Environmental Engineering Reference
In-Depth Information
Figure 21. Modifications to the solar collector field to protect against power failure.
8.2. Evaporating System
8.2.1. Evaporator Pump Maintenance
Pump problems were one of the main causes of plant downtime. The plant had 12 pumps:
seawater intake pump, seawater pump, seawater feed pump, brine blow-down pump, product
water pump, vacuum pump, drain pump, heat collecting pump, heating water pump, drinking
water pump, plant water pump and priming vacuum pump. All these pumps are motor-
operated centrifugal pumps pumping seawater, brine or product water except the vacuum
pump which is an oil ring-seal vacuum pump drawing in a mixture of vapor and non-
condensable gas from the evaporator. Most of the pump problems were started by a high-
pitch noise and vibration which gets worse as time goes on. The pumps dealing with seawater
or its brine were found to be more amenable to failure than the other pumps due to seawater
corrosion problems that affect the pump bearings.
Continuous operation of the evaporator had to be interrupted by pump trouble several
times. The pumps which gave most of the problems were the drain pump, the seawater intake
pump. Most of the problems were resolved by replacing the pump/motor bearings or
replacing the mechanical seal (or packing material). Many emergency plant shutdowns
happened because of “intake pit level low” signal due to air leakage through the shaft packing
of the seawater intake pump because of a worn out packing material. The suction line of this
pump operates at a vacuum due to the fact that the seawater suction point is below the pump
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