1. Introduction - Firenze University Press
1. Introduction - Firenze University Press
1. Introduction - Firenze University Press
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Abstract:<br />
PROCEEDINGS OF ECOS 2012 - THE 25 TH INTERNATIONAL CONFERENCE ON<br />
EFFICIENCY, COST, OPTIMIZATION, SIMULATION AND ENVIRONMENTAL IMPACT OF ENERGY SYSTEMS<br />
JUNE 26-29, 2012, PERUGIA, ITALY<br />
Comparison of IGCC and CFB cogeneration<br />
plants equipped with CO2 removal<br />
Marcin Liszka a , Tomasz Malik b , Micha Budnik c , Andrzej Zibik d<br />
a Institute of Thermal Technology, Silesian <strong>University</strong> of Technology, 44-100 Gliwice, Konarskiego 22,<br />
Poland, marcin.liszka@polsl.pl,<br />
b Institute of Thermal Technology, Silesian <strong>University</strong> of Technology, 44-100 Gliwice, Konarskiego 22,<br />
Poland, tomasz.malik@polsl.pl, CA<br />
c Institute of Thermal Technology, Silesian <strong>University</strong> of Technology, 44-100 Gliwice, Konarskiego 22,<br />
Poland, michal.budnik@polsl.pl,<br />
d Institute of Thermal Technology, Silesian <strong>University</strong> of Technology, 44-100 Gliwice, Konarskiego 22,<br />
Poland, andrzej.ziebik@polsl.pl<br />
The introduction of CO2 removal processes into coal-fired power units causes usually generation of waste<br />
heat which is not possible to utilize within steam cycle. Normally, the waste heat is rejected to cooling water<br />
and then to the environment. As the temperature of waste heat carriers is usually moderately high (ca. 80 -<br />
100C), there is a potential possibility for using them in district heating systems. The main goal of the present<br />
paper is thus the energy and CO2 emission analysis of large-scale CHP plants equipped with CO2 removal<br />
and utilizing waste heat generated within the plant. Two case studies have been formulated. First of them is<br />
dealing with the CFB plant equipped with a tap-backpressure steam turbine and post-combustion chemical<br />
CO2 absorption. The steam necessary for CO2 solvent (MEA) regeneration is taken from the steam turbine<br />
exhaust, while district heat is produced mainly in CO2 dehumidifier and CO2 compression train. The second<br />
case is dealing with an IGCC equipped with the pre-combustion CO2 removal by physical absorption. The<br />
district heat is then produced using classical final flue gas cooler located in HRSG, syngas cooler, as well as,<br />
compression trains of ASU air, nitrogen and CO2 product. For both analyzed cases, the peak-load district<br />
heat production using steam turbine extraction is also possible. Both CFB and IGCC plants have been<br />
modelled on the Thermoflex software. The reference, CFB-based CHP plant without CO2 removal has also<br />
been modelled. The district heat production and district water parameters have been fixed for all analyzed<br />
cases to the same values. The energy utilization factor, exergy efficiency and electricity-to-heat ratio have<br />
been calculated for both plants as main assessment factors. The methodology of alternative electricity<br />
production (equivalent power unit) has been involved for calculation of CO2 emissions. The obtained results<br />
indicates, that IGCC plant has better thermodynamic indicators than CFB-based unit. Moreover, the CO2<br />
emission considering system interconnections within the electricity production network is negative for both<br />
the CFB and IGCC plants equipped with CCS. When comparing exergy efficiency, the highest value is<br />
achieved for the reference CFB plant (without CO2 capture). The decrease of exergy efficiency caused by<br />
CO2 capture and compression is ca. 8 percentage points, but in case of IGCC CHP plant the exergy<br />
efficiency plant is only 3 points lower than for the reference system.<br />
Keywords:<br />
IGCC, CFB, CHP, CCS, waste heat<br />
<strong>1.</strong> <strong>Introduction</strong><br />
The CO2 removal processes integrated with coal-fired power units cause significant drop of energy<br />
efficiency and economic profitability of the overall power generation process. The decrease of<br />
power generation efficiency is externalized usually by increased amount of waste heat rejected to<br />
the environment. The waste heat coming from the CO2 removal and compression installations is<br />
often of moderate temperature (ca. 80-100C), and therefore its utilization within the power cycle or<br />
for external purposes could be possible. On the other hand, the decrease of CO2 emission without<br />
its removal is also possible. The combined heat and power production (CHP) is a good example<br />
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