Makeup requirements

Water Makeup Makeup requirements for a coohng tower consist of the summation of evaporation loss, drift loss, and blowdown. Therefore,... 

Example 13 Calculation of Makeup Water Determine the amount of makeup required for a cooling tower with the following conditions ... 

Mist eliminators are widely used in air polluhon control systems to prevent free moisture from entering the atmosphere. Usually, such mist eliminators are found downstream from wet scrubbers. The recovered mist is returned to the liquid system, resulhng in lowered liquid makeup requirements. 

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. 

The presence of impurities such as butadiene affects the product yield and properties. Butadiene tends to polymerize and form acid-soluble oils, which increases acid makeup requirements. For every pound of butadiene in the feed, ten pounds of additional make-up acid will be required. ... 

Decreasing the heat duty on evaporative cooling tower circuits by better energy efficiency to decrease the evaporation from the cooling tower and hence, decrease the makeup requirements. 

Air streams from the digestion system, vacuum cooler, concentrator, and other areas where fluorine is evolved are connected to a highly efficient absorption system, providing extremely high volumes of water relative to the stream. The effluent from this absorption system forms part of the recycled water and is eventually discharged as part of the product used for fertilizer manufacture. The Minnesota plant requires a constant recirculating water load in excess of 3000 gpm (11.4 m /min), but multiple use and recycle reduce makeup requirements to less than 400 gpm (1.5 m /min) or a mere 13% of total water use. 

Figure 6.14 Chart for estimating cooling tower makeup requirements.

The second benefit of increasing the COC is that, with less makeup required, the variations in makeup water quality will tend to have less effect on the recirculating water (greater cooling water stability). 

The cooling water, steam systems, and water makeup requirements were ... 

The recycle of water from the distillation system also has the effect of reducing the demineralized water makeup requirement. 

The spent catalyst and air move through the regenerator in plug flow to permit the unit to be designed with a low catalyst inventory and thereby reduce fresh catalyst makeup requirement. 

It can be operated continuously in closed loops with modest reagent makeup requirements. 

Using our measured rate data and equilibria from Pressman and Lucas, the estimated reactor residence times for 85% conversion with 1 M H2SO4 at 105°C are 14 hours for a batch or plug flow reactor, 85 hours for a single completely stirred tank reactor (CSTR), or 33 hours for two CSTR s in series. If the reaction was carried out at the scrubber site, no additional purification should be required, but there would be a makeup requirement for sulfuric acid. 

The solvent makeup requirement reported by Hazen [H4] was only 0.21 volumes per 1000 volumes leach liquor treated. 

Thorium makeup requirements for one reactor system, the HTGR (high-temperature gas-cooled reactor), may be estimated from Fig. 3.33. A 1000-MWe HTGR requires 7.4 MT of thorium as feed pet year. Reprocessing recovers 6.8 MT, which can be recycled after storage for 20 to 30 years to permit excess Th to decay. The net thorium consumption of a 1000-MWe reactor then is 0.6 MT/year. Thus, the 441,000 MT of U.S. ThOa thorium reserves listed in Table 6.14 would provide thorium fuel for... 

It should also be noted that water boilers may well need chemical treatment for the first filling of water as well as additional periodic chemical treatment depending on the system s losses and the makeup requirements. Water treatment may vary fromseason to season or over a period of time and, therefore, there should be a requirement that the water-treatment procedure be checked no fewer than four times a year and possibly more frequently if the local water conditions require it. When the system is drained and then refilled, chemical treatment is required inasmuch as raw water has been put into the boiler system. 

The use of overall mass-transfer coefficients does not distinguish between convective and evaporative cooling of the liquid and will not permit computation of the humidity or dry-bulb temperature of the exit air. The air will ordinarily be very nearly saturated, and for purposes of estimating makeup requirements it may be so assumed. The temperature-humidity history of the air as it passes through the tower can be estimated by a graphical method on the diagram (Fig. 7.11) if and kyO are known [17] but approach of the gas to saturation is very critical to the computations, and it is recommended instead... 

The sulfur slurry that accumulates in the bottom of the settler vessel is periodically withdrawn and pumped through a plate and frame filter press where the sulfur is removed and the filtrate is returned to the process. The filtercake is then water washed and air blown to minimize catalyst losses (not shown). The wash water is returned to the system where it serves as a primary source of make-up water to replace that lost by evaporation. The water wash and air blow cycle are the determining factors in the chemical makeup requirements of the process. A small amount of catalyst concentrate is added after each filtration cycle to replace filtercake losses. It is claimed that no catalyst degradation occurs under normal operating conditions. The only other chemical make-up requirement consists of a small amount of alkaline solution for pH control. 

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