Apparatus and method for liquid level measurement in electrolytic cells

Abstract

An apparatus and method for detecting a liquid level in an electrolytic cell are disclosed herein, the apparatus comprising a level tube in fluid contact with the electrolytic cell; a proximity sensor positioned to detect the presence or absence of liquid at a predetermined level in the level tube; and a control system responsive to the proximity sensor, wherein the control system is in communication with the liquid level sensor via a communication system. The proximity sensor detects the presence or absence of fluid in the level tube and sends a signal to the control system via the communication system; and the control system provides an indication of liquid level.

What is claimed is: 
     
         1 . An apparatus for detecting a liquid level in an electrolytic cell, the apparatus comprising
 a level tube in fluid contact with the electrolytic cell;   a proximity sensor positioned to detect the presence or absence of liquid at a predetermined level in the level tube; and   a control system responsive to the proximity sensor, wherein the control system is in communication with the proximity sensor via a communication system.   
     
     
         2 . The apparatus of  claim 1 , wherein the position of the proximity sensor is adjustable along the vertical axis of the level tube. 
     
     
         3 . The apparatus of  claim 1 , wherein the proximity sensor is a capacitive proximity sensor. 
     
     
         4 . The apparatus of  claim 5 , wherein the capacitive proximity sensor has a fixed capacitance for detecting the presence or absence of liquid in the level tube. 
     
     
         5 . The apparatus of  claim 5 , wherein the capacitive proximity sensor has an adjustable capacitance tunable to a value effective to detect the presence or absence of liquid in the level tube. 
     
     
         6 . The apparatus of  claim 5 , wherein the capacitive proximity sensor has a flat configuration and an adjustable capacitance. 
     
     
         7 . The apparatus of  claim 1 , wherein the communication system is a digital communication bus. 
     
     
         8 . The apparatus of  claim 1 , wherein the control system issues a signal to an operator in response to a signal from the proximity sensor. 
     
     
         9 . The apparatus of  claim 1 , wherein the liquid is an electrolyte. 
     
     
         10 . The apparatus of  claim 1 , wherein the electrolytic cell is a chlor-alkali electrolysis diaphragm cell. 
     
     
         11 . The apparatus of  claim 10 , wherein the liquid is brine. 
     
     
         12 . The apparatus of  claim 1 , wherein the proximity sensor detects a low liquid level, and wherein the low liquid level is 0 to about 70 percent of a target liquid level. 
     
     
         13 . The apparatus of  claim 12 , wherein a target liquid level is about 6 to about 8 inches above the top of a cathode in the electrolytic cell; and wherein the low liquid level is 0 to about 4 inches above the top of the cathode in the electrolytic cell. 
     
     
         14 . The apparatus of  claim 1 , comprising a first proximity sensor and a second proximity sensor, wherein the first proximity sensor detects a first liquid level, and the second proximity sensor detects a second liquid level below the first liquid level. 
     
     
         15 . The apparatus of  claim 14 , wherein the first liquid level represents a low liquid level and the second liquid level represents a low-low liquid level, and wherein the first liquid level is about 40 to about 80 percent of a target liquid level, and the second liquid level is 0 to about 40 percent of the target liquid level. 
     
     
         16 . The apparatus of  claim 14 , wherein a target liquid level is about 6 to about 8 inches above the top of a cathode in the electrolytic cell; wherein the first liquid level represents a low liquid level and the second liquid level represents a low-low liquid level; and
 wherein the first liquid level is about 3 to about 5 inches above the top of the cathode in the electrolytic cell, and the second liquid level is about 2 to about 3 inches above the top of the cathode in the electrolytic cell.   
     
     
         17 . The apparatus of  claim 14 , wherein the first liquid level represents a high liquid level and the second liquid level represents a low liquid level, and wherein the first liquid level is about 110 to about 130 percent of a target liquid level, and the second liquid level is 0 to about 40 percent of the target liquid level. 
     
     
         18 . The apparatus of  claim 14 , wherein a target liquid level is about 6 to about 8 inches above the top of a cathode in the electrolytic cell; wherein the first liquid level represents a high liquid level and the second liquid level represents a low liquid level; and
 wherein the first liquid level is about 7 to about 10 inches above the top of the cathode in the electrolytic cell, and the second liquid level is about 2 to about 3 inches above the top of the cathode in the electrolytic cell.   
     
     
         19 . An apparatus for detecting a brine level in a chlor-alkali electrolytic cell, the apparatus comprising
 a level tube in fluid contact with the chlor-alkali electrolytic cell;   a capacitive proximity sensor adjustably mounted on the level tube to detect the presence or absence of brine at a predetermined position on the level tube;   a support for positioning and mounting the capacitive proximity sensor on the level tube; and   a digital control system responsive to the capacitive proximity sensor, wherein the digital control system is in communication with the capacitive proximity sensor.   
     
     
         20 . A method for maintaining a target liquid level in an electrolytic cell, the method comprising
 providing an apparatus comprising
 a level tube in fluid contact with an electrolytic cell, 
 a proximity sensor positioned on the level tube at a target liquid level to detect the presence or absence of a liquid, and 
 a control system responsive to the proximity sensor, wherein the control system is in communication with the proximity sensor via a communication system, and indicates the presence or absence of the liquid at the target liquid level on the level tube in response to a signal from the proximity sensor; and 
   adjusting the liquid level in the electrolytic cell to the target liquid level in response to the signal.   
     
     
         21 . The method of  claim 20 , the method further comprising
 detecting with the proximity sensor the presence or absence of the liquid at the target liquid level on a level tube;   sending a signal from the proximity sensor to the control system in communication with the proximity sensor indicating the presence or absence of the liquid at the target liquid level on the level tube;   generating a signal from the control system indicating the presence or absence of the liquid at the target liquid level on the level tube; and   adjusting the liquid level in the electrolytic cell to the target liquid level in response to the signal from the control system.   
     
     
         22 . The method of  claim 20 , wherein the proximity sensor comprises a display. 
     
     
         23 . The method of  claim 20 , wherein the proximity sensor is a capacitive proximity sensor. 
     
     
         24 . The method of  claim 23 , wherein the capacitive proximity sensor has a fixed capacitance for detecting the presence or absence of liquid in the level tube. 
     
     
         25 . The method of  claim 23 , wherein the capacitive proximity sensor has an adjustable capacitance tunable to a value effective to detect the presence or absence of liquid in the level tube. 
     
     
         26 . The method of  claim 23 , wherein the capacitive proximity sensor has a flat configuration and an adjustable capacitance. 
     
     
         27 . The method of  claim 20 , wherein the communication system is a digital communication bus. 
     
     
         28 . The method of  claim 20 , wherein the control system issues a signal to an operator when the liquid is present or absent at the target liquid level on the level tube. 
     
     
         29 . The method of  claim 20 , wherein the liquid is an electrolyte. 
     
     
         30 . The method of  claim 20 , wherein the proximity sensor detects a low liquid level, and wherein the low liquid level is 0 to about 70% of the target liquid level. 
     
     
         31 . The method of  claim 30 , wherein the target liquid level is about 6 to about 8 inches above the top of a cathode in the electrolytic cell; and wherein the low liquid level is 0 to about  4  inches above the top of the cathode in the electrolytic cell. 
     
     
         32 . The method of  claim 20 , wherein the apparatus comprises a first proximity sensor and a second proximity sensor, wherein the first proximity sensor detects a first liquid level, and the second proximity sensor detects a second liquid level below the first liquid level. 
     
     
         33 . The method of  claim 32 , wherein the first liquid level represents a low liquid level and the second liquid level represents a low-low liquid level, and wherein the first liquid level is about 40 to about 80 percent of the target liquid level, and the second liquid level is 0 to about 40 percent of the target liquid level. 
     
     
         34 . The method of  claim 32 , wherein the target liquid level is about 6 to about 8 inches above the top of a cathode in the electrolytic cell; wherein the first liquid level represents a low liquid level and the second liquid level represents a low-low liquid level; and
 wherein the first liquid level is about 3 to about 5 inches above the top of the cathode in the electrolytic cell, and the second liquid level is about 2 to about 3 inches above the top of the cathode in the electrolytic cell.   
     
     
         35 . The method of  claim 32 , wherein the first liquid level represents a high liquid level and the second liquid level represents a low liquid level, and wherein the first liquid level is about 110 to about 130 percent of the target liquid level, and the second liquid level is 0 to about 40 percent of the target liquid level. 
     
     
         36 . The method of  claim 32 , wherein the target liquid level is about 6 to about 8 inches above the top of a cathode in the electrolytic cell; wherein the first liquid level represents a high liquid level and the second liquid level represents a low liquid level; and
 wherein the first liquid level is about 7 to about 10 inches above the top of the cathode in the electrolytic cell, and the second liquid level is about 2 to about 3 inches above the top of the cathode in the electrolytic cell.   
     
     
         37 . A method for maintaining a target brine level in a chlor-alkali electrolytic cell, the method comprising
 providing an apparatus comprising
 a level tube in fluid contact with the chlor-alkali electrolytic cell, 
 a capacitive proximity sensor adjustably mounted on the level tube to detect the presence or absence of brine at the target brine level on the level tube, 
 a support for positioning and mounting the capacitive proximity sensor on the level tube, and 
 a digital control system responsive to the capacitive proximity sensor, wherein the digital control system is in communication with the capacitive proximity sensor and indicates the presence or absence of the brine at the target brine level on the level tube in response to a signal from the capacitive proximity sensor; and 
   adjusting the brine level in the chlor-alkali electrolytic cell to the target brine level in response to the signal.   
     
     
         38 . The method of  claim 37 , further comprising
 detecting with a capacitive proximity sensor the presence or absence of brine at the target brine level;   sending a signal from the capacitive proximity sensor to the digital control system indicating the presence or absence of the brine at the target brine level on the level tube;   generating a signal from the digital control system indicating the presence or absence of the brine at the target brine level on the level tube; and   adjusting the brine level in the chlor-alkali electrolytic cell to the target brine level in response to the signal from the digital control system.