Ejectors Surface condenser

Vacuum Distillation - Heavier fractions from the atmospheric distillation unit that cannot be distilled without cracking under its pressure and temperature conditions are vacuum distilled. Vacuum distillation is simply the distillation of petroleum fractions at a very low pressure (0.2 to 0.7 psia) to increase volatilization and separation. In most systems, the vacuum inside the fractionator is maintained with steam ejectors and vacuum pumps, barometric condensers, or surface condensers. 

Example 6-9 Ejector Load For Steam Surface Condenser... 

A surface condenser condensing the steam from a process turbine drive operates at 1.0 in. Hg abs. The condensing load is 85,000 Ibs/hr steam. WTat is the capacity of the ejector ... 

Air/water vapor mixture, chart, 364,365 Air/water vapor, 359 Capacity at ejector suction, 369 Capacity for process vapor, 362 Evacuation time, 371, 380 Load for steam surface condenser, 367 Non-condensables, 362, 363 Size selection, 371 Steam pressure factor, 373 Steam requirements, 372 Steain/air mixture temperature, 361 Total weight saturated mixture, 362 Capacity, 358 Discharge, pressure, 358 Effect of excess steam pressure, 358 Effects of back pressure, 359 Effects of wet steam, 356 Inter-and-after condenser, 351 Load variation, 370 Materials of construction, 347 Molecular weight entrainment, chart, 360 Performance, 358, 370, 375 Relative comparison, 357... 

The efficiency of the condenser is reduced by poor air removal (and the presence of other noncondensable gases), so surface condensers usually are equipped with vacuum pumps but also may incorporate older style, single or multistage multielement, steam-jet air ejectors. Under most normal operations, the residual oxygen level is below 20 to 40 ppb 02. 

Condensers and vacuum pumps will be needed for evaporators operated under vacuum. For aqueous solutions, steam ejectors and jet condensers are normally used. Jet condensers are direct-contact condensers, where the vapour is condensed by contact with jets of cooling water. Indirect, surface condensers, are used where it is necessary to keep the condensed vapour and cooling water effluent separate. 

Figure 7.30. Arrangements of two-stage ejectors with condensers, (a) Identification of the parts of a two-stage ejector (Croll-Reynolds Co.). (b) A two-stage ejector with interstage barometric condenser (Elliot Co.), (c) A two-stage ejector with surface condensers interstage and terminal (Elliot Co.).

Steam surface condenser and ejector data sheet (4 pp.) 693... 

A two-stage steam ejector with one surface condenser to handle 2001b/hr of air at 25 Torr, in carbon steel construction. From Table 21.3 the installation factor is 1.7. 

Two SJEs are installed in parallel on the surface condenser (Figure 11.10), mainly to remove air leakage and uncondensed gases/vapour (50 kg/h of dry air and 373 kg/h of water vapour). The two ejectors require 1254.7 kg/h of MP steam, which after use is condensed by... 

Figure 11.10 Surface condenser installed with steam jet ejectors values shown are the current operating conditions.

The condensation unit consists of a surface condenser, condensate pumps of the modular desalinating plant, air-ejectors, special valves, fittings and piping. 

I did not understand thermodynamics at university. It seemed to be an exotic subject with no relevance to my future as a refinery process engineer. It wasn t until I had spent many years working with steam turbines, surface condensers, steam distribution systems, and most especially vacuum ejectors that I realized that without a firm understanding of thermodynamics, I could not operate or troubleshoot such facilities with any degree of confidence. 

Figure 20.3 Steam nozzle used in a large power generator surface condenser first-stage steam ejector vacuum system.

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