1. 1 Selecting an ERS Design Basis SACHE Workshop Gary Van Sciver September 20, 2005

2. 2 Emergency Relief System

3. 3 Vessel Overpressure

4. 4 1999 Allentown, PA 5 fatalities high concentration and temperature of hydroxylamine Concept Sciences

5. 5 Hazardous Release

6. 6 Phillips Pasedena, Texas 1989 23 fatalities Vapor cloud explosion of ethylene and other gases Explosion occurred ~ 2 minutes after release started

7. 7 Bhopal Union Carbide 1984 2,500 fatalities large ERS release of methyl isocyanate

8. 8 Venting Policy: ERS must protect on-site people AND off-site people

9. 9 Balance:

10. 10 What is a Design Basis?

11. 11 Design Basis: Simple way to express system capacity

12. 12 Failure Scenario

13. 13 Fire Scenario

14. 14 Runaway Scenario

15. 15 Failure Scenario: Series of events leading to high vessel pressure.

16. 16 How high?

17. 17 Codes require that the maximum pressure not exceed the vessel design pressure

18. 18 Design Basis: Most severe failure scenario which complies with the Codes.

19. 19 How do we do it?

20. 20 Procedure : 1. Identification 2. Selection

21. 21 1. Identification (of all important failure scenarios)

22. 22 ideas

23. 23 Non-reactive Systems

24. 24 Product Tank Example

25. 25 Non-Reactive Checklist 1.Heat addition a. Normal breathing b. Fire c. Excessive heating 2.Pressurized liquid addition 3.Pressurized gas addition

26. 26 1a. Normal breathing (atmospheric temperature and pressure changes)

27. 27 1b. Fire Exposure

28. 28 1c. Excessive heating (steam valve failures, coil leaks)

29. 29 2. Pressurized liquid addition (usually accompanied by some flashing, especially if hot)

30. 30 3. Pressurized gas addition (line blowing, pressure transfers, pads or purges)

31. 31 Reactive Systems

32. 32 Is there an exothermic or gas-generating reaction?

33. 33 Generic Emulsion Compatibility Matrix

34. 34 Reactive Chemistry Worksheet developed by EPA and NOAA (National Oceanic and Atmospheric Administration) http://response.restoration.noaa.gov/chemaids/react.html

35. 35

36. 36 OSHA Chemical Reactivity Website http://www.osha.gov/dep/reactivechemicals/

37. 37 Bretherick ’ s Handbook of Reactive Chemical Hazards

38. 38 Lab Experiments

39. 39 Emulsion Reactor Example

40. 40 Normal Reaction Checklist 1. Inadequate cooling 2. Inadequate heat sink 3. Excessive reactant 4. Poor reactivity

41. 41 1. Inadequate cooling

42. 42 2. Inadequate heat sink

43. 43 3. Excessive reactant (continuous)

44. 44 3. Excessive Reactant (batch)

45. 45 4. Poor reactivity

46. 46 Abnormal Reaction Checklist 1.Too hot 2.Wrong composition

47. 47 1. Too hot

48. 48 2. Wrong composition

49. 49 System ________________

50. 50 2. Selection (of a design basis from the important failure scenarios)

51. 51 Selection Approaches: A. Codes/Standards B. Tradition/Analogy C. Risk

52. 52 List scenarios by ERS size

53. 53 Example Scenario List: 1.Liquid filling 2.Fire case 3.Half charge runaway 4.Full charge runaway 5.Full charge runaway without water heel

54. 54 A. Codes/ Standards

55. 55 NFPA 30 requires ERS protection against fire exposure

56. 56 B. Tradition/ Analogy

57. 57 Traditional Designs Non-reactive: Fire Case Reactive: Full-charge Runaway

58. 58 Traditional Design

59. 59 ERS Database

60. 60 C. Risk

61. 61 Probability of consequences

62. 62 Consequences

63. 63 Probability (of high vessel pressure)

64. 64 Plot Plan

65. 65 Risk Contours

66. 66 On-site Risk - once per 40,000 years Off-site Risk - once per 100,000 years Rohm and Haas Risk Criteria