Introduction
iFluids Engineering has carried out numerous HAZOP and SIL studies across various refinery units as part of revamp, expansion, and greenfield projects. These studies focus on identifying process hazards, evaluating operability issues, and defining safety instrumented functions (SIFs) in accordance with international safety standards such as IEC 61508 and IEC 61511. The case studies below showcase typical findings and actionable recommendations from HAZOP and SIL assessments in refinery environments.
Methodology
- HAZOP Study: A structured methodology was used, involving the latest P&IDs, with standard guidewords (e.g., No, More, Less, Reverse) to identify process deviations, their causes, and potential consequences. Recommendations were generated for improvements based on collaborative input from multidisciplinary teams (operations, engineering, instrumentation, and safety).
- SIL Determination: SIL assessments were performed using the Risk Graph Method and LOPA Method as outlined in IEC 61508/61511. This method evaluated identified SIFs against risks to personnel, the environment, and economic factors to determine the appropriate SIL level for each safety function.
Key Outcomes
- Strengthened alarm systems for better monitoring of critical process parameters
- Enhanced control logic and interlocks to support safer operations
- Improved system reliability through strategic instrumentation upgrades
- Ensured accurate and up-to-date documentation to support process safety
1. IOCL – Benzene Extraction Unit (BEU) Revamp, Panipet
This case study focused on a refinery modernization project in which the Benzene Extraction Unit (BEU) was evaluated for both process safety and instrumentation integrity. The HAZOP study flagged several potential risks such as overpressure, thermal excursions, reverse flow, and level deviations in critical columns and exchangers.
Key Findings:
- Install high/low temperature alarms for enhanced safety.
- Implement redundant level and pressure transmitters in key system areas to improve reliability.
- Enhance interlocks and control loops in critical columns to support safer operations.
- Ensure clear alarm prioritization and operator response protocols.
- A Safety Instrumented Function (SIF) was identified for a high-pressure scenario, confirming that existing safeguards and control measures were adequate and compliant with safety standards.
2. IOCL – PSA Off-Gas Ethanol Plant, Panipat
This case study involved a Pressure Swing Adsorption (PSA) ethanol plant designed to convert off-gas into ethanol. The HAZOP study focused on critical components such as compressors, gas purification lines integrated with upstream and downstream utilities.
Key Findings:
- Gaps in the availability of low-flow alarms across critical system lines.
- Incomplete verification of key safety system components.
- Missing interlocks for equipment shutdown during abnormal conditions.
- Deficiencies in control logic during startup procedures.
In addition, subsystem reviews were conducted to enhance plant safety and operability:
- Improvements to alarm systems and safety interlocks, along with procedural updates in Inoculator Cell Recycle System
- Enhancements in trip logic, valve isolation strategies, and flare line integration in Compressors
- Installation of high-temperature alarms, analyzers, and reliability-focused interlocks in Dryer System
- System refinements including alarm upgrades and flow control improvements in Falling Film Evaporator (FFE)
The safety assessment identified key areas requiring improved alarms, startup logic, interlocks, and system verification. Appropriate safety functions were defined to reduce risks and enhance overall system reliability and compliance.
The study led to the development of actionable recommendations, driving improvements in instrumentation, control strategies, operational procedures, and system integration for enhanced safety and performance.
3. IOCL – Ethanol Plant Package Systems (LanzaTech Process), Panipat
This facility, based on LanzaTech’s gas fermentation process, operates multiple distributed systems including fermentation units, gas handling, distillation, and drying systems spread across various geographical locations. The study aimed to validate safe operation under both continuous and batch modes.
Key Findings:
- Missing override logic for interlocks, particularly in critical sensor prioritization.
- Inconsistent emergency startup conditions across different operating modes.
- Alarm and control logic discrepancies between system documentation and operational logic.
- Safety concerns in key systems due to improper fail-safe states.
- The HAZOP study resulted in focused recommendations, including modifications to control logic, improved interlock validation, updated alarm rationalization, and integration of better system redundancies.
The assessment highlighted the need for stronger alarms, interlocks, and sensor override functions. Improvements were recommended to ensure effective risk reduction dependable operation across the plant’s distributed systems.
Conclusion
The HAZOP and SIL studies conducted by iFluids Engineering have provided critical insights into enhancing process safety and operability within refinery operations. The studies identified significant hazards and operational gaps, and the resulting recommendations have led to improvements in system reliability, safety compliance, and risk mitigation. These actions have optimized refinery operations, ensuring both effective process control and enhanced safety standards.
Enhance Process Safety with HAZOP, SIL Classification and Verification for Refineries
Looking to improve refinery safety and meet compliance standards? iFluids Engineering provides expert HAZOP, SIL classification and verification services tailored for refinery operations.
Contact us to schedule your consultation and strengthen your process safety systems.