Optimization of carbon dioxide absorption in a continuous bubble column reactor using response surface methodology

Carbon dioxide absorption using amine based solvents is a well-known approach for carbon dioxide removal. Especially with the increasing concerns about greenhouse gas emissions, there is a need for an optimization approach capable of multifactor calibration and prediction of interactions. Since conventional methods based on empirical relations are not efficiently applicable, this study investigates use of Response Surface Methodology as a strong optimization tool. A bubble column reactor was used and the effect of solvent concentration (10.0, 20.0 and 30.0 vol%), flow rate (4.0, 5.0 and 6.0 L min⁻¹), diffuser pore size (0.5, 1.0 and 1.5 mm) and temperature (20.0, 25.0 and 30.0°C) on the absorption capacity and also overall mass transfer coefficient was evaluated. The optimization results for maintaining maximum capacity and overall mass transfer coefficient revealed that different optimization targets led to different tuned operational factors. Overall mass transfer coefficient decreased to 34.7 min⁻¹ when the maximum capacity was the desired target. High reaction rate along with the highest absorption capacity was set as desirable two factor target in this application. As a result, a third scenario was designed to maximize both mass transfer coefficient and absorption capacity simultaneously. The optimized condition was achieved when a gas flow rate of 5.9 L min⁻¹, MEA solution of 29.6 vol%, diffuser pore size of 0.5 mm and temperature of 20.6°C was adjusted. At this condition, mass transfer coefficient reached a maximum of 38.4 min⁻¹, with a forecasted achievable absorption capacity of 120.5 g CO₂ per kg MEA.     

太原市“十四五”规划大气污染防治政策的CO2协同效益评估

为量化评估太原市“十四五”大气污染防治政策的减污降碳协同效益,使用京津冀温室气体-空气污染相互作用与协同模型（GAINS-JJJ）,模拟评估13项大气污染防治措施的减排潜力,CO₂的协同减排效益.2025年政策情景下一次PM_2.5、PM₁₀、SO₂、NO_x、VOCs和NH₃分别减排1.8（5%,相对于基准情景减排比例,下同）、2.5（2%）、3.7（16%）、20.0（27%）、13.6（15%）和0.0 kt（0%）,CO₂减排9.0 Mt（13%）,CH₄排放增加203.3 kt（相对于基准情景增加25%）.SO₂、NO_x与VOCs减排主要发生在电力、工业燃烧与溶剂使用部门,CO₂减排主要发生在工业燃烧部门,CH₄排放量增加是由于煤矿开采活动水平升高.限制“双高”行业的能源消耗,严禁新增产能以及可再生能源发电比例提升措施的CO₂协同减排效益最高.VOCs具有优异协同减碳效益.建议太原市进一步推进终端电气化政策,同时需加大提升电力行业清洁能源比重和可再生能源发电的消纳能力.     

Potential for Advanced Technology to Improve Air Quality and Human Health in Shanghai

/ Air quality in most Asian cities is poor and getting worse. It will soon become impossible to sustain population, economic, and industrial growth without severe deterioration of the atmospheric environment. This paper addresses the city of Shanghai, the air-quality problems it faces over the next 30 years, and the potential of advanced technology to alleviate these problems. Population, energy consumption, and emission profiles are developed for the city at 0.1 degrees x 0.1 degrees resolution and extrapolated from 1990 to 2020 using sector-specific economic growth factors. Within the context of the RAINS-Asia model, eight technology scenarios are examined for their effects on ambient concentrations of sulfur dioxide and sulfate and their emission control costs. Without new control measures, it is projected that the number of people exposed to sulfur dioxide concentrations in excess of guidelines established by the World Health Organization will rise from 650,000 in 1990 to more than 14 million in 2020. It is apparent that efforts to reduce emissions are likely to have significant health benefits, measured in terms of the cost of reducing the number of people exposed to concentrations in excess of the guidelines ($10-50 annually per person protected). Focusing efforts on the control of new coal-fired power plants and industrial facilities has the greatest benefit. However, none of the scenarios examined is alone capable of arresting the increases in emissions, concentrations, and population exposure. It is concluded that combinations of stringent scenarios in several sectors will be necessary to stabilize the situation, at a potential cost of $500 million annually by the year 2020. KEY WORDS: Coal; China; Shanghai; Sulfur dioxide; Air quality; Health effects     

应对气候变化的有效途径:二氧化碳捕集与封存

全球气候变暖问题日益严重,二氧化碳(CO2)捕集与封存(CCS)技术被看作是最有发展前景的解决该问题的技术之一。CCS技术主要包括三个环节:CO2捕集、运输和封存。本文首先介绍了CO2捕集技术,该技术按工艺主要分为燃烧前捕集、富氧燃烧捕集和燃烧后捕集。随后介绍了CO2封存技术,该技术根据封存地点不同可分为地质封存和海洋封存。在众多的CO2封存技术中,CO2强化采油(CO2-EOR)技术由于其较高的经济效益近年来得到广泛应用。虽然CCS技术发展很快,但仍存在很多问题,如CO2泄漏问题、资金投入大等。但是,随着各国政府越来越重视CCS技术的研究和开发,相信未来该技术在抵制全球气候变暖问题上会发挥重要的作用。     

中国2020年SO_2排放量控制在2070万t以下的可行性分析

根据SO2减排控制指标体系中16个指标的概况和变化趋势,对中国2020年SO2排放量做了系统地分析和预测,得到了三组预测图像。中国SO2排放量与国民生产总值（GDP）及其年均增长率、总能耗量及其年均增长率、能源经济环境发展模式（能源消费弹性系数）等12项指标成正相关,与SO2治理强度等4项指标成负相关,当各个指标控制在合理的范围内时我国2020年SO2减排目标是可以实现的。提出了2020年实现SO2减排目标的10个约束条件,如果不满足约束条件时,我国2020年SO2削减目标是不能实现的。     

以清洁生产理念促进我国钛白粉产业的发展

介绍了我国钛白粉产业的现状,阐述了钛白粉产业清洁生产的重要性,分析了影响我国钛白粉产业可持续发展的问题及原因.指出施行清洁生产对钛白粉产业加快技术进步、调整产业结构、促进产业升级具有重要意义.     

炼化企业SO2减排潜力分析

介绍了炼化企业的SO2排放源,建立了自备电厂SO2减排量数学模型,研究了SO2减排量对各影响因素的敏感度,分析了炼化企业SO2减排潜力.自备电厂燃煤锅炉SO2减排措施包括:增设脱硫设施,改进现有脱硫工艺,提高脱硫效率;关停小机组;降低燃料中硫含量.生产过程中催化裂化催化剂再生烟气的脱硫减排措施包括:降低原料硫含量;使用...     

Combined effects of titanium dioxide and humic acid on the bioaccumulation of cadmium in Zebrafish

The combined effects of titanium dioxide (TiO₂) nanoparticles and humic acid (HA) on the bioaccumulation of cadmium (Cd) in Zebrafish were investigated. Experimental data on the equilibrium Cd bioaccumulation suggest that only the dissolved Cd effectively contributed to Cd bioaccumulation in HA solutions whereas both the dissolved and TiO₂ associated Cd were accumulated in TiO₂ or the mixture of HA and TiO₂ solutions, due likely to the additional intestine uptake of the TiO₂-bound Cd. The equilibrium Cd bioaccumulation in the mixed system was comparable to that in the corresponding HA solutions, and significantly lower than that in the corresponding TiO₂ solutions (n = 3, p < 0.05). The presence of either HA or TiO₂ (5-20 mg L⁻¹) in water slightly increased the uptake rate constants of Cd bioaccumulation whereas combining HA and TiO₂ reduced the uptake rate constants.     

Analysis of Long-term Measurements of Airborne Concentrations of Sulphur Dioxide and SO42- in the Rural United Kingdom

During the last two decades, the importance of sulphur dioxide as a pollutant has moved away from its association with suspended particulate matter, to it being a precursor of SO ₄ ^2- aerosol (acidic e.g. sulphuric acid, or neutralised e.g. ammonium sulphate). Co-located concentration data of sulphur dioxide and SO ₄ ^2- , at nine monitoring sites situated in predominantly rural areas in the United Kingdom, collected over the time period 1979–1995, have been analysed. The time series for both species are discussed for the sites. Further analysis has shown that there is a degree of correlation between sulphur dioxide and SO ₄ ^2- for most of the sites considered. This correlation is of approximately the same level for most of the sites taken independently and together, and in most cases the slopes and intercepts associated with the simple empirical model equations arising from the correlation analysis, are of the same order of magnitude. The implementation of these site-dependent model equations within dispersion models for the prediction of the concentration of airborne sulphate aerosol from knowledge of sulphur dioxide concentration is discussed. Furthermore, the correlation analysis revealed the influence of transported sulphate aerosol on the local concentration, especially during high concentration episodes.     

Forty years of atmospheric radiocarbon monitoring around Bohunice nuclear power plant, Slovakia

Radiocarbon variations in the atmospheric CO(2) with attenuating amplitudes and decreasing mean values with typical maxima in summer and minima in winter have been observed since 1967 in two localities of Slovakia, in Bratislava and Zlkovce, situated about 60 km NE from Bratislava, only 5 km from the Bohunice Nuclear Power Plant (NPP). The (14)C record in Bratislava has been influenced mainly by fossil CO(2) emissions, in contrast to the Zlkovce record which has been more variable, as it has clearly been affected by operation of the Bohunice NPP. However, during specific meteorological conditions with NE transport of air masses to Bratislava, the effect of the Bohunice NPP has been visible in Bratislava as well. Maximum (14)C concentrations (up to 120% above a natural background) were observed around A1 NPP which used CO(2) with admixture of air as a cooling agent. The (14)C concentrations around four pressurized light water reactors were up to 30% above the background. The Delta(14)C values in the heavily polluted atmosphere of Bratislava were up to 10% and at Zlkovce up to 5% lower than the European clean air represented by the Jungfraujoch Delta(14)C data. Later the Delta(14)C values were similar at both sites, and from 2003 they were close to the European clean air levels. The observed Delta(14)C behaviour in the atmosphere provides a unique evidence of decreased fossil fuel CO(2) emissions in the region, as well as the long-term effect of the Bohunice NPP on the Bratislava and Zlkovce stations. The estimated annual radiation doses to the local public due to digestion of radiocarbon contaminated food have been estimated to be around 3 microSv.