2016_1 Engineering safer flaring is no accident master

Engineering safer flaring is no accident

Following the Paris agreement in December, limiting greenhouse gas emissions is factoring even more heavily into companies’ purchasing decisions. Wärtsilä’s flare gas recovery system reduces the need for continuous gas flaring and the harmful emissions it causes, and, with a newly engineered e-pellet for its ballistic ignition, conducting intermittent flaring is now even safer and more reliable.

Text: HÅVARD BERTHEUSSEN & ØYSTEIN YTREARNE Photo:

According to the World Bank, the recovery of gas currently flared or vented by the oil industry is a prime way to meet increasing fossil fuel demand and reduce harmful emissions, as flaring gas accounts for about 400 million tons of CO2emissions every year. Flaring can also release smoke containing toxic chemicals, which have further climate impacts and may cause health problems in nearby communities.

To enable utilization of gas that traditionally would be burned during flaring, Wärtsilä’s flare gas recovery system makes it possible to recover the gas safely and cost effectively for other purposes. Along with using that gas for export or re-injection, fuel gas, power generation or for production of LNG, LPG or NGL, the process also offers a substantial reduction in CO2 and NOx emissions compared to continuous flaring.

Even when gas is being recovered, small amounts of gas still need to be flared or vented to reduce the risk of fires or explosions. However, employing proper equipment maintenance and appropriate technology helps keep this already small volume of gas and emissions as low as practicable.

When conducting intermittent flaring, a pilot flame may be maintained for igniting the flares. In contrast, with Wärtsilä’s flare gas ignition technology, even the emissions from a pilot flame are prevented. Furthermore, the safety and reliability of any ignition system is essential in avoiding economic impacts caused by downtime. So, while the basic technology behind Wärtsilä’s ballistic ignition pellet system is already decades old, the latest development guarantees a safe and reliable ignition of the flare whenever required.

The original design for a ballistic ignition pellet system came to be in 1989 when a pellet, apyrotechnic article (like an Independence Day or New Year’s Eve rocket), was fired from a cannon in a 12m freight container. This open trajectory system had lots of flaws, but it got the idea started. The military’s strict standards on security and integrity influenced the next steps of system’s development.

2016_1 Engineering safer flaring is no accident 2
The e-pellet takes the advantages of the low-pressure pellet one step further with electronic operation. The e-pellet’s actual size is 100 mm in length and 20mm in diameter.

First, the system was moved out of an open area and into an enclosed pipe. Removing the effects of wind created more stability and accuracy. Then in 1994, a high-pressure system was developed. Now obsolete, the system, which was mainly used in Norway, only remains in a handful of places.

Following in 2001 came a low-pressure system that was revolutionary. The intricate design incorporated all the technology within the LP2000 pellet itself. In contrast to the high-pressure pellet, which required a hard, 200 barg impact to activate it, the low-pressure pellet only required an initial 5 barg launching pressure to arm it and move it through the guide pipe. Then it was activated when actually leaving the pipe.

From introduction on the Norwegian continental shelf, use of the low-pressure pellet system started to catch on in other locations, such as Oman, India, the US and Europe. The benefits of the low-pressure technology are its high reliability (99.8%) and low maintenance requirements. Wärtsilä’s low-pressure pellet has a relatively indirect ignition compared to rival technology, which depends on more direct contact with the flare flame and needs to be replaced after it burns out. Furthermore, the system is a stand-alone one, which does not need to be attached to other components.

The mechanical version of the low-pressure pellet (LP2000) received the highest achievable safety classification (1.4S), and Wärtsilä offers operator training to reduce any risk of improper use. However, it is not completely fool proof because there still exists the possibility of human error.

The newest improvement takes all the advantages of the low-pressure pellet one step further by making the pellet’s operation electronic, hence the name e-pellet. Although its function is equal to the LP2000 pellet,the e-pellet comes with many advantages: ease of use, reliability and, perhaps most importantly, improved safety.

With the purely mechanical version, the only way to remove pellets from the magazine is by firing them. The electronic one (e-pellet), in contrast, has a “kill battery” function that, in cases of malfunction, renders the pellet harmless after 6 minutes. With e-pellets, someone can work on the system or remove the e-pellets from the magazine without risk to personnel or equipment because the e-pellets will not ignite if not armed by the electronic trigger. In addition to being engineered against the potential for human error, in the case of any malfunction, the e-pellet provides the possibility of fault-finding due to its built-in software diagnostic tools.

Putting these new benefits to work is also simple. The lead time for new orders is low, and those customers with the older system can easily upgrade to use the e-pellet with their existing system. The process merely requires installing a set of four, clamp-on magnets to the guide pipe and can completed within an hour.

With such safe and reliable functioning, Wärtsilä’s e-pellet flare gas ignition system is an ideal component in operations employing only intermittent flaring. Pairing the e-pellet ignition system with Wärtsilä’s flare gas recovery system further reduces the need for flaring, thereby preventing wasted energy and the climate impacts of such significant emissions.

 

Wärtsilä flare gas ignition

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