Master of Science in Sustainable Process Development

Permanent URI for this collectionhttp://192.248.9.226/handle/123/28

Browse

Now showing 1 - 20 of 40

item: Thesis-Full-text
Analysis and optimization of cyclone separators by using rans
De silva, MSM; Narayana, M
Many types of particulate matter collectors are used in the industry to separate particulate matter from the gaseous streams. Among various type of particulate collectors, cyclone separators are one of the most extensively used gas cleaning equipment because ofthey are inexpensive; easier to fabricate, and could be designed to stand under harsh operating conditions. Due to this extensive usage in the industry, many theoretical and experimental studies have been carried out and empirical models were developed to predict cyclone separator’s most important operational parameters. These models have many limitations of illustrating flow behavior properly due to the complex nature of the cyclone gas-solid flow behavior. Computational Fluid Dynamic (CFD) simulation could be useful to predict cyclone performance as an alternative approach. This work represents a CFD simulation of a Lapple cyclone separator using OpenFOAM software. Cyclone simulations have been carried out using turbulence models associated with the Reynolds Average Navier Stokes (RANS) equations. Multiphase Particle in Cell (MPPIC) method was used for the particle modeling, in which particle interactions with other particles were represented by models. The perditions of simulations have been compared both mutually and to literature in terms of cyclone pressure drop, gas-solid flow pattern and collection efficiency. RANS model fairly predict the gas-solid flow pattern of the cyclone. Pressure drop and collection efficiency of cyclone well fitted to the experimental results in the literature. Optimum values for inlet gas-solid velocity and particulate loading rate for the Lapple cyclone were obtained by RANS analysis. Pressure drop variation with gassolid inlet velocity which has been obtained by this analysis could be useful to minimize the energy requirement while maintaining the required collection efficiency.
item: Thesis-Full-text
Assessment of environmental impact for accidental release of heavy gas
Gunawardena, YN; Gunasekera, MY; Narayan, M
An air dispersion model can be used to mathematically simulate air pollutants dispersion in the ambient atmosphere. These dispersion results can be used to predict their environmental impact, concentrations and movement. Such predicted data of hazardous gases released after a chemical accident are valuable since it can be used to provide timely information to emergency response providers as well as to make decisions on siting chemical plants at safe distances from settlements during plant development stages. Dense gas dispersion is the focus of this research as several pressurized dense gas release accidents have happened during the last few years in this country. These gases form clouds heavier than air when released to the atmospheric environment. In this study a mathematical model for the dispersion of heavy gas due to an accidental release is presented in order to determine the environmental impact. The heavy gas model was then used to simulate the dispersion of negatively buoyant and highly toxic chlorine gas to illustrate the use of heavy gas dispersion modeling in hazard analysis. A worst case scenario study with stability class A, was used for an accidental release of 900kg of chlorine from a location in Kaluthara district in Sri Lanka. To determine the impact of the release probit analysis, safe distance and hazardous time period calculations were done. From the model results, for a 900kg chlorine release, safe Immediately Dangerous to Life or Health (IDLH) distance was above 490m. Within this hazardous zone the safe time period starts after 5.44 minutes from the release. Further, this model can be used to predict information, such as concentration variation of the substance released with time and, cloud dimensions such as height and radius. For validation, experimental data in literature were collected and a sensitivity analysis was done to identify the best values for the model parameters.
item: Thesis-Abstract
Bacterial cellulose production by acetobacter xylinum in aerated, agitated and attached system
(2016-02-20) Dissanayake, DMSC; Ismail, M
Cellulose is the most common biopolymer on earth and has been identified as a major building material of all plants. It is common not only in the higher order plants, but also in microorganisms. Plant Cellulose formed to be structural materials for higher order cell, while bacterial cellulose (BC) plays a protective action in its cell. Most common genera which produce BC are Acetobacter, Rizobium, Agrobacterium and Sarcina. It was found that Acetobacter xylinum has the highest capability to produce cellulose rather than other species performed in the same condition. BC could play a very important role as a versatile biomaterial in modern industries as it has high purity, high mechanical strength, high water holding capacity and high crystalline ability compared to plant cellulose. Most of the BC studies have been carried out with Static Fermentation (SF) techniques. However static systems have the drawback when it comes to an industrial usage, due to the reduction of dissolved oxygen (DO) and pH of the media with the increase of cell mass increment and cellulose production. Therefore agitated and aerated systems were developed to overcome the limitations of the SF. Rotating Biological Fermentor (RBF) could be considered as both an agitated and aerated system. This was developed to overcome problems which hindered BC production in SF system. In this research, lab scale RBF was designed and fabricated to operate in three different agitator speeds. Substrate media was prepared using sterilized coconut water inoculated with Acetobacter xylinum. pH and DO variations in RBF and in SF were recorded for 7 to 8 days. Yield of cellulose production and the cell mass was also investigated during the fermentation period for different agitator speeds on both systems. Initial pH of the SF and RBF was 5.3 and with time it reached a steady value of 3.4 whereas in SF the pH decreased further. In the case of DO, the initial value was 1.47 mg/l. There was a continuous drop of DO in SF while in RBF it fluctuated within the range of 0.25 to 0 .43 mg/l. Cellulose production was 0.889×10-10 g CFU-1 ml-1 for SF and 1.92x10-10 g CFU-1 ml-1 for RBF respectively after 8 days. These investigations indicate that the RBF system could supply air to the culture medium in a continuous manner and was able to regulate DO when compared to a SF system. Further pH variation was also minimized in RBF compared to SF favoring the growth of cell mass and thereby yield of cellulose. A mathematical model for the synthesis of BC in a RBF system was also developed. The growth of cellulose is considered as a cellulose film from a mono culture. Glucose depletion, cellulose production and microbial growth in the fermentation medium were explained using the developed models. It was shown that the simulated and experimental results were in close agreement. In addition, the model was successful in predicting yield of cellulose at different rotational speeds of the RBF unit. On conclusion it could be said that RBF is a better system to generate cellulose when compared to SF and the developed model could explain the cell mass and cellulose growth profiles which could be useful in mass scale production.
item: Thesis-Full-text
CFD modeling of a centrifuge for oil - water separation
Thilakarathna, HGSM; Narayana, M
Centrifugation is an efficient, economical and environmentally friendly method to remove un-desirable water content from oil and water mixtures and separate out the desired oil content.Moreover, the disc stack centrifuges are widely used for separating liquids of different densi-ties and applied in industrial coconut oil clarification as well.The main focus of this research work is to model the fluid flow inside the Westfalia discstack centrifuge using Ansys Fluent and identify the flow behavior. With the availability of thelimited computer hardware facility, the model has been run without the discs to avoid com-plexities. In the developed 3 dimensional model, the fluid dynamic behavior of the multiphaseflow has been considered and modeled using the VOF multiphase model available in fluent.The step by step procedure of the model development has been discussed such as the veryfirst stage of geometry selection, drawing and importing to the fluent, mesh generation, allsolution set ups and even the two stage simulation procedure.The simulation results of this research work provides an out line of the resulted flow param-eters of velocity and pressure profiles, turbulent effects such as turbulence intensity, turbulentkinetic energy, and specific dissipation rate and also the phase volume fractions which havebeen saved in every critical stage of the simulation process. Despite the phase volume fractionwhich has been experimentally validated, all other results were theoretically validated.CFD modeling of flow behavior inside the centrifuges is not a popular topic among theresearchers due to the complex flow patterns and the requirement of advanced computer hard-ware facility. However this research work provides a platform to model the similar flow be-haviors and even to model the same case including the discs.
item: Thesis-Abstract
Chemical process route selection based on assessment of inherent environmental hazard, occupational health and safety
(2015-03-01) Warnasooriya, S; Gunasekera, MY
Chemical process route selection is one of the main design decisions that needs to be taken during the preliminary stages of chemical plant design and development. A chemical process route is considered as the raw materials and the sequence of reaction steps that converts them in to desired products. Previously, the most important factor considered in selecting the chemical process route was plant economics. However, now other issues such as safety, environment and occupational health have also become important considerations. Therefore, at early stages of chemical process plant design and development it is necessary to apply methodologies to identify and assess environmental, occupational health and safety hazards involved in the process routes. This work proposes a methodology for assessing chemical process routes to manufacture a chemical based on inherent environmental, occupational health and safety hazards. The method developed in this work can be used during early design stages of a chemical process plant. The process route selection is done based on impacts due to emissions from the ongoing operational conditions of the plant. It considers the potential toxicological impacts on the environment, potential impacts on the occupational health due to fugitive emissions and the potential chemical and process safety impacts within the plant. As the outcome of the methodology, an integrated index called “Inherent Chemical Process Route Index” (ICPRI) is proposed which can be used for the selection of the ‘best’ chemical process route for a chemical process plant, based on inherent environmental hazard, occupational health and safety (IEHS). The lower the ICPRI the more inherently environmentally friendly, inherently occupational healthier and inherently safer the route is. The methodology developed in this work can also rank alternative chemical process routes based on inherent environmental hazard or occupational health hazard and or safety hazard separately. The method was applied on four possible process routes to produce acetone. The propene oxidation route showed the lowest ICPRI value indicating potentially the ‘best’ chemical process route for acetone manufacturing process based on the IEHS assessment. Keywords: Inherent Environmental hazard, occupational health, Inherent Safety, Chemical process route
item: Thesis-Abstract
Comparison of suitaility of different binding materials in briquette forming
Shyamalee, AMD; Amarasinhe, ADUS; Senanayake, NS
The process ofmanual saw dust briquette making was tested with different binding agents in the laboratory with 1.5 ton hydraulic jack. Dry cow dung, wheat flour and paper pulp were selected as binding agents. This briquette was designed with size 35mm Diameter x 35mm length and cylindrical shape. Saw dust was sieved through 2mm screen mesh and 6 different samples were prepared with sieved saw dust and each binding agents as 5%, 10%, 20%, 30%, 40%, and 50% dry basis. Cow dung samples were shown difficulties of mould detaching. Wheat flour and paper pulp binder samples with 5%, 10%, and 20% (dry basis) binders also failed onmould detaching due to breaking of briquettes. The minimum requirement of binder percentage was found to be with 30% dry binder of wheat flour and paper pulp to form stable briquette and hence it was selected for comparison of properties. Densities of briquettes with 30% binder of wheat flour and paper pulp were 373.7 kg/m3 and 289.8 kg/m3 respectively. Compression behavior of briquettes with 30% (dry basis) binding agents was examined for cyclic loading applied using the hydraulic jack. Maximum load of 110kg (35.9 kg/cm2 pressure) was maintained for all the experiments. Number of force cycles needed to reach the pre-determined load was recorded; paper and wheat flour binder briquettes were needed five cycles and cow dung briquettes were needed additional two cycles. Natural drying time was evaluated at 86~89% relative humidity and 25~30oC ambient temperature, It was recorded that briquettes came to 25% moisture content (Wet basis) within 33 hours and 20% moisture content (Wet basis) within 35 hours. Compressive strength of the briquettes was tested for binder percentages of 30%, 40% and 50% (dry basis)of wheat flour and paper pulp binders. Results have indicated that compressive strength increased with the increase of binder percentage. Paper binder briquettes have comparatively high compressive strength in the range of 0.124N/mm2 to 0.238N/mm2 while wheat flour briquettes have 0.032N/mm2 to 0.055N/mm2. Calorific values of raw materials and briquettes were tested. Briquettes obtained from 30% paper binder and 30% wheat flour binder has calorific values of 18.14MJ/kg and 20.04MJ/kg respectively.
item: Thesis-Abstract
Conversion of dye sludge to RDF
(2014-08-08) Rubasingha, SN; De Alwis, A; Wijekoon, S
In Sri Lanka the Dye sludge production from textile industry is large. The large amount of produced dye sludge needs to be properly managed otherwise it will cause lot of environmental problems. Currently textile industries in Sri Lanka use the landfilling method to dispose dye sludge. Because of the landfilling method lot of environmental problems are surfaced, such as emission of toxic gases, ground water pollution and bad odour in environment. This study investigates the feasibility of using the waste dye sludge as fuel called Refused Derived Fuel (RDF). The method is used to produce RDF from dye sludge is mix dye sludge with other wastes available in textile industry. Other waste types which are supposed to use mix with dye sludge are fabrics, paper waste and saw dust. The mixing of waste dye sludge with other wastes in different compositions are investigated. Also different quality parameters of waste sludge and mixtures (after mixing with other wastes) are analysed.Calorifc values of waste sludge with different moisture content and mixtures with different waste fractions ,ash content,sulfer content,chlorine content,heavy metal content are main characterization parameters. Results analysed and it revealed that by mixing dye sludge with other wastes calorific value can be increased from 6 MJ/Kg to 22 MJ/Kg. By considering availability of the waste types during the last year most commonly used mixture composition is selected. We propose that waste dye sludge mixed with other waste types in textile industry is a suitable and effective alternative energy source in Sri Lanka
item: Thesis-Full-text
Development of a computational model for biofilm based microbial fuel cell
(2016-09-15) Marapana, NMNC; Rathnasiri, PG
Studies on Microbial Fuel Cells (MFC) as Power production units are of increasing interest, because it can convert a variety of bio-degradable organic compounds into electricity. In a MFC; biological, chemical and electro-chemical reactions take place resulting in a change of concentration of substrate, suspended solids and growth of a biofilm leading to a production of an electrical current. In this study a dynamic mathematical model is developed that represents the behavior of microbial fuel cell using set of derived equations those describe the consumption of substrate by microorganisms, production of oxidized mediators using reduced mediators, growth of microorganisms in the bulk liquid and the biofilm attached to the anode and production of current at the electrode surface. The system consists of a bulk liquid with suspended cells and the anode with an attached biofilm. Performance of a MFC is evaluated by analyzing the variation of production of current with time, variation of concentration of components (microorganisms, substrate, oxidized mediator and reduced mediator) in the bulk liquid with time and variation of concentration of mediators at the electrode surface with time in various combinations of selected operating parameters (reaction rate, exchange current density and total cell resistance). It was found that, higher the reaction rate the production of current by the fuel cell is high. At the same time, reaching of maximum current production is rapid in the systems simulated with high reaction rates compared to that of the others. On the other hand, high exchange current density values give relatively low current production from the cell where the low exchange current densities give somewhat high current production. Variation of total cell resistance affects in a similar manner on current production. That is, when the cell is simulated with high cell resistance values, the production of current is low. But, the current production sustain for a rather long period.
item: Thesis-Full-text
Development of new hybrid adsorption coagulation method for palm oil mill wastewater treatment
(2015-10-19) Asdullah; Rathnasiri, PG
Activated carbon has been using as an adsorbent for wastewater treatment for decades. It has also been reported that use of fly ash to adsorb impurities in waste water treatment .The main objective of this study is to optimize hybrid adsorption-coagulation method for removal of color, BOD, COD, TDS, TSS and Turbiditypresence in palm oil mill effluent (POME).Mango pit is a natural environmental friendly coagulant and have many advantages over commercially available aluminum and ferric salts used for water and wastewater treatment. Fly ash has the proficiency to be recycled and used various times. This study further investigates the combination of fly ash with mango pit. Three sets of experiments were performed using jar test method namely; only adsorption using fly ash and the second is using mango pit as coagulant and the third one is using fly ash in combination with mango pit in hybrid adsorption-coagulation system. In the first set of experiments only adsorption process was studied using fly ash as an adsorbent by varying particle size and weight. Samples of 300ml wastewater were used with variable fly ash particle size ranging from 355μm and 500μm and operated at 200rpm. Results showed that with decrease in particle size the amount of pollutant adsorbed increased, therefore process was optimized using 355 μm granule size and 90g of dose producedresults in color reduction as 91%, COD 82%, BOD5 83%, TDS 74%, TSS 78% and turbidity 93% respectively. In second set of experiment mango pit was proved to be an excellent coagulant to be used for wastewater treatment which gave reduction of pollutants up to 70%. Further in the third set of experiments equal amount of wastewater samples were investigated using hybrid adsorption-coagulation method by varying concentration and pH of adsorbent-coagulant as (50g-0.6ml, 70g-0.8ml, 90g-1.2ml). When applying hybrid method an improved trend was recorded comparing with previous resultsin reduction of Color from 91% to 97%, COD from 82% to 89%, BOD from 83% to 94%, TDS from 84% to 93% and TSS from 88% to 96% respectively. Hybrid coagulation-Adsorption method has not only positive impact on reduction of wastewater quality parameters but also very cost effective and environmental friendly process. Other advantages include low sludge production and the less amount of coagulants used.
item: Thesis-Full-text
Development of updraft gasifier and performance analysis for different types of biomass materials
(2015-10-19) AMIN, M; Narayana, M; Gunasekera, M. Y.
Traditional fossil fuels such as coal, gas and oil are still major candidates to fulfill the energy requirement but their depletion at sharp rate due to increase in demand is at alarming condition. High prices and environmental pollution issues associated with fossil fuels has diverted thefocus of the world to find out the new energy roots. Biomass is one of energy candidates, environment friendly, which can be utilized to generate heat and power. Biomass can be converted into useful products by thermochemical process such as gasification. This study focuses on to design and development of pilot scale updraft gasifier with gas cleaning unit. Performance analysis in terms of producer gas composition, LHV of producer gas, A/G,G/F, gasifier efficiency and gasification efficiency for different biomass materials at different air flow with and without the packing plate was studied. Other main objective was to find out energy potential of mango pit shell as new biomass material and its comparison with coconut shell, ginisyria (Gliricidia sepium) and a mixture of 50%, 25%, 25% coconut shell, mango pit shell and Gliricidia sepium respectively as an arbitrary selection. Bench scale updraft gasifier was designed and fabricated. Elemental analysis for each biomass was performed in laboratory to find out the properties such as moisture contents, ash contents, volatile matters etc. Reactor was operated successfully, producer gas and other useful byproducts was obtained. Producer gas was analyzed for compositional analysis as major product and reactors performance parameters was calculated. It has been observed that biomass we utilized contains the sufficient energy potential. In case of without packing plate at ER of 0.2 LHV (MJ/Nm3) of producer gas was 4.40, 3.35, 4.20, 3.14 for coconut shell, mango pit shell, ginisyria and mixture respectively. When air flow rate increased, ER increased up to 0.25 it was observed that LHV of producer gas has been decreased. With packing plate experiments it has been found that LHV of producer gas at ER of 0.2 is 4.02, 3.29, 3.70, and 3.21 for coconut shell, mango pit shell, ginisyria and mixture respectively. In packing plate case as well with increase of air flow decrease in LHV of producer gas was observed. Collectively without packing plate results obtained are good as compare to with packing plate case. Gasifier thermal efficiency for different biomass has been found in the range of assumed designed value which was 70%. Bio-char and black condensate was obtained as valuable by products which can be utilized for different applications. Mango pit shell which is thrown as waste can be utilized as biomass to generate the heat and fulfill the respective industry energy demand especially juice industry. Results without packing plate were found good rather than with packing plate.
item: Thesis-Abstract
Effect of drying temperature on the composition of hydro distilled cinnamon bark oil
(2015-06-26) Kumarage, NDI; Amarasinghe, ADUS
Cinnamon (Cinnamomum Zeylanicum) is an endemic plant popularly known as “Kurundu” in Sri Lanka. Cinnamon yields mainly cinnamon leaf oil and cinnamon bark oil. Cinnamon bark oil produces by processing dried cinnamon chips. Composition of cinnamon bark oil varies due to many factors including the type and quality of cinnamon chips. Good quality cinnamon chips can be produced by uniform drying. Present study examines the effect of air drying temperature during pre processing of cinnamon chips on the volatile organic compounds of cinnamon bark oil extracted by the method of hydro-distillation of cinnamon chips. Laboratory scale tunnel dryer fitted with an electrical heater was used to dry cinnamon chips at five different air drying temperatures; ambient temperature, 35 °C, 40 °C, 45 °C and 50 °C. The extracted cinnamon bark oil was analysed by gas chromatography-mass spectrometry (GC-MS). A total of 16 compounds were identified, cinnamaldehyde-E, cinnamyl acetate, linalool and eugenol, in that order, being the main volatile organic compounds. Results indicated that air drying temperature of cinnamon chips significantly altered the composition of cinnamon bark oil. Percentage of Cinnamaldehyde-E increased with the increase in drying temperature. High percentage of monoterpenes, cinnamaldehyde and cinnamaldehyde derivatives such as cinnamyl acetate, and 2-methoxy-cinnamaldehyde was observed at low temperature drying. Increase in drying temperature resulted in substantial losses in certain oxygenated terpenes and sesquiterpene. The percentage of cinnamaldehyde-E could be substantially increased by hot air drying but at the expense of oil yield. Keywords: Bark oil, air drying, volatile organic compounds, cinnamon chips
item: Thesis-Full-text
Effect of particle size and secondary air for particulate biomass combustion in a bubbling fluidized bed reactor
(2020) Silva GGSN; Narayana M
Biomass combustion is used as basic technology to generate heat by humans for millennia. With the incremental needs of modern man, biomass combustion still plays a major role in heat and power generation. In Sri Lankan context, biomass combustion is extensively used in manufacturing industries for boilers, furnaces, dryers, etc. Even though biomass is abundantly available as an energy source in Sri Lanka, industrial biomass combustion systems are operating under very low efficiencies. Operating these industrial combustion systems in an optimum manner will help in numerous ways to industries, environment and society. In this study, particulate biomass combustion in a bubbling fluidized bed combustor model is used to evaluate optimum secondary air flow rate rates and particle sizes. First Proximity of particulate biomass (saw dust) was conducted to find out moisture and volatile content, then sieve analysis was conducted to segregate and name the particle sizes. Different particle sizes were fluidized using measured primary air flow and combusted under varied secondary air flow rates and obtained maximum temperature achievement in three distinct locations (top, middle and bottom) in the fluidized bed reactor by using installed temperature transducers. Secondary air flow rates and temperature results were tabulated for each particle sizes to analyze temperature variation. Matlab CFTool feature was used to generate surface fits for all three location (top, middle and bottom) temperature variation against particle size and secondary air flow rates. After evaluation results and surface fits, Optimum operating secondary air flow rates and particles sizes were identified for used lab scale bubbling fluidized bed combustor. Recommendations were suggested for industrial scale particulate biomass combustion systems such as boilers, furnaces, etc. for optimum operation based on lab scale system results.
item: Thesis-Full-text
Effect of particle size on packed bed biomass combustion
(2018) Rajapaksha, GDM; Narayana, M
In this thesis, particle size effect on biomass (rubber-wood) combustion in a packed bed reactor was investigated in experimentally. Mass loss rate, bed shrinkage rate, temperature profile at different bed locations and gas compositions in the out-of-bed flue gases were measured at a constant primary air flow rate. In this study used a fixed batch of biomass. An external heat source was used to ignite the biomass initially and after ignited the biomass, removed the external heat source. Rubber-wood cubes were fired with size ranging 25mm, 38mm, 50mm and 63mm. As time pass, the height of the packed bed is decreasing due to shrinkage of the bed and also the weight of biomass is reducing with time. It is found that at the operating condition of the current study, burning rate of biomass particle is higher with smaller fuel size; and also smaller biomass particles are faster to ignite than the large biomass particles and have unique combustion stages; on the other hand, larger biomass particles produced a higher flame temperature. Larger particles also cause the combustion process becoming more transient where the burning rate varies for the most part of the combustion process. And also biomass combustion time (operational time) is increased with increasing biomass particle size. And here calculate the percentage of excess air, when increased the particle size, amount of excess air release is high. Therefore, need to control the amount of primary air supply when increased particle sizes.
item: Thesis-Abstract
Effect of ultrasound mixing on esterification of FFA in rubber seed oil
(2014-08-20) Malliyawadu, MND; Gunawardena, SHP
There is an increasing demand for biodiesel, because of its environmental friendly nature and especially due to the depletion of petroleum reserves. Currently, most of the biodiesel is produced from edible oils under base catalyzed transesterification. However, large amount of non edible oils are underutilized and can be converted to biodiesel. The difficulty with base catalyzed transesterification of non edible oil is its higher content of free fatty acids. These free fatty acids react with base catalyst to produce soap and which prevent the separation of ester from the glycerin. The reduction of free fatty acid content of rubber seed oil under catalyzed etherification with ultrasonic mixing (20 kHz, 500 W) was investigated in this study and compared with mechanical agitation. Batch etherification of rubber seed oil was carried out using 2.5:1 (w/w) methanol/ FFA and 0.05:1 (w/w) H2S04/FFA and effect of ultrasound frequency, reaction temperature and reaction time were studied. With the increase of ultrasonic amplitude, mixing intensity was increased and as a result, maximum FFA% reduction of 88.9 observed at the amplitude of 75% and at a temperature of 55°C. When the etherification reaction carried out at elevated temperatures, it shows a greater reduction of FFA% under ultrasonic and mechanical mixing. However, optimum result was gained under mechanical mixing at the temperature of 55°C and at a reaction time of 30 min and the final FFA% of rubber seed oil was 2.75. At the same reaction conditions, acid etherification of rubber seed oil under ultrasonic mixing achieved a FFA% of 3.31.
item: Thesis-Abstract
Implementing a simulator for a process plant with a control system
(2016-01-16) Piyarathna, WADD; Haugen, F; Narayana, M
Intention of this research study is to develop a simulator with LABVIEW for a reactor/flash/recycle plant which is described in Edgar et al. (2003). The material balances, component balances and energy balances for each unit were used to develop this simulator. Plant wide control system was proposed in reference book Process Dynamics and Control (Edgar et al., 2003) was simulated to find out best control parameters for the plant. PID controllers are used to control required parameters and PID controllers were tuned using Good Gain method and trial and error as appropriate. The dynamic mathematical models are based on differential equations which are developed for the reactor, flash unit, and recycle tank and for the heat exchangers. The holdup condition was assumed when developing differential equations in the Edgar et al. (2003) but mathematical model developed for this research work eliminated that assumption and further developed the ODEs. These developed equations are solved using the Second Order Runge-Kutta method, in the library function of Lab VIEW software. The steady state values given in the reference book was used to check the accuracy of the simulator and the simulated plant reached steady state output for the relevant inputs. Instead of PID controllers some of the logical controllers were used for smooth operation of the plant. Special functions of LABVIEW were used to speed up the simulator to reach steady state conditions very fast which in actual time will take of more than one day. This simulator is really a good option to find different conditions of the reactor/ flash/ recycle plant, which are impossible to check in an actual plant which can create very unsafe conditions and damages for the equipment and people.
item: Thesis-Full-text
Influence of CO₂ injection on biomass updraft gasification process
Lenagala, IRND; Narayana, M
The utilization of fossil fuels has enabled large-scale industrial development and largely supplanted water-driven mills, as well as the combustion of wood or peat for heat. The burning of fossil fuels by humans is the largest source of emissions of carbon dioxide, which is one of the greenhouse gases that allows radiative forcing and contributes to global warming. This study focuses on to performance analysis of updraft gasifier with the injection of CO2 as gasifying agent. During the study CO2 was fed in to updraft gasifier in different feed ratios and producer gas composition was analyzed. Rubber wood chips were used as the feed stock of gasifier and testings were carried out in input fractions of CO2 to analyze its impact of CO yield.
item: Thesis-Full-text
Investigation of CO2 sequestration possibility via aqueous phase mineral carbonation using industrial waste materials
(2020) Nanayakkara SG; Rathnayake HHMP
Carbon dioxide (CO2) as the most vital greenhouse gas in the earth’s atmosphere plays a major role in maintaining the global temperature. Higher concentrations of CO2 in the atmosphere, increases amounts of heat entrapped in the atmosphere. Thus, the environmental temperature increases when the CO2 concertation increases and results in global warming. The global CO2 emission was approximately 35.3 billion metric tonnes in 2018 and, it is predicted to be increasing up to 43.08 billion metric tonnes by 2050 as per the prevailing trends in statistical analysis. Therefore, maintaining an acceptable concentration of atmospheric CO2 is required. In this situation, anthropogenic CO2 capture and storage technologies have emerged to reduce the atmospheric CO2 concentration. Among the carbon capture methods, post-combustion CO2 capture technologies are the most common as there is the advantage of ability to retrofitting to existing plants. Mineral carbonation is considered as a natural and exothermic process among available post combustion CO2 capture technologies, which gives promising results in CO2 sequestration by storing as mineral carbonates. Suitable materials for mineralization are natural minerals like silicate rocks, serpentine, olivine minerals or else industrial wastes like oil shale ash, steel slag, paper mill waste, fly ash or mine tailing, etc. In this study, the existing literature on CO2 sequestration capabilities through aqueous phase mineral carbonation of industrial waste materials were reviewed and analyzed. Industrial waste materials, such as coal fly ash and steel slag have significant capture capacities and coal fly ash consumes significantly lesser energy and costs to capture one tonne of CO2. In addition, calcium extraction from Lakvijaya Coal Fired Power Plant fly ash was experimentally investigated to identify the potential for indirect carbonation, to sequestrate CO2 from coal flue gas. A maximum calcium extraction efficiency of 9.65% was obtained for coal fly ash obtained from Lakvijaya Coal Fired Power Plant.
item: Thesis-Full-text
Investigation of multicomponent heavy metals adsorption capability using raw coir dust and processed coir pith
(2020) Amarasinghe AMPC; Rathnayake HHMP
Water is the most vital natural resource that sustains all living organisms on the earth and access to safe and clean water has become a crisis due to intense water pollution by anthropogenic activities, over-pumping of groundwater for irrigation purposes, limited water availability due to climate changes, regional conflicts over common water resources, etc. Wastewaters that contain various heavy metals, such as arsenic, chromium, manganese, nickel, lead, cadmium, zinc, and copper are being discharged into natural water bodies annually by many industries. Industrial processes that generate wastewater with significantly high levels of heavy metals use various techniques, such as chemical coagulation, chemical precipitation, membrane separation, extraction, electrodeposition, ion-exchange, and electrochemical techniques in order to remove the heavy metal contents. Nevertheless, most of these techniques use expensive chemicals and require considerable time, and some of them are proven to be less effective and less efficient, especially in removing trace amounts of metals. Besides above methods, adsorption technique is one of the most widely used technique to remove heavy metals from water and studies have revealed that it is much effective in removing heavy metals with high solute loading and even at minute concentrations. In the past decade, significant number of studies have been conducted worldwide on the removal of heavy metals from aqueous solutions by non-living and biologically inactive biomass. This approach of wastewater treatment is known as biosorption, and the non-living biomass used there is defined as bio sorbent. Use of bio sorbents to remove heavy metals from wastewater is a novel and developing technology in the water treatment field. Coir pith is a waste-derived material that can be utilized as a biosorbent for heavy metals removal from wastewater. In this study, directly obtained raw coir dust from coconut husks and processed coir pith were tested for their removal efficiencies of 8 heavy metals, i.e., As, Cd, Cu, Cr, Mn, Ni, Pb, and Zn. Standard heavy metal solutions were prepared for each metal and heavy metal content of standard solutions, coir pith, and coir dust were first measured using the Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) method. A multicomponent batch adsorption experimental procedure was conducted to determine the removal efficiencies of each metal by both coir dust and coir pith. In experimental procedures, respectively, 1g, 2g, 3g, 4g, and 5g of coir pith and coir dust were added to equal volumes of each metal solution and allow adsorption for 2 hours. Then filtered samples were tested for the heavy metal concentrations using iii the ICP-OES method. Multicomponent heavy metal removal efficiencies of coir pith were tested by varying the adsorption temperatures and the contact time between the heavy metal solution and the coir pith sample. Analytical results show that both raw coir dust and coir pith act as suitable bio sorbents for removal of As, Cd, Cr, Ni, and Pb, and the optimum solid/liquid ratio is 0.1 g/ml at room temperature for 2 hours if contact time for all these five heavy metals. According to the results comparison between the of raw coir dust and processed coir pith, raw coir dust shows higher heavy metals removal capacities Coir pith is the most suitable biosorbent for Cu removal while coir dust is most suitable biosorbent for Mn removal. For raw coir dust metals and bio sorbents 0.08g/ml at room temperature for 2 hours contact period is the optimum solid/liquid ratio. For processed coir pith metals and bio sorbents 0.1g/ml at room temperature for 2 hours contact period is the optimum solid/liquid ratio Anyway both coir pith and coir dust are not suitable for Zn removal from aqueous solutions. For all metals except Zn, contact period of 30 minutes and temperature of 30 °C are the optimum operating conditions. In this experimental we have used multi component heavy metal sample as a result of it both materials adsorption and desorption are happening in the same sample. When we consider heavy metal adsorption with the temperature from 30-70 °C heavy metals adsorption capacity has decreased the reason for this with the increasing of temperature kinetic energy of the metal has increased then desorption is happened inside the sample. As a result of it with increasing of temperature heavy metals adsorption capacity will decrease. When we consider contact time of the heavy metals sample with the absorbent, For Cr, Cu and Pb show similar results. From 30 min to 2 hr material adsorption efficiency has decreased but 2 hr to 4 hr adsorption efficiency has increased the reason is for this, from 30 min to 2 hr desorption appeared in the sample but with the increasing of the contact time from 2 hr to 4 hr again heavy metals adsorption is happened in the sample. But all other heavy metals are showing decreasing trend of heavy metals adsorption capacity with the increasing of contact time.
item: Thesis-Abstract
Investigation of stability of plug flow anaerobic digester using mathematical modeling
(2015-06-26) Karunarathne, HDSS; Rathnasiri, PG; Bakke, R
Anaerobic treatment has gained wide acceptance as a sustainable technology for treatment of solid wastes and waste water. But in the local context this technology is not rapidly advancing due to process failures and poor technology management. Most of the failures are reported in the anaerobic solid waste treatment than waste water treatment. Recently, novel plug flow reactor system has been installed in few local institutions to treat semi solid wastes with improved efficiency. However lack of understanding of operational parameters and functional units of this reactor system has led to suboptimal operation and thereby low gas production and methane yield. Objective of this study is to develop dynamic mathematical model for plug flow reactor system and propose new strategies to enhance the methane yield and stability of the process. The anaerobic digestion model No. 1 (ADM 1) developed by the international water association (IWA) task group for mathematical modeling of anaerobic digestion process is the most sophisticated model established for full- scale industrial applications. In this work ADM1 was implemented in the simulation software package called AQUASIM 2.1f and advective diffusive reactor compartment was initially used to model the plug flow reactor. To be able to model the actual plug flow reactor system as installed two scenarios are introduced i.e. advective diffusive reactor compartment followed by two continuous stirred tank reactors for collection of slurry and gas. The simulation was done for the different hydraulic retention times and feed flow rates for the substrate of food waste. As second scenario, series of CSTR reactors was used to model plug flow reactor and simulated as before. Simulation results on advective-diffusive reactor model reveal that accumulation of gasses in the slurry cause an inhibition in methane production. In series of CSTR model, when the food waste alone was used at low hydraulic retention times, pH decreases drastically and cause to process inhibition in the first reactor. This inhibition radiates towards the other connected CSTR reactors and after a certain periods of time total methane production terminates.
item: Thesis-Full-text
Investigation of temperature profiles of traditional puta and preparation of chalcopyrite ash for ayurvedic treatment using muffle furnace
Pathiraja, PMYS; Gunawardena, SHP; Herapathdeniya, SKMK
Bhasmas (ashes) are complex compound forms of metals, minerals or gemstones obtained after a series of ayurvedic pharmaceutical preparation processes; purification (shodhana), trituration (bhavana) and incineration (marana) in combination with various herbal extracts and other substances. These three processes play an important role in preparation of ashes. Puta is the specific quantum of heat required to get the desired quality ashes in the process of incineration (marana) and naturally available fuels like cow dung cakes are used to produce heat in the conventional puta. The amount of heat required to produce a specific ash is substance specific and described in terms of fuel burnt. The objectives of this research are to establish temperature profiles for Maha Puta, Gaja Puta and Varaha Puta and to verify temperature profile of Varaha puta using a muffle furnace. Temperature profiles were established using dried cow dung cakes with an average calorific value of 15.44 MJ/kg as the fuel and the maximum temperatures achieved for Maha Puta, Gaja Puta and Varaha Puta were 1380 0C, 1060 0C and 850 0C respectively. Then temperature profile of traditional Varaha Puta was matched with a muffle furnace and Chalcopyrite ash (Swarna Makshika bhasma) was prepared using both traditional method and electric muffle furnace. The ashes produced using both methods showed similar properties and hence the temperature profile obtained for traditional Varaha Puta using the muffle furnace was verified.