Ships’ Turbocharged Engines Having grown accustomed to the din of the Engine Room Kawasaki-san recently mustered up the courage to venture inside alone to look around.Sitting noisily in the center of the Engine Room is the engine that supplies the motive force that propels the ship, Kawasaki-san learned the other day from First Engineer Y. “That’s a huge engine,” marveled Kawasaki-san to himself. He was told that it is as powerful as roughly 100 2,000-cc small-truck engines or some l2,000 horses. As Kawasaki-san was passing by the side of the engine, it emitted a loud noise that sounded like the high-pitched shriek of a monstrous bird. Startled, Kawasaki-san jumped about 20 centimeters off the ground. The noise was followed immediately by a sharp drop in the engine’s rpm. First Engineer Y then came rushing into the room.

“Startled you, didn’t it?,” he said to the dumbfounded, petrified Kawasaki-san. “But it’s OK. It’ll be back to normal shortly.” The First Engineer began to work on the turbocharger on top of the engine. After watching him for a while, Kawasaki-san asked the Chief Engineer, who was in the Control Room adjusting the engine’s rpm, “What happened?”

“ That was caused by a fluctuation in rpm due to a dirty turbocharger. In technical parlance, it's called surging. If we left it alone, the turbocharger would break down, causing the engine to shut down ”

“ What does the turbocharger do? ”

“Kawasaki-san, you’ve heard of a turbocharged engine in cars, haven’t you? A ship’s turbocharger is exactly the same. It utilizes the energy of the engine’s exhaust gases to turn the turbocharger’s blade. On the other end of the same shaft is a blade that compresses air and pumps it into the engine. That’s the turbocharger’s function. Thanks to this turbocharger, even a small engine can generate a lot of power. By effectively utilizing exhaust gases, it kills two birds with one stone.”

“ Really?I’m familiar with the term turbocharged engine, but that’s all. Until now, I didn’t know what a turbocharger does. So now the First Engineer is cleaning the turbocharger to remove the dirt that caused the surging. ”

“ That’s right. You’ve become quite a fast learner. In addition to the turbocharger, there’s another device that likewise uses the engine’s exhaust gases to effectively collect energy that would be emitted into the atmosphere. ”

“ Another one? Is that one also used in cars? ”

“ Unfortunately, it’s unique to ships. It’s called an exhaust gas economizer, or E.G.E. for short. It’s installed inside the smokestack. In simple terms, a bunch of pipes is installed inside the smokestack. The pipes have water flowing through them and they perform heat exchange on the heat of the exhaust gases emitted by the engine. This heat is put to effective uses such as heating water or generating steam. The turbocharger and exhaust gas economizer are essential for boosting a ship’s power and conserving energy, but recently they have increasingly been experiencing problems due to deterioration in the quality of fuel oil. One type of problem, like the surging that just happened, is caused by dirty exhaust gases due to poor combustion. The other type of problem is caused by corrosion due to sulfur and other impurities in the fuel. ”

“Why do we have to use such poor-quality oil?”

“Fuel costs account for about 20% of a ship’s total operating expenses, Which is a pretty big share. To reduce operating expenses, we have to use cheap, low-quality oil. For example, grade-C fuel oil is thick like sludge at room temperature, so we have to heat it with steam. We also have to use oil purifiers and other such equipment to remove various impurities from the oil. This equipment also causes problems. If we used high-quality fuel oil, like a car uses gasoline, there would be a lot less equipment in the Engine Room and it would be much easier to use. ”

“What’s the difference in price between automotive gasoline and grade-C fuel oil? ”

“Grade-C oil is about one-fifth the price of gasoline. And grade-A fuel oil is about twice as expensive as grade C ”

“ Wow, that is a big difference. ”

“The First Engineer who had been cleaning the turbocharger returned to the Control Room, wiping the sweat from his brow. ”

“Good job. Let’s report to the Captain and rev the engine back up.”

From the healthy roar coming from the turbocharger, Kawasaki-san could tell that the engine’s rpm was gradually increasing. Looking up again at the turbocharger, Kawasaki-san marveled anew at its size.

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