How are sludges formed?

How are sludges formed?

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 may be formed from a combination of whatever suspended materials are in the water, including loose corrosion products, insoluble mineral precipitates and oil.

What is scale formation?

Scale formation is promoted by the presence of dissolved salts in a supersaturated solution. The precipitation of a crystalline substance from a solution onto the site of scale formation requires three simultaneous factors: supersaturation, nucleation, and adequate contact time.

What are the disadvantages of sludge and scale?

1. Decrease in Efficiency of Boiler : The excessive scale formation may cause clogging of boiler tubes which decreases the efficiency of the boiler. 2. Wastage of Fuel : Scale is a poor conductor of heat.

What are the scale forming substances?

Scaling is mainly due to the presence of calcium and magnesium salts (carbonates or sulphates), which are less soluble hot than cold, or to the presence of too high concentration of silica in relation to the alkalinity of the water in the boiler.

What are scales in Engineering Chemistry?

If the precipitation takes place in the form of loose/slimy precipitate, it is known as sludge. If the precipitation takes place in the form of a hard, adhering crust/coating on the inner walls of the boiler, it is known as scale. Sludge: It is a soft, loose and slimy precipitate formed within the boiler.

What is priming and foaming?

Bubbles or froth actually build up on the surface of the boiler water and pass out with the steam. This is called foaming and it is caused by high concentration of any solids in the boiler water. Priming may be caused by improper construction of boiler, excessive ratings, or sudden fluctuations in steam demand.

What is scale formation answer?

Most scale formations in boilers can be traced to the presence of hardness in the make-up water. This hardness reacts in the high temperatures environment within the boiler to form an insoluble scale. This insoluble scale coats the heat transfer surfaces, acting as an insulator to impede heat transfer.

What is meant by scaling?

Definition: Scaling is the procedure of measuring and assigning the objects to the numbers according to the specified rules. In other words, the process of locating the measured objects on the continuum, a continuous sequence of numbers to which the objects are assigned is called as scaling.

How do I remove scale from my boiler?

Scale is too hard to mechanically remove, and therefore is normally removed by acid cleaning. For one type of scale that is composed singly of hardness, it is practiced to take a method of dissolving and removing deposited scale by adding hydrochloric acid and heating.

What are scales and sludges How can scale formation be prevented by Calgon conditioning?

Calgon = sodium hexa meta phosphate The process involves the addition of calgon to boiler water. It prevents scale and sludge formation by forming highly soluble calcium hexa meta phosphate complex compound with CaSO4.

What are scales and sludges how are they formed?

What is scale example?

Scale is defined as a system or series of marks used for measuring or registering. An example of scale is what someone would use to figure out the length of something. An example of scale is what someone would use to find out how much they weigh. noun. 11.

What’s the difference between sludge and a scale?

Scale (verb) To scatter; to spread. Scale (verb) To clean, as the inside of a cannon, by the explosion of a small quantity of powder. Sludge (noun) Solids separated from suspension in a liquid. Sludge (noun) A residual semi-solid material left from industrial, water treatment, or wastewater treatment processes.

How are scale and sludge formed in a boiler?

Scale and sludge formation in boilers In boilers, water evaporates continuously and the concentration of the dissolved salts increases progressively. When their concentrations reach saturation point, they are thrown out of water in the form of precipitates on the inner walls of the boiler.

How does caustic embrittlement prevent scale and sludge formation?

As a result, the sludge and scale formation in boiler is prevented. Moreover, this treatment : (1) prevents the deposition of iron oxides in the boiler, (2) reduces the carryover of oxides with steam, and (3) protects the boiler units from corrosion by wet steam (steam containing liquid water). Caustic embrittlement is a type of boiler corrosion]

How does Calgon treatment prevent scale and sludge formation?

Calgon treatment prevents scale formation in boilers. Give reason. Addition of calgon (sodium hexa meta phosphate) to boiler feed water interacts with calcium ions in the CaSO4 forming a soluble complex, thus preventing the precipitation of scale and sludge forming salt. 2CaSO4 + Na2 [Na4 (PO3)6] Na2 [Ca2 (PO3)6] +