A hybrid method for predicting the dynamic response of free-span submarine pipelines

Li, Tongtong,Duan, Menglan,Liang, Wei,An, Chen Techno-Press 2016 Ocean systems engineering Vol.6 No.4

Large numbers of submarine pipelines are laid as the world now is attaching great importance to offshore oil exploitation. Free spanning of submarine pipelines may be caused by seabed unevenness, change of topology, artificial supports, etc. By combining Iwan's wake oscillator model with the differential equation which describes the vibration behavior of free-span submarine pipelines, the pipe-fluid coupling equation is developed and solved in order to study the effect of both internal and external fluid on the vibration behavior of free-span submarine pipelines. Through generalized integral transform technique (GITT), the governing equation describing the transverse displacement is transformed into a system of second-order ordinary differential equations (ODEs) in temporal variable, eliminating the spatial variable. The MATHEMATICA built-in function NDSolve is then used to numerically solve the transformed ODE system. The good convergence of the eigenfunction expansions proved that this method is applicable for predicting the dynamic response of free-span pipelines subjected to both internal flow and external current.

Identification of Volatile Flavor Compounds in Chinese Sinkiang Camel-naizi Using Different Solid Phase Microextraction Fibers

Ning Li,Fuping Zheng,Menglan Liang,Baoguo Sun 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.4

Volatile components of Chinese Sinkiang camel-naizi (CSCN) were analyzed using solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). A total of 45 volatile compounds were identified by using 3 fibers, including 17 alcohols, 4aldehydes, 13 acids, 8 esters, 1 sulfur-containing compound,1 lactone, and 1 ketone. Among all the compounds identified, various alcoholic compounds accounted for 78.91% of the total volatiles, and the amount of various esters was only next to that of alcohols, which accounted for 15.01% of the total volatiles. The content of acids,lactone, aldehydes, ketone, and sulfur-containing compound accounted for 6.08%. All of these volatiles constituted the characteristic flavor of raisin-like, fruity, sweet, cheesy, and yogurt-like note of CSCN. The extraction performances of 3 types of SPME fibers (75 μm CAR/PDMS, 65 μm PDMS/DVB, and 50/30 μm DVB/CAR/PDMS) were compared in this study. Of the 3 fibers, the DVB/CAR/PDMS fiber extracted the most volatiles, and the CAR/PDMS fiber the least. The DVB/CAR/PDMS fiber showed the best performance in trapping compounds of CSCN with different polarities.

Coalescence behavior of aqueous drops in water-in-oil emulsions under high-frequency pulsed AC fields

Wanli Kang,Menglan Li,Hongbin Yang,Xin Kang,Fang Wang,Haizhuang Jiang,Min Zhang,Tongyu Zhu,Bauyrzhan Sarsenbekuly 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-

High-frequency pulsed alternating currentfield (HFPACF) has attracted attentions owing to its excellentperformances of eliminating short circuit, saving energy and reducing environmental pollution. To studythe coalescence mechanism of aqueous drops in water-in-oil (W/O) emulsions under HFPACF, micro-behavior of dispersed drops for W/O emulsion was monitored by using a self-designed micro-visualmodel and coalescence mechanism was analyzed by discussing effects of pulse amplitude, pulsefrequency, pulse width ratio, demulsifier concentration, aqueous mass ratio of emulsion, and differentmodel oil emulsions. The results show that the dispersed drops coalesce under the action of electricfield,and the particle size of dispersed drops increases with the increase of pulse frequency and amplitude. When the pulse frequency or amplitude reach to a critical value, aqueous drops are driven to form waterstring or water channel between two electrodes which hinders further drops coalescence in other areas. However, with the increase of pulse width ratio, the size of dispersed drops increases slowly. Theoptimum pulse frequency and pulse amplitude are obtained at 3.9 kV and 4.21 kHz, respectively, theoptimal pulse width range is 54.9%-84.4%. When the concentration of demulsifier is 60 mg/L, thesynergistic demulsification effect achieves the highest performance. When the aqueous mass ratio ofemulsion reaches a high level (over 30%), which means the drops in emulsion have big size, thecoalescence performance under the same electricfield strength is great. Also, it is discovered that thedispersed drops in Yongping model oil emulsion have difficulty in forming water chains, since there aremuch asphaltenes and resins in the water-oil interface leading to high strength offilm. For Shuanghe oilemulsion drops are prevented from coalescing, because it contains a mass of paraffin, which can stabilizeemulsion at low temperature.

Parameters study on lateral buckling of submarine PIP pipelines

Zhang, Xinhu,Duan, Menglan,Wang, Yingying,Li, Tongtong Techno-Press 2016 Ocean systems engineering Vol.6 No.1

In meeting the technical needs for deepwater conditions and overcoming the shortfalls of single-layer pipes for deepwater applications, pipe-in-pipe (PIP) systems have been developed. While, for PIP pipelines directly laid on the seabed or with partial embedment, one of the primary service risks is lateral buckling. The critical axial force is a key factor governing the global lateral buckling response that has been paid much more attention. It is influenced by global imperfections, submerged weight, stiffness, pipe-soil interaction characteristics, et al. In this study, Finite Element Models for imperfect PIP systems are established on the basis of 3D beam element and tube-to-tube element in Abaqus. A parameter study was conducted to investigate the effects of these parameters on the critical axial force and post-buckling forms. These parameters include structural parameters such as imperfections, clearance, and bulkhead spacing, pipe/soil interaction parameter, for instance, axial and lateral friction properties between pipeline and seabed, and load parameter submerged weight. Python as a programming language is been used to realize parametric modeling in Abaqus. Some conclusions are obtained which can provide a guide for the design of PIP pipelines.

Study on an emulsion-type blockage removal agent for heavy oil recovery enhanced by polymer

Tongyu Zhu,Hongbin Yang,Haizhuang Jiang,Xin Kang,Menglan Li,Min Zhang,Wanli Kang,Bauyrzhan Sarsenbekuly,Saule Aidarova,Maratbek Gabdullin 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.89 No.-

In polymerflooding process, the poor solubility of polymer and the wrap of incompletely dissolvedpolymer particles with heavy oil lead to the generation of complicated blockage, which seriously affectsthe normal production of wells. Therefore, how to fabricate an effective blockage removal agent isparticularly important. Based on the blockage from Bohai Offshore Oilfield in China, a blockage removalagent composed of (0.5 wt% potassium persulfate + kerosene (the ratio of kerosene: blockage is 3:5)+0.3 wt% OP-10, the oil-water ratio is 1:9) was developed. The removal effect and mechanism werecharacterized by weight loss method and core test. Moreover, the emulsification property of the removalagent was also evaluated by microscopic appearance. The results showed that the blockage removal agentcan be formulated as an O/W emulsion and had good stability for more than 72 h. Core test showed thatthe permeability had a significant improvement after injection of removal agent. The emulsion-typeremoval agent can demulsify after contact with the blockage, then the oil-soluble detergent as internalphase in emulsion can be released which contributes to the wash off of heavy oil. Accompanied with thepolymer degradation by the oxidant, this agent realized the effective dissolution and removal of blockage.

Synthesis of multi-walled carbon nanotubes over tungsten-doped cobalt-based catalyst derived from a layered double hydroxide precursor

Meng Lan,Feng Li,Guoli Fan,Qilong Chen 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

Multi-walled carbon nanotubes (CNTs) were prepared over a series of W-doped Co-based catalysts derived from layered double hydroxide precursor by catalytic chemical vapor deposition (CCVD) of acetylene. The materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption experi-ments and Raman spectroscopy. The effect of the proportion of W in the Co-based catalysts on the carbon yield, diameter uniformity and quality of CNTs was investigated. The results demonstrated that with the increasing W/Co molar ratio from 0 to 1.0, both the mean number of walls and the average diameter of CNT produced over catalysts increased from about 8 to 28 nm and from about 12.1 to 23.7 nm, respectively. A small amount of tungsten added to the catalyst with the W/Co molar ratio of 0.3 could facilitate the dispersion of catalytically active Co species on the surface of support, and thus uniform and high-quality CNTs with a remarkably high yield of ca. 1600% were obtained.