Monitoring temperatures of a process heater

A method for monitoring a temperature of a process heater, comprising:

• coupling an access port to an inspection window of a process heater that comprises a plurality of heating tubulars mounted in an inner volume of the process heater, the access port comprising at least one visual access portion;
• coupling a first side of a flange assembly to the access port, the flange assembly comprising a bore that extends from the first side to a second side opposite the first side;
• coupling a thermal imaging system to the second side of the flange assembly, the thermal imaging system comprising at least one thermal image capture device comprising a field of view through the bore of the flange of assembly and the at least one visual access portion and into the inner volume of the process heater;
• and
• operating the at least one thermal image capture device to capture at least one image of radiation emitted from the portion of the plurality of heating tubulars.

A system, comprising:

• a door that comprises a window, the door configured to mount to an inspection port of an acid gas preheater that comprises a plurality of heating tubes mounted in a firebox of the acid gas preheater;
• a thermal camera coupled to the door, the thermal camera comprising a focal point aligned with at least one of a center of the window or a center of the inspection port;
• and
• a control system communicably coupled to the thermal camera, the control system configured to perform operations comprising:
• operating the thermal camera to capture at least one thermal image of at least a portion of the plurality of heating tubes;
• processing the captured thermal image into a graphical representation of the thermal image, the graphical representation comprising a plurality of thermal values associated with a plurality of discrete surface locations of the portion of the plurality of heating tubes;
• and
• presenting the graphical representation of the thermal image on a graphical user interface (GUI) communicably coupled to the control system.