As many companies and producers of energy are looking toward establishing a cleaner future, a great amount of consideration is being put into the environmental impact of various fuels. As oil and gas will continue to be used in many industries for the foreseeable future, liquid natural gas (LNG), has become used more frequently, especially in various aerospace applications. Valve World Americas had the opportunity to speak with valve expert Scott Moreland to gain more insight on the future of the valve market, and which valves are best suited for these applications.
By Sara Mathov and Angelica Pajkovic
Expert Scott Moreland believes that LNG has a promising space in aerospace applications. “Fueling systems for rockets are a small industry in itself. Most aero-space groups have decided that LNG is one of the key components for rocket fuels, along with liquid oxygen and hydro-gen,” said Moreland. “Every one of those facilities will use an incredible number of valves, so there is big opportunity in this sector.”
Valves and LNG/Aerospace
Moreland said a main reason that LNG is used for aerospace is because it is condensed, and can fit in a small space. “LNG requires piping systems. As any fluid piping system would, this requires several valves. Having LNG take up less space gives an advantage,” expressed Moreland. “Rockets sit on pads and are not fueled up until its almost time to set them off. They do not want fuel sitting there and elevating in temperature. When they turn it off, they need it to shut down. Therefore, shutdown valves are important in case something happens and operations need to halt.”
As with many piping systems, the valve has to work in both directions. “It must be truly bi-directional, because if something prevents take-off, they want to drain the fuel back out,” said Moreland. “If natural gas is sitting outside in heat, it would expand as it gets warmer, which would not be desirable.”
With a progressive focus on mitigating emissions and producing cleaner energy, valve manufacturers will also strive to provide a zero leakage, bubble tight valves in metal seated applications. “Elastomers can provide that zero-leakage seal in higher than cryogenic temperatures and pressures, but often do not last, or melt away with heat. So, what we will be looking for in metal-to-metal applications, is a metal seal to allow for lower temperatures and lower pressures,” explained Moreland. “Ultimately, severe service applications and zero leakage valves will become much harder to qualify as we transition to cleaner energies.”
Material Selection
“As the materials of construction for LNG and aerospace applications will need to withstand extreme temperatures, and be able to perform very well under various conditions, it will be rare to see something like carbon steel used for these applications,” stated Moreland. “The higher technologies materials, such as duplex and Inconel, will likely be the materials of choice. When choosing the materials, it will also be important to attempt to use as many like materials as possible for the various parts of the application,” he continued. “Additionally, triple offset valves, for example, have an elliptical design. The seat configuration from top to bottom is one dimension, while side to side are another; however, utilizing a full circular design, such as achieved in a quadruple (four)-offset valve, permits for the dimensions to be uniform on the disc including thickness. This circular design allows for an energized O-ring technology to be used. Two different materials can provide a better seal with lower friction. For example, Inconel can be considered for the O-rings and sealing surface. However, Inconel does not expand and contract at the same rate as stainless steel, which could lead to issues with performance if disc & body materials differ from the sealing mechanisms. The materials used should be as like as possible, so the expansion and contraction are uniform. This leads to additional technology in the disc to shaft connections which permit enough free movement as to allow the seal to shift into place without issue when expanding or contracting differently then the body/disc – thus providing for the tighter shutoff in long term usage (high cycles).”
Moreland recalled that very special testing was done for LNG in aerospace. “We tested to extreme conditions. This included 10 thermal cycles, going down to LNG temperatures five times, and back to room temperature five times. Each thermal cycle gets 50 cycles, for a total of 500 cycles. At the end of the test, we had zero leakage and zero emissions,” said Moreland.
What is LNG?
LNG is natural gas in a liquid state. When natural gas is cooled to a temperature of around minus 160° C (minus 260° F) at atmospheric pressure, it becomes a clear, colourless, and odourless liquid. Once liquified, water, oxygen, carbon dioxide,
and sulfur compounds are removed, leaving mostly methane. Natural gas as a liquid is significantly reduced in volume, making it easier to transport. LNG has many benefits, including being non-corrosive and non-toxic. But, due to the extreme temperatures, it could
be dangerous if touched, making storage an important consideration.1 LNG has a well thought out supply chain to ensure proper transportation, storage, and delivery. Elements include the gas field, liquefaction plant, LNG storage tank, LNG tanker, LNG storage tank, vaporizers, and pipeline systems. After tankers deliver the LNG to import terminals, the LNG
is stored, regassified and injected into pipeline systems for delivery to end users.1
Forward Look
Moreland said global efforts are being made for LNG, notably in Spain, with a large LNG regassification facility, and in Trinidad. “The world is moving away from hydrocarbons whenever possible, except for when LNG can be used, since natural gas is a much cleaner process. Many are leaning towards LNG, I can see it as a big industry, and it is still growing,” expressed Moreland.
As many major companies are looking to invest in cleaner technologies, while maintaining their previously established facilities, there will be a unique mix of oil and gas, refining, and LNG production with greener technologies. “There is a lot going on in the industrial sector, both in the United States as well as globally. While a large focus is on newer technologies, such as hydrogen, as it is a new subcategory of energy, oil and natural gas is still here to stay. I think it will be very interesting to see how companies establish a balance between it all as time progresses,” he concluded.
References
1. Liquefied Natural Gas, Government of Canada. Retrieved at: https://www.nrcan.gc.ca/our-natural-resources/energy-sources-distribution/clean-fossil-fuels/natural-gas/liquefied-natural-gas/5679
About the Expert
Scott Moreland is a seasoned valve expert, with a background in valve manufacturing dating back to 1980. His work for manufacturers and with various technologies has helped him work through several workforces and places. He is currently the Vice President of Sales at Quadax Valves. Previously, he worked with several large valve companies, including Petrol-Valves and Cornerstone Valve most recently.