燃气轮机进气冷却技术分析

文中分析了四种不同燃机进气冷却技术的特性和适用条件,给出了评价不同冷却技术经济性的方法和措施,并从理论上分析了燃汽轮机进气温度对燃机机组效率的影响,提出优化方案,为开展燃机进气冷却工程的评估和设计提供了优化思路。     

耦合喷射制冷的微燃机CCHP系统设计及性能分析

考虑到微燃机在夏季高温环境下性能下降导致CCHP(冷热电三联产系统)运行偏离设计工况,本文提出了利用CCHP系统烟气余热进行喷射制冷,并利用该冷量对微燃机进气进行冷却的研究思路。理论计算发现:以青岛为例,在夏季工况下,对微燃机进气进行冷却可以提高出力16.4%,提高发电效率7.5%左右;对比微燃机进气冷却前后,CCHP系统一次能源效率可提高25%左右,而系统一次能源节约率可提高3%~10%;同时系统单位发电量的CO_2排放量可降低约37%。因此,在夏季高温季节对微燃机进行进气冷却可以改善微燃机和CCHP系统运行性能。     

燃气轮机内环水余热回收研究

通过对燃机内环水所携带热量的研究,设计换热器,论证了用内环水加热燃机天然气进气的可行性,从而达到回收内环水余热,节约能源的目的。     

Maisotsenko循环在燃气轮机进气冷却中的应用研究

采用基于Maisotsenko循环的露点间接蒸发式冷却作为进气冷却的手段,研究了不同环境条件下其对燃气轮机性能的提升效果。建立了针对某9E级燃气轮机的热力循环过程的计算模型,并利用该热力模型分析了进气温度变化对燃机出力的影响。基于Maisotsenko循环的原理,以温降为指标对露点间接蒸发冷却器的性能进行了分析。以功率和效率作为指标,对燃气轮机性能随环境条件的变化情况做了数值模拟,对露点蒸发式冷却与无进气冷却、直接喷雾式冷却对燃机性能的影响进行了计算分析。结果表明,在高温低湿度的条件下,露点间接蒸发式冷却能有效提升燃机性能。     

燃气轮机进气制冷技术

本文根据燃气轮机性能曲线,利用余热锅炉后的剩余余热,作为溴化锂制冷机组的热源,对燃机进气进行冷却,达到增大出力、降低能耗的双重效益。     

燃气轮机进气冷却系统研制

燃气轮机的性能受到环境温度的影响,高温时其出力随进入燃机的空气温度升高而降低的问题可通过进气冷却来解决.提出了一种燃气轮机进气冷却系统的设计方案,介绍了一种双工况燃气轮机进气冷却系统以及使用西门子工控软件WinCC与STEP7对监控系统的设计.运行结果表明,该进气冷却系统具有显著的经济效益.     

板式间接蒸发冷却换热器的层流特性研究

间接蒸发冷却换热器与传统空调相比具有环保与节能的优点。由于蒸发冷却过程的传热传质机理复杂,本文针对板式间接蒸发冷却换热器,建立了三维稳态传热传质数学模型,并确定了合适的边界条件。通过数值模拟得到了压力场、温度场和浓度场的分布,并讨论了通道间距、速度、温度以及相对湿度等因素对换热效果的影响,为间接蒸发冷却换热器的设计提供了理论指导。     

利用制冷站余量合理降低燃机进气温度的可行性分析

某燃机电厂配置的溴化锂制冷站尚有剩余容量没有利用,而当地的气温、空气湿度常年较高,对燃机运行负面影响较大。文章首先研究并确定了把这一剩余容量用于冷却燃机进气的可行性,从而提高燃机出力及效率。其次,本文解决了如何在多台燃机之间合理分配剩余制冷容量的问题。在查找相关设计参数、工质参数、机组运行记录基础上,进行综合数据计算,求出不同分配方案的经济收益。通过综合评比,最终得到两个优选方案。     

燃料油回油冷却系统改进

介绍了采用阿法拉伐公司板式换热器作为回油系统冷却的换热器，由于传热性能良好，解决了油库回油超温问题。     

燃机电厂天然气加热单元设置分析

燃机电厂中的调压站及前置处理模块,是改善天然气品质,使其符合燃气轮机进气要求的处理系统,而其中加热单元的设置对燃机进气温度有着重要的影响,直接关系到燃机能否正常运行。以马来西亚SPR能源集团6B级燃机联合循环电厂所配置的加热单元设置为例,介绍和分析其设置方案,为同类项目的设计提供参考。     

大型联合循环机组关键问题的探讨

随着“西气东输”及“引进液化天然气”工程的实施,我国将建设一批大型燃气—蒸汽联合循环电厂。本文就大型燃气—蒸汽联合循环机组的效率、余热锅炉型式、轴系布置、进气冷却等关键技术问题进行了探讨。     

单元式露点蒸发冷却装置的实验研究

本研究设计了一台由干、湿通道相结合的单元式露点蒸发冷却装置,通过实验研究了蒸发冷却装置在空气经过一级冷却的模式1和经过二级冷却的模式2两种运行模式下,不同空气入口参数时的换热效果。实验结果表明,空气的入口温度越高,换热效果越好;低湿度时空气的进出口温差比高湿度时大,但其湿球效率和露点效率反而较低,这说明2种效率并不适用于不同湿度间的冷却效果对比;模式2运行时的换热效果比模式1好。与已有研究成果对比表明,该单元式露点蒸发冷却装置的湿球效率和露点效率分别可以达到120%和88%,为露点蒸发冷却装置的优化设计提供理论依据和优化方向。     

Numerical investigation on the heat and mass transfer in a direct evaporative cooler

A simplified mathematical model is developed to describe the heat and moisture transfer between water and air in a direct evaporative cooler. The mass of evaporated water is treated as a mass source of air flow, and the related latent heat of water evaporation is taken as a heat source in the energy equation. The momentum caused by water evaporation is taken into account in the momentum equations. The effective air viscosity and diffusion coefficient are decided experimentally. The models and methods are validated by comparing the numerical results with those of experiment for the same evaporative cooler. The influences of the inlet frontal air velocity, pad thickness, inlet air dry-bulb and wet-bulb temperatures on the cooling efficiency of the evaporative cooler are calculated and analyzed.The cooling effects of the direct evaporative cooler are predicted for use in four different regions in northwest China using the present numerical method and local weather data for air conditioning design. The predicted results show the direct evaporative cooler with high performance pad material may be well applied for air conditioning with reasonable choices for the inlet frontal velocity and pad thickness.     

自然通风湿式冷却塔加装挡风板优化设计

以湿冷机组自然通风冷却塔相关理论为基础,借助于CFD模拟软件,建立了火电机组湿式冷却塔的传热传质模型,主要的换热区域如填料、雨区和喷淋区采用离散相模型。由于冬季气温较低和塔内的换热不均,在冷却塔的填料下面、进风口处、基环面容易结冰,提出了在进风口处加装挡风板的方案,数值模拟分析结果显示,该方案改善了塔内温度场,有效的防止了塔内结冰。     

Thermal characteristics of air-water spray impingement cooling of hot metallic surface under controlled parametric conditions

Experimental results on the thermal characteristics of air-water spray impingement cooling of hot metallic surface are presented and discussed in this paper.The controlling input parameters investigated were the combined air and water pressures,plate thickness,water flow rate,nozzle height from the target surface and initial temperature of the hot surface.The effects of these input parameters on the important thermal characteristics such as heat transfer rate,heat transfer coefficient and wetting front movement were measured and examined.Hot flat plate samples of mild steel with dimension 120 mm in length,120 mm breadth and thickness of 4 mm,6 mm,and 8mm respectively were tested.The air assisted water spray was found to be an effective cooling media and method to achieve very high heat transfer rate from the surface.Higher heat transfer rate and heat transfer coefficients were obtained for the lesser i.e,4 mm thick plates.Increase in the nozzle height reduced the heat transfer efficiency of spray cooling.At an inlet water pressure of 4 bar and air pressure of 3 bar,maximum cooling rates670℃/s and average cooling rate of 305.23℃/s were achieved for a temperature of 850℃ of the steel plate.     

Analysis of parameters affecting the performance of gas turbines and combined cycle plants with vapor absorption inlet air cooling

The integration of an aqua‐ammonia inlet air‐cooling scheme to a cooled gas turbine‐based combined cycle has been analyzed. The heat energy of the exhaust gas prior to the exit of the heat recovery steam generator has been chosen to power the inlet air‐cooling system. Dual pressure reheat heat recovery steam generator is chosen as the combined cycle configuration. Air film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor–pressure ratio, compressor inlet temperature, turbine inlet temperature, ambient relative humidity, and ambient temperature on performance parameters of plants has been carried out. It has been observed that vapor absorption inlet air cooling improves the efficiency of gas turbine by upto 7.48% and specific work by more than 18%, respectively. However, on the adoption of this scheme for combined cycles, the plant efficiency has been observed to be adversely affected, although the addition of absorption inlet air cooling results in an increase in plant output by more than 7%. The optimum value of compressor inlet temperature for maximum specific work output has been observed to be 25 °C for the chosen set of conditions. Further reduction of compressor inlet temperature below this optimum value has been observed to adversely affect plant efficiency. Copyright © 2013 John Wiley & Sons, Ltd.     

空气含量和水侧污垢对凝汽器传热系数影响的数值分析

以N12180凝汽器为例,采用自行编制的程序数值计算了空气浓度和污垢对凝汽器汽侧传热系数、冷却管壁导热系数以及平均传热系数的影响,分析了空气与污垢对传热过程的影响机理。结果表明：凝汽器进口空气浓度从0增加到0．01％时,凝汽器平均传热系数降低30％;0．5mm的污垢厚度将使冷却管壁的导热系数降低98％,凝汽器平均传热系数降低85％。     

Utilization of the cryogenic exergy of LNG by a mirror gas-turbine

In the course of worldwide efforts to suppress global warming, the saving of energy becomes more important. Recently, LNG (liquefied natural gas) terminals in our country have received more than 50 million tons of LNG per year. Therefore, the utilization of the cryogenic exergy in connection with the regasification of LNG gains more and more importance. The aim of this paper is the recovery of the energy consumed in liquefaction using the MGT (mirror gas-turbine), which is a new kind of combined cycle of a conventional gas-turbine worked as a topping cycle and TG (inverted Brayton cycle) as a bottoming cycle. The optimum characteristics have been calculated and it is shown that this cycle is superior to the current-use gasification systems in employing seawater heat in terms of thermal efficiency and specific output. In the present cycle, the cold LNG is used to cool the exhaust gas from a turbine of a TG, and then the exergy of the liquefied natural gas is transformed, with a very high efficiency, to electric energy. The main feature of this new concept is the removal of an evaporation system using seawater.     

板翅式换热器在燃气轮机进气冷却系统中的应用

将板翅式换热器应用于吸收式燃气轮机进气冷却系统中，降低燃气轮机压缩机进口温度，提高燃气轮机高温条件下的出力，在国内尚无先例。针对板翅式换热器，简要介绍了结构、布置形式和性能。通过实测的运行数据，对板翅式换热器和管式换热器的性能进行了对比。结果表明：板翅式换热器在传热系数、体积、进气阻力等方面，性能优于管式换热器，是一种值得发展的换热设备。最后提出了该板翅式换热器在实际应用中存在的一些问题及对应的处理方法。     

Energetic and exergetic performance analyses of a combined heat and power plant with absorption inlet cooling and evaporative aftercooling

In this paper, exergy method is applied to analyze the gas turbine cycle cogeneration with inlet air cooling and evaporative aftercooling of the compressor discharge. The exergy destruction rate in each component of cogeneration is evaluated in detail. The effects of some main parameters on the exergy destruction and exergy efficiency of the cycle are investigated. The most significant exergy destruction rates in the cycle are in combustion chamber, heat recovery steam generator and regenerative heat exchanger. The overall pressure ratio and turbine inlet temperature have significant effect on exergy destruction in most of the components of cogeneration. The results obtained from the analysis show that inlet air cooling along with evaporative aftercooling has an obvious increase in the energy and exergy efficiency compared to the basic gas turbine cycle cogeneration. It is further shown that the first-law efficiency, power to heat ratio and exergy efficiency of the cogeneration cycle significantly vary with the change in overall pressure ratio and turbine inlet temperature but the change in process heat pressure shows small variation in these parameters.