Titanic Centennial: Fire and Ice

original

[More from the book "The Sinking of the Titanic and Great Sea Disasters," edited by Logan Marshall and first published in 1912. Click on the "Titanic" tag for other selections from this book.]

The Fire in the Coal Bunkers

Unknown to the passengers, the Titanic was on fire from the day she sailed from Southampton. Her officers and crew knew it, for they had fought the fire for days.
This story, told for the first time by the survivors of the crew, was only one of the many thrilling tales of the fateful first voyage. 

'The Titanic sailed from Southampton on Wednesday, April 10th, at noon,' said J. Dilley, fireman on the Titanic. 'I was assigned to the Titanic from the Oceanic, where I had served as a fireman. From the day we sailed the Titanic was on fire, and my sole duty, together with eleven other men, had been to fight that fire. We had made no headway against it.' 

'Of course,' he went on, 'the passengers knew nothing of the fire. Do you think we'd have let them know about it? No, sir.' 

The fire started in bunker No. 6. There were hundreds of tons of coal stored there. The coal on top of the bunker was wet, as all the coal should have been, but down at the bottom of the bunker the coal had been permitted to get dry.

The dry coal at the bottom of the pile took fire, and smoldered for days. The wet coal on top kept the flames from coming through, but down in the bottom of the bunkers the flames were raging.
Two men from each watch of stokers were tolled off, to fight that fire. The stokers worked four hours at a time, so twelve of us were fighting flames from the day we put out of Southampton until we hit the iceberg.
No, we didn't get that fire out, and among the stokers there was talk that we'd have to empty the big coal bunkers after we'd put our passengers off in New York, and then call on the fire-boats there to help us put out the fire.
The stokers were alarmed over it, but the officers told us to keep our mouths shut--they didn't want to alarm  the passengers.

______________________
The coal fire on board Titanic fueled speculation of its contribution to her sinking: link
Apparently, such coal fires were common on board steamships and hastened the switch to diesel fuel.

Buh-Bye NOxious Waste

Nitrogen oxides are everywhere. There are "good" ones and "bad" ones and they're all slightly different. A collection of pretty pictures is here: link  Nitrogen oxides include laughing gas (good), nitrate and nitrite salts in foods (controversial), and nitrate plant fertilizers (good). Nitrogen oxides are even important in sex (good) because the molecule NO (nitric oxide) is key in sexual arousal.* Some nitrogen oxides do more harm than good: nitrogen oxides in clouds help form acid rain and the color of "brown cloud" comes from NO₂. But worst of all, nitrogen oxides come out the tail pipes of more efficient diesel vehicles. I wrote about that back here.

The reason there are so many different nitrogen oxides is because nitrogen and oxygen are Periodic Table neighbors, and being so close together, each covets its neighbor's electrons when excited. But only when provoked. Air does not react with itself under normal circumstances. But give things some radiation, a spark, or a diesel motor, and O₂ and N₂ do the nasty together--they recombine:
  
          N₂ + O₂  --->  2NO_x

There's an "x" subscript there because NO can react further to make NO₂ and other nitrogen oxides. "NOx" is so noxious that the State of California forbade the sale of new diesel vehicles beginning in 2004 (I got one of the last VW Golf models in 2003). Daimler-Benz wanted to get those sales back (leave it to the Germans to invent all the new cool diesel technology) and Daimler's BlueTec technology returns NOx emissions whence they came--back to nitrogen and water:

         4NO + 4NH₃ + O₂  --->  4N₂ + 6H₂O 

That equation is mass-balanced by the way, unlike-ahem, what one finds in the Internets (FTFY). The chemistry looks like complex gas-phase chemistry but actually a metal surface mediates the rearrangements (thankfully not another precious metal catalyst). In practice, NOx abatement injects ammonia into the exhaust stream upstream of the catalyst. Ammonia is the best "blue" additive in theory, but urea, which is more easily transported and handled, can also be used in Daimler's AdBlue technology. From what I've read and heard, the technology works as well but is very expensive. So what else is new. Owners are required to periodically charge up with fresh aqueous urea, which led one owner to ask whether he couldn't just "piss in a tank instead"  hahah.

A good primer on how the technology works can be found here or GIY (Google it yourself)

____________________
*Has anyone noted the irony of "NO" (nitric oxide) being a key factor in male sexual arousal?

Carnot Knowledge: Rudolf Diesel's Awesome Idea

Rudolf Diesel (1858-1913)

Ordinary gasoline engines are powered by the sparked ignition of gasoline vapor compressed with air. The heat of combustion and increased exhaust gas pressure drives pistons, doing useful work derived from the chemical energy stored in the fossil fuel. Gasoline engines behave according to the Otto Cycle and the ideas originally date from the mid-19th century.

Rudolf Diesel, a German engineer, understood the engines of his day and had the radical idea of compressing air inside the piston until it became so hot that fuel would spontaneously ignite when it contacted the hot pressurized air, thus not requiring a spark plug. In essence, Diesel reengineered the existing Otto cycle and invented engines that behaved according to the Diesel Cycle.

Diesel based his ideas on his understanding of the thermodynamics of heat engines, a young science begun by the French engineer Sadi Carnot and who later became known as the father of thermodynamics.

US Patent No. 542,846: "Method of and Apparatus for Converting Heat into Work (Link) was awarded to Diesel and has a clear and concise explanation of how and why diesel motors work. In Diesel's own words (or more likely those of his patent attorney):

The gases in the cylinder are now permitted to expand with gradual introduction of fuel and expansion is so regulated that the decrease in temperature by expansion counterbalances the heat produced by the combustion of the fresh particles of fuel. The effect of combustion will therefore not be increase in temperature or pressure, but increase in actual energy exerted.

Diesel also solved another important problem that still limits the efficiency of gasoline engines, viz., the tendency for gasoline motors to knock or ping due to "predetonation." Autoignition is precisely what diesel motors are supposed to do, albeit in a controlled way.  In a diesel motor, the air and fuel are pressurized separately and then mixed. Because diesel motors burn at hotter temperatures than gasoline engines do, they have a tendency to "burn air," forming nitrogen oxides from the normally inert N₂ and O₂ that make up the air we breathe. Precious metal catalysts are used to convert the nitrogen oxides back into oxygen and nitrogen.

Today, diesel motors find widespread use in nearly all commercial transportation applications: trucks, trains, ships, submarines, and, as I learned from Theo Boehm, even in aviation (BTW, did you know that aviation gasoline still has lead? Link--fine particles of lead oxide (or actually lead chloride or bromide) rain down on us everyday. Europeans use diesel motors far more commonly than we do for personal transportation.

I'm sold on diesels. I own a 2003 VW Golf Diesel (TDI) and I love it. It gets around 43 MPH on the highway and not much less in city because it's a stick. Another advantage to owning a diesel in CA is that they are exempt from smog-testing.