CT Performancesssssssssssss Analysiss.pptx

ct

1. Cooling Tower Performance Analysis

2. Presentation Sequence Introduction Types of cooling towers Assessment of cooling towers Energy efficiency opportunities

3. Introduction

4. Components of a cooling tower Frame and casing : support exterior enclosures Fills (Facilitate heat transfer by maximizing water / air contact Splash fills Film fills Hot water basin Cold water basin (receives water at the bottom of tower) Drift eliminators (capture droplets in air stream) Louvers (equalize air flow into the fill and retain water within tower) Nozzles: spray water to wet the fill Fans : deliver air flow in the tower

5. Types of cooling towers : Natural draft Hot air moves through the tower Fresh cool air is drawn into the tower from bottom No fan required Concrete tower <200 m Used for large heat duties Generally used for water flow rates above 45000 m 3 /Hr.

6. Types of cooling towers : Mechanical draft Large fans to force air through circulated water Water falls over fill surfaces: maximum heat transfer Cooling rates depend on many parameters Large range of capacities Can be grouped, e.g. 8-cell tower

7. Types of cooling towers : Mechanical draft Forced draft Induced draft cross flow Induced draft counter flow

8. Types of cooling towers : Induced draft Two types Cross flow Counter flow Advantage: less recirculation than forced draft towers Disadvantage: fans and motor drive mechanism require weather-proofing

9. Assessment of cooling towers : Effectiveness Effectiveness Range / (Range + Approach) 100 x (CW in temp – CW out temp) / (CW in temp – Wet bulb temp) High effectiveness = good performance

10. Assessment of cooling towers Heat rejected in kCal/hr. or tons of refrigeration (TR) mass flow rate of water X specific heat X temperature difference High cooling capacity = good performance Evaporation loss (m 3 /Hr.) 0.00085 x 1.8 x circulation rate (m 3 /Hr.) x (T 1 – T 2 )

11. Assessment of cooling towers Cycles of Concentration Ratio of dissolved solids in circulating water to the dissolved solids in make up water Blow Down Evaporation Loss / (C.O.C. – 1)

12. Assessment of cooling towers : L/G Ratio Ratio between water and air mass flow rates Heat removed from the water must be equal to the heat absorbed by the surrounding air L(T 1 – T 2 ) = G(h 2 – h 1 ) L/G = (h 2 – h 1 ) / (T 1 – T 2 ) T 1 = hot water temp ( o C) T 2 = cold water temp ( o C) Enthalpy of air water vapor mixture at inlet wet bulb temp (h 1 ) and outlet wet bulb temp (h 2 )

13. Energy efficiency opportunities Selecting a cooling tower Fills Pumps and water distribution Fans and motors

14. Selecting a cooling tower Capacity Heat dissipation (kCal/hour) Circulated flow rate (m 3 /hr.) Other factors

15. Selecting a cooling tower Range Range determined by process, not by system Approach Closer to the wet bulb temperature = Bigger size cooling tower = More expensive

16. Selecting a cooling tower Heat Load Determined by process Required cooling is controlled by the desired operating temperature High heat load = large size and cost of cooling tower

17. Energy efficiency opportunities Monitor approach, effectiveness and cooling capacity for continuous optimization efforts. Consider energy efficient FRP blade adoption for fan energy saving. Consider positive improvements in cooling water pumps with respect to efficiency improvement. Optimize process cooling water flow requirement to save Pump power Evaporation loss Blow down loss

18. L/G Ratio Fills Water Quality Cooling Water network Efficient Tower Summary

19. Thank You.