A Novel Approach To Quantify Scale Thickness and Distribution in Stirred Vessels

Davoody, Meysam; Graham, Lachlan; Wu, Jie; Youn, Inju; Raman, Abdul Aziz Abdul; Parthasarathy, Rajarathinam

doi:10.1021/acs.iecr.7b03543

Cited by 6 publications

(6 citation statements)

References 40 publications

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“…The data also show that, for the same rate of mass transfer, gas sparging decreases the energy consumption; the higher the value of u g , the lower is the energy consumption. These results are consistent with previous studies 50, 51 in that the axial‐flow turbine is more energy efficient than the radial‐flow turbine in view of the high ratios of mass transfer coefficient to specific power consumption ( K / ε ; ε represents the power consumption ( P u or P T ) per unit mass of the solution) produced by the axial‐flow turbine; i.e., the combination of using the 45° impeller along with high superficial gas velocities gives a cost‐effective criterion of the present multiphase reactor.…”

Section: Resultssupporting

confidence: 94%

Heat and Mass Transfer at the Wall of a Square Mechanically Stirred Gas‐Liquid‐Solid Catalytic Reactor

et al. 2021

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Wall mass and heat transfer rates in a square gas‐sparged, mechanically stirred reactor were measured by the electrochemical technique under the effect of various geometrical and hydrodynamic variables. For the 45° impeller, the mass transfer data fit the equation Sh = 0.7Sc0.33Re0.2Reg0.5 with an average deviation of ±6.9 %. For the 90° impeller, the data fit the equation Sh = 0.95Sc0.33Re0.14Reg0.53 with an average deviation of ±7.5 %. Gas sparging enhanced the wall mass transfer rates by factors of up to 2.61 and 3 for the 90° and 45° impellers, respectively, with a significant decrease in the total power consumption. The contribution of the present results to the operation of multiphase mechanically agitated vessels in different aspects is outlined.

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Section: Resultssupporting

confidence: 94%

Heat and Mass Transfer at the Wall of a Square Mechanically Stirred Gas‐Liquid‐Solid Catalytic Reactor

et al. 2021

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“…The weight of scale decreased with the impeller rotation speed regardless of the configuration of baffle clearance. This tendency is consistent with the case of a small agitator using the Lightnin A310 18 and can also be seen in the case of the pipe flow. 14 As Wu et al 15 pointed out, the removal of the material deposit can occur simultaneously with the formation of scale.…”

Section: ■ Introductionsupporting

confidence: 87%

“…The impeller rotating speed was varied from 200 to 280 rpm. A more detailed experimental methodology can be referred in the paper of Davoody et al (2017). 18 Flow Velocity and Power Consumption Measurement.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Effect of Baffle Clearance on Scale Deposition in an Agitated Vessel

et al. 2021

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The material deposition in a mixing tank agitated by the MAXBLEND impeller in a turbulent state was quantified and compared between cases with and without baffle clearance. Magnesium hydroxide formed from the chemical reaction between calcium hydroxide and magnesium chloride was used as a model of scale formation. Flow velocity in the tank was investigated by employing computational fluid dynamics simulation and experimentally validated by an ultrasonic velocity profiler method. Results showed that the amount of scale decreased with the increase in the rotational speed of the impeller due to the erosion effect on the tank wall. In the case without baffle clearance, the smaller weight of the scale was deposited on the front of the baffle plate due to the flow impingement, which enhanced the removal of the scale deposition. However, the lower-velocity magnitude behind the baffles resulted in an enhancement in the formation of scale. Installation of baffle clearance caused a contraction flow in between the tank wall and baffles, and consequently, the higher flow velocity reduced the amount and thickness of the scale. Measurement of the torque showed that the baffle clearance did not affect the power consumption, so the installation of baffle clearance can be a promising approach to reduce scale deposition in terms of saving operational costs and increasing process efficiency and safety.

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“…[1][2][3][4] These unfavourable minerals that usually deposit in pipes, membranes, heat exchangers, and mixing tanks cause a considerable reduction in fluid flow and blockage of the pipelines, and other equipment, together with other consequences like corrosion. [5][6][7][8] There are various types of minerals that form scales. Among these, calcium carbonate 9,10 , barium sulfate 11 , magnesium hydroxide 12 , silica 13,14 , and calcium sulfate 15,16 are frequent.…”

Section: Introductionmentioning

confidence: 99%

“…Mineral scale formation is a major problem in many industrial processes such as crude oil production, reverse osmosis desalination, cooling systems, papermaking, etc. − These unfavorable minerals that usually deposit in pipes, membranes, heat exchangers, and mixing tanks cause a considerable reduction in fluid flow and blockage of the pipelines, and other equipment, together with other consequences like corrosion. − …”

Section: Introductionmentioning

confidence: 99%

Investigating the Effectiveness of Phosphonate Additives in Hindering the Calcium Sulfate Dihydrate Scale Formation

Rabizadeh

Peacock

Benning

2020

Ind. Eng. Chem. Res.

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The effects of 20 ppm 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP), Amino Trimethylene Phosphonic Acid (ATMP), Polyamino Polyether Methylene Phosphonic Acid (PAPEMP), Diethylene Triamine Penta (Methylene Phosphonic Acid) (DTPMPA) and Bis(HexaMethylene Triamine Penta (Methylene Phosphonic Acid)) (BHMTPMPA) on the room temperature crystallization of calcium sulfate dihydrate (gypsum) were investigated by by in situ UV-Vis, XRD, XPS, ICP-OES, and SEM. Comparison between the additivecontaining and additive-free experiments showed that BHMTPMPA was the most efficient antiscalant by completely inhibiting crystallization. Due to the chain length of the BHMTPMPA molecule, the crystallization kinetics decreased to a larger extent than 2DTPMPA. The increase in pH of the solution from ~ to ~ 7, positively enhanced the efficiency of the phosphonates in inhibiting crystallization. Our results revealed that partially deprotonated phosphonate additives were strongly associated with gypsum crystals and / or potentially taken up into the crystal matrix resulted in a sudden and sharp increase in turbidity plots. Furthermore, phosphonate additives altered the thin, twinned gypsum crystals into thick needles.

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A Novel Approach To Quantify Scale Thickness and Distribution in Stirred Vessels

Cited by 6 publications

References 40 publications

Heat and Mass Transfer at the Wall of a Square Mechanically Stirred Gas‐Liquid‐Solid Catalytic Reactor

Heat and Mass Transfer at the Wall of a Square Mechanically Stirred Gas‐Liquid‐Solid Catalytic Reactor

Effect of Baffle Clearance on Scale Deposition in an Agitated Vessel

Investigating the Effectiveness of Phosphonate Additives in Hindering the Calcium Sulfate Dihydrate Scale Formation

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