Advantages of variable speed drive in pump applications
Rekola, Juho Yrjö Eemeli
Permanent address of the item is
Muuttuvanopeuksisien käyttöjen hyödyt pumppusovelluksissa
The thesis is studying centrifugal pump’s variable speed drive’s advantages in Alfa Laval Aalborg’s steam boiler applications. Thesis consists of two main parts. First part examines requirements set for variable frequency drives in standards, regulations and classification societies’ rules. This part can be divided into two parts, requirements for industrial applications and requirements for use in marine applications. Second main part of the thesis is to compare different pump system configurations for Alfa Laval Aalborg’s steam system’s feed water pumping system. This part consists of investment cost analysis for different pump system configurations and from operational cost calculations for these pumping systems. Investment cost analysis includes procurement costs of parts needed in the pumping systems and pump unit assembly costs. Operational cost analysis studies pump systems’ energy consumption and costs derived from the energy consumption. These two parts combined together form cost analysis for the system. Cost analysis is done for two different types of steam generation systems. First analysis is done for diesel power plant’s waste heat recovery system and second analysis is carried out for ship’s steam production system. The analyses are carried out separately because systems’ operation profiles are different and therefore operational cost analysis needs to be carried out separately. Cost analysis show how cost effective variable speed drive can be in this applications. Operational cost calculations are done according centrifugal pump theory. This theory is introduced in the thesis and is been used to explain why variable speed drive in centrifugal pump application is able to save significant amounts of energy compared to direct drive application.