Oxygen Injection Research Articles

Investigating the Influence of Heavy Oil Recovery by In Situ Combustion during Air Injection as EOR Technique

Heavy oil is one of the most useful energy resource special in the times of crises when other resources are not present in profusion. However, Occurrence of heavy oil in unconsolidated sands is one the most challenging factor to recover the heavy oil. Therefore, in this study the main focus is derived towards the extraction of heavy oil with optimistic procedure called air injection. For the research, a reactor assembly was developed for the experimental work on air (21% oxygen) injection into heavy oil (12.59 °API) reservoir. Total 13 kinetics runs were conducted on unconsolidated cores by varying the parameters involved system pressure, flow rate (air flux), oxidation temperature (heat input), and rock formation (sand matrix). It was found that the process is very dependent on operating conditions employed, as oxygen consumption rate was very dependent on air flux. Increase of air flux from 15.19 to 22.78 m 3 /m 2 -hr resulted in slightly increasing rates of oxygen consumption over the temperature range under investigation. The temperature difference also shows great effect on the high temperature oxidation. The pressure and porous media also has great impact on the combustion behavior. The influence of individual parameter was obtained from analysis of the inlet oxygen and composition of flue gases from the combustion cell. Indeed, the oxygen conversion was too less to evaluate the kinetic data at temperature less than 250 °C while for oxidation reactions, the oxygen statistics analyzed from temperature above than 350 °C. The experimental results reveal that the average maximum peak temperature was 440 °C, and the oxidation reaction process at high temperature was very effective in terms of produced carbon oxides with an average percentage of 9.5% CO 2 , 5.5% CO in flue gases. Oil displacement was observed from the analysis of flue gases, consequently; incremental oil recovery was achieved between 56%-80% under high temperature oxidation (HTO) conditions.

Investigating the Influence of Heavy Oil Recovery by In Situ Combustion during Air Injection as EOR Technique

Heavy oil is one of the most useful energy resource special in the times of crises when other resources are not present in profusion. However, Occurrence of heavy oil in unconsolidated sands is one the most challenging factor to recover the heavy oil. Therefore, in this study the main focus is derived towards the extraction of heavy oil with optimistic procedure called air injection. For the research, a reactor assembly was developed for the experimental work on air (21% oxygen) injection into heavy oil (12.59 °API) reservoir. Total 13 kinetics runs were conducted on unconsolidated cores by varying the parameters involved system pressure, flow rate (air flux), oxidation temperature (heat input), and rock formation (sand matrix). It was found that the process is very dependent on operating conditions employed, as oxygen consumption rate was very dependent on air flux. Increase of air flux from 15.19 to 22.78 m 3 /m 2 -hr resulted in slightly increasing rates of oxygen consumption over the temperature range under investigation. The temperature difference also shows great effect on the high temperature oxidation. The pressure and porous media also has great impact on the combustion behavior. The influence of individual parameter was obtained from analysis of the inlet oxygen and composition of flue gases from the combustion cell. Indeed, the oxygen conversion was too less to evaluate the kinetic data at temperature less than 250 °C while for oxidation reactions, the oxygen statistics analyzed from temperature above than 350 °C. The experimental results reveal that the average maximum peak temperature was 440 °C, and the oxidation reaction process at high temperature was very effective in terms of produced carbon oxides with an average percentage of 9.5% CO 2 , 5.5% CO in flue gases. Oil displacement was observed from the analysis of flue gases, consequently; incremental oil recovery was achieved between 56%-80% under high temperature oxidation (HTO) conditions.

Impacts on water quality by in situ induced ozone‑oxygen oxidation in a polluted urban reservoir

The results of the successful implementation of a treatment based on the injection of ozone (O3) and oxygen (O2) into a contaminated body of water are reported for the first time. Three decontaminating units (SCAVENGER™), which have the capacity to inject up to 120 g O3/h and 250 Kg O2/h in the form of microbubbles (90 ± 10 μm in diameter), were placed in the contaminated Valsequillo reservoir, Central Mexico. In order to evaluate the efficacy of the treatment, 20 physicochemical parameters, 18 organic compounds, 66 inorganic compounds and 11 biological indicators were measured before, during and after the treatment; all of them in several representative sites of the east side of the Valsequillo reservoir. After 5 months of operating the SCAVENGER™ units in the eastern part of the reservoir, the concentration of Dissolved Oxygen (DO) increased 68%. Likewise, the chemical reducing conditions of the reservoir reflected by the low oxidation-reduction potential (ORP; −237 ± 75 mV) became quasi-oxidant (10 ± 58 mV). The treatment was efficient in water disinfection, presenting an 80% reduction in Fecal Coliforms (FC). Some heavy metals also showed a decrease in their concentration, being as follows: Al (65%), Cr (35%), Pb (46%), Zn (60%), Mn (20%), Mo (40%), Fe (32%), As (58%) and Co (26%). Due to the selective reactivity of ozone towards aliphatic and aromatic unsaturated compounds, several organic compounds reduced in their concentration by up to two orders of magnitude. Based on the above, it is evident that the treatment with ozone and oxygen was effective in substantially improving the quality of water in the east side of the Valsequillo reservoir.

Influence of thermal treatment on the properties of carbon fiber reinforced plastics under various conditions

Thermal treatment has been regarded as an effective method for recycling carbon fiber reinforced plastics (CFRP). In this paper, the influences of operating temperature, oxygen concentration and superheated steam on the thermal behaviors of virgin carbon fibers (CF) and CFRP were investigated. The properties of recycled CF (rCF) were determined by yarns tensile test, SEM and Raman analyses. The TG results suggested that the oxidation of CFRP was comprised mainly of the decomposition and the oxidation of epoxy matrix, the oxidation of pyrolytic residue, and the oxidation of CF. For the virgin CF, temperature showed a negligible effect on the tensile strength of CF in N2 atmosphere, whereas the injection of oxygen or superheated steam greatly reduced their tensile strength with the increasing temperatures. Higher temperatures led to the surface defects of treated CF due to the oxidative effect. An amount of pyrolytic residue was observed on the rCF during the CFRP pyrolysis. Increasing the O2 concentration removed the pyrolytic residue from the rCF at 500 °C, preserving 94% of the original tensile strength. Higher temperatures showed negative effects on the properties of rCF, where the surface defects were clearly observed, and were exacerbated with higher O2 concentrations. Superheated steam could remove the pyrolytic residue and preserved the properties of rCF.

Different micro-aeration rates facilitate production of different end-products from source-diverted blackwater

The effects of micro-aeration on the performance of anaerobic sequencing batch reactors (ASBR) for blackwater treatment were investigated in this study. Different micro-aeration rates, 0, 5, 10, 50, and 150 mg O2/L-reactor/cycle, and their effect on the hydrolysis, acidogenesis, and methanogenesis of blackwater were evaluated and compared at ambient temperature. Source-diverted blackwater (toilet water) contains high organic contents which can be recovered as biogas. Previous studies have found that anaerobic digestion of blackwater without micro-aeration can only recover upwards of less than 40% of chemical oxygen demand (COD) to methane at room temperature due to the low hydrolysis rate of biomass content in blackwater. This study achieved increases in blackwater hydrolysis (from 34.7% to 48.7%) and methane production (from 39.6% to 50.7%) with controlled micro-aeration (5 mg O2/L-reactor/cycle). The microbial analysis results showed that hydrolytic/fermentative bacteria and acetoclastic methanogens (e.g. Methanosaeta) were in higher abundances in low-dose micro-aeration reactors (5 and 10 mg O2/L-reactor/cycle), which facilitated syntrophic interactions between microorganisms. The relative abundance of oxygen-tolerant methanogen such as Methanosarcina greatly increased (from 1.5% to 11.4%) after oxygen injection. High oxygen dosages (50 and 150 mg O2/L-reactor/cycle) led to reduced methane production and higher accumulation of volatile fatty acids, largely due to the oxygen inhibition on methanogens and degradation of organic matters by aerobic growth and respiration, as indicated by the predicted metagenome functions. By combining reactor performance results and microbial community analyses, this study demonstrated that low-dose micro-aeration improves blackwater biomethane recovery by enhancing hydrolysis efficiency and promoting the development of a functional microbial population, while medium to high-dose micro-aeration reduced the activities of certain anaerobes. It was also observed that medium-dose micro-aeration maximizes VFA accumulation, which may be used in two-stage anaerobic digesters.

Thermodynamics and Structural Properties of Ti3SiC2 in Liquid Lead Coolant

It has been investigated by molecular dynamics method the effect of oxygen injection for Ti3SiC2 corrosion inhibition when this material immersed into high temperature liquid lead coolant. The diffusion coefficient of Ti3SiC2 was determined from mean-square-displacement simulation data. The structures of Ti3SiC2 during corrosion inhibition using oxygen agent were observed by Ovito vizualisation code. The simulations have been done using the Moldy molecular dynamics code. Initial material structure as input of simulation generated by Atomsk, Packmol and VESTA codes based on “file 1520829.cif” format file that taken from the crystallography open database (CoD) website. It is from our work we can show that injecting oxygen with concentration about 0.15 – 0.19 wt%, it seems can stabilize the structure of Ti2SiC3 maximally.

Tailoring of electrical properties of Cu2O thin films fabricated by oxygen injection after argon plasma reduction of CuO films

Cu2O thin films with tailored electrical properties were produced by 25 s plasma reduction of CuO films and immediate oxidation under oxygen flows of 0, 3, 6, 9, 12, 15, and 18 sccm. CuO target films were easily prepared by the dip-coating method and annealing at 400 °C. CuO was transformed to Cu2O by employing an argon plasma treatment devised in our laboratory. Cu2O was produced as the only crystalline phase detected, and the films exhibited smooth surfaces with roughness around 5 nm. All films presented high reflectance in the fundamental absorption region (30%) and high transmittance in the transparency region of Cu2O (65%). The good optical behavior permitted the accurate calculation of optical constants by fitting reflectance and transmittance to an optical model designed with the help of Film Wizard™ software. Variations with oxygen injection were detected for the components of the dielectric function, index of refraction, and absorption coefficient. More importantly, the electrical properties of Cu2O showed a clear dependence on O2 injection. Even though resistivity was on average 80 Ω∙cm, hole mobility varied in the span of 0.75–3.2 cm2/V s, and hole density in the range of 1016–1017/cm3. Upon storage in open-air conditions, the mobility of Cu2O films was increased to 3.8 cm2/V s. The Cu2O films produced show similar quality to those obtained by a sputtering deposition method. However, simpler equipment was employed. The plasma method studied is promising for fast mass production of Cu2O thin films.

Forecast model for dephosphorization process of ferromanganese steels using artificial neural networks

One of the main problems affecting the quality of steel products is the existence of contaminants in alloy steel, being phosphorus (P) a major contamination element interfering with the steelmaking process. The increased P concentration levels can severely affect physical integrity of steel bonds, thus threatening the quality of the final product. The dephosphorization process of Ferromanganese consists by carbothermic reaction that involves the control of the manganese volatilization and reduction of manganese oxide in injection of oxygen. Therefore, we propose to forecast model for dephosphorization process of Ferromanganese steels in a steelmaker industry, that allows estimating the phosphorus concentration levels at the final refining process. We chose the artificial neural network models because it is computational models inspired in the human nervous system and an architecture of neural network with the Levenberg-Marquadt algorithm and Kolmogorov theorem for improving the estimation technique. The developed model presented excellent performance with a percentage error of 0.09%. Based on this created estimation model it is possible to estimate the impact of certain P concentration levels in FeMnMC beforehand, with a considerable amount of reliability. Keywords: Ferromanganese alloys, dephosphorization process, Neural networks, Kolmogorov theorem. 1

Modeling of slag foaming height of electric arc furnace using stepwise regression analysis

Slag foaming directly affects the productivity and quality of steel during the electric arc furnace (EAF) process. Therefore, the slag foaming height needs to be monitored in real-time. However, direct measurement of the slag foaming height is difficult to achieve because the inside of the EAF consists of harsh environments, i.e., high temperature and the presence of gas and dust. A stepwise regression model of the slag foaming height was created using sensor data from the EAF. A total of 272 operational data sets from the EAF process were used to develop and validate the regression model. This data came from 140ton DC-EAF of Dongkuk Steel in Pohang, Korea. We randomly selected 80% of the data for developing the regression model; the remaining 20% of data were used for model validation. The model was validated using the validation benchmark coefficient of determination (R2) and correlation coefficients. As a result, the important variables of slag foaming were statistically selected a priori. Using the regression model, the slag foaming height can be predicted without additional sensors. Based on the developed model, the effects of oxygen injection and carbon injection on the slag foaming height of EAF were predicted and are discussed herein.

Numerical simulation of UCG process with the aim of increasing calorific value of syngas

The determination of operational parameters in the underground coal gasification (UCG) process should be considered in two aspects: first, the total coal in each UCG panel must be gasified and second, the calorific value of the produced gas should be acceptable. The main aim of this study is to present a model that meets these aspects and increasing the calorific value of syngas during this process. In order to achieve those aims, eight different increasing scenarios were devised for total gasification of coal per panel. These scenarios included: increasing oxygen injection rate (scenario 1), the amount of steam injection (scenario 2), operation time (scenario 3), cavity pressure (scenario 4), increase operation time and cavity pressure simultaneously (scenario 5), increase steam injection speed and oxygen injection rate simultaneously (scenario 6), increase in cavity pressure, operating time, steam injection rate and oxygen injection rate simultaneously (scenario 7) and also simultaneous increase in the operating time and steam injection rate (scenario 8). The results showed that for producing syngas with a higher calorific value, the following parameters had the most positive effects respectively: operation time, cavity pressure, steam injection rate and oxygen injection rate. Finally, the model validation was performed for the Centralia LBK-1 UCG pilot and the results showed that this model is very close to reality.

The Potential Application of Microorganisms for Sustainable Petroleum Recovery from Heavy Oil Reservoirs

A microbial enhanced oil recovery (MEOR) technique was tested at low-temperature heavy oil reservoirs (Russia). The bioaugmentation approach used is based on the introduction of hydrocarbon-oxidizing bacteria into the oilfield in combination with an injection of oxygen as a H2O2 solution in order to initiate the first stage of hydrocarbon oxidation and of (NH4)2HPO4 as a source of biogenic elements. Before the pilot trials, the microorganisms of petroleum reservoirs were investigated by high-throughput sequencing, as well as by culture-base and radioisotope techniques. Molecular studies revealed the differences in microbial composition of the carbonate and terrigenous oil reservoirs and the communities of injection and formation water. Aerobic bacteria Rhodococcus erythropolis HO-KS22 and Gordonia amicalis 6-1 isolated from oilfields oxidized oil and produced biosurfactants. Fermentative enrichment and pure cultures produced considerable amounts of low fatty acids and alcohols from sacchariferous substrates. In core-flooding tests, 43.0–53.5% of additional heavy oil was displaced by aerobic bacteria, producing biosurfactants, and 13.4–45.5% of oil was displaced by fermentative bacteria, producing low fatty acids, alcohols, and gas. A total of 1250 t additional oil was recovered as a result of the application of an MEOR technique at the Cheremukhovskoe heavy oil reservoir and Vostochno-Anzirskoe reservoir with light conventional oil.

Species traits and decomposability predict water quality changes during litter submergence

Plant litter plays an important role in affecting the water quality of wetland ecosystems. However, it is unknown whether litter decomposability and species traits might predict water quality changes during litter submergence. Here, we conducted a greenhouse experiment to examine the effects of four submerged plant species, together with two water sources (sampled from tourism and protected areas), and oxygen injection treatments on the changes of eight water quality parameters during litter submergence. Our results showed that litter submergence significantly affected water quality changes, and the observed effects changed through time and differed between two water sources, between oxygen injection and the control treatments, and among different litter species. Moreover, water electric conductivity (EC), total dissolved solids (TDS), water total nitrogen (TN), ammonium and nitrite nitrogen increased with increasing initial litter total carbon (TC), TN and total phosphorus (TP), but water dissolved oxygen (DO) decreased with increasing litter TC, TN and TP. Moreover, water EC, TDS and TN increased with the final mass losses after 10-week submergence. These results indicated that species traits (including decomposability) might be good predictors for the water quality changes during litter submergence, and such a trait-based approach might be a promising tool to link plant species diversity via plant functional traits to water quality or other wetland ecosystem services.

Detailed analysis of Toe-to-Heel Air Injection for heavy oil production

The Toe-To-Heel Air Injection (THAI) operation at Kerrobert, Saskatchewan proved that commercial oil rate is possible together with production of partially upgraded heavy oil. Despite physical model experimentation and simulation investigations of THAI, no detailed analysis has been conducted on a THAI field operation to resolve recovery mechanisms and the strengths and limitations of the process. Here, we present, for the first time, a detailed evaluation of the Kerrobert THAI field operation to find causal relationships between injectants and production rates, gas composition, and temperature rise within the reservoir and which downhole reactions are key in the process i.e. low temperature oxidation, high temperature oxidation, thermal cracking/thermolysis, coke gasification and aquathermolysis. The results demonstrate that there is a competition between oxygen injection for heat generation via oxidation reactions versus air injection leading to cooling of the system which limits the peak oil rate. General comparisons are made to a neighboring Steam-Assisted Gravity Drainage (SAGD) operation in the same formation. A comparison of THAI and SAGD in the formation indicates that although THAI yields significantly lower normalized oil rates than SAGD, it is more energy efficient than SAGD.

Spectroscopic Studies of Longitudinal Discharges in a Supersonic Air Flow during the Injection of Propane, Ethylene, and Oxygen into the Discharge Zone

The paper presents the results of studies of longitudinal electric discharges in a supersonic air flow with a Mach number of M = 2 in the range of static pressures (2.94−4.9) × 104 Pa (∼220−367 Torr) and discharge currents of ∼1.5−1.8 A during the injection of propane, ethylene, and hydrogen, along with oxygen, into the discharge zone through the two types of upstream electrodes (anodes). The design of the electric-discharge modules was such that the discharge was carried downstream by the supersonic flow and closed, mainly to the cathode located downstream. Emission spectroscopy was used to obtain data on the composition of the emitting products that arose in the processes of converting a fuel-air mixture in a discharge and their spatial distribution. In particular, data on the distribution of the radiation intensity of CN, C2 molecules, and OH radical, as well as atomic hydrogen and oxygen in a number of sections of the discharge channel, are presented. The used methodology allowed us to determine the change in the transverse dimensions of the discharge channels along the length and the value of the rotational temperature of molecule C2 for discharges with the injection of propane and ethylene into the discharge zone. The relationship between its value and the conditions for the formation of the discharge and the coefficient of excess oxygen injected into the discharge is established.

Vesicourethral Anastomotic Stenosis after Prostate Cancer Treatment

To describe the epidemiology, pathogenesis, and management of vesicourethral anastomotic stenosis after prostate cancer treatment. Injectable scar modulating agents administered at the time of direct visual internal urethrotomy of vesicourethral anastomotic stenoses have been shown to improve endoscopic treatment outcomes. Trials are ongoing to find the optimal agent and delivery system. Novel tissue engineering techniques are in development and hold promise. Vesicourethral anastomotic stenosis after the treatment of prostate cancer is a challenging complication for patients and urologists. Stenoses are prone to recurrence after endourologic treatment. Open repair is technically demanding and carries substantial patient morbidity. The need for adjuvant or salvage radiation therapy after radical prostatectomy worsens outcomes of both endourologic and formal repairs. Postoperative worsening of urinary incontinence is common after vesicourethral anastomotic stenosis repair and can ultimately require placement of an artificial urinary sphincter or male sling. Occasionally urinary diversion, indwelling foley catheter, or clean intermittent catheterization is necessary when reconstructive options have been exhausted. Adjunctive measures to improve endourologic management such as hyperbaric oxygen and transurethral injection of anti-fibrotic agents have been an area of interest in recent years and show promise.

Factors affecting nitrification with nitrite accumulation in treated wastewater by oxygen injection

ABSTRACT This work provides information on nitrification with nitrite accumulation in low strength ammonia (below 50 mg L−1 NH4–N) and low organic matter (below 150 mg L−1 COD) reclaimed wastewater. In the South Tenerife reclaimed wastewater pipeline (62 km long), injection of O2 has been applied to promote a nitrification process in order to improve water quality and to avoid anaerobic conditions. Nitrification occurs, in most cases, with nitrite accumulation. The amount of oxidized nitrogen compounds produced increases with the oxygen dose applied. The nitrification process is usually favoured instead of the organic matter transformation, due to the low organic matter/ammonia nitrogen ratio of water. The influence of organic matter content on nitrification has been analysed, and a good suitability for COD has been found as an indicator for nitrification limitation (for the range of COD and NH4-N concentrations of the system). Nitrification limitation has been observed above 85 mg L−1 COD, and nitrification inhibition above a concentration of 105 mg L−1. In addition, the limitation of nitrite oxidation bacteria activity (nitrite accumulation) by free ammonia and temperature has been assessed, finding that, for the range of free ammonia (0.6–2.1 mg L−1 NH3) and temperature (20.4–27.0°C) in the study, temperature plays a much more relevant role than free ammonia on nitrite accumulation. The lower limiting temperature for nitrite build-up in the system has been 21.0°C. Below this temperature, nitrite accumulation did not exist or was very low.

Degradation of pharmaceutical compounds in water by oxygenated electrochemical oxidation: Parametric optimization, kinetic studies and toxicity assessment.

The pharmaceutical compounds sulfamethoxazole (SMX), propranolol (PRO) and carbamazepine (CBZ) are biorecalcitrant and frequently detected in waters causing negative impacts on human health and aquatic organisms. Electrochemical oxidation appears as an effective option for the removal of recalcitrant compounds and its enhancement is an important issue for the removal of emerging compounds in water. The contribution of this research lies in the comprehensive analysis of the oxygenated electro chemical oxidation of CBZ, SMX and PRO using Nb/BDD mesh anode. The effect of treatment time, current, pH and oxygen injection on the SMX, PRO and CBZ degradation was assessed using Na2SO4 as electrolyte, process optimization was performed, by-products were identified, kinetic and toxicity tests were carried out using different electrolytes. Finally, the process effectiveness was tested using real secondary effluent spiked with the mixture of the pharmaceutical compounds and the acute toxicity was determined. The obtained results indicated that the oxygenated electrochemical oxidation allows effective simultaneous SMX, PRO and CBZ degradation, which showed a significant dependence of treatment time, current and oxygen injection in Na2SO4 electrolyte. At 90 min of electrolysis the parent compounds were detected as well as eight by-products. At 150 min of treatment, further to the already determined by-products and the parent compounds, appeared phenol and p-benzoquinone. Based on the identified compounds, degradation pathways were explained as a result of two main mechanisms: transformation (hydroxylation, deamination, desulfunation) and bond rupture. The kinetic study indicated an increase of the first-order kinetic constant in the oxygenated electrochemical oxidation process using Na2SO4 and NaBr as electrolyte, nevertheless the constant decreased in the presence of NaCl. In the assays with secondary effluent spiked with SMX, PRO and CBZ, the oxygenation did not enhance the performance of the process, however; pharmaceuticals were degraded with a higher removal rates compared with the ones determined in the Na2SO4 synthetic solutions assays; the oxygenation enhanced the TOC and COD removal. The acute toxicity of spiked secondary effluent was reduced from the first few minutes of the electrochemical oxidation process.

BIO_ALGAE 2: improved model of microalgae and bacteria consortia for wastewater treatment.

A new set up of the integral mechanistic BIO_ALGAE model that describes the complex interactions in mixed algal-bacterial systems was developed to overcome some restrictions of the model. BIO_ALGAE 2 includes new sub-models that take into account the variation of microalgae and bacteria performance as a function of culture conditions prevailing in microalgae cultures (pH, temperature, dissolved oxygen) over daily and seasonal cycles and the implementation of on-demand dioxide carbon injection for pH control. Moreover, another aim of this work was to study a correlation between the mass transfer coefficient and the hydrodynamics of reactor. The model was calibrated using real data from a laboratory reactor fed with real wastewater. Moreover, the model was used to simulate daily variations of different components in the pond (dissolved oxygen, pH, and CO2 injection) and to predict microalgae (XALG) and bacteria (XH) proportions and to estimate daily biomass production (Cb). The effect of CO2 injection and the influence of wastewater composition on treatment performance were investigated through practical study cases. XALG decreased by 38%, and XH increased by 35% with respect to the system under pH control while microalgae and bacteria proportions are completely different as a function of influent wastewater composition. Model simulations have indicated that Cb production (~ 100gTSSm-3day-1 for manure and centrate) resulted lower than Cb production obtained using primary influent wastewater (155gTSSm-3day-1).

Improving the Modeling of Slag and Steel Bath Chemistry in an Electric Arc Furnace Process Model

An improvement to the thermochemical module of the electric arc furnace (EAF) process model developed by Meier based on the work of Logar, Dovžan, and Skrjanc is presented. Different models for the calculation of activities in melt and slag are implemented, and separate reaction zones are defined for the interaction of slag and melt, the injection of oxygen, and the injection of carbon. For each zone, equilibrium compositions and reaction rates are calculated. Furthermore, diffusion of species is considered as a rate-limiting factor in reactions between slag and melt, and diffusion rates are calculated from the bulk melt to the reaction zone where reactions with the slag take place. Oxygen and sulfur dissolved in the melt and CaS in the slag are added as new species not previously considered in the EAF model. The treatment of carbon is revised to reduce model complexity and improve accuracy. The improved model is validated using extensive data from an industrial EAF, and results are compared to measured data as well as results obtained with the unmodified model. The different models for the determination of thermodynamic activities and their impacts on the duration of the simulation as well as its results are evaluated.

Flame Interaction Characteristics in Scramjet Combustor Equipped with Strut/Wall Combined Fuel Injectors

ABSTRACT A strut/wall combined fuel injection scheme was experimentally investigated in a flush-wall scramjet combustor fueled with liquid kerosene. A thin strut was adopted as fuel injector and flame holder, and wall injectors were also placed on side wall of the combustor, downstream of the strut. With the injection of pure oxygen through the injectors in the trailing edge of the strut, a stable flame was achieved in the combustor, and the flame interaction characteristics were experimentally investigated. Experiments were conducted at the inlet of Mach number 2.0 with different strut/wall fuel distribution schemes. Flame was divided into two parts, namely the core flame and the wall flame, and interaction mechanism between the two parts was experimentally investigated. Experiment results show that core flame is enhanced with the increasing of fuel equivalence ratio. Core flame propagates to side wall of the combustor to ignite wall fuel, forming a wall flame. Wall flame leads to a thermal chocking at the downstream of strut to enhance core flame. Combustor performance and flame characteristics are influenced by fuel distribution schemes. The location of wall fuel injectors is also optimized to improve combustion efficiency. These results in this paper are valuable for the future optimization of combustion organization in scramjet combustor with multi-stages fuel injection scheme.