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Example

Example 1 : Repairing Failed Heat Exchangers Owing To Vibration

● Serveral Kettle Reboilers on a new LNG plant suffered vibration-induced failures
 owing to insufficient tube support.
 - Shortly after start-up, one reboiler suffered multiple tube failures.
 - Failed tubes were plugged and bundle stabilized with DTS.
 - Successful operation continues for more than one year after re-start.
● Plant realized significant savings of potential lost opportunity cost from unplanned
 downtime plus cost of purchasing replacement exchangers.

테스트 결과
  Original Exchanger Exchanger with DTS
Duty(MBtu/hr)(MW) 244(71.5) 244(71.5)
Δp(psi)/(kPa) 0.29(2.0) 0.29(2.0)
Vibration Problem Yes No

Fluidelastic Instability Ratio = 4.1
Recommended Upper Limit = 0.8

Vibration analysis indicatied very high probability of Fluidelastic Instability Ratios (FIR) at top rows of bundle.
FIR > 4 as calculated by vibration analysis before DTS reduced to 0.2 after DTS installation.

Example 1 : Locations of DTS strips

● Axial locations of DTS strips.

Example 1 : DTS Strips Positioned Every Other Row

● Implemented vibration mitigation at location "A".

● Implemented vibration mitigation at location "B".

Example 1 : DTS Strips in U-Bends

● Implemented vibration mitigation at location "A".

DTS is the only existing technology
that allows reliable vibration mitigation
in U-Bends and in Vertical Heat Exchangers

Example 2 : New Exchanger With Optimum Heat Transfer And Pressure Drop

● Sometimes, the optimum heat transfer design point, although within the allowable Δp limit, will not be acceptable because of vibration
  problems.
 - Conventional solution is to reduce the shellside velocity which results in an off-optimum design (lower heat transfer performance and
 more costly exchanger).
● Application of DTS removes the vibration potential and allows the optimum design to be used.
● In the example shown, a refinery purchased two 36-inch(914-mm) overhead condenser shells, instead of two 40-inch (1020-mm) shells,
 resulting in a significant cost reduction.

테스트 결과
Exchanger : TEMA AES Condensing Service Conventional Design(with no vibration) Optimum Design with DTS
  44"x192"(1.118mX4.88m)
Plain Tubes
NTIW/Seg
2p/1s
36"x192"(0.914mX4.88m)
Plain Tubes
Double seg
2p/1s
Duty (MBtu/hr)/(MW) 17.7(5.19) 17.7(5.19)
Shell side Δp (psi)/(kPa) 1.8(12.4) 1.4(10)

For new Projects, DTS allows the design at the optimum performance for heat duty and pressure drop, saving significant capital and operation costs.

TEMA AES, 2p/1s, 36"x192"(914x4.88m), Double Segment, Plain Tubes

● Optimized exchanger with vibration problems selected after providing vibration mitigation with DTS strips.

Example 3 : Increase Capacity by 30% Without Vibration Failures

● Treat Gas Heater on Gas Cracker Unit with effluent on shellside
● In a capacity creep project, vibration problem predicted at the new, higher flow rate condition
 - The most expensive solution requires larger replacement exchangers to avoid the vibration condition
 - Retrofit installation of DTS or STS allows vibration-free operation of existing equipment

테스트 결과
Feed / Effluent Heat
Exchanger
TEMA BEU
33" x 126"(838 mm x 3.2 m), 1"(25.4 mm) tubes
1180 ft2(109.6m2)
Segmented baffles
Design Conditions 30% Capacity Creep without DTS 30% Capacity Creep with DTS
Duty (MBtu/hr)/(MW) 49.4(14.5) 64.2(18.8) 64.2(18.8)
Δp (psi)/(kPa) 8.4(58) 10.0(68.9) 10.2(70.3)
Vibration Problem No Yes No

DTS is specially suited for capacity-creep projects :
Spares significant costs of new, larger heat exchangeres, piping and foundations costs.
Technology specially suited to debottle-necking condensers,
reboilers, and feed/effluent heat exchangers.

Example 4 : Debottleneck Gas Loop via ESBs

● Debottleneck a compressor loop in a Chemical Plant where the circuit heat exchanger pressure drop was limiting.
 - Existing heat exchanger showed flow-induced vibration at existing flow rates that led to tube failures.
 - Replaced conventional bundle with an ESB that reduced shellside P from 16 psi (110 kPa) to 3.5 psi (24 kPa).
 - Maintained duty by switching from plain tubes finned tubes.

테스트 결과
Exchanger :
TEMA AEU Feed Preheat w/ Steam
Original bundle
(at debottleneck conditions)
ESB Bundle
25"x126"
(6.35mm X 3.2 m) Shell
1200 ft2 (111 m2)
0.75(19 mm) plain tubes
Segmental baffles
2140 ft2 (199 m2)
0.75" (19 mm) finned tubes
No baffles (axial flow)
Duty (MBtu/hr)(MW) 97.6 (28.6) 103 (30.1)
Δp (psi)/(kPa) 16(110) 3.5 (24)
Vibration Problem Yes No

● Achieved significant savings in operating expense (reduced Δp) and capital avoidance (used existing shell/foundation/piping) that more than
 offset the cost of finned tubes.
● Increased reliability of the exchanger loop and time on stream for the process unit.

ESBs represent a Cost-Competitve solution to minimize pressure drop,
expand capacity, and save existing shells.
Perfectly suited for compressor loops, low pressure, and vacuum services.

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