Page 436 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

414 Major Process Equipment Maintenance and Repair

Llnkage Adjustments
1. Rotate the terminal output shaft to the middle position of its total
travel. Place the terminal shaft lever (17, Figure 8-20) on the shaft
so that it is in the vertical position.
2. Tighten cap screw (18) to secure lever (17) to the terminal shaft.
3. Move terminal shaft lever (17) to the full open position (clockwise
direction).
4. Connect adjustable connecting rod (15) to the terminal shaft lever
(17) by placing shoulder screw (13) through rod end (14).
5. Replace elastic stop nut (19) on shoulder screw (13).
6. Loosen the governor valve stem jam nut, and turn the valve stem
out of the governor valve connection until the valve is firmly-
Seated.
7. Back the valve off of the seat, by turning the stem into the connec-
tion to provide design valve travel.
8. Lock the valve stem jam nut.
Operation and Maintenance of
Cryogenic Plant lurboexpanders'

Turboexpanders have been used for many years in cryogenic process-
ing plants to generate the deep, low-temperature refrigeration required by
industry for gas separation and liquefaction or purification, the recovery of
power from waste heat, and for other rleated processes. Figure 8-21 shows
one such machine.
The turboexpander is a specialized, high-efficiency turbine, develop-
ing the required low temperature by removing heat from the process
stream as power, thus chilling the gas. The power developed is a by-
product of the gas expansion, and the amount of chilling is equal to the
power generated. To absorb this energy, various loading devices are
used. Machines developing less than 50 hp normally dissipate the energy
in an oil turbulence device (dynamometer). For the recovery of higher
amounts of power, integral compressor loads, electric generators, or
pumps are usually used.
Today's high-speed turboexpanders are of rugged construction, suit-
able for years of troublefree service with minimum attention to mainte-
nance after installation and startup. Provisions are built into the systems
to resist numerous abuses to which they may be subjected, such as ice
deposits, solids passing through from plant lines, pressure surges, sudden
cooldown, etc.

* Copyright? Rotoflow Corporation, 1983. Repriuted by permission.