Water cooling tower

Cooling tower blowdown can be reduced by improving the energy efficiency of processes, thus reducing the thermal load on cooling towers. Alternatively, cooling water systems can be switched to air coolers, which eliminates the problem altogether. 

Water Treatment Industrial CleaningPipplications. Boiler and cooling tower waters are treated with lignosulfonates to prevent scale deposition (78). In such systems, lignosulfonates sequester hard water salts and thus prevent their deposition on metal surfaces. They can also prevent the precipitation of certain iasoluble heat-coagulable particles (79). Typical use levels for such appHcatioas range from 1—1000 ppm. 

Phosphonic acid is an intermediate in the production of alkylphosphonates that are used as herbicides and as water treatment chemicals for sequestration, scale inhibition, deflocculation, and ion-control agents in oil weUs, cooling tower waters, and boiler feed waters. For example, aqueous phosphonic acid reacts with formaldehyde and ammonium chloride in the presence of hydrochloric acid to yield aminotri(methylenephosphonic acid) [6419-19-8]. 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

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 In these plants, cooling-tower water withdrawn from rivers cannot be returned to them.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. 

Maintenance cost. Maintenance for air-cooled equipment as compared with sheU-and-tube coolers (complete with coohng-tower costs) indicates that air-cooling maintenance costs are approximately 0.3 to 0.5 those for water-cooled equipment. 

Evaporative condensers (Fig. 11-88) are widely used due to lower condensing temperatures than in the air-cooled condensers and also lower than the water-cooled condenser combined with the cooling tower. Water demands are far lower than for water-cooled condensers. The chemical industry uses shell-and-tube condensers widely, although the use of air-cooled condensing equipment and evaporative condensers is on the increase. 

Condenser cooling medium Brine Chilled water Tower water Chilled water... 

Figure 12.13 illustrates severe damage suffered by a component of a cooling tower water pump. The jagged, undercut, spongelike metal loss characteristic of cavitation damage is apparent in Fig. 12.14. All damage occurred along the inner curvature of the specimen.

NFPA 214 Standard on Water-Cooling Towers, 1996 edition. National Fire Protection Association, Quincy, MA. 

Figure 30-lA presents the integrated environmental control potential for maximum control of particulate matter and SO2. Cooling tower water blowdown and treatment by-products may be used to satisfy scrubber makeup requirements. Fly ash and scrubber sludge will be produced separately. If the catalytic NO, process is required, the integration issues will be increased significantly. 

Figure 30-lC is distinctly different from the first two in the type of SO2 control processes used and the sequence of the particulate matter and SOj controls. It is a promising approach for up to 90% SO2 control of western United States coal, and there is a single waste product. Other features include the collection of particulate matter at temperatures below 90°C and the possibility for spray dryer cooling tower water integration. This. system may or may not include a catalytic NO unit. 

A comparison unit with identical design used once through water cooling. This is the same high sulfur water that was used as makeup for the above cooling tower. Here the sulfur was not allow ed to concentrate and the unit is working fine after several years. 

Provision of efficient drift eliminators of water cooling towers consideration of replacement by air cooling systems. Thermal insulation to protect personnel from contact with hot or cold surfaces prevention of water supply disruption by freezing. 

Water flows inside the tubes, and vapors eondense on the shell side. Cooling water is normally chilled, as in a cooling tower, and reused. Air-eooled surfaee eondensers and some water-cooled units eondense inside the tubes. Air-cooled condensers are usually construeted with extended surfaee fins. 

Acceptance Testing Test procedures to determine the water cooling capacity of towers. Instrumentation used and measurement procedures should be those recommended by the Cooling Tower Institute (CTI) in its "Acceptant Text Procedures. "... 

Wet-Bulb Temperature The temperature of saturated air. The lower the wet-bulb temperature, the more exchange of heat a cooling tower can do. A tower cannot cool the water to a temperature below the wet-bulb temperature of the entering air. 

Fig. 3.3 1-3 Cooling Tower Water (. hloriuiiiiuu Basin water u- circulated by the pump throitgi the venturi at 3t> gpm. Chlorine gas, piiivulril ir. a ton tank, is reduced to zero pressure ni tr.e /r.. s snj c reducing valve to be brought in - < llie u. /-...

HAZOP focuses on study nodes, process sections, and operating steps. The number of nodes depending on the team leader and study objectives. Conservative studies consider e er line and vessel. An experienced HAZOP leader may combine nodes. For example, the cooling looser . .ater chlorination system may be divided into a) chlorine supply to venturi, b) recirculation loop, and e) to .er water basin. Alternatively, two study nodes may be used a) recirculation loop and tower water basin, and b) chlorine supply to venturi. Or one study node for the entire process. 

Hliiull. In v.tive B 5th ijifcni-.O pr< SM re ViilvL-. fail [jpai C)peration Excessive chlorine How to Tower Water Basin - high chlorine level to cooling water -potential for excessive corrosion in cooling water system Rotameter Relief valve an pressure check valve outlet in Nnilk-... 

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