制氢弛放气中CO2胺法捕集工艺模拟及优化

为降低PSA制氢装置弛放气中CO2捕集系统蒸汽消耗量,利用Aspen Hysys软件建立了CO2捕集工艺模型并对捕集工艺进行模拟研究。考察了胺液循环量、解吸系统贫胺液CO2负载量、富胺液进解吸塔温度和解吸压力对蒸汽消耗量的影响。模拟结果表明,随着胺液循环量和解吸系统贫胺液CO2负载量的增大,CO2解吸单耗先降低后升高,最低约为2.04t水蒸气/tCO2。提高富胺液进解吸塔温度或提高解吸压力均有利于降低CO2解吸单耗。     

焦炉煤气CO2吸收增强法制氢的操作条件分析

对焦炉煤气CO2吸收增强法制氢工艺,根据对合成气氢气摩尔分数、CO2摩尔分数、氢气产率及反应器热平衡的要求,确定了制氢反应器制氢温度、制氢压力、水碳比、钙碳比等参数取值范围。在制氢反应器性能模拟基础上,分析了合成气制备、吸收剂再生、合成气分离、热功转化单元的物质能量关联,得到制氢操作条件对焦炉煤气能量转化效率的影响。当制氢压力取2.5MPa、制氢温度取985K、钙碳比≥0.8、水碳比≥4.1时,焦炉煤气能量转化效率可达78%。     

水泥企业碳捕集方案技术及经济性分析

该文通过在某水泥企业采用化学吸收技术对CO2进行捕获,并采用增量成本界定原则,核算水泥厂在进行碳捕集系统改造及运行过程中所增加的所有成本,以此分析碳捕集技术在水泥行业的可行性。     

低浓度CO_2捕集技术的现状与进展

从胺化合物吸收法、膜吸收法、金属氧化物吸收法三方面,介绍了低浓度CO_2捕集的主流方法,分析比较了各种方法的反应原理及优缺点,提出了低浓度CO_2捕集技术的发展方向。     

我国煤基电厂CO2捕集技术发展的探讨

介绍煤基电厂CO2排放的特征,并从燃烧前、燃烧后和富氧燃烧三个方面介绍了CO2捕集技术的特点。通过分析国内外煤基电厂CO2捕集技术的发展现状,提出我国煤基电厂CO2捕集的主要问题,指出适合中国国情的电厂CO2捕集发展方向。最后对我国全面开展煤基电厂CO2捕集技术基础研究和工业研究提出建议。     

建筑材料全寿命期CO2 排放量计算方法

建筑材料CO2 减排是我国整体CO2 减量计划的重要方面,建筑材料CO2 排放量的计算是发展低碳建材、推进建筑节能减排的前提和基础,为此需要确立建筑材料CO2 排放量的计算方法。通过CO2 排放活动分析,从全寿命期和CO2 排放源角度,确定了建筑材料CO2 排放构成;并对六种建筑材料CO2 排放量的计算方法进行了比较分析,选择碳排放系数法作为计算我国建筑材料CO2 排放量的方法;构建了建筑材料全寿命期CO2 排放三阶段计算模型,并提出了建筑材料生产、运输以及处置阶段CO2 排放因子的确定方法。应用实例显示,该方法可较方便地测算出建筑材料全寿命期CO2 排放量。     

生物炭混凝土生命周期CO2排放评价

为评价生物炭混凝土的CO₂排放量,采用生命周期评价技术构建了生物质热解生产生物炭过程的碳排放计算模型、生物炭混凝土从原材料生产到混凝土拆除废弃阶段CO₂排放量化模型和生物炭混凝土服役期碳化-吸收模型,同时研究了生物炭按质量比例取代水泥对混凝土力学性能的影响。在此基础上,计算了1 m³C30生物炭混凝土的CO₂排放量,并与普通C30混凝土CO₂排放量进行对比。结果表明:生物炭作为一种碳负性材料,其碳元素含量越高,CO₂减排效果越好; 当生物炭取代率小于5.0%时,研磨后的超细炭颗粒可以充分发挥填充和内固化效应,有效地提高混凝土的力学性能; 生物炭混凝土生命周期CO₂排放量随生物炭取代率的提高而降低,5%取代率的1 m³木屑生物炭混凝土相比普通C30混凝土,可减排CO₂66.5 kg,减排率为20.7%; 生物炭混凝土在服役期内因碳化吸收CO₂占总碳排放量的1.8%～2.5%,而拆除废弃阶段由于混凝土的比表面积呈指数增长,碳化吸收量需要进一步研究。     

CO2碳化矿渣-CaO-MgO加固土效能与机理探索

CO₂碳化联合工业固废协同加固土技术是旨在替代传统水泥固化方法的新型技术尝试。以工业废料——矿渣为主要材料,辅以活性MgO和CaO形成矿渣-CaO-MgO固化体系,将固化土料均匀搅拌制样后进行CO₂碳化试验。通过无侧限抗压强度、扫描电镜和X射线衍射等试验,探究固化剂掺量、配比、碳化时间和初始含水率等因素对碳化加固土效果的影响。结果表明：CO₂碳化对土体加固具有明显改良效果,碳化24 h试样抗压强度最高可提升25.77倍;碳化试样抗压强度与固化剂掺量（6S4L0M除外）、活性MgO占比呈正相关;碳化试样强度随碳化时间先增加后趋于平缓（或略微下降）、最佳碳化时间为6 h左右,随初始含水率增加而先增加后下降、最佳含水率为16%左右;活性MgO碳化效能明显优于活性CaO,矿渣中低活性CaO并不能显著改良自身碳化性能。CO₂碳化作用促使碳酸盐晶体（CaCO₃、MgCO₃）生成,晶体发育程度与碳化时间、固化剂掺量及活性等因素有关;碳酸盐晶体有效填充试样内部孔隙并黏结土颗粒,形成整体骨架结构使试样强度得以大幅提升。     

水泥项目的CO2减排理念和相应措施

在当今工业CO2减排任务中,水泥行业首当其冲,本文对中材建设有限公司总承包的三个项目最终数据分析,计算出CO2在各环节中的排放比例,结合当初项目的设计理念,提出减排的具体措施和途径。     

全球气候变化与CO2减排方案的探讨

指出以CO2为主的温室气体是全球气候变化的最主要的驱动因素,就影响CO2排放量的入口、人均GDP、单位耗能量和能源含碳量以及碳汇量等进行CO2减排方案的探讨,并认为油田、煤气层和深部含水层等地质处置方法能够有效增加CO2的碳汇量,降低CO2的人为排放量,是当前最有潜力的CO2减排途径。     

Capture of CO2 from flue gas via multiwalled carbon nanotubes

Carbon nanotubes (CNTs) were modified by 3-aminopropyl-triethoxysilane (APTS) solution and were tested for its CO₂ adsorption potential at multiple temperatures (20-100 °C). The physicochemical properties of CNTs were changed after the modification, which makes CNTs adsorb more CO₂ gases. The adsorption capacities of CO₂ via CNTs and CNTs(APTS) decreased with temperature indicating the exothermic nature of adsorption process and increased with water content in air at 0-7%. The mechanism of CO₂ adsorption on CNTs and CNTs(APTS) appears mainly attributable to physical force regardless of temperature change, which makes regeneration of spent CNTs at a relatively low temperature become feasible. The CNTs(APTS) have good adsorption performance of CO₂ at 20 °C as compared to many types of modified carbon or silica adsorbents documented in the literature. This suggests that the CNTs(APTS) are promising low-temperature adsorbents for CO₂ capture from flue gas.     

CO2 加氢合成甲醇催化剂的研究进展

CO_2加氢合成甲醇的运用是在现代社会中对CO_2循环利用的重要方式之一。也同样是对环境保护的重要要求。无论是在CO_2的合成反映之中,还是在新型的催化剂的研制过程之中。在环境保护的过程之中,全球变暖的问题的存在,是急需面对的一个重要问题。所以,对CO_2加氢合成甲醇催化剂的研究非常重要。     

Monitoring off-gas O2/CO2 to predict nitrification performance in activated sludge processes

Nitrification/denitrification (NDN) processes are the most widely used technique to remove nitrogenous pollutants from municipal wastewater. The performance of nitrogen removal in the NDN process depends on the metabolism of nitrifying bacteria, and is dependent on adequate oxygen supply. Off-gas testing is a convenient and popular method for measuring oxygen transfer efficiency (OTE) under process conditions and can be performed in real-time. Since carbon dioxide is produced by carbonaceous oxidizing organism and not by nitrifiers, it should be possible to use the off-gas carbon dioxide mole fraction to estimate nitrification performance independently of the oxygen uptake rate (OUR) or OTE. This paper used off-gas data with a dynamic model to estimate nitrifying efficiency for various activated sludge process conditions. The relationship among nitrification, oxygen transfer, carbon dioxide production, and pH change was investigated. Experimental results of an online off-gas monitoring for a full-scale treatment plant were used to validate the model. The results showed measurable differences in OUR and carbon dioxide transfer rate (CTR) and the simulations successfully predicted the effluent ammonia by using the measured CO₂ and O₂ contents in off-gas as input signal. Carbon dioxide in the off-gas could be a useful technique to control aeration and to monitor nitrification rate.     

CO2 transport by urban plumes in the upper Spanish plateau

CO₂ transport from two cities, Valladolid, over 20 km away and Palencia, over 40 km away from a rural site is analysed through three years of detrended CO₂ concentrations obtained near the surface. Meteorological data were obtained from a RASS sodar. Directional analysis by histogram of concentrations above the 95th percentile revealed three differing sectors, one associated to a rural origin and two linked to both cities. Modes indicated anticyclonic turning during plume travel, confirmed by the daily evolution of the wind direction. At night, the Valladolid concentration median was 6 ppm above the Palencia median, which was 2 ppm higher than the rural sector median. Monthly evolution of daily maxima evidenced the Valladolid plume influence in spring and September, whereas the Palencia plume was noticeable in October and November. Skewness analysis showed almost symmetric distributions in the Valladolid plume and right skewed distributions in the Palencia and rural sectors. This result was attributed to the different mixing of both plumes. Vertical gradients of wind speed, direction and potential temperature were also calculated, and evidenced a stratified structure of the lower atmosphere at night and an almost uniform layer during the day. Finally, the median gradient Richardson number showed the highest values, occasionally above 0.8 for the Valladolid sector, implying lower mixing with the environment in the Valladolid plume than in the Palencia plume.     

Driving CO2 reduction by Integrating Transport and Urban Design strategies

Can the climate problem be framed as an urban development and transport problem where CO₂ reduction is understood as a co-benefit of good development and transport?The third largest source of greenhouse emissions in Australia is transport, and road transport accounts for 88% of transport emissions. A move towards sustainable urbanism, matched with the use of sustainable technologies (vehicle and fuels), is critical to arrest the increased dependence on fossil fuels and the escalating air-pollution at both the local and global scales. An approach towards sustainable urbanism, besides requiring a strong emphasis on land use and transport integration, demands the attainment of a certain level of urbanity through place-making. The DDD of sustainable urbanism (density, diversity, and design) forwarded by Cervero, when combined with Schipper’s ASIF identity to estimate the components of travel that yield emissions (Schipper, Marie,& Gorham, 2000) and the more recent ASIF2 paradigm (avoid, shift, improve and finance) (Dalkmann & Brannigan, 2007) to address changes in these components that reduce emissions, provide a coherent framework for the development of a sustainable green town: Bentley Technology Precinct, located in the car-oriented city of Perth. The success of the outcome is measured by undertaking an audit for place-making, VKT and CO₂ reductions. Findings are presented from the Master Class on ‘Cities - Green or Red? Transport and Urban Design in the context of climate change’, held at Perth in August 2009.     

Uncertainties associated with global effects of atmospheric CO2

Although the evidence is quite clear that the increase in atmospheric CO₂ is at least to a large degree a result of fossil fuel burning, and it is equally clear that this increase will result in some change in the global climate, there are quantitative uncertainties that require additional understanding before full assessments can be made. There are quantitative uncertainties in the natural carbon cycle as well as uncertainties in the behaviour of the various reservoirs when perturbed by man. There are questions about the terrestrial biosphere and about the rate at which the oceans can assimilate and store carbon.There are uncertainties in regard to the climate change that can result from increased atmospheric CO₂. Progress in modelling the atmosphere must continue to narrow these uncertainties before the impacts of climate change on man can be adequately determined.The future demands for fossil fuels are uncertain. The growth of the developing world will be closely linked to fossil energy for the next five to eight decades, and rates of growth in these world segments are dependent on many ill-defined quantities.Only the observed increase in the atmospheric concentration and the present (and recent past) rate of production of CO₂ from fossil fuels provide data without uncertainties.     

Effect of green roof on ambient CO2 concentration

Plants can improve air quality by removing pollutants. The air purification capability of plants has been receiving increasing attention because of the rapid deterioration of the environment. However, research on evaluating quantitatively the effect of plants on the environmental pollutant concentrations is still scarce. This paper studies the effect of a green roof on the ambient CO₂ concentration as an example to assess the benefit of urban greening. The study comprises three parts: (1) Field measurement of the difference of CO₂ concentration at a location in the middle of the plants in a small plot of green roof and one in the surrounding area, (2) Experiments to measure the plant’s CO₂ absorption velocity and emission rate using a sealed glass chamber; and (3) Computer simulation of the CO₂ concentration distribution around a green roof using the measured CO₂ absorption velocity and emission rate to quantify the effects of the green roof on the ambient CO₂ concentration.     

CO2跨临界水—水热泵循环系统的实验研究

在作者设计和建立的实验台上进行了CO2跨临界水-水热泵多种工况的循环性能实验研究,系统运行稳定、调节方便,实验结果表明,系统运行时的最大制冷（热）系数取决于系统的蒸发温度和气体冷却器出口温度,CO2跨临界循环热泵较之传统工质热泵具有较大优势,尤其是在高温热泵领域,指出了系统的改善措施。     

Prediction on CO2 uptake of recycled aggregate concrete

Carbonation of concrete is a process which absorbs carbon dioxide (CO₂). Recycled aggregate concrete (RAC) may own greater potential in CO₂ uptake due to the faster carbonation rate than natural aggregate concrete (NAC). A quantitative model was employed to predict the CO₂ uptake of RAC in this study. The carbonation of RAC and the specific surface area of recycled coarse aggregates (RCAs) were tested to verify accuracy of the quantitative model. Based on the verified model, results show that the CO₂ uptake capacity increases with the increase of RCA replacement percentage. The CO₂ uptake amount of 1 m³ C30 RAC within 50 years is 10.6, 13.8, 17.2, and 22.4 kg when the RCA replacement percentage is 30%, 50%, 70%, and 100%, respectively. The CO₂ uptake by RCAs is remarkable and reaches 35.8%–64.3% of the total CO₂ uptake by RAC when the RCA storage time being 30 days. Considering the fact that the amount of old hardened cement paste in RCAs is limited, there is an upper limit for the CO₂ uptake of RCAs.