Certain situations tend to leave a lasting impression. They make you change the way you see things. They change your perspective and often drive a sense of paranoia. Much like what’s been happening at work. I knew turbochargers are important. They use the exhaust generated in the engine to drive a turbine that forces in fresh air for combustion. So on and so forth. Little that I knew that when neglected they can cripple an engine.
When I joined I was assured by the previous third engineer that all was well and good with all the generators and that I would have a relaxed time. Right on the first day after he left, the load increased on the engine and the turbocharger started surging. Producing loud banging noise like a gunshot and vibrating heavily giving out puffs of smoke and destroying the air filters. I asked the second engineer about this and he said this is the first time it’s done that and it probably happened because of the sudden change in load. And that it’s okay.
The following day while doing a routine water wash of the turbocharger the same thing happened. And then the day after that. And the day after that. I knew something had to be done before this engine dies on me.
I opened up the air coolers first. Hoping that this is where the problem was. And I was partly right. I spent a day clearing out the cooler fins with strong chemicals and hot water. After letting it dry for a day I reassembled everything and gave it a try. But still nothing. The turbocharger still continued to give out gun shot noises of the same intensity. The air cooler was a part of the problem but not the root. I had to attack the source. It was a long shot and the senior engineers weren’t all that sure but they let me do my thing. The next day I got after the turbocharger.
It took me 4 hours in blistering heat to completely reassemble it. And by the end of that time, I was staring point blank at the problem. The nozzle ring was covered in heavy amounts of carbon deposits. The nozzle ring diverts the exhaust onto the impeller thereby streamlining flow of exhaust gas for optimum speed and smooth operation. If carbon deposits happen they reduce the size of the nozzles and this tends to speed up the exhaust gas. This turns the turbine faster which pumps more air than required for combustion. So when a load change occurs the excess air pressure inside is higher than the outside air pressure and it puffs out of the turbocharger sounding like a gun shot and vibrating the whole equipment in the process. And I’m not talking about a small gun shot like a pistol. I’m talking more on the lines of a world war 2 rifle. Bang!! And another Bang a few seconds later.
The nozzle ring was so badly stuck that I could not remove it from the casing. It had to be cleaned in place with whatever means I could use in that situation. I wasn’t completely happy with what was achieved but it was the best that could’ve been done at that time. The turbocharger was reassembled and I have the engine a spin. And not a sound. Perfect harmonious sound from the turbocharger, perfect air pressures and no more gun shots.
The engine has been improving constantly over the past 3 months now and I’ve been keeping a close eye. I call her Roxanne. She has a wild side. Get in her way and she bites. Get her away from your sight for a second and she turns suicidal. Ignore her and she will have her vengeance. It’s like a bad relationship but you want to stick around for the ride. You grab on and hang on for dear life and hope she’s gentle.
That’s Roxanne. Never a dull day.