Reverse Polarity Cleaning and Electronic Flow Control Systems for Low Intervention Electrolytic Chemical Generators

Abstract

Method and apparatus for a low maintenance, high reliability on-site electrolytic generator incorporating automatic cell monitoring for contaminant film buildup, as well as automatically removing or cleaning the contaminant film. This method and apparatus preferably does not require human intervention to clean. For high current density cells, cleaning is preferably performed by reversing the polarity of the electrodes and applying a lower current density to the electrodes. A second lower current density power supply may be used for reverse polarity cleaning. Electrolyte flow is preferably monitored and automatically adjusted.

1 . A method for cleaning an electrolytic cell comprising electrodes, the method comprising the steps of:
 reversing polarities of two or more of the electrodes; and   providing a cleaning current density to the electrodes which is lower than an operational current density used during normal operation of the electrolytic cell.   
     
     
         2 . The method of  claim 1  wherein during normal operation the electrolytic cell produces a concentration of free available chlorine greater than approximately four grams per liter. 
     
     
         3 . The method of  claim 2  wherein during normal operation the electrolytic cell produces a concentration of free available chlorine greater than approximately five grams per liter. 
     
     
         4 . The method of  claim 3  wherein the concentration of free available chlorine is approximately eight grams per liter. 
     
     
         5 . The method of  claim 1  wherein the operational current density is greater than approximately one amp per square inch. 
     
     
         6 . The method of  claim 1  wherein the cleaning current density is less than approximately 20% of the operational current density. 
     
     
         7 . The method of  claim 6  wherein the cleaning current density is between approximately 10% and approximately 15% of the operational current density. 
     
     
         8 . The method of  claim 1  wherein the providing step is performed for less than approximately thirty minutes. 
     
     
         9 . The method of  claim 8  wherein the providing step is performed for between approximately five minutes and approximately ten minutes. 
     
     
         10 . The method of  claim 1  wherein the reversing step comprises using at least one power supply relay or other switching device. 
     
     
         11 . The method of  claim 1  wherein the operational current density is provided by an operational power supply and the cleaning current density is provided by a separate cleaning power supply. 
     
     
         12 . The method of  claim 11  wherein a power producing capacity of the cleaning power supply is smaller than a power producing capacity of the operational power supply. 
     
     
         13 . The method of  claim 1  further comprising the step of monitoring a flow rate of electrolyte through the electrolytic cell. 
     
     
         14 . The method of  claim 13  wherein the monitoring step is performed using a flowmeter, a rotameter, or a pressure transducer, or monitoring a temperature difference across the electrolytic cell via a first thermocouple or thermowell disposed at an inlet of the electrolytic cell a second thermocouple or thermowell disposed at an outlet of the electrolytic cell. 
     
     
         15 . The method of  claim 13  further comprising the step of automatically adjusting the flow rate. 
     
     
         16 . The method of  claim 13  further comprising the step of initiating a cleaning cycle at a predetermined flow rate. 
     
     
         17 . A method for cleaning an electrolytic cell comprising electrodes, the method comprising the steps of:
 reversing polarities of two or more of the electrodes; and   providing a cleaning voltage potential difference to the electrodes which is lower than an operational voltage potential difference used during normal operation of the electrolytic cell.   
     
     
         18 . The method of  claim 17  wherein during normal operation the electrolytic cell produces a concentration of free available chlorine greater than approximately five grams per liter. 
     
     
         19 . The method of  claim 17  wherein the providing step is performed for a time between approximately five minutes and approximately ten minutes. 
     
     
         20 . The method of  claim 17  wherein the reversing step comprises using at least one power supply relay or other switching device. 
     
     
         21 . The method of  claim 17  wherein the operational voltage potential difference is provided by an operational power supply and the cleaning voltage potential difference is provided by a separate cleaning power supply. 
     
     
         22 . The method of  claim 17  further comprising the steps of monitoring a flow rate of electrolyte through the electrolytic cell and automatically adjusting the flow rate. 
     
     
         23 . An apparatus for producing electrolytic products, the apparatus comprising:
 an electrolytic cell comprising electrodes;   a first power supply for providing a first current density to said electrodes;   a second power supply for providing a second current density to said electrodes, said second power supply having an opposite polarity to said first power supply;   wherein the second current density is smaller than the first current density.   
     
     
         24 . The apparatus of  claim 23  wherein said electrolytic cell produces a concentration of free available chlorine greater than approximately five grams per liter. 
     
     
         25 . The apparatus of  claim 23  wherein the second current density is between approximately 10% and approximately 15% of the first current density. 
     
     
         26 . The apparatus of  claim 23  further comprising at least one power supply relay or other switching device. 
     
     
         27 . The apparatus of  claim 23  further comprising a flow monitoring device for monitoring a flow rate of electrolyte through said electrolytic cell. 
     
     
         28 . The apparatus of  claim 27  wherein said flow monitoring device is selected from the group consisting of a flowmeter, a rotameter, a pressure transducer, a pair of thermocouples, and a pair of thermowells. 
     
     
         29 . The apparatus of  claim 28  wherein one thermocouple or thermowell is disposed at an inlet of said electrolytic cell and another thermocouple or thermowell is disposed at an outlet of said electrolytic cell. 
     
     
         30 . The apparatus of  claim 27  further comprising an electronically operated valve for adjusting the flow rate.