A Method for Evaluating Market Value of Turbine Gaspath Component Alternatives

An economic model was developed to evaluate gas turbine component alternatives for base load combined cycle operation, cyclic duty simple cycle operation, and peaking duty simple cycle operation. Power plant operator value of alternative replacement first stage buckets for a GE Frame 7EA gas turbine is evaluated. The popularity and large installed base of the 7EA has prompted a number of replacement part offerings, in addition to the replacement parts offered by the OEM. A baseline case is established to represent the current bucket repair and replacement situation. Each of the modes of power plant operation is evaluated from both a long-term financial focus and a short-term financial focus. Long-term focus is characterized by a nine-year evaluation period, while short-term focus is based on first year benefit only. Four factors are considered: part price repair price, output increase, and simple cycle efficiency increase. Natural gas and liquid fuels are considered. Two natural gas prices are used; one liquid fuel price is considered. Peak, off-peak, and spot market electricity prices are considered. Two baseline repair price scenarios are evaluated: 50% of new part price and 10% of new part price. The key conclusions can be summarized as: • A reduced-life part with more frequent repair intervals is undesirable, even if the part price is reduced by over 60% and the cooling flow is reduced by 1% W₂. • A short-life, “throw-away” part with no required repairs can achieve parity with the baseline if the price is reduced by 25% or more. The operator with a short-term focus will not differentiate between a “throw-away” part and a full-life part. • In general, increased part life has less value to the power plant operator than price reduction or cooling flow reduction. • Repair price (assumed to be 50% of part price) is a relatively small factor for operators with a long-term focus, and no factor at all for operators with a short-term focus. A lower baseline repair price (10% of part price) will decrease the attractiveness of a “throw-away” part, moving the parity point to a 40% price reduction. • A 0.7% W₂ reduction in cooling flow has roughly the same first year benefit, at baseline fuel prices, as a 10–15% bucket price reduction, except to the peak duty operator. The peak duty operator finds no benefit to reduced cooling flow unless electricity can be sold at spot market prices.