烟气循环流化床法

<正>烟气循环流化床脱S工艺由吸收剂制备、吸收塔、脱S灰再循环、除尘器及控制系统等部分组成。该工艺一般采用干态消石灰粉作为吸收剂,也可采用其它对SO2有吸收反应能力的干粉或浆液作为吸收剂。由锅炉排出的未经处理的烟气从吸收塔(即流化床)底部进入。吸收塔底部为1个文丘里装置,烟气流经文丘里管后速度加快,并在此与很细的吸收剂粉末互相混合,颗粒之间、气体与颗粒之间剧烈摩擦,     

两段式处理制取车用燃料级沼气的试验研究

以配制的模拟沼气为原料,采用水洗和可再生的碱金属基吸收剂干法吸收相结合的两段式处理流程来纯化沼气,以沸石颗粒作洗涤塔填料,附载Na2CO3的活性碳颗粒作干式吸收塔填料,制得的CH4含量在95%以上,达到车用燃料级的高纯沼气。     

分馏与吸收稳定系统的关联性分析及优化

由于原料性质不断"变重",影响了长庆石化公司1.4Mt/a重油催化裂化装置分馏与吸收稳定系统的平稳操作。对分馏与吸收稳定系统主要的关联性操作,即分馏塔顶的富气和粗汽油作为吸收塔进料的单向关联、分馏一中回流与稳定塔底温度的双向关联、轻柴油进再吸收塔与富吸收油返分馏塔的双向关联进行了分析,提出了优化措施建议:应适时调整补充吸收剂的量,使之与粗汽油的量之比保持在0.7～1.3的范围内;在减渣进料加工量为110t/h的工况下,将补充吸收剂流量控制在50t/h;稳定塔底重沸器取热量跟踪温度控制应尽快投用;将热量换算更换为流量换算;对一中和稳定塔底的换热流程进行优化;在处理量变化的情况下,应随着贫气量的变化,适时调节贫吸收剂的流量,保证再吸收塔的吸收效果;贫吸收油可改用分馏塔顶顶循油。     

一种吸收稳定改进流程的模拟分析

提出一种改进的吸收-稳定流程,通过增加稳定汽油与吸收贫气的预吸收罐,提高吸收-再吸收过程的吸收效果。预吸收罐的操作条件:温度为30～35℃,压力为1.1～1.5MPa(表),在此条件下操作不会导致装置冷热负荷的额外增加,易于改造实施。应用流程模拟软件Aspen Plus,对某焦化装置的吸收稳定系统进行对比模拟计算与分析,发现预吸收罐增大了对∑C3组分的吸收,减少了再吸收塔∑C3的进料含量,增强了吸收-再吸收过程,在满足同样的干气产品质量指标要求下,柴油吸收剂的用量将降低。改进后的流程与改进前相比,吸收塔能多吸收6%(体积分数)左右的C3组分,在固定补充吸收剂用量不变时,通过改变柴油的流量,在同样控制∑C3不大于3%(体积分数)的干气质量指标下,柴油用量可从改进前的22t/h降低到改进后的12t/h,生产成本显著降低,从而增加了经济效益。     

扰流器作用下循环流化床烟气脱硫塔内流动行为研究

以硼矿石焙烧CFB-FGD系统中的吸收塔为研究对象,以FLUENT15.0为计算平台,采用数值模拟的方法研究了扰流器对吸收塔内气固两相流流场、温度场以及颗粒驻留时间的影响。结果表明:在吸收塔上部加装扰流器可以增强吸收塔上半部的气固两相扰动,强化吸收剂颗粒的内循环,延长吸收剂在塔内的驻留时间,并能有效降低吸收塔出口烟温；随着扰流器出流速度的增大,吸收塔内烟气的平均湍动能增大而出口烟温则逐渐降低。     

开式吸收式热泵降膜吸收器实验研究

以构建的用于开式吸收式热泵的竖直管降膜吸收器实验台为基础,以价格低廉的CaCl2溶液作为吸收剂,通过实验研究确定各参数对吸收过程中传质的影响.实验发现:提高吸收剂浓度、液气比、冷却比和吸收塔高度可增强吸收效果;气体湿度和气体温度的增加会降低吸收效果;冷却水和吸收剂的流动方向也会影响吸收效果.分析了产生这些影响的原因,并从实际应用出发给出了这些参数的限制条件.     

串行流化床生物质气化合成二甲醚的模拟

以稻秸秆为研究对象,利用Aspen Plus软件建立了串行流化床生物质气化制取合成气合成二甲醚（DME）的模型,研究了不同气化温度、水蒸气与生物质的质量比（mS/mB）、DME合成温度、合成压力、吸收塔操作压力及吸收剂与DME的配比（nA/nD）对合成工艺的影响.结果表明：对于采用串行流化床生物质水蒸气气化技术制取DME的一步法合成系统,建议气化温度取750℃左右,mS/mB取0.3,DME合成温度取260℃,合成压力取4MPa,用水作吸收剂,吸收塔的操作压力控制在3～4MPa,nA/nD取0.5;在此工况下,1kg生物质（干燥基）所能产生的二甲醚物质的量约为6.1mol.     

基于Rate-based模型的氨水脱碳吸收过程模拟

以氨水为吸收剂,以脱除300 MW电厂烟气CO2的化学吸收系统作为模拟对象。基于Aspen-Plus软件建立化学吸收系统模型,对氨法脱碳吸收过程进行优化设计。采用Rate-based模型对NH3-H2O-CO2体系中各组分的分压与文献中实验值进行了比对,发现具有很好的一致性。最后经过优化,选择了4.48 mol/L、30℃、1500 kg/s的氨水溶液作为吸收剂吸收50℃的模拟烟气,吸收塔高度为30 m。     

HCl干式净化过程平衡浓度计算及其应用

利用固体产生生成的能耗分析，在传统的热力学平衡公式中加入入修正项，计算HCl气体在利用石灰类吸收剂对其进行干式净化过程的平衡浓度，首次提出气固反应过程中反应气全的平衡浓度随着固体反应率的增大而上升的概念，计算结果表明：吸收剂在达到一定的反应率以后，HCl的平衡浓度随温度的上升而下降。利用平衡浓度随反应率和温度的变化特征可以解释传统的热力学平衡式所不能解释的一些实验现象，并可以利用平衡浓度来预测利用钙基吸收剂干式净化焚烧炉排的HCl的净化效率和吸收剂用量。预测结果可以判断干式净化的使用范围，局限性和改进方向。     

流程模拟技术在石家庄炼化Ⅰ套催化装置上的应用

通过Aspen Plus软件,建立石家庄炼化Ⅰ套催化装置除反-再部分外的流程模拟稳态模型,包括:分馏塔、吸收塔、解吸塔、稳定塔和再吸收塔流程模型,本流程模拟中的分馏塔、吸收塔、解析塔、稳定塔均采用Petro Frac模型,其中,分馏塔和稳定塔均为板式塔,解析塔为板式、填料混合装填,吸收塔、再吸收塔为填料塔。通过模拟工艺过程计算、灵敏度分析,确定较佳的操作条件,以指导生产,调整操作参数,旨在满足产品质量的前提下,达到节能降耗、提高装置经济效益的目的。实际运用过程中,找到吸收塔、解析塔、稳定塔相关变量的关联度,确定了最佳的优化操作参数,稳定塔顶回流量由70t/h下降至60t/h,塔底热源耗能减少266.714kW/h;解析塔底温度由118℃下降至110℃,重沸器热源减少381.14kW/h,合计节省蒸汽消耗0.73t/h,装置全年实现节能效益71.1万元。     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Decomposition of limestone in a solar reactor

The thermal decomposition of limestone has been selected as a model reaction for developing and testing an atmospheric open solar reactor. The reactor consists of a cyclone gas/particle separator which has been modified to let the concentrated solar energy enter through a windowless aperture. The reacting particles are directly exposed to the solar irradiation. Experimentation with a 60 kW reactor prototype was conducted at PSI's 90m² parabolic solar concentrator, in a continuous mode of operation. A counter-current flow heat exchanger was employed to preheat the reactants. Eighty five percent degree of calcination was obtained for cement raw material and 15% of the solar input was converted into chemical energy (enthalpy).The technical feasibility of the solar thermal decomposition of limestone was experimentally demonstrated. The use of solar energy as a source for high-temperature process heat offers the potential of reducing significantly the CO₂ emissions from lime producing plants. Such a solar thermochemical process can find application in sunny rural areas for avoiding deforestation.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

液压系统常见的故障诊断及处理

任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法，这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。     

Biohydrogen production by Anabaena sp. PCC 7120 wild-type and mutants under different conditions: Light, nickel, propane, carbon dioxide and nitrogen

Increasing awareness of environmental problems caused by the current use of fossil fuel-based energy, has led to the search for alternatives. Hydrogen is a good alternative and the cyanobacterium Anabaena sp. PCC 7120 is naturally able to produce molecular hydrogen, photosynthetically from water and light. However, this H₂ is rapidly consumed by the uptake hydrogenase.This study evaluated the hydrogen production of Anabaena sp. PCC 7120 wild-type and mutants: hupL⁻ (deficient in the uptake hydrogenase), hoxH⁻ (deficient in the bidirectional hydrogenase) and hupL⁻/hoxH⁻ (deficient in both hydrogenases) on several experimental conditions, such as gas atmosphere (argon and propane with or without N₂ and/or CO₂ addition), light intensity (54 and 152 ??Em⁻²s⁻¹), light regime (continuous and light/dark cycles 16 h/8 h) and nickel concentrations in the culture medium.In every assay, the hupL⁻ and hupL⁻/hoxH⁻ mutants stood out over wild-type cells and the hoxH⁻ mutant. Nevertheless, the hupL⁻ mutant showed the best hydrogen production except in an argon atmosphere under 16 h light/8 h dark cycles at 54 ??Em⁻²s⁻¹ in the light period, with 1 ??M of NiCl₂ supplementation in the culture medium, and under a propane atmosphere.In all strains, higher light intensity leads to higher hydrogen production and if there is a daily 1% of CO₂ addition in the gas atmosphere, hydrogen production could increase 5.8 times, related to the great increase in heterocysts differentiation (5 times more, approximately), whereas nickel supplementation in the culture medium was not shown to increase hydrogen production. The daily incorporation of 1% of CO₂ plus 1% of N₂ did not affect positively hydrogen production rate.     

Economie d'énergie en trigénération

Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.     

Investigation of the thermodynamic and kinetic properties of La–Fe–B system hydrogen-storage alloys

La–Fe–B hydrogen-storage alloys were prepared using a vacuum induction-quenching furnace with a rotating copper wheel. The thermodynamic and kinetic properties of the La–Fe–B hydrogen-storage alloys were investigated in this work. The P–C–I curves of the La–Fe–B alloys were measured over a H₂ pressure range of 10⁻³ MPa to 2.0 MPa at temperatures of 313, 328, 343 and 353 K. The P–C–I curves revealed that the maximum hydrogen-storage capacity of the alloys exceeded 1.23 wt% at a pressure of approximately 1.0 MPa and temperature of 313 K. The standard enthalpy of formation ΔH and standard entropy of formation ΔS for the alloys' hydrides, obtained according to the van't Hoff equation, were consistent with their application as anode materials in alkaline media. The alloys also exhibited good absorption/desorption kinetics at room temperature.     

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia,northwest Greece)

The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.