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Articles by Ali Elkamel
Total Records ( 7 ) for Ali Elkamel
  Habib H. Al-Ali , Yousef Saif , Ali Elkamel and Ali Lohi
  In this study, electricity production from a network of coal power plants and under environmental constraints is considered. Several pollutants are incorporated into the decision planning process including nitrogen oxides (NOx), sulfur oxides (SOx) and mercury (Hg). A Nonconvex Mixed Integer Nonlinear Programming (MINLP) model was first developed to assist in the evaluation process. An exact linearization of the nonconvex terms was then derived to reformulate the MINLP model into a mixed integer linear program (MILP). Several scenarios of electricity production planning and emission reduction targets are analyzed on a representative case study.
  Habib H. Al-Ali , Yousef Saif , Ali Elkamel and Ali Lohi
  Problem statement: Electricity can be generated from different type of technologies such as fossil and non-fossil power plants. Among these technologies, coal-fired power plants have been a major route for electricity generation. Recently, environmental constraints were imposed over the coal power plant operations in order to reduce their emissions. Besides, renewable energy power plants such as hydroelectric, wind, solar and geothermal have emerged with a potential of low impact on the environment. Approach: In this study, coal-fired power plants with a mix of low emission power plants were analyzed from the viewpoint of coal power plant emission reductions while supplying electricity demand. Electricity capacity expansion was also included within the problem to insure sufficient electricity supply in circumstances of emission reduction constraints. Results: Pollutants such as Nitrogen Oxides (NOx), Sulfur Oxides (SOx) and mercury (Hg) were assumed to be the target compounds. A discrete mathematical programming model was formulated to give an assessment about the coal-fired power plant operations in an electricity generation network. Different scenarios of increased electricity demand and emission reduction targets were applied on Ontario Power Generation (OPG) network to give an illustration of the proposed model. Conclusion: The case study results show the significant impact of combining renewable energy or zero emission technologies on the optimal operation of a network that combines coal-fired power plants.
  Mohammed Ba-Shammakh , Hernane Caruso , Ali Elkamel , Eric Croiset and Peter L. Douglas
  The cement industry is responsible for approximately 5% of global anthropogenic carbon dioxide emissions emitting nearly 900 kg of CO2 for every 1000 kg of cement produced. Effective control strategies to mitigate these emissions are discussed and a mathematical programming model able to suggest the best cost effective strategy is outlined. Control costs consisting of operating and investment costs along with the efficiency of control options are taken into account in the model. A representative case study from the cement industry was considered in order to illustrate the use of the model in giving optimal control strategies. Efficiency improvement measures were found to be effective options for reduction targets up to 10 %. The model suggested that fuel switching and carbon capture must be considered at reduction targets higher than 10%. The cost of cement production was shown to increase dramatically with an increase in reduction target.
  Ibrahim H. Mustafa , G. Ibrahim , Ali Elkamel and A.H. Elahwany
  Problem Statement: The activated sludge system needs to improve the operational performance and to achieve more effective control. To realize this, a better quantitative understanding of the biofloc characteristics is required. The objectives of this study were to: (i) Study the biofloc characteristics from kinetics-mass transfer interaction point of view by quantification of the weight of the aerobic portion of the activated sludge floc to the total floc weight. (ii) Study the effect of bulk concentrations of oxygen and nitrates, power input and substrates diffusivity on the portion aerobic portion of the floc. Approach: An appropriate mathematical model based on heterogeneous modeling is developed for activated sludge flocs. The model was taking into account three growth processes: Carbon oxidation, nitrification and de-nitrification in terms of four components: substrate, nitrate, ammonia, and oxygen. The model accounts for the internal and external mass transfer limitations and relates the external mass transfer resistance with power input. The floc model equations were two- point boundary value differential equations. Therefore a central finite difference method is employed. Results: The percentage aerobic portion increased with increasing with oxygen bulk concentrations and power input and decreases when the bulk concentration of ammonia and substrate increases. Both will compete to consume the internal oxygen by autotrophic and heterotrophic bacteria through aerobic growth processes. The biofloc activity through the profiles was either totally active or partially active. The totally active biofloc is either totally aerobic or aerobic and anoxic together. Conclusions: The heterogeneous floc model was able to describe the biofloc characteristics and reflects the real phenomena existing in the activated sludge processes.
  Ibrahim H. Mustafa , G. Ibrahim , Ali Elkamel and A.H. Elahwany
  Problem Statement: The activated sludge system is a complex dynamic process and must account for a large number of reactions between large numbers of components. There is necessity for simulation models which describe the dynamic behavior of the activated sludge process. The application of the models in most treatment plants is limited due to lack of appropriate data acquisition and parameters identification studies. To realize this, an improvement of the operating strategies of Waste-Water Treatment Plants (WWTP) is required. The objectives of this study were to: (i) To build a process model considering mass transfer limitations and simulate an existing plant (Helwan WWTP) and validate the results using data from another existing plant with (Zenine WWTP). (ii) To adjust the model kinetic parameters of the biochemical reactions under the effect of mass transfer conditions to be prepared for simulation purposes. (iii) Study the effect of the operating conditions on the removal efficiency of both substrate and ammonia. Approach: A process model of the process was built considering mass transfer limitations and the three growth processes: Carbon oxidation, nitrification and denitrification. Helwan WWTP was used in order to extract the suitable stoichiometric and kinetic parameters to be used for the simulation. Helwan WWTP was used through the simulation results of the substrate (BOD) and ammonia. Egyptian Zenine WWTP was used for the testing and validation of the process model through predicting the response of substrate. Results: The average error of the removal efficiency in Helwan WWTP reached 3.3% for the substrate and 12.5% for the ammonia while the average error of the removal efficiency in Zenine WWTP of substrate reached 4.6%. The effects of recycle ratio, flow rate and influent substrate concentrations on the removal efficiency of the aeration tank were studied. It was found that the removal efficiency of substrate and ammonia was increased by increasing the recycle ratio, influent substrate concentrations and also increased by decreasing influent flow rates. It was found also that the sludge age increased by increasing the recycle ratio and decreased by decreasing the influent flow rates. Conclusion: The heterogeneous process model was able to describe the characteristics and reflects the real phenomena existing in activated sludge processes.
  Reyyan KOC , Erdogan ALPER , Eric CROISET and Ali ELKAMEL
  Methane cracking has the potential to produce high purity, carbon monoxide-free hydrogen suitable for application in PEM fuel cells. The 2 products of the reaction are molecular hydrogen and solid carbon. The carbon appears in the form of carbon filaments whose growth is hindered by carbon encapsulation leading to total deactivation of the catalyst. Several attempts have been made to regenerate the catalyst, mainly by gasifying the carbon filament in air or steam. Our work on 5-wt% Ni/g-Al2O3 indicated that after complete gasification of the carbon the catalyst lost nearly all its activity toward methane cracking. However, if the gasification proceeds to only a certain extent, it is possible to recover significant activity of the catalyst. This technique, also known as partial regeneration, is a promising strategy to overcome the challenge of catalyst deactivation in catalytic decomposition of methane. Optimization of the partial regeneration method is presented here, in particular the extent to which the gasification should take place. Activity of the catalyst and the extent of gasification have been monitored through thermogravimetric analysis. Regeneration of catalyst is still a much-questioned field to maintain not only a continuous and also an economical process. That is why this experimental study focused on regeneration of nickel supported on alumina. As an overview of this study: The effects of percentage of nickel, application of reduction, reaction temperature, and the amount of gasified carbon on weight gain are stated as the rate of carbon formation per gram of nickel present in catalyst.
  Reyyan KOC , Erdogan ALPER , Eric CROISET and Ali ELKAMEL
  High purity, carbon monoxide-free hydrogen and filamentous carbon can be produced by thermo-catalytic cracking of methane. Carbon filaments continue to grow until the catalyst deactivates because of carbon encapsulation. Regeneration of catalyst is important to maintain a continuous process. Our work on optimization of the partial regeneration method showed that activity of the catalyst can be sustained for longer times by gasifying not all but some extent of the deposited carbon. In the previous work, a kinetic model was developed to be able to understand the reaction mechanism of deactivation of fresh catalyst at the molecular level. The objective of this study was to develop a well-fitted kinetic model for deactivation of regenerated catalyst. A kinetic model that consists of surface reactions, filament formation, and deactivation was developed for the regenerated catalyst. It is assumed that reaction parameters at the molecular level do not change when the burn off degree is at a moderate extent but these parameters changed drastically when burn off degree is vastly increased or decreased. Rate constant for the encapsulation reaction is adjusted for the simulation results to be representative of the experimental results (typically specific weight of carbon (g C/g Ni) vs. time on stream). The system of differential algebraic equations consists of the steady-state equations for all surface intermediates, an algebraic equation of dissolution/segregation, diffusion equation, and the site balance equation. The system has been solved without assuming any rate-determining step or most abundant surface intermediates. Parameter estimation procedures were repeated for the deactivation cycles of regenerated 5 wt% Ni/γ-Al2O3 catalyst. The basic idea that underlies the model is that every carbon atom will diffuse through the nickel particle and participate in the formation of carbon filaments until the catalyst deactivates. Specific weight of carbon is calculated using the rate of carbon diffusion.
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