Tadashi KONDO
Fluid Machinery & Systems Company
In order for a high-pressure pump to operate stably in the place where it should play its role, it must provide an excellent balance and endure high pressures. These requirements are specific to high-pressure pumps. High-pressure pumps are based on technologies for achieving these requirements. This article outlines these technologies and how they are related to the structure of high-pressure pumps.
Fig. 1 Structure of a boiler feed pump (Model HDB)
Fig. 2 Water flow inside a boiler feed pump (Model HDB)
Table Basic types of Ebara's high-pressure pumps
Fig. 3 Double-suction impeller
Fig. 4 Single-suction impeller
Fig. 5 Balance of the axial thrust of impellers arranged in the same orientation
Fig. 6 Operating principles of the balance disc
Since a volute-type, axially-split-casing, multi-stage pump has impellers arranged back to back as shown in Figure 7, the thrust is offset between the right and left groups of single-suction impellers. For the doublesuction first stage, the thrust is calculated based on the concept described in (1) above. For the first-stage sleeve, balance sleeve, center stage piece (all these shown in Fig. 1), single-suction, single-stage impellers in the odd-numbered stages, and the other sections where the thrust is not offset, the thrust is calculated according to the pressure receiving area and differential pressure. The wearing diameters are thus designed so that the thrust is balanced throughout the rotor. Compared with the radially split type mentioned before, the shaft of the axially-split-casing type is relatively easy to design because the thrust that acts on the shaft is decentralized and no balance disc is required.
Fig. 7 Axial-thrust balance of the impellers arranged back to back
Fig. 8 Example of arrangement of casing bolts for Model SPD (for withstanding pressures up to 15 MPa)
Fig. 9 Longitudinal section of Model HDB
Fig. 10 Model HDB (with an outer casing that withstands pressures up to 55 MPa)
In this short article we introduced the high-pressure pumps associated with our everyday life in the first half and the basic structures of high-pressure pumps in the second half. I hope that you now understand highpressure pumps to some extent.
I am confident that Ebara’s high-pressure pumps are on the world’s top level in any area. This status was achieved, I believe, through the basic technologies described in this article as well as our detailed consideration and expertise about the design and manufacturing of pumps and our customers who highly rate the performance of our pumps. It is also the result of our long experience as well as occasional collaboration with our customers.
As an engineer, I hope that Ebara, not content with the status-quo, will support the next generation society by continuing to manufacture high-pressure pumps toward further development of the product.
Under the Scenes of our Lives High-pressure pump - Role and Application -
50% capacity boiler feed pump(BFP）playing an active role in a 1 000 MW thermal power plant
Large-capacity, Ultrahigh-efficiency, High-pressure Pumps for Seawater RO Desalination Delivered to Carlsbad Desalination Plant in the U.S.
Streamlines in crossover passage and velocity distributions at inlet of the second-stage impeller (Left:original,Right:optimized)
Discussion Meeting Symposium Ebara research system - Cooperation between research and business to create a new future -
Discussion Meeting (Mr. HIYAMA, Mr. SOBUKAWA, Mr. GOTO）
Under the Scenes of our Lives Standard Pumps - Essential Part of our Everyday Lives -
Examples of standard pumps
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