The Design Of The Online Measure System For Oil In Water

The Water-pollution problems in recent years has aroused widespread concern around the world, and mineral oil on the degree of pollution of water have become increasingly prominent, it is directly related to people's lives and health, affecting people's quality of life. Therefore,to do the prevention work well has been imperative for us.Aimed at the problem,we designed a measurement system to measure mineral oil in water online, which can be applied to different filed of water .When the result out of the National Institute of Standards it will automatically alarm to alert people to do the prevention and treatment work.Theoretical basic of the system is: when ultraviolet radiation shines on the surface water samples tested, once the water contains mineral oil,the molecules of these substances absorb UV energy, and jump to high energy state, when they come back from high-energy state to low-energy state,they will transmit fluorescence, which called stimulated emission. Stimulated emission wavelength of the fluorescence depends on the incident wave length and molecular structure of the shined substance. And structure of different types of hydrocarbons are the corresponding fluorescence spectroscopy, based on a special band and intensity we can determine whether there is some kind of hydrocarbons and to determine the size of its concentration. In general, mineral oil in water contains many kinds of components,in which only the aromatic compounds can emit the fluorescence near 350nm. the proportion of the aromatic compounds in oil in is generally unalterable,and it is an important parameter to measure how much of oil in the water therefore, detecting hou much aromatic compounds to determine how much oil in water has been widely recognized.The working process of the system is as follows:first, sample collection system will collect the water-sample that to be tested into the measure-room,when the sample formed to overflow of the state in the funnel, ultraviolet radiation shines on the surface water samples tested, the mineral oil will absorb the energy of ultraviolet radiation and emit fluorescence, then the fluorescence will be detected by the photodetector,then transit to current signals,which will be converted to voltage signal by the current / voltage converter and amplifier.the voltage signal will be sent to the A / D converter module of MCU,after this we will get a digital signal which will be analysed,delt with and displayed.The optical system of this design use Gp3Hg-1 type T-shaped mercury lamp as the lamp-house,which has a strong luminescence at 253.7nm department that is we need. The system uses C8051020F device as its MCU. The C8051F020 family utilizes Silicon Labs' proprietary CIP-51 microcontroller core. The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than four system clock cycles.The most unique enhancement is the Digital Crossbar. The on-chip counter/timers, serial buses, HW interrupts, ADC Start of Conversion input, comparator outputs, and other digital signals in the controller can be configured to appear on the Port I/O pins specified in the Crossbar control registers.The C8051F020 has an on-chip 12-bit SAR ADC (ADC0) with a 9-channel input multiplexer and programmable gain amplifier. With a maximum throughput of 100 ksps, the ADC offers true 12-bit accuracy. The internal voltage reference circuit consists of a 1.2 V, 15 ppm /°C (typical) bandgap voltage reference generator and a gain-of-two output buffer amplifier. So using the internal voltage requires that the input current must be lower than 2.4V.In the peripherals of MCU we designed keyboard interface, display interface, alarm circuits, clock modules, memory modules, as well as the communication module with the PC.Keyboard layout using 3 * 5 array of layout principles, by setting the function keys, numeric keys with LED display module in order to achieve human-computer interaction function.The system has the capability of storing results to let customers inquire by using a EEPROM AT24C512 even when it is not powered. The SMBus0 I/O interface between AT24C512 and MCU is a two-wire, bi-directional serial bus. It is compatible with the I2C serial bus.In order to allow users to easily use the calibration time, counting and operations, the system real-time clock chip joined SD2003, it is a built-in crystal oscillator, I2C bus interface to support high-precision real-time clock circuit.Measuring the concentration of mineral oil in the water when the concentration exceeded 1, the system will automatically issue a warning prompt, when in the design of single-chip microcomputer to control the relay and disconnect and then closed to control the work of a state of alarm. Exceeded, the relay closed, so that the two ends together with the alarm operating voltage, an alarm will sound to prompt the user has exceeded the water concentration of oil.Users on the system in order to achieve the remote control, but also the design of communication with the PC interface, the system using RS-485 and RS-232 bus to the conversion and transmission of signals. Used in PC, write a VB serial communication interface, a good agreement the baud rate, message formats, such as the delivery of communications rules. Through the interface, the user can use PC remote control measuring system, which is convenient and fast.The system's power is made, there are±12V and +5 V output, and conversion has been adopted-5V and 3.3V output for all components of work systems.A good man-machine interface is a bridge, the system compiler in Keil uVision 2 environment, the use of C language to complete the multi-functional, multi-level menu to prepare and realize the timing, calibration, data communications, measurement, information, time-based determined limits set functions.In order to verify the overall system reliability and stability of measurements, done in the laboratory during the development of a large number of measurement tests, of which water is their configuration. On experimental data obtained the data collation, analysis, and data fitting. Installed after the machine, so the measurement of further tests and test results prove that the solution concentration and configuration values.The entire measurement system combined with good hardware and software, and then through further improvements in the hope to be stereotyped, quantitative analysis of the sources of mineral oil content and the type of water environment in the detection of a broader field of applications.