Once-through evaporator systems

A method to control a once-through evaporator system with a plurality of once-through evaporator sections with a distribution valve, comprising:

• positioning a position controller in communication with each distribution valve;
• positioning downstream temperature sensor and a temperature controller in communication with each position controller;
• each position controller determining a static head prediction and a required pressure drop over each distribution valve;
• each temperature controller providing a flow target to each position controller as a set point;
• the set point being based on an average of once-through evaporators section temperatures;
• and
• biasing the set point by a dead band based the average of once-through evaporator section temperatures with respect to an average saturation temperature.

A once-through evaporator system, comprising:

• a plurality of once-through evaporator sections;
• each of the plurality of once-through evaporator sections comprising an upstream distribution valve and a downstream temperature sensor;
• a water separator with a water separator temperature sensor downstream of the plurality of once-through evaporator sections;
• and
• wherein each distribution valve is in communication with a deadband flow control system.