Distributed electric contact water level gauge measuring system and control method thereof

Abstract

The invention discloses a distributed electric contact water level gauge measuring system which comprises sampling short cylinders, at least three electrodes, a single-chip microcomputer, a multi-point switch circuit module and an A / D conversion module, wherein the sampling short cylinders are sequentially distributed and communicated with each water level control key point of a measured container; the electrodes are uniformly distributed in each sampling short cylinder; the number of the electrodes is an odd number; wherein the electrodes in the plurality of sampling short cylinders are sequentially distributed at different elevations to form an electrode scale taking electrode points as scales; the electrodes are electrically connected with the single-chip microcomputer sequentially through the multi-point switch circuit module and the A / D conversion module, the multi-point switch circuit module circularly switches the electrodes connected with the electrode scale, measures the resistance to ground of the electrodes, converts the resistance to ground into rectangular square wave voltage signals and transmits the rectangular square wave voltage signals to the A / D conversion module. The A / D conversion module converts the rectangular square wave voltage signal into a digital signal and transmits the digital signal to the single-chip microcomputer; the single-chip microcomputer receives the digital signal of the A / D conversion module and calculates to obtain a sampling water level h. The water levels of multiple key points of the water storage tank can be accurately measured under all working conditions.

Description

technical field [0001] The invention relates to a distributed electric contact water level gauge measurement system for high temperature and high pressure containers such as boilers, in particular to a distributed electric contact water level gauge measurement system and a control method thereof. Background technique [0002] The supercritical power generating unit is the main unit of my country's power grid. The unit is equipped with a supercritical pressure once-through boiler. Water is the circulating working medium. It is pressed into the economizer by the feed water pump. The superheated steam goes to the turbine generator to generate electricity. Before the boiler starts to ignite and boost with load until the pressure rises to the critical pressure, and the unit slip parameters are shut down until the pressure is lower than the critical pressure, the water-cooled wall flows out of the steam-water mixture. like figure 1 As shown, in order to prevent water from enterin...

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Problems solved by technology

my country's supercritical boilers are only equipped with 4 sets of differential pressure water level gauges, and the signal configuration does not conform to the principle of "dangerous dispersion". What's more, the ambient temperature of multiple sets of differential pressure water level gauges is the same, which will inevitably form a "dangerous concentration" of environmental temperature effects, resulting in The 6 signals fail at the same time, and the automatic adjustment and water level shutdown protection fail at the same time, causing a high probability of accidents

[0004] The water level of the water storage tank has a large range, and the section of the water chamber is only 1% of the section of the water chamber at the zero water level of the steam drum. Intense fluctuations, coupled with the relatively poor measurement stability of the differential pressure water level gauge, lead to a very low actual input rate of the water level automatic adjustment system, which will inevitably increase the monitoring intensity of the operating personnel, especially when the steam turbine is running, the generator is connected to the grid, and the load is increased. In the first stage, the water level control and regulation system is subject to a lot of interference and the amount of interference is large. Even experienced personnel will make operational mistakes, resulting in a high shutdown rate due to water level accidents. In addition, the poor stability of the differential pressure measurement value results in frequent shutdown protection actions for high water levels. According to statistics, the failure rate of one startup is as high as 40%. This situation has continued for many years, which not only directly threatens the safety of unit equipment, but also causes considerable direct economic losses.

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