多晶硅生产技术发展方向探讨

还原高频电源技术、硅烷流化床法和气液沉积法,可与改良西门子法工艺技术有机结合生产多晶硅,对解决目前国内多晶硅所面临的生产成本高、产品质量低下等问题具有非常重要的意义。本文总结了改良西门子法、硅烷流化床法和气液沉积法生产多晶硅的工艺技术,分析了各自的优缺点和发展方向。指出了目前的改良西门子法核心设备的改进方向和应用还原高频电源技术、硅烷流化床技术需在加热方式上做进一步开发研究,气液沉积法可与现有的多种工艺技术相结合形成多种工艺路线,其中二氧化硅经碳热氯化法制备四氯化硅后,与氢气还原四氯化硅法相结合制备多晶硅,是值得研究开发的一种新工艺路线。该工艺路线不仅工艺流程大大缩减,而且四氯化硅的提纯比其他氯硅烷更容易,生产的多晶硅产品质量更高、成本更低。     

多晶硅生产技术发展方向探讨

讨论了国内外在多晶硅生产方面的主要技术——改良西门子法工艺,针对硅烷流化床法和气液沉积法做了技术性分析,为我国多晶硅在硅烷流化床法和气液沉积法方面的发展提供一些建议。开发和利用这些技术,对解决目前国内面临的多晶硅生产成本高居不下、质量不高的问题,提高我国多晶硅在国际上的竞争力具有重要意义。     

多晶硅生产方法探讨及展望

多晶硅是单质硅的一种形态。熔融的单质硅在过冷条件下凝固时,硅原子以金刚石晶格形态排列成许多晶核,如果这些晶核长成晶面取向不同的晶粒,则这些晶粒结合起来,就结晶成多晶硅。目前主要生产方法有改良西门子法、硅烷法、流化床法。多晶硅产品的主要用途有二种:一种是用于制备太阳能电池;另一种是用于集成电路。     

硅粉加工粉尘爆炸危险性与预防措施

阐述国内多晶硅与有机硅产业中硅粉加工过程中出现的粉尘爆炸的危险性,从硅粉在粉碎、输送、分离、除尘等生产过程,论述了硅粉加工生产中存在较大粉尘爆炸危险因素,从厂房设计、工艺设计、安全技术管理等方面进行分析,指出了硅粉加工过程中预防发生粉尘爆炸的方法。     

太阳能级多晶硅生产技术研究现状及展望

论述了目前太阳能级多晶硅的主要生产技术研究现状,并对一些具有代表性的新工艺进行介绍.太阳能级多晶硅的生产方法主要包括改良西门子法、硅烷法、流化床法、冶金法及锌还原法.指出硅烷法和流化床法是未来多晶硅生产技术发展的趋势和方向,冶金法和锌还原法的工艺尚不够成熟,但具有潜力.     

SiHCl_3流化床制备粒状多晶硅研究进展

综述了近年来关于三氯氢硅(Si HCl3)流化床制备颗粒状多晶硅工艺技术研究状况,详细介绍了国内外关于颗粒状多晶硅制备流化床设备的设计思路及制备情况,并讨论了反应器制备方法对产品纯度的影响,分析了"热壁流化床"的技术缺陷,"冷壁流化床"的技术优势,对下一步流化床技术发展进行了展望。     

流化床法制备颗粒多晶硅的研究现状

流化床制备颗粒多晶硅的技术具有能耗低、收率高、可连续化生产等优点。本文介绍了流化床制备颗粒多晶硅工艺的硅烷热分解法和三氯氢硅的氢还原法，分别阐述了两种方法的原理、工艺中存在的问题及近些年的研究现状。     

二氯二氢硅综合应用研究进展

详述了二氯二氢硅与四氯化硅进行反歧化反应制备三氯氢硅技术的研究进展,简述了二氯二氢硅在制备多晶硅、硅烷气、多晶硅薄膜、氮化硅薄膜和二氧化硅薄膜中的应用。     

流化床生产多晶硅的研究

在流态化CVD法生产多晶硅的过程中发生了无数的均相反应和异相反应,均相反应十分的复杂,生成的无定形硅粉中含有氢键,是硅粉发生爆炸的关键因素。主要介绍了均相反应和异相反应的反应机理和主要影响因素(反应温度、入口硅烷浓度、进料气速、颗粒的平均直径、反应压力、床层高度等)对多晶硅和硅粉的影响规律。     

基于MP-PIC方法的冶金硅氢氯化流化床反应器模拟

冶金硅氢氯化流化床是目前多晶硅生产工艺中实现四氯化硅（silicon tetrachloride, STC）循环利用的关键反应器。基于MP-PIC方法建立了冶金硅氢氯化流化床反应器模型。模型中反应源项采用总包反应动力学进行计算。在网格以及计算颗粒包含的真实颗粒数量无关性检验的基础上,对反应器内三氯氢硅（trichlorosilane, TCS）初始浓度进行了无关性检验。模型验证结果表明,模拟结果与实验值符合良好。反应器特征分析结果表明：TCS产率受化学平衡与气固两相流动因素共同控制;反应器操作压力对TCS产率的影响较小;提高进口H₂/STC摩尔比,可以提高TCS产率但会降低H₂的转化率。     

Factors affecting methanol photocatalytic oxidation and catalyst attrition in a fluidized-bed reactor

A resolution IV fractional factorial experimental design explored the effects of seven factors on both the methanol photocatalytic oxidation (PCO) rate and the catalyst particle size distribution using a fluidized-bed reactor. The seven factors were as follows: calcination temperature, calcination time, grinding order, particle size, vibration amplitude, carrier gas humidity, and fluidization velocity. Decreasing calcination temperature from 726 to 623 K increased the activity of TiO₂/Al₂O₃ catalysts for methanol PCO. Attrition during fluidization liberated small TiO₂ particles from the bulk catalyst and the rate of attrition increased with gas velocity. Attrition was the primary cause of catalyst elutriation and not the presence of fine particles initially present in the bed from catalyst preparation. Increasing humidity caused agglomeration of fine particles, which reduced the amount of catalyst carryover. Removal of fines from the catalyst bed prior to fluidization caused an increase in catalyst attrition until the amount of fines present in the bed was similar to that of a bed in which fines were not removed.     

Dynamic simulation of a cascade fluidized-bed membrane reactor in the presence of long-term catalyst deactivation for methanol synthesis

In this work, a dynamic model for a cascade fluidized-bed hydrogen permselective membrane methanol reactor (CFBMMR) has been developed in the presence of long-term catalyst deactivation. In the first catalyst bed, the synthesis gas is partly converted to methanol in a water-cooled reactor, which is a fluidized-bed. In the second bed, which is a membrane assisted fluidized-bed reactor, the reaction heat is used to preheat the feed gas to the first bed. This reactor configuration solves some observed drawbacks of new conventional dual type methanol reactor (CDMR) and even fluidized-bed membrane dual type methanol reactor (FBMDMR) such as pressure drop, internal mass transfer limitations, radial gradient of concentration and temperature in both reactors. A dynamic two-phase theory in bubbling regime of fluidization is used to model and simulate the proposed reactor. The proposed model has been used to compare the performance of a cascade fluidized-bed membrane methanol reactor with fluidized-bed membrane dual-type methanol reactor and conventional dual-type methanol reactor. The simulation results show a considerable enhancement in the methanol production due to the favorable profile of temperature and activity along the CFBMMR relative to FBMDMR and CDMR systems.     

煤快速热解制油技术问题的化学反应工程根源:逆向传热与传质

从化学反应工程的角度分析了煤热解过程中挥发物逸出方向与传热方向相反的现象,阐述了反应温度和反应时间对挥发物反应(二次反应)的不同作用,指出提高热源温度加快热解速度的方法反而会促进挥发物二次反应,导致焦油损失与结焦增加,进而提出抑制挥发物二次反应的关键是降低挥发物在反应器中的温升幅度。     

Contribution to emission reduction of CO2 by a fluidized-bed membrane dual-type reactor in methanol synthesis process

In this work, a fluidized-bed membrane dual-type reactor was evaluated for CO₂ removal in methanol synthesis process. The feed synthesis gas is preheated in the tubes of the gas-cooled reactor and flowing in a counter-current mode with reacting gas mixture in the shell side. Due to the hydrogen partial pressure driving force, hydrogen can penetrate from feed synthesis gas into the reaction side through the membrane. The outlet synthesis gas from this reactor is fed to tubes of the water-cooled packed-bed reactor and the chemical reaction is initiated by the catalyst. The methanol-containing gas leaving this reactor is directed into the shell of the gas-cooled reactor and the reactions are completed in this fluidized-bed side. A two-phase dynamic model in bubbling regime of fluidization was developed in the presence of long-term catalyst deactivation. This model is used to compare the removal of CO₂ in a FBMDMR with a conventional dual-type methanol synthesis reactor (CDMR) and a membrane dual-type methanol synthesis reactor (MDMR). The simulation results show a considerable enhancement in the CO₂ conversion due to have a favourable profile of temperature and activity along the fluidized-bed membrane dual-type reactor relative to membrane and conventional dual-type reactor systems.     

Decomposition characteristics of residue from the pyrolysis of polystyrene waste in a fluidized-bed reactor

Effective treatment of residue generated from the pyrolysis of polystyrene wastes has been one of the important factors in the recovery of styrene monomer and oil from polystyrene wastes. Depending on the experimental conditions, the yields of oil and styrene monomer are considerably decreased in the presence of residue. Here the residue was decomposed effectively in a catalytic fluidized-bed reactor. Nitrogen and silica sand were used as a fluidizing gas and a bed material, respectively. Effects of catalyst, temperature and gas velocity on the characteristics of decomposition of the residue were examined. It was found that the residue could be decomposed to oil or chemicals effectively by means of a catalytic fluidized-bed reacting system. The yields of oil and individual chemicals and the composition of the products were dependent upon the operating variables such as reaction temperature, catalyst and gas velocity.     

废轮胎热裂解技术研究现状与进展

结合目前废旧轮胎资源化处理现状及研究成果,本文对热解机理、热解技术进行分析、对比,着重介绍了热解温度、升温速率、物料粒径、催化剂等工艺参数对热解产物产率的影响,分析表明Coast-Redfern积分法所得动力学模型较准确,平均反应活化能为129.5kJ/mol;现有的研究表明,热解温度对产物产率影响最大,气相产物与液相产物产率随温度升高而增加,其中液相产物产率相对较高的热解温度在500~550℃范围内,固相产物品质较高的热解温度在500~650℃范围内。其次对其固、液、气三相产物特性及应用和污染物（S、PAHs）的分布与控制方法做了归纳总结,为废旧轮胎热解技术向工业化发展提供技术依据。     

复合流化床低阶煤热解制备兰炭的工艺条件

以不同粒径范围的新疆准东煤为原料,在耦合下部流化床和上部输送床的复合流化床中热解制备兰炭,考察了热解温度、过量氧气系数、气化温度、煤颗粒停留时间等对热解产物分布和热解半焦性质的影响. 结果表明,随过量氧气系数、气化温度和颗粒平均停留时间增加,气体产率升高,半焦和焦油产率降低;半焦的比表面积随气化温度升高而增大,而随过量氧气系数增大先增大后减小. 当煤从下部流化床进料时,在过量氧气系数0.11、流化床气化温度850℃、输送床热解温度750℃、流化床内煤颗粒停留时间90 s的操作条件下,可制备出固定碳含量超过83%(w)、挥发分含量低于9%(w)的兰炭.     

煤与生物质的共热解

对近年来煤与生物质共热解的研究作了综述，研究的焦点集中在富氢的生物质向贫氢的煤的转移，即寻找是否存在所谓的协同效应，在固定床，流化床等类型反应器中煤与生物质共热解的研究没有发现协同效应，这主要是因为煤与生物质热解温度的差异所造成的，至今还没见到在自由落下床中煤与生物质共热解的研究报道，在这种类型的反应器中，物料自由落下，物料粒子的温度很大程度上依赖于其黑度，由于煤的黑度远远大于生物质的黑度，在自由落下床中可以使二者达到同步热解，此外，生物质热解产生的富氢气体可以作为煤加氢热解的氢源，在这个基础上，提出了两步法共热解的思路。     

油砂热解特性及工艺与装置研究开发现状与评述

油砂是一种储量巨大的非常规石油资源,油砂热解技术具有良好的工业化前景。本文概述了油砂热解的相关基础研究进展,包括油砂热解的3个阶段、气液固三相产物的性质及多种油砂热解动力学模型的总结。分析了常压干馏、惰性气体保护热解、加氢热解、减压热解及复合热解工艺,简述了不同工艺对产品收率和产品性质等方面的影响。回顾了油砂热解的装置,从固定床、旋转干馏炉、流化床干馏炉到Alberta Taciuk Process （ATP） 装置,重点介绍了具有不同载热方式和能量回收方式的旋转干馏炉和流化床干馏炉。从能源利用效率的角度分析对比了各种热解工艺和热解设备的优势与劣势,阐明了降低能耗提高能源效率是热解技术的主要问题,进而提出了旋转干馏炉和流化床干馏炉具有更好的工业前景。