伪随机序列声源信号在电站锅炉声学测温中的应用

为了获得电站锅炉炉膛温度信息,开发了单路径炉膛烟气温度声学监测系统,引入伪随机序列作为声源信号.在国内某200MW和300MW锅炉上进行了热态试验研究,并利用自制的K型陶瓷热电偶对测量温度进行了标定.结果表明：伪随机序列信号可以作为声学测温的声源信号,但由于其频带过宽,必须进行处理,使其能量集中;测温系统测量的烟气温度与热电偶测量温度相比,误差在2%以内;基于伪随机序列声源的声学测温系统所测温度曲线与负荷曲线吻合,具有很好的稳定性.     

声学测温系统在200MW电站锅炉中的应用研究

为了实现炉膛温度场实时在线监测,在前期单路径声学高温计试验成功的基础上开发了多路径声学测温系统,并首次在国内某电厂的200 MW机组锅炉上进行了安装调试.结果表明：基于相位变换加权的互相关算法,可以有效去除冷态条件下炉膛强混响影响,准确得出声波飞渡时延估计值;经过热态试验验证了该系统的稳定性和可靠性;声学测温系统为传统的高温测量领域提供了新技术,将电站锅炉的燃烧情况可视化,有助于运行人员实时调整燃烧,防止火焰中心偏移,确保锅炉的安全经济运行.     

基于声阵列的电站锅炉水冷壁泄漏定位研究

在声学测温系统测点布置的基础上,融入声阵列定位技术,再现声波测温的同时对炉膛水冷壁的泄漏声信号进行实时监测,并进行泄漏点的精确定位.建立炉管泄漏声阵列定位模型,基于到达时间差定位(TDOA)方法和改进的Chan算法进行三维空间声学定位仿真研究,并进行了空旷环境下和炉膛冷态、热态环境下泄漏点的实验研究.结果表明:仿真与实验结果均符合工程要求,该定位算法具有可行性.     

电站锅炉声学测温中扫频信号声源特性研究

为了对电站锅炉声学测温中的声源进行选择,借助冷态实验台对扫频信号进行了试验研究,并在国内某300 MW锅炉上进行了热态试验.为了确保其准确性,同时利用热电偶进行了热态温度标定.结果表明：线性扫频信号适合作为电站锅炉声学测温中的声源信号;500~3 000 Hz频率段的扫频信号作为声源最为适宜;扫频信号的频率区间越小,互相关时延估计效果越差;扫频周期取0.1 s最为合适;线性扫频信号成功地在300 MW锅炉声学测温系统中得以应用,可为电厂锅炉声学测温的研究提供重要的参考.     

电站锅炉声学测温中时延估计试验研究

对锅炉炉膛冷态和热态声场进行了分析,从理论上对广义互相关时延估计及其加权函数进行了深入探讨,并在国内某300MW机组上安装声学测点,对不同的加权函数进行了冷态和热态试验研究.结果表明：广义互相关时延估计法可以用于声学测温中声波飞渡时间的测量;PHAT加权具有抗混响能力,能在锅炉冷态混响环境下得到准确的时延估计;ML加权具有很好的抗噪能力,能在锅炉热态时得到准确的声波飞渡时间.     

数字式火焰电视监测系统研制及应用

本文介绍了东方锅炉研制的基于双波长理论、采用内窥式成像传感器获取锅炉燃烧火焰图像、通过计算机处理得到炉膛火焰温度场的数字式火焰电视监测系统的结构特点、系统功能和实际使用效果。数字式火焰电视系统与常规炉膛火焰电视和光电高温计的相比，同时具有看火和测温功能，优点明显，是常规炉膛火焰电视系统或光电高温计的替代升级产品。     

轧钢加热炉热电偶测温技术和调节原则

分析了加热炉中热电偶伸入炉膛内长度对炉温测量准确性的影响，介绍了热电偶调节方法和其他影响测温准确性的因素。     

基于声学测温的水冷壁局部超温监测研究

以理论和试验相结合的方法,对锅炉热态时水冷壁附近的温度场及声线分布进行了研究,开发了基于声学测温的水冷壁局部超温监测系统,并在国内某300MW锅炉机组上进行了试验研究.结果表明：声学测温技术应用于水冷壁局部超温监测是完全可行的;锅炉热态时,水冷壁附近的声线会朝着炉膛内高温侧发生弯曲;系统测得的烟气温度作为基准量能很好地反映水冷壁向火侧壁面温度的变化情况;线性扫频信号可以作为监测系统的声源信号,扫频区间在500～3 000Hz为宜;此系统中,互相关时延估计法能准确地计算出声波飞渡时间.     

基于二次相关PHAT-β算法的锅炉声学测温时延估计研究

为了准确获得电站锅炉声学测温中的时延估计,针对传统方法在冷态情况下混响使得测量结果存在多处伪峰值,影响时延估计准确性的问题,提出了一种基于二次相关的相位变换加权(PHAT-β)算法。在实验炉膛和某300 MW机组的测温实验台上进行了实验研究,并将二次相关PHAT-β算法与传统方法进行了对比。结果表明:二次相关PHAT-β算法能准确获得声波的飞渡时间,同时能较好地抑制混响,在锅炉强噪声环境中仍具有较好的适用性,为声学测温时延估计的优化提供了可行方法,同时也对基于时延估计的监测手段提供了新的算法。     

航空发动机高温壁面热电偶测温技术应用

高温壁面温度的准确测量是航空发动机研制过程中的重要环节。热电偶是航空发动机高温壁面测温领域中使用最为广泛的温度传感器。提高热电偶的测温极限、测温精确度以及测温可靠性,是航空发动机试验和测试领域迫切需要攻克和解决的技术难题。本文从铠装热电偶测温技术、薄膜热电偶测温技术和热电偶壁面测温技术修正3个方面,对航空发动机高温壁面热电偶测温技术的研究进展进行了综述。建立热电偶高温壁面测温修正方法将是今后航空发动机高温壁面测温领域需要重点关注的研究方向。     

Measurements of brake disc surface temperature and emissivity by two-color pyrometry

A fiber optic two-color pyrometer was developed for brake disc surface temperature and emissivity measurements. The two-color pyrometer consists of a fluoride glass optical fiber, two HgCdTe detectors equipped with bandwidth filters and a data conditioning and acquisition device. The two-color pyrometer measures the brake disc temperature in the 200–800 °C range with a time resolution of 8 μs. The calibration formula for the signals obtained using a blackbody of known temperature is used to compute the true temperature. The uncertainty estimation for temperature and emissivity was obtained from the calibration results. Tests were carried out on known temperature target and a good correlation was found between results obtained with our two-color pyrometer and those obtained with a commercial two-color pyrometer. Hold braking and deceleration braking tests performed on a braking test bench enabled us to reach the brake disc surface temperature and emissivity during braking. Experimental results show a significant variation of emissivity during braking. Direct measurement of emissivity was carried out on the brake disc after braking and shows the emissivity dependence with the surface quality.     

声学法锅炉温度场检测技术及应用

声学法锅炉温度场检测技术是近年来发展起来的一项新技术。介绍了声学温度场检测技术的声学原理和通过测量声波传感器间的声波传播时间 ,然后利用最小二乘原理重建温度场的测量方法 ,并进行了炉膛截面二维温度场重建仿真。对声学烟温测量方法在锅炉烟温测量中的应用及存在的问题进行了分析和讨论。     

水雾遮蔽表面辐射测温问题的实验研究

在工业生产条件下,高温表面辐射测温方法的准确性常常受到参与性介质的影响.以连铸二冷区铸坯表面测温问题为背景,建立了一套水雾遮蔽表面辐射测温系统,进行了水雾对Raytek MRIS-B 单色/双色红外辐射测温仪测温影响的研究.不同温度水平下的测温实验表明,由于水雾介质的衰减作用,单色辐射测温仪的测量值比被测表面真实温度偏低,出现了负偏差,比色辐射测温仪的测量值比被测表面的真实值偏高,出现了正偏差;随着被测表面温度的升高,水雾对两种辐射测温仪的影响增大,测温仪的测量偏差增大;当被测表面温度一定时,水雾粒子数密度增大,由水雾引起的测量偏差增大.研究结果可为开发工业生产条件下在线辐射测温技术奠定基础,也可为工业生产过程中测温仪的选取提供理论依据.     

Influence of Participating Media on the Radiation Thermometry for Surface Temperature Measurement

A temperature measurement model of radiation thermometry for the surface covered by participating media was developed. The model was based on the radiation heat transfer of participating media and principles of radiation pyrometers, and solved by integral formulation of discrete ordinate method on spectral waveband. The influence of water mist on the indicated temperature of Raytek MR1SB one/two color pyrometer was discussed. Mie theory was used to calculate the radiative properties of water mist. In order to verify the model, a laboratory temperature measurement experiment was executed. The result shows that temperature of radiation thermometry is sensitive to the spectral response wavelength of pyrometer, and the simulated temperature of pyrometer agrees well with the experimental measurements on a suitable wavelength. The simulated temperature was lower than the real temperature of surface for one-color pyrometer, and it could be higher or lower than the real one for two-color pyrometer with the influence of participating media.     

On the deduction of single coal particle combustion temperature from three-color optical pyrometry

Temperature–time histories of burning single coal particles can be obtained with multi-color (multi-wavelength) optical pyrometry. With this method, a number of different temperatures can be deduced from the resulting number of two-color ratios. However, these two-color temperatures do not always agree, causing considerable uncertainty in the temperature measurement. This work used a three-color pyrometer and focused on identifying and minimizing the causes of disparity among the three deduced temperatures. Components of the pyrometer (such as dichroic filters, interference filters and photo-detectors) were modeled mathematically, taking into account their wavelength-dependent properties. The pyrometer was calibrated with both a high-temperature pre-calibrated tungsten lamp, and a moderately-high temperature blackbody cavity, to span the temperature range of interest in pulverized coal combustion. Temperatures were deduced based not only on a suitably-modified pyrometric signal ratio method but also, on a similarly modified pyrometric signal non-linear least-square method, to provide comparison. Results are exemplified by presenting radiation-signal-time and temperature–time profiles of single particles burning in air. The variation of the projected luminous area of burning particles was also computed using both methods, and area–time profiles are presented herein. The char particle emissivity was either treated as a quantity independent of the wavelength (i.e., assuming gray-body behavior), or as a quantity assumed to depend linearly on the wavelength and using pertinent published emissivity data. Finally, a sensitivity analysis was performed to investigate individual effects of parameters, such as the calibration method, the wavelength dependencies of filter transmissivities, and the photo-detector responsivities on the pyrometric signal ratio method temperature consistency.     

An improved two-colour pyrometer based method for measuring dynamic temperature mapping of hydrogen-air combustion

To solve the problem of measuring the combustion temperature of hydrogen gas, an improved two-colour pyrometer with suspended tungsten powder was developed and calibrated by a tungsten halogen lamp. The characteristic temperature parameters of the premixed 30% H₂/70% air flame, including temperature distribution, proportion, maximum value, minimum value, and average value, could be measured and calculated using the improved two-colour pyrometer method and a python code. The temperature measuring results of H₂-air mixture obtained by this technique were compared with that of thermocouples and previous studies. The results verified its feasibility to measure the flame temperature structure of H₂ combustion. Future work concerning the influential factors of the improved two-colour pyrometer was also mentioned.     

生物质成型燃料双层炉排锅炉温度场试验研究

生物质能是极具开发潜力的可再生能源。生物质直接燃烧技术的深入研究及锅炉技术的成熟和锅炉类型的多样化为更好开发生物质能源创造了条件。生物质成型燃料与原生物质及煤相比燃烧性质有较大差别,依据该燃料的特点采用双层炉排层燃锅炉。根据有限元分割成型原理布置测点,用热电偶温度计和红外测温仪测出各点温度,得出各个方向温度分布图,并对其进行分析比较,为水冷壁的合理布置、进风量选择及锅炉稳定燃烧、经济燃烧提供理论依据。     

Digital pyrometry in a solar furnace

The brightness temperature and emissivity measurements of an irradiated specimen at the focal point of a solar furnace have been performed by the use of a brightness pyrometer to which an electrical recorder, an oscilloscope and Polaroid camera were attached previously. The use of such a photographic method gave reading errors as ±2K at 3000°C and ±15K at 2000°C.

Therefore, a digital computer system has been coupled with the brightness pyrometer in order to give the higher accuracy in brightness and true temperature measurements and to process a large amount of data. The system consists of A/D converter, central processing unit, graphic display and other transfer units. After an analog signal from the brightness pyrometer was amplified by a dc amplifier, the signal converted into digital form was operated by the digital computer. Conversion errors in the data processing were found to be ±1K at 3000°C and ±7K at 2000°C respectively. The freezing point data by the new system on refractory oxides such as ZrO₂ and Y₂O₃ were presented.     

预测柴油机排气消声器消声量试验方法研究

采用白噪声信号作为标准声源的输入信号，在常温无气流条件下对消声器实物模型进行了静态放声试验。使用消声器倍频程消声量的测量结果，并应用相似准则，推算出消声器在高温条件下各频带的消声量，从而计算出消声器的总消声量。将此方法应用于某一型号船用高速柴油机排气消声器，将通过放声试验推算的结果与实际配机试验的倍频程数据进行对比分析，结果表明该方法用于预测消声器消声量是可行的。