Effect of Baffle Clearance on Scale Deposition in an Agitated Vessel

Mechanical energy dissipation was investigated in a cylindrical, flat bottomed vessel with four radial baffles and the pitched blade turbine impeller of varied size. This study was based upon the experimental data on the hydrodynamics of the turbulent flow of water in an agitated vessel. They were gained by means of the three-holes Pitot tube technique for three impeller-to-vessel diameter ratio d/D = 1/3, 1/4 and 1/5. The experimental results obtained for two levels below and two levels above the impeller were used in the present study. Radial profiles of the mean velocity components, static and total pressures were presented for one of the levels. Local contribution to the axial transport of the agitated charge and energy was presented. Using the assumption of the axial symmetry of the flow field the volumetric flow rates were determined for the four horizontal cross-sections. Regions of positive and negative values of the total pressure of the liquid were indicated. Energy dissipation rates in various regions of the agitated vessel were estimated in the range from 0.2 to 6.0 of the average value for the whole vessel. Hydraulic impeller efficiency amounting to about 68% was obtained. The mechanical energy transferred by the impellers is dissipated in the following ways: 54% in the space below the impeller, 32% in the impeller region, 14% in the remaining part of the agitated liquid.

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The role of acetic acid in FeCO3 scale deposition on CO2 corrosion of API X65 carbon steel under high temperatures

Corrosion Engineering Science and Technology ◽

10.1080/1478422x.2021.1920171 ◽

2021 ◽

pp. 1-12

Author(s):

Bernardo Augusto Farah Santos ◽

Rhuan Costa Souza ◽

Maria Eduarda Dias Serenario ◽

Eugenio Pena Mendes Junior ◽

Thiago Araujo Simões ◽

...

Keyword(s):

Acetic Acid ◽

Carbon Steel ◽

High Temperatures ◽

Co2 Corrosion ◽

Scale Deposition

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Additive-Enhanced Exfoliation for High-Yield 2D Materials Production

Nanomaterials ◽

10.3390/nano11030601 ◽

2021 ◽

Vol 11 (3) ◽

pp. 601

Author(s):

Dinh-Tuan Nguyen ◽

Hsiang-An Ting ◽

Yen-Hsun Su ◽

Mario Hofmann ◽

Ya-Ping Hsieh

Keyword(s):

Large Scale ◽

2D Materials ◽

Transition Metal Dichalcogenides ◽

Spectroscopic Characterization ◽

High Yield ◽

Nanometer Scale ◽

Efficient Production ◽

Device Performance ◽

Metal Dichalcogenides ◽

Scale Deposition

The success of van-der-Waals electronics, which combine large-scale-deposition capabilities with high device performance, relies on the efficient production of suitable 2D materials. Shear exfoliation of 2D materials’ flakes from bulk sources can generate 2D materials with low amounts of defects, but the production yield has been limited below industry requirements. Here, we introduce additive-assisted exfoliation (AAE) as an approach to significantly increase the efficiency of shear exfoliation and produce an exfoliation yield of 30%. By introducing micrometer-sized particles that do not exfoliate, the gap between rotor and stator was dynamically reduced to increase the achievable shear rate. This enhancement was applied to WS2 and MoS2 production, which represent two of the most promising 2D transition-metal dichalcogenides. Spectroscopic characterization and cascade centrifugation reveal a consistent and significant increase in 2D material concentrations across all thickness ranges. Thus, the produced WS2 films exhibit high thickness uniformity in the nanometer-scale and can open up new routes for 2D materials production towards future applications.

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A two-dimensional model for the secondary flow in an agitated vessel with anchor impeller.

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN ◽

10.1252/jcej.18.81 ◽

1985 ◽

Vol 18 (1) ◽

pp. 81-84 ◽

Cited By ~ 25

Author(s):

MASAKATSU OHTA ◽

MASAFUMI KURIYAMA ◽

KUNIO ARAI ◽

SHOZABURO SAITO

Keyword(s):

Secondary Flow ◽

Two Dimensional ◽

Dimensional Model ◽

Agitated Vessel ◽

Two Dimensional Model

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Effects of vessel baffling on the drawdown of floating solids

Chemical Papers ◽

10.2478/s11696-009-0011-0 ◽

2009 ◽

Vol 63 (2) ◽

Cited By ~ 16

Author(s):

Joanna Karcz ◽

Beata Mackiewicz

Keyword(s):

Experimental Data ◽

Power Consumption ◽

Strain Gauge ◽

High Speed ◽

Vessel Diameter ◽

Rushton Turbine ◽

Agitated Vessel ◽

Dimensionless Equation ◽

Inner Diameter ◽

Floating Particles

AbstractThe effects of baffling of an agitated vessel on the production of floating particles suspension are presented in this paper. Critical agitator speed, needed for particles dispersion in a liquid agitated in a vessel of the inner diameter of 0.295 m, was determined. The just drawdown agitator speeds were defined analogously to the Zwietering criterion. Specific agitation energy was calculated from the power consumption experimental data obtained by means of the strain gauge method. The experiments were carried out for twelve configurations of the baffles differing in number, length and their arrangement in the vessels. The following high-speed impellers were used: up- and downpumping six blade pitched blade turbines, Rushton turbine, and propeller. The impeller was located in the vessel in the height equal to two-thirds or one-third of the vessel diameter from the bottom of the vessel. The results were described in the form of a dimensionless equation.

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Flow Assurance in Buzios Field: Key Challenges and Implemented Solutions

10.4043/31277-ms ◽

2021 ◽

Author(s):

Ivan Noville ◽

Milena da Silva Maciel ◽

Anna Luiza de Moraes y blanco de Mattos ◽

João Gabriel Carvalho de Siqueira

Keyword(s):

Liquid Flow Rate ◽

Hydrate Formation ◽

Oil Field ◽

Oil Fields ◽

Injection System ◽

Flow Assurance ◽

Water Alternating Gas ◽

Early Design Stages ◽

Scale Deposition ◽

Full Operation

Abstract This article's goal is to present some of the main flow assurance challenges faced by PETROBRAS in the Buzios oil field, from its early design stages to full operation, up to this day. These challenges include: hydrate formation in WAG (Water Alternating Gas) operations; reliability of the chemical injection system to prevent scale deposition; increasing GLR (Gas Liquid Ratio) management and operations with extremely high flowrates. Flow assurance experience amassed in Buzios and in other pre-salt oil fields, regarding all these presented issues, is particularly relevant for the development of future projects with similar characteristics, such as high liquid flow rate, high CO2 content and high scaling potential.

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Do We Need Higher Dose Scale Inhibitors to Inhibit Scale under Turbulent Conditions? Insight into Mechanisms and New Test Methodology

10.2118/spe-169780-ms ◽

2014 ◽

Author(s):

Tao Chen ◽

Ping Chen ◽

Harry Montgomerie ◽

Thomas Hagen ◽

Ronald Benvie ◽

...

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Growth Inhibitor ◽

Test Method ◽

Bulk Precipitation ◽

Scale Inhibitor ◽

Surface Deposition ◽

Test Methodology ◽

The Relationship ◽

Scale Deposition

Abstract Turbulent flow, especially around chokes, downhole safety valves and inflow control devices, favors scale deposition potentially leading to severe loss of production. Recently, scale formation under turbulent conditions has been studied and progressed, focused on the bulk precipitation (SPE164070) and a small bore valve loop test (SPE 155428). However, bulk precipitation is not fully representative the surface deposition in the fields and the Reynolds number of modified loop is unknown. The relationship between a measured Reynolds number and surface deposition up until this study has not been addressed. A newly developed test methodology with rotating cylinder has been applied to generate high shear rate and evaluate surface deposition with Reynolds numbers up to ~41000. The relationship between Reynolds number and surface deposition is addressed. Using this highly representable test method for BaSO4 scale deposition, several different generic types of inhibitor chemistries, including polymers and phosphonates, were assessed under different levels of turbulence to evaluate their performance on surface deposition. The results showed it is not always true that higher turbulence results in higher dose of inhibitor being required to control scale. It is inhibitor chemistry and mechanisms dependent. The scale inhibitorscan be classified as three types when evaluating the trend of mass deposition versus Reynolds number and the morphology of the crystals deposited on the metal surface. ➢ Type 1: Crytal growth inhibitors. The mass of surface deposition increases with the increase of turbulence, along with smaller crystals.➢ Type 2: Dispersion and crystal growth inhibitor. The higher the turbulence, the less mass deposition, along with smaller crystals.➢ Type 3: Dispersion scale inhibitors. The higher the turbulence, the less mass deposition. The size of the crystals has no major change. This paper gives a comprehensive study of the effect of flow condition on the scale surface deposition and inhibition mechanisms. In addition, it details how this methodology and new environmentally acceptable inhibitor chemistry can be coupled to develop a chemical technology toolbox that also includes techniques for advanced scale inhibitor analysis and improved scale inhibitor retention, to design optimum scale squeeze packages for the harsh scaling conditions associated with turbulent flow conditions.

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