MSP430单片机氯气联机检测系统设计外文文献及翻译
Abstract The current situation shows that the homemade chlorine gas online detect instrument is low in precision and simple in functions, the import instrument is too expansive and only has the short communication distance with the control center. A chlorine gas online detect instrument was developed. Adopting MSP430 processor and constant electrolytic gas sensor, it can measure the concentration of chlorine gas in the air, give an alarm when the concentration of chlorine gas is out of range and communicate with the control center by GPRS. The measurement range of the device is 0~20 ppm, response time is less than 30 sec and the detecting error is less than 2%. This design is feasible and can meet the real application in papermaking industry, textile industry, pharmacy and water treatment industry.
1. Introduction
Chlorine is an important chemical material which is widely used in papermaking industry, textile industry, pharmacy, plastic industry and water treatment industry. At the same time, chlorine is a virulent gas. It can stimulate people’s mucosa of respiratory tract and mucosa of eyes, or even cause dysfunction of restrictive lung ventilation, inflammation of bronchus, toxic pulmonary edema or burn of eyeballs [1]. The accidents of chlorine leakage happen sometimes in the producing, storage, transport and using of chlorine. To prevent the accident of chlorine leakage and guarantee the safety of workers, It is very meaningful to develop a concentration of chlorine gas online detect device.原文请找腾讯752018766,优-文^论,文.网http://www.youerw.com
The current homemade chlorine gas online detect
instrument is low in precision and simple in function, and the structure is outmoded, can hardly meet the application. Reference [2] is the only domestic patent on chlorine gas online detect instrument. The instrument is realized by analog circuit, low inprecision, outmoded in structure, simple in function and low in reliability. Reference [3] is a pocket chlorine gas alarm device. This device is realized by analog circuit, can only detect the concentration of chlorine gas and give alarm when the concentration of chlorine gas is over-standard but can not connect to the control center. MX48 gas monitor of OLDHAM is the typical representative of foreign products [4]. This instrument is very expensive, can only communicate with control center by cable for short distance, and human-machine interface is not designed properly. According to current situation, this paper develops a chlorine gas online detect device based on embedded technology. Compared with other devices, it is an ideal system with high precision, short response time, high reliability and friendly human-machine interface. This device can communicate with control center by wireless way for far distance. This design has powerful function and flexibility. It can meet the real application in papermaking industry, textile industry, pharmacy, plastic industry and water treatment industry, can prevent the accident of chlorine leakage and guarantee the safety of workers.
The second part of this article introduces the measuring principle of chlorine gas online detecting; the third part introduces the general structure of the system; the forth part is the hardware system designing of the device; the fifth part is the software system designing of the device; the sixth part gives a summary of the whole article.
2. The measuring principle
Constant potential electrolytic gas sensor has advantages of high precision and well stability. It is recognized as the ideal sensor of chlorine gas detecting. The structure of constant potential electrolytic gas sensor is shown in Fig 1: working electrode (WE), corresponding electrode (CE) and reference electrode (RE) are fixed in a container which is filled with electrolyte solution. And this container is sealed with
tetrafluoroethylene permeability membrane. Set the voltage of RE as constant while the sensor works. The WE has the reductive reaction, and the CE has the oxidation reaction. The electrolysis current changes with the chlorine gas density with a direct ratio.
Fig. 1. Structure of chlorine gas sensor
When the sensor works, the relation between electrolysis current and chlorine gas density is shown as follows [5]:
displays them on the screen and sends them to the control center by GPRS. The host control instrument can store and display the historical data of concentration of chlorine gas with the SD card. The control center can analyze and store the data. The detecting range is 0~20ppm. When the concentration of chlorine gas is over-standard, the host control instrument will give alarms and sending signals to the control center. Therefore, this system can prevent the accident of chlorine leakage and guarantee the safety of workers.
4. Hardware system design
4.1. Host instrument hardware system design
Fig 3 shows the hardware structure of host
i = F • A • D • C • n
σi -electrolysis current;
A -diffusing surface area; F -Faraday's number;
D -gas diffusion coefficient;
instrument. It contains processor, RS485 module, SD
card module, Alarm module, GPRS module, human- machine interface module and RTC (real time clock) module. The kernel processor adopted is MSP430F169, witch contain 60KB+256KB FLASH, 2KB RAM, 2 channels of USART and other modules. MSP430 series MCU is 16 bit RISC processor, which are widely1628