Reverse osmosis membranes – How critical are they to your operation?
31 July 2018
High purity water is used in several industries such as pharmaceutical production and power generation, where reverse osmosis (RO) or nanofiltration plants are used to purify the process water. However, the integrity of the filter membranes is vital, so sampling procedures are required to monitor their performance. Bürkert aims to make this process quicker and easier with its latest sampling system solution.
Water filtration down to microscopic, or even Nano-levels, is a very important part of ensuring high water quality. In manufacturing businesses, such as pharmaceuticals, the reasons are obvious and such processes are carefully monitored to ensure continued compliance with statutory regulations.
Defining the need
In applications such as steam turbine driven power generation the water quality has a direct effect on the reliability and performance of the machinery. Any build-up of impurities on turbine blades for example can eventually lead to an imbalance of the rotor, which will result in a lengthy overhaul process and considerable lost production time.
Monitoring water quality traditionally involves testing samples that are manually taken from filtered water lines and processed in a laboratory. Provided the filter membranes are intact, the water samples should provide no cause for concern. However, if a membrane is leaking, it is not immediately apparent that there is a problem.
Typically, as a membrane begins to fail, the increase in impurities is a gradual process and this is something that would not be noticed by measuring pressure differentials across the membrane. Furthermore, pressure sensors are normally only located at the outlet of the RO train, rather than at the end of each RO tube.
Depending on the number of filtration units and the number of staff available for the task of sampling, this process may only be carried out weekly in some cases. Some applications such as power generation will be able to withstand increased impurities, while others like injectable fluids for pharmaceuticals will need to be stopped immediately and the system completely flushed before production can restart.
By measuring water quality frequently, it is possible to build up an accurate picture of water quality and see even the smallest drop in standards. This enables a proactive approach to be taken with regard to replacing the damaged membrane, ensuring that it is changed at the most opportune time.
Creating the solution
Recognising a need for improved sampling frequency and data recording, Bürkert has developed a sampling system that checks membrane integrity and can issue alerts as well as isolate damaged membranes from the larger process. As expert designers of fluid control systems, Bürkert has considerable knowledge in this field and has used a combination of its own products to create a sampling system that can be tailored to individual applications.
Based around a pre-assembled cabinet that contains a Bürkert valve island and the HMI controls and display, the sampling system can be arranged to collect data on one, or several, parameters such as turbidity, conductivity, chlorine and pH. Sampling intervals can be adjusted to suit the application, with the system being flushed with purified water after each cycle.
With pre-set alarm points for each parameter being tested, the system will automatically re-test the sample water that has exceeded a threshold value to confirm the readings. Once confirmed, the sampling system can be set-up to issue alerts and operate shut-off valves that can isolate the damaged membrane from the rest of the system, allowing the production process to continue.
The system can be designed as a stand-alone unit with a plug-and-play control module or it can be delivered as a hardware bundle that can be integrated into the process infrastructure. To accommodate this, the communication systems are flexible with Bürkert offering Profibus DP, Profinet, CAN open, Device net, Fieldbus AS Interface and Interbus protocols to suit almost every industrial setup.
The speed and increased frequency of testing delivered by this system offers considerable benefits to businesses that operate reverse osmosis and Nano filtration units. Productivity can be maintained, even in the event of a membrane failure and test data is retained for trend analysis and audit purposes. Automation of this crucial process has the potential to make significant savings for industries that rely on high quality process water.
For more information, please contact:
Bürkert Fluid Control Systems
Fluid Control Centre
1 Bridge End
Tel: +44 (0)1285 648720
Fax: +44 (0)1285 648761