Quartz Sleeve Fouling Prevention While Maintaining Maximum Electrical Efficiency. IUVA Conference by Ludwig Dinkloh, Global Product Manager

Transcription

1 Quartz Sleeve Fouling Prevention While Maintaining Maximum Electrical Efficiency IUVA Conference by Ludwig Dinkloh, Global Product Manager

2 Introduction / Motivation Note: Wiping System not operational!

3 Outline 1. Definition of Fouling 2. Types of Fouling 3. Monitoring of Fouling 4. Overview of Fouling Factors used by the Industry 5. Impact of Fouling 6. Recommendations/Conclusions

4 Definitions Slight Adaptations from NWRI 2012 Guideline: Fouling Factor: The reduction in available UV output due to changes in transmittance of the (lamp) enclosure (e.g. quartz sleeve) separating the UV lamp from the liquid. The reduction in available UV output is determined by comparison to a new enclosure. (Lamp) Enclosure Fouling: The formation of material on the enclosure, which causes a reduction in the UV intensity emitted through the enclosure.

5 Types of Fouling (*) Mainly Organic Fouling Mainly Inorganic Scaling high organic load (mainly prim & sec) When lamps are off => no disinfection No wiping, wiping off All types of high inorganic loads When lamps are on => temperature difference With or without wiping * from Brooks T. et al (Carollo) Lessons Learned from UV System Performance Audits for Reuse Applications, IUVA 2016

6 Monitoring of Fouling Direct monitoring of fouling? Indirect monitoring of fouling via UV intensity sensors (sensor value influenced by lamp output, lamp age, fouling and UVT of effluent) Measured UV intensity then used in UV systems control philiosphy (RED equation), e.g.:

7 Consequence for Monitoring Irrespective of UV system configuration at least one (1) UV intensity sensor is needed per switchable unit. Advantage of many switchable units : flexibility => lower OPEX Disadvantage of many switchable units : more monitoring BUT: no monitoring no credit (or safety/reliability)

8 Real Measurement of Quartz Sleeve Fouling

9 Design Basis 1/2

10 Design Basis 2/2

11 Examples of Fouling Factors* Manufacturer Calgon Carbon Enaqua Suez Ozonia Trojan Xylem Wedeco Model C³500D C10i AquaRay 3X UVSigna Duron Description Lamp type Horizontal, lamps inside quartz sleeves LPHO Amalgam Horizontal, lamps outside of AFP tubes LPHO non- Amalgam Vertical, lamps inside quartz sleeves LPHO Amalgam Inclined, lamps inside quartz sleeves LPHO Amalgam Inclined, lamps inside quartz sleeves LPHO Amalgam Lamp power 500 W 138 W 406 W 1,000 W 600 W Cleaning/ wiping system 3 rd Party Fouling factor Mechanical None Mechanical Mechanical/ chemical Mechanical Important: differences in kwh/mgd per UV system *Public Domain Information from Bid Openings

12 Carollo Experience (IUVA 2016)

13 What happens without Wiping? UV Pilot Study Documentation for St. Joseph, MO by Black & Veatch (2009)

14 Application of the Fouling Factor in Designs As per Dose Validation Equation (equation is system-specific) where: RED = UVA = The RED calculated with dose monitoring equation, also referred to as the calculated dose in the UVDGM UV absorbance at 254 nm S = Measured UV sensor value S 0 = UV intensity at 100% lamp power Q = Flow rate D L = UV sensitivity of challenge/target organism A,B,O= Model coefficients obtained by fitting the equation

15 Fouling Factor Impact on Design Very system-specific; f(flexibility in design and dose equation)

16 Fouling Factor Impact on Operation System-specific; f(dose equation coefficients, system and lamp flexibility)

17 Cleaning Performance under challenging Conditions Secondary effluent with dissolved iron of ~ 2 mg/l! Visual inspection of wiping tests after 4 months of tests Channel 2 Bank B Module 1 (conventional wiper) Channel 2 Bank B Module 2 (wiper design for tough effluents)

18 UVT Measurements of Quartz Sleeves

19 Recommendations / Conclusions 1. Subject to the effluent quality, fouling does occur in varying degree irrespective of UV system 2. Minimization (or occurrence) of scaling is UV system specific 3. A project-specific and system-specific (!) fouling factor is used to allow for a certain loss of UV transmittance of the enclosure => careful selection incl. O&M aspects and kwh/mgd comparison 4. Impact on design: the higher the fouling factor, the more lamps are needed (CAPEX) => to be weighed against overall in-built redundancy/safety 5. Impact on operation: the more fouling, the higher the power draw (OPEX) => to be monitored (with S/S 0 ) plus indication via power 6. Consequence for monitoring: min. one (1) UV intensity sensor per switchable unit

20 Thank you!