Problems Using Radios Near Cranes

Initial Email Enquiry –

Has any one of our members come across problems with using radios near cranes? especially with the Gross Over-movement Protection Alarm. If they have could they let me have some more information.

1st Response –

I can't remember such an issue with a crane but we had cases in the past of two-ways radios being used too close to a safety gauge and causing a trip of units by feeding false readings to the TDC system (see example below).

An instrumentation problem caused the regenerated catalyst slide valve to shut fully and the resultant loss of catalyst circulation, followed by reduction in reactor temperature allowed unvaporised hydrocarbon to pass to Regen 1. A thick yellow plume of unburnt hydrocarbon mixed with flue gas and some catalyst discharged from Regen 1 stack for approximately 15 minutes, via the CO burner. During the incident the CO Burner tripped on low steam drum level due to loss of CO in flue gas. The sudden increase in steam demand caused problems for the main refinery boilers resulting in prolonged emission of black smoke and shutdown of the solvent de-waxing unit which has a very high steam usage. When the CO burner tripped, a sudden release of flue gas and hydrocarbon occurred from the main seal tank vent at ground level, necessitating sounding of the refinery emergency siren. No damage was caused to equipment as a result of the incident.

Cause of the Incident The primary cause of the incident was the sudden closure of the regenerated catalyst slide valve. It is not absolutely clear what caused the slide valve to shut. The valve was on auto at the time controlling riser outlet temperature at 528°C. One possibility could be interference from radio frequency signals from hand-held radios sometimes used in the control room. It has been reported that transmission signals can corrupt TDC equipment. There has been at least one other unexplained incident where a controller output wandered for no reason.

End of email correspondence on Topic to date

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