Characteristic evaluation of a CO2-capturing repowering system based on oxy-fuel combustion and exergetic flow analyses for improving efficiency

Abstract

SUMMARYA CO 2 -capturing H 2 O turbine power generation system based on oxy-fuel combustion method is proposed to decrease CO 2 emission from an existing thermal power generation system (TPGS) by utilizing steam produced in the TPGS. A high efficient combined cycle power generation system (CCPS) with reheat cycle is adopted as an example of existing TPGSs into which the proposed system is retrofitted. First, power generation characteristics of the proposed CO 2 -capturing system, which requires no modification of the CCPS itself, are estimated. It is shown through simulation study that the proposed system can reduce 26.8% of CO 2 emission with an efficiency decrease by 1.20% and an increase power output by 23.2%, compared with the original CCPS. Second, in order to improve power generation characteristics and CO 2 reduction effect of the proposed system, modifications of the proposed system are investigated based on exergetic flow analyses, and revised systems are proposed based on the obtained results. Finally, it is shown that a revised proposed system, which has the same turbine inlet temperature as the CCPS, can increase power output by 33.6%, and reduce 32.5% of CO 2 emission with exergetic efficiency decrease by 1.58%, compared with the original CCPS.

Characteristics and Economics Evaluation of an H2O Turbine Reheat Cycle Power Generation System Based on Oxy-Combustion Method for Utilizing Exhaust Gas of Large Scale MCFC

“…Since the main compositions of the combustion gas become only H 2 O and CO 2 , the separation of CO 2 gas from H 2 O liquid (condensate) can be physically and automatically performed at the outlet of the condenser at the bottoming cycle in the proposed system [3][4][5][6][7][8][9][10].…”

“…This feature is fundamentally different from a system that captures CO 2 from flue gas by using a chemical absorbent, in which power output inevitably decreases and its powerselling income decreases. The proposed system is based on GT technologies, and as such it could be easily applied to small scale [1] and medium scale PGSs [9], as well as to large scale PGSs [10]. The fuel is burned by using O 2 and therefore the combustion reaction takes place in the combustor without N 2 gas.…”

“…The fuel is burned by using O 2 and therefore the combustion reaction takes place in the combustor without N 2 gas. Hence, no thermal NO x is produced in the proposed system when carbon hydride fuel is used [3][4][5][6][7][8][9][10]. Table 2.…”

“…Tables 2 and 3 show major exogenous variables and parameters used for estimating the characteristics of the STPS and the HTPS, and the values used for characteristics simulation, respectively. The values in Tables 2 and 3 are based on previous analyses performed by the authors on a variety of power generation systems, and are considered to be realizable by applying present technologies [3][4][5][6][7][8][9][10]. Table 4.…”

Process simulation of oxy-fuel combustion for a 300MW pulverized coal-fired power plant using Aspen Plus

“…Zheng and Furimsky [14] considered that the SO x emissions are governed by O 2 concentration in O 2 + CO 2 mixture. Pak et al [15], Li et al [16] and Salkuyeh and Mofarahi [17] studied the CO 2 emission, capture and storage for the oxy-fuel combustion.…”