The packed bed of fixed packing elements acts as a gas distributor, as well as causing good gas/liquid contact, to provide an even flow of gas across {HEAD ~ essentially the entire cross sectional area} of {TAIL ~ the packed bed} of mobile packing elements 
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The packed bed of fixed packing elements acts as a gas distributor , as well as causing good gas / liquid contact , to provide an even flow of gas across { HEAD ~ essentially the entire cross sectional area } of { TAIL ~ the packed bed } of mobile packing elements
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH