Gas Leak Detection System With Remote Communication

Published Date: 02 Nov 2017

Abstract

Chemical process Industry handles multiple gas based products and need major safety methods for calamity prevention. With increasing research activity in Chemistry and Chemical Technology, it is but natural that safety measures have to be highly advanced. With multiple experiences all over the world it has become mandatory for Infrastructure to be planned with utmost safety as the primary criteria in this Industry. The need for continuous monitoring and control is the main safety requirement to prevent hazards, mainly for persons involved and then for environmental protection. Utilisation of hazardous gases also has become a productive tool in Chemical Industry for many Products of use and this calls for strict implementation with technology for centralized monitor and control coupled with disaster recovery for rescue and rehabilitation. Communication Technologies of newer generations provide for such opportunity and in place of connected systems for monitoring, wireless networks help in meeting the above mandatory requirements, WIRELESS SENSOR NETWORKS being the best example for such networks.

Necessary hardware and software platforms provide making use of Embedded System and Communications concepts enabling Centralised monitoring, from a remote location than in a hazardous environment. And the system reported in this paper functions in real time environment, speedier and is highly accurate.

Key words:

Introduction

In modern industries many are Gas based and particularly In high-risk industries such as chemical, pharmaceutical, electricity generation and cement industries, small negligence may result in human losses, economic losses and serious environmental pollution.

Hence many large companies are to meet mandatory standards to prevent hazards. This results in infrastructure investment to upgrade existing equipment. However there are avenues to increase the methodology of accuracy, real-time communication and actual incident location identification. Most of the current equipment is based on wired networks, it is backward in technology and hard to be deployed; the technology of data acquisition in accidents is also backward and so it is hard to locate the leakage point [1]. These problems can be solved with the help of WSN. WSN has absolute superiority on data acquisition and transmission.

In order to improve the rescue quality, shortens the time for rescue, and to achieve not only production safety also ensure worker’s safety in Industries. There is necessity to develop a system in order to detect and monitor the hazardous gas leakages. These leakages mainly caused by erosion, bad connections and external forces and so on. The leakages may occur at joints of containers, reaction kettles and pipelines and places that are exposed for erosion or broken [2]. In this thesis a system is designed based on embedded system using WSN [3]. This system consists LPC2148 microcontroller [4], MQ-2 Gas sensor [5] and ZigBee RF module as a hard ware [6], keil µvision4, flash magic as software are required.

The LPC2148 is known as ARM7TDMI, which belongs to ARM family. ARM7TDMI is a 16/32 bit processor, capability of processing of 16 bit as well as 32 bit instructions. It has 40kB of on-chip static RAM, 512kB of on-chip flash memory and 128-bitwide interface/ accelerator enables high-speed 60 MHz operation.

Gas sensors (MQ-2), used in gas leakage detecting equipment in industries and domestic purposes, are suitable for detecting of LPG, I-butane, propane, methane, alcohol, Hydrogen, smoke.

The data transmission between the transmitter and receiver is done using XBee RF Modules operated within the ZigBee protocol and support low-power wireless sensor networks [7][8]. The modules require minimal power and provide reliable delivery of data between remote devices.

The paper has three parts, first, gives the overall system design, and then provides the approaches on both hardware and software to achieve it.

Structure of the System

In this thesis, to develop the embedded system the methodology is as follows: Here two hardware boards are prepared. One is transmitter and second one is the receiver. In the transmitter side gas sensor measures the leakage value whenever the gas comes into contact with the sensor and sends its output to the LPC2148 through one of the ADC pin. After reading the sensor information by the LPC2148 those values are displayed on the LCD. Here the LCD is interfaced in 4-bit mode. At the same time those values are transmitted to the receiver with the help of XBee (RF). In the receiver side XBee module is interfaced to the LPC2148 to receive the data which is sent by the transmitter. In the receiver side also LCD is interfaced in 4-bit mode and sensor values are displayed on the LCD. After receiving the data the values are updated to the system through serial communication. One set point arranges on both sides. If set point crosses (3.5 V) then buzzer will ON.

Figure2. System Diagram of the Transmitter and Reciever

System Design

Hardware Design

The experimental setup of the proposed system as follows, it consists of two sections: one acts as transmitter and other acts as receiver. Here the transmitter section treated as the remote terminal and receiver section treated as control station. The remote terminal is placed in various location in industries where to find the leakage detection necessary. This remote terminal collects the data from the leakage area and sent to the control station, so that time required to prevent the rescue can be minimized. The below figures shown are transmitter and receiver sections of the gas leak detection and monitoring system respectively.

The hardware setup of transmitter section is shown in fig 7.1, consists of gas sensor, ZigBee and LPC2148. The interfacing of the gas sensor, LCD and ZigBee as follows. Gas sensor consisting of 6pins i.e. two sets of A, B and H and is interfaced to the LPC 2148 as shown in the figure and the sensor output is given to the one of the ADC pin, here the output is given to the P0.28. So that microcontroller read the values from the sensor and collected data will be displayed on LCD (here LCD is in 4-bit mode). The LCD is interfaced to the microcontroller through P0.16, P0.17, P0.18, P0.19 and P0.20 respectively. At the same time data given to the Xbee module to transmit the data to receiver .The Xbee module is connected through P0.9 (UART0) of the microcontroller.

Figure2: Hardware setup of Transmitter and Receiver

The hardware setup of receiver section is shown in Fig 7.2, consists of ZigBee module, LPC2148 and Buzzer. At receiver section the Xbee module collects the data sent by the transmitter. This Xbee module is connected through the one of the UART0(P0.9) pin of the LPC2148, then microcontroller sends the data to the LCD at the same time it update the values in PC. The microcontroller sends the data to the PC through another UART1 (P0.20) pin. This data will be displayed on PC by using hyper terminal.

The functionality of the leakage detection and monitoring is: gas sensor takes analog input whenever the leakage gas comes in contact with the sensor and gives the analog output to the microcontroller. These values read by the microcontroller, displayed on the LCD and at the same time it sends the data to the receiver via the Xbee module. The receiver receives data from the Xbee module on receiving side. These values are read by the microcontroller, displayed on the LCD and at the same time update the values on PC.

Software Design

ZigBee WSN has three kinds of nodes: the coordinator, the router (or FFD) and the end device (or RFD). There are no marked qualitative differences between them on hardware design. The main difference is on communication software design. As the gateway of the ZigBee WSN, coordinator automatically initiates the formation of the network. After that, it will wait on until all the nodes nearby finished joining in the net. Then the coordinator will sent instructions or collect information such as the connection status, sensor data and location data, and then sent them to the control center to update value in the location software. All these processes are completed in a specified number of regularly timed execution cycles. The flow chart of coordinator is shown in Fig. 8

Conclusions

An embedded system is developed to detect and monitor the hazardous gas leakages. The system comprises LPC2148, gas sensor, and ZigBee WSN which provides low data rate, low cost, low power and low maintenance. It detected and monitored the gas leakage as per the sensor data during leakage simulation. This system is based on WSN; it is easy to be deployed compared to other systems. So this helps to improve the rescue efforts and shorten the rescue time in industries effectively.

The network technology in this thesis is based on the application of ZigBee protocol but implemented for point to point link only. However, future application can use point to multipoint which is the strength of ZigBee against Bluetooth. This needs to prove the algorithm in a multi transmitter and single receiver environment. The change in protocol can be optimized for the near environment.

Acknowledgements

The authors acknowledge the support of the Laboratory faculty who helped in rigging the designed circuits and participated in the successful testing.