The Old Pump Design
The ancient pump was designed to have a low-speed all-welded impeller with the suction bell trimmed so as to fit into the undersized pump. It also had a lightweight pump column that comprised of thin welded carbon steel plates. In order to provide resistance to erosion, Dent notes that the bearings were made of very hard carbides. It is also seen pump had a long unsupported shaft making its design and shape look very inferior. However, with time, modifications were made in a bid to correct the inefficiencies of the pump.
The Original Sump Design
The sump dimensions of the original pump were not in accordance with the Hydraulic Institute Standard recommendations. This was concluded to be because of the many vortices that were generated as a result of the hindrance in the flow of water due to the shape defect. The many defects in the sump design called for modifications so as to improve its performance as Dent suggests.
The Program to Correct The System
In a bid to correct the problem of the pump it is noted that a program was developed to review the entire circulating water system. The first correction was that of replacement with a titanium condenser that had a higher tube velocity alongside other pump modifications. Despite the many options such as the dual-speed pumps, variable pitch propellers and variable speed each of the options was weighed in terms of their pros and cons before settling on the best.
Pump Design Features
According to Dent, the new modifications resulted in different designs although there were similarities. For instance, the variable pump design closely resembled the single-speed pump with the only difference being the low-speed bearings of the latter. Nevertheless, the new pumps were made of cast aluminum bronze which was made into three sections bolted together. Their water supply was improved as bearings were of rubber and water lubricated.
The New Pump Design
The new pump had a modified sump which had a flat bottom under the suction bell, curtains, and comer filters all of which were to stabilize and improve the water flow.
The Impact on Condenser and Turbine
Although the modification improved the functioning of the pump, it can be seen that the excessive temperature reduction resulted in efficiency loss. Dent suggested that this shortcoming could be corrected by lowering the speed of the pump. However, Dent notes that before any corrective measure is taken, it is important to determine the type of fouling used.