Majari Magazine

Chemical Engineering is Everywhere

by Michael Hutagalung on 01/11/07 at 12:26 am | 3 Comments | |

When I was thinking about writing this article, I was sitting on a bench in Red Roll Cafe at The Majesty Apartment Bandung. Waiting for the meal to be served, I saw peoples walking here, there, and everywhere. On my table, I noticed an AQUA bottle that I brought from home. I usually refill the bottle with fresh water and reuse it as my daily drinking water container. Suddenly I remembered the time last night I was in the kitchen, spending a minute or two, trying to help my mom even though I realize that I wasn’t really doing a thing.

Last night, I rinsed the bottle with hot water then placed on the cap back onto the bottle. The appearance of the bottle reminded me of an important lesson that chemical engineers have learned over the years. I read many reports of large chemical processing vessels collapsing after being cleaned with steam. Usually, the cause of the incident was that the operator sealed the vessel too soon after cleaning. If all of the steam has not yet condensed and the vessel is sealed, the pressure inside the vessel will decrease (below atmospheric pressure) as the steam condenses. Essentially, a vacuum is formed as the volume of the water vapor decreases. The same mechanism is what caused the plastic bottle to “suck in”. As the water cooled and condensed, the pressure inside the bottle decreased and atmospheric pressure pushed the sides of the bottle inward. A simple, yet important lesson for us, a chemical engineering student. Many tanks and process vessels have been destroyed by this action.

Anyway, it’s unhealthy to reuse the AQUA bottle again and again especially if you often wash it with hot water or expose the bottle to direct sunlight in a certain period of time. Particular amount of heat will destroy some of the polymer particles and will be dissolved in the water we refill in. Have you ever thought of ‘eating’ polymers? (*LOL)

Another item caught my eye in the kitchen that evening. A simple plastic soda bottle. Many people don’t realize that these bottle are made of polyester! Even many people do not know what polyester is. They just say ‘plastics’. From trash bags to cellphones, it’s all plastics!

Anyway, polyester is manufactured in large scale chemical plants just like most chemicals. At the end of the process, the plastic is cut into tiny chips as shown below. These plastic chips are then sold to companies that use a process called injection molding to make bottle preforms. The preforms are then packaged and sold to bottlers of the end products whether it be soda or something else. The bottler uses a technique called blow molding to inject hot gas into the preform and “blow” it out the final size.

Finally, I noticed the water filter on my kitchen sink. This filter contains one of the oldest filtration medias known to chemical engineers: activated carbon. Via a process called adsorption, small particles adhere to the activated carbon as the fluid passes through the filter. Chemical engineers have long used activated carbon to purify liquids and gases. Perhaps the most common application in use today in the chemical industry is the use of carbon to remove tiny particles from gas streams before they are released to the atmosphere. Without the activated carbon, these particles could make the surrounding area a very unpleasant place to live or work. The actual activated carbon filter applications may be seen in the above banner. It is a picture of filters in a water treatment plant.

Showing people that chemical engineering touches their lives everyday is easy. From plastic bottles to activated carbon filter, you can find many more examples. It’s also important to note that chemical engineers can also learned some things from the home as is evident with the collapsing water bottle. Maybe the industrial world and world that we call “home” aren’t so different after all.

Reference(s): Wikipedia – Activated carbon filtering, Wikipedia – Blow moulding, Other sources.