Flue gas stack suction control

An industrial plant comprising a flue gas processing system, the industrial plant comprising:

• a flue gas stack which is configured to receive a flue gas from at least one industrial process, the flue gas stack comprising a discharge outlet which is open to the atmosphere;
• a flue gas processing unit;
• a suction line which is connected between the flue gas stack and the flue gas processing unit;
• a fan which is operatively arranged in the suction line, the fan being configured to draw the flue gas from the flue gas stack to the flue gas processing unit;
• a sensor which is configured to provide a signal which is representative of a gas flow rate or a change in the gas flow rate through the discharge outlet of the flue gas stack, the signal being a measured signal or a calculated signal;
• a controller which is arranged to regulate a flow through the suction line based on the signal from the sensor;
• and
• a flow restriction arranged in the suction line upstream of the fan,
• wherein,
• the fan comprises a control arrangement which is configured to control a pressure in the suction line upstream of the fan and downstream of the flow restriction or to control a pressure differential across the flow restriction.

A method of controlling an operation of an industrial plant which comprises a flue gas processing system, the method comprising:

• operating an industrial process to produce a flue gas;
• flowing the flue gas from a flue gas stack to a flue gas processing unit via a suction line, the flue gas stack comprising a discharge outlet which is open to the atmosphere;
• operating a controller to control a flow rate of the flue gas through the suction line by regulating a flow restriction in the suction line in response to a signal from a sensor, the signal being a measured signal or a calculated signal which is representative of a gas flow rate or a change in the gas flow rate through the discharge outlet of the flue gas stack;
• and
• operating a control arrangement of a fan, the fan being arranged in the suction line downstream of the flow restriction and being configured to control a pressure in the suction line downstream of the flow restriction and upstream of the fan or to control a pressure differential across the flow restriction.