胶体稳定性对渣油加氢装置反应进料/反应产物换热器结垢影响初探

在渣油加氢装置现场操作中,反应进料/反应产物换热器已成为制约装置长周期运行的关键因素之一。通过对原料油胶体稳定性的分析,探寻渣油加氢高压换热器结垢严重、换热效率下降、运行周期缩短等问题的潜在原因。     

渣油加工流程选择及其运行优化

分析了脱碳型、加氢型两种渣油加工工艺的优缺点,介绍了国内某石化公司的渣油加工流程,以及溶剂脱沥青、蜡油加氢处理、催化裂化、部分氧化及气电联产(IGCC)等主要渣油加工装置组成情况,阐述了该公司渣油加工运行及流程优化思路,并对渣油加工装置的运行、标定情况进行分析,对IGCC装置的经济性进行评价,对不同油价下的渣油加工路线及其运行优化进行了总结,渣油溶剂脱沥青—脱沥青油加氢处理—脱油沥青气化制氢的工艺成熟,运行平稳,清洁环保,将脱油沥青用于制氢是合适的工艺路线,并有经济性。     

渣油组成和结构分析及加工方案探讨

介绍国内外多种减压渣油的组成和形态分析结果,着重剖析沥青质、胶质的结构。列举了固定床渣油加氢前后三组分的特点;概括了渣油重溶剂脱沥青油杂质的残留率及加氢后数据;阐述了Ni和V的存在形态及反应转化、沥青质中氮化物种类及脱氮催化剂的现状。针对渣油加氢催化剂结焦、金属沉积、氮化物中毒问题,指出应注意的事项,渣油加工倾向于采用溶剂脱沥青-重蜡油加氢-催化裂化组合工艺。     

渣油中沥青质的分子结构及反应性能的研究进展

沥青质在渣油的组成中占很大的一部分,在渣油加氢反应过程中,沥青质的转化是渣油加氢转化的难点。研究沥青质结构有助于更好地加工渣油。在前人的研究基础上概括了研究沥青质结构、组成的方法,并对于沥青质的反应性能作了分析,有助于对沥青质进行更深入的研究。     

固定床渣油加氢催化剂表面积炭及抑制研究进展

固定床渣油加氢技术是重质油轻质化的重要手段,积炭是造成催化剂失活、缩短渣油加氢装置运行周期的重要原因之一。本文介绍了固定床渣油加氢反应时催化剂积炭的来源、积炭类型及形成机理、影响积炭形成的因素、抑制催化剂积炭的方法。积炭分为软炭和硬炭,主要由渣油中的沥青质等稠合芳香环化合物吸附于催化剂表面脱氢缩合形成;渣油性质、催化剂物化性能和工艺条件共同影响积炭形成,低黏度渣油、大孔径催化剂及较高氢分压可以减少催化剂表面积炭量;反应过程中掺杂低黏度高芳香性馏分油可以较好地抑制积炭形成。文章指出通过对固定床渣油加氢催化剂积炭问题的分析,可以达到有效抑制催化剂表面积炭和延长催化剂运转周期的目的。     

5.00 Mt/a渣油加氢装置的工程设计及运行

某炼厂一期工程新建了一套5.00 Mt/a渣油加氢装置,是当前国内已投产规模最大的固定床渣油加氢装置。该装置采用UOP公司渣油加氢工艺包,中石化洛阳工程公司进行工程设计。该装置以减压渣油、直馏重蜡油和焦化蜡油为原料,经过催化加氢反应主要生产催化裂化原料。相比同类装置,该装置在工程设计中首次取消了各反应器催化剂卸料口,节省投资同时减少高压系统的泄漏点。标定及运行结果表明,该装置完全达到预期的设计目标,运行安全平稳,工程设计和生产运行管理均达到国际先进水平。     

沸腾床渣油加氢柴油馏分加氢生产国Ⅵ标准柴油工艺研究

对沸腾床渣油加氢柴油馏分加氢生产国Ⅵ标准柴油进行了加氢工艺试验考察。结果表明,以沸腾床渣油加氢柴油馏分为原料,在反应压力6.5～7.5 MPa、体积空速1.0～1.5 h^-1、平均反应温度350～375℃、氢油体积比400的工艺条件下,精制柴油各项指标（除十六烷值外）可以满足国Ⅵ车用柴油标准。随着沸腾床渣油加氢柴油馏分馏程变重,加氢脱硫难度大幅度升高。建议生产国Ⅵ标准柴油时,控制终馏点不大于340℃,有利于加氢装置在较缓和的操作条件下实现长周期运行。需要加工馏程较重的沸腾床加氢柴油馏分时,建议按一定比例掺炼到现有柴油加氢精制装置或柴油加氢改质装置中,降低加工难度。     

Ω环换热器泄漏分析及返修技术

针对某炼厂煤焦油加氢装置精制产物/精制冷低分油Ω环换热器在运行过程出现的泄漏问题,制定合理的返修方案并对泄漏原因进行分析,最大程度降低设备再次发生泄漏的可能性,为同类换热器泄漏检修提供技术支持。     

渣油中沥青质的存在形态及其加氢转化反应

沥青质是渣油的重要组成部分,是渣油加氢反应过程中的转化难点。文章在叙述沥青质化学结构表征方法的基础上,讨论了沥青质的结构组成及其在渣油中的存在形态,并对渣油加氢转化反应过程中沥青质的转化行为和反应机理进行了论述。     

400万t/a渣油加氢脱硫装置能耗分析及生产运行探讨

加氢装置能耗是各炼油企业的一个重要经济指标,节能降耗是降低企业经营成本的重要途径。对渣油加氢装置开工后能耗特点进行了分析,通过执行加氢渣油热直供料方案,停用加氢渣油空冷全部电机,节省电能;制定加热炉余热回收调整方案,将加热炉效率提高至93.0%;优化换热流程,提升原料油预热温度,降低燃料气消耗;增大排放废氢量,调整循环气量和循环机负荷,降低中压蒸汽用量等,有效地降低了装置能耗,实际能耗比设计能耗降低5%～10%。     

Constrained thermohydraulic optimization of the flow rate distribution in crude preheat trains

Crude preheat trains are heat exchanger networks which heat the crude oil stream in the petroleum distillation using hot product streams and pumparounds. The final heating step is executed in a furnace. The thermal efficiency of this process is strongly dependent on the crude preheat train performance, and, during the refinery operation, the heat load of the exchangers may decrease due to fouling. Associated to the reduction of the thermal effectiveness of the heat exchangers, fouling also causes an increase of the flow resistances along the thermal equipment. A potential approach to mitigate this problem is based on the optimization of the distribution of the flow rates in the crude preheat train for maximizing the final crude temperature. In this context, this paper presents a constrained nonlinear programming formulation for this task. The equality constraints encompass mass, energy and mechanical energy balances and heat exchanger equations for describing the thermal and hydraulic behavior of the system. The performance of the proposed approach is explored using two examples, a simple network and a crude preheat train based on a real Brazilian refinery.     

考虑关键换热器备用的原油预热系统清垢周期优化

原油结垢是原油预热过程面临的一个严峻问题,它使换热器的传热系数降低,影响正常的生产过程。应对原油预热过程的结垢问题最普遍的方法就是对换热器进行周期清洁,并优化清洁周期。许多结垢严重的行业都采用换热器备用的方式来减少因换热器离线造成的热回收减小,但原油预热系统尚未考虑,因而进一步考虑了关键换热器的备用来进行原油预热系统清垢周期优化。首先选取关键换热器,再通过模拟退火算法进行清洁周期优化。应用所提出的方法对简化的原油预热系统进行了清垢周期优化,结果显示,考虑换热器备用时所得到的清垢周期经济效益更好。     

基于智能预测和机理模型的换热网络清洗决策

原油石化装置的换热器常受到结垢影响,导致换热器性能衰退严重,换热网络性能也会随之衰退,同时换热器之间的耦合关系,导致不同换热器的性能衰退对换热网络整体性能变化的影响不同。以往的清洗决策主要是根据单台换热器性能衰退到一定程度来制定的,这会导致换热网络整体可能处在较差的运行状态。因此,本文提出一种基于智能预测和机理模型的换热网络清洗决策方法,基于换热器的运行数据建立智能预测模型,获得换热器性能变化趋势,结合换热网络的性能模拟模型,进一步获得换热网络的性能变化趋势,从而从换热网络整体性能变化的角度来制定清洗方案。研究表明,对收集到的原油换热器运行数据,建立神经网络预测模型,具有较好的预测精度。通过对原油精馏装置换热网络的案例分析,当HE1、HE2和HE5三台换热器同时发生性能衰退时,换热网络年度公用工程能耗费用将增加12.1%。与传统基于单台换热器性能衰退情况制定的清洗方案相比,从换热网络整体性能衰退角度制定的清洗方案,年度额外公用工程费用减少13.1%,损失费用减少14.1%,年度总费用减少13.8%,而清洗次数仅增加3台次。     

Determination of fouling characteristics of various coals under gasification condition

In a coal gasifier and heat exchanger, adhered and deposited fouling inhibits heat transfer making the stable operation of the gasifier difficult. Since heat-transfer performance of the heat exchanger directly affects the output of Integrated Coal Gasification Combined Cycle plants, it is important to understand the effect of fouling on the characteristics of adhesion and deposition on the heat exchanger tube beforehand. But very few studies have been conducted about concerning the relationship between fouling property and adherability, which depend on the reducing condition on the gasifier system.The main purpose of the present investigation is to determine the low temperature ash deposition behavior under coal gasification condition by using drop tube furnace (DTF), in which behavior of coal particle in actual gasification condition can be simulated experimentally. Nine pulverized coal samples which are in the range of bituminous and sub-bituminous are injected into DTF under gasification condition. The ash particles are deposited onto sample collector by impacting and agglomerating actions; deposit samples of ash are collected, quantitative analyses are performed by EDX and weight measurements. Experiment results illustrated that mineral components are generally considered as a dominant parameter to determine behavior of ash deposition at low temperature among various physical and chemical properties of coal. It is also found that the alkaline earth mineral in coal ash such as MgO and CaO compounds leads to fouling deposition under the gasification condition.     

Impact of deposit ageing on thermal fouling: Lumped parameter model

The thermal and hydraulic performance of heat exchangers can be seriously impaired by the formation of fouling deposits on the heat transfer surfaces. The thermal effect of fouling can be complicated when the deposit is subject to ageing, represented here as a change in deposit thermal conductivity (but not thickness) over time. In this article, we revisit the ageing concept for crude oil fouling proposed by Nelson (Refiner Nat Gas Manufacturer. 1934;13:271–276, 292–298), using a numerical model incorporating first order kinetics to generate quantitative comparisons of different ageing rates. Results are reported for lumped parameter systems (which also simulate point measurement methods commonly used in laboratory testing) that demonstrate that ageing can have a substantial influence on the rate of heat transfer and hence on the surface temperature and rate of fouling. Rapid ageing (compared with the rate of deposition) does not pose problems, but slow ageing, or the use of constant heat fluxes in experiments, can lead to modified thermal fouling behavior. It is concluded that deposit ageing dynamics should be considered alongside deposition rate dynamics when interpreting experimental fouling data and when modeling fouling behavior in support of heat exchanger design or operation. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

西部管道综合热处理余热回收工艺研究

通过对西部管道原油输送工艺现状的研究,发现了原油外输温度过高,引发的一系列问题,特别是破坏管道的防腐层和能耗过高,浪费能源等问题,提出了实施进一步的热能回收,即通过增设油-油换热器将出站高温原油热量进行回收,通过计算结果表明能够减少加热炉负荷,节省能源,在短期内就能实现增效的目的。     

加工俄罗斯原油常压装置设计中应注意的问题

哈尔滨石化分公司为适应原油品种的变化 ,在常压装置技术改造中 ,采用防腐措施 ,调整换热流程 ,换热终温比技术改造前提高 40℃ ;采用热管换热器回收热能 ,能耗较技术改造前平均低 12 5kJ/t原油 ;改造后的常压装置能炼制含硫 <0 5% ,含酸 0 5mgKOH/L原油     

加热炉的选型与工艺设计

目前原油管道上输油站内对原油进行加热的方式有直接加热和间接加热两种,直接加热方式是用于加热炉直接加热原油。直接加热为原油在炉内直接加热,方式虽然设备简单,投资较低,但一旦断流或偏流容易因炉管过热而结焦。故此种加热方式现在并不常用,易造成事故。为确保安全,应设置防偏流、断流、结焦的自控保护系统;另外应在露点以上运行,以避免对流管管壁造成低温露点腐蚀。间接加热方式是目前比较常用的,间接加热炉通过加热中间介质来给原油换热,根据中间介质的不同,可以分为热媒炉和分体式相变炉。主要介绍加热炉的选型,效率规定、热负荷计算并结合工程实际说明分体式相变炉在输油站场中的设计重点。     

Determination of Input Parameters for Crude‐Oil Fouling Using an Integrated Non‐Parametric Method

An integrated, non‐parametric model has been proposed based on neural networks and partial derivatives (PaD) to determine the influence of the operating parameters during crude‐oil fouling. The input parameters included surface and bulk temperatures, fluid velocity, colloidal instability index, and surface substrate, whereas the output was the initial fouling rate. The PaD method was used to slightly change an input while the others were kept constant. The input that changed the output most had the highest impact on the objective output, i.e., the initial fouling rate. This method identified the surface temperature as the most dominant parameter. This indicates that crude‐oil fouling dominantly resulted from chemical reactions due to asphaltene instability.     

废塑料与废机油共催化裂解制取燃料油的研究

以废塑料和废机油为原料,共催化裂解制备燃料油,克服了废塑料裂解因传热差,裂解炉中温度极不均匀、结焦的难题,提高了燃料油得率。实验中考察了裂解温度、不同油固比、萃取剂对燃料油得率和组成的影响。在混合废塑料为PE∶PP∶PS=3∶1.2∶1、裂解温度为420℃、油固比为1.5、ZSM-5/50H分子筛为催化剂的条件下,燃料油得率可达到89%以上,汽、柴油比例达83%。采用络合萃取剂精制裂解产物可显著提高燃料油的安定性。