Centrifugal Compressors Rerates and Retrofits – Power

Since motor drivers are seldom oversized, anything more than a minor power increase may require a new motor. This requires close evaluation of proposed process changes to see if necessary improvements can be achieved while still staying within the driver’s capabilities.

In contrast, turbines and gears can usually be modified to provide increased power. Although turbine data sheets will sometimes provide information regarding maximum steam flow or uprate capabilities, discussions with the manufacturer may be required.

From Equation200-11, you can see that gas horsepower (GHP) is directly proportional to weight flow (w) and head (H), or:

For example, if weight flow is increased by 10% and head is increased by 10%, the power requirement is increased by:

1.10 x 1.10 = 1.21 or 21%

Furthermore, a driver power margin of 10% is recommended. Therefore, the total recommended requirement is increased by:

1.21 + 10% (1.21) = 1.33 or 33%

Leave a Reply

Your email address will not be published. Required fields are marked *