Axially Split Centrifugal Pump Connecting Element

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Solution Overview

Problem

Centrifugal pumps with back-to-back configurations face manufacturing difficulties due to complex geometry in the inversion module, high hydrodynamic losses, and challenges in balancing and disassembling impellers, particularly with shrink-fit attachments.

Innovation Solution

The design features an axially split centrifugal pump with two units connected via a connecting element, where each unit comprises impellers and diffusers, and the inner case is split into two half-parts for easier assembly and reduced hydrodynamic losses, with a groove in the connecting element to facilitate sealing and pressure-assisted assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the inversion module is designed with complex geometry to connect the first and second phases, then the pump can achieve back-to-back configuration for reduced axial thrust and increased efficiency, but the manufacturing difficulty increases significantly requiring casting methods

Engineering Contradiction:

Improveaxial thrust balanceVSAvoidinversion module manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The pump is divided into two separate units (first unit and second unit), each with its own impeller and diffuser. The inversion module is eliminated by using a connecting element that directly joins the two units. This segmentation allows each component to be manufactured separately with simpler geometry, avoiding the complex casting required for the traditional inversion module.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the inversion module has complex geometry with several turns and small radius, then the back-to-back configuration is achieved, but hydrodynamic losses increase significantly

Engineering Contradiction:

Improveconfiguration stabilityVSAvoidhydrodynamic losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The inversion module, which causes high hydrodynamic losses due to its complex geometry with multiple turns and small radius, is completely removed from the design. Instead, a simple connecting element directly joins the first and second units, allowing fluid to flow from the first diffuser outlet to the second impeller inlet without passing through the tortuous path of an inversion module, thereby eliminating the associated energy losses.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If each impeller is balanced separately in the back-to-back configuration, then the rotor cannot be balanced as a whole, but the manufacturing process becomes more complicated

Engineering Contradiction:

Improveimpeller balancingVSAvoidbalancing process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The two units are connected through a common connecting element that integrates them into a single assembly. This allows the rotor (comprising both impellers and the connecting element) to be balanced as a complete assembly rather than requiring separate balancing of each impeller, simplifying the balancing process and improving overall rotational balance.

Inventive Principle:

Principle #5Merging (Combining)

4Strength

If the impellers are attached by shrink fit, then the connection is strong, but disassembling becomes very complicated due to inaccessibility of the back of the last impeller

Engineering Contradiction:

Improveimpeller attachment strengthVSAvoidimpeller disassembly

Core Design Contradiction:

StrengthVSEase of repair

Solution Approach 1:

The pump is segmented into two separate units that are connected by a connecting element rather than being integrated into a single enclosed structure. This segmentation provides access to both impellers from the outside, allowing for easier disassembly and maintenance while maintaining strong shrink-fit attachments, as the connecting element can be accessed and removed to separate the units.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration simplifies manufacturing, reduces hydrodynamic losses, and allows for easier balancing and disassembly of impellers, enhancing the operational efficiency and stability of the pump.

Implementation Method 1

The centrifugal pump further comprises a connecting element between the first unit and the second unit, the connecting element being engaged with a last impeller of the first unit and with a last impeller of the second unit.

Methodology Applied

Scientific EffectMechanical Fastening: Mechanical Fastener

Implementation Method 2

Each unit also comprises a plurality of diffusers. Each diffuser is placed around a respective impeller.

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11555496B2Centrifugal pump

Publication Date: 2023.01.17 NUOVO PIGNONE TECH SRL

AI summary

A centrifugal pump including an outer case; an inner case; a first unit and a second unit placed in fluid communication with each other, each unit including a plurality of impellers; the inner case includes two half-parts joined along a connection plane containing the axis of rotation; a connecting element is placed between the first unit and the second unit, the connecting element is engaged with a last impeller of the first unit and with a last impeller of the second unit.