Experimental Study on the Resistance and Splash Performances of Water Collecting Devices for Mechanical Draft Cooling Towers

In recent years,water collecting systems,with the associated advantages of energy saving and noise reduction,have become the foundation for the development of a scheme to optimize the structure of cooling towers.To explore the feasibility of this approach for mechanical draft cooling towers,a small-scale experimental device has been built to study the resistance and splash performances of three U-type water collecting devices(WCDs)for different water flow rates and wind speeds.The experimental results show that within the considered ranges of wind speed and water flow rate,the pressure drop of the different WCDs can vary significantly.The resistance and local splash performances can also be remarkably different.Some recommendations about the most suitable system are provided.Moreover,a regression analysis of the experimental data is conducted,and the resulting fitting formulas for resistance and splash performance of WCD are reported.

A New Water Saving Device of Swirling Flow for Cooling Towers

This paper is concerned with water saving for water-loop cooling tower system in power plants. A newly developed water saving device of swirling flow is presented. The key point is that the new water saving device makes the steam swirl up along the device wall rather than engender laminar flow in a corrugated plate. The corrugated plate device can save approximately 10 percent of the total lost water. In contrast to the scale model of corrugated plate water saving device, experimental analyses have demonstrated that the new water saving device of swirling flow is more efficient, with a capacity of saving more than 20 percent of water.

Improved Efficiency of Heat Exchange Using KELEA Activated Water

An environmental force termed KELEA (kinetic energy limiting electrostatic attraction) is postulated to reduce the strength of intermolecular (hydrogen) bonding of water molecules, resulting in increased kinetic activity of the water. While regular water does not directly absorb KELEA from the environment, various dipolar compounds with separated electrical charges can seemingly act as a primary antenna for KELEA, with secondary transfer of energy into nearby water. Moreover, once sufficiently activated, the separated electrical charges in activated water can apparently function as a receiver for KELEA, leading to further activation of the water and also to the activation of added water. Prior publications have addressed the agricultural and potential clinical benefits of using KELEA activated water. This article is intended as the first in a series of papers describing useful industrial applications of KELEA activated water. The focus of the present paper is on the improved efficiency of industrial water heating and cooling systems by using KELEA activated water provided by pelleted, ground and heated volcanic rock as supplied by Kiko Technology.

Performance Analysis of Automated Control System for Condenser Water Treatment Unit

The air conditioning system in the Umm Al-Qura University (Albdiya Campus) was conceived to be a district cooling by a remote chilled water plant. Recently, there are two chilled water plants in the university installed strategically to provide chilled water to all the academic and administrative buildings of the university through distribution network with total capacity approximately of 12,000 tons of refrigeration. The plants were built based on cooling towers with open water cycle as heat rejection system. Water treatment chemicals has been used to protect the cooling systems from corrosion, scaling and microbiological fouling accompanied with dissolved and suspended water impurities. Different methods are being used to determine and control the treatment chemical concentrations and system performance indicators. Traditional chemical controller has drawback of indirect measurements and set points. The purpose of this paper is to present a solution to overcome the problems of traditional and conventional chemical treatment and control sys-tems. Central cooling plant number (1) assigned to perform experimental setup using new chemical treatment technology. Advanced automatic chemical treatment controller installed on condensers (1, 2 and 3), and certain key performance indicators were selected and monitored such as chemical and water consumption, power, energy saving, and maintaining system integrity and efficiency. Satisfactory results were obtained in terms of performance and cost of operation.

某大科学装置项目工艺冷却水系统设计

介绍了某在建大科学装置项目的工艺冷却水系统设计,包括服务对象、系统形式、系统组成、水温控制策略、流量控制策略等方面的内容。简述了热回收型水源热泵在工艺冷却水系统中的应用方案,并对工艺冷却水系统设计后续可开展的工作和研究提出了3个方向。

自然通风湿式冷却塔节水方案的数值研究

为降低自然通风湿式冷却塔的耗水量,本文采用一种可用于回收其蒸发损失的空气冷凝器结构,并通过数值模拟方法对其节水特性展开研究。首先基于空气运动控制方程和水蒸气冷凝模型,建立了用于分析空气冷凝器节水特性的数学模型,其次分析了冷却空气流速、空气冷凝器的结构尺寸和材质等因素对该冷凝器节水特性的影响。研究结果表明:空气冷凝器的单位面积节水量随着冷却空气流速以及冷凝器宽度的增大而增大,但随着冷凝器长度和高度的增大而减小;空气冷凝器的材质和壁厚对其单位面积节水量没有显著影响,空气冷凝器可采用重量轻和成本低的薄壁PVC来加工制造。

超大型海水冷却塔盐沉积影响数值模拟研究

针对核电项目中的大型海水冷却塔,采用三维数值模型,结合厂址气象数据、冷却塔设计参数、总图布置以及周围环境特征,研究了2座超大型自然通风海水冷却塔在建筑物、自然风相互作用下的冷却塔飘滴扩散迁移特征和盐沉积量。结果表明,当环境风向与塔排平行时,出口热空气相互叠加形成一股气流,有利于减少飘滴和盐沉积对环境的影响;粒径大于550μm的飘滴不能从高位冷却塔出口逸出;2台核电机组正常运行工况时,盐沉积量一般不会对植物造成损坏。

大型冷凝式消雾节水冷却塔性能试验研究

为研究获得菱形模块消雾节水冷却塔的消雾节水和节能特性,对某设计循环水量为5000 m^(3)/h的菱形消雾节水冷却塔的消雾性能、节水性能和节能性能进行了试验研究。建立了冷却塔消雾节水节能性能评价模型,通过现场试验获得冷却塔消雾节水和节能特性参数及其变化规律。结果表明:消雾节水冷却塔设计出塔空气相对湿度为85%,实测出塔相对湿度为82.28%,消雾指数为1.03,符合“零雾型”消雾冷却塔的要求。经菱形消雾冷凝模块换热后的冷凝水量为14.19 m^(3)/h,冷却塔节水率为25.3%,冷凝节水效果好。单塔年总节能收益约40万元,整体年节能收益达240万元,菱形消雾节水冷却塔具有良好的经济效益及环保效益。

配水方式对冷却塔热力性能的影响研究

为了研究电厂在调峰影响下低负荷运行时合理的配水方式,探寻冷却塔“带水”检修的可能性,采用三维数值模拟方法,计算了某高位收水冷却塔两机六泵全塔配水、一机三泵全塔外围配水和一机三泵半塔配水方式下的塔内外流场特性及热力性能。分析了外围配水和半塔配水可能存在的进塔空气全部从未淋水区域的填料流过而不与淋水填料换热的问题,并统计了配水方式对冷却能力的影响。结果表明,外围配水、半塔配水虽然不存在进塔空气全部从未淋水区域的填料流过的情况,但分区配水热力性能易受到环境风影响,在改善电厂调峰低负荷运行条件下的冷却塔热力性能方面起负面效果。

基于外部冷却模块和内部凝雾模块的高位收水机械通风冷却塔性能对比研究

为了控制雾羽和节约水资源,搭建了高位收水机械通风冷却塔热态实验系统,分别对外部冷却模块(干湿联合冷却塔)和内部凝雾模块(凝雾式冷却塔)的消雾、节水及热力性能进行对比分析,研究了环境温度、循环水进水温度及循环水量对冷却塔性能的影响。结果表明:干湿联合冷却塔和凝雾式冷却塔均具有消雾和节水能力,但实现二者的消雾和节水是以降低冷却塔冷却性能为代价的;与原塔相比,干湿联合冷却塔和凝雾式冷却塔的循环水温降约降低了1.5 K;干湿联合冷却塔和凝雾式冷却塔的消雾和节水性能受运行参数的影响很大,且凝雾式冷却塔的节水量和节水率高于干湿联合冷却塔。

基于定热负荷的自然通风湿式冷却塔防冻特性三维数值研究

针对湿式冷却塔(湿冷塔)冬季运行易出现填料底层、进风口上缘等位置易挂冰的实际问题,建立了基于定热负荷的自然通风湿冷塔三维数值模型,探究了湿冷塔在严寒天气不外加防冻装置运行时的防冻特性规律,分析了填料底层水温、通风量等关键参数的变化特征及影响因素。研究结果表明:环境温度越低,机组负荷对填料底层平均水温、最低水温的影响越大;填料底层水温偏差变化的主要因素是机组负荷、环境风速、配水方式,其中配水方式的影响幅度较大,机组负荷次之,环境风速影响较小;通风量与机组负荷呈正相关关系,与环境温度呈负相关关系;环境温度相同时,外圈配水下的通风量小于全塔配水;迎风侧内部较低处及背风侧外部的水温最低,冻结风险最大,湿冷塔冬季运行时,应着重在迎风侧和背风侧进行防冻装置布置。

Three-dimensional Numerical Study on Thermal Performance of a Super Large Natural Draft Cooling Tower of 220m Height

Based on the heat and mass transfer theory and the characteristics of general-purpose software FLUENT, a three-dimensional numerical simulation platform, composed of lots of user defined functions(UDF), has been developed to simulate the thermal performance of natural draft wet cooling towers(NDWCTs). After validation, this platform is used to analyse thermal performances of a 220m high super large cooling tower designed for inland nuclear plant under different operational conditions. Variations of outlet temperature of the cooling tower caused by changes of water flow rates, inlet water temperatures are investigated. Effects of optimization through non-uniform water distributions on outlet water temperature are discussed, and the influences on the flow field inside the cooling tower are analyzed in detail. It is found that the outlet water temperature will increase as the water flow rate increases, but the air flow rate will decrease. The outlet water temperature will decrease 0.095K and 0.205K, respectively, if two non-uniform water distribution approaches are applied.

NUMERICAL SIMULATION OF FLOW FIELDS IN A NATURAL DRAFT WET-COOLING TOWER

The flow field in the hyperbolic natural draft wet-cooling tower, which has great effects on the economy and security of power plant, was studied through numerical simulation. The mathematical model was established and analyzed in order to optimize the cooling-tower and to evaluate its efficiency. Various working conditions were considered and compared with each other, such as the circulating water flux, air temperature and tower resistance. It is concluded that when the cooling-tower runs without wind, there is a vacuum region inside the tower and the pressure rises with the increase of the tower height. Meanwhile, the inner flow field is axisymmetrical. The air velocity achieves its climax at the axis. It is also found that the effect of circulating water temperature is equivalent to that of the water flux.

Model free optimization of building cooling water systems with refined action space

Deep Q Network(DQN)is an efficient model-free optimization method,and has the potential to be used in building cooling water systems.However,due to the high dimension of actions,this method requires a complex neural network.Therefore,both the required number of training samples and the length of convergence period are barriers for real application.Furthermore,penalty function based exploration may lead to unsafe actions,causing the application of this optimization method even more difficult.To solve these problems,an approach to limit the action space within a safe area is proposed in this paper.First of all,the action space for cooling towers and pumps are separated into two sub-regions.Secondly,for each type of equipment,the action space is further divided into safe and unsafe regions.As a result,the convergence speed is significantly improved.Compared with the traditional DQN method in a simulation environment validated by real data,the proposed method is able to save the convergence time by 1 episode(one cooling season).The results in this paper suggest that,the proposed DQN method can achieve a much quicker learning speed without any undesired consequences,and therefore is more suitable to be used in projects without pre-learning stage.

空调水冷冷水制冷系统调适技术探讨

基于空调系统调适技术的发展现状,以空调水冷冷水制冷系统为研究对象,探讨了冷水机组、冷却塔和水泵的调试评价指标和效果验证方法,介绍了水冷冷水系统的常见系统形式和制冷机房常见问题及解决措施,以达到提高水冷冷水系统的整体运行性能、降低冷水系统运行能耗的目的。

循环水温度对CCPP机组真空度影响的探究

CCPP机组真空度降低,对机组运行稳定性和发电效益会产生影响,通过对CCPP机组真空度降低原因的排查,确认循环水温度升高是导致CCPP机组真空度降低的根本原因。而循环水温度升高又与冷却塔的冷却效果有关,分析确认冷却塔填料结垢是造成冷却塔冷却效果差的原因。通过分析结垢物和产生结垢的原因,提出解决填料结垢的处理方案,保证冷却塔的冷却效果。

塔体构型对钢结构间接空冷系统输运性能的影响研究

以2×350MW空冷机组为研究对象,采用数值模拟方法,详细探究了不同环境风速下,不同塔型空冷系统的流动换热特性;从系统整体至局部扇区两个层面上,揭示了不同塔型条件下空冷散热器水侧换热量和出口水温分布规律。研究结果表明,随环境风速增加,不同塔型间接空冷系统流动换热性能均下降;无风环境下,双曲线塔型冷却性能优于所有直锥塔型;各环境风速下,锥段比为0.2直锥塔型冷却性能低于其他塔型结构;环境风速4 m/s时,锥段比为0.5直锥塔型冷却性能优于其他塔型结构,且在环境风速8 m/s和12 m/s时,仍呈现较好的冷却性能。本研究可为钢结构间接空冷系统结构选型和设计提供理论支撑。

开式消雾节水技术在工业循环冷却水中的应用

循环冷却水系统节水是工业企业节水、节能的一个重要环节。常规开式循环冷却水塔因塔顶排放口易产生大量白雾,造成水资源的浪费;新型冷凝模块消雾节水冷却塔技术在消除白雾和节水方面成效显著,近年来受到广泛关注。分析了消雾节水冷却塔的消雾节水及工作原理,并与常规开式冷却塔进行了基本参数、运行费用、投资等方面的初步对比。初步估算,消雾节水冷却塔与常规冷却塔相比,蒸发水量和排污量可减少约20%,设备投资增加约80%,但整体运行费用较低,其投资成本在两年左右即可收回,在化工行业具有较好的应用前景。

某大型石化项目海水冷却系统设计

通过国外某大型石化项目海水冷却系统设计,对海水直流冷却及海水循环冷却2种设计方案进行比较,从工艺流程、平面布置、构筑物设置、设备选型及投资估算等方面进行探讨,分析了设计中注意事项,以及设计中遇到的重难点问题,总结出相关思路及经验,以供类似项目参考。

空分设备冷却水系统技术改造总结

夏季高温,针对35 000 m^(3)/h空分设备循环冷却水温度与分子筛吸附器进气温度大于高报警值问题,对空分设备循环冷却水系统增设冷却风机、空气预冷系统增设冷冻机,保障空分设备在夏季高温条件下安全、稳定、经济运行。叙述35 000 m^(3)/h空分设备在夏季高温状态运行时,循环冷却水温度与分子筛吸附器进气温度大于高报警值的原因,介绍35 000 m^(3)/h空分设备增设冷却风机与冷冻机技术改造的具体措施、效果。