Pumping Rates to/from Truck and Rail Loading/Unloading Areas

[jmk0407]

I am trying to size pumps from a tank farm to truck and rail loading areas for jet fuel/diesel bulk storage. Are pumping flow rates to/from truck and rail loading and unloading stations simply based on the time to fill or empty a rail car or tanker? If so, is there a rule of thumb for how fast these should be loaded or unloaded? Are there other factors that also come into play (maximum size of tanker truck hose connections, etc.)?

Thanks for your help

 

[MJCronin]

Here is my two cents:

- Pumping rates should consider the number of trucks "on station" and the nature of the liquid pumped.

- Many smaller trucks with approximately 4200 gallon ( 100 barrel) capacity should take 30-45 minutes to load or unload. This roughly translates into pumps that are between 100 and 150 gpm

- The larger tanker trucks, typically used with jet fuel and diesel, can run to 12000 gallons and will take significantly longer.

Be aware that there are also vapor return lines that must be attached and removed from these petrochemical trucks that will slow down the filling cycle

 

[LittleInch]

Loading and unloading rates dependson many things. Critical is the vapour inlet / exit rates and handling capacities. Many a rail car has collapsed due to pump out rate exceeeding gas (air) inlet rate. None of these tanks are rated for even a slight vacuum. Many systems don't have pumps but simply use gracity instead or pump via an atmospheric buried tank with vent aboive the high liquid level to prevent the pump creating a pressure lower than atmospher if the vent became blocked or was not opened properly

Loading hoses and connections are also typically your key factor as you need to limit flow velocity to prevent surge and excess static electricity, especially in diesel to around 5 to 6 m/sec. You're normally looking at 3" or 4" loading hoses and conneections for trucks, maybe 6" or 8" for rail tankers.

When you had a single dip pipe going into top loading tankers, you were probably looking at 35 to 40 minutes to load a 28,000 litre multi bay tanker. With multiple bottom loading connections - maybe 20 to 25 minutes. I've seen unloading rates from rail tankers of an average of 80-100 m3/hr each, using a gravity fed tank.

Keeping the liquid relatively still in the vessel while loading is also important to prevent excessive vapour, spilling and hence fill and discharge rates are established over time to be a practical time that doesn't creat huge velocities or vapour volumes, but completes the operation in a reasonable time.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[PieterStander]

The loading and unloading of tank trucks and RTC's has a couple of considerations.

The velocities of hydrocarbons through a certain diameter pipe should generally not exceed 6m/s, i.e. on a 4" pipe you should not exceed 3000l/min, 3" 1500l/min, 6" 6500l/min.

Then there are the vapour release/induction consideration, on tank trucks there are usually a plate that gives you the the max flow rates, I have not seen this exceed 3000l/min loading and 1300l/min un loading.

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