Optimization of High Pressure Feedwater Heater

At the beginning of 1980’s, the power equipment manufacturing industry in China introduced patent technology on designing and manufacturing the turbine, generator, boiler and their auxiliaries from USA owing to the policy of opening and reformation. In the meantime, our works also imported the patent technology on designing

Producing ultra-high-speed nitrogen jets by arc heating in a low-pressure chamber

Pure nitrogen gas was heated with direct current arc, at input powers from several hundred Watt to over 5 kW, and then injected through a nozzle into a chamber at 1 or 10 Pa pressure, with the purpose of accelerating the gas to very high speed around 7 km/s. Various structures of the arc generator and gas expansion nozzle were examined. Results show that bypass exhausting of the boundary layer before it enters the nozzle divergent section can greatly increase flow speed of the jet, thus it might be possible to use nitrogen as a working gas in high speed gas dynamic test facilities.

DRILLING CHARACTERISTICS OF COMBINATIONS OF DIFFERENT HIGH PRESSURE JET NOZZLES

The high speed fluid jet for directly or indirectly breaking rock is one of the most effective ways to improve the deep penetration rate. In order to maximize the efficiency of energy use, the flow characteristics of different combinations of high pressure jet nozzles are analyzed through numerical simulations. According to the velocity vectors at the bottom and the bottom hole pressure diagram, the effects of the high pressure nozzle combinations on the flow structure and the penetration rate are analyzed. It is shown that the combination of three vertical edge nozzles is very efficient, but inefficient in cleaning the bottom hole and eroding the wall. The jet velocity is 400 m/s and the radius is 5 mm, with a center nozzle added, the problem can be solved, but the high-pressure fluid displacement would increase. The center nozzle＇s jet velocity is 200 m/s and the radius is 8 ram, the combination of two vertical edge nozzles and a center tilt nozzle or that of a vertical edge nozzle and a center tilt nozzle would provide a flow structure favorable for drilling. The angle of inclination is 10°. To take advantage of high pressure jet energy to improve the efficiency of drilling, it is important to select a suitable nozzle combination according real conditions.

Aero-thermal redesign of a high pressure turbine nozzle guide vane

The current article presents conceptual,preliminary and detailed aero-thermal redesign of a typical high pressure turbine nozzle guide vane.Design targets are lower coolant consumption,reduced manufacturing costs and improved durability.These goals are sought by 25%reduction in vane count number and lower number of airfoils per segment.Design challenges such as higher airfoil loading,associate aerodynamic losses and higher thermal loads are discussed.In order to maximize coolant flow reduction and avoid higher aerodynamic losses,airfoil Mach distribution is carefully controlled.There has been an effort to limit design changes so that the proven design features of the original vane are used as much as possible.Accordingly,the same cooling concept is used with minor modifications of the internal structures in order to achieve desired coolant flow and internal heat transfer distribution.Platforms of the new design are quite similar to the original one except for cooling holes and application of thermal barrier coating(TBC).Detailed aerodynamics/heat transfer simulations reveals that the reduced trailing edge(T.E.)blockage and skin friction dominated the negative effect of increased secondary losses.As a result the reduced design performs acceptable in terms of total pressure loss and improving stage efficiency for a wide range of varying pressure ratio.Moreover,more than 20%cooling mass flow can be saved;while maximum and average metal temperatures as well as cross sectional temperature gradients have not been changed much.

THE PERFORMANCES OF HIGH PRESSURE JET OF PURE WATER AND POLYMER SOLUTION WITH CONICAL NOZZLE

In this paper, the effects of polymer additives and nozzle shape on the proper- ties of high pressure water jet discharging into the air are investigated by theory and experiments. Criteria of judging the jet quality are put forward. And, a method that can be used in analysing the fluid flow within the nozzle is developed. Then, the calculated results are compared with the experiments that we carried out; it is shown that the degree of agreement between the two is good. At last, the mechanism to improve on the jet quality with polymer additives is discussed.

A double-layer heating method to generate high temperature in a two-stage multi-anvil apparatus

A new heating method is proposed to increase the cell temperature of the 6-8 type multi-anvil apparatus without reducing the volume of the sample chamber. The double-layer heater assembly (DHA) has two layers of heaters connected in parallel. The temperature of the cell was able to reach 2500 ℃ by using 0.025 mm rhenium foils, and the temperature limit was increased by 25% compared with that of the traditional single-layer assembly. The power-temperature relationships for these two assemblies with different sizes were calibrated by using W/Re thermocouple at 20 GPa. When the volume of samples was the same, the DHA not only attained higher temperature, but also kept the holding time longer, compared to the traditional assembly. The results of more than ten experiments showed that the new 10/4 DHA with a relatively large sample size (2 mm in diameter and 4 mm in height) can work stably with the center temperature of the sample cavity exceeding 2300 ℃ under the pressure of 20 GPa.

Sivells方法在高马赫数低总压喷管设计中的适用性分析

目前高超声速轴对称型面喷管广泛采用Sivells方法进行无黏型面设计,通过求解轴对称的von Kármán动量方程进行边界层修正。该方法在常规高超声速风洞、激波风洞等的高马赫数、高总压条件下已成功应用,但鲜有在高马赫数、低总压条件下的应用研究。在低总压条件下,采用该方法设计了马赫数6、8、10、12的轴对称型面喷管,通过数值模拟分析流场结构,并进行试验验证;模拟了喷管射流流场,通过对射流流场进行结构分析,判断设计方法的适用性。研究结果表明:马赫数6、8喷管流场与设计基本一致,射流流场品质较好,适合开展风洞试验;马赫数10、12喷管流场局部过度膨胀,马赫数高于设计值,其中马赫数10喷管的射流流场品质较好,马赫数12喷管的射流流场品质下降显著且马赫数轴向梯度增大。因此,在高马赫数、低总压条件下,Sivells设计方法仍适用于马赫数6、8喷管,马赫数10喷管处于临界状态,而不适用于马赫数12喷管。

带钢表面高压水射流清洗机理及试验研究

高压水射流技术是冷轧带钢表面清洗的有效技术手段,为了探究高压水射流清洗带钢表面污垢的工作机理,基于计算流体力学理论建立了高压水射流打击力模型,分析了打击力与喷嘴压力和流量的关系。通过正交理论,开展了带钢清洗效果的试验验证,并对不同工况参数下带钢清洗后的表面形貌进行了分析。结果显示,工作压力对于提高带钢清洗后的表面质量影响最为显著。此外,适当增大清洗角度和喷射距离也有助于提高清洗后带钢的表面质量,为优化清洗工艺提供了重要的参考依据。

柔性钻具水力导向射流喷嘴流场分析

现有柔性钻具钻井技术和水力喷射径向钻井技术在控制钻进方向上存在困难或有局限性。为实现钻井导向可控,设计了一种能够水力导向的高压射流喷嘴结构。建立导向喷嘴流体数值模型,利用数值模拟的方法进行流场分析,研究喷嘴倾角、喷嘴直径、喷嘴开启个数等参数对导向力、射流速度的定量关系,给出了导向力方向确定方法。结果表明:随着关闭喷嘴个数的增加,喷嘴导向力呈指数逐渐增大;轴向倾角越大,喷嘴导向力和最大喷射速度越大;喷嘴内径减小时,导向力和喷射速度都显著增大。通过数值模拟验证了射流喷嘴水力导向的可行性,分析结果和导向力的拟合公式对水力导向喷嘴钻进方向的研究具有指导意义。

12Cr2Mo1VR在电站辅机产品中的应用及制造工艺优化

本文主要介绍采用12Cr2Mo1VR材料短筒身的高压加热器,在制造过程中出现裂纹问题,针对此材料进行研究并采取措施,包括优化工艺、改进设计结构等,从而规避风险,保证产品质量。

基于正交试验法的铝合金车体高压水清洗喷嘴结构优化

抑尘剂等复杂的化合物黏着在铝合金车体上,导致车体污染十分严重,高压水射流清洗方法能够有效去除铝合金车辆车体表面黏着的化合物。通过分析圆柱形、锥形、文丘里形和余弦形喷嘴的射流流场分布、射流出口速度、最大壁面静压、相同清洗宽度下压力值范围,得到余弦形喷嘴的清洗性能最佳,锥形喷嘴次之。基于正交试验法设计五因素、四水平正交试验表,得到常用清洗压力下余弦形喷嘴的最优结构参数:进口直径为40 mm、出口直径为20 mm、过渡段半径为40 mm、出射段长度为25 mm、过渡与余弦部分长度比为4。按照最优喷嘴结构参数进行建模,得到三组压力值下高压水出射速度比未优化前提高了2%,且优化效果随着入口压力值的提高而有所下降。在优化后的喷嘴结构参数下进一步计算得出入口压力为10 MPa时,靶距设置为250 mm能达到较好的清洗效果和节能作用。

适用于多种一次调频技术及工况变化的抽汽凝汽式汽轮机数学模型

火电机组是目前电力系统中重要的调频资源,其一次调频能力与汽轮机动态密切相关,但现有汽轮机动态数学模型无法准确反映火电机组在多种一次调频技术以及工况变化情况下的一次调频能力。为准确描述火电机组真实的一次调频动态,该文对汽轮机本体、回热抽汽管道及回热加热器的动态耦合特性进行机理分析,建立适用于主汽阀调节、凝结水节流和高加给水旁路调频技术的汽轮机动态模型;基于机组结构数据及分布式控制系统实测数据,提出跟随工况变化的模型参数在线确定方法;最后,以实际600MW机组为例进行模型验证与仿真分析。结果表明,汽轮机输出功率会受到汽轮机本体和回热系统动态耦合特性的重要影响,且不同工况下机组一次调频能力存在明显差异。该文模型能更准确地描述不同一次调频技术方案及不同运行工况下汽轮机的动态响应特性。

BIM技术在1000MW大型火力发电工程中的应用

随着我国电力建设技术的快速发展,目前1000MW机组工程成为了主流,为保证工程顺利施工,需要借助数字化手段,赋能过程管理。本文介绍了将BIM技术应用于火力发电项目建设过程,辅助进行方案交底,特别是解决重大技术方案不直观、交底不透彻的问题,提升技术交底质量,从而减少返工和成本,产生良好的经济效益。重点介绍一种采用井字架吊具转换吊装高加设备的方法,在吊装施工前进行施工模拟重点技术工艺分析,开展建模内容分析和建模软件选择,进而建模和开展施工模拟,并以其中3个具有代表性的技术工艺模拟优化过程为例,阐述了BIM技术在项目立式高加安装中的应用。通过经济性分析,该施工方案经济效益明显,证明BIM技术的三维化、优化性、模拟性等优点,对于保障危重大施工方案的安全、顺利实施可以发挥十分重要的作用。

高压无气喷涂喷雾流场的CFD仿真分析

为充分了解船舶内场涂装常用的高压无气喷涂技术的雾化原理,改进喷涂工艺,提升喷涂质量,采用计算流体力学(CFD)方法对高压无气喷涂喷雾流场进行仿真分析。针对高压无气喷涂质量缺陷,分析高压无气喷涂的雾化机理,采用FLUENT软件内置的转杯雾化模型建立流场并设置边界条件,研究不同工艺参数下的喷涂效果。研究发现:喷涂压力越大,雾化的液滴直径越小,液滴运动速度越大,产生的漆膜厚度越大;喷涂间距的变化对液滴速度的影响不大,但会导致喷涂区域变大,液膜变薄;外界风速越大,漆膜厚度损失越多。

火焰清理机高压水除鳞装置的优化

针对板坯火焰清理机高压水除鳞装置除鳞效果差的问题,采取了调整高压水除鳞装置的位置、在高压水管增开排空管道以及将高压水除鳞装置的整体框架改为可拆卸式结构的优化措施,结果表明,板坯表面质量得到提高,同时减少了热坯急冷变形弯曲的现象,上述措施简单、可靠、合理,易于实现。

燃煤机组高压加热器水侧泄漏影响因素分析

为及时发现燃煤机组高压加热器泄漏,对某燃煤机组3号高压加热器水侧泄漏对运行参数的影响进行分析。基于高压加热器泄漏案例,通过建立回热系统分析模型,定量分析3号高压加热器水侧泄漏对正常疏水调节阀开度、给水流量偏差及给水泵汽轮机转速等参数的影响,并进行影响因素敏感性分析。采用定量分析方式明确高压加热器水侧泄漏判断依据,并对各判断依据进行优化组合,确定泄漏预警的最终触发条件,据此开发高压加热器水侧泄漏预警装置。结果表明,高压加热器水侧泄漏预警装置比人为判断提前7天时间,可以有效避免因高压加热器泄漏引发的安全事故。

高加危疏阀泄漏对汽轮机性能试验热耗率的影响

针对某电厂2号机组性能试验中3号高加危疏阀无法测量泄漏量导致计算热耗率比实际值虚高的情况,基于ASME PTC6标准,以凝结水流量为基准进行推导分析,认为高加危疏阀存在泄漏但又无法测量泄漏量,会对给水流量和热耗率的计算产生严重干扰。通过建模仿真计算了不同高加危疏阀泄漏量对汽轮机热耗率的真实影响、特性关系及泄漏未被考虑时对热耗率的影响,进而建议性能试验前特别关注高加危疏阀的隔离效果,确保高加危疏阀不存在泄漏,以保证试验结果的客观性。

解析高压水刮刀能有效解决输送皮带漏料扬尘

带式输送机上因黏料问题,需要配备多道清扫器来解决,但是传统利用清扫器上的刮刀彻底刮除输送带表面的黏料效果是不佳,存在漏料和扬尘问题。主要深度分析高压水刮刀的结构和性能,利用高压水刮刀对输送带面物料运行轨迹造成冲击面,将黏料冲击干净,利用清扫器的辅助功能进行刮水浆,达到干净和湿润,从而有效解决输送带漏料和扬尘的问题。

某电厂高压加热器电动门跳闸保护逻辑优化

针对某电厂5号、6号机组高压加热器电动门保护逻辑存在的安全隐患,提出“3取2”的动作逻辑条件,设计安装电动门阀位确认装置,优化逻辑并进行试验。结果表明,改进后的逻辑可有效防止高压加热器电动门误动导致的高压加热器受损事故,延长其使用寿命,保证机组安全稳定运行。

节流孔板在海上高温高压气田的推广应用

海上高温高压气田在节流降压方面存在诸多难题,基于此,参考已有开发经验,结合孔板节流原理,提出了通过井下节流降温来解决采油树抬升问题、油嘴后加装节流孔板解决油嘴冲蚀问题、工艺系统加装限流孔板解决排液阀冲蚀和系统不稳定问题。同时,系统分析了孔板阻塞流、空化气蚀瓶颈,给出了计算孔板节流级数、温度的方法与公式,现场应用效果良好。形成了一套可用于高温高压气田不同生产时期的孔板节流工艺设计方案,确保气田安全、高效、稳定开发。