Power augmentation on gas turbines in summer months
The average annual capacity of TE-TO AD Skopje is 220 MW, but depending on the atmospheric conditions (temperature, pressure and humidity) the production varies from 205 MW to 239 MW.
Turbine output and efficiency of gas turbines is reduced during periods of high ambient temperature. This creates a need to overcome the inherent loss of gas turbine output during this crucial period when enhanced power is most required, exactly in the periods with high ambient temperature.
Fogging system is a gas turbine power augmentation method that consists of injecting atomized water droplets (fog) directly into the gas turbine compressor to improve output and heat rate, i.e decreases of inlet air temperature and increases the mass flow through the compressor. When the ultra-fine water droplets evaporate inside the compressor, they reduce the temperature and significantly reduce the energy consumed by the compressor, the increased mass flow results in an increase in the injected gas in the chamber, which means more power is available at the output shaft of the gas turbine.
Fogging system in a gas turbine – MeeFog
In 2021, TE-TO AD Skopje launched an initiative to implement a power augmentation systems Fogging system on the gas turbine, which in the summer months would contribute to increasing the power of the turbine by about 13 MW (megawatts) under suitable ambient conditions.
The preconditions for the realization of the investment are:
- Sufficient number of hours with high ambient temperature and low humidity
- Sufficient demin water with < 1,5 mS/cm quality
- Demand for peak power during the summer months
- Acceptable price of energy in the hours when these preconditions are met
After analyzing in details it was concluded that the technical and commercial preconditions are met.
Equipment included in the MeeFog system:
- Feed pump for demineralized water for the MeeFog system
- Pump skid with filters and solenoid valves
- Water piping and sprinklers – the most important segment
- Programmable Logic Controller [PLC)
Feed pump, a pump skid, filters, solenoid valves
Installed MeeFog system
The pump skid is installed near the air inlet filter house, on a proper platform.
The water piping and the nozzles are installed after the fine filters directly in the air stream, before the silencers, where several rows of sprinklers are placed on the pipelines.
Water piping and sprinklers in the air intake of Gas Turbine
Main benefits of Power Augmentations project – MeeFog system:
- Increased power production in the hot summer months– maximal value around 13 MW, depending of available temperature drop between dry air temperature and wet bulb temperature.
- Increased range for tertiary power control and ability to be integrated with an automatic generation control signal AGC, contributing in more profit for the power plant
- Reduced NOx emissions (only for inlet fogging)
- Reduced electrical debalanse towards the grid, as the augmentation system can be used to balance the power production nominations
From the calculation of the annual benefit, the investment return period is estimated on 2 years.
The system was put into operation at the beginning of September 2023, at the very end of the summer period, during which an additional 600 MWh of energy was produced in the most unfavorable months. In 2024, only in the summer months, i.e. June, July and August, the power plant with the integrated MeeFog system produced an additional 4000 MWh of electricity. Тhis energy was mostly sold as tertiary regulation or used to balance the planned production, so the profit from it is higher than the regular one.