7.2 Risk Assessment 1

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1 7.2 Risk Assessment Introduction Industrial activities, which produce, treat, store and handle hazardous substances, have a high hazard potential to safety of man and environment at work place and outside. Recognizing the need to control and minimize the risks posed by such activities, the Ministry of Environment & Forests have notified the Manufacture Storage & Import of Hazardous Chemicals Rules in the year 1989 and subsequently modified, inserted and added different clauses in the said rule to make it more stringent. For effective implementation of the rule, Ministry of Environment & Forests has provided a set of guidelines. The guidelines, in addition to other aspects, set out the duties required to be performed by the occupier along with the procedure. The rule also lists out the industrial activities and chemicals, which are required to be considered as hazardous. The proposed project will be producing steel from iron ore and other raw materials. During the process of manufacture of steel and other associated materials hazardous gases are generated which are stored and used within the plant process. In addition to this also some other hazardous chemicals, which are required in the manufacture of steel or produced as a by-product, being stored and handled in plant. The major chemicals handled / stored by the plant includes coke oven gas (COG), blast furnace gas (BF gas), basic oxygen furnace gas (BOF gas), LPG, different acids etc. In view of this, proposed activities are being scrutinized in line of the above referred manufacture, storage and import of hazardous chemicals rules and observations / findings are presented in this chapter. 7.3 Approach to the Study Risk involves the occurrence or potential occurrence of some accidents consisting of an event or sequence of events. The risk assessment study covers the following: Identification of potential hazard areas; Identification of representative failure cases; Visualization of the resulting scenarios in terms of fire (thermal radiation) and explosion; Assess the overall damage potential of the identified hazardous events and the impact zones from the accidental scenarios; Assess the overall suitability of the site from hazard minimization and disaster mitigation point of view; Furnish specific recommendations on the minimization of the worst accident possibilities; and Preparation of broad disaster management plan (DMP), on-site and off-site emergency plan, which includes occupational and health safety plan. 7.4 Hazard Identification The following two methods for hazard identification have been employed in the study: 1 Risk assessment as per ToR-63 VIMTA Labs Limited, Hyderabad C7-1

2 Identification of major hazardous units based on manufacture, storage and import of hazardous chemicals rules, 1989 of Government of India (GOI rules, 1989); and Identification of hazardous units and segments of plants and storage units based on relative ranking technique, viz. fire-explosion and toxicity index (FE&TI) Classification of Major Hazardous Units Hazardous substances may be classified into three main classes namely flammable substances, unstable substances and toxic substances. The ratings for a large number of chemicals based on flammability, reactivity and toxicity have been given in NFPA Codes 49 and 345 M. The major hazardous materials to be stored, transported, handled and utilized within the facility have been summarized in the Table-7.3. The fuel storage details and properties are given in Table-7.4 and Table-7.5 respectively. TABLE-7.3 CATEGORY WISE SCHEDULE OF STORAGE TANKS Materials Blast furnace gas (carbon monoxide) Coke oven gas (hydrogen) Coke oven gas (methane) BOF gas (carbon monoxide) LPG LDO HFO Hazardous Properties UN Dangerous Goods Class 3 Flammable Gas UN Dangerous Goods Class 3 Flammable Gas UN Dangerous Goods Class 3 Flammable Gas UN Dangerous Goods Class 3 Flammable Gas UN Dangerous Goods Class 3 Flammable Gas UN Dangerous Goods Class 3 Flammable Liquid UN Dangerous Goods Class 3 Flammable Liquid TABLE-7.4 HAZARDOUS MATERIALS STORED, TRANSPORTED AND HANDLED A Material No. of Tanks Capacity (Storage Condition) 1 Blast furnace gas (carbon 2 50,000 m 3 monoxide) gaseous, ambient temperature and pressure 2 Coke oven gas (hydrogen & methane) 3 BOF gas (carbon monoxide) 2 50,000 m 3 gaseous, ambient temperature and pressure 2 50,000 m 3 gaseous, ambient temperature and pressure 4 LPG 3 50 T liquid & pressurized 5 HFO m 3 6 LDO m 3 VIMTA Labs Limited, Hyderabad C7-2

3 TABLE-7.5 PROPERTIES OF FUELS USED IN THE PLANT Chemical Codes/Label TLV FBP MP FP UFL LFL c % Blast furnace gas Flammable 50 ppm (carbon monoxide) Coke oven gas Flammable (hydrogen) Coke oven gas Flammable 1000 ppm (methane) BOF gas Flammable 50 ppm (carbon monoxide) LPG Flammable 1000 ppm < LDO Flammable HFO Flammable 14 >350 - > TLV : Threshold Limit Value FBP : Final Boiling Point MP : Melting Point FP : Flash Point UEL : Upper Explosive Limit LEL : Lower Explosive Limit Physio-Chemical Properties of Hazardous Chemicals Stored/Used The physio-chemical properties of BF/CO gas (toxic component is carbon monoxide), LPG and liquid oxygen are given below: Blast Furnace Gas (BFG) BFG is a by-product of the iron making process and is used as a fuel gas. It is an odourless, colourless and toxic gas. Its toxic properties are due to the presence of carbon monoxide (CO) (typically 21-25% v/v) in the gas. In confined space, it can form explosive mixture. BFG is a very low heating value fuel (CV= Kcal/nm 3 ), containing inerts of approximately 58% nitrogen and 17% carbon monoxide. Therefore, the gas is only likely to support stable combustion at elevated temperature, or with a permanent pilot flame. BFG may be ignited by a high ignition source such as a permanent pilot flame. BFG may be ignited by a high ignition source such as a welding torch. However, the resulting combustion is slow. BFG is not typically considered an explosion hazard for the following reasons: Very high ignition energies are required to initiate BFG combustion; High concentration of inerts in the gas; and Very low combustion energy (3.2 MJ/m 3 ). Coke Oven Gas (COG) COG is toxic and flammable gas and has a very strong odour. Its toxic properties are due to the presence of CO (typically 9% v/v) in the gas. COG has a specific gravity of 0.43 and therefore, is a very buoyant gas, which tends to disperse rapidly when released to the atmosphere. VIMTA Labs Limited, Hyderabad C7-3

4 The high concentration of hydrogen and methane in COG suggests that the gas can be ignited by a low ignition energy (e.g., static). Therefore, the probability of ignition of COG leaks is likely to be high relative to other flammable gases. COG is a corrosive gas due to the presence of hydrogen and sulphides (H2S=2500 mg/nm 3 ). This has significant implications for the maintainability of COG systems, because COG pipework frequently develops small corrosion holes. Carbon Monoxide CO is a colourless, odourless gas, which is also flammable (limits 12% to 74%). It has an auto-ignition temperature of 160 C. It is a flammable gas with serious fire hazard. The health effects of CO are largely the result of the formation of carboxyhemoglobin (COHb) which impairs the oxygen carrying capacity of the blood. Resumption of the normal oxygen supply process takes place once the blood. Resumption of the normal oxygen supply process takes place once an individual is removed from the contaminated atmosphere. However, any damage due to the prolonged loss of oxygen supply to the brain may not be reversible. The TLV, STEL and IDLH values for CO is 50 ppm, 400 ppm and 1200 ppm respectively. Liquified Petroleum Gas (LPG) In addition to the BFG, COG and liquid oxygen, JSW-JSL will also use LPG. LPG is a big fire and explosion hazard. Primarily, LPG is associated with the severe fire and explosion hazards, i.e., boiling liquid expanding vapour explosion (BLEVE) under sustained ignition and also vapour cloud explosion (VCE). BLEVE can be caused by an external fire near the storage vessel causing heating of the contents and pressure build-up. While tanks are often designed to withstand great pressure, constant heating can cause the metal to weaken and eventually fail. An unconfined (i.e., in open space) vapour cloud explosion (VCE) is possible only when a large amount comes from a rupture of line/leak from large hole and accumulates in the open space as a cloud while moving along the wind. If the mixture of cloud and air is in the flammability range and some ignition source is available on its way, it ignites and subsequently releases the energy on the point of ignition in the form of a blast wave. It is called vapour cloud explosion (VCE). The human injury and loss of property in case of VCE depends upon the mass involved in the explosion and the location of the center of explosion. A flammable release of gas that does not ignite at the leak source, or has a delayed ignition, can produce a large vapour cloud, which covers a significant area. In the absence of significant confinement or obstruction, ignition of the cloud results in a low velocity flame front with minimal over pressure effects, known as a flash fire and typically results (initially) only in impacts within the flammable cloud Identification of Major Hazard Installations Based on GOI Rules, 1989 Following accidents in the chemical industry in India over a few decades, a specific legislation covering major hazard activities has been enforced by Govt. of India in VIMTA Labs Limited, Hyderabad C7-4

5 1989 in conjunction with Environment Protection Act, This is referred here as GOI Rules For the purpose of identifying major hazard installations, the rules employ certain criteria based on toxic, flammable and explosive properties of chemicals. A systematic analysis of the fuels/chemicals and their quantities of storage has been carried out, to determine threshold quantities as notified by GOI Rules, 1989 and the applicable rules are identified. Applicability of storage rules are summarized in Table-7.6. TABLE-7.6 APPLICABILITY OF GOI RULES TO FUEL/CHEMICAL STORAGE Sr. No. Chemical/ Fuel Listed in Schedule Total Quantity Threshold Quantity (T) for Application of Rules 5,7-9, Blast furnace gas (carbon 2x50,000 m 3(1) monoxide) Coke oven gas (hydrogen & 2x50,000 m 3(1) methane) BOF gas 2x50,000 m 3(1) (carbon monoxide) LPG 3(1) 3x50 T HFO 3(1) 2 x 1000 m 3 25 MT 200 MT 6 LDO 3(1) 2x250 m 3 25 MT 200 MT 7.5 Hazard Assessment and Evaluation Methodology An assessment of the conceptual design is conducted for the purpose of identifying and examining hazards related to feed stock materials, major process components, utility and support systems, environmental factors, proposed operations, facilities, and safeguards Preliminary Hazard Analysis (PHA) A preliminary hazard analysis is carried out initially to identify the major hazards associated with storages and the processes of the plant. This is followed by consequence analysis to quantify these hazards. Finally, the vulnerable zones are plotted for which risk reducing measures are deduced and implemented. Preliminary hazard analysis for fuel storage area and whole plant is given in Table-7.7 and Table-7.8. TABLE-7.7 PRELIMINARY HAZARD ANALYSIS FOR STORAGE AREAS Unit Capacity Hazard Identified Blast furnace gas (carbon monoxide) 1,00,000 m 3 Toxic vapor cloud/ Vapour cloud explosive Coke oven gas (hydrogen & methane ) 1,00,000 m 3 Toxic vapor cloud/ Vapour cloud explosive BOF gas (carbon monoxide) 1,00,000 m 3 Toxic vapor cloud/ Vapour cloud explosive LPG 3 x 50 T BLEVE HFO 2 x 1000 m 3 Pool fire LDO 2 x 250 m 3 Pool fire VIMTA Labs Limited, Hyderabad C7-5

6 TABLE-7.8 PRELIMINARY HAZARD ANALYSIS FOR THE WHOLE PLANT IN GENERAL PHA Category Environmental factors Description of Plausible Hazard If there is any leakage and eventuality of source of ignition. Highly inflammable nature of the liquid fuels may cause fire hazard in the storage facility. Recommendation Provision -- All electrical fittings and cables are provided as per the specified standards. All motor starters are flame proof. A well designed fire protection including foam, dry powder, and CO 2 extinguisher should be provided. Fire extinguisher of small size and big size are provided at all potential fire hazard places. In addition to the above, fire hydrant network is also provided Fire Explosion and Toxicity Index (FE&TI) Approach Fire, explosion and toxicity indexing (FE & TI) is a rapid ranking method for identifying the degree of hazard. The application of FE & TI would help to make a quick assessment of the nature and quantification of the hazard in these areas. However, this does not provide precise information. The degree of hazard potential is identified based on the numerical value of F&EI as per the criteria given below: F&EI Range Degree of Hazard 0-60 Light Moderate Intermediate Heavy 159-up Severe By comparing the indices F&EI and TI, the unit in question is classified into one of the following three categories established for the purpose (Table-7.9). TABLE-7.9 FIRE EXPLOSION AND TOXICITY INDEX Category Fire and Explosion Index (F&EI) Toxicity Index (TI) I F&EI < 65 TI < 6 II 65 < or = F&EI < 95 6 < or = TI < 10 III F&EI > or = 95 TI > or = 10 Certain basic minimum preventive and protective measures are recommended for the three hazard categories. VIMTA Labs Limited, Hyderabad C7-6

7 Results of FE and TI for Storage/Process Units Based on the GOI Rules 1989, the hazardous fuel used by the proposed steel plant is identified. Fire and explosion are the likely hazards, which may occur due to the fuel storage. Hence, fire and explosion index has been calculated for in plant storage. Estimates of FE&TI are given in Table Conclusion TABLE-7.10 FIRE EXPLOSION AND TOXICITY INDEX Sr. Chemical/ Fuel Total Capacity F&EI Category TI Category No. 1 Blast furnace gas (carbon 2 x 50,000 m I III monoxide) 2 Coke oven gas (hydrogen & 2 x 50,000 m I 5.6 I methane) 3 BOF gas 2 x 50,000 m I III (carbon monoxide) 4 LPG 3 x 50 T III 5.43 I 5 HFO 2 x 1000 m I III 6 LDO 2 x 250 m I 9.55 II Results of FE&TI analysis show that the storage of carbon monoxide gas, hydrogen & methane gas, LPG, HFO and LDO falls in category of Light to moderate category. 7.6 Consequence Analysis and Risk Assessment Introduction Consequences of worst-case/major credible emergency scenarios and likely dangers to be associated in the proposed JSW-JSL plant near Barenda village have been assessed through dispersion modeling, consequence and risk analysis. Consequence analysis deals with the study of physical effects of potential dangers associated with hazardous chemicals, their storage and operation etc. For flammable and explosive chemicals like LPG, consequence on humans/animals and structures are studied in terms of heat radiations and over pressures. For toxic chemicals like carbon monoxide, consequence on human/animals are studied in terms of concentration and dose-response relationships. The physical impact of heat radiation, over pressure and toxic concentration are shown in Table The consequence modeling for different release scenarios for proposed JSW-JSL plant has been carried out using the model ALOHA- Area Locations of Hazardous Atmospheres developed by NOHAA and USEPA. Aloha predicates the rate at which chemical vapors may escape into the atmospheres from the leaking/ruptured tank. VIMTA Labs Limited, Hyderabad C7-7

8 Sr. No. TABLE-7.11(A) DAMAGE DUE TO INCIDENT RADIATION INTENSITIES Incident Radiation (kw/m 2 ) Type of Damage Intensity Damage to Equipment Damage to People Damage to process equipment 100% lethality in 1 min. 1% lethality in 10 sec Minimum energy required to ignite wood at indefinitely long exposure without a flame 50% Lethality in 1 min. significant injury in 10 sec Maximum thermal radiation -- intensity allowed on thermally unprotected adjoining equipment Minimum energy to ignite with a 1% lethality in 1 min. flame; melts plastic tubing Causes pain if duration is longer than 20 sec, however blistering is un-likely (First degree burns) Causes no discomfort on long exposures Source: Techniques for Assessing Industrial Hazards by World Bank TABLE-7.11(B) EXPOSURE TIME NECESSARY TO REACH THE PAIN THRESHOLD Radiation Level (kw/m 2 ) Time to Pain Threshold (Seconds) Source: Techniques for Assessing Industrial Hazards by World Bank TABLE-7.11(C) PHYSCIAL IMPACT OF EXPLOSION OVER PRESSURE Pressure Damage Produces by Blast (psig) 0.1 Breakage of small windows under strain 0.7 Minor damage to house structures 1.0 Partial demolition of houses 2 Partial collapse of walls and roofs of houses 3 Heavy machines (3000 lb) in industries building suffered little damage; steel frame building distorted 4 Cladding of light industries building ruptured 5 Wooden utility poles snapped; tall hydraulic press (40,000 lb) in building slightly damaged 7 Loaded train wagons overturned 10 Probable total destruction of buildings; heavy machines tools (7000 lb) moved and badly damaged 300 Limit of crater lip VIMTA Labs Limited, Hyderabad C7-8

9 TABLE-7.11(D) PHYSICAL IMPACT OF TOXIC CONCENRATION Concentration Level Short-Tem Exposure Limit (STEL) Immediately Danger to Life and Health (IDLH) Lethal Concentration at 50% mortality (LC50) Fatal Level Observed Effect Maximum concentration of the substance to which workers can be exposed for a period upto 15 minutes without suffering (a) Intolerable irritation (b) Chronic or irreversible tissue change (c) narcosis of sufficient degree to increase accident proneness, impair self rescue, or materially reduce worker efficiency, provided that no more than 04 excursion per day are permitted, with at least 60 minutes between exposure periods, and provided that daily TLV is not exceeded. An atmospheric concentration of any toxic, corrosive or asphyxiant substance that poses an immediate threat to life or would cause irreversible or delayed adverse health effects or would interfere with an individual s ability to escape from a dangerous atmosphere. If IDLH values are exceeded, all unprotected people must leave the area immediately. LC stands for Lethal Concentration. LC values usually refer to the concentration of a chemical in air but in environmental studies it can also mean the concentration of a chemical in water. For inhalation experiments, the concentration of the chemical in air that kills 50% of the test animals in a given time (usually half to four hours) is the LC 50 value Death Maximum Credible Loss Scenarios (MCLS) As per MSIHC rules 1989 as amended in 2000, disaster management plan (DMP) for any industry is prepared for worst-case release scenarios associated with maximum damage potentials. The hazardous chemicals present in JSW-JSL are susceptible for creating emergency scenarios and have been considered for assessing the damage potentials through predicting the vulnerable zones and fatality/injured levels: Blast furnace (BF) gas (carbon monoxide and hydrogen); Coke oven (CO) gas (carbon monoxide and hydrogen); LPG; HFO; and LDO Consequence Analysis of Accidental Release of Toxic Chemicals The main toxic component of BF gas is carbon monoxide (CO) with maximum 25% as basic composition. The IDLH and STEL values of CO are 1200 ppm and 400 ppm respectively. These values represent the consequence zones of moderate and low damage respectively. The severe level corresponding to 50% toxicity fatality level has been considered as 3696 ppm for 20 minutes exposure duration with reference to CO. As per statutory regulation for the preparation of DMP, the worst-case scenario involving the catastrophic release of entire quantity of a gasholder (BF/CO) is considered, though the frequency of occurrence of worst-case scenario is very VIMTA Labs Limited, Hyderabad C7-9

10 remote. Such scenarios are considered in the assessment of likely dangers in and around the plant with respect to the ultimate preparedness measures Meteorological Information for Consequence Analysis During summer season, JSW-JSL area experiences maximum temperature about 43.4 C with high surface winds and in winter months, the minimum temperature reach about 9.7 C. The relative humidity is in the range of 29.5% 38.4% and during rainy season, it may reach near 87%. The prevailing wind direction varies with respect to season. The predominant wind direction is NW and SW with speed of 1 to 9 km/hr and the calm condition prevails for 7.8%. Atmospheric conditions (wind speed, direction, solar radiation, cloud amount etc.) at the time of release largely controls the extent of vulnerable zones. The physical state of the atmosphere is usually best described by Pasquill-Gifford stability class A (very unstable) to F (very stable). The details of various stability classes are given in Table TABLE-7.12 PASQUILL-GIFFORD ATMOSPHERIC STABILITY CLASSES Surface Day Night Wind Speed Incoming Solar Radiation Amount of over cast (at 10 m) in Strong Moderate Slight >4/8 low <3/8 low m/s cloud cloud <2 A A-B B 2-3 A-B B C E E 3-5 B B-C C D E 5-6 C C-D D D D >6 C D D D D The atmospheric characteristics of a particular site experience in general, almost all types of stability classes during a season (summer, winter and rainy). For example, in summer months, when the temperature is high for a sufficient amount of time, a particular site like JSW-JSL near Barenda village may experience unstable (A/B class) condition in noon time, neutral (D class) for majority of the time and also stable condition (E/F) in the late night. In winter months, when the solar radiation is weak to moderate with a considerable surface wind speed, the atmospheric conditions may correspond to C/D class, E and F class in the late night and early morning. However, the neutral class (D) of atmospheric condition exists for most of the time in a day in a particular season; and hence it is considered as the most representative class for a particular site and in a particular season (summer, rainy or winter). The other average meteorological parameters considered in the analysis are as follows: ambient temperature = 38.5, relative humidity = 48, roughness parameter = 0.17 (industrial area), three stability classes, i.e., B (unstable), D (neutral) and F (very stable) class with wind speeds of 1.5 m/s to 2 m/s. For representative cases, D class with wind speed of 2 m/s has been considered. VIMTA Labs Limited, Hyderabad C7-10

11 7.6.5 Flammable, Explosive and Toxicological Levels Considered The following levels corresponding to severe, moderate and low damage levels have been considered are given in Table-7.13(A) and Table-7.13(B). TABLE-7.13(A) TOXICOLOGICAL LEVELS CONSIDERED FOR CONSEQUENCE ANALYSIS Vulnerable Zones Concentration (in ppm) and Damage Levels considered for BF/CO gas Red zone: severely affected zone 50% Fatality level (CCPS)=3696 ppm for 20 minutes exposure Orange zone: moderately affected zone IDLH=1200 ppm for 30 minutes exposure Yellow zone : low impact zone STEL=400 ppm for 1 minutes exposure TABLE-7.13(B) FLAMMABLE AND EXPLOSIVE LEVELS CONSIDERED FOR CONSEQUENCE ANALYSIS Vulnerable Zones Radiation Intensity (kw/m 2 ) Levels for LPG Red zone: severely affected zone Orange zone: moderately affected zone Explosion Overpressure (psi) Levels for LPG, CO and Hydrogen 37.5 (kw/m 2 ) 7 psi 12.5 (kw/m 2 ) 3 psi Yellow zone : low impact zone 4.5 (kw/m 2 ) 1 psi 7.7 Selection of Scenarios in Gas Holders Blast Furnace (BF) Gas Holder The maximum volume (design capacity) of a BF gas holder is 50,000 m 3. The density of BF gas is 1.02 kg/m 3, the total quantity of BF gas available in the holder of volume 50,000 m 3 is 51,000 kg. Out of this quantity, about 25 %, i.e., 12,750 kg are CO. The maximum amount of hydrogen in BF gas is about 6% and hence the contribution of hydrogen in the holder will be about 3060 kg. The maximum values of temperature and pressure at the header are 35 C and 350 mmwc. The following worst-case release scenarios involving BF gasholder have been conceptualized: i) Accidental release of 12,750 kg of CO into the atmosphere leading to toxic vapour cloud; ii) Accidental release of 12,750 kg of CO into the atmosphere leading to explosive vapour cloud; and iii) Explosion associated with 3060 kg of hydrogen due to catastrophic release of BF gas into the atmosphere from holder. VIMTA Labs Limited, Hyderabad C7-11

12 7.7.2 Coke Oven (CO) Gas Holder The maximum volume (design capacity) of a CO gas holder is 55,000 m 3. As the density of CO gas is 0.43 kg/ m 3, the total quantity of coke oven gas available in the holder of volume 55,000 m 3 us 23,650 kg. Out of this quantity, maximum 9 %, i.e., 2128 kg is CO. The maximum amount of hydrogen in CO gas is about 55 % and hence the contribution of hydrogen in the holder will be about kg. The maximum values of temperature and pressure at the header are 35 C and 343 mmwc. The following worst-case release scenarios involving CO gasholder have been conceptualized: i) Accidental release of approximately 2128 kg of CO into the atmosphere (toxic impact only); ii) Accidental release of 2128 kg of CO into the atmosphere leading to explosive vapour cloud; and iii) Explosion associate with kg of hydrogen due to catastrophic release of CO gas into the atmosphere from holder Fire and Explosion Associated with LPG Storage In JSW-JSL, there will be one LPG bullet with capacity of 50 MT. LPG is a colourless, tasteless and odourless gas. It has the ability to flash back, explode within an enclosed space. It is a flammable gas, so it may be ignited from flames, heat, sparks, static electricity and operational electrical switches. Thus, the use of LPG within the JSW-JSL premise may lead to the occurrence of various scenarios. Only the major scenarios of fire and explosion have been considered for the consequence modeling to assess the maximum damage with the inventory of 45 MT (90 % full bullet). i) Catastrophic failure of a LPG bullet (inventory=45 MT) leading to boiling liquid expanding vapour explosion (BLEVE); and ii) Catastrophic failure of a LPG bullet (inventory=45 MT) leading to vapour cloud explosion (VCE) Consequence Analysis Results for Toxic Carbon Monoxide in BF and CO Gas Holders Though there are several incidences of gas holder fire and explosion resulting into the release, the frequency of occurrence of such catastrophic release scenarios in will vary as per the safety measures adopted in the unit. Carbon monoxide (CO) has both toxicity and flammability/explosive nature. The consequence analysis results in terms of maximum downwind distances due to accidental release of BF/CO gas (equivalent CO) from holders under various atmospheric stability conditions are shown in Table From the Table-7.12, worst case scenarios arising for toxic vapor cloud catastrophic release from the holders (BF/CO) will have toxic impact upto 632 m for CO holders and about 1100 m for BF gas holder respectively for IDLH concentration level (1200 ppm) of CO under neutral stability class (D) and 2.0 m/s. The consequence distances will further increase upto a maximum distance of about 1280 m if the release occurs in stable atmosphere (F class). Whereas, in VIMTA Labs Limited, Hyderabad C7-12

13 unstable atmospheric conditions (B class), the downwind distances will be the least. The graphical representations of the consequence analysis of the carbon monoxide are shown in Figure-7.3. The flammability/explosive impact of CO released from BF/CO holders have been studied in terms of extension of flammable impact under D; 2 m/s. The maximum affected distance of 32 m of CO holder and 78 m of BF gas holder area. TABLE-7.14 MAXIMUM IMPACT DISTANCES FOR TOXIC/FLAMMABLE VAPOUR CLOUD OF CARBON MONOXIDE GAS FROM BF/CO GAS HOLDER Sr. No Scenario 1 Accidental release of kg of carbon monoxide (CO) into the atmosphere due to catastrophic failure of BF gas holder 2 Accidental release of 2128 kg of carbon monoxide (CO) into the atmosphere due to catastrophic failure of CO gas holder *wind speed in m/sec Wind Speed*/ Stability Class Toxic Vapour Cloud (maximum downwind distance in m) (ppm) (ppm) (ppm) Vapour Cloud Explosion (maximum distance in m) 0.7(psi) 1(psi) 2(psi) 2B D F B D F VIMTA Labs Limited, Hyderabad C7-13

14 FIGURE-7.3(A) ACCIDENTAL RELEASE OF CO INTO THE ATMOSPHERE LEADING TO TOXIC VAPOR CLOUD FIGURE-7.3(B) ACCIDENTAL RELEASE OF CO INTO THE ATMOSPHERE LEADING TO VAPOUR CLOUD EXPLOSION VIMTA Labs Limited, Hyderabad C7-14

15 7.7.5 Consequence Analysis Results for Fire/Explosion Scenario of Hydrogen as Component of COG/BFG One of the major flammable/explosive components of CO/BF gas is hydrogen. Besides explosion, it may produce fireball type situation in the presence of ignition source. Since hydrogen is very light, there is a chance of early ignition and less possibility of explosion in late ignition. The maximum affected distances (m) for fire and explosive scenarios of hydrogen under neutral stability class (D) and wind speed of 2.0 m/s is given in Table-7.15 and Figure-7.4. TABLE-7.15 VARIOUS SCENARIOS OF HYDROGEN Scenarios Explosion associated with 3060 kg of hydrogen due to catastrophic release of BF gas into the atmosphere from holder. Explosion associate with kg of hydrogen due to catastrophic release of CO gas into the atmosphere from holder. Over pressure (psi) for Explosion (early ignition)/distance in meter 1 psi 3 psi 7 psi The vulnerable impact distances for explosion associated with hydrogen after worst case release from BF/CO holder in terms of explosion overpressure levels under D; 2 m/s for early ignition. Maximum impact distance corresponding to moderate damage level of 3 psi for BF gas holder is 74 m and CO gas holder is 346 m from the holder area. In addition, for planning purposes, the consequence impact zones (severe/moderate/low) under stability class D, 2 m/s for the worst-case release scenarios considered are depicted in plant layout of JSW-JSL. These drawings show the locations and areas in JSW-JSL coming under severe/moderate/low impact zones corresponding to various concentration levels of toxic vapour cloud of hydrogen. VIMTA Labs Limited, Hyderabad C7-15

16 FIGURE-7.4(A) EXPLOSION ASSOCIATED WITH HYDROGEN DUE TO CATASTROPHIC RELEASE OF BF GAS INTO THE ATMOSPHERE FROM HOLDER FIGURE-7.4(B) EXPLOSION ASSOCIATED WITH HYDROGEN DUE TO CATASTROPHIC RELEASE OF CO GAS INTO THE ATMOSPHERE FROM HOLDER VIMTA Labs Limited, Hyderabad C7-16

17 7.7.6 Consequence Results for Fire and Explosion Scenarios for LPG Since the worst-case release scenario of LPG release are Boiling Liquid Expanding Vapor Explosion (BLEVE) and unconfined Vapor Cloud Explosion (VCE), the impact factors considered are radiation intensity and explosion overpressure. The three heat radiation levels of 37.5 kw/m 2, 12.5 kw/m 2 and 4.5 kw/m 2 and three explosion overpressure levels of 7 psi, 3psi and 1 psi corresponding to severe moderate and low damage levels have been considered respectively. Maximum affected downwind distances (in m) due to heat radiation and explosion over pressure level of LPG (stability class: D and wind speed =2.0 m/s) BLEVE/Fire ball scenarios are given in Table-7.16 and Figure-7.5. TABLE-7.16 (A) THERMAL RADIATION LEVELS DUE TO FAILURE OF LPG BULLET Scenario BLEVE due to catastrophic failure of a LPG Bullet (45 MT) Thermal Radiation Intensities in kw/m 2 /Distance in m 37.5 kw/m kw/m kw/m TABLE-7.16 (B) EXPLOSIVE OVER PRESSURE LEVELS DUE TO FAILURE OF LPG BULLET Scenario Vapour cloud explosion due to catastrophic rupture of LPG bullet (45 MT) Explosion Overpressure Level in psi /Distance in m 1 psi 3 psi 7 psi Never reached LOC Consequence Analysis Results for Pool Fire Scenario for HFO and LDO Storage Tanks The maximum capacity of storage of HFO and LDO are 2x1000 KL and 2X 250 KL respectively. The most credible failure is the rupture/hole of the storage tank. As a worst case, it is assumed that the entire contents leak out into the dyke forming a pool, which may catch fire on finding a source of ignition. The radiation intensities for rupture of HFO and LDO storage tank is given in Table-7.17 and Figure-7.6. TABLE-7.17 THERMAL RADIATION DUE TO FAILURE OF HFO AND LDO TANKS Scenario Failure of HFO storage tank Failure of LDO storage tank Thermal Radiation kw/m 2 /distances in m < VIMTA Labs Limited, Hyderabad C7-17

18 FIGURE-7.5(A) THERMAL RADIATION LEVELS DUE TO FAILURE OF LPG BULLET FIGURE-7.5(B) EXPLOSIVE OVER PRESSURE LEVELS DUE TO FAILURE OF LPG BULLET VIMTA Labs Limited, Hyderabad C7-18

19 FIGURE-7.6(A) THERMAL RADIATION DUE TO FAILURE OF HFO TANKS FIGURE-7.6(B) THERMAL RADIATION DUE TO FAILURE OF LDO TANKS VIMTA Labs Limited, Hyderabad C7-19

20 7.7.8 Coal Handling Plant - Dust Explosion Coal dust when dispersed in air and ignited would explode. Crusher house and conveyor systems are most susceptible to this hazard. To be explosive, the dust mixture should have: Particles dispersed in the air with minimum size (typical figure is 400 microns); Dust concentrations must be reasonably uniform; and Minimum explosive concentration for coal dust (33% volatiles) is 50 gm/m 3. Failure of dust extraction and suppression systems may lead to abnormal conditions and may increase the concentration of coal dust to the explosive limits. Sources of ignition present are incandescent bulbs with the glasses of bulkhead fittings missing, electric equipment and cables, friction, spontaneous combustion in accumulated dust. Dust explosions may occur without any warnings with maximum explosion pressure upto 6.4 bar. Another dangerous characteristic of dust explosions is that it sets off secondary explosions after the occurrence of the initial dust explosion. Many a times the secondary explosions are more damaging than primary ones. The dust explosions are powerful enough to destroy structures, kill or injure people and set dangerous fires likely to damage a large portion of the coal handling plant including collapse of its steel structure which may cripple the life line of the steel plant. Stockpile areas shall be provided with automatic garden type sprinklers for dust suppression as well as to reduce spontaneous ignition of the coal stockpiles. Necessary water distribution network for drinking and service water with pumps, piping, tanks, valves etc., will be provided for distributing water at all transfer points, crusher house, control rooms etc. A centralized control room with microprocessor based control system (PLC) has been envisaged for operation of the coal handling plant. Except for locally controlled equipment like traveling tripper, dust extraction/ dust suppression / ventilation equipment, sump pumps, water distribution system etc., all other in-line equipment will be controlled from the central control room but will have provision for local control as well. All necessary interlocks, control panels, MCC s, mimic diagrams etc. will be provided for safe and reliable operation of the coal handling plant Control Measures for Coal Yards The total quantity of coal will be stored in separate stock piles, with proper drains around to collect washouts during monsoon season. Water sprinkling system will be installed on stocks of coal in required scale to prevent spontaneous combustion and consequent fire hazards. The stock geometry will be adopted to maintain minimum exposure of stock pile areas towards predominant wind direction Identification of Hazards The various hazards associated, with the plant process apart from fuel storage have been identified and are outlined in Table VIMTA Labs Limited, Hyderabad C7-20

21 TABLE-7.18 HAZARD ANALYSIS FOR PROCESS IN THE PLANT Sr. No. Blocks/Areas Hazards Identified 1 Coal storage in open yard Fire, spontaneous combustion 2 Coal handling plant Fire and/or dust explosions including bunker area 3 Boilers Fire (mainly near oil burners), steam explosions, fuel explosions 4 Steam turbine generator buildings Fires in a) Lube oil system b) Cable galleries c) Short circuits in i) Control rooms ii) Switch-gears Explosion due to leakage of hydrogen and fire following it. 5 Switch-yard control room Fire in cable galleries and switch-gear/control room 6 LDO & HSD tank farms Fire Hazardous Events with Greatest Contribution to Fatality Risk The hazardous event scenarios likely to make the greatest contribution to the risk of potential fatalities are summarized in Table Onsite facility refers to the operating site at Barenda village, whereas offsite facility refers to transport and handling systems, which are away from the operating site. TABLE-7.19 HAZARDOUS EVENTS CONTRIBUTING TO ON-SITE FACILITY RISK Hazardous Event Risk Rank Consequences of Interest Onsite vehicle impact on personnel 3 Potential for single fatalities, onsite impact only Entrapment/struck by machinery 3 Potential for single fatalities, onsite impact only Fall from heights 3 Potential for single fatalities, onsite impact only Electrocution 3 Potential for single fatalities, onsite impact only Storage tank rupture 3 Potential for single fatalities, onsite impact only Risk Assessment Summary The preliminary risk assessment has been completed for the proposed plant and associated facilities and the broad conclusions are as follows: There will be no significant adverse community impacts or environmental damage consequences; and VIMTA Labs Limited, Hyderabad C7-21

22 The hazardous event scenarios and risks in general at this facility can be adequately managed to acceptable levels by performing the recommended safety studies as part of detailed design, applying recommended control strategies and implementing a safety management system Risk Reduction Opportunities The following opportunities will be considered as a potential means of reducing identified risks during the detailed design phase: Buildings and plant structures designed for cyclone and seismic events (where appropriate), to prevent structural collapse and integrity of weather (water) proofing for storage of dangerous goods; Provision for adequate water capacity to supply fire protection systems and critical process water; Isolate people from load carrying/mechanical handling systems, vehicle traffic and storage and stacking locations; Installation of fit-for-purpose access ways and fall protection systems to facilitate safe access to fixed and mobile plant; Provision and integrity of process tanks, waste holding tanks and bunded areas as per relevant standards; Containment of hazardous materials; Security of facility to prevent unauthorized access to plant, introduction of prohibited items, and control of onsite traffic; and Development of emergency response management systems commensurate with site specific hazards and risks (fire, explosion, rescue and first aid). **** VIMTA Labs Limited, Hyderabad C7-22