Procedure for drying of cellulose

Claim 1

In a method for drying of cellulose simultaneously in both a closed-hood web dryer and, in parallel working arrangement therewith, a flash drying plant, for disintegrated cellulose, wherein said closed-hood dryer is mounted in a machine shop and is connected to exhaust one portion of its discharged wet air through three serially connected heat exchangers for removing the heat from said portion of the air from the closed dryer before exhausting said portion to atmosphere and to exhaust a second portion through a fourth heat exchanger, ducts for the supply of pre-heated ventilating air to the machine building, connecting ducts for the removal of used ventilating air from said machine building and transferring it to said flash drying plant, said plant comprising a plurality of drying stages for the drying of disintegrated cellulose pneumatically in a stream of heated gaseous drying medium, a heating means for heating said drying medium, said fourth heat exchanger being connected for supplying warmed air to said heating means, a disintegrating device for the cellulose to be dried in said flash drying plant, a wet stage for the pre-heating and dewatering of the disintegrated cellulose in a stream of drying medium recycled form the last dryIng stage before the introduction of said disintegrated cellulose to the first drying stage,means for cooling the dried cellulose leaving the last drying stage, and a compacting means for forming of cooled cellulose into standardized packages of dried cellulose, the improvement comprising the steps of: conducting a first portion of the hot air from the closed hood web dryer and passing said air serially through the first of said serial heat exchangers, the second of said heat exchangers and the third of said heat exchangers and then venting said portion of hot air to the atmosphere, conducting fresh ventilating air through said third heat exchanger and supplying the heated ventilating air to the machine shop, passing water through said second heat exchanger to produce hot water, conducting a portion of the air from within the machine shop through said first heat exchanger to produce a hot drying medium and conducting this hot medium to the web dryer hood, conducting the remaining portion of the hot air from the closed hood web dryer through said fourth heat exchanger for supplying heat thereto so as to warm the air supply for said heating means of the dryer plant, heating said air in said heating means, thereby producing a heated gaseous drying medium for the drying stages, conducting the used ventilating air away from the machine shop, and mixing said used ventilating air with the heated gaseous drying medium from said heating means and producing a plurality of streams having ratios of drying medium to exhaust air such as to give a predetermined temperature and drying medium flow rate for each of said plurality of drying stages of said flash drying plant.