Steam Vapor Research Articles

Investigation of coal gasification hydrogen and electricity co-production plant with three-reactors chemical looping process

This paper analyzes a novel process for producing hydrogen and electricity from coal, based on chemical looping combustion (CLC) and gas turbine combined cycle, allowing for intrinsic capture of carbon dioxide. The core of the process consists of a three-reactors CLC system, where iron oxide particles are circulated to: (i) oxidize syngas in the fuel reactor (FR) providing a CO 2 stream ready for sequestration after cooling and steam vapor condensation, (ii) reduce steam in the steam reactor (SR) to produce hydrogen, (iii) consume oxygen in the air reactor (AR) from air releasing heat to sustain the thermal balance of the CLC system and to generate electricity. A compacted fluidized bed, composed of two fuel reactors, is proposed here for full conversion of fuel gases in FR. The gasification CLC combined cycle plant for hydrogen and electricity cogeneration with Fe 2O 3/FeAl 2O 4 oxygen carriers was simulated using ASPEN ® PLUS software. The plant consists of a supplementary firing reactor operating up to 1350 °C and three-reactors SR at 815 °C, FR at 900 °C and AR at 1000 °C. The results show that the electricity and hydrogen efficiencies are 14.46% and 36.93%, respectively, including hydrogen compression to 60 bar, CO 2 compression to 121 bar, The CO 2 capture efficiency is 89.62% with a CO 2 emission of 238.9 g/kWh. The system has an electricity efficiency of 10.13% and a hydrogen efficiency of 41.51% without CO 2 emission when supplementary firing is not used. The plant performance is attractive because of high energy conversion efficiency and low CO 2 emission. Key parameters that affect the system performance are also discussed, including the conversion of steam to hydrogen in SR, supplementary firing temperature of the oxygen depleted air from AR, AR operation temperature, the flow of oxygen carriers, and the addition of inert support material to the oxygen carrier.

Saturated-Steam Pressure Drop in Flow Through Porous Media

Summary This note provides a simple steady-state method for estimating the pressure drop for steam vapor flowing at a constant mass rate through porous media. The derived formula includes the relevant properties of saturated steam and allows for their distribution along the zone of pressure variation. It also eliminates the need for steam tables within the applicable pressure range (10-2,900 psia). The method can also be extended to cases in which the rate varies in a known manner because of heat loss or other factors.

Technical Advancements in SAGD Evaporative Produced Water Treatment

Abstract There has been a shift away from the use of warm lime softening (WLS) and weak acid cation (WAC) ion exchange for produced water treatment to the use of mechanical vapour compression (MVC) evaporation followed by high pressure drum-type boilers. Approximately 18 steam assisted gravity drainage (SAGD) produced water evaporators are operating or are in various stages of construction in Alberta and overseas. Since the commissioning of the first such evaporators in 2002, many technical advancements have occurred which have resulted in reduced operating costs, improved reliability, reduced scaling and fouling potential, improved distillate quality and improved boiler feed quality for steam generation. This paper provides details of the technical advancements in evaporative produced water treatment based on full-scale operating data and lessons learned. It also presents improved evaporator configurations, discusses improvements in contaminant reduction and scale prevention systems, demonstrates how capital and operating costs can be drastically reduced as compared to earlier evaporator system designs, and provides recent advancements in modularization, evaporator disposal treatment, deoiling, membrane preconcentration, and zero discharge solids drying techniques. Introduction Over the past few years, there has been a rapid shift away from the use of traditional produced water treatment methods using WLS for silica reduction and WAC ion exchange for hardness removal, to the use of evaporative produced water treatment methods at SAGD facilities. With the use of evaporative produced water treatment, standard drum boilers are utilized for steam generation in lieu of once through steam generators (OTSG) and vapour liquid separators. This shift has occurred because of technical, economic and reliability factors, resulting in markedly improved life cycle costs for SAGD facilities. A simplified block flow diagram of the traditional approach to produced water treatment and steam generation is provided in Figure 1. A block flow diagram for the evaporative approach is provided in Figure 2.

An investigation on pretreatments for inactivation of lipase in naked oat kernels using microwave heating

Abstract To investigate the primary factors affecting the efficiency of microwave heating pretreatments in inactivating lipase in naked oat kernels, the effects of temperature, duration of heating, moisture content of oat kernels, tempering time and packaging conditions on the inactivation of lipase activities were examined. Microwave heat treatment for 45 s was found to inactivate 98–99% lipase in oat kernels (20 g in polyethylene package) with 11.1% moisture content, thereby stabilizing oat kernels against triglyceride lipolysis. The steam quantity played a crucial role in lipase inactivation. A trend was found: the higher the quantity of steam evaporated, the lower the residual lipase activities remained in whole kernels. Pretreatments, such as vacuum packaging, increasing the moisture content of oat kernels to a range of 17.0–25.0% from 11.1%, and conducting heat treatments as soon as the kernel moisture contents were adjusted, were found to be beneficial in accelerating steam evaporation; the efficiency of microwave heating on lipase inactivation was thereby increased.

Analysis of flow pattern and heat transfer in direct contact condensation

In direct contact condensation (DCC) phenomenon, whenever steam (vapor) is injected with very high velocity in sub-cooled water, the momentum and the energy of the steam is transferred to the surrounding liquid, leading to generation of flow pattern, turbulent in nature. The turbulent flow pattern enhances the heat transfer coefficient at the interface of steam jet and water (vapor–liquid interface) as well as at the immersed surfaces (solid–liquid interface). The flow and the temperature pattern in DCC system have been measured using hot film anemometer (HFA). The values of heat transfer coefficient at the vapor–liquid and solid–liquid interface were estimated using the CCA module of the HFA. The nozzle diameter ( d 0 ) was varied in the range of 1–2 mm and the nozzle upstream pressure in the range of 0.3–0.35 MPa (corresponding velocities in the nozzle were 286–304 m/s). The time series of velocity and temperature at the interface were analyzed to get the rates of surface renewal. A comparison has been presented between the predicted and the experimental values of heat transfer coefficient.

Reduction in infection risk through treatment of microbially contaminated surfaces with a novel, portable, saturated steam vapor disinfection system

Surface-mediated infectious disease transmission is a major concern in various settings, including schools, hospitals, and food-processing facilities. Chemical disinfectants are frequently used to reduce contamination, but many pose significant risks to humans, surfaces, and the environment, and all must be properly applied in strict accordance with label instructions to be effective. This study set out to determine the capability of a novel chemical-free, saturated steam vapor disinfection system to kill microorganisms, reduce surface-mediated infection risks, and serve as an alternative to chemical disinfectants. High concentrations of Escherichia coli, Shigella flexneri, vancomycin-resistant Enterococcus faecalis (VRE), methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enterica, methicillin-sensitive Staphylococcus aureus, MS2 coliphage (used as a surrogate for nonenveloped viruses including norovirus), Candida albicans, Aspergillus niger, and the endospores of Clostridium difficile were dried individually onto porous clay test surfaces. Surfaces were treated with the saturated steam vapor disinfection system for brief periods and then numbers of surviving microorganisms were determined. Infection risks were calculated from the kill-time data using microbial dose-response relationships published in the scientific literature, accounting for surface-to-hand and hand-to-mouth transfer efficiencies. A diverse assortment of pathogenic microorganisms was rapidly killed by the steam disinfection system; all of the pathogens tested were completely inactivated within 5 seconds. Risks of infection from the contaminated surfaces decreased rapidly with increasing periods of treatment by the saturated steam vapor disinfection system. The saturated steam vapor disinfection system tested for this study is chemical-free, broadly active, rapidly efficacious, and therefore represents a novel alternative to liquid chemical disinfectants.

A New Inundation Correlation for the Prediction of Heat Transfer in Steam Condensers

A new correlation used to account for the inundation effect on the prediction of heat transfer between steam vapor and cooling water in tube-and-shell condensers is proposed in this work. The proposed correlation is validated by comparing the predicted results with the experimental data of a steam surface condenser. A modified k–ϵ turbulence model for gas–liquid two-phase flows with distributed flow resistance is used in the numerical simulation. The predicted results using the proposed correlation agree better with the experimental data than those obtained using the existing correlations for inundation.

Performance of Ni/YSZ cermet cathode prepared by mechanical alloying for high temperature electrolysis of water vapor (steam): effect of anode and cathode thicknesses on the efficiency of hydrogen production

Abstract Ni/YSZ (Y2O3-stabilized ZrO2) composite cathode is fabricated by high-nergy ball milling of Ni and YSZ powders for high temperature electrolysis of water vapor. Composite powder composition, time and rotation speed of ball milling were optimized by trial and error for suitable performance with maximum efficiency of fabricated cathode in high temperature electrolysis of water vapor (steam) at 800°C. The composite powders thus synthesized were characterized using various analytical tools such as X-ray diffraction, scanning electron microscopy and particle size analysis, and a self-supporting planar type unit cell was prepared with Ni/YSZ composite cathode and Pt paste anode screen-printed on each side of YSZ electrolyte disk (30 mm dia.) and then sintered at 1450°C for high temperature electrolysis. X-ray diffraction and particle size analysis results showed that the Ni/YSZ composite effectively consisted of crystalline Ni and YSZ distributed on a sub-micron scale and evenly distributed without aggregation of particles. To study the effect of anode and cathode thickness on the efficiency of the hydrogen production rate, screen-printing of anode and cathode was carried out on each side of YSZ electrolyte to three different thickness values during the fabrication of a self-supporting planar type unit cell which operated quite satisfactorily during high temperature electrolysis at 800°C: a significantly higher hydrogen production rate of 13 sccm (standard cubic centimeters per minute) was reproducibly observed for triple screen-printing of anode and cathode over each side of the YSZ electrolyte disk compared to 0.5 sccm for the single screen-printed cathode under an applied direct current of 0.7 mA cm−2. Additionally, linear increase in hydrogen production was observed with applied current for triple screen-printed electrodes in contrast to single and double screen-printed electrodes.

Solvatochromic Shifts of the n → π* Transition of Acetone from Steam Vapor to Ambient Aqueous Solution: A Combined Configuration Interaction QM/MM Simulation Study Incorporating Solvent Polarization.

A hybrid quantum mechanical and molecular mechanical potential is used in Monte Carlo simulations to examine the solvent effects on the electronic excitation energy of the n → π(*) transition of acetone in ambient and supercritical water fluid, in which the temperature is in the range of 25-500 °C with pressures of 1-2763 atm. In the present study, the acetone molecule is described by the AM1 Hamiltonian, and the water molecules are treated classically. Two sets of calculations are performed. The first involves the TIP4P model for water, and the second employs a polarizable model, POL2, for the solvent. The first calculation yields the excitation energy by using the static ground-state solvent charge distribution obtained from QM-CI/MM calculations. The latter takes into account the effect of solvent polarization following the solute electronic excitation. The trend of the computed n → π(*) blue-shifts for acetone as function of the fluid density is in good agreement with experimental results. The present simulations of acetone in the supercritical, near supercritical, dense-liquid, and ambient water fluids reveal that the solvatochromic shifts are dominated by the electrostatic interactions between acetone and water molecules during the solute excitation. Additionally, the solvent charge redistribution following the solute electronic excitation has a small correlation (0 to -37 cm(-1)) to the total solvatochromic shift and decreases linearly with water density. Both the solvatochromic shift and solvent polarization correction are more obvious in the ambient water than in the supercritical water because the solvent stabilization of the ground state over the excited state is more significant in the former condition.

Hygrothermal Delaminations in Lead-Free Solder Reflow of Electronic Packages

The use of environmentally friendly lead-free solder in electronic assembly requires a higher process temperatures that double the saturated steam pressure inside the electronic package. We studied the interfacial delamination fractures created by the trapped steam inside the defect voids in packages by computationally modeling the steam diffusion and evaporation processes and the hygrothermal fracture behaviors. These results were compared with results from the conventional saturated steam pressure approach. The comparisons revealed that the saturated steam approach is appropriate for small defects, while the evaporative-diffusion approach is suited for delamination analyses of small and large defects. Our results showed that the strain energy release rate increased with initial defect growth, but reached a defect-size independent plateau when the defect had grown larger than the temperature-dependent critical defect size. To control delamination in packages undergoing lead-free solder reflow, the interfacial fracture energy release rate should be engineered to be above this plateau by controlling the interfacial adhesion, and the applied strain energy release rate should be reduced by reducing the diffusion and evaporation rate of water in the materials.

Specific features of modification of activated carbons with steam and hydrogen peroxide vapor at high temperatures and pressures

The effect of high-temperature treatment of activated carbons with water and hydrogen peroxide solutions on their pore structure, surface structure, and adsorption properties was studied.

Preparation of alumina-doped yttria-stabilized zirconia nanopowders by microwave-assisted peroxyl-complex coprecipitation

Alumina-doped yttria-stabilized zirconia (ADYSZ) nanopowders were prepared by microwave-assisted peroxyl-complex coprecipitation (MAPCC) using ZrOCl 2·8H 2O, Y 2O 3 and AlCl 3·6H 2O as starting materials, NH 3·H 2O as precipitant and H 2O 2 as complexant. The effects of adding H 2O 2 and microwave drying on the preparation and properties of ADYSZ were investigated. The precursors and nanopowders were studied by EDX, XRD, SEM and TEM techniques. The results show that the uniformity of component distribution within ADYSZ nanopowders is improved by adding appropriate dosage of H 2O 2. Complexing reaction between H 2O 2 and Zr 4+ ion restrains the hydrolyzation and precipitation of Zr 4+ ion. With the addition of H 2O 2, Al 3+, Y 3+ and Zr 4+ ions can be precipitated synchronously in a relatively narrow range of pH value. H 2O 2 also improves the filterability of the wet precipitate. The highly hydrophilic precipitates can be quickly and effectively separated from aqueous solution. During microwave drying process, the moisture of wet precursors is selectively heated. Quick expansion of steam vapor within the wet colloidal particles causes the aggregations burst into numerous tiny lumps. Compared with oven drying, microwave drying can not only shorten drying time but also reduce aggregation intensity of the resultant ADYSZ nanopowders.

Crumpet Structures: Experimental and Modelling Studies

Crumpets are made by heating fermented batter on a hot plate at around 230°C. The characteristic structure dominated by vertical pores develops rapidly: structure has developed throughout around 75% of the product height within 30s, which is far faster than might be expected from transient heat conduction through the batter. Cooking is complete within around 3 min. Image analysis based on results from X-ray tomography shows that the voidage fraction is approximately constant and that there is continual coalescence between the larger pores throughout the product although there is also a steady level of small bubbles trapped within the solidified batter. We report here experimental studies which shed light on some of the mechanisms responsible for this structure, together with some models of key phenomena.Three aspects are discussed here: the role of gas (carbon dioxide and nitrogen) nuclei in initiating structure development; convective heat transfer inside the developing pores; and the kinetics of setting the batter into an elastic solid structure. It is shown conclusively that the small bubbles of carbon dioxide resulting from the fermentation stage play a crucial role as nuclei for pore development: without these nuclei, the result is not a porous structure, but rather a solid, elastic, inedible, gelatinized product. These nuclei are also responsible for the tiny bubbles which are set in the final product. The nuclei form the source of the dominant pore structure which is largely driven by the, initially explosive, release of water vapour from the batter together with the desorption of dissolved carbon dioxide. It is argued that the rapid evaporation, transport and condensation of steam within the growing pores provides an important mechanism, as in a heat pipe, for rapid heat transfer, and models for this process are developed and tested. The setting of the continuous batter phase is essential for final product quality: studies using differential scanning calorimetry and on the kinetics of change in the visco-elastic properties of the batter suggest that this process is driven by the kinetics of gelatinization. Unlike many thermally driven food processes the rates of heating are such that gelatinization kinetics cannot be neglected. The implications of these results for modelling and for the development of novel structures are discussed.

Thermal analysis of ME—TVC+MEE desalination systems

Thermal analysis of three different configurations of a multi-effect thermal vapor compression desalting system is presented: conventional ME—TVC,ME—TVC with regenerative feed heaters (ME—TVC,FH) and ME—TVC coupled with a conventional MEE system (ME—TVC+MEE). The analysis is based on the First and Second Law of Thermodynamics. A parametric study was carried out to investigate the impact of motive steam pressure, temperature difference per effect, top brine temperature, feed seawater temperature and motive steam flow rate on the system's performance for each configuration. The exergy analysis showed that irreversibilities in the steam ejector and evaporators are the main sources of exergy destruction in the three configurations. When steam is supplied directly from the boiler to all configurations, results showed that the first effect was responsible for about 50% of the total effect exergy destruction. The study also showed that the decrease in exergy destruction is more pronounced than the decrease in the gain ratio at lower values of motive steam pressure. Lowering the temperature difference across the effects, by increasing the surface area, decreases the specific heat consumption. On the other hand, exergy losses are small at low temperature differences and low top brine temperature. The analysis showed that the third configuration (ME—TVC+MEE) has two main features compared to ME—TVC and ME—TVC, FH. First it has a lower compression ratio, which makes the motive steam capable of compressing larger amounts of the entrained vapor; as a result, the amount of motive steam is reduced. Second, the configuration can be used for large-scale production.

Remediation of a chlorinated solvent-contaminated site using steam injection and extraction

The remediation methods designed and deployed for use at the Department of Energy Savannah River Site 321-M solvent storage tank area (SSTA) comprise a complete set of cleanup and control techniques using steam remediation and electrical resistance tomography. The technologies include the engineered combination of steam injection; dual-phase extraction for subsurface remediation; and an in-situ tomographic imaging technology for monitoring of thermal treatment zones in the subsurface. The technologies use methods developed for enhanced oil recovery using steam injection.At the SSTA, the remediation zone was 31 31 m (100 100 ft) on the surface and extended from 6- to 49-m (20- to 160-ft) depth. The ambient water table exists at approximately 44-m (145-ft) depth. Steam injection wells ringed the target zone, with multiphase extraction dominated by a centered dual-phase extraction well, with three additional existing perimeter vapor extraction wells.The SSTA field-scale deployment of steam injection, groundwater pumping, and vapor extraction removed 31,000 kg (68,000 lb) of volatile organic compounds during 12 months of operation. Total steam injected for the 12-month period of operations was approximately 48 109 kJ (45 109 BTU), injected at wellhead pressures between 0.15 and 0.38 MPa (7 and 40 psig), depending on lithology of the screened interval, depth, and operational considerations.

The effects of surface steam treatment on bacterial reduction and storage of beef primals and retail cuts

Beef primals and retail joints were rapidly heated and cooled using steam condensation and evaporation heat transfer processes. Treatments of beef primals to 100 or 120 °C showed no significant differences. After 3 weeks of vacuum-packed storage at 0 °C, mean total viable count (TVC) and enterobacteriaceae counts for treated primals were approximately 1 log 10 cfu cm −2 lower than for un-treated primals. Levels were similar after 6 weeks of vacuum-packed storage. The effects of a second treatment on retail joints cut from treated and un-treated primals that had been stored in vacuum packs for 3 weeks showed TVC and enterobacteriaceae counts for treated joints were approximately 1 log 10 cfu cm −2 lower than for un-treated joints after 4 and 8 days of over-wrapped storage. The results suggest the steam decontamination treatment used can remove small but significant ( p < 0.05) numbers of bacteria from the beef surface.

Temperature Development of Homo- and Hetero-Clustering in Saturated Vapors

Computational findings of temperature increase of clustering degree in saturated vapors are analyzed. A thermodynamic proof is presented and a simple criterion derived. Illustrations are based on saturated steam, magnesium and carbon vapor. The results are applicable to synthesis of fullerenes, metallofullerenes, and heterofullerenes, chemical vapor deposition technique, or atmospheric chemistry.

Decontamination of polyaromatic hydrocarbons from soil by steam stripping: mathematical modeling of the mass transfer and energy requirement.

For cleaning of contaminated soil from polyaromatic hydrocarbons (PAH), a thermal separation process is applied. The process uses superheated steam that is supplied through a nozzle together with a suspension (approximately 40% soil content) of the contaminated soil into a tube reactor. In the reactor, the soil suspension is vaporized, and the PAH are stripped from the soil at temperatures of 140-300 degrees C. In a cyclone, a solid-vapor separation is carried out, and after going through a condenser, a separation of the condensed water and the PAH is obtained. For improvement of the economical performance, a heat recovery is integrated. This is realized by preheating the water/stream supplied to the evaporator by cooling the vapor steam leaving the reactor. For the mathematical description of the process, the removal of the PAH from the soil is considered to take place by a desorption process. Sorption isotherms are measured by batch experiments and can be described by isotherms of Langmuir type. A dispersion model is used to describe the mass transfer of the process. The process is mathematically modeled for instationary and stationary operation. The simulation predicts the lowest energy consumption at a good cleaning performance at a steam-to-suspension ratio of 5.

Theoretical and Experimental Investigation of the Flooding Velocity of an Immiscible Vapor Mixture Condensing in Vertical Tubes

A mathematical model accounting for the pressure oscillation when flooding occurs is presented to predict the velocity limit of an immiscible vapor mixture condensing in a vertical tube. This model incorporated the parameters of vapor inlet velocity, pressure drop, interfacial friction stress, tube inside diameter, and the fluid physical properties. The in-tube condensation experiments of an oil−steam vapor mixture with various mass ratios have been conducted using an 18 mm i.d. brass tube and a 20 mm i.d. glass tube, respectively. The model predicted that data agreed very well with the experimental data, indicating that this model is valid to predict the velocity limit of the immiscible vapor mixture condensing in a vertical tube.

Application of absorption heat transformer to recover waste heat from a synthetic rubber plant

This paper reports the test results of the first industrial-scale absorption heat transformer (AHT) equipment in China, to recover the waste heat released from mixture of steam and organic vapor at 98 °C in coacervation section, synthetic rubber plant of Yanshan Petrochemical Corporation, Beijing, China. The recovered heat is used to heat hot water from 95 to 110 °C, feeding back to the coagulator as the supplementary heating source. The AHT system is operating with H 2O/LiBr solution with heat flow of 5000 kW. The coefficient of performance (COP), the thermal efficiency and the temperature lift of the AHT system are presented. The heat transfer characteristics of the AHT components, i.e. absorber, generator, evaporator, condenser and the liquid–liquid solution heat exchanger, are also illustrated by comparison of experimental data and the model calculated results. The results show that the mean COP is 0.47, the gross temperature lift of 25 °C can be realized and the payback period is ≈2 years.