Jump to content
AmazedByCruising

What's the use of scrubbers?

Recommended Posts

From what I understand, scrubbers are a kind of a shower that captures chemicals like sulfur and particulates before they get into the air, but only to put it into the sea. Not, for instance, to filter out the chemicals and reuse them as fertilizer.

 

So if they are used to protect the environment, what's the advantage compared to waiting a few days before rain and gravity will have done exactly the same?

Share this post


Link to post
Share on other sites
Here is a thread with some interesting technical info on scrubbers:

 

http://boards.cruisecritic.com/showthread.php?t=2424217

 

 

Good explanation by the Chief.

 

If we're thinking about the future, perhaps someday we'll see perfection of small scale rotary kiln technology that would basically allow ships to run on the energy produced by baking their own waste and trash without emission of harmful airborne pollutants. For a goodly portion of the past decade, the US Army has been testing this for mobile field operation. BTW, pretty much odorless. Bigger stationary kilns are already in operation at a variety of locations in India and Asia.

Share this post


Link to post
Share on other sites

Scrubbers that operate on the open loop model must meet standards for several pollutants and carcinogens in order to operate as open loop, especially within harbor limits. Studies have shown that with either dilution of the effluent (adding more water to the wash water before discharge) or some level of centrifuging, that acceptable limits were achieved, and monitored levels within harbors did not change during the trials.

 

Scrubbers that operate on the closed loop model, and those open loops that do some centrifuging, remove the particulate matter and some of the chemicals through centrifuging, and this is then mixed with the ship's waste oil stream which is either incinerated onboard, or landed ashore with certified slops handling companies to be incinerated ashore. Incinerators are also monitored, and operate at different parameters to diesel engines (basically burn at a much higher temperature), to limit emissions. Studies have shown that the sea water and sea life break down the acids in the wash water with less harm than is caused by airborne acids. Sea water is slightly alkaline naturally.

 

As we all know from the acid rain debates and legislation of the '70's and '80's, SOX and NOX emissions are not quickly "taken care of by rain and gravity", but are persistent and can carry in the atmosphere for thousands of miles. Ship's emissions, being relatively small structures for the size of the power generated, and being mobile, are among the last major power sources in the world to be able to build technology that will address the pollution issue.

 

Remember that we are not talking only about cruise ships, that make up less than 1% of the world's total tonnage. 95% of the world's commerce travels by water, and while water transport is still by far the most efficient means of transport in terms of energy consumed per ton of cargo, this is still a huge amount of energy that needs to be controlled.

 

You also need to know the realities of crude oil refining. There are currently in the world three generations of refineries operating. Actually, the oldest, first generation has disappeared, so only the second and third generation facilities remain. A second generation refinery (the most common around the world today) extracts as much "clean product" (from kerosenes like jet fuel, gasolines, diesel fuels, and lubricating oils), and what is left over is about 20-30% of the original crude, and this is "residual fuel oil". A second generation refinery cannot draw any more out of this product, so it is sold for use in power plants and ships. Third generation refineries can extract clean product down to the point where 95% of the crude has been used, and what is left over is solid "coke", which is used in steel production. So, if residual fuel oil has no market (you ban it instead of allowing it to be burned with a scrubber attached), what do the vast majority of refineries do with their left over product? You would have to ship to to the third gen refineries at a cost in energy to move it that would likely exceed the value of the products derived from it. Until we come up with better refineries, we need to have a market for residual fuel oil, but we need to better handle what it produces.

Share this post


Link to post
Share on other sites

As we all know from the acid rain debates and legislation of the '70's and '80's, SOX and NOX emissions are not quickly "taken care of by rain and gravity", but are persistent and can carry in the atmosphere for thousands of miles. Ship's emissions, being relatively small structures for the size of the power generated, and being mobile, are among the last major power sources in the world to be able to build technology that will address the pollution issue.

 

When I was a kid I was told there would be no more forests left in 2000. While that was utter BS, obviously, what pollution goes up will come down. There are probably ways to make ships more environmently friendly. Using electricity from the port instead of using generators so the AC can run using solar energy at least sounds good. Still, I cannot see what environmental group would advocate scrubbers.

 

Studies have shown that with either dilution of the effluent (adding more water to the wash water before discharge) or some level of centrifuging, that acceptable limits were achieved, and monitored levels within harbors did not change during the trials.

 

What does it matter to the gazzilion tonnes of water in the sea if you add 1kg of nitrogen or sulfur directly, or add it after diluting it first with a few tonnes of water from the very same sea? That sounds like a "Princess" solution.

 

Scrubbers still feel like "tadah, no more pollution in the air!" The same amount of sulfur and other stuff will end up in the same ocean (I'm not even sure if that's a bad thing), but this time a bit more because the scrubbers also need energy.

Share this post


Link to post
Share on other sites
When I was a kid I was told there would be no more forests left in 2000. While that was utter BS, obviously, what pollution goes up will come down. There are probably ways to make ships more environmently friendly. Using electricity from the port instead of using generators so the AC can run using solar energy at least sounds good. Still, I cannot see what environmental group would advocate scrubbers.

 

This would be good, if the power were supplied by solar, but most of the world's power plants are still fossil fueled (about 2/3rds)

 

What does it matter to the gazzilion tonnes of water in the sea if you add 1kg of nitrogen or sulfur directly, or add it after diluting it first with a few tonnes of water from the very same sea? That sounds like a "Princess" solution.

 

Scrubbers still feel like "tadah, no more pollution in the air!" The same amount of sulfur and other stuff will end up in the same ocean (I'm not even sure if that's a bad thing), but this time a bit more because the scrubbers also need energy.

 

As far as dilution, to the "gazzilion" gallons of the sea, it doesn't make any difference. To the sea life at the point of discharge it makes a great deal of difference, and affecting the sea life in one spot in the ocean will have a cascade effect on sea life throughout the oceans. This is why ships are allowed to discharge oil in bilge water at concentrations below 15ppm, because perfect oil water separation is not always possible, and would be financially difficult, and at the 15ppm level, it is understood that the effects of the oil are minimal.

 

Environmentalists know that the ocean and the atmosphere have different mechanisms for coping with pollutants, and when something like sulfur would be in different forms (sulfur oxides in air, sulfuric acid in water) in the different media, their basic nature of polluting (what effect does it create?) and its concentration in those different forms can mean that the same quantity of pollutant (sulfur atom) affects the environment differently.

 

If the IMO had not felt that open loop scrubbers that met their standards for pollutant discharge would be safe for the ocean environment, they would have required all to be closed loop.

Share this post


Link to post
Share on other sites
If the IMO had not felt that open loop scrubbers that met their standards for pollutant discharge would be safe for the ocean environment, they would have required all to be closed loop.

 

This article, https://www.krbd.org/2018/08/01/city-reports-on-cruise-discharge-complaints/ says that what is shown in the picture is discharge of the scrubbers. To me, it looks like oil spillage. What do you see?

Share this post


Link to post
Share on other sites
This article, https://www.krbd.org/2018/08/01/city-reports-on-cruise-discharge-complaints/ says that what is shown in the picture is discharge of the scrubbers. To me, it looks like oil spillage. What do you see?

 

From that picture, I can't say what it looks like, other than discolored water. If that was in fact scrubber discharge, then the ship's centrifuge is not working properly. There would not be any oil in the exhaust gas. The scrubber water goes through a centrifuge to remove the particulate matter before it is discharged overboard. This looks like the soot is not being separated properly and forming wet, black globs. The particulate matter is retained onboard either for incineration, or pumping ashore with the ship's oil sludges for disposal in shore facilities. There are also other chemicals added to neutralize the water before it goes overboard. Balancing out an open scrubber system to meet applicable discharge standards is difficult, and requires constant attention and work. The fact that the article says they "switched off the discharge" tells me that they have a "hybrid" system that can be open (discharging to sea) or closed (water retained onboard and recycled). As scrubbers become more common, it may be found that the maintenance of them is not keeping up with adhering to required discharge standards, and so ports may start requiring closed system operation in the port.

Share this post


Link to post
Share on other sites
From that picture, I can't say what it looks like, other than discolored water. If that was in fact scrubber discharge, then the ship's centrifuge is not working properly.

 

There are more pictures on a different site which are a bit clearer. I agree something is not functioning :)

Thank you!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Forum Jump
    • Categories
      • Explore the Night. Sweepstakes - Enter now for a chance to win win a free cruise for two with Azamara Club Cruises!
      • Forum Assistance
      • New Cruisers
      • Cruise Lines “A – O”
      • Cruise Lines “P – Z”
      • River Cruising
      • ROLL CALLS
      • Digital Photography & Cruise Technology
      • Member Cruise Reviews
      • Community Contests
      • Special Interest Cruising
      • Cruise Discussion Topics
      • UK Cruising
      • Australia & New Zealand Cruisers
      • North American Homeports
      • Ports of Call
      • Cruise Conversations
×