Bioprocess Aeration Control System

28 Pages·2015·1.73 MB·English

Bioprocess Aeration Control System

BioChem Technology, Inc.
King of Prussia, PA

March 18, 2015
BioChem Technology Milestones
1978 Incorporation of BioChem Technology, Inc. as a
pharmaceutical process consulting firm
1990 Transition to consulting for wastewater treatment processes
1990 - Focus on R&D and municipal WW process consulting
2000
1997 Begin development of current product line
2000 Installation of first self-calibrating ammonium ISE analyzer
2004 First installation of BIOS process controller
2008 First installation of BACS in US
2011 ISO 9001:2008 and 14001:2004 Certification
Process Control Objectives in BNR Plants
• Stabilize the biology
• Improve effluent quality
• Improve energy efficiency
• Maximize nitrogen removal.
BioChem Products

• BIOS - Optimal Process Control (Ammonia Control)
• BACS - Integrated Aeration Control System
• Engineering Services – Process Simulation & Optimization
Control Problem:
Diurnal Plant Loading
Influent ammonia concentration as a measure of loading
Aeration Control
Current technology
o Constant pressure blower
control
o Feedback PI control of
individual aeration zones
o No communication between
control loops

BioChem Solution (BACS)
o Flow based blower control
o Process-based control of
aeration zones
o Integration of control systems
Conventional DO Control Systems
• typically independent cascaded PI loops for each zone
SP
DO PI
SP
Airflow PI Controller
PV PV
Controller
SP
DO
FIT M
Aeration
FE
Air Zone
Header
Flow
Control
Valve
Conventional DO Control Systems
multiple tuning loops and all sorts of interactions

SP
SP
SP DO PI
SP
DO PI
SP
Airflow PI ContrDolOle rP I
PV Airflow PI SP Controller
PV ConAtrirofllloewr PI Controller PV
PV Controller
SP
Controller
SP
SP
DO
FIT M
FIT M Aeration
FIT M
FE
Zones
Air
FE
Header FE
p=const
PIT
Flow
Control
Pressure PI
Valve
Controller
Blowers
Blower
MCP
PI Pressure Control - Out of Tune
4
3.5

)
L 3
/
g
m
(
2.5
n
o
i DO Set-point 2.5 mg/l (constant)
t
a
2
r
t
n
e
c
n 1.5
o
C Controller out of tune

O 1
D
0.5
0
0:00 6:00 12:00 18:00 0:00
Time
PI Pressure Control
Valve hunting between zones
3.0
2.5
2.0
4.0 hours
Instability
o Two aeration zones on constant pressure header
o Valve action is a response to changes in the opposing zone, not changes in the
process
o Basin and blower control loops “fight” each other
o Difficulties operating at extremes of blower capacity
o Interactions with multiple basins or control zones