[Nor Syamrin Wagirin]

The furnace coil outlet temperature can be controlled either through TC-PC or TC-FC cascade configuration. Each configuration has its advantages. The main advantage of TC-PC cascade control is in term of safety, as most furnace shutdown is tied up with fuel gas burner pressure. As for TC-FC cascade controller, some say it is easier in term of tuning, as it is not heavily affected by the number of burners online.

[Nor Syamrin Wagirin]

keep your inlet line flush with quench water all the time to avoid plugging of inlet line..

[Nor Syamrin Wagirin]

10-15mins for liquid hold-up for feed surge..

[Nor Syamrin Wagirin]

keeping the quench water running into the inlet line during drilling will keep the line clear.. blow the line with steam prior closing..

[Nor Syamrin Wagirin]

we use auto-switch combo cutter.. switching cutting mode from main cutting-mode to pilot-mode has seemed to help whenever we had stuck drill stems..

[Nor Syamrin Wagirin]

the key is to maintain the normal passes at slightly higher coil outlet temperature.. 2-3oC

[Nor Syamrin Wagirin]

our drum is drained and vented (at the end of quenching cycle) to atmosphere at the coke drum ovhd pressure and temperature of about 1kg/cm2g and a70oC (or below).. the drum is opened when pressure is less than 0.05kg/cm2g..

[Nor Syamrin Wagirin]

the crossover temperature is in the region of 370-380oC.. what is the right velocity? how much velocity steam should be maintained? 

[Nor Syamrin Wagirin]

the velocity steam @ 760F is introduced at the double fired heater.. the furnace inlet temperature was recently raised from 540F to 600F.. could this contributed to the higher fouling rate observed at the top radiant section?

[Nor Syamrin Wagirin]

are you referring to the amine absorber? we had bad experience on amine foaming few years back.. we found that condensible hydrocarbon (c4+) in the amine absorbers contributed to the foaming.. try to impove c3+ recovery upstream.. besides, poor amine quality i.e. low strength, high stable salts content would also leads to foaming..

[Nor Syamrin Wagirin]

how is your cooling rate like? initial, middle and end?

[Nor Syamrin Wagirin]

how do you handle vacuum resid that low asphaltene satbillity index? how do yuo keep asphaltene soluble and did not floculate out in the furnace? Have anyone try chemical to avoind foulant in the furnace?

[Nor Syamrin Wagirin]

thanks all for the input.. does anyone uses the blowdown settling drum water for quenching? if yes, what is the limit in temperature at coke drum when intorducing this water? we’d recently switch to open top tank (by incident), what we see is that the the water tank accumulates some oils (over the time), which we perform daily skimming. We are thinking of using demulsifier in the the settling drum to help separate water and oil. Any good chemicals?

[Nor Syamrin Wagirin]

we run the furnace outlet temperature at 910F earlier in the cycle, within 1hr after drum switching, to avoid too much firing in the furnace. our coker is a two drum coker, which we experienced some temperature swing during drum switching, causing the furnace inlet temperature to drop. As the coke drum heats up, the furnace COT is increased to its normal operating temperature of 920F.

[Nor Syamrin Wagirin]

we had earlier problem to our ovhd condenser even with wash water. upon investigation, the problem is contributed due to poor distribution on the wash water. during the recent shutdown, we had modified the wash water distribution system.

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