Industrial boiler water: close monitoring and proactive treatment protocols are critical
As water treatment is a critical aspect of industrial boiler management and potentially one of the greatest operational risk points, AES relies on close partnerships with third-party industrial water treatment specialists – which act as important safety nets.
“We engage with companies that stand behind their treatment programmes, check these are continuously working and – if any adjustments are needed – provide detailed technical information. They are the ‘eyes and ears’ of boiler water system health,” explains Dennis Williams, Commercial Director of specialist steam and boiler operations and maintenance service provider, Associated Energy Services (AES).
Troubled water
The calcium and magnesium content of municipal water makes it hard and unsuitable for use in boilers. Typically, a water softener – an ion exchange resin bed which uses salt to remove the calcium and magnesium and replaces these with sodium – creates boiler-friendly, soft water.
The deposition of hard calcium or magnesium scale prevents heat transfer. As a layer builds up, it becomes increasingly resistant to thermal energy transfer and decreases energy transfer into the boiler water. Efficiency drops, boilers must run harder – consuming more fuel.
Poor heat transfer also raises the risk of developing hot spots on tubes, in corners, crevices and wells. Higher operational temperatures within these thickened areas could impact boiler material metallurgy, causing tube leaks, failures, cracking and propagation.
Organic contamination – especially of condensate returned for reuse and heat recovery – is another consideration, according to Williams: “It is important to treat hardness and organic compounds. Oil leaks are a major risk. In food manufacturing, a leak in a heat exchanger or a coil could result in residue being sucked into the lines, ultimately contaminating the boilers. There have been instances where sugar has leaked – which is very detrimental if it gets into the water side of the boiler.”
Williams points out that organics can also cause foaming. This results in priming (the carry-over of water into the steam lines), which is also potentially dangerous: “Slugs of water are pushed by steam from behind. If there is a sudden, 90 degree turn in a steam line, valve or a reducer, that high-speed slug of water smacks into it – and could damage, rupture or destroy the line. A damaged main steam line could potentially shut down a manufacturing facility.
Wet steam can also compromise product quality. For example, food manufacturers find the ordinarily safe food-grade chemicals pose a problem: “Steam should evaporate, leaving a very small trace element of chemicals. However, with wet steam, concentrations are a lot higher. When operating a canning plant, wet steam could mark cans or cause corrosion,” Williams explains.
High chlorine levels in boiler make-up water add a further complication, he notes: “Chlorine degrades the ion exchange capability of the resin beds treating hardness. You have to add a filtration process before the water softener to capture excess chlorine.”
Dead in the water
AES and its industrial water treatment partners have encountered a wide variety of boiler water treatment-related challenges. A client in the food industry, for example, encountered severe challenges after caustic soda was introduced into a reverse osmosis plant, risking caustic embrittlement and necessitating costly adjustments and repairs.
In another example, a water tube boiler was damaged by untreated, hard concentrate return: “The client was repeatedly asked to dump or divert rather than reuse the contaminated condensate, but no action was taken. When we took the boiler offline and inspected it, significant repairs were needed. Unfortunately in this instance – as the client elected not to invest in the required repairs – the asset was mothballed, and effectively lost due to poor water treatment.”
Scaling in between boiler tubes due to water hardness is another common issue, says Williams: “Water space is blocked up and boiler output capacity is affected. If this is quickly noticed, online descaling can be actioned – or alternatively, an acid wash to dissolve the deposits may need to be carried out. However, the resulting acid waste solution must be disposed of in an environmentally-friendly manner, which is costly. We warn clients to avoid these situations at all costs.”
Testing the waters
Williams advises testing and closely monitoring boiler water quality, to pinpoint potential problems so that these can be mitigated before becoming catastrophic.
“One can only really tell how successful the water treatment is when the asset is taken offline. On a fire tube boiler, we now use cameras to see in between the bundles. On water tube boilers, we also rely on cameras placed in the mud and steam drums to do inspections. However, because these are only done periodically – it is critical for water to be managed properly in between.”
The majority of boiler water testing is done manually – as fully automated systems are expensive, unreliable and require frequent calibration. In AES’s key performance indices, soft water tests on boilers are key: “We do multiple tests per shift, per boiler, per site and per day, 24/7 for 365 days a year while these assets are operating. Boiler operators are specially trained, and this is a key part of the course-work for a certified AES qualified boiler operator,” Williams notes.
Partners in water treatment
Williams says that AES expects its water treatment service providers to issue fortnightly reports after visiting sites. Their technical capability is critical – and they must be interested in what is happening, be safety- and quality-focused – and engage on an intensive, value-added level.
AES also expects its water treatment partners to deal with emergencies, monitor chemical levels on site for dosing, do spot checks and – if there is an issue with chemicals or they run out – to replenish chemicals and clear containers.
“Furthermore, we believe it is important to partner with proactive water treatment experts in order to remain abreast of new technology, formulations and developments in the pivotal area of industrial boiler water treatment,” Williams concludes.
