横管初冷器阻力增大原因分析与改进

介绍了横管初冷器在运行中存在的问题并进行改进,解决了初冷器阻力大、冷却效果差、蒸汽吹扫频繁的问题,实现了横管初冷器的连续、稳定运行。     

哈密瓜片充氮低氧热泵干燥工艺研究

本文以哈密瓜为试验材料,以氮气为干燥介质置换空气降低设备中氧体积分数,研究了温度、切片厚度、氧体积分数和风速对哈密瓜热泵干燥速率、L值、Vc和总酚含量等指标的影响,正交试验结果表明最佳干燥工艺参数为：干燥温度50℃,切片厚度5mm,氧体积分数5％,干燥后哈密瓜片水分含量为7．42％,L值为71．28,Vc含量为21．06mg／100g,总酚含量为8．46mg／100g。     

乙烯装置裂解炉热效率影响因素分析及对策实施

乙烯装置裂解炉热效率是裂解炉的重要参数,同时与装置能耗有着十分密切的关系,提高裂解炉热效率是降低能耗的关键。本文以抚顺乙烯裂解炉装置为例,结合近几年实际运行数据对影响裂解炉热效率的主要因素进行了分析,并提出优化各项参数,在实际操作中切实可行的,提高热效率的办法。     

导热油蒸氨工艺的改进措施

采用导热油技术替代水蒸汽蒸氨,是节能、减排、降耗的办法。在实际应用中,存在再沸器列管被焦油堵塞、塔盘漏液、效率降低等问题,造成蒸氨废水中氨氮指标波动。为了保持导热油系统稳定,采取了多项措施,取得了良好效果。     

内加热式热泵干燥装置的设计

内加热式热泵干燥装置通过导热加热方式提供物料中水分气化所需热能,可获得较高的能源效率和除湿能耗比。在介绍内加热式热泵干燥装置基本结构和工作过程的基础上,给出了其物料衡算、能量衡算和主要部件选型参数的计算公式,为内加热式热泵干燥装置的设计提供了较好的参考。     

固定管板式换热器有限元分析及应力评定

利用有限元分析软件ANSYS,对某固定管板式换热器在机械载荷和温度载荷共同作用下的应力强度进行分析,并对其危险截面作应力评定和强度校核。指出换热器应力分析应包括不同危险工况,并对不同危险部位进行分析与评定,这样才能保证其安全可靠地运行。     

改进的管道天然气液化装置及优化研究

陕京二、三线、西一线、中亚管道、西二线相继投产以及西三线全面开工,国内输气管道操作压力等级越来越高。沿线高压管道与城市配气管网之间存在很大压差,在调峰型 LNG 站中利用压差膨胀制冷液化天然气是一种经济利用压力能方案。对国内现存的一种管道天然气液化装置分析,发现存在不合理性并对其改进,改进后流程能够适应各种压差（>3.0~3.5 MPa）特别是克服了当压力大于临界压力时不能正常有效工作的缺陷。同时对改进的管道天然气液化装置进行研究分析,得出该装置的关键参数（如：分流器分流比、膨胀机膨胀压力、低温天然气温度等）对整个液化率的影响。最后对改进的管道天然气液化装置优化分析得出各物流参数并且液化率达到19.86%。由此可见改进的管道液化天然气装置具有充分利用压能、液化率高和适应范围广等优点。     

聚碳酸亚丙酯/壳聚糖熔融共混改性研究

采用熔融共混法将聚碳酸亚丙酯(PPC)与壳聚糖(CS)共混改性,研究了CS含量对PPC/CS共混物相容性、玻璃化转变温度(Tg)、热失重温度和拉伸性能的影响,并探讨了CS改性PPC的作用机理。结果表明:PPC与CS的共混属于简单物理共混,CS对PPC的Tg影响不大,但可显著提高PPC基体的耐热性能,扩大复合材料的加工温度范围。同纯PPC相比,PPC/CS共混物的TGA曲线向高温区偏移,共混物的5%分解温度(T-5%)较PPC提高了51⁵9℃,其50%分解温度(T-50%)提高了1259℃,其50%分解温度(T-50%)提高了12²1℃;另外,共混物的TGA曲线只存在一个高温区的失重台阶,这是由于CS的引入抑制了PPC在低温区的解拉链式降解,因而只有高温区的无规降解发生。此外,随着CS含量的增加,PPC/CS共混物的拉伸强度不断增大,当CS含量增至20%时,材料的拉伸强度由纯PPC的4.7 MPa上升至12.5 MPa。     

Reduction of Empiricism through Flow Visualization and Computational Fluid Dynamics

In chemical process industry, a variety of equipment is used for carrying out different unit operations and unit processes. The design procedures for this equipment have been largely empirical due to the complexity of fluid mechanics. In view of this, a stepwise procedure has been suggested based on experimental fluid dynamics (EFD) and computational fluid dynamics (CFD). One application of EFD and CFD is presented for the prediction of the heat transfer coefficient in the single‐phase turbulent pipe flow. The present capabilities of CFD for the design of different process equipment have been outlined.     

Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model

Heat production from geothermal reservoirs is a typical heat transfer process involving a cold working fluid contacting a hot rock formation. Compared to the thermal-physical characteristics of water, supercritical CO₂ (scCO₂) has a higher heat storage capacity over a wide temperature-pressure range and may be favored as a heat transfer fluid. Singularly characteristic of scCO₂-based heat extraction is that the hydraulic-thermal properties of the scCO₂ vary dramatically and dynamically with the spatial pressure gradient during unsteady-state flow along fracture. This highly nonlinear behavior presents a challenge in the accurate estimation of heat extraction efficiency in scCO₂-based EGS. In this paper, a thermal–hydraulic-mechanical (THM) coupled model is developed by considering deformation of the fractured reservoir, non-Darcy flow and the varying thermal-physical properties of scCO₂. The proposed model is validated by matching the modeling temperature distribution with published data. The results show that during continuous injection of scCO₂, the fracture first widens and then narrows, ultimately reopening over the long term. The sequential fracture deformation behaviors are in response to the combined impacts of mechanical compression and thermally-induced deformation. By controlling the injection parameters of the scCO₂, it is found that the heat extraction rate is positively correlated to its pore pressure or mass flow rate. The heat extraction rate can be significantly enhanced, when the inlet temperature of scCO₂ is below its critical temperature. As a result, the heat increment recovered per unit mass of scCO₂ decreases as the hot rock is gradually cooled. Meanwhile, the heat increment recovered per unit mass of scCO₂ decreases by increasing the inlet temperature of scCO₂ or its mass flow rate, but increases as the outlet pressure rises. Furthermore, multi-linear regression indicates that controlling the inlet temperature of the scCO₂ can significantly improve the thermodynamic efficiency of heat extraction.