1. of coil pipe exhaust gas boilers
Design program
of coil pipe exhaust gas boilers

2. Project established in 2006 between Garioni Naval and Politecnico di Milano
Common target:
Formation of a graduated person with the best available knowledge in the field of thermal design of fired and exhaust gas steam boilers, thermal oil heaters, also using biological fuels
Access to best available literature in terms of exchange coefficients and rates
Preparation of more accurate calculation programs capable to consider different lay-outs and geometries from the standard, starting from exhaust gas and then also considering fired equipments
Verification of Garioni Naval design programs, with the possibility of improvements of nominal capacity and potential cost savings

3. Schematic view of boiler longitudinal section

4. Longitudinal half-section in case of three coils

5. Longitudinal half-section in case of six coils

6. Numbering of exhaust gas paths

7. Numbering of coils

8. Input file data

9. HOT END COLD END Exhaust gas in parallel (Feeding pattern: P) 1 2 3 45 6 7
HOT END is the boiler side with inlet hot gases, COLD END is the boiler side with outlet cold gases.

10. COLD END
Exhaust gases in series from the inside (Feeding pattern: I) 1 2 3
HOT END

11. Exhaus gases in series from the outside (Feeding pattern: E)
HOT END 1 2 3
COLD END

12. COLD END HOT END Coils in parallel from the Hot End
Explanation of this information in the input data file: 1 2 3 4 5 6

13. COLD END HOT END Coils in parallel from the Hot End
Explanation of this information in the input data file: 1 2 3 4 5 6

14. Coils in parallel from the Cold End
HOT END
COLD END
Explanation of this information in the input data file: 1 2 4 5 6 3

15. HOT END COLD END Coils in series from the outside, continuously 1
Explanation of this information in the input data file: 2

16. HOT END
COLD END
Explanation of this information in the input data file: 1 2

17. COLD END HOT END Hybrid feeding of coils, mix of series and parallel 12 3
Explanation of this information in the input data file: 4 5 6

18. Coils can be divided in several sections due to geometric discontinuities
COLD END
HOT END
SECTION 1
SECTION 2
SECTION 3
SECTION 4
SECTION 5
Potential geometric discontinuities:
Changes in pipe diameter
Changes in pipe thickness
Start and stop of coils in different positions
Sections are numbered from Hot End.
Maximum number of sections is five.

19. Starting point of any section is considered from the hot end
COLD END
HOT END
SECTION 1
SECTION 2
SECTION 3
SECTION 4
SECTION 5

20. Comparison with standard Garioni Naval exhaust gas calculation programs:
GARIONI POLITECNICO DIFFERENCE
TH/EG kW 514 kW %
TH/EG kW 499 kW %
TH/EG kW 522 kW %
TH/EG kW 524 kW %
TH/EG kW 580 kW %
TH/EG kW 580 kW %
TH/EG kW 765 kW %
TH/EG kW 997 kW %
TH/EG kW 559 kW %
TH/EG kW 1522 kW %

21. RESULTS
Reliability of Garioni Naval exhaust gas calculation programs, with average safey margin in the design of about 8%
Possibility of more accurate analysis
Better fitness for purpose of designed equipment, with possibility to better match with customers request in terms of capacity and size of equipment
Reduction of unnecessary costs due to certain, guaranteed and certified safety margins