Detecting Faults

Solutions for real-time visibility of gas leakages

The city gas distribution (CGD) sector is set to witness significant growth in the coming years. India has a high potential for gas demand, and is expected to become one of the largest gas consumers globally.  Currently, 70.86 per cent of the total population and 52.8 per cent of the total area of the country have been covered by the CGD network. After the completion of bidding rounds 11 and 11 A, 98 per cent of the population and 88 per cent of the geographical area of the country are expected to be covered.

The number of piped natural gas networks in the country has increased at a compound annual growth rate of about 21 per cent from 3.61 million connections in 2016-17 to 9.35 million connections in 2021-22. As of January 31, 2022, a total of 352,961 inch-km of steel and medium density polyethylene pipeline has been laid by CGD entities across the country. Despite the huge potential of the gas sector in India, there are several concerns when it comes to CGD, specifically related to its pipeline network infrastructure.

Challenges

The CGD sector is currently facing many challenges. The pipeline network is being expanded ba­sed on demand. Solutions cannot be confined to specific geographical areas (GAs) as is the case with petrochemicals and refineries. More­over, there are geographical and distance-based challenges. Further, the pipeline network is complex, which is not ideal for laying cables.

Other concerns involve district-regulating skids and field-regulating stations located near high density populations. For these, any gas leakage or fire can be catastrophic. These stations are in un­controlled/unmonitored environments guarded by singular security guards, who cannot prevent gas leaks. If leakage occurs and is noticed by the security guard, they inform operational and management personnel. By the time the concerned personnel arrive, it might be too late. Thus, these stations are a potential source for conflagrations.

Conventional solutions include controllers and detectors connected via wires. Data collection for monitoring can also be done using a supervisory control and data acquisition (SCADA) system, but this would be a conclusive decision for CGD players. Laying cables across such long distances is not feasible with the available technology, and wireless networks are quite expensive.

Moreover, maintenance remains a serious concern, as GAs cover multiple towns, cities or even states, and it is difficult to maintain each and ev­ery location in a GA.  Thus, there is a need for a di­gital solution that requires no maintenance while also making the system easier to monitor. Preferably, such a digital solution would have all its nodes working on rechargeable batteries. The central node controller, which is the gateway, would work on 220 volt amperage and frequency (VAC). Electricity available at the station should be sufficient for the gateway to work. The communication should be based on a 2G/4G network gateway and impart SMS alerts. No ma­nual intervention or third party would be required to detect or notify leakages. Finally, the system should not be dependent on the gateway.

Remote reading device

A remote reading device is a wireless gas detector that is carefully designed to tackle practical issues faced by CGD partners.

Our new remote reading system has received an ATEX-certified enclosure with ingress protection 68 rating. It contains a rechargeable battery that needs to be recharged every six to eight months.It has an expected life of over six months, de­pe­nding on the number of alerts and alarms. It uses a non-dispersive infrared (NDIR) sensor with a T90 response time of less than five seconds. An alert is raised the moment there is gas leakage. It also performs self-diagnostics: every day at a predesignated time, it sends SMSs to users with information about the status of the device – whether the battery is working fine, what the signal strength is, and how the device is performing overall. Thus, the health of the system can be monitored easily and daily. One can choose to receive direct SMS alerts or institute a gateway for gas leakages. The system works on 2G/4G network and has zero installation and maintenance costs.

The system also has some optional features. For instance, Bluetooth can be used for remote configuration, and there is a 24/7 display option. Mo­reover, the system utilises a server-based tech­nology that delivers data directly via the in­dustrial internet of things and cloud. Finally, the­re is no distance-based limitation.

Most detectors have antennas requiring specific hazard-proof certification. But the detector in this system has an internal 2G/3G/4G antenna. This eliminates the need to get separate approvals for external antennas.  Moreover, there is a graphical display so that even people without technical training can understand and handle the system. The sensor is housed in an ATEX-approved 316 stainless steel enclosure. The system also includes ATEX-approved transmitter housing and a magnetic reed switch. Most notably, the system includes a special kind of housing that integrates the battery, electronics and display into a single unit. There is also a separate unit for the battery. It has an integrated battery enclosure. Further, it uses a mirror-less/lens-less NDIR sensor to avo­id condensation in conditions of high humidity. This gateway can communicate with 32 sensors at one time. It has an LCD display showing complete information.

It comes with a relay connection through which one can initiate a mitigation system, and double pole double throw relays for alarm annunciation. It involves RS-485 output, which is generally used for SCADA communications or to communicate with third-party systems for data acquisition. It works at 230 VAC power. It has dynamic LEDs for status indication. Each issue has an LED indicator. It also has a user-friendly keypad.

This device has 1/10th the installation cost of a solar device. Further, there is no maintenance cost, and no danger of pilferage or damage by wildlife. The cost of an ATEX-certified solar panel is substantial, further exacerbated for solar devices to be installed in Zone 1 or 2 regions. There are no external elements, resulting in high mean times between failures. Currently, the system has been deployed by GAIL Gas Limited in India’s National Capital Region. n

Based on inputs from a presentation by Debojyoti Mandal, Lead, Sales and Marketing, First Sense Safety, at a recent India Infrastructure conference