Seal it – and protect the climate

Natural gas is transported in pipelines over many thousands of kilometers to destinations around the globe, both overland and via the seabed. The flow of gas must be prevented from ebbing and drying up. Every now and again, giant compressors, like springs, with the power of about 100 car engines provide the necessary boost. But in the process, methane gas escapes. Until now, at least. The recently developed zero-emission mechanical seal, CobaDGS, from EagleBurgmann uses nitrogen to prevent these harmful emissions. The sealing innovation makes a sustainable contribution to curbing global warming.

Methane is the main component of natural gas and has a much greater greenhouse effect than carbon dioxide (CO2). Dr. Ferdinand Werdecker, Director of Engineering for Compressor Seals at EagleBurgmann predicts: If all the compressors in German pipelines no longer allowed the escape of methane emissions directly into the atmosphere and were instead sealed with CobaDGS, 15,000 tons of direct methane gas emissions could be avoided annually. This corresponds to 1.3 million tons when converted to carbon dioxide (CO2), which is equivalent to the annual CO2 emissions of around 600,000 private households. The new sealing technology could save four times this amount throughout Europe, and even fifty times the amount worldwide – equivalent to more than 63 million tons of CO2 per year.

How does EagleBurgmann’s sustainable sealing solution work? The compressor’s power is transmitted via a shaft to a blade wheel driving the flow of natural gas in the pipeline. The shaft sleeve through the compressor housing must be sealed. But this has always resulted in leakage – and even with technically sophisticated solutions such as dry gas seals, methane gas escapes.

Dry gas seals have a stationary and a rotating ring, whose contact faces almost touch. Less gas escapes if the gap is narrower, meaning the transport of gas is more cost-effective for the operator and the negative impact on the environment is less dramatic. The CobaDGS uses nitrogen to seal even this remaining gap, which is only two or three thousandths of a millimeter wide. The somewhat higher pressure of the “nitrogen barrier” prevents gas from flowing through the gap and escaping.

“We’ve advanced this basic principle to work at high operating pressures of up to 160 bar for the main seal. We use it for most of the compressors,” says Werdecker.  A further benefit: Thanks to gas lubrication, the CobaDGS operates almost wear-free and, with proper maintenance, its service lifetime is virtually unlimited.