method for optimization of verdampfungstrocknung paper, speed, and a dryer section of a paper machine and paper for the implementation of the procedure

摘要

A method and an equipment for evaporation drying of the paper web that comes from the press section (10) of a paper machine. The method consists of three successive stages I, II and III that are carried out in the direction of progress of the web (W) as follows: (I) in the first stage, the paper web coming from the press section (10) of the paper machine is heated in a short section (L1) of the paper machine in the machine direction quickly to a temperature of 55...85 DEG C, and web breaks of the relatively moist and, thus, weak web (W) are minimized; (II) after the first stage (I), the main evaporation drying of the web (W) is carried out so that the evaporation efficiency (PE) and the rate of increase in the dry solids content (KA) of the web (W) are substantially higher than in the first stage or in the final stage (III), and the web temperature (TW) does substantially not rise while the drying proceeds (Fig. 4); (III) in the final stage, the drying is continued with a decreasing evaporation efficiency (Fig. 3) and with such an average rate of increase in the dry solids content (KA) of the web (W) in the machine direction as is lower than in the preceding stage (II) but higher than in a conventional cylinder drying with single-wire draw so that the paper quality can be controlled at the same time.