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I am currently managing a high pressure water injection triplex pump in a hydro cracking unit. I am plumbed into the unit with my diesel powered pump that has taken place of two electric drive pumps that have failed for undisclosed reasons to me at this time. This particular job was given to my company on short notice and the only information i have received is that this was critical that the unit still perform at at least 50% production and in the event of a failure of the pump I'm operating the best thing I can do is run. If anyone has any experiences with these pumps could you enlighten me to the hazards involved, the use in process, and any down stream side effects on a refinery when they are out of service? Also I was told that within twenty minutes of shut down on their pumps that their unit would cease to function due to salt build up.
 
Answers
22/04/2012 A: Satish Angadi, Haldor topsoe, satish.angadi@gmail.com
20 minutes is in my opinion holds the clue. Does this mean that they are putting less amount of water or they are processing feed with with high N, S and Cl contents.
You may try to do reverse engineering: check
1) injected wash water quantity: check what was recommended by plant designer, how much they are putting.
2) check the salts contents in sour water from downstream of REAC. It should be 4%. NACE allows higher upto 8%, i think. But then see if sour water from cold separator, level control valve will have plugging problems.
More the water, better. Check NPRA papers.
Disclaimer:
This information is not to be used for design.
26/01/2012 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
In the Hydrocracker plant reactors, hydrogen sulfide and ammonia are formed due to various reactions that take place. They combine to form ammonium bisulfide. Other ammonium salts may also be formed. Ammonium bisulfide is highly corrosive in nature and may cause serious hazards due to very fast corrosion and deposit formation as it gets deposited at temperatures existing upstream of coolers. So it is necessary to dissolve it in specific quality of wash water injected properly at suitable rates.
20/01/2012 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
An essential part of the operation is the injection of water in the reactor effluent cooling section of the process. The water dissolves ammonium chloride that forms as the flowing fluid is cooled. This salt is solid and will plug or foul the equipment if not washed away. The fouling is not instantaneous when the water flow is stopped, rather it is gradual. However, if air cooler tubes are plugged with salt, it can be difficult for the resumed water flow to reach the spots where the salt needs to be dissolved. Therefore, it is wise to resume the water injection within a few hours if possible. If your client has observed the effect of water stoppage within 20 minutes, then I would accept their experience for that process unit.
Since the question implies a safety issue, I must state my usual disclaimer: My comments are not intended to be used as the basis for design, construction, operation or maintenance activities.