First 100% diesel-powered ships of the Royal Navy

The PhD by Brown mentioned above seems the most authoritavie study on coal-to-oil transition. Just have to read it now

 

The following is from Kew files digitised by the Arabian Gulf Digital Archive: Arabian Gulf Digital Archive

Search for "Furnace Fuel Oil" returned a file, DEFE 3/45, which refers to the French requirements for fuel and ammunition stored at Singapore in the early 1950's.

Specification of Furnace Fuel Oil
Specific Gravity : Must not be less than 0.890 at 2000.
Acidity : The oil must not show any trace of mineral acidity.
Freezing Point : The oil must remain fluid at a temperature of O° c.
Flash Point: When tested in the LUCHAIRE or the PENSKY-MARTENS equipment the oil must not give off inflammable gases at temperatures below 80°C.
Fluidity/Viscosity : The kinetic viscosity must be less than 50 centistokes at 50°C; at equal temperature this is the equivalent of an Englez viscosity of less than 7° or to a "Barlsey base marine" fluidity greater than 114 calibration.
Calorific capacity : The upper limit of calorific capacity, measured by means of the calorimetic shell must not be less than 10500 calories.
Sulphur : The sulphur content of the oil must be less than 1.5%
Tar : The tar content must not exceed 5% maximum.
Ash : The ash content must not exceed 0.05% maximum.
Water and sediment : The total water and sediment content, measured by centrifugation, must not exceed 1%. Moreover, the water content, measured by distillation, must not exceed 0.7%.
Sedimentation : The oil must be free of any tendency to lay down deposits at temperatures between 0° and 40°C; nor must it show any tendency to deposit excessive sediment in preheaters when brought to a temperature equivalent to a viscosity of 30 centistokes (4º Englez or 190 "Barlsey base marine").

Specification of Diesel Fuel
Origin : Obtained by direct distillation of crude oil as distinct from products of cracking processes,
Specific gravity : Between 0.830 and 0.885 at 20° C.
Viscosity : Between 4 and 9 centistokes at 20°C, i.e., between 1.31 and 1.75 Englez at the same temperature.
Behaviour when subjected to cooling : Must remain liquid after being subjected to a temperature of minus 10° for one hour.
Flash point : Must not give off inflammable gases at temperatures below 75°C when tested in the Luchaire or the Pensky Martens equipment.
Water and sediment. Total content below 0.5%.
Precipitation test with "normal" petrol : Result below 0.5%.
Distillation : 100 cubic centimetres must distil less than 30% before reaching 255°C and at least 90% before reaching 350°C.
Carbon : Residue less than 0.5%.
Overall acidity : Less than 0.5%.
Mineral acidity : Nil.
Calorific capacity : Equal to at least 10,700 calories.
Sulphur : Content less than 1%.
Ash : Content less than 0.5%.

Specification of Coal
Briquettes
Water : Less than 2%.
Gaseous products : Less than 20%
Ash : Less than 8 to 9%.
Calorific capacity : 7,500 calories
Sulphur : Less than 1.75 to 2%
Proportion of slack and dust : Less than 4%.

Domestic coal
Water : Less than 3%.
Gaseous products : 22 - 25%
Ash : Less than 10 to 12%.
Calorific capacity : 7,500 calories
Sulphur : Less than 1.75 to 2%
Proportion of slack and dust : Less than 25%.

 

Not really. The large diesels in the Panzerschiffe were for a specific purpose, range on long-distance raiding missions. For other vessels the Germans experimented with high-pressure steam systems where steam was raised by a fuel oil boiler. These were all failures and made at least one whole class, the Flottenbegleiter, unusable, and other ships basically the naval equivalent to hangar queens.

The Germans also, during the war, went back to coal with the M-class 'channel destroyer' minesweepers, because there wasn't enough oil to go around.

All the best

Andreas

 

Not really "not really":
The long range played a rather subordinate role during development and construction of the pocket battleships:
The diesel was chosen because its compact design allowed the maximum permissible armament of 280mm and sufficient speed to be combined constructively within the tonnage permitted by Versailles (albeit at the expense of armour). A corresponding turbine engine would have required a longer hull and thus made this concept impossible.
The long range was a most welcome side effect, which, due to the lack of suitable bases, was of course readily incorporated into the concept of overseas naval warfare.

I have somewhere saved the discussions and decision-making processes. In fact, monitors were even discussed for a short time - but the Admiralty desperately wanted "blue water" surface units again.

 

Thanks for the correction!

All the best

Andreas

 

The conversion of naval motive power from coal to oil was quite simple being one of replacing coal fired boilers with oil fired boiler.It may have merely required conducting a mod of fitting oil burners where possible to existing coal fired boilers.For the RN, the Dreadnoughs were laid down as coal firing but the policy of "only fuel oil"was introduced and for commissioning were oil fired with small amount of coal carried for domestic use.

By the turn of the 19th century,Charles Parsons had revolutionised naval propulsion with his steam turbines from the development of the Turbinia in 1894.RN Dreadnoughts were equipped with them as were Japanese Dreadnoughts,the former steamed with oil when prior to the Great War,the conversion was done.With the Japanese Dreadnoughs,it appears that the steam turbines again were CAPs. Other Japanese Dreadnoughts had propulsion from an engineering alliance of Curtis and Parsons.

Parsons soon built up a reputation for his steam turbine propulsion.They also powered the French Navy Bretagne,Lorraine and Provence Dreadnoughts but were fired by coal.

(As regards the Kreigsmarine in WW2 ,the reliable MAN diesel supplied the propulsion for the U Boats.Augsburg,the main factory was an important target in the economic warfare by the RAF. The first raid was in daylight by the new Lancaster equipped No 44 and No 97 Squadrons on 17 April 1942)

 

Agree on the initial conversion, as ultimately the method of steam raising is relatively irrelevant to the way steam is used to generate motive power. In modern power generation we have seen steam being raised by fossil fuels such as fuel oil, distillate (diesel) coal, or exhaust heat from gas turbines (CCGT). The important impact from a naval design perspective is the difference in calorific content of the fuels (higher for oil per unit of weight and space) and handling (pipes and pumps for oil, lots of manual labour for coal).

All the best

Andreas

 

I would say that fuel oil has a CV of 50% more than Welsh steam coal,say in Imperial, 18000 Btu/lb against 12000 Btu/lb for coal.

As regards the differential in weight.Apparently discussed in the design and commissioning of Dreadnoughts was that they would not attain their specified speed unless the coal was down to half stocks.

Looking at the Iron Duke Class of Dreadnoughts of 1912 during the transition period between coal and oil.Normal Coal was 1000 tons with a Maximum of 3250 tons while Normal Oil was 1050 tons with Maximum Oil being 1600 tons

 

DUKES has anthracite at about 31GJ/t, and fuel oil at 41GJ/t, so not quite 50% better. However for vessels not in a position to coal with top-quality anthracite, you first only get 25GJ/t out of normal steam coal, but then presumably also have issues with lower quality fuel producing more residues (assuming that the Admiralty standard was a minimum level of expected fuel performance).

Good info on the vessels during the transition.

All the best

Andreas

 

There is a slight complication, you have to arrange for oil fuel tanks and piping instead of coal bunkers

 

Good description of the converting process:
https://qr.ae/prR3HT

 

Roy that's accepted, those works would be included in the package for conversion to oil plus removal of coal bunkers etc or in an original installation oil firing package. Might also mean changes to the original construction to accommodate a new conversion and it is important to be aware of the original design philosophy and its integrity is not compromised..

With oil tanks it is very important that there is provision for draining off water accumulation at the bottom of the tanks otherwise there is a great risk of adulterated oil being supplied to the burners which would result in adverse performance or burner failure. A long established practice onshore is to incorporate a "floating suction" at the oil tank take off to ensure that debris accumulation below was not drawn off by the oil pumps. These in turn would be provided with suction filters. Below the floating suction head would be the water draw off drain valve. Some oil tanks would be provided with some form of recirculating system by transfer pumps returning oil back into the oil tank or adjacent tanks. This could be used to maintain viscosity within its specification and depending on the grade fuel oil, oil tanks would be fitted with oil tank heaters. Steam was the obvious choice for marine installations.

That recirc line shown in Post #31 is common to all fuel oil plant plant being installed to maintain the specified oil temperature when no burners are in use. Takes me back to many years ago when on a recent commissioned plant, one of four boilers, the last to be commissioned had its oil supply loop suffering from a lower than normal oil pressure and a slightly reduced oil temperature. A thorough check on the oil pipework runs identified the problem of incorrect pipework fitting. Instead of the common oil supply main being fitted to the boiler inlet oil supply loop, the recirc line from the adjacent boiler had been connected to the boiler inlet oil supply loop. Hence the problem which was resolved by connecting the pipework correctly.