Large mechanical-draft cooling towers

Crossflow mechanical draft towers are thermally less efficient. They offer less resistance to air flow and can operate at higher velocities than counterflow towers, which means less horsepower and smaller cell sizes for comparable outputs. In practice, however, both crossflcw and counterflow designs have advantages and limitations, depending on the type of application. 

Electric motors. These should be matched to power requirements of the fan. 

Fan blades. These are fabricated of lightweight metal or plastics and are balanced. 

Speed reducer. It is usually integrated with other elements, namely, motor, shaft and fan. Its job is to convert the high-rpm, horizontal rotation of the drive shaft into the vertical, low-rpm motion of the fan shaft. 

Header pipe. This is usually made of redwood staves for very large towers. 

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A method is given for predicting the costs of large evaporative type natural and mechanical draft cooling towers as functions of the main design parameters. The costs and parameter factors are expressed analytically for use in power plant optimization programs. 3 refs, cited. 

In an atmospheric spray tower the air movement - is dependent on atmospheric conditions and the aspirating effect of the spray nozzles. Natural-draft cooling tower operation depends on a chimney or stack to induce air movement. Mechanical-draft cboling towers utilize fans to move ambient air through the tower. Deck-filled towers contain tiers of splash bars or decks to assist in the breakup of water drops to increase the total water surface and subsequently the evaporation rate. Spray-filled towers depend only on spray nozzles for water breakup. Coil shed towers are comprised of a combination structure of a cooling tower installed on top of a substructure that contains atmospheric section coils. Hyperbolic natural-draft cooling towers are typically large-capacity systems. 

Perhaps the most common environmental requirement in modem cooling tower installations is that of noise. The fan equipment and the falling water generate cooling tower noise. In large mechanical- or natural-draft cooling... 

The magnitude of the heat rejection of large modern power generating plants is so great that the problem of potential environmental effects due to dry cooling systems must be studied. The plumes from both natural-draft and mechanical-draft towers designed for 1000-MW plants of several representative types are examined with respect to... 

On the Minimum Size of Large Dry Cooling Towers with Combined Mechanical and Natural Draft... 

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