To prevent scale formation
There are two ways to prevent formation of scale.
- Eliminate or reduce the hardness minerals from the feed water. Control of factors that cause hardness salts to become less soluble important. Hardness minerals are defined as water-soluble compounds of calcium and magnesium. The majority of the compounds of calcium and magnesium are much less soluble than the corresponding sodium. By replacing calcium and magnesium part of these minerals with sodium solubility of sulphates and carbonates has improved to such an extent that scaling is no longer a problem. This feature of water softening.
- The second method of prophylaxis of the scale, controlling water conditions that affect the solubility of scale-forming minerals. Five factors that affect the rate of formation of scale:
- Temperature
- Total dissolved solids (TDS)
- Hardness
- Alkalinity
- pH
These factors to some extent be controlled by proper design and operation of water-cooled equipment. Proper temperature levels are maintained, ensuring a good flow velocity of the water and adequate cooling tower.
Consumption of water recirculating systems should be approximately 3 l/min per ton. The lower level in the flow stream to allow the water to stay in contact with hot surfaces condenser for a long time and pick up more heat. Temperature drop on the tower should be from 8 to 10F (4.5 to 5.5C) for compression cooling system, and 18 to 20F (10-11 C) in most of the absorption systems. This cooling effect, due to evaporation, depends on the tower features and uncontrolled atmospheric conditions.
Airflow through the tower and degree of water gap of two factors that determine the amount of evaporation that will occur. Because the heat energy required for evaporation, the amount of water into steam and lost from the system determines the amount of heat. That is, the number of BTU heat recovery factor. One pound of water in cooling towers temperature, requires 1050 BTU be converted from liquid to vapor. Therefore, the higher the weight of water evaporated from the system, the stronger the effect of cooling or lowering of the temperature throughout the tower.
Total dissolved solids, hardness and alkalinity the influence of three interrelated factors. These fumes, makeup, and bleeding or blowing rates. Water, when it evaporates, the system remains in its pure form, leaving behind all dissolved substances. The volume of water evaporative cooling takes place at a relatively constant figure due to the use of float valves.
Fresh make-up water brings with dissolved material. This is added, that has been left behind by evaporated water. Theoretically, if we assume that all the water leaves the system due to evaporation and system volume remains constant, the concentration of dissolved material will increase to infinity. For this reason, bleeding or purging is used.
There is a limit to the number of any material that can be dissolved in water. When this limit is exceeded, the introduction of additional material will cause any sludge or scale form. Control the speed at which the dissolved material is removed controls the degree to which this material is concentrated in the circulating water...
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Industrial