FLORENCE, Italy - Freshly overhauled Franco Crosti 2-8-0 No. 741.120 is back in operation. A Franco Crosti boiler consists of a standard boiler and one or two additional boilers for preheating the water. The feedwater heater is not designed to produce steam, instead raising the temperature of the feedwater. By preheating the feedwater with the help of the exhaust gases in separate boilers, very efficient locomotives were created. Two engineers working for the Ferrovie dello Stato (the Italian State Railway), Attilio Franco and Dr. Piero Crosti, designed the system in the 1930s. Between 1958 and 1960, 81 class 740 2-8-0s were rebuilt into 741s with a single preheater under the main boiler.
After its withdrawal from service No. 741.120 was preserved in Pistoia. It was restored to working order in Moretta and in September the engine was serviceable again.
Its first run was a three-car private charter for a group of poets over the Faentina line from Florence to Faenza, Italy, on Oct. 13. From Florence the train ran via Vaglia to Borgo San Lorenzo. North of Borgo San Lorenzo there is a12-mile tunnel through the Apennines. Usually steam trains are only allowed to pass through this tunnel with a diesel locomotive as the leading engine. However an exception was made and the train passed through the tunnel without diesel assistance. The road around the tunnel is very curvy; in fact, it is a mountain pass. However, even though it was not a photo special, the train waited for photographers at the tunnel exit: a very nice gesture from the crew.
There was a strict schedule for reading poems in each coach throughout the journey between Florence and Faenza (and even further to Bologna with an electric locomotive). In Faenza the engine was turned in the shop, where there is an operational turntable and a water column. Because the poetry train went on to Bologna with the electric, the steam locomotive returned to Florence light engine.
Source: http://trn.trains.com/news/news-wire/2007/10/italian-franco-crosti-boilered-steam-locomotive-back-in-operation
For a wonderful story with lots of photos of this unique engine, please visit:
http://www.markusworldwide.ch/Railways/Italy/741_Garfagnana/741_Garfagnana.htm
:o)
Quite an unusual locomotive as you noted. But it still has the unmistakable sounds of steam. :)
ReplyDeleteAnd the photos in the link are not to be misses. Beautiful countryside and majestic mountains.
Great finds as usual. Thanks, Chickenmom.
You're welcome! It was a good one to share.
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I jumped over to the linked story. High quality photos and a beautiful look at the Italian countryside.
But.
This is a quote from the article,
"The concept was that the preheater did warm up feeding water, thus remaining at relatively low temperatures compared to the boiler, so the remaining heat from combustion gases could be absorbed ideally. The design increased the overall efficiency substantially."
Preheaters are used to gain efficiency and they usually capture waste heat from a process so that instead of throwing the heat away, you save energy, (money) by using the waste heat. The statement, "the preheater did warm up feeding water," is completely correct. Then the statement goes off the rails, (yes, a train analogy) by saying, "thus remaining at relatively low temperatures compared to the boiler" You cannot preheat water, and have it remain at the same temperature!
Next, the article grasps the basic concept of one of the laws of thermodynamics in that you must have a temperature difference to exchange heat. They failed to grasp the concept that a locomotive boiler's feedwater is at ambient temperature and the difference in temperature between the feedwater and the exhaust steam is going to so great that heat will be exchanged even if you preheat the feedwater greatly.
Warning. The following is a summation of the basic steam cycle in Navy enginerooms and firerooms,I will skip the dry numbers but it is going to get a little technical so hang on.
Fossil fuel boilers in use by the Navy operate at pressures of either 600 or 1200 pounds per square inch. Regardless of the pressure the principles remain the same.
This continues in comment two.
Comment Two.
DeleteBasic Steam Cycle.
We will start our steam cycle energy discussion where the steam enters the propulsion turbines.
Very hot, very high pressure steam goes into the turbine blades, the steam gives up energy to create motion, the motion is used to make the ship go through the water.
The steam leaves the propulsion turbines at a much reduced temperature and pressure. Here is where ships and trains become completely different. Ships recycle steam, and do not simply send it up the stacks. There are no water tanks for ships as the oceans are salt water and salt water cannot, and must not be put into boilers.
The steam goes into a condenser and is turned back into water. The condenser has tubes filled with salt water, and the steam flows around the tubes, gives up heat to the ocean, and then condensed steam (non salt water called condensate) falls to the bottom of the condenser. This water is going to go through several preheaters before it is returned to the boiler.
First preheat. The condenser is kept in a high vacuum and the vacuum is maintained in part by steam jet air ejectors. As the steam from the air ejectors leaves the air ejectors it passes through a tubed heat exchanger and gives up some of its energy to the condensate. Now the condensate is warmer, but not yet ready to go to the boiler.
Second preheat. Next is the deaerating feed heater. We need to remove the majority of dissolved oxygen from our condensate before sending it to the boiler and we need to use the steam that is being exhausted from auxiliary pumps. The condensate is sent to the deaerating feed heater and mixed with steam. The oxygen is mostly removed and the condensate gains more heat. This is where the water changes names from condensate to feedwater.
Next we will pump the feedwater through two different pumps and then send it towards the boiler.
Third preheat. Our final preheat is located in the exhaust stacks of the propulsion boilers. The boilers are burning fossil fuels, and the heated air and the products of combustion are going up the stacks. These exhaust gases are very hot.
Just as the gases leave the boiler they pass through a network of tubes. The tubes contain the incoming feedwater and this is our final chance to use the waste heat of the boiler to preheat water and save some energy.
The water next goes into the boiler, is heated by the fires of hell, the water turns into steam, and the steam heads for the turbines to begin the cycle anew.
John in Philly, Retired Navy Machinist Mate.
Thank you for your great comments, John! Did not know that ships recycled the steam! I bet I wasn't the only one who thought they used the ocean water! I cannot imagine the heat in those engine rooms - kudos for your service and experience! :o)
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