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Application :
a, Drying and removing of CO2 from natural gas , LPG , air , inert and athmospheric gases , etc .
b, Removal of hydrocarbons , ammonia and methanol from gas streams ( ammonia syn gas treating)
c, Special typs are used in the air break units of buses , trucks and locomotives .
d, Packed in small bags , it may be used simply as a packing desiccant .
Molecular sieve 4A is an alkali alumino silicate , it is the sodium form of the type a crystal structure . 4A molecular sieve has an effective pore opening of about 4 angstroms (0.4mm) . Dohntec type 4A Molecular Sieve will adsorb most most molecules with a kinetic diameter of less than 4 angstroms and exclude those larger . Such adsorbable molecules include simple gas molecules such as oxygen , nitrogen , carbon dioxide and straight chain hydrocarbons . Branched chain hydrocarbons and aromatics are excluded .
Na2O . Al203. 2SiO2. 4.5H2O
SiO2:Al2O3≈2
Technical Parameter
Item | Unit | Technical data | |||
Shape |
| Pellet | Sphere | ||
Diameter | mm | 1.5-1.7 | 3.0-3.3 | 1.7-2.5 | 3.0-5.0 |
Size ratio up to grade | % | ≥98 | ≥98 | ≥96 | ≥96 |
Bulk density | g/ml | ≥0.68 | ≥0.68 | ≥0.68 | ≥0.68 |
Wear ratio | % | ≤0.20 | ≤0.25 | ≤0.20 | ≤0.20 |
Crushing strength | N | ≥30/cm | ≥45/cm | ≥30/piece | ≥70/piece |
Static water adsorption | % | ≥20.5 | ≥20.5 | ≥21 | ≥21 |
Static methanol adsorption | % | ≥15 | ≥15 | ≥15 | ≥15 |
Water content, as shipped | % | ≤1.5 | ≤1.5 | ≤1.5 | ≤1.5 |
Regeneration
Dohntec molecular sieves 4A can be regenerated by either heating in the case of thermal swing process , or by lowering the pressure in the case of pressure swing process .
To remove moisture from a 4A molecular sieve , a temperature of 250-280°C is required . A properly regenerated molecular sieve can give moisture dew points below -100°C .
The outlet concentrations on a pressure swing process will depend on the gas present , and on the conditions of the process .
4A molecular sieves