PART 7 - TOPIC 2 CONSEQUENCE MODELING USING ALOHA

Transcription

1 PART 7 - TOPIC 2 CONSEQUENCE MODELING USING ALOHA Dr. Arshad Ahmad arshad@utm.my 1

2 Software Commonly used for Risk Analysis Software SAFETI SFU CAFTAN ETRA HAZSEC. HAZTRAC. PHAST. WHAZAN EFFECTS. DAMAGE PC-FACTS. ASAP FMECA ANEX Application Onshore Risk Analysis. Offshore Risk Analysis. Fault Tree Analysis. Event Tree Analysis. HAZOP Study. HAZOP Recommendation Tracking. Consequence Analysis. Consequence Analysis. Consequence (Effects) Modeling. Consequence (Damage) Modeling. Failure & Accident Databank. Event Tree Analysis. Failure Mode Effects & Criticality Analysis. Life Time Analysis & Failure Estimation.

3 Software Commonly used for Risk Analysis Software ALOHA CLASS RISK CURVES RISKA T E&P FORUM FACTS OREDA FRED EAHAP Application Consequence Analysis Hazardous Area Risk & Classifications TNO Individual & Group Risk computations Risk Analysis model of Health & Safety Executives, UK Hydrocarbon Leak & Ignition Database. TNO Frequency Estimation Database DNV Frequency Estimation Database Consequence Analysis software of Shell, UK Consequence modeling software of Energy Analysts Inc. US)

4 What is CAMEO? CAMEO is computer software primarily used: For chemical emergency planning For chemical response; and For regulatory compliance The overall CAMEO system is a suite of three separate, integrated software applications: CAMEO (Computer aided management of emergency operation) MARPLOT (Mapping application for response and planning of local operational task) ALOHA (Areal locations of hazardous atmosphere) Developed by: EPA s Chemical Emergency Preparedness and Prevention Office NOAA s Hazardous Materials Response and Assessment Division

5 CAMEO Answers Questions What hazards are at this site? Where is the hazard located? What is the chemical? What specific hazard(s) does it present? How can the hazard be mitigated?

6 Toxic Release Inventory Cameo Module Relationships Chemicals in Inventory/ Transit Storage Locations Chemical Information Facilities Screening & Scenarios Incidents Routes Special Locations Contacts Census Data Resources

7 ALOHA

8 What is ALOHA Air hazard modeling program Predicts how quickly chemical will escape from a tank, puddle, gas pipeline etc Model how gas travel downwind (include neutrally buoyant and heavy gas dispersion) Model fire and explosion (pool, jet, flash, BLEVE, VCE) Produces threat zone estimate, showing area of hazards (toxicity, thermal radiation) Threat zones can me mapped into MARPLOT, Google maps, Google earth 8

9 Example of ALOHA s Output Threat Zones Concentration at a point 9

10 GIS Compatible Output 10

11 Fire and Explosion

12 Pool Fire 12

13 Pool Fire 13

14 Jet Fire 14

15 Jet Fire 15

16 BLEVE Fireball Model 16

17 BLEVE Fireball Model 17

18 Flash Fire & Vapor Cloud Explosion Model 18

19 Flash Fire & Vapor Cloud Explosion Model Vapor cloud explosion major assumptions: Uses Baker-Strehlow-Tang methodology Flammable mass (0.9LEL - UEL) Explosion efficiency Detonation 100% Deflagration 20% Ignition options Hard ~10 6 Joules Soft ~1 Joule 19

20 Flash Fire & Vapor Cloud Explosion Model Vapor cloud explosion major assumptions: (cont.) Congestion options High area blockage ratio > 40% Low area blockage ratio < 10% 20

21 Flash Fire & Vapor Cloud Explosion Model 21

22 Example

23 Example: Facility Siting Case Study 23

24 Example: Facility Siting Case Study Release through 3-inch relief valve leading to: Jet fire Flash fire Vapor cloud explosion Failure of storage vessel engulfed in flames leading to: BLEVE fireball 24

25 Facility Siting Case Study BLEVE & Fireball 25

26 Facility Siting Case Study Jet Fire Results 26

27 Facility Siting Case Study VCE Detonation 27

28 Facility Siting Case Study VCE Deflagration 28

29 Facility Siting Case Study Combined 29

30 ALOHA Scenario In a transportation accident at km 182 of Southbound North-South Expressway in Nilai, a 9000 Gallon tank truck carrying ammonia overturns and shears off a flange whose diameter is 4 inches. The size of the tank is 24 feet long and 8 feet in diameter. The tank contains liquid, which is stored at ambient temperature. The fill density of the tank is 75% by volume. The sheared-off flange creates a circular opening of about 3 inches in diameter, and it is located at 30% of the way to the top of the tank. At the time of the accident, the wind direction is NE (i.e. blowing from NE), the wind speed is 3 m/s, measured at 10 m height. The accident occurred on a highway near a small village. The weather is partly cloudy, 80% relative humidity, and the temperature is 32 degrees Celsius. 30

31 Mapping Aloha Threat Zones into Google Earth

32 Displaying Aloha Threat zones on Google Earth Step 1: Create any Threat Zone in ALOHA; for example you could enter the following criteria as an example: SITE DATA: Location: STILLWATER, OKLAHOMA Building Air Exchanges Per Hour: 0.93 (unsheltered single storied) Time: December 19, hours CST (using computer's clock) CHEMICAL DATA: Chemical Name: CHLORINE Molecular Weight: g/mol AEGL-1 (60 min): 0.5 ppm AEGL-2 (60 min): 2 ppm AEGL-3 (60 min): 20 ppm IDLH: 10 ppm Ambient Boiling Point: F Vapor Pressure at Ambient Temperature: greater than 1 atm Ambient Saturation Concentration: 1,000,000 ppm or 100.0% ATMOSPHERIC DATA: (MANUAL INPUT OF DATA) Wind: 10 miles/hour from n at 3 meters Ground Roughness: open country Cloud Cover: 5 tenths Air Temperature: 66 F Stability Class: D No Inversion Height Relative Humidity: 50% SOURCE STRENGTH: Direct Source: 200 pounds/min Source Height: 0 Release Duration: 10 minutes Release Rate: 200 pounds/min Total Amount Released: 2,000 pounds Note: This chemical may flash boil and/or result in two phase flow. 32

33 Displaying Aloha Threat zones on Google Earth Step 1: Select the Display / Threat Zone menu Step 3: Accept the Level of Concern values ALOHA should now display the Threat Zone graph 33

34 Displaying Aloha Threat zones on Google Earth Step 4: To display this graph on Google Earth, you MUST know the specific Latitude / Longitude of the release point. If you don t know the Lat / Long value, you can determine it by using MARPLOT, or Google Earth, a hand-held GPS unit, etc. For my example, I am using the following Lat / Long coordinates as the release point: N W Step 5: After you have determined the exact Lat / Long coordinates, return to ALOHA with the Threat Zone displayed Step 6: Select the File à Export Threat Zones menu 34

35 Displaying Aloha Threat zones on Google Earth Step 7: Choose PAS if exporting to ArcView using the ArcMap Import Tool or Choose KML if exporting to Google Earth 35

36 Displaying Aloha Threat zones on Google Earth Step 8: Enter the Lat / Long values Step 9: Select OK 36

37 Displaying Aloha Threat zones on Google Earth Step 10: Name the file and save to your computer desktop; in my example, I have named the file ALOHA Chlorine Threat Zone.kml Step 11: Save the file 37

38 Displaying Aloha Threat zones on Google Earth Step 12: Go to your computer desktop Step 13: Find the saved KML file and double-click on it This should launch Google Earth and automatically zoom-in and display the Threat Zone at the specified Lat / Long position. 38

39 GROUP PROJECT Carry out QRA on the scenario given Plot the individual risks on Google map/ Google earth Prepare a written report (20-30 pages) Prepare for oral presentation Oral presentation is expected in 3 weeks Written report shall be due in 4 weeks

40 End of Lecture 40