scholarly journals Decrease of Nozzle Clogging through Fluid Flow Control

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1420 ◽  
Author(s):  
Enif Gutiérrez ◽  
Jose de Jesus Barreto ◽  
Saul Garcia-Hernandez ◽  
Rodolfo Morales ◽  
María G. González-Solorzano
Keyword(s):  
Boundary Condition ◽  
Deposition Rate ◽  
Raw Materials ◽  
Internal Flow ◽  
Inclusion Size ◽  
General Boundary Condition ◽  
Nozzle Clogging ◽  
Flow Modification ◽  
Internal Surfaces ◽  
Plant Trials

Decreasing the clogging deposition rate of alumina inclusions in continuous casting nozzles is possible through three simultaneous measures: Flow modification, use of raw materials with low impurities contents, and smoothed internal surfaces. The control of the internal flow consists on avoiding dead regions and developing symmetric patterns. A mathematical model performed tests of the feasibility of these measures. The adherence of inclusions to the nozzle wall, using this model, employs a boundary condition based on the thickness of the sublaminar boundary instead of the conventional “trap” boundary condition. The use of the general boundary condition yields deposition rates that are unaffected by the inclusion size. The proposed boundary condition discriminates against the clogging deposition rate through the particle sizes. Plant trials complemented with water modeling, using these nozzles, proved that the present approach could considerably decrease the clogging occurrence.

Additions of Salt Cake and KAlF4 from Aluminum Production to Steelmaking Slags

2012 ◽  
Vol 31 (4-5) ◽  
pp. 529-537
Author(s):  
G.A. Sweet ◽  
S. Ferenczy ◽  
W.F. Caley ◽  
G.J. Kipouros
Keyword(s):  
Raw Materials ◽  
Aluminum Production ◽  
Secondary Aluminum ◽  
Promising Alternative ◽  
Salt Cake ◽  
Steelmaking Slags ◽  
Alternative Means ◽  
Temperature Operating ◽  
Plant Trials

AbstractFluorspar, a mineral primarily composed of CaF2 is the most commonly used slag fluidizer in steelmaking. Due to increasing costs for fluorspar steelmakers are seeking alternative means of achieving slag fluidity. The research has concentrated on other minerals or the wastes of other high temperature operating industries. A promising alternative to fluorspar has been identified in a previous work from this laboratory which is the salt cake from secondary aluminum production such as the flux in remelting aluminum scrap and dross. This material is widely available and also considered toxic (meaning that use in steelmaking helps to reduce environmental impacts from disposal). The present work is an investigation of the viability of using mixtures of salt cake and KAlF4 in slag-fluidizing applications by measurements of viscosity and weight loss at high temperatures (to evaluate whether large amounts of potentially harmful gases are formed). In addition, characterization of raw materials and melted slags has been performed. In terms of fluidity the mixtures of aluminum salt cake and KAlF4 are qualified for use as fluidizers. The results of the present study will be used to design plant trials.

General boundary-condition recalculation algorithm for temperature fields of different geometry

1983 ◽  
Vol 45 (5) ◽  
pp. 1294-1297 ◽  
Author(s):  
G. T. Aldoshin ◽  
A. S. Golosov ◽  
V. I. Zhuk ◽  
D. N. Chubarov
Keyword(s):  
Boundary Condition ◽  
Temperature Fields ◽  
General Boundary ◽  
General Boundary Condition

Bending of a circular plate with an eccentric circular patch symmetrically loaded with respect to its centre

1956 ◽  
Vol 52 (3) ◽  
pp. 584-598 ◽  
Author(s):  
W. A. Bassali ◽  
R. H. Dawoud
Keyword(s):  
Boundary Condition ◽  
Circular Plate ◽  
Complex Variable ◽  
Poisson’S Ratio ◽  
Complex Variable Method ◽  
Variable Method ◽  
Poisson's Ratio ◽  
General Boundary ◽  
General Boundary Condition ◽  
Circular Patch

ABSTRACTThe complex variable method is applied to obtain solutions for the deflexion of a supported circular plate with uniform line loading along an eccentric circle under a general boundary condition including the clamped boundary , a boundary with zero peripheral couple , a boundary with equal boundary cross-couples , a hinged boundary and a boundary for which , η being Poisson's ratio. These solutions are used to obtain the deflexion at any point of a circular plate having an eccentric circular patch symmetrically loaded with respect to its centre. Expressions for the slope and cross-couples over the boundary and the deflexions at the centres of the plate and the loaded patch are obtained.

Pipeline Coating Failures and Preventions

2019 ◽  
Author(s):  
Manish Jain ◽  
Piyush Thakor
Keyword(s):  
Oil And Gas ◽  
Gap Analysis ◽  
Internal Flow ◽  
Gas Pipelines ◽  
Corrosion Failure ◽  
Internal Surfaces ◽  
Depth Analysis ◽  
Electro Osmosis ◽  
Flow Improvement ◽  
External Coating

The coating and cathodic protection protect pipeline against the corrosion. The failure of these two defense systems leads to corrosion failure of pipelines. Any changes in chemical, physical or electrochemical properties of coating which affect their properties to isolate tFhe pipes from the corrosive atmosphere is considered as failure of coating. The failure mechanism and the gap analysis need to be continuously done for improvements in specifications and its executions. Majority of the global oil and gas pipelines are being protected externally with either 3-Layer Polyolefin coating system or fusion bonded coatings. Some of the gas pipelines are provided with a flow improvement internal coatings considering nil corrosive challenges on internal surfaces. The failures in the external coating appear in the form of edge disbondment from cutbacks and near holidays, complete loss of adhesion of coating, loss of cohesion within coating, cracking in the coating, swelling & blistering around holidays, distortions in the coating, electro osmosis, electrophoresis and highly alkaline atmosphere near holidays, continual increase in CP currents and corrosion of the substrate. The internal surfaces of pipes are suffering corrosion mainly due to presence of corrosive gases viz. carbon dioxide, oxygen, condensates and other corrosive substances even in traces. The common methods like Dehydration, Inhibitors, Buffering, Biocide and Cleaning pigs are not adequate to protect the pipelines to from the corrosion. A very thin internal flow coat can hardly resist any corrosion and gets failed. This paper presents the in-depth analysis of the major causes of coating failures and the improvements required in the external and internal coating selections, specifications, coating applications, testing and its maintenance.

Bending of an Elastically Restrained Circular Plate Under Normal Loading Over a Sector

1958 ◽  
Vol 25 (1) ◽  
pp. 37-46
Author(s):  
W. A. Bassali ◽  
R. H. Dawoud
Keyword(s):  
Boundary Condition ◽  
Circular Plate ◽  
Complex Variable ◽  
Variable Method ◽  
General Boundary Condition ◽  
Single Treatment ◽  
Normal Loading ◽  
Simply Supported ◽  
Thin Circular Plate ◽  
Elastically Restrained

Abstract The complex variable method is used to find the deflection, bending and twisting moments, and shearing forces at any point of a thin circular plate normally loaded over a sector and supported at its edge under a general boundary condition including the usual clamped and simply supported boundaries. In this way separate treatments for these two cases are avoided and a single treatment is available.

Stability and sensitivity analysis in a simplified solid rocket motor flow

2013 ◽  
Vol 722 ◽  
pp. 618-644 ◽  
Author(s):  
G. Boyer ◽  
G. Casalis ◽  
J. L. Estivalèzes
Keyword(s):  
Boundary Condition ◽  
Sensitivity Analysis ◽  
Global Stability ◽  
Internal Flow ◽  
Numerical Data ◽  
Base Flow ◽  
Solid Rocket Motor ◽  
Inflow Boundary Condition ◽  
Convergence Zones ◽  
Solid Rocket

AbstractThe present article aims at enhancing the computation of the global stability modes of the internal flow of solid rocket motors (SRMs) approximated by the Taylor–Culick solution. This modal approach suffers from the consequences of the non-normality of the global linearized incompressible Navier–Stokes operator, namely the lack of robustness of the eigenvalues that can lead to the computation of pseudo-modes rather than actual eigenmodes. In this respect, the effects of non-normality associated with strongly amplified eigenfunctions are highlighted on a simplified convective–diffusive stability problem with uniformly accelerated base state, the latter property being a typical characteristic of the Taylor–Culick flow. Non-convergence zones for the eigenvalues are exhibited for large Reynolds numbers and are related to the critical sensitivity to disturbances applied to one of the boundary conditions. For this reason, and according to experimental and numerical data related to the stability of simplified SRMs, a global stability analysis is performed assuming that the hydrodynamic fluctuations emerge from a geometrical defect applied at the sidewall. This comes to fix the upstream boundary condition at the abscissa of the sidewall disturbance. The resulting eigenmodes are shown to be discrete, numerically converged, well identified by a finite number of points of undefined phase of the velocity fluctuations. They marginally depend on Reynolds number variations, but are modified by changes on the boundaries location. As in the simplified problem, the inflow boundary condition is the most critical in terms of sensitivity to numerical errors, although not dramatic. Finally, the sensitivity analysis to infinitesimal base flow changes indicates that the variations applied close to the inflow boundary condition induce the largest move of the eigenvalues. In spite of the large non-normal effects induced by the large polynomial growth of the eigenfunctions, this paper shows that discrete instabilities may emerge from a wall defect, in contrast to configurations without such a geometrical perturbation whose dynamics may be rather driven by pseudo-modes.

ESTIMATES OF SOLUTIONS OF IMPULSIVE PARABOLIC EQUATIONS AND APPLICATION

2008 ◽  
Vol 01 (02) ◽  
pp. 257-266
Author(s):  
GUOHUA SONG
Keyword(s):  
Boundary Condition ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Parabolic Equations ◽  
Population Biology ◽  
Model Problem ◽  
General Boundary ◽  
General Boundary Condition ◽  
Estimates Of Solutions

This paper is concerned with the estimates of solutions for an impulsive parabolic equations under general boundary condition. We prove that the solutions of impulsive parabolic equations can be controlled and estimated by the solutions of dominating impulsive ordinary differential equations. We also apply the above results to a model problem arising from population biology.

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