Sirius P.Eng.
Chemical
We are currently engaged in a conceptual study for a Natural Gas Pipeline Gas Turbine Driven Centrifugal Compressor Facility.
The overall compression ratio is 2.614. Even though the discharge temperature is below the limits commonly imposed for per stage, I am considering 2 preliminary concepts which I have run in HYSYS with a polytropic efficiency of 70%:
1. Single-stage design (11.32 MW brake power)
2. 2-stage Design (10.73 MW brake power) - 1st Stage compression ratio 1.626, 2nd stage compression ratio is 1.625.
Obviously, the 2-stage design has the advantage of lower compression power - 600 kW less; I have estimated the fuel gas savings to be about US$6 million over the 25 years life of the facility. However, I expect the capital investment and yearly maintenance cost for the 2-stage design to be higher.
1. Can anyone share any correlations or simple formulas for:
- Estimating the total capital cost of the gas turbine driven centrifugal compressor (i.e gas compressor, gas turbine, interstage cooler, piping, etc.) -
for instance, in US$/MW or US$/BHP, etc.
- Estimating the yearly maintenance costs (parts, servicing, etc.)
- Other factors to be considered in the life cycle cost of the
2. For the 2-stage design, the maximum allowable pressure drop across the interstage cooler is 70 kPa. I understand that the most economical approach is to use equal compression ratios per stage. How can I relate mathematically, the relationship between the compression ratio per stage, suction pressure and discharge pressure and the pressure drop across the interstage cooler? - in my initial HYSYS model I used a trial-and-error approach.
The overall compression ratio is 2.614. Even though the discharge temperature is below the limits commonly imposed for per stage, I am considering 2 preliminary concepts which I have run in HYSYS with a polytropic efficiency of 70%:
1. Single-stage design (11.32 MW brake power)
2. 2-stage Design (10.73 MW brake power) - 1st Stage compression ratio 1.626, 2nd stage compression ratio is 1.625.
Obviously, the 2-stage design has the advantage of lower compression power - 600 kW less; I have estimated the fuel gas savings to be about US$6 million over the 25 years life of the facility. However, I expect the capital investment and yearly maintenance cost for the 2-stage design to be higher.
1. Can anyone share any correlations or simple formulas for:
- Estimating the total capital cost of the gas turbine driven centrifugal compressor (i.e gas compressor, gas turbine, interstage cooler, piping, etc.) -
for instance, in US$/MW or US$/BHP, etc.
- Estimating the yearly maintenance costs (parts, servicing, etc.)
- Other factors to be considered in the life cycle cost of the
2. For the 2-stage design, the maximum allowable pressure drop across the interstage cooler is 70 kPa. I understand that the most economical approach is to use equal compression ratios per stage. How can I relate mathematically, the relationship between the compression ratio per stage, suction pressure and discharge pressure and the pressure drop across the interstage cooler? - in my initial HYSYS model I used a trial-and-error approach.