Modelling of MEMS Based Temperature Sensor and Temperature Control in a Petrochemical Industry Using LabVIEW

摘要

Temperature monitoring and control is an essential process in the continuous process industries like that of the Petrochemical industries. Starting from the very storage of the different chemicals to their cracking and distillation, Temperature plays a very important role in all these processes. The total process consists of two major parts, such as the sensing of the Temperature using a Temperature sensor and hence the controlling of the same using a real time controlling software. In this work, we hypothise  the fabrication of a MEMS based temperature sensor for sensing the temperature and the use of LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench) of  National Instruments, USA for controlling of the same. A simplified, novel, cost-effective  Micro-Electronic-Mechanical Systems (MEMS) technology is to be developed for realizing a temperature-sensing array on a flexible polyimide substrate. The fabrication technique will utilize liquid polyimide to form  flexible film on the rigid silicon wafer using a temporary carrier during the fabrication. A platinum thin film is to be employed as temperature sensitive material and  temperature-sensing arrays are micro machined on the polyimide, from which the silicon wafer carrier is removed at the end of fabrication. The platinum thin film temperature sensor exhibits excellent linearity and  temperature coefficient of resistance. Due to  the effective thermal isolation, the flexible temperature sensors also show a very high sensitivity. The MEMS technology based on liquid polyimide enables the development of flexible, compliant, robust, sensor skins for many other important applications, such as robotics, biomedicine, aerodynamics and space exploration. After the sensing part is done we proceed to the task of temperature control. For this purpose we employ the usage of  LabVIEW controlling software-n-n using Virtual Instrumentation. The analog output of temperature sensor is fed to the Analog to Digital Converter (ADC) which converts it into a Digital signal. This signal is fed to the  LabVIEW system using a IEEE 802.11g wireless or Ethernet communication Acquisition Device (DAQ)s.The usage of Wi-fi i.e., Wireless Data Acquisition devices is adopted in this case. This is a flexibility provided by NI(National Instruments)LabVIEW software for remote sensing and monitoring. The parameter (here, Temperature) set point is fixed based on the process. The generated error signal can be recorded in an array and graphical analysis can be performed using the PID Toolkit VI present inside the software. Through the use of continuously recorded output, process engineers can pinpoint the time and machine in which the temperature goes out of the specified range and identify the chemical products affected.