Validation of a system for simultaneous harvesting of water and heat using a steam recovery membrane

Key points of this research results

  • Proposed and validated a system that extracts steam and heat from combustion exhaust gases using a separation membrane. 
  • In a waste incineration plant, the system was found to eliminate the need for external water supply and recover 70% of combustion heat. 
  • The proposed system is believed to be applicable not only to waste incineration plants but also to any steam emission source, such as power plants and chemical plants. 

Outline

  We proposed a system using an organosilica membrane with excellent hydrothermal stability to recover steam from flue gas (see figure). In this system, 74 tons/day of highly purified steam is recovered through the membrane and the water, which condenses after latent heat utilization, is reused as water spray. The introduction of this system eliminates the need for external water supply, enabling operation even in areas without a large nearby water source. Additionally, since the flue gas after steam recovery contains less moisture, there is an expected secondary effect of no visible white plume (condensed steam) from the chimney. 

  A laboratory-scale test for steam recovery from simulated gas (containing steam, air, and hydrogen chloride) was conducted for over six months, confirming the hydrothermal stability of the organosilica membrane. This is the longest reported stability for steam above 150°C. Subsequently, a bench-scale organosilica membrane unit was tested in an operational waste incineration plant, demonstrating its capability to recover steam under real gas conditions. Based on the experimental data from lab and bench-scale tests, simulations revealed that recovering 74 tons/day of steam needed for spray water results in a net heat recovery (after deducting system power consumption) of approximately 200 GJ/day. This is equivalent to recovering about 70% of the waste combustion heat. 

  This research was published in Nature Communications.


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