I cannot speak for measuring the LOI on-line but if you relate LOI to Particle size, My company have an on-line particle sizing system that is extensively used for Cement mill monitoring & control and is now being included in several applications for PF (Pulverised Fuel). The same system can be employed for dry powder measurement in the range 0.5-1000um and can also measure dilutable slurries.

Please contact me for more information about On-line measurement of particles.

carl.sabin@malvern.co.uk ■

Dear Mr. Svanberg,

there are several methods to determine particle size distributions in fly ash.

Online determination can be done locally e.g. at a sample pipe from a chimney, by time-of-flight analysis. The particles suspended in the gas are sucked through an acceleration nozzle. The acceleration is dependent on the aerodynamic particle diameter. At the exit of the acceleration nozzle you have two laser beams. Particles cross the laser beams and produce two signals per particle. The time between the two signals determine the particle time-of-flight. These time-of-flight is correlated to the particle aerodynamic diameter and can be calibrated so that no mathematic algorithm is necessary. By overlapping the two laser beams you get an combined signal for each particle. This technology provides an automated correction for coincidence and false particle counting. In summary the time-of-flight technique using overlapping laser beams provide a very high size and time resolution, crucial for doing online-size determination.

Online determination can also be done by light scattering. That means that you have only one laser beam. A particle crossing this laser beam scatters the laser light. With complex mathematic calculation you get a size information from the scattered light. The disadvantage is that it is only a size information, not the actual particle size, because the scattered light depends on the particle material (which is complex in fly ash), like chemical composition and refractive index. Latter doesn't allow a direct calculation of the particle size from the amount of scatter light.

TSI is a very well known manufacturer of different techniques for particle size distribution determination. The time-of-flight technique with overlapping beams could be the best suitable technique for your issue and is realized in an instrument we call aerodynamic particle sizer (APS). See http://particle.tsi.com for further information.

There is much more to tell about particle size determination, but that wouldn't fit in this screen. Do not hesitate to ask further questions for more details.

Best wishes,

Axel Zerrath

Applications Engineer

Particle Instruments

TSI

axel.zerrath@tsi.com ■