Periodic cooling towers

Periodic Cooling Towers for Electric Power Plants... 

Constmction of new power plants in the coal region of the western United States presents serious problems in states whose laws dictate zero effluent. In these plants, cooling-tower water withdrawn from rivers cannot be returned to them. In these situations, cooling-tower effluent is purified by distillation (vapor-compression plants have predominated) and by a combination of distillation and membrane technology. The converted water then is used as boiler feedwater the plant blowdown (effluent) is evaporated from open-air lined pools, and pool sediment is periodically buried back in the coal mine with the flue ashes. 

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. 

For the periodic or once-off buyer it is essential to obtain advice from a reputable supplier or a consultant with experience of cooling towers usage (Figure 34.4). 

As an example, the reputable cooling tower designer would establish most of the above parameters from his own experience. In addition, he could determine with his client the economic factors which could influence his selection, i.e. low capital cost with high mnning costs, or a higher capital cost with more acceptable power costs (a 12-month or a 5-year payback period). Turnkey contractors often understandably ignore this particular factor, and end users should always obtain alternative designs to make their own selection. 

Relative humidity tends to be much higher at night than during the day. Consequently, the critical period for the formation of cooling tower-induced... 

The total cost is the economic factor that normally decides the final cooling tower design however, the optimum selection must include not only the capital investment, but also all operating costs based on the period of amortization. Other factors to be considered are general design, manufacturer, replacement parts, flexibility of operation, etc. Costs include capital investment and operating costs. 

Periodic Response of a Viscoelastic Cooling Tower Lanshaar, H. L. Boresi, A. P. 

The periodic response of a linear viscoelastic cooling tower to a prescribed recurring sequence of pressure fluctuations and earth accelerations are analyzed. An approximate analysis, based on the bending theory of shells, is presented. The problem is reduced to a double sequence of boundary-value problems of linear ordinary differential equations. 19 refs, cited. 

Due to the permanent load conditions of hyperbolic cooling systems, it is very difficult to periodically clean tower basins, and considerable silt, slime, algae, and other debris can easily accumulate. 

At its simplest, however, systems for HOBr generation require merely that the bromide and bleach chemicals are pumped directly into a flow of water (usually the makeup water) for a certain period each day and at a prescribed ratio. Then the water, containing the two chemicals, passes through a static mixer and into the cooling tower basin (see Figure 6.2) or, more preferably,... 

Periodic inspection and cleaning of all cooling tower components. 

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