Diagnosis of steam generator by estimating an unobserved important state variable

Figures & data

Figure 1 A schematic of “Monju”

Figure 2 A simplified model of superheater

Figure 3 A simplified model of evaporator

Table 1 Peak frequencies of process signals obtained by frequency analysis and setting frequencies of Butterworth filter

Process	Peak frequency	Passband edge	Stopband edge
signal	[Hz]	frequency [Hz]	frequency [Hz]
MW	0.005442	0.006	0.007
T N in SH	0.000333	0.001	0.002
T N out SH	0.000136	0.001	0.002
T N in EV	0.000136	0.001	0.002
T N out EV	0.005442	0.006	0.007
T W in EV	0.000068	0.006	0.007
T W out EV	0.005442	0.006	0.007
T W in SH	0.005442	0.006	0.007
T W out SH	0.000068	0.006	0.007
P W in EV	0.005669	0.006	0.007
P W out EV	0.005669	0.006	0.007
P W in SH	0.005669	0.006	0.007
P W out SH	0.005669	0.006	0.007

Figure 4 A noise-filtered process signal of temperature of liquid sodium at the inlet of evaporator; blue line is simulated process signal and red line is noise-filtered process signal

Table 2 The rate of relative errors of K _SH and K_L that are more than ±0.5%

Averaging time of
process values	K SH	KL
1 minute	40%	66%
2 minutes	18%	37%
4 minutes	0%	0%

Figure 5 The estimated results of the overall heat transfer coefficient using time-averaged process values per 1 minute; blue line is the relative error of K _SH and pink line is the relative error of K_L

Figure 6 The estimated results of the overall heat transfer coefficient using time-averaged process values per 2 minutes; blue line is the relative error of K _SH and pink line is the relative error of K_L

Figure 7 The estimated results of the overall heat transfer coefficient using time-averaged process values per 4 minutes; blue line is the relative error of K _SH and pink line is the relative error of K_L