Have you ever started a project that you assumed was going to be a simple thing, and then it turned into something totally unexpected?
Sort of like going after an electrical problem in your car – you start out looking at the fuse box and end up with the entire dash spread across the passenger seat.
In our line of work, we are called in to do a lot of testing at various plants, and it’s often considered routine testing where we don’t expect to find anything substantial.
Having just returned from a delightful job at a power plant located in a part of the world that replicated the atmospheric conditions of Antarctica and the social conditions of the Tsar and Rasputin, I was ready for a nice, easy test in a warm, cozy, quaint locale where everyone spoke the same language.
Therefore I was pleasantly surprised when Greg Gigawatt informed me that he scheduled a test for us at the tranquil South Livingston Electric Energy Power Station (SLEEPS). This is a plant that always does all its maintenance, never has a forced outage and its emissions
Greg and I walked off the airplane (where we were both upgraded to first class) and to the car rental counter where we were informed that we were – yet again – upgraded to a Lamborghini.
Arriving at the station, we were greeted by the performance engineer and our testing specialist, Jonny Joule, who informed us that all the instrumentation was installed and working like a champ.
Even though this was our first time at the plant, I felt that this test was going to be a snap. Jonny had already performed a dry run and the plant staff said that everything looked very good. So Greg and I sat down and started looking at the data, which seemed to just be a formality at this point.
As we were sitting in the 30´ x 30´ office space the plant had provided for us, with full fiber optic internet access at the highest speeds we had ever seen, I saw this little flash in Greg’s eyes that told me this was not going to be such a peachy job after all. He asked me to have a look at the air heater gas outlet temperatures. The air heater gas outlet temperatures between the A and B air heaters were about 30 degrees different, and there were differences in the air outlet temperatures as well as.
“I think we might have some heat transfer issues,” Greg surmised.
I checked the latest performance report from the plant, but there was no mention of any problems.
We asked the performance engineer about it. He brought up a trend of the temperatures on his 90? monitor and we noticed Air Heater A & B gas and air outlet boundary temperatures had been showing a difference for almost two years. We picked up the phone and talked to the control room about the condition of the soot blowing system. They informed us that based on their indications, everything was working just fine. Greg and I looked at each other. So much for a vacation.
We walked out to the plant to find Jonny holed up in his air conditioned testing office with our computer. We asked him to check out the air heater temperature indicators we had installed, to make sure they were working as expected. While Jonny was checking out our instrumentation, Greg and the performance engineer went to look at the soot blowing equipment. I went to the control room to see what indications they were using to determine that the soot blowing equipment was working. When they turned the soot blowing equipment on, the indicator light said it was on, and that was their sign that all was well. I asked when they last did soot blowing, and then went back to look at the performance data. It told me that the A–side did not improve very much after the cleaning.
Greg, the performance engineer and I met with Jonny in the office and went to the white board (the one with the built-in printer). We looked at the data we had taken to see how the air heater performance stacked up against the baseline values. The current values were significantly different than the baseline values. So now we had two problems, there was a significant difference between the A & B air heaters, but the absolute values were very different than the baseline values. Greg asked what kind of coal they were using and found out that a while back they had switched to Powder River Basin (PRB). Gas exit temperatures using the design coal were substantially lower than those burning the PRB coal. Reviewing previous plant data confirmed the lower temperatures before the PRB coal usage (about 265°F-275°F). We suggested that they establish a new baseline using the PRB coal.