| An accurate measurement of pulverized coal concentration in primary air pipe of boiler plays an important role in safe and economic operation of thermal power plants. Yet for The fluid is very complex gas-solid two-phase flows, the accurate measurement of pulverized coal concentration has always been a problem.Currently measurement methods of pulverized coal concentration have direct methods and the indirect methods, but these measurement methods are inadequate in accuracy, security and economy.This paper presents a new method of measuring the concentration of pulverized coal——Ultrasonic cross-correlation function method, and on the basis of this approach a measuring instrument of pulverized coal concentration is designed and developed.In the paper,the principle of Ultrasonic cross-correlation function method is introduced,according to the measurement principle and the functional needs of specific projects, overall design of the measuring instrument is carried out.The hardware structure consists of measuring ultrasonic sensor drive circuit, ultrasonic sensor receiving circuit, the signal control circuit and signal acquisition and processing system components.For high-speed acquisition and transmission bottleneck problem, a scheme based on FPGA (Field Programmable Gate Array) and ARM (Advanced RISC Machines) combining the DMA (Direct Memory Access) is putted forward, which is easy to modify and upgrade, convenient to debug.Then a concrete hardware design of the measuring instrument was carried out,and control program of the measuring instrument based on the ARM architecture was designed and programmed in integration environment ADS1.2.Finally software and hardware debugging were done,then all parts are fitted to an instrument box, in the laboratory, experiments on the feasibility and reliability of the instrument is done.Experimental results show that the measuring instrument meets the design requirements,and will be very important to improve the efficiency of boilers. |
PDF Full Text Request