Dual Mechanical Seal Layout With Process Gas Leakage Return
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Solution Overview
Problem
Existing mechanical seal arrangements for sealing non-toxic gaseous media like carbon dioxide or nitrogen are costly due to the need for a separate barrier gas device, which incurs continuous operating costs and structural complexity.
Innovation Solution
A mechanical seal arrangement with two mechanical seals in series, where the first seal has an open gap in the non-operating state and returns leakage to the process chamber, while the second seal seals the fluid chamber from the bearing chamber, using the process medium as a barrier without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate barrier gas device is used to provide barrier gas for mechanical seals, then sealing reliability is improved, but device complexity and operating costs increase
Solution Approach 1:
The patent merges the barrier gas function with the process gas system by using the process gas itself as the barrier gas. The fluid chamber between the two mechanical seals is filled with process gas that serves dual purposes: as the medium being sealed and as the barrier gas protecting the mechanical seals, thereby eliminating the need for a separate barrier gas device.
Solution Approach 2:
The process gas performs multiple functions simultaneously: it is the medium being compressed/sealed and also serves as the barrier gas for the mechanical seals. This multi-functionality eliminates the need for separate barrier gas supply systems, reducing device complexity while maintaining sealing reliability.
2Reliability
If a separate barrier gas device is used to supply barrier gas under predetermined pressure, then sealing performance is improved, but operating costs increase
Solution Approach 1:
The system uses the process gas itself to provide the barrier function without requiring external barrier gas supply equipment. The process gas automatically fills the fluid chamber and provides barrier protection, eliminating continuous operating costs associated with separate barrier gas generation and supply systems.
3Reliability
If the first sealing gap is closed during operation, then sealing effectiveness is improved, but leakage recovery capability is reduced
Solution Approach 1:
The sealing system is divided into two separate mechanical seals with distinct functions. The first mechanical seal handles the primary sealing with its sealing gap closed during operation, while the second mechanical seal provides the barrier function. This segmentation allows the first seal to focus on sealing effectiveness while the system as a whole maintains leakage recovery capability through the fluid chamber and return line.
4Device complexity
If two mechanical seals are arranged in series without a fluid chamber, then structure is simpler, but leakage management becomes more difficult
Solution Approach 1:
A fluid chamber is introduced as an intermediary element between the two mechanical seals. This fluid chamber serves as a collection point for leakage from the first seal and a distribution point for barrier gas to the second seal, facilitating leakage management while maintaining a relatively simple overall structure.
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 design achieves reliable, cost-effective sealing with minimal leakage, eliminating the need for a separate barrier gas device and allowing the use of non-toxic media like carbon dioxide or nitrogen, while maintaining sealing performance at high speeds.
Implementation Method 1
The first mechanical seal comprises a rotating and a stationary slide ring, which define a first sealing gap between their sliding surfaces. The second mechanical seal comprises a rotating and a stationary slide ring, which define a second sealing gap between their sliding surfaces.
Implementation Method 2
The mechanical seal arrangement comprises a first and a second pretensioning device. The first pretensioning device prestresses the stationary slide ring of the first mechanical seal and the second pretensioning device prestresses the stationary slide ring of the second mechanical seal.
Implementation Method 3
A return line in a housing leads off from the fluid chamber, which is configured to return the gaseous, non-toxic medium to the process area.
Data Source
AI summary
The invention relates to a mechanical seal arrangement for sealing a process chamber (6), which is filled with a non-toxic, gaseous process medium, with respect to a bearing chamber (8), comprising a first mechanical seal (2) with a rotating slide ring (20) having a first sliding surface (20a) and a stationary slide ring (21) having a second sliding surface (21a), which define a first sealing gap (22) between the sliding surfaces (20a, 21a), a second mechanical seal (3) with a rotating slide ring (30) having a third sliding surface (30a) and a stationary slide ring (31) having a fourth sliding surface (31a), which define a second sealing gap (32) between the sliding surfaces (30a, 31a), a first pretensioning device (4) which prestresses the stationary slide ring (21) of the first mechanical seal (2) in the axial direction (X-X) and a second pretensioning device (5) which prestresses the stationary slide ring (31) of the second mechanical seal (3) in the axial direction (X-X), a fluid chamber (7) arranged between the first mechanical seal (2) and the second mechanical seal (3), which is in fluid connection with the first and second sealing gap and, in operation, receives leakage from the process chamber (6) via the first sealing gap (22), and from which a return line (9) leads off, configured for a return of process medium from the fluid chamber (7) to a process area.