电石渣直接湿法碳酸化固定CO2的反应特性

碱性固废湿法碳酸化是一种矿化固定CO₂的有效方式。为探究电石渣废弃物直接湿法碳酸化固定CO₂的反应特性，基于高压反应釜试验装置，在常温环境下研究液固比(5～20)、碳酸化时间(0～4 h)和反应压力(0.1～1.0 MPa)对电石渣碳酸化速率和CO₂固定能力的影响。结果表明，电石渣具备良好的CO₂固定能力，1 h内整体碳酸化反应基本完成，CO₂固定能力会随液固比和反应压力的增加而提升。反应时间4 h,最优工况(1 MPa、液固比20)下电石渣的CO₂固定量达9.26 mmol/g,而在0.1 MPa、液固比5时，电石渣的CO₂固定量仅3.58 mmol/g。电子扫描显微镜和热重分析证明了电石渣碳酸化反应后生成了大量CaCO₃,且碳酸化产物的粒径显著减小。因此，在反应釜中常温加压条件下，电石渣直接液相碳酸化即具备较好的CO₂固定能力和较高的碳酸化效率。本研究结果能为电石渣加速矿化固定CO     

碱性工业固废矿化封存二氧化碳研究进展

温室效应引起的全球变暖已经影响到人类的生存和发展，CO₂减排刻不容缓。CO₂矿物碳酸化作为一种CO₂减排技术，受到越来越多的关注。相对于传统天然矿化原料，碱性工业固废具有反应速率快、碳酸化效率更高、能耗低等特点，并且利用碱性工业固废进行CO₂矿化还可以产出高附加值产物用于化工、建筑等领域。本文主要综述了碱性工业固废的矿化机理，利用碱性工业固废(粉煤灰、钢渣、电石渣)进行CO₂碳酸化的研究进展及吸收-矿化一体化(IAM)技术。对于以碱性工业固废为原料的碳酸化技术，未来应进一步加强机理和生命周期影响评价的研究并优化工艺流程；针对IAM工艺今后应开发出高效、经济的吸收剂和封存能力更好的矿化原料，并加强对IAM工艺反应机理的研究。     

间歇氯化对电石渣循环捕集CO2性能的影响

提出在碳酸化气氛中间歇加入HCl（间歇氯化）提高电石渣在循环煅烧/碳酸化反应中捕集CO₂性能的新思路。在双固定床反应器上,在不同循环次数加入HCl、碳酸化温度、CO₂/HCl体积比等条件下,研究HCl间歇加入对电石渣循环碳酸化特性的影响。结果表明,在循环煅烧/碳酸化反应中间歇加入HCl使电石渣间歇氯化能提高其循环捕集CO₂性能。在前N次循环碳酸化时加入0.1% HCl,当N=4时能使电石渣获得最优CO₂捕集性能,第10个循环时的CO₂吸收量比无HCl时提高了51%。HCl与CaCO₃发生氯化反应,破坏致密产物层对CO₂扩散的阻碍,提高了电石渣的碳酸化转化率。在碳酸化气氛加入HCl时,最佳碳酸化温度仍为700℃。随CO₂/HCl体积比增大,HCl对电石渣捕集CO₂性能的促进作用减弱。     

电石渣制备球霰石型CaCO3的影响因素研究

为了高附加值利用电石渣以及封存CO₂,以电石渣为原料，使用多种添加剂，常压制备了球状球霰石。利用粉末X射线衍射仪、扫描电子显微镜、傅里叶变换红外光谱仪等考察了添加剂种类、反应温度、电石渣中杂质、反应体系对合成CaCO₃中球霰石的影响。结果表明，甘氨酸和丝氨酸对诱导生成球霰石的效果显著，反应温度的增加不利于球霰石的生成，电石渣中的杂质Al₂O₃和SiO₂可以诱导Ca(OH)₂矿化CO₂体系形成方解石。不同反应体系会影响所制备球霰石的晶体大小，电石渣-CO₂体系制备的晶体尺寸最小。在15℃的电石渣-CO₂反应体系中，通过添加甘氨酸可以制备单分散的表面有粗糙突起的球霰石型CaCO₃。以上研究结果为利用电石渣等碱性工业废渣制备高附加值球霰石，同时安全有效封存大量CO₂温室气体提供了一种简便方法。     

超声波强化钙基废渣碳酸化固定CO2的性能

钙基废渣碳酸化固定CO₂可实现CO₂的永久封存,并可实现CO₂原位固定,但苛刻的反应条件、过慢的反应速率是困扰该技术发展的瓶颈。对超声波作用下的钙离子浸出及其碳酸化反应特性进行了实验研究,并与搅拌浸出过程进行了对比,考察了浸出条件的影响及其碳酸化反应过程中溶液pH值与电导率变化特性,对碳酸化反应产物进行了XRD、SEM和TGA分析。结果表明,超声波可有效促进Ca2+从钙基废渣中浸出,其促进效果与废渣种类、浸出时间、超声波功率、浸取剂pH值、浆液存放量和废渣粒度等有关,钢渣和电石渣的含钙量、浸出率和超声波强化效果都较其他废渣高;钙离子浸出浓度随超声波功率的增强而增多;浸取剂pH值越低,浸出浓度越高;废渣粒度越高,超声波作用越明显。超声波对碳酸化反应也有强化效果,与机械搅拌相比,在超声波作用下固碳率更高,碳酸化反应程度更高。     

CO2矿物封存技术研究进展

CO₂捕集与封存技术是目前实现碳减排最有效的方法。其中,CO₂矿物封存（又称CO₂矿化）是利用CO₂与含钙镁硅酸盐矿物进行反应使CO₂以稳定的碳酸盐形式永久储存起来。本文首先介绍了CO₂矿化的基本原理和技术路线,其中间接矿化反应条件较温和、矿化效率更高、得到的产物也更纯,因此对于CO₂间接矿化的研究也更广泛。本文综述并对比了天然矿物及工业固废矿化CO₂的研究进展,指出工业固废更有利于CO₂矿化过程。工业固废矿化CO₂过程矿化CO₂的同时处理了工业固废,实现以废治废,因此它在经济上也是具有一定优势。在此基础上,本文以高炉渣为代表,介绍了其矿化CO₂的详细研究进展,指出采用可循环的助剂、回收高炉渣中有价元素可提升矿化过程经济性。对于CO₂矿化过程的放大试验、生命周期的评估及低能耗的新工艺开发将是CO₂矿物封存实现工业化的关键。     

CO2矿化及吸收-矿化一体化(IAM)方法研究进展

为避免温室效应带来的负面影响,CO₂减排已成为目前的当务之急。CO₂矿物碳酸化作为一种有潜力的CO₂减排技术,受到了学者们的广泛关注。CO₂矿物碳酸化方法主要包括直接干法碳酸化、直接湿法碳酸化以及间接碳酸化等不同工艺过程。目前,CO₂直接或间接碳酸化方法面临的关键挑战是提升CO₂碳酸化反应动力学特性;反应速率慢、碳酸化效率较低是当前该技术的主要问题。传统CO₂胺类化学吸收法具有吸收速率快、吸收容量大和吸收剂能循环再生的优点,但能耗和运行成本较高。将CO₂胺类化学吸收法与CO₂碳酸化过程结合而开发的CO₂吸收-矿化一体化技术（IAM）不仅解决了传统工艺高能耗、低转化率的问题,而且使工艺流程简化、成本降低,有利于应用于工业化。本文主要综述了近年来CO₂矿化技术的研究进展,对比了各种工艺技术路线的不同特点,并分析指出加强对IAM工艺反应机理的研究以及开发出高效、经济的吸收剂和矿化原料,将是该工艺未来研究的重点和关键。     

钙硅酸盐矿物湿法碳酸化封存二氧化碳实验研究

钙硅酸盐矿物湿法碳酸化封存CO₂是具有发展前景的固碳技术。为了比较不同种类的含钙硅酸盐矿物固碳效果的差异，研究了温度、压力、液固比(mL/g)、粒度及矿物添加剂(NaHCO₃和NaCl)对硅灰石和钙长石湿法碳酸化封存CO₂效果的影响。结果表明，硅灰石和钙长石的碳酸化产物分别是方解石和文石，热重实验结果显示，方解石的热稳定性强于文石。各实验条件下硅灰石碳酸化转化率均高于钙长石，两种矿物碳酸化转化率随压力增大、粒度减小、NaHCO₃和NaCl的加入而增大；获得了硅灰石和钙长石的最大碳酸化转化率分别为83.62%、16.20%，二者差异显著。在温度为120～210℃两种矿物溶解吉布斯自由能(ΔG_r)的计算表明，硅灰石溶解过程的吉布斯自由能始终小于钙长石溶解吉布斯自由能，说明硅灰石溶解速率和溶解反应自发进行的程度都大于钙长石，这是影响钙硅酸盐矿物碳酸化反应活性的关键因素。     

CO2碳酸化石灰岩酸解产物回收乙酸及副产沉淀碳酸钙

乙酸酸解石灰石造腔是一种建造地下储库同时环保地开采石灰岩制备沉淀碳酸钙的新方法。通过耦合乙酸酸解石灰石及酸解产物乙酸钙CO₂碳酸化的工艺过程,研究了乙酸酸解石灰岩的表面反应动力学和乙酸钙CO₂碳酸化的工艺技术条件。采用正交实验分析法,研究了CO₂碳酸化反应中乙酸钙浓度、反应温度、CO₂压力、反应时间对乙酸钙碳酸化反应制沉淀碳酸钙的影响,并通过正交实验确定了最优化操作条件。实验结果表明,乙酸酸解反应速率主要受乙酸浓度控制。CO₂碳酸化反应在当乙酸钙溶液浓度为0.631 mol·L^-1,CO₂压力为5.0 MPa,温度为80℃,反应时间为50 min时CO₂碳酸化效率达到最高（23.13%）,生成的沉淀碳酸钙产品各项指标均符合中国国标优级要求。     

烟气中水蒸气对钙基吸收剂碳酸化的影响特性

在循环煅烧/碳酸化反应系统上考察煅烧气氛和碳酸化气氛中水蒸气含量以及CO₂分压对钙基吸收剂成型颗粒碳酸化的影响,通过对钙基吸收剂微观结构分析(扫描电镜、氮吸附分析)以理解水蒸气影响碳酸化特性的机理。结果表明,煅烧气氛和碳酸化气氛中的水蒸气均可提高钙基吸收剂的碳酸化转化率,水蒸气含量分别为10%和5%时,吸收剂的碳酸化性能较好;水蒸气在碳酸化气氛中对高铝水泥改性吸收剂的改善作用较石灰石显著。煅烧气氛中的CO₂分压越高,烧结现象越严重,降低钙基吸收剂的捕集效率;碳酸化气氛CO₂分压提高,有利于提高钙基吸收剂的碳酸化转化率。烟气中水蒸气丰富了吸收剂的微观孔隙,使得吸收剂捕集CO₂性能得到改善。     

不锈钢渣碳化影响因素及其机理研究

为开发γ-C₂S不锈钢渣碳储存的潜力,最大限度地提高不锈钢渣的综合利用率。通过研究主要碳化参数(如液固比、成型压力、CO₂分压)对不锈钢渣碳化性能的影响规律来评估不锈钢渣的CO₂储存能力,以期能够提供更佳的不锈钢渣碳化过程。利用XRD、SEM/EDS、DSC/TG分析对不锈钢渣碳化产物组成及微观形貌进行表征,并探索其碳化机理。结果表明,较佳碳化参数为成型压力为2.50 MPa,液固比为10%,CO₂分压为0.3 MPa。较佳碳化条件下每千克不锈钢渣可固化储存CO₂气体约123.6 g。不锈钢渣碳化过程以γ-C₂S碳化反应为主,碳化产物中出现了片状、颗粒状的CaCO₃,随碳化时间延长,晶体逐渐长大为团簇状。因此,利用不锈钢渣储备碳及制备碳化制品是可行的。     

Gas-Liquid Mass Transfer Characteristics in a Gas-Liquid-Solid Bubble Column under Elevated Pressure and Temperature

abstract The volumetric mass transfer coefficient kLa of gases (H2, CO, CO2) and mass transfer coefficient kL on liquid par-affin side were studied using the dynamic absorption method in slurry bubble ...     

Experimental studies of air-blast atomization on the CO2 capture with aqueous alkali solutions

In this work, an air-blast atomizing column was used to study the CO₂ capture performance with aqueous MEA (mono-ethanol-amine) and NaOH solutions. The effects of gas flow rate, the liquid to gas ratio (L/G), the CO₂ concentration on the CO₂ removal efficiency (η) and the volumetric overall mass transfer coefficient (K_Ga_v) were investigated. The air-blast atomizing column was also compared with the pressure spray tower on the studies of the CO₂ capture performance. For the aqueous MEA and NaOH solutions, the experimental results show that the η decreases with increasing gas flow rate and CO₂ concentration while it increases with increasing L/G. The effects on K_Ga_v are more complicated than those for η. When the CO₂ concentration is low (3 vol%), K_Ga_v increases with increasing gas flow rate while decreases with increasing L/G. However, when the CO₂ concentration is high (9.5 vol%), as the gas flow rate and L/G increases, K_Ga_v increases first and then decreases. The aqueous MEA solution achieves higher η and K_Ga_v than the aqueous NaOH solution. The air-blast atomizing column shows a good performance on CO₂ capture.     

电石渣-矿渣复合胶凝材料性能研究

电石渣作为一种工业废渣,其碱度较高,综合利用率较低。为了解决过量的电石渣,利用电石渣的强碱性,研究了电石渣对矿渣胶凝体系的碱激发性能。利用电石渣碳化反应可生成碳酸钙的特性,探索了不同碳化制度对电石渣碱激发矿渣胶凝体系的性能影响规律。结果表明:大掺量电石渣对矿渣胶凝材料有很好的碱激发效果,生成大量的C-(A)-S-H凝胶,而复掺粉煤灰和偏高岭土胶凝体系性能最佳;电石渣-矿渣复合胶凝体系经过不同碳化制度处理后,胶凝体系力学性能有效提升;使用CO₂气体作为外部碳化源,材料基体表层生成致密结构,基体力学性能提升;使用尿素作为内部碳化源,基体内部碳化均匀,胶凝体系力学性能提升。     

CO2 mineralization of carbide slag for the production of light calcium carbonates

The production of polyvinyl chloride by calcium carbide method is a typical chemical process with high coal consumption, leading to massive flue gas and carbide slag emissions. Currently, the carbide slag with high CaO content is usually stacked in residue field, easily draining away with the rain and corroding the soil. In this work, we coupled the treatment of flue gas and carbide slag to propose a facile CO₂ mineralization route to prepare light calcium carbonate. And the route feasibility was comprehensively evaluated via experiments and simulation. Through experimental investigation, the Ca²⁺ leaching and mineralization reaction parameters were determined. Based on the experiment, a process was built and optimized through Aspen Plus, and the energy was integrated to obtain the overall process energy and material consumption. Finally, the net CO₂ emission reduction rate of the entire process through the life-cycle assessment method was analyzed. Moreover, the relationship between the parameters and the CO₂ emission life-cycle assessment was established. The final optimization results showed that the mineralization process required 1154.69 kW·h·(t CO₂)^-1 of energy (including heat energy of 979.32 kW·h·(t CO₂)^-1 and electrical energy of 175.37 kW·h·(t CO₂)^-1), and the net CO₂ emission reduction rate was 35.8%. The light CaCO₃ product can be sold as a high value-added product. According to preliminary economic analysis, the profit of mineralizing can reach more than 2,100 CNY·(t CO₂)^-1.     

CO2 capture by double metal modified CaO-based sorbents from pyrolysis gases

High-temperature pyrolysis technology can effectively solve the problem of municipal solid waste pollution. However, the pyrolysis gas contains a large amount of CO₂, which would adversely affect the subsequent utilization. To address this problem, a novel method of co-precipitation modification with Ca, Mg and Zr metals was proposed to improve the CO₂ capture performance. X-ray diffraction (XRD) patterns and energy dispersive X-ray spectroscopy analysis showed that the two inert supports MgO and CaZrO₃ were uniformly distributed in the modified calcium-based sorbents. In addition, the XRD results indicated that CaZrO₃ was produced by the reaction of ZrO₂ and CaO at high temperatures. The effects of doping ratios, adsorption temperature, calcination temperature, CO₂ concentration and calcination atmosphere on the adsorption capacity and cycle stability of the modified calcium-based sorbent were studied. The modified calcium-based sorbent achieved the best CO₂ capture performance when the doping ratio was 10:1:1 with carbonation at 700 ℃ under 20% CO₂/80% N₂ atmosphere and calcination at 900 ℃ under 100% N₂ atmosphere. After ten cycles, the average carbonation conversion rate of Ca-10 sorbent was 72%. Finally, the modified calcium-based sorbents successfully reduced the CO₂ concentration of the pyrolysis gas from 37% to 5%.     

Local hydrodynamics of gas–liquid-nanoparticles three-phase fluidization

The laser Doppler anemometer (LDA) and conductivity probes were used for measuring the local hydrodynamic performances such as gas holdup and liquid velocity in a lab-scale gas–liquid–TiO₂ nanoparticles three-phase bubble column. Effects of operating parameters on the local gas holdup and liquid velocity were investigated systematically. Experimental results showed that local averaged axial liquid velocity and local averaged gas holdup increased with increasing superficial gas velocity but decreased with increasing TiO₂ nanoparticles loading and the axial distance from the bottom of the bubble column. A three-dimensional computational fluid dynamic (CFD) model was developed in this paper to simulate the structure of gas–liquid–TiO₂ nanoparticles three-phase flow in the bubble column. The time-averaged and time-dependent predictions were compared with experimental data for model validation. A successful prediction of instantaneous local gas holdup, gas velocity, and liquid velocity were also presented.