scholarly journals Studies on the Exergy Transfer Law for the Irreversible Process in the Waxy Crude Oil Pipeline Transportation

Entropy ◽  
2018 ◽  
Vol 20 (5) ◽  
pp. 309 ◽  
Author(s):  
Qinglin Cheng ◽  
Anbo Zheng ◽  
Shuang Song ◽  
Hao Wu ◽  
Lili Lv ◽  
...  
Keyword(s):  
Crude Oil ◽  
Irreversible Process ◽  
Pipeline Transportation ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Exergy Transfer

Molecular Dynamics Study on Microscopic Mechanism of Dissolution, Diffusion and Aggregation Process for Waxy Molecules in the Process of Waxy Crude Oil Pipeline Transportation

2019 ◽  
Author(s):  
Yifan Gan ◽  
Qinglin Cheng ◽  
Zhihua Wang ◽  
Jinwei Yang ◽  
Wei Sun ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Crude Oil ◽  
Dynamics Simulation ◽  
Precipitation Process ◽  
Pipeline Transportation ◽  
Waxy Crude Oil ◽  
Wax Precipitation ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Transportation Process

Abstract In order to ensure the safe and economic operation of waxy crude oil transportation process, the micro-dynamic mechanism and thermodynamic characteristics of wax precipitation process at nanoscale are necessary to be revealed. Here, we established the molecular dynamics model to characterize the phase transition and precipitation behavior of waxy molecules in multiphase system (including oil, asphaltene and water), the relative error between simulated results and experimental data measured by Dutour et al. (2002) is less than 5%. Under the coupling effect of different operation parameters, the molecular dynamics simulation was employed, the simulated results showed that the spherical paraffin crystals underwent the process of dissolution, diffusion and aggregation, then the waxy cluster crystals with larger amount but smaller volume would form, and it would deposit on the outer wall under the concentration gradient. The influence mechanism of different operating parameters on wax precipitation was analyzed, of which the increase of temperature and water cut will decrease the wax precipitation, while the increase of pressure will enhance the wax precipitation rate, furthermore, by means of the hydrogen bonding and the effect of similar dissolution, the water and asphaltene molecules also affect the wax precipitation process at molecular-scale. The researches of this paper provide the theoretical support for the paraffin removal and control in waxy crude oil pipeline transportation process.

A methodology to investigate factors governing the restart pressure of a Malaysian waxy crude oil pipeline

2021 ◽  
pp. 109785
Author(s):  
Guillaume Vinay ◽  
Petrus Tri Bhaskoro ◽  
Isabelle Hénaut ◽  
Mior Zaiga Sariman ◽  
Astriyana Anuar ◽  
...  
Keyword(s):  
Crude Oil ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline

scholarly journals Study on Optimizing Operation of Preheating Commissioning for Waxy Crude Oil Pipelines

2014 ◽  
Vol 6 ◽  
pp. 894256
Author(s):  
Jian Zhang ◽  
Yi Wang ◽  
Xinran Wang ◽  
Handu Dong ◽  
Jinping Huang ◽  
...  
Keyword(s):  
Crude Oil ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Governing Equations ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Single Station ◽  
Oil Pipelines ◽  
Volume Method

A mathematical model is established for the preheating commissioning process of waxy crude oil pipelines. The governing equations are solved by the finite volume method and the finite difference method. Accordingly, numerical computations are made for the Niger crude oil pipeline and the Daqing-Tieling 3rd pipeline. The computational results agree well with the field test data. On this basis, fluid temperature in the process of the preheating commissioning is studied for single station-to-station pipeline. By comparing different preheating modes, it is found that the effect of forward preheating is the best. Under different preheating commissioning conditions, the optimal combination of outlet temperature and flow rate is given.

scholarly journals Unavoidable Destroyed Exergy in Crude Oil Pipelines due to Wax Precipitation

Entropy ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 58
Author(s):  
Qinglin Cheng ◽  
JinWei Yang ◽  
Anbo Zheng ◽  
Lu Yang ◽  
Yifan Gan ◽  
...  
Keyword(s):  
Crude Oil ◽  
Design Parameters ◽  
Burial Depth ◽  
Outlet Temperature ◽  
Waxy Crude Oil ◽  
Wax Precipitation ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
Operation Parameters

Based on the technological requirements related to waxy crude oil pipeline transportation, both unavoidable and avoidable destroyed exergy are defined. Considering the changing characteristics of flow pattern and flow regime over the course of the oil transportation process, a method of dividing station oil pipelines into transportation intervals is suggested according to characteristic temperatures, such as the wax precipitation point and abnormal point. The critical transition temperature and the specific heat capacity of waxy crude oil are calculated, and an unavoidable destroyed exergy formula is derived. Then, taking the Daqing oil pipeline as an example, unavoidable destroyed exergy in various transportation intervals are calculated during the actual processes. Furthermore, the influential rules under various design and operation parameters are further analyzed. The maximum and minimum unavoidable destroyed exergy are 381.128 kJ/s and 30.259 kJ/s. When the design parameters are simulated, and the maximum unavoidable destroyed exergy is 625 kJ/s at the diameter about 250 mm. With the increase of insulation layer thickness, the unavoidable destroyed exergy decreases continuously, and the minimum unavoidable destroyed exergy is 22 kJ/s at 30 mm. And the burial depth has little effect on the unavoidable destroyed exergy. When the operation parameters are simulated, the destroyed exergy increases, but it is less affected by the outlet pressure. The increase amplitude of unavoidable destroyed exergy will not exceed 2% after the throughput rises to 80 m3/h. When the outlet temperature increases until 65 °C, the loss increase range will not exceed 4%. Thus, this study provides a theoretical basis for the safe and economical transportation of waxy crude oil.

Study of Wax Deposition Rate in Waxy Crude Oil Pipeline

2013 ◽  
Vol 401-403 ◽  
pp. 891-894 ◽  
Author(s):  
Qing Lin Cheng ◽  
Xu Xu Wang ◽  
Xian Li Li ◽  
Wei Sun ◽  
Ling De Meng
Keyword(s):  
Crude Oil ◽  
Deposition Rate ◽  
Normal Operation ◽  
Wax Deposition ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Oil Transportation ◽  
Different Seasons ◽  
Deposition Tendency

In waxy crude oil transportation process, wax crystals start to precipitate as the oil temperature drops to wax appearance point, and then form a network structure gradually which attaches to the wall. The problem of wax deposition seriously affects the normal operation of pipeline. Based on the wax deposition tendency coefficient method, combined with experimental data, the parameters related to wax deposition tendency coefficient is fitted, and the wax deposition rate equation of crude oil is determined finally. The variation law of wax deposition rate along the pipeline is analyzed, and the influence of different seasons and different throughput the on wax deposition rate is discussed subsequently.

scholarly journals The study on temperature field variation and phase transition law after shutdown of buried waxy crude oil pipeline

2017 ◽  
Vol 10 ◽  
pp. 443-454 ◽  
Author(s):  
Qinglin Cheng ◽  
Yifan Gan ◽  
Peidi Wang ◽  
Wei Sun ◽  
Ying Xu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Temperature Field ◽  
Crude Oil ◽  
Field Variation ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline
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