cooling towers
DESCRIPTION
general ppt on cooloing towers for power engineer's.... thank you for readingTRANSCRIPT
Cooling towers
Operation and water management
Forced Draft Cooling Towers
Forced Draft Cooling Towers
Forced Draft Cooling Towers
Forced Draft Cooling Towers
Natural Draft Cooling Towers
Small cooling installations
Water Distribution Details
1. Fan 2. Drift eliminator 3. Warm water 4. Water distribution 5. Water sprinkling nozzle 6. Fill packing
7. Air inlet 8. Water pool 9. Cooled water
Packing Materials
Cooling Tower Mass Balances
Water and Salt BalancesA water balance around the entire system is:
M = E + D + W
Since the evaporated water (E) has no salts, a chloride balance around the system is:
M (XM) = D (XC) + W (XC) = XC (D + W)
and, therefore:
XC/XM = Cycles of concentration
= M/(D + W)
= M/(M – E) = 1 + [E ÷ (D + W)]
Windage Losses
Windage losses (W), in the absence of manufacturer's data, may be assumed to be:
W = 0.3 to 1.0 percent of C for a natural draft cooling tower without windage drift eliminators
W = 0.1 to 0.3 percent of C for an induced draft cooling tower without windage drift eliminators
W = about 0.01 percent of C (or less) if the cooling tower has windage drift eliminators
Heat Balance
From a simplified heat balance around the cooling tower:
E HV = C · ΔT · cp
Hv = Latent heat of water evaporation = 2260 kJ/kg
Δ T = Temperature difference top to bottom
Cp = Specific heat of water = 4.184 kJkg-1C-1
Biocides - The Ct Concept
In disinfection, the ability to inactivate microorganisms is a function of both disinfectant concentration and time.
Fractional removal = Cntm
This is generally simplified to Fractional removal = Ct
Ct values have been determined for99.99% virus and 99.9% Giardia removal
http://www.pnl.gov/fta/6_ozone.htmhttp://www.cti.org/downloads/legion_2000.pdf
Chlorine Dioxide ProductionClO2 made from Sodium Chlorite: Acidification of Chlorite5 ClO2- + 4 H+ --> 4 ClO2 + 2 H2O + Cl-Oxidation of Chlorite by Chlorine2 NaClO2 + Cl2 --> 2 NaCl + 2 ClO2Oxidation of Chlorite by Persulfate2 NaClO2 + Na2S2O8 --> 2 ClO2 + 2 Na2SO4From Sodium Hypochlorite and Sodium ChloriteNaOCl + 2 NaClO2 + 2 HCl --> 2 ClO2 + 3 NaCl + H2OElectrochemical oxidation of chloriteClO2- --> ClO2 + e-Dry chlorine/chlorite (laboratory method)NaClO2 + 1/2 Cl2 --> ClO2 + NaCl (solid)