Chemical Water Treatment for Steam Boilers
Steam is used in many processes and anyone operating a steam boiler will know that keeping the steam raising system running is critical. No steam usually means no production. Of course, the steam is made by boiling water which sounds simple enough, so why do you need water treatment for your system? Water treatment is a general name given to a wide range of equipment and chemicals which are there to prevent problems and increase efficiency. The main problems found in steam raising systems are scale formation, corrosion and carryover
SCALE FORMATION – HOW DOES SCALE FORM?
The water coming into your site contains minerals. These minerals form a hard scale deposit when you boil the water – you will have seen this in the bottom of your kettle.
WHAT PROBLEMS DOES SCALE CAUSE?
Scale forms on the inside surfaces of the boiler causing a big reduction in heat transfer efficiency as the scale is thermally insulating. This means higher costs in energy for your steam boiler. Systems can even fail completely because they are damaged by overheating.
HOW DO YOU PREVENT SCALE FORMING?
Preventing scale from forming in the first place is of course the best strategy and its surprisingly simple – you install a water softener.
These come in lots of shapes and sizes from small domestic units to huge industrial systems, but they all work in a fairly simple way. They are very reliable and cost effective. Find out more here: https://columawater.co.uk/technologies
The steam boiler is made of steel and filled with boiling water, so it’s not surprising that corrosion is going to happen – steel goes rusty very quickly. The main strategy for reducing corrosion is to remove the oxygen from the water – no oxygen means no corrosion. Oxygen is removed from the water before it gets to the steam boiler by heating up the feedtank (or hotwell) to 80˚C. Any small amount of oxygen remaining is then removed by dosing an oxygen scavenger chemical to the feedwater.
The aim of the steam raising system is to produce steam – which is a gas made of pure water. Carryover means that water from the boiler has ‘boiled over’ into the steam system which causes many problems – the steam pipes will corrode, and the product may become contaminated. Carryover is avoided by preventing the TDS (total dissolved solids) getting too high. This is why the steam boiler must be ‘blown down’, reducing the TDS. Almost all systems now do this automatically, but its very important to check this system is working correctly every day.
Water treatment for your steam boiler system is an investment which will maintain efficiency and prevent expensive problems. Done properly, it will save you far more than it costs in fuel, water, repairs and downtime.