performance.

Analysis of heat and moisture transfer during drying of urea particles

Urea is an inexpensive form of nitrogen fertilizer which is widely used in the agricultural industry. Urea as granule is produced through a drying process by which moisture content decreases to avoid operational issues. In this study, a numerical model is proposed for the drying of urea particles in the prilling process. The model is developed based on mass, heat, and hydrodynamic transfer equations for the urea particles and cooling air. The moisture and temperature variations of particles and cooling air at different heights of the prilling tower are calculated under different operating conditions. The shrinkage of particles due to the moisture loss during the drying process at different heights of the tower is considered. The model is validated with the real data obtained from a urea drying plant operated under steady-state condition. The result highlights that the model can be used to manipulate the operating parameters to improve product quality and to minimize urea temperature to prevent lamps and caking formation in the tower.

Effects of Prilling Process on the Microstructures and Electrical Properties of Lanthanum Chromite Ceramics

Lanthanum chromite(LaCrO3) with different amounts of PVB solution were synthesized by classical solid state reaction. We have studied the effects of different amounts of PVB solution( 0 mL, 1 mL, 2 mL, 3 mL) during prilling process on the microstructures and electrical properties of LaCrO3. The scanning electron microscopes, relative densities and resistivities of samples suggest: (1) the sinterability of LaCrO3is optimal among samples when adding 1 mL PVB solution to LaCrO3powder during prilling process. (2) sample with 1 mL PVB solution has the highest resistivity, while other counterparts’ resistivities have no distinct correspondence with the amount of PVB solution.

Spatial instability and break-up of viscoelastic Giesekus curved jets with surfactants

This paper deals with the prilling process, which is widely used to produce small spherical pellets from molten material. To deliver pellets of a uniform size, it is essential to understand the mechanism of the break-up of liquid jets. In this paper, we propose a model of the viscoelastic liquid jet using the Giesekus constitutive equation and investigate drop formation of a viscoelastic curved liquid jet with a layer of surfactants along its free surface. Furthermore, the governing equations have been reduced to one dimension by using an asymptotic analysis. Then, the steady state solutions for a spiralling viscoelastic liquid jet with surfactants have been found, and therefore the spatial instability analysis has been performed to derive the eigenvalue relation. Moreover, the Lax–Wendroff method has been used to solve the nonlinear evolution equations for determining the break-up lengths and drop formation of viscoelastic Giesekus curved jets with surfactants.

A novel method for the production of core-shell microparticles by inverse gelation optimized with artificial intelligent tools

Numerous studies have been focused on hydrophobic compounds encapsulation as oils. In fact, oils can provide numerous health benefits as synergic ingredient combined with other hydrophobic active ingredients. However, stable microparticles for pharmaceutical purposes are difficult to achieve when commonly techniques are used. In this work, sunflower oil was encapsulated in calcium-alginate capsules by prilling technique in co-axial configuration. Core-shell beads were produced by inverse gelation directly at the nozzle using a w/o emulsion containing aqueous calcium chloride solution in sunflower oil pumped through the inner nozzle while an aqueous alginate solution, coming out from the annular nozzle, produced the beads shell. To optimize process parameters artificial intelligence tools were proposed to optimize the numerous prilling process variables. Homogeneous and spherical microcapsules with narrow size distribution and a thin alginate shell were obtained when the parameters as w/o constituents, polymer concentrations, flow rates and frequency of vibration were optimized by two commercial software, FormRules® and INForm®, which implement neurofuzzy logic and Artificial Neural Networks together with genetic algorithms, respectively. This technique constitutes an innovative approach for hydrophobic compounds microencapsulation.

Genome mining and motif truncation of glycoside hydrolase family 5 endo-β-1,4-mannanase encoded by Aspergillus oryzae RIB40 for potential konjac flour hydrolysis or feed additive.

Two novel glycosyl hydrolase family 5 (GH5) β-mannanases (AoMan5A and AoMan5B) were identified from Aspergillus oryzae RIB40 by genome mining. The AoMan5A contains a predicted family 1 carbohydrate binding module (CBM-1), located at its N-terminal. The AoMan5A, AoMan5B and truncated mutant AoMan5AΔCL (truncating the N-terminal CBM and linker of AoMan5A) were expressed retaining the N-terminus of the native protein in Pichia pastoris GS115 by pPIC9KM. The specific enzyme activity of the purified reAoMan5A, reAoMan5B and reAoMan5AΔCL towards locust bean gum at pH 3.6 and 40°C for 10min, was 8.3, 104.2 and 15.8U/mg, respectively. The temperature properties of the reAoMan5AΔCL were improved by truncating CBM. They can degrade the pretreated konjac flour and produce prebiotics. In addition, they had excellent stability under simulative gastric fluid and simulative prilling process. All these properties make these recombinant β-mannanases potential additives for use in the food and feed industries.

Development of prilling process for biodegradable microspheres through experimental designs

The prilling process proposes a microparticle formulation easily transferable to the pharmaceutical production, leading to monodispersed and highly controllable microspheres. PLGA microspheres were used for carrying an encapsulated protein and adhered stem cells on its surface, proposing a tool for regeneration therapy against injured tissue. This work focused on the development of the production of PLGA microspheres by the prilling process without toxic solvent. The required production quality needed a complete optimization of the process. Seventeen parameters were studied through experimental designs and led to an acceptable production. The key parameters and mechanisms of formation were highlighted.

A Systematic Study on Manufacturing of Prilled Microgels into Lipids for Oral Protein Delivery

The development of novel systems with oral protein delivery as ultimate goal represents an important field of pharmaceutics. Prilling of protein-loaded polymeric solutions into lipid-based hardening baths could provide here an attractive formulating technology. As the obtained microgel dispersion can be directly capsule-filled, no drying step is required and thermal drug degradation is avoided. This study aims to find excipient combinations for the novel prilling process and investigate systematically diverse material and process factors. Bovine serum albumin and mono-N-carboxymethyl chitosan were selected as model protein and prilling polymer, respectively. The prilling suitability of 880 formulations was screened with 60 ternary phase diagrams comprising two co-solvents, 10 different glycerides, and three so-called complementary excipients. Preliminary capsule compatibility was tested for one month on 245 formulations in hard and soft capsules with different shell materials. Ternary phase diagrams' center points were used to evaluate morphology, encapsulation efficiency, and protein stability of the prilled microgels. As result, several formulations proved suitable for prilling and compatible for capsule filling. Statistical analysis using partial least square regression revealed significant factors regarding different quality attributes of microgel dispersions. Therefore, an improved understanding was obtained for this promising drug delivery approach.

Fatty acids for controlled release applications: A comparison between prilling and solid lipid extrusion as manufacturing techniques

The aim of the present study was to evaluate the solid state characteristics, drug release and stability of fatty acid-based formulations after processing via prilling and solid lipid extrusion. Myristic acid (MA), stearic acid (SA) and behenic acid (BA) were used as matrix formers combined with metoprolol tartrate (MPT) as model drug. The prilling process allowed complete dissolution of MPT in the molten fatty acid phase, generating semi-crystalline MPT and the formation of hydrogen bonds between drug and fatty acids in the solid prills. In contrast, as solid lipid extrusion (SLE) induced only limited melting of the fatty acids, molecular interaction with the drug was inhibited, yielding crystalline MPT. Although the addition of a low melting fatty acid allowed more MPT/fatty acid interaction during extrusion, crystalline MPT was detected after processing. Mathematical modeling revealed that the extrudates exhibited a higher apparent drug/water mobility than prills of the same composition, probably due to differences in the inner systems’ structure. Irrespective of the processing method, mixed fatty acid systems (e.g. MA/BA) exhibited a lower matrix porosity, resulting in a slower drug release rate. Solid state analysis of these systems indicated that the crystalline structure of the fatty acids was maintained after SLE, while prilling generated a reduced MA crystallinity. Binary MPT/fatty acid systems processed via extrusion showed better stability during storage at 40°C than the corresponding prills. Although mixed fatty acid systems were stable at 25°C, stability problems were encountered during storage at 40°C: a faster release was obtained from the prills, whereas drug release from the extrudates was slower.

Basic design methodology for a prilling tower

AbstractA design methodology was developed for prilling towers based on simultaneous heat, mass, and momentum balances. Basic principles of the prilling process and related sub‐models were considered for production of relatively mono‐size prills. The method was employed in the design of a prilling tower for production of ammonium nitrate prills from a highly concentrated solution. A special showerhead spray, operating under laminar conditions in a Rayleigh jet break‐up regime, was designed to enhance production of mono‐size prills. Air was used at ambient conditions. The droplets leaving the showerhead fall through the air stream in a counter‐current fashion. Heat transfer from particles to air includes cooling in the fully liquid state, solidification, and cooling in the fully solid state.The Computational Fluid Dynamics (CFD) simulation revealed the formation of a quiescent zone around the nozzle discharge region, which had a significant effect on decreasing the secondary disintegration of the droplets, and hence narrowed down the size distribution towards the desired value. The size of the produced prills was larger than the predicted value due to the formation of ammonia bubbles inside the prills.

Urea Finishing Process: Prilling Versus Granulation

Solid urea is the largest nitrogen fertilizer product which is produced in two forms of granules and prills. Although the chemical properties of both prills and granules remain similar, their different physical and mechanical properties are distinguishable and make them suitable for different application either as fertilizer or raw materials for chemical industry. The objective of this work is to analyses physical and mechanical properties of urea granules produced in two different plants in Malaysia using fluidized bed process and compare them with the imported urea prills to the country; hence make a process-product relationship for urea finishing processes. Results of size distribution of the samples show that the most of the granules fall in the size range between 2.82 and 3.06mm, whereas the prills size is around 1.65mm. Strength measurement using side crushing test also shows that the prills with the average failure load of 3.80N remain significantly weaker than the granules with failure load of 10-17N. Strength distribution of the particles also shows that a more uniform strength distribution is observed for the prills than the granules. It is concluded that the urea prilling process is the finishing process which produces the weaker and the more uniform size and strength of the particles than the fluidized-bed granulation process.

Instability of viscoelastic curved liquid jets

The industrial prilling process is a common technique to produce small pellets which are generated from the break-up of rotating liquid jets. In many cases the fluids used are molten liquid and/or contain small quantities of polymers and thus typically can be modelled as non-Newtonian liquids. Industrial scale set-ups are costly to run and thus mathematical modelling provides an opportunity to assess methods of improving efficiency and introduces greater levels of precision. In order to understand this process, we will consider a mathematical model to capture the essential physics related to a cylindrical drum, which is rotated about its axis. In this paper, we will model the viscoelastic nature of the fluid using the Oldroyd-B model. An asymptotic approach is used to simplify the governing equations into 1D equations. Moreover, a linear instability analysis is examined and the most unstable modes are found to grow along the jet. Furthermore, the non-linear instability is investigated by using a finite difference scheme to find break-up lengths and droplet formation.

Instability of viscoelastic curved liquid jets with surfactants

The prilling process is a common technique utilised in different applications in many industrial and engineering processes. Typically in such a process a liquid jet emerges from an orifice and thereafter breaks up into small spherical droplets of various sizes due to interfacial instabilities. As is common in many industrial applications the fluid used is often a mixture of various fluids and will typically contain polymers or other additives which will cause the fluid to behave like a non-Newtonian fluid. Furthermore, surfactants may be used in such processes to manipulate the size of the resulting droplets. In this paper, we model the fluid as a viscoelastic liquid and use the Oldroyd-B constitutive equation. We reduce the governing equations into a set of one-dimensional equations by using an asymptotic analysis and then we examine steady state solutions for viscoelastic rotating liquid jets with surfactants. We thereafter examine small perturbations to this steady state to investigate both linear and non-linear instability of the liquid jet.

Critical parameters involved in producing microspheres by prilling of molten lipids: From theoretical prediction of particle size to practice

The aim of this work was to identify the key parameters which influence the running of the prilling process with lipid material from the initial melting to the formation of solid microspheres. The microsphere size would essentially result from break-up at the Rayleigh–Weber’s wavelength which mostly depends on the liquid properties (mass density, surface tension and dynamic viscosity). After molten liquid extrusion through the nozzle, the cooling rate is very fast and the instantaneous temperature of the liquid jet decreases rapidly of 0.2–0.3°C during the duration of the droplet formation (1–2ms). This leads to no significant modification of the physical characteristics of the lipids and only a very slight change in the dynamic viscosity. Consequently, no significant effect on the optimal wavelength λW and on droplet formation can occur. However, coalescence of liquid droplets has been observed during their fall, probably caused by turbulence into the air column, leading to a minor population of larger microspheres.

Flow Analysis of Melted Urea in a Perforated Rotating Bucket

A comprehensive study of the internal flow field for the prilling application in a perforated rotating bucket has been carried out. Computational Fluid Dynamics (CFD) is used to investigate the flow field of urea melt inside the perforated rotating bucket. The bucket is mounted at the top of the prilling tower. In prilling process, urea melt is sprayed by the perforated rotating bucket to produce the urea droplets, which falls down due to gravity. These drops fall down through a cooling medium and solidify into prills. The velocity field in the bucket is very important to study, as it has great effect on the heat and mass transfer performance in prilling process. ANSYS 14.0 CFD package is used to simulate and Design Modeler and Catia V5 are used for geometrical model of the perforated prilling bucket. Velocity distribution on different planes are obtained and discussed.