The present application provides a method of adjusting a feedwater mass flow rate to maintain a constant steam temperature in an evaporator section. The method may include the steps of determining a change in a number of operational parameters, predicting a change in steam temperature based on the number of operational parameters, combining the predicted changes in steam temperature, determining a feedforward signal based on dynamically offsetting the combined predicted changes in steam temperature, and changing the mass flow rate of feedwater based on the feedforward signal.