Cryogenic Submerged Pump Permanent Magnet Motor Efficiency
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Solution Overview
Problem
Cryogenic submerged motor pumps face limitations in operating speed and efficiency due to the use of induction motors, which result in higher rotor resistance losses and require slower speeds to minimize viscous friction drag, leading to reduced durability and increased costs.
Innovation Solution
A permanent magnet motor with a unique rotor geometry and high-speed operation is employed, eliminating the need for gear drives and utilizing multiple smaller impellers, along with advanced materials and manufacturing techniques to enhance efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pumps are used for LNG and cryogenic fluids, then the pumps can handle a wide range of fluids, but the pumps suffer from bacterial growth in seals, cavitation, and fluid leakage due to improper sealing and material selection
Solution Approach 1:
The patent changes the temperature parameter by using a cryogenic pump designed to operate at temperatures of -40°F to -200°F, which prevents bacterial growth in seals and maintains proper fluid viscosity. This parameter change fundamentally alters the operating conditions to eliminate the harmful effects of bacterial growth and cavitation
Solution Approach 2:
The patent employs composite material selection for seal and bearing components, using materials specifically selected for cryogenic service such as stainless steel and other low-temperature compatible materials. This material selection prevents fluid leakage and eliminates bacterial growth by ensuring materials remain intact and functional at cryogenic temperatures
2Ease of operation
If mechanical seals are used in conventional pumps, then sealing is provided, but fluid leakage occurs due to fluid warming and improper seal material selection
Solution Approach 1:
The patent changes the temperature parameter by maintaining cryogenic conditions throughout the pump system, including in the mechanical seal components. This prevents fluid warming that would cause seal deterioration and fluid leakage, while also preventing bacterial growth in the seal interface
Solution Approach 2:
The patent specifies seal materials selected for cryogenic service, such as stainless steel mechanical seals and other low-temperature compatible materials. These materials maintain their structural integrity and sealing properties at cryogenic temperatures, preventing fluid leakage that would occur with conventional seal materials
3Ease of manufacture
If conventional pump designs are used, then the pumps can be manufactured with standard components, but the pumps require significant modifications for cryogenic service including seal, bearing, and material changes
Solution Approach 1:
The patent segments the pump into distinct components (pump housing, mechanical seal assembly, bearing assembly, coupling) that can be manufactured separately using standard processes for each component type. This allows standard manufacturing techniques to be applied to each segment while the overall assembly is configured for cryogenic service
Solution Approach 2:
The patent designs the pump with universal features that can handle various cryogenic fluids (LNG, liquid hydrogen, liquid oxygen, nitrogen) through proper material selection and seal configuration. This multi-functionality reduces the need for significant modifications for different applications while maintaining cryogenic capability
4Strength
If standard pump materials are used, then material availability is high, but material embrittlement and structural integrity fail at cryogenic temperatures
Solution Approach 1:
The patent specifies materials selected for cryogenic service, including stainless steel and other low-temperature compatible materials that maintain their ductility and structural integrity at temperatures of -40°F to -200°F. These materials are specifically chosen to resist embrittlement that would occur with conventional materials at cryogenic temperatures
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
The solution achieves higher operating speeds, reduced parasitic losses, improved durability, and increased efficiency, while minimizing costs and size, resulting in enhanced performance and reliability for cryogenic fluid pumping.
Implementation Method 1
the liquid seal relies on hydrodynamic pressure distribution to maintain the seal
Implementation Method 2
Pump components will contract at cryogenic temperatures
Data Source
Figure 1
Figure 1A
Figure 1B
AI summary
A cryogenic submerged multi-stage pump assembly includes a vertically oriented pump shaft. A permanent magnet electrical motor includes a rotor attached to the pump shaft and a stator disposed about the rotor. A first-stage impeller assembly includes a first impeller attached to the pump shaft, the first impeller configured to move a cryogenic fluid from a first impeller inlet to a first impeller outlet when the pump shaft is rotated by the electric motor. A second-stage impeller assembly includes a second impeller attached to the pump shaft, the second impeller configured to move the cryogenic fluid from a first impeller housing to a second impeller inlet and then to a second impeller outlet when the pump shaft is rotated by the electric motor. The first and a second impeller housing are disposed about the first and second impellers and configured to channel the cryogenic fluid.