HIGH TEMPERATURE CAPTURE OF CARBON DIOXIDE: CHARACTERISTICS OF THE REVERSIBLE REACTION BETWEEN CaO(s) and CO2(g)

The reversible reaction between CaO(s) and CO₂(g) may ultimately find application in a high temperature process to control CO₂ emissions from advanced power generation processes. At appropriate temperature and pressure combinations, CO₂(g) is removed from the gas phase and captured as CaC₃(s). At higher temperature and/or lower pressure, the reaction is reversed to produce a gas stream having high CO₂(g) concentration suitable for use or ultimate disposal. Both the calcination and carbonation reactions have been studied in an electrobalance reactor as a function of temperature, pressure, and gas composition. Multicycle tests have provided preliminary information on sorbent durability. Solid structural property characteristics have been measured as a supplement to the reaction studies.

Rapid and complete calcination of CaCO₃ can be achieved at temperatures as low as 750°C under one atmosphere of N2. Higher pressure reduces the calcination rate while the presence of CO₂ in the calcination atmosphere requires the use of higher temperature. Mild calcination conditions produce a CaO product which is most reactive during the carbonation phase. Carbonation is characterized by a rapid initial reaction rate followed by an abrupt transition to a quite slow rate. Significant reduction in CO₂ capacity between the first and second carbonation cycles, ranging from 15% under favorable reaction conditions to more than 30% at severe conditions, was found. However, the capacity loss tended to moderate as the number of cycles increased.     

羌D2井白云岩储集层孔隙空间结构研究

通过铸体薄片鉴定和白云岩物性、压汞分析以及观察,详细论述了羌D2井白云岩的储集层孔隙空间结构特征,指出白云岩的主要储集空间为晶间孔、晶间溶孔和裂缝,细晶白云岩和白云岩石化微晶灰岩物性好。依据白云岩的岩石学特征和白云岩物性参数,阐述了该井白云岩储集层孔隙空间结构特征与白云岩结构特征的相关关系。     

脱碳系统的特点及技术分析

改良苯菲尔法是合成氨工艺脱除转化气中二氧化碳以得到合格的合成氨工艺气的代表性单元操作,其运行的能耗高低、稳定性将直接影响着工厂的经济效益.介绍工艺流程特点、技术评估及技改情况.     

KINETIC AND STRUCTURAL STUDIES OF REGENERATION OF SULFIDED DOLOMITE IN CARBON DIOXIDE II THE CYCLIC REGENERATION

(Communicated by H.L. Toor)

Regeneration of sulfided dolomite in CO₂, an alternative to regeneration in CO₂/H₂O, has been conducted in a TGA system up to 20 cycles under the optimal regeneration condition. The solid sorbent has shown a much slower deterioration in sulfidation capacity upon cycling by regeneration in CO₂ than in CO₂/H₂O. The utilization of Ca reached 50% in the 20th cycle, compared with the 20% by the CO₂/H₂O regeneration. The XES sulfur profile of partially reacted samples indicated a switch in reaction pattern, both in sulfidation and regeneration, from topochemical to nonlopochemical at the 3th/4th cycle. Incorporaling the concept of solid deactivation, a cyclic regeneration model was developed and successfully predicts the progress of regeneration in a specific cycle and the trend of change in reaction pattern.     

KINETIC AND STRUCTURAL STUDIES OF REGENERATION OF SULFIDED DOLOMITE IN CARBON DIOXIDE II THE CYCLIC REGENERATION

(Communicated by H.L. Toor)

Regeneration of sulfided dolomite in CO₂, an alternative to regeneration in CO₂/H₂O, has been conducted in a TGA system up to 20 cycles under the optimal regeneration condition. The solid sorbent has shown a much slower deterioration in sulfidation capacity upon cycling by regeneration in CO₂ than in CO₂/H₂O. The utilization of Ca reached 50% in the 20th cycle, compared with the 20% by the CO₂/H₂O regeneration. The XES sulfur profile of partially reacted samples indicated a switch in reaction pattern, both in sulfidation and regeneration, from topochemical to nonlopochemical at the 3th/4th cycle. Incorporaling the concept of solid deactivation, a cyclic regeneration model was developed and successfully predicts the progress of regeneration in a specific cycle and the trend of change in reaction pattern.     

温室气体(CO2)煤层封存的可行性分析

我国是以煤炭消费为主的国家,温室气体CO2的大量排放使我国面临越来越大的环境压力;同时我国煤层气的资源量非常丰富,但是由于煤储层呈现“三低一高”的特性使我国煤层气的采收率相对较低。本文通过研究得出,采用煤层深埋CO2技术,可以达到使温室气体CO2减排和提高煤层甲烷采收率的目的,这样既可以缓解我国所面临的环境压力,同时又可以改善我国的能源结构。     

石灰石的煅烧分解及其吸收二氧化碳机理

在天然气或合成气制氢过程中,借助于石灰石煅烧分解与石灰吸收二氧化碳的化学循环反应,去除反应产物,破坏化学平衡,可以连续地驱动化学反应进行,从而提高氢气的产率,同时控制温室气体二氧化碳的排放．在多功能热重反应器（TGR）内就化学循环反应过程中的颗粒尺寸、温度煅烧分解率等对吸附剂煅烧分解和吸收特性的影响进行了比较充分的实验研究．当吸收反应温度在500℃～620℃范围内时,CaO吸收二氧化碳的反应速率与石灰石中钙的利用率都维持在比较高的水平,石灰石分解后产生的氧化钙的利用率增长比石灰石的分解率增长慢,分解率高,吸热量也高,因此,简单地提高石灰石的分解率并不是提高石灰石钙利用率的最佳选择。     

KINETIC AND STRUCTURAL STUDIES OF REGENERATION OF SULFIDED DOLOMITE IN CARBON DIOXIDE I THE FIRST CYCLE REGENERATION

(Communicated by H. L. Toor)

Half-calcined dolomite (CaCO₃ · MgO) is one of the most promising sorbents for desulfurizing fuel gas at high temperatures. For environmental reasons, the spent dolomite must be capable of regeneration for cyclic use. Regeneration by a mixed gas of H₂O/CO₂ has not met with success due mainly to the deterioration of sorbent reactivity with cycling. This research investigates an alternative method of regeneration using CO₂ alone and its application to cyclic use.

Kinetic data for first cycle regeneration are collected in a TGA system at 500 to 950°C and 1 to 21.4 atm. The effects of gas-composition, preconditioning and solid structure are also studied. The results show that regeneration by CO, is equally effective as by H₂O/CO₂ in terms of sorbenl reactivity. More significantly, the sorbent has shown a much slower deterioration upon cycling. Examination of solid structure by SEM and compositional profile of sulfur by XES reveals that the reaction proceeds topochemically above 700°C and homogeneously below 650°C. A transport-reaction model is developed and shown to agree closely with experimental results.     

REACTOR-MEMBRANE PERMEATOR CASCADE FOR ENHANCED PRODUCTION AND RECOVERY OF H2 AND CO2 FROM THE CATALYTIC METHANE-STEAM REFORMING REACTION

The catalytic reforming of methane by steam is an important industrial process that produces H₂, CO and CO₂, thus chemically transforming natural gas, coal gas and light hydrocarbon feedstocks to synthesis gas or hydrogen fuel. Methane-steam reforming may consist of a number of reactions depending on the reforming catalyst, operating conditions and feedstock composition, The typical industrially desirable reactions are the reverse of methanation (CH₄ + H₂O = CO + 3H₂) and the water-gas shift (CO + H₂O = CO₂ + H₂). Both reactions are equilibrium limited and the composition of the mixture that exits the reformer is in accordance with the one calculated thermodynarmically. Removal of reaction products at the reactor exit by means of selective membrane permeation can offer improved CH₄ conversions and CO₂ and H₂ yields, assuming the subsequent utilization of the reject streams by a second methane-steam reformer. We numerically investigated the feasibility of a system of two tubular methane-steam reformers, in series with an intermediate permselective polyimide membrane permeator, as means of improving the overall CH₄ conversion and the H₂, CO₂ yields over conventional methane-steam reforming equilibrium reaction-separation schemes that are currently in industrial practice. The unique feature of the permselective polyimide separator is the simultaneous removal of H₂ and CO₂ versus CH₄ and CO from the reformed streams. The utilized 6FDA-3,3', 5,5'-TMB aromatic polyimide was reportedly characterized [10] and found to exhibit superior permselective properties compared with other polyimides of the same or different dianhydride sequence. Conversion and yield of the designed reactor-membrane permeator reforming system can be maximized by optimizing the permselective properties of the membrane material and the design variables of the reactors and the permeator. Product recovery and purity in the permeate stream need to be compromised to overall enhance methane conversion and product yield. The operating variables that were varied to investigate their effect on the magnitude of conversion and yield included the inlet pressure of the first reformer, the temperature of both reformers, and the permeator dimensionless Pe' number (variation of the first two variables results to a drastic change in the composition of the reformed stream that enters into the permeator). The numerical results show that the new reformer-membrane permeator cascade process can be more effective (it can offer increased CH₄ conversions and H₂, CO₂ yields) than conventional equilibrium methane-steam reforming reaction-separation processes currently in practice.     

ALTERNATIVE GENERATION OF H2, CO AND H2, CO2 MIXTURES FROM STEAM-CARBON DIOXIDE REFORMING OF METHANE AND THE WATER GAS SHIFT WITH PERMEABLE (MEMBRANE) REACTORS

A new process is proposed which converts CO₂ and CH₄ containing gas streams to synthesis gas, a mixture of CO and H₂ via the catalytic reaction scheme of steam-carbon dioxide reforming of methane or the respective one of only carbon dioxide reforming of methane, in permeable (membrane) reactors. The membrane reformer (permreactor) can be made by reactive or inert materials such as metal alloys, microporous ceramics, glasses and composites which all are hydrogen permselective. The rejected CO reacts with steam and converted catalytically to CO₂ and H₂ via the water gas shift in a consecutive permreactor made by similar to the reformer materials and alternatively by high glass transition temperature polymers. Both permreactors can recover H₂ in permeate by using metal membranes, and H₂ rich mixtures by using ceramic, glass and composite type permselective membranes. H₂ and CO₂ can be recovered simultaneously in water gas shift step after steam condensation by using organic polymer membranes. Product yields are increased through permreactor equilibrium shift and reaction separation process integration.

CO and H₂ can be combined in first step to be used for chemical synthesis or as fuel in power generation cycles. Mixtures of CO₂ and H₂ in second step can be used for synthesis as well (e.g., alternative methanol synthesis) and as direct feed in molten carbonate fuel cells. Pure H₂ from the above processes can be used also for synthesis or as fuel in power systems and fuel cells. The overall process can be considered environmentally benign because it offers an in-situ abatement of the greenhouse CO₂ and CH₄ gases and related hydrocarbon-CO₂ feedstocks (e.g., coal, landfill, natural, flue gases), through chemical reactions, to the upgraded calorific value synthesis gas and H₂, H₂ mixture products.     

DYNAMIC KINETICS OF THE COMMON INTERMEDIATES FORMED IN CO AND CO2 HYDROGENATIONS ON Rh/MgO

Stable intermediates are formed during both CO and CO₂ hydrogenations on Rh/MgO at 190-220^°C. The intermediates consist of at least four species, each of which is consecutively and irreversibly converted at a similar rate, forming the final product of CH₄ by reaction with H₂     

CO2在仿生物型吸收剂和其他吸收剂中的溶解度

引　言本文提出一种仿生物型ＣＯ2 吸收方法 ,试以生物体内控制呼吸作用的呼吸酶中的关键核心基团为基础 ,合成出的物质作为ＣＯ2 吸收剂 ,通过测定ＣＯ2 在包括仿生物型吸收剂在内的几种典型吸收剂中的溶解度 ,说明仿生物型ＣＯ2 吸收剂的热力学特性及其潜在的工业应用前景 .1　原　理ＣＯ2 在物理溶解时气液平衡符合Ｈｅｎｒｙ定律ＰＡ =ＨＡｃＡ (1)　　伴有化学反应的吸收[1] 较为复杂 ,其气液平衡关系既服从相平衡关系 ,又要服从化学平衡关系 .但总的来说 ,都可以表示为ＣＯ2 (Ａ)与吸收剂中活性组分Ｂ之间的作用ＣＯ2 +Ｂ ＣＯ2 ·Ｂ …     

KOH活化与CO2活化的ACF的孔结构

以KOH和CO2为活化剂分别制备了粘胶基活性炭纤维，并用77K氮吸附进行了孔结构表征。结果表明：两种活化方法制备的样品都是以微孔为主的多孔材料，但孔径分布有所不同，KOH活化的样品具有更窄的孔径分布。     

MODELLING OF EQUILIBRIUM SOLUBILITY OF CO2 AND H2S IN AQUEOUS AMINO METHYL PROPANOL (AMP) SOLUTIONS

Information on acid gas solubility in solvents utilized is needed for the design of gas plants. A mathematical model for the prediction of equilibrium solubility of CO₂ and H₂S in aqueous 2-amino-2-methyl-l-propanol (AMP) solutions is presented. The equilibrium constant, K₁ governing the main amine reaction is expressed as a function of not only temperature but also acid gas partial pressure and AMP concentration. Model predictions agree favourably with experimental data.     

DECOMPOSITION BEHAVIOR AND MECHANISM OF CALCIUM SULFATE UNDER THE CONDITION OF O2/CO2 PULVERIZED COAL COMBUSTION

The decomposition behavior and mechanism of calcium sulfate in O₂/CO₂ pulverized coal combustion were studied in an entrained flow reactor. A reaction rate expression correlating the influence of various factors was proposed for CaS0₄ decomposition and it is able to predict CaS0₄ decomposition satisfactorily. Under the conditions investigated, the decomposition of CaS0₄ was found to be a regime of chemically controlled shrinking core reaction. A CO₂-rich atmosphere enhances CaSO₄ decomposition in absence of oxygen. CaSO₄ particles have catalytic effect on formation of CO from CO₂. A high SO₂ concentration inhibits CaSO₄ decomposition. The kinetics of CaSO₄decomposition has obvious dependence on experimental facilities and conditions, whereas the activation energy has much lower dependence. The kinetics derived in this work is more appropriate for investigating desulfurization in O₂/CO₂ pulverized coal combustion because an entrained flow reactor has a much closer condition to that in O₂/CO₂ pulverized coal combustion than a TGA.     

二氧化碳压缩机叶轮刮伤事故分析

介绍二氧化碳压缩机在试开车过程中遇到的问题和发生的事故,分析事故发生的过程、现象、原因,提出预防措施。     

二氧化碳吸收塔和再生塔改造

介绍西天然气化工有限责任公司合成氨装置脱碳系统中的吸收塔和再生塔的填料分布器工艺改造及该项目收到的良好经济效益和社会效益。     

脱碳系统液泛原因分析与对策

介绍脱碳系统采用自行开发的富液冷却工艺,取代传统苯菲尔特工艺在合成氨装置中的成功应用,以及脱碳系统在运行过程中发生的液泛现象和处理方法,提出今后进一步改进的设想.     

用旋转圆盘仪研究酸岩表面反应动力学

通过模型建立与求解，提出了一种基于旋转圆盘仪试验求取酸岩表面反应时酸液表面浓度的数值方法；并在此基础上，针对某油层白云岩样与盐酸非均相反应，用自行研制的旋转圆盘仪模拟试验装置，确定了一定条件下的酸岩表面反应动力学方程及其活化能。     

影响CO2转化率的原因分析

分析中原大化尿素装置CO2转化率低的原因,并提出相应的改造措施和改进方法。