Separate Gas Research Articles

Transient behavior of the DYNASWIRL® phase separator during cryogenics tank-to-tank transfer operations

In order to separate gas and liquid from a two-phase mixture in space or earth applications, one can generate a strong artificial acceleration field instead of relying on gravity. This can be achieved by generating a swirl flow in a separator. The DYNASWIRL® phase separator is such a passive device, which had been demonstrated in air/water mixtures in the laboratory and on five reduced gravity NASA parabolic flights. In this work, extensive laboratory testing and numerical simulations are conducted to demonstrate the validity of the DYNASWIRL for phase separation with cryogenics. Liquid nitrogen (LN2) is used for extensive testing involving unsteady tank-to-tank transfer with quenching of separator and piping, liquid boil-off and vaporization, phase separation and recovery. This paper describes the separator and testing setups used. It examines the effects of the liquid (water and LN2), geometric parameters, and their effects on the separation and on the pressure loss across the separator, and analyzes the flow dynamics of the gas removal process. Validated numerical simulations support the experimental results and help explain the effects of the design parameters on the results.

Characterising Horizontal Two-Phase Flows Using Structured-Planar Laser-Induced Fluorescence (S-PLIF) Coupled With Simultaneous Two-Phase PIV (S2P-PIV)

Understanding the physics that underpins the behaviors of two-phase flows is immensely useful for a diverse number of industries, including oil and gas, nuclear, and aerospace. Stratified air-liquid two-phase flows are amenable to the application of two-phase PIV, but this is often only possible if PIV processing parameters can be chosen to match the separate gas and liquid phase image sets. Accurate interface location detection is, therefore, extremely important to facilitate appropriate masking during analysis. This paper examines the effectiveness of using the Structured-Planar Laser Induced Fluorescence (S-PLIF) method to aid in the accurate capture and processing of simultaneous two-phase PIV (S2P-PIV) for a gas-sheared liquid flow. Prior S2P-PIV work made use of direct interface detection, using contrast on images from the air-side camera. However, this method proved limiting in higher gas shear cases when the highly wavy nature of the flow prevented the camera from seeing all of the interface. An alternative prior approach using the liquid-side camera and the planar laser-induced fluorescence (PLIF) technique often led to large errors due to reflections from the free surface. Interface detection using the S-PLIF method facilitates a clearer delineation between the two phases through analysis of the change in the structure of the incident light, significantly reducing errors generated by the traditional PLIF. This then facilitates higher quality PIV analysis, both because interface identification is far more accurate and also because frame specific masking of the individual phases can be more automated. This paper presents air/water data from a rectangular channel with a liquid flowrate of 8 litres per minute and superficial gas velocities in the range 1 - 14 m/s. Data capture of the two phases is concurrent with the developed S-PLIF approach used to locate the interface, enabling separate and more accurate PIV analysis of the two phases over a wider parametric range than was previously possible. The data analysis shows that the transition to the disturbance/roll wave regimes is associated with a change in the liquid’s axial velocity profile and a significant increase in normalized axial velocity root-mean-square velocity fluctuation. Data sets from this work can be used to accurately describe high-speed gas-sheared two-phase flows that will be extremely useful for CFD model development and validation.

Gas Lift and Electric Submersible Pump Combination used to Activate a Dead Well

The well-called KD-2 (for confidential reasons) is not producing because the bottom hole pressure of the well is greater than the reservoir pressure. The purpose of this paper is to activate the well KD-2 by the gas lift and electric submersible pump (ESP) with a rotating gas separator combination in order to increase its production. The completion and the pressure, volume, and temperature (PVT) data are processed under Pipesim and by integrating a certain number of calculations by the nodal analysis and the decline curve methods. The results obtained show that well KD-2 activated by the gas lift provides a flow rate of 3038.019 STB/day. In order to increase the flow rate of well KD-2 activated by the gas lift, the ESP with rotating gas separator is added and the flow rate becomes 4845.325 STB/day which represents a gain of 59.48% in flow rate. In addition, the gas lift and ESP with rotating gas separator combination guarantees an eight-year operating period for a probability of $ 3,601,197 with a return on investment of 2 months. The gas lift and ESP with rotating gas separator gas combination can be used to optimize the production of low-flow wells in the same geographical areas and to consider the reactivation of dead wells.

Odors Detection and Recognition Based on Intelligent E-Nose

Electronic noses have become more common as a result of developments in sensor technology, machine learning (ML), and Artificial Intelligence (AI). At the moment, the majority of e-nose research is conducted in laboratories; access from other locations is not possible with e-nose. Very few real-time smell detection applications, including tiny drones equipped with commercial gas sensors or biosensors made of insect antennas, have been created. The scope of this work is to design an intelligent E-Nose for odors detection. Smell Inspector developer kit has been used to get measurements. The Smell Inspector consists of sensors for temperature and humidity in addition to four smell iX16 chips. The Smell Inspector creates digital fragrance fingerprints using a variety of separate gas detectors. The approach for object recognition and classification using artificial intelligence techniques is presented in this paper. These techniques include Machine Learning (ML), clustering, and regression algorithms. Using the K-Nearest Neighbor (KNN) algorithm, the experimental results' array sensors were able to recognize; clean air, onion, garlic, coffee, spices, lemon, vinegar, gasoline, petrol, diesel, and perfumes with 78% accuracy rate.

Electrochemical Gas Separations for Green Energy Integration

Separation and purification of molecules and compounds is one of the fundamental processes of chemistry and a hugely important factor in industrialization, accounting for as much as 15% of world’s energy consumption. As the world tries to limit and reduce the effects of climate change, simultaneous development of a green chemical economy and carbon sequestration strategies are needed. Both these goals need to effectively and efficiently separate gas phase molecules to make the implementation of these technologies feasible, requiring an even higher demand for economical and green gas phase separation. The current methods of gas phase separation used in industry rely predominantly on inefficient processes, such as cryogenic distillation or temperature or pressure swing absorption. Gas phase separation by electrochemical means can offer theoretically high energy efficiency separation, as the energy supplied can operate exclusively on the molecule of interest, if proper material and design criteria are met, while traditional methods act upon the entire gas mixture. Additionally, electrochemical separations can reduce the number of steps needed as they can simultaneously separate and compress the purified gas, easing the demand for high energy processing required when using mechanical pumps. However, the effectiveness of these technologies depends largely on the operating conditions and materials that make up the electrochemical cell. Thus, a key factor driving improvement in this field relies heavily on material development, such as improved membranes/separators, catalysts, and other cell materials which can in turn give rise to novel techniques and high performance of the electrochemically driven devices. Electrochemical gas phase separations integrated with green energy are critical to reaching climate change targets, but they in turn rely on the development of novel materials at enlarged scales and implementation of these technologies at reduced costs. In this article, we discuss the principles and applications of three electrochemical gas separations: hydrogen (H2) pump, ammonia (NH3)compression, and carbon dioxide (CO2) separation.

Unmanned Helicopter Airborne Fourier Transform Infrared Spectrometer Remote Sensing System for Hazardous Vapors Detection

The rapid development of unmanned aerial vehicles (UAVs) provides a new application mode for gas remote sensing. Compared with fixed observation and vehicle-mounted platforms, a Fourier transform infrared spectrometer (FTIR) integrated in the UAV can monitor chemical gases across a large area, can collect data from multiple angles in three-dimensional space, and can operate in contaminated or hazardous environments. The unmanned helicopter has a larger payload and longer endurance than the rotary-wing drone, which relaxes the weight, size and power consumption limitations of the spectrometer. A FTIR remote sensing system integrated in an unmanned helicopter was developed. In order to solve the data acquisition and analysis problem caused by vibration and attitude instability of the unmanned helicopter, a dual-channel parallel oscillating mirror was designed to improve the stability of the interferometer module, and a robust principal component analysis algorithm based on kernel function was used to separate background spectrum and gas features. The flight experiment of sulfur hexafluoride gas detection was carried out. The results show that the system operates stably and can collect and identify the target spectrum in real time under the motion and hovering modes of an unmanned helicopter, which has broad application prospects.

Analysis of the Influence of Gas Leakage in The Dipleg of Cyclone Separators on Particle Properties

The FCC unit uses a cyclone separator for gas-solid separation of catalysts from flue gas or oil and gas. When the cyclone separator experiences a gas leakage fault, it directly affects its separation performance, causing excessive catalyst emissions and leading to the occurrence of catalyst running faults. However, there is currently a lack of diagnostic technology for cyclone separator equipment malfunction and gas leakage. Therefore, the influence of the dipleg of the cyclone separator on the particle loss rate under different gas leakage velocities was investigated experimentally. Experiments show that under normal conditions, particles are subject to multiple cycle separation, and fewer particles randomly enter the riser with the upward rotating flow to escape, which is mainly determined by the structure size and inlet velocity of the cyclone separator. When gas leakage occurs in the dipleg, the higher the gas leakage velocity, the higher the particle loss rate. As the number of particle cycles increases, the loss rate gradually decreases. For this purpose, the cyclone separator inside the FCC unit in the industrial site is taken as the object. In response to multiple cyclone separator loss faults, the changes in process parameters and collected catalyst particle properties of the cyclone separator are analyzed, and the changes in the running dose inside the device during operation are analyzed. Based on the analysis results, the operation of the unit is optimized and adjusted to avoid unplanned shutdown and maintenance. Therefore, based on this, a fault diagnosis technology for catalyst loss in FCC unit cyclone separators based on particle property parameters has been created, which has the characteristics of accuracy and reliability and can be applied to the analysis and diagnosis of catalyst loss faults in FCC unit.

(Invited) Understanding PEMFC by Advanced Electron Microscopy

A thorough knowledge of the atomic structure and composition of catalyst nanoparticles is paramount to the development of advanced materials for proton exchange membrane fuel cells (PEMFC), one of the most promising energy conversion devices for automotive and stationary applications. Pt and Pt-based alloys nanoparticles (NPs) are currently used as the catalyst to promote the kinetics of the hydrogen oxidation and oxygen reduction reactions in the anode and cathode of the fuel cell, respectively. Yet, the durability of the catalysts remains a major issue for their commercialization. In addition, it is essential to characterize the ionomer distribution and coverage over the catalyst NPs and the carbon support, as the ionomer/catalyst interface plays a critical role in the ORR and MEA fuel cell performance.Ideally, voltage cycling of the membrane electrode assemblies would be performed in-situ within a TEM, but these experiments are highly challenging, since separate gas phase reactants need to be present simultaneously, in particular hydrogen and oxygen Instead, a very close approximation to a true in-situ experiment is done via potential cycling in a half-cell in the presence of liquid electrolyte, as opposed to solid electrolyte in a single cell. This allows us to observe the exact same location before and after cycling through a technique called identical location TEM/STEM (IL-TEM/STEM). Under these conditions, various electron microscopy techniques, such as bright-field TEM and HAADF STEM coupled with EDS and EELS can be performed. To better acquire and understand TEM/STEM-based experimental images, in particular the selection of appropriate operating conditions, and interpretation/validation of the results, it is critical to perform multislice TEM/STEM image simulations to calculate the interaction of an electron beam with a material system.In this talk, the focus is to understand the behavior of Pt and Pt-alloy NPs during the various stages of fuel cell cycling. For this purpose a set-up was developed to simulate the effect of voltage cycling on the cathode side of the fuel cell. In this set up, catalyst NPs supported on carbon nanotubes and amorphous carbon were observed by advanced transmission electron microscopy, before and after cycling. In particular, we studied Pt and Pt-alloy NPs and carbon support degradation mechanisms as a function of cycling using for the first time a combination of 2D IL TEM and 3D IL TEM. This new approach reveals many unpredictable features of morphology changes/behavior of Pt NPs and carbon support, after experiencing the long durability test. These new findings provide an insight which great surpasses what have been observed using solely 2D IL TEM.The experiments show particle migration in conjunction with carbon corrosion during the initial cycles, whereas the appearance of single atoms and atomic clusters on the surface of the carbon support appear after additional voltage cycling as a result of surface dissolution of NPs. For the case of alloyed NPs, the experiments show a heterogeneous deposition of Pt on the NPs. Moreover, we demonstrate a novel approach to distinguish the ionomer phase from the carbon support in PEMFCs, by employing the carbon signal in STEM-EELS, using two types of detectors. In this fashion, not only the ionomer, but also the carbon support, can be mapped in high spatial resolution, despite some damage caused by the electron beam.

The hydrocarbon source potential of Permo-Triassic rocks of the Indochina Block adjacent to the Paleo-Tethys suture in Thailand

The main Thailand petroleum systems are found in the syn-rift and post rift sections of Cenozoic rift basins. The Khorat Plateau area is a separate gas province with Permian limestone reservoirs possibly sourced from Triassic lacustrine, and Permo-Carboniferous marine shales. However, these source rocks and those of equivalent age west of the Khorat Plateau are not well described in the literature. This study investigated the source potential of outcropping Permo-Triassic shales from the western margin of the Khorat Plateau and the Khao Khwang Fold and Thrust Belt (KKFTB). The key formations sampled are: Permian: Alum Shale, Nong Pong, Sap Bon, Khao Khad, and Nam Duk formations; Triassic: Pang Asok and Hua Hin Lat Formation. Most potential Permo-Triassic source rocks sampled exhibited little potential due to the dominance of Type IV, non fluorescent amorphous, vitrinite and intertinite mascerals and low <1 % TOC content. Probably the Type IV kerogens are not original, but the product of subsurface alteration of other kerogen types (most likely Type III). The complex burial histories of the formations indicates such alteration could have occurred post-maturation. Probably maximum burial in the KKFTB was attained during the Triassic Indosinian Orogeny when upper diagenetic to anchizone conditions were attained. Significant burial also occurred when the Jurassic-Cretaceous Khorat Group (>2 km thick) was deposited. This later burial could be responsible for later maturation in areas north of the KKFTB. Simply in terms of TOC content >1, the Hua Hin Lat and Khao Khad formations have the most promising source potential.

Tiny Windows in Reticular Nanomaterials for Molecular Sieving Gas Separation Membranes

AbstractThe current state of reticular chemistry enables the synthesis of a wide range of highly porous nanomaterials for gas separation, including metal‐organic frameworks (MOFs), covalent organic frameworks (COFs), porous organic cages (POCs), metal‐organic cages (MOCs), and polyhedra (MOPs). This perspective focuses on membrane technology, a key player in energy‐efficient gas separations. It explores the world of reticular materials, taking a glance at tiny pore windows with narrow openings, which are ideal for high‐resolution molecular sieving, and how to design them. Promising concepts in this field are membranes consisting of neat materials, but also mixed matrix membranes, where polymeric films incorporate reticular fillers, creating cost‐efficient membranes. This article sheds light on the potential use of reticular materials as membrane components. The reticular synthesis of MOFs offers the ability to separate gas molecules with minimal size differences effectively. For COFs, the crucial factor lies in reducing their pore size, preferably through functional group modifications. Porous cage compounds can achieve fine distribution from homogeneous dispersions into polymers making them excellent candidates for mixed matrix membranes. This perspective provides strategies and guiding principles for the future of reticular nanomaterials‐based membranes, addressing the pressing need for advanced and efficient separation technologies.

Investigation of the Effect of Side Arm Orientation of the T-Junction on Gas–Liquid Stratified Flow

T-junctions are important structures used in a number of industries to separate gas and liquid. This work studied the effect of the orientation of the side arm on the separation efficiency using a computational fluid dynamics (CFD) approach, and a new mechanical model is developed based on force analysis to predict the liquid carryout threshold. Laboratory experiments from published works are used to verify the CFD simulation and the new model. In this work, the angle of the side arm to the horizontal plane, α, and the angle of the side arm to the main arm’s axial direction, β, are investigated. The results show that with increasing β, the liquid carryover threshold increases accordingly, demonstrating that the liquid can be more easily carried to the side arm, while the liquid-carrying performance in the side arm is not sensitive to the inclination angle, β. Hence, in the new model, the inclination angle of is ignored. Experimental data are collected to validate the new model. The results show that this model can accurately predict the liquid carryover threshold, and the relative error is 4.16%.

Effect of Gas Injection on the Enhancement of Condensate Recovery in a Gas Condensate Reservoir

So far, many methods have been used to increase production from gas condensate reservoirs, but in general, all these methods can be placed in two groups:1) Methods of maintaining pressure or preventing pressure drop; 2) Creating chemical changes in reservoir fluids to improve production mechanisms due to capillary forces.Also, many of the methods used have realized both of the above purposes and at the same time while maintaining the reservoir pressure (or preventing pressure drop) also change the chemical physical properties of the reservoir. One of these methods is gas injection. What causes severe changes in the performance of condensate gas reservoirs as soon as the pressure reaches the dew point pressure is the change of the reservoir fluid from a single-phase gas state to a two-phase gas condensate state. In order to accurately study the fluid behavior of one of condensed gas reservoirs, the reservoir fluid was simulated by software, four samples of nitrogen gas, carbon dioxide, methane and separator gas, were injected into the reservoir and then the effect of changing injection rate, injection pressure and injection duration on gas condensate recovery has been investigated by these injection gases.

Liquid Water Permeability in a Hydrophobic Microporous Layer for the Anode Interdigitated Flow Field of a Gas-Liquid Separating Polymer Electrolyte Membrane Water Electrolyzer

A novel interdigitated flow field for polymer electrolyte membrane water electrolyzers composed of oxygen exhaust channels apart from liquid water feed channels has been developed for ground and space applications. This design can internally separate oxygen gas and liquid water between the flow channels, dispensing with water circulators for bubble removal and external separators with natural or centrifugal buoyancy. In this electrolyzer, pressurized liquid water is injected in the in-plane direction from the water channels to the catalyst layer through the hydrophobic microporous layer (MPL) of the anode porous transport layer. The produced oxygen gas is discharged in the through-plane direction of the MPL, taking advantage of the capillary pressure in the MPL. This study conducted liquid water permeability tests on the MPL with pressurized water. We find gradual permeability decreases with time for different liquid water pressures. The permeability will be a useful parameter for the optimal structural designs of this electrolyzer.

Two-stage bubble point pressure: A newly found feature of Dutch Twill weave porous screen

The porous screen is a vital material in the area of in-orbit propellant management, due to its efficient performance to separate gas and liquid in microgravity conditions. Among the diversities of screens, the Dutch Twill weave (DTW) screen is the most commonly used owing to its extensive adaptability of different fluids including storable and cryogenic propellants. This study focuses on the bubble point pressure (BPP), a quite important characteristic parameter of the screen applied to gas-liquid separation. It has been commonly considered by previous researchers that BPP for a given working fluid and fixed screen structure has a certain value. However, the two-stage-bubble-point pressure phenomenon that was newly found in an experiment reveals three new parameters of DTW screens: the first order BPP, the second order BPP, and the critical depressurizing level. After a bubble breakthrough occurs, only if the driving pressure is decreased to under the critical depressurizing level, can the screen be fully resealed; otherwise, the screen can be just partially resealed. For the pressurization beginning at the fully resealed state, the critical value of the driving pressure to trigger a bubble breakthrough is the first order BPP; but for the pressurization beginning at the partially resealed state, the critical value becomes the second order BPP. To understand this phenomenon, we analyzed the microstructure of DTW screens and then reconstructed the conceptual model of screen pore, according to the distribution mode of pore diameter. The new model explain the phenomenon by introducing three special character parameters: the first order BPP, the second order BPP, and the critical depressurizing level, which are corresponding to the locations of the first throat, the second throat, and the abdomen in a pore passage, respectively. The detailed mechanism was quantitatively illustrated by a CFD simulation. The discovery of this feature of DTW screens should be a meaningful reminder that after bubble breakthrough occurs, only when the driving pressure is decreased to below the critical depressurizing level, can the original performance of screen be recovered fully.

Dynamic and Steady-State Simulation Study for the Stabilization of Natural Gas Condensate and CO2 Removal through Heating and Pressure Reduction

Stabilization of condensate is a highly energy-consuming process compared to other oil and gas processes. There is a need to reduce this energy consumption. Therefore, the present work aims to simulate the stabilization unit in terms of available energy and on-spec stabilized condensate products. Natural gas condensate liquids (NGL) need to be stabilized by eliminating lighter hydrocarbon gases and acid gases before being sent to the refinery. Stabilized NGL has the vapor pressure determined as a Reid vapor pressure of 7 psia, showing that light components did not evolve as a separate gas phase. Stabilization and CO2 removal was performed through the distillation method by heating and pressure reduction using steady state and dynamic simulation through Aspen HYSYS. Different process alterations around the exchanger and column have been studied based on the utilities available for the stabilization and CO2 removal process. Sensitivity studies, including the impact of CO2 concentration, the temperature at the inlet of the stabilizer flash separator, and the dynamic simulation for the PID controller, have been performed to analyze the impact on the process parameters, such as Reid vapor pressure (RVP) and CO2 of the rundown air cooler and heat duties of the exchangers. Actual plant data have been used for the validation of process simulation values for the accuracy of the condensate stabilization unit model. Based on the scenarios analyzed, it can be concluded that the nitrogen stripping method achieved 7 ppmv CO2 and 7 psia RVP in the condensate from the cooler outlet, while a variation of 29 bpd was observed for the stabilized condensate flowrate throughout all scenarios with data validation showing 0.24% discrepancy between Aspen Hysys data and actual plant data.

Silver-Based Supportless Membrane Electrode Assemblies for Electrochemical CO2 Reduction

CO2 is one of the major contributors to the emission of greenhouse gases boosting climate change. Meanwhile, renewable energy production is fluctuating due to weather conditions, demanding for appropriate storage, e. g. by Power-to-X technology. The first step of these processes, the production of hydrogen via water electrolysis, is typically linked to a second step to obtain hydrocarbons [1]. Meanwhile, electrochemical CO2 reduction (eCO2R) is capable of generating chemical feedstocks by converting excess CO2, simultaneously using renewable energy sources during peak times. A promising pathway of eCO2R focuses on CO, as it can be produced with high selectivity at silver catalysts, concurrently generating hydrogen as the only byproduct [2]. To partly overcome the mass transport limitations resulting from the very limited solubility of CO2 in aqueous electrolytes, gas diffusion electrodes (GDEs) are typically used for eCO2R in a three-chamber setup with anolyte, catholyte and separate gas compartment [3].However, there are still considerable overpotentials in this setup, among others caused by ohmic losses such as the electrolyte resistance. Employing membrane electrode assemblies (MEAs), either both electrodes or one of them can be combined with the membrane to form a full- or half-MEA, respectively, resulting in a significant decrease in cell voltage. Although there have already been studies on the fabrication of MEAs employing silver catalysts for eCO2R [4, 5], they are still very limited in options and mostly based on carbon gas diffusion layers (GDLs).The manufacturing approach applied in this work is based on a catalyst ink recipe for sintered silver GDEs originally developed for chlor-alkali electrolysis by Moussallem et al. [6]. Instead of using Nickel mesh as a substrate, the suspension is spray-coated on a stainless steel plate to enable the required treatment at temperatures above 300 °C. Afterwards, the catalyst layer is hot-pressed on the prepared anion exchange membrane at more moderate temperatures, forming a supportless cathodic half-MEA.Resulting from variations in the manufacturing procedure, different MEAs are electrochemically characterized, examining Faradaic efficiencies as well as cell voltages, also in comparison to measurements performed in three-chamber setup. Addressing challenges in product efficiency and membrane degradation, it is shown that this type of MEA is capable of eCO2R to CO, already reducing the cell potential at elevated current densities by nearly 50 %, see fig. 1.[1] Tom Kober et al. Report: perspectives of power-to-X technologies in Switzerland: supplementary report to the white paper. en. Technical report. 2019. doi: 10.3929/ETHZ-B-000525806.[2] Yoshio Hori et al. “Electrocatalytic process of CO selectivity in electrochemical reduction of CO2 at metal electrodes in aqueous media”. Electrochimica Acta, 39 (11-12), (1994), 1833–1839.[3] Thomas Burdyny and Wilson A. Smith. “CO2 reduction on gas-diffusion electrodes and why catalytic performance must be assessed at commercially-relevant conditions”. Energy & Environmental Science, 12 (5), (2019), 1442–1453. doi: 10.1039/C8EE03134G.[4] Zengcai Liu et al. “CO2 electrolysis to CO and O2 at high selectivity, stability and efficiency using Sustainion membranes”. Journal of The Electrochemical Society, 165 (15), (2018), J3371–J3377. doi: 10.1149/2.0501815jes.[5] Jonghyeok Lee et al. “Electrochemical CO2 reduction using alkaline membrane electrode assembly on various metal electrodes”. Journal of CO2 Utilization, 31 (2019), 244–250. doi: 10.1016/j.jcou.2019.03.022.[6] Imad Moussallem et al. “Development of high-performance silver-based gas-diffusion electrodes for chlor-alkali electrolysis with oxygen depolarized cathodes”. Chemical Engineering and Processing: Process Intensification, 52 (2012), 125–131. doi: 10.1016/j.cep.2011.11.003. Figure 1

Experimental demonstration of high-temperature (>1000 °C) heat extraction from a moving-bed oxidation reactor for thermochemical energy storage

Previously developed reduction-oxidation (redox) thermochemical energy storage technologies must store their products at high temperatures, complicating handling and transportation. This work describes a countercurrent, tubular, moving bed oxidation reactor at laboratory scale that produces high grade heat and allows solids to enter and exit the system at ambient temperatures. The particles implemented in the system consist of a novel magnesium‑manganese-oxide material well-suited for thermochemical energy storage. Output heat is obtained via a separate extraction gas flow, which exits from the middle portion of the main reactor tube. With this design, reactor temperatures in excess of 1000 °C and extraction temperatures above 950 °C were achieved. Deviation between the two measurements is a result of extraction thermocouple placement and losses in the reactor extraction arm; improvements to these parameters would bring the extraction temperature closer to the bed temperature. The reactor produces enough energy via oxidation to sustain both heat extraction and continued chemical reaction. During one representative steady state experiment at a particle flow rate of 1.5 g/s, an average of 447 W was extracted from the reactor out of an estimated 1083 W of released chemical energy for a duration of 70 min. Among the four experiments, the maximum bench-scale oxidation reactor energy efficiency of 36.2% and corresponding round-trip efficiency of 13.7% considering both redox reactors were demonstrated. Characteristics of an ideal system are considered and future improvements are proposed.

Effects of MWCNTs on O2/N2 separation performance and morphology of sPEEK/PEI composite membranes: Experimental and molecular dynamics simulation studies

This study involved the development of blend membranes using sulfonated poly (ether ether ketone) (sPEEK) and poly (etherimide) (PEI) with varying amounts of multi-wall carbon nanotubes (MWCNTs) (up to 2 % by weight). The gas separation performance of these membranes was evaluated for the separation of O2 and N2 gases. In order to achieve a degree of sulfonation of 70 %, PEEK was sulfonated directly. The manufactured membranes were characterized using X-ray diffraction (XRD), scanning field emission electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FTIR). Their operational evaluation was performed through permeability tests for pure gases of O2 and N2. The effect of sPEEK/PEI composition on membrane selectivity and gas permeability in the blend was studied. The selectivity and gas permeability values varied between those of individual polymers, fluctuating systematically with sPEEK/PEI content variation in the blends. The addition of MWCNTs to the blend improved the selectivity and permeability of O2 and N2 simultaneously. To further investigate the potential industrial application and stability of these membranes, experiments were conducted under different feed pressures (2 to 8 bar). The membrane containing 1 % of MWCNTs showed the best performance for O2 gas. Molecular dynamics simulations (MDS) were performed using the COMPASS force field to estimate the diffusivity of O2 and N2 gases through selected membrane systems. The simulated results agreed well with the available experimental data. With compared to the reported separating data, the prepared nanocomposite membrane was greatly efficient, which makes it promising platform to separate mixed gas flows and other related environmental processes.

Process Simulation and Optimization of Fluid Catalytic Cracking Unit’s Rich Gas Compression System and Absorption Stabilization System

In a fuel-based refinery, rich gas in the fluid catalytic cracking (FCC) unit is further processed to separate dry gas and refinery products (i.e., stabilized gasoline and liquified petroleum gas). The process is utility-intensive and costly and includes a two-stage compressor, pumps, an absorber, a stripper, a stabilizer, and a re-absorber. The optimization was conducted with respect to the compressor outlet pressure from the gas compression system (GCS) and the flow rate of absorbent and supplementary absorbent from the Absorption-stabilization System (ASS) using the process simulation software Aspen Plus. Compared to the base case of a 725 kt/a rich gas FCC unit, a refinery can save 2.42% of utility costs under optimal operation. Through optimized operation, medium-pressure steam consumption has been reduced by 2.4% compared to the base case, resulting in a significant improvement in total operational cost. The optimization strategy can provide insightful guidance for the practical operation of GCS and ASS.

Evolution of LIBS technology to mobile instrumentation for expediting firearm-related investigations at the laboratory and the crime scene

Gunshot residue (GSR) is one of the few forensic disciplines that lack accurate screening techniques. This study proposes using a mobile LIBS instrument to detect inorganic GSR and compares performance to a previously validated laboratory instrument. The mobile LIBS is designed with advanced configurations specifically for on-site GSR analysis, including a CMOS detector and a sampling chamber that holds up to six typical GSR collection devices with separate gas flow ports to prevent cross-contamination. A significant novelty of the portable instrument is its image magnification, which allows quick searching and visualization of GSR particle morphology. The single-particle imaging and elemental composition capability is one of a kind and offers superior confirmatory features for GSR. The mobile LIBS performance was evaluated for residues collected from the hands of shooters (100 samples) and non-shooters (200 background samples), analyzed sequentially by the mobile instrument and then the laboratory instrument. Accuracies better than 98.8% were obtained by both instruments, demonstrating their suitability for trace IGSR detection from skin specimens. Implementation of this methodology is anticipated to drastically speed up response times (i.e., from several hours per sample by standard SEM-EDS practice to a few minutes by LIBS). The screening methods can be easily incorporated into workflows to improve decision-making processes at the crime scene and laboratory settings, reduce backlogs, and improve case management.