LNG Release Alert Test

Transcription

1 2016 LNG Release Alert Test Target area proposed HaminaKotka LNG terminal Finnish Environment Institute January 2016 Helsinki Jorma Rytkönen

2 Acknowledgement This report describes briefly the actions taken during the alert exercise conducted by the Finnish Environment Institute (SYKE). The exercise scenario tested was a LNG outflow case, where assistance was especially requested from EMSA s MARICE service, duty officer of the Finnish Meteorological Institute (FMI) and the Finnish Institute of Occupational Health (FIOH). The author of this report would like to thank these organizations for the valuable assistance received in a very short notice during the alert mode. The data received was seen valuable and had a very significant role when considering response activities and considering necessary rescue actions in the case of the major chemical spill. 1

3 Executive Summary New LNG terminals are currently under construction and planning in Finland. The same tendency is also going in the whole Baltic Sea area. New terminals will also mean increased number of LNG carriers visiting terminals, LNG bunkering ships and finally increasing number of ships having dual fuel engine systems onboard for LNG or low sulfur diesel/bio oil. Authorities are also facing new challenges when evaluating the safety issues related to the maritime transport: in the distress situation, i.e. when collided or grounded or fire onboard do the existence of LNG onboard mean certain additional measures to be taken into account when conducting rescue activities or performing measures for pollution prevention. This report describes briefly the alert exercise arranged by Finnish Environment Institute (SYKE). The exercise scenario selected consisted of the LNG release from the coastal LNG carrier: ship got a black out situation and hit the pier with too fast speed. A puncture for the tank was formed and the LNG gas started to leak out to the sea forming a pool and starting to evaporate. Alert measures conducted assistance requests sent to EMSA s MARICE service, Finnish Meteorological Institute and Finnish Institute of Occupational Health to evaluate the gas plume drift and to get instructions for emergency personnel against the LNG leakage. All basic data requested was received in less than 2.5 h including estimations for toxic and flammable zones and proposed protective measures related to rescue actions. Main results and brief discussion on the results are shown in this exercise report. 2

4 Contents Acknowledgement... 1 Executive Summary... 2 Contents... 3 Exercise Scenario... 4 Actions taken Alert log... 6 Discussions... 7 Lessons Learned Conclusions References List of Appendices

5 Exercise Scenario In order to illustrate possible danger of the possible LNG outflow a scenario was formed where LNG coastal carrier will berth with too heavy speed and hit existing LPG pier of the HaminaKotka s terminal in Finland. As a result one of the three LNG caissons, each m 3, will get a rupture and the instant LNG gas outflow will start. The rupture size is close to 1 m 2 close to the water line. Storage tanks temperature is -163 C, pressure close to 0,7 bar. The rupture is above the waterline in the mid-section of the ship. During the accident the south-western wind speed is 12 m/s, significant wave height close to the pier 0.3 m and the prevailing temperature close to +1 o C., Figure 1. The rupture size of the scenario, roughly 1 m2, corresponds well the analyses made in (Vidmar et al 2011) where average rupture size by a set of scenarios have been analysed: 250 mm Maximum possible rupture size caused by grounding 750 mm Maximum possible rupture size caused by collision 1500 mm Maximum possible rupture size caused by terrorist attack 7,000 m 3 /h Maximum possible leakage rate for 10 min 10,000 m 3 /h Maximum possible leakage rate caused by sabotage for 60 min. Figure1. Exercise area. The virtual damage site has been marked by letter. Additional info is given in the right hand corned of the figure. 4

6 The hazard associated with LNG is mainly in its potential to cause severe fires resulting in heat radiation. If a large quantity of LNG is spilled into a pool, the cloud that is formed as it evaporates is a mixture of natural gas, water vapour, and air. Initially the cloud is heavier than air (due to its low storage temperature) and remains close to the ground. The buoyancy moves the natural gas upward at a gas temperature of around 170 K (-103 o C). The major influences on natural gas diffusion are environmental conditions. The cloud moves in the direction of the wind and the wind causes the cloud to mix with more air. If the concentration of gas in the air is between 5% and 15% it is flammable and burns if it contacts any ignition source. A concentration of gas smaller than 5% will not ignite and if the concentration is over 15% the air becomes saturated. The explosion of natural gas is not possible in open spaces because the low velocity of flame spread, around 0.4 m/s, is not enough to produce a pressure wave (Vidmar et al 2011). The scenario having the character of the major LNG release was selected to get some confirmation against proposed safety zones around the proposed terminal. Another significant argument was to check the actions related to the local emergency plan, and especially all possible precautionary actions to avoid fire an/or explosions to take place. Terminals where LNG bunkering could be carried out shall have a local emergency plan. Emergency plans should include at least the procedures and responsibilities to handle the following possible scenarios: - Release of LNG and NG, Fire and explosion during Ship to Ship LNG bunkering of seagoing and inland vessels. - Release of LNG and NG, Fire and explosion due to collision with bunker vessels or gasfuelled ships. - Release of LNG and NG, Fire and explosion during Terminal to Ship LNG bunkering of seagoing and inland vessels. - Release of LNG and NG, Fire and explosion during the Truck to ship bunkering of seagoing and inland vessels (GL. 2013). Thus the scenario created here will form some baseline ideas for firefighting service, bunker facilities and surrounding infrastructure. 5

7 Actions taken Alert log The exercise was started at 1:30pm local time, and terminated the same afternoon at 4:00pm. The following log of actions can be listed: - 1:32pm Alert made by SYKE was sent to MARICE by , after the service was contacted by phone for confirmation. - 1:34pm Duty Officer of the FMI was alerted by SYKE to evaluate the gas plume drifting - 1:54pm Notification receiving the Request was sent by MARICE. - 2:02pm SYKE alerted FIOH and asked occupational health instructions. - 2:29pm MARICE delivered FDS cameo data sheet on the LNG properties with baseline reactivity alert notes. - 2:37pm additional information was sent to FIOH by SYKE - 2:47pm FMI sent their first estimation on the possible gas plume drift using hydrogen sulphide (HS) as a substrate (no methane modelled in their system). Additionally a table describing the drifting time versus distance and the ppm distribution from the origin, was attached. No estimation of the vertical ppm profile was made, however. - 3:16pm MARICE service delivered their estimation of the gas plume drifting using ALOHA model. Instead of LNG propane gas was used for modelling. AEGLs areas, as defined in discussions chapter, represent threshold exposure limits for the general public, pm SYKE comments the Aloha results for MARICE: propane seems to overestimate safety zones? - 3:24pm FIOH sends TOKEVA instructions (T2c) for LNG and OVA instructions for methane (suits for LNG) how to act in emergency situation pm MARICE run Aloha once more with lower volumes (3500 m 3 above and 500 m 3 below. Logically, the flammable area becomes smaller. - 4:02pm SYKE announced the exercise over and sent notifications to the participating bodies. 6

8 Discussions Exercise started at 1:30 by alerting the relevant bodies identified already above. First valuable response given by MARICE service was received at 2:29pm in the form of Cameo data sheet on the LNG properties (Appendix 1/cover page). The message contained also the following instructions: a.) for the firefighting measures: DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED. CAUTION: Hydrogen (UN1049), Deuterium (UN1957) and Hydrogen, refrigerated liquid (UN1966) burn with an invisible flame. Hydrogen and Methane mixture, compressed (UN2034) may burn with an invisible flame. SMALL FIRE: Dry chemical or CO2. LARGE FIRE: Water spray or fog. Move containers from fire area if you can do it without risk. FIRE INVOLVING TANKS: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not direct water at source of leak or safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2012). b.) for the accidental release measures: As an immediate precautionary measure, it is mentioned : isolate spill or leak area for at least 100 meters (330 feet) in all directions. c.) LARGE SPILL: Consider initial downwind evacuation for at least 800 meters (1/2 mile). THIS IS THE CASE TO COINSIDER IN THE PRESENT SCENARIO. d.) FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. Other information received contained information about the EPI protective clothing recommended and data about the stability and reactivity of the gas: EPI : Protective Clothing: Self-contained breathing apparatus; protective clothing if exposed to liquid. (USCG, 1999). Stability and reactivity : Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. Pressures may build to dangerous levels if liquid gas contacts water in a closed container. AT 2:47pm FMI sent their first estimation of the gas plume drifting using hydrogen sulphide (HS) as a substrate in their drift model calculation (Escape model). Additionally the ppm values per distance close to the ground level from the accident point was listed, please see Table 1. FMI s response contained a gas plume drift picture, as shown in Figure 2.Based on this illustration the gas plume seems to drift through the whole city behind the port area! No estimation of the vertical ppm profile was made, however, which made it difficult to 7

9 understand if the gas may cause social impacts (irritation, suffocation) or causing danger for fire/explosion (flammable zone). Figure 2. Estimated LNG drift by FMI using hydrogen sulphide as a substrate for modelling. MARICE serviced delivered their gas plume drift estimation based on the ALOHA model at 3:16pm. MARICE identified the LNG outflow being very cold liquefied gas which will react with water in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. MARICE was not able to model the vaporization of the LNG in the conditions of the alert scenario, ALOHA model was run with propane (assuming that its behavior will be close to that of LNG). The scenario outflow, 7000 m 3, was also referred as the worst case scenario. 8

10 Table 1. Escape table on the calculated parameters (FMI). Vertical columns from left to right correspond: distance, drifting time, max concentration close to ground, max concentration close to ground as ppm, temperature and drifting velocity. The following analyses was presented: As for Toxicity: Figure 3 shows the gas plume drift with the identified AEGLs areas which represent threshold exposure limits for the general public. They are applicable to emergency exposure periods ranging from 10 minutes to 8 hours. AEGL-2 and AEGL-3 and AEGL-1 values as appropriate have been developed for 1 hour and distinguish varying degrees of severity of toxic effects. 9

11 The following definitions for the shown AEGL limits has been made: AEGL-1 is the airborne concentration, expressed as parts per million or milligrams per cubic meter (ppm or mg/m 3 ) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic non-sensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. AEGL-2 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape. AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life threatening health effects or death. Figure 3. MARICE evaluation for the gas plume drift using ALOHA model. Toxicity evaluation using propane as a drifting substrate. As for flammable level: For the flammable zone the estimation shown in Figure 4 was given. The parameter shown in the figure LEL is defined as Lower Explosive Limit. Hereafter have been drawn predicted areas where the ground-level vapor concentration in air is within the flammable range and can be ignited. 10

12 Figure 4. Flammable zones predicted by MARICE service. SYKE operational team defined both MARICE and FMI estimations are showing very long precautionary zones for the gas drift: gas plume will drift kilometers reaching outer suburban areas of the city. Thus discussions were carried out and notes were exchanged to try another gas as a modelling substrate to get more realistic view (for example methane). Modelling tools did not have LNG substrate as input gas. MARICE sent 3:57pm their new estimation using lower volumes of 3500 m 3 (Figure 5) and 500 m 3 (Figure 6) instead of the scenario worst case volume 7000 m 3. Smaller gas volume used in the calculation led to the smaller LEL zones, as seen from the figures. Related to this alert test SYKE performed no literature analyses related to the gas drift modelling or verified results related to the tests performed. However, as a brief reference the Table 4 of (Woodward, L. & Pitblado, R. 2010) has been attached as Appendix 4. It contains large scale tests results on the LNG release where two cases represent scenarios with ship and water. These tests gave estimations for the maximum lower flammability limit such as 442 m and 2250 m (ship and jetty). No deeper verification or analyses, however, has been made in this report. 11

13 Figure 5. Flammable zones predicted by MARICE service, release of m 3. Figure 6. Flammable zones predicted by MARICE service, release of 500 m 3. Finnish Institute of Occupational Health (FIOH) delivered their instructions at 3:24pm for SYKE. FIOH delivered Finnish TOKEVA instructions concerning LNG (Appendix 5) and 12

14 suitable OVA instructions for right procedures (for Methane) for the emergency situation (Appendix 6). FIOH also gave short instructions concerning the correct protective wearing in the emergency situation for the rescue personnel. Based on the TOKEVA the correct protective wearing is the fire-resistant wearing and pneumatic breathing apparatus. Furthermore following instructions should be taken into account based on OVA instructions for Methane: Methane gas outflow will cause danger of ignition outside and danger of explosion in indoor facilities. Any possible source of ignition can lead to the danger of fire and/or explosion. The mixture of oxygen and LNG will burn whoosh-like way. If the leakage will continue in the moment of ignition, the flame will stay in the point of leakage. In indoor situation the ignition of the gas mixture will lead to the explosion. Outside from the point of gas outflow a gas cloud will be formed. The border lines of the gas cloud need to be surveyed using gas detector (measuring the danger for ignition). The same holds on for indoor gas releases. Furthermore all possible sources causing the possible ignition have to be removed. 13

15 Lessons Learned The Exercise gave a good confident on all participating bodies related to their expertise and fast response: MARICE service worked effectively and gave first instructions for countermeasures in the short notice. Service was easy to use and communication and comments in the case went rapidly and with great expertise. MARICE system with their modelling toolbox is a valuable addition for the emergency preparedness. FMI duty officer with the expert team gave their response in the short notice, too. The response received included gas plume drift estimation which alerted the SYKE s response group to watch closer to the possible consequences of the scenario created: both MARICE and FMI modelling output s with kilometers long dangerous zones would create significant challenges for the response activities in the real situation! FIOH, gave also valuable information related to occupational safety and instructions for protective measures. These instructions were received also in the very short notice. When evaluating the possible consequences or impacts of the scenario used in this Exercise the following facts or restrictions for general usage of this report need to be taken into account: - Both modelling tools used in this study did not have a real mixture of LNG gas in their database. Simulations made using propane and nitrogen sulfide will probably overestimate the length of the gas plume drift. However, when evaluating the safety zones around the terminal, additional measures need to be taken when planning the preparedness for emergency situation and rescue actions. - Additionally some features of the models do not suit well to the light gases (at least with the case of ESCAPE model). Suitable modelling tools and test cases should be verified to get realistic model for the operational usage, please see for example (Webber et al 2006); - The dynamics of the size of the rupture, gas outflow velocity and gas interaction with the water surface with waves may have significant impact on the real gas plume formation. Similarly the effect of outdoor temperature may affect significantly on plume drift: questions were risen how the cold temperature will effect on the length of the safety zone. Does the gas drift longer distances for example in a normal winter weather with -20 o C temperature? - LNG gas releasing to the water surface will form a pool resulting gas evaporation and the formation of the gas cloud. Wave dynamics or the presence of ice in winter time will change the dynamics compared to the calm water situation.. - Probability for major LNG release will probably be low. Past reported incidents related to terminals and LNG transport supports this educated guess. It is more likely the possible LNG releases in the accident situations will be smaller having more local impacts and restricted impacts on the surrounding area. It should be understand that the properties which make LNG a good source of energy can also make it hazardous if not properly contained. LNG is predominately methane (87-99%) 14

16 but its composition also includes small amounts of other hydrocarbons. The chemical composition of the natural gas and the properties its components also determines how LNG behaves. One must clearly distinguish its properties as a liquid form its properties as a gas or vapour. LNG is odourless, colourless, non-corrosive, non-toxic and it is not easily flammable. If the concentration of LNG in the air is between 5% and 15% it is flammable if it contacts any ignition source. LNG s low temperature makes it cryogenic liquid. 15

17 Conclusions Finnish Environment Institute (SYKE) run an alert exercise in 18 th December The scenario tested was a virtual LNG release initiated by collision of a LNG coastal carrier and the pier in the HaminaKotka port. Based on the exercise scenario a rupture was formed to the middle section of the ship having the tank volume of 7000 m 3 of LNG. LNG outflow resulted the pool formation on the water surface with the formation of the gas cloud. Three bodies were alerted in the exercise: EMSA s MARICE service, Finnish Institute of Occupational Health and Finnish Meteorological Institute s duty officer. The requested assistance covered instructions for emergency actions, protection and the possible evaluation of the gas plume drift towards the port and surrounding city. Asisstance requested was received quickly, and first instructions were achieved in the short notice. It was noted, that LNG as a source material was not included into the input material of the used models. Propane and hydrogen sulfide (HS) used in calculations will overestimate the drifted plume distance. Spill quantity affects significantly on the evaluation of the flammable zone. In a real situation the estimation of the quantity of the spill outflow may be difficult due to many parameters affecting on the release dynamics. Pool formation dynamics with waves, and the presence of ice in winter time are some of these parameters to be studied later. Finally, main results of this exercise should be analysed in detail and evaluate on the basis of the existing emergency plan. Local emergency plan should be checked especially against: - assessment of scenarios for the dispersion of Natural Gas clouds and - installation of safety and exclusion zones in case of collision with bunker vessels or gasfuelled ships 16

18 References GL, European Maritime Safety Agency (EMSA) - Study on Standards and Rules for bunkering of gas-fuelled Ships. Final Report. Report No p + 52 app. NOAA. Report on Cameo Chemicals: LIQUEFIED NATURAL GAS (CRYOGENIC LIQUID). 4 pp. Sandia Guidance on Risk Analysis and Safety Implications of a Large Liquefied Natural Gas (LNG) Spill on Water, SAND , Dec Webber et al LNG source term models for hazard analysis. A review of the state-of-the-art and an approach to model assessment. Report by the UK Health and Safety Executive (HSE) 178 p. Vidmar et al The influence of large accidents on risk assessment for LNG terminals. In: Sustainable Maritime Transportation and Exploitation of Sea Resources. Edited by Enrico Rizzuto and Carlos Guedes Soares. Pp ISBN: Woodward, L. & Pitblado, R LNG RISK BASED SAFETY Modeling and Consequence Analysis. John Wiley & Sons,Inc Publication. 392 P. 17

19 List of Appendices 1 MARICE contact form 2 CAMEO/LNG sheet, page 1. 3 Aloha model input parameters 4 Summary of large scale dispersion test data (Woodward, L.& Pitplado, R. 2010) 5 TOKEVA instructions, page 1 of 4 pages (in Finnish) 6 OVA instructions for Methane, page 1 of 10 Pp( in Finnish) 18

20 Appendix 1 19

21 20

22 Appendix 2 21

23 Appendix 3 Aloha MODEL input parameters (MARICE) 22

24 Appendix 4 23

25 Appendix 5 24

26 Appendix 6 25