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Performance of a Semi-Closed Oxy-Fuel Combustion Combined Cycle (scoc-cc) with an Air Separation Unit (ASU)

Sammak, Majed LU ; Thern, Marcus LU and Genrup, Magnus LU (2018) ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018 3.
Abstract

The objective of this paper is to evaluate the performance of a semi-closed oxy-fuel combustion combined cycle (SCOC-CC) and its power penalties. The power penalties are associated with CO2 compression and high-pressure oxygen production in the air separation unit (ASU). The paper discusses three different methods for high pressure oxygen (O2) production. Method 1 is producing O2 directly at high pressure by compressing the air before the air separation takes place. Method 2 is producing O2 at low pressure and then compressing the separated O2 to the desired pressure with a compressor. Method 3 is alike the second method, except that the separated liquid O2 is pressurized... (More)

The objective of this paper is to evaluate the performance of a semi-closed oxy-fuel combustion combined cycle (SCOC-CC) and its power penalties. The power penalties are associated with CO2 compression and high-pressure oxygen production in the air separation unit (ASU). The paper discusses three different methods for high pressure oxygen (O2) production. Method 1 is producing O2 directly at high pressure by compressing the air before the air separation takes place. Method 2 is producing O2 at low pressure and then compressing the separated O2 to the desired pressure with a compressor. Method 3 is alike the second method, except that the separated liquid O2 is pressurized with a liquid oxygen pump to the desired pressure. The studied SCOC-CC is a dual-pressure level steam cycle due to its comparable efficiency with three pressure level steam cycle and less complexity. The SCOC-CC, ASU and CO2 compression train are modeled with the commercial heat and mass balance software IPSEpro. The paper analyzed the SCOC-CC performance at different combustion outlet temperatures and pressure ratios. The combustion outlet temperature (COT) varied from 1200 °C to 1550 °C and the pressure ratio varied from 25 to 45. The study is concerned with mid-sized SCOC-CC with a net power output 100 MW. The calculations were performed at the selected design point which was at 1400°C and pressure ratio at 37. The calculated power consumption of the O2 separation at a purity of 95 % was 719 kJ/kgO2. The power consumption for pressurizing the separated O2 (method 2) was 345 kJ/kgO2 whereas it was 4.4 kJ/kgO2 for pumping liquid O2 to the required pressure (method 3). The calculated power consumption for pressurizing and pumping the CO2-enriched stream was 323 kJ/kgCO2. The SCOC-CC gross efficiency was 57.6 %. The SCOCCC net efficiency at method 2 for air separation was 46.7 %. The gross efficiency was reduced by 9 % due to ASU and other 2 % due to CO2 compression. The SCOC-CC net efficiency at method 3 of the air separation was 49.6 %. The ASU reduced the gross efficiency by 6 % and additional 2 % by CO2 compression. Using method 3 for air separation gave a 3 % gain in cycle efficiency.

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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
air separation unit, combined cycle, cycle performanc, liquid oxygen, oxy fuel, SCOC-CC
host publication
Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems
volume
3
publisher
American Society of Mechanical Engineers(ASME)
conference name
ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018
conference location
Oslo, Norway
conference dates
2018-06-11 - 2018-06-15
external identifiers
  • scopus:85053921846
ISBN
9780791851043
DOI
10.1115/GT2018-76218
language
English
LU publication?
yes
id
ea7f8128-3743-4d73-a42b-7a836d85dfe6
date added to LUP
2018-10-22 10:35:09
date last changed
2019-02-20 11:32:30
@inproceedings{ea7f8128-3743-4d73-a42b-7a836d85dfe6,
  abstract     = {<p>The objective of this paper is to evaluate the performance of a semi-closed oxy-fuel combustion combined cycle (SCOC-CC) and its power penalties. The power penalties are associated with CO<sub>2</sub> compression and high-pressure oxygen production in the air separation unit (ASU). The paper discusses three different methods for high pressure oxygen (O<sub>2</sub>) production. Method 1 is producing O<sub>2</sub> directly at high pressure by compressing the air before the air separation takes place. Method 2 is producing O<sub>2</sub> at low pressure and then compressing the separated O<sub>2</sub> to the desired pressure with a compressor. Method 3 is alike the second method, except that the separated liquid O<sub>2</sub> is pressurized with a liquid oxygen pump to the desired pressure. The studied SCOC-CC is a dual-pressure level steam cycle due to its comparable efficiency with three pressure level steam cycle and less complexity. The SCOC-CC, ASU and CO<sub>2</sub> compression train are modeled with the commercial heat and mass balance software IPSEpro. The paper analyzed the SCOC-CC performance at different combustion outlet temperatures and pressure ratios. The combustion outlet temperature (COT) varied from 1200 °C to 1550 °C and the pressure ratio varied from 25 to 45. The study is concerned with mid-sized SCOC-CC with a net power output 100 MW. The calculations were performed at the selected design point which was at 1400°C and pressure ratio at 37. The calculated power consumption of the O<sub>2</sub> separation at a purity of 95 % was 719 kJ/kgO<sub>2</sub>. The power consumption for pressurizing the separated O<sub>2</sub> (method 2) was 345 kJ/kgO<sub>2</sub> whereas it was 4.4 kJ/kgO<sub>2</sub> for pumping liquid O<sub>2</sub> to the required pressure (method 3). The calculated power consumption for pressurizing and pumping the CO<sub>2</sub>-enriched stream was 323 kJ/kgCO<sub>2</sub>. The SCOC-CC gross efficiency was 57.6 %. The SCOCCC net efficiency at method 2 for air separation was 46.7 %. The gross efficiency was reduced by 9 % due to ASU and other 2 % due to CO<sub>2</sub> compression. The SCOC-CC net efficiency at method 3 of the air separation was 49.6 %. The ASU reduced the gross efficiency by 6 % and additional 2 % by CO<sub>2</sub> compression. Using method 3 for air separation gave a 3 % gain in cycle efficiency.</p>},
  author       = {Sammak, Majed and Thern, Marcus and Genrup, Magnus},
  isbn         = {9780791851043},
  keyword      = {air separation unit,combined cycle,cycle performanc,liquid oxygen,oxy fuel,SCOC-CC},
  language     = {eng},
  location     = {Oslo, Norway},
  publisher    = {American Society of Mechanical Engineers(ASME)},
  title        = {Performance of a Semi-Closed Oxy-Fuel Combustion Combined Cycle (scoc-cc) with an Air Separation Unit (ASU)},
  url          = {http://dx.doi.org/10.1115/GT2018-76218},
  volume       = {3},
  year         = {2018},
}