两种物理吸收法在沼气脱碳中的模拟对比研究

运用化工流程模拟软件PRO/II对水洗法和碳酸丙烯酯法沼气脱碳进行了模拟对比,原料气组分按CH4为57%,CO2为40%,N2为2.8%,O2为0.2%模拟计算,结果显示两种方法在2.7,1.3,0.7 MPa的操作压力下,CH4回收率都可达到98%以上,操作压力极大影响系统运行能耗,宜根据生物天然气终端用途和CO2是否具有回收及利用价值来确定。生物天然气中CH4>93%,CO2<1.5%,N2<5%,O2<0.5%,达到《天然气》二类气及《车用压缩天然气》指标;水洗法CH4和CO2回收率略高于碳酸丙烯酯法,但碳酸丙烯酯法投资低、能耗低、操作维护简单,经济上更有优势。经净化脱碳后的沼气利用价值得到提高,经济和社会效益显著。     

压力水洗法沼气脱碳的模拟研究

采用PRO II 8.0电解质模型模拟了压力水洗法沼气脱碳单元的运行成本和CH_4回收率,要求净化气CO_2浓度3.0%,CH_4收率96%。通过改变进口浓度、吸收塔理论板数、吸收压力、吸收温度、闪蒸压力和再生气-液比,模拟对运行成本和收率的影响。结果表明:高理论板数、低温、高压、高闪蒸压力有利于降低运行成本。吸收压力为0.8 MPa,吸收温度为5℃,闪蒸压力为0.35 MPa时,沼气压力水洗脱碳单元的运行成本为14.4分/m~3,CH_4回收率可以达到98.4%。     

熔融盐对高含氮废弃物气流床气化产气调质与污染物脱除特性研究

在生物质气流床（5 kg/h）气化和熔融盐调质净化装置上,进行了熔融盐对高含氮废弃物气流床气化产气的调质与污染物脱除实验,考察了不同熔融盐温度、不同静液高度对出口气体调质和含N、S、Cl污染物脱除特性的影响。结果表明：经过熔融盐调质后,产气中CO与CO2浓度下降,H2浓度明显上升。当温度从380℃升高至580℃时,H2/CO值提高至7.3。随着静液高度的提高,出口气体中CO2与CO浓度下降,H2浓度由30.1%提高至36.8%;熔融盐对高含氮废弃物气流床气化产气中含N、S、Cl污染物有较明显的脱除效果,H2S、SO2、HCl与含氮污染物中的HCN与NOx已完全脱除,当温度为580℃、静液高度为67.5 mm时,NH3脱除率达到96%。     

变压吸附在沼气脱碳中的应用

采用变压吸附法(PSA)对沼气中CH4-CO2混合物进行分离研究。在四塔变压吸附装置上进行中试试验,对相同环境温度和不同环境温度两种工况下不同原料气组成,分别测定了变压吸附脱碳前后气体中CH4和CO2的体积含量,沼气经变压吸附法脱碳后,净化气中CH4浓度高达97%以上,CO2含量低于1%,CH4回收率为94%。试验证明,变压吸附脱碳技术成本小、能耗低、运行基本不受环境温度影响,在沼气脱碳中具有良好的应用前景。     

两段式生物脱硫工艺对沼气中H_2S去除效果的实验研究

本研究采用两段式生物脱硫工艺,以异养脱硫菌Pseudomonas putida DS1(假单胞菌属)为菌株,研究了硫化物负荷、溶解氧(DO)、气液体积比、p H值等工艺参数对硫化物脱除效果的影响。实验结果表明:DO影响Pseudomonas putida DS1对硫化物的去除率,当硫化物负荷为40 g·m-3·h-1、DO为1.5 mg·L-1时,S2-去除率达90.6%以上;硫化物负荷与DO呈线性关系,随着硫化物负荷增加,DO逐渐增大;硫化物去除率随硫化物负荷的增加而降低,当硫化物负荷小于80 g·m-3·h-1时,硫化物去除率大于90%;当硫化物负荷大于80 g·m-3·h-1时,硫化物去除率低于90%;当沼气中H2S浓度为3 000±10 ppm、气液比为15∶1时,H2S去除率达93.6%;循环液p H值为8.0时,沼气中H2S的去除率达94.0%,Pseudomonas putida DS1对S2-去除率达96.9%,硫化物的转化产物主要为单质S0。     

填料塔内喷淋氨水同时脱碳脱硫实验研究

通过在填料塔内喷淋较低质量分数的氨水,同时脱除模拟烟气中的CO2和SO2.对氨水质量分数、液气比、CO2体积分数、pH值、反应温度和SO2体积分数等影响因素进行研究,选出最佳工况进行连续循环运行,并探讨了实验参数对气溶胶排放的影响,提出控制气溶胶携带的措施.结果表明:氨水质量分数增大、液气比增大和初始CO2体积分数降低均会提高脱碳效率;pH值减小不利于CO2的脱除,但在9.6~10.2出现波动;在15~60℃内,35℃时脱碳效率最高;SO2体积分数的增大会降低脱碳效率;上述影响因素对脱硫效率影响不大,脱硫效率维持在99%以上;260min连续循环运行的实验中,脱碳效率在5min内达到95%以上且能维持30min,脱硫效率在3min内可达到近100%,且保持在92%以上.     

单乙醇胺溶液捕集烟气中CO2的传质过程研究

通过建立CO2散装填料(玻璃弹簧)吸收系统,以乙醇胺(Monoethanolamine)溶液为吸收剂,考察了MEA浓度、CO2分压和液气吸收比等对模拟烟气中CO2传质过程的影响。研究结果表明:在实验条件下,随着液气比的增大,CO2脱除率不断增大;液气比过大,将降低吸收液利用率,液气比过小,将导致CO2脱除率太低。此外,在试验条件下,对填料塔气相总体积传质系数KGav进行了分析,试验结果为实际燃煤CO2吸收填料塔的设计及优化提供必要的理论支撑。     

水合物法分离生物质气化气中CO2的研究

以生物质气化气中的CO2为研究对象,研究压力、气液比、四丁基溴化铵(TBAB)浓度和洗焦废水对CO2分离效率的影响。结果表明:CO2的分离效率(分离因子)随进气压力的增大先增大后减小;随气液比的增加先减小后增大;达到水合物形成的平衡压力后,随TBAB浓度的增大而减小。较低浓度的洗焦废水由于可增加气体的溶解速率并减少水合物的诱导时间而增加水合物的形成速率。在2.1 MPa、气液比14.63、TBAB物质的量浓度为0.29%时,CO2分离效率最高,分离后气相CO2气体含量由17.85%下降到8.71%,目标气体H2、CO损失率约为5%,水合物相中CO2含量达81.63%。     

加压水洗沼气脱碳的实验研究

利用加压水洗提纯沼气小试实验装置,研究了进水流量、进气流量、吸收压力和吸收温度对沼气加压水洗脱碳过程中CO2去除率、CH4回收率和CO2饱和度等参数的影响。结果表明:增大吸收压力和降低吸收温度可显著提升加压水洗脱碳效果,增大进水流量和减小进气流量可以提高CO2去除率和产品气的纯度;CO2去除率越高,CH4回收率和产气率越低;当进水流量为100 m L/min、进气流量为800 m L/min、吸收温度为10℃、吸收压力为0.8~1.0 MPa时,产品气中的CO2含量可控制在3%以下,能够满足车用压缩天然气技术标准的要求。     

沼气微氧发酵过程硫转化及微生物群落

以水稻秸秆与猪粪为原料,探究微氧发酵过程中S元素的转化与微生物群落特征以及通氧量的影响。结果表明,厌氧发酵过程中原料的S元素约有65.7%转化为H2S进入沼气,19.0%进入发酵后的沼液,15.3%残留在沼渣中。微氧条件下,沼液中S2-的浓度(100 mg/L)远低于厌氧条件的250 mg/L,约71.8%的S元素转化为H2S然后被氧化成为S单质和少量SO42-。H2S去除效率随通氧量的增大而增大,当通氧量为11.85 L/m3沼气时,约96%的H2S被氧化脱除。根据高通量测序结果,与厌氧发酵相比,在微氧条件下,沼液中微生物多样性仅有轻微变化,比较稳定;硫氧化菌明显增多,而产甲烷菌无明显变化。较高浓度硫氧化菌的存在,有利于沼气中H2S的及时转化,可减轻H2S对产甲烷菌活性的抑制,从而促进厌氧发酵的进行。     

火电厂节能工作浅析

本文探讨了火电厂节能基本程序和工作方法,分析节能工作要从基础工作、技术创新、设备整治、燃烧管理等方面入手的论述.     

浅析磨合期汽车的使用

如何合理使用磨合期的汽车，使其摩擦机件的磨损量能够平稳、均匀地磨合而不至于过度磨损，对汽车实际使用寿命有着重要的意义。从机器磨合期的特点和磨损机理出发，对汽车磨合期如何正确使用进行了有实际意义的探讨。     

Geothermal energy in agriculture in Yugoslavia

SFR Yugoslavia has natural hot water springs practically all over its territory, indicating the presence of geothermal reservoirs underground. There is no final estimate of how much energy can be expected from this new resource, except for figures based on the results of studies and investigations.The first use of geothermal energy in Yugoslavia in numerous spas dates back to the 19th century. Some remarkable examples of central heating are known, but the most widespread use is in agriculture (in greenhouse heating, farm heating and drying of agricultural products).     

Energy conservation measures in an institutional building in sub-tropical climate in Australia

In this study, various energy conservation measures (ECMs) on heating, ventilating and air conditioning (HVAC) and lighting systems for a four-storied institutional building in sub-tropical (hot and humid climate) Queensland, Australia are evaluated using the simulation software called DesignBuilder (DB). Base case scenario of energy consumption profiles of existing systems are analysed and simulated first then, the simulated results are verified by on-site measured data. Three categories of ECMs, namely major investment ECMs (variable air volume (VAV) systems against constant air volume (CAV); and low coefficient of performance (COP) chillers against high COP chillers); minor investment ECMs (photo electric dimming control system against general lighting, and double glazed low emittance windows against single-glazed windows) and zero investment ECMs (reset heating and cooling set point temperatures) are evaluated. It is found that the building considered in this study can save up to 41.87% energy without compromising occupancies thermal comfort by implementing the above mentioned ECMs into the existing system.     

Uncertainties in decarbonising heat in the UK

Heating is arguably one of the most difficult sectors to decarbonise in the UK's energy system. Meeting the 80% greenhouse gas emission reduction target by 2050 is likely to require that heat related emissions of CO₂ from buildings are near zero by 2050, and there is a 70% reduction in emissions from industry (from 1990 levels). Though it is clear that the use of the natural gas network will reduce over time, recent modelling suggests a limited residual role for gas by 2050 to help meet peaks in heat demand. High levels of uncertainty about the way in which heat will be decarbonised present a number of challenges to policy makers. This paper will explore the risks and uncertainties associated with the transition to a low carbon heat system in the UK as outlined by the 4th carbon budget review. The potential impact of key uncertainties on the levelised costs of heat technologies and the development of energy networks are explored using a sensitivity analysis approach. Policy changes required to decarbonise the heat sector are also examined.     

Viscous heating in liquid flows in micro-channels

Many experimental works on forced convection through micro-channels evidenced that when the hydraulic diameter is less than 1 mm, conventional theory can no longer be considered as suitable to predict the pressure drop and convective heat transfer coefficients. This conclusion seemed valid for both gas and liquid flows. Sometimes the authors justified this claim by invoking “new” micro-effects. On the contrary, in this paper the explanation of the experimental results obtained for micro-channels in terms of friction factors will be researched inside the conventional theory (Navier-Stokes equations). In particular, this paper will focus on the role of viscous heating in fluids flowing through micro-channels. A criterion will be presented to draw the limit of significance for viscous dissipation effects in micro-channel flows. The role of the cross-sectional geometry on viscous dissipation will be highlighted and the minimum Reynolds number for which viscous dissipation effects can no longer be neglected will be calculated as a function of the hydraulic diameter and of the micro-channel geometry for different fluids. It will be demonstrated how viscous effects can explain some experimental results on the Poiseuille numbers in micro-channels, which recently appeared in the open literature.     

Solar drying in sludge management in Turkey

Two main wastewater treatment plants in Bursa city in Turkey will start to operate and produce at least 27,000 tons of dry solids per year by the end of 2006. The purpose of this study was to investigate an economical solution to the sludge management problem that Bursa city would encounter. The general trend in Turkey is mechanical dewatering to obtain a dry solid (DS) content of 20%, and liming the mechanically dewatered sludge to reach the legal landfilling requirement, 35% DS content. This study recommends limited liming & solar drying as an alternative to only-liming the mechanically dewatered sludge. Open and covered solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. Faecal coliform reduction was also monitored. The specially designed covered solar drying plant proved to be more efficient than the open plant in terms of drying and faecal coliform reduction. It was found that, if the limited liming & solar drying method was applied after mechanical dewatering instead of only-liming method, the total amount of the sludge to be disposed would be reduced by approximately 40%. This would lead to a reduction in the transportation, handling, and landfilling costs. The covered drying system would amortize itself in 4 years.     

Electoral cycles in electricity losses in India

A third of electricity in India is lost each year, where losses refer to power that is supplied but not billed. Utilizing data from the power corporation of Uttar Pradesh, India's most populous state, we study the politics of electricity losses. Examining annual data over four decades, we document that UP's electricity losses tend to increase in periods immediately prior to state assembly elections. Drawing upon geographically disaggregated data for the period 2000–09, we observe higher line losses just prior to the 2002 and 2007 state elections. Our analysis shows that the incumbent party was more likely to retain the assembly seat as line losses in the locality increased. We interpret these results as corroboration that political parties deliberately redirect electricity to flat rate and unbilled users in a context of chronically inadequate supply. Political factors appear to affect line losses in ways that technical and economic factors alone cannot explain.     

Energy consumption in rural transportation in India

Energy consumption in rural transportation has been computed, taking into account the energy embodied in vehicles or bullocks, as well as the fuels or feeds and food (of operators). Bullock cart transport consumes over four times more energy than vehicles. However, animal transport will continue to be preferred because of its availability.