American LNG Pumping Up

Cheniere's Sabine Pass LNG terminal is leading the way with Cove Point's commissioning capping a strong 2017 for US LNG export growth. The number of facilities coming online are set to quadruple the current production capacity by 2019.

Here are some highlights from Jordan Blum’s article:

-       Sabine Pass complex recently added its fourth LNG unit and started shipping cargos this fall, solidifying its position as the world's largest LNG exporting terminal outside of Ras Laffan Industrial City in Qatar.

-       Virginia's Dominion Energy prepares this month to become the nation's second LNG exporter, operating from its Cove Point terminal in Maryland

-       Houston-based Kinder Morgan's Elba Island LNG project is scheduled next year to begin shipments out of Georgia. 

-       The first LNG export terminal in Texas is slated to open in late 2018 when Houston's Freeport LNG is expected to begin operations at its Quintana Island terminal.

More on Cove Point from Justin Jacob’s:

-       Dominion has started taking in feed gas for liquefaction, making first exports imminent. -The facility is fully contracted for 20 years to sell gas to a joint venture between Japan's Sumitomo and Tokyo Gas as well as India's GAIL, some of Asia's biggest LNG buyers

Bonus: Check out some of the US shipments headed into Japan and export data at Genscape, thanks to Jason Lord.

Qatargas’ Involvement in the future of LNG

Qatargas Plans to Maintain its Presence as Global LNG Demand Increases.

Doha Night Skyline for Qatargas LNG Blog.jpg

Global LNG demand is projected to hit 500mtpa by 2030. That is a year to year growth of nearly 5 percentage points on average. With that Qatargas is pushing into the expanding market of LNG as a marine fuel and diversifying in other ways to maintain their position in the LNG market. Complete details on The Peninsula here.

Good News For US LNG & Information About Where the Cargo is Heading

Liquified natural gas from the USA was exported at 109 Bcf in December, and the future is looking better with shipments expanding to Northeast Asia. In 2016 most of the US produced LNG went to South America, but the newer shipments are most likely headed to Northeast Asia, which is all good news. More details below from Gregory Brew and Argus.

"Northeast Asia becomes main market for US LNG

One of the main advantages of US LNG is that it does not have destination restrictions like LNG from other producing regions. "  Source: Argus

"A Rosy Future For U.S. LNG

Four countries in South America received fifty-four percent of all American LNG in 2016"  Source: Gregory Brew

Experiencing LNG Pump Vibration Time Waveform Instability or a “Ski Slope” in the Vibration Spectrum? Try This Easy Fix.

Before taking the drastic steps of troubleshooting mounting or cable issues, or even upgrading the transducers, try this easy option: increase the supplied excitation current to the accelerometer probe.

Clients often have vibration waveform data that is erratic, unreasonably or impossibly high, or a velocity spectrum with the “ski slope” effect, as seen in figure one. Most of these inaccuracies can be traced back to mathematical errors – errors which are compounded when used to process flawed acceleration data. Although software keeps improving, no software will be helpful when processing inaccurate data. Therefore, it is necessary to provide the best data possible for any analysis. The mathematical transformation of acceleration data to vibration spectrum data is very sensitive and highly effected by noise and instability in the system. Generally, mathematical inaccuracies increase the more the data is processed, causing false waveform RMS values and incorrect spectrums because the errors from the integrated noise will have larger magnitudes than the actual equipment vibrations. Increasing the power to the vibration probe loop can stabilize signals and the data that will be received for processing.

 

Fig. 1: Example of Vibration Frequency Spectrum from Acceleration Data that shows “Ski Slope” effect.

Looking at the specification sheet for PCB’s 351B41 cryogenic sensor as an example, it is known that the constant current excitation range is from 2-20 mA. Most rack systems are configured to output 2-3.5 mA, but this can be increased through modifying the configuration of the rack or by adding a constant current source to the system. Increasing the supply current has been shown to improve signal quality – especially on in-tank retractable type pumps where the rack is hundreds of meters from the actual accelerometer probe.

The effects of noise and drift in the system can be eliminated by increasing the excitation current to varying amounts, depending on the system. Of course, it is important to ensure that the output does not exceed the rated excitation current of the transducer or the system. Increasing the output current to the transducer has stabilized both vibration velocity time waveforms and also eliminated or greatly reduced “ski slope” issues or lower ghost frequencies in velocity spectrums at multiple LNG regasification plants.

Looks can be deceiving. Whether the pumps have recently been commissioned or they have been running fine for years, make sure to check the spectrums for 1x prevalence to ensure you do not have faulty data. There have been documented cases in which the waveform RMS values for these pumps were within acceptable ranges, but the data was nonetheless faulty. After further analysis it was clear that the data was faulty. Despite the sum of the energy of the spectrum giving an overall acceptable value, the spectrum had little to no energy content at the operating speed of the pump.

Of course, increasing the excitation current is not a cure-all. Problems with cables, mounting, or transducer overload can cause these same issues. But the increase of the current supply can be done without ever needing to take your valuable equipment offline.

If you are experiencing issues with your cryogenic submerged motor pump’s vibration monitoring system or would benefit from a specialty review of the data, feel free to contact NICHE Cryogenic Solutions.

Chuck Blackett

Chief Engineer - NICHE Cryogenic Solutions

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