无人值守热力站自动化控制的实现与改进措施

在当代科技飞速发展的背景下,无人值守热力站的自动化控制成为提高供热系统效能和减少人力成本的重要方向。本文主要分析了实现和改进无人值守热力站自动化控制的关键措施。通过引入先进的技术和创新的管理手段,致力于构建一个智能、高效、可持续的供热系统以适应未来城市发展的需求。从智能传感器的应用到控制算法的优化,将探索如何使热力站在无人值守的情况下更加灵活、可靠,从而为城市能源管理迈向新的高度。通过对传感器技术、数据分析算法等领域的综合运用,旨在优化热力站的运行模式,提高能源利用效率。同时将关注环境友好型解决方案,致力于减少对自然资源的依赖,推动热力站向可持续发展的方向迈进。

无人值守热力站流量自控全网平衡调节方法

为解决供热系统的流量平衡调节困难问题,现提出无人值守热力站流量自控全网平衡调节方法。控制好无人值守热力站的流量数据采集,实现对热力站的全方位监控和管理,进行热力站流量的全网平衡调节设计,使各处热力站的供暖效果一致。结果表明,对于实验设定的循环流量最优值,经过全网平衡调节后,其循环流量数值要明显优于调节前的循环流量数值,证明该方法能够有效地实现热力站的流量自控和全网平衡调节。

电动势法测定热力学函数变化值

设计了电池:Ag,AgCl|KCl(0.1mol/L)||AgNO3(0.01mol/L)|Ag,测定了其在不同温度下的电动势并计算热力学函数变化值△G298、△H298、△S298,最大相对误差分别为-1.70%、-3.68%和-4.22%.

电化学法测定化学反应热力学函数变化值

根据可逆热力学体系的要求,把化学反应设计成可逆原电池,利用电化学法测定可逆电池在不同温度下的电动势值,进而求算化学反应的热力学函数变化值。

蒸气压缩式制冷循环制冷剂的热力优值评价

虽然热电制冷和蒸气压缩式制冷产生制冷效应的方式不同,但是热电材料在热电制冷中的作用相当于蒸气压缩式制冷循环中的制冷剂。在热电制冷中,将在研究其制冷系数的过程中导出的"热电优值"作为评价热电材料性能的指标。类似地,本文通过建立蒸气压缩式制冷循环的制冷系数的解析式,导出制冷剂的"热力优值",将其作为制冷剂热力性能的评价指标,并计算常用制冷剂的"热力优值"。

浅析无人值守热力站的设计与实现

介绍了无人值守热力站运行模式的设计思路,探讨了远程监控系统的构成及通信方式,论述了自动化控制技术在无人值守站运行中的实施与应用,阐述了该技术在解决热网平衡、管网调控及站点管理等方面取得的成绩。

无人值守热力站与平衡自控系统的研究

应用热力站自控系统和平衡自控系统可将供热企业的精细化管理水平全面提高,再借助自控系统进行热力站的节能管控,也能为供热企业节省很多人力和资源,而他们自身的经济效益、社会效益也能够得到最大限度的提高。

分布变频技术在无人值守热力站中的应用

城市集中供暖已成为我国热网节能改造的主要发展趋势,将分布变频技术应用在无人值守热力站中,具有节约电能、运行成本低、运行安全系数高的特点。

无人值守热力站配电监测系统的设计方案

主要介绍集中供热系统中无人值守热力站低压配电室自动监测系统的设计。随着集中供热系统的发展,集中供热热力站自动化程度越来越高,但是无人值守热力站的高低压配电室的安全却容易被忽略。低压配电室的监测系统关系到无人值守热力站各个生产现场配电设备和自动化设备能否正常运转。就集中供热系统中无人值守热力站低压配电室动力柜、变频器、自控柜的自动监测设计进行介绍。

基于百度热力图的重庆中心城区活力时空特征分析

随着大数据发展,百度热力图因其能通过可视化的形式来反映当前地区人群集聚情况,被广泛应用于城市活力、城市规划的研究中。为研究城市活力,本文以重庆中心城区为研究对象,通过python爬虫获取工作日和节假日共36张百度热力图,在ArcGIS软件中对热力值进行分级提取,从时间和空间两个维度对重庆中心城区活力进行分析,揭示重庆市中心城区工作日和节假日居民出行活动特征。结果表明:1) 居民的出行规律受工作时间影响。工作日越接近上班时间,高热区面积就越大,而下班时间之后,高热区面积逐渐减小;节假日的出行规律与工作日相比存在滞后性,热区面积快速增加和减少时间都比工作日晚;2) 重庆中心城区工作日的活力区域比较集中,节假日比较分散,这跟工作日和节假日居民的出行地点不同有关。这些研究结论在一定程度上为重庆中心城区的城市规划和居民出行提供参考。

南宁市老城区街道的空间活力及时空特征分析——基于百度热力图数据

以南宁市老城区为例,通过提取连续一周百度热力图中的人口热力数据,分析老城区街道空间活力的时空特征与特点。结果表明,南宁市老城区街道空间活力一天内的变化情况呈现“分散—弱集聚—强集聚—分散”的变化过程。工作日主要体现出以节律性为主的集聚过程,街道空间活力在白天持续时间长,街道空间活力程度高。休息日表现出延后性的特点,夜间依然存在较高的街道空间活力。从空间分布来看,中华路—朝阳路—江北大道—北大南路围合而成的街区成为老城区街道空间活力集聚程度最高的区域。

A thermo-mechanical damage constitutive model for deep rock considering brittleness-ductility transition characteristics

This paper developed a statistical damage constitutive model for deep rock by considering the effects of external load and thermal treatment temperature based on the distortion energy.The model parameters were determined through the extremum features of stress−strain curve.Subsequently,the model predictions were compared with experimental results of marble samples.It is found that when the treatment temperature rises,the coupling damage evolution curve shows an S-shape and the slope of ascending branch gradually decreases during the coupling damage evolution process.At a constant temperature,confining pressure can suppress the expansion of micro-fractures.As the confining pressure increases the rock exhibits ductility characteristics,and the shape of coupling damage curve changes from an S-shape into a quasi-parabolic shape.This model can well characterize the influence of high temperature on the mechanical properties of deep rock and its brittleness-ductility transition characteristics under confining pressure.Also,it is suitable for sandstone and granite,especially in predicting the pre-peak stage and peak stress of stress−strain curve under the coupling action of confining pressure and high temperature.The relevant results can provide a reference for further research on the constitutive relationship of rock-like materials and their engineering applications.

Furnace structure analysis for copper flash continuous smelting based on numerical simulation

According to the innate characteristic of four types of furnace, the copper flash continuous smelting （CFCS） furnace can be considered a synthetic reactor of two relatively independent processes： flash matte smelting process （FMSP） and copper continuous converting process （CCCP）. Then, the CFCS thermodynamic model was proposed by establishing the multi-phase equilibrium model of FMSP and the local-equilibrium model of CCCP, respectively, and by combining them through the smelting intermediates. Subsequently, the influences of the furnace structures were investigated using the model on the formation of blister copper, the Fe3O4 behavior, the copper loss in slag and the copper recovery rate. The results show that the type D furnace, with double flues and a slag partition wall, is an ideal CFCS reactor compared with the other three types furnaces. For CFCS, it is effective to design a partition wall in the furnace to make FMSP and CCCP perform in two relatively independent zones, respectively, and to make smelting gas and converting gas discharge from respective flues.

Effects of static magnetic fields on melt flow in detached solidification

A series of three-dimensional numerical computations were conducted to understand the effects of different static magnetic fields on thermal fluctuation and melt flow during the detached solidification of CdZnTe. Numerical calculations were carried out by three different configurations of magnetic field: without magnetic field, with an axial magnetic field (AMF) and with a cusp-shaped magnetic field (CMF). The results reveal that the magnetic fields can effectively suppress the melt flow and thermal fluctuation and the suppression effect of the AMF is stronger than that of the CMF. Besides, the physical mechanism of thermocapillary?buoyancy convection instability was discussed and the effects of magnetic field on the critical Marangoni number were also obtained.

Study on Starch Properties of Rice Enriched with Resistant Starch

This study aimed to compare starch properties among rice germplasms with different contents of resistant starch. Rice germplasms with significant differ- ences in resistant starch content were screened by the rice germplasm resource project team in Jiangsu Academy of Agricultural Sciences, to analyze the differences in RVA eigenvalues and starch crystal thermodynamic properties using differential scanning calorimeter （DSC）. The result showed that three rice materials with high contents of resistant starch exhibited low breakdown viscosity and high setback vis- cosity; three rice materials with low contents of resistant starch exhibited high breakdown viscosity and low setback viscosity. Significant differences were observed in RVA eigenvalues and starch crystal thermodynamic properties among rice germplasms with different contents of resistant starch, which provided new indices for breeding functional rice cultivars with high resistant starch content.

基于大数据对轨道交通站内公共设施优化研究——以武汉轨道交通2号线为例

伴随大数据的发展及应用,用户的数字足迹为有效展现城市人口流动的轨迹和时空聚集状态提供了便利,弥补了传统城市调研和空间规划的缺陷。本文借助百度地图热力图人群分布数据,通过大数据方法并结合传统收集数据方法、实地调研、问卷调查,从安全性、高效性、舒适性和便捷性四个方面探讨轨道交通站内公共设施与人群分布的关系。研究结果表明:武汉轨道交通2号线站内公共设施高效性较好,但人性化不足;安全性与舒适性符合人群分布特征,但整体水平较低;便捷性有待提高,未来在提升站内设施便捷性时,应与站点周边环境相结合。

NUMERICAL PREDICTION OF AIRCRAFT HYDRAULIC SYSTEM BASED ON THERMAL DYNAMIC ANALYSIS

A mathematical model of principal elements of the aircraft hydraulic system is presented based on the heat transfer theory. The dynamic heat transfer process of the hydraulic oil and the pump shells within an aircraft hydraulic system are analyzed by the difference method. A kind of means for the prediction to variational trends of the aircraft hydraulic system temperature is provided during operation. The numerical prediction and simulation under the operational conditions are presented for ground trial running and the decelerated operation in flight. Computational results show that there is a good coincidence between the experimental data and the numerical predictions.

Simulation on flow, heat transfer and stress characteristics of large-diameter thick-walled gas cylinders in quenching process under different water spray volumes

Cooling strength is one of the important factors affecting microstructure and properties of gas cylinders during quenching process,and reasonable water spray volume can effectively improve the quality of gas cylinders and reduce production costs.To find the optimal water spray parameters,a fluid-solid coupling model with three-phase flow was established in consideration of water-vapor conversion.The inner and outer walls of gas cylinder with the dimensions of d914 mm×38 mm×12000 mm were quenched using multi-nozzle water spray system.The internal pressure,average heat transfer coefficient(have)and stress of the gas cylinder under different water spray volumes during quenching process were studied.Finally,the mathematical model was experimentally verified.The results show that both the internal pressure and have increase along with the increase of spray volume.The internal pressure increases slowly first and then rapidly,but have increases rapidly first and then slowly.To satisfy hardenability of gas cylinders,the minimum spray volume should not be less than 40 m^3/(h·m).The results of stress indicate that water spray quenching will not cause deformation of bottle body in the range of water volume from 40 to 290 m^3/(h·m).

Thermodynamic study on reaction path of Hg(Ⅱ) with S(Ⅱ) in solution

The mercury sulfidation experiments were conducted in the pH range from 1 to 13. The results show that Hg（II） reacted with equimolar S（ II ） has the lowest remained Hg（II ） concentration （9.7 μg/L） at pH 1.0 and the highest remained concentration （940.8μg/L） at pH 13.0. Meanwhile, the changes of pH values were monitored exactly, which reveal that solution pH values change when mixing the same pH value solutions of HgCI2 and Na2S. In order to explain the phenomena and determine the reaction paths of Hg（II） reacting with S（ II ） in the solution, the concerned thermodynamics was studied. Species of S（ II ）-H2O system and Hg（II）-H2O system at different pH values were calculated, and then the species distribution diagrams of S（II）-H2O system, Hg（ II ）-H2O system and Hg（ II ）-Cl-OH--H20 system were drawn. Combining the experimental data and thermodynamic calculation, the mechanism of Hg（II） reacting with S（II） was deduced. The results indicate that different species of S（ II ） and Hg（II） have the diverse reaction paths to form HgS precipitate at different pH values and the standard Gibbs free energies change （△tGm^⊙） of those equations are also calculated, which can provide a guidance for mercury-containing wastewater treatment with Na2S.