磁场对油田污水硫酸钙结垢的影响研究

采用两种不相容水混合的方式,实验研究了磁场对硫酸钙结垢的静态与动态影响。结果显示,常温放置时,先磁化成垢阴离子盐溶液和成垢阳离子盐溶液中的两种或一种然后再混合,都能防止和延缓硫酸钙结垢。对流动的流体磁化后,单位时间挂片上的结垢量减小,管线中的结垢量降低。用l号磁化器磁化后单位时间挂片的平均结垢量比不磁化实验时挂片的平均结垢量减少了35％：单位时间管线前4米的平均结垢量比不磁化实验时管线前4米的平均结垢量减少了60%以上,第5米减少了50％,第6米减少了23％。用2号磁化罂磁化后单位时间挂片的平均结垢盘比不磁化实验减少了47％,单位时间管线中的平均结垢量减少了70%以上。     

碳酸钙型油田水结垢特性实验分析

为了研究油田水在不同温度、不同离子浓度下的结垢规律,对碳酸钙型油田水进行了实验分析。采用静态实验的方法,通过改变模拟油田水的温度、离子浓度和加热时间,得到了不同条件下的结垢规律。实验结果表明,油田水的临界结垢温度为42.5℃左右,主要沉淀离子钙离子的浓度对临界结垢温度有影响。在一定实验条件下,随着钙离子浓度的增加,油田水的临界结垢温度将降低。该实验结果可为油田现场及集输管道的温度设定提供参考。     

油田水结垢及其影响因素的研究进展

油田水结垢已成为国内外油田面临的一大问题.结垢的形成主要取决于微溶或难溶盐是否达到过饱和,以及盐类结晶的生长历程.不同的影响因素对结垢的影响程度不同.本文综述了温度、压力、pH值、水质成分、流速和管道表面状况等因素对油田水结垢的影响,可为防垢/阻垢提供理论支持和相应对策.     

浅谈油田清垢与防垢技术

油田采出水及注水系统的水含有较多的溶解盐类,当工况变化时容易析出、沉淀、产生水垢。而“油田油井清垢与防垢技术”就是通过物理或化学方法对不同成因的油井结垢进行清除和预防的一门学科。朝阳沟油田油井及管道清的防垢技术的建立是在实验室内模拟结垢的过程和相关实验的基础上,针对朝阳沟油田油井的情况进行结垢分析,针对性很强,合成的复配型防垢剂能够降低井口的加药量,并且除垢的效果明显。     

油田集输环境低表面能改性聚烯烃的防垢性能

针对油田集输除垢成本高、流程复杂的问题，以低表面能改性聚烯烃(LH-PE)在油田集输环境中的防垢性能为研究对象，以长庆油田第五采油厂采出水模拟溶液为介质，采用室内静态结垢、流动环道动态结垢相结合的方法分析温度、流量、离子浓度对LH-PE表面结垢量的影响。结果表明，温度较高时，结垢在短时间内发生，超过40℃时，结垢量大幅增加；流量低于407.68 L/h时，垢晶析出沉积大于介质流动剥蚀，结垢量呈增加趋势；流量超过407.68 L/h后，30℃时结垢量随流量增大而减少，40,50℃时结垢量随流量增大而增加，这是因为介质高温导致垢晶析出沉积加剧；HCO3-在结垢中起主要作用；垢晶以松散的文石、球霰石为主。同时，在长庆油田第五采油厂对LH-PE内衬的钢丝增强复合管进行试用，高压清水扫线后获得大块垢样，其表面粗糙且有冲积壑，这说明扫线可轻易清除污垢。上述结果表明，LH-PE在油田集输中应用时虽不能避免结垢，但形成的污垢可通过高压清水扫线清除，能节约除垢成本、简化除垢流程，可用于油田集输环境。     

超声波除碳酸钙垢的实验研究

目前,超声波是一种在工业中广泛应用的技术,可以用于油田管道的污垢清理。为了更加深入研究超声波除碳酸钙垢的效果,有必要探究超声波的参数对除垢率的影响。在实验室条件下,组装了一套超声波除垢设备,通过改变超声波的频率、辐照时间和辐照温度,分别处理Q235钢制挂片上的碳酸钙垢,采用处理前和处理后挂片质量差的方法来评价除垢效果。实验结果表明在频率为28 kHz、辐照时间为10 min和辐照温度为40℃的条件下,超声波除碳酸钙垢能力强、效果好。因此,优选出超声波不同参数之间的组合对提高除碳酸钙垢率至关重要。     

硫酸钡结垢影响因素及防垢剂性能评价

为了研究硫酸钡结垢量的影响因素,室内开展了成垢离子浓度、温度、矿化度和pH值对硫酸钡结垢量的影响实验,并考察了4种防垢剂(HEDP、ATMP、PBTCA、HFGJ-26)对硫酸钡垢的防垢效果。结果表明,随着成垢离子浓度的增大和pH值的升高,硫酸钡结垢量逐渐增加;而随着温度和矿化度的升高,硫酸钡结垢量逐渐减少。硫酸钡防垢剂效果评价实验表明,防垢剂HFGJ-26具有良好的防硫酸钡垢效果,其加量在50 mg·L~(-1)时,防垢率可以达到85%以上,能够对硫酸钡垢的形成起到良好的抑制作用。     

弱碱三元复合驱油井结垢影响因素的研究

研究了弱碱三元复合驱油井水结垢的主要影响因素和基本规律,并通过挂片试验考察了不同钢材的结垢差异。结果表明:碳酸盐垢是主要结垢类型,其成垢率受温度、CO_2浓度、矿化度等因素的影响较大。当反应6 h时,在25,45,65℃的成垢率分别为40.07%,57.12%,87%;密闭系统、敞口系统、鼓泡系统6 h结垢率分别为27%,57.12%,85%。矿化度试验结果表明:在5 g/L时成垢率达到最高值82.12%。同时,油管材质会影响模拟结垢水中碳酸钙的结垢,在6~24 h内,各材质加速模拟结垢水中钙结垢由大到小的顺序依次为铸铁、321不锈钢、P110钢、N80钢、45#碳钢。实际生产中应使用平滑的管材,可通过镀膜、涂层等方式对管材进行处理。     

渤海SZ36-1油田注水结垢趋势预测与试验验证

无机结垢是油田注水过程中的严重问题之一,结垢造成了在油田开采过程中较大的经济损失,为了高效开发油田。应对结垢进行科学合理的预测,从而采用相应的防治措施。本文主要通过对渤海SZ36-1油田的地层特征及注入水特征的分析,判断所结的垢可能为碳酸钙垢和硫酸钙垢,编制相应的软件对碳酸钙垢和硫酸钙垢进行了预测。并通过静态结垢试验验证了理论预测结果。结果表明,在该油田的注水过程中有碳酸钙垢形成,但硫酸钙垢不是主要成垢类型;结垢量随温度的上升而增大。     

油田采出水结垢及配伍性实验理论研究

目前,我国大部分油田已经进入开发的中后期,普遍采用的是注水开发工艺、多层位混合开采和多层位混合输送的处理工艺。若注入水和地层水之间不配伍或者不同层位采出水之间配伍性差,就会形成各种类型的油田结垢。结垢不仅造成储层堵塞,会给储层带来伤害,也会给设备和集输管道带来不同程度的腐蚀,降低设备的传热速率和堵塞管道的危害。本文主要介绍了油田采出水中垢的结垢成因、结垢危害、结垢趋势预测以及防垢技术,并以此作为配伍性实验理论研究的基础,对混采混输及回注工艺具有一定的现实指导意义。     

碱对镀锌铁表面CaCO3污垢生长特性的影响机理研究

为解决因水结垢造成的管线堵塞问题,提出了变被动结垢为主动结垢的思路。针对某油田注入水,以镀锌铁为研究基质,综合动态模拟剪切实验以及SEM、EDS和浊度测试,探究碱类型和浓度对CaCO₃污垢生长特性的影响机理。结果表明5种常用碱——碳酸钠Na₂CO₃、碳酸氢钠NaHCO₃、三乙醇胺TEOA、氢氧化钙Ca(OH)₂和氧化钙CaO对污垢结垢量、失钙率及结垢诱导期影响各异,其中Na₂CO₃对失钙速率影响显著,而CaO对结垢速率影响较为明显。其次,不同碱促使污垢形成不同的晶型晶貌,其中方块状和层状垢物易于在材料表面堆积,即有利于结垢。最后,碱浓度对污垢生长影响具有双重性,存在抑垢和促垢浓度区间。     

Experimental investigation and theoretical modeling on scale behaviors of high salinity wastewater in zero liquid discharge process of coal chemical industry

Zero liquid discharge (ZLD) treatment and reuse equipment of high salinity wastewater in coal-chemical industry often occur in various types of blockage problems because of high salt content, affecting the long-term stability of the device. In this study, the effects of solution temperature, steel, reaction time and wall roughness on fouling were investigated. The changes in the contents of fouling and fouling substances were qualitatively and quantitatively analyzed by XRD and EDS respectively, and the formation of scale was observed by SEM. The results show that with temperature increasing, Q235 steel is the most difficult to scale. Scaling rate of all salt scales reaches a maximum after 12 h, and the fouling rate decreases significantly from 12 to 48 h. It gradually stabilizes at 48 to 96 h. With the roughness increasing, the thickness of fouling layer increases, and a linear relationship is presented for 1 to 10 h. By comparing actual and simulated wastewater scaling rates, the relationship between actual and simulated wastewater scaling rates is y=ax^-0.494. The composition of the scale was analyzed, calcium carbonate is the main product and increases with fouling time. Based on the above-mentioned results combining literatures, the hybrid prediction model with calcium carbonate as the main product is put forward. It is discussed microscopically that calcium carbonate is converted from aragonite and vaterite in a thermodynamically metastable state to calcite in a thermodynamically stable state.     

流动过冷沸腾传热强化及阻垢

在流动沸腾传热实验中,考察了CaCO3污垢溶液的形成过程及各种工艺条件对流动过冷沸腾传热的影响. 研究条件包括流体速度、溶液温度、CaCO3溶液浓度及热通量,实验中发现了一些规律. 同时还考察了不同阻垢剂[聚天冬氨酸(PASP)、2-膦酸丁烷-1,2,4-三羧酸(PBTCA)及氨基三甲叉膦酸(ATMP)]对流动过冷沸腾传热的影响. 结果表明,所选阻垢剂均能抑制污垢的生成并降低了污垢热阻,而且存在最佳浓度范围. 但不同阻垢剂的阻垢效果不尽相同,在本实验条件下,ATMP的阻垢效果最好,PBTCA次之,PASP的阻垢效果较差.     

管道结垢机理及影响因素分析

油田管道结垢是国内外油田生产面临的普遍问题。针对油田结垢,从压力的影响、结晶动力学因素、流体动力学因素三大类因素入手,分析了管道结垢的影响机理。     

冷指实验研究碳酸钡结垢规律

污垢中的主要成分是碳酸钙,还有碳酸钡、硫酸钡、镁盐、硫酸锶等。国内外学者对碳酸钙结垢规律的研究很多,对碳酸钡的研究相对较少一些。通过冷指实验,控制离子浓度、反应温度、pH值、反应时间和搅拌速度以及溶液的过饱和度,以研究这些参数对碳酸钡结垢的影响。结果表明,碳酸钡垢的生长速率随着温度的增加而增加,随着流速的增加而减小,pH为9时最小,浓度对其生长速率的影响不甚明显。利用冷指实验研究碳酸钡结垢规律是一种较新的方法,其研究成果为油田除垢防垢提供一定的理论依据。     

电磁场对换热表面CaCO3结垢行为及其形态影响的实验研究

基于水处理技术抑垢及缓蚀效果在线监测实验台,进行了换热器表面污垢在电磁处理下生长特性的半工业性实验研究。通过污垢热阻的在线监测跟踪换热器表面碳酸钙的结垢过程。利用Quanta 200扫描电子显微镜及X'Pert Pro X射线衍射仪对污垢样本的晶型、晶貌进行了定性和定量分析,表述了电磁场对碳酸钙晶型及晶貌的影响。实验结果表明:电磁场能降低换热器表面的结垢速率,垢样中方解石质量分数由100%降低为40.55%,文石质量分数增加为59.45%。     

Membrane autopsy to investigate CaCO3 scale formation in pilot‐scale,submerged membrane bioreactor treating calcium‐rich wastewater

BACKGROUND: Membrane scaling is an area of research interest because it can deteriorate membrane performance. The extent to which membrane scaling is produced varies depending upon the concentration of scale‐forming species such as calcium on the membrane surface. Bench‐scale tests have been conducted to better understand membrane scaling in submerged membrane reactors (MBR). However, relatively few studies of membrane scaling in pilot‐scale, submerged MBR have been reported. The objective of this study was to perform membrane autopsy work to analyze membrane scaling in a submerged MBR treating calcium‐rich wastewater. RESULTS: Membrane autopsy work provided evidence that deposition of calcium carbonate (CaCO₃) scale occurred on the membrane surface at the completion of pilot‐scale, submerged MBR operation. The CaCO₃ scaling resulted in significant external fouling on the surface of the membrane. The membrane scaling increased the rejection of calcium with MF membranes. However, the level of CaCO₃ scaling as internal fouling (in the pores) was almost negligible. This autopsy work also showed that aeration did not play a major role in controlling CaCO₃ scaling at the membrane surface in a submerged MBR. Chemical cleaning using citric acid solution efficiently removed CaCO₃ scale from the membrane. Combining citric acid with sodium hypochlorite pretreatment provided synergistic effects, further reducing CaCO₃ scale formation. CONCLUSION: The carbonate salt of calcium leads to precipitation resulting in surface fouling of membranes, and this cannot be removed physically by aeration in a submerged MBR treating calcium‐rich wastewater. It is necessary to combine properly‐selected cleaning strategies with submerged MBR treating wastewater containing a high potential for inorganic chemical precipitates. Copyright © 2009 Society of Chemical Industry     

碳酸钙在流动过冷沸腾条件下的结垢机理研究

Fouling of heat transfer surfaces during subcooled flow boiling is a frequent engineering problem in process industries. It has been generally observed that the deposits in such industrial systems consist mainly of calcium carbonate （CaCO3）, which has inverse solubility characteristics. This investigation focused on the mechanism to control deposition and the morphology of crystalline deposits. A series of experiments were carried out at different surface and bulk temperatures, fluid velocities and salt ion concentrations. It is shown that the deposition rate is controlled by different mechanism in the range of experimental parameters, depending on salt ion concentration. At higher ion concentration, the fouling rate increases linearly with surface temperature and the effect of flow velocity on deposition rate is quite strong, suggesting that mass diffusion controls the fouling process. On the contrary, at lower ion concentration, the fouling rate increases exponentially with surface temperature and is independent of the velocity, illustrating that surface reaction controls the fouling process. By analysis of the morphology of scale, two types of crystal （calcite and aragonite） are formed. The lower the temperature and ion concentration, the longer the induction period and the higher the percentage of calcite nreciDitated.     

Factors Affecting Scale Formation in Sea Water Environments – An Experimental Approach

Sea water is a complex aqueous environment with a large tendency for scale formation, which is usually ascribed to scaling from dissolved salts and suspended particles. Scale formation is causing many problems in thermal processes such as desalination and steam generation plants. In a typical desalination plant, ca. 40 % of the heat transfer area is provided to allow for scale formation problems, which is equivalent to a ca. 10 % increase of the whole capital cost of the plant. The main constituents forming scale in sea water environments, i.e., calcium carbonate, calcium sulfate and magnesium hydroxide, are extensively investigated in the present work. In order to obtain a better understanding of the scaling tendency of the seawater environment, an experimental unit was precisely designed and coupled with a data acquisition system for continuous monitoring of the investigated parameters. Significant factors affecting scale formation such as concentration of salts, flow velocity, water temperature and pH of the environments were studied at length using mild steel and stainless steel (smooth and rough). Hydrodynamic parameters such as Reynolds number and shear stress were used in the analysis of the collected data and revealed the role of shear stress in the effective removal of scale. The Kern‐Seaton scale model was used to calculate the fouling resistance in each case and the values obtained were compared with the experimental results. A modification of this model was also undertaken to provide better agreement with experimental findings.