水力空化改质对重质原油沥青质及性质的影响

利用水力空化过程产生局部的高温、高压、高射流以及强大的剪切力等极端化学物理条件改质处理沙特重质原油，试验结果表明：沙特重质原油经过水力空化改质后粘度由13.61降低至7.22mm2/s，残碳由7.16%降低至6.48%，实沸点蒸馏后减压渣油降低1个百分点。进一步采用APPI FT-IR MS、XRD、FT-IR、SEM和粒度分布等技术研究了水力空化改质对沙重原油分子组成，沥青质团聚体微晶结构、沥青质胶束粒径分布、沥青质官能团、沥青质形貌等方面的影响，从分子角度阐述空化改质重油的机理。研究结果表明：水力空化改质后沙重原油分子量分布、芳烃类化合物缔合作用变小；沥青质对低DBE化合物吸附性能降低；沥青质团聚体微晶结构更加松散；沥青质胶束粒度分布降低；沥青质分子相互团聚作用力减弱。进一步考察了水力空化改质前后减压渣油延迟焦化性能，改质处理后焦炭产率降低1.85个百分点，液体收率和气体产率分别增加1.52和0.33个百分点，水力空化改质对沥青质性质、结构特点的改善能够有效的提高其加工性能。     

阶梯溢流坝面坡度对一体化消能工水力特性的影响

为探求高水头、大单宽流量下坝面坡度对一体化消能工水力特性的影响,以阿海水电站为原型,采用三维k-ε双方程紊流模型,引入水气两相流VOF计算方法,利用几何重建格式来迭代生成自由水面,对1∶0.80、1∶0.75、1∶0.65三种阶梯面坡比进行数值模拟研究。结果表明:①最大负压值均位于首级阶梯立面凸角下1/4附近,并随坡度增加而增大。坡度为56.98°时,最大负压值为61.02 kPa,超过了6×9.81 kPa。②水流空化数在宽尾墩水舌出口位置出现最小值,空化数随坡度变陡而减小。坡度为56.98°时,空化数最小为0.358。坡度为51.34°时,空化数最大,为0.381。③随着阶梯溢流坝坝面坡度变缓,消力池最大临底流速增大。当坡度为51.34°时,消力池最大临底流速最大,达到26.84 m/s,超过了25 m/s,易发生冲磨破坏。当坡度为56.98°时,消力池最大临底流速最小,为24.00 m/s。消力池尾坎前最大临底流速随坡度增加而减小,坡度为56.98°时最小,为9.63 m/s;坡度为51.34°时,消力池尾坎前最大临底流速最大,为9.96 m/s。④坡度的变化对一体化消能工消能率的影响不大,坡度从51.34°增加到56.98°,消能率只提升0.15%。     

Microstructure and corrosion behaviors of FeCrNiBSiMox stainless steel fabricated by laser melting deposition

In this paper, FeCrNiBSiMo_x (x = 1.0, 1.5, 2.0, 2.5) stainless steels were successfully prepared using a laser melting deposition technology, with the aim to investigate the effect of Mo content on microstructure and corrosion behaviors. The results showed that the as-deposited specimens were composed mostly of α-Fe and a small amount of (Cr, Mo)₇C₃, and (Cr, Mo)₇C₃ existed in the inter-dendritic (ID) region. As the Mo content increased, grain refinement could be clearly observed, and the area of the ID region increased from 27% to 54%. The low-angle boundaries accounted for 60–70% of the grain boundaries of the as-deposited specimens. Increasing the content of Mo improved the microhardness of the as-deposited specimens from 652 HV to 813 HV. The corrosion current density of the as-deposited specimens with the Mo mass fractions of 1.0%, 1.5%, 2.0%, and 2.5% were 1.37 × 10⁻⁶, 1.02 × 10⁻⁷, 6.19 × 10⁻⁷, and 3.06 × 10⁻⁷ A/cm², respectively. The as-deposited specimen with Mo content of 1.5% had lower cumulative erosion loss and erosion loss rate than other as-deposited specimens. The FeCrNiBSiMo_x (x = 1.5) specimen exhibited excellent resistance to electrochemical corrosion and cavitation erosion.     

空化对液膜密封流场特性及密封性能的影响

为进一步探索液膜空化对密封性能的影响，以螺旋槽液膜密封为研究对象，基于JFO空化模型及坐标变换建立其数学模型并采用有限体积法离散求解。探讨Reynolds和JFO两空化边界下的密封速度场和流量场分布规律以及空穴压力对密封性能如承载能力和摩擦扭矩等影响。结果表明：空穴区的形成具有动态性，速度矢量在空穴区内部为0，在液膜始破边界和靠近内径处的液膜重生边界上速度矢量朝向空穴区，而在靠近外径处的液膜重生边界上速度矢量远离空穴区；液膜流量场主要集中于槽区内且JFO空化边界下的流量场分布比Reynolds空化边界下值更为密集；空穴压力的增加可提升液膜承载能力但增幅较小，而对摩擦扭矩的影响可忽略不计。     

超声强化过氧化氢-维生素C体系糖汁脱色的研究

研究超声强化过氧化氢-维生素C复合脱色剂体系对糖汁脱色的规律,考察了超声功率、复合脱色剂用量、超声温度和时间对糖汁脱色率的影响。试验结果表明:超声空化强化过氧化氢-维生素C对糖汁具有良好的脱色效果,当处理糖汁量为100 mL,超声功率为260 W,过氧化氢与维生素C的用量均为1.6 mL,空化温度为70℃,超声时间为6 min时,脱色率达到53.4%。通过正交试验分析,得到各个因素对糖汁脱色率影响的主次关系为:超声功率>复合脱色剂用量>超声时间>空化温度。     

转速对齿轮泵内流场空化强度的影响

针对齿轮泵中齿轮转速在500~3652 r/min的变转速条件下工作的实际工况,该文通过实验的方法研究了转速对某型齿轮泵内流场空化强度的影响。使用现有的齿轮泵测试实验台,对在齿轮泵转速改变的条件下,齿轮泵内流场的空化强度改变进行监测。由于空化无法直接测量,该文根据空化诱导振动理论对齿轮泵的振动进行测量,得到了齿轮泵内流场空化强度随齿轮转速上升而增强的规律。通过Pumplinx软件对内流场进行建模,利用软件特有的空化损伤模块进行了仿真验证,仿真结果表明齿轮泵内流场空化强度随齿轮转速上升而增强,与实验所得规律一致。本文所总结的规律对减弱齿轮泵内流场空化强度,提升使用寿命具有一定的参考作用。     

基于MCGS的洗油空穴反应实验装置计算机控制系统设计

介绍了基于MCGS的洗油空穴反应实验装置远程计算机自动控制系统的硬件、软件设计及其实现过程,为后续进一步的研究工作提供理论和实践基础。     

汽蚀对离心泵性能影响的实验研究

离心泵长时间运转后,会出现危害严重的汽蚀现象,造成泵性能下降,严重时影响泵的效率、寿命,甚至造成离心泵内部部件损坏。文章通过改变进口压力的方法对单泵、双泵并联、双泵串联等工况下汽蚀对离心泵性能影响进行实验研究。结果表明:当进口压力小于输送液体的饱和蒸汽压时,液体开始发生气化并伴随气泡产生,表明泵内发生汽蚀;汽蚀初期离心泵的效率开始下降,但表现不明显;随着汽蚀不断增大至严重汽蚀区时,Q 1~η曲线出现陡坡,效率出现明显下降并伴随嗡响。实验证明采用提高泵的进口压力等措施可适当减小汽蚀对泵性能的不利影响。     

Modeling of an industrial scale hydrodynamic cavitation multiphase reactor for Prileschajew epoxidation

The hydrodynamic cavitation multiphase reactor (HCMR) is emerging as a promising alternative for the intensification of liquid–liquid heterogeneous reactions, but research on HCMR modeling is lacking. In this article, an HCMR model was developed using Prileschajew epoxidation as the model system. First, based on experimental measurements of oil/water two-phase flow downstream of hydrodynamic cavitation devices, semiempirical correlations were proposed to describe the droplet size and droplet size distribution (DSD) as functions of flow conditions and geometry parameters. Then, with boundary conditions calculated by the DSD correlation, a droplet dynamics simulation in a reaction tank was performed by computational fluid dynamics coupled with population balance model to obtain the two-phase interfacial area. Finally, the acquired reactor model was substituted into an overall kinetic model, to simulate the epoxidation reaction in HCMR. Model predictions were verified by experimental results measured on an industrial scale HCMR.