Brief HAZOP Example of an Ammonia Fill Station

4 BRIEF HAZOP EXAMPLE OF AN AMMONIA FILL STATION 

A large, 100 ton storage tank holds the bulk of the plant s ammonia capacity. However, to use the ammonia effectively, it is transferred to a holding tank or ready storage. From the ready storage, the ammonia is dispersed to the various parts of the plant. The distance from the storage tank to the ready storage is approximately one mile. A positive-displacement pump and various control and manual valves are used to transfer the ammonia. Both tanks are fitted with relief valves. 

A dry nitrogen gas system is used periodically to purge the system of contamination. All venting is connected to the unit scrubbers. 

It would be impossible to repeat a full-blown HAZOP here, but this ammonia fill station is a good example to demonstrate the important elements in a HAZOP. It does emphasize various inherent problems found in a typical process unit in a chemical plant. 

Most HAZOP entries are not quite so detailed as this one. However, it is worthwhile to go into some detail here to note some of the liner points of HAZOPs. Because the HAZOP is a systematic review of the design and operation, it is also fairly repetitive. Most of the repetition has been deleted here for ease of reading. Table 6.3 is the one summary report sheet (of various) of the ammonia fill station HAZOP. 

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