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.