8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
1/23
Operation of Louisiana Low Turbulence (LLT)Clarifiers
Vadim Kochergin
Audubon Sugar Institute
Presented at the
Jamaica Association of Sugar Technologists
Annual Conference,
November 4, 2011, Ocho Rios, Jamaica
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
2/23
Rapidorr 444
CFD Modeling
Chetty and Davis, 2001
Large Scale Turbulent Eddies in an Industrial
Clarifier
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
3/23
Design Concepts
Large scale turbulent eddies created by juiceintroduction need to be reduced.
Velocity in the feed channels should remain
relatively high to eliminate plugging/scaling. Uniform distribution of feed inlets and outlets
in order to have uniform vertical juice
velocities to make full use of the cross-
sectional area of the clarifier.
Minimize any non-vertical flows within a
clarifier.
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
4/23
Proof of Concept- 25 m3/hr flow
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
5/23
Proof of Concept
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
6/23
Basic TRD Layout
Side View
Top View
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
7/23
Industrial Trials 2009 Grinding Season
Turbidity, suspended solids, and flocculant usage
were monitored for the three clarifiers at Westfield
Sugar Mill.
a 20 ft. diameter Graver
a 20 ft. diameter Graver retrofitted with the new design
a 30 foot diameter Dorr, with two mud boots
* High mud levels -200-300 Lbs per ton of cane was notuncommon
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
8/23
Turbidity- Comparison 2009 season
20
30
40
50
60
70
80
90
100
110
10/7/2009 10/27/2009 11/16/2009 12/6/2009 12/26/2009 1/15/2010
Turbidity(N
TU)
Date
GraverModified
Dorr
Poly. (Graver)
Poly. (Modified)
Poly. (Dorr)
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
9/23
Results
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
10/23
Observations
Season 2009/2010
Clarifier showed better performance compared toGraver and Dorr at the same mill
Bagacillo in clear juice was observed due to air
entrainment in the pre-distributor
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
11/23
Turbulence Reduction Device
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
12/23
Updated clarifer design 2010
Sterling, LA
Residence time 30-40 minutes
Redesigned feed distributor
Material of construction- Cromgard Steel
(American Utility Metals)
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
13/23
Clarifier Retrofit
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
14/23
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
15/23
Water test Sterling, Summer 2010
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
16/23
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
17/23
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
18/23
Sterling Clarifier Turbidity Comparison
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
19/23
Controlled Tests
Two separate tests were conducted in which the
flowrate to the LLT was increased from 750 to
1000-1100 GPM to test the limits of the clarifierthroughput
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
20/23
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
21/23
Controlled Tests Summary
No air entrainment at 1100 GPM ( 50 % increasecompared to the standard operating flowrate of 750GPM)
No mud flocs / bagacillo in clear juice
No significant change in turbidity
Using the same amount of flocculant as at 750 GPM
Mud consistency remained constant during second test. Flocculant was increased with increased flowrate.
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
22/23
Conclusions
Air entrainment problem has been resolved withimproved pre-distribution
No air entrainment was observed even at 50 % increase
compared to nominal throughput
LLT design showed on average 20 % better performancethan SRT design at lower residence time (35 min vs 45
min)
Slightly more flocculant was used as compared to the
SRT. Flocculant use optimization has not beenperformed
Capital cost of LLT design was estimated at about 30-40
% of SRT design
8/12/2019 Operation of Louisiana Low Turbulence (LLT) Clarifiers
23/23
Acknowledgements
American Sugar Cane League for providing partial
funding for the project
Personnel of Sterling, Lula, Westfield and EnterpriseSugar Mills