A dynamic simulator was developed for a natural circulation drum type boiler through a joint Youngstown State University/The Babcock and Wilcox Company cooperative agreement. The model was created using the commercial software package MATLAB/Simulink. The goal was to produce a model that could numerically analyze the transient, cold start of a drum boiler system for use in product design and optimization.
The drum boiler was first separated into individual components consisting of the economizer, drum, downcomer, waterwall, superheater, turbine valve, and controller. Flow streams were then developed to transfer enthalpy, pressure, and mass flow rate between the components. Within the components, conservation of mass, momentum, and energy were applied to compute the exit enthalpy, pressure, and mass flow rate from the incoming flow streams. Also, an in depth analysis of transport delay was performed to develop an algorithm with a moving boundary in order to eliminate numerical diffusion.
The simulator was able to perform a cold-start transient up to operating pressure. A comparison of the drum pressure solver was made with a published Simulink model and reasonable agreement was found. Also, the pressure-flow solver performed within 0.1 psi using a ten second time step. The developed transport delay algorithm performed well on a system-wide basis and proved to conserve both energy and the enthalpy profile. The methodology used allows for component compression to extend discretization enhancing solution resolution, as well as component use in other boiler systems.