AETHER CT

[Energy Newspaper] The most urgent task for activating the hydrogen economy is to make the hydrogen supply price cheaper, and to do this, transportation costs must be lowered as much as production costs. The key equipment for lowering transportation costs is the ‘tube trailer.’ If the tube trailer’s hydrogen transport volume per transport is increased and the number of transports is reduced, transportation costs can be lowered. Domestic hydrogen transportation is mainly carried out using hydrogen-only tube trailers of 200 bar or less. 

 This is the most realistic method as it can transport up to 320~350kg of hydrogen per transport. Currently, more than 400 hydrogen tube trailers are in operation, centered around hydrogen charging stations.

Hydrogen tube trailers are a ‘blood vessel’ that stores a large amount of hydrogen and runs all over the country, so the importance of ensuring safety and management during transportation is being emphasized. However, hydrogen tube trailers are currently towed vehicles, and the safety measures for hydrogen gas are limited to three: misfire prevention, safety valve, and emergency shut-off valve. In addition, there is no separate monitoring system, and drivers are responsible for safety management on their own, so it is pointed out that they are in a ‘blind spot for accidents.’

Accordingly, Gangwon Technopark Energy Center has launched a hydrogen trailer safety device monitoring demonstration project and has begun to seek ways to prevent hydrogen tube trailer accidents. Our paper visited the Gangwon Technopark Energy Center demonstration site to look into the progress. 

Increasing hydrogen trailer accidents… Safety management is needed

On December 28, 2021, a fire broke out in a hydrogen tube trailer carrying 325 kg of 190 bar hydrogen near the Yuseong Tunnel on the Dangjin-Yeongdeok Expressway in the Daejeon direction. According to the fire department and the media at the time, the accident was caused by a tire fire due to overheating of the vehicle's brakes, which caused the hydrogen tank to overheat, which increased the pressure and caused the safety valve to operate in a timely manner, forcibly discharging the hydrogen in the tank for about 30 minutes, and the discharged hydrogen caught fire, creating a hydrogen flame 10 to 20 m long. 

The tube trailer was severely damaged in this accident, but there were no casualties.

It has been investigated that it has occurred several times overseas as well. In 2019, at the Air Products Transfill facility, a hydrogen gas leak occurred while filling a trailer transporting hydrogen, causing an explosion and fire, injuring two people and damaging nearby vehicles.

In addition, a collision between a hydrogen tube trailer and a pickup truck occurred on a highway in Oklahoma, USA, resulting in the explosion of a hydrogen storage tank, resulting in one death and an evacuation advisory within a 0.5 mile radius. 

As such, the number of hydrogen trailer accidents and damages, including the accidents introduced above, are on the rise. 

Therefore, it clearly shows the need for thorough maintenance of hydrogen transport vehicles and the need to strengthen management and supervision.

Accordingly, Gangwon Techno Park is conducting a demonstration project to monitor the safety of hydrogen trailers by attaching and monitoring sensors related to important safety devices.

▲ Gangwon Techno Park installed sensors in key parts of hydrogen trailers and built a safety monitoring system.

An official from Gangwon Techno Park explained, “Currently, safety inspections before and after driving tube trailers are entirely dependent on the personal management skills of drivers who have completed training from specialized institutions or hold related licenses,” and “Since there is no separate monitoring system, safety management is impossible.”

This demonstration project is planned to monitor the most concerning factors during charging, transportation, and use of hydrogen tube trailers. 

First, it is monitoring the misfire prevention device during charging and shipment. Currently, it is managed by the inspection of the tube trailer driver. Accordingly, we plan to establish a safety monitoring system by attaching sensors to each major part, such as △whether the pneumatic connection part with the tractor is detached during tube trailer charging and transportation, △whether the landing gear is fixed when raised, and △whether the high-pressure tube is detached and the safety protection device is inspected.

In addition, there is a risk of a rollover accident that can cause a major accident if the landing gear for securing and preventing the trailer from falling after the tractor-trailer is separated falls off during operation and gets stuck on the ground, so a landing gear monitoring sensor is also attached for safety. 

In addition, a gas detection sensor is attached to prevent hydrogen gas leakage during operation. If the tube trailer is at a charging station (shipping yard), safety can be secured through the gas detection sensor at the charging station (shipping yard), but if hydrogen gas leaks during operation, it is extremely dangerous because there is no gas detection sensor.

An official from GE, which developed the monitoring program, said, “Hydrogen tube trailer accidents do occur occasionally, but there are many types that can be sufficiently prevented in advance. GE has applied a safety monitoring system to a tube trailer currently operating in Samcheokgyo-dong and is currently monitoring safety-related issues related to hydrogen tube trailers on the platform,” and predicted that this safety monitoring system will completely alleviate the public’s anxiety.

 Currently, Gangwon Techno Park is attaching a safety monitoring system to three hydrogen tube trailers currently under its management (one owned by Gangwon TP and two owned by Gangwon Province), and is verifying the safety management system for: △towed vehicle coupling, △air/power cable coupling, △landing gear fixation, △misfire prevention device operation status, and △gas detection. Through this, the plan is to verify the platform operation of the hydrogen infrastructure monitoring system and verify failure monitoring using facility vibration sensors. The official explained, “This demonstration project is a demonstration project to build a monitoring platform based on IoT that links safety sensors to the entire infrastructure, including hydrogen production facilities, charging stations, and tube trailers. 

In particular, the safety detection system for hydrogen tube trailers was developed by selecting appropriate sensors that can be used for electrical and mechanical sensors and many lubricant-based ones, and considering integrated location, explosion prevention, and communication.”

Through this project, Gangwon Techno Park is establishing an IoT safety management system at three locations: Samcheok Obun-dong Hydrogen Charging Station, Samcheok Gyo-dong Hydrogen Production Facility, and Samcheok Gyo-dong Hydrogen Bus Charging Station, and is conducting facility operation monitoring and cause analysis in case of failure. 

In addition, it plans to eliminate safety insensitivity through a safety monitoring system that transports hydrogen via hydrogen tube trailers, such as kingpin engagement status, trailer support leg status, hydrogen detection, and tube trailer location confirmation.

In addition, each hydrogen charging station and production facility will be equipped with an IoT safety management system and an ‘edge server’ that can temporarily store, convert, and transmit data. 

The remote server and monitoring system control room that will store the data transmitted from this edge server are planned to be built in the Gangwon Techno Park Energy Center in the future. Gangwon Techno Park believes that if this monitoring system operates smoothly, it will be able to help resolve hydrogen safety insensitivity by disclosing to the general public the status of hydrogen leaks and safety sensor operation at hydrogen production and charging facilities through the monitoring platform.

It also provides efficient facility operation tips to production facility and charging station operators through real-time safety data and quick notifications in case of failure. 

In addition, it is expected that the analysis of data accumulated during the verification period will help analyze the cause of accidents and find customized solutions.

*Source: https://www.energy-news.co.kr/news/articleView.html?idxno=212859

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