Oxygen consumption rate monitor

Claim 1

Apparatus for determining the oxygen consumption rate of a process having an input source of oxygen and an exhaust, comprising in combination, a first solid electrolyte electrochemical cell having a first electrically conductive electrode and a second electrically conductive electrode, means for maintaining an oxygen reference media of known oxygen concentration at said second electrode, means for supplying a sample of said process exhaust gas to said first electrode, said first solid electrolyte electrochemical cell generating an EMF as a function of the difference in oxygen concentration between the oxygen reference media and the sample exhaust gas, a second solid electrolyte electrochemical cell having a first electrically conductive electrode and a second electrically conductive electrode, means for providing an oxygen containing media at said second electrode of said second electrochemical cell, means for supplying said sample exhaust gas to said first electrode of said second electrochemical cell prior to supplying said sample exhaust gas to said first electrochemical cell, and a feedback circuit means operatively connected between the electrodes of said first solid electrolyte electrochemical cell and the electrodes of said second solid electrolyte electrochemical cell to apply the EMF signal generated by said first solid electrolyte electrochemical cell as an excitation signal across the electrodes of said second solid electrolyte electrochemical cell, said second solid electrolyte electrochemical cell operating as an oxygen ion pump, the current generated by said second solid electrolyte electrochemical cell as a result of the applied excitation from said feedback circuit changing the oxygen concentration of the sample exhaust gas until the oxygen concentration of the sample exhaust gas substantially equals the oxygen concentration of the oxygen reference media of said first solid electrolyte electrochemical cell thereby resulting in an EMF signal output of approximately zero from said first solid electrolyte electrochemical cell, said current flow in said second solid electrolyte electrochemical cell being an indication of the oxygen consumption rate of said process, and blower means including a variable speed blower and a blower speed control circuit means operatively coupled between said second solid electrolyte electrochemical cell and said variable speed blower to control the speed of the blower as a function of the current generated by said solid electrolyte electrochemical cell.