摘要:

Spectral Sciences, Inc. is developing a multipoint humidity monitor for drying application in the pulp and paper industry. The humidity is measured by monitoring near-infrared optical absorption in the process stream atmosphere. An array of sensor heads distributed throughout the plant is linked by fiber optic cables to a single source/readout device which can be located in a control room hundreds of meters away. The sensor heads and cables are modular. allowing for raid installation and reconfiguration of a distributed sensor system in process control applications. The method used for quantifying the optical absorption provides substantial stability, accuracy, and signal processing advantages over standard wavelength scanning or band pass techniques. The laser diode's output wavelength is actively locked to the center of a water absorption line, thereby providing a constant monitor of water vapor concentration which is insensitive to all other species in the process stream. Wavelength modulation and second harmonic detection techniques are used to quantify the water vapor concentration. A simultaneous temperature measurement then permits an output of the absolute humidity or humidity ratio for process monitoring or control

ISSN:0737-3937    

DOI:10.1080/07373939108916723

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373939108916724

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper describes a simple thermoelectric psychrometer that measures equilibrium humidity of a sample in a small vessel. The psychrometer consists of one thermocouple and detects the wet-and dry-bulb temperatures using the same measuring junction. The detector consists of a K-thermocouple, 0.1mm in diam., and the surface of the junction is covered with a thin fiber material. When the fiber is moistened by water, the junction acts as a wet bulb. As the moisture in the fiber is lost, the temperature of the junction rises rapidly to that of the dry bulb. The psychrometer constant is derived from equi-dew-point lines drawn up experimentally and is found to be 0.00074°C-1 Data of the equilibrium humidities observed for saturated sodium chloride solution and some foods are shown.

ISSN:0737-3937    

DOI:10.1080/07373939108916725

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Drying plants are often run solely on the experience of the personnel who usually operate on the "safe" side using larger amounts of energy than necessary. A more efficient method of reducing the energy and costs is the installation of an industrial moisture measuring system, using special sensors to monitor the maximum dewpoint differential

ISSN:0737-3937    

DOI:10.1080/07373939108916726

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper presents a general overview of Freeze-Drying (Lyophilization) and discusses the underlying principles of the process. Emphasis has been placed on the freeze-drying of biological materials and special mention has been made to the formulation of bio products prior to processing

ISSN:0737-3937    

DOI:10.1080/07373939108916727

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Maize is the second largest agricultural produce in France. To be acceptable on national and foreign markets, it must preserve its physico-chemical properties during the drying process that occurs after harvesting, specially the wet-milling quality which is measured, in our case, by the "Turbidity Test". We have tried to make a dynamic model which could simulate all transitory phenomena observed in a real industrial dryer (tempering, condensation) and to predict its quality performance. This dryer conception tool, based on a simple compartmental analysis is useful for fast computations. This concept is described and compared with the experimental results

ISSN:0737-3937    

DOI:10.1080/07373939108916728

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Thin layer air drying of plum was studied. The drying conditions in this study are : dry bulb temperature ranging from 60 to 100 °C, air moisture content ranging from 0.008 to 0.089 kg water/kg dry air and air velocity ranging from 0.5 to 2 1x11s. An exponential model was used to describe the drying curve. The heat and moisture balances on the air were used to calculate the outlet air temperature and its moisture content. The heat balance on the product was used to calculate the product temperature. These equations were used to predict the drying of plum in deep bed. A good agreement between the experimental and calculated product moisture content, the product temperature and the outlet air temperature were obtained

ISSN:0737-3937    

DOI:10.1080/07373939108916729

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We have developed models to determine the radiative heat transfer of infrared dryers. Using the models, the efficiencies of several IR constructions are calculated. The radiation properties of all parts of the IR dryer are measured with an IT-IR spectrometer using integrating sphere techniques. With these models and measured results, the total efficiencies of several dryer constructions are calculated for: an electric dryer with a pambolic mirror, an elecmc dryer with a flat ceramic mirror, and a gas-fired dryer. The effect of a back reflector on these dryers is also calculated. The efficiencies of all these dryers are compared to each other.

ISSN:0737-3937    

DOI:10.1080/07373939108916730

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The aim of this study has been to develop a mathematical model for water flow and binder migration in coated paper. The model can be used for simulation of the stages starting after the coating applicator including infrared and air drying sections. On the basis of the model the moisture, temperature and binder distribution can be determined across the paper thickness. Approximating equations concerning the paper properties are used in the model. We have measured the diffusion coefficient between the water and binder substances. Representative numerical examples are presented for separate and combined infrared and air drying processes.

ISSN:0737-3937    

DOI:10.1080/07373939108916731

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Coal was dried and simultaneously reduced in size in a spouted bed using air at different temperatures as the spouting fluid and either glass beads as a dynamic grinding aid or a specially designed metal insert as a static grinding aid. Both semi-batch and continuous operations were carried out, the balanced feed and product-discharge rates in the latter being pre-determined from the results in the former. The rates of both drying and comminution were synergistically increased with increases in inlet air temperature. The static insert was shown to be a more effective comminution device than the glass beads.

ISSN:0737-3937    

DOI:10.1080/07373939108916732

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor