Instrument for Steam, Air, or Nitrogen Blow Monitoring
Steam, air, or nitrogen blowing of piping, superheaters, and reheaters occurs after erection, repair, or chemical cleaning.  It consumes energy and time, so that monitoring its effectiveness is important.  Up to now, the process has been judged largely on the basis of experience.
A new instrument fulfills the need for direct inline, on-line monitoring by electronically determining the impacts of individual contaminating particles on a target probe permanently installed in the system to be cleaned.  The instrument determines both the number of particles and the mass of each particle.
Information supplied by the instrument relates the number and size of particles to the progress of the blow, to the length of individual blows, and to other parameters - such as blow time, pressure, temperature, and flow velocity.
The instrument has applications in monitoring of startup of major components and protection of turbines and valves from foreign-object damage.  One instrument, permanently installed for several years, has been monitoring oxide exfoliation, a condition that can cause solid-particle erosion of a high-pressure turbine.
The probe location is close upstream of the end valve.  Velocities there are only a few hundred feet/sec, so the probe is not damaged by vibration.
Results of four steam blows
Figure 1.  Results of Four Steam Blows of a Superheater and Reheater.  Areas Under the Curves Represent the Particle Mass Removed During the Blow.