Solid oxide fuel cell system for producing variable generated power based on power demand

摘要

The present invention provides a solid oxide fuel cell system capable of preventing excess temperature rises while increasing overall energy efficiency. The present invention is a solid oxide fuel cell system, including: a fuel cell module, a fuel supply device, a heat storing material, and a controller which, based on power demand, increases the fuel utilization rate when output power is high and to lower it when output power is low, and changes the electrical power actually output at a delay after changing the fuel supply amount. The controller has a stored heat estimating circuit for estimating the surplus heat based on fuel supply and on power output at a delay relative thereto. When a utilizable amount of surplus heat is accumulated in the heat storage material, the fuel supply is reduced so that the fuel utilization rate increases relative to the same electrical power.

主权项

1. A solid oxide fuel cell system operable to generate electrical power variable in accordance with power demand, comprising:
a fuel cell module configured to generate the electrical power using fuel; a fuel supply device configured to supply the fuel at a fuel supply rate to the fuel cell module; an oxidant gas supply device configured to supply oxidant gas at an oxidant gas supply rate to the fuel cell module for generation of the electrical power; a heat storage material configured to store heat produced within the fuel cell module; a power demand detection device configured to detect the power demand; and a controller programmed to operate the fuel supply device, responsive to a change of the power demand, to change the fuel supply rate to change a level of the electrical power generated from the fuel cell module and output the electrical power at a changed level to meet the change of the power demand, wherein the controller is programmed to have a delay time implemented between outputting the electrical power at the changed level and changing the fuel supply rate in response to the change of the power demand, wherein the controller comprises a stored-heat estimating circuit programmed to estimate an amount of surplus heat accumulated in the heat storage material at least in part by implementations of the delay time between changing the fuel supply rate and outputting the electrical power at the changed level, and wherein in response to an estimation by the stored heat estimating circuit that a first amount of surplus heat is accumulated in the heat storage material, the controller is programmed to control the fuel supply rate to output a level of electrical power at a first fuel utilization rate, and in response to an estimation by the stored heat estimating circuit that a second amount of surplus heat, which is higher than the first amount of surplus heat, is accumulated in the heat storage material, control the fuel supply rate to output the level of electrical power at a second fuel utilization rate, which is higher than the first fuel utilization rate, wherein the fuel utilization rate is a rate of an amount of fuel used for generation of electrical power with respect to a total amount of fuel supplied to the fuel supply device.