Technical Specifications (PPC)

Available in fixed or semi-portable installations, the PPC is an optimal answer to the need for in-process particle characterization of dilute process streams in hostile environments. The PPC has been proven in such applications as: Fossil Energy Combustors Hazardous Waste Processing Incineration Facilities Powder & Materials Process Streams Filtration Efficiency Measurements

Size Range General capability from 0.2 to 200 microns Typical configuration is 0.4 to 80 microns Concentration Submicron: up to 107/cm3 (typical up to 106/cm3 Supermicron: to 10 PPM by volume Flow Velocity 0.1 to 400 m/sec up to 500,000 measurements/second Accuracy / Precision Accuracy: ±5% of indicated size Precision: ±3% of indicated size Verification via ASTM reference standard reticle Remote Operation Control PC to signal processor/optical probe:  1,000 meters thru Ethernet connection Explosion proof / waterproof enclosures available Instrument Design The PPC system is an optical single particle counter consisting of an optical sensor head, and electronics interface/signal processing enclosure, and a computer to run the data collection and display software. The sensor requires clean, dry compressed air and electricity.  The probe form of the optical head requires a water-flow to cool the sensor at high temperatures. Optical Sensor Two interface packages are available, a low pressure- high temperature flow cell or a high pressure-low temperature cell.  The probe is designed so that it can also be inserted into a gas flow.  The optical parameters can be customized to suit user's specific particle size and concentration requirements.  Particle measurements are based on analysis of light scattered by single particles passing through the focused laser beams. Signal Processor This enclosure contains modules for processing of signals from the sensor probe, and interfacing with the computer. Communicaton between the computer (typically a laptop) and the signal processor is by ethernet.  The signal processor must be within 7 meters of the sensor, while the distance between computer and signal processor is unlimited via Ethernet.  Enclosures can be provided for standard laboratory environments or to meet explosion/waterproof requirements. The enclosure requires input power of 88-258 Vac, 47-63 Hz. Software PPC software offers: Windows based color graphics program for data acquisition, processing, and display.  Continuous real-time display of a wide range of particle distribution parameters. Flexible data formatting Process Interface Options Two standardized mounts have been designed that allow customization of the PPC for a wide range of applications. High Temperature Probe (up to 1400C):  The water-coolde optical probe measures 9.5 cm OD and accommodates insertion lengths from 1 to 5 meters.  The gas-purged window system has an 8 cm x 3 cm aerosol flow access region.  The probe is ideal for measurement through an access port of 10 cm or larger. High Pressure Probe (up to 150 bar):  A high pressure flow cell is used for extraction measurements from high pressure systems.  Temperatures up to 500C have also been measured.

Layout of water jacket and PPC probe for in situ high temperature applications. PPC probe (3” dia.) is inserted into 4” dia. water jacket and lined up with 1.3” x 2” open slot. Maximum insertion distance is 2 meters for 8’ long water-cooled jacket.

Typical Installations The probe has an extensive history in combustion research, and has been used to measure burning coal particles in small scale reactors up to 500 megawatt boilers.  Other applications include filtration measurements upstream and downstream of electrostatic precipitators, baghouses, mist eliminators, cyclone separators, and paint booths. Example Results in a pulp and paper Recovery Boiler Figure 5. shows results from a pulp and paper recovery boiler (@ 700C) giving the absolute concentration Number Frequency distributions.  The measurements are restricted to particle sizes greater than 5 microns for this application because the focus of the DOE study was to understand the deposition characteristics of particle formation and deposition in the 5-100 micron size range.  These results show a factor of >10 decrease in the particle concentration as the flow passes through the major heat transfer sections of the boiler.   These results also provide a direct measure of the total mass of material in the boiler, which is more accurate than conventional sampling measurements by extraction.  Conventional Impactor measurements are less accurate because of fume deposits in the sampling probe and unknown re-entrainment.

Even more importantly, the real-time PPC can show the extreme time variation of particle concentrations as shown in Figures 6 and 7.  Figure 6 shows a factor of 10 variation in particle concentrations over day long periods.  Figure 7 shows similar factors of 10 countrate fluctuations over periods of less than a minute.  These measurements show that the boiler system is fluid-mechanically bi-stable and improvements in performance require stabilization of fuel/air mixtures at the boiler entrance.  Results of this kind cannot be obtained by other than an optical measurement technique such as the PPC.

For information regarding the Process Particle Counter (PPC) contact: Donald Holve, Ph.D. dholve@processmetrix.com voice: (925) 460-0385 x116