Evaluation of CO2-capturing Power Generation Systems Utilizing Waste Heat from Ironworks.

Abstract

Two kinds of CO 2 -capturing power generation systems with and without regenerator are proposed which utilize saturated steam produced by making use of waste heat from ironworks, and their thermodynamic and economical characteristics were investigated. As an example of saturated steam, temperature and quantity was assumed to be 200°C and 10 t/h, respectively, by considering use of waste heat from a kiln at a pellet factory in an ironworks. Fundamental characteristics of the two proposed systems are estimated through computer simulation, such as power generation efficiency, energy saving characteristics, amount of CO 2 reduction, and economics. It was shown that the best system is attained for the proposed system without the regenerator when its turbine inlet temperature is set at 350°C. At this condition, the system was estimated to be economically feasible and to have following characteristics: repowering power generation efficiency 97.7 %, annual amount of saved energy 83.3 TJ, annual amount of CO 2 reduction 1 738 t-C, unit cost of generated power 6.42 yen/kWh, annual gross profit 25.4 million yen, and depreciation year 5.70. The proposed system could be adopted in many other waste heat emitting factories owing to its large CO 2 reduction characteristics and its economical profitability.

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

“…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.…”

“…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.…”

“…Unit power cost, depreciation year, benefit-cost ratio (BCR) and internal income rate of return (IRR), which indicates the average return rate of the invested capital, were adopted in the present research. Table 5 shows the values assumed for performing economic evaluation [3][4][5][6][7][8][9]; for simplicity of conversion, Japanese yen was converted into US dollar at a rate of 100 yen = 1 US $. Regenerator and condenser costs are taken into consideration as an additional facility cost for the HTPS, since these units do not exist in the conventional GT PGSs [1].…”

“…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].…”

Comprehensive evaluation of a CO2-capturing high-efficiency power generation system for utilizing waste heat from factories

“…This deteriorates the efficiency of the CO 2 -capturing system and its economics. To alleviate these shortcomings, one of the authors has proposed power generation systems (PGSs) based on oxy-combustion methods, where solar thermal energy or waste heat from factories is used [12][13][14][15][16][17]. A defect of these systems is that system location is limited to sites where a large quantity of solar thermal energy or waste heat with high quality is available.…”