Condenser counterflow

Gegen-stoff, m. antisubstance, antibody antidote, -strahl, m. reflected ray, reflection. -Strom, m. countercurrent, inverse current, counterflow. -stromkiihler, m. countercurrent condenser or cooler, -stiick, n. counterpart, match. 

In the stripper/condenser, the gas is cooled by counterflowing condensate from the condenser. The temperature of the SO2 rich gas that leaves the condenser is used to control the amount of cooling medium that must be sent to the condenser. Condensate from the stripper is returned to the buffer mix tank. The SO2 rich gas, containing at least 90% SO2 with the remainder being water, is ready for transport to a process unit. In the refinery, this normally will be the SRU or acid plant, where it will be converted to elemental sulfur or sulfuric acid. The SO2 can also be compressed and transported if necessary. Eigure 16.9 shows a typical Belco LABSORB System. 

In 1974 the Atlantic City Electric Co. placed Unit 3 of its B L England Station into commercial operation. Condenser cooling for the unit is provided by circulating sea water in a closed-cycle, natural-draft system. The cooling tower selected for the site was a hyperbolic, counterflow unit. The thermal test instrumentation procedures and test data as well as drift measurement results are given. The paper indicates that the tower operates within design specifications for thermal performance and that it meets the environmental criteria regarding the drift. 

Fig. 1.3 (a) Natural draft, hyperbolic, counterflow tower (b) Natural draft, hyperbolic crossflow tower (c) Induced draft, crossflow tower (d) Induced draft, counterflow tower (e) Forced draft, galvanized, evaporative condenser (f) Induced draft, FRP, bottle tower. 

Ion exchange desalination - DESAL , SIROTHERM Membrane desalination - Reverse Osmosis, Electrodialysis Continuing fixed bed counterflow development Condensate polishing systems Ion Chromatography analysis, and Pellicular resins Polymeric adsorbents... 

The manner in which a heat exchanger is piped up can influence its performance. Horizontal units should have inlet and outlet nozzles on the top and bottom of the shell or channel. Nozzles should not be on the horizontal centerline of the unit. In general, fluids should enter the bottom of the exchanger and exit at the top, except when condensation occurs. Units are almost always designed to be counterflow and the piping must reflect this. When cocurrent flow has been specified, it is equally important that it be piped to suit. 

FIGURE 6.37 Schematic diagrams of spiral-plate heat exchangers (a, b) basic construction for two fluids in counterflow, (c) configured for condensation or reboiler service. 

In U.S. plants hydrofluorination is carried out in two stirred fluidized-bed reactors in series, with counterflow of solids and gases. The bed to which UO2 is fed and from which exhaust gases are discharged runs at 300°C, partially converts UO2 to UF4, and reduces the HF content of the effluent gases to around 15 percent. The bed to which anhydrous HF and the partially converted UO2 are fed runs at 500°C and converts more than 95 percent of the UO2 to UF4. To prevent caking of the fluidized beds, it has been found necessary to provide each reactor with a vertical-shaft, slow-speed stirrer to scrape the reactor walls. Production rates around 700 to 900 kg/h are obtained in 0.75-m-diameter reactors. Effluent gases are filtered to remove entrained solids, cooled to condense aqueous HF, and scrubbed to remove the last traces of HF. 

If there were just a small curvature for the condensing fluid, the zones would be figured as a counterflow exchanger and then the normal overall correction factor would be used in each zone. This assumes the correction factor for each zone is the same as the overall. 

With a large hump in the condensing curve, you cannot apply the same correction factor to each zone nor can you take each counterflow zone and calculate a correction factor fi om the counterflow temperatures. This would give an inaccurate At, particularly in the low At zone next to the shell outlet. 

The vapor stream from the meal and oil distillation systems consists of solvent vapor, water vapor (from the stripping steam) and air that has entered the system entrained in the voids of the press cake. Some additional air unavoidably gains entry into the vacuum systems. The vapor stream from the final condenser consists of air saturated with solvent and water vapors. The solvent vapors are selectively scrubbed in a packed tower by a counterflow of special mineral oil. The mineral oil is recycled after being heated, stripped of solvent, and cooled. The hexane vapor remaining in the vent stream should be below the lower explosive limit (1.3% by volume). Nevertheless, overall rapeseed plant losses per tonne flow through the extractor are typically much higher than they are for soybeans. This problem should be researched and, if possible, overcome. 

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