One of our HDS units is planning on routing their stripper overhead liquid to the crude unit top pumparound (@ the suction of the pump). I would have prefered to route the stream to the slop tank. However, the stream would then back out crude from the crude unit. The stream is at 100F and it...
Do the draws from a Crude tower need to be sized for aerated fluid? What is the recommended length of the self-venting pipe. Could the diameter of the pipe be decreased within a couple of feed from the nozzle?
What is the best location for a tray thermocouple? I have a thermocouple located at the outlet of the tray downcommer. The temperature fluctuates by 10-15 degrees and is hard to control. Should the thermocouple be on the vapor or the liquid phase? In the downcommer where I can guarantee...
The kettle reboiler in our Deethanizer tower has a pretty consistent swing that has been a mystery for the past 20 years. The steam to the reboiler is controlled by Tray 2 of the tower. Every ten minutes this temperature cycles up and down. This wave is strong enough to increase the overhead...
Our depropanizer has flooded condensers. Over the years we have tried to improve the pressure conrol in this tower without success. The last proposed control scheme will control the accumulator pressure with the level in the drum. That is, when the pressure increases, the overhead release...
I was given the task of identifying which exchangers in the crude unit preheat train where fouling. I was lucky becuase I have plenty of thermocouples and flowmeters to calculate the U coefficient of each bank of exchangers. There were 3 banks of exchangers where the U coefficient had...
Has anyone out there experienced salt built up in the Vacuum tower? During "normal" operations our LVGO section pressure drop is ~ 8mmHg. Over time, however, the dP increases! When it reaches 14mmHg, the unit goes thru a salt sublimation process. The temperature in the LVGO section...
I was wondering what other refineries do to optimize their HVGO cutpoint/yield. In my refinery the strategy is to always maximize the heater outlet temperature. I have noticed, however, that the actual yield does not necesarily increase with the higher duty/temp and that sometimes maximizing...
We have and HDS unit that processes 100% coker naphtha (I don't recommend this operation to ANYONE). It has 3 reactors. The 1st Reactor was ment to be for diolefin saturation and it is placed before the furnace. Sometime ago, it was decided to convert this unit to heavy coker naphtha and a...
We have and HDS unit that processes 100% coker naphtha (I don't recommend this operation to ANYONE). It has 3 reactors. The 1st Reactor was ment to be for diolefin saturation and it is placed before the furnace. Sometime ago, it was decided to convert this unit to heavy coker naphtha and a...
I have been told by many experts that the pumparound trays in a crude tower have a 30% efficiency at the most. However, my crude tower simulation shows that the pumparound trays efficiency should be between 45-55% to match the pumparound duty in the middle and the bottom pumparound. In the top...
