The dynamic response of pressure relief valves in vapor or gas service. Part II: Experimental investigation

An experimental testing program designed to evaluate the opening stability characteristics of direct acting pressure relief valves (PRV) in gas/vapor service is described. Three different valve sizes from each of three different manufacturers were tested at two different set pressures to determine their opening characteristics (disk lift vs. time). The valves were tested with several different lengths of inlet piping as well as with and without discharge piping to determine the conditions under which unstable operation (chatter) would occur. Part I of this program described a mathematical model for predicting the dynamic response of PRV's, and the data described in this test program were used to evaluate the accuracy of the model, as described in Part III of this study to follow.     

基于支持向量机的采空区稳定性分级

针对采空区稳定性分级的影响因素众多且关系复杂的特点,提出采用支持向量机理论对采空区稳定性进行分级。根据分级评价指标选取原则,选取岩体结构、地质构造、岩石的质量指标、地下可见水、地下水体、周边开采的影响、相邻空区的情况、工程布置、跨度、面积、高度、矿柱的尺寸及布置、埋藏深度和采空区的规格14个影响因子,建立了采空区稳定性评价指标体系,引入支持向量机理论,选择有向无环图方式构造多类分类器,得到采空区稳定性分级的支持向量机模型。将该模型用于山东黄金矿业西山矿区的25个采空区进行分级,并与未确知测度方法的分级情况     

The influence of slope collapse on water exchange between a pit lake and a heterogeneous aquifer

Slope collapse will reduce the water exchange. Slope collapse will affect the spatial distribution of the water exchange. Precipitation have the most impact on the dynamics of the water exchange. Due to the increase in open pit mining, pit lakes have become common surface water features, posing a potential risk to subsurface aquifer. In this study, a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package. For the first time, the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level. Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m³/a without collapse of the pit lake slope, while the total net water exchange under slope collapse conditions is 248000 m³/a (i.e., a reduction of 1.40-fold). The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April, shifting to negative values in zone IV from June to August and in zone V in June and July. Moreover, the monthly net water exchange per unit width decreases from north to south, and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse.     

某大型地下洞室群围岩稳定性工程地质评价

某水电站布置有大型的地下洞室群,其规模在国内外已建和拟建的工程中都是十分罕见的。总体上说,地下厂房区岩体质量较好,但由于多期的构造作用,在厂房区岩层中发育有不同级别的结构面,对围岩的稳定性有一定影响。对此,本文运用围岩分类法和数值模拟法分析了厂房开挖后围岩的整体稳定性,然后运用UNWEDGE软件对主厂房顶拱部位的不稳定块体进行了分析评价。     

新疆博格达山北坡表土花粉散布特征

基于博格达山北坡68个表土样品花粉组合特征,对比植物群落样方调查结果,借助聚类分析、主成分分析方法,探讨了表土花粉组合与现代植被分布的关系。研究表明,(1)博格达山北坡表土花粉可划归5个不同植被带,湿度是影响其分布的主要因素,藜科(Chenopodiaceae)、蒿属(Artemisia)、云杉属(Picea)花粉分布受气流影响显著,忽略它们对其他植被带花粉组合的干扰,表土花粉与现代植被分布对应良好。各植被带均有其特有的花粉组合方式,山地荒漠带藜科-蒿属组合占绝对优势,山地草原带演替为蒿属-藜科-禾本科(Poaceae)-蔷薇科(Rosaceae)组合,山地森林带以云杉属-桦木属(Betula)-蒿属-藜科-禾本科为主,高山草甸带以蒿属-云杉属-藜科-莎草科(Cyperaceae)组合为特征,高山垫状植被带表现为蒿属-藜科-蔷薇科-云杉属组合。(2)草本植物花粉含量(62.7%)优势明显,乔、灌木(37.3%)次之。蒿属(23.1%)、藜科(21.5%)、云杉属(18.1%)、莎草科(9.4%)、禾本科(8.6%)、桦木属(5.7%)、蔷薇科(5.3%)等科(属)含量高、变幅大,为最主要的花粉类型,可作为古气候研究的重要依据,藜科、蒿属产量大、易传播,表现出超代表性,云杉属代表性较好,莎草科则受自身结构及保存条件等多重因素影响呈低代表性。(3)蒿属/藜科(A/C)比值不仅能将山地荒漠带、山地草原带区分开,还能指示研究区域湿度变化,古环境重建时可作为区域有效湿度的代用指标。     

Promotional effect of ion-exchanged K on the low-temperature hydrothermal stability of Cu/SAPO-34 and its synergic application with Fe/Beta catalysts

• K⁺ hinder the structural degradation of Cu/SAPO-34 under humid condition<100°C. • K⁺ on Cu/SAPO-34 brings lower acidity and inferior SCR activity at high temperature. • Fe/Beta was used to compensate the low activity of Cu/SAPO-34 at high temperature. • The hybrid catalysts with KCu/SAPO-34 and Fe/Beta show a great potential for using. K ions were introduced onto Cu/SAPO-34 catalysts via the ion-exchange process in order to improve their stability under low-temperature hydrothermal aging. The changes in structure and copper-species contents of these catalysts upon hydrothermal aging were probed in order to investigate their effects on selective catalytic reduction (SCR) activity. For the fresh Cu/SAPO-34 catalysts, K ions had little influence on the chabazite framework but effected their acidities by exchanging with acid sites. After hydrothermal aging, the structural integrity and amount of active sites decreased on pure Cu/SAPO-34. While the K-loaded catalysts showed improved chabazite structure, acidity, and active site conservation with increasing K loading. However, although the 0.7 wt% K catalyst maintained the same crystallinity, active site abundance, and low-temperature SCR activity as the fresh catalyst upon aging, an apparent decrease in SCR activity at high temperature was observed because of the inevitable decrease in the number of Brönsted acid sites. To compensate for the activity disadvantage of K-loaded Cu/SAPO-34 at high temperature, Fe/Beta catalysts were co-employed with K-loaded Cu/SAPO-34, and a wide active temperature window of SCR activity was obtained. Thus, our study reveals that a combined system comprising Fe/Beta and K-loaded Cu/SAPO-34 catalysts shows promise for the elimination of NO_x in real-world applications.     

基于演化博弈的危化品安全监管情景推演研究

针对危化品安全生产监管问题,基于演化博弈理论构建危化品安全监管演化博弈模型,并将危化品事故发生率引入模型,对比分析危化品企业与地方政府监管部门行为策略的演化稳定均衡。在此基础上进行情景推演模拟仿真,研究表明:危化品事故发生率,对危化品企业和地方政府监管部门的策略选择有显著影响,当危化品事故发生概率低于某一临界值时,危化品企业和监管部门都会疏忽安全投入和监管;地方政府承受危化品事故经济损失和信誉损失增大时,危化品安全监管系统演化呈现出周期性波动;引入上级政府惩罚机制情景下,当上级政府惩罚力度高于危化品企业未投入安全生产受到的处罚和地方政府安全监管成本时,其最终都选择安全投入和严格监管策略。研究结论为政府监管危化品安全生产提供新的思路和对策建议。     

弓长岭露天铁矿采空区稳定性及预警研究

采空区对露天矿的安全生产具有极大的威胁。针对弓长岭露天矿众多已探明的采空区进行了稳定性分析。对露天矿日常的爆破作业进行了爆破测振,统计回归出萨道夫斯基经验公式参数,获得了爆破振动对空区产生的荷载。建立了采空区顶板三铰拱承载的力学模型,推导了空区顶板稳定性的判据。利用数值模拟方法,计算拱形空区在不同荷载作用下稳定性,对弓长岭露天铁矿已探明各空区进行了预警,为弓长岭露天矿处理空区及安全生产提供依据。     

露天转地下开采对复合边坡稳定性影响的评价

露天矿深部资源开采因受到剥采比等因素的制约需要转为井工矿开采;从采掘空间位置分布关系来看,边坡体位于地下采动影响域内,由此造成了两种采动效应的相互作用,并构成复合叠加效应,使得边坡稳定性受到严重影响,一旦产生滑坡将严重影响周边环境的安全或诱发次生灾害。以某矿的开采工程实践为背景,针对地下开采作用下山体与露天边坡的稳定性进行了研究,系统分析了露天坡和山峰外侧边坡的稳定性,并对滑坡可能产生的后果及其次生灾害进行了分析,从而为矿山安全生产和防控提供了决策依据     

不同碳源种类对好氧颗粒污泥合成PHA的影响

影响好氧颗粒污泥稳定性的因素众多,其中碳源种类的不同会造成好氧颗粒污泥合成聚羟基烷酸酯(PHA)的不同,进而影响其稳定性能.采用混合碳源驯化培养的好氧颗粒污泥进行试验.考察了厌氧条件下,乙酸钠等八种碳源对好氧颗粒污泥合成PHA的影响.结果表明,颗粒污泥对乙酸钠和蔗糖具有较好的转化能力,合成PHA的量分别为102.19mgCOD/g·VSS和70.58mgCOD/g·VSS,显著高于其他碳源的PHA合成量(5~26mg/g×VSS).故以蔗糖和乙酸钠作碳源均有利于颗粒污泥稳定性能的维持,而当以甲醇作碳源时好氧颗粒污泥的贮存能力最差.