Dry Gas Seal Pumping for Low-Pressure Rotary Machine Housings

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Solution Overview

Problem

Rotating machines generate heat due to gas churning within sealed chambers, leading to energy loss and inefficiencies, as existing technologies fail to effectively reduce this heat generation.

Innovation Solution

A dry gas seal is used to pump gas out of the sealed chamber, reducing the pressure to below atmospheric levels, thereby minimizing gas churning and associated heat generation, utilizing a non-contacting mechanical gas seal with a mating and primary ring configuration that allows controlled gas leakage to create a pressure dam and separate the rings, allowing for relative movement without contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the shaft rotates within a sealed chamber containing gas at atmospheric pressure, then the shaft is properly sealed and supported, but heat generation due to gas churning increases energy loss

Engineering Contradiction:

Improveenergy lossVSAvoidheat generation

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The patent changes the pressure parameter of the gas environment from atmospheric pressure to reduced pressure (vacuum conditions). This parameter change reduces gas density and viscosity, thereby minimizing gas churning and heat generation during shaft rotation, directly addressing the energy loss problem.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates an inert vacuum environment within the sealed chamber by removing gas molecules. This inert environment eliminates the harmful interaction between the rotating shaft and gas molecules, preventing heat generation from gas churning while still allowing the shaft to rotate freely.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Reliability

If a traditional contact seal is used to seal the shaft, then sealing is achieved, but friction and heat generation increase

Engineering Contradiction:

ImprovesealingVSAvoidfriction

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces traditional mechanical contact seals with a magnetic coupling system that operates in a vacuum environment. The magnetic coupling provides sealing without physical contact, eliminating friction-based energy loss while maintaining sealing reliability through magnetic field interaction across the seal interface.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the rotating shaft and the external environment. This magnetic field mediates the transmission of rotational force and provides sealing functionality without requiring direct mechanical contact, thereby eliminating friction and heat generation associated with traditional contact seals.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If the pressure in the housing is reduced to below atmospheric pressure, then heat generation from gas churning is reduced, but gas leakage into the housing must be controlled

Engineering Contradiction:

Improveheat generationVSAvoidpressure control

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent implements a feedback control system that monitors the pressure differential across the seal interface and adjusts the pumping rate accordingly. This feedback mechanism maintains the vacuum environment by compensating for gas leakage, ensuring pressure control reliability while minimizing heat generation from gas churning.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The magnetic coupling system automatically maintains the vacuum seal by leveraging the pressure differential itself. The external atmospheric pressure pushes the seal interface against the rotating shaft, creating a self-sealing effect that minimizes gas leakage without requiring additional active control, thereby maintaining pressure control reliability while reducing heat generation.

Inventive Principle:

Principle #25Self-service

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 significantly reduces heat generation and energy loss by lowering the pressure in the sealed chamber, achieving energy savings and potential cost reductions while minimizing emissions.

Implementation Method 1

a pressure differential between a process cavity and a seal chamber

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

the gas that is drawn into the grooves is compressed... The compressed gas creates a pressure dam that causes the primary ring to 'lift off' from the mating ring

Methodology Applied

Scientific EffectGas pressure: Pressure Gradient

Implementation Method 3

reducing the pressure in the sealed chamber... reduces gas density and viscosity, thereby minimizing gas churning and heat generation

Methodology Applied

Scientific EffectPressure reduction: Depressurisation

Data Source

PatentUS11870320B2Pumping seal for rotating machines

Publication Date: 2024.01.09 JOHN CRANK UK

AI summary

A rotary machine includes a rotating shaft, a housing that surrounds a portion of the rotating shaft and has an initial pressure therein and a gas seal that pumps gas out of the housing to reduce pressure in the housing to an operating pressure that is less than the initial pressure.