单盘外浮顶油罐自动通气阀溢油的原因分析

简要介绍了外浮顶油罐自动通气阀的结构形式和工作原理，将外浮顶罐浮盘未升起时浮盘与罐底之间的油气空间类比标准固定，顶罐容积确定热影响容积进行储罐通气量及通气阀通气面积的计算，根据流体稳定流动量方程推导出油品进入自动通气阀阀体内的高度计算公式，确定自动通气阀在通气面积一定时阀杆必须具有的设计高度，进而分析出一些已建油罐可能由于通气阀通气面积不够或阀杆设计高度不足而产生溢油的原因和今后设计应注意的问题。     

国内外浮顶储罐导电片放电实验对比分析

通过对比分析API RP 545与安全工程研究院针对浮顶储罐导电片开展的模拟雷击放电实验及结论,认为安全工程研究院设计的实验方案更符合储罐的实际运行状况依据实验结果提出了取消二次密封上的导电片、在浮盘与罐壁之间采用多个可伸缩式接地装置替代现有导电片的改进措施,技术方案可行,便于检查和维护,更安全可靠.     

大型储罐铝制内浮顶的结构分析

根据国家石油战略储备的需要，成品油罐正在向大型化趋势发展，大型铝制内浮项的应用愈显其重要价值。目前国内使用的铝制内浮顶有多种结构，通过了解、调研国内铝制内浮项的设计、生产、制造及使用情况，比较它们各自的优缺点，以求设计，生产出新型、节能的大型铝制内浮顶。     

外浮顶对大型立式储液罐地震反应影响分析

为了减轻大型外浮顶立式储液罐在地震灾害中的损失,基于ANSYS软件建立了考虑液体晃动和罐底提离的大型外浮顶立式圆柱形储液罐有限元模型,计算了地震作用下不同形式浮顶(平浮顶、正锥形,倒锥形)的大型外浮顶储油罐的动力响应.数值分析结果表明,地震荷载作用下,外浮顶对大型立式储液罐地震反应影响不可忽视,浮顶可以减轻液面晃动,但也会增加液体提离高度.不同形式的外浮顶对大型立式储液罐地震反应影响程度不同,平浮顶为最优浮顶形式.     

浮顶储罐的焊接变形与防治措施

浮顶储罐的浮舱顶板是整个罐体中厚度最薄的部位,也是储罐焊接施工中最易产生焊接变形的部位。浮舱顶板的焊接变形与浮顶的结构、组装、焊接顺序及焊接工艺方法等相关。由于浮舱顶结构较复杂,其焊接顺序与罐底幅板的焊接顺序有较大差别的。防止浮舱顶板的焊接变形应从结构设计、组装顺序、焊接顺序、焊接工艺等方面着手。对已产生的变形,应选择正确的方法进行校正和补救。     

立式浮顶储罐基础隔震地震响应研究

为研究浮顶储罐基础隔震地震响应问题,将浮顶假定为均质刚性圆板,波高振动形式受浮顶约束假设为沿半径线性分布.由速度势理论出发,建立液体运动势函数、基底剪力、倾覆力矩表达,由板振动理论建立浮顶运动方程,由能量原理建立罐体运动控制方程.采用时程分析方法研究了浮顶储罐基础隔震的地震响应,数值结果表明：隔震基频宜取2～3rad/...     

大型外浮顶立式储液罐被动控制方法

为了减轻大型外浮顶立式储液罐在地震灾害中的损失,基于ANSYS软件建立考虑液体晃动和罐底提离的外浮顶立式储液罐有限元模型,并将被动耗能技术引入大型外浮顶立式储液罐抗震分析中,在罐壁与浮顶之间分别安装摩擦阻尼器和粘滞阻尼器.数值分析结果表明,储液罐液体晃动幅度、罐壁竖向压应力和环向拉应力、罐底提离高度都有不同程度的减小.说明在罐壁与浮顶之间安装摩擦阻尼器或粘滞阻尼器可以减轻储液罐地震灾害,从而有效提高外浮顶立式储液罐抗震能力.     

干气密封在重整循环氢压缩机上的应用

介绍了催化重整装置循环氢压缩机所改用的干气密封的结构、工作原理及控制系统,以及由浮环密封改用干气密封的主要改造内容和改造后的使用情况．     

桩基施工中常见质量问题及应对措施

基础作为建筑物的重要组成部分,施工质量的好坏对建筑物的结构安全、使用寿命及功能都有重要影响.为了保证建筑产品达到预期的建造效果,从桩基础施工中常见的质量问题入手,针对桩基础施工中的桩塌孔、钢筋笼上浮、钻孔偏斜、桩缩孔、桩头质量差、钻头被卡及桩顶标高不足等问题及其形成原因进行剖析,并提出了相应的预防措施.     

发散型阶梯式磁流体密封的磁场有限元分析

阶梯式磁流体密封结构是一种在阶梯式迷宫密封基础上提出的用以提高普通磁流体密封耐压能力的新型密封结构.为了在阶梯式磁流体密封结构密封间隙内获得最大磁能积,在阶梯式磁流体密封理论的基础上,对一种具有二级磁源的发散型阶梯式磁流体密封结构进行了磁路设计,同时采用有限元法数值计算出密封间隙内的磁场分布从而计算出阶梯式磁流体密封耐压能力,并对计算结果进行了分析和讨论.结果表明:发散型阶梯式磁流体密封耐压能力随着径向密封间隙的增大而减小;永磁体与极靴结合处的漏磁是导致磁路法设计的发散型阶梯式磁流体密封结构耐压能力偏高的原因.     

Instability characteristics of the cracked roof rock beam under shallow mining conditions

To establish the movement relationship for the roof breaking under shallow mining conditions, the mechanical model of the roof rock beam was built, then the structure instability process of the roof rock beam was analyzed. The changing criterion of the vertical displacement was established and the relationship between the deflection and the rotary motion of roof block was determined. Regarding a mining face in Shangwan Mine, the responsing laws of the deflection and horizontal thrust of the roof rock beam were obtained through FLAC3D numerical analysis. The results show that the structure instability of the cracked roof rock beam depends on the interaction between the vertical load and the horizontal thrust.For the roof rock beam, when the vertical load keeps constant, the horizontal thrust fluctuating rises with increasing deflection. The horizontal thrust increases constantly with the deeper buried depth and the smaller span.     

A robust approach to identify roof bolts in 3D point cloud data captured from a mobile laser scanner

Roof bolts such as rock bolts and cable bolts provide structural support in underground mines. Frequent assessment of these support structures is critical to maintain roof stability and minimise safety risks in underground environments. This study proposes a robust workflow to classify roof bolts in 3 D point cloud data and to generate maps of roof bolt density and spacing. The workflow was evaluated for identifying roof bolts in an underground coal mine with suboptimal lighting and global navigation satellite system(GNSS) signals not available. The approach is based on supervised classification using the multi-scale Canupo classifier coupled with a random sample consensus(RANSAC) shape detection algorithm to provide robust roof bolt identification. The issue of sparseness in point cloud data has been addressed through upsampling by using a moving least squares method. The accuracy of roof bolt identification was measured by correct identification of roof bolts(true positives), unidentified roof bolts(false negatives), and falsely identified roof bolts(false positives) using correctness, completeness, and quality metrics. The proposed workflow achieved correct identification of 89.27% of the roof bolts present in the test area. However, considering the false positives and false negatives, the overall quality metric was reduced to 78.54%.     

Application of coal mine roof rating in Chinese coal mines

The coal mine roof rating(CMRR) is a measure of roof quality or structure competency for bedded roof types typically of underground coal mines. The CMRR has been used widely in the US, South Africa,Canada and Australia. In order to investigate the application of the CMRR system in Chinese coal mines,two coal mines in China located in Panjiang Coal Field in Guizhou Province were investigated. Field data were collected which is required to calculate the CMRR value based on underground exposure. The CMRR values of 11 locations in two coal mines were calculated. The investigations demonstrated that the chance of mine roof failure is very low if the CMRR value is more than 50, given adequate support is installed in mine. It was found that the CMRR guideline are useful to preliminarily investigate stability in Panjiang Coal Field mines.     

Fixed-length roof cutting with vertical hydraulic fracture based on the stress shadow effect: A case study

Pre-driven longwall retracement roadway (PLRR) is commonly used in large mine shaft. The support crushing disasters occur frequently during the retracement, and roof management is necessary. Taking the 31107 panel as research background, the roof breaking structure of PLRR is analyzed. It is concluded that the roof cutting with vertical hydraulic fracture (HF) at a specified position, that is, fixed-length roof cutting, can reduce support load and keep immediate roof intact. The extended finite element method (XFEM) is applied to simulate hydraulic fracturing. The results show that both the axial and transverse hydraulic fracturing cannot effectively create vertical HFs. Therefore, a novel construction method of vertical HF based on the stress shadow effect (SSE) is proposed. The stress reversal region and HF orientation caused by the prefabricated hydraulic fracture (PF) are verified in simulation. The sub-vertical HFs are obtained between two PFs, the vertical extension range of which is much larger than that of directional hydraulic fracturing. The new construction method was used to determine the field plan for fixed-length roof cutting. The roof formed a stable suspended structure and deformation of the main PLRR was improved after hydraulic fracturing.     

粗放式屋顶绿化的热惰性

屋顶绿化的热工性能是进行建筑节能工程设计和评价的依据,但目前对屋顶绿化热工性能的研究很少关注热情性.以一种粗放式屋顶绿化在自然通风状态下连续5个月的对比测量数据为依据,采用统计分析方法研究了屋顶绿化对气候热作用波动的衰减和延迟特性.结果表明,绿化屋顶与裸屋顶相比,对气候热作用波动的平均衰减倍数提高了1倍以上,延迟时间有所减少.     

钢弹簧浮置板隔振道路的模态分析

为了减小道路交通汽车荷载对广州市番禺万博商务中心地下空间结构产生的低频振动影响，研发一种新型的钢弹簧浮置板隔振道路。应用ANSYS软件分别建立钢弹簧浮置板、地下空间、浮置板和地下空间结构的三维有限元模型，对这3种不同结构进行模态分析，并进一步研究了传导比。结果表明：设计的浮置板道路基频为8.69 Hz；地下空间基频为15.69 Hz；浮置板与地下空间整体结构基频为7.33 Hz；从振型上看，低频时主要体现为浮置板的振动，中高频时主要为地下空间结构顶板的振动；3种结构的传导比峰值均出现在第一阶固有频率附近，地下空间结构在增加钢弹簧浮置板后传导比最大为0.878。钢弹簧浮置板道路可起到良好的隔振效果。     

Mechanical analysis of roof stability under nonlinear compaction of solid backfill body

Based on the compaction characteristic test and the nonlinear compaction deformation characteristics of backfill material, this paper applies the theory of nonlinear elastic foundation of thin plate to establish a mechanical model of backfill body and roof in solid dense backfill coal mining. This study critically analyses the deflection equation of the roof by the energy method, derives the conditions of roof breakage and combined with concrete engineering practice analyses, determines roof movement regularity and stability in solid dense backfill mining. Analysis of the engineering practice of the 13,120 backfill panel of Pingmei 12# mine shows the theoretical maximum of roof convergence in backfill mining to be415 mm which is in significant agreement with the measured value. During the advancing process of solid backfill mining at the panel, the maximum tensile stress on the roof is less than its tensile strength which does not satisfy the conditions for roof breakage. Drilling results on the roof and ground pressure monitoring show that the integrity of roof is strong, which is consistent with the theoretical calculations described in this study. The results presented in the study provide a basis for further investigation into strata movement theory in solid dense backfill mining.