Daialos:
Please refer to the attached quick and very basic sketch.
A vapor balance type of liquid transfer is a universal system used when dealing with toxic, flammable, or expensive vapors related to the transferred liquid. It allows you to transfer the liquid fluid as fast as you want without any problems of trapped vapor or pulling a vacuum in your source tank. It essentially replaces the pumped out liquid in the source tank with the vapor in the target tank. Both the target and source tanks are kept at the same pressure. Many compressed liquids – such as ammonia, carbon dioxide, LPG, and others are transferred in this manner every day. I’ve even transferred liquid phenol with this system. As with everything else, you should expect a tradeoff for eliminating all emitted ethanol vapors. For example:
- You will have to standardize all your tanker trucks transporting your ethanol out of your plant to be equipped with a standard filling dip pipe that suits your established filling system. This is something I’ve found to be not a problem when discussed with your transporter, who should be happy to eliminate all dangerous vapor fumes while exposed to filling. If you own your transport tankers, then this is even easier to arrange.
- You will need to install a vapor line on your storage tank(s). If you are filling from various tanks, then this calls for a vapor balance header with block valves on each tank. If you have a common pressure establish on all your storage tanks, then this is even easier.
- I don’t know how you presently meter your ethanol filling operation. I presume you are weighing your vehicles while filling. If so, you should have no problems with this system. If you are using a visual check while filling, the method will require you to have level detectors. This is a problem where operations are run on a very low cost level and the operation is manual. This type of old fashioned operation does not allow for vapor emissions control and has to be modernized in any event if current regulations on emissions, safety, and costs are to be implemented.
I don’t have any basic data on your installation so that’s all I can furnish. I hope this helps you out.
Ethanol Tank Truck Filling.xlsx 17.16KB
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