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NRP 2. OverVIEW. Why LabVIEW? Type Definitions How is the initial state chosen? Sensor Configuration/Calibration Waste Composition SBR suggested volumes and flows Airflow control. Why LabVIEW?. Designed for Data Acquisition, Analysis, and Control
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OverVIEW • Why LabVIEW? • Type Definitions • How is the initial state chosen? • Sensor Configuration/Calibration • Waste Composition • SBR suggested volumes and flows • Airflow control
Why LabVIEW? • Designed for Data Acquisition, Analysis, and Control • Development is 4-10 x faster than text based languages • Industry standard (jobs…)
Jobs? • POST DATE:.....9/5/2002 • YsearchDB • Required qualifications include software development experience in a Rapid Application Development environment, specifically with extensive LabVIEW experience • Education Requirement:.....BS (or higher) • SALARY:.....$70,000 - $90,000
Type Definitions • A type definition forces the data type to be the same everywhere it is used. • A strict type definition forces almost everything about the control to be identical everywhere it is used including: • Data type • Sizes • Position of elements • Colors etc.
Type Definitions • Elegant and powerful method to speed up program development • Suppose you need to modify a data structure • Suppose the data structure is used in many places in your program (because you use many subVIs) • Update everything automatically by saving the data structure as a type definition!
Type Definitions • Advantage: easy modification of data structure • Enumerated types • Adding states • Adding cases • Even constants have type definitions! • Control Set Points • I modified flow control this morning. I didn’t have to change this data structure everywhere it is used! • Add a turbidity set point • What happens to saved method?
Initial State • How does Operator Selected State work? • How does the software choose which state to go to when you switch to automatic? Initial plant state next plant state • Off Fill with water • Manual Fill with water • All other states automatic rule
Sensor order Reactor volume Air pressure (flow) Dissolved Oxygen Temperature Diffuser Air Pressure Calibration steps File (reservoir volume), set physical units File (Pa) Dissolved Oxygen (saturated H2O) File (thermistor) File (Pa) Sensor Configuration/Calibration
Synthetic Feed Composition Stock 1 (100x) refrigerator Organic carbon Nitrogen Phosphate and pH Stock 2 1000x Metals Stock 3 1000x
Feed Characteristics • Completely soluble at feed concentration • 325 mg/L COD (Chemical Oxygen Demand) • 40.9 mg/L nitrogen • Stocks 2 and 3 will be added to tap water in 100 L tank that will be pumped to each plant • Stock 1 will be diluted (by you) to 20x and stored in your refrigerator
4 h SBR Activated Sludge Operation 1.5 L • What is the recycle volume? • What is the volume of waste (tap+concentrate) • What is the volume of tap water? • What is the volume of concentrated waste? 3.5 L 3.325 L 175 mL X = 3 g/L Xr=10 g/L 5 L 1 hr 6 hr
Dissolved Oxygen Control • Suppose the fill cycle just ended • How could you set the initial aeration rate? • How could you correct the aeration rate? • What are some potential control strategies? • Using a valve and a DO probe • Using a valve, pressure sensor, and an accumulator • Using a valve, pressure sensor, accumulator, and a DO probe
New Data Structure for Airflow Control Settings that apply to all states
New Code for Airflow Control • See Plant Control • Control based on target DO is not yet implemented • Plant can run without this sophisticated control • This is new territory for all of us! • I think it is a fun programming challenge
Next Week’s Plans • Meet in lab MWF! • Add the DO probe • Upgrade to new software • Run Plant in automatic mode • Run your plant with fake synthetic waste! • Manually add sodium sulfite to mimic oxygen demand and see how your plant responds to low oxygen levels • Eliminate all leaks!
Correction based on gradual change in oxygen levels over time Air Flow Rate • Aerate tank at high aeration rate, then stop and measure = Solve for Qair and substitute kox OTE will be less in wastewater than in tap water