Small-Scale Pressure Swing Adsorption Oxygen Production Technology Test

 Small-scale pressure swing adsorption oxygen production technology
 

Small pressure swing adsorption (PSA) oxygen production technology uses air as raw material to produce oxygen through physical adsorption, with electricity as its only energy source. Within minutes of being powered on, the equipment can continuously produce medical oxygen with an oxygen content greater than 90%, meeting medical care standards. This technology offers advantages such as simple operation, reliability, long-term oxygen supply, and cost-effectiveness.

Small PSA oxygen concentrators are widely used in hospitals, homes, hotels, oxygen bars, and other public places, with strict requirements for size, weight, noise, and energy consumption. To meet these demands, the concentrators must be compact, lightweight, portable, quiet, and energy-efficient. To further enhance the performance of the small PSA oxygen generator, this study explores factors influencing oxygen production, including molecular sieve selection, switching time, optimization of pressure equalization steps, and oxygen storage tank capacity. The goal is to improve oxygen production efficiency, reduce energy consumption, and extend the equipment's service life through these optimizations.

 

 

 

Process flow

Pressure swing adsorption (PSA) oxygen production relies on the different adsorption capacities of zeolite molecular sieves for oxygen and nitrogen under varying pressures. At high pressure, nitrogen is adsorbed, enriching oxygen, while at low pressure, nitrogen is desorbed, yielding oxygen-rich gas. Multiple adsorption beds are switched in sequence for continuous oxygen production. Common PSA processes include high-pressure adsorption with atmospheric desorption (PSA), pressurized adsorption with vacuum desorption (VPSA), and atmospheric adsorption with vacuum desorption (VSA).

The PSA process is widely used in small-scale oxygen production due to its simplicity and low investment, but its high energy consumption has driven interest in the more energy-efficient VPSA process. In recent years, VPSA technology has gained traction in small-scale applications, with products already launched abroad.

To improve gas recovery, oxygen purity, and reduce energy consumption, the pressure equalization (PE) step has been introduced. This step connects two adsorption towers, allowing gas from the high-pressure tower to flow into the low-pressure tower, balancing their pressures. This recovery of mechanical energy and optimization of gas concentration distribution enhances energy efficiency and recovery rates.

Studies show that the PSA process with PE significantly reduces switching pressures, compressor power loss, and bed power loss while improving energy efficiency and gas recovery. While PE has been widely applied in large-scale systems, its use in small-scale devices is less common due to technical and cost limitations. In small-scale PSA oxygen production, PE can be implemented at the inlet, outlet, or both ends of the adsorption tower, improving performance, efficiency, and energy savings.

 

 

Test process

1-filter; 2-compressor; 3-cooler; 4-pressure gauge; 5-two-position five-way solenoid valve; 6-muffler; 7-adsorption tower; 8-pressure equalizing solenoid valve; 9-throttle valve; 10-three-way valve; 11-check valve; 12-gas storage tank; 13-pressure limiting valve;
14-flow meter; 15-control panel

The experimental device uses a control panel to manage the two-position five-way solenoid valve and the pressure equalizing solenoid valve, enabling three process configurations: no pressure equalization, pressure equalization at the air inlet, and pressure equalization at both ends of the adsorption tower. The system adjusts the pressure equalizing time and air inlet connection time to switch between these processes.

Air is purified, compressed, and cooled before entering the adsorption tower with zeolite molecular sieve for separation. The separated oxygen flows into a gas storage tank, while the remaining nitrogen is vented. Oxygen flow is controlled by a flow meter, and switching time is adjusted via the control panel. Oxygen content is measured using the copper ammonia solution method and YHL intelligent oxygen meter.

This experiment focuses on the impact of factors like molecular sieve type, switching time, pressure equalization steps, adsorption tower ratio, and storage tank volume on oxygen production. Some parameters are dimensionless for clearer analysis of their effects on performance.

Conclusion
 

Different types of molecular sieves have significant impacts on oxygen production efficiency, with LiX molecular sieve performing the best. Using LiX can greatly reduce the size of the adsorption tower, lower the oxygen-to-air ratio, and enhance overall machine performance.

Switching time is a key parameter in pressure swing adsorption (PSA) oxygen production. The optimal switching time for a specific system must be determined through experimentation.

Introducing a pressure equalization (PE) step can effectively increase oxygen content and recovery rate, leading to energy savings. The addition of a single PE step significantly improves both oxygen concentration and recovery rate. Therefore, for small-scale PSA oxygen production systems, a simple one-step PE process is commonly used.

Increasing the height-to-diameter ratio of the adsorption tower helps improve oxygen production performance in small-scale PSA systems. However, excessively high ratios can reduce the utilization of molecular sieves and cause significant wall effects, which negatively impact oxygen production efficiency.

Increasing the capacity of the gas storage tank helps improve oxygen content and reduce fluctuations in oxygen supply.