276 ENVIRONMENTAL ENGINEERING
Figure 14-2. A shredding facility showing the conveyor belt leading to a vertical
shredder.
Shredder Performance and Design
The performance of a shredder is assessed by the degree of particle size reduction
achieved and then compared with the cost in power and shredder wear. The parti-
cle size distribution of a nonhomogeneous material such as municipal solid waste
(MSW) is expressed by the Rosin-Rammler distribution function (Rosin and Rammler
1933)
where
Y = the cumulative fraction of particles (by weight) less than size x,
n = a constant, and
n, = the characteristic particle size: the size at which 63.2% of the particles
(by weight) are smaller (1 - 1 /e = 0.632).