PERFORMANCE of HEAT RECOVERY SYSTEM FOR A SPRAY DRYER

A factorial experimental design was used to study the effect of exhaust heat recovery, air flow rate and outlet temperature on the energy consumption of a spray dryer. A commercial-scale cocurrent flow dryer with pressure atomization was used to dry 15 wt% sodium sulfate solutions. the inlet air to the dryer was preheated by using a shell-and-tube heat exchanger to recover energy from the exhaust air. Heat recovery reduced the energy consumption of the dryer by 12–28%, with the largest reduction occurring at the high levels of air flow rate (13,000 kg/h) and outlet temperature (104°C). the energy consumption of the dryer was lowest when heat was recovered at the low air flow rate (6500 kg/h) and low outlet temperature (82°C). No problems were encountered with fouling or cleaning of the heat exchanger. the total pressure drop across the heat exchanger varied from 0.05–0.2 kPa depending on the air flow rate. This additional flow restriction resulted in an estimated 8% decrease in air flow rate but had negligible effect on energy consumption. the warm-up time and the space required by the heat recovery unit were insignificant factors for this dryer. the payback period of the heat recovery system was estimated as 4.1–5.4 years with a rate of return of 21–28%.     

HXHT1小型粮食干燥机的简介与试验

简述了所研发的HXHT1型小型粮食干燥机的结构特点和工艺流程,设备采用逆顺流加热及缓苏的干燥工艺,并配备小型生物质燃料热源,具有热效率高、节能显著、烘干品质好、成本低、可操作性强、通用性及适用性好的优点。产品具有广阔的市场前景。     

浅析玉米干燥机工艺结构对干燥后玉米水分不均匀度的影响

通过对顺逆流式、混流式玉米干燥机进行的全面技术性能测试,证实了使用混流式玉米干燥机干燥玉米后,其水分不均匀度要比使用顺逆流式玉米干燥机的低,通过对影响玉米干燥过程的工艺结构进行分析研究,探讨了解决玉米干燥后水分不均匀度高的方法。     

基于工艺流程的纸机干燥部建模与模拟

基于三段通汽式干燥部工艺流程,在“输入已知、输出未知”和“先烘缸、再通风、后纸张”的原则指导下,以烘缸组为最小建模单元,根据序贯模块法的基本思路,构建了纸机干燥部的静态模型。以某新闻纸机干燥部为对象进行模拟,给出了进出各模块的物流和能流信息,模拟结果与该纸机实际运行情况基本一致。该模型符合纸机干燥部工艺流程,可以用来模拟各模块之间的物流和能流信息,便于为干燥部用能分析提供依据。     

干燥后玉米水分不均匀度影响因素的分析与建议

本文根据对顺流式、顺逆流式、混流式、横流式、双塔玉米干燥机及小型玉米干燥机进行全面技术性能测试结果，分析影响玉米干燥后水分不均匀度高的因素。通过对工艺结构的研究分析和实际测试结果的线性分析，认为玉米干燥机工艺结构、穿越粮层风速和粮层厚度是影响干燥后玉米水分不均匀度的主要因素，并针对已有玉米干燥机及新建玉米干燥机，分别提出解决问题的方法。     

集成物流、能流和流分析的纸机干燥部建模

针对目前纸机干燥部建模和用能分析中未能有效集成物流、能流和流分析的状况,采用面向对象的方法,将复杂、多物料的纸机多烘缸干燥部的传热传质过程划分为多个相对独立的功能单元并建立了与之对应的单元模型,重点介绍了纸幅单元模型的建立。所有单元模型具有能量和量分析功能并与传统的物流分析集成。基于序贯模块法,应用单元模型构建了干燥部的模块流程图,并对某造纸企业的干燥部进行仿真,仿真结果与实际测量结果基本一致,表明建立的单元模型基本合理。通过调整进各烘缸段新鲜蒸汽的流量或压力等手段,可节省新鲜蒸汽用量,降低吨纸汽耗,达到节能的目的。     

基于Fluent的负压式电加热干燥机内部流场分析与机构参数优化

针对负压式电加热干燥机存在内部流场不均匀、干燥效率低等问题,以Fluent为基础对负压式电加热干燥机内部风速场、温度场进行数值模拟,并采用SolidWorks对干燥机内部结构进行改进设计。结果表明:影响干燥机干燥效率的主要因素是工作参数和结构参数,通过改变工作参数和优化结构,可以达到干燥机内部流场均匀性最优。经SolidWorks优化设计后的干燥机内部流场均匀性相对于原有结构有明显提高,优化后的结构参数满足设计要求,且极大地提高了干燥机的热利用率和工作效率。     

不同叶丝分组干燥技术比较

为解决"红旗渠(银河之光)"在传统叶丝干燥处理时烟叶潜质不能充分发挥、分组加工过程中生产调度时间较长和能源浪费等问题,对"红旗渠(银河之光)"产品进行了叶丝干燥工序的分组加工处理试验,并与传统的叶丝干燥工艺与分组加工在物理指标、感官质量和烟气指标等方面进行了比较,结果表明:"红旗渠(银河之光)"采用分组叶丝干燥工艺处理后,烟丝填充性能提高,感官质量得到改善,烟丝耐加工性增强,烟叶潜质得到进一步发挥。     

利用埋管流化床干燥PTA的可行性初探

涤纶原料对苯二甲酸乙二酯生产所用干燥机以进口为主,设备投资大,运行成本高,国内开发难度大。埋管流化床在己二酸干燥装置上的应用,为PTA装置中干燥机的改进提供了一个新的思路。     

涂布机干燥箱的节能控制系统开发

干燥箱是印刷机的涂布设备中能耗最大的单元,同时又存在很大的节能空间。目前涂布机干燥箱普遍存在着由于运行自动化程度不高、操作仅凭借现场工人操作经验、缺乏理论指导等问题导致的能源浪费的现象。文章设计了一种基于涂布机干燥箱最优工艺参数的自动控制系统,重点给出了它的软件设计方法。该软件通过对涂布干燥设备的参数优化与控制,结合先进的电控装置,使干燥箱能够在最优工艺参数下自动的高效运行,从而实现了干燥箱的节能目标。     

蒸汽喷射式热泵在纸机干燥部供热的应用分析

将蒸汽喷射式热泵引入到传统的纸机干燥部多段式供热系统之中.建立了系统的计算模型,对一个典型的纸机三段供热干燥系统进行了计算.结果表明,引入喷射泵以后的系统较之传统系统,蒸汽耗量减少10%左右,段间流动压差增加,有利于烘缸内冷凝水的排出,干燥效果也更佳.     

Enviro-economical feasibility of groundnut drying under greenhouse and indoor forced convection hot air dryers

In the present paper, groundnut samples were dried under natural convection greenhouse drying (NCGHD), forced convection greenhouse drying (FCGHD), and indoor forced convection hot air drying (IFCHAD) modes in the climatic conditions of Rohtak, India (28°54′ N 76°34′E). Samples of groundnut were dried up-to-the-safe storage moisture level of 8–10%. Drying cost per kg of dried groundnut under NCGHD, FCGHD, and IFCHAD modes were found to be ₹ (Indian National Rupee) 25.18 (0.34 US$), ₹ 42.18 (0.57 US$), and ₹ 135.85 (1.84 US$), respectively for the same wire mesh sieve size. Cost under greenhouse drying modes decreases with the increase in wire mesh sieve size. Cost under NCGHD and FCGHD modes was 81.46%–69% less than the average drying cost per kg of dried groundnut under IFCHAD mode for the same sieve size. Critical parameters such as embodied energy, energy payback time (EPBT), CO₂ mitigation, and carbon credit earn (CCE), which help study the cost analysis of a greenhouse dryer have also been evaluated. Cost of manufacturing a greenhouse decreases with a decrease in embodied energy. Maximum utilization of a greenhouse dryer can reduce CO₂ emission. Carbon credit trading is used to control pollution. It provides an economic incentive to achieve a reduction in pollutants emission. EPBT was found to be about 1.66, 1.72, and 4.67 years for natural convection greenhouse dryer, forced convection greenhouse dryer, and hot air dryer, respectively.     

纸机钢制烘缸技术存在的问题及对策分析

对造纸行业使用的钢制烘缸和铸铁烘缸的优点和缺点进行了比较.就纸机钢制烘缸的材料选择和结构设计、制造以及使用中存在的问题进行了分析.在技术方面,应该加快更新钢制烘缸技术规范的步伐,适应高车速和多品种纸机生产对烘缸性能的要求,减少钢制烘缸的制造成本,降低纸厂在钢制烘缸设计寿命期内的缸面处理费用.     

富氮低氧+磷化氢防治储粮害虫技术的实仓应用研究（中英文）

为防治澳大利亚主要仓储害虫,开发富氮气调技术作为熏蒸剂的辅助手段。然而,由于成本问题,一直影响其在行业推广应用。本研究利用中国长顺安达公司的先进膜分离技术,与传统的制氮技术（变压吸附/PSA）进行性能比较,在西澳Kwinana的CBH粮食港,开展实仓应用实验,以解决阻碍其推广的运营和成本问题。为满足澳大利亚严格的标准操作条件,长顺安达专业团队对港口设备进行了升级改造,目标消杀成本设定为0.50澳元/吨粮（磷化氢的高端熏蒸成本）。研究表明,旧的PSA技术的运营成本为2.43澳元/吨粮,该技术在产生和维持控制害虫所需的99%氮气浓度水平方面也显示出操作局限性。相比之下,使用膜技术制氮的成本为0.99澳元/吨粮,其他性能增益还包括运行4.5天内即可产生所需的氮气浓度,且可维持14天以完全控制害虫。     

多通道烘缸通道内流体流动特性数值模拟研究

探讨了多通道烘缸内流体通过通道时的流动特性,建立了多通道烘缸通道的计算流体力学模型,并用计算流体力学软件FLUENT模拟通道内在不同气相折算速率及不同液相折算速率工况下,通道内气液两相分布及其沿通道壁面方向的压力降,得出了通道内流型的变化情况,为多通道烘缸的流动与传热机理研究提供了理论依据。     

Experimental investigation of drying behaviour and conditions of pumpkin slices via a cyclone‐type dryer

This paper describes an experimental investigation of the drying behaviour and conditions of pumpkin slices via a convective cyclone‐type dryer. Drying experiments were conducted at air inlet temperatures of 60, 70 and 80 °C and air velocities of 1 and 1.5 m s^?1. Samples of 200 g of cylindrical pumpkin slices (thickness 5 mm × diameter 35 mm) were arranged in a single layer on each of two trays. The least squares method was applied to derive the drying curve equation of samples. During the experiments the following parameters were measured: weight loss, temperature, relative moisture and velocity. From these parameters, dimensionless mass loss, moisture content, mass shrinkage and drying rate of samples were calculated and are discussed in detail. Additionally, the transport of water during dehydration was described by the diffusion mechanism, and Fick's equation was used for evaluation of the experimental data. The linear sections of drying curves were analysed by linear regression to obtain the moisture diffusivities. It was found that pumpkin slices would dry perfectly within 340–720 min under these drying conditions. The convective cyclone dryer could also be used to dry other products. Thus it is expected that this new dryer will help farmers and producers to reduce the cost of drying. Copyright © 2003 Society of Chemical Industry     

Improved energy efficiency of farmers' cooperative litchi drying operation in Northern Thailand

In 2007, Hmong farmers growing litchi in the mountainous region of Northern Thailand started to dry the fruit in response to its declining market price. However, the locally available dryer, although affordable and of a size appropriate for smallholder farmers' cooperatives, showed excessive gas consumption, and this, along with rising fuel costs, imposed a threat to the drying operation. The objective of this study was to test low‐cost, easy‐to‐implement modifications to a locally available convection dryer, to improve its energy efficiency. Experiments were conducted in cooperation with a Hmong farmers' cooperative in Northern Thailand. Insulation of the air ducts and control of the air recirculation rate led to energy cost savings of US$2.45 per dryer‐load. With the modifications required being simple, the investment needed was recovered after only approximately 20 loads, while the energy efficiency of the dryer increased from 33% to 39%.     

Technological and sustainable strategies for reducing losses and maintaining the quality of soybean grains in real production scale storage units

Soybean is the oilseed most cultivated worldwide and is in full production expansion in Brazil. However, the logistics and grain quality in post-harvest stages is increasingly concerning. The objective of this work was to evaluate different sustainable strategies of managing the mass of soybean grains in function of water content, optimizing the combined drying and storage operations to improve grain flow and quality in real production scale storage units. The experimental were consisted in two step, first: moisture soybean (SUL) (17%), dry soybean from the RR crop (SSLRR) (14%), dry soybean from the RR2 crop (SSLRR2) (14%), soybean dried in a continuous dryer (SSS1) (12%), in silo-dryer (SSS2) (14%), and in intermittent dryer (SSS3) (14%), moisture soybean (SUL) submitted to aeration drying (Silo 1), to partial drying (SSS1, SSS2, SSS3), and supplemented with aeration drying (Silo 2), dry soybean from the RR2 crop (SSLRR2) and stored in aeration (Silo 3), dry soybean from the RR crop (SSLRR) and stored in aeration (Silo 4), and second step: the lots of soybean (RR and RR2) was submitted the drying at low air temperatures of 35, 45, and 55 °C until the grains reached water content of 12% for cold storage at 10 and 20 °C, over two months. It was determined the physical and physical-chemical quality of soybean grains before and after drying and during the time in storage. The best option of preprocessing and storage strategy to obtain soybean flow and quality in high-capacity storage and handling unit was the combined drying (SSS1, SSS2, SSS3) and dry-aeration storage systems. The soybean grains harvested at high water contents submitted to drying at low temperatures and stored under artificially refrigerated conditions presented better grain quality over storage time but increased the operational drying time, hindering the flow of grain mass.     

54—THE SIMULATION OF A MOISTURE-CONTROL SYSTEM FOR WOOL DRYERS

An account is given of an investigation into simulating the behaviour of a moisture-control system for suction-drum dryers handling loose wool. The dynamic characteristics of a typical plant without control were measured, and the characteristics of standard pneumatic-control elements were determined separately. These characteristics in transfer-function form yielded the parameters for an electrical-analog simulation, which showed that indirect control of the outgoing moisture in the wool was possible, since the hygrothermal environment in the dryer could be regulated satisfactorily. The control system could also cope with periodic fluctuations in the wool feed-rate, provided that these were of dissimilar period to that of the control loop itself.     

纸机干燥部循环润滑系统关键控制参数的研究

介绍了纸机干燥部循环润滑系统的组成,分析了水分和温度对纸机干燥部润滑油性能的影响,对纸机干燥部润滑系统中水分的危害进行了探讨,进一步提出了对纸机干燥部循环润滑系统关键参数进行控制的必要性和潜在价值。最后,对纸机干燥部润滑系统关键参数的控制进行了研究。