电容层析成像技术在线测量气固流化床空隙率的研究

Study on Voidage Measurement of Gas-solid Fluidized Bed by Using Electrical Capacitance Tomography

基于电容层析成像技术,提出了一种在线测量气固流化床空隙率的新方法。建立了相应的12电极电容层析成像气固流化床空隙率测量系统,可同时实现气固流化床空隙率分布的在线显示和整体空隙率测量。选择加权反投影算法进行图像重建以保证空隙率分布显示的实时性和有效性。采用Tikhonov正则化原理和ART算法相结合的组合型新图像重建算法来实现整体空隙率的测量。Tikhonov正则化原理用于克服图像重建过程中的不适定问题,ART算法用于提高最终重建图像的质量。研究表明以上提出的空隙率测量新方法是有效的。空隙率分布在线测量的速度可达25幅/秒以上,整体空隙率测量的最大误差可小于5%。

Based on electrical capacitance tomography technique, a new method for the on-line voidage measurement of gas-solid fluidized bed was proposed. A 12-electrode electrical capacitance tomography measurement system for the voidage measurement of gas-solid fluidized bed was developed. This system can implement voidage distribution display and global voidage measurement of gas-solid fluidized bed simultaneously. The weighted back projection algorithm was selected as the image reconstruction algorithm to satisfy the requirement of voidage distribution display. A new hybrid image reconstruction algorithm which combines Tikhonov regularization theory with ART (Algebraic Reconstruction Techniques) algorithm was presented to implement the global voidage measurement of gas-solid fluidized bed. The use of Tikhonov regularization theory was to solve the ill-posed problem of image reconstruction and the use of ART algorithm was to improve the quality of the final reconstructed image. Study results showed that the proposed new voidage measurement method is successful. The speed of image reconstruction of voidage distribution display is greater than 25 frames per second and the maximum error of global voidage measurement is less than 5%.