Exergy-based analysis of conventional coal-fired power plant retrofitted with oxy-fuel and post-combustion CO₂ capture systems

Abstract

Capturing and sequestering CO 2 from coal-fired power plant is being proposed as one of the key solutions for stabilizing greenhouse gas concentration in the atmosphere. Recently, absorbing system and oxy-fuel combustion technology have been proposed as attractive options for capturing CO 2 in power generation systems utilizing hydrocarbon fuels. This study is focused on energy and exergy analysis to compare the oxy-fuel combustion and absorbing system from different points of view to make a better insight into the cases from different aspects. The results show that the post-combustion and oxy-fuel CO 2 capture systems result in 10.5% and 9.1% decrease in exergy efficiency of the retrofitted plants, respectively, compared with the conventional coal-fired power plant (base case). Additionally, boiler is the major exergy destruction source in all investigated plants. Also, air separation unit and CO 2 capture and storage system have the largest amount of exergy destruction among the additional components of retrofitted plant with oxy-fuel combustion and post-combustion CO 2 capture systems, respectively.

Opportunities for Decarbonizing Existing U.S. Coal-Fired Power Plants via CO2 Capture, Utilization and Storage

“…Multiple EGUs within a single plant might have different attributes. Given the large cost and high energy penalty associated with amine-based CCS systems, , previous studies indicate that retrofitting amine-based CCS to existing coal-fired plants would lead to substantial increases in the cost of electricity generation (COE). , The lifetime of the CO 2 capture facilities can be limited by the remaining life of existing plants. These factors are often viewed as critical barriers to CCS deployment .…”

“…However, for existing coal-fired EGUs that have been fully or substantially amortized, the COE of an EGU retrofitted with CCS can be comparable to or lower than that of a new plant . Relatively large, young, high-efficiency coal-fired EGUs equipped with flue-gas desulfurization (FGD) and selective catalytic reduction (SCR) systems are potentially suitable for CCS retrofit applications. , Auxiliary power systems can be used to maintain the electricity output of retrofitted plants. ,, Thus, the feasibility of a CCS retrofit should be evaluated on a site-specific basis because the retrofit cost varies significantly with unit characteristics. , As a revenue-enhancing opportunity, selling the captured CO 2 product for enhanced oil recovery can lower the added cost for CCS …”

“…7,8 Auxiliary power systems can be used to maintain the electricity output of retrofitted plants. 4,9,10 Thus, the feasibility of a CCS retrofit should be evaluated on a site-specific basis because the retrofit cost varies significantly with unit characteristics. 5,11 As a revenue-enhancing opportunity, selling the captured CO 2 product for enhanced oil recovery can lower the added cost for CCS.…”

Experimental Study on NOx Reduction in Oxy-fuel Combustion Using Synthetic Coals with Pyridinic or Pyrrolic Nitrogen

“…Coal combustion in utility power plants is one of the largest contributors to the anthropogenic emission of carbon dioxide (CO 2 ), which also brings about many environmental pollution problems, such as nitrogen oxides (NO x ), sulfur oxides (SO x ), particulate matters (PMs), mercury (Hg), and so on [1][2][3][4][5][6][7]. Several approaches can be utilized to reduce CO 2 emissions originating from coal-fired power plants, including the improvement of thermal efficiency, the replacement of coal with low-carbon fuels, the introduction of combined cycles, and the capture and storage of CO 2 (CCS) [8][9][10][11][12]. Oxy-fuel combustion can not only capture CO 2 in the large-scale but also obviously lower NO x emission in coal-fired power plants [13][14][15][16][17][18][19][20], which is a potential clean coal technology in the near future and is drawing an ever-increasing attention nowadays.…”

Dynamic Exergy Method for Evaluating the Control and Operation of Oxy-Combustion Boiler Island Systems

“…Oxy-combustion, a complex energy conversion system, is considered as a promising CO 2 capture option to reduce CO 2 emissions from power plants. It can be retrofitted from a conventional power plant with minor modifications , even though additional energy penalties , and economic costs , are required. To realize its commercial demonstration, great efforts have been made to design a suitable control system and obtain dynamic behavior. , Nevertheless, it is still required to seek new methodology to reduce energy consumption.…”