Please find Boiler Tube Research Part 5 for previous explanation.
XRD analysis of the deposit part in a pipe 4 on the image 3.34 is part of a pipe in 4 who experienced plastic deformation torn up to. Seen all the difference in color deposit in the area around rips. XRD analysis was conducted in three locations as seen in the picture. And the result can be seen in images 3.35 to 3.37 as well as table 3.11 to 3.13 .
From the analysis result of XRD shown that there is a fine coating of different deposit around the area that get torn. Deposit formed namely namely hematite and chromium carbide. That factors affect the establishment of chromium levels carbide is carbon temperatures and high. If viewed from result test material composition, having pipe 4 of carbon large enough exceed to the maximum levels allowed. And high temperatures experienced pipe 4 cause the possibility of the establishment of this chromium carbide.
Mechanical and thermal analysis in Pipe 3.
Based on analysis of a visual inspection and metallurgy earlier , the greatest damage to the pipe 3 is the depletion of the outer wall. This is because eroded due to depletion of the wall and on occurring thin the part most torn that causes leakage.
Based on this case , which appears that hypothesis is that this happened because of depletion of continuous erosion in the same place in the pipe this 3. The cause of the most experienced is probably misdirected soot blower. High pressure steam produced by the soot-blower carrying accompanied by the possibility of condensed water and fly ash as particles of solid make the mechanism of erosion was faster and exacerbate the process of depletion of the wall in a certain area until the level of the thickness of the walls of certain, pipes are not able to withstand more internal pressure from this re-heater in a pipe , and finally this pressure to tear a pipe and causing leaks. This will then hypothesis' evidenced by a simulation of supporters as described in sub chapter 3.6.
Mechanical and thermal analysis in Pipe 4.
Pertaining to the failure of the 4 it was apparent that the four had crash and a deforming large enough to tear a pipe.The largest of this is because the soot blower experiencing misdirected that strikes the 4th and at the same time the blower supposed to spray the sidelines of the pipes of shifted to the pipeline themselves (in this case the 3rd). Based on the information obtained in the field that was a nuisance to soot blower is stuck at operate ( of no return to the original position since stalled something). This incident had occurred before the pipeline detected damaged on 3 and 4.
If seen from the form of the destruction of the 4 the probability of which is hitting sootblower the fourth part of a thread 3.38 looked at the picture.High temperatures in both inside and outside the operation hours is a long time and is likely to decline in a metal pipe, so that when the next crash damage occurs as mentioned above.Which is based on section of that hypothesis 3.6 will support it.
to be continue...
Please find Boiler Tube Research Part 5 for previous explanation.
Please find Boiler Tube Research (Re-Heater) part 4 for previews explanation.
Hardness test on part 4 as below...
From the analysis of the photo the micro structure and the violence / hardness test in the area 4 pipe damaged can be inferred:
1 Defect happened because of a conflict from the outside so plastic deformation occurs. Plastic deformation allegedly happened at a high temperature ( above a recrystallization ), because seen no change the micro structure occurring significantly.
2 The results of the violence / hardness test also show the possibility of a conflict at high temperatures where the value of violence / hardness tends to decline.
3 Of the results of a photograph of SEM visible cracks that happened due to plastic deformation.
4 From the EDX found indications of those compounds from outside the pipe as al2o3 4 , sio2 , fe2o3 that might exist or attached to objects that hit pipes 4 .
Pictures 3.30 is passage in a tubular 3 that experienced rips. Appear to be any differences in the hues deposit around the area rips. The XRD analysis done in three locations such as can be seen in such a figure.
The results of the analysis XRD pipe 3 was in this picture 3.31 until a picture 3.33, as well as table 3.8 up to table 3.10.
Of the analysis result of XRD it is evident that there is a fine coating deposit vary in several locations. This indicates that such a possibility a crack that happened was long enough. Hematite , magnesium and calcium hydroxide carbonat is deposit of a kind of water-formed deposits
to be continue to Boiler Tube Research Part 6.
Every coal has different of properties and while the coal delivery has change, it would be make boiler combustion change too.
It needs calculation special logic diagram to monitor how much coal heating value that is burning and the calculation result of heating value is using for input data of air and coal fuel consumption.
The simplified of the logic can be express as power plant basic control. For example if the boiler is controlling the load and the turbine control valve is controlling the main steam pressure, while the coal delivery is changing from higher heating value to the lower one, the main steam pressure will decrease a little bit.
To compensate the decreasing of main steam pressure, the boiler need coal combustion more to maintain stable the load. For this reason that logic got name "energy per unit mass compensation".
Let's consider picture below that Boiler Master is setting from Unit Control and feedback signal from generator load. Also on Turbine Control is setting from unit control and feedback signal from main steam pressure. This logic control assume coal heating value 24,697 kJ/kg.
Four pictures below are breakdown from Boiler Master that got change of coal heating value.
Next calculation http://anto-hendarto.blogspot.com/2009/01/coal-calculation.html
Fuel Air Master demand get input signal from Boiler Master demand. This was set beginning by coal characteristic that will be used, for example bituminous coal which has coal heating value around 24,697 kJ/kg as blue color. That is using as SV (set value) for the Fuel Air Master PID control.
And the yellow color tell about Excess Air program from Boiler Master Demand 200MW to 720 MW. The output set value for 200MW around 44% and for 720MW around 13%.
Operator can do increase or decrease the excess air program from the bias by feedback from actual gas analyzer.
The output from PID control is giving to each Pulverize Group Control input signal. 100% is linearly with 70T/h.
These two picture below are describing Fuel Air Master Program as input for Primary Air Flow Demand. For example, 72.08% Fuel Air Master has output 86.04% Primary Air Flow demand equal to 92.92 T/h.
These two picture below are describing Fuel Air Master Program as input for Secondary Air Flow Demand. For example, 73.21% (after add with excess air program and assumed Fuel Air Combustion Correction is zero) Fuel Air Master has output 77.14% Secondary Air Flow demand equal to 273 T/h.
This table can be read that secondary air flow demand with Fuel Air Master 72.08% is 304.67 T/h. It means Fuel Air Combustion Correction is 37.67 T/h
These three pictures below are describe Fuel Air Master for Air Combustion completely.
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