Cooling towers specifications

Cooling Water System. A list of cooling duties will be available at this point so the cost estimate for this system can be factored or estimated based on a similar operating system. For a more definitive estimate based on initial or detailed layout, it is probably best to use a contractor or consultant skilled in these designs. If a cooling tower is involved, the groundwork will already have been set. This basis can be passed along on specification sheets provided in the Appendix to a vendor for quotes. 

Debris particles that are heavier than water migrate to the outer wall area and slither down into a collection bowl that is periodically blown down. Very little water is lost. Typical performance is 97.8% of solids with specific gravity exceeding 1.2 down to 45 microns. Side stream filtration is more common in cooling tower applications. The scheme uses a small dedicated pump to draw dirty water from the sump, direct it through a filtration device and sent it back to the basin. 

The purchase of the cooling tower is, in most cases, a once in a decade operation. Where towers are bought on a regular basis, specifications are determined either by the user or by the consultant, incorporating their experience of operation and any changes required as a result of production/process alterations. 

Some manufacturers of internal cooling tower components, specifically fill material and drift eliminators, have products produced from less easily ignited plastic that have been tested by a nationally recognized testing laboratory and determined to have sufficient fire resistance or reduced flame spread ratings that when, and only when, used in an otherwise noncombustible cooling tower, do not require fixed automatic fire protection. 

NFPA 214 provides specific guidance regarding fire protection of cooling towers including recommended water spray application rates. The detailed design of fixed fire protection systems for cooling towers should follow the requirements of NFPA 13 or NFPA 15. 

At the time of completion of an installation, the water and air conditions and the loads may not be exactly the same as those of the design specification. Acceptance tests performed then must be analyzed to determine if the performance is equivalent to that under the design specifications. Such tests usually are performed in accordance with recommendations of the Cooling Tower Institute. 

There are a number of terms with rather rigorous definitions within the context of cooling tower technology. It is worthwhile for the newcomer to this subject to learn these definitions early on in the discussions. In subsequent chapters we will apply the following definitions to establishing specific design guidelines. 

Before developing specific relationships to describe cooling tower operations, it is worthwhile to review some elementary principles in developing material and energy balances. In addition, we need to review heat and mass transfer analogies before tackling design problems. The more experienced reader may wish to proceed to Chapter 4 or try the example problems at the end of the chapter as a refresher. 

Cooling towers are classified according to the method by which air is introduced to the tower. The principal types are atmospheric spray, natural-draft, mechanical-draft, deck-filled, spray-filled, coil shed and hyperbolic towers. Most industrial cooling tower installations are field-erected units designed for specific thermal characteristics. 

Plant operations personnel generally purchase cooling towers rather than construct them themselves. The philosophy behind this policy is that it makes available to operators a wealth of practical knowledge directly applicable in the field. The operator must specify the amount of water and the temperature range required to handle a specific set of process conditions. It is the fabricator s responsibility to propose a system that will meet the operator-furnished conditions for the 5% wet-bulb in the plant locality. This also means that the fan power with which the operation will be accomplished will be guaranteed. 

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