Purify The Natural Gas Using 3A, 4A ,5A Or 13x Zeolite Molecular Sieves
The demand for using molecular sieves in the natural gas industry has been increased to the great extent due to their higher adsorption ability at the most competitive price. To prevent corrosion, the formation of hydrate and freezing of gas molecules in cryogenic equipment, it is required to remove the impurities in order to supply highly pure natural gas to the processing plants. For natural gas purification/separation, different types of molecular sieves such as 3A, 4A, 5A &13X are used depending on the pore size and molecule diameter.
These molecular sieves in the form of beads and pellets are available to absorb water and other compounds while avoiding the formation of carbon dioxide.3A, 4A, 5A &13X acts as a drying agent that offers highly beneficial and selective adsorption properties to obtain a purified gas. The use of these adsorbents is widely spread for the contaminant separation from natural gas. The mixture of gases or compounds with water is passed through the beads or pellets series of 3A, 4A, 5A &13Xto for the separation due to sieving effect. These molecular sieves are used depending on the molecule diameters, bulk density, crushing strength, static water adsorption as well as water content. For natural gas purification/separation, these adsorbents play a great role in obtaining the desired industrial gas which can be used for various applications.
|Natural Gas and Petroleum Drying Molecular Sieve Type A Typical Physical Properties|
|Item||Unit||4*6 Mesh||3*5 Mesh|
|Bulk Density||g/ml ≥||0.65-0.80||0.65-0.80|
|Equilibrium Water Capacity @ 25℃||wt% ≥||19.0-21.0||19.0-21.0|
|Heat of Adsorption||BTU/lb of H2O||1800||1800|
|Crush Strength||Point Contact||N ≥||80-130||80-130|
|Attrition Rate||wt% ≤||0.1||0.1|
|Size Qualification||% ≥||98||98|
|Package Moisture||wt% ≤||1.5||1.5|
|The interval value of the indexes above are on the basis of the different grade of Natural Gas and Petroleum Desiccant A|
Regeneration in typical cyclic systems constitutes removal of the adsorbate from the molecular sieve bed by heating and purging with a carrier gas. Sufficient heat must be applied to raise the temperature of the adsorbate, the adsorbent and the vessel to vaporize the liquid and offset the heat of wetting the molecular-sieve surface. The bed temperature is critical in regeneration. Bed temperatures in the 175-260° range are usually employed for type 3A. This lower range minimizes polymerization of olefins on the molecular sieve surfaces when such materials are present in the gas. Slow heat up is recommended since most olefinic materials will be removed at minimum temperatures; 4A, 5A and 13X sieves require temperatures in the 200-315 °C range.
After regeneration, a cooling period is necessary to reduce the molecular sieve temperature to within 15° of the temperature of the stream to be processed. This is most conveniently done by using the same gas stream as for heating, but with no heat input. For optimum regeneration, gas flow should be countercurrent to adsorption during the heat up cycle, and concurrent (relative to the process stream) during cooling. Alternatively, small quantities of molecular sieves may be dried in the absence of a purge gas by oven heating followed by slow cooling in a closed system, such as a desiccator.