hello all! I am working on a scrubber system (open close loop) with a choice at engine outlet. we can go to the scrubber or in a by pass line. For the engine (11MW), I have a question in case of issue on the exhaust line. imagine all dampers (the one on the by pas line and the other on the scruber line) are closed when the engine is running. what will be the consequence? stopping of the engine or damages of the exhaust line? do we have protection normally at the engine exhaust gas outlet? thank you!
No new development without new problems and no new problems without new opportunities for some, apparently:
With the 01.Jan. 2020 deadline just around the corner, scrubbers are the main topic around the Shipping Seminar Circuit and in Board rooms:
If you do come back and check this a month after posting…
Why not just have the dampers activate limit switches attached to an idiot light? Or just use one damper, placed on the bypass line, then you wouldn’t have to worry about it.
Thanks! This one is very interesting. Hopfully we take care of the design. Specially for the material used. We have no this kind of issues.
Thanks WT Sherman.
Sure we have open and close position on the DCS. It is not possible as a initial condition to start the engine if the damper is not open. But imagine if we loose the damper during the operation of the engine! It is not the same issue.
Same it is not possible to have only one damper one the by-pass. Otherwise you will some flue gas in the scrubber because no isolation. Imagine if you have no water flow in the scrubber and no damper to the scrubber. We will have issue.
I don’t know if the engine, if we loose dampers or dampers are closed, will try to stay running, then will be stopped because of too high pressure? This is the point…
Make your dampers spring open/air close.
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I worked on one ship that had a sudden complete blockage of an exhaust stack on a running generator. It resulted in a small crankcase explosion. So yes, it will stop, just a question of what gets damaged in the process. May just blow out an exhaust bellows.
I’ve never seen an engine control system that had a shutdown or alarm for high exhaust back-pressure, but it seems like a simple one to implement. That being said, I’d agree with @W.T.Sherman that it’d be best to come up with a damper arraignment where this is not a possibility.
I was going to suggest shear lines on the damper plates with a sensible failure point, but your suggestion is probably better. A slightly imbalanced design would accomplish the same, but then you’ll be dealing with actuation force tied to flow.
An alternative would be a physical interconnect like you have on older ballast transfer systems, but forcing both dampers open at changeover rather than both valves closed.
EDIT: To answer the original question, you really can’t design the system so that blockages can occur. Engine damage may or may not happen, but engines are mission critical systems, and unexpected loss of propulsion can have really serious consequences.
Could the corrosion problem in scrubber system be solved by choosing the right paint?:
http://www.allaboutshipping.co.uk/2019/10/22/lasting-protection-for-scrubbers-and-outlets/