Developing Cold Flow Technology for Pipeline Transportation of Paraffinic 'Waxy' Mixtures

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dc.contributor.advisorMehrotra, Anil K.
dc.contributor.authorHaj-Shafiei, Samira
dc.contributor.committeememberHusein, Maen M.
dc.contributor.committeememberKaran, Kunal
dc.date2019-06
dc.date.accessioned2019-05-02T16:26:28Z
dc.date.available2019-05-02T16:26:28Z
dc.date.issued2019-04-29
dc.description.abstractThe terms hot flow and cold flow refer to the bulk temperature of a ‘waxy’ crude oil being above and below its wax appearance temperature (WAT), respectively. The deposit thickness has been reported to decrease substantially when the crude oil in a pipeline is in the cold flow regime and the deposit thickness approaches zero when the crude oil temperature is the same as the surrounding temperature because of the absent of temperature driving force. The cold flow regime was characterized by two-phase flow, in which solid wax crystals are suspended in the liquid phase. However, achieving cold flow of a ‘waxy’ crude oil would invariably involve solid deposition on the cooling surface especially in the hot flow regime. This thesis is focused on understanding and developing the cold flow technology for pipeline transportation of paraffinic ‘waxy’ crude oils. Solids deposition in the cold flow regime from a wax–solvent mixture was studied experimentally using a cold finger apparatus to develop stable two-phase solid-in-liquid suspension and to prove the reduction of deposit thickness in the cold flow regime. This study further investigated a novel methodology for accomplishing cold flow condition without any significant deposition in the hot flow regime using both cold-finger and flow-loop apparatuses. In this approach, the effect of cooling rate was investigated on the temperature difference between the mixture and the coolant as well as the extent of wax deposition. It was found that the temperature difference and the deposit mass increased with the cooling rate. With a constant temperature difference, no deposition was observed above the WAT. The results indicated that the deposition in the hot flow regime could be decreased substantially, or even be avoided when the waxy mixture is cooled at a low cooling rate. In addition, a steady-state heat-transfer model along with the effect of deposit aging was developed for the formation of a deposit-layer from wax–solvent ‘waxy’ mixtures in a pipeline under turbulent flow. The trends in the model predictions compared satisfactorily with those reported from bench-scale experimental studies as well as the predictions from an unsteady-state moving boundary problem formulation.en_US
dc.identifier.citationHaj-Shafiei, S. (2019). Developing Cold Flow Technology for Pipeline Transportation of Paraffinic 'Waxy' Mixtures (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/36428
dc.identifier.urihttp://hdl.handle.net/1880/110246
dc.language.isoengen_US
dc.publisher.facultySchulich School of Engineeringen_US
dc.publisher.institutionUniversity of Calgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.subjectHot flowen_US
dc.subjectCold flowen_US
dc.subjectCrystallizationen_US
dc.subjectCooling rateen_US
dc.subjectSolid depositionen_US
dc.subjectWax appearance temperatureen_US
dc.subjectParaffinic waxy oilen_US
dc.subject.classificationEnergyen_US
dc.subject.classificationEngineering--Chemicalen_US
dc.subject.classificationEngineering--Environmentalen_US
dc.subject.classificationEngineering--Petroleumen_US
dc.titleDeveloping Cold Flow Technology for Pipeline Transportation of Paraffinic 'Waxy' Mixturesen_US
dc.typedoctoral thesisen_US
thesis.degree.disciplineEngineering – Chemical & Petroleumen_US
thesis.degree.grantorUniversity of Calgaryen_US
thesis.degree.nameDoctor of Philosophy (PhD)en_US
ucalgary.item.requestcopytrue
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