Classification of Desalination Technologies
Desalination technology is used by humans since thousands of years. Being in the desert surrounded by sand and rocks or being on the sea sailing through salty waters, always fresh water is needed every day to keep the human body in a balanced hydrate mode.
Nature started using desalination processes from the very first moment. Different concentration levels drive everything alive on our planet. Humans started using first evaporation and condensation processes to purify unusable water. In the last century the number of processes to desalinate water and other liquids has gone through a very big development. New processes have been found, existing processes have been improved.
Overviewing all known desalination processes of today we may find a large number in a lot of science areas. In order to give this convolute of technology a systematic structure a larger group of desalination experts and scientists developed a Classification of Desalinaiton Technology (CDT) system.
This Classification of Desalinaiton Technoogy system is based on the natural working principles of chemistry, physics and biology. It starts as low as electrochemistry and nuclear physics. From here on it is building up its structure. Under the five main science fields 20 subordinated science areas have been found describing all natural working principles in desalination systems.
In order to structure all known desalination technologies a general structure was build up to the Classification of Desalinaiton Technology system (CDT):
The first classification level does divide in transient phase and stable phase technologies.
The second level classes represent the separation processes of desalination technologies.
The third level classes show the main technology, in some cases without further structure.
The fourth level classes are split in advanced sub-desalination technologies.
In total there were 51 desalination technologies found and classified inside CDT.
As of today the used technologies mainly are Multi-Stage Flash and Reverse Osmosis they can be found within the structure at the third level.
Everybody is free to make use of this CDT but is asked to make a reference to DME GmbH on behalf of all people being involved, please.
We will keep developing CDT and you are free to participate in this discussion!
(more details LINK)
Future Desalination Technology
Saving material and energy per ton of water produced is the main target of all developments in desalination. Due to this basic attempt every of the today known technology has to prove its benefits against the established ones. Not pointing out every new technology three of them are selected and briefly described at this stage (2017).
Obviously an idea for a technology needs to develop. On the right hand side you can see an overview of different technologies. This sketch does illustrate the state of science knowledge and in the same way the state of Development, Technology and Art.
Legend: State of science knowledge values
0 Very high, 1 High, 2 Medium, 3 Low, 4 Very low
In this context DME does illustrate some of the know how build up and some of the support given so far in this field of activities preforming. In order to classify the development of a technology DME did introduce the
– Desalination Technology Development Benchmark –
also called “DesTeDeBe”. You will find more details “here (LINK)”
Some of the latest developments in technology are now benchmarked here. In order you want to know more, please get in contact with DME.
(LINK)
Multi-Stage Flash (MSF)
Multi-Stage Flash (MSF) evaporation desalination plants are based on flash evaporation in a cascade of stages (effects) at different pressure levels. In the brine-recirculation mode, the brine is recirculated through the system.
In the last stage of an MSF plant, the heated feed water is led into the pressure vessel where it partially evaporates in a flashing process due to the pressure decline. The vapour is used to preheat the feed water. The part of the brine that does not evaporate is sucked into the next stage which has a lower pressure. There, the same flashing and evaporation procedure takes place again, but at lower pressure and thus lower saturation temperature.
In this way, the feed that is used to condense the steam at every stage from the lowest pressure at the first stage to the highest pressure at the last stage is heated up continuously. The result is a low mean temperature difference between the feed water and the condensing steam, although the heat transfer is of type latent-sensible. Thus, the exergy losses are low.
The circulation of the brine mainly reduces costs for pre-treatment, but also reaches higher operation flexibility and better thermal efficiency. At the same time complexity and costs for components, construction, and maintenance rise.
(LINK)