【作者】 汤达斌；

【导师】 冯勇建；

【作者基本信息】 厦门大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 注蒸汽采油是开采稠油的重要手段。隔热油管的真空度影响其隔热性能,从而影响注蒸汽采油的开采效果,因此,如何测试油管真空度是注蒸汽采油的重要研究方向。本项目以电容式微型真空传感器为测试单元,借助PZT压电晶体模块在其共振频率下的逆压电效应,结合PIC16F876A单片机及相关外围信号处理电路,从而测试隔热油管的真空度。就此,本文主要开展了以下研究工作:1.对影响油管隔热性能的导热、对流、辐射等因素进行分析,确定对流是影响散热的主要因素、真空度是油管隔热性能高低的主要指标。根据油管结构的封闭特性,设计整体测试方案。2.针对电容式微型真空传感器测得的电容值比寄生旁路电容小几个数量级的情况,采用由前置电容放大器、相关双采样技术和增量调制器等组成的电容/电压转换器作为电容测试电路,增加补偿电容以消除寄生电容的影响,采用相关双采样电路和增量调制器抑制低频噪声与高频噪声,实现从电容到电压的转换。3.在隔热油管内部,利用PIC16F876A对由电容测试电路测试的信号进行采集分析,通过PZT压电薄膜晶体在其共振频率下的逆压电效应,实现与外界的USART通信。4.PZT压电薄膜晶体本身的原理及结构具有缺陷,经由其产生的脉冲信号会产生失真及干扰,设计出对PZT压电薄膜晶体输出信号进行处理的信号处理电路,解决了信号的失真与干扰问题。5.测试系统要求体积小,功耗低。在软件上对系统MCU工作模式、I/O端口进行分析设置,在硬件上对系统工作电源、时钟频率进行分析设置,结合Dickson电荷泵,设计测试系统的单电池电源供电系统,实现了小体积与低功耗。6.根据滑动平均及最小二乘法理论,用MATLAB对由后期信号处理模块得到的信号进行采集与分析,解决了在高速率测试下保持信号完整性与去除信号干扰的矛盾。根据现有的文献检索,国外在隔热油管真空测试领域的研究有了一定的进展,但这些方法有的成本高,有的难实现,有的只能定性测量,不能定量测量。在国内,相关研究报道较少。因此,本课题的研究具有一定的现实及理论意义。更多还原

【Abstract】 Steam process oil extraction was the vital method of thick oil exploitation. The vacuum level of insulated tubing affected heat insulation capability, and then affected the exploit effect of steam process oil extraction. Therefore, how to test the vacuum level of oil pipeline is the important research direction of steam process oil extraction. In the project, we used capacity vacuum micro sensor as test cell, adopted PZT piezoelectric crystal converse piezoelectric effect on its resonant frequency, and combined PIC16F876A with some related signal processing circuit. Thus measured the vacuum level of insulated tubing successfully. This dissertation launches the following research:1、Analyzed factors that affect the oil pipeline’s heat insulation capability, such as heat conduction、convection current and radiation. Confirmed that convection current was the main cause of heat elimination, and that vacuum level was the main performance index of oil pipeline’s heat insulation capability. According to enclosed property of the oil pipeline, the test project. was designed.2、The capacitance that tested by capacitive vacuum micro sensor was smaller than the parasitic capacitance, so a capacitance voltage converter that was composed of preamplifier、correlated double sampling technology and delta modulator was adopted as capacitance test circuit. Another compensatory capacitance was added in this circuit to eliminate the influence of the parasitic capacitance. Correlated double sampling technology and delta modulator were applied to attenuate low-frequency and high-frequency noise, and realized the capacitance-voltage conversion3、Within the insulated tubing, signal that generated from CVC capacitance test circuit was collected and analyzed by PIC16F876A. Through PZT piezoelectric crystal converse piezoelectric effect on its resonant frequency, the system can communicate with outside by USART. 4、The principle and structure of PZT piezoelectric crystal had some defects. The impulse signal that pass through it were distorted and interfered. So a signal process circuit that can process the output signal generated by PZT piezoelectric crystal was designed, and it solved the signal distortion and interference.5、The test system required small bulk and low power consumption. In software, MCU system work mode and I/O port were analyzed and set. In hardware, system power and clock frequency were analyzed and set. A power system based on monocell and Dickson charge pump was designed, and it reduced system bulk and system power consumption.6、The signal from the after-signal processing circuit by MATLAB was collected and analyzed according to moving average and least squares theory, the contradiction between the maintenance of signal integrity and the removal of signal interference under high-speed test was solved.According to the existing literature, there were some progresses about the study of insulated tubing vacuum test on abroad. some of those methods cost, and some difficult to achieve, some only qualitative measurement, not quantitative measurement. There were few related research reports at home. Therefore, there is certain practical and theoretical significance about the issue.更多还原