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比利时Ingersoll Rand公司在空气压缩机、工具、气泵和材料处理领域处于全球领先地位,已经扩展了接触冷却螺杆式空气压缩机生产线,新引进的R-Series系列电机功率达37~45 kW。全新系列还包括固定转速和变频螺杆式空气压缩机(排气量在4.80~7.59 m^3/min),能够提供更高额定功率,发挥最大价值。采用渐进式自适应控制(PAC)保护新型R-Series(37~45 kW)系列,V-Shield工艺、新型的Xe-Series智能控制系统控制空气压缩机。 相似文献
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乌沙山电厂循泵电机冷却水系统原采用海水作为冷却介质,运行中发现循泵电机冷却器频繁泄漏,经过对比研究多种改造方案,选择独立的闭式循环冷却方案,采用淡水作为冷却介质。改造后效果良好,未在发生冷却器泄漏缺陷,确保了机组安全稳定运行。 相似文献
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造纸厂和纤维板厂的热磨机,一般由容量较大的高压交流电机拖动。为了限制启动电流,有些采用电抗器降压启动,但仍有电流冲击。铡B制启动电流而论,采用辅助电机启动效果最佳。即启动时由一台可调速电机(辅助电机,或称启动电机)带动热磨主电机启动运转、加速(通过离合器),待到接近额定转速时,高压开关合闸,高压电机接通电源运行,同时,辅助电机断电停机,离合器分开,启动过程结束。现以一台热磨机为例作简单介绍。见图1。热磨主电机为交流异步电动机,10kV,136A2000kW,启动电流倍数5.5。辅助电机为直流电动机,189kw,390V… 相似文献
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研究mps430单片机构成步进电机的控制系统,控制步进电机实现三相六拍运行,启动、升减速、停车定位,以及与上位机的通信,采用串行通信模块、单片机模块和电机驱动模块来构成电机的控制系统;用定时器中断来控制I/O输出高低电平,控制驱动的通断,实现脉冲的环形分配完成三相六拍运行;控制定时时间,来控制频率的增加和减少,实现升减速。电机的启动频率达到1000hz,最高运行频率达到20000hz。 相似文献
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详细介绍了采用西门子S7-200CN-PLC和-PT178界面设计的磨粉机控制系统.系统的控制对象是磨辊电机的启动与停止、喂料辊电机的启动与停止、磨辊离舍轧电机的正转与反转以及定位. 相似文献
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大中型电机工作时,必须减压启动。由于控制设备处在长期工作状态,一些元器件和自耦变压器难免不发生故障.继电器、接触器及其它元件坏了很容易更换修理,但自耦变压器线包烧坏若无备件,一、二 相似文献
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№7-Ⅱ型络筒机槽筒电机(008—330—53)转子轴(见图1)与塔形皮带轮通过销钉连接以传动带方式带动槽筒运转。由于槽筒启动与制动迅速,时间极短,且槽筒电机在间歇开关的作用下,使转子轴与带轮连接处(见图1箭头处)反复承受扭应力,经频繁使用此处极易疲劳折断,且断口较平整。一旦转子轴折断,由于采购不到电机转子轴配件,价值3000多元的整个电机也就无法使用,于是我们采取了如下补救办法。 相似文献
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Thermal conductivity of carrots and potatoes was measured using a line heat source probe adapted for measurements to 130°C. Fastest response and rapid attainment of linearity in temperature rise vs In time plots, were obtained with a silicone oil-filled probe with an uninsulated thermocouple junction. Custom designed electronics to amplify thermocouple output, and computer control of measurements, data acquisition and analysis resulted in 0.4% data repeatability (two standard deviations) for calibration standards. Thermal conductivity of carrot and potato vs temperature agreed well with the published volume fraction model for multi-component foods. 相似文献
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为了提高碳纸的导电、导热性,采用电阻小且导热系数高的中间相沥青基碳纤维为原料,部分替代聚丙烯腈基碳纤维以制备碳纸;研究了中间相沥青基碳纤维不同添加比例对碳纸的微观形貌、结晶结构及导电、导热性能的影响。结果表明,随着中间相沥青基碳纤维添加比例的提高,碳纸的石墨化度明显提升,导电、导热性能显著增加。当中间相沥青基碳纤维与聚丙烯腈基碳纤维的质量比为3∶7时,经过石墨化的碳纸石墨化度为97.4%,与石墨化后纯聚丙烯腈基碳纸相比,电阻率由6.80 mΩ·cm降低至4.37 mΩ·cm,降低了35.7%;垂直表面的导热系数由0.084 W/(m·K)提高到0.159 W/(m·K),提高了88.8%。 相似文献
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Thermal conductivities (k) of gelatinized starch gels and of starch gels with dissolved sucrose were determined at 80 to 120°C and at 39.6 to 75% moisture by a line heat source probe method. A special made sample holder prevented moisture evaporation during determination. Regression equations relating k to temperature and moisture were developed through stepwise regression analysis. Reliability of the developed equations was verified through experiments. The maximum error for regressed k values was 0.0085 W/mK. 相似文献
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作者研究了葡萄糖结合高压热杀菌(HPTS)处理对枯草芽孢杆菌芽孢的杀灭效果及其内膜的影响,通过平板计数法、电导率测定、流式细胞术分析及傅里叶变换红外光谱分析等对枯草芽孢杆菌芽孢的灭菌效果、离子释放量、内膜通透性及膜结构稳定性进行了研究。结果表明:在600 MPa、75 ℃条件下,芽孢死亡量达到4.64个对数值,而在添加了质量分数60%的葡萄糖溶液后,芽孢的死亡量减少了约2个对数值。随着葡萄糖质量分数的升高,芽孢的离子释放量显著下降(P<0.05);流式细胞术结果显示在600 MPa、75 ℃结合质量分数60%葡萄糖溶液处理下样品的阳性区域(M2)占比为92.88%,这表明芽孢内膜通透性显著增加(P<0.05);通过分析样品在3 000~ 2 800 cm-1波段的傅里叶变换红外光谱,发现与单独HPTS处理相比,添加葡萄糖可以使芽孢内膜的—CH2/—CH3官能团吸收峰明显减弱,葡萄糖可有助于维持芽孢内膜结构的稳定性。由此可知,葡萄糖含量对HPTS灭活枯草芽孢杆菌芽孢的效果有重要影响。 相似文献
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High hydrostatic pressure treatment (400 MPa, 15 min, 5–50°C) of potato cubes (2 × 2 × 2 cm) was compared with hot water blanching (100°C, 30–180 set). Inactivation of microorganisms and polyphenoloxidase, texture and density change, leaching of potassium and loss of ascorbic acid were monitored. Reduction of microbial counts was comparable for both methods and polyphenoloxidase was completely inactivated at 20°C, when dilute citric acid solutions (0.5 or 1.0%) were used as “immersion” medium. Hot water blanching and high pressure treatment resulted in samples of similar softness. Leaching of potassium was reduced 20% after pressure treatment on vacuum-packaged samples. Retention of ascorbic acid in pressure-treated samples was temperature dependent ranging from = 90% at 5°C to = 35% at 50°C. 相似文献
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为研究高压结合热处理对猪肉风味的影响,以猪背最长肌为原料,用不同压力(200~600?MPa)结合热处理(20~60?℃)10?min,采用气相色谱-质谱和电子鼻对各样品的风味进行分析。在不同样品中共鉴定出141?种挥发性风味成分,包括醛、酮、醇、酯、酸、烷烃等。处理样品中挥发性化合物种类和总峰面积与对照组相比都有所增加,且样品的总峰面积随温度或压力的升高而增加,醛类、酮类和醇类是引起总峰面积增加的主要原因。偏最小二乘回归分析表明,压力对风味的影响较温度更大,处理条件越剧烈对样品风味改变越大;电子鼻分析表明,600?MPa的压力处理能显著改变样品风味。因此对猪肉进行高压处理时,压力应控制在400?MPa左右为宜,而温度在不超过60?℃时对风味的作用较小。 相似文献
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Hyun‐Wook Choi Jae‐Hwang Lee Soon‐Chul Ahn Byung‐Yong Kim Moo‐Yeol Baik 《Starch - St?rke》2009,61(6):334-343
Effects of ultra high pressure (UHP), pressing time and HCl concentration on non‐thermal starch hydrolysis using ultra high pressure were investigated. As regards ultra high pressure, starch granules maintained their structure up to 450 MPa and were partially disintegrated at 600 MPa. Degree of hydrolysis did not change up to 450 MPa and dramatically increased at 600 MPa indicating that starch hydrolysis increased with increasing destruction of starch granules. Pressing time did not affect the degree of hydrolysis. However, degree of hydrolysis and destruction of starch granules increased with increasing HCl concentration up to 4 M. Gel permeation chromatography showed that the soluble fraction of starch formed by hydrolysis mainly consisted of maltooligomers and maltose. X‐ray diffraction pattern changed from A type to C type upon hydrolysis, otherwise it remained as A type. This work provides fundamental information of UHP processing for starch and shows a potential of non‐thermal UHP processing for a new starch hydrolysis method. 相似文献