Pressure-Balanced Seal Cascades for High-PV Rotating Equipment
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Solution Overview
Problem
Existing sealing technologies for expanders and compressors face challenges in handling high operational PV ratios and providing cost-effective sealing solutions, especially in applications like Organic Rankine Cycle (ORC) processes and gas pipeline systems, where maintaining process fluid purity and preventing lubricant contamination are critical.
Innovation Solution
The implementation of pressure balancing and cascading techniques using process fluid to reduce the pressure differential across seals, combined with magnetic couplings and pressurized lubricant circulation systems, allows for efficient sealing and contamination prevention, while also extending the operational pressure capacity of equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seals are used in high PV applications, then sealing capability is limited, but device complexity and cost increase when attempting to overcome these limits
Solution Approach 1:
The sealing system is divided into multiple independent seals arranged in series, each handling a portion of the total pressure differential. This segmentation allows each seal to operate within its PV limits while collectively managing high pressure applications, avoiding the need for a single complex high-PV seal design
Solution Approach 2:
A sealing fluid is introduced as an intermediary substance between the process fluid and atmosphere. This sealing fluid creates a pressure barrier that reduces the effective pressure differential across critical seals, enabling them to operate within their PV envelopes while maintaining reliable sealing in high-pressure applications
2Reliability
If pressure differential across seals is reduced through balancing techniques, then seal reliability improves, but system complexity increases
Solution Approach 1:
The pressure balancing function is merged with the existing sealing system architecture by integrating sealing fluid injection ports and pressure control mechanisms into the seal housing. This combination achieves pressure differential reduction without requiring a completely separate balancing system, thereby improving seal durability while limiting the increase in system complexity
3Reliability
If lubricant circulation systems operate under pressure blanket, then contamination prevention improves, but energy consumption increases
Solution Approach 1:
The lubricant circulation system is designed to utilize the existing pressure differential in the process system to maintain the pressure blanket, rather than requiring continuous active pressurization. The system self-regulates by allowing lubricant to circulate under the natural pressure conditions, preventing contamination while minimizing additional energy consumption
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 approach effectively reduces the PV factor on seals, enhances seal durability, and prevents lubricant contamination, thereby improving the efficiency and reliability of sealing systems in various industrial applications, including ORC processes and gas pipeline systems.
Implementation Method 1
a driver shaft magnetic coupling to a driven shaft
Implementation Method 2
pressure balancing and cascading techniques using process fluid to reduce the pressure differential across seals
Implementation Method 3
pressurized lubricant circulation systems, allows for efficient sealing and contamination prevention
Data Source
AI summary
A method and system is provided for pressure balancing one or more seals in machines such as expanders and/or compressors using the process fluid which is being expanded or compressed to provide the pressure for pressure balancing the other side of the one or more seals. The one or more seals may be part of a pressure containing chamber which may comprise a seal, a bearing and/or a gear on a rotating shaft common to the seal. An amount of pressure to be supplied to housing(s) for a machine so as to create a pressure cascade, and thereby dropping the pressure in each subsequent chamber as pressure approaches atmosphere. Pressure differentials may be directed to leak process fluid to the chamber into the process. Pressurized lube oil systems may be employed for balancing pressure and delivering lubricant to the seals, bearings and gears.