optimizing tower designs - h2so4today...3” mm ceramic saddles vs. flexeramic 88 parameter b ase...
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CONFIDENTIAL – © 2018 All Rights Reserved
Optimizing Tower Designs
Koch Knight, LLC
Matthew J. Thayer
November 8 2018
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Table of contents
Brief history of the plant sizing- Break down was based on the following sizes: 500,1000, 2000, 3000, 4000, 5000 MTPD
Discovery and analysis of the issues surrounding the larger plant
Options to correct the issues associated with these larger plant Reduction of the stress and the loads on the bricks Reduction in the diameter of the towers
Repair of the existing tower options
Conclusion
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Looking at the raw data
Reviewed more than 100 towers Ages of the plant varied from less than one year to 20 plus years
Data gathered on both brick lined and metallic towers, some of the data gathered: Age if the plant Diameter Tower type – Brick and Metallic Brick Types- Red shale vs Acid proof Membrane type Environmental averages Limited information on Seismic and wind loading
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Main Issue Discovered –Next Steps As the tower diameter increased, more issues were identified
Failure/repair requirements of the external shell occurring faster as the diameter of the shell increased
Perform an FEA on the shell to see if any specific issues could be uncovered – Simple base case to determine if there is an issue.
Categorized raw data on the towers and focused in on three items: • Membrane type • Size of the tower • Repairs of the existing tower
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FEA Evaluation
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General Modeling of the shell
Figure 1: Model of lining system for PYROFLEX® acid resistant sheet lining case.
DURO™ Acid Brick II-P 2 x 65 MM
Process temperature (130°C)
Inside diameter
Ambient Conditions
(-‐20°C to 30°C)
Stee
l she
ll (1
2.7m
m)
Pyro
flex
(9m
m)
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2 Meter Radial No Membrane
Figure 2: Radial displacement of the 2-meter diameter tower without membrane.
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9 Meter Radial No Membrane
°C
Figure 3: Radial displacement of the 9m diameter tower without a membrane.
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2 Meter Radial With Membrane
Figure 4: Radial displacement of the 2-meter diameter tower with PYROFLEX membrane.
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9 Meter Radial With Membrane
Figure 5: Radial displacement of the 9-meter diameter tower with PYROFLEX membrane.
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Gap Between Refractory and PYROFLEX/Steel Shell
ID = 2000 mm ID = 9000 mm
With PYROFLEX
No PYROFLEX
With PYROFLEX
No PYROFLEX
Cold Ambient No Gap No Gap No Gap No Gap
Warm Ambient No Gap No Gap No Gap 0.3 mm Gap
Displacement Summary
Figure 6: Comparison Gap Data Recap
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Dome Displacement
Figure 6: Radial displacement at packing support when the tower is in operation at 130°C with 30°C ambient temperature
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PYROFLEX™ PTFE DuPly Membrane/Brick
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Change the Packing
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Plant Sizing
Size of the plant 75 mm Nom Saddles (Dia.(M)/Vol)
FLEXERAMIC® 88 Packing (Dia./Vol)
500 MTPD 3400 / 30 2800 / 20
1,000 MTPD 4700 / 50 4000 / 40
2,000 MTPD 6700 / 110 5700 / 80
3,000 MTPD 8200 / 160 7000 / 110
4,000 MTPD 9500 / 210 8100 / 150
5,000 MTPD 10600 / 260 9000 / 190
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Comparison to random packings 3” mm Ceramic Saddles vs. Flexeramic 88
Parameter Base Case
ΔP Reduction
Increased Efficiency and ΔP
ReductionIncreased Capacity
Increased Capcacity
and Efficiency
New Smaller Tower
Packing 75 mm FX 88 FX 88 FX 88 FX 88 FX 88Diameter 20'0" 20'0" 20'0" 20'0" 20'0" 17'3"Packed Height 12' 9' 12' 9' 12' 9'Gas Flow (lb/hour) 500,000 500,000 500,000 650,000 650,000 500,000Acid Rate (gpm) 4,700 4,700 4,700 6,100 6,100 4,700Pressure Drop (" w.c.) 8 3 4 7 8 8% Flood at Bottom (Max.) 73% 54% 54% 77% 77% 80%SO3 Removal 99.98% 99.98% 100.00% 99.98% 100.00% 99.98%
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Benefits in Sulfuric Acid Service• Reduced tower size (Reduce capital costs of new units and
provide flexibility in replacement options)
• Reduced stress in the tower
• Increased capacity (Debottleneck existing units)
• Increased efficiency (Remedy for undersized units)
• Robust design
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REPAIR METHODS
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Failure Inside An Acid Tower
1. Acids inherently find ways to permeate through brick and mortar
2. Once penetrated to the membrane, the acid slowly converts the surface of the protective barrier to carbon.
3. Carbon is stable, as long as it is not washed away due to continuous flow of acid.
4. Once carbon is washed off, carbon steel meets acid creating iron sulfide. The same wash process occurs and reduces thickness of wall finally perforating it.
Brick
Mortar
Membrane
Carbon Steel
Acid
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Repair Methods Available
1. Some try to weld another steel plate on top of the acid leak. Welding will destroy the existing membrane creating even more problems.
2. Another way is trying to fill the voids between steel shell and brick lining with some kind of acid resistant materials: • Potassium Silicate would be the
oldest way of repairing • Pecora Mastic was an improvement • With newer low viscosity acid
resistant resins on the market providing different ways of repair.
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Potassium Silicate
How do we get the potassium silicate to stay in place? It is brittle and reacts immediately with acid to form a solid. • Weld a box to the steel shell and try to fill
the voids with mortar • A thick and highly viscous material that will
not flow easily into the void and will only deliver a temporary solution.
• Lots of post maintenance required.
Brick
Mortar
Membrane
Potassium Silicate
Acid
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PECORA® INJECTION
The next best solution is to inject Pecora Mastic into the voids. • The material is thick and highly viscous • Material needs to be heated and mixed with
a solvent to be injected properly into voids • An even distribution throughout the void
cavity is obtainable • Solvents evaporate creating pathways for
acid within the material.
Brick
Mortar
Membrane
PECORA® Mastic
Nipple / Injection
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PECORA® INJECTION
•With pathways created flow will continue getting once again to the steel shell.
•New Steel Perforation will appear
•Let’s start from the beginning once again!
Brick
Mortar
Membrane
Acid
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NOVOLAC INJECTION
As said before is a specifically developed resin resistant to high corrosive acids and creates an array of solutions to injecting void spaces between steel and brick linings. • Low Viscosity • With a low pressure injection machine
voids can be fully filled • Resin Reacts with acid, but flow pushes the
reacted resin out • Penetrates small cracks
Brick
Acid
Mortar
Membrane
Novolac
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NOVOLAC INJECTION
• As it is a 100% solids material (no VOC) it hardens and cures to form an Acid Resistant Membrane
• Minimal to Nil Voids Cutting off flow for “ New Acid Highways”
• Can be re-injected at new ports any time to catch places which were not treated before.
Brick
Acid
Mortar
Membrane
Novolac
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Lay out and drilling of the tower
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Special Thanks
Steve Purchelli – Saconix
John Horn – MECS/Dupont
Rick Davis – Rick Davis Consulting
George Wang – GWang Consulting
Dr. Hannes Storch – Outotec
Jan DuPlessis Theron - Lucideon
English
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Thank you for your time
Any questions?
English