BS 382 0 RContents(3.80000e-2)CreationDate(D:20150610152143-0700)DA(11 TL Cour 8 Tf)DS(font: Courier New 8.0pt; text-align:left; color:000000 )F 4ITFreeTextTypewriterM(D:20150610154553-0700)NM(d33bb2f0-362b-48fd-815a-2b53b6535eff)P 35 0 RRC( 3.80000e-2.Leaks should be identified, quantified and corrected where possible.
This difference can be used to calculate the approximate amount of evaporation that has occurred in the cooling tower. The recirculation rate can be determined from information on pump performance, tower hydraulics, etc. Cooling Tower Capacity Calculation Formula How To Determine RecirculatingA detailed description of how to determine recirculating rate is given in the PAC-3 section of the Value Added Troubleshooting Guide. Many times throttling valves, pipe restrictions, and head pressure restrictions interfere and can produce deviations as great as 50-75 from the name plate values. Concentration ratio is also referred to as the cycles of concentration. All of the dissolved ions are left behind to concentrate in the system. If the only system water loss was through evaporation, the dissolved ions in the recirculating water would continue to concentrate (from the ions left after evaporation) until the solubility of each ion in the water was exceeded and massive scaledeposition resulted. Most systems cannot tolerate any scale; therefore, the level or concentration of critical scaling-prone ions in the water is usually controlled by a combination of bleeding off a certain portion of the recirculation water and adding anti-scaling compounds. The rate at which water is bled from a system (in gpm; m3hr) compared with the amount of fresh water being introduced in the system (in gpm; m3hr) will also determine the concentration ratio. Compare its concentration in the makeup water to its concentration in the recirculating water by dividing the tower content by the makeup content. If the cycles of calcium concentration are consistently lower than the cycles of magnesium concentration, for example, the calcium can be assumed to be precipitating in the system. There may also be scale forming in the heat transfer equipment, thereby impeding production.) Entry of ions from sources other than the makeup water can invalidate any ratio being developed. ![]() The amount of water entering the system must be equal to the amount leaving the system. If the concentration ratio is also known then the makeup water requirements can be calculated as follows. In very tight (low water loss) open recirculating systems, the two primary areas for system water loss are evaporation and water blowdown. In practice, however, a lot of water may also be lost through system water leaks, by water combining with the product or process, or by tower drift. Indsutry standard is the installation of a cooling blowdown controller, to adjust the amount of blowdown automatically. For calculation purposes, all of these water losses, except for evaporation, are generally considered together and called tower water blowdown. The blowdown rate is normally measured in gallons pen minute (m3hr). Unfortunately the ideal cooling system only exist in concept and in operating systems we find other water losses that need to be understood and factored into the overall cooling system materials balance equation. ![]() Drift is the primary mechanism for transmission of pathogens from a cooling system to a host. Drift is usually estimated based on a percentage of recirculation. ![]()
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