薛令阳,王书茂,高振江,于贤龙,林 海,魏 青.真空干燥过程中物料质量在线测量设备设计与试验[J].农业机械学报,2018,49(9):326-337.
XUE Lingyang,WANG Shumao,GAO Zhenjiang,YU Xianlong,LIN Hai,WEI Qing.On-line Measurement of Material Quality in Vacuum Drying Process[J].Transactions of the Chinese Society for Agricultural Machinery,2018,49(9):326-337.
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真空干燥过程中物料质量在线测量设备设计与试验   [下载全文]
On-line Measurement of Material Quality in Vacuum Drying Process   [Download Pdf][in English]
投稿时间:2018-03-19  
DOI:10.6041/j.issn.1000-1298.2018.09.038
中文关键词:  真空干燥  质量  在线测量  设备  设计
基金项目:国家重点研发计划项目(2017YFD0400905)和中国农业大学基本科研业务费专项资金项目(2017GX001)
作者单位
薛令阳 中国农业大学 
王书茂 中国农业大学 
高振江 中国农业大学 
于贤龙 中国农业大学 
林 海 辽宁工程技术大学 
魏 青 中国农业大学 
中文摘要:针对真空脉动干燥过程中物料质量在线获取易受到机械振动、温度变化和气流短时冲击等多重干扰,导致测量困难、测量精度不高的问题,提出了将固定料架和测量料架分离的测量方案,并选用高精度的测量器件,在经过信号滤波、温度修正和气流干扰排除等多种修正手段后,实现了温度变化范围20~45℃、明显外部剧烈振动、冲击时间小于1min的正常进抽气条件下总量程1500g、去掉料盘后有效量程1000g、最大引用误差0.1%的物料质量在线测量。静态测试结果显示,满量程最大引用误差0.06%,物料干燥测试结果显示,干燥终点最大引用误差0.1%,能够清楚反映整个干燥过程中的质量变化情况和干燥速率变化情况,可为研究农产品干燥过程中物料状态变化规律和实现自动干燥工艺调控提供技术支持。
XUE Lingyang  WANG Shumao  GAO Zhenjiang  YU Xianlong  LIN Hai  WEI Qing
China Agricultural University,China Agricultural University,China Agricultural University,China Agricultural University,Liaoning Technical University and China Agricultural University
Key Words:vacuum drying  mass  on line measurement  device  design
Abstract:The change of material mass is an important parameter of material state evaluation during the drying process. Pulsed vacuum drying process is a sealed state, herein, the device of mass measurement must be installed inside the drying chamber, which leads to the measurement processing vulnerable to interference, including the mechanical vibration caused by equipment operation, temperature change caused by drying room heating, airflow interferences which with pulsating state. The multiple effects of these disturbances may cause low measurement accuracy. In order to solve this problem, a measurement plan for separating the heating plate fixed material rack and the material measuring rack was put forward. Firstly, the vibration characteristics of the rack were effectively analyzed. The minimum resonance vibration frequency was about 8Hz, and the main resonance frequency was about 25Hz. According to the vibration characteristic, two order IIR digital filter were designed, which effectively solved the vibration problem. Then the drift characteristics of the sensor were measured for zero drift of the sensor caused by temperature. The correction temperature range was 20~45℃, and it was found that it can be corrected by five or six order polynomials. However, the higher calculation of higher order polynomials was not conducive to the real time control of the whole machine. Therefore, the piecewise polynomial fitting method was adopted. The temperature stage of the piecewise fitting formula of zero drift werey=647062-60410t+1403t2 (20℃≤t<215℃), y=21235-2172t+62t2-065t3 (215℃≤t<43℃), y=-499406+23206t-2749t2(43℃≤t≤45℃). The air turbulence in the process of inlet and outlet was not regular, which had little effect on the whole drying process. Therefore, the measured data of intake and exhaust stages were removed and replaced with linear interpolation data. In order to get the final mass data, a linear relationship between filtered and corrected sensor output and standard mass was established, and the final mass conversion formula was mo=0.00044021(x-y)-1.4553. In the formula, through the static test, the measurement system of full scale maximum reference error was 0.06%. The results of material drying test showed that the maximum reference error of the drying end was 0.1%. Through the data recording during drying process, it can clearly reflect the quality change and drying rate change in the whole drying process. The research result provided technical support for studying the changing rule of material status and realizing automatic drying process control in the drying process of agricultural products. 

Transactions of the Chinese Society for Agriculture Machinery (CSAM), in charged of China Association for Science and Technology (CAST), sponsored by CSAM and Chinese Academy of Agricultural Mechanization Science(CAAMS), started publication in 1957. It is the earliest interdisciplinary journal in Chinese which combines agricultural and engineering. It always closely grasps the development direction of agriculture engineering disciplines and the published papers represent the highest academic level of agriculture engineering in China. Currently, nearly 8,000 papers have been already published. There are around 3,000 papers contributed to the journal each year, but only around 600 of them will be accepted. Transactions of CSAM focuses on a wide range of agricultural machinery, irrigation, electronics, robotics, agro-products engineering, biological energy, agricultural structures and environment and more. Subjects in Transactions of the CSAM have been embodied by many internationally well-known index systems, such as: EI Compendex, CA, CSA, etc.

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