ARRANGEMENT AND METHOD FOR CONTROLLING PRESSURE FILTER
Disclosed is an arrangement and method for controlling a pressure filter. The arrangement comprises the pressure filter for solid-liquid separation for producing a filter cake and a moisture analyzer for providing an indication of moisture content of the filter cake. One or more controllers may be used for utilizing the indication of moisture content to set a drying time for the solid-liquid separation.
1 . An arrangement for controlling a pressure filter, the arrangement comprising:
the pressure filter for solid-liquid separation for producing a filter cake;
a moisture analyzer for providing an indication of moisture content of the filter cake;
one or more controllers for utilizing the indication of moisture content to set a drying time for the solid-liquid separation.
2 . The arrangement according to claim 1 , wherein the moisture analyzer comprises a microwave analyzer, a capacitive sensor or a near-infrared sensor.
3 . The arrangement according to claim 1 , arranged for setting the drying time utilizing indications of moisture content provided from more than one solid-liquid separation cycles of the pressure filter.
4 . The arrangement according to claim 1 , wherein the one or more controllers comprise a multivariable controller.
5 . The arrangement according to claim 1 , wherein the one or more controllers comprise a multivariable MPC (model predictive control) controller.
6 . The arrangement according to claim 1 , arranged for additionally utilizing the indication of moisture content to set a pressing amount of the pressure filter.
7 . The arrangement according to claim 1 , comprising one or more weight sensors for providing an indication of the weight of the filter cake.
8 . The arrangement according to claim 1 , wherein the pressure filter comprises one or more load cells for providing an indication of the weight of the filter cake.
9 . The arrangement according to claim 7 , arranged for additionally utilizing the indication of weight to set a feed amount for the pressure filter.
10 . The arrangement according to claim 1 , arranged for simultaneously utilizing the indication of moisture content and an indication of operating capacity of the pressure filter for setting the drying time and, optionally, a feed amount for the pressure filter and/or a pressing amount of the pressure filter.
11 . The arrangement according to claim 1 , wherein the solid-liquid separation comprises a washing phase and the arrangement comprises one or more sensors for providing an indication of quality of the washing phase for setting the drying time and/or a control value for washing the filter cake.
12 . The arrangement according to claim 1 , comprising one or more sensors for providing an indication of pH, electrical conductivity or turbidity of a filtrate produced by the pressure filter for setting the drying time and/or a control value for washing the filter cake.
13 . A method for controlling a pressure filter for solid-liquid separation, the method comprising:
receiving an indication of moisture content of a filter cake produced by the pressure filter for the solid-liquid separation; and
utilizing the indication of the moisture content for setting a drying time for the solid-liquid separation.
14 . The method according to claim 13 , comprising receiving an indication weight of the filter cake; wherein the indication of weight is utilized together with the indication of the moisture content for setting the drying time, a feed amount for the pressure filter and, optionally, a pressing amount of the pressure filter.
15 . A controller configured to cause the method of claim 13 to be carried out.
16 . The arrangement according to claim 8 , arranged for additionally utilizing the indication of weight to set a feed amount for the pressure filter.