重整装置预加氢单元压降增大原因分析及对策

九江分公司催化重整装置由于用氢流程的安排、预加氢增压机能力、原料杂质、系统的含铁物质等原因．预加氢反应系统存在压降上升过快现象,影响了装置长周期稳定运行。由重整原料油氯含量相对较高引起的铵盐沉积．预加氢反应器入口处的低压操作（1．70～1．75MPa）和气油体积比的低限操作（100）加速了催化剂的生焦积炭,这些因素不仅影响装置的处理量,而且引起重整系统压力上升,致使重整反应深度降低、产氢减少．成为限制重整装置稳定运行的瓶颈。通过对反应器顶部催化剂床层的“撇头”、氮气吹扫处理,再对空冷器E106和水冷器E107进行热水冲洗,并在反应器顶部装填级配剂后,预加氢反应系统总压降由0．48MPa降至0．2MPa．     

加氢处理催化剂级配技术及应用进展

渣油加氢处理催化剂需要具备加氢脱金属、加氢脱硫、加氢脱氮、加氢脱残炭及部分加氢转化等功能,但目前尚未开发出集这些功能于一体的单一品种的催化剂。因此,需要根据原料性质、操作条件和对产品质量的要求,将不同功能的加氢处理催化剂级配使用。在渣油加氢反应器中,催化剂级配装填的顺序为保护剂/HDM/HDS/HDN催化剂,沿反应物流方向,催化剂尺寸、孔径在反应器内由上到下逐渐减小,而催化剂活性则逐渐增加,整个催化剂床层中催化剂的物理和化学性质要保持平稳过渡。但这种级配装填方法不适用于高含氮渣油,于是又提出了反向催化剂级配装填技术,其特点是沿物流方向催化剂活性逐渐降低,改变了HDS、HDN催化剂床层的级配,并在床层之间增设一个过渡催化剂床层,使每个催化剂床层的温升更加平稳。催化剂的级配装填最初是为了解决渣油加氢处理存在的问题,但此后其应用范围几乎扩大到各种加氢处理工艺,从而极大地改善了各种加氢处理工艺的综合技术经济指标。     

汽油脱硫醇装置固定床床层压降增大的原因及对策

长庆石化汽油精制装置,采用的是无碱Ⅱ型脱硫醇工艺,现设置3台汽油脱硫醇固定床反应器,固定床反应器床层压降增大给装置的正常运转带来困难,影响装置的加工量,严重时会造成精制汽油硫醇硫含量超标,博士试验不合格。导致床层压降增大的原因主要有:汽油携带碱液进入固定床反应器,盐类和杂质在催化剂表面的累积,以及加工量波动对床层的扰动。总结出采用碱液洗涤降低床层压降的方法:通过对碱液和固定床反应器的强化控制,以及平稳汽油的进料流量,使床层压降降低,产品质量合格。提出了推迟固定床床层压降增大、延长使用时间的3条建议:更换一个容积更大的(为80.8m3)预碱洗沉降罐;在纤维膜预碱洗罐出口增加2台液-液聚结分离器,以脱除汽油中携带的碱液和水分,减少对后路反应器的影响;将3台固定床反应器的压力显示接入DCS系统,进行实时监控。     

高温鼓泡流化床的流化行为

床层温度在20－1000℃范围内,以4种粒径的煤灰为实验物料,研究了不同表观气速下最小流化速度,床层平均空隙率,压力波动标准偏差和主频的变化规律,最小流化速度随床层温度升高而减小;相同床温下,平均空隙率随表观气速升高而增大,不同床温下,压力波动偏差随流化数增加而增大。相同流化数时,B类颗粒的压力波动标准偏差受床层温度变化影响较小,而D类粒子随床层温度升高压力波动标准偏差减小,胡着流化数增加,压力波动主频减小。     

增压富氧燃烧流化床炉内传热特性

建立了增压富氧燃烧流化床锅炉炉内传热模型.通过模型计算,分析了颗粒粒径、空隙率、床层温度及系统压力等因素对炉内传热特性的影响.结果表明：随着颗粒粒径增大,传热系数减小;随着空隙率增大,传热系数减小;随着温度升高,传热系数增大;随着压力升高,传热系数增大,但增加的幅度明显变小,说明当压力升高到一定程度时,继续升高压力对传热没有太大影响.     

加氢精制反应系统压降升高的原因分析及对策

广州分公司加氢精制（-）B装置在进行焦化汽油加氢精制过程中存在催化剂床层压降升高过快的问题。造成这一问题的主要原因，是原料油性质在存储过程中发生变化、二烯烃发生聚合。通过对相关设备管线的清洗吹扫．以及采取对原料油流程的优化等手段，使催化剂床层压降稳定在0．1MPa以下。达到了理想的操作效果。     

焦化汽(柴)油加氢精制装置生产国Ⅴ柴油的实践与优化

随着车用柴油的排放标准日益严格,炼油厂面临着柴油质量升级问题,主要指标是降低硫含量(≤10%)、提高十六烷值(≥49%)、降低稠环芳烃含量(≤11%)。惠州炼化2.0Mt/a焦化汽(柴)油加氢精制装置生产的精制柴油占全部柴油产量的40%左右,其硫含量偏高(40μg/g左右),改用柴油深度加氢脱硫催化剂FHUDS-6,以生产国Ⅴ标准柴油。对使用该催化剂的满负荷标定数据进行分析。加氢精制反应器第一、二床层装填再生后的精制剂FH-40C,第三床层装填催化剂FHUDS-6。装置标定结果表明,FHUDS-6催化剂具有良好的加氢脱硫活性和稳定性,在氢分压7.6MPa、氢油体积比590、加氢保护反应器反应床层平均温度332.7℃、加氢精制反应器反应床层平均温度365℃、加氢保护反应器空速1.746h-1、加氢精制反应器空速1.931h-1的条件下,柴油中硫的质量分数为5.2μg/g,十六烷值为54.8,产品质量满足国Ⅴ柴油排放标准要求。     

固体催化剂装填技术及设备进展

随着催化反应器的大型化及科技水平的发展,固体催化剂的装填技术和设备越来越成为催化剂工程化开发的重要内容。催化剂装填质量的好坏,直接影响到装置的技术经济指标。更重要的是,如果催化剂装填疏密不均,很容易造成物料"短路"或床层下陷,从而导致反应器内物料和温度分布不均匀,物料与催化剂接触时间不均匀,反应器压力降不均匀,影响产品质量和催化剂寿命。催化剂装填技术的核心,就是要在装填过程中实现催化剂的均匀装填,提高装填密度和装填效率。目前,工业上大多数固体催化剂的装填已实现了由人工到机械的转化,甚至实现了自动化,而且许多工业催化剂实现了密相装填。国外许多公司都开发了专有的密相装填技术,国内在催化剂密相装填设备和技术开发上也取得了可喜的进展。不过,催化剂装填的许多科学和技术问题仍有待解决,如催化剂装填的均匀化和高密度化仍需提高,催化剂装填过程中的颗粒破损和压力降增大问题还没有得到很好解决等。     

双层滤料过滤床的压降特性研究

介绍了双层滤料床的工作原理及其高过滤效率和低压降的过滤特性,试验测试了双层滤料过滤床的各层压降,分析了床层总压降、布风器、沙层和膨胀珍珠岩层的压降特性。结果表明,沙层压降占床层总压降的75%~90%,膨胀珍珠岩层压降占5%~22%。压降特性证明了沙层为表面过滤,膨胀珍珠岩层为深床过滤,这是双层滤料过滤床过滤效率高达99.99%,床层容尘量达到单层沙床10倍的原因所在。     

C6组分加氢系统压降升高原因及改进措施

中国石化上海分公司苯抽提装置系由1974年投产的重整—抽提—精馏装置改造而来,因原料中含有烯烃,高温下容易在加热炉炉管及反应器上部的催化剂床层处生焦,造成C6组分加氢系统压降升高,导致装置停工。为此,采取多项改进措施：增加一台热载体换热器,以替代加热炉,避免局部高温,减缓生焦速率;对装置实施爆破吹扫,清除固体颗粒;使用活性更高、选择性饱和烯烃的能力更强的新型催化剂;改装置进料为上游连续重整装置直接进料,避免了C6组分中二烯烃长时间储存后生成低聚物并转化为高聚物生焦,导致压降升高的可能;同时,于2008年更换一台压缩机,增强装置运行的稳定性。措施实施后,加氢系统压降一直稳定在0.7MPa,实现了装置长周期运行。     

CFD simulation and experimental study for two-phase flow through the trickle bed reactors, sock and dense loaded by trilobe catalysts

In this study single and two phase flow through the trickle bed reactor loaded with a two different loading manner, sock and dense, have been investigated numerically and experimentally. The CT-scan imaging and an image processing code have been used for investigation of radial porosity distribution of trilobe catalyst in sock and dense loading procedure in trickle bed reactors and two different correlations have been proposed. These correlations were used in a single and two phase CFD code for prediction of pressure drop of gas flow in dry and prewet trilobe catalyst packed bed and also pressure drop and dynamic liquid holdup for two phase flow. In addition, these variables were studied experimentally with a laboratory scale trickle bed reactor. The results of CFD simulations show a very good agreement with experimental data.     

Porous copper fiber sintered felts with surface microchannels for methanol steam reforming microreactor for hydrogen production

In this study, a laser micro-milling technique was introduced into the fabrication process of surface microchannels with different geometries and dimensions on the porous copper fiber sintered felts (PCFSFs). The PCFSFs with surface microchannels as catalyst supports were then used to construct a new type of laminated methanol steam reforming microreactor for hydrogen production. The microstructure morphology, pressure drop, velocity and permeability of PCFSF with surface microchannels were studied. The effect of surface microchannel shape (rectangular, stepped, and polyline) and catalyst loading amount on the reaction performance of methanol steam reforming microreactor for hydrogen production was further investigated. Our results show that the PCFSF with rectangular microchannels demonstrated a lower pressure drop, higher average velocity and higher permeability compared to the stepped and polyline microchannel. Furthermore, the PCFSF with rectangular microchannels also exhibited the highest methanol conversion and H₂ flow rate. The best reaction performance of methanol steam reforming microreactor for hydrogen production was obtained using PCFSF with rectangular microchannels when 0.5 g catalyst was loaded.     

Experimental study on 75 kWth downdraft (biomass) gasifier system

Experimental study on 75 kW_th, downdraft (biomass) gasifier system has been carried out to obtain temperature profile, gas composition, calorific value and trends for pressure drop across the porous gasifier bed, cooling–cleaning train and across the system as a whole in both firing as well as non-firing mode. Some issues related to re-fabrication of damaged components/parts have been discussed in order to avoid any kind of leakage. In firing mode, the pressure drop across the porous bed, cooling–cleaning train, bed temperature profile, gas composition and gas calorific value are found to be sensitive to the gas flow rate. The rise in the bed temperature due to chemical reactions strongly influences the pressure drop through the porous gasifier bed. In non-firing mode, the extinguished gasifier bed arrangement (progressively decreasing particle size distribution) gives much higher resistance to flow as compared to a freshly charged gasifier bed (uniformly distributed particle size). The influence of ash deposition in fired-gasifier bed and tar deposition in sand filters is also examined on the pressure drop through them. The experimental data generated in this article may be useful for validation of any simulation codes for gasifiers and the pressure drop characteristics may be useful towards the coupling of a gasifier to the gas engine for motive power generation or decentralized electrification applications.     

Comparison of conventional and spherical reactor for the industrial auto-thermal reforming of methane to maximize synthesis gas and minimize CO2

Auto-thermal reforming (ATR), a combination of exothermic partial oxidation and endothermic steam reforming of methane, is an important process to produce syngas for petrochemical industries. In a commercial ATR unit, tubular fixed bed reactors are typically used. Pressure drop across the tube, high manufacturing costs, and low production capacity are some disadvantages of these reactors. The main propose of this study is to offer an optimized radial flow, spherical packed bed reactor as a promising alternative for overcoming the drawbacks of conventional tubular reactors. In the current research, a one dimensional pseudo-homogeneous model based on mass, energy, and momentum balances is applied to simulate the performance of packed-bed reactors for the production of syngas in both tubular and spherical reactors. In the optimization section, the proposed work explores optimal values of various decision variables that simultaneously maximize outlet molar flow rate of H₂, CO and minimize molar flow rate of CO₂ from novel spherical reactor. The multi-objective model is transformed to a single objective optimization problem by weighted sum method and the single optimum point is found by using genetic algorithm. The optimization results show that the pressure drop in the spherical reactor is negligible in comparison to that of the conventional tubular reactor. Therefore, it is inferred that the spherical reactor can operate with much higher feed flow rate, more catalyst loading, and smaller catalyst particles.     

标准催化剂公司加氢催化剂在惠州炼化高压加氢裂化装置的应用

中海油惠州炼化高压加氢裂化装置处理能力为4000kt/a,采用先进的壳牌专利工艺技术,是目前国内单套处理能力最大的加氢裂化装置,加工原料主要是常减压减二、减三线蜡油和焦化蜡油。该装置选用标准催化剂公司开发的保护剂Opti Trap[Medellion]、Opti Trap[Macro Ring]、Opti Trap[Ring]、Opti Trap[Filter Lobe]、Max Trap[Ni,V]VGO、加氢精制催化剂DN-3551、深度脱氮催化剂Z-503和加氢裂化催化剂Z-3723。从催化剂床层压降、反应温度(催化剂活性)、催化剂选择性、产品收率和产品性质等方面分析催化剂使用性能,结果表明:保护剂较强的容垢能力和级配装填技术,为主催化剂充分发挥性能提供了条件;加氢精制催化剂DN-3551以及深度脱氮催化剂Z-503具有较强的脱硫、脱氮和芳烃饱和能力;加氢裂化催化剂Z-3723具有较高的裂化活性和选择性。     

内置过滤元件流化床的阻力特性及结构优化

对三维流化床颗粒层过滤器的阻力特性进行了研究。并对过滤元件的结构进行了优化。研究表明．流化床颗粒层过滤器的系统阻力主要决定于过滤元件的阻力,优化过滤元件应该是系统优化的主要方向;优化后的颗粒层过滤器能够有效地减少系统的阻力达到23％以上;在权衡过滤效率和床层压降时,有一个恰当的操作气速和静止床层高度。     

Optimization of a fluidized bed reactor for methane decomposition over Fe/Al2O3 catalysts: Activity and regeneration studies

Catalytic methane decomposition was investigated over 40 wt% Fe/Al₂O₃ catalyst in fluidized bed reactor (FLBR). After optimization of FLBR conditions in terms of catalyst bulk density, particle size, minimum fluidization velocity, and the catalyst bed height, the catalyst activity and stability tests were conducted by comparison with a fixed bed reactor (FBR). Although a similar stable methane conversion was obtained over both reactors, the pressure drop during 35 min operation of FBR was 9 times higher than that of FLBR, which indicated the possibility of continuous operation of methane decomposition process over FLBR. Further, the influence of the space velocity, feed dilution and regeneration on catalysts reactivity was studied in FLBR to conclude that a reaction condition of 12 L/g_cat∙h, feed of 20%H₂–80%CH₄ and CO₂-regeneration of deactivated catalysts may be favourable for operating methane decomposition in FLBR continually and effectively to provide stable hydrogen.