Paper or board machine with at least one drying unit for drying a paper or board web

摘要

The invention concerns a paper or board machine comprising at least one drying unit (Rn) for drying a web (W) of paper or board. The drying unit comprises a loop of a drying wire (32a), a large-diameter impingement-drying and/or through-drying cylinder (31), which is fitted inside the loop of the drying wire (32a), a first and a second smooth-faced, heated contact-drying cylinder (30) fitted outside the loop of the drying wire (32a), and a blow hood (35). <??>The contact-drying cylinders (30) have a diameter D2 smaller than the diameter D1 of the impingement-drying and/or through-drying cylinder (31) and are placed on top of and in the vicinity of the impingement-drying and/or through-drying cylinder (31) at both sides thereof. <??>The contact sector b of the impingement-drying and/or through-drying cylinder (31) over which the web is arranged to pass supported on the outer face of the drying wire (32a) is b > 180 DEG , and the blow hood (35) covers the impingement-drying and/or through-drying cylinder (31) substantially over the entirety of said contact sector. <??>The impingement-drying and/or through-drying cylinder (31) is substantially fitted in a basement space (KT) provided underneath the floor level (K1-K1) of the paper or board machine hall, and the central axes of the contact-drying cylinders (30) are placed in the vicinity of, or above, the floor level (K1-K1) of the paper or board machine hall. The blow hood (35) is open or openable at its bottom so that the removal of broke out of connection with the impingement-drying and/or through-drying cylinder (31) takes place substantially by the force of gravity. <IMAGE>