Years ago, my brother and I were working on his VW Squareback (and if you recognize that, join the grey hair club). We discharged the battery 4 times and the car still would not produce self-sustaining combustion. We were sure the problem was the carburetor. After about 36 hours of work, we stood there dumbfounded, staring at the silent engine. Then out walked our Dad, who took one look and said, “Is this wire important?”
It was the wire from the coil to the distributer.
Moisture separator reheaters (MSR) are particular to nuclear power plants, but the things we can learn apply to fossil plants as well. Most nuclear power plant steam generators (boilers or HRSGS to our exclusively fossil or combined-cycle types) produce saturated steam. By the time it goes through the HP turbine, there is a significant amount of moisture in the steam.
In a nuclear plant, there are no IP turbines. Not wanting to turn the LP turbine into a water wheel, this moisture is removed by a moisture separator and heated in a reheater. Sometimes the reheater has two stages,
Gregory Gigawatt and I had just gotten off the plane from BTU city when I noticed I’d missed a call. The message: “Hey, Mr. Megawatt, this is the shift supervisor at Metropolis Nuclear Power Station. We have a problem with our moisture separator, Superman is still trying to figure out entropy so we need you to come and take a look. Oh, and bring your tie.”
The last part of that message gave me pause; it was a clear indication of management frenzy.
After going through the security check points, we sat down with Steve the Salty Shift Supervisor, or S4, to discuss the situation. Steve informed us that second-stage reheater steam supply flow was way up, LP inlet temperature had been decreasing, and they were down a few megawatts. They had put together action plans, Kepner-Tregoe analysis, and root cause analyses, and then proceeded to implement multiple troubleshooting procedures with peer checks, all to no avail. Their plant indicator now had a sad face and management wanted the smile back again. We had worked with S4 before and knew that if he was stumped, we were in big trouble. He was one of those rare shift supervisors who had been around long enough to know the turbine side of the plant better than most. My first question was, “When are you going to be on mid-shift so we can come in and talk about this without extra help?”
So we had three days to look over some data and evaluate some hypotheses before we could do a plant walkdown.
We looked at some plant data and came up with the following facts:
- The A-side LP inlet temperature had decreased about 20°F
- The turbine first-stage pressure had decreased about 0.5 percent
- The steam flow to the second stage reheater had increased about 150 klbm/hr
- The final feedwater heater extraction pressure was down about 1.5 percent
- Final feedwater temperature had decreased about 2°F
- Feedwater flow had decreased about 40 klbm/hr
- First stage reheater drain flow also decreased to almost nothing
The system engineer said we should not trust the first-stage reheater drain tank flow because it had been jumping all over the place and was not indicating correctly. I glanced at Double G and he gave me the look that said, “Where have we heard that before?”