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.

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.

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.

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。

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.

An optimized protocol using Steedman’s wax for high-sensitivity RNA in situ hybridization in shoot apical meristems and flower buds of cucumber

In situ mRNA hybridization(ISH)is a powerful tool for examining the spatiotemporal expression of genes in shoot apical meristems and flower buds of cucumber.The most common ISH protocol uses paraffin wax;however,embedding tissue in paraffin wax can take a long time and might result in RNA degradation and decreased signals.Here,we developed an optimized protocol to simplify the process and improve RNA sensitivity.We combined embedding tissue in low melting-point Steedman’s wax with processing tissue sections in solution,as in the whole-mount ISH method in the optimized protocol.Using the optimized protocol,we examined the expression patterns of the CLAVATA3(CLV3)and WUSCHEL(WUS)genes in shoot apical meristems and floral meristems of Cucumis sativus(cucumber)and Arabidopsis thaliana(Arabidopsis).The optimized protocol saved 4–5 days of experimental period compared with the standard ISH protocol using paraffin wax.Moreover,the optimized protocol achieved high signal sensitivity.The optimized protocol was successful for both cucumber and Arabidopsis,which indicates it might have general applicability to most plants.

Structures and Functions of Cuticular Wax in Postharvest Fruit and Its Regulation:A Comprehensive Review with Future Perspectives

Cuticular wax plays a major role in the growth and storage of plant fruits.The cuticular wax coating,which covers the outermost layer of a fruit’s epidermal cells,is insoluble in water.Cuticular wax is mainly composed of very long-chain fatty acids(VLCFAs);their derivatives,including esters,primary alcohols,secondary alcohols,aldehydes,and ketones;and triterpenoids.This complex mixture of lipids is probably biosynthesized in the epidermal cells of most plants and exuded onto the surface.Cuticular wax not only makes the fruit less susceptible to microbial infection but also reduces mechanical damage to the fruit,thereby maintaining the fruit’s commodity value.To date,research has mostly focused on the changes,function,and regulation of fruit wax before harvest,while ignoring the changes and functions of wax in fruit storage.This paper reviews on the composition,structure,and metabolic regulation of cuticular wax in fruits.It also focuses on postharvest factors affecting wax composition,such as storage temperature,relative humidity(RH),gas atmosphere,and as exogenous hormones;and the effects of wax on fruit postharvest quality,including water dispersion,fruit softening,physiological disorders,and disease resistance.These summaries may be of assistance in better understanding the changes in cuticular wax in postharvest fruit and the resulting effects on fruit quality.

Wax from Pyrolysis of Waste Plastics as a Potential Source of Phase Change Material for Thermal Energy Storage

Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyrolysis is deemed the most economical option. Currently, the wax obtained from the pyrolysis of waste plastics is mainly used as a feedstock to manufacture chemicals and fuels or added to asphalt for pavement construction, with no other applications of wax being reported. Herein, the thermal pyrolysis of three common waste polyolefin plastics: high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), was conducted at 450 ℃. The waste plastics-derived waxes were characterized and studied for a potential new application: phase change materials(PCMs) for thermal energy storage(TES). Gas chromatography–mass spectrometry analysis showed that paraffin makes up most of the composition of HDPE and LDPE waxes, whereas PP wax contains a mixture of naphthene, isoparaffin, olefin, and paraffin. Diff erential scanning calorimetry(DSC) analysis indicated that HDPE and LDPE waxes have a peak melting temperature of 33.8 ℃ and 40.3 ℃, with a relatively high latent heat of 103.2 J/g and 88.3 J/g, respectively, whereas the PP wax was found to have almost negligible latent heat. Fourier transform infrared spectroscopy and DSC results revealed good chemical and thermal stability of HDPE and LDPE waxes after 100 cycles of thermal cycling. Performance evaluation of the waxes was also conducted using a thermal storage pad to understand their thermoregulation characteristics for TES applications.

Emerging low-density polyethylene/paraffin wax/aluminum composite as a form-stable phase change thermal interface material

Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.

Overexpression of ZxABCG11 from Zygophyllum xanthoxylum enhances tolerance to drought and heat in alfalfa by increasing cuticular wax deposition

Drought and heat stresses cause yield losses in alfalfa,a forage crop cultivated worldwide.Improving its drought and heat tolerance is desirable for maintaining alfalfa productivity in hot,arid regions.Cuticular wax forms a protective barrier on aerial surfaces of land plants against environmental stresses.ABCG11encodes an ATP binding cassette(ABC) transporter that functions in the cuticular wax transport pathway.In this study,Zx ABCG11 from the xerophyte Zygophyllum xanthoxylum was introduced into alfalfa by Agrobacterium tumefaciens-mediated transformation.Compared to the wild type(WT),transgenic alfalfa displayed faster growth,higher wax crystal density,and thicker cuticle on leaves under normal condition.Under either drought or heat treatment in greenhouse conditions,the plant height and shoot biomass of transgenic lines were significantly higher than those of the WT.Transgenic alfalfa showed excellent growth and 50% greater hay yield than WT under field conditions in a hot,arid region.Overexpression of Zx ABCG11 up-regulated wax-related genes and resulted in more cuticular wax deposition,which contributed to reduction of cuticle permeability and thus increased water retention and photosynthesis capacity of transgenic alfalfa.Thus,overexpression of Zx ABCG11 can simultaneously improve biomass yield,drought and heat tolerance in alfalfa by increasing cuticular wax deposition.Our study provides a promising avenue for developing novel forage cultivars suitable for planting in hot,arid,marginal lands.

Fischer-Tropsch wax catalytic cracking for the production of low olefin and high octane number gasoline: Process optimization and heat effect calculation

To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.

Wax deposition modeling in oil-water stratified pipe flow

Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies.However,a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process.In this work,a three-dimensional(axial,radial,and angular)robust wax deposit model for oil-water stratified circular pipe flow was developed.The model of formation of a gel deposit based on the first principles of rheology was developed,associated with the results obtained from hydrodynamics and heat/mass transfer simulations.The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow.It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress,thereby leading to an increase in the degree of gelation as well as the deposit rate.Furthermore,a local deposit analysis in the circumferential direction was conducted,for water cut 75%and total flow rate 5 m3/h,which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points,where the oil-water interface contacts the inner wall,the deposition thickness quickly dropped to 0.It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.

An Experimental Study on the Interaction between Hydrate Formation and Wax Precipitation in Waxy Oil-in-Water Emulsions

The coupled formation of wax crystals and hydrates is a critical issue for the safety of deep-sea oil and gas exploration and subsea transport pipeline flow.Therefore,this paper conducts an experimental study on the characteristics of methane hydrate formation in a water-in-oil(W/O)system with different wax crystal contents and explores the influence of different initial experimental pressures on the induction period and maximum rate of hydrate formation.The wavelet function was introduced to process the reaction rate and calculate the maximum speed of hydrate formation.Notably,the higher the pressure,the smaller the maximum rate of hydrate formation.We observed that wax crystal precipitation increases the viscosity of the emulsion,which limits the diffusion of gas in the liquid phase during hydrate nucleation and thus delays the hydrate nucleation.The methane gas precipitation also affects the remaining fraction’s wax content and therefore affects the wax precipitation.Secondary hydrate formation was observed several times during the experiment,increasing the risk of pipeline blockage.Overall,this work provides insights into the effect of wax crystal precipitation on hydrate behaviour that could facilitate flow assurance applications in subsea multiphase pipelines and inform the safe transportation of oil and gas pipelines.

Application of Wax Therapy in Pain Care of Patients with Rheumatoid Arthritis

Objective: To investigate the effect of wax therapy in pain care of patients with rheumatoid arthritis. Methods: Convenience sampling method was used to select inpatients with rheumatoid arthritis admitted to the rheumatology and immunology department of a 3A hospital in Jingzhou City. 75 patients from January 2021 to June 2021 were selected as the control group, and 75 patients from January 2022 to June 2022 were selected as the observation group. The control group was given routine nursing, and the observation group was implemented wax therapy nursing on the basis of the control group. The relief of clinical symptoms (morning stiffness time, pain score) and quality of life score of the two groups were observed. Results: After intervention, there was statistical significance between the two groups (P Conclusion: Wax therapy can improve the time of morning stiffness, the degree of pain and the quality of life of patients with rheumatoid arthritis.

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.