Generators running on heavy oil.

Macphail
3rd May 2009, 22:50
Glenorchy Ex BF Priam, 1943 built.

The generators where Allenís straight eights, they started on diesel oil and then went on to HFO. Why didnít this practice continue.

John

surfaceblow
4th May 2009, 01:50
Some diesel engine generators (Daihatsu and MaK) that I worked on used blend oil after starting. We used a mixture of IFO 380 and diesel oil. The blend equipment was set up to have a 1 to 1 ratio (one ton IFO 380 and one ton gas oil). The blend oil was only used when there was at least 80 per cent load one the engine below that we used straight gas oil. We also used the gas oil while maneuvering and in-port.

At the present time the trend is to go to low sulfur and lighter fuels to meet environmental concerns. On the West Coast of America they are setting up Cold Iron Areas were ships have to plug in and stop their engines.

makko
4th May 2009, 02:21
Most generators are now designed to run on pure IFO 380. The fuel pumps and injectors are designed with this in mind and DO is only used when running down an engine prior to a major maintenance. What I am surprised at is the relatively scarce use of homogenizers given the generally poor quality of current fuels and the relatively high levels of asphaltenes and the possibility of "auto-incompatibility". I have been working informally on a paper on this based on experience specifically over the past two years. On the latter BF's, all engines ran on HFO. I am also amazed at the lack of knowledge amongst current engineers concerning fuel quality and management.
Regards,
Dave

steve2
17th May 2009, 17:21
Glenorchy Ex BF Priam, 1943 built.

The generators where Allenís straight eights, they started on diesel oil and then went on to HFO. Why didnít this practice continue.

John

The Allens were started up on diesel and then changed over to stinking hot bunker 'C'. The rational was that this saved money on fuel and reduced the tank space needed for diesel. The other thing it did was increase the maintenance dramaticaly due to the sulpur and other muck in the 'C'. Plenty of crew on board in those days to do the work and they were relatively cheap!

Modern MaK's are also designed to be dual fuel but in their case it is gas oil and diesel. The engines have heated circulating systems allowing start up on Diesel and Viscotherms to maintain the correct viscosity. Times have changed. Unless of course you bunker Diesel in Singapore when you can once again get all sorts of c*** in your fuel!
Steve

Duncan112
17th May 2009, 22:35
Bank Lines "Fish" class were fitted with Allen alternator engines, designed to run on DO, converted to run on a blend (Until some clever B'tard found that they would burn 380cst HO) then ran on pure 380, starting and stopping on DO only because the injection pumps etc were not fitted with trace heating.

Just prior to the ships sale Troutbank had one engine fitted with all nimonic valves, forged steel pistons with oil spray cooling (top end bush in con rod modified to give this) and bigger LO pump to give the oil flow necessary. This seemed to work - at least the engine started to do more than 3000 hours between head swaps.

Greek new owners arrived and converted the engines back to DO (the old fuel pumps and fuel valves were down the steering flat) remarking that it was cheaper to burn the more expensive fuel than pay overtime for the remedial work. - A similar attitude to chart corrections prevailed - charts were bought for the forthcoming voyage only and no folios maintained.

Seemed to run the ships quite successfully for some years after that.

Duncan

eldersuk
17th May 2009, 23:53
Elder Dempster's Eboe ran 6 cyl Allens on H.O. although starting and stopping on D.O. It must have been a failed expriment in economics as none of the other ships were converted.

Derek

Abbeywood.
5th September 2009, 06:54
Elder Dempster's Eboe ran 6 cyl Allens on H.O. although starting and stopping on D.O. It must have been a failed expriment in economics as none of the other ships were converted.

Derek

I Sailed in the 'Lancashire', (Bibby's - 1969/70), with 3 x 6cyl Allens. we change them over to run on HFO purely due to DO bunkers becoming short. Fortunately got away with only one machine being contaminated with excess carbon and gunge. Soon changed back when fresh bunkers received.
Nevertheless, the performance was pretty good on HFO, but then Allen's were a very reliable engine

Satanic Mechanic
5th September 2009, 19:52
Its all quite simple really - cost.

The cost of MDO is absolutely horrendous and with the new types of recirculating fuel valves there is no need to run either gene's or Main Engines up or down on MDO. These fuel valves ensure the line is hot and circulating with hot oil all the way to the valve tips - so no cold blockages and of course with a nice accurate visco then there should be no problems. Worthwhile comparing the fuel rail temperature with the visco outlet - some ships you need to artificially lower the viscosity in order to get it right at the rail - before going to find who shut the trace heating valves. This plus the modern understanding of metallurgy , tribology and engine design means that the overhaul intervals on HFO engines are now expected to be at least around 16000 hrs (had one at 24000hrs and was still fine) there is just no advantage in running on MDO at all now.

Blended fuels of course had all the disadvantages of HFO without having any of the advantages of MDO. plus you had the horrible blending plant (Belinda the Blender) to contend with as well as the cost of using DO.

The only time I use MDO on engines now is , as has been pointed out before, before maintenance or dry dock to clean the lines out and on restarting until I can heat the HFO. (Note - remember to change over the returns - contaminated MDO tanks never ever ever impress)

Billieboy
6th September 2009, 09:55
As an aside, on the latest LP/NG ships which use the cargo, 'Burn-off', in the main engine/boilers, do the gennys have similar dual fuel systems these days?

Satanic Mechanic
6th September 2009, 11:14
As an aside, on the latest LP/NG ships which use the cargo, 'Burn-off', in the main engine/boilers, do the gennys have similar dual fuel systems these days?

After a fashion - the latest LNG vessels are dual fuel diesel electric so yes on a normal sea passage the generators are burning boil off gas, of course the generators are also powering the vessel. The first versions of this system use only diesel - which when it was realised just how much diesel the vessels would have to bunker and how much it cost caused several accountants to either have a tax deductable heart attack or to drop dead on the spot - so the latest version are trifuel i.e gas/diesel/HFO

Duncan112
6th September 2009, 11:30
I agree entirely with SM about running and stopping on HO, however I found that running alternator engines on HO at low load led to choking of the inlet valves - with long standbys and running cranes it was necessary to run the engines for long periods on low loads - we tended to adjust the load sharing between the engines manually and run the low loaded engine on DO.

Comments anyone?

Duncan

Satanic Mechanic
6th September 2009, 11:54
I agree entirely with SM about running and stopping on HO, however I found that running alternator engines on HO at low load led to choking of the inlet valves - with long standbys and running cranes it was necessary to run the engines for long periods on low loads - we tended to adjust the load sharing between the engines manually and run the low loaded engine on DO.

Comments anyone?

Duncan

Duncan

i know exactly where you are coming from - I detest running them anything below 50% load, unfortunately I am not entirely happy over about 90% load either as I like a bit of spare. Just so long as I have both engines above 50 % I am happy enough , however for fluctuating loads I have a different approach, some control systems do this for you -Lyngso notably but I do it manually as well. I have one engine running at 80 - 85% with the other taking the remainder of the load and varying with the load - then every 30 minutes I swap them over. I also make a lot of use of PMS auto start and stop functions if it is appropriate and delayed starts are acceptable.

Philthechill
6th September 2009, 12:58
Vambo! You seem very much up-to-speed on "things modern" engine-wise so you could maybe explain how "boil-off" on LPG/LNG ships is used in diesel-engines.

The concept of using "boil-off" in a steam-plant is pretty obvious as you (presumably) just pipe the gas into the furnaces but, surely, piping gas directly into a diesel's combustion-space would promote "knocking" (detonation) much as you would get if you injected petrol into the combustion-space of a diesel which is why, of course, people who mistakenly fill their diesel-engined auto, with petrol, get all sorts of "interesting" results (apart from the lack of lubrication in the pump and injectors that it!!) resulting from their memory-slip.

I could see the idea of having a gas-condensing plant to liquefy the boil-off and injecting it as a liquid as a possiblity but then if you're going to condense the boil-off why not just return the liquefied gas to the storage-tanks where it's boiled-off from? However a gas-condensing plant, just for the job of condensing boil-off, would be quite a large bit of kit and would need not inconsiderable electrical-power to drive it, so obviously it's cheaper to utilise the boil-off as a gas to help propel the ship or generate power.

The observation by "Makko" on this "Thread" on May 4th. (Post #3) re. he's surprised there doesn't seem to be much use of homegenisers where HO and Diesel/Gas oil, is used, raises quite an interesting train-of-thought. Having seen how homogenisers are used in dairies to "force" the fat in milk to blend with the other products in the milk I could see it working quite well to "force" the lighter elements of diesel/gas oil to blend quite "happily" with the heavier HO.

Anyway, Vambo, old tater, if you could explain how this fiendishly clever use of boil-off is done you will be doing me a great service,(Hippy) as it will calm my incredibly fevered mind--------for a while! Salaams, Phil

Satanic Mechanic
6th September 2009, 13:30
Chilly

Indeed steam plant is easy you just take the boil off and put it in the furnace at the rate required using a rotary compressor. Now with the modern unpopularity of steam due to efficiency or some such nonsense we have to start looking at diesels. Now I have never seen this on an LPG vessel as those gasses are easily reliquified however on LNG methane there are two ways of going about this:

The dual fuel engine - these are medium speeds that operate as normal diesels when on diesel but when they are operating on gas they become Otto cycle engines with the gas getting induced with the scavenge air and ignition being initiated by a small diesel injector. You are of course correct that 'knock' is indeed a problem - so each cylinder is provided with a knock sensor (piezo crystal affair) and the ignition is advanced or retarded to suit. Obviously a lot of electronics in use.

The Gas Engine - dead easy this it is exactly the same as a slow speed two stroke except gas is injected instead of diesel. Only small problem is you have to get the gas up to about 250 bar for injection - this causes a lot of people to go (EEK). again ignition timing can be altered by the use of a common rail electronic injection system and knock sensors.

Condensing gas is the same as reliquifaction so why use cargo when you don't have to - plus with a boiling point of -163 methane is a right git to liquify (about 5 MW and a lot of N2)

Homogenisers are more interesting at the moment with the possibilities of introducing water into the fuel to control emissions. But for diesel - we just don't use it if we can help it and if we do blending is not the preference.

TIM HUDSON
6th September 2009, 13:42
I sailed on a LPG/LNG ship in 1989 named Havfru which had a Sulzer main engine modified to burn LNG boil off. She was built at Moss Rossenborg in 1973 as Venator. A Gas turbine/alternator using boil off provided all electrical power when loaded. I believe she was the first two stroke diesel to be capable of such. During my time aboard we carried only LPG however.
As far as diesel engined auxilary continuously using IFO 380 in 1991 I stood by the building in Kvaerner Govan of a LPG ship designed for this purpose. Automation made change-over to diesel fuel whenever an alarm condition arose. Worked ok as long as fuel quality not too bad.!
tim

Satanic Mechanic
6th September 2009, 13:56
I sailed on a LPG/LNG ship in 1989 named Havfru which had a Sulzer main engine modified to burn LNG boil off. She was built at Moss Rossenborg in 1973 as Venator. A Gas turbine/alternator using boil off provided all electrical power when loaded. I believe she was the first two stroke diesel to be capable of such. During my time aboard we carried only LPG however.
As far as diesel engined auxilary continuously using IFO 380 in 1991 I stood by the building in Kvaerner Govan of a LPG ship designed for this purpose. Automation made change-over to diesel fuel whenever an alarm condition arose. Worked ok as long as fuel quality not too bad.!
tim

its not new technology - but with the advent of electronic controls it has improved to point where it is much more acceptable.

Auto change over to diesel - I always bypassed it - apart from it not being required on every alarm condition it had terrible habit of gassing up the engine leading to me having a hissy fit.

I hope it wasn't you who bent the shaft on that ship ;)

Philthechill
6th September 2009, 16:15
Vambo! Many thanks for your reply but, as ever, more questions are raised!!!!!

Just what sort of compressors do you use to get the gas up to 250 bar? Gas-compressors of the type produced by Dresser-Rand or, (probably), something a little less bulky? I can understand people getting a little "concerned" as I'm sure compressing a volatile gas to these pressures can cause all kinds of problems! It's understandable there being a lot of electronic wizardry involved as otherwise I don't suppose it would be viable would it?

You mention each cylinder having its own anti-knock sensor. Does this mean that each cylinder is, in effect, a single-cylinder engine with the gas/fuel-injection being individually controlled to suit the conditions in that particular cylinder or is the anti-knock sensing "pooled" by the electronics which then decides to retard the timing on all cylinders to eliminate the pre-ignition going on? If this is how it works the advancing and retarding of the timing must be going on virtually second by second, I should imagine. Theoretically, of course, if you've got pre-ignition going on in one cylinder ergo you MUST have pre-ignition going on in ALL cylinders but, as any student of i.c. engines knows, it ain't that simple!!!!

I'd much appreciate further explanation, if possible, as I find the whole concept completely absorbing. Again many thanks for your highly informative writings so far! Salaams, Phil(Hippy)

Satanic Mechanic
6th September 2009, 16:26
Vambo! Many thanks for your reply but, as ever, more questions are raised!!!!!

Just what sort of compressors do you use to get the gas up to 250 bar? Gas-compressors of the type produced by Dresser-Rand or, (probably), something a little less bulky? I can understand people getting a little "concerned" as I'm sure compressing a volatile gas to these pressures can cause all kinds of problems! It's understandable there being a lot of electronic wizardry involved as otherwise I don't suppose it would be viable would it?

You mention each cylinder having its own anti-knock sensor. Does this mean that each cylinder is, in effect, a single-cylinder engine with the gas/fuel-injection being individually controlled to suit the conditions in that particular cylinder or is the anti-knock sensing "pooled" by the electronics which then decides to retard the timing on all cylinders to eliminate the pre-ignition going on? If this is how it works the advancing and retarding of the timing must be going on virtually second by second, I should imagine. Theoretically, of course, if you've got pre-ignition going on in one cylinder ergo you MUST have pre-ignition going on in ALL cylinders but, as any student of i.c. engines knows, it ain't that simple!!!!

I'd much appreciate further explanation, if possible, as I find the whole concept completely absorbing. Again many thanks for your highly informative writings so far! Salaams, Phil(Hippy)

Chilly

I'll PM you with some bits and pieces - to be absolutely honest I am sitting here in Galicia with a head like a box of frogs so I cant be ersed typing it all(Thumb)

averheijden
9th September 2009, 20:13
L.S.
My experience with auxiliary diesels on heavy fuel is from 1954
I sailed as 3rd engineer on the Dutch ship mv BAUD in Indonesia
We had 3 auxiliary diesels from STORK (Holland), 5 cylinders continuous running on heavy fuel 600” Redw.1 at 100į F
Same fuel we used in the main Engine: 8 cylinder WERKSPOOR.
We had no steam boiler on board!!!
All the heating on the engines for the fuel was done by electric heaters (DC 220V)
The fuel in the bunkers was heated by heating coils with cooling water from main- and auxiliary engines.
Regards
Alfons