浅析内浮顶会属油罐油量计算方法

计算内浮顶金属油罐油量时,不仅要考虑油品的液高、密度、温度,而且要考虑浮顶在罐内的状态,即分析浮顶完全起浮状态、浮顶介于浮顶最低点与起浮高度之间的状态、浮顶完全未起浮状态,从而按照不同情况对浮顶质量进行扣除.     

从传热学角度分析影响储罐计量准确度的因素

温度是影响油量计量准确度的重要参数。国内长期以来对如何确定罐壁平均温度和罐内油品温度代表性的问题,始终没有一个科学的、指导实践应用的测量和计算方法。文章从工程热力学和传热学的角度,通过研究油品储运过程中罐壁、罐内油品和大气环境间的热能传递规律,探索影响储罐静态计量准确度的各种因素,通过建立数学模型,推导分析传热过程温度场的变化和各种状态环境下罐壁平均温度、油品平均温度以及计量处理方法的合理性和取值规律。     

浮顶油罐加热过程的数值模拟

为掌握浮顶油罐内的温度分布,提高加热效率,进行了浮顶油罐内原油加热过程的传热研究。以某2×10~4m~3的单盘浮顶罐为例,基于对浮顶罐加热过程的分析,结合传热学理论,建立了单盘浮顶油罐二维加热模型,应用FLUENT软件对原油加热过程与流动进行了仿真模拟,得到了原油不同加热时间后的温度分布以及原油流场分布,结果表明:原油加热过程中由于自然对流,在浮顶罐内产生漩涡,在罐壁底部流速较低;浮顶罐中心区域内原油温度分布均匀,加热管、罐壁和浮顶下部温度较高。     

浅析内浮顶金属油罐油量计算方法

计算内浮顶金属油罐油量时，不仅要考虑油品的液高、密度、温度，而且要考虑浮顶在罐内的状态，即分析浮顶完全起浮状态、浮顶介于浮顶最低点与起浮高度之间的状态、浮顶完全未起浮状态，从而按照不同情况对浮顶质量进行扣除。[第一段]     

立式金属罐静态计量交接不确定度分析

一、立式金属罐静态计量交接不确定度数学模型 1.交接油品质量△m的数学模型 根据静态计量交接流程,可以得到交接油品质量△m的数学模型为△m=m1-m2={(VB1+△VSP1×d20前4)×[1+3α(t罐1-20)]×VCF1×(ρ20前-1.1)-G}×(1-Ws1)-{(VB2+△VSP2×d20后4)×[1+3α(t罐2-20)]×VCF2×(ρ20后-1.1)-G}×(1-Ws2) (1) 式中:△m——油品计量交接质量值,kg;VB1-前尺液位高度下的总表载体积,m3;△VSP1——前尺罐内液位高度下装水引起的静压力容积增大值,m3;d0前4——前尺罐内油品密度与4℃纯水密度(取1000kg/m3)比值;α——油罐材质线膨胀系数(碳钢—般取0.000012,1/℃);t罐1——前尺罐壁温度,℃(用初始罐内油温代替);VCF1——前尺温度、密度下查得的体积修正系数;ρ20——罐内油品标准密度,kg/m3;G——罐内浮顶的质量,kg;Ws1——前尺罐内油品的含水率,％;VB2——末尺液位高度下的总表载体积,m3;△VSP2——末尺罐内液位高度下装水引起的静压力容积增大值,m3;d20后——末尺罐内油品密度与4℃纯水密度(取1000kg/m3)比值;t罐2——末尺罐壁温度,℃(用末尺罐内油温代替);VCF2——末尺温度、密度下查得的体积修正系数;Ws2——罐内油品的含水率,％.     

立式金属罐浮顶质量测量方法探讨

立式金属罐浮顶质量的测量是浮顶罐检定的主要部分之一，其测量结果误差的大小直接影响被检罐的测量不确定度。按照JJG168—1987《立式金属罐容量(试行)》检定规程规定的浮顶质量的测量方法对5万m^3浮顶罐进行周期检定，用已标定的浮顶罐。罐内盛装石油，测量被检浮顶罐浮顶质量时发     

关于立式浮顶金属罐容量检定中底量与浮顶摩擦力误差的探讨

<正>目前,兰州石化公司原油计量大部分仍然依靠贮存立式浮顶金属罐的体积计量,加上相应的温度、密度和含水量测定方法来实现。本文主要探讨立式浮顶金属罐测量中罐底量和浮顶摩擦力对测量结果的影响,以期在当前条件下能进一步提高油品的体积计量准确度。一、罐底变形对体积计量的影响立式浮顶金属罐施工及验收规范中对已建成的罐有相应要求,按照规范,对于建成的罐,由于基础质     

正确处理外浮顶立式金属计量罐的油量计算

随着我国石油工业的不断发展．油品贸易也趋向国际化。而做为油品储存及计量的重要工具——立式金属计量罐也向着具有储存量大、密封性能好、安全可靠、便于维修等特点发展。而外浮顶立式金属计量罐恰恰具备了这些特点。     

大型油气储罐的结构型式与变化趋势

大型储罐分为外浮顶储罐和固定顶储罐,固定顶储罐包括锥顶储罐和拱顶储罐两种型式.目前国际上储存原油是浮顶储罐和固定顶储罐并用,但外浮顶已逐渐减少;储存液化气主要用球罐和立式圆筒型低压储罐.中国储存原油主要用外浮顶储罐,储存液化气的方式与国际上一致.     

大型内浮顶储罐固定拱顶的整体吊装

针对单罐容积5万m3的内浮顶储罐的施工过程中,分别选取储罐通常所用的倒装法和正装法的各自优点,即罐底和罐壁采用正装施工工艺,罐顶则采用预制后整体吊装的施工工艺,以达到提高施工效率、缩短施工周期、确保安全的目的。     

浮子卷套水箱设计及其内部运动与传热传质特性研究

许多热泵系统水箱中存在冷热水直接接触造成的不可逆热损失,为减小此项损失。设计制作了一种新型浮子卷套水箱,该水箱中的浮子卷套结构将冷热水分隔在两个腔中,避免了冷热水直接接触。实验测试了水箱内部浮子的运动特性、供热水时水温变化过程和水箱上下腔之间的传质特性;实验结果表明浮子卷套可在水箱中上下自由运动,浮子静止时漂移量小、运动时速度稳定;浮子卷套结构有效减小了水箱内部热损失;但目前设计的浮子卷套水箱上下腔之间仍存在少量传质渗漏,浮子卷套的材料和制作需进一步改进。     

大型LNG储罐罐底保冷层结构优化研究

针对大型LNG储罐罐底漏热量大及基础保冷性能差等问题,对储罐底部保冷结构进行了优化,并对不同储罐底部基础的温度场分布和漏热量进行了数值模拟和现场对比分析。结果表明:储罐冷损失与泡沫玻璃砖厚度呈双曲线函数关系,在内外壁温差为185 K时泡沫玻璃砖保冷层厚度设置为600 mm保冷效果显著,再增加厚度时保冷损失减小缓慢;储罐基础采用夯土基础时保冷性能优于柱桩基础,而夯土基础需在罐底设置加热系统,因此工程上大型LNG储罐需根据实际情况进行选择。     

Thermomechanical response of LNG concrete tank to cryogenic temperatures

The reinforced concrete tanks for liquefied natural gas storage, which have many advantages over steel tanks (high resistance to cryogenic temperatures and thermal shock, fatigue and buckling, fire resistance, etc.), are analyzed. Since the main drawback of concrete tanks is their poor resistance to tensile stresses, in order to investigate the thermally induced tensile stresses, a numerical model of a transient thermal analysis is presented for the evaluation of thermomechanical response of concrete tank to the cryogenic temperature, taking into account the temperature dependence of the thermophysical properties of the concrete tank thermal conductivity and specific heat.     

Analysis of temperature and pressure changes in liquefied natural gas (LNG) cryogenic tanks

Liquefied natural gas (LNG) is being developed as a transportation fuel for heavy vehicles such as trucks and transit buses, to lessen the dependency on oil and to reduce greenhouse gas emissions. The LNG stations are properly designed to prevent the venting of natural gas (NG) from LNG tanks, which can cause evaporative greenhouse gas emissions and result in fluctuations of fuel flow and changes of fuel composition. Boil-off is caused by the heat added into the LNG fuel during the storage and fueling. Heat can leak into the LNG fuel through the shell of tank during the storage and through hoses and dispensers during the fueling. Gas from tanks onboard vehicles, when returned to LNG tanks, can add additional heat into the LNG fuel. A thermodynamic and heat transfer model has been developed to analyze different mechanisms of heat leak into the LNG fuel. The evolving of properties and compositions of LNG fuel inside LNG tanks is simulated. The effect of a number of buses fueled each day on the possible total fuel loss rate has been analyzed. It is found that by increasing the number of buses, fueled each day, the total fuel loss rate can be reduced significantly. It is proposed that an electric generator be used to consume the boil-off gas or a liquefier be used to re-liquefy the boil-off gas to reduce the tank pressure and eliminate fuel losses. These approaches can prevent boil-off of natural gas emissions, and reduce the costs of LNG as transportation fuel.     

Simulation Research of Vaporization and Pressure Variation in a Cryogenic Propellant Tank at the Launch Site

In order to improve depiction of pressure variation and investigate the interrelation among the physical processes in propellant tanks, a 2D axial symmetry Volume-of-Fluid (VOF) CFD model is established to simulate a large-sized liquid propellant tank when the rocket is preparing for launch with propellant loaded at the launch site. The numerical model is considered with propellant free convection, heat transfer between the tank and the external environment, thermal exchange between propellant and inner tank wall surfaces, gas compressibility, and phase change modeled under the assumption of thermodynamic equilibrium. Vaporization rate of the vented LH2 tank and prediction of pressure change in the tank pressurized with GHe are obtained through simulation. We analysis the distributions of phase, temperature, and velocity vectors to reveal interactions among the propellant’s own convection motion, heat transfer and phase change. The results show that the vaporization rate is mainly affected by heat leaks though the tank wall when the tank is vented, but it does not completely accord with the trend of the leakage because of convection motion and temperature nonuniformity of the liquid propellant in the tank. We also find that the main factors on pressure variation in the pressurized tank are the heat transfer on the tank wall surface bonding the ullage and propellant vaporization which has comparatively less influence.     

相变蓄热水箱分层特性的实验研究

本文基于三水合醋酸钠,搭建了一套相变蓄热水箱实验系统,在初始水温为80℃、进水温度为5℃的工况下,测试得到了水箱的热力学特性,并采用填充效率分析法以及火用效率分析法,在进水体积流量分别为1、3、5、7、9 L/min时,分析了相变蓄热水箱的热分层特性。结果表明,当水箱温度为80℃时,普通水箱、相变蓄热球PCM48水箱、相变蓄热球PCM58水箱的热能分别为18. 81、19. 34、19. 07 MJ。进口体积流量相同时,相变蓄热球越靠近水箱进口,水箱的热分层效果越好。随着进水体积流量的增大,分层效果下降。不同水箱的理查森数Ri在t^*=0. 5达到最大值,Ri随相变蓄热球位置的降低而减小,PCM48和PCM58在第4层时的Ri分别为7. 569和7. 781,而在第1层时的Ri分别减小为7. 03和7. 145,表明水箱热分层的程度随着相变蓄热球位置的升高而降低。     

大型低温液体贮存站贮罐设计选型论证(续)

运用热力学第一定律对低温液体在贮存、运输转注过程中的热力学特性进行了分析,定量分析、计算了低温液体节流过程的节流汽化率值,提出了减少节流过程所形成的汽化率的有效途径;论证了在大型低温液体贮存站贮罐设计选型时,应根据不同的低温液体液源、液体品质和操作工况等条件进行设计选型;论证了除合理地选择正确的低温液体贮罐结构形式外,还应高度重视低温液体贮罐的安全泄放设计,以确保低温液体贮存站的安全性能、使用性能和技术经济性能均处于最佳状态。     

Reproducibility of solidification and melting processes in a latent heat thermal storage tank

This study analyzes the reproducibility of solidification and melting tests in a tank containing 181 kg of paraffin for cold storage at around 8 °C. Firstly, an experimental campaign of 10 identical tests was carried out. The performance is practically the same in terms of PCM temperatures and thermal power, with a maximum deviation of 2% in the capacity of all tests. In a second campaign, the impact of the initial conditions was studied. The results indicate that fixing a same mean PCM temperature at the beginning of the tests is insufficient to ensure an accurate reproducibility. Depending on the heat transfer rate during the preparation tests, the capacity differed in up to 33%. In tanks with such quantities of PCM, fixing a uniform initial PCM temperature is hardly possible, thus it is important to prepare the tank with same operation conditions.     

基于EMD的神经网络空耦超声储油罐液位检测

由于仅从信号时域幅值的大小信息虽然能够判断储油罐中不同介质的液位,但是获得的特征信息非常有限,为获得更多储油罐中不同介质信号的特征信息来提高液面识别率,针对储油罐罐壁厚度为5 mm的钢制储油罐为对象,采用空气耦合超声兰姆波同侧相向检测法,并使用A0模态对储油罐进行检测.利用经验模态分解(EMD)对采集储油罐中的不同介质...     

Study on Heat Transfer Characteristics of Phase-Change Energy Storage Unit for Thermal Management

The objective of the study was to investigate the heat transfer characteristics of a phase-change energy storage unit for thermal management. Considering the conduction in the solid and natural convection in the liquid, a physical and mathematical model for heat transfer was formulated. The governing conservation equations were solved using the finite-volume method on fixed grids. An enthalpy-porosity method was used for modeling the melting phenomenon of a phase-change energy storage unit. The time and space movement of the phase front, the temperature distribution, and the heat dissipation rate have been analyzed based on the model. The influence of the unit geometry, heat source location, and types of phase-change materials on the thermal performance of the energy storage unit were investigated. The model and numerical method were evaluated by comparing the numerical predictions with the experimental results. There was found to be excellent agreement between the calculation and experiment, indicating that the numerical method for heat transfer simulation of a phase-change energy storage unit is accurate. The results from the analysis elucidate the thermal performance of the phase-change energy storage unit and will provide the basis for the design and optimization of thermal management systems.