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Tham khảo tài liệu 'evaporation condensation and heat transfer part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 550 Evaporation Condensation and Heat Transfer Fig. 4.4 Four phases of drying with conventional double tier configuration. 5. Steam and condensate system In modern paper machines there are several points in the steam and condensate system. These include dryers steam box pocket ventilation equipment roll handling wire pit and process water heating and machine room ventilation. In terms of paper drying the main steam and condensate consumption points are the dryer section and pocket ventilation as heat energy required to dry paper are sourced from dryer cylinders and hot ventilation air. The basic requirements and objectives of the steam and condensate system are to allow maximum unrestricted drying of the paper with a gradual increase in cylinder surface temperature from the wet end to the dry end provide drying control for machine operator remove air and non-condensibles provide maximum condensate removal at all paper machine speeds economic utilization of steam provide uniform reel moisture and provision of sheet breaks differential and control. Figure 5.1 shows the basic steam and condensate system of a commercial paper machine. There are a number of variations in steam and condensate system depending upon the machine design. In fact every paper machine has its own unique steam and condensate Fundamentals of Paper Drying - Theory and Application from Industrial Perspective 551 system. The design of steam and condensate system is influenced by available steam pressure machine speed grammage or basis weight range sheet dryness after the press section and quality requirements of the finished products. The steam and condensate systems for different paper grades are either cascade systems thermo-compressor systems or combinations of the two. Fig. 5.1 Basic steam and condensate system of a commercial paper machine. 5.1 Condensate behaviour In multicylinder paper drying system where steam is used as the source of heat energy the heat inside the cylinder is released by .