Gas Feed Rate Research Articles

Optimal design and operation for simultaneous shale gas NGL recovery and LNG re-gasification under uncertainties

Both shale gas and liquefied natural gas (LNG) contain certain amounts of C2+ hydrocarbons (NGL), which might profitably be recovered. To accomplish this, the shale gas stream needs cold energy to chill down and scrub NGL; while the LNG stream needs hot energy to evaporate and separate from NGL. Thus, integrating both processes of shale gas processing and LNG re-gasification, so as to utilize cold energy from LNG re-gasification process to assist the NGL recovery, has potentially significant benefits on both energy savings and high-value product productions. In this paper, a new methodology to guide the conceptual design and operation for such a process synthesis has been developed, where the uncertainty of shale gas feed rate changes has been considered. The methodology includes four steps of work: superstructure development and data preparation, synthesis model development and solution identification, heat exchanger network design, and final process validation via rigorous simulations. Compared with the recent study of Wang et al. (2013), the paper has two major contributions: (1) a new MILP model with more precise process presentations; and (2) process synthesis with consideration of the uncertainty of shale gas feed rate, which enhanced future operational flexibility of the conceptual design.

Hydrogen Production in a Sorption-Enhanced Fluidized-Bed Membrane Reactor: Operating Parameter Investigation

Sorption-enhanced steam reforming, assisted by membrane separation of H2 in a fluidized bed reactor, is simulated numerically based on a kinetic two-phase model. A residence time distribution function method is implemented to account for CO2 capture in continuous operation. The effects of operating pressure, total gas feed rate, solid recycle rate, fresh sorbent feed rate, effective membrane area, and permeate pressure on the performance of a continuous fluidized bed reactor are investigated. A CH4 conversion of >91% for operation at 0.6 MPa and 550 °C is predicted to be possible with the assistance of the sorbent and membranes. The reforming performance is very sensitive to the effective surface area of membranes. A sorbent fraction of >0.7 (by mass) is necessary to achieve a product with H2 selectivity of >98%, free of CO and CO2, for realistic membrane effectiveness factors. Adding fresh sorbent or increasing the sorbent mass fraction improves the H2 productivity for a moderate solids recycling rate. Effective CO2 capture rate depends greatly on the sorbent feed rate.

Weldability of the superalloys Haynes 188 and Hastelloy X by Nd:YAG

The requirements for welded aircraft parts have become increasingly severe, especially in terms of the reproducibility of the geometry and metallurgical grade of the weld bead. Laser welding is a viable method of assembly to meet these new demands, because of automation, to replace the manual TIG welding process. The purpose of this study is to determine the weldability of Hastelloy X and Haynes 188 alloys by the butt welding process with a Nd:YAG laser. To identify the influential parameters of the welding process (laser power, feed rate, focal diameter and flow of gas) while streamlining testing, an experimental design was established with the CORICO software using the graphic correlation method. The position of the focal point was fixed at 1/3 of the thickness of the sheet. The gas flow rate and the power of the beam have a major effect on the mechanical properties and geometry of the weld. The strength of the weld is comparable to that of the base metal. However, there is a significant decrease in the elongation at break of approximately 30%. The first observations of the cross section of the weld by scanning electron microscopy coupled with EBSD analysis show a molten zone presenting dendritic large grains compared to the equiaxed grains of the base metals without a heat affected zone.

Demonstration of a Concentrated Potassium Carbonate Process for CO2 Capture

A precipitating potassium carbonate (K2CO3)-based solvent absorption process has been developed by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) for capturing carbon dioxide (CO2) from industrial sources, such as power plant flue gases. Demonstration of this process is underway using both a laboratory-based pilot plant located at The University of Melbourne and an industrial pilot plant located at the Hazelwood Power Station in Victoria, Australia. The laboratory-scale pilot plant has been designed to capture 4–10 kg/h CO2 from an air/CO2 feed gas rate of 30–55 kg/h. The power-station-based pilot plant has been designed to capture up to 1 tonne/day CO2 from the flue gas of a brown-coal-fired power station. In this paper, results from trials using concentrated potassium carbonate (20–40 wt %) solvent are presented for both pilot plants. Performance data (including pressure drop, holdup, solvent loadings, temperature profile, and CO2 removal efficiency) have been collected from ea...

Coal combustion under Calcium Looping Process conditions

Coal of three kinds was burned in an oxygen-enriched atmosphere using a twin-fluidized bed solid circulation system under conditions of the Calcium Looping Process. This twin-fluidized bed system comprised a fast bed regenerator (calciner), into which fuel and oxygen-enriched gas were fed, and a bubbling bed absorber (carbonator), into which air was fed. Inert quartz sand was used as the bed material to evaluate the coal combustion behavior, including char transportation from regenerator to absorber and formation of CO and CO2 there. First, the circulation rate and the residence time of solids in the regenerator (calciner) were measured to determine the suitable operation conditions. The effect of gas feed staging to the regenerator on the solid residence time was evaluated. By reducing the ratio of the primary gas feed rate to total gas feed rate to 0.5, average solid residence time of about 40s was attained. Under this gas-feed condition, coal combustion experiments were conducted. Effects of volatile matter content of coal on CO and CO2 formation in the absorber and NOx emissions from the regenerator were investigated. High-volatile matter coal was found to be favorable to reduce CO and CO2 formation in the absorber, but conversion of the fuel-N to NOx of high-volatile matter coal was higher than that from low-volatile coal.

Nonequilibrium Atmospheric Pressure Forward-Vortex Plasma System for Generation of Reactive Species in Flowing Water for Medical Applications

Recent research in plasma applications in bioengineering and plasma medicine gives attention to plasma treatment of various liquids, especially water, for the growing number of medical and biological applications. In this paper we present a forward-vortex nonequilibrium atmospheric pressure plasma system for generation of nitrogen and oxygen reactive species as well as reduced pH in flowing water. We discuss the dependence of pH and nitrate produced in water on both the carrier gas and the gas feed rate.

Influence of Spraying Parameters on the Microstructure and Properties of Plasma-sprayed Al2O3/40%TiO2 Coating

Abstract In this paper, the influences of parameters such as spraying voltage, spraying current, primary gas feed rate and spraying distance on the properties of plasma-sprayed Al2O3-40 wt.%TiO2 composite ceramic coating were studied by using orthogonal experimental design. The influence sequences of the parameters on the properties of plasma-sprayed Al2O3-40 wt.%TiO2 coating are: spraying distance, spraying voltage, spraying current, argon gas flow rate. The optimum parameters were determined: spraying distance 100 mm, spraying current 440 A, spraying voltage 120 V, and argon gas flow rate 3.0 m3/h. Scanning electronic microscope was used to observe the surface and cross-section morphologies of the Al2O3-40 wt.%TiO2 coating prepared by using the optimum parameters. The phase structure was analyzed by X ray diffraction. The through-thickness microhardness was measured by microhardness instrument. The bonding strength between the coating and substrate was determined by dual tensile test method. The porosity was measured by image analysis method. The results showed that the plasma-sprayed Al2O3-40 wt.%TiO2 composite ceramic coating has a dense structure with the porosity of 1.5%. In addition, the coating has typical layered structure. Al2O3-rich area and TiO2-rich area exhibiting different colors have homogeneous distribution and good combination. Due to the function of NiAl/AlSi bond coating, the bonding strength between the Al2O3- 40 wt.% TiO2 coating and substrate reaches 45 MPa. The coating is mainly composed of γ-Al2O3 metastable phase, α-Al2O3 stable phase, Ti8O15 and Al2TiO5.

Light Tar Decomposition of Product Pyrolysis Gas from Sewage Sludge in a Gliding Arc Plasma Reformer

Pyrolysis/gasification technology utilizes an energy conversion technique from various waste resources, such as biomass, solid waste, sewage sludge, and etc. to generating a syngas (synthesis gas). However, one of the major problems for the pyrolysis gasification is the presence of tar in the product gas. The tar produced might cause damages and operating problems on the facility. In this study, a gliding arc plasma reformer was developed to solve the previously acknowledged issues. An experiment was conducted using surrogate benzene and naphthalene, which are generated during the pyrolysis and/or gasification, as the representative tar substance. To identify the characteristics of the influential parameters of tar decomposition, tests were performed on the steam feed amount (steam/carbon ratio), input discharge power (specific energy input, SEI), total feed gas amount and the input tar concentration. In benzene, the optimal operating conditions of the gliding arc plasma 2 in steam to carbon (S/C) ratio, 0.98 kWh/m3 in SEI, 14 L/min in total gas feed rate and 3.6% in benzene concentration. In naphthalene, 2.5 in S/C ratio, 1 kWh/m 3 in SEI, 18.4 L/min in total gas feed rate and 1% in naphtha- lene concentration. The benzene decomposition efficiency was 95% , and the energy efficiency was 120 g/kWh. The naphthalene decom- position efficiency was 79% , and the energy yield was 68 g/kWh.

Decomposition of benzene as a surrogate tar in a gliding Arc plasma

The pyrolysis and gasification technology uses diverse waste resources, including biomass, urban solid waste, and sewage sludge, to produce synthetic gases for industrial use. The tar in the thermal decomposition gas from the pyrolysis and/or gasification process, however, damages synthetic gas facilities and causes operation trouble. In this study, a gliding‐arc plasma reformer for tar decomposition was developed to address the aforementioned problem. In addition, experiments were performed on the variables that affect the tar removal efficiency, and the optimal operation condition was presented. The experimental variables included the steam flow rate, input benzene concentration, total gas feed rate, specific energy input (SEI), gas nozzle diameter, electrode length, electrode gap, and electrode shape. With the increase in the total gas feed rate, the benzene decomposition efficiency slightly decreased, and with the increase in the SEI, the energy efficiency increased. In the stable plasma discharge condition, a smaller nozzle diameter, a longer electrode gap, and a longer electrode length led to better decomposition and energy efficiencies. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 837–845, 2013

Removal characteristics of tar benzene using the externally oscillated plasma reformer

To destruct tar from pyrolysis and/or gasification, an externally oscillated gliding arc plasma reformer (EOPR) was designed and verified its decomposition performance. The external oscillation device can give to expand the discharge area of the gliding arc plasma reformer. An experiment was conducted using surrogate benzene, which is generated during the pyrolysis and/or gasification, as the representative tar substance.To identify the characteristics of the influential parameters of tar decomposition, tests were performed on the oscillation frequency and amplitude, steam feed rate, and total gas feed rate.The optimal operating conditions of the EOPR were 267Hz in oscillation frequency, 3Vpp in oscillation amplitude, 0.66L/min in steam feed rate, 0.12% in benzene concentration, 16.7L/min in total gas feed rate, and 0.17kWh/m3 in SEI (specific energy input). The benzene decomposition efficiency was 90.7%, and the energy yield was 22.95g/kWh. Without oscillation, the decomposition efficiency was 82.6%, and the energy yield was 20.9g/kWh, both of which were 8.9% lower than those with the external oscillation. Tar benzene was decomposed into light gases (H2, CO, and CO2), hydrocarbons (CH4, C2H4, and C2H6) and carbon block.

Kinetic model of K–Ni/α-Al2O3 catalyst for oxidative reforming of methane determined by genetic algorithm

Effects of preparation conditions of a K–Ni/α-Al2O3 catalyst on the activity and selectivity of high-pressure reforming of methane was investigated. Catalyst preparation parameters such as calcination temperature of boehmite, the amount of NiO and the amount of K loading were designed by L9 orthogonal array, and the catalysts were prepared by an impregnation method. Each catalyst was used in an activity test where contact time was decreased by increasing the gas feed rate, and conversion was recorded until O2 conversion was below 30%. Both the conversions and syngas selectivity were used for fitting by Genetic algorithm. The algorithm was applied to determine the kinetic parameters of the reaction network of high-pressure reforming of methane. Then a support vector machine was trained using the nine dataset to correlate the catalyst preparation parameters and the kinetic parameters. After the training, we conducted grid searches to build response surfaces of the kinetic parameters. Thus, the all kinetic rate constants could be predicted as functions of the catalyst preparation conditions. The analysis of the kinetic model suggested that successive oxidation of the syngas was the most influential factor for low syngas selectivity. Whereas the amount of NiO loading influences on hydrogen oxidation, CO oxidation was not accelerated by NiO. High syngas selectivity was attained by using a less amount of diluent in the catalyst bed.

Spray Drying of Mannitol as a Drug Carrier—The Impact of Process Parameters on Product Properties

Powders intended for the use in dry powder inhalers have to fulfill specific product properties, which must be closely controlled in order to ensure reproducible and efficient dosing. Spray drying is an ideal technique for the preparation of such powders for several reasons. The aim of this work was to investigate the influence of spray-drying process parameters on relevant product properties, namely, surface topography, size, breaking strength, and polymorphism of mannitol carrier particles intended for the use in dry powder inhalers. In order to address this question, a full-factorial design with four factors at two levels was used. The four factors were feed concentration (10 and 20% [w/w]), gas heater temperature (170 and 190°C), feed rate (10 and 20 L/h), and atomizer rotation speed (6,300 and 8,100 rpm). The liquid spray was carefully analyzed to better understand the dependence of the particle size of the final product on the former droplet size. High gas heater temperatures and low feed rates, corresponding to high outlet temperatures of the dryer (96–98°C), led to smoother particles with surfaces consisting of smaller crystals compared to those achieved at low outlet temperatures (74–75°C), due to lower gas heater temperatures and higher feed rates. A high solution concentration of the feed also resulted in the formation of comparably rougher surfaces than a low feed concentration. Spray-dried particles showed a volume-weighted mean particle size of 71.4–90.0 µm and narrow particle size distributions. The mean particle size was influenced by the atomizer rotation speed and feed concentration. Higher rotation speeds and lower feed concentrations resulted in smaller particles. Breaking strength of the dried particles was significantly influenced by gas heater temperature and feed rate. High gas heater temperatures increased the breaking strength, whereas high feed rates decreased it. No influence of the process parameters on the polymorphism was observed. All products were crystalline, consisting of at least 96.9% of mannitol crystal modification I.

An optically pumped XeF(C-A) laser with repetitive rate of 10 Hz

A novel XeF(C-A) laser which can be operated in repetition mode has been developed based on surface discharge optical pumping technique. Its maximum repetitive rate is up to 10 Hz. The influence of repetitive rate and gas flow rate on the stability of output energy is studied and the main factor which influences the stability of output energy is analyzed. The experimental results show that increasing the gas flow rate into laser chamber can improve the stability of the output energy. The ideal output energy results of 20 laser pulses under different repetitive rates and their optimal experimental conditions are presented. Output energies of more than 4 J and better stability can be obtained when the laser device operates at 1, 2, and 5 Hz, respectively. When the gas feed rate is larger than 53 l/s, the stability of output energy is improved obviously at the repetitive rate of 10 Hz, and the average energy of 20 laser pulses is up to 3.2 J.

Bead characterization of FCAW of a rutilic fluxed core wire

This paper studies the effect of operational conditions on bead shape characteristics in fluxed core arc welding with a Brazilian-made wire with rutilic flux (ASME SFA-5.20: E71T-1/E71T-9/E71t-9M) of 1.2 mm in diameter. Bead-on-plate downhand welding trails were performed on 12 mm-thick low-carbon steel plates with a constant voltage power supply. A digital data logging system was used to measure the welding current and voltage, and wire feed rate. While the shielding gas composition (75% Ar–25% CO2 and 100% CO2), wire polarity, and feed rate (7 and 9 m/min) were varied during the trials, the electrode voltage (16 mm) and arc length (3.5 mm) were not changed. Weld bead characteristics (penetration depth, width, and fused and deposited areas), the presence of discontinuities, bead microstructure, and hardness were evaluated. Welding conditions of high productivity (high deposition rate) associated with adequate bead characteristics were determined for the wire.

Computational fluid dynamics modelling of nanopowder production by chemical vapour synthesis process

The chemical vapour synthesis (CVS) process has been applied to the production of nanosized metallic, intermetallic and ceramic particles of 5–200 nm sizes. A multiphase computational fluid dynamics model, which incorporates the gas phase governing equations of overall continuity, momentum, energy and species mass transport in two- and three-dimensional frameworks, has been used as an integral part of the CVS research. The population balance model is coupled with the gas phase equations to describe the formation and growth of nanoparticles. The quadrature method of moments, which allows direct tracking of local particle size distribution, is used to solve the particle population balance. The model has been applied to the CVS of tungsten carbide, aluminium and silica nanopowders from the vapour–phase reactions of precursors. Comparisons of the model predictions with experimental results in terms of average particle size and other process parameters have shown reasonable agreements. The effects of operating conditions, such as reaction temperature and carrier gas feedrate, on the particle size distribution have been evaluated. The model has shown a considerable potential as a tool for designing and scaling up these particle synthesis processes.

Induction plasma synthesis of nanometric spheroidized glass powder for use in cementitious materials

Because of its high throughput, Inductively-Coupled Plasma (ICP) torch can commercially provide an added value to waste glass (WG). It vaporizes WG into nanometric spheroidized glass powder (SGP) that could be used as a cementitious material. Changing the plasma gas (N2 vs O2), quench flow rate, pressure and WG feed rate induce variations on the particle size distribution and chemical composition. Using Field Emission Gun Scanning Electron Microscopy (FEGSEM), Brunauer, Emmet and Teller (BET) method, nano phase separation and Inductively-Coupled Plasma-Mass Spectrometry (ICP-MS), low quench gas, pressure and WG feed rate increase the nanometric content and specific surface of SGP. The use of O2 increases silica (SiO2) and decreases the sodium oxide (Na2O) content of SGP. The use of N2 rather demonstrates enrichment of SGP in Na2O in the cold reactor zones. This study shows that the nucleation theory of a crystalline material can be applied to an amorphous material.

Reforming of methane and carbon dioxide by DC water plasma at atmospheric pressure

An experimental plasma chemical reactor, equipped with a novel water plasma torch, was used for reforming methane and carbon dioxide mixture to produce synthesis gas (syngas). Water plasma is generated by the torch at atmospheric pressure, in the absence of carrier gases, water cooling system and special steam supply system. The influence of the ratio of CO 2 to CH 4 and total feed gas rate on syngas production, composition and energy conversion efficiency were investigated. Compared to other plasma technologies, the higher reaction performance was obtained by the novel water plasma process. The results show that, under optimum experimental conditions, the energy conversion efficiency reaches up to maximum value of 1.87 mmol/kJ and the highest energy efficiency of 74.63% is achieved, which is higher than that of other plasma processes. Furthermore, the obtained syngas with high mole ratio of H 2 to CO (close to 2) is suitable for the direct industrial application.

Catalytic reforming of natural gas for hydrogen production in a pilot fluidized-bed membrane reactor: Mapping of operating and feed conditions

A fluidized-bed membrane reformer was operated in two independent laboratories to map various operating conditions, to investigate the effects of changing the composition of the natural gas feed stream and to verify earlier experimental trials. Two feed natural gases were tested, containing either 95.5 or 90.1 mol% of methane (3.6 or 9.9 mol% of other gaseous higher hydrocarbons). Experimental tests investigated the influence of total membrane area, reactor pressure, permeate pressure and natural gas feed rates. A permeate-H 2-to reactor natural gas feed molar ratio >2.3 was achieved with six two-sided membrane panels under steam reforming conditions and a pressure differential across the membranes of 785 kPa. The total cumulative reforming time reached 395 h, while hydrogen purity exceeded 99.99% during all tests.

In-situ CO2 capture in a pilot-scale fluidized-bed membrane reformer for ultra-pure hydrogen production

A novel pilot fluidized-bed membrane reformer (FBMR) with permselective palladium membranes was operated with a limestone sorbent to remove CO2in-situ, thereby shifting the thermodynamic equilibrium to enhance pure hydrogen production. The reactor was fed with methane to fluidize a mixture of calcium oxide (CaO)/limestone (CaCO3) and a Ni-alumina catalyst. Experimental tests investigated the influence of limestone loading, total membrane area and natural gas feed rates. Hydrogen-permeate to feed methane molar ratios in excess of 1.9 were measured. This value could increase further if additional membrane area were installed or by purifying the reformer off-gas given its high hydrogen content, especially during the carbonation stages. A maximum of 0.19 mol of CO2 were adsorbed per mole of CaO during carbonation. For the conditions studied, the maximum carbon capture efficiency was 87%. The reformer operated for up to 30 min without releasing CO2 and for up to 240 min with some degree of CO2 capture. It was demonstrated that CO2 adsorption can significantly improve the productivity of the reforming process. In-situ CO2 capture enhanced the production of hydrogen whose purity exceeded 99.99%.

겔침전과 화학증착법에 의한 구형 UO2입자와 TRISO 피복입자 제조

HTGR using a TRISO coated particles as nuclear raw fuel material can be used to produce clean hydrogen gas and process heat for a next-generation energy source. For these purposes, a TRISO coated particle was prepared with 3 pyro-carbon (buffer, IPyC, and OPyC) layers and 1 silicone carbide (SiC) layer using a CVD technique on a spherical UO₂ kernel surface as a fissile material. In this study, a spherical UO₂ particle was prepared using a modified sol-gel method with a vibrating nozzle system, and TRISO coating fabrication was carried out using a fluidized bed reactor with coating gases, such as acetylene, propylene, and methyltrichlorosilane (MTS). As the results of this study, a spherical UO₂ kernel with a sphericity of 1+0.06 was obtained, and the main process parameters in the UO₂ kernel preparation were the well-formed nature of the spherical ADU liquid droplets and the suitable temperature control in the thermal treatment of intermediate compounds in the ADU, UO₃, and UO₂ conversions. Also, the important parameters for the TRISO coating procedure were the coating temperature and feed rate of the feeding gas in the PyC layer coating, the coating temperature, and the volume fraction of the reactant and inert gases in the SiC deposition.