Ballast system troubles

[Newtothis]

Could someone please explain to me how the ballast system works, It has a vacuum priming unit and a stripping ejector and I'm not so sure how these work together... I think I understand the basics but the crews terrible English language skills are getting me no closer to understanding lol. Ive had the books out and read my college notes but there is no mention of these components and I would just like to know a bit more... Any help is appreciated

[thebrookster]

Without any knowledge of your system, it is very hard to give an explanation, however I shall give a possible scenario, based upon the names.

A vacuum priming unit sounds like the primer for the main ballast pumps. You should have these fitted, I guess. Will be big buggers, they can normally shift a lot of water pretty damn quick!! Normally a ballast pump would be a centrifugal pump (at least the ones I have seen were), which needs priming before it will work. This will be the job of your vacuum priming unit I guess.

The stripping pump sounds like it should be a second pump, which is used to get the remnants out the tanks. At least, that was what stripping was on the tankers I served on. So I would guess this pump is used once the tank levels drop to a certain level.

As I said, hard to say without more details. Can you at least give us an idea what type of ship you are on? There maybe someone here who has sailed them before, and can answer more accurately than my guess!!

[Newtothis]

Thanks for replying, im on a general cargo ship, 190 metres length, 41880 DTW, it was built in 1982 so as you can imagine, the systems may be outdated ! I just want to know where the stripping ejector sits in the system really, as I hadn't heard of one until I arrived. So you reckon when the ballast tanks get to a certain level, then the stripping ejector will start and deballast them completely ? Is that normally the case?

Thanks again for replying

[Chiefy]

No...basically ;-)

Right the vacuum unit is there to help get suction on the ballast pumps as stated previously. Especially if sucking form tank to sea.

The eductor will be manually used, and only used for stripping out the tanks, all tanks have an unpumpable "bit" left in them, most of the time people will leave that in the tank as it does no harm BUT if you wish to do tank entry or any work in the tank then you may educt or strip them till they are very very empty ;-)

The eductor normally uses some form of driving water (ballast pump going sea to sea) and then through a venturi to create a suction which you then line up on the tank you want to strip. This has the advantage that the pump is never run dry and if the tank is totally empty and you suck in air it causes no damage.

Oh and for the record a ship of that age isnt really that old.....there are old and technology really has not changed that much in about 100 years

[Newtothis]

Ah right, now i get it! Thanks Chief! So the ballast water is pumped straight from the sea to the required tank, or from tank to tank, with valves controlled from the ballast room. When deballasting, does the water need to be passed through any sort of filter or oily water separator? or can it be discharged straight overboard?? Sorry about all the questions, i'm just getting to grips with it lol.

[ETwhat?]

no need for an oily water separator, it isnt sharing cargo tanks and it has come from the sea in the first place, plus the sort of rate these pumps work at is much higher than an OWS will cope with. They will do ballast exchange depending on the route, this replaces near coastal water with edge of ocean water and vice a versa, the idea is to stop the transport of alien creatures from one enviroment to the other.

[thebrookster]

Chiefy is quite correct, IF you have an eductor!!

The Eductor is one method of tank stripping, you may also have a PD pump of some kind fitted instead.

Now, in terms of ballast water cleaning, ETwhat? is correct for the time being, however a lot of work is currently going into ballast water cleaning! The shipping industry has caused a fair amount of damage to water systems (not intentionally I hasten to add!), as the sea water around Africa holds different wee bugs etc to say that in the North Sea. Ballasting has moved all this life all over the place, with differing side effects.
The big issue they are having is using a filtration system slows ballasting, which therefore slows loading times, which increases time in port, which of course increases costs all over. My last company, Knutsen, were making big moves in this area, with a system they called KBAL, of which one of the prototypes was installed on one of the ships I was a cadet on several times. No idea what happened with this in the end, was undergoing a whole whack of testing whilst I was onboard (we shall not mention the modification myself and the C/E planned to do to a sampling pipe, which was delayed slightly because neither of us could work out how to turn the damn welder on!! ).

[Chiefy]

ah ballast water management....oh ye indeed, we have that here, Alfa Lavals system as you ask, basically a B&K filter with uv lights for anti bacterial purposes.....it is one of many gaining traction and acceptance ;-)

[thebrookster]

This is a vague link about the KBAL system, appears according to this website it is still waiting final approval.

The big selling point the KBAL system has, if it is approved, is that it can be fitted with a minimal alteration required to the ship, so it can be easily retro-fitted within the usual 4 weeks of dry dock.

http://www.ballastflow.com/homeindex.html

[Chiefy]

4 weeks of dry dock? Who the bloody hell do you work for? 7-10 days MAX dry docking with this mob, strewth...luxury 4 weeks.....

[GuinnessMan]

ah ballast water management....oh ye indeed, we have that here, Alfa Lavals system as you ask, basically a B&K filter with uv lights for anti bacterial purposes.....it is one of many gaining traction and acceptance ;-)

Ah, this is something I've had the "joy" of looking into for the last few months....

After researching all the different technologies and all the different plants, laws, etc I would stay as far away from UV systems as possible. Reason being is that they don't actually kill any organisms within the tank, they only make them "non-viable" and that may not be enough to satisfy the Americans as they were saying that organisms must be dead (not to mention that massive power requirement that a UV system has). Now that only really leaves a Chemical based system, but even they are having difficulties at the moment as quite a number have been found not to work in Fresh Water, some won't work in Water below 10C, etc, etc. It's come to a point where the best system I saw available (the Wilhelmsen one) was pulled off the market as there were too many flaws within the product.

Now when it comes to getting the best system, I have been looking solely at systems that are approved for use in America as they have the most stringent regulations, and at the moment, there are only about 6 companies who have put their systems up for approval to the USCG (as they've taken control of the whole issue from various states, so no Calfornian or New York requirements nonsense). It's all still a work in progress, but if you're looking at interesting systems, I would point you in the direction of Balpure as theirs seems to be doing the best for the moment....

[Chiefy]

ahhh but alfa laval has both filtering and uv which I believe meets us requirements, you filter and uv when ballasting, and uv only on de-ballast, I wouldnt call 72kW for a 500mt/hour system that big a power requirement, but then we do have 17MW of power available ;-) Go Reefer boats :-)

[thebrookster]

Chiefy, I am used to Oil Tankers that need full vetting etc etc, as they operate as DP Shuttle Tankers. My experience (having done two) is they drydock for roughly 4 weeks when doing their 5/10 year surveys, so I may have a skewed view of drydocking

[GuinnessMan]

ahhh but alfa laval has both filtering and uv which I believe meets us requirements, you filter and uv when ballasting, and uv only on de-ballast, I wouldnt call 72kW for a 500mt/hour system that big a power requirement, but then we do have 17MW of power available ;-) Go Reefer boats :-)

Nearly all the systems have a pre-treatment filter! The main reason I liked the Wilhelmsen system was because it didn't just filter and dose, it also ripped apart the wee beasties before dosing using a device similar to a washing machine! I also deal with Chemical and LNG tankers, so these things don't tend to have that kind of power available! Besides, I still have my reservations about UV and the US as the suppliers I know going for their approval so far have all been Electro-Chem systems...

Chiefy, I am used to Oil Tankers that need full vetting etc etc, as they operate as DP Shuttle Tankers. My experience (having done two) is they drydock for roughly 4 weeks when doing their 5/10 year surveys, so I may have a skewed view of drydocking

4 weeks!? With the exception of the LNG tankers we don't do 4 week drydocks, normally it's a maximum of about 14 days and thats really pushing it!

[thebrookster]

Maybe I have a skewed view, thinking back on it, one ship they dockyard broke the Bow Thrusters (seals in the wrong way) which increased the time slightly, and the other ship was being 'upgraded' to DP2 spec, along with having the KBAL system fitted, which could account for timing. (She was theoretically converted to DP2 when she was first converted to Shuttle, having been a Chemical tanker before, but reality was she only needed DP1 for her charters. When they then looked at using DP2 and getting the relevant certs, they discovered some pumps etc that were on the "wrong" busbar )

The KBAL I think worked on a similar basis to what you say for the Wilhelmsen setup, cept they 'dropped' the water from deck level to bottom, with a venturi of some sort to increase speed which smashed said little beasties quite nicely. Didn't pay an enormous amount of detail to the rest, as I get sidetracked with the C/E into peering through microscopes at said little beasties
The bit that was most interesting tbh was working with the two C/E's in doing various modifications etc, and getting to learn stuff I might otherwise have missed. The bulk of the rest of my training was with Filipino's, so language was a bit of a barrier to asking the more detailed questions for the why's and wherefore's, a British and a Norwegian C/E were better pickings! (I was originally going to do a Physics degree, until a car crash put paid, but I still prefer to understand things to a far higher detail than a ship's engineer might normally need to! I was very lucky to have some officers who had a similar level of interest!)