Hi Amad,
Unfortunately I cannot help you in sizing of filter, but as far as I understand filter selection is best left to the Vendor. Usually its a proprietary item and Vendors will not compromise even if you exhibit your calculations.
Vendors have their own designs for the cartridges. In fact the data given by you in the above post can lead to different diameters and sizes of the filter, which are dependent upon the number of filter elements being used and the size of each cartridge. You also need to specify the change out frequency because this will be a measure of over design which the Vendor incorporates in his own design. Change out time is related to your plant availability and hence needs to be conveyed to the Vendor.
I also assume that there is no liquid present in this gas, because if its present you need to provide space for liquid drop out. You may also need to go for a filter coalescer, wherein the design becomes still more critical.
I would suggest to send your query to multiple Vendors and then compare.
Regards,