Multistage Gas Shaft Sealing With Inlet Pressure Equalization
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Solution Overview
Problem
High differential pressures in gas processing equipment, such as compressors, pose challenges in maintaining effective sealing, leading to increased pressure pulsation, lubrication oil consumption, and gas emission, as existing sealing systems struggle to manage the stress and containment of gas effectively.
Innovation Solution
A progressive sealing system with multiple pressure spaces along the shaft, including an intermediate pressure space in hydraulic communication with the process gas inlet, recirculates leaked process gas back to the inlet, reducing pressure differential and contact pressure, and utilizing a series of seals and ports to manage pressure equalization and lubrication, thereby reducing seal wear and pressure pulsation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high differential pressure is maintained in the sealing system, then effective sealing is achieved, but pressure pulsation and stress on sealing elements increase
Solution Approach 1:
The sealing system is divided into multiple sealing members arranged in series along the shaft, creating multiple sealing stages. Each sealing member handles a portion of the pressure differential, segmenting the total pressure load into manageable stages that reduce pressure pulsation while maintaining overall sealing effectiveness.
Solution Approach 2:
An intermediate pressure space is introduced between the high-pressure cavity and the atmosphere, serving as a pressure buffer zone. This intermediary space allows progressive pressure reduction through multiple sealing stages, dampening pressure pulsations that would otherwise directly transmit through the sealing system.
2Reliability
If high differential pressure is maintained, then sealing containment is improved, but lubrication oil consumption increases
Solution Approach 1:
The sealing system uses multiple sealing members in series, with each member operating at a reduced pressure differential compared to a single-stage seal. This segmentation reduces the force driving lubrication oil through each sealing interface, thereby reducing overall oil consumption while maintaining gas containment.
Solution Approach 2:
The system utilizes the process gas itself as a sealing medium in the intermediate pressure space, creating a pneumatic seal that reduces reliance on lubrication oil for sealing purposes. The pressurized process gas helps prevent oil from being drawn into the sealing interface.
3Reliability
If high differential pressure is maintained, then sealing effectiveness is improved, but gas emission to atmosphere increases
Solution Approach 1:
Multiple sealing members create multiple barriers to gas leakage. Each sealing member provides an additional layer of protection against gas emission, with the intermediate pressure space serving as a detection and containment zone that prevents direct atmospheric release of leaked process gas.
Solution Approach 2:
The intermediate pressure space acts as a feedback mechanism, allowing monitoring and control of sealing performance. By maintaining this intermediate zone, the system can detect and respond to sealing issues before they result in significant atmospheric emissions, enabling corrective action.
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
The solution effectively reduces pressure differential across seals, extends seal life, minimizes gas loss and lubrication oil consumption, and provides a cooling effect through gas expansion, while maintaining high-pressure containment and reducing pressure pulsation.
Implementation Method 1
The maximum pressure in the intermediate pressure space is lower than a greater of the input pressure and the output pressure, and higher than atmospheric pressure
Implementation Method 2
pressure is reduced along the shaft in stages, or progressively along a labyrinth
Implementation Method 3
provides a cooling effect through gas expansion
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A gas processing system includes a vessel (102) defining a cavity (106) for processing a gas. The vessel includes a process gas inlet (108) for accepting process gas at an input pressure, and a process gas outlet (110) for discharging process gas at an output pressure. The gas processing system further includes a shaft (122) coupled to the vessel and a multistage sealing system (114) comprising multiple seals (136) spaced along the shaft. The shaft is configured to transfer mechanical energy to or from gas in the vessel. Each adjacent pair of seals defines a corresponding pressure space therebetween. One of the pressure spaces is an equalizing pressure space (144a) in hydraulic communication with the process gas inlet via a flow line (116), such that in operation, pressure in the equalizing pressure space is maintained at an equalized pressure with respect to a pressure in the process gas inlet.