Study Of The Boiler Liquid Level Detecting System Based On Phase Laser Rang Finding Technology

Liquid level is one of the most important parameters of measurement and control in manufacturing process. In the process of boiler control system working, liquid level is a very important parameter. So it is important to control the liquid level. The liquid level data must be acquired well and truly, and it is an important precondition of upgrading the management level and realizing intellectualization.This paper begins with the laser ranging. The advantage of the laser range-measuring system is clarified through the compare of several range-measuring manners and the anatomy of the laser range-measuring development trending. And put forward the method of phase-laser measuring to measure the liquid level of boiler on the basis.Firstly, the principle of phase-laser measuring distance and difference frequency measuring phase is introduced in this paper. The structure of the fiber and its ray transmission principle are introduced. By the use of optical fibers to transfer the optically encoded signal, the measurement spot is kept apart from the electronic processing system. The working principle and performance data of several semiconductor laser resource and photoelectric detector are described. And the thesis introduces the basic requirements of Light Source Selection. The method for the detection of weak signal is mainly proposed. The basic principle and structure of the phase-loop are researched in detail.Secondly, the circuit and the optical path of the liquid level detecting system are developed. The light source and its drive circuit are selected and designed with the aim of providing the stimulating signal to the system. The optical signal carrying the liquid level information is transferred to the electrical signal, and signal processing circuit is used. In order to obtain the accurate liquid level signal, high accuracy phase measurement based on the MSP430 single-chip microcomputer is designed in this paper. So the liquid level information can be acquired real-timely and truly, and it realizes the real-time liquid level measurement of boiler.This liquid level measuring system has the merits of wide detecting range, high precision, simple structure and steady.