Calcium Carbonate (CaCO3) is one of the most common scales in oil field operations. Various fluids (brine, oil and gas) can mix in the reservoir and/or wellbores under drastically varying sets of thermodynamic, kinetic and hydrodynamic conditions that will affect the carbonate scale forming tendencies.
What is scaling in RO plant?
Scaling means the deposition of particles on a membrane, causing it to plug. It is an unwanted effect that can occur during nano filtration and Reverse Osmosis processes. Scaling causes a higher energy use and a shorter life span of the membranes, because these will need cleaning more often.
What is scaling in water?
Scaling occurs when water has high levels of minerals like calcium carbonate, which can build-up on surfaces. Slight scaling can be considered beneficial in that the inside surfaces of metal pipes become coated with harmless minerals that act as a barrier to corrosion.
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 scale formation?
Disadvantages of Scale formation (1) Wastage of fuel : Scales have a poor thermal conductivity so the rate of heat transfer from boiler to inside water is greatly reduced. In order to provide a steady supply of heat to water, excessive or overheating is done and this causes increase in fuel consumption.
What are the reason for the formation of scale?
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 is scale and sludge formation?
Water in boiler is continuously heated causes the increase in the concentration of dissolved and suspended solids. The precipitation in the form of soft loose and slimy deposits (sludge) The precipitation in the form of hard deposits, which are sticky on the walls.
How can scale formation be prevented?
Operation at elevated pH will also reduce the potential for the formation of silica scale. The most cost effective method for preventing scale formation (where applicable) is injecting a scale inhibitor....Preventing Scale Formation in Reverse Osmosis Systems
What are the causes of scale and sludge?
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.
What are the disadvantages of scale and sludge?
Disadvantages of Sludge: Sludges are poor conductors of heat, hence there is wastage of portion of the heat generated. If sludges are formed along with scales, then sludge gets entrapped in the scales and both get deposited as scales. Excessive sludge formation disturbs the working of the boiler.
What are the disadvantages of boiler scales?
Disadvantages of Scale formation (1) Wastage of fuel : Scales have a poor thermal conductivity so the rate of heat transfer from boiler to inside water is greatly reduced. This causes distortion of boiler tube and also makes the boiler unsafe to bear the pressure of the steam, especially in high-pressure boilers.
What is the difference between sludge and scale Why are they harmful to boiler operation?
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.
Does magnesium cause scaling?
Dissolved calcium and magnesium salts are primarily responsible for most scaling in pipes and water heaters and cause numerous problems in laundry, kitchen, and bath. Hardness is usually expressed in grains per gallon (or ppm) as calcium carbonate equivalent.
What is the difference between boiler scale and sludge?
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.
Why a crusty boiler scale is formed in boilers when hard water is used?
A crusty ‘boiler scale’ is formed in boilers, when hard water is used because insoluble CaCO3 or MgCO3 is formed in large scale which gets deposited as crusty ‘boiler scale’. Its formed when bicarbonates of calcium or magnesium are converted into carbonates.
What are the disadvantages of using hard water in boiler?
Hard water that’s filled with minerals like calcium and magnesium can cause damage to the tubes inside water boilers. If these minerals are present in the boiler’s water supply, it can lead to limescale forming on the surface of the tubes, which has the potential to cause overheating and tube failure.
How do you flush out a boiler?
Switch off the boiler when the heat reaches to about 45°. You should do reversing the flow of the power flush in every ten minutes. Close all other radiators, but except one to allow through, repeat the same process with all other radiators. Open all of the radiator valves and allow the flush to flow freely.
What is the cause of foaming in the boiler?
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. When this boiler water carryover is excessive, steam-carried solids produce turbine blade deposits.
What causes foaming?
Foam can be formed when the physical characteristics of the water are altered by the presence of organic materials in the water. The foam that appears along lakeshores is most often the result of the natural die-off of aquatic plants.
