Scaling can sap energy, maintenance time
If some method can be found to control scaling, there is the potential to save energy and prevent equipment failure and reduce maintenance
Boil a kettle of tap water in a hard water area and two undesirable observations are made: A fine but harmless scum appears on the surface of the water and a hard white encrustation develops on the heating element. The latter is calcium carbonate and is usually referred to as limescale. The limescale that deposits on the heating element will, if untreated, reduce the efficiency of the kettle, induce corrosion of the element, and ultimately lead to appliance failure. However, it is not just domestic appliances that are affected; boilers and steam generators also develop limescale deposits, which will cause similar problems if left untreated.
Limescale can form wherever water is heated. The reason for the problem is that source waters (potable or ground water) contain dissolved mineral salts, sometimes described as hardness, which have low solubility in the water. When heated, the water can no longer hold these salts in solution and deposition must then occur.
What can go wrong?
Deposits are an insulting layer on heat transfer surfaces. This leads to more power being consumed or to the need to install heavier duty equipment to compensate. It is estimated that 40% more energy is needed to heat water in a system fouled with ¼-in. of limescale.
Scale in water lines reduces the available cross-section area and the throughput. Eventually the line will become completely blocked. Equipment then needs to be shut down for cleaning, and this costs money.
Safety valves or emergency process sensors (e.g., that operate deluge systems) may not operate in an emergency. Overheated boilers can be dangerous.
Stagnant conditions can develop in void spaces beneath deposits, and this encourages corrosion of steels and other metallic surfaces. The results can be fluid leaks and equipment failure, which is potentially dangerous. Scale surfaces are also excellent growth sites for bacteria, which can crate conditions hazardous to health (e.g., production of legionella pneumophila).
In order to establish if you have a problem, try answering these questions:
- Do appliances such as water-fed equipment contain white scale?
- Are there signs of unexpected deposit formation around valves or at the pipe outlets?
- Are boilers/heat exchangers performing below design?
- Is corrosion a problem in the plant?
- Is the water throughput less than expected?
The more times that the answer is "yes," then the more likely it is that you have scale.
Case Study Database
Get more exposure for your case study by uploading it to the Plant Engineering case study database, where end-users can identify relevant solutions and explore what the experts are doing to effectively implement a variety of technology and productivity related projects.
These case studies provide examples of how knowledgeable solution providers have used technology, processes and people to create effective and successful implementations in real-world situations. Case studies can be completed by filling out a simple online form where you can outline the project title, abstract, and full story in 1500 words or less; upload photos, videos and a logo.
Click here to visit the Case Study Database and upload your case study.
Annual Salary Survey
In a year when manufacturing continued to lead the economic rebound, it makes sense that plant manager bonuses rebounded. Plant Engineering’s annual Salary Survey shows both wages and bonuses rose in 2012 after a retreat the year before.
Average salary across all job titles for plant floor management rose 3.5% to $95,446, and bonus compensation jumped to $15,162, a 4.2% increase from the 2010 level and double the 2011 total, which showed a sharp drop in bonus.