[coker squirrel]

You not only need an Emergency Procedure for Loss of Heater Feed but you also need a Safety Interlock System (SIS) to protect your Heater. You should have it set up to trip the Heater Fuel Gas and inject steam or boiler feed water that would protect your coils from coking up and plugging.

[coker squirrel]

We plan to ensure the feed line possible line is not plugged from decoking by blowing the feed line out with steam prior to closing the Delta Valve. Our feed lines come in at 90° so that should help in that regard anyway. We just had our Delta Valves installed and we are now starting the Unit back up from turnaround so we don’t have any history yet.

[coker squirrel]

I posted this question concerning the Delta Valve. I thought that I was logged on. Has anyone experienced any problems with the Delta Valve feed line configuration? I can also see another potential problem with this gap. When the Drum is put in Warm-up, this area would hold condensate (oily-water). When the Hot Feed is switched into the Drum, it seems to me that this condensate would flash and cause a pressure spike. Has anyone experienced this?

[coker squirrel]

For the best protection, use FRC Sickers. We use Nomex coveralls along with FRC Slickers over that for unheading the bottom head. It is a little hot for the unheading process but it really doesn’t take that long.

[coker squirrel]

Drum skin temperatures alone are not the best indicators for determining whether or not a coke drum has been adequately quenched and cannot be used to determine if there are any hot spots. Drum skin temperatures can be used but there are better indicators for an adequately quenched drum. Some are: < 135°F Top outlet temperature, < 5 psig at the end of the quench and < 1 psig to remove the top head, total amount of quench water used should be consistent, the amount of sour water produced is a very good indicator, and the knowledge of any change in the coker feedstock. Some crude blends produce shot coke, which makes it very difficult to quench. Drum skin temperatures can be also used for other things. We use the bottom skin temperature (< 250°F) as an interlock for removing the bottom head.

[coker squirrel]

Marc, I see that I neglected to answer the other part of your question after posting. Yes, our climate is such that it requires some form of heat tracing. As part of your procedure, you should include to check the heat tracing to ensure it is in working order before taking the pump out of service for maintenance. The suction and discharge lines along with the warm-up line around the discharge valve should all be heat traced. Also, as part of your procedure and line modifications, you need an evacuation line off the top of your warm-up line. It is important to wash out the pump with LGO after isolating it to the evacuation system. If you wash through the warm-up line with LGO, you will not have any problems finding this line plugged when you need it to return the pump back to service. After, LGO washing the pump, you then follow it with a steamout in the same direction.

[coker squirrel]

Yes, we have a 1 1/2″ line around the discharge check valve. And you are correct, we do partially open the discharge valve and crack open the 1 1/2″ valve around the discharge valve. We use the discharge from the companion pump through this line (1 1/2″ check valve bypass – we call it our “warmup line”) to slowly warm up the pump with the heater feed from the discharge of the companion heater feed pump. The key difference here is that we warm up the pump with the suction valve closed. We have installed a new line on the suction side of the pump (located close to the suction valve and within the pump isolation). This line goes up to the wash-zone portion of the Fractionator. If you completely warm up the pump with the suction valve closed through this line to the wash-zone, you will clear the pump and discharge line of all light material that may cavitate the companion pump through the revese flow on the suction line. After slowly warming up the pump this way up to around 400°F, you close the warmup line and then slowly open the suction valve. You then close the new line valve at the pump suction and then slowly open the warmup valve again. This puts the pump into a normal warmup standby mode and is ready to start.
I aslo have a wash header in which I use to clear the pump with LGO for maintenance, steam it out to the evacuation system and also to LGO wash all the associated lines after use. This is completely enclosed system, no hydrocarbon ever goes to the atmosphere.
Using this method, you can start your CHGO or CHLGO seal flush before warming up the pump with heater feed. This is recommended to keep the heater feed from ever entering the seals.
This works every time. No more pump cavitations.

[coker squirrel]

We are installing Delta Valves on our bottom heads next month. I wanted to angle the feed line slightly upward but due to the line retrofit we were only able to go in at a 90 deg angle configuration. We are also slightly worried about impengement on the opposite side of the drum. We were more concerned about the top flange of transition spool piece connection on the bottom head itself. We are going to weld the transition spool piece to eliminate the top flange connection. I have heard both pro’s and con’s to doing this. We feel like we are better off eliminating the flange. Are there any ideas on this?

[coker squirrel]

Limited warm up from the suction to the Blowdown could be a contributory factor but it seems as though from your biggest problem is while starting this pump there is a problem of some sort happening involving the discharge of the pump. Do you also reverse the flow through the discharge line through a warm-up line around the check valve as part of the pump warm up process prior to bringing the pump up on line? How hot do you get the case temperature before putting the pump on line?

[coker squirrel]

Yes. Light material will back through the common suction line when you open the suction valve and cause the companion pump to cavitate. The trick is to warm up the pump prior to opening the suction valve. An added line back from the suction side of the pump to somewhere like the flash-zone can provide a means to warm up the pump.

[coker squirrel]

I used to have that problem. I had a line installed at the suction side of the pump back to the Fractionator wash-zone so that I could warm-up the pump with the suction valve closed. After warming up the pump, you can then open the suction valve and close the line back to the wash-zone then wash this line with CLGO back to the wash-zone so that it doesn’t plug. This works every time. No more pump cavitations.

[coker squirrel]

For loss of heater feed, it is best to trip the heater fuel gas and inject emergency steam into heater feed coils to prevent coils from coking. After returning heater feed service, try to coke for an additional 4 hours before switching out of the drum to mitigate the effect of uncoked resid in the drum.

[coker squirrel]

The Drum inlet valves need to be interlocked with the switch valve to prevent switching into a closed valve. Also, it is a good idea to interlock your switch valve with the bypass and common valves to prevent switching (bypassing) into a closed valve. To accomplish this, you must have MOV operated valves. Valen does provide these type of valves.[&:]

[coker squirrel]

I am also looking for ways to improve cycle time and safety while we are at it. A couple of initiatives that we are currently going after: Delta Valve for bottom unheading and auto-switch drill bits. [;)]

[coker squirrel]

Too much light material in the feed to the Fractionator could cause the Heater Charge pump to cavitate and loose suction. This would trigger a low flow trip on the Heater but this wouldn’t be because of a two phase flow. Some light material in the feed to the Fractiontor could cause an increase in Fractionator overhead make and if uncontrolled could lead to a Compressor shutdown.

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