A water softener removes hard water minerals, like calcium and magnesium, which can cause scaling and damage in the boiler tubes,” explains Lionel Maasdorp, MD at Allmech, a South African manufacturer of boilers and supplier of water treatment components.
“Cooling towers are another common application for industrial water softeners. They can operate much more efficiently with softened water. This can help to realise a drastic reduction in maintenance requirements, chemical feed quantity, and the volume of water required for operation. The correct balance of minerals of incoming water to industrial systems is essential to the proper operation and maintenance of expensive equipment.”
While Lionel says water softeners are fairly low maintenance equipment, he recommends regular service visits are carried out to ensure that they are operating optimally.
How softeners work
Water softeners use a process called ion exchange to soften the incoming raw water. The process involves the transfer of unwanted hard ions, such as Calcium (Ca+) and Magnesium (Mg+), from the water to a solid substance that accepts these (the resin), and exchanges the ions for a desirable type of ion. Water softeners usually use sodium (Na+) as the exchange ion. Sodium ions are supplied from dissolved sodium chloride (salt). As hard water passes through a softener, the calcium and magnesium trade places with sodium ions.
“Every softener has a bed of resin, which extracts the hardness in the water by capturing the calcium and magnesium ions that cause hardness,” explains Lionel. “After a while, the resin bed becomes saturated with these hardness-causing minerals, and there comes the need for ‘regeneration’. Softener regeneration is simply the process of removing the minerals or ions absorbed from the resin beads in the water softener.”
The regeneration cycle, which restores the exhausted resin capacity consists of four steps: backwashing, brine rinsing, slow rinsing and fast rinsing.
“Water softeners must regenerate regularly to function properly. While some softeners regenerate daily, others may regenerate once or a few times a week, and some may regenerate just once in two weeks. The frequency of regeneration depends on the volume of the tank, water usage, and hardness of the raw water.”
Key maintenance considerations
When it comes to onsite water softener maintenance, it’s important to check the salt level in the brine tank regularly, and to use the right kind and quality of salt.
“You also need to eliminate what we call ‘salt bridges’ in the brine tank. This is when a hard salt crust develops, which means there’s a barrier between the water and salt which stops the salt from dissolving properly, often because the salt has been thrown directly into the brine tank without the bag,” says Lionel. “Keeping the brine tank clean of mud, build-up or debris at the bottom of the tank is important to keep it operating efficiently.”
He advises that users ensure the automated, semi-automated or manual softener control valve is operating correctly by regenerating the water softener as per its technical specifications.
A planned maintenance programme will ensure that problems are avoided or managed quickly as they arise. It is important to select the correct type of treatment plan to suit the operation’s needs. “At Allmech, we offer our customers a monthly maintenance service, which includes all the aspects required to keep their softeners functioning optimally.
“The pre-treatment system is the most critical part of the total boiler water system, as it ensures water impurities are either removed or reduced to acceptable levels,” Lionel concludes. “Taking proper care of the softener is the best way to protect your investment in boiler or cooling tower equipment.”