Page 87 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Chapter 2

Repair of Vertical Pumps*

Types of Vertical Pumps for Process Plants

The types of vertical pumps most commonly used in process plants
include multistage process and condensate pumps, single stage inline
process pumps, cooling water and cooling tower circulating pumps, and
deepwell pumps. The multistage process and condensate pumps as illus-
trated in Figure 2-1 utilize standardized diffuser bowl assemblies in-
stalled in an outer barrel that is under suction pressure. This type of
pump is often used where the available NPSH is not sufficient to accom-
modate a horizontal pump, or where space is at a premium. The first
stage impeller is located below foundation level, thus providing addi-
tional NPSH. Reference 1 classifies these as vertical canned pumps of
the double-casing type. Double casing refers to the type of construction
in which the pressure casing is separate and distinct from the pumping
element it contains. The single stage inline process pump shown in Pig-
ure 2-2 is simple, and pipe strain has minimal impact on rotating element
alignment. This type of pump is selected when low initial cost of the
pump, foundation, and piping is especially significant, and sufficient
NPSH is available. Cooling water and cooling tower circulating pumps
as shown in Figure 2-3 take suction from an open pit, sump, lake, river,
or ocean. They provide cooling water to process units and to steam gen-
erating plant condensers. A typical deepwell pump is shown in Figure
2-4. As the name implies, it pumps water from deep wells and is used to
supply makeup and utility water to process plants in areas where the wa-

* CopyrighP 1984 by Byron Jackson Pump Division, Borg-Warner Industrial Products,
Inc., Long Beach, CA. Reprinted by permission.

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