System and method for controlling liquid level in a vessel

A level control system for controlling a liquid level in a vessel containing a two-phase fluid, the system comprising:

• a plurality of sensors configured to measure parameters related to the vessel, wherein the parameters comprise liquid level in the vessel, vapor flow rate leaving the vessel, pressure in the vessel, temperature of the vessel, and feed-liquid flow rate entering the vessel indicative of a state of the vessel;
• a predictive controller configured to receive output signals from the plurality of sensors and control a liquid level in the vessel based on the output signals from the plurality of sensors;
• the controller comprising:
• a volume prediction unit configured to predict a volume of liquid in the vessel based on output signals from the plurality of sensors and a variation in pressure, thermal load, or combinations thereof in the vessel;
• a set point generation unit configured to generate a liquid level set point of the vessel based on the predicted volume of liquid over a predetermined time period in the vessel;
• and
• a liquid level control unit configured to control a liquid level in the vessel based on the generated liquid level set point by manipulating one or more elements coupled to the vessel.

A level control system for controlling a water level in a boiler drum containing a two-phase fluid;

• the system comprising:
• sensors configured to measure parameters related to the boiler drum, wherein the parameters comprise water level in the boiler drum;
• steam flow rate leaving the boiler drum;
• pressure in the boiler drum, temperature of the boiler drum, and feed-water flow rate entering the boiler drum indicative of a state of the boiler drum;
• a predictive controller configured to receive output signals from the plurality of sensors and predict a volume of water in the boiler drum based on output signals from the plurality of sensors and a variation in pressure, thermal load, or combinations thereof in the boiler drum;
• wherein the controller is configured to generate a water level set point of the boiler drum based on the predicted volume of water over a predetermined time period in the vessel;
• and control a water level in the boiler drum based on the generated water level set point by manipulating one or more control elements coupled to the boiler drum.

A method for controlling a liquid level in a vessel containing a two-phase fluid, the method comprising:

• sensing parameters related to the vessel via a plurality of sensors;
• wherein sensing parameters comprises sensing liquid level in the vessel, vapor flow rate leaving the vessel, pressure in the vessel, temperature of the vessel, and feed-liquid flow rate entering the vessel indicative of a state of the vessel;
• predicting a volume of liquid in the vessel based on output signals from the plurality of sensors and a variation in pressure, thermal load, or combinations thereof in the vessel;
• generating a liquid level set point of the vessel based on the predicted volume of liquid over a predetermined time period in the vessel;
• and
• controlling a liquid level in the vessel based on the generated liquid level set point by manipulating one or more control elements coupled to the vessel.