Friday, January 25, 2013

FTV 1/26/2013 Captain Lima joins the Kennedy

Here is the distillation tank in the Engine Room of the Kennedy

Capt Lima joined the Kennedy in New Orleans. Capt Lima is the Vice President of Academic Affairs, and a licensed Chief Engineer, he is training the cadets in Marine Engineering, As Captain Lima explained, "With over 700 onboard the vessel, water is precious. Water is necessary for cooking, cleaning and the boiler. Fresh water can be produced by one of two methods. One is a distillation process where salt water is boiled under low pressure and the steam is condensed resulting in very pure water. The other method is through reverse osmosis where water is pumped at very high pressure through membranes which filter the salt from the water. Water from the reverse osmosis system cannot be used in the boilers".

We can see this process in the classroom where distillation of salt water can be done on a small scale using the sun. Solar water distillation operates on the basic principles of the water cycle -- evaporation, condensation, and precipitation -- to purify water for drinking and other uses. The device used in distillation is called a still, which consists of a basin in which the source liquid is heated, a condenser in which the heated vapor is cooled back to the liquid state, and a collection vessel in which the purified liquid is collected.

Click on this picture to see solar distillation video
The use of reverse osmosis is most commonly used to produce the bottled water that we drink. The process of reverse osmosis forces impure water (salt water or contaminated water) through a membrane into a tank. Using high pressure on the impure water side "reverses" the natural osmotic process, permitting the passage of pure water through a membrane but leaving the contaminants out. This process is also called ion exclusion, because all the other chemical molecules in the water are not able to pass through the membrane, only the pure water molecules can. Reverse osmosis is being used more often now that modern advances in synthetic materials have produced membranes that are highly efficient at rejecting contaminants, and making them tough enough to withstand the greater pressures necessary for efficient operation. The use of reverse osmosis is used to produce the bottled water that we drink.

Try this activity to get salt from salt water.
Design and build a desalinization tank
Learn more about the use of reverse osmosis in making bottle water.

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