BP I,C&E CONFERENCE

ADVANCES IN COMPRESSOR SURGE DETECTION

John Platt & Jim McCraw

E&PTG - Houston

Northstar – HP CompressorStg 3-4 Diaph

“Bulb” “Box”

Northstar Update - Process - CODA

HP-B, 4th Stage - ESD (w/o 1-second delay), Aug 29, 2002

5225 NPT

4950 NPT

1.53

5.335.93

2.07

5.1934.894

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

0 10 20 30 40 50 60 70 80 90

Flow Function - Sqrt (h/Ps)

0

1

2

3

4

5

6

7

8

9

10

11

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15

Pd/Ps CODA Surge Line CODA Overload Line ESD Decel -Seconds ESD Decel -Comp rpm

BackgroundBackground

Goal: To explore the effectiveness of using thrust bearing load changes to measure the onset of surge in centrifugal compressors.

How? By employing static and dynamic thrust load sensing equipment in the thrust bearing and the thrust bearing housing.

Engineered SolutionEngineered Solution

• Dynamic sensors between pads/links in RMT thrust bearings (4 load cells per Bearing- 8 Total)

• Static sensors behind Thrust Bearing - recessed in thrust housing (2 top half - 2 bottom half, 4 load cells per side - 8 total)

• Four Load Cells Per Thrust Bearing

• Wires Exit Bearings radially and come out Housing at Horizontal Split

RMT Thrust Bearings With Dynamic Load Cells

Dynamic Load Cells Wire ExitDynamic Load Cells Wire Exit

Load Cell Wire Bundle

Thrust Bearings

Thrust Housing

Static Load Cell CavitiesStatic Load Cell Cavities

Thrust Housing (Bottom Half)

Static load cells mounted in recessed hole in Thrust Housing

Thrust Housing

(Bottom Half- Rotated)

Static Load Cells Shown in Orange

Static Load Cells In Thrust HousingStatic Load Cells In Thrust Housing

Static Load Cells Wire Exit

Conducted FEA on housing

Results (based on 500 psi thrust load): Maximum stress = 5330 psi Maximum deflection = 0.47 mils

Visual results next 3 slides

Static SensorsStatic Sensors

FEA ResultsFEA Results - StressStress

FEA ResultsFEA Results - StressStress

FEA ResultsFEA Results - DeflectionDeflection

The Next Steps

•Static and Dynamic load cells were installed in the thrust bearing and the thrust bearing housing

•Shop factory testing indicated that load cells functioned properly

•Field testing / Operation will be the next step to determine if the these load cells prove to be beneficial to determine the onset of surge.

Joint GMRC / PRCI Project

• U$ 50,000 from GMRC

• U$ 50,000 from PRCI

• U$ 125,000 from US DoE / NETL

• Contractor: Southwest Research Institute

• In 2nd year of two year effort

• Discussions with potential commercialization partners