水合物法分离混合气中二氧化碳的实验研究

在小型水合物反应装置上研究了纯水、四氢呋喃(THF)、四丁基溴化铵(TBAB)3种不同体系对二氧化碳水合物生成动力学特性的影响。结果表明THF体系中水合物生成的诱导时间最短,在6~15℃较高的反应温度下仍可以显著改善CO_2水合反应体系的相平衡条件。在4.5~6MPa,0.5~6℃条件下,研究了混合添加剂THF/SDS体系中CO_2/N_2混合气水合物生成特性及其分离效果。结果发现,9%THF体系中加入0.3%SDS可以进一步缩短水合反应诱导时间,增大水合反应系统压降,提高了水合物的储气量,与单一THF体系相比,CO_2的回收率提高了近10%。研究表明THF/SDS混合添加剂可在较高操作温度下改善CO_2/N_2的分离效果,降低分离能耗。     

温度扰动促进CO_2水合物生成特性的实验研究

根据水合物相区CO2气体溶解度的双重特性,在小型实验装置上研究了温度扰动对CO2水合物生成特性的影响。结果表明,纯水体系中实施温度扰动可以有效促进水合物的快速生成,气体压降提高了30%。在含0.3%十二烷基硫酸钠(sodium dodecyl sulfate,SDS)添加剂体系中采用温度扰动的促进效果更加明显,且生成量增多,反应更彻底。反应结束时的剩余气体压力非常接近设定温度下的的相平衡压力,系统的气体压降是未扰动的2.6倍。研究还发现,选择合适的温度扰动时机能够在很大程度上进一步缩短水合物的生成时间。     

机械强化制备二氧化碳水合物的特性研究

搅拌是促进CO2水合物快速制备的1种有效的机械强化方法。为提高水合物的生成速率并且降低能耗,在小型高压水合物反应装置上实验研究不同搅拌时机对CO2水合物生成特性的影响。结果发现,搅拌可以大大提高CO2的溶解速率,使CO2气体在3 min内即可达到溶解饱和。此外,水合物生成过程中搅拌时机的选择也非常关键。研究发现,仅在气体溶解和降温成核过程中实施35 min的搅拌不仅可以显著提高CO2水合物的生成速率,而且大大缩短了搅拌时间,与静态反应系统相比,能耗可降低86%。     

含盐体系二氧化碳水合物的生成与分解特性

在小型水合物反应装置上对含盐体系CO2水合物的相平衡特性进行了实验研究,并探讨盐度及pH值对CO2水合物的生成和分解特性的影响。结果表明,与纯水相比,含盐体系中CO2水合物的相平衡条件要求更高,CO2水合物的稳定存在区域缩小,且盐度越大越明显;盐类物质对CO2水合物的生成有抑制作用,增加了水合物的成核诱导时间,降低了水合物的生成量;pH值较高的含盐体系不利于CO2水合物的成核和生成;CO2水合物的分解速度随着温度的升高而增大,而盐度对水合物分解的影响并不明显。     

不同O2浓度下NH3选择非催化还原NO的实验和模型研究

NO的选择性非催化还原反应是燃烧过程重要的脱硝途径。文中在800~1 200 ℃,初始浓度CNO,ini=200 mmol/mol、CO2,ini=0%~10%、氨氮比CNH3/CNO=1.2的情况下,进行了NH3/NO/O2的均相流反应器的实验和化学动力学模拟研究,着重研究不同氧浓度对NO和N2O浓度变化规律的影响。实验结果表明,在微量氧气杂质(CO2"50 mmol/mol)条件下,脱硝温度更高,而脱硝率达到了95%。化学动力学模型预测的NO和N2O浓度变化规律与实验结果非常吻合：氧浓度的升高使NH3/NO的最佳反应温度下降,同时降低脱硝的效果;N2O生成浓度随着氧浓度的升高而降低,对应N2O最大浓度的温度也降低。微氧工况的N2O最大生成浓度比低氧浓度下更低,而生成温度更高。     

固硫中间产物CaS生成反应动力学研究

在层燃炉和煤粉炉的燃烧固硫过程中,钙基固硫剂的固硫产物主要是CaSO_4和CaS,其中CaS的生成特性对燃煤锅炉的脱硫有很大影响。文中对CO气氛下CaSO_4转化成固硫中间产物CaS的特性进行了热力学分析,并利用热重与红外光谱分析法进行了CaS生成反应特性实验。结果表明：CaS的生成反应优先于CaSO_4的分解反应,CO浓度改变对CaS生成过程的影响不大,但低浓度CO会导致CaSO_4的分解反应提前,CaS的转化率也略低。建立了CaS生成反应动力学,得到CO气氛下CaS的生成反应为1/2阶化学反应,指前因子为5．69×10~(12),表观活化能为461．37kJ/mol。     

三聚氰酸选择性非催化还原脱硝特性的实验研究

采用立式管式炉实验系统研究了三聚氰酸选择性非催化还原脱硝特性,探索了温度、O2浓度、停留时间、三聚氰酸与NO摩尔比、NO初始浓度等反应参数以及CO和H2O对三聚氰酸脱硝特性的影响。实验得出适宜的脱硝反应参数:反应温度约为950℃,温度窗口为876~1150℃,停留时间为1.1~1.2 s,摩尔比为0.5,O2浓度为2%~3%。较高的NO初始浓度可以获得较高的脱硝效率。典型工况参数下,三聚氰酸在900℃时取得最大脱硝效率83.1%,大于900℃后,脱硝效率下降幅度较小,与氨气和尿素选择性非催化还原相比,具有更好的高温脱硝特性。CO和H2O的加入可以提高较低温度时的脱硝效率,拓宽温度窗口,使其向低温方向移动,较适宜的CO浓度约为200μL/L,H2O浓度约为5%。     

工艺操作参数对烟气SNCR脱硝性能影响的数值模拟

采用SNCR反应详细机理建立了SNCR计算模型,仿真结果与实验结果的脱硝曲线整体趋势基本一致,同时利用Chemkin-Pro对SNCR反应进行仿真计算,针对NSR、反应停留时间、添加剂(CO、H_2、CH_4)浓度、NO初始浓度、氧气浓度、水蒸气浓度及反应压强等多种影响SNCR反应的因素进行了深入研究,分析各因素对SNCR反应的影响规律。仿真计算结果表明,O_2及添加剂(CH_4、CO、H_2)均可以降低SNCR所需的反应温度,提高NSR可以令最佳脱硝效率温度显著降低,停留时间的延长在一定范围内可以提高脱硝效率,同时使温度窗口略有降低,水蒸气浓度与NO初始浓度的影响在低温段与高温段具有不同的作用特征,反应压强的提高可降低SNCR所需的反应温度但同时会令出口NO_2含量上升。研究结果可为超超临界循环流化床锅炉超低NO_x排放技术的参数优化提供参考。     

不同气氛下煤粉燃烧硫氮污染物析出的特性研究

利用水平炉在O2/N2气氛和O2/CO2气氛下煤粉燃烧进行了实验研究,对煤中硫氮排放特性进行了比较分析。发现较高温度下无机硫产生SO2较多,出现峰值的时间提前。温度升高NOx转化率增加。相同温度下,O2/CO2气氛下SO2、NO排放峰值较低。不同CO2浓度下SO2排放变化不大。挥发分NO析出几乎无影响,而焦炭NO峰值随CO2浓度升高呈减小趋势。提高O2浓度对有机硫析出的影响不大,而无机硫生成SO2的时间提前,峰值提高。NO生成峰值生成时间均提前。静态实验结果表明新型燃烧方式有利于降低SO2和NO的排放。     

尿素/三乙醇胺湿法烟气脱硫脱硝的试验研究

尿素溶液与NOx反应生成N2和CO2气体,可实现烟气同时脱硫脱硝,该文进行了尿素/三乙醇胺湿法脱硫脱硝的试验研究。试验采用双级串连的填料塔为主体反应器,分别对气速、液气比、反应物浓度、添加剂浓度、反应温度等参数对尿素溶液吸收SO2反应的影响进行了试验研究,并进行了尿素溶液同时吸收SO2和NOx的试验研究,研究表明：增大气速、液气比可使脱硫效率增加,而三乙醇胺和尿素浓度对脱硫效率影响较小。SO2和NOx具有相互协同促进作用,其净化效率在试验条件下可分别提高1%~3%和5%~ 6%,总脱硫效率可达95%以上,脱硝效率在63%以上。     

Direct Electrical Heating of Subsea Pipelines—Technology Development and Operating Experience

The formation of hydrates in the subsea production of oil and gas is a well-known problem. As the unprocessed well stream cools down, hydrates start to form around 25 degC, depending on the water cut and pressure in the pipeline. Several solutions are available to solve this problem. Generally, chemicals (i.e., methanol) have been used. Methanol reduces the critical temperature where hydrates are formed. Alternatively, hydrates can be prevented by using thermal insulation in combination with direct electrical heating (DEH). Thus, the well stream is kept above the critical temperature for hydrate formation. DEH heats the pipeline by forcing a large electric current to flow through the pipeline steel. The system model for design and sizing of the system is presented. DEH uses a single-phase system where the heated pipeline is electrically connected to the surrounding sea water. Thus, the system current is divided between sea water and pipeline, requiring additional sacrificial anodes on the pipeline. The anode system for a pipeline with DEH is discussed. There are currently more than 100 km of DEH pipelines on the Norwegian Continental Shelf. The operating experience from these installations is discussed. This paper presents the research and development for application of the system for pipelines with lengths up to 50 km     

三种负极材料添加对铅酸电池循环寿命影响

通过在铅酸电池负极添加1%的碳粉、TiO_2和SiO_2,研究了负极材料添加对铅酸电池循环寿命的影响。结果表明,在负极活性物质添加碳导致化成时间增加。添加碳电极在第一次PSoC循环中比含TiO_2电极表现更加出色。在第二次PSoC循环中含SiO_2电极寿命最低。在第二次PSoC循环中含碳电极没有比含TiO_2电极表现更加出色。添加碳和TiO_2显著增加电极循环寿命。在PSoC循环中,在电极中添加碳和TiO_2具有重要作用,可以获得低的充电电压和降低负极孔隙量级,这些机制改善了电极接受充电电流的能力,限制了硫酸盐晶体的长大。在PSoC循环高电流放电条件下,电池内阻具有重要影响,导致显著的初始电压降和影响电极的循环寿命。     

Heating of an oil well with the hydrate blockages using a heating cable

The problem of formation of hydrate blockages in oil wells during oil production is investigated. The thermal method of removal of blockages using a heating cable is considered. Temperature fields in an oil well with a heating cable are calculated. The time of heating to remove the hydrates is determined.     

Influence of additives on the dielectric strength of high-densitypolyethylene

In this study, we present the results of the influence of chemical additives (antioxidant and UV stabilizer) and pigments (titanium dioxide and carbon black) on the short-term dielectric breakdown test of high-density polyethylene (HDPE). These additives and pigments are commonly added to polyolefins, which are used as insulating material for medium voltage cables. The incorporation was performed in a single screw extruder and thin films specimens were obtained by hot compression from extruded materials. For the dielectric breakdown test, an automated system has been used. A voltage ramp of 500 V/s was applied to specimens immersed in a silicon oil bath at room temperature. The degree of crystallinity and chemical modification of the formulations were evaluated by X-ray diffraction and Fourier transform infrared (FTIR), respectively. The dielectric breakdown results have been analyzed by a Weibull distribution. The shape and scale parameters of this distribution have been obtained by a graphic and maximum likelihood method. These results showed that the carbon black is the component that affects the dielectric strength, that the β shape parameter from the graphic method can be used to evaluate additive mixing conditions, and that the weakest point for formation of the rupture channel is on the carbon black agglomerate     

回转干馏炉转向及物料配比对停留时间的影响

物料在回转干馏炉内的停留时间影响油页岩固体热载体干馏技术的干馏效果及出油率。在油页岩固体热载体干馏系统实验台上,以油页岩颗粒与页岩灰的混合物为实验物料,采用示踪粒子方法研究了冷态条件下混合物的配比、回转干馏炉（带内部翻料构件）的旋转方向2种因素对混合物停留时间的影响。结果表明,混合比例的不同会造成颗粒平均粒径的不同,平均粒径较小的混合物料停留时间长;干馏炉因翻料构件的结构特性,旋转方向不同时能形成不同的颗粒运动模式,当工作在直角抄板模式时,较大的表面层颗粒滚落距离造成了较长的物料停留时间。     

Removal of dilute benzene using a zeolite-hybrid plasma reactor

The decomposition of benzene was carried out using a plasma reactor packed with a mixture of BaTiO₃ and zeolite pellets, the zeolite-hybrid reactor. The reactor performance was characterized by measuring CO_x formed during plasma discharge and CO_x adsorbed on the solid surface, The decomposition efficiency of benzene in the hybrid reactor was 1.4-2.1× higher than that in a conventional plasma reactor packed with BaTiO₃ alone. Benzene existing outside a zeolite crystalline pore was found to decompose more easily than that inside a zeolite pore. In addition, the presence of zeolites suppressed the formation of NO_x     

Proposal of a high‐performance solid oxide fuel cell combined power generation system with carbon dioxide recovery

A new fossil‐fuel‐utilized high‐performance combined power generation system with liquefaction recovery of carbon dioxide is proposed. In the system, pure oxygen is used as the oxidant gas to prevent the mixture of nitrogen in the exhaust gas and to make the liquefaction recovery of carbon dioxide possible. Solid oxide fuel cell is selected as the topping cycle. The exhaust fuel gas of the solid oxide fuel cell is afterburned with its exhaust oxidant gas of pure oxygen and the heat of the combustion gas is utilized in the bottoming cycle. Nonequilibrium MHD/noble gas turbine cycle is selected as the bottoming cycle because the temperature of the combustion gas reaches about 2300 K. It is made clear through detailed examination of energy balance that the total thermal efficiency of the system using natural gas (methane) as the fuel reaches 63.24% (HHV) or 70.18% (LHV). This efficiency is very high as for the system with carbon dioxide recovery. The proposed system, therefore, has excellent performance, and further research and development is warranted. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(4): 12–21, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10146     

Molten carbonate fuel cell stack performance with gas recycling

The molten carbonate fuel cell (MCFC) power plant is expected to be one of the most promising future power generation systems for the electric utilities because of its high efficiency, environmental suitability and capability of using coal as fuel. To obtain such attractive performance, it is necessary for the plant to adopt the gas-recycling operation system. The authors tested a 6-kW class MCFC stack with three types of gas recyclings, i.e., cathode, anode and carbon dioxide ones, including pressurized conditions. This paper describes the test results and the effects of the gas-recycling operations. Cathode gas recycling is proved to be able to control the stack temperature and give the flexibility for setting oxygen utilization. Anode gas recycling is proved to be able to suppress the methane formation and decrease the deviation of the stacked cell voltages. Including the starting-up process, it is proved that the electricity can be generated from the stack without supplying carbon dioxide from outside the system by carbon dioxide gas recycling. In such a process using a burner for carbon dioxide gas recycling, burner temperature must be controlled to a certain value. It is important to adjust the fuel supplying rate, load current and cathode gas-recycling ratio to each other. At the load change process, constant gas utilization operation is not effective in changing the burner temperature.     

CO2催化氢化催化剂及其反应机理综述

研究二氧化碳资源化利用技术将对电厂CO₂减排工作具有重要意义。综述了基于催化氢化思想的CO₂转化催化剂及其反应机理,其主要涉及铜、镍、锌等过渡金属和钌、铱、钯等贵金属。现有催化氢化CO₂转化技术研究主要集中于研究与开发高活性催化剂,分析与推测反应机理,提高产物产率及选择性,优化反应体系结构与条件等方面。高活性催化剂如双金属合金,过渡金属催化体系将是未来CO₂催化氢化领域主要的研究方向之一。各催化剂催化氢化CO₂反应机理较为复杂,值得深入研究。随着经济、环保、节能等新型CO₂催化氢化技术的开发及研究的深入,电厂CO₂减排及资源化工业应用也将成为可能。