Vapor Recovery from Truck Loading 1

[KernOily]

Hi guys. Not sure this is the right forum, but.

Question: What is the typical method/strategy used for vapor recovery of vapors displaced during truck loading? The commodity is light crude oil. The trucks will be bottom-loaded. The connection for the vapor line is on the bottom also, if that matters. Thanks in advance!!

 

[MortenA]

check out cool sorption/Aker

http://www.akersolutions.com/en/Glo...pour-recovery-units-and-systems/Depot-series/

Best regards, Morten

 

[gr2vessels]

In your case the vapor return line is connected to the bottom of the road tanker, but can be in the top or piped externally to an accessible point.
Normally you have an internal pipe in each compartment open in the tanker vapor space and continued outside of the compartment(s) to a common API coupling for vapor return next to the API filling couplings on the bottom of tanker. The loading station has a vapor return line piped back to the storage tank. The vent line is interlocked with the filling line, so you cannot start filling unless the vapor return line is connected to the storage tank and the grounding cable is connected to the tanker. This is a standard 'loading arm' station for road tanker filling. The grounding line is also an instrument conductor for the filling rate monitoring, the over-fill protection and net transfer control. The control system is either a complex, SCADA like system or a simple local control panel and batch controller, containing all the standard controls and interlocks. Most of the local controllers are standard, off-shelf purchase items, but require programming and connection to the plant monitoring system. The internet is full bursting with relevant info, everyone wants to sell you components or up to turnkey filling stations.
Cheers,
gr2vessels

 

[dcasto]

either refrigeration or adsorption.

 

[KernOily]

Guys - Thanks for the great replies! Pete

 

[KernOily]

OK another dumb question. I will be unloading trucks into floating roof tanks. Floating roof tanks have no vapor space. So how do I equalize the vapor space in the truck if I don't have a vapor space in the loading tank?

The diagrams I have seen thus far all show the vapor space of the truck connected to the vapor space of the unlosding tank, this done to equalize the pressure inside the truck. This won't work if the truck is being loaded from a floating roof tank.

I really need a Truck Loading 101 class or a primer. I have searched everywhere and haven't found anything. Thanks guys!

 

[LittleInch]

You fill the vapour space with very low pressure inert gas usually supplied by the facility. This is commonly nitrogen, CO2 or I have heard of the exhaust gas from the tanker engine being used. To unload you will need a pump to fill the tank unless you've got a lot of gravity on your side, so the facility should have thought of this and supply inert gas for the vapour space. The key is the phrase very low pressure. This is probably low millibars for trucks.

If it is non hazardous liquid that doesn't create a hazardous vapour then you could just use air, but floating roof sounds like hydrocarbons to me so air is a complete no no.

My motto: Learn something new every day

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

 

[KernOily]

Thanks LI. Much appreciated. Yes I am supplying an unlaoding pump on the unloading islands. We will bid out the unloading islands to the Carbis/Saferack/etc. guys as a skid package.

Yeah - Can't use air to equalize the trucks since the commodity is crude oil.

So then what is the typical method for the inert gas to get to the trucks? Do I just furnish a bottle rack with N2/CO2 bottles, some let-down regulators, and piping to connect to the unloading islands? Then the CO2 piping just connects to the vapor line on the truck I assume?

Thanks brother - I owe you a cold one!

 

[LittleInch]

More or less yes, but beware of the cold vapour you might get when expanding to near atmospheric. I have seen exhaust gas from an engine used before now as this is readily available where as your n2 or co2 will start to cost you money.

You might want to create a small pressurised (2 to 3 barg) tank to allow the easy movement of large low pressure volumes.

My motto: Learn something new every day

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

 

[chicopee]

If I remember correctly from researching this matter some 15 years ago when we were removing our underground gasoline tank, NFPA allowed engine exhaust as a blanketing agent.

 

[KernOily]

Thanks for the replies guys.

In reference to the engine exhaust method, I have not fouind any connections or hardware (e.g. OPW) that would permit this. The truck would have to be set up with an exhaust connection of some type so the driver can connect the tank vapor line to the exhaust line. Also I believe the pressure would have to be regulated osmehow because the backpressure ont he exhaust can't be allowed to exceed some value before the engine starts to run poorly.

 

[gr2vessels]

KermOily,
All you need is a correctly sized vent/vacuum relief valve fitted with a flame arrester. Talk to the manufacturers of road tankers fittings, they have the correct type and size of those valves, including the ones used for crude oil transport.
Cheers,
gr2vessels