POOR boiler water treatment is the primary cause of poor boiler performance, according to Chris Paterson, MD of specialist operations and maintenance service provider to the steam and boiler sector, Associated Energy Services (AES).
Not all water is created equal and there is a lot more to water treatment than ensuring that it appears clean, he says. Yet, this is where many companies are tempted to cut costs.
However, because correctly treated boiler water is integral to preventative maintenance and essential to ensuring boiler safety – as well as operational and energy efficiency – this is one of the first and most critical issues that AES addresses when taking over the operations and maintenance of a client’s boilers and energy plant.
A drop in water standards
Poor infrastructure has reduced municipal water quality – while the increased cost of this water source has persuaded many companies to switch to alternative streams such as borehole water and stored rainwater – creating a whole new set of challenges, says AES operations director Ray Lund.
“Each of these streams has different properties. Hardness levels (how much calcium and magnesium is in the water) and total dissolved solids (TDS) need to be considered. When using borehole water, the iron and silica content need to be checked. Furthermore, boiler water should be thoroughly tested over time to see what is in it – and to check the variability of the various contaminants – so that one can design and install appropriate treatment equipment and technology,” Paterson advises.
According to Lund, the quality of water going into a boiler has two direct impacts: the first on the life of the boiler and the second on its heat transfer capacity and efficiency – which affects the overall energy plant management.
Clarifying boiler water treatment
Using the analogy of a domestic kettle, Lund explains that compounds such as calcium and magnesium form a hard scale which adheres to surfaces. This limits the transfer of heat from the fire side of the boiler to the water side, making the boiler inefficient when it comes to the production of steam.
However, this does not happen immediately. Paterson warns: “Poor water treatment damages boilers over long periods. Water does not go off specification in one day.
Therefore, water treatment needs to be done correctly and consistently, every single day. Unfortunately, this is what many manufacturing and processing facilities miss.”
Lund notes that the relationship between on-site boiler operators and water treatment companies forms a strong foundation for a watertight boiler water treatment strategy.
At the beginning of the process, solids are removed via different forms of filtration. Plants with very high TDS might require the installation of a reverse osmosis (RO) plant which can be a very effective energy-saver, as it requires fewer blow-downs of the boiler to clean it out.
“Typically with municipal water supply, the TDS is low, so we proceed directly to a softener. However, there are some areas in the country where the water is very hard. We look at various technologies to identify the most cost-effective way in which to manage that over the long term,” says Lund.
PH control is always critical, and must remain within the right parameters to facilitate the formation of a protective layer which protects the internal surfaces of the boiler.
For more information: https://www.aes-africa.com/
