钙基吸收剂循环吸收CO2特性的研究进展

采用钙基吸收剂循环吸收CO2是目前理论比较成熟,前景比较好的零排放技术。通过对钙基吸收剂吸收CO2现状技术和改善其吸收特性方法的总结,探讨了钙基吸收剂的选择、吸收CO2的效率、循环吸收效率下降的原因和循环流化床吸收CO2系统,为CO2的捕集和吸收提供了有益参考,同时提出了以后研究需要改进的内容,为后期的实验研究指明了方向。     

O2/CO2气氛添加CaCO3对徐州烟煤PM2.5排放的影响

采用管式炉研究了在O2/CO2气氛下添加CaCO3对PM2.5(空气动力学直径小于2.5,μm的颗粒物)排放特性的影响.试验采用荷电低压撞击器(ELPI)采集和分析燃烧后的PM2.5.结果表明,添加CaCO3是燃烧过程中影响PM2.5生成的重要因素.添加CaCO3后,生成PM1的数密度和质量浓度均降低,而PM1-2.5的数密度和质量浓度均略有增加,PM2.5粒径分布均呈双峰分布,峰值点分别出现在0.2,μm和2.0,μm左右.随着CaCO3添加质量分数的增加,PM2.5中的S、Pb、Cu、Na和K几种元素的浓度呈下降趋势.     

神华煤粉在CO2和N2高温气氛下SOx生成释放规律的研究

通过在固定反应床实验系统上,进行了不同燃烧气氛、不同氧气体积浓度、不同燃烧环境温度及不同颗粒粒径下神华煤粉的燃烧实验,在实验过程中对气体污染物SOx生成释放规律进行了研究。发现了CO2气氛下SOx呈现双峰现象,即在煤粉燃烧过程中,S元素转化成SOx的过程分为挥发分释放阶段和焦炭燃烧阶段。SOx释放过程中第一个峰的积分值占总积分值的百分比随着燃烧环境温度的升高而降低,即在较高的燃烧环境温度下SOx主要来源于无机硫化合物。在煤粉燃烧过程中,SOx生成释放曲线的2个峰值随着氧气浓度的升高而增加,SOx总生成量也略为增加;单位氧气消耗量生成的SOx(记为YSOx)随着燃烧环境温度的升高而升高;煤粉颗粒粒径对YSOx的影响规律不明显。高温1 600℃下,煤粉自固硫特性的作用下SOx的生成量与1 000℃时相当。     

O2/CO2/H2O气氛下CO燃烧机理的分子动力学模拟研究

采用反应分子动力学(ReaxFF MD)模拟方法研究了O₂/CO₂/H₂O气氛下CO的燃烧。结果表明：根据化学平衡原理,高浓度CO₂抑制CO的氧化,同时CO₂在高温下参与反应CO₂+H—→CO+OH,进一步抑制CO氧化。在较低温度条件下,较高浓度H₂O的三体效应显著,抑制了CO氧化。另一方面,在较高温度条件下,H₂O参与的H₂O+H—→H₂+OH和H₂O+O—→OH+OH反应占据其化学作用的主导地位,进而促进CO氧化。随着O₂浓度的增加,CO的氧化速度加快。     

H2O和SO2对钙循环捕集CO2碳酸化过程协同效应的研究

采用自制恒温热重系统研究了H₂O和SO₂对钙循环捕集CO₂的协同效应,并结合吸收剂的孔径进行了机理分析。结果表明：气氛中的H₂O加速了碳酸化快速反应阶段的反应速度,改善了CaO颗粒的孔结构,从而提高了碳酸化转化率;气氛中的SO₂阻碍了CO₂的捕集,使碳酸化转化率下降,且随循环进行碳酸化转化率下降更加明显;当H₂O和SO₂协同作用于碳酸化过程时,钙循环特性受H₂O和SO₂的协同效应影响：加入0.05%体积分数的SO₂后,当H₂O体积分数从0%增加至20%时,吸收剂孔容积逐步上升,CO₂捕集能力得到改善;加入10%体积分数的H₂O后,当SO₂体积分数从0%增加至0.1%时,吸收剂孔隙堵塞更加严重,CO₂捕集能力下降,但是相较于无H_2<...     

O2/CO2气氛下石灰石脱硫特性的研究

在沉降炉中进行了石灰石的脱硫特性研究.表明用20%O2+80%CO2的混合气体作助燃气时比用空气作助燃气时有较好的脱硫效果,并能减少NOx的排放,是一种新的能同时控制CO2,SO2和NOx三种污染物的好方法.图8参8     

空气与O2+CO2气氛下钙基脱硫剂固硫规律的实验研究

对合山烟煤在空气及O     

高压O2/CO2气氛下煤焦理论计算研究

研究表明在6MPa压力,富氧浓度为30%的条件下的增压富氧燃烧的经济性可以达到最佳。在此气氛下用一个简单的燃烧模型对碳球燃烧的情况进行理论计算,与空气气氛下的燃烧情况作对比,得到增压富氧燃烧在煤粉的燃烧时间和对烟气捕集回收二氧化碳上的优越性。从而为增压富氧燃烧的进一步发展提供理论基础。     

钙基吸附剂固定床吸附烟气中Hg~0的试验研究

在小型模拟燃煤烟气Hg吸附和形态转化试验台上研究了几种钙基吸附剂对模拟烟气中Hg的脱除效果。结果表明:Ca(OH2)对单质汞的吸附主要是物理吸附;CaO对单质汞的吸附则是物理吸附和化学吸附共同作用的结果;SO2和HCl可以通过与钙基吸附剂发生反应提供活性位或者将Hg0氧化成Hg2+来促进对汞的吸附,HCl对汞的促进作用更强;加入高锰酸钾浸渍煅烧改性后,由于化学吸附的发生,钙基类物质的吸附能力有所提高。     

煅烧参数对钙基CO2吸收剂反应特性的影响

利用能实现等温测量的热重实验台,探讨了煅烧气氛中CO2浓度对石灰石煅烧、再碳酸化以及水蒸气对循环特性的影响。结果表明,随着煅烧气氛中CO2浓度的增加,石灰石完全分解的时间逐渐延长,但在80%浓度以下,其煅烧、碳酸化动力学特性相差不多。循环过程中,水蒸气可以提高吸收剂的活性,煅烧阶段水蒸气可以增加石灰石的分解速率,碳酸化阶段水蒸气可以提高碳酸化反应速率及CO2吸收能力。     

钙基脱硫剂高温分解特性模拟研究

以反应动力学为基础,考虑CO2在产物层中的扩散影响、分解过程中CaO的高温烧结作用及CO2的烧结影响。模拟研究钙基脱硫剂石灰石(CaCO2)在不同的反应温度、气氛及颗粒粒径下的分解特性及生成CaO的比表面积变化情况。     

单位电量CO_2排放强度与单位产值CO_2排放强度关系初探

电力单位产值CO2排放强度是全国单位产值CO2排放强度的重要组成部分,其既与电力行业排放绩效即单位发电量CO2排放强度有关,也与全社会能源效率、电气化水平、资源与市场情况等因素相关。本文系统分析了有关指标的统计特征、国际对比、影响因素及趋势预测,指出"十二五"及"十三五"期间,不论是单位电量CO2排放强度,还是电力单位产值CO2排放强度,其下降幅度都是有限的,需要理性看待并科学设置规划指标。     

Metal-organic frameworks for CO2 photoreduction

Metal-organic frameworks (MOFs) have attracted much attention because of their large surface areas, tunable structures, and potential applications in many areas. In recent years, MOFs have shown much promise in CO₂ photoreduction. This review summarized recent research progresses in MOF-based photocatalysts for photocatalytic reduction of CO₂. Besides, it discussed strategies in rational design of MOF-based photocatalysts (functionalized pristine MOFs, MOF-photosensitizer, MOF-semiconductor, MOF-metal, and MOF-carbon materials composites) with enhanced performance on CO₂ reduction. Moreover, it explored challenges and outlook on using MOF-based photocatalysts for CO₂ reduction.     

The impact of CHP generation on CO2 emissions

The combined generation of heat and power (cogeneration) is praised by many as a technique for reducing the emissions of CO₂ in industrialized nations. This is generally true but not always. In this article we discuss the impact of some major variables on the CO₂ emission reduction capacity of cogeneration. Two sets of variables are predominant: the characteristics of the CHP process and the composition of the electricity generation sector. We highlight the interaction between the two sets of variables with the help of diagrams.     

Energy demand and CO2 emissions reduction options in Nigeria

This paper presents policy options for reducing CO₂ emissions in Nigeria. The policies were formulated based on a thorough analysis of Nigeria's current energy consumption patterns and the projected evolution of key parameters that drive Nigeria's energy demand — primarily the rate of industrialization, the demand for transportation services, and the expansion of Nigeria's population. The study shows that the most promising options for reducing CO₂ emissions in Nigeria are improving energy efficiency and increasing the use of natural gas and renewable energy sources.     

高浓度CO2下CaCO3循环煅烧试验与模拟

建立了高浓度CO2气氛下CaCO3循环煅烧过程数学模型,利用钙基吸收剂多次循环煅烧试验对模型进行了验证,在此基础上分析了CO2浓度、吸收剂种类、粒径和循环次数等参数对CaCO3煅烧的影响。结果表明:CaCO3分解温度随气相中CO2含量的增加而增大;在高浓度CO2下,随循环反应次数的增加,吸收剂循环反应活性下降,使得所生成的CaCO3质量也随循环次数的增加而减少,致使CaCO3煅烧完全所需时间会随循环反应次数的增加而减少。     

Pilot scale autothermal gasification of coconut shell with CO2-O2 mixture

This paper explored the feasibility and benefit of CO₂ utilization as gasifying agent in the autothermal gasification process. The effects of CO₂ injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO₂/C ratio from 0.6 to 1.6. O₂ was injected at an equivalence ratio of approximately 0.33–0.38 for supplying heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO₂ injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO₂-O₂ gasification with a CO₂/C ratio of 0.6–1.2. The progress of the expected CO₂ to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO₂/C ratio increased. The producer gas heating value of CO₂-O₂ gasification was consistently higher than that of air gasification. These results show the potential of CO₂-O₂ gasification for producing high quality producer gas in an efficient manner, and the necessity for more work to deeply imply the observation.     

CO2 methanation combined with NH3 decomposition by in situ H2 separation using a Pd membrane reactor

Combination of the reactions by means of membrane separation techniques are of interest. The CO₂ methanation was combined with NH₃ decomposition by in situ H₂ separation through a Pd membrane. The CO₂ methanation reaction in the permeate side was found to significantly enhance the H₂ removal rate of Pd membrane compared to the use of sweep gas. The reaction rate of CO₂ methanation was not influenced by H₂ supply through the Pd membrane in contrast to NH₃ decomposition in the retentate side. However, the CH₄ selectivity could be improved by using a membrane separation technique. This would be caused by the active dissociated H species which might immediately react with adsorbed CO species on the catalysts to CH₄ before those CO species desorbed. From the reactor configuration tests, the countercurrent mode showed higher H₂ removal rate in the combined reaction at 673 K compared to the cocurrent mode but the reaction rate in CO₂ methanation should be improved to maximize the perfomance of membrane reactor.