Firetube Boiler Design, Construction & Engineering. Presented by Steve Connor July 29, 2015

Transcription

1 Firetube Boiler Design, Construction & Engineering Presented by Steve Connor July 29, 2015

2 What We Are Covering Today Brief on FT boiler evolution Major FT components Engineering & Summary Advancing Firetube Boiler Design Construction The Burner Dryback vs Wetback 2

3 Boiler Evolution Steam Locomotives NOTE: These firetube boilers could weigh up to 200,000lbs and reach speeds of 100mph 3

4 Boiler Evolution Steam Locomotive Cut-A-Way Stack Steam dome Convection tubes Tube sheet Water line Furnace NOTE: These boilers were an integral part in leading the way in the industrial revolution starting in the 1860 s. 4

5 Boiler Evolution Titanic Titanic Boiler Room NOTE: The Titanic was powered by 29 firetube boilers that contained 159 furnaces which were fired with 825 tons of coal per day. 5

6 Titanic s Steam Engines 4 Cycle Steam Engines Discovered 13,000 feet deep 2.5 miles down 6

7 Scotch Marine Boiler With Single or Multiple Furnaces 7

8 Firebox Boiler Locomotive Firebox Steam drum Stack convection Furnace Convection section Furnace NOTE: The Firebox boiler is only for low pressure steam and hot water. 8

9 Major Components Stack Pressure vessel Burner Controls 9

10 Single Package A Standard For Firetube Construction Was Created 10

11 Typical Industries Served Refinery & Petro-Chemical Universities/Colleges/Schools Government buildings Hospitals Hotels and Conference Centers Chemical/Pharmaceutical Automotive Food & Beverage Textiles Corrugated container Pulp & paper Building supplies Ethanol & Bio-Diesel Aerospace & Military 11

12 Construction Integral Gun 12

13 Construction Starts with flat plate Shell openings are cut in 13

14 Construction Shell is rolled into form 14

15 Construction Seams are welded; longitudinal & circumferential X-Rayed and witnessed Tube sheets cut and drilled Tube sheet cutting/drilling Shell welding 15

16 Tube Sheets Installed First tacked Full penetration weld; Down hand position Tack weld Full penetration weld 16

17 Boiler Fittings Are Installed Outlet & return connections Safety valve connection(s) Vent connection Surface blow-off connection Feed water connection Bottom blowdown connections Water level control connections Stay braces for high pressure 17

18 Furnace Fabrication & Install Fabrication Install 18

19 Stress Relieving After all pressure vessel welding is completed the entire assembly is stress 1100 deg. F. 19

20 Burner & Trim Prepared Trim assembled Burner components affixed Gas train Feed water piping Integral burner 20

21 Tubes Fabricated Roll Stock Rolling & Welding 21

22 Tubes Banded and Ready For Install 22

23 Tube Install Rolled and Welded Rolled and Beaded Rolled and Flared 23

24 Tube Attachment Rolled and Beaded Tube Rolled and Flared Tube Rolled and Welded Tube Tube End Cooling Tube End Cooling Tube End Cooling 24 24

25 Hydrostatic Testing 1 1/2 times the maximum allowable working pressure 25 25

26 Boiler Construction Insulation & lagging Throat & liner installation Front & rear door hanging Burner installation Final assembly & trim Test fire 26

27 Final Painting & Shipping 27

28 Horizontal Firetube Boilers The Dryback Baffles Tubesheet 4 3 Two (2) Tubesheets Refractory Filled Door

29 Horizontal Firetube Boiler The Wetback Three (3)Tubesheets Three Tubesheets Difficult access, 2 nd pass Water Leg Rear access plug 29

30 Size & Pressure Ranges HP Design pressures to 350# Wetback design used above HP 30

31 31 The Burner

32 Firetube Burner Types Gun Integral 32

33 Burner Types Wind box Diffuser Blast tube Blower/fan Burner Ass y Air inlet Integral burner Gun burner 33

34 Types of Firing High-low-Off Modulating Turndown: 4:1 or 10:1 34

35 35 Fuels

36 Maximize Combustion Control Single Point Parallel Positioning Fuel Air FGR 36

37 Flue Gas Recirculation Emission Reduction FGR Integral burner Gun burner 37

38 Efficiency Range based on boiler capacity, Fuel, Firing rate and Operating Pressure/Temperature: 81 87% NOTE: FGR may impact turndown, Reducing efficiency. 38

39 The Engineering Behind the Design 39

40 40 Established in 1880

41 Safety Becoming a Key Issue The Sultana Boiler Explosion Kills 1238 in April 27, 1865 Commissioned Jan Boiler repaired a few days before the explosion. Events like this lead to safety regulations; stringent codes 41

42 Safety Becoming a Key Issue Steam Locomotive Explosions..Devastating 42

43 ASME Code (American Society of Mechanical Engineering) Section I High pressure - Steam boilers above 15 psi. Hot water boilers above 160 psi (hydrostatic pressure) and/or F outlet temperature Section IV Low pressure - Steam boilers less than 15 psi. Hot water boilers less than 160 psi and/or 250 F. outlet temperature 43

44 Steam Nozzle Sizing & Velocity Surface velocity: 10 /sec. Nozzle: 5000 /min. Steam header valve Steam nozzle Water Surface 44

45 Radiant & Convective Heat Transfer Radiant Furnace Convection heat transfer 45

46 Furnace Emissivity & Heat Release Greater temperature difference by the power of 4! Stefan s Law M = T 4 BTU/Ft3 Radiant 46

47 Burner and Furnace Matching 47

48 Engineering Analysis Plain Furnace Corrugated Furnace No difference in efficiency, durability or life expectancy 48

49 Heating Surface Convective Reynolds number:. Relation of viscous to inertia forces. Velocity = square root of temperature Heat Transfer Coefficient:. Proportionality between heat flow & Delta T Radiant 49

50 Convective Heat Transfer Plain Tubes Extended Surface Tubes 50

51 Convective Heat Transfer Typical Boiler Tube Boundary layer 51

52 Extended Tube Surface INCREASED INERTIA FORCES = INCREASED HEAT TRANSFER No Boundary layer Spiral tubes 52

53 Reducing Weight and Footprint NOTE: These are attractive features to architects designing new boiler rooms when faced with budget restraints. Typical: 30% less weight 15% less floor space Reduced fan motor horsepower Same or better efficiency, durability and life Optimum furnace Improve convection heat transfer 2 pass 53

54 Designing Boilers in the 21 st Century Is boiler R&D like it was in the past? 54

55 Computation Fluid Dynamics & Finite Element Analysis CFD Modeling FEA Proving 55

56 56 Structural Verification

57 Tensile Strength Metal Stresses Tube Sheets Metal Deformation Tubes & Ligaments Furnace 57

58 Summary The firetube boiler is a versatile package suitable for a plethora of applications including heating and process Typical size range is HP Pressures to 350# Construction follows ASME code Sections I & IV and includes close 3 rd party inspections There are both dryback & wetback horizontal firetubes with each having advantages and disadvantages The fuel firing capability of these boilers is extensive including bio-fuels. The boiler is getting smaller in size and weight without compromising efficiency, durability and life span. The engineering is complex, but present day advancements in computer technology has accelerated and improved the process 58

59 Contact Us David Brick Firetube Product Manager cleaverbrooks.com 59