新型相变有机胺吸收捕集CO2技术研究进展

CO₂捕集、利用与封存(CCUS)技术是实现碳减排的关键技术之一,有机胺吸收技术是目前研究最广泛、最成熟的CO₂捕集技术,已有少数工业应用案例。吸收剂是吸收技术的核心,吸收剂的研发创新是该领域的热点方向。相比于单一相的有机胺吸收剂,相变吸收剂在吸收CO₂后产生相变行为,仅需对富相进行再生,可大幅减少再生体积,降低再生能耗。本文介绍了传统混合胺相变吸收体系的典型工艺、吸收机理和吸收剂研究进展,分析了吸收剂吸收CO₂后富相黏度高、富相体积占比大及其导致的再生能耗增加的问题。本文系统梳理了为解决上述问题而研发的四种新型的相变吸收体系,分别为空间位阻胺混合型相变吸收剂、物理溶剂混合型相变吸收剂、醇胺混合型相变吸收剂、催化剂-有机胺复合型相变吸收剂,对各类新型相变吸收体系的设计构建原理及性能强化机制进行了分析。最后,基于对研究进展的深入分析,提出了相变吸收剂的未来研究方向。     

相变离子液体体系吸收分离CO2的研究现状及展望

全球工业化的迅速发展及人口增长使得化石燃料消耗不断增加，导致二氧化碳(CO₂)排放量逐年递增，引发全球化气候问题。醇胺吸收法目前在工业CO₂捕集应用最广泛，主要以单乙醇胺、甲基二乙醇胺等水溶液为吸收剂，存在溶剂损耗大、再生能耗高等问题，开发高效低能耗的新型吸收剂是实现CO₂大规模捕集的关键。离子液体具有气体亲和性好、蒸气压低、结构性质可调等特点，其中相变离子液体体系因节能潜力大被认为是新一代CO₂吸收剂，其吸收CO₂后由均相变为互不相溶的液-液或液-固两相，再生时仅需对CO₂富相加热处理，可有效减少吸收剂再生体积，降低再生能耗。重点总结近五年相变离子液体体系在CO₂分离的研究现状和进展，对不同相变行为的液-液和液-固相变离子液体体系分类阐述和讨论，并对其发展趋势进行展望。     

Aspen Plus模拟高浓度H2S/CO2酸性气的选择性分离

以煤制氢尾气中的高浓度酸性气体H₂S和CO₂为对象,以聚乙二醇二甲醚（NHD）为吸收剂,使用PC-SAFT状态方程拟合了酸性气体CO₂和H₂S在聚乙二醇二甲醚（NHD）溶剂中溶解参数,运用Aspen Plus流程模拟软件,构建两级吸收分离工艺,实现H₂S和CO₂的高效分离,H₂S浓度由30%提升至98.7%,CO₂含量由55%提升至99.4%。由此,可以通过高效分离酸性气H₂S和CO₂,并以提浓后再资源化利用的方式实现酸性气的污染控制。     

相变吸收捕集烟气中CO2技术的发展现状

化学吸收法作为目前最有效的CO₂捕集技术,吸收剂常用有机胺,但过高的再生能耗和成本限制了其在工业中的应用。基于传统有机胺溶剂开发出来的相变吸收剂被认为可以大幅减少解吸能耗,成为近几年研究的热点。本文详细介绍了相变吸收剂的常见类型、分相机理,并根据其具体组成进行了种类划分,对比分析了常用相变吸收剂和传统乙醇胺（MEA）吸收液的再生能耗,并指出温度、CO₂负荷以及相分离等因素对相变吸收剂的工艺流程长期运行稳定性的影响。在制备相变吸收剂的过程中,可加入活化剂来降低CO₂富液黏度,加入助溶剂来提高传质特性。本文阐述了现有相变吸收剂的挥发、降解和腐蚀等特性的研究现状。最后,结合研究现状和烟气捕集需求对相变吸收剂今后的研究方向给出了建议。     

N,N-二乙基乙醇胺(DEEA)溶液CO2吸收解吸性能的实验研究

胺法捕集回收二氧化碳工艺存在的最大缺陷是高吸收速率与低再生能耗不能共存,高效溶剂的开发是解决这一问题的有效途径之一。为筛选出吸收解吸综合性能良好的吸收剂,本文利用溶剂快速筛选实验装置对几种不同醇胺吸收剂进行了实验研究,主要从溶液吸收负载、吸收速率、解吸负载、解吸速率、循环容量及相对再生能耗等方面进行了分析比较,实验结果显示N,N-二乙基乙醇胺(DEEA)溶液表现出较好的CO₂捕获性能。此外,通过溶解度装置、填料吸收塔及再生塔分别对DEEA溶液的平衡溶解度、传质系数及再生能耗进行了实验研究与验证。实验结果表明:增加溶液浓度会降低其CO₂平衡溶解度;增加CO₂分压能增加其CO₂平衡溶解度;增大进料温度能增加溶液在填料塔中的传质系数;提高富液负载及贫液负载会降低溶液的再生能耗。因此,基于其较好的吸收解吸性能,DEEA是一种可以工业化应用的潜在吸收剂。     

酸性气体脱除装置液力发电可行性研究

酸性气体脱除装置中,吸收了H₂S与CO₂的富液甲醇压力较高,通过减压闪蒸对富液甲醇进行初步解吸净化,在此过程中全部采用减压阀直接减压送入后系统,能量白白浪费。若采用液力发电设备回收此部分能量,不仅能够节能降耗,还可以产生一定的经济效益,通过调研与论证来研究液力发电的可行性。     

胺法脱碳系统再生能耗

胺法脱碳系统最大的缺陷是再生能耗高,流程参数优化是降低再生能耗的有效途径。为了解再生操作参数对再生能耗的影响,通过再生塔实验台对醇胺吸收剂在不同再生工艺参数下的再生特性进行实验研究。实验内容包括富液CO₂担载量、富液进料温度、再沸器温度、再生压强及胺的种类因素对再生能耗及再生速率的影响,并分析了显热、潜热的变化规律。应用Aspen Plus 基于速率模型对再生过程进行了模拟研究。研究结果表明:提高富液CO₂担载量和富液进料温度能有效降低再生能耗。增大再沸器温度及再生压强反而增大再生能耗。一乙醇胺(MEA)再生能耗较高,混入甲基二乙醇胺(MDEA)能够显著降低能耗。提高富液CO₂担载量和再沸器的温度可以加快CO₂再生速率。     

离子液体-水复配吸收剂捕获CO2性能

基于绿色合成方法制备出亲水性离子液体(ILs)[NH₂-C₃mim][Br],从有效降低CO₂吸收-解吸操作成本出发,采用ILs-H₂O复配吸收剂,开展了常温加压CO₂吸收及吸收剂常温减压解吸再生实验。结果表明,比CO₂吸收量(基于复配吸收剂或离子液体组分)随复配吸收剂中ILs组分浓度而变;吸收初期,CO₂吸收速率随吸收剂配比变化显著;以CO₂高吸收率和吸收剂低成本为目标,优选出新型水基复配吸收剂(离子液体与水质量比为1.38:1)。分别以水基离子溶液、改良热钾碱液和活化复配醇胺液为吸收剂,在自行搭建的超重力场强化吸收-连续逆流接触(加热或减压)解吸再生台架实验装置上进行了CO₂捕获与吸收剂再生连续化实验。结果表明,在超重力场作用下,改良热钾碱液和活化复配醇胺液对CO₂有较好的捕获,吸收率分别在98%、96%和90%以上,3种吸收剂经加热或减压解吸再生后均可循环回用,水基离子溶液吸收剂在常温减压下解吸更具有实际可操作性。     

消除冶炼烟气还原过程的硫排放

介绍一种从含SO₂冶炼烟气中100%回收硫磺的新技术——GGO工艺。冶炼烟气通过吸收-再生法产生φ（SO₂）100%的气体,然后通过利用氢气作为还原剂的热反应器和克劳斯催化反应器生成硫磺。含有H₂S、SO₂、H₂和H₂O的尾气送入尾气反应塔,H₂S与SO₂在水溶液中继续反应;对悬浮液过滤回收硫磺。反应塔排出的主要含有H₂、未反应H₂S和SO₂的气体返回热反应器。本装置无气体排放。     

[Bmim][BF4]/MEA混合水溶液吸收CO2的吸收性能与液液分相机理

对液液两相CO₂吸收剂1-丁基-3-甲基咪唑四氟硼酸盐（[Bmim][BF₄]）/乙醇胺（MEA）混合水溶液吸收性能进行了实验测定,研究了离子液体[Bmim][BF₄]的引入对吸收性能和液液分相的影响,并通过定量碳谱核磁共振法对分相机理和各相中的物质分布进行分析。研究结果表明,一定配比的[Bmim][BF₄]/MEA混合水溶液吸收CO₂之后会出现互不相溶的液液两相,这种现象伴随着CO₂产物的富集;导致液液分相的原因是氨基甲酸盐浓度的增大;随着[Bmim][BF₄]质量分数的增大,溶液吸收速率呈现出先增大后减小的趋势;分层后H₂O主要分布在富液相,[Bmim][BF₄]主要分布在贫液相,H₂O的质量分数直接影响分层后富液相的传质性能。     

Microbial reduction of sulfur dioxide and nitric oxide

Two process concepts have been developed for a microbial contribution to the problem of flue gas desulfurization and NO_x removal. We have demonstrated that the sulfate-reducing bacterium Desulfovibrio desulfuricans can be grown in a mixed culture with fermentative heterotrophs in a medium in which glucose served as the only carbon source. Beneficial cross-feeding resulted in vigorous growth of D. desulfuricans, which used SO₂(g) as a terminal electron acceptor, with complete reduction of SO₂ to H₂S in 1–2 s of contact time. We have proposed that the concentrated SO₂ stream, obtained from regeneration of the sorbent in regenerable processes for flue gas desulfurization, could be split with two-thirds of the SO₂ reduced to H₂S by contact with a culture of sulfate-reducing bacteria. The resulting H₂S could then be combined with the remaining SO₂ and used as feed to a Claus reactor to produce elemental sulfur. However, the use of glucose as an electron donor in microbial SO₂ reducing cultures would be prohibitively expensive. Therefore, if microbial reduction of SO₂ is to be economically viable, less expensive electron donors must be found. Consequently, we have evaluated the use of municipal sewage sludge and elemental hydrogen as carbon and/or energy sources for SO₂ reducing cultures. Heat and alkali pretreated sewage sludge has been successfully used as a carbon and energy source to support SO₂ reduction in a continuous, anaerobic mixed culture containing D. desulfuricans. The culture operated for nine months with complete reduction of SO₂ and H₂S. Another sulfate-reducing bacterium, Desulfotomaculum orientis, has also been grown in batch cultures on a feed of SO₂, H₂ and CO₂. Complete reduction of SO₂ to H₂S was observed with gas-liquid contact times of 1–2 s. We have also demonstrated that the facultative anaerobe and chemoautotroph, Thiobacillus denitrificans, can be cultured anoxically in batch reactors using NO(g) as a terminal electron acceptor with reduction to elemental nitrogen. We have proposed that the concentrated stream of NO_x, as obtained from certain regenerable processes for flue gas desulfurization and NO_x removal, could be converted to elemental nitrogen for disposal by contact with a culture T. denitrificans. Two heterotrophic bacteria have also been identified which may be grown in batch cultures with succinate or heat and alkali pretreated sewage sludge as carbon and energy sources and NO as a terminal electron acceptor. These are Paracoccus denitrificans and Pseudomonas denitrificans.     

SIMULTANEOUS ABSORPTION OF H2S AND CO2 INTO A SOLUTION OF SODIUM CARBONATE

The simultaneous absorption of H₂S and CO₂ has been studied both experimentally and theoretically. A model has been developed which predicts the absorption rates of H₂S and CO₂ into a sodium carbonate solution. The absorption rates are calculated according to the two-film theory. In the liquid film, the finite rate of the CO₂ reaction was considered. Otherwise, in the liquid film as well as in the liquid bulk, equilibrium conditions for all reactions were assumed. Absorption experiments were performed on a packed column using a counter-flow strategy. In the experiments the influence of the initial carbonate concentration, the gas flow rate and the temperature on the removal efficiencies of H₂S and CO₂ and the selectivity of H₂S were investigated. It is desirable to absorb the H₂S but not the CO₂. The agreement between the absorption model and the experimental results from the absorber tower was satisfactory. The mass transfer coefficients were determined by fitting the experimental data to the model with respect to the H₂S and CO₂ content in the outgoing gas. The H₂S content was used to determine the gas side mass transfer coefficient and the CO₂ content was used to determine the liquid side mass transfer coefficient, The effective contact area of mass transfer was taken from published data. With a constant packing height, both the experiments and the model indicated that high carbonate concentration benefits the removal efficiency of H₂S. Higher gas flow rate also benefits the selectivity for H₂S. However, the removal efficiency will decrease. At higher temperatures the selectivity and the removal efficiency of H₂S decreased. Under the conditions investigated, the absorption of H₂S was essentially controlled by gas-side mass transfer and the absorption of CO₂ was controlled by liquid-side mass transfer     

ABSORPTION OF SO2 AND H2S IN SMALL-SCALE VENTURI SCRUBBERS

Small-scale venturi scrubbers having geometries of typical large-scale units were constructed from glass and were operated in a laboratory system. Carrier gas streams consisting of air or nitrogen and up to 30% (by volume) CO₂ were mixed with SO₂ or H₂S to give SO₂ or H₂S concentrations in the range of 1890-4400 ppm. These gas mixtures were then scrubbed in the Venturis using various injected liquids (plain water, NaOH solutions, NH₄OH solutions, and NaOH/NaHCO₃ solutions) at L/G ratios of 0.0004-0.0040 m³ liquid per standard (1 atm, 60°F)m³ of gas (3-30 gallons liquid per 1000 standard ft³ of gas). Absorption percentages for SO₂ and H₂S were determined as functions of the L/G ratio, initial liquid pH, and liquid composition. The effects of venturi throat length, gas velocity, and the presence of CO₂ in the gas stream were also determined.     

活性碳纤维负载型脱硫剂在矿井气体环境条件下的应用

H₂S作为煤炭开采过程中经常会出现的气体,对煤矿的生产安全造成不利影响,必须进行脱除工作。然而煤矿中还可能存在其他组分的气体,这些气体可能会一定程度上影响H₂S的脱除。本文选取活性碳纤维分别负载氢氧化钠及氧化铜,并选取两种材料的最佳负载量。之后,模拟煤矿实际条件,探讨复合脱硫剂在实际矿井气氛条件下的脱硫性能。结果表明,煤体在受热情况下会产生的多组分混合性气体,这些气体会对脱硫剂性能产生极大的影响,当煤体温度升高,其产生的CO、CO₂等气体呈指数增大,并且会产生少量的CH₄、C₂H₆、C₂H₄、C₂H₂等气体,随着这些气体生成量增大,脱硫剂脱硫性能开始下降。且在矿井气体氛条件下SO₂气体的产生受到了抑制,特别在煤气组分含量大的情况下,SO₂气体甚至晚于H₂S气体出现。此外通过测量脱硫剂失活后的表面pH,发现即便在一些气体氛围下脱硫剂的脱硫时间更短,其脱硫后产物的表面pH极为相近,说明煤体产生的酸性气体CO以及CO₂等可能也被吸附到脱硫剂的表面上生成酸性物质。     

ZSM-5催化剂与低温等离子体协同转化H2S-CO2制合成气

将H₂S和CO₂混合酸气一步转化制合成气,既实现了二者无害化处理,又生产出合成气,是一条理想的废气资源化利用新路线。由于分子结构稳定,在常规条件下因受热力学平衡限制,二者转化率极低。而在低温等离子体中,H₂S和CO₂可被激发为高活性物种来参与反应。研究了具有不同Si/Al摩尔比的ZSM-5催化剂与低温等离子体结合实现H₂S-CO₂一步高选择性制合成气,显著提高了H₂S-CO₂转化性能。考察了ZSM-5催化剂中Si/Al比和低温等离子体放电条件等对反应的影响。其中,当Si/Al比为80时表现出最优催化性能,最高H₂和CO产率分别达到56.1%和10.0%。对常规条件和低温等离子体氛围下的不同ZSM-5催化剂上CO₂、H₂S、CO、H₂等化学吸脱附行为进行了对比研究,发现低温等离子体促进了催化剂对CO₂、H₂及CO分子的吸附活化,进而明显提升了H₂S和CO₂转化。     

SIMULTANEOUS ABSORPTION OF C02 AND H2S IN SULFINOL SOLUTIONS IN A SET OF PACKED ABSORBER-STRIPPER

Simultaneous absorption of CO₂ and H₂S in a Sulfinol solution have been studied in a set of small pilot scale packed absorber-stripper. Data were presented on the effects of varying liquid circulation rate, feed gas flow rate, feed gas composition and steam pressure at bottom of stripper, on the individual gas removal %, steam stripping efficiency and overall volumetric gas-phase mass transfer coefficient for absorption. A comparison with an earlier work on absorption into 20% hot potassium carbonate solution in the same apparatus show that the influence of operating variables on the performance of the absorber-stripper unit is qualitatively similar for both types of solvents except that the steam stripping efficiency of the Sulfinol system is much more superior than the 20% hot carbonate system under similar conditions. This shows that the hybrid nature of the Sulfinol solvent gives a much better regeneration efficiency than chemical solvents in simultaneous CO₂ and H₂S removal     

锆基双金属氧化物催化剂硫中毒的研究

在工业二氧化碳加氢制甲醇过程中,硫化氢气体的引入将对该过程中使用的催化剂活性及稳定性带来负面的影响。基于此,采用微反应合成法成功制备了InZrO_x和ZnZrO_x锆基催化剂,并研究了在二氧化碳加氢反应中,硫化氢气体对锆基催化剂的结构性质及其催化性能的影响规律。结果表明,在T=573 K、p=3.0 MPa和GHSV=18 000 mL/(g_cat·h)条件下,仅通入二氧化碳/氢气反应气时,InZrO_x和ZnZrO_x催化剂的二氧化碳转化率和甲醇选择性分别为7.2%、9.3%和93%、92%。在二氧化碳/氢气原料气中通入体积分数为5×10^-3硫化氢气体时,InZrO_x和ZnZrO_x催化剂的二氧化碳转化率和甲醇选择性都降为0,这主要是因为硫化氢气体占据了氧空位,导致锆基双金属氧化物催化剂硫中毒失活。当停止通硫化氢气体时,InZrO_x和ZnZrO_x催化剂的二氧化碳转化率和甲醇选择...     

液硫脱气与克劳斯尾气处理

采用三氧化二铝或二氧化硅固体催化剂进行的最新实验室研究表明,H2Sx先在催化剂表面的碱性位分解为H2S,然后被吹扫气从液硫中驱除出去.由于H2S从气相返回液相的传质是一个有限的过程,从理论上讲,这预示着可利用克劳斯尾气作为吹扫气.试验还揭示,在涂有三氧化二铝的堇青石上,脱气期间尾气中约60％的H2S和SO2转化为元素硫.这预示着(例如)可在硫冷凝器管内衬入涂有三氧化二铝的堇青石管,以在脱气的同时提高总转化率.     

富氧燃烧烟气冷凝塔钠碱法脱硫过程SO2和CO2共吸收建模与实验研究

建立SO₂与CO₂共吸收到钠基溶液中的吸收速率模型,假设该模型中SO₂的水解反应为瞬间反应;关于CO₂水解反应存在两种假设：有限动力学假设和瞬间反应假设。由这两种方法计算分别获得SO₂的吸收速率并与完全预混气液反应器中的的动态实验进行对比。采用瞬间反应假设可以预测反应速率的趋势,绝对反应速率误差仍然较大。而采用有限动力学假设的模拟值与实验值在pH>3吻合良好。CO₂对SO₂吸收速率的影响主要通过影响气相传质系数和相同pH下溶液总硫浓度产生。根据CO₂存在与否对SO₂吸收速率的影响,获得五个不同的相互作用pH的区间。pH>11.42时,SO₂/N₂吸收速率大于SO₂/CO₂,主要由于气相传质系数影响;7.8 < pH < 11.42时,SO₂/N₂的吸收速率和SO₂/CO₂吸收速率相似,主要由于气相传质系数和溶液总硫影响抵消;5.41 < pH < 7.8时,SO₂/CO₂的吸收速率相对较高,主要由于溶液总硫影响更大;2.8 < pH < 5.41时,SO₂/CO₂的吸收速率相对较低,主要由于气相传质系数影响;pH < 2.8时,SO₂/N₂和SO₂/CO₂吸收速率相似,主要受液相传质的控制。模拟同时获得不同pH下溶液中碳和硫相关离子的转化规律和SO₂吸收速率的控制步骤,为富氧燃烧冷却塔同时脱硫设备的设计和运行提供参考。