N atural cooling tower
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This document discusses natural draft cooling towers. It begins by defining a cooling tower as a device used to transfer heat and cool water for reuse. It then discusses the types of cooling towers, focusing on natural draft towers. The key components of a natural draft cooling tower are described, including the supply basin, cooling tower, fill material, and drift eliminators. The document explains that natural draft towers use the stack effect and heat transfer between warm water and ambient air to cool the water, which is then recirculated. Finally, it provides some strategies to improve the efficiency of natural draft cooling towers.
N atural cooling tower
- 1. Natural Draft Cooling Towers PRESENTED BY: ABDULLAH MANSOOR ROLL#0042 SECTION MB
- 2. Contents What is a cooling Tower Types of Cooling Tower Natural Draft Cooling Tower Common terms use in Cooling Towers Construction of natural Cooling Towers Working of Natural Cooling Tower Strategies to improve efficiency
- 3. Cooling towers “A cooling tower is a device that is use transfer heat and cool water for reuse in a process” Cooling towers are used in process industries to cool off effluent water from various heat transfer equipment e.g., condensate from a condenser. The cooled water is sent back to the process for reuse, thus emphasizing conservation of water.
- 5. Types of cooling tower
- 6. Cross and Counter Flow in Natural Cooling Towers
- 7. What is a Natural Draft Cooling Tower What is a Natural Draft Cooling Tower? A Few Important Terms Components How it Works Remarks A natural draft cooling tower is a means to remove waste heat from a system and release it into the atmosphere. Typically used at oil refineries, chemical plants and power plants to remove heat absorbed from circulating cool water systems. Two types of Heat loss take place in the cooling tower 1. Sensible heat loss 2. Evaporation
- 8. Why evaporation causes cooling ? Evaporation results in vapor escaping from the surface of the liquid. The vapors require energy to escape. That energy is heat. As vapors escape the surface, they carry with them some heat content of the liquid, and thus cause the liquid surface to cool.
- 9. Important Terms Wht is a Natural Draft Cooling Tower? A Few Important Terms Components How it Works Wet Bulb Air Temperature Adiabatically adiabatic cooling Dry Bulb Air Temperature Natural Draft Stack Effect Humidity • What is a Natural Draft Cooling Tower? • A Few Important Terms • Components • How it Works • Remarks
- 10. Components What is a Natural Draft Cooling Tower? A Few Important Terms Components How it Works Remarks Supply Basin Tower Pumps Cooling Towers Vertical Ribs Reinforced Concrete Shell Internal Void Diagonal Columns Hot Water Inlet Fill Splash Film Hot Water Distribution System Cold Water Collection Drift Eliminators - Drift eliminators are used to control this drift loss from the tower. (Mist) • What is a Natural Draft Cooling Tower? • A Few Important Terms • Components • How it Works • Remarks
- 12. Basic working principle of a cooling tower Considering an example of an air-water system, the basic working principle of a cooling tower can be listed as, 1. Hot water and relatively cool ambient air enter the cooling tower. 2. Heat transfer between the air stream and the water stream occurs. 3. Hot water transfers its heat to the ambient air and becomes cool. 4. Cool water is removed from the cooling tower and sent back to the process plant. 5. The resulting hot air rises and is, generally, removed from the top of the tower by virtue of its low density.
- 13. How it Works What is a Natural Draft Cooling Tower? A Few Important Terms Components How it Works Remarks
- 14. Strategies to improve cooling tower performance When designing a cooling tower, always use the highest wet-bulb temperature as reference. Monitor the range and approach carefully during the design. High range and low approach leads to good performance. Improve the quality of water to be cooled by the tower resulting in low utilization of make-up water. Regularly monitor the tower for scale build-up and biological impurities. Regularly monitor the flow of water and air inside the tower
- 15. References Literature: Dr. N.P. Cheremisinoff, Handbook of Chemical Processing Equipment, 1st edition, Butterworth- Heinemann, USA, 2000. J. M. Coulson, J.F. Richardson, J.H Harker, J.R. Backhurst, Chemical Engineering Volume 1 – Fluid Flow, Heat Transfer and Mass Transfer, 6th edition, Butterworth- Heinemann, USA, 1999. San Diego County Water Authority, Technical Information for Cooling Towers Using Recycled Water, San Diego, USA, 2009. Training Session on Energy Equipment, Cooling Towers, UNEP, 2006. Websites / URL’s: http://www.cti.org/whatis/coolingtowerdetail.shtml http://www.engineeringtoolbox.com/ http://www.deltacooling.com/resources/principles-of-cooling- towers/
Editor's Notes
- #4: http://www.cti.org/whatis/coolingtowerdetail.shtml
- #15: During the design of a cooling tower, the wet-bulb temperature should be carefully monitored and selected as it may vary from season to season. Always use the highest temperature which occurs in summertime at high humidity. Pre-Treatment of water to remove BOD and TDS before sending to the tower.