US 5,234,601 AGranted

Apparatus and method for controlling regeneration of a water treatment system

AssigneeAutotrol Corporation

InventorsDonald R. Janke, Frank Kunesh, Michael G. Busby

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Abstract

A water treatment apparatus has a tank that contains a resin bed through which water flows. The apparatus is controlled by occasionally measuring the conductivity of the resin bed at two spaced apart locations to produce first and second conductivity measurements. The ratio of the two conductivity measurements is calculated periodically. The present ratio value, along with the minimum and maximum ratio values that occurred since a previous regeneration of the resin bed, are used to determine the movement of an exhaustion front through the resin bed. A probability of exhaustion also is determined and when that probability exceeds a given value, regeneration of the resin bed is initiated. The conductivity measurements are used to determine if the resin bed has lost efficiency and in which event a warning signal is sent to the user. During regeneration, the conductivity at one of the locations in the resin bed is monitored to detect whether a regenerant has entered the tank; if not another warning signal is sent to the user.

Claims24

Dependent claims

A water treatment system comprising:

a tank having an inlet and an outlet, and containing a particle bed;
first and second sensors located at two locations in the particle bed to sense electrical conductivity at each location;
means, connected to said sensors, for deriving a ratio value representing a ratio of electrical conductivities sensed at the two locations;
a source of first and second threshold values;
a first means for determining whether the ratio value received from said means for deriving is less than all previous ratio values produced since a given point in time, to identify a minimum ratio value designated RATIO.sub.min ;
a first means, responsive to said first means for determining and said means for deriving, for producing a first probability by dividing the ratio value by RATIO.sub.min ;
a first comparator, coupled to said source and said first means for producing, to generate an indication when the first probability becomes greater than the first threshold value;
a second means, responsive to the indication from said first comparator, for determining whether the ratio value received from said means for deriving is greater than all previous ratio values occurring after the indication was generated, to identify a maximum ratio value designated RATIO.sub.max ;
a second means, responsive to said second means for determining and said means for deriving, for producing a second probability by dividing the ratio value by RATIO.sub.max ;
a second comparator, coupled to said source and said second means for producing, to detect when the second probability becomes less than the second threshold value;
and
a mechanism, coupled to said first and second comparators, to regenerate the particle bed of the water treatment system in response to the first probability becoming greater than the first threshold value followed by the second probability becoming less than the second threshold value.

9 more elements

A water treatment system comprising:

a tank having an inlet and an outlet, and containing a particle bed;
first and second pairs of electrodes with each pair being placed at a different height in the particle bed;
a signal generator having an output at which is produced an alternating signal having a given frequency, and having a conductor connecting the output to one electrode of each of said first and second pairs of electrodes;
means, connected to the other electrode of each of said first and second pairs of electrodes, for producing a ratio value corresponding to a ratio of a signal S1 produced from said first pair of electrodes and a signal S2 produced from said second pair of electrodes;
a first means for determining whether the ratio value received from said means for producing is less than all previous ratio values produced since a given point in time to identify a minimum ratio value designated RATIO.sub.MIN ;
an analyzer, coupled to said means for producing and to said first means for determining, to compare the result of dividing ratio values by RATIO.sub.min to a first threshold and to generate an indication when the first threshold is exceeded by the ratio value;
a second means, responsive to the indication from said comparator, for determining whether the ratio value received from said means for producing is greater than all previous ratio values produced, after the indication was generated, to identify a maximum ratio value designated RATIO.sub.max ;
a calculator, coupled to said means for producing and to said first and second means for calculating a probability P according to the expression:
##EQU5## where n is a non-zero constant;
a control means, coupled to said calculator, for comparing the probability to a second threshold and producing a regeneration control signal when the probability is below the second threshold;
and
a mechanism connected to said control means to regenerate the particle bed in response to the regeneration control signal.

9 more elements

Dependencies are inferred from the claim text.