Determination of Safety Integrity Level of a Sugar Plant
using Modified LOPA and Modified Safety Design of
a Vacuum Breaker Valve

Abstract

Nellikuppam Sugar plant is the first Agro based Industry established in India which produces variety of Sugar grades and other sugar related products from raw Sugar-cane. Though it has more than two centuries of expertise in Sugar making process, it still strives hard to eliminate the occurrences of minor accidents and to achieve its primary motto being ‘Zero Incidents’. This work completely focuses on the strength of the safety measures adopted to each and every equipments existing in the plant and estimates the Safety Integrity Level (SIL) of the Nellikuppam plant with respect to Critical Equipments in Mill House and Sugar House. The methodology utilized in determining the SIL value is the Layer Of Protection Analysis called LOPA with significant modifications in its approach. LOPA being the semi-quantitative tool adopted to explore the existing safeguards available in the sugar plant considering the criteria of the Independent Protective Layer (IPL) as recommended by CCPS. LOPA been executed based on the criticality evaluation of the equipments, as this approach being quick and cost effective in the process of identifying the IPLs for the specific hazard which is anticipated for the selected equipments. A systematic procedure has been developed and applied to the critical equipments of the Mill house and Sugar house to demonstrate the advantages and challenges of the prevailing safety system of the plant.
In addition, this paper also deals with the design modification and analysis of the vacuum breaker valve which is one of the IPL for the Critical equipments. With the help of Design by Analysis (DBA) technique, the weakest members of the IPL being evaluated and strengthened to increase the dependability and to remove the anticipated problems of the IPL that could help to operated the IPL safely. Recommendations to improve the effectiveness of the Vacuum Breaker Valve also discussed.