节能变风量空调系统探讨

以最常用的风量自动调节式节流变风量空调系统的自动控制为例，介绍了变风量空调控制中送风静压控制、送风流量控制的原理和应用。     

风机泵类调速控制与节能

风机泵类调速控制与节能浙江省杭州钢铁集团公司程鹏，刘建芬风机、水泵在使用过程中均要求风量、流量可调节或为间歇工况，而目前大部分是采用恒速可运转，全压供风。在设计时，又往往增加风机、水泵的富余量，无形中又提高了电动机的功率。在进行风量、流量调节时，大部...     

循环流化床垃圾焚烧炉汽包水位的自调整模糊控制

针对垃圾焚烧炉热负荷波动频繁、给水调节阀调节精度较低的现状,采用自调整模糊控制策略,实现了汽包水位在±10mm范围内的自动控制,符合锅炉运行要求。试验结果表明:自调整模糊控制策略特别适用于具有非线性环节的对象控制。该控制系统在减小水位偏差的同时,注重维持给水流量和主汽流量之间的相互平衡,减少给水调节阀的频繁动作,更有利于提高水位调节的快速性、鲁棒性和调节精度。图4表2参3     

调频电机在常减装置中的应用

利用变频调速器控制电机和机泵的转速，从而实现用转速调节法调节液态介质的流量，达到降低电能消耗，减少生产成本，提高企业经济效益的目的。     

变频调速在空调系统节能中的应用研究

分析了空调系统流体输送的特点和流量调节方式,指出变频调速装置用于空调的变流量（水量、风量）调节可显著节能,并以实例说明变频调速系统在经济上的可行性。     

通风机的节能大有潜力

<正> 全国拥有通风机几百万台,所消耗的能量是相当可观的。有的厂矿通风机所耗能量占全厂电耗的三分之一。目前全国拥有的通风机,大部分是老产品,结构陈旧,效率极低。且由于设计不合理,以及无调节流量装置或因操作管理等问题,浪费了大量电能,因此研制新型高效节能通风机和采用各种调节风量等措施提高风机的运行效率,势在必行,大有潜力。     

液粘调速装置在节能减排中的应用

针对水泵风机采用恒速节流调节运行时存在浪费大量电能的问题,吉林油田水厂选用液粘调速装置改造水泵机组后,通过改变水泵和风机转速调整水量、风量,使轴功率大幅度降低,节约大量电能,经济效益可观。     

变频调速器在锅炉引风机中的应用

一、采用风门挡板调节风量,存在浪费电能的问题我厂的锅炉主要是负责供应全厂生产用汽的动力设备,由于生产用汽量的变化比较频繁,波动幅度大,往往在用汽高峰时,需要加大锅炉的供汽量,而在生产用汽量减少,蒸汽压力上升时,又要降低锅炉的供汽量。为了使锅炉的供汽情况能不断地适应生产用汽的需要,就必须经常调节锅炉鼓务问机的风量。在一天当中,如此反复操作的次数较多,调节的方法是,保持鼓月间机的全速运行,靠调节风机管道内风门档板的开度,来达到控制风量的目的。显然,这种把大量的电能消耗在风门挡板上,是一种浪费电能的不…     

鼠笼式异步电动机改变定子电压调速

引言风机和水泵在实际运行中,是需要调节流量和压头的。由于风量(流量)与风机水泵(以下简称机、泵)的转速成正比,压头与转速的平方成正比,而消耗功率与转速的立方成正比。因此,用降低转速来减小风量时,其消耗功率会降低很多。例如当转速降至额定转速的60％吋,风量也降至额定值的60％,而功耗将降到额定功率的22％,用关小风门以减小风量时,其功耗仅有较小的下降,这是由于许多能量损耗在风门(或挡板)的节流损失上。用两种不同方法控制风量的功率消耗曲线     

内置旁路的外置式蒸汽冷却器在钢铁企业煤气发电机组中的应用

在超高温亚临界煤气发电机组回热系统的3段抽汽设置外置式蒸汽冷却器,以增加3段抽汽高温蒸汽的热量回收,提高锅炉给水温度,提高机组热效率和经济性。针对以往工程的3#外置式蒸汽冷却器采用外置式给水旁路,需额外设置旁路管道及流量孔板,且在变负荷运行时易出现蒸汽冷却器和旁路流量分配偏离设计的现象,提出一种可自动调节的内置旁路结构的蒸汽冷却器,既节省材料又提高可靠性,为后续工程设计提供参考。     

三种水库优化调度方案实施模式的对比研究

为研究水库优化调度方案在水位、流量及出力控制模式下的实施效果,以发电量最大为目标建立优化调度模型并求解,选取发电效益、水位越限风险率及弃水量构建评价指标体系,对不同水库运行工况下的调度方案实施过程进行仿真计算,并评价其实施效果。小漩水电站的实例应用结果表明,水位控制模式对应的水位越限风险率最低,但弃水量最大导致其发电效益最差;流量控制模式与出力控制模式对应的水位越限风险率相差不大,但出力控制模式弃水量更少,发电效益更高。因此,出力控制模式可作为调度方案实施过程中的首选模式。     

Performance of nano-hydraulic turbine utilizing waterfalls

The aim of this investigation was to develop an environmentally friendly nano-hydraulic turbine utilizing waterfalls. A model of an impulse type hydraulic turbine constructed and tested with an indoor type waterfall to arrive at an optimum installation condition. Effects of an installation parameter, namely distance between the rotor and the waterfall on the power performance were studied. The flow field around the rotor was examined visually to clarify influences of installation conditions on the flow field. The flow visualization showed differences of flow pattern around the rotor by the change of flow rate and rotational speed of the rotor. From this study it was found that the power performances of the rotor were changed with the distance between the rotor and the waterfalls. The maximum power coefficient of this turbine is approximately 60%. Also, to respond to changes in the waterfall flow rate, we placed a flat plate on the upper side of the rotor to control the water flow direction. As a result, we found that the coefficient of this turbine is increased with the flow rate and power could be obtained even when the flow rate changed by 3.5 times if the plate was placed on the upper side of the rotor. Although the power coefficient decreased when the plate was installed, the power coefficient still is from 53 to 58%.     

集中供热热网系统节能措施

针对集中供热管网热损失中,热、电消耗所占的比例大的问题,采用预制保温管和管道直埋敷设技术,有效地减少管网的散热损失。通过保证管网的水力失调度,减少热网中水泵的耗电量。采用热网的变流量调节,减少耗电量。加强对热网的管理,降低失水率。     

锅炉单冲量给水调节器设计￣[1]的改进

在大型锅炉汽包水位控制过程中，当蒸汽流量或给水流量突然变化时，会产生严重的虚假水位现象，本文把Ｓｍｉｔｈ预估控制形式应用到给水流量反馈和蒸汽流量前馈中来补偿系统的非最小相位特性，另外把ＰＩ调节器拆分成Ｐ调节器和Ｉ调节器，并使反馈和前馈不进入Ｉ调节器，来消除稳态误差，整个控制系统结构简单，仿真结果表明，它具有良好的控制效果和很强的鲁棒性。     

Improved control strategy for forced flow solar water heating systems

The solar water heating system functioning on a fixed temperature control (FTC) mode, rather than a differential temperature control (DTC) mode (continuous water flow rate), has appreciable advantages for saying parasitic power consumption and reducing the maintenance cost. A computer simulation model, using a numerical analysis method, has been developed to study a forced flow solar water heating system taking into account the realistic conditions of operations. It is noted that the most critical parameter in designing such types of system is the water flow rate. The results are obtained, corresponding to a solar water heating system of 4000 1/day capacity working at an average temperature of 60°C.     

Experimental investigations on the heat transfer characteristics in a natural circulation loop for an integral type reactor

The natural circulation characteristics in the primary loop of an integral type reactor were experimentally investigated during various operational conditions by using the VISTA facility. The test matrices included the natural circulation characterization tests and operational transient tests. The heat transfer characteristics in a natural circulation loop for an integral type reactor were experimentally investigated by using the VISTA facility and steady-state natural circulation tests were performed by changing the core power and feed water flow rate simultaneously. The initial core power and feed water flow rate were 25%. During a natural circulation operation both the core power and feed water flow rate were changed from 20% to 50%. The experimental data were compared with the predictions from existing correlations of Duffey et al. [1] and Vijayan et al. [2]. It was shown that Duffey et al.'s correlation [1] for a two-phase natural circulation predicted the experimental data very accurately. Also four operational transient tests were performed for the cases of feed water increase, feed water decrease, power decrease and power increase. The thermal-hydraulic parameters of core power, flow rate, pressure and fluid temperatures in the primary system, feed water flow rate, pressure and fluid temperatures in the secondary system were investigated. They showed a symmetric behavior between their increases and decreases and a quick stabilization behavior of major thermal-hydraulic parameters including the natural circulation flow rate in the primary loop.     

抽水蓄能电站同发同抽工况下漩涡特性的研究

为探究抽水蓄能电站同发同抽工况的可行性,对某抽水蓄能电站进行物理模型试验研究发现,当电站最低淹没深度满足Gordon公式的要求时,在同发同抽工况下侧向进水口前观测到尺度和强度较大的立轴漩涡。通过分析对比单个水力单元单向发电工况与同发同抽工况的库区流态,得出在同发同抽工况下,抽水侧水体形成的沿岸回流与发电侧表面横流相互挤压后汇聚,对涡核区域水体施加附加剪切力,从而导致回流流速持续增大,产生吸气漩涡。针对产生漩涡的水动力学条件,提出抬高死水位和在进/出水口上方平台加设隔墙两种方案,达到消除同发同抽工况下的吸气漩涡的目的。研究成果可为抽水蓄能电站同发同抽工况研究提供参考。     

Dynamic modeling,simulation and control design of an advanced micro-hydro power plant for distributed generation applications

A small-scale hydropower station is usually a run-of-river plant that uses a fixed speed drive with mechanical regulation of the turbine water flow rate for controlling the active power generation. This design enables to reach high efficiency over a wide range of water flows but using a complex operating mechanism, which is in consequence expensive and tend to be more affordable for large systems. This paper proposes an advanced structure of a micro-hydro power plant (MHPP) based on a smaller, lighter, more robust and more efficient higher-speed turbine. The suggested design is much simpler and eliminates all mechanical adjustments through a novel electronic power conditioning system for connection to the electric grid. In this way, it allows obtaining higher reliability and lower cost of the power plant. A full detailed model of the MHPP is derived and a new three-level control scheme is designed. The dynamic performance of the proposed MHPP is validated through digital simulations and employing a small-scale experimental set-up.     

Optimization of water-cooled chiller system with load-based speed control

This study investigates the energy performance of chiller and cooling tower systems integrated with variable condenser water flow and optimal speed control for tower fans and condenser water pumps. Thermodynamic-behaviour chiller and cooling tower models were developed to assess how different control methods of cooling towers and condenser water pumps influence the trade-off between the chiller power, pump power, fan power and water consumption under various operating conditions. Load-based speed control is introduced for the tower fans and condenser water pumps to achieve optimum system performance. With regard to an example chiller system serving an office building, the optimal control coupled with variable condenser water flow could reduce the annual system electricity use by 5.3% and operating cost by 4.9% relative to the equivalent system using constant speed fans and pumps with a fixed set point for cooling water temperature control.     

Analysis of load‐following characteristics for an integrated pressurized water reactor

Integrated pressurized water reactor (IPWR) usually be equipped with once‐through steam generators (OTSGs). The OTSG has many advantages such as simple mechanical structure, smaller size, and higher heat transfer efficiency. It produces superheated steam but with less inventory in its secondary side. The steam pressure is easily affected by steam flow rate or feed water flow rate. This draws more attention to design advanced reactor control system. In this paper, a study has been carried out to analyze the thermal hydraulic performance of an advanced IPWR under steady‐state and transient conditions by using a thermal hydraulic safety analysis code Relap5. An effective load‐following control system is proposed. The steady‐state operating characteristics of IPWR at different load conditions show that the average primary coolant temperature, steam pressure, and coolant mass flow rate are the most important control parameters. Pump frequency conversion strategy and OTSG grouping run strategy are used to study the transient operating characteristics of IPWR. Simulation results of the control system demonstrate its capability in regulating feedwater flow rate and reactor power to follow the change of steam flow rate. According to the results, the OTSG grouping run strategy is optimized to ensure the OTSG operates safely under low load conditions. Copyright © 2013 John Wiley & Sons, Ltd.