Water cooling sprays

Water sprays are sometimes used instead of fireproofing where the fireproofing application may be considered detrimental to the situation or uneconomical to achieve. Typical examples are the surface of pressure vessels or piping where metal thickness checks are necessary, structural facilities that cannot accept additional loads of fireproofing materials due to dead weight or wind loads, inaccessibly of the surface for application of fireproofing, or impracticability of fireproofing application. 

Normally where it is necessary, fireproofing is preferred over water spray for several reasons. The fireproofing is a passive inherent safety feature, while the water spray is a vulnerable active system that requires auxiliary control to be activated. Additionally the water spray relies on supplemental support systems that may be vulnerable to failures, i.e., pumps, distribution network, etc. The integrity of fireproofing systems is generally considered superior to explosion incidents compared to water spray piping systems. The typical application of water sprays in place of fireproofing is for vessel protection. 

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HR-ICP-MS EEEMENT-2 (Pinnigan MAT, Germany) equipped with a standard introduction system (quartz water-cooled spray chamber, concentric nebulizer, torch with 1.5 mm i.d. injector and nickel cones) was used for measurements. The following operating conditions were used RP power 1150 W, coolant gas flow rate 16 1 min k auxiliary gas flow rate 0.85 1 min nebulizer gas flow rate 1.2 1 min k Sample uptake rate was 0.8-1 ml min k Measurements were performed with low and middle resolutions. Rh was used as an internal standard. Por calibration working standard solutions were prepared by diluting the multielemental stock solutions CPMS (SPEX, USA) with water to concentration range from 5 ng to 5 p.g I k... 

P. Schramel, Improvement of ICP-measurements by using a water-cooled spray chamber, Fresenius Z. Anal. Chem., 320 (1985), 233-236. 

An analytical scheme was developed [3] to characterize both the concentration and nature of the selenium species present in the various streams measmed (Fig. 1). Because an in-depth discussion of all of the techniques would be beyond the scope of this paper, the reviewed work will focus on the efforts to measure total selenium as well as selenite, selenate, and selenocyanate. A Sciex Elan Model 6000 Inductively Coupled Plasma-Mass Spectrometer system equipped with a water-cooled spray chamber was used for all of the selenium measurements. The operating conditions used for the ICP-MS are presented in Table 2, while conditions for the IC are presented in Table 3. 

Reaction times can be as short as 10 minutes in a continuous flow reactor (1). In a typical batch cycle, the slurry is heated to the reaction temperature and held for up to 24 hours, although hold times can be less than an hour for many processes. After reaction is complete, the material is cooled, either by batch cooling or by pumping the product slurry through a double-pipe heat exchanger. Once the temperature is reduced below approximately 100°C, the slurry can be released through a pressure letdown system to ambient pressure. The product is then recovered by filtration (qv). A series of wash steps may be required to remove any salts that are formed as by-products. The clean filter cake is then dried in a tray or tunnel dryer or reslurried with water and spray dried. 

Although the continuous casting of steel appears deceptively simple in principle, many difficulties are inherent to the process. When molten steel comes into contact with a water-cooled mold, a thin soHd skin forms on the wall (Eig. 10). However, because of the physical characteristics of steel, and because thermal contraction causes the skin to separate from the mold wall shortly after solidification, the rate of heat abstraction from the casting is low enough that molten steel persists within the interior of the section for some distance below the bottom of the mold. The thickness of the skin increases because the action of the water sprays as the casting moves downward and, eventually, the whole section solidifies. 

Hardenability is so important that a simple test is essential to measure it. The Jominy end-quench test, though inelegant from a scientific standpoint, fills this need. A bar 100 mm long and 25.4 mm in diameter is heated and held in the austenite field. When all the alloying elements have gone into solution, a jet of water is sprayed onto one end of the bar (Fig. 12.3). The surface cools very rapidly, but sections of the bar behind... 

In many cases, heating or cooling of the gaseous effluent will be required before if enters the control device. The engineer must be thoroughly aware of the gas laws, thermodynamic properties, and reactions involved to secure a satisfactory design. For example, if a gas is cooled there may be condensation if the temperature drops below the dewpoint. If water is sprayed into... 

Evaporative Cooling of the Turbine. Traditional evaporative coolers that use media for evaporation of the water have been widely used in the gas turbine industry over the years, especially in hot climates with low humidity areas. The low capital cost, installation, and operating costs make it attractive for many turbine-operating scenarios. Evaporation coolers consist of water being sprayed over the media blocks, which are made of fibrous corrugated material. The airflow through these media blocks, evaporates the water, as water evaporates, it consumes about 1059 BTU (1117kJ) (latent heat of vaporization) at 60 °F (15 °C). This results in the reduction... 

Open Tube Sections (Water cooled) Tubes require no shell, only end headers, usually long, water sprays over surface, sheds scales on outside tubes by expansion and contraction. Can also be used in water box. Condensing, relatively low heat loads on sensible transfer. Transfer coefficient is low, takes up less space than pipe coil. 0.8-1.1... 

In a continuous casting machine, molten steel is poured into a reservoir at the top of the machine. It passes at a controlled rate into a water cooled mold where the outer shell of the steel becomes solidified. The steel is drawn down into a series of rolls and water sprays, which ensure that it is both rolled into shape and fully solidified at the same time. At the end of the machine, it is straightened and cut to the required length. Fully formed slabs, blooms, and billets emerge from the end of this continuous process. 

FIGURE 4.21 Water cooling in a cooling tower, which operates according to the parallel flow principle in other words, the water spray turns in the direction of the air flow. 

Where hot ambient temperatures are expected, overall turbine efficiency and horsepower output can be increased by installing an evaporative cooler in the inlet. Inlet air flows through a spray of cold water. The temperature of the water and the cooling effect caused by the inlet air evaporating some of the water cools the inlet air. In desert areas where the inlet air is dry and thus able to evaporate more water before becoming saturated with water vapor, this process is particularly effective at increasing turbine efficiency. 

If the compound being extruded is not attacked by water, for example, conventional butadiene-acrylonitrile based compounds, the preforms are passed through a water cooling system. The water cooling system can be using either the spray technique or complete submersion. 

Wlien ejectors pull non-condensables and other vapors from a direct contact water condenser (barometric, low level jet, deaerator) there is also a release of dissolved gases, usually air, from water. This air must be added to the other known load of the ejector. Figure 6-22 presents the data of the Heat Exchange Insdtute [10] for the amount of air that can be expected to be released when cooling water is sprayed or otherwise injected into open qqae barometric or similar equipment. 

Figure 9-102. Cross-section of iow-head forced-draft tower showing fan housing arrangement, fiiling, water distribution spray system and spray eliminators. Used by permission of Foster Wheeler Corp., Cooling Tower Dept.

Metals which are subject to oxidation or attack by nitrogen can be sprayed in a closed system so that air is exluded. The heat necessary to melt the wire is produced by current generated in the wire itself by high-frequency currents flowing in small water-cooled coils. By this means, titanium, niobium and even uranium, can be sprayed without gaseous contamination. 

In most climates the wet bulb temperature is well below the dry bulb temperature and there is an advantage in using water or evaporative cooling for larger plant. These options need to be investigated and compared. The present concern over spray-borne diseases may indicate a preference for air cooling in the vicinity of institutions but correct maintenance of water cooling towers and evaporative condensers will permit their use elsewhere. Table 10.2, based on the tentative temperature differences of 15 K and 12 K... 

Figure 13.12. Water-cooling tower. View of spray distribution system...

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