(52p) Technique to Perform Petrochemical Complex-Wide Inadvertent Chemicals Mixing and Reactivity Study

Operating chemical plants require the delivery of chemicals from outside sources. According to the US National Association of Chemical Distributors, around 40 million Tons of chemicals were delivered in 2016 to customers every 8.4 seconds. These chemicals may be in any phase or shape like solid, liquid or even gases. Chemicals transported into a petrochemical plant may be used as raw material, catalyst, water treatment or process treatment chemical etc. These chemicals may be hazardous by nature and may even be more hazardous upon unintentional mixing with each other or with process.

Among all the chemical transportation happening in a petrochemical plant, liquid chemicals for water or process treatment are of most interest due to the frequency of makeup, batch process, involvement of human action and hazardous nature of the chemical. Chemicals being transported via pipeline pose a lesser risk on inadvertent mixing and this is studied in detail in a normal HAZOP as misdirected flow etc. Solid chemical pose a lesser risk due to less expected reactivity upon mixing and usually less frequent make up, loading and unloading.

In a typical Olefins complex, the count of chemicals with credibility of inadvertent mixing and hazardous reactivity may go as high as 25 to 30 chemicals. These chemicals include anti fouling chemicals, dispersants, acids, amines and proprietary chemicals. Credibility of inadvertent mixing of chemicals can help to shortlist the chemicals of greatest risk from inadvertent mixing.

Typically, the hazards of inadvertent mixing are studied within the boundaries of individual plants, while ignoring the credible scenarios of cross mixing from Plant A to Plant B within the same Petrochemical Complex.

This paper explains a proven technique to perform a complex-wide study of the chemicals mixing credibility and hazardous reactivity that reveals hidden risks, which may not otherwise be discovered through the typical process hazard analysis techniques like HAZOP of individual plants.