Four-Bed VPSA Oxygen Production with Single Vacuum Pump
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Solution Overview
Problem
Current vacuum pressure swing adsorption (VPSA) systems face challenges in achieving large-scale oxygen production (>350 tons/day) efficiently, with high energy costs and equipment requirements, limiting their cost competitiveness with cryogenic distillation for large-scale applications.
Innovation Solution
A four-bed VPSA system with dual feed inlets, utilizing two compressors and one vacuum pump, allowing 100% utilization of equipment, simultaneous feed to two beds, and using void space gas for purging without additional storage tanks, thereby reducing capital and operating costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional four-bed VPSA systems use two compressors and two vacuum pumps, then the system can handle large-scale oxygen production, but the capital cost and operating cost increase significantly
Solution Approach 1:
The patent combines the function of two vacuum pumps into a single vacuum pump by implementing a coordinated four-bed VPSA cycle where beds are operated in specific sequences. This merging reduces the number of vacuum pumps from two to one, thereby lowering capital costs and operating expenses while maintaining large-scale oxygen production capacity
Solution Approach 2:
The single vacuum pump is designed to handle multiple functions that previously required two separate pumps. The coordinated operation of four beds allows one vacuum pump to perform the evacuation function for multiple beds in sequence, making the single pump universally capable of maintaining the required vacuum conditions for large-scale oxygen production
2Reliability
If product quality gas is used for purging in VPSA systems, then the purging function is effective, but the loss of oxygen product increases
Solution Approach 1:
The patent implements a purging strategy where void space gas from one bed is used to purge another bed instead of using product quality oxygen gas. This approach recovers the purging function while avoiding the loss of valuable oxygen product, as the void space gas is otherwise waste gas that would be discarded anyway
Solution Approach 2:
The system uses its own void space gas (a byproduct of the VPSA cycle) to perform the purging function, making the system self-sufficient. This self-service approach eliminates the need to consume external oxygen product for purging, thereby reducing oxygen loss while maintaining effective bed regeneration
3Reliability
If compressors and vacuum pumps operate at less than 100% utilization, then equipment redundancy is provided, but capital costs and operating costs increase
Solution Approach 1:
The coordinated four-bed VPSA cycle is designed to ensure continuous useful action from both compressors and the vacuum pump. The bed sequencing and timing are optimized so that equipment operates continuously at high utilization without idle time, eliminating the need for redundancy while maintaining 100% availability for large-scale oxygen production
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 configuration achieves 10-20% improvement in oxygen productivity and 5-10% reduction in capital costs, enabling cost-effective large-scale oxygen production while avoiding the use of product quality gas for purging.
Implementation Method 1
vacuum pressure swing adsorption (VPSA) systems and processes that employ a single train including four beds
Implementation Method 2
The production of oxygen from air currently uses vacuum pressure swing adsorption (VPSA) or pressure swing adsorption (PSA) systems technology
Data Source
AI summary
The present invention generally relates to large capacity (e.g., greater than 350 tons/day O2) vacuum pressure adsorption (VPSA) systems and processes that employ a single train including four beds, at least one feed compressor feeding two beds simultaneously at any given instant in time, and a single vacuum pump. The compressor(s) and the vacuum pump can be utilized 100% of the time. Use of product quality gas for purging is avoided, with about 10-20% improvement in O2 productivity and 5-10% reduction in capital cost expected.