PPD architecture development via polymer–crystal interaction assessment

Paso, Kristofer; Krückert, Karsten Karl; Oschmann, Hans-Jörg; Ali, Hassan Refat H.; Sjöblom, Johan

doi:10.1016/j.petrol.2014.02.002

Cited by 17 publications

(29 citation statements)

References 13 publications

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“…7 the influence of different PPDs or asphaltenes onto the wax crystal morphology is shown and compared to the blank case with no WI. Wax crystals formed without additives show plate and needle like structures similar to CPM images reported in other studies [49][50][51].…”

Section: Cross-polarized Microscopy (Cpm)supporting

confidence: 83%

“…The intensity and amount of white spots in an image can also provide ground for the estimation of the amount of wax precipitated [49]. Addition of PPD 1 and PPD 2 therefore suggests the lowest amount of wax precipitated, which shows as crystals of a few micrometer or less in diameter, which are smaller than for the other samples tested.…”

Section: Cross-polarized Microscopy (Cpm)mentioning

confidence: 99%

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Wax-Inhibitor Interactions Studied by Isothermal Titration Calorimetry and Effect of Wax Inhibitor on Wax Crystallization

et al. 2017

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Isothermal titration calorimetry (ITC) is applied to investigate the interactions of polymeric pour-point depressants (PPDs) or asphaltenes with macrocrystalline wax in a model oil system. This represents a novel approach to measure and compare the heat of interaction for solid wax crystals with different wax inhibitors (WIs). In addition, the PPDs were characterized via size-exclusion chromatography (SEC) and differential scanning calorimetry (DSC), and the effect of PPDs or asphaltenes onto the wax appearance temperature (WAT) and the formed wax-oil gel was investigated using DSC, cross-polarized microscopy (CPM), and rheometry. The results show that there is detectable interaction heat with wax crystals for all PPDs, and asphaltenes. DSC and viscometry show a decrease in observed WAT for all WIs as compared to the additive-free blank case. CPM imaging shows differences in structure, shape, and size of the wax crystals formed in presence of particular PPDs or asphaltenes, which is also seen as a decrease in gel-breakage strength. Overall, there is no direct correlation between interaction heat and WI performance characteristics, such as a high decrease in WAT or gel strength. Ethylene-vinyl acetate copolymer (EVA) with 25 % vinyl actetate accounts for the highest interaction heat measured, but shows effective decrease in wax crystals size for only part of the crystals while acting as a flocculate to others, which resulted in a low effect on gel strength.Commercial PPDs based on polycarboxylate have the best performance for the model oil system used, but show only overage interaction heat values. The interaction heat of asphaltenes with wax is measurable, but lower than for the PPDs tested. The presence of asphaltenes significantly lowered the gel strength and changed the wax crystal morphology to rounder and dendrite like shapes. These findings suggest that asphaltene compounds are incorporated into the wax crystals, changing the structure and shape of the crystals.

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Section: Cross-polarized Microscopy (Cpm)supporting

confidence: 83%

Section: Cross-polarized Microscopy (Cpm)mentioning

confidence: 99%

Wax-Inhibitor Interactions Studied by Isothermal Titration Calorimetry and Effect of Wax Inhibitor on Wax Crystallization

et al. 2017

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“…Additive C and Additive D also reduce cloud point as dosage increases, but the pour point shows maximum reduction around 100 ppm. Previous work have proposed that the differences in dosage effectiveness of the additives to reduce cloud point and pour point probably result from the predominant action mechanism of the active polymers as paraffin solubilizers, wax crystal modifiers, and interfacially-active agents [18,19]. The correlation between pour point reduction and cloud point reduction can be more easily interpreted from Figure 6.…”

Section: Cloud Point and Pour Point Of Model Waxy Oilsmentioning

confidence: 94%

“…They explained the cloud point depression by a mechanism of thermodynamic suppression of nucleation which was associated with a reduction in wax deposition on a cold surface [17]. Paso et al also proposed a thermodynamic solubilizing effect of polymeric additives to explain the cloud point reduction of a model oil system [18]. Figure 5 shows the pour point reduction of Model Oil 1 by the same wax inhibitors at the same additive concentrations as those presented in Figure 4.…”

Section: Cloud Point and Pour Point Of Model Waxy Oilsmentioning

confidence: 98%

Evaluation of Paraffin Wax Inhibitors: An Experimental Comparison of Bench-Top Test Results and Small-Scale Deposition Rigs for Model Waxy Oils

et al. 2015

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The performance of paraffin inhibitors from several chemical families was evaluated using two model waxy oils in bench-top tests such as cloud point and pour point, and in small-scale deposition rigs using a cold finger and a flow loop. In addition, rheological characterization of the inhibited systems was conducted to provide additional insights into the function of the paraffin inhibitors. Similarities and differences in the response of the model oils to the paraffin inhibitors are discussed along with the correlations between the results from bench-top tests and the observed wax deposit inhibition performance.The model waxy-oils were formulated using blends of commercially available waxes dissolved in a paraffinic solvent or a mixture of paraffinic and aromatic solvents. The wax blends were chosen to represent a broad range of carbon number distributions including one highly polydisperse distribution with an extended distribution of high carbon number waxes exceeding C50. Candidate paraffin inhibitors were initially evaluated for their impact on cloud point and pour point in these model oils. Subsequent testing of the inhibited systems included rheological characterization over a range of temperatures, cold finger deposition tests and flow loop deposition tests in a pipe-in-pipe geometry. All results are compared to the baseline results for the uninhibited model waxy oils.While changes in cloud point and pour point gave a good indication that a particular paraffin inhibitor was impacting the wax crystallization process, this did not guarantee a significant reduction in deposits of the inhibited system. Moreover, the experimental conditions used in the small-scale deposition tests also affected the observed performance of paraffin inhibitors, indicating that temperature gradients (i.e., oil temperature and coolant temperature) must be optimized to achieve the highest discriminating power. This study highlights the degree of correlation and the areas of departure between bench-top test results and the main objectives of deposit reduction, and yield stress reduction in flowing systems. It also discusses the advantages and risks of using only the bench-top test results for the selection of paraffin inhibitors.

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“…This was because the existences of alkyl side-chains with proper length, could promote the intermolecular intermiscibility between grafted EVALs and wax molecules. 38,39 3.6. Process of Wax Crystallization.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Synthesis and Evaluation of Grafted EVAL as Pour Point Depressant for Waxy Crude Oil

Ren

Fang

Chen

et al. 2018

Ind. Eng. Chem. Res.

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Alcoholized ethylene–vinyl acetate copolymer (EVAL) was chemically modified by grafting n-alkyl acrylates with different alkyl chain lengths. The grafted EVAL was characterized through Fourier transform infrared (FTIR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and element analysis. The effect of grafted EVAL on wax crystallization process of crude oil was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results showed that the length of alkyl side-chain in grafted EVAL largely influenced the efficiency of grafted EVAL. Grafted EVAL with side-chain length of C16 could reduce the pour point of Shengli (SL) crude oil by 11 °C, and that with side-chain length of C18 could reduce the pour point of Jianghan (JH) crude oil by 14.5 °C. The introduction of alkyl side-chain could improve wax solubility and promote grafted EVAL to adsorb and cocrystallize with wax molecules, which obviously decreased the wax precipitation amount and changed the wax crystallization process.

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PPD architecture development via polymer–crystal interaction assessment

Cited by 17 publications

References 13 publications

Wax-Inhibitor Interactions Studied by Isothermal Titration Calorimetry and Effect of Wax Inhibitor on Wax Crystallization

Wax-Inhibitor Interactions Studied by Isothermal Titration Calorimetry and Effect of Wax Inhibitor on Wax Crystallization

Evaluation of Paraffin Wax Inhibitors: An Experimental Comparison of Bench-Top Test Results and Small-Scale Deposition Rigs for Model Waxy Oils

Synthesis and Evaluation of Grafted EVAL as Pour Point Depressant for Waxy Crude Oil

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