Development of timer based on liquid level measurement system

This paper describes the design and development of the timer based on liquid level measurement system in which timer 555 is used in astable mode. The capacitor charging time i. e. the ON time pulse width of the timer output waveform which is measured using a digital storage oscillator （DSO）,is linearly proportional to the capacitance of a co-axial cylindrical capacitive transducer, and this capacitance once again linearly varies with the change in liquid level. Hence, we obtain a linear relationship between the liquid level and the capacitor charging time. The main advantages of this developed system are linear input-output relationship, small in size, easily portable, cost effective, and independent on the ambient temperature effect. The system can also be exploited to measure dielectric constant of liquid or solid in various process industries.

Design of the Measuring Instrument to the liquid level Based on MSP430 SCM

This paper introduced the components, principle and the hardware and software design of the multiplexing measuring and control instrument to the liquid level that is based on MSP430 SCM. This system is made of pressure sensor, signal processing circuit, electromagnetic valve, output driving circuit, Chinese character LCD, keyboard, optic alarm circuit and MSP430MCU, and realized Liquid level automatic monitor, out range alarm and online function.

New Measuring Method for Colorless Liquid Level Based on CLC100 Level Sensor and Powercast Wireless Sensor Kit

In this paper, a new wireless measuring method for colorless liquid level measurement was presented, based on latest CLC100 liquid level sensor and Powercast wireless sensor development kit. The wireless system is divided into two parts, level measurement and data transmission part as well as data receiving and display part. First part included the capacitive liquid level sensor CLC100 and the wireless senor board. CLC100 sensor was used for liquid level measurement. Wireless sensor kit from Powercast Corporation included one wireless sensor board, which was used for signal transmission. A built-in PIC microcontroller was embedded in the transmission module, for the purpose of processing and data transmitting. Due to CLC100 sensor’s output voltage exceeding the sensor board’s input limitation, a voltage convertor was designed to connect the sensor and the wireless sensor board. The final results were voltages corresponding to the liquid level, and were processed by an independent PIC development board, and then sent to PC’s hyper terminal via serial-port by this PIC microcontroller. Experiments showed that this wireless sensor node prototype worked well.

Improved suspension quality and liquid level stability in stirred tanks with Rotor-Stator agitator based on CFD simulation

The solid-liquid mixing is an important operation unit in the preparation of composites by stirring casting.High quality composite materials need good homogeneity and stable liquid level.In this work,the performances of the Rotor-Stator agitator for solid suspension in stirred tank were investigated through CFD modeling,including the homogeneity,power consumption and liquid level stability.The Eulerian-Eulerian(E-E)multiphase model and the RNG k-εturbulence model were adopted for modeling the multiphase flow and the turbulence effects,respectively.The effect of various important parameters such as stirring speed,particle size,solid loading and the use of baffles were examined.Adding a stator structure with array holes outside the rotor can optimize the flow pattern,thereby improving the mixing uniformity and liquid level stability.The homogeneity and liquid level stability attained by the Rotor-Stator agitator were better than those for the A200(an axial-flow agitator)and the Rushton(a radial-flow agitator).

Fully self-powered instantaneous wireless liquid level sensor system based on triboelectric nanogenerator

Self-powered sensors are highly sought for wireless sensing applications in space exploration,industries,and environmental monitoring,etc.However,most current self-powered sensor technologies are based on the multiple energy conversion routine:energy collection,rectification,energy storage,and power management before it can be used for sensor systems,leading to exceptionally low energy utilization efficiency and very short periods of wireless sensing operation with majority of information lost.Here,we propose a triboelectric nanogenerator(TENG)based fully self-powered instantaneous and real-time wireless sensor system which does not contain electronic devices and microchips,but the passive components only.An innovative cylindrical capacitive-type liquid level sensor is also proposed and is then integrated into the wireless sensor system for monitoring liquid levels or identifying substance of the liquids.This sensor system can convert pulsed voltage output of the TENG into sinusoidal signal with a resonant frequency containing the sensing information and is transmitted to the receiver in distance in real-time.The maximum transmission distance of the sensor system could reach 1.5 m for a 10 cm diameter magnetic-core coil pair.The wireless sensor system exhibited excellent stability and excellent linearity with a sensitivity of 4.63 kHz/cm,and demonstrated its great application potential for the self-powered liquid level monitoring.

Modeling of Liquid Level and Bubble Behavior in Vacuum Chamber of RH Process

In the Ruhrstahl-Heraeus （RH） refining process, liquid steel flow pattern in a ladle is controlled by the fluid flow behavior in the vacuum chamber. Potassium chloride solution and NaOH solution saturated with CO2 were respectively used as a tracer to investigate the liquid and gas flow behaviors in the vacuum chamber. Principal compo nent and comparative analysis were made to show the factors controlling mixing and circulation flow rate. The liquid level and bubble behavior in the vacuum chamber greatly affect fluid flow in RH process. Experiments were performed to investigate the effects of liquid steel level, gas flow rate, bubble residence time, and gas injection mode on mixing, decarburization, and void fraction. The results indicate that the mixing process can be divided into three regions： the flow rate affected zone, the concentration gradient-affected zone, and their combination. The liquid steel level in the vacuum chamber of 300 mm is a critical point in the decarburization transition. For liquid level lower than 300 mm, liquid steel circulation controls decarburization, while for liquid level higher than 300mm, bubble behavior is the main controlling factor. During the RH process, it is recommended to use the concentrated bubble injection mode for low gas flow rates and the uniform bubble injection mode for high gas flow rates.

Development of the liquid level meters for the PandaX dark matter detector

The two-phase xenon detector is at the frontier of dark matter direct search. This kind of detector uses liquid xenon as the sensitive target and is operated in two-phase （liquid/gas） mode, where the liquid level needs to be monitored and controlled in sub-millimeter precision. In this paper, we present a detailed design and study of two kinds of level meters for the PandaX dark matter detector. The long level meter is used to monitor the overall liquid level while short level meters are used to monitor the inclination of the detector. These level meters are cylindrical capacitors that are custom-made from two concentric metal tubes. Their capacitance values are read out by a universal transducer interface chip and are recorded by the PandaX slow control system. We present the developments that lead to level meters with long-term stability and sub-millimeter precision. Fluctuations （standard deviations） of less than 0.02 mm for the short level meters and less than 0.2 mm for the long level meter were achieved during a few days of test operation.

Analysis and Design of Scaling Optimal GPM-PID Control with Application to Liquid Level Control

In this paper, a new analysis and design method for proportional-integrative-derivative （PID） tuning is proposed based on controller scaling analysis. Integral of time absolute error （ITAE） index is minimized for specified gain and phase margins （GPM） constraints, so that the transient performance and robustness are both satisfied. The requirements on gain and phase margins are ingeniously formulated by real part constraints （RPC） and imaginary part constraints （IPC）. This set of new constraints is simply related with three parameters and decoupling of the remaining four unknowns, including three controller parameters and the gain margin, in the nonlinear and coupled characteristic equation simultaneously. The formulas of the optimal GPM-PID are derived based on controller scaling analysis. Finally, this method is applied to liquid level control of coke fractionation tower, which demonstrate that the proposed method provides better disturbance rejection and robust tracking performance than some commonly used PID tuning methods.

Ultrasensitive liquid level sensor based on slice-shaped composite long period fiber grating

In this paper,a novel liquid level sensor with ultra-high sensitivity is proposed.The proposed sensor is configured by a sliceshaped composite long period fiber grating(SSC-LPFG).The SSC-LPFG is prepared by polishing two opposite sides of a composite multimode-single-mode-multimode fiber structure using a CO;laser.The method improves the sensitivity of the sensor to external environment.Based on the simulation calculation,a liquid level sensor with a length of 3 mm is designed.The experimental transmission spectrum agrees well with the simulation result.The experimental results show that the sensitivity reaches 7080 pm/mm in the liquid level range of 0-1400 μm in water.The temperature sensitivity is24.52 pm/℃ in the range of 20℃-90℃.Due to the ultra-high sensitivity,good linearity,and compact structure,the SSC-LPFG has potential application in the field of high-Drecision liquid level measurement.

Design of Laser Radar Fiber Optic Liquid Level Sensor System

A novel fiber optic liquid level sensor based on laser radar (ladar) is reported here. Using the perfect technique of ladar in which the phase of amplitude modulated light wave reflected from the liquid surface is compared with that of original modulation signal, the distance can be measured precisely. A special symmetric compensating coaxial optical system is proposed to eliminate many adverse effects. It realized the one-time electronic-free optical measurement on a simulated oil tank and achieves an accuracy of 0.3%, within a temperature range of -10 ℃～+40 ℃ over a measuring of 0～10 m.

Liquid nitrogen level meter for high-temperature superconductor (HTS)

Many kinds of high temperature superconductor （HTS） power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and controlled to ensure the thermal stability and the dielectric strength as well. To measure the level, capacitance method and differential pressure method are usually used. However, each method has installation difficulties and measurement errors for unsteady state operation with varying system pressure. A new liquid level meter using a 2G HTS conductor is described, which has similar structure with the liquid helium level meter with NbTi filament. The level meter is fabricated with a parallel connected heater, which helps the separation of the superconducting region and normal region, considering the critical temperature, large heat capacity of conductor and cooling characteristics. The level of liquid nitrogen can be obtained from the measured voltage signal along the 2G HTS conductor. Design, fabrication and test results of the new liquid nitrogen level meter are presented.

Application of Neural network PID Controller in Constant Temper-ature and Constant Liquid-level System

Guided by the principle of neural network, an intelligent PID controller based on neural network is devised and applied to control of constant temperature and constant liquidlevel system. The experiment results show that this controller has high accuracy and strong robustness and good characters.

The Design Liquid-level Monitoring System of Adopting the Ultrasonic Sensing Technology

Utilizing the technology of Ultrasonic wave,relevant test arithmetic and the PC to carry on monitoring,controlling and cen-tralized management of the liquid-level in the liquid container. It can prevent from keeping in touch with the examined liquid,not only has increased the continuous working time of the system greatly,simplifying maintenance of the sensor conveniently,can also realize overhauling in producing and boost the productivity and management level. The working principle,hardware structure of the instrument and the design method are presented,and the selection of sensor and MCU is discussed in detail in this paper. MCU are used to control the emission and receiving. Then the liquid-level are calculated,which makes the design more intelligent.

Evaluation study on properties of a macroporous silica-based CMPO extraction resin to be used forminor actinides separation from high level liquid waste

Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.

基于计算机视觉的常用玻璃量器自动检定装置

玻璃量器作为常规配套设备,其需求量日益增长,常用玻璃量器的检定任务越来越重,传统的人工检定已不能满足日益增长的业务需求。该文提出了一种图像法和反馈控制技术相结合的容量示值检定自动化技术,即一种基于图像处理的常用玻璃量器检定自动化装置,主要解决加液自动化功能、容量示值读数自动化功能。开发集数据采集、处理、原始记录生成、报告打印等多功能于一体的软件系统。

透明容器液面机器视觉检测方法

机器视觉检测容器内液体体积的关键在于液面图像识别。根据目标成像特征,研究了基于液面特征和基于参考特征的透明容器液面机器视觉检测方法。通过图像实例与成像机理分析发现,利用液面灰度特征和边缘特征的液面检测方法受液面形态和成像质量的影响较大,而利用外部参照物折射成像出现分离带的液面检测方法在工业相机平视液面时亦容易导致检测失败,且自上而下的搜索方式存在检测误差大的问题。为了提高检测稳定性,提出了一种基于外部参考成像特征的液面检测新方法。该方法基于透明容器影响参照物成像的规律作为检测原理,通过检测参照物的行间梯度,利用液面处梯度最大的特征,自下而上搜索和识别液面。新检测方法不仅增强了液面识别的鲁棒性,还提高了液面检测的准确性。

基于单片机的造纸用液位自动化控制系统研究

为切实应对以往造纸用液位控制系统依赖于自动控制机理构建控制电路所造成的液位控制精确度低与自动化程度低等问题,由嵌入式技术重焕液位控制系统活力着手,针对造纸碱回收蒸发工段黑液液位控制需求,基于52单片机和超声波传感器搭建了液位自动化控制系统。系统测试结果表明,以单片机与传感器相结合的液位控制系统精准度高、自动化程度高,且安全稳定性更高,不仅可充分适应当前追求无人化、高效化的造纸工业生产体系,还可普遍推广应用于其他工业领域。

基于PLC控制器的造纸机干燥部管理方案研究

为实现针对造纸机干燥部的自动化管理,节约造纸企业的蒸汽使用量,降低纸张生产成本,基于造纸机干燥部的基本工艺流程对闪蒸罐液位、气罩送风温度和气罩露点温度实施重点监控,并通过S7-300 PLC控制技术对相关环境的车间设备进行自动化控制。在此基础上,通过STEP7软件编辑自动化管理方案运行程序,并采用Win CC组态软件组建终端操作界面。经试验研究发现,所设计的系统终端操作界面友好直观,数据信息交互方便快捷,造纸企业5个月内的平均吨纸汽耗量下降了0.214吨,纸张生产成本进一步降低。

SPHC产品冲压开裂原因分析及改进措施

针对下游客户提出的SPHC产品冲压开裂问题展开分析、讨论,结果表明:从问题试样断口处检测出的夹杂物为开裂直接原因。夹杂物含有结晶器保护渣特有元素K、Na,证明其来源于结晶器保护渣;浇注中结晶器液面存在波动情况。通过实施相关措施及6个月验证,有效降低了SPHC产品由夹杂物原因导致的改判率,使其质量得到改善。

高含硫天然气净化装置过滤器液位计引管失效分析

介绍了某大型净化厂脱硫单元原料气过滤器失效的问题,对过滤器液位计引管直管段及焊接法兰进行化学成分、金相组织、断口形貌等分析,探讨失效的主要原因。结果表明,原料气过滤器失效的原因是过滤器的材质不符合要求,长期处于偏低温度和酸性介质环境中导致原料气过滤器氯化物应力腐蚀失效。准确掌握设备失效成因,有针对性地采取防护措施,对于确保装置长周期安全运行具有重要的意义。