Page 263 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Mechanical Separations 233

Table 4-5
Application for Dust Collectors in Industry (cont.)
COLLECTOR TYPES USED IN INDUSTRY
Concen- Particle Cyclone High Eff. Wet Fabric Hi-Volt See
tration Sizes Centrlf- Collector Arrester Electro- Remark
Operation ugal static No.
Pharrnaceu tical and Food Products
"-• Mixers, grinders, weighing,
blending, bagging, packaging light medium rare frequent frequent frequent 39
b. Coating pans varied fine to rare rare frequent frequent no 40
medium
Plastics
b. Raw material processing (See comments under Chemicals) 41
a. Plastic finishing light to varied frequent frequent frequent frequent no 42
moderate
Rubber Products
o.. Mixers moderate fine no no frequent usual no 43
b. Batchout rolls light fine no no usual frequent no 44
c. Talc dusting and dedusting moderate medium no no frequent usual no 45
d. Grinding moderate coarse often often frequent often no 46
Woodworking
c . 'Woodworking rnachiues moderate varied usual occasional rare frequent no 47
b. Sanding moderate fine frequent occasional occasional frequent no 48
c. Waste conveying, hogs heavy varied usual rare occasional occasional no 49
By Permission John M. Kane, Plant Engineering, Nov. (1954).

REMARKS REFERRED TO IN TABLE 4-5

I. Dust released from bin filling, conveying, weighing, mixing, 20. Collection equipment expensive but public nuisance com-
pressing, forming. Refractory products, dry pan and screen- plaints becoming more frequent.
ing operations more severe. 21. In addition to grain handling, cleaning rolls, sifters, purifiers,
2. Operations found in vitreous enameling, wall and floor tile, conveyors, as well as storing, packaging operations are in-
pottery. volved.
3. Grinding wheel or abrasive cut off operation. Dust abrasive. 22. In addition to grain handling, bins, hammer mills, mixers,
feeders, conveyors, bagging operations need control.
4. Operations include conveying, elevating, mixing, screening, 23. Primary dry trap and wet scrubbing usual. Electrostatic is
weighing, packaging. Category covers so many different ma- added where maximum cleaning required.
terials that recommendation will vary widely. 24. Cleaning equipment seldom installed in past. Air pollution
5. Cyclone and high efficiency centrifugals often act as primary emphasis indicates collector use will be more frequent in
collectors followed by fabric or wet type. future.
6. Usual set up uses cyclone as product collector followed by 25. Where visible plume objectionable from air pollution stand-
fabric arrester for high over-all collection efficiency. ards, use of fabric arresters with greater frequency seems
7. Dust concentration determines need for dry centrifugal; plant probable.
location, product value determines need for final collectors. 26. Most cupolas still have no collectors but air pollution and
High temperatures are usual and corrosive gases not unusual. public nuisance emphasis is creating greater interest in con-
8. Conveying, screening, crushing, unloading. trol equipment.
9. Remote from other dust producing points. Separate collector 27. Zinc oxide loading heavy during zinc additions. Stack tem-
usually. peratures high.
10. Heavy loading suggests final high efficiency collector for all 28. Zinc oxide plume can be troublesome in certain plant loca-
except very remote locations. tions.
11. Difficult problem but collectors will be used more frequently 29. Crushing, screening, conveying, storing involved. Wet ores
often introduce water vapor in exhaust air stream.
with air pollution emphasis. 30. Dry centrifugals used as primary collectors, followed by
12. Public nuisance from boiler blow-down indicates collectors are final cleaner.
needed. 31. Collection equipment installed primarily to prevent public
13. Higher efficiency of electrostatic indicated for large installa- nuisance.
tions especially in residential locations. Often used in con- 32. Collectors usually permit salvage of material and also reduce
junction with dry centrifugal. nuisance from settled dust in plant area.
14. Public nuisance from settled wood char indicates collectors 33. Salvage value of collected material high. Same equipment
are needed. used on raw grinding before calcining.
15. Hot gases and steam usually involved. 34. Coarse abrasive particles readily removed in primary col-
lector types.
16. Steam from hot sand, adhesive clay bond involved. 35. Roof discoloration, deposition on autos can occur with
17. Concentration very heavy at start of cycle. cyclones and less frequently with dry centrifugal. Heavy
18. Heaviest load from airless blasting due to higher cleaning duty air filters sometimes used as final cleaners.
speed. Abrasive shattering greater with sand than with grit 36. Linty particles and sticky buffing compounds can cause
or shot. Amounts removed greater with sand castings, less trouble in high efficiency centrifugals and fabric arresters.
with forging scale removal, least when welding scale is Fire hazard is also often present.
removed. 37. Unit collectors extensively used, especially for isolated ma-
19. Operations such as car unloading, conveying, weighing, stor- chine tools.
ing. (Remarks cont. on next page)