Motor Air-Gap Gas Recirculation to Cut Barrier Fluid Drag
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Subsea pumping systems face challenges with high gas volume fractions, leading to inefficiencies and increased costs due to the need for barrier fluids, which require complex systems for supply and maintenance, and result in drag losses and operational impracticalities in high-speed motors.
Innovation Solution
A system using an ejector to inject a mixture of gas and motive fluid into the air gaps of rotating machines, reducing viscosity and eliminating the need for barrier fluids by recirculating gas through the air gaps, thereby minimizing drag losses and simplifying the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier fluid is used in the air gap to prevent process fluid leakage, then motor reliability is improved, but device complexity increases due to dedicated supply systems and maintenance requirements
Solution Approach 1:
The invention extracts the barrier fluid function from the traditional liquid barrier system and replaces it with a gas-phase barrier (inert gas or vapor) in the air gap. This eliminates the need for complex liquid supply systems, reservoirs, and maintenance infrastructure while maintaining the motor sealing function.
Solution Approach 2:
The invention uses gas-phase materials (inert gases or vapor) instead of liquid barrier fluids to create the barrier function. The gas is introduced into the air gap to prevent process fluid leakage, leveraging pneumatic principles to achieve the same protective function with simplified system architecture.
2Reliability
If barrier fluid is used to seal the motor, then process fluid leakage is prevented, but drag losses increase due to fluid viscosity in the air gap
Solution Approach 1:
The invention changes the physical state parameter of the barrier material from liquid to gas phase. Gas-phase materials have significantly lower viscosity than liquids, which maintains effective sealing while dramatically reducing drag losses and improving motor efficiency.
Solution Approach 2:
By using gas-phase barrier materials instead of liquid barrier fluids, the invention exploits the low viscosity and compressibility characteristics of gases to reduce frictional drag in the air gap while maintaining the sealing function.
3Reliability
If liquid barrier fluid is used in high-speed motors, then sealing is achieved, but operational impracticality occurs due to high drag and efficiency losses
Solution Approach 1:
The invention changes the physical state from liquid to gas, which fundamentally alters the flow characteristics and reduces viscosity by several orders of magnitude. This makes the motor operable at high speeds where liquid barrier fluids would create excessive drag and efficiency losses.
4Productivity
If centrifugal pump is used in deep water, then pumping function is achieved, but system complexity increases due to exclusive well drilling and gas separation requirements
Solution Approach 1:
The invention extracts the gas separation function from the well infrastructure and integrates it directly into the pump system. The pump is designed to handle gas-liquid mixtures directly, eliminating the need for separate gas separation equipment and exclusive well drilling operations.
Solution Approach 2:
The pump system is designed with multi-functionality to handle both gas and liquid phases simultaneously, as well as provide the pumping function. This universal design eliminates the need for multiple separate systems (gas separation, liquid pumping, exclusive well infrastructure) and simplifies the overall system.
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 solution enhances motor efficiency, reduces operational costs, and simplifies the interface between the motor and surface units by eliminating the need for barrier fluids, while decreasing space requirements and drag losses.
Implementation Method 1
mixing a gas (08) from the gas-extraction unit (24) of pump (32) with a motive fluid (48) coming from discharge (14) of pump (32)
Implementation Method 2
said throat (04) being continued by a diffuser (06), which is responsible for the pressurization of mixture of gas (08) and motive fluid (48)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a system for the recirculation of gas in air gaps of rotating machines via an ejector (10), a motor (18) and a pump (32), consisting in circulating a gas (08) extracted from a gas-extraction unit (24) which is located in the pump (32). This gas circulates in the gap between the rotors (28) and the stator (26) of the motor (18). The rotor (28) of the motor (18) is coupled to the shaft of the pump (32), and in one embodiment the gas (08) from the gas-extraction unit (24) flows from the pump (32) to the ejector (10) in order to be injected into the air gap (20), the gap between the rotor (28) and the stator (26), thereafter returning to the process line (34). In another embodiment, the gas (08) from the gas-extraction unit (24) flows from the pump (32), being injected directly into the air gap (20), thereafter passes via the ejector (10) in order to recirculate the gas to the process line (34).