Oxy‐fuel combustion technology: current status,applications, and trends

The increased level of emissions of carbon dioxide into the atmosphere due to burning of fossil fuels represents one of the main barriers toward the reduction of greenhouse gases and the control of global warming. In the last decades, the use of renewable and clean sources of energies such as solar and wind energies has been increased extensively. However, due to the tremendously increasing world energy demand, fossil fuels would continue in use for decades which necessitates the integration of carbon capture technologies (CCTs) in power plants. These technologies include oxycombustion, pre‐combustion, and post‐combustion carbon capture. Oxycombustion technology is one of the most promising carbon capture technologies as it can be applied with slight modifications to existing power plants or to new power plants. In this technology, fuel is burned using an oxidizer mixture of pure oxygen plus recycled exhaust gases (consists mainly of CO₂). The oxycombustion process results in highly CO₂‐concentrated exhaust gases, which facilitates the capture process of CO₂ after H₂O condensation. The captured CO₂ can be used for industrial applications or can be sequestrated. The current work reviews the current status of oxycombustion technology and its applications in existing conventional combustion systems (including gas turbines and boilers) and novel oxygen transport reactors (OTRs). The review starts with an introduction to the available CCTs with emphasis on their different applications and limitations of use, followed by a review on oxycombustion applications in different combustion systems utilizing gaseous, liquid, and coal fuels. The current status and technology readiness level of oxycombustion technology is discussed. The novel application of oxycombustion technology in OTRs is analyzed in some details. The analyses of OTRs include oxygen permeation technique, fabrication of oxygen transport membranes (OTMs), calculation of oxygen permeation flux, and coupling between oxygen separation and oxycombustion of fuel within the same unit called OTR. The oxycombustion process inside OTR is analyzed considering coal and gaseous fuels. The future trends of oxycombustion technology are itemized and discussed in details in the present study including: (i) ITMs for syngas production; (ii) combustion utilizing liquid fuels in OTRs; (iii) oxy‐combustion integrated power plants and (iv) third generation technologies for CO₂ capture. Techno‐economic analysis of oxycombustion integrated systems is also discussed trying to assess the future prospects of this technology. Copyright © 2017 John Wiley & Sons, Ltd.     

C/SiC Gradient Oxidation Protective Coating on Graphite by Modified Reactive Melt Infiltration Method: Effects of Processing Parameters on Transition Interface Thickness and High-Temperature Anti-oxidation Behavior

Metallurgical and Materials Transactions A - In this research, it was found that the C/SiC transition interface thickness increases without a significant decrease in toughness by modifying the...     

Numerical simulation of froth formation in aerated slurry coupled with population balance modelling

A computational fluid dynamic (CFD) model has been developed to incorporate pulp and froth zones into one model. In the present research, froth was considered as a separate phase comprised of a mixture of gas, liquid and solids. Considering the froth phase as a separate phase, allowed the incorporation of pulp and froth zones into one model by tracking the formation and destruction of the froth phase due to mass exchange between the pulp and froth. Bubble break-up and coalescence were taken into account in the pulp zone, by employing user functions, written using FORTRAN. The effect of bubble coalescence process due to ?lm rupture was considered in the froth phase. The variation in the concentration of attached particles due to attachment and detachment processes were also taken into account. The CFD model predicted the height of froth layer, the concentration of different bubble sizes in both pulp and froth zones, and finally the multiphase ?ow phenomena in the slurry column. Froth height was found to increase with the increase of gas flow rate while increasing solid concentration decreased froth height.     

Cascaded waste‐heat recovery as a green technology for energy sustainability in power generation

In this work, the Cascaded waste‐heat recovery (WHR) is analyzed from the thermodynamic point of view. Typically, WHR is most effective with small gas turbines and old machines which have a relatively higher design mass flow per kW and higher exhaust temperatures than new designs. The working fluid used in the WHR technology is propane, which vaporizes and condenses at low temperatures. The temperature of the heat source, the outlet pressure of the two expanders, and the mass flow rate of the working fluid are assumed as working variables of the technology. The effect of these variables on the thermal efficiency and power output is evaluated. The obtained results are analyzed and discussed. The results of the calculation are also compared with similar published studies. The overall efficiency considering the gas turbine upstream ranges from about 35% up to 39%. The highest efficiency and power output of the WHR alone at 900 K heat source temperature, 800 kPa condenser pressure, and 100 kg/s mass‐flow rate are 30% and 18 MW, respectively, for two‐expander WHR, and 18% and 9 MW, respectively, for single expander WHR. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of plasma parameters on increasing the purity of nitrogen atom encapsulated fullerene in an RF plasma

Relatively high purity of nitrogen atom encapsulated fullerene (N@C₆₀) has been synthesized by an electron beam superimposed radio frequency (RF) discharge plasma method. Nitrogen species are characterized by an optical emission spectroscopy (OES); and a relationship between optical emission spectra and the purity of N@C₆₀ has been examined. It is observed that the increased amount of nitrogen molecule ions impinging on the sublimated fullerenes enhance the synthesis of N@C₆₀. Here, it is cleared that the efficient synthesis of N@C₆₀ is possible by controlling the parameters of electron beam superimposed RF plasma. As a consequence, comparatively high purity of about 0.08% of N@C₆₀ has been obtained.     

Application nonparametric criteria in the analysis of oil fields development

Waterflood or pressure maintenance project is considered one of several methods of enhanced oil recovery, which is widely being used in oil fields. Water injection efficiency analysis is very important for operation future plan and finds out if any opportunity is available to improve project performance. The conventional methods beside nonparametric criteria have been applied in this research in order to evaluate water injection operation. Gini coefficient analysis has been used to illustrate the water injection impact in terms of oil and water production trends over the time of injection operation.     

Analysis of steelmaking kinetics from IMPHOS pilot plant data

It is widely accepted that understanding the kinetics of steelmaking is a complex task, and reliable and validated kinetics models are required for developing successful steelmaking process models. Therefore, as an initial attempt, this paper analyses the applicability of first order kinetics to explain the steelmaking reaction kinetics using the published data in the IMproving Phosphorus Refining research report. The process data for 20 heats in a 6?tonne pilot plant were analysed for the removal of carbon, silicon, manganese and phosphorus using first order kinetics with static and dynamic equilibrium conditions. It was observed that the removal behaviour of silicon closely followed a first order kinetics relationship, while that of carbon only approximately followed a first order kinetics relationship. The removal of manganese did not show a good degree of fit with first order kinetics using static equilibrium condition, but a clear improvement was observed when calculated using dynamic equilibrium condition. In contrast, the kinetics of phosphorus oxidation did not follow any first order relationship.     

A Novel Algebraic Technique for the Construction of Strong Substitution Box

Magnetic induction applications mostly rely on resonance for inducing maximum magnetic fields to system loads and hence for each resonant frequency dedicated circuits are required. Unfortunately, the frequency responses of such inductive systems manifest several peaks (frequency splitting) when their coupling coefficients are equal to or larger than critical coupling. Such frequency responses with several peaks are detrimental when the objective is to transfer maximum energy. Frequency splitting between inductive coils have been seen to date as detrimental to wireless power transfer and inductive communication systems. In this paper it is demonstrated that frequency splitting is a welcome phenomenon with advantage in the design of inductive filter banks and multi-frequency inductive systems. The centre frequencies of the filter banks result from split bands of inductive systems. This phenomenon is applied in conjunction with an innovative recursive algorithm to design inductive filter banks. The filters straddle both sides of the resonant frequency position and can be resolved individually.