Chandana Ratnayake

SINTEF | Stiftelsen for industriell og teknisk forskning · Department of Process Technology

The fisheries and aquaculture industries are vital components of global food production, yet they also contribute to release of microplastics into marine environments, posing risks to ecosystem health and seafood safety. Among the contributing factors, the erosion of feeding pipes during the pneumatic conveyance of fish feed pellets stands out as a...

Barite is added to drilling fluids as weight material to increase its density. Over time, when the drilling fluids are left static in the annulus, gravitational forces will make the barite settle out. This settled barite is today the main reason for casing cut and removal process, which accounts for up to 50% of time related to P&A operations. Know...

Alumina is one of the most widely used materials today, with a total annual production of millions of tonnes of highly pure alumina. A large portion of this is used to make metal aluminum. Apart from that, a growing amount of alumina is used in ceramics, refractories, catalysts, and various other products. In nature, alumina can be found in differe...

Early CPFD simulation studies on designing a fluidized bed reactor for alumina chlorination showed that the model suffers from high particle outflow and dense phase bed channeling. The present study is aimed to optimize the previous alumina chlorination fluidized bed reactor model through modified geometry, parameter modifications, and improved mes...

Fluidization is a well-established and widely used technology in the process industry. The production stability and the large effective contact area between the active substances, resulting in high mass and heat transfer between the phases, are some of the main advantages of fluidization. However, this technology has not yet been adequately develop...

As in many real applications, in the world of fine powders and small particles, depending on the accuracy of the relevant method, there are uncertainties and vagueness in the parameters such as particle size, sphericity, initial solid void fraction, envelope density, etc. In some cases, there are different methods to measure a parameter, such as a...

Aluminum is one of the most used metals. Since aluminum has a unique combination of appealing properties and effects, it allows significant energy savings in many applications, such as vehicles and buildings. Although this energy-saving leads to lower CO2 emissions, the production process of aluminum still dramatically impacts the environment. The...

As a part of the new sustainable aluminum production process under study, alumina chlorination plays a crucial role. The relevant process is an exothermic reaction in a fluidized bed reactor. The solid alumina reacts with chlorine and carbon monoxide and produces aluminum chloride and carbon dioxide as the main products. Then carbon dioxide can be...

Removal of material from the surface due to particle impact is typically referred to as erosive wear. Impact erosion involves many parameters and several wear mechanisms. In the present study, sandblast type erosion tester was used to investigate the influence of particle size, impact angle and exposure time in impact erosion. Air-borne dolomite pa...

We are really pleased to have undertaken the organization of the 5th International Symposium of Reliable Flow of Particulate Solids (RELPOWFLO V), which was held in Skien, Norway, June 13–15, 2017 and to have compiled and published the selected research works presented during the event. These articles proceed the Preface. The RELPOWFLO series has a...

The article discusses issues related with storage of granular materials in silos made of corrugated sheets and reinforced with vertical ribs. Advantages and disadvantages of these structures are named, and typical technological solutions used by largest silo producers are presented. Moreover, basic assumptions of Eurocode 3 are discussed in the con...

In process technology, liquids, gas, or solids are well described with good predictabilities by established theories. In contrast, particulate solids or powders show inconsistencies in their behavior under different process conditions. Sometimes, they show solid-like properties and on another occasions, they behave like liquids. Particles may suffe...

Drill cuttings generated by offshore drilling operations are handled as a hazardous waste. In sensitive marine environments, the concept of zero discharge of waste is implemented. Hence the drill cuttings have to be stored within the drilling rig for a short time period until they are transported to the onshore treatment facilities. As the drill cu...

Investigation of the possibility of using a pneumatic conveying technique for thetransportation of dry drill cuttings is the main objective of this study. Both pilot-scale experimental and simulation approaches were carried out for sand, whichwas used as a model material that mimics the properties of dry drill cuttings. Sim-ulations based on the mu...

Computational fluid dynamics simulations were performed to investigate the behavior of dilute phase pneumatic conveying of plastic pellets in a horizontal circular pipe. The pellets are 200 μm in diameter and 1000 kg/m3 in density. A parametric study was performed to investigate the effects of turbulence model and model collision parameters on pres...

The manipulation (transport, mixing, segregation etc.) with powders and granular materials can be crucial for the quality of a final product. Detailed description and analysis of granular flow phenomena from the first principles is therefore very valuable. Here, simulations of granular mixing and segregation via discrete element method (DEM) of two...

The handling and processing of powders and granular materials can be crucial for the quality of a final product. Detail description and analyzing of granular flow phenomena from the first principles is therefore very valuable. In present study, simulations of granular mixing and segregation of binary‐size mixture via discrete element method are per...

Fouling in Mass Transfer

Three dimensional Computational Fluid Dynamics (CFD) simulations were performed to investigate the sensitivity of specularity coefficient in Johnson and Jackson particle-wall boundary conditions on the predictions of dilute phase pneumatic conveying characteristics in a horizontal pipe. The simulated pipe diameter is 30.5 mm and the pipe length is...

The present study focuses on investigating the possibility of using pneumatic conveying technique for the transportation of dry drill cuttings. Both pilot-scale experimental and modelling approaches were carried out for a model material which mimics the properties of dry drill cuttings. The model material is dry sand and the particle sizes are in t...

The offshore drilling operations generate huge volume of drill cuttings. Rig site transfer of cuttings can be a challenge both if pneumatic conveyors or screw conveyors are used. Especially, wet powder is a challenge since the particles become too sticky for easy handling or too dry for acting like a slurry. This paper presents the preliminary resu...

This study investigated the applicability of the multiphase particle-in-cell (MP-PIC) method for predicting pneumatic conveying characteristics. Three-dimensional computational particle fluid dynamics (CPFD) simulations were performed to assess the dilute-phase pneumatic conveying of plastic pellets in a horizontal circular pipe. The pellets were 8...

This review study mainly focuses on the application of Computational Fluid Dynamics (CFD) in the investigation of gas-solids multiphase flow systems and one would get a general overview of gas-solids flow models by having an insight to this article. The applicability and limitations of conventional models and recent developments of existing multiph...

Pressure drop and velocity profiles of dilute-phase pneumatic conveying of plastic pellets in a horizontal pipe were investigated through computational fluid dynamics (CFD) simulations. The diameter and the density of the pellets are 200 µm and 1000 kg/m3, respectively. Simulations were carried out for the air velocities range from 6 to 15 m/s and...

Fine particles grinded by various size reduction methods are often characterized by their particle size and size distribution as measured by analytical instruments. It is generally believed that particle size can play an important role in the determination of partile flow property. Particle shape, as important as particle size, also influence the f...

Pneumatic conveying is a material transportation process used on nearly every offshore rig, in which bulk particulate materials are moved over horizontal and vertical distances within a piping system with the help of an air stream. Using either positive or negative pressure of air or other gases, the material to be transported is forced through pip...

Fish farmers consider the cost of fish feed pellets as one of the most expensive factors in fish cultivation. Proper control of the handling and conveying systems is necessary to avoid damage and disintegration of the cylindrically shaped fish feed pellets. Pneumatic conveying is widely used to transport large quantities of fish feed. Proneness of...

A study of the influence of particle size and shape of carbon anthracite on the flow and packing behavior has been made. The candidate particle was first grinded by a lab-scale pin mill in order to manufacture different particle sizes and shapes. Image analyzer was employed for determination of particle shape size and shape.

The presence of fine particles in bulk solids has been known to affect the pneumatic transport characteristics. However, there is still no tool available to predict the exact nature of the variation of transport capacity with change in fines concentration in a bulk material. This article presents experimental findings on the nature of the variation...

Mass flow rate of solids is probably the most important parameter in pneumatic conveying systems. It is a challenging task to measure this parameter in gas–solid flows.A new and simple model is presented and described to calculate the mass flow rate of solids in pneumatic conveying systems, based on air flow and pressure measurements. The principle...

When conveying particulate materials, changes in size and shape of individual particles can be observed. These changes can have a great impact on the bulk powder and affect its flow properties in the pipeline. Changes can be wanted or unwanted depending on the whole process chain and final use of the powder. In this investigation, dextrose monohydr...

Accurate measurements of solids flow rate in pneumatic conveying systems have been a need for the different industries in which these systems are used. In this study, a system identification approach, which is called the Deterministic Stochastic Realization (DSR) method, is used to obtain a state-space model. The selection of inputs to the system i...

In many industries particulate materials are conveyed pneumatically, and it is both important and challenging to measure the mass flow rate of solids in a gas–solid mixture online. In this article we present some results from experiments carried out on a semi-industrial pneumatic conveying system located at the Department of Powder Science and Tech...

Although some literature can be found on the behavior of blow tanks, very few studies could be found on the pressure loss at the entry section to a pipeline (henceforth called entry pressure loss) from a top discharge blow tank in a pneumatic conveying system, even though its magnitude can be significant as compared to the total system pressure dro...

Any undesired change to the surface of a part or component of a system as the result of removal of small particles due to mechanical causes is usually termed as wear or erosion in the process industry. This phenomenon is common in many industrial and non-industrial situations. In the case of pneumatic conveying wear has been identified as a major d...

Although attrition during pneumatic conveying is a common problem, very few publications can be found in the open literature on this subject. The particle-to-wall impact is perhaps the predominant cause of degradation since the particle impinges the wall surface at high velocities in dilute phase pneumatic conveying. The most important factors appe...

A major challenge facing the designers of pneumatic transportation systems is how to scale up reliably based on the results from pilot-scale test facilities. Further, even if dense phase flow condition prevails at the start of the conveying system, it may be a dilute phase flow condition at the end of the pipeline. Hence, any scaling-up technique s...

Hole cleaning is still among the most important problems to handle in drilling operations and one of the most studied phenomena within the petroleum industry. Insufficient hole cleansing can lead to stuck-pipe, excessive pump pressures and equivalent circulating density (ECD), pack-offs, lost circulation, etc. all of which again can lead to loss of...

In this article experimental findings have been presented to show that the pressure drop coefficient (K) for vertical and horizontal pneumatic conveying for a given bulk material follows a certain pattern. The pressure drop coefficient for vertical pneumatic conveying for a given material has been found to be independent of any variation of particl...

Avhandling (dr.ing.) - Høgskolen i Telemark / Norges teknisk-naturvitenskapelige universitet The main objective of this investigation was to formulate a comprehensive scaling up technique for designing of pneumatic conveying systems by addressing the whole pipeline together with all accessories. Five different bulk materials together with five qual...

It has been shown that a simple model for pressure drop calculation based on classical Darcy's equation with some modifications can be used for pneumatic conveying. The predicted pressure values match with the test data reasonably well.

A brief survey has shown that although scaling-up techniques in pneumatic conveying systems have generally been based on laboratory-scale test data, there still exists a divergence of opinions about the right choice of certain basic parameters such as solids friction factor and air friction factor. In this article, a simple model for pressure drop...

It has been shown that a simple model for pressure drop calculation based on classical Darcy's equation with some modifications can be used for pneumatic conveying. The predicted pressure values match with the test data reasonably well.

During the last two decades, computer techniques have become well-accepted and useful tools for studying two- phase gas-solids flow processes. With the development of high speed high-capacity desk top personal computers, scientists and researches have extensively been using several large scale commercial computer codes to predict the flow phenomena...

During pneumatic conveying of particulate materials, changes in the size and shape of the individual particles can be observed. These changes can have a great impact in the bulk powder and affect its flow properties in the pipelines and can be wanted or unwanted according to the whole process chain and final use of the powder. In this investigation...