油气田水合物形成机理及抑制剂的研究进展

通过介绍水合物的结构、形成机理及形成这种物质所带来的弊端,指出了研究合理的水合物抑制剂,在油气田发展环境保护中具有重要的理论和现实意义。同时根据水合物生成条件及主要防治措施,针对现有水合物抑制剂的种类及应用特点,提出了油气田水合物抑制剂研究的发展方向。     

肉类食品冷冻与解冻门道多

正都知道吃肉要吃新鲜的,但时常家中不可避免会储存一些冻肉。冷冻肉储存时间不宜过长,否则容易失水,导致口感变差。关于肉类的冷冻和解冻都有一些讲究。肉类冷冻讲究速度肉类在冷冻过程中,通常将肉降温到零下1度至零下5度进行储存,这个温度区间叫做"冰晶生成带",大多数水分会在这个温度结成冰。但如果长时间停留在此温度区间,冰晶会不断     

产品市场

大棚地层增温装置本装置由热管炉或普通水暖炉、管道组成加热管路,管路上装有水泵、排气管和水温计。从热管炉或普通热水炉中加热到适当温度的水,经出水口流到管道中,经土壤吸热后又流经水泵回到热管炉或普通热水炉中,从而大大提高了大棚内地层的温度,解决了棚内蔬菜...     

生活垃圾焚烧烟气再循环率影响因素研究及应用

城市生活垃圾在焚烧炉中燃烧时,会产生NO_X等一系列污染物。随着烟气排放标准的提高,如何通过燃烧技术抑制NO_X的生成成为重点。提出烟气再循环技术,即将焚烧系统中燃烧产生的部分烟气从袋式除尘器出口引至焚烧炉内,代替部分或全部二次风,与炉内烟气相互扰动并充分混合,形成还原性气氛,可抑制烟气中NO_X的生成,同时降低排烟损失,提高经济效益。通过数值模拟和设计计算,来分析影响烟气再循环率的因素;并结合实例,采用烟气再循环技术对降低NO_X的排放,提高锅炉效率所起到的显著效果。     

城市有机垃圾焚烧烟气中氮氧化物生成特性的研究

本文对城市有机垃圾经模化后,在一小型固定床燃烧炉中进行了燃烧试验,研究了燃烧温度、炉内停留时间、过剩空气系数、垃圾粒径等因素对NOx生成的影响。研究表明,NOx在燃烧温度为600－800℃的范围内生成量最大,且随着停留时间的延长、过剩空气系数的增大、粒径的减少而增大。添加CaCO3、CaO对NOx的生成有不同程度的影响。     

不同浸提条件对土壤氨氮提取数量的影响

土壤溶解性有机氮（DON）的推算是通过测试土壤全氮、氨氮和硝态氮的数量,利用全氮减去氨氮和硝态氮获得。不同区域或不同学者对DON的定义不同,在测试过程中选取多种浸提方法测定土壤氨氮,结果导致测试结果存在较大的差异。但这种差异受到何种因素控制,目前还没有形成统一的认识。基于此,研究应用正交试验方法,通过统计分析了振荡时间、浸提剂、温度以及土水比对土壤氨氮浸提数量的影响。结果表明：不同因素对氨氮浸提数量的影响程度为土水比>浸提剂>振荡时间>温度;对氨氮浸提数量分别表现为随土水比与浸提剂浓度增大而升高;在浸提温度低于50℃时,土壤氨氮的浸提数量随温度升高而升高;振荡时间在60 min内,土壤氨氮的提取数量随着振荡时间增加而增高。     

乌鲁木齐市茶浴炉生产和运行状况的调查

茶浴炉是一种小型自然引风为主的常压锅炉，生产工艺和技术要求较低，审批准建锅炉房手续简便，本市现有茶浴炉生产厂家数十家，在用茶浴炉3000台左右，主要为双层反烧式茶浴炉。这种茶浴炉以原煤为燃料，利用二次燃烧使燃料充分燃烧，提高热效率，减少烟尘的排放。我们在调查中发现，若产品质量不过关或违章操作，会造成茶浴炉非正常燃烧，导致烟尘排放浓度严重超标，从而加剧城市大气污染。卫茶浴炉的基本结构和燃烧原理1．l基本结构反烧式茶浴炉炉体分为上、下两层炉排，上层为钢管水冷炉排，下层为铸铁炉排。水冷炉排上设有加煤门，两层…     

气体水合物在海洋中的分布及其赋存区域的海洋地质特征

气体水合物是一种潜在的新型能源，在资源开发、环境保护和全球气候变化等方面具有重要的意义。通过对DSDP、ODP、IODP的大量资料和国际其它最新资料的综合分析，揭示了气体水合物在海洋中的分布规律，即主要分布在主动陆缘的增生楔区、被动陆缘的近海区域和泥火山分布区。阐明了气体水合物赋存区域的沉积速率、沉积物的有机碳含量、沉积物的粒度、水动力条件和海洋生产力等海洋地质特征。     

基于SNCR工艺的水泥窑烟气脱硝技术

<正>由洁华控股股份有限公司开发的基于SNCR工艺的水泥窑烟气脱硝技术,适用于水泥回转窑烟气脱硝。主要技术内容一、基本原理利用压缩空气将雾化后的还原剂(18%~25%的氨水或30%~50%的尿素溶液)喷入水泥分解炉合适温度区域(850℃~1050℃),将NOx还原转化成N_2和H_2O。当温度低于800℃时,NH_3与NO的反应速度变慢,会导致大量未反应的氨形成逃逸。当反应区温度高于     

烟气回流工艺在垃圾焚烧系统NOX减排中的工程应用分析

为有效抑制生活垃圾在机械炉排炉焚烧过程中NO_X的产生,有研究者提出采用烟气回流技术可以有效抑制NO_X的生成和排放。目前关于烟气回流技术的理论研究和数值模拟较多,而基于实际工程应用的研究较少。选择了烟气回流工艺在山东省某生活垃圾焚烧项目上的应用情况进行研究,从烟气回流工艺的技术原理、排放指标、运营数据和经济性等方面进行了分析,同时也总结了本工艺在应用过程中需注意的事项。研究表明,采用烟气回流工艺的#3炉引风机出口NOX平均排放和氨水平均用量比未采用烟气回流工艺的#1炉,分别降低了25.8%和43.7%,且NO_X浓度波动与烟气含氧量密切相关。总体上,烟气回流工艺的使用能够有效抑制NOX_的产生,并且同时减少了氨水等物料的消耗,降低了运营的成本。但是当进入焚烧炉的垃圾品质出现急剧恶化的情况下,会影响焚烧炉的燃烧工况而使烟气回流量降低,导致NOX减排效果下降。     

A new apparatus to enhance the rate of gas hydrate formation: Application to capture of carbon dioxide

A new apparatus employing a modular, mechanically agitated gas-inducing crystallizer is used to demonstrate the capture of CO₂ via hydrate crystallization. The crystallizer enhances the contact of hydrate forming gases with water and thus the rate of hydrate crystallization increases. Flue gas (CO₂/N₂) and fuel gas (CO₂/H₂) mixtures were used to represent post- and precombustion capture. A comparison between the rates of hydrate formation in different crystallizers is presented by defining a metric called the normalized rate of hydrate formation. The gas uptake and the separation efficiency for the fuel and flue gas mixtures were found to be greater compared to the results obtained in a smaller scale stirred tank reactor (Kumar et al., 2009c, Linga et al., 2008). The gas uptake and CO₂ recovery for flue gas mixture in the presence of THF obtained in this work was higher than that reported in the literature with tetra-n-butyl ammonium bromide and tetra-n-butyl ammonium fluoride (Fan et al., 2009, Li et al., 2009). Although hydrate crystallization is able to capture CO₂, the power required for mechanical agitation was found to be very significant. If the hydrate process is to be used industrially then hydrate crystallization must be carried out without mechanical agitation.     

站场伴生气减排回收工艺研究与应用

伴生气的回收利用一直是油田生产中长期以来存在的难点问题。针对部分油田站场因伴生气量低造成的燃烧排放或无效放空的生产现状，研制了一种基于双U型管气液分离、气体过滤、阀前调压稳压和止回阀的组合式回收装置。对组合式回收装置进行了功能测试，并在17座站场现场应用，供气系统压力平稳，加热炉正常运行，实现了低气油比站场伴生气100%回收利用，有利于油田安全环保、节能减排与清洁生产。     

Capture of carbon dioxide from flue or fuel gas mixtures by clathrate crystallization in a silica gel column

A column of silica gel was employed to contact water with flue gas (CO₂/N₂) mixture to assess if CO₂ can be separated by hydrate crystallization. Three different silica gels were used. One with a pore size of 30 nm (particle size 40–75 μm) and two with a pore size of 100 nm and particle sizes of 40–75 and 75–200 μm respectively. The observed trends indicate that larger pores and particle size increase the gas consumption, CO₂ recovery, separation factor and water conversion to hydrate. Thus, the gel (gel #3) with the larger particle size and larger pore size was chosen to carry out experiments with concentrated CO₂ mixtures and for experiments in the presence of tetrahydrofuran (THF), which itself is a hydrate forming substance. Addition of THF reduces the operating pressure in the crystallizer but it also reduces the gas uptake. Gel #3 was also used in experiments with a fuel gas (CO₂/H₂) mixture in order to recover CO₂ and H₂. It was found that the gel column performs as well as a stirred reactor in separating the gas components from both flue gas and fuel gas mixtures. However, the crystallization rate and hydrate yield are considerably enhanced in the former. Finally the need for stirring is eliminated with the gel column which is enormously beneficial economically.     

Kinetic of formation for single carbon dioxide and mixed carbon dioxide and tetrahydrofuran hydrates in water and sodium chloride aqueous solution

A laboratory-scale reactor system is built and operated to measure the kinetic of formation for single and mixed carbon dioxide–tetrahydrofuran hydrates. The T-cycle method, which is used to collect the kinetic data, is briefly discussed. For single carbon dioxide hydrate, the induction time decreases with the increase of the initial carbon dioxide pressure up to 2.96 MPa. Beyond this pressure, the induction time is becoming relatively constant with the increase of initial carbon dioxide pressure indicating that the liquid phase is completely supersaturated with carbon dioxide. Experimental results show that the inclusion of tetrahydrofuran reduces the induction time required for hydrate formation. These observations indicate hydrate nucleation process and onset growth are more readily to occur in the presence of tetrahydrofuran. In contrast, the presence of sodium chloride prolongs the induction time due to clustering of water molecules with the ions and the salting-out effects. It is also shown that the degree of subcooling required for hydrate formation is affected by the presence of tetrahydrofuran and sodium chloride in the hydrate forming system. The presence of tetrahydrofuran in the hydrate system significantly reduces the amount of carbon dioxide uptake. The apparent rate constant, k, for those systems are reported.     

站场伴生气减排回收工艺研究与应用

针对部分油田站场因伴生气量低造成的燃烧排放或无效放空的生产现状,研制了一种基于双U型管气液分离、气体过滤、阀前调压稳压和止回阀的组合式回收装置。对组合式回收装置进行了功能测试,并在17座站场现场应用,供气系统压力平稳,加热炉正常运行,实现了低气油比站场伴生气100%回收利用,有利于油田安全环保、节能减排与清洁生产。     

Hydrate formation during CO2 transport: Predicting water content in the fluid phase in equilibrium with the CO2-hydrate

In order to evaluate the risk of hydrate formation in CO₂ transport one has to be able to predict the water content in the fluid phase in equilibrium with the CO₂-hydrate. A literature review has identified some knowledge gaps, for example, there are no results available at temperatures lower than 243.15 K (?30 °C); and none of the models found in literature predicts the water content with high accuracy. A model based on equality of water fugacity in fluid and hydrate phase is presented here and used for the predictions of water content in equilibrium with hydrates. Although this model gives better accuracy in the overall temperature and pressure ranges of measurements than the models found in the literature, it is not accurate enough to satisfy the requirements of CO₂ transport. The simulation results also show that it is possible to form hydrate at low water content, such as x_w = 50 vppm, if temperature is low enough. In order to verify the results and improve the model accuracy further, more experimental data in a larger temperature and pressure region are required.     

Dynamis CO2 quality recommendations

In the carbon capture and storage (CCS) chain, transport and storage set different requirements for the composition of the gas stream mainly containing carbon dioxide (CO₂). Currently, there is a lack of standards to define the required quality for CO₂ pipelines. This study investigates and recommends likely maximum allowable concentrations of impurities in the CO₂ for safe transportation in pipelines. The focus is on CO₂ streams from pre-combustion processes. Among the issues addressed are safety and toxicity limits, compression work, hydrate formation, corrosion and free water formation, including the cross-effect of H₂S and H₂O and of H₂O and CH₄.     

An updated assessment of the acute impacts of ocean carbon sequestration by direct injection

This paper evaluates the expected environmental impact of several promising schemes for ocean carbon sequestration by direct injection of CO₂, and serves as a major update to the assessment by Auerbach et al. (1997) and Caulfield et al. (1997) of water quality impacts and the induced mortality to zooplankton. Three discharge approaches are considered, each designed to maximize dilution over the water column: a point release of negatively buoyant CO₂ hydrate particles from a moving ship; a stationary point release of CO₂ hydrate particles forming a sinking plume; and a long, bottom-mounted diffuser discharging buoyant liquid CO₂ droplets. Two of these scenarios take advantage of the enhanced dilution offered by CO₂ hydrate particles, and are based on recent laboratory and field studies on the formation and behavior of such particles. Overall, results suggest that it is possible with present or near present technology to engineer discharge configurations that achieve sufficient dilution to largely avoid acute impacts. In particular, the moving ship hydrate discharge is identified as the most promising due to its operational flexibility. In addition to lethal effects, sub-lethal and ecosystem effects are discussed qualitatively, though not analyzed quantitatively. Our main conclusion is that ocean carbon sequestration by direct injection should not be dismissed as a climate change mitigation strategy on the basis of environmental impact alone. Rather, it can be considered as a viable option for further study, especially in regions where geologic sequestration proves impractical.     

气田水回注的水质问题及回注井选择

气田水回注是解决气田水对环境污染的有效途径。由于气田水矿化度高，硫化物及悬浮物含量也高，如果不经处理就回注，将直接影响回注效果。文中探讨了气田水水质与回注量的关系，并且介绍了回注井的选择原则。