RISK ASSESSMENT 6.1 INTRODUCTION

Transcription

1 RISK ASSESSMENT 6.1 INTRODUCTION Krishak Bharati Cooperative Limited (KRIBHCO) is proposing to setup a NPK (12 lakh MT) Fertlizer plant at Sy. No. Bit-II, Survepalli village, near to Krishnapatnam port, Venkatachalam Tehsil, Nellore District Andhra Pradesh. Four raw materials in liquid state, namely Ammonia, Phosphoric Acid, Sulphuric Acid and MOP have been proposed to be used for the manufacturing of NPK fertilizer. Storage at Plant Site Ammonia storage tank : 1 x MT. Sulphuric acid storage tank : 1 x MT. Phosphoric storage tank : 1 x MT. MOP storage total capacity : Storage at Krishnapatnam (KPCL) Port MT. Ammonia : 2x15000 MT; Phosphoric acid : 4x10000 MT. Through Pipelines, these raw materials are unloaded from Berth to Port Storage (03-05 km) and from Port storage to Plant site (16 km) Hazard identification and risk assessment was carried out for the chemicals, which are being proposed to be stored & handled. Safety measures for storage and handling of these chemicals are also proposed in this chapter Objectives & Methodology of the Risk Analysis Study A three LEVEL risk assessment approach is adopted. The brief outline of the three tier approach is given below: Level 1 Risk Screening This is top-down review of worst- case potential hazards/risks, aimed primarily at storage of chemicals, which pose the highest risk. The Material Safety Data Sheets (MSDS) of the chemicals were reviewed to identify the potential hazards posed by the chemicals.various screening factors considered include: o o o Inventory of hazardous materials; Hazardous properties; Storage capacity; Asian Consulting Engineers Pvt. Ltd. 6-1

2 Level 2 Risk Scenario Identification After identification of potential hazards, different risk scenarios were delineated for each of the chemicals based on the nature of hazard. Level 3 Quantitative Risk Assessment PHAST 6.7 version software was used for the risk assessment of the liquid raw materials, which will be stored at the premises. Risk assessment was carried out for each of the risk scenarios identified for the chemicals in case of leakages from the storage tanks. Worst possible scenarios were taken into account for the risk analysis Hazards Classification The hazard classification has been carried out based on the data provided in MSDS data sheets and as per the classification MSHIC Rules, 1986 and its amendments thereof. The hazard classification is given in Table 6.1. Table 6.1: Potential Hazard Classification and Analysis of Chemicals to be Used in the Proposed Unit Sl. No. Hazardous Material Quantit y to be Stored (MT) 1 Ammonia 10,000 MT (Plant Side) 30,000 MT (Port Side) 2 Sulphuric Acid 10,000 MT (Plant Side) Potential Hazards Fire Hazard: Forms flammable mixture with air. Explosion Hazard: Forms explosive mixture with air and highly reactive with other substances, especially metals to form violently explosive substances. Health Hazard: Strongly irritant to skin, eyes and respiratory system. Inhalation of high concentration causes suffocation, burning of the tract and may be fatal. Fire Hazard: Contact with combustible materials may cause fire. Highly reactive. Contact with many organic and inorganic chemicals may cause fire or explosion. Contact with metals liberates flammable hydrogen gas. Health Hazard: Highly corrosive and toxic. Strong sulphuric acid mist is carcinogenic. Reactivity: Hazard Classification as per Part I, Schedule I, MSHIC Rules, 1986 and its amendments thereof Extremely Toxic (Inhalation Toxicity - >0.5 mg/l) Extremely Toxic (Inhalation Toxicity mg/l) Asian Consulting Engineers Pvt. Ltd. 6-2

3 Sl. No. Hazardous Material 3 Phosphoric Acid Quantit y to be Stored (MT) 10,000 MT (Plant Side) 40,000 MT (Port Side) Potential Hazards Highly reactive with water, metals, excess heat, combustible materials, organic materials, oxidizers, amines, bases. Fire hazard: Reacts with most metals to produce flammable/explosive hydrogen gas. Reacts violently with strong caustics, sodium tetrahydroborate metals, fluorides, halogenated organics, cyanides, sulphides, mercaptans, nitrides, metal phosphides, acetylides, silicides, carbides. Potentially dangerous reactions with strong oxidizing agents, reducing agents, organic peroxides. Azo compounds, epoxides, aldehydes and other polymerizable compounds can polymerize violently with phosphoric acid. Forms detonable mixture with nitromethane. Explosion Hazard: Containers may explode when heated. Health Hazard: If heated, releases toxic vapours. Mists may cause irritation of the eyes, nose and respiratory tract. May cause increased pulmonary resistance and transient cough. Severe overexposure can cause pulmonary edema which may be fatal. Symptoms (shortness of breath, cyanosis) may appear several hours after exposure. Concentrated solutions may cause pain and severe burns to the skin. Concentrated solutions cause immediate pain, severe burns and permanent corneal damage which may result in blindness. Hazard Classification as per Part I, Schedule I, MSHIC Rules, 1986 and its amendments thereof Extremely Toxic (Inhalation Toxicity mg/l) Asian Consulting Engineers Pvt. Ltd. 6-3

4 6.1.3 Risk Scenarios Based on the identified potential hazards of the chemicals, different scenarios were delineated as given in Table 6.2. Table 6.2: Identified Risk Scenarios Chemical Scenario No. Identified Potential Risk Scenarios Ammonia Sulphuric Acid Phosphoric Acid Risk Assessment Scenario-1. Scenario-2. Scenario-3. Scenario-4. Scenario-5. Scenario-6. Scenario-7. Scenario-8. Scenario-9. Scenario-1 Scenario-1 Scenario-2 Scenario-3 Leaking tank (Port), chemical is not burning and forms evaporating puddle. Leaking tank (Port),, chemical is burning and forms a pool fire. Tank(Port), explodes. Leaking Pipeline, chemical is not burning and forms evaporating puddle. Leaking Pipeline, chemical is burning and forms a pool fire. Pipeline explodes. Leaking tank (Plant), chemical is not burning and forms evaporating puddle. Leaking tank (Plant),, chemical is burning and forms a pool fire. Tank(Plant), explodes. Leaking tank, chemical is not burning and forms an evaporating puddle. Leaking tank(port), chemical is not burning and forms an evaporating puddle. Leaking Pipeline, chemical is not burning and forms an evaporating puddle. Leaking tank(plant), chemical is not burning and forms an evaporating puddle. After the identification of hazards and likely scenarios, risk assessment was carried out for each of the scenario using the PHAST software. The dimension of the tank taken into account for modelling is tabulated in Table 6.3. The Details of Ammonia pipelines is given in Table 6.4.The modelling was carried out for the study period only, i.e. the climatological data taken into account were for the study period. PHAST models key hazards- toxicity, flammability, thermal radiation (heat), and overpressure (explosion blast force) - related to chemical releases that result in toxic gas dispersions, fires, and/ or explosions. Table 6.3: Details about the Storage Tank Capacity and Dimension Sl. Storage Tank Quantity to be Stored Chemical No. Capacity (MT) (MT) 1. Ammonia (Plant 1 X10,000 10,000 Storage) 2. Ammonia (Port 2 X 15,000 30,000 Asian Consulting Engineers Pvt. Ltd. 6-4

5 Sl. Chemical No. Storage) 3. Phosphoric Acid (Plant Site) 4. Phosphoric Acid (Port Site) 5. Sulphuric Acid (Plant Site) Storage Tank Capacity (MT) Quantity to be Stored (MT) 1 X10,000 10,000 4 X 10,000 40,000 1 X10,000 10,000 Table 6.4: Details of Ammonia Pipeline Sl. No. Scenario Description Pipeline dia in mm Length of pipeline in meters Operating Pressure in barg Operating Temperature in deg C Flow rate in Kg/sec Above ground / Undergro und Material Handled 1. Ammonia Pipeline (Port to Plant Site) 6"* 16 kms 14 Kg/cm2-33 deg C 60 m3/hr or TPH Above Ground Ammonia *Subjected to detail design Modelling Output The modelling output for the identified potential risk scenarios for each of the chemical is given below. Ammonia Storage Tank (Port): Scenario 1: Leaking tank (Port), chemical is not burning and forms evaporating puddle ERPG 1 25 PPM, ERPG PPM, ERPG Scenario 2: Leaking tank (Port),, chemical is burning and forms a pool fire Asian Consulting Engineers Pvt. Ltd. 6-5

6 Scenario 3: Tank(Port), explodes.. Scenario 4: Leaking Pipeline, chemical is not burning and forms evaporating puddle. ERPG 1 25 PPM, ERPG PPM, ERPG PPM Scenario 5: Leaking Pipeline, chemical is burning and forms a pool fire. Asian Consulting Engineers Pvt. Ltd. 6-6

7 Scenario 6: Pipeline explodes. Scenario 7: Leaking tank (Plant), chemical is not burning and forms evaporating puddle. ERPG 1 25 PPM, ERPG PPM, ERPG Scenario 8: Leaking tank (Plant),, chemical is burning and forms a pool fire. Asian Consulting Engineers Pvt. Ltd. 6-7

8 Scenario 9: Tank(Plant), explodes Interpretation of the Modelling Output Around three threat zones have been plotted in the modelling output i.e. Yello, Green and Blue, representing areas of hazard. The range for these threat zones is based on the AEGLs (Acute Exposure Guideline Levels) and ERPGs (Emergency Response Planning Guidelines), which are used default by the software. The threat zone values and the distance of the threat zone from the storage tank (in the downwind direction) is tabulated in Table 6.5. It can be inferred from the table, that in case of formation of evaporating puddle, Pool Fires of Ammonia storage tanks (Port), Ammonia Pipelines, Ammonia Sorage Tanks (Plant site) impacts will fall outside the, on the nearby areas. Whereas in case of Sulphuric acid & Phosphoric acid cases the evaporating puddle in case of leakage will be within the. These chemicals are hence not included in the ALOHA & PHAST Software databases. Asian Consulting Engineers Pvt. Ltd. 6-8

9 Table 6.5: Threat Zone Levels and its Distance from the Storage Tank Chemical Scenario No. Threat Zone Level Distance from the Storage Tank (Downwind direction) in m Yellow: > 750 ppm (60 min) >10,000 Scenario-1 Green: > 150 ppm (60 min) >10,000 Blue: > 25 ppm (60 min) >10,000 Yellow: > 37.5 kw/m 2 (potentially 820 lethal within 60 sec) Scenario-2 Green: > 12.5 kw/m 2 (2 nd degree burn 1020 within 60 sec) Blue: > 4 kw/m 2 (pain within 60 sec) 1340 Yellow: > 0.3 bar (50% Fatality 270 Probability) Scenario-3 Green: > 0.1 bar (10% Fatality Probability) 405 Blue: > 0.03 bar (Mild Impact, <1% Fatality) 775 Yellow: > 750 ppm (60 min) Negligible Scenario-4 Green: > 150 ppm (60 min) 1596 Blue: > 25 ppm (60 min) >10,000 Yellow: > 37.5 kw/m 2 (potentially 167 lethal within 60 sec) Scenario-5 Green: > 12.5 kw/m 2 (2 nd degree burn 220 within 60 sec) Blue: > 4 kw/m 2 (pain within 60 sec) 317 Yellow: > 0.3 bar (50% Fatality 28 Probability) Scenario-6 Green: > 0.1 bar (10% Fatality Probability) 46 Blue: > 0.03 bar (Mild Impact, <1% Fatality) 93 Scenario-7 Yellow: > 750 ppm (60 min) >10,000 Green: > 150 ppm (60 min) >10,000 Blue: > 25 ppm (60 >10,000 Ammonia (15,000 MT Capacity Storage Tank, KCPL Port) Ammonia Pipelines Ammonia (10,000 MT Capacity Storage Tank, Plant Site) Remarks area. i.e effects can area. i.e effects can Within the project area.. area. i.e effects can area. i.e effects can area i.e effects can area. i.e effects can Asian Consulting Engineers Pvt. Ltd. 6-9

10 Chemical Scenario No. Threat Zone Level Sulphuric Acid min) Scenario-8 Yellow: > 37.5 kw/m 2 (potentially lethal within 60 sec) Green: > 12.5 kw/m 2 (2 nd degree burn within 60 sec) Blue: > 4 kw/m 2 (pain within 60 sec) Scenario-9 Yellow: > 0.3 bar (50% Fatality Probability) Green: > 0.1 bar (10% Fatality Probability) Blue: > 0.03 bar (Mild Impact, <1% Fatality) Distance from the Storage Tank (Downwind direction) in m Remarks area. i.e effects can Within the project area.. Scenario-10 Low <100 mtrs Within. Phosphoric Acid (10,000 MT Capacity Storage Tank, Plant Site) Phosphoric Acid Pipeline Phosphoric Acid (10,000 MT Capacity Storage Tank, Plant Site) Scenario-11 Low <100 mtrs Within Scenario-12 Low <100 mtrs Outside. i.e effects can felt outside the project area Scenario-13 Low <100 mtrs Within Note: Sulfuric acid & Phosphoric acid are not volatile enough to be considered an outdoor air dispersion hazard, even though it is hazardous when inhaled. That is, under normal conditions, it cannot enter the atmosphere fast enough to reach concentrations hazardous to people within a large area. These chemicals are hence not included in the ALOHA & PHAST Software databases Safety Measures for Storage of Hazardous Chemicals The existing unit has well developed emergency management plan, which will be also extended to the proposed project as well. Regular mock drills are being conducted to create awareness among the employees about possible hazards and to train them on the way to react during an emergency situation. The safety measures with respect to the identified hazard and assessed risk are given in the following sections. Asian Consulting Engineers Pvt. Ltd. 6-10

11 6.1.8 Fire and Explosion Hazard Ammonia poses fire and explosion hazard. It must be stored in the designated explosive/inflammable storage area. The following measures should be adopted, while the storage of the above mentioned chemicals: Fire alarm system must be installed and regulation inspection of the same should be carried out. The storage tank must have safety valve to release any kind of pressure built up within the tank. The tank must be jacketed. Periodical checking of the containers must be carried out to identify any leakage. The storage tank must be closed to avoid evaporation of the ammonia and ignition of the same. The area must be cordoned off as No Smoking Area and absolutely no source of iginition must be present in and around the storage area. Small spills must be cleaned immediately. Good housekeeping practices must be followed. No combustible materials must be kept in the storage area. Ammonia pipelines to be periodically inspected and Pneumatic pressute testing to be done Ammonia leak detectors to be installed along the ammonia pipeline with automatic shut off provision in order to have a early detection & control Ammonia Pipeine to be provided route markers & caution boards all along the pipeline (Right of Way) at regular intervals Patrolling of Ammonia pipeline path to be done to avoid damages caused by third parties Toxic and Reactive Hazard Phosphoric acid and Sulphuric acid are highly toxic and corrosive in nature. Hence, additional precautionary measures as given below must be taken to avoid any adverse impact on the health of the employee: All employees handling the chemicals must wear rubber gloves, safety google, safety shoes, and adequately covered dress (to avoid dermal toxicity). The nature of toxicity must be labelled on the tanks. Asian Consulting Engineers Pvt. Ltd. 6-11

12 Supervior must conduct regular inspection to check the usage of PPEs by the employees handling the toxic chemicals. First aid training to employees. The storage tanks must have the following: Rubber lining to avoid corrosivity of the storage tanks. Safety valve to avoid accumulation of gas (especially hydrogen gas) in the storage tanks.. Asian Consulting Engineers Pvt. Ltd. 6-12