use of Ultrasound in Electrical and Mechanical Applications in Thermal / Gas Power Plant

There are lots of uses of ultrasound in power plants such as leak detection, bearing analysis, valve inspection, steam trap analysis and etc. CSI has one such product in the market,SONIC SCAN.

SonicScan_Fault_Isolation_System_pds.pdf (144 Kb, 19 downloads)

Ultrasound for Power Plants.
Leak Detection:
a. Boiler Leaks (heat rate problems).
b. Steam traps Diagnostics
c. Heat Exchangers for leak detection?
Both on-line and off-line.
d. Condendsor Leaks
E. Expansion Joint Leaks
f. In-leakage around turbine shaft and access plates (on-line).
g. Compressed Air Leaks
h. High Pressure Steam Leaks
i. High Pressure Steam valves.
j. Hydrogen Leaks
Electrical:
k. Switchgear (corona, tracking & arcing)
l. Substations (corona, tracking & arcing)
m. SF-6 Breakers (gas leaks) & (corona,
tracking & arcing)
n. Transformers Nitrogen Blanket Leaks.
o. Transformers Pumps and Fan motor bearings.
p. Transformers Internal Arcing
q. Transformers (arcing, tracking & corona)
Mechanical:
r. Bearings
s. Slow Speed Bearings (under 300 rpm's)
t. Acoustic Lubrication
u. Gearboxes (bearings & gears)
v. Pumps for Cavitation
x. Pumps bearings
Other Leaks Detection:
y. Soot Blowers for Leaks (flanges & manifolds)
NUCLEAR:
z. Containment Wall Inspection (Leak Detection)

HOPE THIS HELPS YOU........

[quote]
Thanks Jim , Iqbal for listing the applications .

Are PDM managers working in Power Plants in your countries implementing programs on regular basis for these applications as they do for Vibration / Thermography ?

Can somebody explain me the following applications in detail :

z. Containment Wall Inspection (Leak Detection)

c. Heat Exchangers for leak detection?
Both on-line and off-line.

d. Condendsor Leaks

e.In-leakage around turbine shaft and access plates (on-line).


Wishing All Very Happy New Year

Yes,
z. a containment wall refers to the building housing the reactor head. During construction and/or on a periodic inspection for wall integrity, airborne ultrasound (high frequency scanner same that is used for air leaks) can be used to locate leaks in the wall once the wall is pressurized. Sometimes the reactor wall must be accessed for repairs of the reactor head. A hole must be made into the wall by disintegrating the concrete surrounding the rebar, cutting and removing the rebar that makes up the containment wall. After rebuilding the wall and pressurizing it GROSS leaks can be heard first before proceeding to more refined leak methods.
c. Heat exchangers are typically u-tube type exchangers. Others maybe straight tube construction. Some power plants I have been into that have u-tube type I have been able to train them on how to inspect the H/exch with airborne ultrasound both on-line and off-line.
On-Line: Using the contact probe on the outer shell of the h/exch you should divide the shell into 4 sections, each section has 4 inspection points (North, South, East, West), using the contact probe touch those points and listen for a popping sound similar to what steam flashing would sound like. The point or points with the loudest sound is of close proximity to the leak.
Off-line: You should expose the tube sheet at one end, pressurize the shell and scan the outer periphery first working your way through the tube sheets listening for the sound of air leaking, you can also the rolled end of the tube as well. I personally do not use the tone-generator method for this operation due to the density of the tubes within the shell it is not as effective as pressurizing the shell with deck air or a dry nitrogen. Caution: Be sure to completely blow out each tube of any water before performing the off-line inspection.
d. Condenser Leak:
Condenser tube leaks are typically noticed when the sodium level rises. Sensitive sodium parts per billion (ppb) counters are in the condensate pump discharge system. If the sodium level is high, the plant can go to a "partial load".

(A partial load means the turbine above the water box is still turning and after isolating and draining the water box while the turbine is still turning will produce a negative pressure surrounding the tubes (steam side) within the tube bundle. The negative pressure will produce turbulent flow (a vacuum) at the mouth of the tube sheet that can be heard by the ultrasound receiver).

This will allow the technician to enter the water box and scan using the airborne scanner to find tube leaks. Most ultrasound detectors are not sealed WELL ENOUGH to handle the high humidity for more than a few seconds (SDT170 is very well sealed for this operation). Once you enter the water box you can scan close to the tube sheet listening for sound of an air leak, at this time you can place a rubber cone or use a flexible wand to reach the tubes so that you can scan across the tube opening to listen for an increase of sound indicating that the tube is leaking.
e. In-Leakage around turbine shaft and access plates (on-line):
Airborne ultrasound use is often limited to the user of the instrument. Such is the case with finding control air leaks on jet engines. For instance the dynamics of the surrounding especially for humans (we have several openings of the head) the sounds around us makes it almost impossible to hear through the headphones let alone concentrate on hearing a leak. With a steam turbine much the same is so. I have heard in-leakage around the turbine shaft using an airborne ultrasound receiver. It took awhile for me to get USED to the surrounding sound to find the leaks. The volume in the headset has to be high, but, more than that they have to be of the highest quality

(Sometimes I will use the headset of one instrument on another ultrasound instrument by using a Radio Shack adaptor, because the noise cancelling effect of one manufacturer’s headphone and the sensitivity of another instrument is better)

Access plates as well, this access doors or plates are removed for turbine maintenance periodically. They are very hard to seal properly, using an airborne scanner and a glove on one hand to block competing sounds is a good proactive to locating leaks around these points.
Jim (Ultra-Sound Technologies)

Jim thanks for very good explanation two things I will like to understand is
1) Could you please explain on Boiler Leaks (heat rate problems)

2) What are the precaution one has to take while using the Parabolic Dish for Overhead compressor lines with lot of pipes carrying other gase near by . How do you suppress the suurounding ultrasound.Is it effective for overhead inspection.