原油降粘的超声波电源系统研制

发布时间：2018-05-16 05:39

本文选题：原油降粘 + 超声波电源　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：我国境内开采的原油多为高凝点的石蜡基原油,随着运输过程中温度逐渐降低,原油中石蜡不断析出,原油粘度升高,流动性变差,在输油管壁形成结蜡现象,对运输效率造成了不良影响。超声波降粘技术可破坏石蜡晶体结构,原油降粘效果良好且不产生多余杂质。超声波电源是超声波降粘系统的重要组成部分,其性能对原油降粘效果至关重要。本文对超声波电源在原油降粘应用中的工作方式进行分析,研制可以应用于原油降粘的超声波电源。本文首先根据超声波原油降粘工况,并对原油降粘用换能器进行阻抗特性分析,明确超声波电源的技术指标并提出总体设计方案。以IGBT为功率元件、采用全桥逆变电路实现输出驱动换能器的高频交流电,其中逆变电路所需的直流电由不可控整流滤波电路输出;为了抑制逆变电路中IGBT关断时各极之间产生的浪涌电压,在各极之间并联瞬态电压抑制二极管防止IGBT被击穿。对IGBT的驱动要求进行探讨,设计具有隔离功能的驱动电路,使用迟滞比较器构成过流保护电路。以STM32F407为主控芯片设计超声波电源的控制系统,采用输出互补PWM信号模式驱动全桥逆变电路,并利用旋转编码器实现PWM信号的频率和占空比调节,由此实现对超声波电源的频率和功率的调节,以适应原油降粘过程中换能器因负载阻抗变化而导致的频率漂移。换能器在谐振频率下工作时的等效负载是容性,利用交流电直接驱动将产生大量无用功,导致换能器的热损,影响换能器的工作寿命。建立换能器的等效电路模型,根据阻抗分析结果设计调谐匹配电路,在仿真平台Saber中建立超声波电源模型,进行调谐匹配仿真分析。针对换能器在原油降粘过程中的匹配失谐现象,研制可调匹配电感,实现电感的无级连续调节。此外,根据阻抗匹配原理,对高频变压器进行详细设计。最后,本文对超声波电源进行测试,在示波器上得到电源各环节的输出波形,对比串联调谐匹配和LC型匹配网络,测试结果表明LC型匹配的调谐效果更佳且具有滤波功能。使用本文研制的超声波电源驱动换能器进行原油降粘实验,对比分析超声波处理前后的原油粘度,发现超声波能够有效降低原油粘度。
[Abstract]:Most of the crude oil mined in China is paraffin based crude oil with high condensate point. With the temperature gradually decreasing during transportation, paraffin wax in crude oil continuously precipitates, the viscosity of crude oil increases, the fluidity becomes poor, and wax deposit is formed on the oil pipeline wall. It has a negative impact on transport efficiency. Ultrasonic viscosity reduction technology can destroy the crystal structure of paraffin, and the viscosity reduction effect of crude oil is good and no excess impurities are produced. Ultrasonic power supply is an important part of ultrasonic viscosity reducing system, and its performance is very important to the viscosity reduction effect of crude oil. In this paper, the working mode of ultrasonic power supply in the application of oil viscosity reduction is analyzed, and the ultrasonic power source which can be used in crude oil viscosity reduction is developed. In this paper, according to the condition of ultrasonic oil viscosity reduction, the impedance characteristic of the transducer for oil viscosity reduction is analyzed, and the technical specifications of ultrasonic power supply are defined and the overall design scheme is put forward. Using IGBT as power element, the output drive converter is realized by full-bridge inverter circuit, in which the DC of inverter circuit is output by uncontrollable rectifier filter circuit. In order to suppress the surge voltage between the poles when IGBT is turned off in the inverter circuit, the transient voltage suppression diodes are paralleled between the poles to prevent the IGBT from being broken down. The driving requirements of IGBT are discussed, the drive circuit with isolation function is designed, and the over-current protection circuit is constructed by using hysteresis comparator. The control system of ultrasonic power supply is designed with STM32F407 as the main control chip. The full-bridge inverter circuit is driven by output complementary PWM signal mode, and the frequency and duty cycle of PWM signal are adjusted by rotary encoder. Thus, the frequency and power of ultrasonic power supply can be adjusted to adapt to the frequency drift caused by load impedance change in the process of oil viscosity reduction. The equivalent load of the transducer working at the resonant frequency is capacitive. The direct drive of AC will produce a lot of useless power, which will lead to the heat loss of the transducer and affect the working life of the transducer. The equivalent circuit model of the transducer is established, and the tuning matching circuit is designed according to the results of impedance analysis. The ultrasonic power supply model is established in the simulation platform Saber, and the tuning matching simulation analysis is carried out. Aiming at the matching detuning of the transducer in the process of viscosity reduction of crude oil, the adjustable matching inductor is developed to realize the stepless and continuous regulation of the inductor. In addition, according to the principle of impedance matching, the high frequency transformer is designed in detail. Finally, the ultrasonic power supply is tested in this paper. The output waveforms of each link of the power supply are obtained on the oscilloscope. Compared with the series tuning matching and the LC matching network, the test results show that the LC matching tuning effect is better and has filtering function. The viscosity reduction experiment of crude oil is carried out by using the transducer driven by ultrasonic power supply developed in this paper. The viscosity of crude oil before and after ultrasonic treatment is compared and analyzed. It is found that ultrasonic wave can effectively reduce the viscosity of crude oil.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE868;TB55

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