Patent ID: 8097138

Claim:
An oxygen partial pressure control apparatus comprising: at least one oxygen pump comprising a solid electrolyte with a tubular structure, at least two oxygen sensors, wherein each of said two oxygen sensors comprises comprising a solid electrolyte with a tubular structure, a heating furnace which houses the oxygen pump and the oxygen sensors and which can heat and maintain said at least one oxygen pump and said at least two oxygen sensors at an operational temperature, and wherein air or pure oxygen is supplied to the inside of the heating furnace, and an oxygen pump operation control means for controlling operation of said oxygen pump based on the oxygen partial pressure detected by said oxygen sensors, wherein the oxygen pump and the oxygen sensors are placed in parallel, such that the air or pure oxygen serves as a purge gas that sweeps the surroundings of said at least one oxygen pump and said at least two oxygen sensors, and said at least one oxygen pump and said at least two oxygen sensors are connected such that a common process gas can flow through said at least one oxygen pump and said at least two oxygen sensors, wherein the common process gas whose oxygen partial pressure has been reduced by the oxygen pump can be introduced into the oxygen sensors, and wherein said oxygen pump operation control means has a PID (proportional-integral derivative) constant defined as a function of the oxygen partial pressure, and every time either of said at least two oxygen sensors samples a current oxygen partial pressure value, said PID constant is automatically adjusted in coordination with the function to depend on the current oxygen partial pressure, and wherein operation of said oxygen pump is subjected to PID control based on the adjusted PID constant.