3d trasar technologies for reliable waste water recycle...
TRANSCRIPT
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Manish Singh, Atanu Basu
15 June 2012
3D TRASAR Technologies for Reliable Waste Water Recycle and Reuse
Outline
Introduction
3D TRASAR Technology for Sugar Background
Technology overview
Data
Summary
3D TRASAR Technology for Membrane Background
Technology overview
Case Study
Summary
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Introduction
There is increasing stress on water resource, and increasingly stringent regulatory norms on water consumption and discharge
Recovery of the effluent streams is a rather daunting task as the quality can have dynamic variations
3D TRASAR Technologies have been developed to automatically handle such dynamic variations and ensure efficient system operation.
These technologies have demonstrated significant water savings, energy savings and asset protection.
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3D TRASAR Technology for Sugar
Sugar Industry Trends and Needs
Trends
• An increasing trend in sugar industry is the production of cogeneration power in addition to producing sugar
• Such cogen plants have boilers and condenser cooling water systems
• Increase in the quantity and quality requirements of water
Needs
• To reduce the water and energy footprint
• Protection of assets (boiler, cooling tower)
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Sugar Cane Milling Process
More than 70% of sugarcane by weight is water !
Lot of water is generated in the form of process condensate when sugar juice is concentrated in evaporator from 12 – 16% solids to 60% solids
This condensate has potential for reuse as boiler water or cooling water make up
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• Very low in dissolved solids• Low in Organics• Has Ammonia
Characteristics
• There are huge dynamic variations in the quality of condensate
Variability
• Difficult to treat in a wastewater plant (high hydraulic load with low organic load)
• When sent to the drain high discharge costs• Frequent variations in quality makes it difficult for
reuse in a boiler / cooling water application
Challenges
Sugar Process Condensate
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Reuse challenges
Formation of organic acids
Decrease in boiler water
pH
Increased caustic dose;
corrosion
Shutdown
Increased organics load
Increased microbial fouling
Increased biocide dose;
corrosion
Tower collapse
Contaminated process condensate, if reaches boiler or cooling tower, can cause serious problems
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Current technologies in market
• Not online• Labor intensive
-naphthol test
• Low sensitivity• Low selectivity
Conductivity
• Very expensive• Time lag in response
Total Organic Carbon (TOC)
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3D TRASAR Technology for Sugar
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Fluorometry based automation that monitors “sugar shots” online, controls the condensate discharge, helps sugar mills maximize the condensate recovery while maintaining the reliable and efficient operation of the boiler and cooling systems.
Process Condensate Return Line To Boiler / Cooling Tower
Blo
wd
ow
nDetect the sugar contamination level with on-line sugar fluorometerDetermine by comparing the sugar reading with the setpointDeliver a signal to trigger alarm and turn on the blowdown valve
during sugar shot
Lower than setpoint
Higher than
setpoint
possibly contaminated with sucrose, organics and inorganics
Sampling Line
3D TRASAR Sugar Fluorometer
Specific to fluorophores present inherently in sugar cane juice
Developed after analyzing data from fluorescence spectroscopy done on sugar juice and condensate samples from various cane sugar mills
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3D TRASAR Technology for Sugar
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Data from Field Application
Sensitivity3D TRASAR® for Sugar is much more sensitive than conductivity
Early detection3D TRASAR® for Sugar detected the entrainment event about 30 min prior to its detection by conventional method being used at site
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Summary & Key Benefits 3D TRASAR Technology for Sugar is a fluorescence-based monitoring technology that is
able to detect the condensate quality variations with high sensitivity and selectivity, and provides early detection
Reliable reuse of vapor condensate as boiler make-up, cooling tower make-up, or other sections of plant (assurance that only good quality condensate goes to boiler / cooling tower)
Water savings (reduced wastewater discharge; reduced raw water consumption) and energy savings; improved environmental sustainability
Meet discharge norms set by environmental regulatory authorities (savings on punitive charges)
Protection of assets (boiler, cooling tower) from potential corrosion, scaling, microbiological fouling
Efficient power co-generation (lesser fresh water, lesser chemicals, cleaner cooling water for cogen plant)
24×7 Remote monitoring and troubleshooting via Nalco 360TM
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3D TRASAR Technology for Membrane
Obstacles to optimal RO performance
Lack of analysis and interpretation of operating data, leading to inappropriate, insufficient or no corrective action being taken
Limited or missing monitoring of operational variables
Insufficient resources to make the proper changes
Operation and/or water source has changed since the original installation
Mechanical limitations of equipment
Bad design
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RO Best Practices
Normalize data
Take action based on normalized trends Detect fouling
Detect scaling
Schedule cleanings
Absolute Chlorine removal to protect the membranes
Optimize Recovery (yield) without compromise
Monitor feed water changes
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Automation
Chemicals & Consumables
Service
Equipment
3D TRASAR Technology for Membrane
3D TRASAR Technology for Membrane Objective
Drive performance towards Best Practices1. Immediate feedback on problems
2. Cleaning at the right time
3. Reduce risk for chlorine exposure
4. Safely operate at optimal (maximum) recovery
5. Improve chemical control
Leading to improved efficiency and reduced costs 1. Water savings
2. Waste water savings
3. Chemical savings
4. Consumables savings
5. Energy savings
• Reduced downtime• Reduced labor cost• Reduced off spec product• Increased capacity• “Green” operation
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1. Immediate Feedback of problems
The main reasons for short membrane life are: Scaling/Fouling
Deferred Cleaning
Halogen attack (chlorine damage)
3DT Technology for Membranes can detect all of these problems and notify with alarm.
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1. Immediate Feedback of Problems
3DTTfM Monitoring
AlarmNotifications!
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2. Cleaning at the right time
Membrane elements MUST be cleaned when one of the following parameters is noticed 15% loss in normalized permeate flow
15% increase in normalized differential pressure
15% increase in salt passage
Failure to follow these rules will result in reduced membrane life
Remember, operation of a membrane system at higher pressure will use more energy!
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2. Cleaning at the right time
Cleaning should have been done here
Ineffective cleanings
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3. Reduce risk for chlorine exposure
Protect against permanent membrane damage from an unforeseen (sudden) increase of chlorine in the feed water
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4. Safely operate at Optimal recovery
Key feature of the technology
Most RO systems are designed for only 75% recovery Because it is conservative
Because these systems are likely not maintained properly
They would rather waste the water than have to replace the membranes
With this technology, we can operate more efficiently and closer to the limits
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Low recoverywasted feed water and excessive water to waste
High recoveryadditional cleaning or destroyed membranes due to scale
5. Improved Chemical control
Dose rate could safely be decreased from 4 ppm to right around 1 ppm
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Good control at 3.5 ppm antiscalant, even with a system that is ON only intermittently.
Implementation
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Concentrate
Permeate
Feed Water
F FuS uSP
P
P
P
TFL
FL
FL
PP
Multiple data streams come into a central unit
3D TRASAR for Membrane Equipment
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A Case Study
System
RO Train (2 stages)
Permeate demand:100 gpm (22.7 m3/h)
Feedwater flow: 160 gpm(36.3 m3/h)
60% recovery
Goals
Obtain stable water production
Decrease water consumption
Decrease total cost of operation
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Halogen controlBefore
Prior to using this technology, halogen control was erratic
A predetermined amount of SBS (sodium bisulfite) is added to the RO feedwater to control free chlorine.
Only spot checks were possible due to limited personnel resources
Occasional ORP surges were likely, but there was no way to know
ORP(Oxidation Reduction Potential) is used to detect the existence of residual chlorine in feedwater to the RO. Even
very low levels of chlorine (< 0.1 mg/L) can harm RO membranes.
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0
100
200
300
400
500
600
700
3/21 3/22 3/23 3/24 3/25 3/26 3/27 3/28 3/29 3/30
Fee
d O
RP
(m
V)
Sulfite pump replaced
0 1 2 3 4 5 6 7 8 9
Time (day)
Occasional ORP surges
Halogen controlAfter
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Better “eyes” on the system, 24/7
Close 24/7 monitoring by Nalco 360TM
Detected occasional ORP surges
Replaced sulfite pump
Protected $10,600 worth of customer assets (membranes)
Water Recovery control
Low recovery levels at ~60% to obtain stable water production.
Low recovery was due to high conductivity in feedwater and high scaling potential at the high pH employed by the system (to prevent excess CO2 leaking through the permeate).
There was a desire to increase recovery, but the existing monitoring system was insufficient to track and detect potential system failures.
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Before After
water recovery rates were increased methodically to 73%
Result – Economic benefit with mitigated risk
Close 24/7 monitoring by Nalco 360TM allowed more aggressive water recovery without hampering system operation
Water recovery was raised to 73%
Cost savings were estimated at $67,000/year
Additional observations: ORP Alerting – SBS chemical pump failure that would have been almost
undetectable without the trended data and alarms of the 3D TRASAR Technology for Membrane systems.
RO Operation – Due to unbalanced changes between the flows and pressures in the system, we were able to identify that the RO system’s concentrate valve had started to fail. We were able to prevent any RO catastrophic damage, stop unnecessary water loss, and most importantly, avoid unplanned RO shut down to fix the valve.
Bad Sensors – Alert notifications for instrumentation issues.
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Summary and tangible benefits Water and waste water savings
- If actual recovery is lesser than design
Increased time between membrane replacement- If membrane life is extended from 2 years to 4 years
Decreased cleaning frequency- If membranes are cleaned once a quarter rather than once a month
Minimize cost / consequence of poor water quality on final product- Ability to be proactive; address water quality issues before they impact
process performance or product quality
Operate on different / lower quality feed water- Lower cost of water when switching from well to surface water- Ability to maintain production when placed under local water use restrictions
Minimize downtime / full availability- Lost production associated with unplanned downtime due to membrane
fouling or membrane replacement
Maximize capital utilization- Get as much water, of “just right” quality, from your existing RO system; avoid
the cost of adding a new RO system
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