Temperature Visiualization And Radiation Parameters Reconstruction Research In Industrial Boiler

As the pivotal heating equipment, industrial furnace was widely used in domestic industrial economy, which was also high energy consumption. The problem of how to improve energy utilization became the top priority of the research of industrial furnaces. Real-time temperature measurement is the premises for optimal combustion of furnace. Improving the temperature detection skill and achieving uniform temperature distribution maybe helpful to safe and optimize operation of industrial furnace.The difficulty of temperature measurement of industrial furnace lies in the large size of the furnace and the strong pulse of the burning flame, which make it difficult to detection the three-dimensional temperature distribution by commonly used thermocouples, pyrometers, acoustic method, and laser-based method. Radiation image processing combined with radiative inverse solving has been proved to be effect for temperature visualization, which has been applied in the power plant boiler. But different from the boiler, the wall temperature of industrial furnace is high, and the wall radiation can not be ignored, which makes the radiation process in the furnace more complicated. Meanwhile, the wide range of industrial furnaces, the variable of fuel type, the more complex of combustion process and the intermediate products of combustion, would make the radiation parameters more difficult to grasp. Therefore, this article will concentrate on how the use the flame image processing and radiative inverse solving to realize the three-dimensional temperature visualization in industrial furnace. Specifically as follows:Firstly, we researched the impact of high wall temperature on radiation imaging process in the industrial furnace, originated from the difference of the furnace and boiler. By using the DRESOR method to solve the radiative transfer equation, we obtained the transitive relation between combustion temperature and flame images, and established a single wavelength radiation imaging model for industrial furnaces.Flame radiation parameter is the prerequisite input for temperature measurement by inverse radiative transfer method. In order to decouple the temperature and radiation parameters, this paper presents a new simultaneously reconstruction method which combined by regularization method and optimization method. Firstly, the flame monochromatic radiation intensity under two wavelengths corresponding to red and green color were get by CCD cameras which were installed on the boundary of furnace, then red monochromatic intensity was used to reconstruct the temperature distribution by regularization method, while the green monochromatic intensity was used fo the optimization target to rebuild radiation parameters. Simulation showed that the reconstruction algorithms were able to reconstruct the furnace temperature distribution and radiation parameters under different measurement errors.Further, experimental study of simultaneous reconstruction of temperature and radiation parameters were carried out on a hot experimental furnace by using CCD detectors and the corresponding computer image acquisition and processing system, which verified the feasibility of the reconstruction algorithm. Further tests of real-time temperature detection were carried out in the hot experimental furnace. Comparision of three measurement points between thermocouples and visualization system showed that, the measurement error in the whole process was less than 5% and the duct surface temperature measurement error was no more than 20℃.The simultaneous reconstruction algorithm was very time consuming, which could not meet the needs of real-time temperature measurement in the furnace. This paper presented a new algorithm for fast temperature reconstruction-Improved colorimetry method. In ths method, the traditional colorimetric method was extended from single-point temperature calculation to solve the multi-dimensional, non-uniform temperature reconstruction. At the same time, the improved colorimetry method could reduce the influence of inaccuracy of radiation parameters, which could obtain a more accurate temperature reconstruction result than monochromatic method.At last, three-dimensional temperature visualization of furnace was researched on a walking beaming reheating furnace. A monitoring system was established by installing two CCD cameras on north and south walls of every four sections. The convergent values of simultaneous reconstruction algorithm were set as the approximate radiation parameters distribution in the furnace, and then the three dimensional temperature were visiualized by improved colorimetric method. Compared with thermocouples, the visiualization system could deduct the three-dimensional temperature in the walking beam reheating furnace in real time and accurately, which could also give the asymmetric heating information of furnace and the slab surface. Meanwhile, online monitoring of billet heating was realized by communicating with the on-site computer control system.In summary, the three-dimensional temperature visualization and deduction of radiation properties of media and high-temperature wall in industrial furnace was realized by the combination method of flame image processing and radiation inverse solving. Further research of this technology would improve the workpiece heating quality in industrial furnace, reduce the fuel consumption and pollution emissions, and finally, achieve the safe and economic operation of industrial furnaces.