| 摘要 |
PURPOSE:To control a surface level of brine in a multistage flash desalinator with a high accuracy, by directly measuring a surface level of the brine in an evaporation chamber, and controlling the maximum temperature of the brine to maintain the surface level at a constant level. CONSTITUTION:A multistage flash desalinator is operated, while controlling a desalination amount. A surface level of brine in an evaporation chamber is directly measured, and the measured value LX1 is compared with a reference value S. In case where the deviation of the value LX1 from the reference value S exceeds an allowance, an insensitive zone setting device DB outputs a signal, and a PI controller generates a proportion plus integration control signal. This control signal is carried through a rate limit, a max-min limit and an automatic-mannual switching device HIA, and compared with a signal from a maximum brine temperature gennerator TE. According to this comparison, a valve TCV for controlling heated vapor to heat the brine is opened or closed to make the maximum brine temperature to the reference value. Thus, the surface level of the brine is controlled with a high accuracy. |
