Page 351 - Wastewater Solids Incineration Systems

312 Wastewater Solids Incineration Systems

a
TABLE C.3 Total equipment horsepower requirements for two incinerators at Westerly WWTP .
% Operated Estimated power, hp b
Item Rated Estimated Used
1. Quincy air compressor 25 75 19
2. Center drive shaft 20 75 15
3. Induced draft fan 250 75 188
4. Ash bucket elevator 2 75 2
5. Lower ash screw 2 75 2
6. Upper ash screw 2 75 2
7. Upper ash screw 1 75 1
8. Ash roll crusher 10 75 8
9. Burner air fan 75 75 56
10. Combustion air fan 50 75 38
11. Center shaft cooling fan 25 75 19
12. Stationary and rotary blowers 0.125 75 0
13. Long ash screw conveyor 3 75 2
14. Ash bin truck conveyor 3 75 2
15. Soot blower compressor 40 75 0
(Operated 10 min/d)
16. Oil cooling fan (center shaft) 0.5 75 0
17. Building drainage sump 150 50 75
18. Process water pump 250 50 125

Totals 909 551
a In accordance with a permit condition, the district is only allowed to burn wastewater solids in one of
Westerly’s incinerators at a time. As a result, a decision was made to set the average incineration related
horsepower at 275. Total hp 275.
b hp 745.7 W.

3.3.1 Operators

The cost of the four operators is calculated below:
Four operators $18.20/hr 1.4766 (benefits) 2080 hr/yr $223,593

3.3.2 Overtime
Instead of adding additional operators to the payroll, each of Westerly’s WWTP
incinerator operators typically works an additional 312 hours (15%) overtime per