Pumpback Loop to Storage Sphere
Pumpback Loop to Storage Sphere
(OP)
Hello,
I saw a pumping system that utilizes a pumpback loop to the storage sphere at all times for normal pentane. The pump transfers the pentane to an end source also, but always utilizes the line back to the sphere. What is the reason for this? Could it be:
1. always mixing the pentane (no stagnent pentane to heat up in the sphere in warm conditions).
2. heat from stopping the pump could cause pentane to vaporize causing cavitation in the pump.
Any other reasons or which of these are correct in your engineering opinion?
Thanks.
I saw a pumping system that utilizes a pumpback loop to the storage sphere at all times for normal pentane. The pump transfers the pentane to an end source also, but always utilizes the line back to the sphere. What is the reason for this? Could it be:
1. always mixing the pentane (no stagnent pentane to heat up in the sphere in warm conditions).
2. heat from stopping the pump could cause pentane to vaporize causing cavitation in the pump.
Any other reasons or which of these are correct in your engineering opinion?
Thanks.





RE: Pumpback Loop to Storage Sphere
Your #2 reason is just one of the main scope reasons. I doubt if #1 is part of the original scope. The reason I say this is that you identify the fluid as Pentane and I believe you are mistaken (or this is a typo error) - or the spherical tank is being used provisionally for storing this relatively “heavy” hydrocarbon. I say relatively “heavy” because even lighter hydrocarbons like butane and propane don’t “earn” the privilege of being stored in a sphere. Spherical tanks are very expensive storage units and are usually reserved for much lighter hydrocarbons.
If I were allowed to employ a physically strong (good pressure containing feature) tank like a sphere to store Pentane, I could easily justify a substantial Nitrogen blanket and the assurance that the Pentane in the sphere is always in the liquid state. Therefore, I wouldn’t be concerned with “stagnent pentane to heat up in the sphere in warm conditions”. Even if there were no N2 blanket, the sphere can easily absorb the higher vapor pressures to maintain the Pentane in the saturated, liquid state.
What is probably one of the main reasons employed in the original scope is that the transfer pump’s total capacity is such that it requires flow control and there is a need also to avoid a dead-head condition on the discharge. A recycle back to the tank is always a sure and safe way to provide those needs.
RE: Pumpback Loop to Storage Sphere
RE: Pumpback Loop to Storage Sphere
A much better application for this service is a multistage vertical turbine pump. While more reliable and much more efficient, they require significantly more capital cost. Oh yea, they still need the minimum flow line back to the sphere.
RE: Pumpback Loop to Storage Sphere