Smart Orifice Flowmeter Design And Research

Orifice plate flowmeter was an instrument which could be used to calculate current capacity according to the differential pressure of orifice plate installed in pipeline, the given liquid parameters and orifice geometry size. At present it was widely applied to measure the flux of gas, liquid and steam. Traditional orifice plate flowmeter had some demerits such as low measuring precision and high power dissipation. But the development tendency of flowmeter was high-precision, low power-dissipation, numeralization, integration, intellectualization and networking. Based on the extremely low power dissipation 16-bit MCU produced in Texas Instruments Incorporated, the orifice plate flowmeter was designed in this thesis. Related software and hardware work were completed to realize the basic function.In the literature summary, the conception and classification of flowmeter, the merits, demerits and application scope of various flowmeter were firstly introduced, then the structural style and development tendency of intelligent flowmeter especially the orifice plate flowmeter were analyzed. Then, its measurement principle and theoretical formula, as well as the structural style and technical requirements of standard orifice were expounded. As the core of this thesis, the hardware and software design of flowmeter, the application and programming of peripheral module, the analysis and manipulation of timing of serial bus such as SPI, I C, the concept of low power-dissipation in program design and the countermeasure to enhance stability of program were emphatically discussed in the thesis.The design principle of intelligent orifice plate flowmeter was intelligence, low power-dissipation and low cost. On the choices of hardware, SDPS3 monocrystalline silicon differential pressure sensor produced in German SENSE Corporation was chosen as the sensor. MSP430F149 MCU was chosen as the micro-control chip. 24-bit analog-to-digital converter, 16-bit digital-to-analog converter, ferroelectric memory with calendar and clock, low power-dissipation liquid crystal display etc. were chosen as other peripheral components. About the software, on the principle of low power-dissipation, clock source was rationally distributed. The essential establishment and the corresponding module initialization were completed in master routine. The main function of the system such as sampling of differential pressure signals, computing flux and renovating LCD display and so on were completed in the Interrupt program of TimerA. The system was mostly in the LPM3 low power-dissipation pattern Therefore, the power-dissipation was reduced which could extend the lifetime of the battery The algorithm of flowmete operation was studied in the thesis. Double-precision floating number operation was adopted in calculating flowmete and the hardware multiplier embedded in MSP430F149 was used in the program which enhanced the operation precision and speed.