【作者】 张辉；

【导师】 李忠正；

【作者基本信息】 南京林业大学 ， 制浆造纸工程， 2008， 博士

【摘要】 在打浆和高得率制浆中广泛采用的盘式磨浆机,其磨浆间隙的测量与控制一直是国内外磨浆设备的关键技术之一。然而,国内外目前采用主电机总电流即磨浆功率控制手段,实际受浆流量、浓度、杂物及盘齿磨损等因素影响使磨浆间隙测量间接且不准确,故磨浆间隙的精确、在线实时测量技术始终未获突破。它对提高磨浆纤维质量以及设备安全运行等意义重大。本文首先在研究分析出解决盘间磨浆间隙精确、在线实时测量技术需满足的关键条件;并研究筛选出可满足的传感器测量技术;进一步研究了所选择的传感器测量旋转齿盘类金属构件表面位移物理量的基本理论、方法和其输入与输出特性;研究了实际盘式磨浆机上磨浆间隙在线实时测量的安装的理论、技术与方法,各种工况下的传感器输入与输出特性;最后,研究和设计了磨浆间隙信号采集与处理过程中的标度变换与算法流程、基本程序等。本文主要获得以下成果:1、较适合于盘式磨浆机运行工况及具有磨盘磨片特征的旋转齿盘形金属构件表面位移量直接、精确测量的传感器为电涡流位移传感器。2、电涡流传感器探头引起齿盘形金属表面电涡流分布为:盘齿部分电涡流环域分布为畸形圆闭环流的组合,边界附近密度很高;齿体部分电涡流同样是以探头线圈轴为轴心对称,但分割开各自形成非圆形、边缘畸变的独立闭环流;齿槽底面以下部分,电涡流环域分布为一以探头线圈轴为轴心的整体同心圆。有效测量齿盘形金属表面微位移时,探头所覆盖齿盘面区域的电涡流特性保持固定。3、直径Φ11 mm电涡流传感器探头测量齿盘形金属表面静态或动态旋转时,与平面金属导体的电压—位移(U-X)特性曲线整体变化趋势完全一样;在X接近于0距离时输出值U“突变提升”要比平面盘提前。齿盘形金属表面变转速状态下,转速<760rpm(相当于线速172m/min)时,U在<±0.04v内波动;而当转速>760rpm时,U值稳定,且转速越高、示值越平稳;在0.60～7.20mm齿盘位移间隙测控范围内,传感器静、动态试验数据进行最佳特性曲线线性回归相关系数都大于0.999,各齿盘试件的特性曲线斜率基本相同。4、在测量齿盘形金属表面边界区位移量时,电涡流传感器输出特性存在边缘影响效应,其影响范围为探头径向端面与齿盘形金属表面边缘距离e<3mm。5、电涡流传感器探头直接且精确的实时测量盘式磨浆机磨浆间隙时,不受磨浆浆种、浓度和流量的影响;在动、定磨盘处于无浆静态、无浆动态以及有浆动态三种工况下,电涡流传感器的位移电压输入输出特性基本一致,线性好,且退盘与进盘时重现性好。6、盘式磨浆机磨浆盘间隙动态监测引起磨浆间隙变化的共有“阶段性开机前的间隙调零和取得初始间隙,启动旋转运行,进、退盘操作,停机”四种操作状态。对应于四种操作状态具有相应的间隙算法和算法程序转换流程。本课题研究,在国内外首次进行了电涡流传感器用于旋转齿盘形金属面位移测量的理论与输入、输出特性研究,并为电涡流传感器开劈了新的非接触测量位移的用途;提出了盘式磨浆机高速旋转齿盘的动态非接触式测量位移的理论与方法,以及直接、实时、精确测量与调节控制磨浆间隙的技术原理和具体实施方法,为使理论研究的磨浆工艺在磨浆机上精确实施和提高磨浆工艺技术控制水平奠定了理论基础,具有广阔的应用前景。更多还原

【Abstract】 To measure, control and adjust the refining gap of disc refiner used widely for beating and high-yield pulping has been being one of the key technologies of disc refiner. The present technology in the world is based on keeping stable electric current value, that is, the refining power of disc refiner’s host motor. In practice, the electric current value of disc refiner’s host motor is influenced by the mobility of pulp flux and consistence and by impurity in pulp, and the scale value of the vernier doesn’t contain the wearing gap between rotating tooth-disc and stable tooth-disc when disc’s running. Therefore, the present technology has not made the Direct, Online and Precise Measurement of Refining Gap (DOPMRG) of disk refiner come true. DOPMRG is much necessary for improving the pulp-refining quality and ensuring the disc refiner to run safely.In the paper, firstly, the key technical demands to realize DOPMRG were brought forward. Secondly, the transducer satisfied with DOPMRG was screened out. Thirdly, the displacement-measuring theory, method, and in-and-out characteristic of the transducer screened out above were discussed when used for measuring the displacement of the rotating tooth-like metallic disk. Then, the condition, theory, technology and method about installing transducer on the disc refiner’s stable disc, as well as the in and out characteristic of the transducer working under the different conditions of practical pulp refining, were researched and evaluated respectively. Finally, the calibration transform and program-converting flow of plate-gap arithmetic , as well as the basic program on computer, were studied showing.The main conclusions obtained in the paper are as follows:1. The eddy current sensor is best fit for measuring directly and accurately the displacement of the rotating tooth-like metallic disk with the conditions the disc refiner works under, and with the shape of the tooth-disc of disc refiner.2. The eddy current distribution on tooth-like metallic disk are: that there is a series of compound, abnormal, and closed circumfluent eddy current distribution in the tooth part, and that there is thicker circumfluent eddy current distribution around the edge area of tooth; but, that, in non-tooth (plane) part (below the underside of the alveolus), there is circumfluent eddy current distribution which is a series of circularity with one heart of the axes of the probe loop. If eddy current sensor is used for effectively measuring the surface displacement of tooth-like metallic disk, its probe should always cover with the same characteristic of sum of tooth and alveolus area, so as to bring about the stable eddy current characteristic.3. When the probe of eddy current sensor (Φ11 mm) measured the stable and rotating metallic tooth disc, the Sensor’s Voltage (U)-Displacement (X) Response Curve (SVDRC (U-X)) showed the same changing rend as that obtained when it measured the metallic plane disc. When X was the same and closed to zero, the out-voltage U of sensor for the metallic tooth disc showed stepping up earlier than that of sensor for metallic plane disc. SVDRCs (U-X) of different metallic tooth discs with different tooth size were very closed.When the metallic tooth disc rotated at the speed of less than 760rpm (corresponding to the line speed of 172m/min), the value of U of SVDRC (U-X) waved in the range of±0.04v; while the value of U was steady when tooth disc’s rotating speed was more than 760rpm, and the more the rotating speed, the steadier the value of U.With displacement of 0.6~7.20mm, obtained were the optimized linearity regression equations’parameters of in-and-out characteristic data of eddy current sensor of 9 testing tooth discs for captive and dynamic tests. The correlation coefficients of the 9 linearity regression response curves were all more than 0.999, and slops of the 9 linearity regression response curves were almost the same.4. There was non-linear edge effect of in-and-out characteristic of eddy current sensor when it measured the displacement of the border area of tooth-like metallic disc. The border area with non-linear edge effect was e<3mm (e represented the distance between the probe’s radial end and the border of tooth-like metallic disc).5. When the probe of eddy current sensor was used for DOPMRG of disk refiner, the in-and-out characteristic of eddy current sensor did not be influenced by kinds, consistence, flux of the pulp refined. And when the stable and rotating discs worked respectively under three working conditions of stopping state without pulp, rotating state without pulp, and rotating state with pulp, the in-and-out specialities of eddy current sensor were almost consistent, and recurred very well when the stable disc advanced and fell back.6. There are four operating states for the refining disc: zeroing and obtaining initial gap, starting and running, advancing and falling back, and pausing. During the calibration transform as well as on-line acquisition and processing of the signal exported by the transducer measuring the refining gap of the disc refiner, the plate gap arithmetic and program-converting flows of four operating states are different.The paper did, for the first time in the world, open out the displacement measuring theory, method, and in-and-out characteristic of eddy current sensor when it was used for measuring the displacement of the rotating tooth-like metallic disk, which provided eddy current sensor with a new application of non-contact displacement measurement. The paper, also, indicated the theory, basic technical principle and method of DOPMRG of disk refiner, which settled the important base for guaranteeing pulp refining technic parameters to be put in practice on refiner and for enhancing the pulp refining technic controlling level. The paper’s application will have great foreground and be spread fast.更多还原