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太原市呼延水厂是山西省引黄入晋的配套工程,为解决山西水利资源,国家投资127亿元人民币,建设了引黄入晋工程,黄河水从万家寨水库经5级提升到达汾河水库,其中一路又经过隧道穿过吕梁山脉到达呼延水厂. 相似文献
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侯峰 《机械工程与自动化》2008,(2):180-182
高分子絮凝剂投加是水厂污泥处理系统中的重要环节.主要介绍了太原市呼延水厂原高分子絮凝投加系统的设计缺陷及改造后新系统的水处理工艺和自动控制系统. 相似文献
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射流放水阀动态关闭过程研究 总被引:1,自引:0,他引:1
射流放水阀是水电站和水坝放水系统中广泛应用的流量控制装置.目前关于射流放水阀的数值模拟均为静止状态下的流场分析,运动状态下的流场数值模拟还未见报道.本文采用温度体模型和重叠分区背景网格方法生成射流阀动态关闭过程中的计算域网格,首次采用数值模拟方式对其动态过程进行研究.数值模拟结果显示,射流阀流量与开度呈近似线性变化规律,但在大开度和小开度范围内,流量随开度的变化较为平缓.水流经阀针后发生分离,在其背部形成主流区、剪切层区和回流区.在阀针外缘处、阀壳喉部及阀针后侧的压力远远低于阀针头部及正面压力,将导致这些区域发生汽蚀.数值模拟结果与实验观测到的现象非常吻合. 相似文献
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文章论述了一种纯机械结构流量安全阀的构成与工作原理,对节流控制口的开度与流量关系进行了理论分析.当自来水管路系统中某一个管子突然断裂跑水,瞬间流量骤增,超过设定最大流量时,流量安全阀自动关闭,切断水路,起到安全保护作用. 相似文献
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针对核电站装卸料机重水供给系统的压力控制过程复杂,操作模式变换时压力互扰大、耦合影响明显,压力流量响应过程很难取得好效果等问题,在深入分析工况的基础上对系统管网结构作了优化调整;通过设计公共母管及泄流阀旁路调节控制改善主管路串行阀进口侧的重水压力,使之有较好的稳定度。出口管路的压力控制由旁路并行阀的开度调节,开度控制采用一种基于自寻优模糊控制的策略,并以此设计了新型控制器。试验结果表明,新型控制方式具有良好的学习功能与抗干扰性能;新的装卸料机重水压力供给系统能达到输出跟随速度快、变化平稳、压差波动小,系统动、静态性能明显提高;克服了常规控制方法存在的压力响应速度慢和超调大等问题。 相似文献
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基于PLC的冷却水恒压系统的设计与实现 总被引:1,自引:1,他引:0
冷却水在金属切削加工中对减少刀具磨损,提高加工质量起着不可或缺的作用。在自动生产线中,要求冷却水的供应能够压力恒定,流量充足。本文介绍了一套工业用冷却水的恒压供应系统。该系统采用性能优异的春日变频器和西门子PLC S7-120s,通过控制各类阀的通断和电动机的启停来控制系统管网内的实际压力始终围绕期望值左右变化,并逐渐降低波动的幅度,以达到压力恒定控制的目的。同时能够使冷却水循环利用,既节约了成本又达到了使用要求,可为同类系统的设计和改进提供参考。 相似文献
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基于PLC的双恒压供水控制系统设计 总被引:4,自引:0,他引:4
该双恒压供水控制系统是以PLC控制为核心,变频调速技术为基础,并结合压力传感器、变频器、水泵、继电器、接触器等组成。在此系统中,PLC将压力设定值与测量值的偏差经PID运算后得到的控制量作用到变频器,从而通过变频器控制水泵的转速调节管网的压力,实现恒压供水的目的。 相似文献
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ZHOU Hua ZHANG Zengmeng GAO Yuan'an YANG Huayong 《机械工程学报(英文版)》2010,23(4):418-427
Water-assisted injection molding(WAIM), an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savings and injection pressure control can not be attained based on conventional valve control system. Moreover, the injection water can not be supplied directly by water hydraulic proportional control system. Poor efficiency and control performance are presented by current trial systems, which pressurize injection water by compressed air. In this paper, a novel water hydraulic system is developed applying an accumulator for energy saving. And a new differential pressure control method is proposed by using pressure cylinder and water hydraulic proportional pressure relief valve for back pressure control. Aiming at design of linear controller for injection water pressure regulation, a linear load model is approximately built through computational fluid dynamics(CFD) simulation on two-phase flow cavity filling process with variable temperature and viscosity, and a linear model of pressure control system is built with the load model and linearization of water hydraulic components. According to the simulation, model based feedback is brought forward to compensate the pressure decrease during accumulator discharge and eliminate the derivative element of the system. Meanwhile, the steady-state error can be reduced and the capacity of resisting disturbance can be enhanced, by closed-loop control of load pressure with integral compensation. Through the developed experimental system in the State Key Lab of Fluid Power Transmission and Control, Zhejiang University, China, the static characteristic of the water hydraulic proportional relief valve was tested and output pressure control of the system in Acrylonitrile Butadiene Styrene(ABS) parts molding experiments was also studied. The experiment results show that the dead band and hysteresis of the water hydraulic proportional pressure relief valve are large, but the control precision and linearity can be improved with feed-forward compensation. With the experimental results of injection water pressure control, the applicability of this WAIM system and the effect of its linear controller are verified. The novel proposed process of WAIM pressure control and study on characteristics of control system contribute to the application of water hydraulic proportional control and WAIM technology. 相似文献
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《Measurement》2016
This paper presents the instrumentation and control architecture for a laboratory based two-stage 4-bed silica gel + water adsorption system. The system consists of primarily two fluids: refrigerant (water vapour) and heat transfer fluid (water) flowing through various components. Heat input to the system is simulated using multiple heaters and ambient air is used as the heat sink. The laboratory setup incorporates a real time National Instruments (NI) controller to control several digital and analog valves, heaters, pumps and fans along with simultaneous data acquisition from various flow, pressure and temperature sensors. The paper also presents in detail the various automated and manual tasks required for successful operation of the system. Finally the system pressure and temperature dynamics are reported and its performance evaluated for various cycle times. 相似文献
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陈贵银 《机械工程与自动化》2011,(6)
通过分析目前的用水情况,设计出一个采用89C51单片机智能控制水位高低的经济型系统,该系统通过对生活用水的二次利用和冲刷大小便所用水量的情况不同来达到节水的目的. 相似文献
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