Condenser spray

N2, and traces of PH, CO2, E, and S large furnaces generate off-gas at a rate of about 120—180 m /min. In most installations the off-gas is passed through a series of Cottrell electrostatic precipitators which remove 80—95% of the dust particles. The precipitators ate operated at temperatures above the 180°C dew point of the phosphoms. The collected dust is either handled as a water slurry or treated dry. Einal disposal is to a landfill or the dust is partially recycled back to the process. The phosphoms is typically condensed in closed spray towers that maintain spray water temperatures between 20 and 60°C. The condensed product along with the accompanying spray water is processed in sumps where the water is separated and recycled to the spray condenser, and the phosphoms and impurities ate settled for subsequent purification. 

Contact Condensers Spray condensers, jet condensers, and barometric condensers all utihze water or some other hquid in direct contacl with the vapor to be condensed. The temperature approach between the liquid and the vapor is veiy small, so the efficiency of the... 

Most of the generated vapour is condensed in spray condensers which are equipped with circulation pumps and an EG cooler. The vapour that is still uncondensed is withdrawn from the gas phase with the help of a vapour jet which is located down-stream behind the spray condenser and generates the necessary vacuum in the reaction zone. The most critical part of the spray condenser system is the end of the pipe leading the vapour from the prepolycondensation reactors and the finishers into the spray condenser. The transition from a hot to a cold environment causes deposition of solid material onto the cold walls which has to be removed manually or by means of a mechanical scraper. 

Process vapours from the esterification reactors and EG from the EG-vapour jet, as well as from the vacuum stages of the spray condensers, are purified in the distillation unit. The distillation unit commonly consists of two or three columns and is designed for continuous operation. The purified EG is condensed at the top of the third vacuum rectification column and returned to the process via a buffer tank. Gaseous acetaldehyde and other non-condensables are vented or burned and high-boiling residues from the bottom of the third column are discharged or also burned. 

Other results on heat transfer in a large spray condenser are given by Waintraub et al. ( Removing Packings from Heat Transfer Sections of Vacuum Towers, AIChE 2005 Spring National Meeting, Proceed-... 

Contact Condensers Spray condensers, jet condensers, and barometric condensers all utilize water or some other liquid in direct contact with the vapor to be condensed. The temperature approach between the liquid and the vapor is very small, so tne efficiency of the condenser is high, but large volumes of the liquid are necessary. If the vapor is soluble in the liquid, the system is essentially an absorptive one. If the vapor is not soluble, the system is a true condenser, in which case the temperature of the vapor must be below the dew point. Direct-contact condensers are seldom used for the removal of organic solvent vapors because the condensate will contain an organic-water mixture that must be separated or treated before disposal. They are, however, the most effective method of removing heat from hot gas streams when the recovery of organics is not a consideration. 

Spray condensers No Latent heat of vaporization Temperatures Flow rate Height to diameter ratio 70 1 12 1 20... 

A process column separates side reaction low boilers from the diol, which is then recycled back to the reaction. Spray condensers and vacuum units recover unreacted feedstock and recycle the diol, thus improving the economics of this process. 

Physical conditions greatly depend on the aggregate state of the continuous phase (vapor in spray and tray condensers, liquid in pool-type condensers, and liquid film on the solid surface in packed bed condensers). Design of the most frequently used spray condensers, featuring vapor condensation on the water droplets, depends on the heat and mass transfer phenomena involved with saturated vapor condensation in the presence of the subcooled liquid droplets of changing mass. The process is very complex. For further details on the problems involved, consult Refs. 116 and 118. Such designs involve a substantial input of empirical data. 

Another form of condenser frequently used in chemical industry is the spray condenser. This is a modified form of spray absorber or scrubber in which cold water is sprayed into a stream of vapour to cool it and to flush away the resultant condensate. This is usually employed in connection with water-sealed vacuum pumps. 

Figure 22-1 Spray condenser showing method of angling the spray nozzles to give good spray coverage, and recycling of theproduct.

Design Basis Fission product containment Containment of PS type containment spray condensation pool cooling passive active active The surrounding reactor building serves as a secondary containment, kept at a below-atmospheric pressure, ventilation exhaust air passes through filters... 

Often these condensers have internal structures to create a better distribution of the coolant, so that the liquid surface is as large as possible. In spray condensers, nozzles are used for a good distribution of the coolant. 

Spray condensers (Figure 3.5). Here condensate is recirculated through... 

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