Posts Tagged ‘corrosion’

Could you save $1,000,000 a day?

June 23, 2014

Few companies can afford to have plant outages that could lead to losses of a million dollars a day, yet that is what is at risk if you fail to monitor your boiler chemistry correctly.

It all comes down to contaminants. A 500 megawatt boiler boils off around 1,500 tons of water an hour, around one million tons per month. Boiler feed water contains contaminants that are very hard to eliminate. And when this water boils off, these contaminants are left behind, causing a host of potential problems for your boiler.

Poor efficiency, corrosion, leaks, cracks and ultimately failed components can all result.

Close monitoring and control can determine the best time for boiler blowdown operations to bleed off a measure of the contaminated water. This helps to prevent scale deposits from insulating the heat surfaces, which can decrease the rate of steam generation and cut operating efficiency.

Clearly, it pays to keep an eye on boiler chemistry. As well as the need to replace failed components, a shut down boiler does the rest of the plant no favours either, with critical processes reliant on steam unable to operate.

But it’s not just the water in the boiler that needs attention. Keeping a check on the steam distribution loop and other areas around a power plant gives a complete overview of conditions. With the data to back up a planned maintenance programme, you can keep outages to a minimum.

So, what are the key things to measure? Well, one of the important ones is dissolved oxygen, a major cause of corrosion in steam systems. Oxygen contamination of steam condensate can lead to inefficient or improper feed water aeration, air leaking into pump seals, receivers and flanges, leaking heat exchangers and air getting into systems that should be a vacuum. Localised pitting corrosion is another danger. This can be particularly hazardous, as it can cause critical equipment in the steam system to fail rapidly.

A cure for this is adding hydrazine, which removes oxygen and has several other benefits. Ensuring the right amount is added gives all the benefits without unnecessary expense. The level of sodium and silica are two other parameters that need close attention, as both these chemicals can have undesirable effects.

So, keeping an eye on your boiler’s chemistry is number one on any boiler operator’s to-do list, as making sure your boiler has the right chemical balance could help you keep your books balanced.

Over the coming weeks, we will explain more about the importance of boiler chemistry monitoring, including tips on where to monitor and how to ensure effective measurements of hydrazine, sodium and silica levels.