ENERGY & FUELS
·
2024
·
IF 5.2
Shi-dong Zhou,Zhen-hao Ren,Yi-song Yu,Yang Liu,Xiao-fang Lv,Hui Du
During the operation of deep-sea pipelines, the accumulation and deposition of hydrates are important reasons for pipeline blockage. The current main measure to solve the hydrate plugging problem is the addition of low-dose inhibitors (LDHIs), but it is not yet known whether the precipitation of wax crystals will affect their effectiveness. Therefore, in this study, the hydrate cohesive force within the wax-free/wax-containing system was directly measured by using a micromechanical force device (MMF) and the reasons for the change in cohesive force were analyzed from a morphological point of view. The results showed that glycine was effective in reducing the cohesion between hydrate particles in both wax-free/wax-containing systems and still exerted the effect of antiagglomeration agent (AA) at very low concentrations (as low as 0.10 wt %). Moreover, the optimum concentration of glycine was 0.50 wt %. At this concentration, the cohesive force decreased from 8.54 to 7.07 mN/m in the wax-free system, a decrease of about 17.2%, while the cohesive force decreased from 5.94 to 2.15 mN/m in the wax-containing system, a decrease of about 63.8%. By observation of the morphology of the hydrate particles, the presence of glycine was found to reduce the volume of the liquid bridge by changing the surface roughness and wettability of the particles, thereby reducing the cohesive force. And when wax was contained in the system, the wax further reduced the wettability by adsorbing on the surface of the hydrate particles. However, under certain AA conditions, the increase in wax concentration (from 0.1 to 0.3 wt %) resulted in the free water inside the hydrate being more likely to form liquid bridges with the surrounding particles, thus weakening the effect of AA. This work analyzes the effect on cohesive force in the simultaneous presence of LDHIs and wax from a morphological point of view, which is beneficial in providing more insights into securing safe hydrate flow management.
研究领域:
石油工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2021
·
IF 7.033
Yang Liu,Zhengnan Sun,Guolin Jing,Shuo Liu,Yihai Yang,Jianqi Xu
The alkali-catalyzed alcoholysis of polyethylene vinyl acetate (EVA) was used to obtain the product ethylene-vinyl alcohol copolymer (EVAL), and the grafting product poly(ethylene-vinyl alcohol)-graphene oxide (EVAL-GO) was prepared in the form of chemical grafting by utilization of the groups on the surface of GO and EVAL through the esterification reaction. The products were analyzed by Fourier transform infrared (FTIR), 1 H nuclear magnetic resonance (NMR) and Thermogravimetric (TG). The rheological properties of the oil sample and changes in the morphology of wax crystals were characterized by Advanced Hybrid Rheometer and polarized optical microscopy (POM) respectively. The degree of alcoholysis of EVAL reached 74.51%, and the grafting rate of EVAL-GO (0.5%) was 36.18%. Reduction of pour point and gel point of nanocomposite treated crude oil was 12 °C and 4 °C from undoped crude oil at the optimum additive concentration of 1000 mg/kg. Moreover, it decreased the viscosity and yield value of virgin crude oil by 99.5% and 78.3%, respectively. From the morphological analysis, it was indicated that EVAL-GO could make the wax crystals form sphere-like crystals, and the increased void space promoting more liquid oil to be released thus significantly improving the low-temperature fluidity of Daqing waxy crude oil.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Xinjie Sun,Lingli Jia,Xinyuan Li,Shanrong Zhang,Yiting Wang,Mingwang Fan,Jun Xu
Wax precipitation causes numerous challenges in the transportation and refining of crude oil. Wax deposition can be decreased and the flowability of waxy crude oil in cold temperatures can be increased by addition of polymer additives in the crude oil. Sequentially well-structured polymers synthesized by reversibly additive fragment chain transfer (RAFT) polymerization enhance the capability to inhibit the growing of wax crystals. In this paper, star chain-transfer agents (star-CTA) was synthesized by esterifying polyol with a tri-thiocarbonate RAFT reagent. Then, poly octadecyl acrylate-maleic anhydride (POM) copolymers with linear and star structure (3, 4, 6 arms) were synthesized via RAFT polymerization. The chemical structures were then characterized using FT-IR, 1 H NMR and GPC approaches. The effects of star copolymers on wax crystallization and cold flowability were analyzed by DSC, XRD, polarized light microscopy and rheology. The transformation from lamellar to fibrous crystals and a decrease in fractal dimensions of crystal growth upon adding all polymers were observed through kinetics of isothermal crystallization and non-isothermal crystallization (NIC) using DSC. Upon further calculations, the crystallization activation energy of NIC increased from 34.40 kJ/mol to 63.22 kJ/mol with the increase of arms. Revealed by XRD, both of the relative crystallinity index and the grain size of crystals are reduced by polymers. Further, the growth along the x and z axes is suppressed, resulting in fibrous growth. The viscosity initially decreases and then increases as the number of arms of polymer increases, with 4-arms POM (4X-POM) reducing the viscosity by 64.63 %. The present work reveals the mechanism of inhibiting wax crystal growth by star polymers, providing valuable theoretical guidance for the practical application.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2024
·
IF 3.7
Donghai Yang,Mofan Li,Qing Yun,Huayao Sun,Qing Li,Xuedong Gao,Chaohui Chen,Limin He
Electrocoalescence technology can efficiently dehydrate waxy crude oil but the mechanisms are still unclear. Herein, the continuous microscopic behaviors of droplet falling, deformation, and coalescence were experimentally investigated to clarify the dynamic response mechanism of droplet in waxy oil under an electric field. The results showed the droplet falling under both gravity and electrostatic attraction to deform by the electric field force. Moreover, the expansion and clamping of the liquid bridge resulted from the competition between electric field force and capillary force. However, the precipitated wax crystals reduced the kinetic energy of the droplet and affected its external circulation, thus delaying the falling time. In addition, the wax crystals with interfacial activity adsorbed on the oil-water interface and cross-linked to form a spatial network structure, thereby weakening droplet deformation, hindering liquid film drainage, and inhibiting liquid bridge expansion. Importantly, the droplet adsorbed wax crystals exhibited interfacial elasticity, which makes them more inclined to partial coalescence. The low-frequency pulsed direct current (PUDC) electric field with high strength intermittent effect displayed the most obvious inhibition effect on the wax crystals. Overall, these findings look promising for future design and optimization of high-efficiency electric dehydrators and related fields.
研究领域:
石油工程
·
界面科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
PETROLEUM SCIENCE AND TECHNOLOGY
·
2019
·
IF 1.07
Weichao Du,Yongfei Li,Bo Yun,Jie Zhang,Rongjun Zhang,Gang Chen
In this paper, four novel cyclohexanone-alcohol hemiketals (KL-1, KL-2, KL-3, KL-4) as waxy crude oil flow improver have been prepared by cyclohexanone and 1-pentanol, 1-Hexanol, 1-heptanol, 1-octanol. Evaluation results demonstrate the hemiketal compounds have obvious effect on the viscosity and pour point of Henan crude oil. DSC analysis showed that waxing point and waxing peak decreased to a certain degree in 0.05% hemiketal solutions. Wax crystal morphology analysis indicated the four hemiketals played a role of nucleation in the process of waxy crude oil decoagulation, and in that way acts as waxy crude oil flow improver.
研究领域:
石油化学
·
材料科学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2019
·
IF 3.021
Hailin Yu,Zhengnan Sun,Guolin Jing,Zhiwei Zhen,Yang Liu,Kai Guo
Nanocomposite pour point depressants (PPDs) provide a new way to further improve the fluidity of waxy crude oil at low temperatures, which has important application values in pipeline transportation. In this work, the effect of ethylene-vinyl acetate (EVA) doped with magnetic spherical nanoparticles of Fe3O4 (30 nm) on the morphology of wax crystals and the flow behavior of Daqing crude oil was investigated by polarized optical microscopy and rheological testing. The results showed that, compared to the EVA PPD doped with spherical nano-SiO2 (with the same size), the EVA (VA = 28%)/Fe3O4 nanocomposite PPD caused Daqing crude oil to have a more compact and regular wax crystal structure and a weaker gel structure because of the synergistic effect of magnetic materials and heterogeneous nucleation. This study examines the mechanism of nanocomposite PPDs and provides a new perspective for the development of new nanohybrid PPDs.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
PETROLEUM SCIENCE AND TECHNOLOGY
·
2021
·
IF 1.268
Zihao Huang,Xin Pu,Jiawen Hu,Jin Gu,Jichang Liu
A series of poly (n-alkyl acrylate-maleic anhydride) with different molecular weights were prepared as pour point depressants (PPDs) for JENM waxy crude oil obtained from the China-Myanmar crude oil pipeline. The crystallization temperature, wax morphology, and rheological behavior of crude oil were analyzed by differential scanning calorimetry, polarizing microscope, and rotary rheometer, respectively. The results indicate that the molecular weight significantly affects the performance of the pour point depressant. When the weight-average molecular weight (Mw) of copolymers were ranging from 60,000 to 70,000, it has a better pour point depression effect for JENM crude oil. The added copolymer (MW = 68,300) has achieved optimal performance which decreased the pour point of crude oil from 30 to 19 °C and crystallization temperature from 39.5 to 36.1 °C with the smallest wax crystal size and the 96.7% reduction viscosity.
研究领域:
石油化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Petroleum Science
·
2023
·
IF 5.6
Yang Liu,Zheng-Nan Sun,Sheng-Zhu Ji,Yi-Hai Yang,Jian-Qi Xu,Guo-Lin Jing
The nanocomposite EVAL-CNT was produced by chemical grafting in the solution system through the esterification of ethylene-vinyl alcohol copolymer (EVAL) and carboxylated multi-walled carbon nanotubes (O-MWCNT), and its structural properties were characterized. The improvement of the rheological properties of the waxy oil system by the novel pour point depressant was investigated using macroscopic rheological measurements and microscopic observations. The results showed that EVAL-CNT nanocomposite pour point depressant (PPD) could significantly reduce the pour point and improve the low temperature fluidity of crude oil and had better performance than EVAL-GO at the same addition level. The best effect was achieved at the dosing concentration of 400 ppm, which reduced the pour point by 13 °C and the low-temperature viscosity by 85.4%. The nanocomposites dispersed in the oil phase influenced the precipitation and crystallization of wax molecules through heterogeneous crystallization templates, which led to the increase of wax crystal size and compact structure and changed the wax crystal morphology, which had a better effect on the rheological properties of waxy oil.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Petroleum Science
·
2024
·
IF 6
Yang Liu,Zheng-Nan Sun,Guo-Lin Jing,Yi-Hai Yang,Hui Jiang,Xiao-Yan Liu
The effect of alcoholic polyethylene-vinyl acetate (EVA) product ethylene-vinyl alcohol copolymer (EVAL) on the low-temperature flow properties of model oil containing asphaltene (ASP) was investigated. The change of wax crystal microscopic morphology of model oil before and after modification were examined, and the influence of asphaltene mass fraction on the rheological improvement effect of EVAL was analyzed. The composite system of EVAL and asphaltene significantly reduced the pour point, gel point, apparent viscosity, storage modulus and loss modulus of waxy oil at low temperatures. When the EVAL concentration is 400 ppm and the asphaltene mass fraction is 0.5 wt%, the synergistic effect of the two is optimal, which can reduce the pour point by 17 °C and the modulus value by more than 98%. The introduction of EVAL strengthens the interaction between asphaltenes and wax crystals, forming EVAL-ASP aggregates, which promote the adsorption of wax crystals on asphaltenes to form composite particles, and the polar groups prevent the aggregation of wax crystals and reduce the size of wax crystals, thus greatly improving the fluidity of waxy oils.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2015
·
IF 2.587
Jun Xu,Hejian Jiang,Tao Li,Xiaoming Wei,Tongshuai Wang,Jing Huang,Weina Wang,Anthony L. Smith,Jie Wang,Rui Zhang,Yisheng Xu,Li Li,Robert K. Prud’homme,Xuhong Guo
Modification of the paraffin crystallization and flow ability of waxy crude oil is of vital importance during transportation and restart processes at low temperature. To investigate the influence of pendants in comb-type copolymers on the cold flow ability of crude oil, maleic anhydride-α-octadecene copolymer and its derivatives with octadecyl (MAC), phenyl (AMAC), or naphthalene (NMAC) pendants were synthesized. These derivatives, when added to waxy crude oil, change the size and quantity of the paraffin crystals observed by polarizing light microscopy (PLM), improve the flow ability of waxy oils by reducing the viscosity and yield stress revealed by rheometer, and decrease the paraffin crystallization temperature and quantity of wax precipitation determined by differential scanning calorimetry (DSC). AMAC had the greatest effect followed by MAC and NMAC, respectively. It seems that small aromatic pendants improve the flow ability of waxy oils by adsorbing on the surface of asphaltenes, while large aromatic pendants impair the assembly of copolymers with asphaltenes by a higher steric hindrance.
研究领域:
石油化学
·
胶体与界面化学
·
流变学
·
能源材料
·
油气储运工程
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2012
·
IF 2.721
Yumin Wu,Guangdi Ni,Fei Yang,Chuanxian Li,Guoliang Dong
To investigate the influence of structure variables of polymeric additives on the pour-point depression and rheological behavior of waxy crude oil, maleic anhydride co-polymer and its derivatives with different polar and/or aromatic pendant chains were designed and synthesized. All prepared additives were characterized by Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). The pour-point and rheological properties of Changqing (CQ) crude oil with a low asphaltene content before and after additive beneficiation were studied in detail. Differential scanning calorimetry (DSC) and polarizing light microscopy were employed to gain insight on the interactions between such additives and wax crystals. The results are encouraging and showed that all four polymeric additives exhibited good efficiency as flow improvers in CQ crude oil. The reduction of pour-point and rheological parameters after additive addition largely related to the polymer structure. The polymer containing aromatic units showed the best performance, which could depress the pour point by 19 °C and decrease the yield stress as well as viscosity to a large extent.
研究领域:
石油工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Processes
·
2023
·Vol. 11
·期 4
·1159
·
IF 3.5
ZhengNan Sun,Biao Yan,GuoLin Jing,YiHai Yang,HongJing Li,FuNing Zhang
Differences in the synthesis methods can affect the performance of nanocomposite materials. The synthesis methods of SiO2-based nanocomposite pour point depressants synthesized by chemical hybrid are mostly in situ polymerization and chemical grafting. However, there are still some gaps in the synthesis of nanocomposites using chemical grafting. In this paper, the amino-modified Nano-SiO2and octamethyl methacrylate-maleic anhydride copolymer was used to prepare PM18-g-NSiO2by an amidation reaction, and the product was compared with PM18/SiO2prepared by the solution blending method. The characterization results of FT-IR and SEM showed that the chemical bond formed between PM18 and NSiO2and PM18-g-NSiO2showed a more regular morphology structure. The results of rheological tests showed that the optimal concentration of PM18-g-NSiO2and PM18/SiO2is 300 mg·kg−1, but the decrease of PM18-g-NSiO2is 19 °C, while the decrease of PM18/SiO2is only 13 °C. The lowest viscosity of model oil added PM18-g-NSiO2was only 214 mPa·s while PM18/SiO2reached 453 mPa·s. The wax crystal structure after adding PM18-g-NSiO2is also more regular and smaller compared to PM18/SiO2. We concluded that differences in the synthesis methods may lead to the different coverage of the polymer on the surface of the nanoparticle.Keywords:nano-SiO2;polymethacrylate;nanocomposite pour point depressant;flow properties;wax crystal
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）