日用陶瓷生产过程中的节能技术

介绍了目前日用陶瓷在生产过程中采用的一些节能技术,其中详细介绍了在日用陶瓷烧成过程中运用的节能技术并对烧成过程中的能耗进行了分析,指出了今后日用陶瓷工业的节能途径。     

PREDICTING THE ENERGY CONSUMPTION OF CONTINUOUS WELL-MIXED FLUIDIZED BED DRYERS FROM DRYING KINETIC DATA

ABSTRACT

Previous work has shown that it is possible to predict the size of a continuous welt-mixed fluidized bed dryer from batch drying curve measurements. This approach has been extended in the present study to include energy consumption calculations. A computer code was written to simulate the performance of the dryer and to determine its specific energy consumption E_s. Starting in this case with an isothermal bed batch drying curve, the program first calculates the mean solids residence time required under specified operating conditions. Mass and energy balances are then used to calculate the heat duty and E_s. The bed temperature was found to have a significant effect on specific energy consumption in all cases. However, the influences of air flowrate and humidity, and of solids loading, were shown to depend on the solids drying characteristics.     

RESIDENCE TIMES OF TWO- AND THREE-COMPONENT MIXTURES IN CASCADING ROTARY DRYERS

The residence times of the components of two- and three-component mixtures of fine (195 µm), coarse (1315 µm) and very coarse (5040 µm) sands were measured in a pilot-scale cascading rotary dryer. The effects of mixture composition and air velocity (0-5.4 m s^-1) were determined. With no air flowing through the drum, the residence times of the individual components were almost the same as that of the overall mixture. Increasing the gas velocity caused a large decrease in residence time. In contrast, particle size had very little effect. The spread of residence times increased with air velocity, peaking between 2 and 4 m s^-1; composition had very little effect on the spread. The residence time of the overall mixture could be calculated using the particle transport model of Matchett and Baker if both the modified drag coefficient Φ_d and the particle Reynolds number Re_p were based on the superficial air velocity and the mass-average particle diameter.     

MODELING AND SIMULATION OF DEEP-BED GRAIN DRYERS

This paper concerns with heterogeneous modeling of deep-bed grain dryers based on two-phase model by taking into account coupled heat and mass transfer within grains. This model also consider axial mass and heat dispersion in the fluid phase. The dynamic two-phase equations are solved numerically by finite difference with alternating direction implicit method algorithm, and then applied to simulate humidity and temperature profile of drying gas across dryers together with moisture content and temperature of grains. The capabilities of these models were compared with experimental data obtained from available literatures, under drying conditions such as temperature and absolute humidity of drying gas and moisture content of grains. The simulation results show that the dynamic of corn drying within the bed is well predicted by the two-phase model.     

优化蒸汽系统 力争节能降耗最佳化

上海石化烯烃事业部蒸汽系统庞大复杂,蒸汽系统的优化难度较大,相关技经指标也较差。为此,通过加强专业化管理强度和力度,在工艺、设备和管理等方面着手,优化蒸汽系统,取得了明显效果。     

DRYING OF MEDICINAL PLANTS WITH SOLAR ENERGY UTILISATION

ABSTRACT

In the paper, a potential of solar energy for drying of medicinal plants in Polish conditions is estimated and development of solar drying technologies is presented. The results of economic assessment of flat-plate solar collectors applied for drying of medicinal plants on a farm are promising. In some specific conditions, e.g. drying of wild grown medicinal plants in remote areas, even application of photovoltaic modules for driving of a fan of a solar dryer is a profitable option and enables easy control of the drying air temperature.     

SIMULATION AND SCALE-UP OF PNEUMATIC CONVEYING AND CASCADING ROTARY DRYERS

This paper presents a unified model for simulation of cocurrent and countercurrent dispersion-type dryers. The main industrial applications are to pneumatic conveying (flash) dryers and cascading (direct) rotary dryers. The basic model is a one-dimensional incremental (stepwise) simulation, which has been developed over a number of years Equations for particle motion, heat and mass transfer, heat and mass balances and local gas conditions are solved simultaneously over a small increment along the dryer. All workers have previously had considerable difficulty in obtaining a good fit between simulations and actual results from pilot-plants or large-scale industrial dryers. A new “fitting mode” calculation overcomes this by identifying the parameters which need to be adjusted, concentrating on those which cannot be measured accurately. Excellent agreement has been obtained between the model and experimental data by this method. The paper also presents revised formulations for particle motion and heat transfer in rotary dryers. The model has been incorporated into two computer programs for flash and rotary dryers respectively, and results from the former are shown for a case study.     

SIMULATION AND SCALE-UP OF PNEUMATIC CONVEYING AND CASCADING ROTARY DRYERS

ABSTRACT

This paper presents a unified model for simulation of cocurrent and countercurrent dispersion-type dryers. The main industrial applications are to pneumatic conveying (flash) dryers and cascading (direct) rotary dryers. The basic model is a one-dimensional incremental (stepwise) simulation, which has been developed over a number of years Equations for particle motion, heat and mass transfer, heat and mass balances and local gas conditions are solved simultaneously over a small increment along the dryer. All workers have previously had considerable difficulty in obtaining a good fit between simulations and actual results from pilot-plants or large-scale industrial dryers. A new “fitting mode” calculation overcomes this by identifying the parameters which need to be adjusted, concentrating on those which cannot be measured accurately. Excellent agreement has been obtained between the model and experimental data by this method. The paper also presents revised formulations for particle motion and heat transfer in rotary dryers. The model has been incorporated into two computer programs for flash and rotary dryers respectively, and results from the former are shown for a case study.     

ENERGY SAVING IN INDUSTRIAL DRYING PLANTS BY PARTIAL RECOVERY OF THE LATENT HEAT OF THE EXHAUST AIR

ABSTRACT

Energy saving in industrial drying by recovering part of the latent heat of the vapor exiting the drier is considered in this paper. This heat recovery is accomplished through a two-stage heat exchanger system, wherein the first stage brings the primary circuit to vapor saturation conditions, while the second stage acts as a condenser. Optimal heat recovery is assured by intelligent, fully automated process control.     

工业建筑节能设计探讨

工业建筑能耗在社会总能耗中占有较大比例，我国在有关工业建筑节能设计等方面的规范、标准还不健全，随着我国节能减排工作的深入开展，工业建筑节能工作也日益受到重视。本文就工业建筑中的一些节能方法进行了探讨。     

模型流体超额Gibbs自由能的计算机分子模拟方法

<正>通过计算机分子模拟,可以直接得到体系的一些与其内分子的空间坐标有关的力学性质, 如内能、压力和密度等。然而要直接计算体系的与墒有关的性质,如GibbS自由能,目前仍十 分困难。     

A SIMULATION MODEL FOR SOLAR THIN-LAYER DRYING PROCESS

A mathematical formulation of the physical process of solar drying based on conventional heat and mass transfer equations is presented. The model Includes: a a technique of estimating the solar radiation on a south-facing tilted panel using the meteorological and geographical parameters for a typical location; b the procedures for obtaining the thermal performance of a solar air-heater for a flat-plate flow-over-absorber design; c an analysis of the drying process based on the Lewis analogy and the Equilibrium Moisture Content concept. Results predicted by the simulation model are presented.     

A SIMULATION MODEL FOR SOLAR THIN-LAYER DRYING PROCESS

A mathematical formulation of the physical process of solar drying based on conventional heat and mass transfer equations is presented. The model Includes: a a technique of estimating the solar radiation on a south-facing tilted panel using the meteorological and geographical parameters for a typical location; b the procedures for obtaining the thermal performance of a solar air-heater for a flat-plate flow-over-absorber design; c an analysis of the drying process based on the Lewis analogy and the Equilibrium Moisture Content concept. Results predicted by the simulation model are presented.     

DEVELOPMENT OF A FUZZY EXPERT SYSTEM FOR THE SELECTION OF BATCH DRYERS FOR FOODSTUFFS

ABSTRACT

The selection of dryers is an art in which knowledge, experience and science all play important roles. Historically, dryer selection has been made by experts on the basis of their extensive knowledge. However, in recent years, computer-based techniques have been developed, which have the potential of at least partially deskilling this process. Of the various possibilities, fuzzy expert systems, in which the selection qualifiers are represented as linguistic rather than numerical variables, are the most promising. This paper describes the development of a fuzzy system for the selection of batch dryers for food products. It featured a novel modular approach in which independent selection goals for dryer type, atmospheric, vacuum or freeze operation, and single or multiple units were adopted. This made the system particularly flexible and amenable to adaptation. The program starts from a ‘ drying process checklist“ in which the principal process variables are specified, and provides a ranked list of feasible alternative dryers. The algorithm was extensively tested and provided quite plausible results. Four representative case studies are presented and discussed.     

DEVELOPMENT OF A FUZZY EXPERT SYSTEM FOR THE SELECTION OF BATCH DRYERS FOR FOODSTUFFS

The selection of dryers is an art in which knowledge, experience and science all play important roles. Historically, dryer selection has been made by experts on the basis of their extensive knowledge. However, in recent years, computer-based techniques have been developed, which have the potential of at least partially deskilling this process. Of the various possibilities, fuzzy expert systems, in which the selection qualifiers are represented as linguistic rather than numerical variables, are the most promising. This paper describes the development of a fuzzy system for the selection of batch dryers for food products. It featured a novel modular approach in which independent selection goals for dryer type, atmospheric, vacuum or freeze operation, and single or multiple units were adopted. This made the system particularly flexible and amenable to adaptation. The program starts from a ' drying process checklist“ in which the principal process variables are specified, and provides a ranked list of feasible alternative dryers. The algorithm was extensively tested and provided quite plausible results. Four representative case studies are presented and discussed.     

浅析裂解炉的节能减排

介绍了天津乙烯装置裂解炉节能减排管理及具体实施措施。通过优化工艺调整,减少燃料气、锅炉给水、蒸汽、电能等能源消耗,达到了挖潜增效的目的。     

基于热平衡的陶瓷隧道窑节能技术分析

对某陶瓷隧道窑全窑热平衡进行了测算,在对各耗热项的节能潜力进行分析的基础上,结合陶瓷工业隧道窑目前的技术水平,探讨了陶瓷隧道窑的节能途径与技术。     

预混式二次燃烧系统的节能减排效果

介绍了一种预混式二次燃烧系统,包括其结构、工作方式、原理等。分析了该系统在陶瓷辊道窑和熔铝炉上应用的节能减排效果。     

THERMOCOMPRESSOR DESIGN FOR EFFICIENT ENERGY RECOVERY OF PAPER PRODUCTION PLANT DRYERS

Abstract

The operational performance of a paper production plant can be significantly improved by appropriate process interventions. This paper deals with energy aspects of the most important section of such a plant, the paper drying section. A significant intervention that would lower the operational cost of the drying process is proposed. It refers to the recompression of low pressure steam leaving the dryers by means of a thermocompressor that would utilize high pressure steam coming from the plant burners. The mathematical model of the thermocompressor is evaluated and its design procedure is formulated as a mathematical programming problem involving appropriate objective function and constraints.     

多孔纤维状物质的冷冻干燥模型

通过对草菇进行冷冻干燥实验,研究了过程中样品的中心温度及水分率随时间的变化关系．对冻干过程中物料干燥层和冰冻层进行质量和热量衡算,建立了升华─吸附─解吸数学模型．实验值与模型计算值吻合良好．