CARGO RECIRCULATION AT SEA, ON CHEMICAL TANKERS-- CAPT AJIT VADAKAYIL

CARGO RECIRCULATION AT SEA, ON CHEMICAL TANKERS--  CAPT AJIT VADAKAYIL


The last stainless steel chemical tanker I commanded was less than a year old.

They managed to screw up most of the super-expensive cargo hoses, while doing cargo reirculation at sea ( Kaolin clay slurry )

The ship had fantastic diffusers for the drops and it was NOT necessary to do bottom to top recirc with cargohoses.

Chemical tankers have very little freeboard in the loaded passage and the cargo hoses full of slurry hung up with slings can get very heavy --and with rolling get damaged badly.

There is a saying " Stupid is forever!"

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From: XXXX (Master) [mailto:master.XXXX@gtships.com]
Sent: 04 January XXX 15:09
To: XXX
Cc: XXXX

Subject: RE: XXXX/ ALICE IN CLAY SLURRY

gentlemen,

in july 2010, fairchem yuka carried clay slurry.

to keep the clay slurry from sedimenting—this ship used bottom to top recirculation at sea by using cargo hoses—as per charterers instructions.

this was as ridiculous as, having a computer but using burtons tables to calculate.

nobody knew what the computer could do!!

these cargo hoses are NOT meant to do such gymnastics, tying up with ropes with ship rolling.  they are meant for internal looping at the manifold.

so XXX of the hoses got condemned. 

we now have XX hoses only, instead of XXX brand new hoses ( XXX supply ).

just check out the pictures of the cargo hoses —see how badly they got damaged.

LEARNING TIME –

PL PUT YOUR THINKING CAPS ON --

on XXX we have 16 nos recirculation nozzles.

in scientific parlance this hardware is called DE-AGGLOMERATOR –or—DE-FLOCCULATOR.

now why does clay slurry get sedimented?—pray?

because the colloids are NOT stabilized ( like latex ) to prevent agglomeration.

the electric charge is neutralized.

STABILISING IS ALL ABOUT STATIC ELECTRICITY AND ELECTRIC CHARGES.

when you put egg whites and vegetable oil and beat them in a mixer, you get mayonnaise—it remains so because of electric charges, which keep colloids apart.

when colloids combine they flocculate to form clumps and settle down. heating or centrifuging is one way.

adding electrolytes to remove electric charges is another way—the way they do it for lub oil for easy filteration.

SO WHEN YOU RECIRC CLAY SLURRY BY FORCING CARGO THROUGH THESE TINY ORIFICES—YOU BUILD UP ELECTRIC CHARGE AND KEEPS THE CLAY SLURRY IN SUSPENSION. 

THE COHESIVE FORCES ARE WEAKENED BY AGITATION TOO.

in future in my vision I see CAVITATION nozzles , where the imploding air bubbles will create 2000 bars of homogenization effect.

thanks and best regards

capt. ajit vadakayil

master

mt XXX

master's cabin phone : +870 XXX (Inm F77)-- first call

bridge  phone :  +870 XXX (Sing Tel-FBB ) -- second call

bridge phone: +870 XXX (Inm F77)

fax -  : +870 XXX (Inm F77)

tlx ( sat c) : +870 XXXX 

Email:  master.XXX@gtships.com

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A stable colloidal system is one in which the particles resist flocculation or aggregation and exhibits a long shelf-life.

This will depend upon the balance of the repulsive and attractive forces that exist between particles as they approach one another.

 If all the particles have a mutual repulsion then the dispersion will remain stable. However, if the particles have little or no repulsive force then some instability mechanism will eventually take place e.g. flocculation, aggregation etc.

In certain circumstances, the particles in a colloidal disperson may adhere to one another and form aggregates of successively increasing size that may settle out under the influence of gravity. An initially formed aggregate is called a floc and the process of its formation flocculation. The floc may or may not separate out.

 If the aggregate changes to a much denser form, it is said to undergo coagulation. An aggregate usually separates out either by sedimentation (if it is more dense than the medium) or by creaming (if it less dense than the medium).

The term’s flocculation and coagulation have often been used interchangeably. Usually coagulation is irreversible whereas flocculation can be reversed by the process of deflocculation. The following figure schematically represents some of these processes.

CAPT AJIT VADAKAYIL
29 YEARS IN COMMAND
..