Page 171 - Fluid Catalytic Cracking Handbook

144 Fluid Catalytic Cracking Handbook

* Eliminates concern about rate and compositions of extraneous
streams entering the gas plant because they are not included in
the overall balance.
* Eliminates concern about correcting for end points because the
effluent sample is cut at the desired TBP end point.
* Eliminates concern about obtaining a 100% weight balance.

Disadvantages of Reaction Mix Sampling

* Possible leaks during sampling.
* Possible inaccurate measurement of volume of gas and weight
of liquid.
* Requires qualified individuals to perform the test.
» Requires separate lab to perform analyses.
* Can require special procedures and be expensive.

Recommended Procedures for Conducting a Test Run

A successful test run requires a clear definition of objectives, careful
planning, and proper interpretation of the results. The following steps
can be used as a guide to ensure a smooth and successful test run,

Prior to the Test Run

1. Issue a memo to the involved departments: operations, laboratory,
maintenance, and oil movement. Communicate the purpose,
duration, and scope of the test run. Include a list of samples and
the required analyses (Table 5-1).
2, Inform the units feeding the FCC. The composition of FCC
feedstock should remain relatively constant during the test run.
Flow meters should be zeroed and calibrated.
Sample taps should be checked, particularly those that are not
used regularly.
5, The sample bombs used to collect gas and LPG products should
be purged, marked, and ready.

Data Collection
1. The duration of a test run is usually 8 to 12 hours.
2. Operating parameters should be specified. It should be docu-
mented which constraints (i.e., blower, wet gas compressor, etc.)
the unit is operating against.