Prediction Model of Wax Deposition Rate in Waxy Crude Oil Pipelines by Elman Neural Network Based on Improved Reptile Search Algorithm

A hard problem that hinders the movement of waxy crude oil is wax deposition in oil pipelines.To ensure the safe operation of crude oil pipelines,an accurate model must be developed to predict the rate of wax deposition in crude oil pipelines.Aiming at the shortcomings of the ENN prediction model,which easily falls into the local minimum value and weak generalization ability in the implementation process,an optimized ENN prediction model based on the IRSA is proposed.The validity of the new model was confirmed by the accurate prediction of two sets of experimental data on wax deposition in crude oil pipelines.The two groups of crude oil wax deposition rate case prediction results showed that the average absolute percentage errors of IRSA-ENN prediction models is 0.5476% and 0.7831%,respectively.Additionally,it shows a higher prediction accuracy compared to the ENN prediction model.In fact,the new model established by using the IRSA to optimize ENN can optimize the initial weights and thresholds in the prediction process,which can overcome the shortcomings of the ENN prediction model,such as weak generalization ability and tendency to fall into the local minimum value,so that it has the advantages of strong implementation and high prediction accuracy.

Probing the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil via molecular dynamics simulation

High content of asphaltenes and waxes leads to the high pour point and the poor flowability of heavy oil,which is adverse to its efficient development and its transportation in pipe.Understanding the interaction mechanism between asphaltene-wax is crucial to solve these problems,but it is still unclear.In this paper,molecular dynamics simulation was used to investigate the interaction between asphaltenewax and its effects on the crystallization behavior of waxes in heavy oil.Results show that molecules in pure wax are arranged in a paralleled geometry.But wax molecules in heavy oil,which are close to the surface of asphaltene aggregates,are bent and arranged irregularly.When the mass fraction of asphaltenes in asphaltene-wax system(ω_(asp))is 0-25 wt%,the attraction among wax molecules decreases and the bend degree of wax molecules increases with the increase ofω_(asp).Theω_(asp)increases from 0 to 25 wt%,and the attraction between asphaltene-wax is stronger than that among waxes.This causes that the wax precipitation point changes from 353 to 333 K.While theω_(asp)increases to 50 wt%,wax molecules are more dispersed owing to the steric hindrance of asphaltene aggregates,and the interaction among wax molecules transforms from attraction to repulsion.It causes that the ordered crystal structure of waxes can't be formed at normal temperature.Simultaneously,the asphaltene,with the higher molecular weight or the more hetero atoms,has more obvious inhibition to the formation of wax crystals.Besides,resins also have an obvious inhibition on the wax crystal due to the formation of asphalteneresin aggregates with a larger radius.Our results reveal the interaction mechanism between asphaltene-wax,and provide useful guidelines for the development of heavy oil.

Differences in leaf cuticular wax induced by whole-genome duplication in autotetraploid sour jujube

Drought-resistant plants exhibit strong water retention capability.In this regard,the autotetraploid sour jujube leaves exhibit better water retention than diploid leaves.Morphological comparisons and physiological comparisons of diploid and autotetraploid leaves showed that the autotetraploid leaves had thicker leaf cuticles and more leaf wax accumulation than the diploid leaves,which could reduce cuticle permeability and improve the drought tolerance of leaves.In this study,the cuticular wax crystalloids on the adaxial and abaxial sides of young and mature jujube leaves were observed in the two ploidy types,and unique cuticular wax crystalloids covering a large area of the cuticle on autotetraploid sour jujube leaves may provide an advantage in reducing leaf non-stomata transpiration and improving plant drought tolerance.Based on the transcriptome,115 differentially expressed genes between diploids and autotetraploids were further analyzed and found to be involved in the accumulation of cuticular wax components,including terpenoids,fatty acids,and lipids,as well as ABC transporter and wax biosynthetic process.Finally,14 genes differentially expressed between glossy autotetraploid leaves and nonglossy diploid leaves,such as LOC107414787,LOC107411574 and LOC107413721,were screened as candidate genes by qRT-PCR analysis.This findings provided insights into how polyploidization improved drought tolerance.

The effect of ethylene-vinyl acetate copolymer on the formation process of wax crystals and hydrates

Ethylene-vinyl acetate copolymer(EVA) as a kind of effective polymeric pour point depressant has been extensively used in the pipeline transportation of crude oil to inhibit wax deposition and improve the low temperature fluidity of crude oil. In this work, molecular dynamics simulations were performed to investigate the effect of EVA on wax-hydrate coexistence system to evaluate the application potentiality of EVA to the flow assurance of deep-sea oil-gas-water multiphase flow system. Our simulation results reveal that wax molecules gradually stretched and stacked from random coiling to a directional and ordered crystalline state during the process of wax solidification. The strong affinity of polar vinyl acetate side chains of EVA to neighboring water molecules made the EVA molecule prefer being in a curly state,which disrupted the ordered crystallization of surrounding wax molecules and delayed the solidification rate of wax cluster. In addition, it is found that EVA cocrystallized with wax molecules to form eutectic when the wax was fully solidified. The simulation results of hydrate nucleation and growth show that the EVA molecule displayed a two-sided effect on gas adsorption of wax crystals, which was the key factor that affected the nucleation and growth of hydrates in the methane-water system. The nonpolar hydrocarbon backbone of EVA increased the diffusion rate of methane and water, allowing more methane to diffuse to the surface of wax crystals, reducing the methane concentration in aqueous solutions and inhibiting the hydrate formation. On the other hand, the nonpolar vinyl acetate chains had a repulsive effect on methane, which reduced the adsorption area of methane on the eutectic surface and decreased the adsorption threshold value of the wax crystal. The excluded methane molecules would continue dissociating in the aqueous phase and participating in the nucleation and growth process of hydrates.Therefore, the probability of hydrate formation would be increased. It was worth noting that the inhibition performance of EVA on hydrate formation mainly played a significant role in the system with small wax crystal, while its hydrate promotion effect played a dominant role in the system with lager wax crystal. In summary, EVA could significantly inhibit both of the wax and hydrate deposition for the waxgas-water multiphase system with low wax content. When the wax content in the system was high, the role of EVA was mainly played in the alleviation of wax crystallization rather than the gas hydrates. The results of the present work can contribute to a better understanding of EVA on wax deposition and hydrate formation, and provide theoretical support of the potential industrial applications of EVA.

Experimental study on wax deposition of highly paraffinic oil in intermittent gas-oil flow in pipelines

Oil-gas two phase wax deposition is a fairly common and open-ended question in flow assurance of multiphase transportation pipelines.This paper investigated the two main aspects of oil-gas two phase wax deposition layer:apparent thickness and crystal structure characteristics.A typical highly paraffinic oil in Bohai Sea,China,was used as the experimental material to investigate the wax deposition thickness in oil-gas two phase under the influence of different oil temperatures,superficial gas/liquid phase velocities and gas-oil ratios by using multiphase flow loop experimental device.Just as in the classical theory of wax molecular diffusion,it showed that wax deposition thickness of oil-gas two phase increased with increasing oil temperature.Analysis of the impact of different superficial phase velocities found that the actual liquid flow heat transfer and shear stripping was the gas phase dominant mechanisms determining wax deposit thickness.In addition,the crystal structure of the wax deposition layer was characterized with the help of small-angle X-ray scattering(SAXS)for different circumferential positions,flow rates and gas-oil ratios.The bottom deposition layer had a complex crystal structure and high hardness,which were subject to change over flow rate variations.Furthermore,the SAXS results provided evidence that the indirect effect of the actual liquid velocity modified by the gas phase was the main mechanism.Our study of the effect of gas phase on the wax deposition of oil-gas two phase will help shed light onto the mechanism by which this important process occurs.Our findings address a very urgent need in the field of wax deposition of highly paraffinic oil to understand the flow security of oilgas two phase that occurs easily in multiphase field pipelines.

ZmCER1,a putative ECERIFERUM 1 protein in maize,functions in cuticular wax biosynthesis and bulliform cell development

The cuticular wax,acting as the ultimate defense barrier,is essential for the normal morphogenesis of plant organs.Despite this importance,the connection between wax composition and leaf development has not been thoroughly explored.In this study,we characterized a new maize mutant,ragged leaf4(rgd4),which exhibits crinkled and ragged leaves starting from the sixth leaf stage.The phenotype of rgd4 is conferred by ZmCER1,which encoding an aldehyde decarbonylase involved in wax biosynthesis.ZmCER1 function deficient mutant displayed reduced cuticular wax density and disordered bulliform cells(BCs),while ZmCER1 overexpressing plants exhibited the opposite effects,indicating that ZmCER1 regulates cuticular wax biosynthesis and BCs development.Additionally,as the density of cuticular wax increased,the water loss rate of detached leaf decreases,suggesting that ZmCER1 is positively correlated with plant drought tolerance.

涂装高浸透WAX应用说明

主要介绍了高浸透WAX材料的特性,以及基于现有设备基础进行相关的设备改造及注意事项。

Development of a SGJ-1 of Water-Based Anti-Wax Agent

The phenomenon of petroleum wax deposition is very common during oil well production. When the wax molecule condenses on the surface of the pipeline, it will hinder the exploitation of crude oil, reduce the recovery rate of crude oil, and may lead to the blockage of the pipeline when it is serious, so that the oil recovery work will stop. This phenomenon can be obviously changed by using wax cleaning agent. However, the low ignition point and toxicity of oil-based wax remover are not conducive to oil recovery. Therefore, a new water-based paraffin remover SGJ-1 was developed in this paper. The best formula is: wax dispersant 15%, wetting reversion agent 1%, sodium silicate 1%, alcohol cosolvent 8% and 75% water. Condensation point, wax dissolution rate and anti-wax performance of SGJ-1 water-based dewaxing and anti-waxing agent were tested by self-assembly testing device. The experimental results show that the condensation point of SGJ-1 is -34°C, the viscosity reduction effect is good under 35°C, and the wax dissolution rate is 0.0512 g/min, The highest wax prevention rate can reach 89.58% and the wax removal and wax prevention ability is excellent. Compared with other paraffin removers, SGJ-1 can also reduce the viscosity of crude oil, so it has a good development prospect.

Effect of surfactants and their blend with silica nanoparticles on wax deposition in a Malaysian crude oil

The present study investigated the wax deposition tendencies of a light Malaysian crude oil（42.4° API）, and the wax inhibiting potential of some surfactants and their blends with nanoparticles. With the knowledge that the majority of the wax inhibition research revolved around polymeric wax inhibitors, which cause environmental issues, we highlighted the potential of surfactants and their blend with SiO2 nanoparticles as wax deposition inhibitors. Different surfactants including oil-based, silane-based, Gemini and bio-surfactants were considered as primary surfactants. The primary surfactants and their respective blends at a concentration of 400 ppm were screened as wax inhibitor candidates using cold finger apparatus. The screening results showed a significant influence on the paraffin inhibition efficiency on wax deposition by using 400 ppm of silane-based surfactant, which decreased the wax deposition up to 53.9% as compared to that of the untreated crude oil. The inhibition efficiency among the silane-based surfactant（highest） and bio-surfactant（lowest）revealed an appreciable difference up to 36.5%. Furthermore, the wax from the treated sample was found to deposit in a thin gel-like form, which adhered inadequately to the surface of the cold finger. A further investigation by blending the 400 ppm silane-based surfactant with a 400 ppm SiO2 nanoparticle suspension in a load ratio of 3：1 found that the wax inhibition decreased up to 81% as compared to the scenario when they were not added. However, we have shown that the synergy between the silane-based surfactant and the nanoparticles is influenced by the concentration and load ratio of surfactant and nanoparticles, residence time, differential temperature and rotation rate.

Physical properties of wax deposits on the walls of crude pipelines

Wax deposits on the wall of a crude oil pipeline are a solid wax network of fine crystals, filled with oil, resin, asphaltene and other impurities. In this paper, a series of experiments on wax deposition in a laboratory flow loop were performed under different conditions （flow rate, temperature differential between crude oil and pipeline wall, and dissolved wax concentration gradient）, and the wax deposits were analyzed, so quantitative relationships among wax content, wax appearance temperature （WAT）, shear stress, and radial concentration gradient of dissolved wax at the solid/liquid interface were obtained. Finally, a model was established to predict WAT and the wax content of the deposit.

Pre-heating temperature induced flowability and wax deposition characteristics of crude oil adding wax inhibitors

This paper investigated the effects of pre-heating treatment temperatures(T_(pre))on the flowability and wax deposition characteristics of a typical waxy crude oil after adding wax inhibitors.It is found that there is little difference in wax precipitation exothermic characteristics of crude oils at different T_(pre),as well as the wax crystal solubility coefficient in the temperature range of 25-30℃.For the undoped crude oil,the flowability after wax precipitation gets much improved and the wax deposition is alleviated as T_(pre)increasing.At T_(pre)=50℃,the viscosity and wax deposition rate of crude oil adding wax inhibitors are higher than those of the undoped crude oil.When the T_(pre)increases to 60,70,and 80℃,the flowability of the doped crude oil are largely improved and the wax deposition is suppressed with the T_(pre)increase,but the wax content of wax deposit increases gradually.It is speculated that,on the one hand,the T_(pre)increase helps the dispersion of asphaltenes into smaller sizes,which facilitates the co-crystallization with paraffin waxes and generates more aggregated wax crystal flocs.This weakens the low-temperature gel structure and increases the solid concentration required for the crosslink to form the wax deposit.On the other hand,the decrease in viscosity increases the diffusion rate of wax molecules and accelerates the aging of wax deposits.The experimental results have important guiding significance for the pipeline transportation of doped crude oils.

Steedman’s wax包埋切片DAPI染色法证实铝诱导花生根尖细胞程序性死亡

【目的】检验Steedman’swax包埋切片DAPI染色法是否适用于观察花生根尖细胞核形态。【方法】分别采取100μmol/L AlCl3处理不同时间(0、4、8、12 h)后两个花生品种(铝敏感型中花2号和耐铝型99-1507)的根尖,经过Steedman’s wax包埋切片等一系列过程,利用荧光染料DAPI染色观察细胞核形态变化。【结果】100μmol/L AlCl3可引起花生根尖细胞核形态发生改变,核质浓缩、核边缘化、呈新月状等,具有明显的PCD特征。花生根尖细胞在铝胁迫下发生PCD,PCD程度与花生耐铝性呈负相关,与处理时间呈正相关。【结论】Steedman’swax包埋切片DAPI染色法是一种快速、高效的适用于观察花生根尖细胞核形态的方法。

Determination of wax pattern die profile for investment casting of turbine blades

In order to conform to dimensional tolerances, an efficient numerical method, displacement iterative compensation method, based on finite element methodology （FEM） was presented for the wax pattern die profile design of turbine blades. Casting shrinkages at different positions of the blade which was considered nonlinear thermo-mechanical casting deformations were calculated. Based on the displacement iterative compensation method proposed, the optimized wax pattern die profile can be established. For a A356 alloy blade, substantial reduction in dimensional and shape tolerances was achieved with the developed die shape optimization system. Numerical simulation result obtained by the proposed method shows a good agreement with the result measured experimentally. After four times iterations, compared with the CAD model of turbine blade, the total form error decreases to 0.001 978 mm from the orevious 0.515 815 mm.

用对称透射二维WAXS强度研究PET取向非晶态结构

用对称透射法，测试聚酯（PET）取向非晶试样的二维广角X射线散射相干强度Ie（K，α），将不同方位角α上的Ie（K，α）非晶重叠峰曲线进行计算机分解，获得分子链间原子散射引起的二个峰为A（K＝0．126）、B（K＝0．169）；分子链内原子散射引起的五个峰分别为C（K＝0．304）、D（K＝0．553）、E（K＝0．374）、F（K＝0．465）、G（K＝0．606），K单位为nm－1．分析了它们的结构起源以及主要峰参数与α的关系，得到PET取向非晶态的细微结构信息．

一种用于DAPI染色的方法——Steedman's wax包埋切片法

以植物的胚珠和子房为实验材料,介绍一种用Steedman swax包埋对组织切片中的细胞核进行DAPI染色的方法.Steedman swax作为一种低熔点多酯蜡,具有与石蜡相似的性质,切片方法同常规石蜡切片,适合于切成厚度大于5μm的连续切片.Steedman swax包埋的切片能成功地进行DAPI染色.与用压片法和Technovit7100或GMA包埋切片法进行的DAPI染色相比,用Steedman swax包埋切片法进行的DAPI染色具有廉价、操作简便、可进行连续切片、图象清晰等优点,特别在植物细胞程序化死亡 PCD 的研究中及细胞核DNA含量测定方面,有着较大的应用价值和潜能.

3个水稻WAX2同源基因表达的组织特异性及逆境响应特征

利用拟南芥的WAX2基因序列BLAST检索出3个水稻同源基因,命名为OsWAX2-1、OsWAX2-2和OsWAX2-3,与拟南芥WAX2基因的同源性分别为56.0%、55.2%和52.0%;其预测的编码蛋白与WAX2蛋白的同源性分别为61.5%、60.5%和64.7%。这3个蛋白都分别存在4个跨膜结构区和1个甾醇去饱和酶的保守区,说明它们都属于跨膜蛋白并可能与角质层的蜡质合成有关。采用半定量RT-PCR方法检测3个OsWAX2基因在水稻不同部位的表达情况,及高温、低温、NaCl、PEG和ABA5种处理对3个OsWAX2基因在转录水平表达的影响。结果表明,3个OsWAX2基因在水稻中的表达存在时空差异,3个基因在水稻萌动的胚中表达量都很高,OsWAX2-3基因在叶中的表达量最高;3个OsWAX2基因对高温、低温、盐、干旱及ABA胁迫响应也存在差别,OsWAX2-1只在ABA处理时增强表达;OsWAX2-2受高温、低温、盐、干旱胁迫及ABA诱导并且响应迅速。这一结果为进一步研究OsWAX2基因在水稻生长发育过程及逆境胁迫下的功能与作用机制提供了参考。

双轴拉伸PET薄膜成膜过程非晶区分子取向的WAXS研究

本文将常应用于小的角度范围(29_(CuK_α)<50°)的结晶峰和非晶峰的计算机分峰法,推广到PET薄膜的广角度散射范围(2θ_(CuK_α)=5°—140°)。通过对分离出来的表征非晶区分子链间分布的非晶主峰特征参数的分析,探讨了在特定拉伸条件下非晶区分子取向在成膜过程的变化。

Properties of Compound Systems of Paraffin Wax Emulsion and Copper Azole and Treated Wood

[Objective]Preservation and waterproof treatment are two crucial parts in wood protection, which can not only extend the service time, but also expand the application range of wood products. [Method] This work combined CA with paraffin wax emulsion to treat wood samples, and basic properties of the compound system, such as stability （storage stability and centrifugal stability）, particle size and pH val-ue, and water repel ency （water absorption, shrinkage and swel ing） of treated sam-ples were investigated. [Result and Conclusion] 1） the compound systems of CA and paraffin latex had a favorable miscibility and stability; 2） compared with untreated wood, CA-treated samples showed poor water repel ing properties, whereas samples treated with the compound systems indicated an obvious reduction in water absorp-tion, and the shrinkage and swel ing of them were improved as wel .

Thermodynamic Modeling of Wax Precipitation in Crude Oils

Most of the crude oils contain waxes which precipitate when temperature drops, resulting in deposition in pipelines and production equipment. It is necessary to set up a model which can predict the wax appearance tem-perature and the amount of solid precipitated in the different conditions. A modified thermodynamic solid-liquid equilibrium model to calculate wax precipitation in crude oil systems has been developed recently. The assumption that precipitated waxes consist of several solid phases is adopted in this research, and the solid-solid transition is also considered in the modified model. The properties of the pseudo-components are determined by using empirical correlations. New correlations for properties of solid-solid and solid-liquid transitions are also established in this work on the basis of the data from the literature. The results predicted by the proposed model for three crude oil systems are compared with the experimental data and the calculated results from the literature, and good agreement is observed.

The structure of integument and wax glands of Phenacoccus fraxinus(Hemiptera:Coccoidea:Pseudococcidae)

Using scanning electron microscopy and optical microscopy,we studied the structure of the integument and wax glands of the mealybug,Phenacoccus fraxinus Tang(Hemiptera:Coccoidea:Pseudococcidae).We observed the ultrastructure of four wax pores including trilocular,quinquelocular,and multilocular pores as well as tubular ducts,recording characteristics of their structure,size and distribution.We found that that the integument of the mealybug consists of three main layers-the procuticle,epidermis and basement membrane-and four sub-layers of the procuticle-the epicuticle,exocuticle,endocuticle and formation zone.The waxsecreting gland cells were closely arranged in epidermis.All of them were complex and composed of one central cell and two or more lateral cells.These complex cells possess a large common reservoir for collection and storage.Synthesized by the glandular cells,the wax is excreted outside integument through canals.