Dynamic heat release calculation for improved feedback control of solid-fuel-based combustion processes

A system for modulating a solid-fuel-based combustion process, comprising:

• a processing unit;
• and
• a non-transitory computer-readable memory having stored thereon program instructions executable by the processing unit for:
• determining, using a virtual sensor, a current instantaneous heat release of a solid-fuel-based heat generator based on at least two sensor values, the at least two sensor values comprising a flow rate of steam produced by the heat generator and a steam drum pressure differential over time in the heat generator;
• at a high speed heat release controller in cascade connection with a slow-speed heat release controller comprising one of a steam flow controller and a steam pressure controller, receiving the current instantaneous heat release from the virtual sensor and comparing the current instantaneous heat release to a current firing rate demand received from the slow-speed controller;
• and
• when the current instantaneous heat release does not correspond to the current firing rate demand, causing, at the high-speed controller, an underfire air flow of and a rate of fuel flow to the heat generator, to be adjusted with a closed-loop time constant of less than two minutes to minimize a difference between the current instantaneous heat release and the current firing rate demand.