摘要:

Drying of thin paper sheet on a Yankee cylinder equipped with a steam heated high velocity hood is examined. When possible infiltration of air from the surroundings is considered, then the process is fully determined by twelve variables. One of these can be chosen as an independent variable. An equation group of eleven equations is derived. The method of solution is iterative. Finally, a numerical demonstration example is presented.

ISSN:0737-3937    

DOI:10.1080/07373938508916265

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The paper presents a turbulence model based on the Kolmogorov-Prandtl hypothesis. The model is applied for determining the heat transfer coefficient of an aerofoil dryer. The differential equations of the turbulent flow are described as well as their numerical solution. Comparions between the theoretical and experimental values show that the turbulence model gives satisfactory results.

ISSN:0737-3937    

DOI:10.1080/07373938508916266

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The effect of the dryer cylinder diameter on the dryer specific evaporation rate is examined theoretically. It is observed that, in the range of cylinder diameters applicable in practice, the dryer specific evaporation rate is nearly independent of the selected cylinder diameter when the dryer geometry remains unchanged. In practice, however, the dryer geometries have changed slightly according to the cylinder diameter.

ISSN:0737-3937    

DOI:10.1080/07373938508916267

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The optimal nozzle-to-plate spacing is experimentally studied for the case when a free jet of high temperature gas impinges normally on a large flat plate. The stagnation-point heat transfer becomes maximal when the flat plate is placed at the end of the potential core region. A generalized model is proposed which permits prediction of the optimal nozzle-to-plate spacing and stagnation-point heat flux over a wide range of the initial density ratio.

ISSN:0737-3937    

DOI:10.1080/07373938508916268

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The continuously increasing paper machine speeds and widths have contributed to the growing importance of dryer section runnability. To obtain an optimal way of operating the dryer section, the papermakers can have access to dryer section surveys performed by machine manufacturers and suppliers of ventilation equipment and dryer fabrics. In the last years also the use of computer simulation has increased. It strengthens the reliability of given recommendations and multiplies the benefits gained from the survey by enabling the valuation of even completely new running situations.

ISSN:0737-3937    

DOI:10.1080/07373938508916269

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

It is well known in the drying of paper that it is possible reduce the size of the dryer section and/or increase the drying capacity by using vacuum. Furthermore a smaller dryer section contributes to a decrease in the energy losses. However, the use of Minton vacuum dryers in the late 20's was never really successful. Especially with increasing machine speeds maintenance became a problem.

ISSN:0737-3937    

DOI:10.1080/07373938508916270

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The origins of poor CD (cross machine) moisture profiles In tissue production are discussed generally. CD line force distribution at the first and second presser roll has a significant influence on the CD moisture profile. The crowning of cylinder and presser rolls compensates for the deformation of the Yankee cylinder shell (due to nip load, internal steam pressure and hood operating conditions) and of the presser rolls but only for any one given operating condition. However, during operation the parameters often have to be varied. in a sensitivity analysis the resulting CD line force deviations were calculated and typical figures are given here to demonstrate the relative effect. The shape of the resulting line load curves are drawn and from these the typical shape of the resulting CD moisture- profile can be derived. Means for possible control such as controllable presser rolls, sectionally adjustable hoods and steam boxes as well as eddy current and infra-red -heating are discussed and evaluated.

ISSN:0737-3937    

DOI:10.1080/07373938508916271

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A mathematical model is presented to predict the drying rates and energy consumption for the process of impingement steam drying of paper during the constant-rate drying period. Preliminary experiments have verified the validity of the simulation model. The predicted results show consumption may be as low as 640 kJ/kg water evaporated while hot air Yankee dryers typically consume 5020 to 7100 kJ/kg water evaporated

ISSN:0737-3937    

DOI:10.1080/07373938508916272

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor