Validation of a Mathematical Model by Studying the Effects of Recirculation of Drying Gases

Ståhl, Magnus; Berghel, Jonas

doi:10.1080/07373930802046450

Cited by 18 publications

(6 citation statements)

References 13 publications

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“…Calculation indicates that the required heating tube area should be approximately 25 m 2 for installation in an existing rotary dryer (6.2 MW) to increase the drying capacity by 10%. [26] The use of heating tubes in a drying system changes the outgoing moisture content and thereby affects the production settings of the following process, for example, a pellet press. The outlet moisture content increases when the heating tube is turned on as well as when the inlet gas temperature is increased.…”

Section: Discussionmentioning

confidence: 99%

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The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer

Berghel

2011

Drying Technology

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Interest in the use of biofuels, such as pellets and briquettes, has continued to grow in the European market in recent years. In order to manage the increased use of biofuels, the dryer capacity must also increase. One possible way of accomplishing this is to install heating tubes into the already existing dryers. Therefore, industrially relevant and appropriate design data, such as energy efficiency and a possible increase in the capacity of developing drying systems, are needed. This article presents the experimental results obtained from drying sawdust in a continuous spouted bed using a heating tube submerged in the bed; the results are compared with those obtained from a bed without using a heating tube. Superheated steam is used as the drying gas in all tests. The drying test is performed with an almost constant inlet moisture content and at three different inlet and outlet temperatures. The drying efficiency increases when the heating tube is turned on. Some explanations of the relation between inlet and outlet gas temperature and moisture content are presented.

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Section: Discussionmentioning

confidence: 99%

“…It should be possible to build a model based on the Ståhl and Berghel [26] concept. The heating tube could be adapted to the model by, for example, including an extra drying section or adding a factor to the formula for calculation of the volumetric heat transfer coefficient.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer

Berghel

2011

Drying Technology

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“…Procesos de secado con altos tiempos de residencia afectan la cantidad de material presente en el pellet final, al igual que promueven la evaporación de terpenos, se disminuye así el poder calorífico final del producto [21]; así mismo, el uso de sistemas de recirculación de gases en la etapa del secado mejora la eficiencia del proceso haciéndo-lo más rentable puesto que disminuye la cantidad total de energía requerida [22].…”

Section: B Sistemas De Manufactura De Pellets De Biomasaunclassified

Producción y uso de pellets de biomasa para la generación de energía térmica: una revisión a los modelos del proceso de gasificación

Núñez¹,

Fajardo²,

Vargas³

2012

Iteckne

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“…Frodeson et al (2013) have shown, based on industrial data, that pellet plants have the potential to increase their drying capacity as well as their energy efficiency by implementing a two-step drying technique [17]. Furthermore, Ståhl and Berghel (2008) show that the increased recirculation of drying gases causes a more energy-efficient operation of dryers and that recirculation gives a significantly higher dew point, which means that more energy can be recovered in the condenser [21]. However, these studies all focus on dryers based on evaporative drying and there is a possibility of increasing energy efficiency in the drying step by removing some of the water in the feedstock by mechanical dewatering.…”

Section: Introductionmentioning

confidence: 99%

The Potential for a Pellet Plant to Become a Biorefinery

et al. 2019

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The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery.

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Validation of a Mathematical Model by Studying the Effects of Recirculation of Drying Gases

Cited by 18 publications

References 13 publications

The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer

The Effect of Using a Heating Tube in an Existing Spouted Bed Superheated Steam Dryer

Producción y uso de pellets de biomasa para la generación de energía térmica: una revisión a los modelos del proceso de gasificación

The Potential for a Pellet Plant to Become a Biorefinery

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