Dear Anil,

First have a look at the thread:

https://forum.bulk-online.com/showth...matic+unloader

Your concern about the energy consumption of a pneumatic alumina unloader is probably biased by an image that is widespread because of the fact that a lot of insufficient designs are built.

I made a preliminary quick design of an alumina unloader for a 40000 dwt ship and found the the following results in regard to energy consumption.

Screw compressor: Aerzen 2x VM140 at 6490 rpm with pre inlet:

430 tons/hr at 0.65 bar vacuum – 1.05 kWh/ton

415 tons/hr at 0.47 bar vacuum – 0.92 kWh/ton

Blower: Aerzen 2x GM220L at 1500 rpm:

368 tons/hr at 0.4 bar vacuum – 0.85 kWh/ton

Hybrid blower: Aerzen 6x D75L at 3000 rpm:

363 tons/hr at 0.4 bar vacuum – 0.66 kWh/ton

A screw unloader has disadvantage that, when foreign matter damages the screw, it might be well possible that the whole unloader is out of service for weeks. (experience)

Moreover, alumina is a very abrasive material that wears out the screws.

In a pneumatic conveying system, only the bends and butterfly valves (or pinch valves need attention. (experience)

Straight pipe will last for millions of tons in pneumatic conveying installations. (experience)

Loading bulktrucks can be done with airslides.

Let us know, when you require more information.

Have a nice day

Teus ■

Dear Anil,

Your concern about the energy consumption of a pneumatic alumina unloader is probably biased by an image that is widespread because of the fact that a lot of insufficient designs are built.

I made a preliminary quick design of an alumina unloader for a 40000 dwt ship and found the the following results in regard to energy consumption.

Screw compressor: Aerzen 2x VM140 at 6490 rpm with pre inlet:

430 tons/hr at 0.65 bar vacuum – 1.05 kWh/ton

415 tons/hr at 0.47 bar vacuum – 0.92 kWh/ton

Blower: Aerzen 2x GM220L at 1500 rpm:

368 tons/hr at 0.4 bar vacuum – 0.85 kWh/ton

Hybrid blower: Aerzen 6x D75L at 3000 rpm:

363 tons/hr at 0.4 bar vacuum – 0.66 kWh/ton

A screw unloader has disadvantage that, when foreign matter damages the screw, it might be well possible that the whole unloader is out of service for weeks. (experience)

Moreover, alumina is a very abrasive material that wears out the screws.

In a pneumatic conveying system, only the bends and butterfly valves (or pinch valves need attention. (experience)

Straight pipe will last for millions of tons in pneumatic conveying installations. (experience)

Loading bulktrucks can be done with airslides.

Let us know, when you require more information.

Have a nice day

Teus

Attachments

comparisonpneumaticversuspneumaticalunloading (PDF)

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