An innovative steam boiler water treatment technology from Spirax Sarco uses reverse osmosis (RO), in a process the company says enables healthcare steam users to achieve 'a step-change' in energy efficiency.
Spirax Sarco explained: “RO is a robust, chemical-free technology that uses semi-permeable membranes to deliver purified water to boilers and clean steam generators. It can strip out between 98 and 99% of the total dissolved solids (TDS) in the feed water, slashing the boiler blowdown rate to less than 1%, and knocking between 1 and 3% off fuel bills.
“Where conventional RO water treatment systems reject approximately a third of the water that passes through them, Spirax Sarco’s unique zero-loss systems use an innovative approach to eliminate virtually all waste water. This alone saves typical steam users 2-3% of fuel costs.”
Combined with other savings, such as reducing the need for chemical water treatments, Spirax Sarco RO systems will reportedly usually pay for themselves in well under a year, and sometimes in six months. Elsewhere in the steam system, RO is said to help cut down on plant outages by reducing corrosion in the condensate circuit caused by the build-up of carbonic acid, provided that it is used with the right complementary treatments.
But what is RO? Spirax Sarco said: “Osmosis is a natural phenomenon that controls the flow of fluid across a semi-permeable membrane barrier. It balances the flow of fluid and nutrients across every cell wall in our bodies, for example. With RO a pump is used to apply pressure and force the natural process into reverse. The pump effectively forces a concentrated stream of salts through a membrane into two streams. One stream is the reject stream or concentrate stream, and the other is the sought after pure water (permeate) stream. RO is a safe way of producing pure water because it doesn’t need the acid or caustic regenerants used in conventional demineralisation plants.”
RO systems comprise a pressure pump, housing, and membrane. Water is pumped into the RO system under pressure and the pure water (or permeate) is forced out, directly into either a hotwell or permeate holding tank. In steam applications, the boiler or clean steam generator would be the next stop. The biggest cost of running an RO system is the energy needed to pump the water, so Spirax Sarco uses optimised, composite membranes and smaller, more efficient pumps that minimise the pumping energy needed.
Anyone concerned that introducing a new technology might involve adding substantially to their maintenance burden can, Spirax Sarco says, “stop worrying”. It said: “Provided that the water entering the RO system is properly treated, the robust membranes are very low maintenance, and, if they are damaged, they are easy to replace.”
To find out how a Spirax Sarco RO system can bring you significant energy savings and other benefits, visit www.SpiraxSarco.com/uk, or telephone 01242 535390.
