Evaporation water cooling

Computerized Engineering Model for Evaporative Water Cooling Towers... 

The withdrawn residual gas is warmed in the heat exchanger and is used for the regeneration of the molesieve adsorber and for evaporative water cooling. 

The solution obtained is evaporated somewhat, cooled in a vacuum desiccator and the crystals of the tetraoxo-acid filtered off too drastic evaporation causes formation of the heptaoxodiphosphoric acid by loss of water. 

Steam-Jet Systems. Low pressure water vapor can be compressed by high pressure steam in a steam jet. In this way, a vacuum can be created over water with resultant evaporation and cooling water, therefore, serves as a refrigerant. This method frequently is used where moderate cooling (down to 2°C) is needed. The process is inefficient and usually is economically justified only when waste steam is available for the motive fluid in the steam jet. 

When the dryer is seen as a heat exchanger, the obvious perspective is to cut down on the enthalpy of the air purged with the evaporated water. Minimum enthalpy is achieved by using the minimum amount of air and cooling as low as possible. A simple heat balance shows that for a given heat input, minimum air means a high inlet temperature. However, this often presents problems with heat-sensitive material and sometimes with materials of constmction, heat source, or other process needs. AH can be countered somewhat by exhaust-air recirculation. 

Although 600 m of water is used to make a metric ton of fertilizer, 150—240 m to make a tonne of steel, 480 m to make a tonne of gasoline, and 1000 m to make a tonne of acetate fiber, Htde if any is required chemically in any of these processes. Recycling can reduce industrial requirements by a factor of 10—50. Much of this water, particularly that for cooling, and often that for washing, can be saline. Some petroleum refiners have used salt water to remove heat (water s principal role in gasoline production), and some have actually produced table salt by evaporation in cooling towers. 

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. 

Figure 1.8 Evaporation of a metal by laser beam irradiation to provide a source for the deposition of nanoparticles on a water-cooled substrate...

Example. A water-cooled unit with an evaporator temperature of-40°F will require 3 horsepower/ton of refrigeration. A ton of refrigeration is equal to 12,000 BTU/hr. Here are equations for these curves in the fonn ... 

The solution in the left flask is stirred for 30 minutes after all the potassium amide has been added. The nitrogen inlet is briefly removed and 120 g. (1.5 moles) of ammonium nitrate is added this discharges the ehartreuse color. (Caution Vigorous foaming occurs.) Ethyl ether (500 ml.) is added and the dry iee condenser is replaced by a standard water-cooled condenser. I he ammonia is evaporated by allowing the stirred reaction mixture to warm to room temperature this takes several hours iti(l it is convenient to have it occur overnight. 

Water chiller A water-cooling device operating either by the direct expansion of a refrigerant by an absorption system or by evaporative cooling. 

Preparation of 18,20-Cyclo-5a-pregnane-3, 20-diol 3-Acetate ° A solution of 5 g of 3j9-hydroxy-5oc-pregnan-20-one 3-acetate in 1000 ml of spectroscopically pure ethanol is irradiated with a 250 Watt Philips Biosol A mercury high pressure lamp No. 10/27 through a cental water cooled pyrex jacket under nitrogen for 4 hr. The solvent is then evaporated under reduced pressure and the residues from 2 such reactions are combined and chromatographed on 300 g of neutral alumina (activity II). 

Irradiations of Testosterone Acetate (114), —In t-Butanol. 1.25 g of (114) in 250 ml t-butanol is irradiated for 32 hr at 30° under nitrogen with a Hanau Q81 high-pressure mercury lamp placed in a central water-cooled Pyrex immersion well with acetone filter. The solvent is evaporated in vacuo and the residue chromatographed on 125 g silica gel with benzene-ethyl acetate (4 1) to yield 0.29 g 17 -hydroxy-la,5 -cyclo-10a-androstan-2-one acetate [(118) 23%] mp 164-165°, after crystallization from acetone-hexane [a]i3 37 (CHCI3) 0.14 g cyclopentanone (120) (11%) mp 106-107° [aJo 38° (CHCI3) and 0.58 g starting material [(114) 46%]. Ratio (118) (120) - 2 1. 

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. 

Reduction of pressure here will cause liquefied gas to evaporate and cool and may freeze the water in the tubes. 

The mixture is decanted into an Erlenmeyer flask, the residual green salts are washed with two 15-ml portions of acetone, and the washings are added to the main acetone solution. Cautiously, sodium bicarbonate (approx. 13 g) is added to the solution with swirling until the pH of the reaction mixture is neutral. The suspension is filtered, and the residue is washed with 10-15 ml of acetone. The filtrate is transferred to a round-bottom flask and concentrated on a rotary evaporator under an aspirator while the flask temperature is maintained at about 50°. The flask is cooled and the residue transferred to a separatory funnel, (If solidification occurs, the residue may be dissolved in ether to effect the transfer.) To the funnel is added 100 ml of saturated sodium chloride solution, and the mixture is extracted with two 50-ml portions of ether. The ether extracts are combined, washed with several 5-ml portions of water, dried over anhydrous magnesium sulfate, and filtered into a round-bottom flask. The ether may be distilled away at atmospheric pressure (steam bath) or evaporated on a rotary evaporator. On cooling, the residue should crystallize. If it does not, it may be treated with 5 ml of 30-60° petroleum ether, and crystallization may be induced by cooling and scratching. The crystalline product is collected by filtration and recrystallized from aqueous methanol. 4-r-Butylcyclohexanone has mp 48-49° (yield 60-90 %). 

A mixture of 10.5 g of 1,4steam bath for 4 hours during which 2.0 g of methylmercaptan was collected in a dry ice bath connected to the reaction flask through a water cooled reflux condenser. The reaction mixture was then evaporated at 15 mm pressure to a solid residue which was then dissoived in 80 ml of 50/50 methanol-ethanol. The solution was filtered and evaporated to approximately 50 ml volume and allowed to cool and crystallize, giving a crop melting at 213.5°C to 215°C of 1,4[Pg.743]

The following procedure is given in U.S. Patent 3,458,528 78 grams (0.675 mol) of 5-nitroimidazole is dissolved in 1,500 ml of acetic acid upon the addition of 72 ml (0.57 mol) of boron trifluoride etherate. 175 ml (3.5 mols) of ethylene oxide in 175 ml of hexane, in a dropping funnel topped with a cold finger, is added slowly over 1 hour to the above solution maintained at 32° to 35°C with a water cooling bath. The mixture is concentrated under high vacuum to 100 to 150 ml volume. The residue is diluted with 500 ml of water, neutralized to pH 7 with aqueous sodium hydroxide, and extracted with 1.5 liters of ethyl acetate. The extract is dried and evaporated to yield 1-(2 -hydroxyethyl)-5-nitroimidazole. 

Preparation of Diethylphenylacetonitrile 25 grams of sodium was dissolved in 300 ml liquid ammonia containing 0.3 gram ferric chloride and 59 grams phenylacetonitrile was added slowly with stirring. After about 15 minutes a cooled solution of 80 grams of ethyl chloride in 200 ml dry ether was added and the mixture stirred for 1 hour. The ammonia was then allowed to evaporate, water added and the ether layer separated, dried, concentrated and the residual oil distilled in vacuo to yield diethylphenylacetonitrile as an oil,... 

---