Power Generation-Energy from Waste Industry
Feed water quality is of paramount importance in all aspects of steam raising plant at whatever operating pressure and even more so in the power generation industry.
The levels of certain contaminants has to be kept at extremely low levels to ensure steam purity limits are not exceeded and to ensure that damage to heat transfer surfaces and turbines does not occur.
Such systems come under standards such as ISO BS EN 12952 (Water-in-tube) and BS 12953 (Water-in-Shell) as well as BS2486:1997. The higher the operating pressure the more exacting the requirements.
Traditionally to get high purity water twin bed demineralisation plants with final cation polishing or complex mixed bed regeneration systems have been employed with all the complex handling issues that result, with the need for acid and caustic regeneration chemicals coupled with safe means of disposal after neutralisation.
If there is an imbalance in the regeneration sequence there can be unforeseen consequences and potential equipment damage.
With modern Reverse Osmosis plant coupled with continuous electro-deionisation (CEDi) it is possible to achieve and exceed the quality of water that might be expected from a traditional demineralisation plant.
In fact, it is possible to achieve in some instances the quality of water that is required by the used of selected membranes only in either single pass or twin pass mode without the need for continuous electro-deionisation.
Using twin pass RO as a pre-cursor to continuous electro-deionisation can in fact reduce the ionic loading onto the CEDi module and if in the unlikely event of one RO stream breaking down can allow the system to continue to run without taking it off-line.
The system has been installed for 3 years and is in continuous operation. The level of confidence in the system is so high that the old back up demineralisation plant has been decommissioned and removed.