HEATING SYSTEM WITH A SECTIONWISE CONTROLLABLE HEAT SUPPLY FOR PAPER WEBS IN A RUNNING STATE

Abstract: System with a heating element of a sectional structure over which webs of paper or paper product are led so that webs with a crosswise difference in moisture content will be heated per section and in such a way that a flat paper web or paper product is obtained.

Description: Heating system with a sectionwise controllable heat supply for paper webs in a running state. The invention comprises a system with a heating element of a sectional structure over wnich webs of paper or paper product are led so that webs with a crosswise difference in moisture content will be heated per section and in such a way that a flat paper web or paper product is obtained. It is a known fact that due to the manufacturing process or storage of the paper an unequal moisture distribution will take place in the paper web. It has become apparent that this phenomenon occurs streakwise. Deterioration of the convertib lity and quality of the final product will be the consequence. Customary is to heat the web by means of drum-type cylinders filled with pressurized steam, against which the paper is guided and subsequently corrected through water sprays or nozzles as described amongst others in EP-B-0042497. Apart from the known steam drums, there are also other heating systems known and specified as f.i. in Dutch patent application no. 7307303. The subject system is meant to improve the quality of the final product by remedying the defect of wet streaks through a sectionwise heat control . After the paper or paper web has passed the system, the remaining moisture has been equally distributed across the width of the web. The application is explained by means of Fig. 1. The installation is illustrated in perspective by Fig. 1. Paper web 1 is guided under guide roller 2 over a number of heating plates 3 which are mounted next to one another across the width of paper web 1. Each heating plate 3 has a steam supply 4 which can be controlled by control valves 5 or by automatically activated valves. By apolying more steam or less, the temperature of the heating plates will increase or decrease. Guide roller 2 will take care that paper web 1 will be brought in a more close or less close contact with heating plates 3. Guide roller 2 can be moved up and down by threaded spindle 6 and threaded bushing 7 which are mounted on both sides of the system. Threaded spindle 6 is driven by an electromotor mounted on one side of the system and this motor will also drive the other spindle crosswise by means of " intermediate shaft 9. ' All condensate drains are connected with the steam system via a steam trap. Figure 2 is a schematic representation of a double backer where only some rollers 11 and 1 section are outlined. It may be remarked that this machine can hold a number of sections, depending on the desired final results. According to figure 2 similar heating plates 3 have been mounted at the upper side of the corrugated board 14 and conveyor belt 10. By means of air-pressure control system 12 and a mechanical connection 13, conveyor belt 10 and heating plates 3 can be pressed upon each other with a varying intensity. Through the pressure of the plates, sectionwise controllable heat transfer will take place in the longitudinal direction of the web. Figure 3 shows a cross-section of the situation. The maximum working pressure of heating plates 3 is + 16 Bar of steam.

Claims: CLAIMS 1. System for thermal treatment of running webs of fibrous material, such as paper or paper product, c h a r a c t e r i z e d that the fibre web to be heat-treated will be guided over a number of heating elements positioned side by side in the direction of the paper line and of which the temperature is adjustable (controlled) per element. 2. System according to claim 1, c h a r a c t e i z e d that the heating elements 3 are positioned in the direction of the paper line in a somewhat arched fashion. 3. System according to claim 1, c h a r a c t e r i z e d that the elements have a dual heating surface to be able to radiate at both upper and lower sides. 4. System acoording to claim 1-3, c h a r a c t e r i z e d that the moisture in the web will evaporate through the heat supply to the paper. 5. System according to claim 1-3, c h a r a c t e r i z e d that guide or idler rollers are present to control the effective length of the heating surface. 6. System according to claim 1-3, c h a r a c t e r i z e d that heating will take place by means of steam of which the pressure will be varied per section. 7. System according to claim 1-3, c h a r a c t e r i z e d that the heating elements are electrically heated.

Inventors: ALSEMA CORNELIS HENDRIKUS, ALSEMA, CORNELIS, HENDRIKUS
Applicants: ALSEMA CORNELIS HENDRIKUS, ALSEMA, CORNELIS, HENDRIKUS
Application year: 1987
Main classification: D21F5
IPC codes: B31F1, D21F5, D21F7