AdVE > The Technology of AdVE
Terrabon's AdVE technology provides an innovative new way to desalinate brackish and salty water.
Developed as a by-product of the MixAlco fermentation broth dewatering process, AdVE's technology successfully integrates an efficient compressing device and heat exchanger design, resulting in a very high heat transfer coefficient. Texas A&M University holds patents on this heat exchanger design and the process integration for AdVE, both of which it has licensed to Terrabon.
Mechanical vapor-compression seawater desalination systems are commonly operated at temperatures below 80°C; however, AdVE employs a system operating at 172°C. This higher operating temperature delivers important advantages:
- A lower amount of compression work is required.
- A smaller latent heat transfer area is needed, and
- A smaller, less costly compressor can be used.
AdVE™ employs a novel, low-cost latent heat exchanger that allows the use of low temperature differentials, thus reducing energy requirements. The compressor pulls vapors from the low-pressure side of the evaporator, compresses them, and returns them to the high-pressure side where they condense and supply the latent heat needed to evaporate more water from the low-pressure side. The heat is recycled, thus enabling a more efficient, cost effective process.
Injecting water into the compressor allows the compression to be nearly isothermal, which makes the compressor more energy efficient. Conventional centrifugal compressors do not allow water injection because the high-speed blades can be damaged from the impact with the droplets. In contrast, a gerotor positive-displacement compressor operates at lower speeds and has robust components that can tolerate liquid injection. The gerotor compressor is less expensive, it can be easily sized to the specific compression needs, and it is more efficient over a wider range of operating conditions.
Multi-effect mechanical vapor compression requires removal of non-condensable gases to avoid their accumulation in the heat exchanger. Accordingly, AdVE requires the feed water be de-gassed before processing. Fouling in the heat exchanger is also mitigated by using an ion exchange and other treatments of the incoming feed water to remove sulfate and carbonate ions. In the event that fouling does occur in the heat exchanger, there are existing commercial solutions, such as the introduction of abrasive material, that are able to safely and economically remove it.
For more efficient operation of AdVE, several stages are configured in a train that operates at successively lower pressures and temperatures. Steam from the high-pressure side of the heat exchanger boils water from the low-pressure side of an adjacent heat exchanger. The high-pressure or steam-side of the heat transfer is a significant part of total resistance; thus, increasing the steam-side heat transfer coefficient can measurably improve overall system performance. The design of the plates used in AdVE provides significantly higher heat transfer coefficients than other available heat exchanger designs.
MixAlco™
AdVE™
SoluPro™