Page 379 - Compression Machinery for Oil and Gas

360 SECTION II Types of Equipment

Example cold startup curve
6000
Critical speeds
Check overspeed trip
Lateral 2SQV9 2900 - 3000 rpm (calc.)
5M6-4 2600 - 2800 rpm (calc.)
MCS
Torsional 1254, 11852, 14599, 25146 rpm Calculated
5000
Rated speed
Speed values Min. required hold period
Low idle#1 500 rpm 10 min
2000 rpm 120 min
Low idle#2
Critical speed band 2400 - 3200 rpm
4000 Minimum speed
3600 rpm
High idle#1 70 min
Min speed 3856 rpm High idle speed
Speed (rpm) 3000 OVS 5567 rpm Critical speed band
MCS
5061 rpm
4820 rpm
Rated
Low idle speed #2 Governor valve
T&T valve
control
2000
control
Establish light vacuum
by enabling ejectors.
Then, open TTV
Check
1000 manual trip
Low idle
Enable GC
speed #1
supply seal steam increase vacuum
0
–1.0 0.0 1.0 2.0 3.0 4.0 5.0
Time (h)
FIG. 7.47 Cold start-up curve.
Example hot startup curve
(5–30 min after trip)
6000
0 Speed values Min. required hold period
Low idle#1 500 rpm 5 min
Low idle#2 2000 rpm 2 min
5000
Critical speed band
2400 - 3200 rpm
Check process
3 min
High idle#1 3600 rpm
Min speed 3856 rpm
Minimum speed
4000
Stop
High idle speed
Speed (rpm) 3000 Critical speed
band
Stop
seal
Low idle speed #2
steam
2000
T&T valve Governor valve
Establish light vacuum
control control
by enabling ejectors.
Then, open TTV
Disable GC
1000
Low idle
speed #1
Enable GC
supply seal steam increase vacuum
Break SC Restart
preparation
vacuum
0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
FIG. 7.48 Hot start-up curve.