卧螺离心机直流共母线变频差速研究

发布时间：2018-08-31 10:39

【摘要】：卧螺离心机是煤泥脱水工艺中的常用设备,现有煤用卧螺离心机速差固定不可调节。前期研究结果表明,变速差卧螺离心机有利于提高脱水效率,但存在速差调节不稳定以及电机反向充电烧毁变频器的问题。因此,本项研究构建双变频共直流母线驱动系统,研究双变频速差控制方案和离心机空载状态下刮刀与筛篮拖动关系,以及研究载料工况下再生电能的影响因素对卧螺离心机工业应用有着指导作用。本文主要针对卧螺离心机的速差控制方案、离心机工作机构运行状态、再生电能影响因素及离心机脱水效果几方面进行研究。根据脱水工艺及控制要求设计离心机转速调节系统,画出控制系统方框图,采用动态响应分析,提出串级系统控制策略。对比计算单回路控制系统和串级控制系统方框图传递函数,分析优化后的离心机转速调节系统的动态特性和克服二次干扰的能力。依托搭建的离心机调速系统,通过双电机对拖关系试验,研究离心机空载运行条件下,频率差的改变对双电机对拖干扰的影响,发现频率差增大,系统受对拖干扰的影响效果总体下降,其中筛篮受对拖干扰的影响与频率差为正相关,刮刀受对拖干扰的影响与频率差为负相关。并通过对离心机主要工作机构的工作状态分析,发现在离心机运行时,再生电能是由于刮刀电机输入制动转矩所致。根据再生电能的产生特点,分析并提出共直流母线方案对其进行处理。在离心机载料运行工况下,分析筛篮转速、离心机速差及离心机处理量对再生电能影响。研究表明再生电能随筛篮转速的升高而增大,随速差的增加而增大,速差越大增速越快,随离心机处理量的提高而增大。最后,基于已搭建的卧螺离心机试验系统进行粗煤泥脱水试验,研究本试验所用卧螺离心机的最佳工作速差区间及最适宜筛篮工作转速范围,结果表明3.0-9.0rpm为最佳工作速差区间,筛篮工作转速则要高于435.0rpm,速差对于脱水效果的影响大于筛篮转速对脱水效果的影响。
[Abstract]:Horizontal screw centrifuge is a common equipment in coal sludge dehydration process. The speed difference of existing horizontal screw centrifuge can not be adjusted. The previous research results show that the variable speed differential horizontal screw centrifuge is beneficial to improve the dehydration efficiency, but the speed difference adjustment is unstable and the motor reverse charge burns out the inverter. Therefore, this paper studies the construction of double frequency conversion common DC bus drive system, and studies the control scheme of double frequency conversion speed difference and the relationship between scraper and screen basket driving under the condition of no load of centrifuge. The research on the influencing factors of regenerated electric energy under loading condition has a guiding effect on the industrial application of horizontal spiral centrifuge. This paper mainly focuses on the speed difference control scheme of the horizontal spiral centrifuge, the running state of the working mechanism of the centrifuge, the influence factors of regenerating electric energy and the dehydration effect of the centrifuge. According to the dehydration process and control requirements, the speed regulation system of centrifuge is designed, the block diagram of the control system is drawn, the dynamic response analysis is adopted, and the control strategy of cascade system is put forward. The block diagram transfer function of single loop control system and cascade control system is calculated, and the dynamic characteristics of the optimized rotating speed regulation system of centrifuge and the ability to overcome the secondary interference are analyzed. Based on the speed regulation system of centrifuge, the influence of frequency difference on towing interference of double motor is studied under the condition of no-load operation of centrifuge through the test of towing relation of double motor, and it is found that the frequency difference increases. The effect of the system affected by towing interference was generally decreased, in which the influence of sieve basket on towing interference was positively related to the frequency difference, and the influence of scraper on towing interference was negatively correlated with the frequency difference. Through the analysis of the working state of the main working mechanism of the centrifuge, it is found that the regenerative electric energy is caused by the input braking torque of the scraper motor when the centrifuge is running. According to the characteristics of generation of regenerated electric energy, a common DC bus scheme is proposed to deal with it. Under the operating condition of centrifuge loading, the influence of screen basket speed, centrifuge speed difference and centrifuge handling capacity on regenerated electric energy is analyzed. The results show that the regenerated electric energy increases with the increase of the speed of the screen basket, increases with the increase of the speed difference, increases with the increase of the speed difference, and increases with the increase of the processing capacity of the centrifuge. Finally, based on the dewatering test of coarse coal slime, the optimum working speed difference interval and the optimum working speed range of the horizontal spiral centrifuge used in this test are studied. The results show that 3.0-9.0rpm is the best working speed difference interval. The working speed of the screen basket was higher than that of 435.0 rpm, and the effect of the speed difference on the dehydration effect was greater than that of the screen basket speed on the dehydration effect.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD462.1;TD94

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