四喷嘴气化炉炉顶二次补汽(气)气化新方式的探讨

针对四喷嘴气化炉工艺烧嘴使用寿命短、拱顶耐火砖寿命短、不适应水冷壁结构等瓶颈问题,探索四喷嘴气化炉炉顶二次补汽(气)气化新方式。结果表明,二次补汽(气)气化新方式在高浓度水煤浆气化和干粉煤气化中具有明显的应用优势:能够消除四喷嘴向上撞击流股,可适应四喷嘴气化炉的水冷壁结构;能够强化氧、煤间的反应,降低烧嘴平面和拱顶温度,延长工艺烧嘴和耐火砖使用寿命;能够充分利用炉顶高温热能强化水解和CO_2还原反应,增加有效气产量和系统产能;可增加炉温及煤粒在炉内停留时间的调控手段,使气化反应更趋向于按人为意愿进行控制。     

煤快速热解获得液态烃和气态烃的研究(Ⅲ)——气体停留时间的考察

用内蒙扎赉诺尔褐煤在气流床反应器中进行快速加氢热解的研究.在6.OMPa、700℃、氢气载气在反应器内的停留时间为7～71s范围内,总生成物产率随停留时间增加而提高,停留时间达42s时,液态轻质芳烃(三苯+三酚)出现最大值达13.5%,比短停留时间的产率增加了1.6倍;71s时,气态和气、液态生成物总产率分别为31.6%和42.1%.随气体停留时间的增加,气态和液态轻质芳烃产率的提高与焦油量的减少和半焦中残留挥发分的降低有密切关系.在快速热解过程中,加氢二次反应不可避免,且对气、液生成物的产率和产物分布有重要影响.载气停留时间是控制二次反应的重要手段.     

裂解与分离(Ⅲ) 第二章 管式裂解炉

上一章的简要内容是裂解制乙烯、丙烯的反应原理和工艺问题。讨论了裂解过程中的化学反应规律,着重分析了生成乙烯的一次反应和乙烯消失和引起结焦结炭的二次反应。为了促进一次反应和抑制二次反应,操作条件要采用高温、短停留时间和低分压。并且对含氢量不同的原料控制不同的裂解深度。为此对裂解炉提出了很高的要求:必须创造裂解所需的高温条件、在极短时间内对裂解物料能供反应吸热所需的大量热量、保证烃在高温区有所要求的短停留时间。本期刊登的是第二章的前半部分,讨论管式裂解炉的操作特性,包括停留时间分布的均匀化、轴向温度分布的可控化、裂解深度和产品分配的可调化、传热的强化以及裂解炉型等问题。下期刊登第二章的后半部分,内容为管式裂解炉结构设计和最佳化、急冷和能量利用等问题。     

瓶级PET固相聚合乙醛变化规律研究

通过对不同瓶级聚对苯二甲酸乙二醇酯(PET)固相聚合生产工艺各阶段乙醛(AA)含量变化规律的分析,研究产品中AA含量随反应停留时间、反应温度、反应气固比及氮气中AA含量的变化规律.结果表明:瓶级PET产品中AA含量随反应停留时间的延长及反应温度的升高而降低,随氮气中AA含量的降低而降低;在工艺条件一定的情况下,瓶级PET中AA含量随基础切片端羧基含量的上升而升高;当气固比大于0.25时,提高气固比对产品中的AA含量没有影响.     

甲醛不锈钢废热锅炉事故统计分析及防止对策

<正> 一、概 述 甲醇氧化制取甲醛的工艺中,离开固定床氧化器的工艺气温度为 640～700℃。在此温度下停留时间过长,将会产生二次反应形成副产物甲酸,对后续设备、管道造成腐蚀,并影响产品质量。在老流程中,采用冷却水间壁急冷,但工艺气余热未被利用。 79年广州溶剂厂采用废热锅炉回收余热蒸汽首获成功后,国内先后有十余甲醛生产     

温度和停留时间对煤热解挥发分二次反应的影响

在两段固定床反应器中考察了温度和停留时间对煤热解挥发分二次反应产物分布的影响. 结果表明,温度和停留时间对二次反应的影响相互关联. 温度≤600℃、停留时间小于2 s时,挥发分基本不发生气相二次反应. 随温度升高和停留时间延长,挥发分二次反应加剧,焦油产率下降,气体产率和积碳产率增加. 温度低于700℃时,焦油主要转化为气体产物,气相二次反应由二次裂解反应控制;高于700℃时,焦油转化为气体和积碳,气相二次反应由裂解反应和结焦反应共同控制. 提高二次反应温度和延长停留时间,热解气中的H2, CH4和CO产率增加,CO2产率减少,焦油中杂原子化合物及其中的酚、甲酚和二甲酚产率降低,大于3环的重质多环芳烃(PAHs)产率增加,H/C和O/C原子比降低,特别是在900℃时,随停留时间延长,H2和重质PAHs产率快速增加.     

共聚PET固相聚合粘度变化规律的研究

利用固相聚合生产装置,研究了共聚PET固相聚合反应温度、停留时间、氮气流量、催化剂含量、基础切片端羧基含量对增粘的影响。结果表明:在一定的工艺条件下,产品粘度随反应温度提高、停留时间的延长及催化剂含量的增大而增大;当气固比大于0.3时,增大氮气流量对增粘速率不再产生影响。     

微通道反应器内合成高纯度碘化钾

利用微通道反应器,研究了氢碘酸、甲酸溶液及氢氧化钾合成碘化钾的反应,考察了反应温度、原料配比、停留时间对碘化钾产率的影响。获得了较优的反应工艺条件,反应温度为85℃、停留时间为30 s、m(氢碘酸)∶m(甲酸)=54%、m(氢氧化钾)∶m(水)=31%。在该优化工艺条件下,碘化钾的产率为97%,产品纯度达到99%。实验结果表明,该方法具有反应时间短、产品收率高、绿色环保等优点。     

克劳斯燃烧炉流场定制

克劳斯燃烧炉是脱硫工艺中重要的设备,克劳斯燃烧炉的结构对炉内气体的流动和反应有显著影响。对扼流圈结构、常规工艺和补酸气工艺下不同花墙结构的燃烧炉进行数值模拟,对比停留时间及混合程度,找出最优的燃烧炉结构。结果表明:花墙结构明显增加了炉内气体的混合程度并延长了停留时间。对于不同花墙结构,孔板延长的双旋花墙结构的克劳斯燃烧炉炉内气体混合效果最好,停留时间相对于扼流圈结构增加了6.32s。补酸气工艺可以降低燃烧炉出口SO_2的质量分数并提高硫单质的产率。通过选取最优的克劳斯燃烧炉结构,对克劳斯燃烧炉进行流场定制,有利于燃烧炉内反应的充分进行。     

绿色涂料助剂CS—12的合成

本文介绍了丁辛醇装置副产物异丁醛的缩合产品2,2,4-三甲基-1,3-戊二醇单异丁酸酯的性质、用途、合成及分离工艺条件。其中采用连续法工艺停留时间短,反应单程收率大于60%,产品纯度98%(wt)以上,是性能优良的绿色涂料助剂。     

流化床稀相段对焦油裂解的影响

为降低煤在热解过程中的焦油产率 ,在一流化床稀相段考察了温度和停留时间对焦油裂解的影响 .结果表明 :焦油转化率随着温度和停留时间的增加而明显提高 ,但其增长幅度却逐渐变小 ,说明继续升高温度和停留时间对降低焦油产率的作用在逐渐减小 .同时温度或停留时间的增加也促进了 H2 ,CO和 CO2 产率的增长 ,对脂肪烃类的影响比较复杂 .在不同温度下 ,气体热值随停留时间的增加均呈下降趋势 .     

热解和气化过程中焦油裂解的研究

介绍了在热解、气化过程中关于焦油裂解的研究,讨论了温度、压力、气氛、停留时间和加热速率对焦油裂解的影响．同时讨论了氧化钙对焦油裂解的影响,并对不同催化剂的催化剂活性进行了比较．     

Design of a Flexible Pilot Plant Reactor for the Steam Cracking Process

A design technique for a pilot plant reactor of single diameter is presented to scale up or down steam cracking coils of different configurations like mono‐tubular, classical, and reversed splits. Using dimensional analysis, two criteria are selected in establishing partial similarity between different scales, the mean residence time, and the axial pressure profile in the reactor, in addition to preserving the flow pattern within the turbulent region. The sensitivity and accuracy of the proposed method is compared to another conceivable alternative that focuses on the lateral gradients. The pilot reactor coil is adapted for any large‐scale reactor by the adjustment of feed flow rate and the effective length exposed to the firebox heat flux. Simulation results for naphtha cracking in a commercial split coil and also the equivalent pilot plant reactors are used for verification and validation of this method.     

Gas flow behavior and residence time distribution in a FCC disengager vessel with different coupling configurations between two-stage separators

To deeply understand the effect of coupled configuration between two-stage separators on the gas flow behavior in fluid catalytic cracking disengager space, the gas flow field and residence time distribution in a bench-scale disengager is numerically studied on the platform of the commercial computational fluid dynamics software package, Fluent 6.1. Two conventionally used coupling configurations in refineries and a newly-designed configuration are investigated. The Reynolds stress model is applied to simulate the gas flow field and the results agree well with the experimental values measured by a smart five-hole probe. Coupled with the Reynolds stress model, a scalar transport equation is used to obtain the gas residence time distribution. It is shown that the coupling configuration between the primary and secondary cyclones has an apparent effect on the gas flow behavior. The newly-designed configuration is better to quickly discharge the gas into the secondary cyclone inlet with a maximum residence time of 0.38 s, compared to 7.72 s and 2.79 s for the two conventional configurations. The simulation results indicated that the appropriate modification of the coupling configuration can help to improve the gas flow. The knowledge of the gas flow field also help to understand the coke formation process in the disengager space.     

催化裂化过程中的热裂化与催化裂化

研究了催化裂化过程中热裂化反应和催化裂化反应的特点和影响因素 .结果表明反应温度、剂油比和反应时间能显著地影响热裂化反应和催化裂化反应 .采用适当的催化剂和短反应时间能抑制催化裂化过程中不利的热裂化反应 ,达到调整产品分布和产品组成的目的 .     

Influence of alkali on restrained shrinkage behavior of cement-based materials

Experiments have been conducted to study effects of high alkalinity on restrained shrinkage behavior and cracking sensitivity of cement-based materials at early ages. The restrained shrinkage test has been conducted with an ellipse ring setup and the initial cracking time was monitored with a continuous conductive strip. Alkali content and alkali type as well as the shrinkage-hydration relationship have been studied. The experimental results have shown that the cracking sensitivity of a cement-based material is increased with an increase in alkali content. The influence of the excess alkali on the cracking sensitivity is more obvious for cement paste with a low water-to-cement ratio (w/c) than that with a high w/c. The hydration processes and microstructure development of cement paste have been investigated using heat of hydration measurement and electrical resistivity measurement. The superimposed resistivity curve and heat evolution curve provide more comprehensive understanding on factors influencing shrinkage development.     

基于迁移学习的裂解炉产率建模

乙烯裂解炉通常以石油分馏产品为原料,并在高温条件下使长链分子的烃断裂成各种短链的气态烃和少量液态烃,从而获得乙烯、丙烯等烯烃及其他产品.建立这些主要产品的产率模型对裂解炉的先进控制、操作优化等任务在理论和实际上都具有重要意义.尽管在不同裂解原料、不同炉型的裂解炉状况下产品收率均存在差异,但由于裂解炉运行具有半连续性、周期性特征,裂解温度、停留时间及烃分压等因素对裂解产率的影响具有共性,因此为减小建模过程中典型样本采集等成本,有效利用历史数据提高建模精度,有效利用这些不同运行过程中存在的相似性,辅以迁移学习算法实现不同工况下裂解产率的快速建模.相比较以前的研究,此建模方法在少量新数据的情况下充分挖掘了历史数据中包含的信息.最后,以某乙烯厂为研究实例进行裂解产率建模,结果显示能够获得较好的产率预测精度,验证了该建模方法的有效性.     

Study of cracking FCC naphtha in a secondary riser of the FCC unit for maximum propylene production

To satisfy the increasing propylene demand, reprocessing FCC naphtha in a secondary riser of the FCC unit was investigated. To this aim, a full range FCC naphtha was cracked over a mixture of two kinds of commercial equilibrium FCC catalysts, which contained 95 t.% Y zeolite-based catalyst and 5 wt.% ZSM-5 zeolite-based additive. The effects of operating parameters such as reaction temperature (temperature of the riser outlet), catalyst-to-oil ratio and residence time on FCC naphtha cracking were studied in a continuous pilot plant. This work demonstrates that FCC naphtha requires high operating severities to crack, and approximately 12–19 wt.% FCC naphtha can be transformed into propylene. The conversion and yield of propylene showed a rapid increase with increasing reaction temperature, and the increase of catalyst-to-oil ratio also enhanced FCC naphtha cracking, even at high reaction temperature. However, at high catalyst-to-oil reactions, hydrogen-transfer reactions constrain further increases in light olefin yields. At these high operating severities, shortening residence time is an appropriate way to obtain high yields of propylene combined with (i) lower yields of dry gas and (ii) a lower apparent hydrogen-transfer coefficient.     

热载气体直接加热石油烃裂解研究进展?I. 裂解装置和技术

概述了以气体为热载体的石油烃直接加热裂解技术及其应用;介绍了热载气体直接加热石油烃裂解的装置组成、运行条件、产物产率、技术改进及发展状况,分析了裂解反应机理和反应动力学;指出热载气体直接加热裂解具有原料适用性广、产物分布灵活、热效率较高和受结焦影响小等优点,但同时也有裂解装置结构较复杂、缺乏系统性研究数据等不足. 最后对热载气体直接加热石油烃裂解的研究进行了展望,指出以氢氧燃烧产生的过热水蒸汽作为热载气体的直接加热裂解技术,在提高换热效率、降低碳排放、扩大原料范围和耦合制取合成气等方面有很大优势,发展前景广阔.