Key issues:
- It is a requirement of the Power Station gas turbines that the gas temperature should never fall below +5 °C.
- However, during a cold winter day or night start-up sequence when the outside temperature could be as low as -6 °C, exposed components and associated pipe work may cause the delivery of gas to the gas turbine that is lower than the minimum prescribed temperature during the initial few minutes.
Methodology:
- Simulate various cold start-up scenarios with heat transfer.
Solution:
- Without trace heating the simulation showed sub -5 °C gas will reach the gas turbine for at least the first 2 minutes until 12 °C gas from the underground buffer zone will increase the gas temperature above 5 °C.Thus trace heating is needed from the final filters and associated spooling (and all the way to the gas turbines). As shown in the simulation, the buffer spool outlet temperature does not fall below about 10 °C at any time due to its large thermal inertia and hence heat tracing upstream of the buffer spools is not required.
