[coked]

Yes, we had tried the same method. We steamed the drum for 24 hours. Then introduce water in and drain it out. Draining would be a good indication on what to expect during unheading. If there is no issue during draining, then unheading the drum should be ok. We took precaution during unheading with operators on pyrosuit. Fortunately, unheading was ok. 

[coked]

im sure you would have changed your entry to side entry. Was it a single or dual entry? There have been cases where quenching was not sufficient in single side entry.

[coked]

we have been monitoring the NH3 and Sulphide content on the overhead. Typical value are in the range of 1500 – 2000 ppm. Is this normal or on the high side?

[coked]

we had run at 910F before due to high skin temperature (towards end of run). We normally run higher COT at start of run and gradually reduce it towards end of run to sustain furnace operation. however, we keep monitoring our vcm and coke quality.

[coked]

Shot coke tendency depends on the MCR (micro carbon residue) as well. As long as the ratio between asphaltenes and MCR are below 0.6-0.5 normally it wont be shot coke. 

[coked]

well i heard from flowserve that the best practise will be to do a cone cut on the bottom then proceed with cutting from top. However, depends on the type of coke that you are making. Shot coke have higher tendency for cave in. Thus, top to bottom more advisable. 

[coked]

We had been processing asphaltenes as high as 18%. 

[coked]

well there is a curve where increase the recycle ratio will improve your fractionation cut depending what is the fluid for recycle. However, recycling too much will not really give you much benefit. Trend your history/do a test run in getting your optimum recycle (with max yield on your desired liquid yield)

[coked]

We set the online spalling limit at 1184F (P9 tubes) and during the spall, increase the temperature to 1250F and spall for approximately 24 hours.

[coked]

Have you checked if the opening hunting as well? i would get the transmitter calibrated and if the opening is hunting as well, you might want to get them serviced. 

[coked]

in our DCU we constantly have this problem whenever the vacuum unit upsets. The first indication will be on the charge pumps where the amps will go high. The overall gas make will be a higher resulting in system pressuring up. This would overload the overhead condenser and increase compressor inlet gas temperature. Further increase will trip the compressor.
The only mitigation plan we would have to reduce feed whenever we notice there is an upset or the charge pumps going up.

Regards.

[coked]

depending on experience, the vr properties also plays a role in determining the heater run lenght together with good operation. We had seen cokers with somewhere 2 months to 1 year before going into spall. 

[coked]

We had the same problem with sagging tubes. We check on the burners and replace those that have pinching flames. We also included a routine thermal inspection on the tubes to make sure there is no hot spot. 

[coked]

The usage of antifoam very much depending on the velocity of vapor inside the coke drum. There was a point of time when we had to inject a lot more to supress the foam with a shorter cycle ( as fr us it means more feed pushing through the furnace and coke drum).

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