Separation pressure and

A vessel may be subject to more than one condition under different failure scenarios. For example, a low pressure separator may be subject to blocked discharge, gas blowby from the high pressure separator, and fire. Only one of these failures is assumed to happen at any time. The relief valve size needs to be calculated for each pertinent relieving rate... 

Fig. 18.16. Hydrotreating—Chevron Lummus Global LLC. Includes reactor (1), hot high pressure separator (2), hot low pressure separator (3), cold high pressure separator and product fractionator (4). (Source Hydrocarbon Processing, 2004 Refining Process Handbook. CD-ROM. September 2004 copyright 2004 by Gulf Publishing Co., all rights reserved.)...

Unreacted NH3 and CO2 are separated from the urea solution in the high-pressure separator and in two to three steam-heated carbamate strippers at successively lower pressures. The off-gas from the separator and the first-stage stripper is absorbed in the high-pressure absorber by a side stream of partially stripped reactor effluent from the high-pressure separator. Heat evolved in the absorber reaction is removed (to increase absorption capacity) by the addition and expansion of part of the liquid ammonia feed at this point. Pure gaseous ammonia from the top of the absorber is also recycled to the urea reactor after being condensed. 

High pressure separator and turboexpander designs are highly dependent on vapor-liquid equilibrium K-values. Variation in K-values is examined by selecting a common basis (Property-75) for enthalpy/entropy calculations. 

The total effect of the high pressure separator and the turboexpander flash calculations is shown by the estimated ethane recovery in Table IV which varies from 82.1% to 88,4%. The estimated propane recovery for all cases is 99+%. 

After polymerization, the reacting mass is transferred to a high-pressure separator (150-200 atm). The polymer-rich stream withdrawn from the bottom of the high-pressure separator undergoes a second separation step at near-atmospheric pressures in a low-pressure separator. The phase separation in the high-pressure separator and in the separators of the recycle line makes it possible to remove the polymer or wax from the mixture. To improve the separation efficiency, the pressure or the temperature in the separators must be decreased. Then, the recycle gas contains only traces of wax, and a lower amount of ethylene remaias dissolved in the polymer melt from the high-pressure separator. 

Step 1 define process type (single-stage or two-tage), number of reactors of each stage and the corresponding reaction beds, number of high-pressure separator and if amine treatment is included in the model. 

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