Key Technology Of The Combustible Gas Warning System For Sewerage

The sewerage is an important component of the urban public utility system, it is responsible for collecting and discharging the household waste water as well as the waste water of industrial production. In recent years, many sewerage explosion accidents occurred in many large and middle cities, most of these accidents were caused by the density of ignitable gas (mainly methane) which is excessively high. Because the sewer explosion accident usually occurs in the densely populated area, this causes great loss to human society. However, the traditional way for sewer gas monitoring is based on random inspection by sewer workers, the work is arduous and the information is time delayed. Therefore, establishing the urban sewerage network automatic real-time monitoring system for flammable gas is in urgent need to prevent sewer explosion accident as well as protect environment quality.The urban sewer combustible gas warning system is proposed in this paper according to the characteristics that the heat conductivity of each gas is different, and the combustible gas density in the sewer is measured by special thermal conductivity sensor, which has continuously and automatic monitor ability. This system relies on existing mobile communication network GPRS/GSM to make data acquisition and bidirectional data transfer to and from monitoring center. It features always online, data flow volume based billing, low or no investment in physical equipment and easy maintenance and so on.Based on the predecessor's work, this paper has conducted further research to this system and made great improvement in the following:(1) Reliable realization of the sensor circuit for flammable gas density signal;(2) Realization of the field unit data acquisition and control, mainly including the realization of internet-based FTP data transmission and the Chinese and English mixed short-message commands;(3) The development of monitoring center information management system and alarm system.The innovative idea regarding the Chinese and English mixed short-message commands and the E-mail based alarm system in this paper could reduce the system cost and simplify the development.Besides, the urban sewer combustible gas warning system proposed in this paper could also used for on line monitoring other virulent noxious gas by changing the sensor of data acquisition terminal. The method is of great value in applications for urban air pollution monitoring and other unmanned monitoring situations.