| 摘要 |
This invention relates to a method of controlling a sludge thickening process, in which one or more flocculation agents (F1, F2) and/or coagulants (K) are fed into the incoming sludge (IS) prior to feeding said sludge into a thickener (1) and filtrate (RF) and thickened sludge (FS) is discharged separately from the thickener (1). According to the invention the amount of solid substance (SS content) in the filtrate (RF) is measured with an adjustable frequency, data from the measurement of the amount of solid substance (SS content) in the filtrate is fed to a control unit (2), a feeding unit (3) for providing a metered feed of a flocculant (F1) is connected to the control unit (2), whereby the metering of the flocculant (F1) is sensed, an upper (SSmax) limit value of the amount of solid substance (SS content) in the filtrate is set in the control unit (2), and the measured amount of solid substance is compared to the limit value, and, when exceeding the upper (SSmax) limit value for the measured amount of solid substance (SS content), the control unit (2) increased the feeding of the flocculant (F1) until the measured amount of dry substance falls below the limit value again, an upper limit value (F1max) for the feeding of flocculant (F1) is set in the control unit (2) and is compared with the sensed value, and, when exceeding the upper limit value (F1max) for the feeding of flocculant (F1) the feeding of flocculant (F1) is decreased through the control unit (2) until it falls below the limit value (F1max) for the feeding of flocculant (F1) again and the control unit (2) gives an alarm signal to the operator or alternatively the control unit switches over to feeding another flocculant (F2). |
