HIGH JOURNAL TEMPERATURE ISSUE ON FLENDER GEARBOX

• Gearbox mentioned here is transmission of compressor train 10-K-4021which compresses natural gas to supply process air for the plant.

• Name Unit: Process Air Compressor 10- K-4021

1. Introduction

•Service: Process

Air

•Compressor Driver:

Steam Turbine.

•Bearing of gearbox:

offset type.

1. Configuration

ST LP comp

HP comp

LSS

HSS

Phenomenon Time Event Corrective actions Results

7/7/2009 : bearing

temp. of input shaft

increased

2009 Major maintenance

for Gearbox with

attention of Flender

specialist

Replace new JB and Thrust bearings.

Realignment of Comp. train

(Pls. refer to your report attached)

The temperature was

gradually increased;

however, it was still in

acceptance limit.

Temperature has

fluctuated unstably

with high amplitude

value (over 100oC)

2011 Major maintenance

for GB.

Replace journal bearing and thrust bearing of gearbox

Realignment of comp. train.

JB temp. of output

increased to alarm setpoint

of 100oC.

01/2012 Minor maintenance. Kept using old JB and increased bearing clearance to

average value of specification (0.15mm for HSS, and

0.16mm for LSS) by hand.

Alignment for coupling between GB – 2MCL805 and GB –

2MCL 356.

Temperature also increased

to 105oC after 6 months of

running.

08/2012

Minor maintenance.

Kept using old JB and increased bearing clearance to

average value of specification. (0.16mm for HSS, and

0.17mm for LSS) by hand

Alignment for coupling between GB – 2MCL805 and GB –

2MCL 356.

Temperature have still

increased to 111oC (over

software alarm 110oC)

9/2013 Minor

maintenance

Change new modified bearing (modified by

OEM) with clearance increased to 0.17mm.

Temp. is stable with

value under 80oC. 5/2015 Minor maintenance Keep reused bearing, just alignment checks, contact and

backlash check.

Temp. is stable with value

under 80oC.

12/2017 Major maintenance Change new bearing set with clearance of HSS: 0.16mm,

LSS: 0.19mm.

Change new thrust bearing and opinion & gear set.

Revamp the ammonia plant to increase from 100% to

120% load.

Temp increasing with time.

After 3months of running,

the temp increase to 103oC.

1. History summary

2. problem

BEFORE REVAMP AFTER REVAMP

Stable 76-77oC Unstable:

82-102oC

After 3months of running, the temp increase to 103oC.

3. What done in turnaround 2017?

1. Replace new set of opinion and gear.

2. Replace new journal and thrust bearing.

4. How about alignment and clearance?

Shaft alignment between LSS and compressor and HSS and HP comp is in spec. of OEM.

GB – HP

compressor

LP comp –

GB

1. How about alignment and clearance?

Gear contact

Backlash 0.5mm

Spec. 0.4-0.64mm

Axial clearance 0.33mm

Spec. 0.33-0.55mm

4. How about alignment and clearance?

Journal bearing clearance

5. How about the oil?

Oil is new and qualified by BP.

www.dpm.vn

6. What change in turnaround

Before Revamp After Revamp SPEC

Load of compressor train

100% 107%-110%

Speed 10,600 rpm 10,700-10,800

rpm

Temperature 76-77oC 82-102oC Trip 125oC

Vibration 10um 10-11um

JB at LP comp of HSS

0.16mm 0.16mm 0.13-0.174mm

JB at HP comp of HSS

0.17mm 0.16mm 0.13-0.174mm

We revamped the ammonia unit in turnaround which the

load of compressor was increased around 107-110%

compared to the previous load.

7. What records from monitoring system (system1)

Journal bearing temperature

7. What records from monitoring system (system1)

Axial displacement and Thrust bearing bearing temperature

7. What records from monitoring system (system1)

Radial vibration

7. What records from monitoring system (system1)

805 -HSS 356 HSS

356 - DE 356- NDE

Shaft centerline in operation

after turnaround is normal.

JB temperature is changed

when load change 2%

1X

Radial Vib is under 11um

7. What records from monitoring system (system1)

Cause: when the load increased after revamp the clearance is considered not enough which seems to make the bearing temperature increase.

Suggestion: increase the journal bearing clearance as followings:

8. Our evaluation and suggestion

Shaft Clearance SPEC

LSS LP compressor side 0.23mm 0.15-0.194mm

HP compressor side 0.23mm

HSS LP compressor side 0.19mm 0.13-0.174mm

HP compressor side 0.20mm