Super High Pressure Research Articles

Improvement of chemical monitoring of water-chemistry conditions at thermal power stations based on electric conductivity and pH measurements

The increased requirements to the quality of the water heat conductor for working superhigh (SHP) and supercritical (SCP) pressure power plants and promising units, including combined-cycle gas turbine (CCGT) units and power plants with ultrasupercritical parameters (USCPs), can largely be satisfied through specific electric conductivity and pH measurements for cooled heat conductor samples combined with calculations of ionic equilibria and indirect measurements of several specified and diagnostic parameters. The possibility of calculating the ammonia and chloride concentrations and the total concentration of hardness and sodium cations in the feed water of drum-type boilers and the phosphate and salt contents in boiler water was demonstrated. An equation for evaluating the content of potentially acid substances in the feed water of monotube boilers was suggested. The potential of the developed procedure for evaluating the state of waterchemistry conditions (WCCs) in power plants with CCGT units was shown.

Hydrogen diffusion kinetics and structural integrity of superhigh pressure Mg-5 wt%Ni alloys with dendrite interface

A strategy of low-angle orientation dendrite interface-high index planes-which prepared by super-high pressure (SHP) technique, is proposed and successfully improved the hydrogen storage properties of Mg based materials for the first time, wherein a simple binary Mg-Ni alloy is used as a sample to elucidate its related mechanisms. The phase composition, morphology variation and hydrogen storage properties of the as-cast and SHP Mg-5Ni alloys in the temperature range of 1100–1600 °C are systemically investigated. The reversible hydrogen storage capacities and plateau hydrogen pressure of the as-cast and SHP alloys are close due to the same hydrogen storage phases (Mg and Mg2Ni). Note that although SHP treatment at 1600 °C has a large weight fraction of Mg6Ni compound, it still effectively reduces the onset temperature of dehydriding (∼262 °C), as well as improves the hydrogen desorption kinetics at low temperatures and structural integrity. The low onset temperature and outstanding hydrogen sorption/desorption kinetics are mainly associated with the formation of a large number of dendrite interface, in which the hydrogen atoms readily occur “zig-zag” jumps along {11−20} prismatic planes. This dendrite interface of high index planes which prepared by SHP technique paves a new pathway to enhance the hydrogen storage performances of magnesium based alloys.

Features of steam turbine cooling by the example of an SKR-100 turbine for supercritical steam parameters

Basic principles of cooling of high-temperature steam turbines and constructive solutions used for development of the world’s first cooled steam turbine SKR-100 (R-100-300) are described. Principal differences between the thermodynamic properties of cooling medium in the steam and gas turbines and the preference of making flow passes of cooled cylinders of steam turbines as reactive are shown. Some of its operation results and their conclusions are given. This turbine with a power of 100 MW, initial steam parameters approximately 30 MPa and 650°C, and back pressure 3 MPa was made by a Kharkov turbine plant in 1961 and ran successfully at a Kashira GRES (state district power plant) up to 1979, when it was taken out of use in a still fully operating condition. For comparison, some data on construction features and operation results of the super-high pressure cylinder of steam turbines of American Philo 6 (made by General Electric Co.) and Eddystone 1 (made by Westinghouse Co.) power generating units, which are close to the SKR-100 turbine by design initial steam parameters and the implementation time, are given. The high operational reliability and effectiveness of the cooling system that was used in the super-high pressure cylinder of the SKR-100 turbine of the power-generating unit, which were demonstrated in operation, confirms rightfulness and expediency of principles and constructive solutions laid at its development. As process steam temperatures are increased, the realization of the proposed approach to cooling of multistage turbines makes it possible to limit for large turbine parts the application of new, more expensive high-temperature materials, which are required for making steam boilers, and, in some cases, to do completely away with their utilization.

Space-time analysis of the changing patterns of population pressure on the ecological environment in China

This paper examines the temporal change and spatial variation of population pressure on the ecological environment in China. We have collected sufficient data from the statistical yearbooks of 31 provincial administrative areas in 1990, 1995, 2000, 2005, and 2010. Using a geographic information system (GIS) and relevant models, we analyzed the trend of the population pressure on ecological environment and the change of the gravity center of ecological environment quality. We conclude that: (1) generally, population pressure on the ecological environment in China was becoming higher during 1990–2010, especially in some areas where the population and environment were in serious imbalance and the ecological environment experienced severe pollution; (2) during a certain period, population pressure on the ecological environment was becoming lower in some areas, but the ecological environment was getting worse; (3) the areas with super-high population pressure on the ecological environment were Beijing, Tianjin...

Microstructure and Phase Transformation of Super-High Pressure Mg-Li Alloy

Super-high pressure (SHP) changes crystal structure and electronic distribution of metallic materials, which plays an important role in properties. Herein, a duplex Mg-7%wt.Li alloy was heat-treated under SHP (2 GPa) by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 450~1350 °C. Microstructure, phase transformation behavior and mechanical properties were examined. Compared with the as-cast sample, the SHP samples after heat-treating from 450 °C to 750 °C under 2 GPa were composed of twinning in addition to duplex structure. Comparatively, the samples treated between 1050 °C and 1350 °C exhibit typical dendritic morphology. Phase transformation from Li3Mg7 phase or Li0.92Mg4.08 phase to Li3Mg17 phase occurred during the whole investigated temperature range, in which only the Li3Mg17 phase maintained when the temperature exceeds 1050 °C. The microhardness of the sample prepared at 750 °C under 2 GPa was 73.15HV, which is 1.5 times higher than that of the as-cast one. The improved microhardness is mainly attributed to the formation of nanosized twins during SHP treatment. These fine twins effectively prohibit the dislocation movement during deformation. It reveals the SHP is an effective approach to prepare high performation Mg alloys.

Diesel nozzle geometries on spray characteristics with a spray model coupled with nozzle cavitating flow

Fuel spray characteristics is known to significantly affect the combustion and emission processes in diesel engines. High-pressure common-rail system can supply so high injection pressure for getting the better spray characteristics to enhance combustion efficiency and reduce emission. With the fuel injection pressure increasing, spray process becomes more and more complex which makes the study on atomization mechanism more challenging. Under the super high injection pressure, the internal turbulent flow and cavitating flow of the nozzle will greatly influence the subsequent fuel atomization process and spray characteristics, especially the cavitation has been the key to relating internal flow of nozzle and atomization behavior. So it is necessary to simulate the fuel spray process considering of internal cavitating flow of the nozzle. In this paper, firstly, the high-precision three-dimension structure of nozzle with detailed internal geometry information were obtained using synchrotron radiation x-ray phase contrast imaging technology, which was used for the mesh generation of three-dimensional numerical simulation of the cavitating flow in the nozzle. Then the spray model coupled with nozzle cavitating flow was setup in FIRE v2010 and validated by the spray experimental data got from the high-speed imaging technology on a high-pressure common-rail injection system. The spray simulations coupled with cavitating flow showed that the cavitating flow characteristics in nozzles have a large effect on both macroscopic properties and microscopic properties. Finally basing on the above verified spray model, multi-scheme simulations with various geometry parameters of nozzle were performed and the effect of nozzle geometries on the spray characteristics was analyzed and it was concluded that the nozzle sac volume, hole inlet curvature, hole inclination angle, injector needle lift and needle eccentricity had obvious effects on the nozzle flow and subsequent spray, and there was an opposite trend between the spray penetration and Sauter mean diameter, which provided a certain reference value for structure optimization of the fuel system.

A Kind of Electric-Corona-Prevent Paint

Based on the issue of the Corona Loss that generated in EHV and UHV transmission process, the work is about energy saving, emission reduction, and creates a kind of electric-corona-prevent paint which is suitable for both the super high pressure transmitting wires and metal equipment . The paint is consisted of RTV, charcoal and other additives. The basic theory is to cover the wires which are certain degree damaged with the paint by spraying. After that, we carry out some experiments on the covered and uncovered wires to contrast the loss of electric-corona. The results of the experiments show that, the wire covered by the electric-corona voltage and a lower loss of electric-corona than those without the paint, which proved the effect of the electric-corona-prevent paint well.

Preservation conditions for marine shale gas at the southeastern margin of the Sichuan Basin and their controlling factors

Complex tectonic movements and high thermal maturity of marine shale dominate South China, where preservation conditions are critical for shale gas enrichment and productivity. Based on the exploration practices of the Silurian shale gas at the southeastern margin of the Sichuan Basin in recent years, conventional gas and shale gas were compared in terms of their preservation conditions. The results revealed that superior roof and floor conditions are indispensable to shale gas preservation. Moreover, the self-sealing ability and the huge gap of up to 2–8 times between vertical and lateral permeability of shale gas reservoirs determine the lateral diffusion as the basic pattern of shale gas migration. The unconformity at the bottom of Lower Cambrian leads to worse preservation conditions in the system, and cutting by faults may accelerate the diffusion of shale gas. Major controlling factors for shale gas preservation and their criteria of discrimination were also investigated. It is suggested that: (1) the strength of tectonic modification is the major factor controlling shale gas preservation. Broad and gentle structures with continuous seals and an anticlinal setting are more favorable for the enrichment of shale gas, and a closed evolutionary environment with late uplifting is more favorable for the preservation of shale gas; (2) shale gas can be preserved well in downdip areas without faults or effectively closed or shielded by faults and areas far away from outcrops or zones with stratigraphic hiatus; (3) pressure coefficient is a comprehensive indicator for discriminating preservation conditions. In the study area, the pressure coefficient is in positive correlation with shale gas production and the high or super-high pressure of reservoir is a signal of good preservation condition for shale gas; and (4) in the areas within the southeastern Sichuan Basin, other than those close to erosion zones or hiatus, the Wufeng Fm. of Upper Ordovician and the Longmaxi Fm. of Lower Silurian present high pressure coefficient (up to 2.25) generally, demonstrating good preservation conditions for shale gas, while the pressure coefficient reduces progressively toward or outside the margin of the basin, corresponding to downgrading preservation conditions.

Microstructure and compression deformation behavior in the quasicrystal-reinforced Mg-8Zn-1Y alloy solidified under super-high pressure

The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). And, compression deformation behavior at room-temperature was studied. The results showed that the microstructure of Mg-8Zn-1Y alloy solidified under ambient pressure and super-high pressure was both mainly composed of α-Mg and quasicrystal I-Mg3Zn6Y. Solidification under super-high pressure contributed to refining solidified microstructure and changing morphology of the intergranular second phase. The morphology of intergranular second phase (quasicrystal I-Mg3Zn6Y) was transformed from continuous network (ambient pressure) to long island (high pressure) and finally to granular (super-high pressure) with the increase in pressure. The compressive strength, yield strength and rupture strain of the samples solidified under ambient pressure were significantly improved from 262.6 MPa, 244.4 MPa and 13.3% to 437.3 MPa, 368.9 MPa and 24.7% under the pressure of 6 GPa, respectively. Under ambient pressure, cleavage plane on compressive fracture was large and smooth. When it was solidified under the pressure ranging from 4 to 6 GPa, cleavage plane on compressive fracture was small and coarse. In addition, dimple, tear ridge and lobate patterns existed.

The Spatial Analysis of Population Pressure on the Ecological Environment in China during 1990-2010 Years

This paper examines the temporal and spatial variations of population pressure on the ecological environment in China. We have collected sufficient data from the statistical yearbooks of 31 provincial administrative areas in 1990, 1995, 2000, 2005 and 2010. By using the geographic information system (GIS) and relevant models, we analyzed the trend of the population pressure on ecological environment. We conclude that: 1) generally, population pressure on the ecological environment in China was becoming higher, especially in some areas, the population and environment was in severe imbalance and the ecological environment experienced serious pollution; 2) during a certain period when population pressure on the ecological environment was becoming lower in some areas, the ecological environment was getting worse; and 3) the areas of super high population pressure on the ecological environment were Beijing, Tianjin and Shanghai.

Study on Architecture of Measurement of Multi-Points Strain of Hinge Sleeve of Cubic Press under Super-High Pressure

A system of measuring of multi-points strain of hinge sleeve of cubic press was presented. This system can measure more than 40-points of stress synchronously. The key equipment of this system is PXI platform which is the product of NI. This system acquires data of strain of hinge sleeve of cubic press under super-high pressure when it is working, which is very useful for aid-design of hinge sleeve of cubic press. The results of measurement are also helpful for comparing with simulations and validate its reliability.

The Fatigue Life Analysis of Prestressed Wire-Wound Super-High Pressure Vessel Based on ANSYS

With the the development of super-high pressure technology such as the super-high biological treatment processing, the wire-wound prestressed vessel was widely used as the main pressure bearing structure. It’s proved that the stress was well-distributed along thickness direction and the carrying capacity was improved comparing with traditional pressure vessel. But the deign of wire-wound pressured vessel so far only checks out the fatigue strength margin of winding wire according to the design theory, and lacking of fatigue design of inner cylinder could causes potential safety hazard. So a stress analysis was carried out for prestressed wire-wound vessel with the help of ANSYS, and the fatigue life of the whole prestressed vessel was validated by means of theoretical calculation and the Fatigue Tool .

Preparation of pillared carbon thin films from the reduction of silylated graphite oxide by UV light irradiation and their size selective electrical response to various molecules

Silylated graphite oxide thin films were reduced by UV light irradiation using a super high pressure Hg lamp at 95°C. The reduction of silylated graphite oxide was completed within 24h and a new pillared carbon with an interlayer spacing of 0.81nm was obtained. Pillared carbons with larger interlayer spacings of about 1.13nm were also obtained from graphite oxide silylated with octyltrichlorosilane and then with 3-aminopropyltriethoxysilane for 1.5–6h, when they were reduced by UV light irradiation and heating at 200°C under vacuum. Selective electrical response during exposure to gaseous vinylene carbonate, acetonitrile, ozone and hydrogen molecules has been achieved by changing the pillar density in the resulting pillared carbon films.

Analysis on Fatigue of Hinge Sleeve in Cubic Press Based on ANSYS

Hinge sleeve of cubic press is the key important equipment which is used in the field of processing and production of super-hard materials, and is always under super high pressure. So the problem of fatigue must be concerned. In this paper, the model of hinge sleeve of cubic press was established in ANSYS and UG. Fatigue of hinge sleeve in cubic press was analyzed by ANSYS. The results of calculation shows that the times of work period of hinge sleeve reaches 61550 under extreme load, satisfied the requirement of design.

Microstructure and Compression Deformation Behavior in the Quasicrystal-Reinforced Mg-6Zn-2Y Alloy Solidified under Super-High Pressure at Room-Temperature

The microstructures of the Mg-6Zn-2Y alloy solidified under high pressures were investigated using scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The room-temperature compression behavior was analyzed through experiments, showing that the microstructures of the alloys are consisted of α-Mg and quasicrystal I-Mg3Zn6Y phases. With solidification pressure increasing, the microstructures were refined, and the morphologies of the inter-dendritic secondary phase were improved from continuous networks into long-island and granule. The compression strength, yielding strength and compressibility were increased significantly corresponding with solidification pressure, from 259.02 MPa, 230.39 MPa and 18.3% under ambient pressure to 361.43 MPa, 272.25 MPa and 33.1% under high pressure of 6 GPa. The cleavage planes are flat, and the cleavage steps are straight under ambient pressure. However, the cleavage planes are small and rough under 4-6 GPa; tearing dimples occur in the tearing area, indicating that the degree of cleavage fracture decreases under high pressure.

Phase transformation of Mg–Li alloys induced by super-high pressure

The effect of superhigh pressure (4GPa) on phase transformation behavior and mechanical properties of a duplex phase Mg–7wt%Li alloy has been investigated in the temperature range from 450 to 1150°C. Hardness and tensile strength of Mg–7wt%Li alloy have been significantly improved by super-high pressure treatment at 700°C for 120min. The microstructural observation is confirmed that super-high pressure is of benefit for phase transformations from bcc-Li3Mg7 to hcp phases and hcp-Li3Mg17 to hcp-Li0.92Mg4.08. The improved mechanical properties are mainly associated with the reduction of bcc-Li3Mg7 phase and the formation of {10−11} compression twins in hcp-Li0.92Mg4.08 phase.

Study on Fatigue of Hinge Sleeve of Cubic Press based on ANSYS

Hinge sleeve of cubic press is the most important equipment which is used in the field of processing and production of super-hard materials, and is always under super high pressure, so the problem of fatigue must be concerned. In this paper, Actual model of hinge sleeve of cubic press was established in ANSYS. Strength of hinge sleeve of cubic press was calculated under super high pressure load in realistic condition, which the equivalent stress contours were obtained, and the danger point was found out. Then the fatigue analysis was carried out to this danger point by applying ANSYS/Fatigue module. Consequently the fatigue usage coefficients were obtained.

Effects of super-high pressure on microstructures, nano-mechanical behaviors and corrosion properties of Mg–Al alloys

Abstract The aim of this study was to investigate the effects of super-high pressure solidification (2 and 4 GPa) on microstructures, nano-mechanical behaviors and corrosion properties of Mg-30 wt.% Al alloy. The lattice parameter (a) of Mg matrix is decreased and the c/a value is increased owing to the increased Al concentration in Mg matrix. In contrast to the as-cast sample or other super-high pressure samples, the Mg matrix is more homogeneous and the net-like eutectic phase becomes finer after super-high pressure solidification at 800 °C under 2 GPa. In addition, the area fraction of eutectic phase is reduced with increasing the exterior pressure and temperature during the solidification, whilst the Al concentration in both the Mg matrix and the eutectic phase are enhanced. The nanoindentation results indicate that both the hardness and Young’s modulus are sensitive to the solidification pressure and temperature. The Tafel curves and electrochemical impedance spectroscopes results reveal the corrosion properties of the sample at 800 °C under 2 GPa are remarkably improved due to the formation of a compact and continuous oxide layer.

Effect of consolidation pressure up to 1.8GPa on the sintering of nanocrystalline nc-Y2O3

Abstract Sintering of nanocrystalline (nc) monoclinic yttrium oxide (Y 2 O 3 ) was studied in the homologue temperature range of 0.4–0.7 T M . Samples were isostatically consolidated at super high pressure (SHP), up to 1.8 GPa. The combined effects of consolidation pressure and sintering temperature on the properties and microstructure are explored. The physical properties of the samples, mainly elastic modulus follow in general the density changes, or the interparticle contact area, but are also affected by sintering temperature. The effect of compaction pressure and sample density on the phase transition is studied and discussed.

Spherical strengthening precipitate in a Mg-10 wt%Y alloy with superhigh pressure aging

A Mg-10wt% Y alloy exhibited age hardening response by both artificial aging at 220°C (T6) and superhigh pressure aging (6GPa) at 300°C (SHP-300). A spherical strengthening precipitate (Mg24Y5) was achieved after SHP-300 heat treatment, which was different from conventional plate-shaped strengthening precipitate (β′) after T6 treatment. Compared with the T6 state sample, the peak hardness, strength and ductility were improved by means of SHP-300 treatment. The improved hardness and strength were associated with the nano-scale precipitate (Mg24Y5) and strain hardening. The large elongation was ascribed to the formation of spherical precipitate, which can effectively reduce the stress concentration during the deformation process.