Adaptive control of BTX removal in sulfur recovery units

A system comprising:

• an outlet flowline from an activated carbon bed, the outlet flowline configured to flow an acid gas stream out of the activated carbon bed after the activated carbon bed has removed benzene, toluene, and xylene from the acid gas stream;
• a bypass flowline connected to the outlet flowline, the bypass flowline having an inner diameter that is smaller in comparison to an inner diameter of the outlet flowline, the bypass flowline providing an alternative flow path for the acid gas stream exiting the activated carbon bed around the outlet flowline, the bypass flowline comprising a bypass valve configured to control flow of the acid gas stream exiting the activated carbon bed through the bypass flowline;
• a furnace configured to receive the acid gas stream from at least one of the outlet flowline or the bypass flowline, the furnace comprising a burner configured to combust at least a portion of the acid gas stream in the presence of oxygen;
• a control system comprising:
• a temperature sensor coupled to the furnace, the temperature sensor configured to measure a furnace temperature of the furnace and transmit the measured furnace temperature;
• and
• a controller communicatively coupled to the temperature sensor and to the bypass valve, the controller configured to:
• receive the measured furnace temperature from the temperature sensor;
• determine a difference between the measured furnace temperature and a specified setpoint temperature;
• and
• reduce a percent opening of the bypass valve in response to determining that the difference between the measured furnace temperature and the specified setpoint temperature is equal to or greater than 10 degrees Fahrenheit (° F.) differential.

A method comprising:

• flowing an acid gas stream to an activated carbon bed, the acid gas stream comprising hydrogen sulfide, benzene, toluene, and xylene;
• removing, by the activated carbon bed, benzene, toluene, and xylene from the acid gas stream;
• flowing the acid gas stream from the activated carbon bed to a furnace comprising a burner;
• combusting, by the burner, at least a portion of the acid gas stream in the presence of oxygen;
• measuring, by a temperature sensor coupled to the furnace, a furnace temperature of the furnace;
• determining, by a controller communicatively coupled to the temperature sensor, a difference between the measured furnace temperature and a specified setpoint temperature;
• and
• adjusting, by the controller, flow of the acid gas stream from the activated carbon bed to the furnace in response to determining that the difference between the measured furnace temperature and the specified setpoint temperature is equal to or greater than 10 degrees Fahrenheit (° F.) differential.