Fast start-up analyses for Benson heat recovery steam generator

In this study, an entire simulation model is developed to investigate the influence of fast gas turbine start-up (within 20 min) on the dynamic behavior of a Benson heat recovery steam generator. The model includes a new high pressure feedwater control concept that considers a large number of live plant parameters and derivative functions. The advanced feedwater control circuit offers the possibility to operate the high pressure system in level mode (nature circulation) or Benson mode (once-through). Furthermore, it provides a rapid response and ensures a save operation to Benson HRSG (heat recovery steam generator) during the GT (gas turbine) abrupt transients and fast start-up procedures. A set of enhanced steam bypass control circuits are also implemented in the model. The developed HRSG model and its advanced control circuits are validated toward the design data at different part loads. The obtained results demonstrate very good physical agreement with relative error less than 3% and cite as evidence that the Benson model represents the real power plant. Finally, different fast start-up procedures (hot, warm, cold) are assessed with the validated Benson model, which provides adaptable operation demands to meet the gas turbine fast start-up requirements.

► New high pressure feedwater control concept offers the possibility to operate in level or once-through mode.
► Benson provides adaptable operation demands to meet gas turbine fast start-up requirements.
► Modern gas turbine reaches its nominal load within 20 min while heat recovery steam generator needs 50, 90 or 170 min depending on start-up types.