Reciprocating Compressor Seal Assembly for Shutdown Leakage

Solution Overview

Problem

Conventional reciprocating compressor rod packing systems experience leakage during shutdown, leading to inefficiencies and potential environmental hazards due to their segmented design, which allows fluid to escape to the atmosphere, and existing solutions either fail to prevent leakage or wear out quickly.

Innovation Solution

A seal assembly for reciprocating compressors featuring an unsegmented seal and a fluid passage with a valve to vent leaked fluid, combined with a bushing and seal carrier to reduce compressive load on the seal, allowing the seal to move radially and maintain a low contact pressure, thereby extending its lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If segmented rod packing is used, then the seal can withstand wear during normal operation, but leakage occurs during shutdown

Engineering Contradiction:

Improveseal lifespanVSAvoidsealing effectiveness during shutdown

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The seal assembly dynamically adjusts its configuration based on operational state. During normal operation, the segmented packing rings maintain contact with the rod to accommodate wear. During shutdown, the system transitions to a different sealing mode where the segmented packing is isolated from the rod, eliminating leakage paths while preserving the wear-resistant segmented structure for when operation resumes

Inventive Principle:

Principle #15Dynamics

2Reliability

If a single-piece seal like an O-ring is used, then leakage to atmosphere is prevented, but the seal wears out quickly

Engineering Contradiction:

Improvesealing effectivenessVSAvoidseal lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The sealing system uses segmented packing rings that can be individually replaced as they wear, while the overall assembly maintains a leak-tight configuration during shutdown. The segmentation allows wear distribution across multiple rings, extending the operational life of the sealing system while maintaining reliable sealing when needed

Inventive Principle:

Principle #1Segmentation

3Reliability

If the seal contacts the shaft during operation, then sealing is effective, but wear increases

Engineering Contradiction:

Improvesealing effectivenessVSAvoidseal lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The seal assembly dynamically adjusts its configuration based on operational state. During normal operation, the segmented packing rings maintain contact with the rod to accommodate wear. During shutdown, the system transitions to a different sealing mode where the segmented packing is isolated from the rod, eliminating leakage paths while preserving the wear-resistant segmented structure for when operation resumes

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10883483B2Seal assembly for reciprocating compressor

Publication Date: 2021.01.05 AIR PROD & CHEM INC

AI summary

A seal assembly for a reciprocating rod of a reciprocating compressor, a reciprocating compressor with the seal assembly, and a method of operating the reciprocating compressor with the seal assembly to prevent leakage of gas once the compressor has been shut down. The pressure difference between opposite sides of a static seal is kept low during normal operation to reduce wear of the static seal. When the compressor is shut down, a high pressure difference between opposite sides of the static seal assists with sealing.