{"id":2613,"date":"2021-03-14T11:07:27","date_gmt":"2021-03-14T10:07:27","guid":{"rendered":"https:\/\/yvcharron.com\/?page_id=2613"},"modified":"2021-04-06T15:21:04","modified_gmt":"2021-04-06T13:21:04","slug":"fossil-fuel-power-plants-intermediate-co2-removal","status":"publish","type":"page","link":"https:\/\/yvcharron.com\/index.php\/fossil-fuel-power-plants-intermediate-co2-removal\/","title":{"rendered":"Fossil Fuel Power Plants – Carbon dioxide – INTERMEDIATE CO2 removal – Stoichiometric combustion – Compression-expansion loop – Physical solvent – CO2 inventory"},"content":{"rendered":"\n

CONTENT:<\/strong> 1_Introduction; 2_Gas turbine types; 3_Examples of gas turbine intermediate air process; 4_Description of an intermediate CO2 removal system; 5_System performance; 6_Carbon dioxide inventory; 7_Comparison between external and intermediate systems; 8_Conclusion; Annexe 1 \u2013 Combustion chamber pressure parameter; Annexe 2 \u2013 Artificial air dilution increase<\/p>\n\n\n\n

1_Introduction<\/strong><\/h2>\n\n\n\n

Carbon dioxide concentration into the atmosphere is a major issue. Unfortunately, this gas is not the only one responsible for atmosphere pollution. Other gases produced during fossil fuel combustion present similar danger like greenhouse effect, toxicity and acid rains. These gases are mainly water vapour, nitrogen oxides, carbon monoxide, hydrocarbons and fine particles. As such, all efforts to limit their emission should be undertaken. In this document, these gases are often included in the wording \u201cCarbon dioxide\u201d for simplification.<\/p>\n\n\n\n

Page \u201cPower plants \u2013 External CO2 removal\u201d of this web site, describes how carbon dioxide produced in the combustion chamber of a gas turbine may be absorbed at a relatively high pressure and low temperature in a contactor by a physical solvent. This high pressure is achieved by a compression – expansion loop<\/strong> activated by the energy of the hot gas exiting the power turbine. This gas process is carried out externally to the gas turbine<\/strong>.<\/p>\n\n\n\n

https:\/\/yvcharron.com\/index.php\/fossil-fuel-power-plants\/<\/a><\/p>\n\n\n\n

This mode of operation is transferrable to a steam boiler burning carbonated fuels (including coals) discharging to the atmosphere a polluted gas containing carbon dioxide at a relatively high temperature. The higher the exhaust temperature, the higher is the pressure level reached by the compression \u2013 expansion loop.<\/p>\n\n\n\n

The present article presents a significantly different system where the carbon dioxide is capted upstream the combustion chamber. In that instance, the compression \u2013 expansion loop is operated from the turbine air compressor exit pressure level and not from the atmospheric pressure level. This gas process occurs internally <\/strong>(or more precisely at an intermediate position) to the gas turbine.<\/strong><\/p>\n\n\n\n

EXTERNAL and INTERMEDIATE treatments of the polluted air (mainly, carbon dioxide and NOx) present some similarities also relative advantages and disadvantages described below.<\/p>\n\n\n\n

To determine the applicability of this intermediate air process, it is important to look at the characteristics of the different types of gas turbines (mainly aero derivative and heavy duty gas turbines) and other cases of internal air process.<\/p>\n\n\n\n

More details concerning this presentation <\/strong>may be found in the PDF document<\/strong> below.<\/p>\n\n\n\n

\"Intermediate<\/a><\/figure><\/div>\n\n\n\n

2_Gas turbine types<\/strong><\/h2>\n\n\n\n

The mode of operation of gas turbines is presented in page \u201cPower plants \u2013 External CO2 removal<\/span>\u201d https:\/\/yvcharron.com\/index.php\/fossil-fuel-power-plants\/<\/a> and resumed below.<\/p>\n\n\n\n

There are two main types of gas turbines: the aero derivative and the heavy duty (or industrial). They differ mainly by their application, their performance and their mode of construction.<\/p>\n\n\n\n

As suggested by their name, aero derivative gas turbines<\/strong> are based on a central core engine derived from the aircraft industry (jet engine) discharging hot gases with a high momentum (in an aircraft, the backward engine thrust displaces forward the aircraft) towards a last turbine stage usually named Power turbine<\/strong> or Free turbine<\/strong>. These turbines operate with a relatively large thermal efficiency, of the order of 40%. As a result, less heat is rejected to the atmosphere due to an exhaust gas temperature usually lower than 500\u00b0C (an average of 450\u00b0C).<\/p>\n\n\n\n

Industrial gas turbines<\/strong> differ from aeronautical design in that frames, bearings and blading are of heavier construction<\/strong>. Their thermal efficiency is smaller (30 to 35 %). As a result more heat is rejected to the atmosphere due to an exhaust gas temperature often larger than 500\u00b0C (an average of 550\u00b0C).<\/p>\n\n\n\n

The relatively large compression pressure ratio of an aero derivative gas turbine <\/strong>(30 to 35) induces a relatively high temperature at the compressor exit <\/strong>(approaching 700 \u00b0C). In contrast, the lower pressure ratio of a heavy \/ industrial gas turbine (15 to 20) induces a lower temperature at the compressor exit (of the order of 500 \u00b0C\u00b0).<\/p>\n\n\n\n

The temperature and the pressure levels at the GT compressor exit are two important parameters for the design of CO2 removal at an intermediate position in a gas turbine<\/strong> as it will be seen in this article.<\/p>\n\n\n\n

More details concerning the different turbine types and some characteristics of an air compressor of a gas turbine <\/strong>may be found in the attached PDF (see above).<\/p>\n\n\n\n

3_Examples of gas turbine intermediate air process<\/strong><\/h2>\n\n\n\n

The normal air process in a gas turbine is as follows: ambient air is suctioned by a compressor, pushed towards a combustion chamber then released in an expander where the hot gas expansion provides sufficient energy to drive both the air compressor and an external load (an electric generator or a mechanical brake).<\/p>\n\n\n\n

It is meant here by external and intermediate air process<\/strong> (or treatment for CO2 removal) the following:<\/p>\n\n\n\n