Risk Assessment: Tools, Techniques, and Their Applications

21.2 Example Analysis

This example provides the basic steps for performing a thorough risk assessment of a process plant. For this example, the fictitious chemical reactor from Chapter 13, critical functional analysis, has been used as the case. The attributes of the reactor are as follows:

• It is a 5500-gal-capacity batch reactor.
• Three chemicals are combined in the reactor to produce chemical D. These chemicals are chemicals A, B, and C.
• The following amounts of chemicals are stored on-site:
  • 20,000 gal of chemical A;
  • 40,000 gal of chemical B;
  • 60,000 gal of chemical C;
  • 80,000 gal of chemical D.
• The ratio of the three chemicals are as follows:
  • 10% chemical A;
  • 30% chemical B;
  • 60% chemical C.
• Chemicals have to be mixed in the proper ratio for 30 min to ensure a successful batch.
• The reaction is exothermic. For each degree over 300°F the reactor reaches, the quality of the product is reduced. Chemical E is the contaminant produced. The batch becomes 1% chemical E for each degree over the 300°F level.
• Increased temperature can cause a spike in reactor pressure. If the pressure reaches 310°F, the reactor pressure will near the safety factor limits of the reactor. At this point, a rupture disk will break and the gases produced will be directed to a scrubber column.
• The product must have <2% chemical E to be successful.

The fictitious chemicals used in this process and their physical and hazardous properties are provided in Table 21.3.

Table 21.3 Chemical Properties

Figure 21.1 ...