Floc Strength in Bridging Flocculation

Mühle, K.; Domasch, K.

doi:10.1007/978-3-642-76093-8_8

Cited by 8 publications

(9 citation statements)

References 11 publications

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“…The shortest time (5 min) was best for all three parameters, COD, polyphenols (P), and aromatic compounds (A) (see Figure ). This therefore indicates that prolonged stirring leads to the rupture of the connections formed between the coagulant and the colloidal particles and the process's consequent loss of efficiency . One also observes from the figures that, for this 5-min mixing time, the COD, aromaticity, and polyphenol removals in water I were 25%, 5%, and 3% greater, respectively, than those in water II, further confirmation of the greater efficacy of the process for waters with lower organic matter content.…”

Section: Resultsmentioning

confidence: 58%

“…Adequate mixing is necessary both when the coagulant is added and during the formation and growth of the floc. As particle sizes increase, stirring may break up existing flocs as a result of disruptive forces, and the collision efficiency of the particles in a shear field decreases. , A dynamic balance between floc growth and breakage often leads to a steady-state floc-size distribution, where the limiting size depends on the applied shear rate . If the effective shear rate is increased, preformed flocs can be broken in a manner that depends on the floc size relative to the turbulence microscale .…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of Ferric Chloride as a Coagulant for Cork Processing Wastewaters. Influence of the Operating Conditions on the Removal of Organic Matter and Settleability Parameters

Domínguez

Heredia

González

et al. 2005

Ind. Eng. Chem. Res.

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This is a two-part work on the chemistry of iron(III) as coagulant in the treatment of cork processing wastewater. The main aim of the first part was to determine the removal of organic matter as measured by reductions in chemical oxygen demand (COD), polyphenols (P), and aromatic compounds (A) that can be obtained using this physicochemical process. To this end, jar-test experiments were used to determine the optimal conditions for the process, in particular, the effective iron dosage, temperature, contamination level of the wastewater, coagulant mixing time, stirring speed, and pH. The ranges of parameters tested for the coagulation process were coagulant dose (200−1500 mg/L), contamination of the wastewater (water I, COD 800 mg/L; water II, COD 1100 mg/L; water III, COD 2000 mg/L; water IV, COD 4000 mg/L), mixing time (5−30 min), stirring speed (60−300 rpm), temperature (20−80 °C), and pH (4−11). The resulting removal capacities were in the ranges 35−65% for COD, 55−90% for polyphenols, and 40−90% for aromatics. The best results were obtained with the shortest coagulant mixing time, 5 min, a stirring speed of 300 rpm, and the lowest temperature studied, 20 °C, although the difference at higher temperatures was only slight. The optimal choices of pH and coagulant dose fundamentally depended on the contamination level of the wastewater. In the second part of the work, the main aim was to examine the influence of the operating conditions on the system's settleability parameters. It is well-known that it is just as important to achieve good settleability parameters in the physicochemical treatment of wastewaters as it is to attain a high level of decontamination. These parameters will determine the dimensions of the required equipment and hence the costs of the installation. This second part of the study therefore analyzes the influence of the different operating variables on the following settleability parameters: sediment volumetric percentage, settling velocity, sludge volume index, and residual conductivity in the clarified water. The optimal conditions found for the settling process were not the same as those that had been determined in the first part of the study for the elimination of organic matter. Finally, taking into account economic and practical reasons, the Talmadge−Fitch method is used to apply the results to the design of a clarifier−thickener unit to treat 2 m3/h of wastewater. The required minimum area of the unit would be 4.01 m2.

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Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Evaluation of Ferric Chloride as a Coagulant for Cork Processing Wastewaters. Influence of the Operating Conditions on the Removal of Organic Matter and Settleability Parameters

Domínguez

Heredia

González

et al. 2005

Ind. Eng. Chem. Res.

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“…In general, several parameters, such as pressure, temperature, oil phase composition, salinity, gas composition, shut-in time, hydrate inhibitors, etc., may change the value of the cohesive force . The measured cohesive force (4.8 mN/m) was inputted to Muhle’s model to calculate the hydrate agglomerate size at different shear rates in CSMHyK. , …”

Section: Results and Discussionmentioning

confidence: 99%

“…The hydrate agglomerate size is a result of the cohesive force, fluid shear, oil viscosity, and the hydrate particle size. The hydrate agglomerate size is calculated from Muhle’s model inside CSMHyK with the input of cohesive force . Hydrate agglomeration may be neglected if AA is injected into the system, due to the fact that AA can act as an intermediary between particles to reduce the cohesive force .…”

Section: Experiment Model and Field Operation Descriptionmentioning

confidence: 99%

Changing the Hydrate Management Guidelines: From Benchtop Experiments to CSMHyK Field Simulations

et al. 2020

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High-pressure and low-temperature conditions during subsea pipeline transportation favor the formation of gas hydrates and may create challenging flow assurance problems. Once gas hydrates have plugged the pipeline, it is usually difficult and costly to remediate. To prevent hydrate plugging, rigorous hydrate management guidelines need to be formulated and implemented at an affordable cost. Current hydrate management guidelines are mostly based on fluid analysis and benchtop experimental results, which may not represent the actual field conditions. Based on this situation, a simulation tool that can bridge the gap between benchtop experiments and field pipeline transportation conditions is needed. In this paper, a methodology is proposed to combine benchtop ultralow volume (<10 mL) experiments with field simulations to provide insights for field hydrate management. This methodology was applied to a real black oil field to study the blockage risk during shut-ins of varying durations. Simulations were carried out at three representative water cuts. It is indicated that for production shut-ins within 6 h, the flowlines can be directly restarted without hydrate plugging risk. Hydrate slip and accumulation could increase the plug potential, thus for a restart following a planned shut-in longer than 6 h, AA injection might be necessary. Simulations indicate that even after 16 h into a shut-in, the hydrate formation amount would be very low during dead oil displacement. This suggests that dead oiling could be a good strategy to minimize risk during the ensuing restart for unplanned shut-ins longer than 6 h. Based on these simulation results, the envelope for a hydrate risk management approach can be expanded to allow higher water cut operation with minimal blockage risk during extended unplanned shut-ins and restarts. This simulation tool and the proposed methodology may be used to develop competitive field hydrate management guidelines with relatively low capital expense (CAPEX) and operating expense (OPEX) in different fields.

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“…The difficulty concerning a mathematical determination of FH has already been emphasized. Therefore, the centrifugal method (MUHLE et al 1982;MUHLE et al 1983; MUHLE, DOMASCH) was used for approximate experimental determination of the adhesion force in the platecrystalsystem (see Fig. 4).…”

Section: (4)mentioning

confidence: 99%

Modelling of mechanism of agglomeration of KCl crystallization

Schmok

1988

Cryst. Res. Technol.

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The article presents an analysis into agglomeration during KC1 vacuum crystallization. The theoretical and experimental investigations into the mechanism of agglomeration during mass crystallization result in an extension of the growth phenomena within the known model equations. The basis for this is essentially constituted by the collision model concepts of the theory of floculation in disperse systems. The parameters derived from the microprocess analysis (energy dissipation, content of solids, growth rate of individual grains) lead to model equations which are confirmed by laboratory and test trials.Es wird uber eine Analyse zur Agglomeration bei der Vakuumkristallisation von KCl berichtet. Die theoretischen und experimentellen Untersuchungen zum Agglomerationsmechanismus bei der Massenkristallisation fuhren zu einer Erweiterung der Wachstumsphiinomene in den bekannten Modellgleichungen. Wesentliche Grundlage dafur sind die Kollisionsmodellkonzepte der Flockungstheorie in dispersen Systemen. Die aus der Mikro-prozeI3betrachtung abgeleiteten verfugbaren Parameter (Energiedissipation, Feststoffgehalt, Wachstumsgeschwindigkeit des Einzelkorns) fuhren zu Modellgleichungen, die durch kleintechnische Experimente und Betriebsversuche bestiitigt werden.

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Floc Strength in Bridging Flocculation

Cited by 8 publications

References 11 publications

Evaluation of Ferric Chloride as a Coagulant for Cork Processing Wastewaters. Influence of the Operating Conditions on the Removal of Organic Matter and Settleability Parameters

Evaluation of Ferric Chloride as a Coagulant for Cork Processing Wastewaters. Influence of the Operating Conditions on the Removal of Organic Matter and Settleability Parameters

Changing the Hydrate Management Guidelines: From Benchtop Experiments to CSMHyK Field Simulations

Modelling of mechanism of agglomeration of KCl crystallization

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