Adsorption cycles steam regeneration

Do not regenerate molecular sieves by steaming water typically is strongly adsorbed and may not be easily displaced by adsorbent in next adsorption cycle. 

The dmm filling operation operates on a 24-h/day basis and the adsorption units are operated on an 8-h adsorption, 5-h regeneration cycle, with 3 h for cooling and standby. The steam used during the 5-h regeneration cycle was determined to be 2725 lb (mass flow meter). 

As already mentioned, the adsorption of water vapors on the hydro-phobic Styrosorb 2 is extremely low, so that no more than 5% residual moisture remains in the sorbent beads after steam regeneration. Therefore, it is not necessary to dry the sorbent additionally before conducting the next sorption cycle. 

After steam regeneration, the bed is hot and wet and must be cooled by blowing with air. This will also remove much of the water present. Some of the water should remain on the bed, where it will in due course be displaced by the more strongly adsorbed solvent. This helps to keep the bed temperature low during the adsorption part of the cycle since the heat of desorption of the water is supplied by the solvent s heat of adsorption. 

Wet gas steam leak/leaky valves/inadequate regeneration/wrong adsorbent/ adsorbent damaged by excessive regeneration temperature/adsorption cycle too long/[early breakthrough]. ... 

First, the temperature of the activated carbon is increased to approx. 100°C. This temperature increase reduces the equilibrium load of the activated carbon. Further reduction of the residual load is obtained by the flushing effect of the steam and the declining toluene partial pressure. The load difference between spent and regenerated activated carbon - the working capacity - is then available for the next adsorption cycle. 

The use of active carbon beds to adsorb organic vapors with steam regeneration is primarily a TSA cycle however, desorption is aided by the displacement of organic compounds by water. The adsorbed water then serves to limit temperature rise in the bed during the next organic vapor adsorption step. 

Steps. Thermal-swing cycles have at least two steps, adsorption and heating. A cooling step is also normally used after the heating step. A portion of the feed or product stream can be utilized for heating, or an independent fluid can be used. Easily condensable contaminants may be regenerated with noncondensable gases and recovered by condensation. Water-iminiscible solvents are stripped with steam, which may be condensed and separated from the solvent by decantation. Fuel and/or air may be used when the impurities are to be burned or incinerated. 

MTZ (mass transfer zone). 500. 501 multicomponent data, 503 operating cycles, 502 operating parameters, 502 operating practices, 504 packed beds, 500-504 regeneration, 502, 504 regeneration steam, 502 Adsorption equilibria, 495,497... 

The technical application of high-silica molecular sieves without any non-framework aluminium as protective layer restricts the water loading of the stream in sorption processes. The use of supersaturated steam for the regeneration of the adsorbent is impossible since already after a few adsorption/desorption cycles the molecular sieve is totally damaged. However, adsorbents which are modified by surface alumination are remarkably more resistant against water. 

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