What is the priming and foaming?
Priming is the carryover of varying amounts of droplets of water in the steam (foam and mist), which lowers the energy efficiency of the steam and leads to the deposit of salt crystals on the super heaters and in the turbines.
What are scales and sludges?
If the precipitation takes place in the form of loose and slimy precipitate, it is called sludge. On the other hand, if the precipitated matter forms a hard, adhering crust/coating on the inner walls of the boiler, it is called scale.
What is foaming in Engineering Chemistry?
Foaming is the continuous formation of bubbles which have sufficiently high surface tension to remain as bubbles beyond the disengaging surface.
What are the boiler troubles explain in detail?
Boiler troubles: Sludge, scale, priming and foaming, caustic embrittlement, boiler corrosion are collectively known as boiler troubles. It is the intercrystalline cracking of boiler due to Na2CO3. In high pressure, Na2CO3 undergoes hydrolysis to produce NaOH.
How does foaming occur?
A foam is produced by trapping millions of tiny gas bubbles in a liquid (whipped egg white) or a solid (marshmallow). Whisking water and air produces hundreds of bubbles but they soon ‘pop’, leaving only water and air again.
What is priming in centrifugal pump?
What Is Pump Priming? Priming simply means preparing or getting something ready for operation. For a centrifugal pump to work properly, you need to fill it up with water. When everything is right, a standard (non-self-priming) centrifugal pump looks like this. The pump will resume operation once the air is removed.
What is Calgon conditioning?
Calgon conditioning involves the addition of Calgon or sodium hexametaphosphate to boiler water. this substance interacts with calcium ions forming a highly soluble complex and thus prevents the precipitation of scale-forming salt.
What is the basic difference between sludge and scale?
1 Due to heating, the salt containing water will get concentrated and changes into loose and slimy precipitates called sludge. 1 When these precipitates becomes hard and adherent called scales. 2 Sludge is not harmful for boiler. 2 Scales is harmful for boiler.
What is priming in chemistry?
Priming is the process by which contamination in water droplets leave the boiler with the steam during heating. Priming can either be caused by mechanical factors such as: Construction of the boiler. High water level.
What is foaming technique?
The chemical foaming process can be undertaken by two methods. The first method is as follows: A blowing agent is added to a molten polymer and is decomposed to release gas. Then, the polymer is foamed by pressuring and heating, as shown in Figure 4a.
What is priming in boiler?
Priming (foaming in North America) is a condition in the boiler of a steam locomotive in which water is carried over into the steam delivery. It may be caused by impurities in the water, which foams up as it boils, or simply too high a water level.
What is degree of hardness of water?
Degree of hardness is defined as the number of parts of calcium carbonate or equivalent to various calcium and magnesium salts present in a million parts of water by mass. It is expressed in ppm. 24 mg of MgSO4 present in 103 g of water106 g water will contain =24000 mg of MgSO4=24 g of MgSO4.
Why is priming needed?
The main objective of priming a pump is to remove the gas present. So, if the air or other gases present inside the pump casing and suction line, it must be primed before starting. But if the pump suction line and the casing are already filled with liquid during start-up, priming is not required.
What is sludge formation?
Sludge is a water-formed sedimentary deposit which may include all suspended solids carried by the water and trace elements in solution in the water. Sludge reduces heat efficiency and may cause scale formation in boilers and heat exchangers.
Why Calgon conditioning is better than phosphate conditioning?
Answer. In calgon Conditioning, the added calgon forms soluble complex compound with CaSo4, thereby it prevents the scale and sludge formation in water. this soluble complex does not cause any problem in boilers.
How is foaming caused?
A foam forms when small bubbles of gas are trapped in a solid or liquid. How is a foam produced? A foam is produced by trapping millions of tiny gas bubbles in a liquid (whipped egg white) or a solid (marshmallow).