Info

—1-1—

FIG. 5.23.2 Wet suppression system at a crusher discharge point. (Reprinted from C. Cowherd, Jr. and J.S. Kinsey, 1986, Identification, assessment, and control of fugitive particulate emissions, EPA-600/8-86-023, Research Triangle Park, N.C.: U.S. EPA.)

FIG. 5.23.2 Wet suppression system at a crusher discharge point. (Reprinted from C. Cowherd, Jr. and J.S. Kinsey, 1986, Identification, assessment, and control of fugitive particulate emissions, EPA-600/8-86-023, Research Triangle Park, N.C.: U.S. EPA.)

and its operations and the requirements of operating personnel. The engineer must evaluate the materials in the dust in addition to the particle size and define the characteristics of the material including the auto-ignition temperature, explosive limits, and the potential for electrostatic buildup in moving these materials. The engineer must locate the pickup and select the components to be used in the system.

Each operation generates various amounts of dust. The environmental engineer uses the amount of dust, the particle size, and the density of the dust in determining the capture velocity of the dust, which affects the pickup or hood design. Normal capture velocity is a function of particle size and ranges from 6 to 15 ft/sec (Opila 1993). In practice, the closer the hood is to the dust source, the better the collection efficiency is and the less air is needed for the collection process. The engineer should design enclosures and hoods at suitable control velocities to smooth the air flow. Examples of dust collection follow (Kashdan, et al. 1986):

A bag tube packer (see Figure 5.23.3) where displaced air is treated from the feed hopper supplying the packer, from the bag itself, and from the spill hopper below the bagger for any leakage during bag filling Open-mouth bag filling (see Figure 5.23.4) where the dust pickup hood collects the air displaced from the bag Barrel or drum filling (see Figure 5.23.5) that uses a dust pickup design with the same contour of the drum being filled. The pickup is designed for a single drum diameter; the design becomes complicated if 15, 30, and 55 gal drums are filled at the same filling station. The height and diameter of these drums vary affecting the capture velocity of the air. The pickup of dust created when material flows down a chute onto a conveyor belt (see Figure 5.23.6) The pickup points required for dust-free operation of a flatdeck screen (see Figure 5.23.7)

0 0

Post a comment