All boilers, especially the popular fire-tube and water-tube boilers, are used to heat water (or other fluids) to very high temperatures to produce steam. The steam (a dry gas) is used for various purposes – power generation, sanitation, central heating, cooking, etc. This is obviously quite a prolonged process which runs for hours on end – and is not without imperfections.
Anyone who knows anything about boiler tubes know that with use comes with issues with particle deposits inside the pipe. Over time, these sediments shield the water from the heat generated from the fuel. Consequently, more fuel would be needed to achieve the temperature required to heat the water. This results in an overall inefficiency and, eventually, failure of the system.
Knowing this, the importance of boiler tube cleaning cannot be over-emphasized. You must carry out regular cleaning if you hope to run an efficient boiler and spend less fuel doing so. It is quite common to find people quickly turning to chemical cleaning as a solution. This is not a bad solution to this problem. However, it is one thing to know that it is important to clean out your boiler; it is another thing to know when to clean your boiler chemically. Here are a few instances were chemical cleaning is suitable:
- In instances where certain under-deposit corrosion process such as hydrogen damage has resulted in failures, you can use chemical cleaning to get rid of deposits to forestall any more damage to the pipes.
- When there is a contamination event, whether major or minor, chemical cleaning is required to remove the deposits and the contaminants underneath it as well.
- When more than 10% of the boiler’s tubing is being replaced, chemical cleaning is required to maintain a consistent layer of oxide.
- When implementing significant modification in your boiler of its system. These changing could be switching the type of fuel used or modifying the burners. To get your boiler to function optimally after such a change, it is important to chemically clean it out.
Other Boiler Cleaning Methods
Although chemical cleaning is a practical and effective method for getting rid of slag, ash, and other tube deposits, there are other methods that are equally effective in their own right. Each of these methods is very effective in certain situations and for different states of the deposits they help remove.
Acoustic Cleaning Method
As the name already suggests, this is the use of sound to “shake off” particle deposits such as ash from the boiler tubes. This is popularly done using acoustic horns that are post-installed on the boiler. Acoustic cleaning is very effective for dry particles like ash which means it would not be effective for super-heaters. It is a safe method which can be operated online i.e. while the boiler is running without damaging the boiler in any way.
The method involves the use of water at very high pressure (1200 gallons per minute or more) to remove slag deposits from boilers. Water lancing is effective where acoustic cleaning isn’t because it can deal with both dry ash and slag. It employs the use of high-powered, high-volume hydroblast apparatus and can clean slag up to 40 feet into the tube. You can check here to know more about hydroblasting.
The trick thing about water lance is whether it can be used online. Yes, this is very possible but also very precarious and delicate process. It would be quite dangerous to spray water onto the boiler while it is operational. And so, online cleaning should only be performed by highly experienced individuals. This also depends on the type of boiler being cleaned. Water lances may not be practical, or even safe, for some other types of boilers.
In boilers that are designed in such as a way that water lances may be ineffective or dangerous, soot blowers could come in handy. Soot blowers are equipment that uses compressed steam or air to prevent slag from building up in the boiler. The best thing about soot blowers is that they can keep the boiler clean without the need to shut it down. There are four types of soot blowers: Insertable Rotating (Wall blowers), fixed rotating, Air heater blower, and the Insertable kinetic (Long Retractable Soot Blower). Go here to read more about the comparison and selection of different types of soot blowers. Soot buildup can cause problems for boilers such as soot fires which can create localized hotspots in the tubes. These localized hotspots weaken the tube material over time and would eventually lead to boiler failure. The soot removed from the tubes is blown out by the flue gases, or can be trapped if the blower has a soot collector. Many boilers have soot blowers preinstalled in them at the time of their manufacture. However, soot blowers can be retrofitted onto boilers that do not originally have one built into them. Thanks to growing advancement in technology, there are now intelligent soot blowers that are designed to initiate a cleaning process when soot builds up to a certain level in the boiler.
As explosive as this method may sound it is not so novel. It is a fairly old method that is still being employed by a good number of plant operators. This process uses explosives such as dynamite to remove slag from the tube of boilers. This method is time-efficient and convenient. It is also very useful for boilers where the use of water is either dangerous or not possible due to the lack of water. Although this method cannot be used online, but it could help save water that would have been used to clean the boiler tubes. You can learn more about explosive cleaning in this report https://www.epri.com/#/pages/product/1022262/.
Carrying out regular cleaning of boilers is extremely important to maintain optimal operation and prevent boiler failure. Boiler cleaning can improve its efficiency by 1% to 4%. It is also very crucial to know when to do this and what method is most suitable. Every plant operator should assess their unique situation and figure out what cleaning method will save them the most time and resources without damaging the boiler. You can go to this link to know more about boiler maintenance: https://www.powermag.com/boiler-chemical-cleaning-doing-it-correctly/