Enriched Air Research Articles

Oxygen enrichment of air: Performance guidelines for membranes based on techno-economic assessment

The use of oxygen-enriched air (OEA) is an important strategy for reducing process cost and CO2 emissions in several industrial processes. Membrane-based processes, attributing to their high energy efficiency, are promising alternatives to cryogenic distillation and pressure-swing adsorption (PSA) at small to medium scales. However, so far, the techno-economic assessment of membrane processes has been focused on the production of low-purity O2. This study assesses O2 enrichment by membrane-based processes in a large purity range (30–95%), and reports significant energy and cost savings when high-performance membranes, marked by O2 permeance of 500–1000 GPU and O2/N2 selectivity in the range of 2–20, are developed. The analysis identifies that O2/N2 selectivities of 2–4, 6–15, and 20 are optimal for target purity of 30–40%, 50–65%, and >70%, respectively, leading to specific costs in the range of 20–50 $/tonEPO2 when blending with air is not considered. Purity target below 75% can be achieved by the single-stage process while double-stage processes are needed for higher purity targets. If highly-selective membranes are available, the cost of lower purity OEA can be further reduced by blending higher purity OEA with air.We demonstrate the benefits of the membrane process for four important applications. For natural gas combustion, optimal energy and cost savings of 41% and 22%, respectively, are predicted using membranes with selectivity of 4. An optimized hybrid system combining membrane enricher and post-combustion capture reduces energy consumption (22%) and cost (6%) with respect to the standalone capture. The production of medical-grade oxygen (90% purity) from membranes is economical (0.4 $/kL) compared to that from PSA (0.6–0.8 $/kL). Finally, 95% O2 can also be produced for oxycombustion with a specific cost of 32 $/tonEPO2.

An Experimental Investigation of In Situ Combustion in High Permeability Contrast Systems

Abstract A significant portion of world oil reserves reside in naturally fractured reservoirs and a considerable amount of these resources includes heavy oil and bitumen. Thermal enhanced oil recovery methods (EOR) are mostly applied in heavy oil reservoirs to improve oil recovery. In situ combustion (ISC) is one of the thermal EOR methods that could be applicable in a variety of reservoirs. Unlike steam, heat is generated in situ due to the injection of air or oxygen enriched air into a reservoir. Energy is provided by multi-step reactions between oxygen and the fuel at particular temperatures underground. This method upgrades the oil in situ while the heaviest fraction of the oil is burned during the process. The application of ISC in fractured reservoirs is challenging since the injected air would flow through the fracture and a small portion of oil in the/near fracture would react with the injected air. Only a few researchers have studied ISC in fractured or high permeability contrast systems experimentally. For in situ combustion to be applied in fractured systems in an efficient way, the underlying mechanism needs to be understood. In this study, the major focus is permeability variation that is the most prominent feature of fractured systems. The effect of orientation and width of the region with higher permeability on the sustainability of front propagation are studied. The contrast in permeability was experimentally simulated with sand of different particle size. These higher permeability regions are analogous to fractures within a naturally fractured rock. Several ISC tests with sand-pack were carried out to obtain a better understanding of the effect of horizontal, vertical, and combined (both vertical and horizontal) orientation of the high permeability region with respect to air flow to investigate the conditions that are required for a self-sustained front propagation and to understand the fundamental behavior. Within the experimental conditions of the study, the test results showed that combustion front propagated faster in the higher permeability region. In addition, horizontal orientation almost had no effect on the sustainability of the front; however, it affected oxygen consumption, temperature, and velocity of the front. On the contrary, the vertical orientation of the higher permeability region had a profound effect on the sustainability of the combustion front. The combustion behavior was poorer for the tests with vertical orientation, yet the produced oil API gravity was higher. Based on the experimental results, a mechanism has been proposed to explain the behavior of combustion front in systems with high permeability contrast.

Experiments and modeling of Komvophoron sp. Growth in hydraulic fracturing wastewater

The high management cost of wastewater generated during oil and gas production using hydraulic fracturing technology necessitates economically viable alternative technologies for remediation and reuse. In this study, an Oklahoma native microalgae strain, Komvophoron sp., was grown in four different flowback and produced water samples generated during hydraulic fracturing. Biomass production profile and pollutant removal efficiency of the strain were evaluated. The experimental data demonstrated that this strain was able to grow in all wastewater samples examined when suitable light intensity and CO2 flow rate were provided. Biomass productivity of the strain varied from 5.5 to 12 g m−3 day−1 depending on the wastewater sample used in the cultivation experiments. Very high nitrogen and phosphorus removal from the growth medium, up to 99 and 63%, respectively, could be achieved by growing and harvesting algal biomass in the wastewater samples. A mathematical model developed based on pH, light intensity and CO2 enriched air flow rate as system variables well described the experimental biomass productivity and pollutant removal efficiency data. The proposed mathematical model was successfully used to identify sets of operating conditions which would maximize biomass productivity and macronutrient removal efficiencies. Hence, the model developed in this study is a useful tool to assess technical viability and design of an efficient algal wastewater remediation process to reduce the impact of hydraulic fracturing on environment while producing biomass that can be converted to industrial bio-products including biofuels.

Determination of the effects of oxygen-enriched air with the help of zeolites on the exhaust emission and performance of a diesel engine

The aim of the present experimental study is to reduce exhaust emissions and improve performance by feeding a diesel engine with oxygen enriched air by the help of natural and synthetic zeolites. Oxygen enrichment process is carried out by a zeolite filter (ZF) system that operates by the pressure swing adsorption (PSA) method. In the experiments, clinoptilolite-type natural zeolite (NZ) in 1.3–3 mm fractions and 0.4–0.8 mm 13X HP type synthetic zeolite (SZ) were used. Scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) were used to observe the surface and particle structures of NZ and SZ and to perform the elemental analysis. According to the data obtained from the ZF system, NZ and SZ provided oxygen increases of 18.57% and 41.91%, respectively, when compared to the rate of oxygen in the air of the test environment. As a result of feeding the intake line of the engine with oxygen enriched air by using NZ and SZ, decreases in the carbon monoxide (CO), hydrocarbon (HC), smoke density, and brake specific fuel consumption (BSFC) values and increases in the nitrogen oxide (NOX), vibration, noise, exhaust gas temperature (EGT), and brake thermal efficiency (BTE) values were observed.

Investigating the effects of oxygen enrichment with modified zeolites on the performance and emissions of a diesel engine through experimental and ANN approach

Oxygen enrichment of intake air in internal combustion engines (ICE) is one of the effective methods used to reduce exhaust emissions and increase performance. In this study, oxygen enrichment process was performed with pressure swing adsorption (PSA) method using two zeolite types including acid-modified zeolite (AMZ) and base-modified zeolite (BMZ). In the experiments, clinoptilolite-type natural zeolite in 1.6–3 mm fractions was used. HCI, NH4NO3 and NaOH solutions were used to obtain AMZ and BMZ. Engine experiments were carried out using a four-stroke, single cylinder, direct injection, air-cooled diesel engine. In addition, by designing an artificial neural network (ANN) model with the capability to estimate the experimental results, its performance was tested. When the oxygen rate (21%) in the medium air, where the experiments were carried out, was compared with the oxygen rates in the air obtained with the use of AMZ and BMZ in zeolite filter (ZF) system, an increase of 17.14% and 21.90% was observed, respectively. As a result of the addition of oxygen-enriched air to the fresh air drawn into the combustion chamber in the ZF system, the carbon monoxide (CO), hydrocarbon (HC), smoke density and brake specific fuel consumption (BSFC) values decreased and the nitrogen oxide (NOX), vibration, noise, exhaust gas temperature (EGT) and brake thermal efficiency (BTE) values increased when compared to standard diesel engine (SDE). According to the obtained results, ANN estimated the exhaust emission and performance parameters with the regression values (R) of 0.99423–0.99990 and low error rates in the range of 0.002–6.93%.

Review on the ecophysiology of important Andean fruits: Solanaceae

The high Andean areas present ecophysiological conditions suitable for the cultivation of many fruit species, especially of the Solanaceae family. The objective of this review is to present important ecophysiological information on four fruit trees grown in cold climates: Cape gooseberry, tree tomato, lulo, and sweet cucumber o pear melon. The cape gooseberry is a species well adapted to cold tropical climate, it is grown between 1,800 and 2,700m a.s.l., with temperatures of 13 to 16°C. It is highly adapted to high solar radiation and to the abrupt changes between the day and night temperatures. It requires a precipitation of 1,000 to 1,800mm year-1 uniformly distributed throughout the year, and is sensitive to water deficit but also to waterlogging and strong winds. The tree tomato, in Colombia, produces better from 1,800 to 2,600m a.s.l., with temperatures between 13 and 20°C, annual rainfall between 1,500 and 2,000mm, relative humidity around 80%, and solar brightness of 1,800 to 2,300 hours/year; it does not resist strong winds, water deficit or waterlogging. The lulo requires environments with high precipitation (1,000 to 2,800mm) and penumbra because it loses a lot of water through transpiration but waterlogging also affects it; it grows well in areas between 1,600 to 2,400m a.s.l. and 16 to 24°C, with photosynthesis rates up to of 34.03µmol CO2 m-2 s-1. The sweet cucumber is of growing interest in many exotic fruit markets, it grows at 900-2,800m a.s.l. with temperatures <25°C and responds well to air enrichment with CO2.

Improving the Performance of Composite Hollow Fiber Membranes with Magnetic Field Generated Convection Application on pH Correction.

The membranes and membrane processes have succeeded in the transition from major technological and biomedical applications to domestic applications: water recycling in washing machines, recycling of used cooking oil, recovery of gasoline vapors in the pumping stations or enrichment of air with oxygen. In this paper, the neutralization of condensation water and the retention of aluminum from thermal power plants is studied using ethylene propylene diene monomer sulfonated (EPDM-S) membranes containing magnetic particles impregnated in a microporous propylene hollow fiber (I-PPM) matrix. The obtained membranes were characterized from the morphological and structural points of view, using scanning electron microscopy (SEM), high resolution SEM (HR-SEM), energy dispersive spectroscopy analysis (EDAX) and thermal gravimetric analyzer. The process performances (flow, selectivity) were studied using a variable magnetic field generated by electric coils. The results show the possibility of correcting the pH and removing aluminum ions from the condensation water of heating plants, during a winter period, without the intervention of any operator for the maintenance of the process. The pH was raised from an acidic one (2–4), to a slightly basic one (8–8.5), and the concentration of aluminum ions was lowered to the level allowed for discharge. Magnetic convection of the permeation module improves the pH correction process, but especially prevents the deposition of aluminum hydroxide on hollow fibers membranes.

Effect of the combustion system on reduction of thermal specific energy consumption in an industrial high temperature process

This paper presents an experimental study carried out in an industrial furnace for frits production using different configurations of burners based on different combustion techniques such as enriched air combustion, flat-flame oxy-combustion and preheater air combustion. The residence time of combustion gases inside the furnace also was modified. Several combustion configurations were tested and its effects on productivity and thermal energy specific consumption and efficiency were determined. The results show that higher residence time of the combustion gases can decrease significantly the specific consumption of fuel, while the change of the burners and combustion techniques did not show significant effects on decreasing the energy consumption. However, it is highlighted that the oxy-combustion flat-flame burners produced the lowest specific consumption of fuel. Even though the experiments were conducted in a furnace for frit production, the corresponding results can also be applied to guide or improve other industrial high temperature processes.

Simulation of a new biomass integrated gasification combined cycle (BIGCC) power generation system using Aspen Plus: Performance analysis and energetic assessment

A new biomass integrated gasification combined cycle (BIGCC), which featured an innovative two-stage enriched air gasification system coupling a fluidized bed with a swirl-melting furnace, was proposed and built for clean and efficient biomass utilization. The performance of biomass gasification and power generation under various operating conditions was assessed using a comprehensive Aspen Plus model for system optimization. The model was validated by pilot-scale experimental data and gas turbine regulations, showing good agreement. Parameters including oxygen percentage of enriched air (OP), gasification temperature, excess air ratio and compressor pressure ratio were studied for BIGCC optimization. Results showed that increase OP could effectively improve syngas quality and two-stage gasification efficiency, enhancing the gas turbine inlet and outlet temperature. The maximum BIGCC fuel utilization efficiency could be obtained at OP of 40%. Increasing gasification temperature showed a negative effect on the two-stage gasification performance. For efficient BIGCC operation, the excess air ratio should be below 3.5 to maintain a designed gas turbine inlet temperature. Modest increase of compressor pressure ratio favored the power generation. Finally, the BIGCC energy analysis further proved the rationality of system design and sufficient utilization of biomass energy.

Research on nitrogen enriched air flow of on-board inert gas generating system

Research on nitrogen enriched air flow of on-board inert gas generating system

Hyperoxia in Depression

Several studies of normobaric hyperoxia in some neurological conditions have demonstrated clinical benefits. Oxygen enriched air may increase oxygen pressure in brain tissue and have biochemical effects such as on brain erythropoietin gene expression, even in patients without lung disease.

Effects of elevated CO2 levels on lung immune response to organic dust and lipopolysaccharide

Workplaces with elevated organic dust levels such as animal feed barns also commonly have elevated levels of gasses, such as CO2. Workers exposed to such complex environments often experience respiratory effects that may be due to a combination of respirable factors. We examined the effects of CO2 on lung innate immune responses in mice co-exposed to the inflammatory agents lipopolysaccharide (LPS) and organic dust. We evaluated CO2 levels at the building recommended limit (1000 ppm) as well as the exposure limit (5000 ppm). Mice were nasally instilled with dust extracts or LPS and immediately put into chambers with a constant flow of room air (avg. 430 ppm CO2), 1000 ppm, or 5000 ppm CO2 enriched air. Results reveal that organic dust exposures tended to show decreased inflammatory responses with 1000 ppm CO2 and increased responses at 5000 ppm CO2. Conversely, LPS with addition of CO2 as low as 1000 ppm tended to inhibit several inflammatory markers. In most cases saline treated animals showed few changes with CO2 exposure, though some changes in mRNA levels were present. This shows that CO2 as low as 1000 ppm CO2 was capable of altering innate immune responses to both LPS and organic dust extracts, but each response was altered in a different fashion.

The effect of increased temperature and CO2 air enrichment on the nutritive value of orchard grass (Dactylis glomerata) in permanent grassland

AbstractHigh yielding ruminant livestock require high nutritive value in forage for maintenance, growth and production. Climate change has been documented as impacting on the nutritive value of forage plants. Therefore, the aim of this study was to investigate the impact of increased temperature in combination with CO2-enhancement on the nutritive value of orchard grass (cocksfoot; Dactylis glomerata L.), as a C3 model plant, widespread in mountainous permanent grassland plant communities. Functional traits and forage quality of orchard grass were investigated both under ambient (C0T0) and under simulated, future climate conditions (C2T2) with increased temperature (+3°C) and enhanced CO2 concentration (+300 ppm) under field conditions. Plant samples were taken from each of the three growths over a period of three consecutive years and numerous functional properties and forage quality parameters were determined. Special attention was paid to the determination of water-soluble carbohydrates (WSC), crude protein (CP), non-protein N (NPN) and metabolizable energy (ME) as possible indicators for different climatic conditions. It is hypothesized that (i) functional traits and (ii) forage quality of orchard grass are altered by increased temperature and higher CO2 concentration. The results showed a negative impact of C2T2 compared to C0T0 on tiller height (54.4 v. 70.6 cm) and weight (2.42 v. 3.22 g) as average over cuts and years. The NPN content was lower in C2T2 (312 g/kg CP) compared to C0T0 (339 g/kg CP). In contrast, the WSC content was higher in C2T2 (90.3 g/kg DM) compared to C0T0 (82.5 g/kg DM). Both ME content and digestibility were increased in C2T2 (9.18 ME/kg DM and 68.2%) compared to C0T0 (8.86 ME/kg DM and 65.4%). Concluding, under increased temperature and enhanced CO2, both functional traits and certain nutrients and their fractions appear to change in orchard grass.

Nitrogen enriched air for Nox reduction in Diesel engine

This paper analyzes the impact of nitrogen enriched air on emissions, in cylinder pressure, heat released during the working cycle and fuel consumption of a diesel engine. The experiment was performed on a naturally aspirated single cylinder diesel engine by increasing the nitrogen concentration supplied through a cylinder and NOx, CO, THC emissions were all measured with the help of a five gas analyzer. It was observed that enriching the inlet air with nitrogen decreases the NOx concentration considerably with a penalty on hydrocarbon emissions and thus the fuel conversion efficiency.

Hyperoxia in depression

IntroductionSeveral studies of normobaric hyperoxia in some neurological conditions have demonstrated clinical benefits. Oxygen enriched air may increase oxygen pressure in brain tissue and have biochemical effects such as on brain erythropoietin gene expression, even in patients without lung disease.ObjectivesThis pilot, randomized, double-blind study examined the efficacy of normobaric hyperoxia as a treatment for depression.MethodsFifty-five consenting patients aged 18-65 years with mild to moderate depression were included in the study. Participants underwent a psychiatric inclusion assessment and a clinical evaluation by a psychiatric nurse at baseline, 2 and 4 weeks after commencement of study intervention. Participants were randomly assigned to normobaric hyperoxia of 35% fraction of inspired oxygen or 21% fraction of inspired oxygen (room air), through a nasal tube, for 4 weeks, during the night. Patients were rated blindly using the Hamilton Rating Scale for Depression (HRSD); Clinical Global Impression (CGI) questionnaire; Sheehan Disability Scale (SDS).Results The present study showed a significant improvement in HRSD (p<0.0001), CGI (p<0.01) and in SDS (p<0.05) among patients with depression who were treated with oxygen-enriched air, as compared to patients who were treated with room air. In CGI, 69% of the patients who were treated with oxygen-enriched air improved compared to 23% patients who were treated with room air.ConclusionsThis small pilot study showed a beneficial effect of normobaric hyperoxia on some symptoms of depression.DisclosureNo significant relationships.

The effects of dimethyl ether enriched air (DMEA) on exhaust pollutants and performance characteristics of an old generation diesel engine

ABSTRACT In this study, the effect of dimethyl ether enriched air (DMEA) on pollutants and performance characteristics a diesel engine was evaluated. The combustion parameters have been evaluated by simulation method. Simulation results show that the in-cylinder pressure increases slightly while the combustion duration is shorter for DMEA-engine compared to the original case. In addition, a comparative test on DMEA-engine was carried out, in which DME was supplied into the intake manifold at a constant concentration to the mass of intake air. The results show that, when operating with DMEA, the brake specific energy consumption (BSEC) reduces slightly at full load condition by 2.20%. While, at a speed of 1600 rpm, the BSEC increases from 2.6% to 7.7% at low load and slides from 3.1% to 5.5% at high load condition. The smoke level reduces moderately when the test engine operating with DMEA by 6.25% on average at full load and 2.0% to 8.2% as load increases at intermediate speed condition. The CO emission reduces 5.28% while NOx and HC emission increase 5.62% and 7.1% on average at full load condition. At the speed of 1600 rpm, CO reduces 5.9% while NOx and HC increase by 7.1% and 27.5% on average.

Application of oxygen enrichment and adiabatic humidification to suction air for reducing exhaust emissions in a gasoline engine

ABSTRACT This paper aims to reduce the exhaust emissions of a gasoline engine by conditioning the engine intake air. The oxygen enrichment of inlet air to reduce the HC and CO emissions and humidifying the inlet air to control NOX emissions was applied. The intake air oxygen concentration was increased from 21% to 25% by 2% interval. The oxygen enrichment of the engine inlet air increased the combustion rate, and thus combustion improved, and thermal efficiency increased. This situation led to a reduction in HC emissions and CO emissions. However, the combustion improvement caused a striking rise in NOX emissions because of the high cylinder temperature and high oxygen concentration. This undesirable effect was tried to be alleviated by adiabatic humidification of the engine inlet air. For this purpose, the relative humidity of the intake air was increased from 35% to 65% before and then to 85%. For this, the intake air passed through the conditioning chamber, the dry thermometer temperature lowered by 4 °C for a relative humidity of 85% thanks to the evaporative cooling of water. The results showed that oxygen enrichment caused a 13.5% and 9.3% increase in thermal efficiency in order of half and full load. The humidification method resulted in a 14.3% and 18.3% decrease in thermal efficiency for half and full load. The results also showed that the humidification method could only control NOX increment generated at half load and 23% oxygen condition.

Effect of Oxygen Enrichment on Top Layer Sinter Properties

Properties like shatter index and yield of the top layer of iron ore sinter in a Dwight-Lloyd sintering machine have always been a bottleneck for improvement of overall sinter quality due to the practical limitation of achieving high sintering temperature and dwell time in the top layer. To improve the sinter yield and shatter index of top layer, various technologies like usage of additional coke breeze, gaseous fuel injection and oxygen enrichment have been reported. In this paper, effect of oxygen enrichment of the incoming air on top part of the sinter bed was investigated using pot sinter experiments with varying oxygen percentage of 0 to 12 vol.% in the incoming air for an initial duration of 1/3rd of the total sintering time. It was observed that with increasing oxygen percentage from 0 to 9 vol.% in the incoming air, top layer sinter yield increased from 76.1 to 80.6% and shatter index from 69.0 to 74.8%. The improvement in sintering properties were mainly attributed to the promotion of sintering reaction with improved time-temperature profiles specifically at the top layer which results in increase of phase fraction of Silico ferrites of calcium and aluminum (SFCA-I). However, beyond 9 vol.% oxygen enrichment, change in sinter properties was not significant. It is considered that excessive increase of oxygen enrichment does not contribute much to the increase of top layer peak temperature.

The Experimental Study of the Kinetics of the Cyclic Adsorption Process of Air Enrichment with Oxygen

For mass transfer cyclic processes in the “adsorptive - porous adsorbent” system when air is enriched with oxygen by the method of short-cycle heatless adsorption, a new method has been implemented for determining the coefficients of mass transfer and mass conductivity of processes in systems with a solid phase from kinetic curves. It has been experimentally proved that during the adsorption separation of atmospheric air, the rate of cyclic “adsorption - desorption” processes can be limited by both internal and external diffusion resistance. The mass conductivity coefficients are determined depending on the mass content of the distributed adsorptive (O2, N2) by a method that does not require the implementation of the intradiffusion kinetic regime. The analysis of the kinetics of the process of air enrichment with oxygen is carried out; the coefficients of mass transfer and mass conductivity, which can be used in kinetic calculations and numerical study of the properties and modes of the cyclic adsorption process of atmospheric air separation and oxygen concentration, are determined.

Using of Enriched Air Blast While Operation of Shaft Furnaces at LLC “Mednogorsk Copper-Sulfur Plant”


 
 
 In this article we consider the practices of blast smelting of copper-bearing charge with oxygen enriched air blast at Mednogorsk Copper-Sulfur Plant. The degree of air blast enrichment with oxygen has been increased from 30% to 36%, and productivity has raised by 20.1%. The copper content in matte has made up 33.0-35.3%, in dump slag – to 0.5% Cu. We have provided the mass and heat balances of the smelting. We have demonstrated the influence of air blast oxygen enrichment degree on productivity of blast smelting, solid fuel consumption, contents and quantity of smelting products.
 
 
 
 Keywords: blast smelting, air blast, oxygen enriched, enrichment degree, furnace capacity, specific smelting rate, matte, anthracite