High-pressure Equipment Research Articles

Large elastoplastic strains and the stressed state of a deformable gasket in high pressure equipment with diamond anvils

A procedure is developed and realized in the form of a numerical modelling program for deformation of a gasket in diamond anvils taking account of the effect of high pressure and large elastoplastic strains for the material. The procedure is based on the finite element method with a stepwise iteration algorithm (the initial stress method). In the case of considerable distortion of the finite element network with large strains a procedure is used for redefining the network deformation. A package of programs for solving elastoplastic problems with large strains and high pressure developed at the Institute of Superhard Materials of the Ukrainian National Academy of Sciences is used in the calculations. Two materials are considered: hardened stainless steel T301 and pressed lithographic limestone (PLL). A degree of compression of a factor of eight is achieved for PLL (Odquist parameter q≈5.5, elastic volumetric strain (EVS) 0.7, pressure 24 GPa) and a factor of 5.8 for steel T301 (q≈3, EVS 0.7, pressure 50 GPa). The distribution of elastic and plastic zones during deformation and stress distribution over the anvil-gasket contact surface are obtained, and the stagewise nature of the deformation process is revealed.

Preparation of lithium aluminate monolith of controlled porosity by a sol-gel method

Lithium aluminate (LiA102) has received much attention due to its promising use as a tritium breeding material in fusion reactors [1, 2], and as an electrolyte matrix for the molten carbonate fuel cell (MCFC) [3, 4]. LiA102 powder can be prepared by a solid-state reaction between 7-A1203 and a lithium compound such as carbonate and hydroxide, or a sol-gel method starting from metal alkoxides [11]. The sol-gel processing of LiA102 produces a powder with a better controlled ratio of lithium to aluminum due to the low processing temperature [5]. Various combinations of alkoxides of lithium and aluminum were tested to prepare LiA102 powder by Turner et al. [7]. They found that amorphous LiA102 was directly transformed to v-LiA102 at temperatures as low as 550 °C, when lithium methoxide and aluminium n-butoxide were hydrolyzed at 25 °C. Most of the research on the sol-gel route to LiA102 has involved preparation with powders; preparation methods using monolithic porous LiA102 were not seriously examined. In this letter, we propose a direct route to the preparation of pore-controlled monolithic LiA102 by a sol-gel method. Crack formation over the drying period has limited accessibility to this monolithic route [7, 8]. There have been several suggestions to avoid cracks during drying, such as DCCA (drying control chemical additive) addition [9], supercritical drying, and freeze drying [10]. The DCCA addition method has advantages over other methods. First, no costly additional equipment, such as high pressure equipment or freeze drier, is needed. Secondly, porosity can be controlled by varying the amount of DCCA or other additives such as carbon black or active carbon. Currently, fonnamide, dimethylformamide (DMF) [7, 8], glycerol, and oxalic acid [8] are widely used as a DCCA. Regarding the role of a DCCA, it is reported that the DCCA makes pore size larger and reduces capillary stress [7]. Specific roles of the DCCA, however, vary depending on the types of DCCA, and are not yet fully understood. The procedure for preparing monolithic gel is summarized in Fig. 1. Lithium isopropoxide (LiOC3H7) and aluminium isopropoxide (AI[OC3 H713), 0.05 moles of each, were mixed with 100 ml of isopropanol in a three-neck flask. This mixture was then stirred with a magnetic stirrer at 80 °C. After 2 h of stirring, yellowish brown precipitates were obtained at the bottom of the flask. These precipitates were mixed with 200 ml of ethanol, refluxing under nitrogen gas at 80 °C for 2 h. The 2012 I-'soUtrhp uomx'de ]

High-temperature synthesis of tungsten carbide in a methane-hydrogen gas medium

Tungsten carbide synthesis in a methane-hydrogen medium have been studied and the conditions for obtaining WC power with no free-carbon impurity determined. Hard alloys based on a “gas” carbide have been shown to exhibit high ductility. The results of the study have been used to develop a commercial process to produce high-ductile hard alloys for high-pressure equipment, stamping dies, and drilling tools.

Deactivation of fixed-bed nickel hydrogenation catalysts by sulfur

A series of fixed-bed nickel hydrogenation catalysts was tested in the dearomatization of hydrocarbon solvents. The mechanism of catalyst deactivation by aromatic sulfur compounds was studied in high-pressure micro-flow equipment by variation of the experimental conditions and the sulfur content of the feed. It is concluded that catalyst deactivation proceeds under mild but realistic conditions through formation of a surface sulfide which blocks the active surface. The rate of the disappearance of the active sites is a first-order process with rate constant 1.0 × 10 −3 (ppm S) −1 h −1. Under more severe conditions, more sulfide layers are formed, but bulk Ni 3S 2 was not observed even after full deactivation of the catalysts. The poisoning of the active sites in the latter case is no longer a first-order process. Consequently, under the circumstances investigated, the sulfur resistance of nickel catalysts is determined by the nickel surface area per unit weight of catalyst.

High pressure equipment for food processing

Abstract Processing food with pressure improves the quality and shelf life of the product. The pressure required is normally 600 to 900 MPa (approximately 6000 to 9000 atm). Equipment for high pressure food processing is available today from ABB Pressure Systems AB. The plant can have a through-put of 300 to 6000 litres per hour at 600 MPa pressure depending on the size of the press. The processing cost at 600 MPa is between 3 to 20 pence per litre depending on production capacity. Processing at 900 MPa instead of 600 MPa will increase the cost 50%, while prolonging the processing time from 3 minutes to 6 minutes at 600 MPa, i.e. introducing a hold time, increases the cost 100%. Pressure is thus cheaper than time. The food is prepacked in flexible material and loaded into the high pressure vessel. Pure water is used as pressure transmitting medium. The pressure is increased to the value required. After decompression the food is ready for distribution.

High pressure equipment for the food industry

Abstract Hydrostatic pressure technology is a novel non-thermal food processing technology whereby foods are subjected to high hydrostatic pressure, generally in the range of 100 to 600 MPa, at or around room temperature.

Low-Pressure Wellhead for High-Pressure Stimulation

E&P Exchange Maturity of U.S. producing wells and constrained economics dictate careful planning and strict attention to details to optimize workover and recompletion operations. One aspect of operations that can significantly reduce costs is planned preparation of a wellhead for high-pressure stimulation. Historically, there have been four basic approaches to solving old wellhead configuration problems to prepare for high-pressure stimulation down casing. Deteriorated casing and/or inadequate casing cement may dictate the method chosen. An adequate wellhead without competent tubulars will not permit high-pressure stimulation down casing. Purchase of a high-pressure wellhead with all components rated above treating pressures generally provides the least economic solution. Conventional wellhead seals in casing hangers and conventional valve designs do not adequately address pressure requirements during stimulation even if properly pressure-rated. Case histories adequately describe the weaknesses of using conventional production casing hanger seals during fracturing of a well. Several cases are documented where the seal was released, lodged against the casing hanger slips, and caused the casing to fall into the well below the casing head. Residues from stimulation (such as acid or proppant) often are found behind the seals and weaken the system so that long-term service is characterized by leaks and failures. Conventional production gate valves of proper pressure rating exhibit their own special set of performance problems and are quite expensive. These valve scan become packed with fracturing proppant and fail to close. This condition often leads to broken shear pins or twisted stems, depending on the design of the gate/stem mechanism. Loose-fitting gates and seals have low-pressure sealing problems and permit fracturing fluids to enter the operating mechanism. Stimulation fluids corrode and damage as well as permit freeze-ups during high-rate gas production or in cold weather. The wellhead isolation tool (WIT), or tree saver, was developed to circumvent these problems by retaining high-pressure stimulation fluids inside the tool during fracturing. This device isolates the wellhead from the harsh environment of the stimulation processes. The WIT must be lifted above the existing wellhead and "stabbed" into the treating string. Many of the old wells have "egged" or "burred" casing that makes installation of the WIT an expensive, major operation. The presence of the WIT mandrel restricts flow during stimulation and interferes with staging packers and perforating devices when multiple zones are to be stimulated. Because the WIT must sustain and resist damage caused by corrosive and abrasive fluids, repair costs are often significant. Erosion of the WIT mandrel must be considered when using this tool. Close tolerances, check valves, and seals must be maintained in the WIT for high-pressure service. Case histories of WIT failures usually reflect exposure of the low-pressure wellhead to stimulation pressures and proppant invasion. A lower-cost and often-used approach to configuring for high-pressure pumping is to rent a high-pressure valve and BOP. Fracturing connections and lubricators for packers or perforating equipment are exchanged between stages by breaking connections above the BOP. The rented high-pressure valve is subject to erosion, corrosion, and proppant packing as described previously. The BOP is not designed to hold pressure from above and is especially exposed to fluid erosion and proppant damage. Low initial costs are often overshadowed by expensive BOP repair charges when this approach to well preparation isused. Some recent technical developments may provide a lower-cost solution. A casing spool is now available that features an external casing seal that cannot be pumped out. This seal is extremely reliable and has functioned on many extreme-pressure (15,000-psi) jobs without a single failure. Having the seal installed in a "frac spool" is very important because it provides convenient adaption from the low-pressure casing hanger to high-pressure control equipment with safety and reliability. Casing hanger seals are isolated from the harsh stimulation environment. While the newly available spool discussed above provides a partial solution to the low-pressure-wellhead/high- pressure-stimulation problem, valve performance must also be considered. Recent improvements in gate-valve design have produced a valve that meets all required performance criteria for efficient stimulation operations. The new "frac valve" features low maintenance with close tolerances on gate/seal surfaces, low operating torque, high corrosion and erosion resistance, sealing in both directions, and generally high performance in functionality. As shown in Fig. 1, a competitive solution for high-pressure operations maybe a compact wellhead configuration with the most recent advances used throughout. The components of this fracturing tree have been used on more than600 high-pressure, high-rate, high-proppant stimulation treatments without a single performance failure. P. 383^

Proteins under pressure. The influence of high hydrostatic pressure on structure, function and assembly of proteins and protein complexes.

Oceans not only cover the major part of the earth's surface but also reach into depths exceeding the height of the Mt Everest. They are populated down to the deepest levels (approximately 11,800 m), which means that a significant proportion of the global biosphere is exposed to pressures of up to 120 MPa. Although this fact has been known for more than a century, the ecology of the 'abyss' is still in its infancy. Only recently, barophilic adaptation, i.e. the requirement of elevated pressure for viability, has been firmly established. In non-adapted organisms, increased pressure leads to morphological anomalies or growth inhibition, and ultimately to cell death. The detailed molecular mechanism of the underlying 'metabolic dislocation' is unresolved. Effects of pressure as a variable in microbiology, biochemistry and biotechnology allow the structure/function relationship of proteins conjugates to be analyzed. In this context, stabilization by cofactors or accessory proteins has been observed. High-pressure equipment available today allows the comprehensive characterization of the behaviour of proteins under pressure. Single-chain proteins undergo pressure-induced denaturation in the 100-MPa range, which, in the case of oligomeric proteins or protein assemblies, is preceded by dissociation at lower pressure. The effects may be ascribed to the positive reaction volumes connected with the formation of hydrophobic and ionic interactions. In addition, the possibility of conformational effects exerted by moderate, non-denaturing pressures, and related to the intrinsic compressibility of proteins, is discussed. Crystallization may serve as a model reaction of protein self-organization. Kinetic aspects of its pressure-induced inhibition can be described by a model based on the Oosawa theory of molecular association. Barosensitivity is known to be correlated with the pressure-induced inhibition of protein biosynthesis. Attempts to track down the ultimate cause in the dissociation of ribosomes have revealed remarkable stabilization of functional complexes under pseudo-physiological conditions, with the post-translational complex as the most pressure-sensitive species. Apart from the key issue of barosensitivity and barophilic adaptation, high-pressure biochemistry may provide means to develop new approaches to nonthermic industrial processes, especially in the field of food technology.

Determination of carbofuran by on-line immunoaffinity chromatography with coupled-column liquid chromatography/mass spectrometry.

Development of a new technology for combined on-line sample preparation and analyte confirmation is presented. This technology involves the use of antibodies for trace analyte extraction and enrichment directly from a complex matrix. The antibodies are used in columns designed for use with ordinary high-pressure liquid chromatographic equipment. The immunoaffinity columns are combined with conventional reversed-phase LC columns by use of column-switching techniques and coupled directly to an atmospheric pressure ionization quadrupole ion trap mass spectrometer equipped with a pneumatically assisted electrospray (ion spray) interface. A column of aldehyde-activated silica was used to prepare a column specific to carbofuran. This column demonstrated excellent specificity toward carbofuran and showed no binding of another, unrelated compound, fluometuron. Direct extraction and detection of carbofuran was demonstrated at low levels (40 pg/mL) in spiked water, but the real utility of immunoaffinity chromatography (IAC) is demonstrated by the on-line extraction and detection of carbofuran from a chemically complex, crude potato extract. Samples extracted using an IAC column indicate that superior purification is obtained with IAC in comparison with samples pumped directly onto a reversed-phase trapping column. A detection limit for carbofuran of approximately 2.5 ng/g of potato was obtained using an atmospheric pressure ionization quadrupole ion trap mass spectrometer.

Production of Bulk Amorphous Mg<SUB>85</SUB>Y<SUB>10</SUB>Cu<SUB>5</SUB> Alloy by Extrusion of Atomized Amorphous Powder

Amorphous Mg85Y10Cu5 powders with a particle size fraction less than 25 μm were produced by using a newly designed high-pressure argon atomization-consolidation equipment in which each content of oxygen and moisture was controlled to be less than 1 ppm. The extrusion of the amorphous powders at 373 K causes the formation of a bulk alloy having the nonequilibrium structure which is the same as that for the as-atomized powders. The thermal stability of the extruded alloy is also the same as that for the as-atomized powders. The Young’s modulus, compressive fracture strength and fracture elongation at R.T. for the bulk alloy are 46 GPa, 750 MPa and 1.8%, respectively, which are nearly the same as those for the melt-spun amorphous ribbon with the same alloy composition. The fracture surface of the bulk alloy consists mainly of a vein pattern. No appreciable trace of the original boundaries between the powders is seen and hence the powders seem to have a truely bonding state. The good consolidation tendency is presumably because of the clean surface state for the atomized powder by the use of the closed preparation equipment.

New Generation Beltpresses and Decanters for Sludge Dewatering

Stimulated by diminishing sludge disposal facilities in agriculture in the Netherlands, an increased interest has developed for improved sludge dewatering techniques. The required changeover to sludge treatment processes like composting, drying and incineration is expensive and costs are considerably influenced by extended mechanical dewatering capabilities. In cooperation with the Dutch Water Authorities and industry, DHV Water BV has been performing full-scale test programmes since 1989. Each test programme involves the treatment of various sludges, simultaneously dewatered using between two and nine different types of full-scale equipment, such as beltpresses, decanters, filterpresses and high pressure equipment. A combination of proper process design and control, together with the latest developments in the design of dewatering equipment, have resulted in dry solids percentages far higher than any reported to date. In this respect, the decanter has been shown to be an attractive alternative in many situations where filterpresses are used for the dewatering of municipal sludges.

Gasket for sealing high-pressure equipment

Gasket for sealing high-pressure equipment

High Pressure Synthesis and Magnetostrictive Measurement of Laves Phase Pr1-xRxFe2 (R=Ce, Nd)

Laves phase rare-earth iron intermetallic compounds were synthesized under high pressure and high temperature by using a double stage multianvil high pressure equipment. The minimum pressure required to synthesize the Laves phase was determined. The maximum magnetostriction of 8×10-6 was attained at room temperature for PrFe1.8.

Construction of a slim-tube equipment for gas tracer evaluation at simulated reservoir conditions

For several years the application of tracers has been a supplementary technique to monitor fluid flow in oil and gas reservoirs. This work describes the design and construction of a slim-tube equipment for evaluation of different gas tracers under reservoir conditions. The intention behind the construction and build-up of this high-pressure equipment is to study the interaction between the rock matrix and various tracer molecules, and the interaction between oil and the tracer molecules. Chemical tracers, i.e. perfluorinated hydrocarbons, are analysed on-line by gas chromatography with EC-detection. Radioactively labelled tracer gases are analysed by automatic sample collection followed by liquid scintillation counting directly on the gas phase.

産業用高圧装置の現状と食品加工への応用

Recently, a large number of high pressure equipments have been utilized in industry for high-pressure food processing, forming and sintering of powdered materials and many other purposes.In this paper, recent progress in industrial high pressure technology is reviewed. Among various high pressure equipments, cold isostatic pressing (CIP) is being utilized most in high-pressure food processing. The method and constitution of CIP are described together with its recent progress and applicability to food processing.

The scope for pressing and sintering diamond-bearing components in shock waves

The most highly stressed materials of that type are diamond-bearing composites having matrices composed of tungsten-cobalt hard alloys (slavutich and tvesal) [2, 3]. Those composites are made by hot pressing and have extremely high wear resistance, but they disintegrate rapidly because of their low strength under conditions of dynamic or cyclic loading. Their physicomechanical properties do not meet the rapidly tightening industrial requirements. The main factor responsible for weakening is the damage to the diamond grains, which is due to the cracking in them when the structure is formed [4, 5]. The physical significance can be evaluated from the proportion of grains containing cracks in unit volume. Grain-size analyses on recovered diamond grains have shown that the damage is functionally related to the mode of sintering, the diamond grade, the grain size, and the diamond concentration [4, 6]. Diamonds are damaged during hot pressing not only because of the solvent metal inclusions they contain, the technological defects, and the state of strain in the mold, but also because the method is used at P and T such that the diamond does not pass from the brittle state to the plastic one. High-pressure equipment has substantially reduced the damage to the diamond grains [5] and thus confirms that P and T influence the damage. A second factor that reduces the strength is the stress concentration near the diamond grains. However, the strength of tvesal as a function of diamond grain size below which stress concentration does not occur and the composite can be considered as a macroscopically homogeneous medium damaged by the joint action of the uniformly distributed residual temperature-dependent and mechanical stresses [6, 7].

Hydrogenation of residual oil using an ore derived water soluble ammonium molybdate catalyst

Hydrogenation of residual oil, though attractive, has been expensive due to hydrogen requirements, high pressure equipment, and high cost of a generally used cobalt-molybdenum supported catalyst. In this study hydrogenation of atmospheric residual oil (260 °C +) with API gravity of 16 (20 °C) and viscosity of 252 × 10 −3 Pa s (30 °C) is carried out in an internally stirred autoclave in the presence of a dispersed water soluble unsupported ammonium molybdate catalyst prepared from a molybdenum ore. This provides an effective economic alternative to the use of expensive supported commercial catalysts for the hydrogenation of residual oil. The most suitable hydrogenation experimental conditions for the hydrogenation of residual oil were found to be 0.216% molybdenum based on residual oil, 13.8 MPa pressure, 405 °C reactor temperature, and 30 min reaction time. Under these conditions, API gravity of the product oil increased to 23 with a decrease in viscosity to 16.6 × 10 −3 Pa s. An ASTM distillation of the hydrogenated residual product gave 34% liquid boiling below 235 °C.

Acoustic emission from zinc under pressure

Abstract The kinetics of some processes in materials under high hydrostatic pressure can be investigated with an acoustic emission method after a special adaptation of the high pressure equipment. The method has been applied for studying the effect of compression anisotropy in hcp polycrystalline material - zinc.

Technological and design specifics of high-pressure equipment developed by vniimetmash

Abstract New high-pressure machinery designed by Vniimetmetmash.

STUDY ON PHASE TRANSITION IN SMSC Cd1-xMnxSe UNDER HIGH PRESSURE

Using diamond-anvel cell high pressure equipment, the phase transition of Cd1-xMnxSe under high pressure has been measured by optical absorption and X-ray diffraction methods, It has been found that the phase transition is irreversible. Under common pressure, Cd1-xMnxSe has wurzite structure, but it transforms to Nad structure under high pressure. When the pressure is removed, Cd1-xMnxSe becomes zinc blend structure. In addition, the relation between the pressure of phase transition and component x is also obtained.