煤/煤焦油/沥青质的热等离子体裂解特性比较分析

针对化石资源劣质化和大宗低价值化工中间产品的反应工程新问题,提出利用热等离子体超高温特性实现极端条件下难利用原料的高效清洁转化,重点探讨并比较了煤化工中的原煤、煤焦油和石油化工中的沥青质的热等离子体裂解特性。通过热等离子体裂解实验室小试装置考察了3种典型原料的裂解行为,结果表明,煤焦油和沥青质具有高于煤的转化率和乙炔收率;建立了基于热力学的热等离子体裂解反应过程的能量平衡分析方法,模拟计算了不同操作条件下各原料在兆瓦级中试装置上的裂解结果,给出了相同等离子体能量注入的条件下不同原料裂解过程的物流和能流关系;并进一步模拟分析了原料间混合裂解的混料配比对裂解气的影响,为热等离子体裂解过程的工业原料筛选和原料混合裂解提供了科学依据。     

热等离子体裂解煤制乙炔的研究进展

热等离子体裂解煤制乙炔过程为煤的直接化工利用提供了一条有前景的、清洁的转化途径,有望成为替代传统的电石法乙炔生产工艺的新技术。本文对等离子体煤裂解制乙炔的实验室及工业中试研究进行了评述,综述了该过程在反应体系热力学分析、实验室和工业中试规模实验研究以及产物气急冷技术等方面的研究进展,分析了该过程在工业化进程中尚存在的关键性问题,提出有待深入开展的基础研究方向。     

热等离子体裂解煤一步法制乙炔关键技术及过程经济性分析

热等离子体裂解煤一步法制乙炔过程为煤的直接化工利用提供了一条绿色、清洁和高效率的转化途径。基于兆瓦级热等离子体裂解煤反应器的研发,概述了已有的基础和工程研究成果,并重点从高效气固混合、结焦控制以及反应器优化与放大3个方面探讨了反应器的一些关键技术问题。从反应系统角度出发,基于对该过程的物料、能量衡算和经济效益分析结果,指出能量和物料的综合利用是该过程经济性的保证。     

热等离子体热解煤焦油制乙炔

利用热等离子高温、高焓等特性热解煤焦油制乙炔是一条清洁高效的乙炔生产技术。在实验室对热等离子体热解煤焦油反应中的原料进样温度、反应气氛、输入比焓等关键因素展开了研究。结果表明,热等离子体可将煤焦油直接转化为乙炔及其他小分子气态产品,预热煤焦油可改善其流动性从而提高煤焦油和等离子体射流的初始混合效率;氢等离子体的加入可显著提高煤焦油转化率和乙炔收率并减少结焦;随着输入比焓的增加,煤焦油转化率、乙炔收率和气态产品总收率均得到提高。在实验中得到的煤焦油转化率最高为86.3%,乙炔收率最高为24.6%,气态产品总收率最高为51.7%。煤焦油在热等离子体的热解过程中副产乙烯,乙烯收率达到7.9%。乙炔收率和乙烯收率的比值可用于预测气相体系温度。     

热等离子体热解煤焦油制乙炔

利用热等离子高温、高焓等特性热解煤焦油制乙炔是一条清洁高效的乙炔生产技术。在实验室对热等离子体热解煤焦油反应中的原料进样温度、反应气氛、输入比焓等关键因素展开了研究。结果表明,热等离子体可将煤焦油直接转化为乙炔及其他小分子气态产品,预热煤焦油可改善其流动性从而提高煤焦油和等离子体射流的初始混合效率;氢等离子体的加入可显著提高煤焦油转化率和乙炔收率并减少结焦;随着输入比焓的增加,煤焦油转化率、乙炔收率和气态产品总收率均得到提高。在实验中得到的煤焦油转化率最高为86.3%,乙炔收率最高为24.6%,气态产品总收率最高为51.7%。煤焦油在热等离子体的热解过程中副产乙烯,乙烯收率达到7.9%。乙炔收率和乙烯收率的比值可用于预测气相体系温度。     

非热等离子体催化转化C1分子及其催化剂研究进展

非热等离子体催化具有反应条件温和、启动快和反应器结构紧凑等特点,在C₁分子催化转化领域（如CO₂加氢、甲烷活化、水煤气变换反应和甲醇重整制氢）有着广阔的应用前景。具体来说,等离子体特有的高能电子可在气相中快速活化稳定性极强的C₁分子并生成活性物质,接着与催化剂结合发生表面化学反应,从而实现常温常压下C₁分子的高效转化。然而,等离子体与催化剂之间的协同作用机制以及催化机理极为复杂,仍有待进一步研究。本综述简单介绍了非热等离子体催化转化C₁分子的近期研究进展,重点探讨了适用于非热等离子 体的催化剂研究以及催化机理的高级原位表征。最后,提出了非热等离子体催化转化C₁分子的未来发展方向：①设计并构筑适用于非热等离子体催化的高效催化剂,并研究其构效关系;②发展高级原位表征技术,揭示活性物质的作用机理以及催化机理;③设计并构建高效的等离子体催化反应器,并建立反应器的理论模型和数值模拟方法,科学指导等离子体反应器的设计、优化和放大。     

碱性介质活性氧调控技术在湿法冶金中的研究进展

化工冶金制造业的绿色化升级需从清洁生产技术创新入手,研发重大特色资源的高效绿色合理利用技术是实现资源环境可持续发展的关键。张懿院士开创建立的亚熔盐介质清洁化工冶金共性技术,实现了多种具有化学共性的难处理两性金属矿物的高效清洁转化与分离,并建立了以活性氧调控技术为核心的亚熔盐介质化学理论体系。基于活性氧的电化学基础研究,本工作进一步提出了以电化学活性氧调控技术为核心的碱性介质电化学高级氧化新体系,为活性氧调控技术在冶金、资源和环境等领域的应用提供理论和技术支持。     

等离子体多相反应器基础研究和过程强化

等离子体是物质第四态,其中大量高能活性粒子的存在,使得等离子体强化的化学反应过程展示出特殊外场作用下的非常规行为。一方面,等离子体提供的高活性环境,可以从原子/分子尺度大大强化化学反应过程,特别是实现非常规条件下的反应;另一方面,等离子体的特有性质,在介观尺度改变了相间接触行为,形成区别于常规多相流的独特的流体力学、传递和反应特性。本文概述了将低温等离子体的理化特性与多相反应过程集成,所形成的相关基础研究和低温等离子体反应器的工业发展,包括热等离子体煤制乙炔,冷等离子体气固催化、氯化聚氯乙烯合成以及气液等离子体反应过程。     

连续微反应加氢技术在有机合成中的研究进展

加氢反应是有机合成中很常见的一种反应类型,采用常规的间歇加氢釜具有反应效率低、操作烦琐和安全性差等问题。而连续加氢微反应器进行非均相催化加氢反应能提供更高的传质性能,催化剂的回收利用与产物的纯化也更为方便,能极大地提高生产效率,减少贵金属催化剂的损失。因为这些优点,连续微反应加氢技术得到了越来越多的关注。本文阐述了连续微反应加氢技术中常用的微反应器与固体金属催化剂类型,以及不同官能团非均相高效催化加氢的研究进展,在此基础,对该技术在精细化工领域的应用进行了展望。连续微反应加氢技术使得加氢过程可以在更安全、更高效、更环保的条件下完成,具有很高的工业应用价值,是未来化学化工领域重点发展的方向之一。     

热等离子体转化煤的研究进展

介绍了热等离子体裂解煤制乙炔、富勒烯、碳纳米管和炭黑,以及热等离子体煤气化制合成气的原理、研究现状、存在的主要问题及发展前景。指出热等离子煤转化是一种高效、洁净的技术,在煤化工等领域具有巨大的应用和发展空间,尤其是热等离子体裂解煤制乙炔联产氢与纳米碳材料工艺,值得重视和开发。     

煤粉高温快速裂解过程的颗粒内部传递行为

热等离子体裂解煤制乙炔为超高温毫秒级反应过程,煤粉升温及脱挥发分过程直接决定了反应器的乙炔产率和经济性。建立了描述单颗粒煤粉高温快速裂解过程的机理模型,综合考虑了颗粒自身导热阻力及挥发分逸出煤粉所伴生的热阻效应。模型预测表明颗粒内部传热阻力显著影响煤粉的热裂解过程,与忽略颗粒内部传热阻力相比,脱挥发分时间减慢30%～40%,且颗粒粒径增大该影响越加明显;提高供热流体温度可加速、加强煤裂解反应深度。针对毫秒级煤裂解过程,大于100μm的煤粉或者低于2000K的热流体温度均难于实现满意的脱挥发分行为,所得结果为反应器的设计和操作提供了重要的指导。     

Downer reactor: From fundamental study to industrial application

Downer reactor, in which gas and solids move downward co-currently, has unique features such as the plug-flow reactor performance and relatively uniform flow structure compared to other gas-solids fluidized bed reactors, e.g., bubbling bed, turbulent bed and riser. Downer is therefore acknowledged as a novel multiphase flow reactor with great potential in high-severity operated processes, such as the high temperature, ultra-short contact time reactions with the intermediates as the desired products. Typical process developments in industry have directed to (1) the new-generation refinery process for cracking of heavier feedstock to gasoline and light olefins (e.g., propylene) as by-products; and (2) coal pyrolysis in hydrogen plasma which opens up a direct means for producing acetylene, i.e., a new route to synthesize chemicals from a clean coal utilization process. This paper is to give a comprehensive review on the development of fundamental researches on downer reactors as well as the particular industrial demonstrations for the fluid catalytic cracking (FCC) of heavy oils and coal pyrolysis in thermal plasma.     

气液等离子体过程强化技术及其在高级氧化过程的应用

气液等离子体过程强化技术是20世纪80年代发展起来的一门新兴交叉学科,在高级氧化过程、液相化学合成和纳米材料制备等领域具有巨大的研究与应用价值。从化学工程的角度理解,气液等离子体过程强化技术的本质是特殊外场作用下的多相传递与反应过程,其中涉及高能电子碰撞、化学活性组分氧化、紫外光解和冲击波等多种物理与化学作用。由于气液等离子体过程强化技术本身的复杂性及多学科交叉性,对其复杂的物理与化学耦合机理还未得到充分认识,同时缺乏对气液等离子体反应器的系统研究及设计指导,从而极大程度地限制了该技术的进一步应用和发展。为全面认识气液等离子体过程强化技术,本文综述了近年来有关气液等离子体过程强化技术的诊断及机理研究进展,并剖析了气液等离子体反应器的设计思路,同时回顾和展望了气液等离子体高级氧化过程的最新研究进展,讨论了气液等离子体过程强化技术的研究方向。     

高频热等离子体热解水氯镁石沉积氧化镁薄膜

我国盐湖资源丰富,其中位于青海的察尔汗盐湖是我国最大的钾肥生产基地。然而在钾肥生产过程中副产的大量水氯镁石（MgCl₂·6H₂O）目前尚得不到有效的利用,“镁害”已经成为盐湖卤水提钾后的首要问题。本文提出以高频热等离子体为高温热源,强化水氯镁石的热解过程,同时将热解产物沉积得到高附加值的MgO薄膜。研究结果表明,该工艺热解效率高,热解得到高纯的MgO薄膜,沉积效率可达到3.2 mm·min^-1,薄膜颗粒粒径处于10～60 nm之间,具有良好的光致发光性能;同时沉积工艺过程简单,适合大规模连续化生产。     

Synthesis of nanograined zirconium diboride microsphere powder feedstock via emulsification of suspensions

Ceramic nanograined materials have desirable characteristics compared to their macroparticle counterparts but are rarely used in industrial applications due to issues with poor handleability and health hazards. Due to interparticle forces that become more dominant as the particle size decreases, it is difficult to use nanomaterials to fill dies, spread on surfaces, or flow through hoppers found in various manufacturing processes. Here we report a scalable gelcasting solution and unique emulsification process to create microspheres composed of nanoscale powders to enhance the flowability and handleability of nanomaterials. The gelcasting solution and emulsification process can be used with any nanoparticle composition that can be suspended in a liquid phase. This paper reports the effects of various parameters on zirconium diboride microsphere formation, such as surfactant content and mixing conditions. The microspheres maintain the nano-scale characteristics of the powder but improve its flowability by using cross-linked polyvinyl alcohol to combine irregularly shaped zirconium diboride nanoparticles with a particle diameter of 60 nm into larger spherical particles with a d₅₀～25 μm. This hierarchical feedstock engineering design combine the positive characteristics of materials across both length scales and improve the flowability of the feedstock from a Hausner Ratio of 1.56 to 1.19. The materials produced using this technique can be used in thermal plasma spray, die filling for hot pressing or spark plasma sintering, and binder jet printing applications.     

Towards synthesis of an optimal thermal cracking reactor

To develop new reactor options for thermal cracking of ethane or other light hydrocarbons to lower olefins a fundamental process synthesis approach is taken. Firstly, an optimal reaction path and conditions are targeted, starting from a mechanistic reaction network. Secondly, to implement the optimal reaction path the reactor geometry and equipment are designed. This contribution focuses on the development of a targeting approach, for which a new distributive reaction-mixing synthesis model is formulated and applied. The mixing kernel in the model provides freedom to redistribute the reaction mixture along a continuous reaction coordinate to optimize product yield. The model was validated for two applications. It reproduces the results for the Van de Vusse reaction network as obtained by the attainable region theory. When applied to a small reaction network for the conversion of ethane into ethylene, it reconfirms the existing result that for this network the plug flow mode at maximum temperature and minimum pressure gives the optimal olefin yield.     

Additive manufacturing of ZrB2–ZrSi2 ultra-high temperature ceramic composites using an electron beam melting process

Owing to their high melting points and ability to resist extreme thermal stresses, ultra-high temperature ceramics (UHTCs) are important materials for critical applications such as hypersonic flights, space re-entry vehicles, and rocket engines. Traditional manufacturing processes restrict the freedom to manufacture UHTCs with complex geometries due to the limitations of die and mold designs. Electron beam melting (EBM) is an established powder-bed layer-by-layer additive manufacturing (AM) process for metal parts. In this research, an effort was made to evaluate the feasibility of EBM for the AM fabrication of UHTC-based materials, and to investigate the microstructures of the fabricated materials under different processing conditions. A mathematical model was developed to simulate and optimize the processing parameters for the fabrication of ZrB₂-30 vol% ZrSi₂ UHTC using EBM. The simulation results were compared with experimental observations. For EBM fabrication of ZrB₂-30 vol% ZrSi₂ composites, the optimal processing parameters are beam power of 500 W with scanning speeds of 500, 750, and 1000 mm/s, and beam power of 1000 W with scanning speed of 1000 mm/s. This study demonstrates the potential for additive manufacturing of UHTCs with complex geometries by the EBM technique.     

Influence of high ash Indian coals in fluidized bed gasification under different operating conditions

Coal gasification has been internationally accepted as one of the most viable and effective clean coal technology for power generation. Presently, the coal being produced in India is having high ash content and it is a major constraint for most of the commercial applications in process industries. The present paper deals with the variation of higher heating value (HHV) of the product gas and carbon conversion with different inherent properties under different operating conditions in fluidized bed gasification. It has been observed that HHV of product gas increases with volatile mater, fixed carbon and temperature, whereas, mineral matter, air and steam show decreasing effect on HHV. On the other hand, carbon conversion increases with volatile matter, air, steam and temperature. It has also been observed that mineral matter provides catalytic effect to a certain level for carbon conversion, whilst, decreasing trend has been observed with the fixed carbon.