A graphical inherent safety assessment technique for preliminary design stage

Abstract

User-friendly plants are needed for equipment failure to not seriously affect its safety, productivity, or efficiency. Safer and user-friendly plants can be designed through the implementation of hazard prevention strategies during the design phase, which is known as the concept of inherent safety. The Graphical Inherent Safety Assessment Technique (GISAT) for preliminary engineering design stage is presented in this paper. GISAT incorporates information obtainable from the process flow diagram (PFD) in the assessment of inherent safety features of a process. This technique evaluates three inherent safety parameters, namely flammability, explosiveness, and toxicity. GISAT also utilises accident statistics in the construction of its graphical rating as the hazard level indicator for chemical process equipment assigned under five groups—reactor, heat transfer equipment, separation equipment, storage tank, and other equipment. In this technique, quantity of the chemicals involved in an equipment represents the weightage of the assessment that is used to identify the root-cause of hazards in each equipment. Hydrodealkylation process of toluene (HDA) to produce benzene is used as a case study to demonstrate the application of GISAT. The results indicate that heat transfer equipment E102 as safer in terms of flammability compared to other equipment while all equipment were found to be safer in term of explosiveness. Separation equipment V102, heat transfer equipment E102, and recycle gas compressor C101 were found to be safer in terms of toxicity. Meanwhile, heat transfer equipment E101, E102, and E103 as well as gas compressor C101 are regarded as safer in terms of fire, explosion, and toxic release combination type of accident as represented by the GISAT Total Score. After the level of hazard in each equipment have been identified, hazard prevention strategies can be applied to equipment with higher level of hazard for hazard reduction.