最新真空熔炼炉

真空加热可获得无氧化加热、脱气、高纯度化等多种效果，广泛应用于金属热处理、金属熔炼等领域。概述了真空感应熔炼炉、电子束熔炼炉、真空等离子熔炼炉、真空电弧炉等真空熔炼炉的用途与特点。重点介绍了混合动力汽车电动机与蓄电池用钕烧结磁铁与氢吸留合金制造用水冷辊式真空熔炼炉与新型急冷铸造式真空熔炼炉的设备结构、特点及其生产工艺流程。照3图7参1     

真空热处理——《工业加热》,

本文着重介绍了真空气氛,真空气氛的特点,载气法和真空热处理炉与真空烧结炉的种类、构造、特点等等。表7个,图7幅,照片2张,参考文献4种。真空热处理——《工业加热》,@陈留根~~     

汽轮机真空系统严密性评价方法的发展状况

汽轮机真空系统严密性是关系到汽轮机安全、经济运行的重要指标。目前，评价汽轮机真空系统严密性的指标是真空系统严密性试验得到的真空下降速度。对现有的各种评价汽轮机真空系统严密性的方法包括真空系统严密性试验存在的问题进行了分析，指出在线测定漏入真空系统的空气量并据此实现在线定量评价真空系统严密性是未来的发展趋势，并对实现在线定量评价真空系统严密性所需要解决的一些技术问题进行了讨论。     

余热发电汽轮机真空低的分析与处理

厂水泥熟料纯低温余热发电所用的是1×12 MW的机组,自投运以来凝汽器真空较长时间低于设计值运行,同时机组在运行中出现过凝汽器真空恶化的现象。经全面分析真空系统工作原理及设备运行工况,得出汽轮机真空系统不严密、射水抽气器工作不正常、循环水流量不足、循环水温升高、凝汽器传热端差大等是造成凝汽器真空低的主要原因。结合各种故障给出提高凝汽器真空的方法与措施,提高了真空值。     

真空压力加载方式对泥浆固结效果的影响

为了研究真空压力加载方式对泥浆固结效果的影响,通过室内模型试验,分别从土样排水量、平均沉降量、差异沉降量、物理力学性质等方面分析了不同加载方式下4组相同土样的固结效果。结果表明,与常规真空预压加载方式(初始真空压力为-80 kPa)相比,降低初始真空压力(初始真空压力分别取-20、-50 kPa)和分级加载真空预压下的试验箱排水量分别提高了10.6%、6.1%、14.0%,表层土体平均沉降量分别提高了8.02%、5.64%、12.85%,可见采用降低初始压力真空预压和分级加载真空预压处理泥浆时固结效果更好。     

凝汽器最佳真空确定方法的改进

现有的凝汽器最佳真空的确定方法只适用于凝汽器水侧管壁清洁、汽轮机真空系统严密性正常或抽气设备运行性能正常的工况。文中首先对凝汽器清洁率对最佳真空的影响进行了分析,然后提出一种新的凝汽器最佳真空的确定方法,该方法利用凝汽器综合清洁系数来体现凝汽器水侧管壁脏污程度、汽轮机真空系统严密性及抽气设备运行性能对最佳真空的影响,从而提高了最佳真空的确定精度。     

凝汽器脏污及漏气对循环水系统优化目标值的影响

首先阐述循环水系统优化运行的目标值--最佳真空确定的原理;然后计算分析了凝汽器清洁情况对最佳真空的影响;最后利用凝汽器综合清洁系数来体现凝汽器水侧管壁脏污程度、汽轮机真空系统严密性对最佳真空的影响,提高了最佳真空的确定精度、得到的循环水系统优化方式更合理.     

太阳能真空集热管的结构种类与特点

太阳能真空集热管按真空封装结构可分为两大类：全玻璃真空集热管和玻璃－金属真空集热管,从取热方式、使用温度和性能要求的不同又有各种不同的内部结构。本文对国内外一些有代表性的太阳能真空集热管的结构种类和特点做了综述。     

利用汽轮机真空系统严密性试验获取更多信息的研究

通过对汽轮机真空系统严密性试验过程中真空下降速度的分析 ,指出真空下降速度并不是漏入真空系统空气量的单值函数 ,其还受到凝汽器运行参数及汽轮机排汽量的影响 ,为了使真空系统严密性试验结果具有可比性 ,应该将试验结果进行修正。同时 ,为了利用真空系统严密性试验得到更多的信息 ,指出了真空系统严密性试验在凝汽器水侧脏污与汽侧空气量故障的分离、漏入真空系统空气量的软测量以及汽轮机整机密封性检测方面的作用     

真空高压气淬炉

一、前言 真空油淬火炉取代盐浴炉,是热处理行业的一大进步,而近年发展的真空高压气淬炉和真空油淬火炉比较,具有如下一些优点: 1.结构简单。真空油淬火炉一般有加热和冷却两个室,二室之间有闸门。真空高压气淬炉只有一个工作室。     

关于电站抽真空设备的选择

汽轮发电机组在启动和正常运行过程中,抽真空设备都要投入运行,其工作的正常与否直接影响凝汽器的真空以及机组能否安全、经济运行。结合结构、性能等方面详细分析了目前广泛使用的3种抽真空设备——射汽抽气器、射水抽气器和水环真空泵的优缺点,综合考虑地区、成本、机组规模等因素完成抽真空设备的合理选择。     

Theoretical simulation of vacuum cooling of spherical foods

A model has been developed for predicting the temporal temperature and mass of spherical solid foods during vacuum cooling. This paper discusses the effects of product thermophysical properties, convection heat transfer coefficient, latent heat of evaporation as well as vacuum environmental parameters that govern the heat and mass transfer of product. The temporal trends of total system pressure, product temperature such as surface temperature, centre temperature, mass-average temperature, the mass of product were predicted. The model accounts for the change of temperature of solid product systematically during vacuum cooling by means of simulation. This paper also compares the results of the computer algorithm with experimental results taken from published literature.     

Long-term field tests of vacuum glazing

This paper describes the first long-term field tests done on vacuum glazing. In this preliminary study, glazing samples were mounted in an outdoor environment and observed for more than one year. The effects of large temperature differences and thermal cycling on the thermal performance and the mechanical stability of the glazings have been investigated. The results provide support for the viability of vacuum glazings in their intended application as thermally insulating windows.     

有无砂垫层真空预压法的吹填土现场试验及数值模拟

以温州丁山垦区的吹填淤泥真空预压加固处理工程为例,基于现场试验和数值模拟,对无砂垫层真空预压法和传统的有砂垫层真空预压法从表面沉降、分层沉降、孔隙水压力、固结度、静力触探、十字板强度及部分土体物理力学参数等方面对加固效果进行了对比分析。结果表明,两者加固效果接近,无砂垫层真空预压法可用于代替传统的有砂垫层真空预压法。     

采用刷子汽封提高汽轮机内效率

为了提高汽轮机的内效率;汕头万丰热电有限公司在50 MW汽轮机上全面使用刷子汽封,并获得了优异效果:除汽轮机效率提高1.57%外,还有效地提高了汽轮机的真空度,并大大减少了汽轮机机油进水.介绍了轴、隔板和叶顶刷子汽封结构参数的确定方法,计算了刷子汽封的效益,并评估了刷子汽封对凝汽器真空度的影响.     

Hydrogen permeation enhancement in a Pd membrane tube system under various vacuum degrees

Hydrogen purification using palladium (Pd) membrane technology has been seen as a potential solution for producing pure hydrogen form hydrogen-rich gas. Compared to traditional practices of operating the permeate side of the membrane at atmospheric pressure, in this study, a vacuum is applied. The effects of various vacuum degrees applied to the permeate side of the Pd membrane are investigated and compared to the results under normal operation without a vacuum. The feed gas used for experiments consists of a mixture of hydrogen (70 vol%) and nitrogen (30 vol%). Three membrane operating temperatures (320, 350, and 380 °C), four pressure differences (2, 3, 4, and 5 atm) across the membrane, and four vacuum degrees (−15, −30, −45, and −53 kPa) applied to the permeate side are considered. For the three operating temperatures, the best improvements in the performance of hydrogen permeation are at 320 and 350 °C when a −53 kPa vacuum is applied, resulting in 79.4% and 79.1% improvements, respectively, compared to normal operations. Increasing temperatures leads to an increase in H₂ permeation both with and without a vacuum; however, best performances of H₂ permeation are observed in cases without a vacuum.     

Vacuum lifetime and residual gas analysis of parabolic trough receiver

The vacuum characteristics and lifetime are the key problems of parabolic trough receiver. Heat loss of the receiver will greatly increase when the vacuum has been lost. Especially, if hydrogen is inside the annulus space of the receiver, heat loss at a level is approximately a factor of four higher than the loss for a receiver with good vacuum. Suitable vacuum levels and residual gases should be maintained in the receiver to ensure performances during its projected lifetime. In this paper, the variations of composition and partial pressure of residual gases with temperature in the receiver were measured by a high sensitivity quadrupole mass spectrometer gas analyzer. The effects of residual gas and getter on the vacuum lifetime of receiver were analyzed. The results showed that hydrogen was the main residual gas in the annular space of receiver without getter, and the nitrogen was the main gas released in the receiver with getter. It can be confirmed that the residual gas analysis was a very effective way to predict and evaluate the vacuum lifetime of the receiver.     

考虑节水因素的凝汽器最佳真空的确定方法

凝汽器真空不仅影响到汽轮机的运动安全性,经济性及汽轮机的调节性能,而且还曩到冷却的消耗量,随着环境及水资源保护意识的提高,由冷却水造成的热污染及水资源消耗量以及由此产生的经济损失已不容忽视,文中提出一种考虑节水因素的凝汽器最佳真空的胡定方法,为降低发电成本及减少环境污水提供了一项有效的途径。表1参5     

侧底复吹RH真空精炼中均混特性的物理模型研究

基于相似原理,建立了几何相似比为1：5的水模型,对RH精炼过程钢液循环流动行为进行研究。考察了提升气体流量、真空度、不同吹气方式以及不同形状的浸渍管对混匀时间的影响规律。结果表明：均混时间随吹气量增大先减小后增大,随真空度增大而减小。在相同吹气流量下,单独采用侧底复吹方式或单独采用椭圆形浸渍管,均混时间减小。