Technological Development

The high-efficiency oxygen generating device "HT-PSA"

The HT-PSA (High Temperature-Pressure Swing Adsorption) reduces electric power consumption significantly and the costs for oxygen generation to enable energy savings and cost reductions in existing oxygen generation facilities. Through low cost oxygen generation and the subsequent introduction of oxygen-rich combustion, energy saving can be achieved in such processes as high-temperature industrial furnace and steelmaking. Furthermore, it can contribute to the efficient recovery of CO₂ in the future.

 

Outline

This technology HT-PSA utilizes PSA (Pressure Swing Adsorption), a typical gas separation technology. The remarkable point is to use a perovskite oxide as an absorbent to both absorb and desorb oxygen by fluctuating the pressure while maintaining the high temperature of the absorbent at approximately 600 centigrade. Perovskite oxide has a unique crystal structure, and the perovskite oxide used in this technology captures only oxygen under high temperatures and high oxygen partial pressure, and desorbs the oxygen when the pressure decreases (and the partial pressure of the oxygen becomes low). It is also highly capable as an absorbent with an oxygen- nitrogen separation factor of 10 or higher. Furthermore, the technology enables highly-efficient heat recovery by using a regenerator as a heat exchange system to maintain the temperature of the absorbent at around 600 centigrade.
 
Currently, even with the utilization of the cryogenic separation method which is capable of generating oxygen of the highest efficiency, the electric power consumption rate stands at approximately 0.3kWh/m³N-O₂. However, HT-PSA technology indicates an improved electric power consumption rate of approximately 0.2kWh/m³N-O₂, owing to the superior capabilities of the perovskite oxide as an absorbent, and the highly-efficient heat recovery technique through the installation of  the regenerator. The electric power consumption rate of this technology is significantly superior to that of the 0.3～0.4kWh/m³N-O₂ of oxygen generation by the conventional PSA method.
 
The original concept for this technology was proposed by Adsorption Technology Industries Ltd. and KASTEC (Art, Science and Technology Center for Cooperative Research, Kyushu University), Miura Laboratory, with basic tests conducted under the NEDO (New Energy and Industrial Technology Development Organization) Research and Development Program for Innovative Energy Efficiency Technology in fiscal 2010.
Research and development was conducted between 2011 and 2013 under the NEDO project (development of practical applications stage).
Under the NEDO project for Strategic Innovative Energy Saving Technology (development for demonstration stage), we enhanced the efficiency and expanded the size of the equipment from 2014, while also pursuing lower costs in the absorbent along with mass production. In 2015, our prototype unit with an oxygen production capacity of 100m³N/h achieved an electric power consumption rate of approximately 0.4kWh/m³N-O_2, which exceeded our target of 0.5kWh/m³N-O_2.


 
At high temperatures of around 600℃ and under low pressure (low oxygen partial pressure), Perovskite-type oxides undergo a phase change and take on a Brownmillerite structure, desorbing oxygen in the process. This reaction is reversible, as increasing pressure (high oxygen partial pressure) results in the oxygen molecules to be readsorbed.
 

Characteristics

 

• Generates oxygen at the world’s highest level, approximately 0.2kWh/m³N-O₂ of an electric power consumption rate.
• Generates oxygen of 95% or higher concentration levels that the conventional PSA method cannot achieve.
• Able to extract nitrogen-rich gas to produce oxygen-rich gas concurrently.

 

Perspective

Since 2016, we scaled up the prototype unit, and developed a demonstration unit that targeted oxygen generation capacity of around 500m3N/h aiming at its electricity emission factor of 0,25 kWh/m3N-O2. We are targeting at the development of scaled-up units corresponding to the various sizes of oxygen demand of the users and planning the launch in the market. Thereafter, we continued to gradually pursue larger scales, and we plan to ultimately develop a model with oxygen generation capacity of around 10,000m3N/h and launch it into the market. If we are able to develop a low cost oxygen generation method, we will be able to realize energy conservation through oxygen-rich combustion, even in fields where it is conventionally not widely used. Furthermore, in the case of pure oxygen combustion, the CO2 concentration level of the exhaust gas will be more than 90%, the effective CO2 recovering can contribute to improvements in the economical efficiency of CCSU（Carbon Capture and Storage, utilization）.
 

Remarks

This technology is being developed by Tokyo Gas with the assistance of the NEDO Program for Strategic Innovative Energy Saving Technology.

 

• Project leading by: Tokyo Gas Co., Ltd., Industrial Energy Department
• Collaborate with: Adsorption Technology Industries Ltd., and Tokyo Gas Chemicals Co., Ltd.
• Project period: FY2014-FY2016