Cooling recycling

The reactor effluent might require cooling by direct heat transfer because the reaction needs to be stopped quickly, or a conventional exchanger would foul, or the reactor products are too hot or corrosive to pass to a conventional heat exchanger. The reactor product is mixed with a liquid that can be recycled, cooled product, or an inert material such as water. The liquid vaporizes partially or totally and cools the reactor effluent. Here, the reactor Teed is a cold stream, and the vapor and any liquid from the quench are hot streams. 

AU industrial operations produce some wastewaters which must be returned to the environment. Wastewaters can be classified as (1) domestic wastewaters, (2) process wastewaters, and (3) coohng waste-waters. Domestic wastewaters are produced by plant workers, shower facihties, and cafeterias. Process wastewaters result from spills, leaks, and product washing. Coohng wastewaters are the result of various cooling processes and can be once-pass systems or multiple-recycle cooling systems. Once-pass coohng systems employ large volumes... 

Recycling and Reuse 9. Recycle cooling water and treated wastewater to the extent feasible. 10. Recover and reuse spent solvents and other chemicals to the extent feasible. 

Even if the reactor temperature is controlled within acceptable limits, the reactor effluent may need to be cooled rapidly, or quenched, for example, to stop the reaction quickly to prevent excessive by product formation. This quench can be accomplished by indirect heat transfer using conventional heat transfer equipment or by direct heat transfer by mixing with another fluid. A commonly encountered situation is one in which gaseous products from a reactor need rapid cooling and this is accomplished by mixing with a liquid that evaporates. The heat required to evaporate the liquid causes the gaseous products to cool rapidly. The quench liquid can be a recycled, cooled product or an inert material such as water. 

FC = IF TIME > = TIMEfail THEN 0. 0 ELSE FCl conditional recycle cooling flow ... 

Use of recycling cooling towers to replace a once-through cooling system. 

Recycling Cooling and Chilling Equipment Energy Prasad, Anil Fitzgerald, John... 

Rectifying stages (Fig. 2.36) concentrate the more-volatile components in a vapor stream. A liquid recycle condenses the less-volatile components from the rising vapor. To generate the liquid recycle, cooling is applied to condense a portion of the overheed vapor. The liquid recycle is termed reflux. 

Gaseous emission from phosphoric acid plants can be scrubbed with cool contaminated recycle cooling water to relatively low emission levels. However, to minimize cooling tower or cooling pond emission, fluorine recovery often is necessary on those streams that have a significant fluorine content. 

Polypropylene was produced in three reaction trains on a location that employed nearly 300 workers. A recycle cooling line on a Reactor in Train A plugged with product slurry. This was considered a regular occurrence. Standard procedures to address this plugged line required mechanics to work under the direction of operators to rod-out the... 

Gayev, Ye.A., Denisenko, A.I., and Asaturyan, A.Sh. (1990) Mathematical Modeling of Long Spray-Ponds for Cooling of Recycled Cooling Water of Conventional and Nuclear Power Plants Under Windless Conditions, Fluid Mechanics - Soviet Research, Vol. 19, No. 3, 66-75. 

In order to maintain maximum efficiency in recovery, the adsorbers are usually operated on a time cycle. This is adjusted to provide a reasonable factor of safety so that no solvent will be lost at the end of the cycle. Break-point control is used on recycle-cooling systems wherein the air leaving the first adsorber is subsequently passed through a second adsorber thus any vapor of a solvent that comes through the first bed is picked up by the second. This results in a substantial increase in the capacity of the bed and reduces the requirements for steam in the later stage of desorption. 

Considerable frictional heat is generated that must be removed to achieve low residual oil and prevent damage to the cake and oil. Some screw presses recycle cooled pressed oil over the cage to remove the heat, while others use water-cooled shafts and bar cages. 

Aqua ammonia is usually produced in a plant in wiiich anhydrous ammonia and water are continuously mixed with recycled cool aqua ammonia in a simple pipe-type mixing chamber. Erx>ugh water is added to adjust the liquid s edfic gra ity to that of aqua ammonia containing 20% nitrogen or other desired concentrations. -The-product-is usually cooled in a conventional heat exchanger or plate-type cooler. Usually a 45-tonne tank car of anhydrous ammonia can be converted to 187 tonnes of aqua ammonia in approximately 5 to 8 hours. The rate of converaon is dependent upon the cooling capacity of the plant. 

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