The Experts below are selected from a list of 97215 Experts worldwide ranked by ideXlab platform
Ying Zheng - One of the best experts on this subject based on the ideXlab platform.
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overall Pressure Balance and system stability in a liquid solid circulating fluidized bed
Chemical Engineering Journal, 2000Co-Authors: Ying ZhengAbstract:Abstract A Pressure Balance analysis has been carried out, along with a dimensionless empirical correlation for the solids holdup in the riser and a semi-empirical equation for the Pressure drop across the non-mechanical control valve derived in this work, to successfully predict the stable operating conditions and explain the origin of the unstable operation phenomena of the liquid–solid circulating fluidized bed. The effects of the total and auxiliary liquid velocity, the solids inventory and the unit geometry on the stable operation range are discussed. Furthermore, this work also reveals the importance of unit structure in improving the performance of the liquid–solid circulating fluidized bed systems.
Tokihiko Kobata - One of the best experts on this subject based on the ideXlab platform.
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a high gas Pressure calibration system using a liquid lubricated Pressure Balance
Measurement, 2017Co-Authors: Hideaki Iizumi, Hiroaki Kajikawa, Tokihiko KobataAbstract:Abstract We developed a high gas Pressure calibration system that uses a liquid-lubricated (LL) Pressure Balance as a standard for Pressures up to 100 MPa. The LL Pressure Balance can generate gas or hydraulic Pressure by changing the Pressure medium. We first evaluate characteristics of the LL piston–cylinder (PC), such as its effective area and fall rate. The effective area of the LL PC is evaluated through comparison with a hydraulic Pressure Balance. When the LL PC uses a gas, the fall rate is affected by gas dissolution into liquid in the LL PC reservoir. The results of calibrating a Pressure gauge under the developed system are consistent with those by an existing hydraulic Pressure calibration system.
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Development of low-Pressure calibration system using a Pressure Balance
Measurement, 2012Co-Authors: Momoko Kojima, Tokihiko KobataAbstract:Abstract A new calibration system for low-Pressure is now under development at NMIJ/AIST. The new system is designed to calibrate Pressure transducers in the Pressure range of less than 10 kPa in absolute mode. The Pressure generation technique needs only a single Pressure Balance and the Pressure in the bell-jar is used as a calibration Pressure instead of the system Pressure. In this paper, the outline of the calibration system and the measurement results are described.
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Long-term evaluation of effective area ratio of Pressure Balances
2010Co-Authors: Tokihiko Kobata, Momoko Kojima, Hiroaki KajikawaAbstract:A Pressure Balance is a device that is implemented directly from the basis of the definition of Pressure and can be used as a Pressure standard. Its main components are a piston-cylinder assembly and weights. The force generated under the weight whose mass has been measured precisely is exerted on the piston. When the Pressure is applied to float the piston under load up to the equilibrium level, this Pressure is defined by dividing the force by the effective area of the piston-cylinder assembly. The most important factor in determining the precise Pressure generated by the Pressure Balance is the effective area. Comparative measurement of reference and test Pressure Balances using the cross-float method is widely used to calibrate the unknown Pressure generated by the test Pressure Balance. From the measurement results, the effective area ratio of the two Pressure Balances is obtained. We have evaluated effective area ratios of two Pressure Balances in various combinations on a regular and systematic basis. In this article, some typical examples are given.
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Progress in development of controlled-clearance Pressure Balance in NMIJ
Journal of Physics: Conference Series, 2010Co-Authors: H Kajikawa, K Ide, Tokihiko KobataAbstract:A new controlled-clearance Pressure Balance is under development with the aim of improving the hydraulic high-Pressure standard up to 1 GPa. This Pressure Balance consists of three parts: (i) a Pressure generation device up to 1 GPa, (ii) a weight-loading unit which can load/unload weights automatically and independently, (iii) a controlled-clearance piston-cylinder which is designed to allow the jacket Pressure to be applied independently. Some adjustments were made for loading heavy weights on/off the piston safely, keeping them in Balance, then generating the Pressure stably. Stability of the generated Pressure was checked for several piston-cylinders, and it was found that Pressure fluctuation was less than a few parts per million. The jacket Pressure coefficient of a 500 MPa controlled-clearance piston-cylinder was precisely evaluated as a function of both the system Pressure and the jacket Pressure.
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COMPARISON BETWEEN GAS AND HYDRAULIC Pressure BalanceS USING A LIQUID-LUBRICATED Pressure Balance
2009Co-Authors: Tokihiko KobataAbstract:A method for comparing Pressures of different mediums generated by gas and hydraulic Pressure Balances is examined to improve consistency between gas and hydraulic Pressure-standards. The Pressure range compared is 0.5 MPa to 7 MPa. In the method, a liquid- lubricated Pressure Balance was used and a precise Pressure transducer was applied as a comparator to determine the equilibrium state between the two Pressure Balances. In this paper, the comparative result and the uncertainty obtained from the method are presented. From the results, it was shown that the method adopted in this study could be used to compare gas and hydraulic Pressure Balances accurately.
Liu Ren-huan - One of the best experts on this subject based on the ideXlab platform.
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Study on Pressure Balance in a single-loop solid circulation fluidized-bed system
Journal of China University of Petroleum, 2006Co-Authors: Liu Ren-huanAbstract:The relation of Pressure Balance must be kept properly in a circulation loop for keeping a fluidized-bed unit in working order.The Pressure Balance of a single-loop solid circulation system was experimentally studied in a gas-solid fluidized-bed test facility with the diameter of 800 mm and the height of 12?000 mm by multi-point Pressure detector.It is shown that the Pressure Balance is in close relation with the fluidized bed operation status and solid circulation rate.The measured Pressure curve of the whole loop takes the shape of "8".In the upper dilute region of the fluidized bed,its Pressure is higher than that of the dipleg,while in the lower dilute region of the fluidized bed,its Pressure is lower than that of the dipleg.With the increase of fluidization velocity,the solid circulation rate increases.The distributions of voidage in fluidized bed and dipleg are both trending upwards on the top and downwards at the bottom.The distribution of Pressure in a single loop depends on the properties of fluidized bed and cyclone.
Daniele Peila - One of the best experts on this subject based on the ideXlab platform.
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feasibility study of tar sands conditioning for earth Pressure Balance tunnelling
Journal of rock mechanics and geotechnical engineering, 2015Co-Authors: Daniele Martinelli, Daniele Peila, Enrico CampaAbstract:Abstract This paper presents the results of laboratory test on the feasibility of soil conditioning for earth Pressure Balance (EPB) excavation in a tar sand, which is a natural material never studied in this respect. The laboratory test performed is based on a procedure and methods used in previous studies with different types of soils, but for this special complex material, additional tests are also conducted to verify particular properties of the tar sands, such as the tilt test and vane shear test usually used in cohesive materials, and a direct shear test. The laboratory test proves that the test procedure is applicable also to this type of soil and the conditioned material can be considered suitable for EPB excavations, although it is necessary to use a certain percentage of fine elements (filler) to create a material suitable to be mixed with foam. The test results show that the conditioned material fulfils the required standard for an EPB application.
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earth Pressure Balance tunnelling in rock masses laboratory feasibility study of the conditioning process
Tunnelling and Underground Space Technology, 2013Co-Authors: Daniele Peila, Andrea Picchio, Alessio ChieregatoAbstract:Abstract Earth Pressure Balance (EPB) shield tunnelling is considered to be an effective tunnelling method when surface settlements must be avoided by controlling face stability and underground water inflow. EPB technology is applied increasingly to the conditioning of rock masses in which the presence of polluting material is foreseen and must be controlled, or when explosive gases from the rock mass must be prevented from entering in the machine. The use of an EPB machine in ‘closed mode’ can prevent the dispersion of dangerous materials in the underground environment. This study was performed to evaluate the feasibility of using EPB technology in rock masses and the effectiveness of this tunnelling process in terms of soil conditioning, conditioned soil permeability, Pressure transmission on the tunnel face, and the ability to extract the material with a screw conveyor. The research was developed with a set of laboratory tests carried out on three different types of rock masses where tunnelling with EPB machines are planned to be constructed in Italy but the results can be easily applied to similar rock mass types. The tests have been carried out both with slump tests and with a specially constructed screw conveyor extraction device. In the paper the most important results are presented and discussed.
C M Sutton - One of the best experts on this subject based on the ideXlab platform.
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The feasibility of a watt Balance based on twin Pressure Balances
2016 Conference on Precision Electromagnetic Measurements (CPEM 2016), 2016Co-Authors: C M Sutton, M T Clarkson, W M KisslingAbstract:In previous work at MSL, the concept of a watt Balance based on twin Pressure Balances was proposed both for a measurement of the Planck constant and for a non-artefact realisation of the kilogram. Here, further developments of the concept are described including a novel magnet system suitable for use in a Pressure Balance based watt Balance. The feasibility of such a watt Balance achieving an accuracy (relative standard uncertainty) of about 2 parts in 108 is considered, focusing mainly on alignment and Pressure Balance performance characteristics.
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A method of analysis for cross-floats between Pressure Balances
Metrologia, 2005Co-Authors: C M Sutton, M P Fitzgerald, W GiardiniAbstract:We present a method of analysis for cross-floats between Pressure Balances. This analysis relates to the residual mass method of treating cross-float data in which the residual mass Me of one Pressure Balance is an unknown in the analysis, along with the effective area and the elastic distortion coefficient. Me is the effective mass of any unweighed parts of the piston and load and may include an equivalent mass for other forces on the piston such as oil surface tension. Two models for the analysis with the Me method are presented in a form suitable for linear least squares analysis: one for the calibration of a Pressure Balance and the other for the comparison of two reference Pressure Balances. This analysis is equivalent to the p-method when Me is known to be zero. Linear generalized least-squares estimation is shown to be convenient for the calculations. A Pressure Balance calibration is used to illustrate the analysis and the associated uncertainty evaluation.
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The Pressure Balance as an Absolute Pressure Standard
Metrologia, 1994Co-Authors: C M SuttonAbstract:Gas-operated Pressure Balances as primary standards for absolute Pressure are discussed, with emphasis on obtaining the effective area from the piston-cylinder dimensions and the mass in vacuum of the Pressure Balance floating element. The performance of one 35 kPa Pressure Balance is presented showing that an accuracy of better than 10 ppm can be achieved. Repeat measurements of the piston-cylinder dimensions ten years apart gave the same calculated effective areas to within 3 ppm. These calculated areas vary by up to 2 ppm with gas Pressure and gas type. Comparison with two interferometric manometers, using other nitrogen gas-operated Pressure Balances as transfer standards, resulted in effective areas -7 ppm and 2,6 ppm different from the area calculated from the piston-cylinder dimensions.
