A positive displacement, electric motor driven, air cooled compressor shall
be provided for circulating the digester gas. The compressor shall be
capable of providing [_____] cubic meters per second cfm of gas at [_____]
kPa psi and shall be driven by a [_____] kW horsepower explosion-proof
electric motor. The motor shall operate on [_____] volts ac, [3] [_____]
phase, 60 Hz. Motor shall conform to NEMA MG 1. Controls shall conform to
NEMA ICS 1, NEMA ICS 2, NEMA ICS 3, NEMA ICS 4, NEMA ICS 6, UL 845, and UL
508. Panel shall be NEMA 250, Type 7. Motor power shall be transmitted to
the compressor through a static-conducting V-belt drive.
2.5.2
Diffusers
Diffusers capable of diffusing the specified quantity of gas into the
sludge shall be provided. The diffusers shall be constructed of a material
resistant to corrosion caused by digester sludge and shall be of a
nonclogging design which prevents the backflow of sludge into the gas
piping upon loss of gas pressure. [Draft tubes shall be constructed of at
least 6 mm 1/4 inch thick steel plate and shall have flared bottoms.]
2.5.3
Piping System
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NOTE: Certain gas recirculation piping systems
provide discharge wells which allow removal of the
discharge tubes within the wells for inspection or
change of depth of discharge without interrupting
digester operation and provide sealing in of gas
during removal and replacement of discharge tubes.
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2.5.3.1
Piping
Piping shall comply with paragraph DIGESTER GAS HANDLING SYSTEM.
2.5.3.2
Motor Operated Multiport Rotary Valve
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NOTE: Include this paragraph only if paragraph
COMPRESSED GAS SLUDGE MIXING SYSTEM is specified.
**************************************************************************
A single motor operated multiport rotary valve or multiple motor operated
valves shall be provided for control of gas supply to the individual
diffusers.
2.5.4
Supernatant Removal
**************************************************************************
NOTE: Include this paragraph if supernatant removal
is included in project.
**************************************************************************
[Overflow box with weir or supernatant piping] [Rotatable draw-off
supernatant pipe to pull supernatant at varying levels] shall be provided.
Digester sight glass or depth indicator shall be provided.
SECTION 11380
Page 20
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