Multiphase Bulk Solids Flow Systems

1980 ◽  
Vol 102 (2) ◽  
pp. 129-132
Author(s):  
R. B. Emery
Keyword(s):  
Soil Mechanics ◽  
Fluid Pressure ◽  
Pressure Control ◽  
Multiphase System ◽  
Mechanical Loads ◽  
Bulk Solids ◽  
Design Goal ◽  
Flow Systems ◽  
Quantitative Design ◽  
Design Construction

Theory and proof are presented here related to fluid pressure control of bulk solids flowability. They are directed toward a quantitative design goal for fluid-solids flow systems. An effort is made to relate multiphase system concept to existing soil mechanics, strength of material and bulk solids flow theory. Gas or liquid interstitial loads often add cumulative effects to the mechanical loads normally considered in bulk solids flow systems. Summation of the mechanical, gas and liquid loads form the basis for multiphase system design. Useful savings in design, construction and maintenance are expected from application of multiphase theory. Quantitative design can, in some cases, provide flow, no-flow, or a controlled combination of flow and no-flow.

Concepts of Multiphase Flow Related to the Jenike Design Method

1974 ◽  
Vol 96 (3) ◽  
pp. 936-939
Author(s):  
R. B. Emery
Keyword(s):  
Interstitial Fluid ◽  
Design Method ◽  
Fluid Pressure ◽  
Bulk Solids ◽  
Design Goal ◽  
Bulk Solid ◽  
Liquid Moving ◽  
Flow Systems ◽  
Quantitative Design ◽  
Flow Functions

Hypotheses are presented here for improving bulk solids flowability. They are directed toward a quantitative design goal for gas-solids flow systems. An effort is made to relate gas control in gas-solids flow systems to the Jenike design method. Cohesion and friction in slumped beds are frequent barriers to flow. Gas or liquid moving through bulk solids interstices can reduce interparticle cohesion. Changes in interstitial fluid pressure can modify friction angles and so change channel flow factors and bulk solid flow functions. Mass flow can be achieved in gas-solids flow systems using comparatively large hopper half apex angles.

Plug Flow of Bulk Solids Using Gas Pressure Control

1979 ◽  
Vol 101 (1) ◽  
pp. 85-89
Author(s):  
R. B. Emery
Keyword(s):  
Interstitial Fluid ◽  
Stress Ratio ◽  
Plug Flow ◽  
Fluid Pressure ◽  
Pressure Control ◽  
Gas Pressure ◽  
Bulk Solids ◽  
Converging Channel ◽  
Slot Opening ◽  
Powdered Coal

This paper considers interstitial fluid pressure as an additional characteristic effecting bulk solids flowability. It describes a method for improving flow control of cement, powdered coal, sand, etc. through a converging hopper by applying particle stress-ratio control. In some applications, flowability of bulk solids can be modified rather than make costly modifications to the hopper. The patented method combines a baffle, a slot opening and gas pressure control modifying flowability in a converging channel. Plug-flow, a preferred type of mass flow, has been achieved flowing cement through hoppers open to the atmosphere as well as through enclosed, pressurized hoppers.

scholarly journals Correction to: Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Kodai Nakagomi ◽  
Toshiko Terakawa ◽  
Satoshi Matsumoto ◽  
Shinichiro Horikawa
Keyword(s):  
Fluid Pressure ◽  
Pressure Control ◽  
Pore Fluid ◽  
2016 Kumamoto Earthquake ◽  
Pore Fluid Pressure ◽  
Seismicity Rate ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Seismicity Rate Changes

An amendment to this paper has been published and can be accessed via the original article.

Controlling the Height of Multiple Hydraulic Fractures in Layered Media

SPE Journal ◽  
2016 ◽  
Vol 21 (01) ◽  
pp. 256-263 ◽  
Author(s):  
Aditya Khanna ◽  
Andrei Kotousov
Keyword(s):  
Fluid Pressure ◽  
Pressure Control ◽  
Shielding Effect ◽  
Hydraulic Fractures ◽  
Fracturing Fluid ◽  
Fracture Spacing ◽  
Gas Recovery ◽  
Fracture Opening ◽  
Fracture Height ◽  
Fracture Height Containment

Summary Fracture-height containment is desirable in hydraulic-fracturing treatments because it can result in better efficiency of oil or gas recovery and have less impact on the environment. Several mechanisms of the containment of a single hydraulic fracture were investigated in the past, and the outcomes of these studies are now well-documented in the open literature. However, the effectiveness of these mechanisms in the case of multiple closely spaced hydraulic fractures has not received much attention. The latter situation typically arises in the case of multiple transverse fractures emanating from a single horizontal wellbore. In this paper, we develop a mathematical model that one can use to assess the fracture-interaction phenomenon as well as the effect of the modulus contrast between adjacent rock layers. We consider the situation in which one must contain the hydraulic fractures entirely in the pay zone and investigate fracturing-fluid-pressure control as a possible mechanism of height containment. It is demonstrated that when the fracture spacing becomes comparable with the fracture height, the interaction between the fractures produces a shielding effect. In this case, the fracturing-fluid pressure that ensures fracture containment is greater in comparison with the case of a single isolated fracture. However, the fracture opening is also smaller in the case of closely spaced fractures. The dependence of the fracturing-fluid pressure and fracture opening on the fracture spacing needs to be taken into consideration during the selection of fracture spacing for a particular treatment.

The chemical potential in thermodynamic systems under non-hydrostatic stresses

1968 ◽  
Vol 307 (1488) ◽  
pp. 1-13 ◽  
Keyword(s):  
Thermodynamic Equilibrium ◽  
Chemical Potential ◽  
Normal Component ◽  
Fluid Pressure ◽  
Multiphase System ◽  
Phase System ◽  
Hydrostatic Stresses ◽  
Discontinuous Displacement ◽  
Multi Phase ◽  
Work Done

It is proved that a chemical potential μ v = u v – Ts v + pv v may be introduced for every chemical component v which may be considered a possible component everywhere in a multiphase system in thermodynamic equilibrium under non-hydrostatic stresses, where —3 p is the trace of the stress tensor. It is a condition of equilibrium that μ v has the same value throughout such a system and it is shown that in a virtual infinitesimal variation d U = T d S + d W + Ʃ v μ v d N v , where U, S are the total energy and entropy of the multi-phase system, and d W is the total mechanical work done on the system. At an interface between phases where a discontinuous displacement is permitted, it is shown also that μ v = u v - Ts v + P n v v , for both phases in contact at the interface, P n being the normal component of the pressure at the interface. In a system in which each phase is under a uniform stress and is connected to at least one other phase by such an interface, all phases at equilibrium must thus have the same value of p , and the normal component of the pressure at every such interface must also be p . An important example of this latter result is that of a fluid-solid system, for which, if p is the fluid pressure, the solid must be under an equal hydrostatic pressure p together with a shear stress whose principal directions are perpendicular to the normal of the interface, this new result representing a considerable restriction on the possible stress in a solid at chemical equilibrium with the fluid. The chemical potential is not assumed to exist but is introduced as an undetermined multiplier in the application of the Gibbs condition of thermodynamic equilibrium, and all its important properties are deduced. The same method may be applied more simply in hydrostatic cases.

Mechanical Spring Replacement With Pneumatic Return Device in a Valve Train: Effects on Dynamics and Preload Tuning

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Pastorelli Stefano ◽  
Almondo Andrea ◽  
Sorli Massimo
Keyword(s):  
High Speed ◽  
Dynamic Stiffness ◽  
Fluid Pressure ◽  
Time History ◽  
Pressure Control ◽  
Transmission Efficiency ◽  
Valve Train ◽  
Internal Resonances ◽  
Return Spring ◽  
Mechanical Spring

The paper presents a comparison of performance for a cam transmission of an engine valve train operating with a mechanical spring and with a return spring device that uses a pneumatic spring. Dynamic analysis of the cam mechanism is performed in the frequency and time domains employing a combined lumped-distributed parameter model capable of predicting the effects of the higher harmonics of the cam lift profile on system performance, in particular of the return spring device. Dynamic stiffness of the transmission in the frequency domain and time history of the contact force between cam and follower are evaluated. The limits of the traditional mechanical spring-closing system at high-speed camshaft operations are investigated, highlighting that they are mainly imposed by the internal resonances of the spring. The pneumatic spring is an improved replacement of the steel spring because of better dynamic behavior. Furthermore, the pneumatic return device allows preload tuning of the spring, which may increase transmission efficiency through proper control of the fluid pressure. Study of the pressure control circuit is also presented.

Experiment and Simulation on Pressure Pulsation Accompanied by Acoustic Resonance and Piping Vibration

2011 ◽  
Author(s):  
Takashi Tsuji ◽  
Akira Maekawa ◽  
Tsuneo Takahashi ◽  
Michiyasu Noda ◽  
Minoru Kato ◽  
...  
Keyword(s):  
Pressure Pulsation ◽  
Fluid Pressure ◽  
Control Valve ◽  
Acoustic Resonance ◽  
Pressure Control ◽  
Piping System ◽  
Knowing That ◽  
Opening Ratio ◽  
Pressure Control Valve ◽  
Improve Condition

To improve condition-based maintenance (CBM) techniques for operating plants, it is necessary to investigate, by experiments and numerical simulations, on the behavior of fluid inside piping system in detail. This study was conducted using the full-scale piping system under conditions that could seriously threaten the plant operation, by matching pressure pulsation, acoustic resonance and piping natural frequency. Although piping vibration is reported to influence fluid pressure pulsation, there were few examples of such influence in the conditions of this experiment. Knowing that the opening ratio of the pressure control valve affects the boundary condition for acoustic resonance, the experiment and numerical simulation at different opening ratios were conducted. It was suggested that there are cases in which a valve partially open at 25% or less shouldn’t be taken as a closed end. This finding conflicts with widespread design assumption.

Sign in / Sign up

Export Citation Format

Share Document