How Do Nuclear Submarines Make Oxygen?- Smarter Every Day 251

Summary

In this Smarter Every Day episode, Destin explores the critical life support systems of a nuclear submarine, focusing on oxygen production and carbon dioxide removal. He delves into the technology and processes, such as the Central Atmospheric Monitoring System (CAMS), electrolysis, and chemical reactions in oxygen candles, that allow submarines to stay submerged for extended periods. Destin also examines the use of Monoethanolamine (MEA) and lithium hydroxide for CO2 scrubbing, illustrating the ingenious methods that sustain life underwater.

Takeaways

• 🌐 The video is a deep dive into how submarines create breathable air and remove carbon dioxide, focusing on the USS Toledo's methods.
• 🛰️ The submarine uses a Central Atmospheric Monitoring System (CAMS) to monitor oxygen levels and the presence of various gases throughout the vessel.
• 🔋 The submarine has two primary methods for creating oxygen: electrolysis using purified water and potassium hydroxide, and burning oxygen candles that contain iron and sodium chlorate.
• 💧 Electrolysis requires seawater to be purified through filtration and reverse osmosis before being split into hydrogen and oxygen using potassium hydroxide as a catalyst.
• 🔥 Oxygen candles, when ignited, burn iron and release oxygen from sodium chlorate, creating a chemical reaction that generates breathable oxygen without the need for electricity.
• 🚫 Straight electrolysis on seawater is dangerous as it would produce chlorine gas, which is harmful, so purification is essential before the process.
• 🛑 Carbon dioxide is removed from the submarine's atmosphere through 'scrubbing' using two main processes: Monoethanolamine (MEA) in a chemical absorption system, and lithium hydroxide as a passive chemical scrubber.
• 🔄 The MEA system involves an absorber tower and a boiler stripper, where 'rich' amine saturated with CO2 is heated to release the gas, which is then compressed and discharged into the sea.
• ⚗️ Lithium hydroxide is used as a backup for CO2 scrubbing and can be sprinkled in areas with high concentrations of people to passively remove carbon dioxide from the air.
• 🔄 The oxygen creation and CO2 scrubbing processes are critical for maintaining a livable atmosphere on a submarine, especially during extended underwater missions.
• 🎧 The episode is sponsored by Raycon, which makes high-quality earbuds with convenient features for users, such as a pause button for runners.

Q & A

What is the primary purpose of submarines in relation to their underwater operations?

Submarines are designed to stay underwater for as long as possible, sometimes even when they are unable to surface due to conditions such as being under ice, like the USS Toledo.

Why is it necessary to create oxygen onboard a submarine?

Oxygen is essential because the crew consumes it and exhales carbon dioxide, which can sour the internal atmosphere if not balanced, making it uninhabitable.

What is CAMS and what role does it play on a submarine?

CAMS stands for Central Atmospheric Monitoring System, which is used to monitor the atmosphere at various locations within the submarine to ensure a livable environment.

How does the crew monitor different types of gases on the submarine?

The crew uses CAMS to monitor not only oxygen and carbon dioxide but also other gases like refrigerant R-114, hydrogen, and nitrogen to maintain a safe atmosphere.

What is the significance of the sniffer device used on submarines?

The sniffer device, or refrigerant leak detector, is used to locate leaks of gases like R-134 by detecting the gas and alarming when it's found, ensuring the safety of the crew.

How does the process of electrolysis create oxygen on a submarine?

Electrolysis involves using electrodes in purified water with potassium hydroxide as a catalyst to split water into hydrogen and oxygen, providing breathable oxygen for the crew.

Why can't electrolysis be performed directly on seawater?

Direct electrolysis on seawater would produce chlorine gas and hydrogen, which is dangerous and lethal, so the seawater must first be purified through filtration and reverse osmosis.

What are the two methods for creating oxygen on a submarine as mentioned in the script?

The two methods for creating oxygen on a submarine are electrolysis and the use of oxygen candles, which release oxygen through a chemical reaction without the need for electricity.

How do oxygen candles work and why are they useful?

Oxygen candles work by burning a mixture of iron and sodium chlorate, which releases oxygen. They are useful because they can create oxygen without electricity, providing a backup method in case of power loss.

What is the role of Monoethanolamine (MEA) in scrubbing carbon dioxide from the air on a submarine?

Monoethanolamine, or MEA, is used in a chemical absorption process to remove carbon dioxide from the air. It absorbs CO2 when sprayed over air in an absorber tower and then releases it when heated in a boiler stripper, allowing the MEA to be reused.

How is carbon dioxide removed from the submarine after being scrubbed by MEA?

After MEA absorbs CO2, the rich amine with CO2 is heated to release the gas, which is then compressed to the pressure of the surrounding seawater depth and released outside the submarine as fine bubbles.

What is the alternative method to MEA for scrubbing CO2 and why is it useful?

Lithium hydroxide is an alternative to MEA for CO2 scrubbing. It is useful as a passive means of removing CO2 from the atmosphere, especially in situations where the MEA system cannot be used, such as during power outages.