Re: Increasing Volume Within Bulk Tanks
Vladimir could put you right regarding marine Classification Societies requirements, I'll bet.
From simple pressure vessel considerations:
You will be carrying more mass in the tanks & so the support saddles would have to be design checked as well as the shell.
If your (pressure) vessel was also designed for "full vacuum" you are in the clear. It probably is designed to cover full vacuum under the ABS classification, but you'll have to check. In any event you will need a snifting valve or similar relief.
Maybe your Classification Society requires permanent onboard vacuum raising plant, they should. This will take up space & cost a lot of money compared to it's intermittent operation. OK, so do winches. Adequate vaccum plant will require small liquid ring pumps, which are level height critical, possibly plus heat exchangers for the pump working fluid.
If the technology exists you should search further down the line because the benefits for casing grouting crews would be considerable.
Best of luck. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Densified Filling
The basic problem with cement and similar fine powders is that they entrain air in the dilated state of filling and this is slow to escape from the bulk, so that the initial stored density is low and the powder tends to behave in a fluid condition, which can also raise problems with swilling about in road tankers as they accelerate and brake. Dropping the powder down a convoluted wall vertical loading spout is certain to produce loose bulk conditions, whereas careful design of the off-loading equipement can deliver the material is a higher density condition by way of good feed equiment to focus the flow stream and minimising free fall into the vessel.
Filling under partial vacuum will maximise the filling density, but is a bit awkward to arrange. A simpler method is to fill in the normal manner and then connect a local, mass flow hopper that doubles as a vacuum vessel to draw out excess air quickly. The space created can then be topped up with fresh material and any dust drawn up into the hopper drained back to the receiving vessel. I doubt if the holding capacity can be doubled, but a very useful weight increase can be gained. One drawback is that the condition of the bulk material in the vessel is then much less free flowing and consideration has to be given as to whether it can be discharged easily. ■
Increasing volume within bulk tanks
I have a supply vessel transporting bulk cement and barite to offshore oil drilling rigs. The problem is that space is limited with an ever increasing need for more product. It appears that there is new technology for tanks to store more than twice their normal volume if the product is stored under vacuum rather than under pressure. If anyone knows about this technology, I would like to learn how and if my 40 psi 1,000 cu. ft. tanks could be converted to the vacuum type storage. Also, how would the delivery system operate? ■