Presentation on Cooling Towers and Their Characteristic Used in Nuclear Industry By M. Usman Shaikh, Dir HRD Cooling Towers and Their Characteristic Used in Nuclear Industry 1. 2. 3. 4. 5. 6. 7. Operating principles and basic definitions Types of cooling towers Mechanical components of cooling tower Cooling water treatment and quality Cooling tower used in nuclear industry Comparison between nuclear and chemical industry Conclusions 1. Operating Principles and Basic Definitions General operation Air water contact Counter flow Cross flow Heat Transfer Principles Evaporation Sensible heat Latent heat . Cross Flow Cross flow is a design in which the air flow is directed perpendicular to the water flow (see diagram below). . .Counter Flow In a counter flow design the air flow is directly opposite of the water flow (see diagram below). Operating Principles and Basic Definitions Sensible Heat : It is amount of heat which is sensed by thermometer . . This heat is used to overcome intermolecular forces of attraction. Latent Heat : It is amount of heat which is not sensed by thermometer. This heat is used to increased temperature of liquid. 2. Types of Cooling Towers General classification . Types of Cooling Towers Classification according to configuration Atmospheric spray tower Natural draft tower Mechanical draft tower . Conditioning .Mostly used in Air. Used at Power Plant . Used in Super Markets /Hotels etc . Complete A/C system with Cooling Tower . . Types of Cooling Towers Classification according to configuration Spray filled tower Coil shed tower Dry cooling tower . 3. Mechanical Components of Cooling Tower Ladder Drift eliminator Louvers Hot water basin Gear box Fire protection . Mechanical Components of Cooling Tower Wet down system Cold water basin Motor Vibration switch Partition wind wall Fan . nonreturn valve .Mechanical Components of Cooling Tower Walk ways Splash fills Spray nozzle Drive shaft Gate. 4. Cooling Water Treatment and Quality Five types of cooling tower water problems Scale formation Little dose of HCl for alkaline water.5) Corrosion Chromates of sodium and zinc are most common Growth of organics Direct chlorine shock and chlorinated organic compounds Suspended solids Pre-treatment of water reduces this problem Oil leakage Proper monitoring and maintenance of process equipments . this problem is not common in acidic water of pH(6-6. Water is chemically neutral SI > 0.0.5-7. Stability index = 7. 0F C = calcium hardness.5. Scale forming tendencies are present SI < 0.0. corrosive tendencies are indicated Stability index Stability index = 2 pH’s – pH (actual) Stability index = 6. ppm B = temperature. Stability index = 6. expressed as ppm CaCO3 D = Alkalinity.3 + A + B) –(C +D) A = total solids. scale forming corrosive good range .Cooling Water Treatment and Quality Cooling water quality Saturation index(SI) Saturation index = pH (actual) – pH’s (Langelier’s equation) pH’s (Langelier’s equation) = (9. expressed as ppm CaCO3 SI = 0. 0 .Cooling Water Treatment and Quality Cooling water quality pH For good quality water ph should be within 6. For good quality water it should not be greater then 2.0 Total hardness It is the sum of carbonate and non-carbonate hardness · Very soft 15 (ppm caco3) · Soft 15-50 (ppm caco3) · Medium hard 50-100 (ppm caco3) · Hard 100-200 (ppm caco3) · Very hard >200 (ppm caco3) Concentration factor The ratio of total dissolve of the cooling water to the total dissolve of the of the makeup water.5-7. 5. Cooling Towers Used in Nuclear Industry Cooling tower used at 3-miles island. USA Natural draft Hyperbolic type . Cooling Towers Used in Nuclear Industry Cooling towers at nuclear power plant Mechanical draft Induced Cross flow type Large fans pull air across the dropping water to remove the heat . Chashma NPP Cooling Tower . CHASHMA-1 Cooling Towers . Cooling Towers Used in Nuclear Industry Cooling tower at a European nuclear power plant Natural draft Hyperbolic type Almost 120m high . 6. Comparison Between Nuclear and Chemical Industry Chemicals industry Average height = 8-15 m Fertilizer industry Average height = 22-28 m Nuclear industry Average height = 100-150 m Blow down contains Treatment chemicals Blow down contains Treatment chemicals Blow down contains Treatment chemicals and negligible activity Mostly natural draft hyperbolic type Selection depend on the atmospheric and seismic conditions Mostly mechanical draft induced type Selection depend on the atmospheric conditions Mostly mechanical draft induced type Selection depend on the atmospheric conditions . 6m 0.Comparison Between Nuclear and Chemical Industry Dukovany nuclear power plant(408 MWe.4m3 s . Check republic) Number per unit Height 2 125m Top diameter Water evaporated per tower 82. and mechanical draft. hyperbolic type at nuclear power plants because a large amount of energy is required to run the fans.Example is dry cooling tower if nuclear tower is present in desert If the blow down is directly put into lake the aquatic life will be in danger in case of NPP . Conclusions The size of cooling towers at nuclear industry is almost four times the size at fertilizer plants They are generally natural draft.7. induced type at fertilizer plants Blow down contains treatment chemicals in fertilizer plants while activity also included in case of NPP Selection depends upon the atmospheric conditions in case of FPP and depends on the seismic conditions as well in case of NPP. Cooling Towers and Their Characteristic Used in Nuclear Industry Thank you Questions please ? .