The Hardening Process and Morphology of a Wax Deposit in a Pipe Flow

Masoudi, Sh.; Sefti, Mohsen Vafaie; Jafari, Hojat; Modares, Hamidreza

doi:10.1080/10916466.2010.493910

Cited by 19 publications

(16 citation statements)

References 18 publications

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“…5. The crystals became more scattered microplate‐like and more hollow areas were observed, which leads to a softer material (Masoudi et al, 2010). This correlates with their higher friction coefficient and wear loss at 50 °C as a softer surface negatively affects transfer film forming and increases the real contact area at the interface.…”

Section: Resultsmentioning

confidence: 99%

The Friction and Wear Behaviors of Vegetable Oil‐Based Waxes, Natural Beeswax, and Petroleum Paraffin Wax

Tao

Kawaguchi

Wang

2020

J Americ Oil Chem Soc

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Quantitative analyses on the coefficient of friction of common coating waxes are necessary and essential for designing systems for coating, conveying, packaging operations, transporting, and storing of papers and paperboards, while analyses on wear behavior can be helpful for predicting performance durability of the coating surface. In this study, we investigated the friction and wear behaviors of six waxes including four commercial waxes and two soybean oil-based wax developed in our lab for bulk corrugated coating. The effect of normal load, sliding velocity, and environmental temperature was evaluated. The friction coefficient of different waxes varies with sliding conditions. Higher normal load, sliding velocity, and environmental temperature resulted in significantly greater wear loss. Crystalline morphology and crystallinity of waxes were affected by the environmental temperature, and they correlate to the variations in friction coefficient and wear loss of these materials.

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Section: Resultsmentioning

confidence: 99%

The Friction and Wear Behaviors of Vegetable Oil‐Based Waxes, Natural Beeswax, and Petroleum Paraffin Wax

Tao

Kawaguchi

Wang

2020

J Americ Oil Chem Soc

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“…Li et al argued that the increase in boundary fractal dimension (an index characterizing wax crystal complexity) and decrease in aspect ratio are the root causes for wax strength enhancement when wax content increases. Coutinho et al and Masoudi et al found that the increase in wax deposit strength over time is accompanied by changes in wax crystal morphology. Bai and Zhang proposed that the increasing average carbon number of wax crystals ratchets up the aspect ratio and down the boundary fractal dimension and average size, consequently, the strength of oil‐wax gel decays.…”

Section: Wax Properties Affecting Wax Removalmentioning

confidence: 98%

Advances and Future Challenges of Wax Removal in Pipeline Pigging Operations on Crude Oil Transportation Systems

Huang

Wang³

et al. 2020

Energy Tech

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Wax deposition is a severe flow assurance challenge that threatens waxy crude oil production and transportation. For wax remediation, pipeline pigging is the most widely used technique. However, the elusiveness of wax removal mechanism and the lack of reliable methods to evaluate wax breaking force and wax removal efficiency easily trigger pig stalling and wax blockage in field pigging operations. Modeling wax breaking force and wax removal efficiency, therefore, promotes the pigging confidence. This Review seeks to clarify the current picture of wax removal research in crude oil pipeline pigging. Relevant wax deposit properties including wax layer thickness and strength are discussed. Wax removal mechanisms are summarized from perspectives of wax–pig interaction, macroscopic force response, and scenarios with oil flow. Prediction models of wax breaking force and wax removal efficiency are analyzed comprehensively. Pig geometry optimization using this model is given. In addition, the key roles of wax deposit strength, viscoelasticity and thixotropy, foam pig investigation, and wax plug prediction are highlighted for guiding future endeavors in this area.

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“…Experimental results have shown that a harder deposit, with a lower fraction of the entrapped oil, is formed under higher shear rates. [51,54,75,78,129,130,[134][135][136] One approach for modelling the deposit aging phenomenon assumes counter-diffusion of heavier paraffins into the deposit and lighter paraffins out of the deposit. [78][79][80] It predicts relatively slower changes in the deposit composition.…”

Section: Modelling Of Pipeline Flow Shut-downmentioning

confidence: 99%

A review of heat‐transfer mechanism for solid deposition from “waxy” or paraffinic mixtures

et al. 2020

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Summarized in this review are a large number of experimental and modelling studies for advancing the heat-transfer-based mechanism for solid deposition from "waxy" or paraffinic oils and mixtures. This comprehensive heat-transfer approach is entirely different from a more popular molecular-diffusion mechanism. It has evolved from numerous publications, over three decades, which explored topics related to thermodynamic, rheological, crystallization, solid deposition, and shutdown and deposit-aging behaviour of prepared multicomponent paraffinic mixtures of varying compositions to simulate "waxy" crude oils. These investigations covered a wide range of compositions, temperatures, and cooling rates-under static, sheared, laminar and turbulent conditions-in both the hot and cold flow regimes. The heat-transfer mechanism for wax deposition is based on (partial) freezing or liquid-to-solid phase transformation process, for which steady-state and unsteady-state mathematical models have been developed and validated with extensive laboratory data. Furthermore, a shear-induced deformation model for the deposit aging phenomenon has been developed and validated; it is based on a partial release of the liquid phase from the incipient gel, thereby causing an enrichment of heavier alkanes and a corresponding depletion of lighter alkanes in the deposit. A successful analogy with the ice deposition process has confirmed the wax deposition process to be also controlled by heat transfer, without involving any other mechanism for wax deposition. All of these previous studies confirm that wax deposition is predominantly a thermally driven process. K E Y W O R D S aging, cold flow, heat transfer, solid deposition, waxy crude oil 1 | INTRODUCTION Crude oils are complex mixtures of hydrocarbons, including high molar mass alkanes or paraffins, which are referred to as waxes. Waxes contain carbon numbers ranging from 18-65. [1] Crude oils that contain a significant proportion of high molecular weight paraffins or waxes are referred to as paraffinic or "waxy" crude oils. Waxes tend to crystallize and deposit on cooler surfaces because of their decreased solubility in the crude oil at lower temperatures. The highest temperature at which the first crystals start to appear, upon cooling of a "waxy" crude oil, is called the wax appearance temperature (WAT), which is also referred to as the cloud point temperature (CPT). The precipitation and deposition of solids are of significant importance in the production,

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The Hardening Process and Morphology of a Wax Deposit in a Pipe Flow

Cited by 19 publications

References 18 publications

The Friction and Wear Behaviors of Vegetable Oil‐Based Waxes, Natural Beeswax, and Petroleum Paraffin Wax

The Friction and Wear Behaviors of Vegetable Oil‐Based Waxes, Natural Beeswax, and Petroleum Paraffin Wax

Advances and Future Challenges of Wax Removal in Pipeline Pigging Operations on Crude Oil Transportation Systems

A review of heat‐transfer mechanism for solid deposition from “waxy” or paraffinic mixtures

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