SUMMER COURSE ON EXERGY AND ITS APPLICATIONS THERMOECONOMIC ANALYSIS with SPECO METHOD

1. SUMMER COURSE ON EXERGY AND ITS APPLICATIONS THERMOECONOMIC ANALYSIS with SPECO METHOD C. Ozgur Colpan July 2-4, 2012 Osmaniye Korkut Ata Üniversitesi

2. OUTLINE • Review of Exergy Analysis • Engineering Economic Analysis • Introduction to Thermoeconomics • SPECO Method • Cost balance • F and P rules • Case Studies • Summary

3. REVIEW OF EXERGY ANALYSISDefinitions • Exergy is the maximum work that may be achieved by bringing a system into equilibrium with its environment • Exergy analysis is a method that uses the conservation of mass and conservation of energy principles together with the second law of thermodynamics for the analysis, design and improvement of energy systems EXERGY Kinetic Chemical Physical Potential

4. REVIEW OF EXERGY ANALYSIS Definitions (Cont’d) • Equilibrium • Thermal: T=To • Mechanical: P=Po • Chemical: μ=μo (T,P,μ)  (To, Po, μ)  (To, Po, μo) Restricted dead state Dead state Thermomechanical exergy Chemical exergy

5. REVIEW OF EXERGY ANALYSIS Physical and Chemical Exergy WATER IDEAL GAS MIXTURE HYDROCARBON FUEL (CaHb)

6. REVIEW OF EXERGY ANALYSIS Exergy Destruction and Exergy Loss Exergy destruction is due to irreversibilities within a system • Friction • Expansion • Mixing • Chemical Reaction • Heat transfer through a finite temperature diff. Internal Irreversibilities External Irreversibilities Exergy is lost when the energy associated with a material or energy stream is rejected to the environment

7. REVIEW OF EXERGY ANALYSISExergy Balance and Exergetic Efficiency The steady state form of control volume exergy balance Exergetic efficiency Overall exergetic efficiency:

8. ENGINEERING ECONOMIC ANALYSISSteps The steps that should be applied in an economic analysis: • Estimation of purchased equipment costs • Year-by-year analysis Carrying Charges Total Revenue Requirement Expenses

9. ENGINEERING ECONOMIC ANALYSISSteps (Cont’d) • Calculation of levelized costs: If money transactions occur at the end of each year within the plant economic life Where If cost escalation is applied to an expenditure With

10. ENGINEERING ECONOMIC ANALYSISSteps (Cont’d) Cost rate associated with capital and O&M costs Levelized cost rate of fuel Levelized cost rate of raw water

11. INTRODUCTION TO THERMOECONOMIC ANALYSIS • The objective of a thermoeconomic analysis might be: • To calculate separately the cost of each product generated by a system having more than one product • To understand the cost formation process and the flow of costs in the system • Thermoeconomic optimization = exergy-aided costminimization • To optimize specific variables in a single component • To optimize the overall system

12. THERMOECONOMIC ANALYSISSPECO Method Three steps • Identification of exergy streams • Definition of fuel and product • Writing the cost balances and auxiliary equations The steady-state form of control volume cost balance is

13. THERMOECONOMIC ANALYSISSPECO Method (Cont’d) The F rule Total cost associated with the removal of exergy from an exergy stream in a component = Cost at which the removed exergy was supplied to the same stream in upstream components. The P rule Each exergy unit is supplied to any stream associated with the product of a component at the same average cost cp. This cost is calculated from the cost balance and the equations obtained by applying the F rule

14. THERMOECONOMIC ANALYSISSPECO Method (Cont’d) Exergy Analysis Calculate costs of exiting streams using cost equations Costs are known for all entering streams Exergy rates Plant component Cost equations Levelized capital investment, and operating and maintenance costs EconomicAnalysis

15. CASE STUDIESCase-1 17 Dump Condenser C 18 8 9 12 11 10 7 13 Desuperheater 6 Condensate Pump 20 21 Steam Turbine Deaerator C 14 D 4 B 22 E HP Steam Drum Stack 15 LP Steam Drum 5 D HRSG 16 19 Gas Turbine System 1 3 BFW Pump 17 2 A

16. CASE STUDIESCase-2 15 C 16 Condenser 6 8 10 9 7 11 Desuperheater Condensate Pump 18 19 Steam Turbine Deaerator C 12 D 4 B 20 E HP Steam Drum Stack 13 5 LP Steam Drum D 14 17 HRSG Gas Turbine System 1 3 BFW Pump 15 2 A

17. CASE STUDIESCase-3 20 10 9 C 6 Desuperheater 7 12 11 13 Condenser Condensate Pump 8 14 Steam Turbine C 16 Deaerator 22 23 D 4 17 B 24 Stack E IP Steam Drum HP Steam Drum F 5 15 LP Steam Drum D HP BFW Pump 18 HRSG Gas Turbine System 1 3 E IP BFW Pump 21 2 A 19 20

18. CASE STUDIESInput Data and Assumptions • Assumptions • Heat loss from HRSG is assumed to be 2% of heat absorbed • Pressure drop on the gas side of HRSGis 5%, on the water side isneglected • Blow down requirements are not taken into account • All the steam export from the system returns as condensate

19. CASE STUDIES Economic Analysis

20. CASE STUDIES Thermoeconomic Analysis Cost flow rate at each state is found applying cost balances as well as F and P rules to each component where applicable. Example: Steam turbine (including electric generator) for Case - 2

21. CASE STUDIES Thermoeconomic Analysis (Cont’d) • Cost of other plant equipment and the monetary loss • associated with exergy loss should be apportioned between • products. • Example: Case-2

22. CASE STUDIES Results

23. CASE STUDIES Results (Cont’d)

24. CASE STUDIES Results (Cont’d)

25. SUMMARY • Exergy analysis gives more insights than conventional energy analysis. • Economic analysis has three steps: Estimation of purchased equipment costs, year-by-year analysis, and calculation of levelized costs • Results of economic analysis and exergy analyses are used as input in thermoeconomic analysis. • In SPECO method, solving the cost balance and the auxiliary equations originating from F and P rules, cost flow rates of each state and cost of the products are found. • The case studies show that cogeneration system with extraction-condensing steam turbine are thermo-economically more feasible.