石灰碳化煤球碳化机理及新工艺探讨

对石灰颗粒，单个煤球的碳化过程，以新观点解释了煤球碳化机理，研究了成型压力与煤球质量，碳化速率及预干燥的关系。提出低压成型，高料层你温碳化及后补强期的新工艺。     

纳米碳酸钙引进技术中多级鼓泡碳化工艺探讨

对引进的日本、意大利及中国台湾的纳米碳酸钙生产工艺中的碳化技术进行对比，反映出多级鼓泡碳化与单一间歇鼓泡碳化在工艺、设备及控制等方面的差异，从而决定了产品在应用中的差异。为降低生产成本，实现常温碳化制备纳米碳酸钙，晶核预成技术在工业化生产中得到了广泛的应用，并不断完善。指出企业应根据全套生产装置特点对产品的应用方向做出选择。     

新型组合式纳米碳酸钙碳化工艺研究

结合中国现有的鼓泡碳化、喷雾碳化以及超重力反应的特点，研制并设计出一套鼓泡和喷雾碳化相结合的新型碳化工艺技术，生产出粒径分布在40～60nm，且结晶规整、分散良好的纳米级碳酸钙产品。     

超细碳酸钙制备新工艺

根据石灰乳悬浊液碳化反应的机理，设计并研制出管式碳化法生产超细碳酸钙的新工艺，通过管式碳化反应法与传统的间歇鼓泡式碳化反应的比较，从生成物的沉降体积、碳化率、碳化时间等数据说明二的特点，为今后的研究及工业化生产提供依据。     

高纯度二氧化碳生产超细碳酸钙的碳化机理

以连续鼓泡碳化法为研究对象，以高纯度CO2为碳化气，用双膜理论探讨了生产超细碳酸钙的碳化反应机理，为实际生产中碳化反应速率与产品粒径大小实行分级控制、防止包裹返碱现象的发生、优化工艺参数提供了理论依据。该结论虽来源于连续鼓泡碳化法，但对其它生产方法也具有一定的参考价值。     

年产四万吨联碱碳化操作压力初探

本文通过对联碱系统中塔压对碳化操作影响的现场及理论分析,阐述了碳化操作压力对整个碳化反应及结晶的影响规律。     

纳米级碳酸钙的生产、应用和开发前景

介绍了纳米级碳酸钙的4种生产方法:多段喷雾碳化法、一步碳化法、二步碳化法和旋转填充床碳化器碳化法。阐述了纳米级碳酸钙在橡胶、塑料制品、造纸、涂料、油墨等方面的应用情况及其开发前景。     

轻质碳酸钙碳化新工艺

提出了喷射碳化新工艺，介绍了设备流程、原理。测定结果表明：新工艺具有投资少、能耗低、产品质量好、易于操作等特点，还对碳化过程微观机理进行了探讨。     

对小氨碱厂碳酸化的探讨

本文对如何加强小氨碱厂技术管理,改善碳化条件,优化碳化操作来提高碳化转化率、增加生产效益作了一些探讨。     

炭材料中孔控制技术

综合评述了国内外炭材料中孔控制方面的发展情况，总结提出了炭材料的几种中孔控制技术，经活化法，共混聚合物碳化法，有机凝胶碳化法和模板碳化法。     

Magnesium Hydroxide Dehydroxylation/Carbonation Reaction Processes: Implications for Carbon Dioxide Mineral Sequestration

Gas-phase magnesium hydroxide carbonation processes were investigated at high CO₂ pressures to better understand the reaction mechanisms involved. Carbon and hydrogen elemental analysis, secondary ion mass spectrometry, ion beam analysis, X-ray diffraction, and thermogravimetric analysis were used to follow dehydroxylation/rehydroxylation/carbonation reaction processes. Dehydroxylation is found to generally precede carbonation as a distinct but interrelated process. Above the minimum CO₂ pressure for brucite carbonation, both carbonation and dehydroxylation reactivity decrease with increasing CO₂ pressure. Low-temperature dehydroxylation before carbonation can form porous intermediate materials with enhanced carbonation reactivity at reduced (e.g., ambient) temperature and pressure. Control of dehydroxylation/rehydroxylation reactions before and/or during carbonation can substantially enhance carbonation reactivity.     

超细碳酸钙对硫铝酸盐水泥基双液注浆材料性能的影响

为了进一步改善硫铝酸盐水泥基双液注浆材料(SCGM)的力学性能和抗碳化性能,采用气-液碳化法合成了超细碳酸钙(SC),研究了SC掺量对SCGM凝结时间、水化硬化性能、抗碳化性能及微观结构的影响规律。结果表明:SC可以促进SCGM的水化,提高力学性能及抗碳化性能;当SC掺量为3%(质量分数)时,养护6 h和28 d的抗压强度分别提升29.40%和26.43%,碳化5 d后,碳化深度降低了24.12%,碳化7 d后,碳化收缩降低了19.05%。该研究结果为进一步提升SCGM的力学性能和抗碳化性能提供了新方法。     

CO2 Capture Behavior of Shell during Calcination/Carbonation Cycles

The cyclic carbonation performances of shells as CO₂ sorbents were investigated during multiple calcination/carbonation cycles. The carbonation kinetics of the shell and limestone are similar since they both exhibit a fast kinetically controlled reaction regime and a diffusion controlled reaction regime, but their carbonation rates differ between these two regions. Shell achieves the maximum carbonation conversion for carbonation at 680–700 °C. The mactra veneriformis shell and mussel shell exhibit higher carbonation conversions than limestone after several cycles at the same reaction conditions. The carbonation conversion of scallop shell is slightly higher than that of limestone after a series of cycles. The calcined shell appears more porous than calcined limestone, and possesses more pores > 230 nm, which allow large CO₂ diffusion‐carbonation reaction rates and higher conversion due to the increased surface area of the shell. The pores of the shell that are greater than 230 nm do not sinter significantly. The shell has more sodium ions than limestone, which probably leads to an improvement in the cyclic carbonation performance during the multiple calcination/carbonation cycles.     

掺合料对混凝土早期碳化深度影响的试验研究

通过自然暴露环境条件下掺合料混凝土的早期碳化试验,分析了粉煤灰掺量、矿渣掺量、煤矸石掺量对单掺混凝土碳化深度的影响规律,探讨了双掺掺合料对混凝土碳化深度发展规律的交互作用,并基于试验数据建立了掺合料碳化速度影响系数的表达式。结果表明：单掺粉煤灰掺量小于15%时混凝土的碳化深度略有减小但掺量超过15%后碳化深度随粉煤灰掺量的增加而增加,单掺矿渣混凝土的碳化深度随矿渣掺量的增加而增加,单掺小于20%的煤矸石使混凝土早期抗碳化性能提高但掺入超过30%的煤矸石后混凝土碳化深度明显增加;随着粉煤灰掺量的增加,双掺粉煤灰和矿渣、双掺粉煤灰和煤矸石的混凝土碳化深度增加,在粉煤灰混凝土中掺入25%矿渣或20%煤矸石后混凝土的碳化深度变化较小;在煤矸石混凝土中掺入25%~40%的矿渣时混凝土的碳化深度无明显变化但再掺入超过40%的矿渣时碳化深度明显增大,在矿渣混凝土中掺入20%煤矸石后混凝土的碳化深度增长约40%。     

再生混凝土抗碳化性能试验研究

通过9种不同再生粗骨料、再生细骨料取代率下再生混凝土快速碳化试验,系统研究了再生骨料类型及其取代率对再生混凝土抗碳化性能的影响规律.基于试验,分析了分别经受3d、7d、14d和28d碳化试验后再生混凝土碳化深度和立方体抗压强度变化率;提出了再生混凝土28 d碳化深度预测模型;研究了28 d碳化作用后不同取代率下钢筋再生混凝土抗压承载力.试验结果表明,碳化作用导致混凝土立方体抗压强度升高,且提高幅度随再生骨料取代率的增加而增大;再生混凝土抗碳化性能与普通混凝土相比有所降低,各阶段碳化深度较大,且发展较快;再生骨料的掺入对混凝土碳化后抗压承载力具有不利影响;基于本文提出的再生混凝土碳化深度预测值与试验结果符合较好.     

Effects of Steam Addition during Calcination on Carbonation Behavior in a Calcination/Carbonation Loop

The effects of steam addition during calcination on the carbonation behavior of calcium‐based sorbents in cyclic calcination/carbonation experiments were investigated. Variations in the CaO conversion rate during carbonation were measured to evaluate the influence of operating conditions and particle size on the carbonation reaction in kinetic‐ and diffusion‐controlled reaction regimes. Surface sintering and particle aggregation during cyclic calcination/carbonation affected the sorbent surface area, pore volume, and possibly the pore size, resulting in less sorbent recyclability and a trigger time retard in the fast kinetic‐controlled carbonation. Steam addition during calcination positively affected the recyclability of the sorbents and altered the carbonation behavior.     

弯曲荷载下喷射混凝土衬砌碳化耐久性研究

以一般大气环境长大喷射混凝土单层永久衬砌隧道为背景,开展弯曲荷载作用下喷射混凝土衬砌碳化耐久性试验.采用改进的四点弯曲法,对应力比为0、0.25、0.50和0.75的混凝土试件进行快速碳化试验,并对无荷载混凝土试件的抗压强度、劈裂抗拉强度及抗折强度进行测试.以张誉碳化模型为基础,对其碳化系数进行修正,建立考虑应力比、受力方式、钢纤维和成型方式的喷射混凝土碳化深度预测模型.结果表明:喷射混凝土碳化深度符合Fick第一定律,碳化系数与受力方式和应力比、钢纤维及成型方式有关.喷射混凝土碳化耐久性优于模筑混凝土,钢纤维可进一步提升喷射混凝土碳化耐久性.碳化混凝土相对抗压强度和相对劈裂抗拉强度随碳化深度增大而增大,相对劈裂抗拉强度与碳化深度呈指数关系.通过将模型预测值与试验值进行对比,其平均偏差小于10%,标准差为0.07,对弯曲荷载喷射混凝土碳化深度的预测具有较好的适用性.     

鼓泡床中电石渣加速碳酸化分析与响应面优化

搭建了鼓泡床碳酸化反应器,研究常温常压下电石渣直接液相碳酸化矿化封存CO₂的能力,揭示了重要操作参数表观气速、液固比和CO₂浓度对电石渣矿化封存CO₂能力和碳酸化效率的影响规律。同时构建响应面模型,分析各参数对电石渣碳酸化效率的影响强度,优化获得最大碳酸化效率及相应操作工况。结果表明,增加气速有利于钙离子溶解和CO₂吸收,但反应器中过高气速易导致气相通道效应,不利于气液充分接触。当液固比降低,溶液中钙离子浓度提高,更有利于碳酸化反应,但液固比过低会影响固液间传质。适当增加CO₂浓度有利于提高碳酸化效率,但CO₂浓度增至到一定值后,对碳酸化效率影响降低。响应面建模分析发现,各因素对碳酸化效率影响顺序为：液固比>CO₂浓度>表观气速。优化结果发现碳酸化效率最高为93.58%,工况为表观气速0.07m/s,液固比为8.26mL/g和CO₂体积分数为20.91%。研究可知,鼓泡床中常温常压下电石渣直接液相加速碳酸化反应,具有较大的CO₂固定量和高的碳酸化效率,实验结果为电石渣加速矿化封存CO₂技术的发展提供了基础数据。     

废弃纤维再生混凝土孔结构及碳化性能分形特征研究

以水灰比、再生骨料取代率、废弃纤维长度和体积掺量为设计变量,利用压汞试验及快速碳化试验,探讨了废弃纤维再生混凝土的孔结构、碳化性能的分形特征以及两者之间的关系.结果表明:废弃纤维再生混凝土孔结构具有显著的分形特征,废弃纤维的加入可阻止结构中有害孔的形成,改善废弃纤维再生混凝土内部的孔结构;纤维的加入可以提高再生混凝土的碳化性能,最优体积掺量为0.12%,碳化边界轮廓线的分形维数越小,对应的碳化深度越大;废弃纤维再生混凝土的碳化深度与孔隙体积分形维数之间存在相关性,随着孔体积分形维数减小碳化深度增大,根据孔隙体积分形维数来评价不同设计变量的废弃纤维再生混凝土碳化深度是可行的.     

Competition of several carbonation reactions in concrete: A parametric study

Carbonation caused by atmospheric carbon dioxide is one of the major physicochemical processes which can compromise the service life of reinforced concrete structures. While the bulk of the carbonation reaction is that of calcium hydroxide, other constituents of the porous matrix can also carbonate and compete with calcium hydroxide for carbon dioxide. Particularly the carbonation of calcium–silicate hydrates and unhydrated constituents are neglected by most authors in carbonation prediction models. In this paper, a mathematical model of carbonation is extended to include additional carbonation and hydration reactions. The competition of the several reactions and their effect on the carbonation depth is investigated by dimensional analysis and numerical simulations. A parameter study emphasises that multiple internal reaction layers appear. Their position and speed essentially depend on the strength of the different reactions. It is also observed that, for a wide range of parameters, the effect of some of the additional reactions on the carbonation depth is small. In particular, a comparison with data from laboratory experiments justifies the neglect of the carbonation of the unhydrated constituents in prediction models.