加氢固定床反应器催化剂密相装填与安全控制

随着炼油技术的进步,催化反应器大型化、标准化、强度化的发展趋势,固定床固体催化剂的装填技术及装填设备越来越成为反应器热效率、压力降的重要影响因素。催化剂装填质量的好坏,不仅影响催化剂的填装量,而且直接影响到装置的处理量,致使技术经济指标下降。更重要的是,如果催化剂在装填过程中因技术短板或操作导致疏密不均,很容易造成物料短路或床层下降,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等现象,严重影响了产品质量与催化剂寿命。因此催化剂装填的核心就是实现催化剂的均匀装填,提高装填密度和装填效率。文章以华北某加氢固定床反应器催化剂装填为背景,简述了普通装填方法与现有密相装填的设备和方法,并将两种装填方法的优缺点进行了分析论述。最后,针对装填操作安全以及装填效果保障的行为控制进行了叙述。     

严格执行各项措施,保证催化剂装填质量

对于加氢裂化装置开工过程来说,催化剂装填是很重要的一个环节,装填质量是后续开工平稳运行的重要保障。催化剂料面必须平整,催化剂均匀散开,避免任何局部堆积超过100mm。此外,还应特别注意反应器中热电偶套管和器壁周围催化剂分布,以保证均匀、良好的装填,以防止开工后产生沟流现象。     

脉冲料栓式密相气力输送系统研究

介绍了脉冲料栓式密相气力输送系统输送装置和输送原理，分析了料栓在输送过程中的流动行为以及栓压与栓长栓速之间的关系，分析了料气速度比及压损公式，为设计和使用脉冲料栓式密相气力输送系统提供参考。     

槽车密相补气式气力输送系统的设计

介绍密相气力输送的基本原理和技术 ,一种采用密相脉冲补气式气力输送PET切片的槽车贮罐运输、中转、卸料、仓贮的系统的建立 ,节约投资、降低能耗 ,提高了经济效益     

上出料系统粉煤密相气力输送特性及其与下出料系统的比较

考察了气体进入方式和输送压力对上出料发料罐系统粉煤密相气力输送特性的影响,并比较了上出料和下出料发料罐系统的煤粉输送量、固气比和稳定性差异。结果表明,在上出料发料罐系统中,随锥部气增加,煤粉输送量和固气比呈先增加后减小趋势;随底部气和调节气增加,煤粉输送量和固气比呈减小趋势;随输送压力增加,煤粉输送量和固气比先明显增加后增加趋势减弱。与上出料发料罐系统相比,相同输送差压下,下出料发料罐系统具有较高的输送量和固气比,但二者均具有良好的输送稳定性。     

固定床渣油加氢过程催化剂级配优化研究及工业应用

采用SHIFT—G反向催化剂级配技术对固定床渣油加氢催化剂级配进行优化,中型试验和工业应用结果表明,优化装填后的催化剂级配体系消除了影响装置操作周期的不利因素,合理地分配了反应负荷,有效地改善了加氢产品性质,延长了工业装置运转周期,提高了经济效益。     

脉冲式密相气力输送水平管中的料栓行为

探讨了聚丙烯颗粒在脉冲式密相气力输送水平管中的料栓行为. 结果表明在一定操作气速下,料栓的长短变化有规律,料栓的运动速度随其长度而变;栓长为1 m左右的聚丙烯颗粒由栓状流向沙丘流型转变的料气速度之比为0.7~0.8,出现在操作气速5 m/s左右;单个料栓的压力梯度与其长度有关,沿单个料栓的压力梯度和截面固含量随气速而变;料栓压降与操作气速无关.     

多晶硅硅粉密相气力输送系统选择与维护

本文阐述了多晶硅生产装置中硅粉输送装置的原理、输送方式的选择计算以及密相气力输送的工作方式、控制系统、故障判断方法。     

流化床系统物料密相循环特性的研究

通过对并列流化床间固体颗粒密相循环的实验研究，分析了流化工况对颗粒物料循环量的影响，提出了并列流化床系统用辅助气流控制颗粒循环量的临界操作条件，对给定系统最大颗粒循环量的计算作了说明。     

煤粉加压密相输送系统研究现状及发展方向

为优化干法煤气化的煤粉密相输送系统,介绍了加压密相气力输送技术和基于散体力学理论的固体输送泵技术2种典型的煤粉加压密相输送技术,分析了2种典型技术的技术特征及气体加压密相输送技术中的关键问题,提出了干粉加压固体输送泵的发展方向。固体输送泵技术是未来煤粉密相输送的发展趋势。未来应加强国内散体力学的相关理论、数值及试验研究,包括散体静力学,散体动力学的相关基础研究;研究煤种、水分、粒径等参数与摩擦系数之间的函数关系,确定Stamet Pump及PWR针对国内煤种所能提供的最大输出压力;确定典型的Stamep Pump、PWR的XTL技术工业放大的瓶颈所在,提出切实可行的放大解决方案。     

Numerical simulation of fixed bed reactor for oxidative coupling of methane over monolithic catalyst

A three-dimensional geometric modelwas set up for the oxidative coupling of methane (OCM) fixed bed reactor loaded with Na₃PO₄-Mn/SiO₂/cordierite monolithic catalyst, and an improved Stansch kinetic model was established to calculate the OCMreactions using the computational fluid dynamicsmethod and Fluent software. The simulation conditions were completely the same with the experimental conditions that the volume velocity of the reactant is 80 ml·min^-1 under standard state, the CH₄/O₂ ratio is 3 and the temperature and pressure is 800 ℃ and 1 atm, respectively. The contour of the characteristic parameters in the catalyst bed was analyzed, such as the species mass fractions, temperature, the heat flux on side wall surface, pressure, fluid density and velocity. The results showed that the calculated valuesmatchedwell with the experimental values on the conversion of CH₄ and the selectivity of products (C₂H₆, C₂H₄, CO,CO₂ and H₂) in the reactor outlet with an error range of ±4%. The mass fractions of CH₄ and O₂ decreased from 0.600 and 0.400 at the catalyst bed inlet to 0.445 and 0.120 at the outlet, where the mass fractions of C₂H₆, C₂H₄, CO and CO₂ were 0.0245, 0.0460, 0.0537 and 0.116, respectively. Due to the existence of laminar boundary layer, the mass fraction contours of each species bent upwards in the vicinity of the boundary layer. The volume of OCM reaction was changing with the proceeding of reaction, and the total moles of products were greater than reactants. The flow field in the catalyst bed maintained constant temperature and pressure. The fluid density decreased gradually from 2.28 kg·m^-3 at the inlet of the catalyst bed to 2.18 kg·m^-3 at the outlet of the catalyst bed, while the average velocity magnitude increased from 0.108 m·s^-1 to 0.120 m·s^-1.     

催化精馏塔中催化剂填装技术的研究述评

按气、液、固三相间不同的接触方式,将催化精馏技术中的瓶颈问题之一的催化剂填装技术分为两大类作了系统的介绍,即气、液、固三相混合接触式和液、固与气、液分别接触式。阐明了各类填装方式的优缺点及其可能的应用领域,指出了催化剂填装技术未来多元化的发展趋势。     

Bed structure and its impact on liquid distribution in a trickle bed reactor

Trickle bed reactors, which has been a workhorse for the process and refining industry for many decades, are progressively being challenged to provide solutions to deep processing of feedstocks. It is known that the structure of the packed bed which is formed with a certain arrangement of catalyst particles in the three-dimensional space within the reactor modulates in an unknown fashion the flow of fluids in the trickle bed, and in turn affects the conversion and selectivity in the trickle bed. Under deep processing conditions, the impact of the bed structure in modulating the overall reactor performance in a trickle bed is not as yet established. The question begets three sequential studies: estimating and quantifying the bed structure, measuring the liquid distribution, and estimating transport parameters (that are dependent on the bed structure and liquid distribution) so that the overall performance metrics as a reactor may be quantified. This contribution relates to the second of these questions, the first being already addressed to some extent by our earlier work. The current investigation aims at quantifying the effect of structure of the packed bed on hydrodynamics of the reactor. The impact of various packing techniques is discussed along with the development of correlations for two-phase pressure drop and dynamic liquid holdup. Liquid distribution is studied in depth for various operating parameters such as gas and liquid superficial velocities and column aspect ratio for uniform and non-uniform packing methods. The packing devices consist of various inserts attached to a hopper which can generate packing structures having void fraction in the range of 37.2%–46.4%. The maldistribution factor and flow maps for various aspect ratio of column suggest that maldistribution rises along with the increased channeling effect along the height of the column. Uniformly packed bed were measurably less prone to maldistribution along the length than the non-uniformly packed beds.     

UASB反应器处理玉米淀粉废水稳定性研究

分析了UASB反应器稳定运行的影响因素,试验结果表明:通过对进水量的主动调整可以解决因进水浓度波动带来的影响,反应器COD容积负荷在10 kg/(m3·d)左右时,上升流速0.7 m/h是最佳值,能够承受2 kg/(m3·d)的负荷冲击,处理效率仍能保持在75%以上.     

Simulation of a spouted bed reactor for solid catalyst alkylation

A process simulator was developed to afford a better understanding of the performance of a butene-isobutane alkylation plant that uses a three-phase spouted bed reactor and a super acid solid catalyst. The mass and energy balances were numerically solved using lump of reactions and kinetic expressions previously developed. The results indicate the strong influence of the gas linear velocity and temperature in the riser and downcomer behavior that affects the activity, selectivity, and stability of the catalytic systems that cannot be predicted otherwise. The optimal operating conditions were determined for a particular catalyst and set of costs. The impacts of the recycling alkylate and isobutane to the reactor as well as the presence of hydrogen to control the coke formation are analyzed.     

脱硝催化剂在金属基体表面的负载方法与工艺研究进展

基于负载脱硝催化剂的换热管烟气脱硝与余热回收一体化技术,具有良好的发展前景,但在实际应用中缺乏在铁基体表面高效、稳定负载脱硝催化剂的方法及工艺。本文综述了国内外有关脱硝催化剂在金属基体表面的各种负载方法及其特性,重点探讨了浸渍法、粉末涂覆法、离子交换法、脉冲激光沉淀法、辊压法、浆料喷涂法等直接负载方法,以及溶胶-凝胶法、高温氧化法、等离子喷涂法、超音速火焰喷涂法、电弧喷涂法、电泳沉积法等间接负载方法的中间过渡层制备方法。同时,对直接负载方法及间接负载方法的优缺点分别进行了对比分析,以期为烟气脱硝与余热回收一体化技术的应用提供借鉴,并指出等离子喷涂-浸渍法是脱硝催化剂在铁基体表面负载的可行方法之一。     

两段式固定床反应器上生物油水相部分的重整制氢反应

比较了不使用催化剂和使用商业催化剂Z204时两段式反应器生物油水相部分的重整制氢反应的特点,研究了反应温度和生物油水相部分蒸馏温度对生物油水相部分重整制氢反应的影响,考察了催化剂的寿命和蒸馏残渣的特性。实验结果表明,在两段式反应器上使用Z204催化剂时,H₂收率最高可达47％,明显高于不加催化剂时的H₂收率;在蒸馏温度为200 ℃、反应温度为750 ℃的条件下,反应在约4 h的反应时间内H₂收率基本维持在35%左右。对蒸馏残渣的特性考察表明生物油水相部分蒸馏残渣的变形温度要远高于反应时的温度。     

加氢催化剂膨胀床器外预硫化工艺研究

采用膨胀床对加氢催化剂进行了器外预硫化研究。研究了预硫化工艺条件对加氢催化剂硫化度α的影响。结果表明,α随着硫化温度的增加而增加,但是,烯烃加氢活性在370 ℃时出现最大值。吡啶-TPD表征结果证明,硫化温度高,催化剂的酸性强,而酸性影响催化剂加氢活性。对膨胀床和器内CS₂硫化两种方法预硫化的催化剂进行烯烃加氢活性对比,发现膨胀床器外预硫化催化剂α值高、加氢活性好。器外预硫化的适宜工艺条件:硫化时间10 t₀,硫化温度370 ℃,床层膨胀率12％。硫化和还原同时进行的催化剂活性高。     

Experimental studies and modeling of a fixed bed reactor for Fischer-Tropsch synthesis using biosyngas

The aim of this work was to study the Fischer-Tropsch (FT) synthesis of a model biosyngas (33% H₂, 17% CO and 50% N₂) in a single tube fixed-bed FT reactor. The FT reactor consisted of a shell and tube with high-pressure boiling water circulating throughout the shell. A spherical unpromoted cobalt catalyst was used with the following reaction conditions: a wall temperature of 473 K, a pressure of 20 bars and a gas hour space velocity (GHSV) of 37 to 180 NmL.g_cat^− 1.h^− 1. The performance of the FT reactor was also validated by developing a 2D pseudo-homogeneous model that includes transport equations and reaction rate equations. Good agreement between the model predictions and experimental results were obtained. This developed model was extended to predict and quantify the influence of the FT kinetics as well as determine the influence of the tube diameter and the wall temperature. The predicted behaviors for CO and H₂ conversion, productivity of hydrocarbons (mainly CH₄ and C₅₊) and fluid temperature along the axis of the reactor have been analyzed.