Page 449 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Steam Turbines and Turboexpanders 427

Note: The expander inlet screen should be positioned where it can be
conveniently removed for cleaning and still not interfere with the
operation of the safety shutdown valve.

Refer, also, to the maximum allowable pipe nozzle load drawing,
which experienced vendors will furnish.

Seal Gas System

Connect the plant’s seal gas supply to the filters on the control panel.
Refer to vendor-supplied data for requirements and to the system sche-
matic and control panel drawings for location.

Lube Oil Cooler
If the oil system incorporates air cooling, connect proper voltage to
each air-fan motor. Install, set and test vibration switch.

Variable Nozzles
After installing the nozzle actuator, connect the plant instrument air
supply and air signal line to the variable nozzle positioner. The vendor
should have provided data on pertinent pressures.
Safety Shutdown Valve

The expander shutdown valve (with solenoid) should be placed in the
process piping at the expander inlet. See that it does not interfere with the
screen. An adequate air supply must be connected to the solenoid valve to
enable the safety trip valve to close within onehalf second or less.

Electrical Connections

Refer to the system schematic and/or electrical schematic (or wiring
diagram) for wiring, and any applicable component manufacturer’s data.
On all components, care must be taken to use the terminal combinations
for the voltage to be used.

Veri& that all switching power feeders and circuit breakers are locked
out in the off position when connecting the power supply.

NOTE: To avoid electrical abuse, make certain that sensor lines to the
various switches are properly connected to the plug-in circuit
boards inside the junction box and not shorted to ground.