Working on a study of water treatment system to meet the 15 ppm FOG needed for overboard discharge. Not looking for the old salts to hand me a paper but would appreciate inputs on:
I can research from there. I began googling companys and systems but it’s hard to determine the industry leaders from slick web pages found on line.
Most common units I’ve seen offshore are the Helisep 1000 and 2000 OCD models by Coffin.
Well, there’s Hamworthy (Warsila), Alfa-Laval, Coffin, Asian knock-offs of same. Almost all work on the principles of coalescence. Some of them add chemicals to help break emulsions, others have secondary filtration.
Project? Or just curious?
That’s what I needed. Looks like the Heli-sep is a centrifigual coaelesor which makes sense. A gravity clarifier, even with emulsion breaking additives (polymetric or ferric salts) are probably poor choices on a ship.
Was thinking micro or ultrafiltration might also be effective. These are tangential flow membrane systems which would not be operationally affected by the roll of the ship. Only down side I’ve found so far is they are energy intensive.
Good stuff guys.
[QUOTE=Jetryder223;82213]Working on a study of water treatment system to meet the 15 ppm FOG needed for overboard discharge. Not looking for the old salts to hand me a paper but would appreciate inputs on:
I can research from there. I began googling companys and systems but it’s hard to determine the industry leaders from slick web pages found on line.[/QUOTE]
I’m more than happy to assist you and I might have the information you need! Oil Filtering Equipment is one of the most common detainable deficiencies during Port State Controls and the test standard for Bilge water separators (MEPC.107(49) could have been so much better. The fact is that many separators on the market are designed to comply with this test standard and not to shipboard conditions.
Please feel free to contact me on info@cleanship-scandinavia.com.
Our two biggest boats use the alfa laval purifers, with some jap OCM and display. The office has been buying a new brand for the rest of us lately and they work really well. We have 2 ROV’s on board, so we get huge volumes of waste water from the ROV LARS. Between the manit on the ROV’s and everytime it rains the LARS is just a huge pan that catches everything, they send all the rain water down to us to process before going overboard.
The new systems we have been getting are called Boss 107, from recovered energy. They are a coalescing type system with a pre-filter. They are rated in different tonnage and flow rates. they have a Deckma Hamburg OCM and OMD, we have had good luck with them so far. An older coalescing system I used to see on the tugs was a bilge boy. They never worked worth a dang though!!!
[QUOTE=Jetryder223;82213]Working on a study of water treatment system to meet the 15 ppm FOG needed for overboard discharge. Not looking for the old salts to hand me a paper but would appreciate inputs on:
I can research from there. I began googling companys and systems but it’s hard to determine the industry leaders from slick web pages found on line.[/QUOTE]
Interesting! Oil Filtering Equipment is one of the most common detainable deficiencies during Port State control and the test standard specification MEPC.107(49) could have been so much better. Many OWS on the market are designed to comply with the test standard and not shipboard conditions.
Anyhow, I might have the information you need, so please drop me an email info@cleanship-scandinavia.com
I worked on a vessel that had what we called a “steam-out tank”. Worked on the principle that it its a whole heck of a lot easier to remove the water from the oil, rather than the oil from the water. Pumped our bilge holding tank up to a tank on deck heated by steam coils (fed from our EGB or aux boiler) and kept an eye on the vent up top. Once it stopped puffing moisture clouds we knew all the water had been removed and the tank was drained to the slop tank. The difference in soundings in both tanks (BH and Slop) before and after gave us an accurate record of how much water was removed. Underway we could easily dispose of 1 cubic meter of water a day (only ran for 12 hours a day during the 2nds watch). Arguably that’s a lower and slower rate than some of the “stated” capacities of the traditional OWS units but in my opinion its easier, simpler and there is a zero chance for an accidental discharge overboard. I am aware that few boats in the gulf have a steam supply readily available however the principle would work equally as well with electric heating coils. If I had the choice on a new build or retrofit, I would get a cheap and simple traditional OWS to satisfy the CFR’s and CG inspections and a nice steam out setup to use as the workhorse in processing bilge water. The newest ORB’s already have a method listed for recording and logging bilge water processing using an “evaporation” technique (wording might be different but the principle is not).
[QUOTE=Ryan.Gannon;82310]I worked on a vessel that had what we called a “steam-out tank”. Worked on the principle that it its a whole heck of a lot easier to remove the water from the oil, rather than the oil from the water. Pumped our bilge holding tank up to a tank on deck heated by steam coils (fed from our EGB or aux boiler) and kept an eye on the vent up top. Once it stopped puffing moisture clouds we knew all the water had been removed and the tank was drained to the slop tank. The difference in soundings in both tanks (BH and Slop) before and after gave us an accurate record of how much water was removed. Underway we could easily dispose of 1 cubic meter of water a day (only ran for 12 hours a day during the 2nds watch). Arguably that’s a lower and slower rate than some of the “stated” capacities of the traditional OWS units but in my opinion its easier, simpler and there is a zero chance for an accidental discharge overboard. I am aware that few boats in the gulf have a steam supply readily available however the principle would work equally as well with electric heating coils. If I had the choice on a new build or retrofit, I would get a cheap and simple traditional OWS to satisfy the CFR’s and CG inspections and a nice steam out setup to use as the workhorse in processing bilge water. The newest ORB’s already have a method listed for recording and logging bilge water processing using an “evaporation” technique (wording might be different but the principle is not).[/QUOTE]
Let me try and wrap my head around this system.
Bilge water is pumped to to a holding tank on deck. Tank is heated with steam coils. Water is evaporated, residual oil goes to a sludge holding tank.
OK, first - the BTU’s required to boil off that water is huge. Can’t see this being cost effective UNLESS the steam is getting it’s energy for waste heat. Is that the case?
Second, do I understand you are discharging a M^3/d of oily sludge to surface waters? Would that be legal? Or, did I read that wrong and you are blending the distillate oil tank in with the bunker oil to recover BTU value?
edit - I think I read that wrong. When you say you are disposing of 1 M^3/d, you are referring to the evaporation rate. (About 264 gallons) I assume the slop tank contents are held until it can be pumped out back in port.
Question - can the slop tank contents be bled back and used as boiler feed? I would think the energy content would be pretty high.
Question 2 - 264 gpd (or 528 if operated full time) is not very much. Does demand ever exceed capacity? If yes, what then?
EGB= exhaust gas boiler so yes, in this instance the energy to create the steam was recovered from waste heat off the ME and SSDG exhausts.
Regarding the second portion of your reply, the " 1 cubic meter" is how much water was removed from the water/oil mix by evaporation. When evaporation was complete the sludge left in the tank was drained to the slop tank, to be pumped ashore when in port or for use in the incinerator.
On this vessel in particular there wasn’t a way to take suction on the slop tank to feed the Aux boiler or ME/SSDG ( both operated on HFO) but I do t see any glaring reasons why this couldn’t be applied with appropriate filtration/separation.
264.1 gallons may seem small at first, however that number is how much water was removed from the total content of the steam-out tank, not the total “process water” as most OWS manuals would define it. What I mean by this is that when a traditional OWS states it’s capacity it is the throughput to the unit, not the amount of oil/water discharged on either respective end. To make an accurate comparison to a steam-out tank setup you would have to consider the total volume of the tank, as this original oil/water mix is the “process water”. I don’t remember the exact volume of the tank in my own personal experience but I would approximate 1600 gallons ( 6 foot diameter cylinder 8 ft tall). So to be fair, 1600 gallons of “process water” was originally introduced into the tank, and completed evaporation in 12 hours, yielding a process rate of 2.2 gpm
Keep in mind this was a large slow speed diesel running on HFO with Alfa laval FO and LO purifiers so the majority of what we pumped up to the steam-out tank was sludge. I would anticipate better rates on a vessel using DFM as its main source of fuel i.e. higher water content in its bilge holding/ dirty oil tank
[QUOTE=Jetryder223;82213]Working on a study of water treatment system to meet the 15 ppm FOG needed for overboard discharge. Not looking for the old salts to hand me a paper but would appreciate inputs on:
I can research from there. I began googling companys and systems but it’s hard to determine the industry leaders from slick web pages found on line.[/QUOTE]
This may help on the technical level
Leaders may include “DVZ”, a German company. Deckma usually just makes the discharge monitors.
On our newer vessels, we use preheating (electric) to promote separation and better OWS performance.
No complaints from engineers, but I will check.
[QUOTE=Jetryder223;82313]Let me try and wrap my head around this system.
Bilge water is pumped to to a holding tank on deck. Tank is heated with steam coils. Water is evaporated, residual oil goes to a sludge holding tank.
OK, first - the BTU’s required to boil off that water is huge. Can’t see this being cost effective UNLESS the steam is getting it’s energy for waste heat. Is that the case?
Second, do I understand you are discharging a M^3/d of oily sludge to surface waters? Would that be legal? Or, did I read that wrong and you are blending the distillate oil tank in with the bunker oil to recover BTU value?
edit - I think I read that wrong. When you say you are disposing of 1 M^3/d, you are referring to the evaporation rate. (About 264 gallons) I assume the slop tank contents are held until it can be pumped out back in port.
Question - can the slop tank contents be bled back and used as boiler feed? I would think the energy content would be pretty high.
Question 2 - 264 gpd (or 528 if operated full time) is not very much. Does demand ever exceed capacity? If yes, what then?[/QUOTE]
The evaporative systems are commonly found in machine shops where you have large volumes of soluble oil mixed in water which cannot be separated by coalescing or weir type separators. The energy consumed by these units is tremendous. Coalescing, weir, and centrifugal separators are always a better option for marine vessels. Although, if you never venture 25 miles off shore you could technically run an evaporative system when you can’t run any other type,
Follow up on this - Are there any systems that permit re-blending of concentrated slop tank contents with fuel? Bunker is pretty dirty fuel to begin with, I would think small amounts of slop metered in the feed would not creat an issue.
Has anyone tried this or are the risks not worth it?
I worked on a Fish Processing vessel that had a system much like the one Ryan.Gannon described.
We pumped the bilges up to the holding tank, used Aux Boiler to heat it and separate/evaporate the water.
Mixed in excess fish oil, added diesel fuel to what was left and then burned that in the incinerator and Aux. Boiler.
The tank was much larger than the one he mentioned (maybe 4000 gallons?). We ran this process 24/7, separate/evaporate for a day or two, burn from that tank for a day or two.
It worked very well and we seldom used the OWS.
All the bilge water, slops and extra fish oil was used in this system.
One Fishing Vessel I worked on mixed used engine oil in the fuel tanks, about 50 gallons of oil to 4500 gallons of fuel.
I didn’t like it, but that was the way it was done.
Never had any problems that were directly related to this.
I know one boat in our fleet that injects bilge water into the main engine exhaust.
The C/E rigged up a system on his own. I haven’t seen it, and wouldn’t do it, but he likes it.
[QUOTE=Jetryder223;83560]Follow up on this - Are there any systems that permit re-blending of concentrated slop tank contents with fuel? Bunker is pretty dirty fuel to begin with, I would think small amounts of slop metered in the feed would not creat an issue.
[/QUOTE]
[I]“Bunker is pretty dirty fuel to begin with …”[/I]
If that is the case, whoever buys the fuel needs to find another supplier.
The sludge was removed from the fuel and lube because it is sludge … re-introducing it to the fuel is a waste of time, energy, and just contaminates the fuel even more since you are slowly concentrating the crud that was properly removed the first time around.
This doesn’t even begin to address the risk of very costly damage to fuel injection components and other components in the combustion gas path.
And by the way, Heli-Sep OWS units are not centrifugal separators … since you are “studying” the subject, start by looking at how current systems work and try to avoid going into this area with incorrect assumptions about fuel, slops, sludge, and how oil is removed from water.
Fair enough Steamer. I opened this thread with no assumptions however. My assignment was only to investigate environmentally responsible methods of bilge water management. I was sure there were legitimate reasons for not blending slop & bunker - thank you for spelling it out.
I think I have enough leads on systems to finish my study. Appreciate all the help.