pdvsa_2012_kgtower-97
TRANSCRIPT
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
KG-TOWER
Hydraulic Design and Rating
Software
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
What is it?
It allows users to design and rate KG proprietary packings and conventional valve and sieve trays.
It will provide the estimated capacity and pressure drop of KG high performance trays.
It will estimate a tower diameter and provide some design details (downcomer widths, for example).
It gives an indication of the turndown expected.
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
What else?
The KG-TOWER software has a list of both sales and technical contacts.
It includes pictures of our packings, valves, and trays.
It uses the same models that we use in our internal version to design our equipment.
Built in unit conversions.
Relative efficiency given for our packings.
It can import up to 5 loadings from SimSci-Esscors PRO/II and Aspen Technologys simulators.
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Design Information Hydraulic Loads
Vapor (flow to tray)
Mass flow rate [kg/h or lb/hr]
Density [kg/m3 or lb/ft3]
Viscosity [cP]
Liquid (flow from tray)
Mass flow rate [kg/h or lb/hr]
Density [kg/m3 or lb/ft3]
Viscosity [cP]
Surface tension [dyne/cm]
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Design Information System Properties
Foaming tendency
Fouling
Application
Pressure and temperature
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
EXAMPLE PROBLEM - ACID GAS
ABSORBER
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Current Operation
2000mm
20 trays on 600mm spacing
36,000 kg/h
18.2 mol% CO2 (451 kg-mol/h)
90 mol ppm CO2 (0.18 kg-mol/h)
260,000 kg/h
30 wt% MEA
279,800 kg/h
0.47 mol CO2/mol MEA
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Revamp
Goal is to increase throughput by 35% Existing trays would be flooded
What is required to check packing capacity? Vapor rate
Vapor density
Liquid rate
Liquid density
Liquid viscosity
Liquid surface tension
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Physical Properties
Absorber top V = 16,160 kg/h
v = 24.6 kg/m3
L = 260,000 kg/h
L = 991.1 kg/m3
L = 1.01 cP
L = 66.6 dyne/cm
Absorber bottom V = 36,000 kg/h
v = 23.8 kg/m3
L = 279,800 kg/h
L = 926.7 kg/m3
L = 0.83 cP
L = 61.5 dyne/cm
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
KG-TOWER Design Program
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Loading Input Screen
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Packing Design Screen Current Operation
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Packing Design Screen Proposed Operation
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Efficiency
How do we check the efficiency of our selected packing?
Highest accuracy achieved by using a rate based simulation program such as the RATEFRAC module in
PROII
Calculate transfer units and height of a transfer unit using experimental Kga data for this system
Estimate efficiency of proposed packing using efficiency data from existing trays
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
KG-TOWER
TRAY DESIGN
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Liquid Flow
Downcomer
Active Area or
Bubbling Area
Outlet Weir
Inlet Area
Vapor Flow
Downcomer
Clearance
Flow Path Length
Tray Spacing
Crossflow Tray Terminology
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Design Information Mechanical Information
Materials of construction
Tower manhole size
Existing tower attachments (revamp situation)
User Company Design Standards
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Optimizing Features
Number of flow passes
Downcomer adapters (revamp)
Sloped / stepped downcomers (kick-back)
Sweptback weirs
Radius lip downcomers
Sumps
Anti-jump baffles
Weir blocks
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Tray Design Rules of Thumb
Conventional Trays
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Input Values
Tray Spacing
24 [610 mm] is the most common
Typically ranges from 12 to 30 [300 to 760 mm]
Number of Flow Paths vs. Tower Diameter
1 Pass > 2.5 [760 mm] (ring supported)
2 Pass > 5 [1500 mm]
3 Pass > 8 [2400 mm]
4 Pass > 10 [3000 mm]
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Input Values
Downcomer Chord
4 [100 mm] or 1/12 tower diameter minimum
applies to both top and bottom
Kickback
3 [75 mm] typical for conventional trays or to provide top-to-bottom area ratios:
< 2:1 if vapor density < 1.0 lb/ft3 [16 kg/m3]
< 3:1 if vapor density < 1.0 - 3.0 lb/ft3 [16 - 48 kg/m3]
< 4:1 if vapor density > 3.0 lb/ft3 [48 kg/m3]
Center and Off-center Downcomer Width
6 [150 mm] minimum
Applies to both top and bottom unless boxed DC is used
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Input Values
Off-center Downcomer Position
Typically located to provide equal flow path lengths
Sweptback weirs
Can lose active area
Sump Width
Same as top downcomer width
Sump Depth
as need to provide VUD of 1.0 ft/sec [0.3 m/s]
4 to 6 [100 to 150 mm] is typical
25% of tray spacing maximum
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Input Values
Weir Height
Generally 1 to 3 [25 to 75 mm]
Default is 2 [50 mm]
Use less than 12% of tray spacing to avoid a loss of jet flood capacity
Downcomer Radius
1 [25 mm] is standard for conventional trays
Downcomer Clearance
typically weir height minus 0.5 [10 to 15 mm]
0.75 [20 mm] absolute minimum [1 or 25 mm preferred min]
1.5 [37 mm] minimum for refining applications
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Calculated Values
Jet Flood 85% maximum (all trays)
Downcomer Choke Flood (all trays)
85% maximum for low and moderate pressure
65-80% for high pressure hydrocarbon fractionation
Downcomer Backup: Conventional trays
40% or 33% if DL- DV is < 30 lb/ft3 (of TS + HW)
clear liquid basis
Weir Loading
6 gpm/ft [4.5 m3/m/h] minimum
consider more passes above 120 gpm/ft [90 m3/m/h]
Crest Over Weir
0.25 [6 mm] minimum
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Calculated Values
Downcomer Exit Velocity
Conventional: 1.6 ft/sec [0.49 m/s] maximum (clear)
Downcomer Head Loss
Conventional: 1.5 [38 mm] liquid maximum
not applicable if downcomer radius is used
Dry Tray Pressure Drop
15% of tray spacing is the design limit (all trays)
Flow Path Length
18 [460 mm] minimum without a special design
16 [400 mm] absolute minimum to have tray manways (special design required)
Consider using more passes above 120 [3.0 m]
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Rule of Thumb
While not applicable to all systems, there is an old industry rule of thumb that states:
10% entrainment will result in a 10% loss of tray efficiency
20% weepage will result in a 10% loss of efficiency
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CONFIDENTIAL 2012 Koch-Glitsch, LP. All rights reserved.
Low Liquid Rate Tray Features
When the weir loading is very low, the momentum of the vapor can throw the entire liquid rate into the
downcomer (or to the tray above) and blow the tray
dry.
In the process, the downcomer can become unsealed, thus aggravating the process.
When the weir loading is less than 6 gpm/ft [4.5 m3/m/h], the weir height should be a minimum of 2 [50 mm] tall.
Use weir blocks (picketing).