摘要
在原油生产过程中,从油井中开采出来的原油是含有一定水分的,由于油和水的比重不同,原油中的水分会沉降在油罐底部,需输送到分离灌中进行油水分离,处理成低含水率的成品原油。因此,油水界面检测是实现储油罐水位自动控制的重要环节。原油储罐内油水界面的实时及准确测量是成功分离出原油的重要保障,也是储运系统管理和计算原油储量的主要依据。
该文在详细研究国内外油水界面检测理论与技术的基础上,根据油水介电常数不同的原理,采用分段式电容传感器,设计了一款新颖先进的油水界面智能监测仪。文中详细论述了油水界面的检测原理和整个系统的构成,并论述了系统的硬件设计和软件设计。该监测仪的重要特色是该油水界面监测仪中设置了串行通信模块,具有两种工作模式。该油水界面监测仪可以单机工作,又可以作为一个下位机,构成基于RS-485总线的远程计算机监控系统。
油水界面的测量是该油水界面智能监测仪的关键性技术,分段式电容传感器的原理就是将一根全量程长度的圆筒形传感电容进行分段处理,每一段对应着固定的长度,用现代微电子技术手段,逐段测量每段的电容值,如果所测的电容值既不是纯油对应的电容值,也不是水对应的电容值,从而便可确定储油罐内的油水界面。
该监测仪采用分段式电容传感器通过在线检测介质(油和水)介电常数的方法,把储油罐内油水界面的动态变化转换为电信号的变化,并对不同层面液体的电容进行扫描检测,且将检测结果转换成数字量送到单片机进行处理,从而达到对储油罐内油水界面实时监控与调理之目的。
整个系统的硬件设计和软件设计都采用模块化的设计方法,仿真结果表明设计方案达到预期目标。
In the production process of crude oil, the crude oil exploited from the oil well has certain moisture content, because the specific gravity of oil and water is different, the water in the crude oil will subside the base of oil tank, must be separated from the water in separation tank and processed to be low water content oil. Therefore, the detection of oil-water interface is the important link to realize the auto-control of water level in oil tank. The real-time and accurate detection of oil-water interface in oil tank is the important guarantee to successfully separate oil from water, and is also the mainly basis of managing and computing the oil volume.
After the comprehensive study of present theory and technology on oil-water interface examination at home and aboard, according to the principle that the dielectric constant of oil and water is different, we design a kind of oil-water interface intelligent monitoring instrument by sectional type capacitance sensor. This paper discusses the examination principles of oil-water interface and its systemic structure in detail, and both the hardware and software design for the whole system. The monitoring instrument is characteristic of its serial communication module and two kinds of working patterns. The monitoring instrument not only can work solely, but also can constitute the computer supervisory system based on the RS-485 bus as a slave.
The detection of oil-water interface is the crucial technology of the monitoring instrument, the principle of sectional type capacitance sensor is that an entire measuring range length columnar capacitance sensor is separated into subsections, each section has the fixed length, measures each section with modern microelectronics technology, if the capacitance value detected is neither the corresponding value of pure oil nor the corresponding value of water, thus the oil-water interface in oil tank will be fixed on.
The monitoring instrument transforms the dynamic change of oil-water interface in oil tank into the change of electric signals through the method that the dielectric constant of medium(oil and water) real-time detected by the sectional type capacitance sensor, and detects the corresponding capacitance of the different layers liquid, then transforms the result detected into the digital signal processed by the MCU, thus achieve the intention of oil-water interface real-time monitoring and adjusting in oil tank.
Both the whole system's hardware and software design use the modular design method, the simulation result proves the design up to the desired goal.
引文
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