Gas Phase Flow Research Articles

Thermophysical processes in dry granulation of metallurgical slags

Mathematical model for theoretical analysis of thermophysical processes of melt drops solidification is examined during their motion inside cooling gas, applying to granulation task. The heat exchange equations during granulation, taking into account convection, heat conductivity in solid phase and Stefan conditions on the boundary of phase transition, are presented. The relationships characterizing correlation of the power exchange parameters in dispersed medium are obtained in the conditions of phase transition in melt drops inside gas phase flow. Analytical relationships allow to consider correlation of the parameters which characterize granulation process, to provide directions of efficient conduction of the processes for achieving the preset aims and to reveal the conditions for optimal technological parameters of the process. Speed of the power exchange processes determines the size of an installation and allows to make preliminary assessment during designing. Different motion modes for particles and gas are investigated. The variants for calculation of gas dynamic parameters of straight flying trajectory for a slag melt particle are suggested; they are based on solving the problem of particle motion in the gas medium, taking into account particle size, medium resistance, initial particle speed. Used relationships allow to assess the particle flying time, which is corresponded to the required time of particle cooling during its flying, and to choose programming conditions for motion of dispersed jet of slag melt. These conditions guarantee forming of solid crust on the cooled particle and possibility of size determination for a granulation system. Possible scheme of slag heat realization, allowing to utilize maximally the exergy of secondary power resources, is considered. The obtained results can be used for improvement of the existing installations fir dry granulation and for designing of the new ones, as well as for optimization of operating modes of granulators, for their efficiency rise and increase of power saving possibilities for a granulation system.  The research was conducted within the framework of the State assignment, project No. FSWF-2020-0019.

Thermodynamic assessment of nonstoichiometric oxides for solar thermochemical fuel production

Two-step solar thermochemical cycling (STC) based on nonstoichiometric oxides is an ideal means of solar fuel (e.g., H2, CO) production. Screening of nonstoichiometric oxides with excellent thermodynamic performance is key to achieving high solar-to-fuel efficiency. However, application-driven materials assessment intended for reactor-level solar fuel production performance requires mimicking realistic operating conditions of on-sun tests in a laboratory setting, which makes oxides assessment and screening an onerous task to accomplish experimentally. In this work, a rapid assessment and screening model of nonstoichiometric oxides for two-step solar thermochemical cycling assuming fixed-bed flow pattern and quasi-equilibration of the solid with the flowing gas phase is developed, with solar-to-fuel efficiency being the target function of optimization. The model accounts for the thermodynamic parameters of oxide materials and typical operating conditions of experimental thermochemical cycling. This study employed the model to explore and compare two groups of typical nonstoichiometric oxides (CeO2- and (LaSr)MnO3-based) for their maximum efficiency under their uniquely optimized cycling conditions. The results show that CeO2 can reach a maximum efficiency of 12.9% at reduction temperature of 1500 °C, which is superior to other candidate materials, including 20 mol% Zr-doped CeO2 (10.1%), La0.6Sr0.4MnO3 (2.5%) and La0.8Sr0.2MnO3 (3.3%). Even when the reduction temperature is lowered to 1350 °C, ceria yields the highest efficiency amongst the candidate STC materials considered. The optimal cycling strategy depends on the inherent thermodynamic properties of the oxides. This approach serves as a framework for assessing the maximum efficiency and optimal conditions of candidate thermochemical materials within a range of constraints rather than comparing materials under arbitrary cycling conditions, which may inherently favor one material over another. For oxidation temperatures below 800–1000 °C, the model could be further improved by considering reaction kinetics.

Experimental Study on Gas–Water Relative Permeability Characteristics of Tight Sandstone Reservoir in Ordos Basin

Accurate measurement of relative permeability curve is the basis for evaluating gas reservoir performance. The unsteady-state method could bring significant measurement error for low-permeability cores. However, it is difficult to control the constant gas flow rate in the traditional steady-state method, which obstacles the experimental operation. In this study, an improved steady-state method was proposed. First, the pressure value obtained from the experiment, when the gas permeability no longer changed with the average pressure on the rock core, was set as the testing pressure. Then, the gas was injected under constant pressure, and the water was injected with a constant flow rate. Finally, the relative permeability values of gas and water phases were calculated based on Darcy’s law. Comparative analysis of the results of the relative permeability curves under formation pressure and pressure with negligible slip effect indicates that the relative permeability curves are the same in gas and water phases, proving the feasibility of the new method. Further, the results were compared with those of the test method at normal pressure, the water-phase relative permeability showed no significant change, the relative permeability of gas phase was larger, the two-phase flow area became wider, and the irreducible water saturation was lower than that at the normal pressure. This result reflects that pressure does not significantly affect the flow of wetting phase but tremendously influences the nonwetted phase under low pressure. The relationship between relative permeability and water saturation is linear in the semilogarithmic coordinate diagram and can be described by using the following relationship: ln k rg / k rw = a S w + ln b . With the decrease in the core permeability, relative permeability curve, and isotonic point moved to the right, irreducible water saturation gradually increased, and residual gas saturation decreased, indicating that the smaller permeability induced a lower gas-phase flow capacity.

CFD simulation of gas pressure drop in porous packing for rotating packed beds (RPB) CO2 absorbers

Rotating packed bed (RPB) is a promising technology which can be used to intensify mass transfer in absorption processes. A better understanding of fluid dynamics is crucial to fill the gap in fundamental knowledge. Raising awareness on new technology and creating rules for process design and control are also very important. The experimental investigation of fluid in rotating beds is a very complex and difficult issue. What is more, the knowledge of the phase behavior in an RPB device is still insufficient. Therefore, an CFD (computational fluid dynamics) simulation is proposed as a tool for the study of gas phase flow inside porous packing. This study presents a three-dimensional numerical model for two fluid models: k-ε and RNG k-ε, for predicting dry pressure drop. The obtained simulation outcome was compared with the experimental results. The experimental dry pressure drop for porous packing was investigated for rotational speed in the range from 150 rpm to 1500 rpm and compared to the results from the CFD model. The comparison between the experimental and simulation results indicates very good consistency for the entire range of the rotational speed of interest. CFD modelling is recognised as an adequate tool leading to the better understanding of gas phase behaviour inside an RPB, filling an essential gap in our knowledge of the hydrodynamics of rotating packing, which allows to improve the design and performance of the process in RPB in terms of minimizing energy and material consumption.

Formation dynamics and size prediction of bubbles for slurry system in T-shape microchannel

The bubble formation dynamics and size manipulation in the slurry of polystyrene microspheres in the microfluidic T-junction were visually investigated by a high-speed camera. Based on the evolution of the bubble neck with time, the formation process of bubbles is divided into three stages: filling, squeezing and pinch-off. The particle concentration has an obvious effect on the squeezing stage, while less impact on the filling and pinch-off stages. In the squeezing stage, the evolution of the dimensionless minimum neck width of bubbles with time could be described by a power-law relationship. The increase of the particle concentration or continuous phase flow rate could lead to the increase of body flow of the continuous phase and the enhancement of the squeezing force acted on the bubble neck, correspondingly, the power-law index α in the squeezing stage enlarges. Moreover, the bubble size increases with the increase of the gas phase flow rate and the decrease of the particle concentration and continuous phase flow rate. However, the effect of the particle concentration on the bubble size weakens with the increase of the continuous phase flow rate. In addition, a new prediction correlation of the bubble size for the slurry system in a T-shape microchannel was proposed with good prediction accuracy.

Impact of gas pressure on particle feature in Fe-based amorphous alloy powders via gas atomization: Simulation and experiment

• The flow dynamics of the gas phase and gas-melt two-phase fields, and the break-up process were illustrated. • The particle size distributions of simulated results were consistent with the powder experimental tests. • The Fe-based alloy powders with diameters in the range of 25–45 μm were found to be a fully amorphous phase. Gas atomization is now an important production technique for Fe-based amorphous alloy powders used in additive manufacturing, particularly selective laser melting, fabricating large-sized Fe-based bulk metallic glasses. Using the realizable k-ε model and discrete phase model theory, the flow dynamics of the gas phase and gas-melt two-phase flow fields in the close-wake condition were investigated to establish the correlation between high gas pressure and powder particle characteristics. The locations of the recirculation zones and the shapes of Mach disks were analyzed in detail for the type of discrete-jet closed-coupled gas atomization nozzle. In the gas-phase flow field, the vortexes, closed to the Mach disk, are found to be a new deceleration method. In the two-phase flow field, the shape of Mach disk changes from “ S ”-shape to “ Z ”-shape under the impact of the droplet flow. As predicted by the wave model, with the elevation of gas pressure, the size of the particle is found to gradually decrease and its distribution becomes more concentrated. Simulation results were compliant with the Fe-based amorphous alloy powder preparation tests. This study deepens the understanding of the gas pressure impacting particle features via gas atomization, and contributes to technological applications.

Effects of inclination angle and heat power on heat transfer behavior of flat heat pipe with bionic grading microchannels

Bionic structure has become a popular tool to design heat pipes for its ability of heat transfer enhancement and liquid transport. Inspired by the powerful water collection and transfer capability of pitcher plant surface, this paper presents a new flat heat pipe design with bionic grading microchannels (BGFHP) based on special high-low structured surface. Firstly, the performance advantages of BGFHP are revealed by comparing the heat transfer performance and visible internal flow characteristics of BGFHP and conventional FHP. Secondly, the performance variation and influence trend of BGFHP are investigated experimentally with inclination angle and thermal power as variables. Finally, thermal management effects of natural cooling, FHP and BGFHP in fuel cells are compared to demonstrate the practical application of BGFHP. Results show that the high-low channel structure of BGFHP has the advantages of micro-channel hydraulic transport, and the small channel increases the heat transfer area, circulation efficiency and gas phase flow area, resulting in better start-up time and heat transfer capacity than the traditional FHP. The thermal resistance of BGFHP is reduced by 22%, while the thermal conductivity is increased by more than 40%. In the load range of 10–26 W and inclination angle range of 0–90°, the overall thermal resistance and temperature uniformity of BGFHP decreases and then increases as the inclination angle increases. With the increase of heat power, the thermal resistance of BGFHP gradually decreases, whereas the temperature uniformity first decreases and then increases. The optimal working condition of BGFHP is 45° and 24 W, with a minimum thermal resistance of 0.21 K/W. In the fuel cell temperature control test, the BGFHP was able to maintain the temperature below 52 °C, which is 5 °C lower compared to the FHP. This result shows the advantage of the BGFHP in terms of temperature control.

Numerical simulation of the stability of water fiber-optic in water jet-guided laser machining

Water jet-guided laser machining is a new compound machining technology, which has been widely used in many fields due to its better processing effect. In this technology, the coupling of laser beam and micro-water jet directly determines the machining effect, and the prerequisite for successful coupling is the steady flow of the water jet, so ensuring the stability of the micro-water jet is the key to the stable machining of water jet-guided laser. Therefore, it is of great significance to studying the stability of the water fiber-optic in water jet-guided laser processing. In this paper, aiming at the problem that the stability of the water fiber-optic is difficult to control, a finite element model of the water fiber-optic is established. The convection model is vortex gas-phase flow “enveloped” water fiber-optic which is used to explain the interaction mechanism, and the flow field distribution of gas-phase flow and water fiber-optic convection was obtained. The results show that water fiber-optic is refined under the constraint of gas-phase flow, and the maximum processing distance can increase by three times. At the same time, the gas-phase flow can accelerate the removal of processing debris, and the processing accuracy and efficiency are improved.

Production of Niobium Nitride Via Nitrogen-Based Solid-Gas Reaction

Nanostructured niobium nitride was synthesized through a solid-gas reaction in an atmosphere of nitrogen and hydrogen using an oxalic niobium precursor. Crystal phases evolution throughout the reactive processes were evaluated using X-Ray Diffraction, reaction parameters modifications were performed in isotherm time, gas flow, and precursors’ mass. It was verified the synthesis of a stable NbN material with a hexagonal structure under the following conditions: 1g of precursor, 300 min of isotherm at 1100 °C and, the gas flow of N2 = 40% (v/v), and H2 = 60% (v/v). The increase in gas phase flow and the decrease of solid load favored the process, and a pure and single-phase powder was obtained. This set indicates the importance of physical resistance in the fluid-particle interaction process. Under these conditions, the solid obtained had a crystallite size of 30 - 50 nm.

Effect of bend of horizontal rectangular duct on Scattering and Breakup of gas-liquid interface

The flow of a liquid film sheared by gas stream in a horizontal rectangular bent duct was investigated using a high-speed camera. Compared to the straight horizontal duct condition, the local gas-phase velocity distribution in the bend and the effects of interactions such as reflections of waves impinging on the wall remain unknown. In this study, we investigate the unique scattering and splitting behavior that occurs at the bend by varying the gas-phase flow velocity and the bend angle of the rectangular duct. Specifically, Bag breakup was quantitatively evaluated using We number and compared with Bag breakup generated from a single droplet using characteristic time t*bk. The results showed that Bag breakups were unevenly distributed due to bend effects, and the We number varied depending on the location of the Bag breakup. It was also found that the possible range of the characteristic time of bag breakup was smaller than that of a single droplet.

Numerical study on the characteristics of a nano-aluminum dust-air jet flame

Nano-sized aluminum dust is quite attractive in the application scenarios with limited residence time. This study simulated an aluminum nanoparticle-air jet flame in a burner that was proposed to characterize the mixing and burning properties of dust and air in a classical ramjet configuration. The model considers the flow of gas phase by employing three-dimensional multicomponent Navier-Stokes equations, and the aluminum particles via the Lagrange approach. A combustion sub-model was developed to characterize the heat convection, radiation and combustion processes of nano-sized aluminum particles. Thereafter, the model was validated by comparing with experimental results of dust jet flow and aluminum particle combustion. With the present model, the characteristics of flow field, and variations of particle temperature, heat release and statuses etc. were examined in detail, by which the mixing zone and flame structure were defined. The results showed that the nano-aluminum particles in the inner mixing layer were firstly ignited by the hot co-flow air and burned, and these particles in the core jet region were ignited downstream. Once the aluminum particles were ignited, they burned out promptly in this burner. The effects of particle size were evaluated, and the results show that the lengths of mixing layer and reaction zone, as well as the width of reaction zone reduce with decreasing particle size, whereas the width of mixing layer stays the same.

Computational analysis of the mechanisms and characteristics for pulsating and uniform flame spread over liquid fuel at subflash temperatures

The present study aims to gain insight of the mechanisms and characteristics for pulsating and uniform flame spread over liquid fuel at subflash temperatures. A specific goal is to use the validated three-dimensional (3-D) numerical model to reveal fine details of the gas and liquid phase flows as well as the resulting flame characteristics, which are challenging to obtain experimentally. To facilitate the study, 3-D formulations have been developed to explicitly solve the transport equations in both phases. A compressible solver was formulated for flame propagation in the gas phase using a one-step chemical reaction expression and mixture-averaged diffusion coefficients for the gaseous species. An incompressible solver with temperature dependent thermo-physical properties was employed to describe the convective motions and heat transfer in the liquid fuel region. Validation has been conducted for both uniform and pulsating spreads over a narrow 1-propanol tray with varying fuel depths through comparing the predicted flame front evolution with published measurements. Further qualitative comparison has also been conducted for some predicted fine features of the gas and liquid phase flows and flame spreading characteristics with published experimental observations. For both the uniform and pulsating spread, the detailed flame structure including the main diffusion flame and a small stratified premixed flame at the front have been captured. Wherever relevant, the detailed predictions were also used to shed light on some discrepancies in previously reported features in different laboratory studies and numerical simulations. Finally, the detailed 3-D predictions were used to illustrate fine features of the subsurface convective flow and its relative position to the flame front, the relative magnitudes of the subsurface flow velocity and that of the spread rate as well as the role of the thermocapillary-driven subsurface flow in the flame spread mechanism.

Experimental investigation of water-gas mixed seepage parameters characteristics in broken coal medium

In order to study the mixed permeability characteristics of broken coal medium, the parameter changes during water-gas permeation are analyzed and discussed in this study. It includes the law of two-phase flow state transformation, the law of permeability evolution and the principle of effective stress action. Firstly, the water-gas mixed permeation test system was designed by independent design. Then the gas and liquid two-phase permeation parameters were measured in real time by using multiple sets of sensors. The results are as follows: In one hand, the two-phase seepage process in broken coal medium, the seepage apparent Reynolds number is mainly distributed between 1230–2207. The difference of two orders of magnitude between the kinematic viscosities of the two fluids leads to an asynchronous transition process between the liquid and gas phase flow regimes. On the other hand, there is a competitive relationship between the relative permeability ratio of water and gas phases. When the proportion of gas phase relative permeability is distributed in the interval 71.7%–85.1%, the proportion of gas phase relative permeability is dominant, and it is most sensitive to the influence of the compaction deformation process of the initial pore structure. At the same time, the permeability k decreases with the increase of the effective stress σov in all three stages of the compaction deformation of the skeleton of the broken coal medium, in accordance with the relationship: σov=0.678/k+0.608. The effective stress will directly determine the pore deformation process of the structure of the broken coal medium.

Effect of pore-throat structure on gas-water seepage behaviour in a tight sandstone gas reservoir

In this study, effect of pore-throat structure on gas–water seepage behaviour in a tight gas sandstone formation has been experimentally examined. More specifically, pressure-controlled mercury injection tests were performed to measure capillary pressure and identify the characteristics of a pore-throat structure such as its connectivity and size distributions. According to the pore-throat structure together with its median throat radius, pore-throat skewness, relative sorting coefficient, and cutoff throat volume ratio, the pore-throat structure was then classified into three types, while gas permeabilities under different conditions are corrected with consideration of the slippage effect and different pore-throat structures. Subsequently, seepage characteristics, including distribution of movable fluid saturation, relative permeability, and water locking degree, were quantified using displacement experiments integrated with the nuclear magnetic resonance (NMR) technique for the three classified types of pore-throat structure, respectively. With the deteriorated pore-throat structure, the throat size distribution curves are found to shift to the left, porosity gradually decreases, and the irreducible water saturation gradually increases. Both water saturation at the isotonic point and irreducible water saturation increase, and gas phase relative permeability at the irreducible water saturation together with water relative permeability within the saturation range of simultaneous gas–water flow decreases consecutively, indicating the seepage capacity of gas and water is weakened. With the deteriorated pore-throat structure, the water locking becomes more serious and its corresponding water saturation together with the damage coefficient of gas permeability is larger, and the influence of water on gas phase flow is more significant. The pore-throat structure, especially its connectivity, is found to be the main factor dominating the movable fluid saturation and two-phase seepage characteristics in a tight sandstone gas reservoir. This study allows us to better understand how the pore-throat structure affects the gas–water seepage behaviour in a tight gas reservoir, provided that its characterization has been quantitatively conducted and the seepage patterns are identified and classified within a consistent and unified framework. These findings further provides solid fundamentals for efficient and effective exploitation of tight gas reservoirs.

Boiling Heat Transfer and Visualization for R717 in a Horizontal Smooth Mini-tube

The paper presents an experimental and theoretical investigation on the two-phase flow boiling heat transfer with ammonia (R717) as the refrigerant in a horizontal smooth mini-tube with inner diameter of 3mm. The experimental data were obtained in the following condition, the heat flux density is 10∼30 kW · m − 2 , the mass flux is 40∼200 kg · m − 2 · s − 1 , the saturation temperature is -10∼10 ℃, and the range of vapor quality is 0.1 ∼1. The experimental results show that the heat transfer coefficient before dryout phenomenon increases and gradually reaches a peak with the increase of vapor quality, but occurs heat transfer deterioration after dryout phenomenon. Combined with the transform of flow patterns, the effect of mass flux, heat flux density, and saturation temperature on the heat transfer coefficient and friction pressure drop are analyzed. The theoretical gas phase flow velocity of ammonia is much higher than other refrigerants, and the flow boiling heat transfer for ammonia is more dependent on convective boiling. The existing correlations of two-phase flow are compared with the measured data of ammonia. According to the experimental and comparative results, Kew and Conwell correlation and Müller-Steinhagen and Heck correlation were updated respectively, and new boiling heat transfer correlation and frictional pressure drop correlation were obtained.

Monolithic lateral p–n junction GaAs nanowire diodes via selective lateral epitaxy

Semiconductor p–n junctions are essential building blocks of electronic and optoelectronic devices. Although vertical p–n junction structures can be formed readily by growing in sequence, lateral p–n junctions normal to surface direction can only be formed on specially patterned substrates or by post-growth implantation of one type of dopant while protecting the oppositely doped side. In this study, we report the monolithic formation of lateral p–n junctions in GaAs nanowires (NWs) on a planar substrate sequentially through the Au-assisted vapor–liquid–solid selective lateral epitaxy using metalorganic chemical vapor deposition. p-type and n-type segments are formed by modulating the gas phase flow of p-type (diethylzinc) and n-type (disilane) precursors in situ during nanowire growth, allowing independent sequential control of p- and n-doping levels self-aligned in-plane in a single growth run. The p–n junctions formed are electrically characterized by fabricating arrays of p–n junction NW diodes with coplanar ohmic metal contacts and two-terminal I–V measurements. The lateral p–n diode exhibits a 2.15 ideality factor and a rectification ratio of ∼106. The electron beam-induced current measurement confirms the junction position. The extracted minority carrier diffusion length is much higher compared to those previously reported, suggesting a low surface recombination velocity in these lateral NWp–n diodes.

Evaluating the Effectiveness of Turbulence Models in the Simulation of Two-Phases Combustion

Supersonic atomized combustion is one of the crucial physical and chemical processes occurring in a jet engine. Numerical simulations of these processes are of scientific and applied interest for the development of high-efficiency jet systems. This paper aims to study the interaction between a fluid jet and a supersonic transverse flow with an analysis of the two-phase mixing process using a large eddy turbulent model based on the Euler-Lagrange method. Favre-filtered Navier-Stokes equations were used to describe the gas phase. The liquid phase was expressed in the form of discrete droplets whose formation was calculated using Kelvin-Helmholtz decay models, Rayleigh-Taylor and Taylor analogy. The results of numerical simulation are in a good consistency with experimental data of other studies. It was found that the behaviour of the gas phase flow is caused by the pressure gradient due to which the high velocity flow enters the atomization zone, deflecting to the near-wall region. The relative gas-liquid velocity was shown to significantly affect the motion of the droplet. High velocity of the gas phase at the leading edge and in the central region of the atomization zone leads to acceleration of the droplets until the relative gas-liquid velocity becomes equal to zero. The results obtained can be used to evaluate the atomization process when designing a scheme for a fluid jet injection into a supersonic flow.

Modelling Flow and Fate of Contaminants in Groundwater Using a Version of the Five Steady- State Pollutant Transport Models

It is essential to understand pollutant flow and fate in the permeation zones for adequate groundwater quality protection. This review highlights the hydraulic controls on pollutant filtration into the groundwater. The study is divided into seven sections, viz: Numerical modelling of contaminants in aquifers; Modeling tool for pollutant flow, fate, and theorisation; Theoretical approaches to groundwater modelling; Model input variables; and Modeling the vertical flow of contaminants from surface water to aquifers; Recent advances; and Challenges of groundwater pollution modelling. The latter illustrates how contaminants flow are simulated in a saturated aquitard aquifer. Model Type 2 is applied to simulate contaminant flow in a fully splintered formation. Model Type 3 showed the vertical flow of contaminants within an unsaturated zone. The vertical flow of pollutants within an unsaturated region without a recharge is simulated using Model Type 4. Model Type 5 is applied to study gas-phase flow from a point situated within the un-inundated area beneath a confined zone, to the uppermost layer of the superimposed groundwater reservoir and then flow horizontally into the aquifer. Application of these models shows that an initial measurement with traditional, and repeatedly selecting none-site-specific factor. The models are qualitatively harmonious in conjunction with general trends in interpretations and offer a convenient approximation of pollution. However, the execution of these models is limited by a lack of adequate field data. Thus, the model output must be examined within the model uncertainty framework, data input limitations, and methodologically established standards from the literature.

Development of microfluidic droplet shooter and its application to interface for mass spectrometry

Gas/liquid microfluidics has developed for high-efficiency mass transport, mixing and reaction in various applications of chemical analysis and synthesis. However, ejection of uniform liquid droplets floating in gas phase from the microchannels with trajectory control is still challenging. In this study, we developed a method for shooting picoliter droplets in a controlled direction that utilizes microscale gas-phase laminar flows and applied it to a mass spectrometry (MS) interface. The principle of droplet shooting using two-step gas-phase flow focusing was proposed. A microfluidic device with a branched and stepped hydrophobic microchannel was fabricated by top-down glass fabrication technologies. We verified the shooting of droplets of aqueous and organic solvents in the volume range of 3.61–24.9 pL at kilohertz frequencies. A model that considers the capillary force and the drag force was verified to establish a design guideline. Utilizing the developed microfluidic droplet shooter, we demonstrated high-efficiency sample transport to a single quadrupole mass spectrometer. We verified a sample injection rate of approximately 100 % by ejection of picoliter droplets into an MS injection aperture of a 400-μm diameter and achieved detection of caffeine with 3 times higher sensitivity than conventional electrospray ionization interface with sample dispersion.

Optimization of static defoaming structure in gas-liquid separator

ABSTRACT The foam generated in the CO2 flooding-produced fluids causes considerable oil and gas treatment problems, especially in the separation process. The foam in the gas-liquid separator is detrimental to the liquid level control and can also reduce the gas-liquid separating efficiency. To accelerate the defoaming process and increase the gas-liquid separating efficiency, different defoaming structures were evaluated and optimized experimentally within a horizontal separator with a gas-liquid cylindrical cyclone (GLCC) at the inlet. When the gas-phase flow is constant at 2 m3/h and the gas-liquid ratios are 0.4, 0.8, 1.2, 1.6, 2.0, and 2.4, the effects of the type, the quantity of defoaming baffles, and the spacing between defoaming baffles were investigated. The defoaming effect of the perforated folded baffle is better than that of the ordinary baffle and multi-cone baffle, reducing up to 11% of the time. With three defoaming baffles, the foam can be broken by sufficient interception and squeeze, and the defoaming effect is much better than a single baffle or two baffles, reducing up to 8% of the time. The relative increase of the defoaming distance is beneficial to the defoaming. Moreover, the defoaming effect of 120 mm spacing is better than 40 mm and 80 mm spacing, reducing up to 9% of the time.