Nitrogen Rejection Units play a crucial role in removing nitrogen from methane-rich gas streams, allowing operators to recover reserves previously deemed uneconomical.
By Joanne McIntyre, Stainless Steel World
The nitrogen rejection sector traces its origins to the oil and gas sector, where some gas fields exhibit nitrogen levels which affect the calorific value of the gas, referred to as BTU value or Wobbe index. Pipeline operators require the gas to meet a minimum BTU content to meet their customers’ specifications, and therefore require the nitrogen to be removed.
In August 2024, Stainless Steel World published an exclusive interview with EPC company BCCK (see box). Fraser McDowell, Director of Strategy and Business Development at BCCK, explained: “We believe our NiTech® Nitrogen Rejection Units (NRU) to be the most efficient nitrogen reduction process, using cryogenic distillation and the Joules Thompson (JT) effect to condense nitrogen out of the methane-rich stream.”
The process is engineered to deliver optimal methane recovery while minimising the environmental impact. The proprietary cryogenic technology requires critical material selection. Austenitic stainless steels have been used extensively for subzero applications to -269°C (-425°F).
“These steels contain enough nickel and manganese to depress the acceptable design into the subzero range. Thus, they retain a face-centred cubic crystal structure when cooling from hot working or annealing temperatures. The tensile strengths of chromium-nickel austenitic stainless steels increase markedly with decreasing temperature,” explained Fraser.
New agreement with ZAP
Recently BCCK signed an agreement with ZAP Engineering and Construction Services, Inc. to deliver a 45 MMSCFD NiTech® Dual Tower NRU and oil removal system. The new cryo-facility will commence operations in Q1 of 2027. The two companies share a mutual goal of advancing gas processing in the Permian Basin.
BCCK’s president and CEO Kevin Blount said, “This will be BCCK’s 46th NRU, a testament to our longstanding, unrivaled experience in nitrogen rejection and cryogenic gas processing. Our technology provides a highly efficient and environmentally friendly design with a very clean vent stream in support of the drive to reduce methane emissions.”
The NiTech series has become synonymous with delivering reliable, cost-effective and environmentally conscious solutions. NiTech NRU technology enables operators to recover reserves previously deemed uneconomical due to high nitrogen or other contaminants. Its small footprint, low power consumption, and high hydrocarbon recovery rates make NiTech a smart choice for operators.
BCCK’s mechanical engineering department is well-versed in material selection for each design case. It ensures that all relevant codes are being adhered to, such as ASME Section VIII for pressure vessels and ASME B31.3 for piping. “Most fabrication is done in-house at our Midland, Texas facility, which is an ASME U and R coded shop and is certified to the ISO 9000 quality standard,” explained Fraser.
Headquartered in Midland, Texas, with a satellite engineering and sales office in The Woodlands, Texas, BCCK was founded in 1980 and holds numerous technology patents. For more information, visit www.bcck.com.
Read the full interview with Fraser McDowell from BCCK, in which he outlines the technology behind Nitrogen Rejection Units and the use of stainless steels in the demanding application here:
Nitrogen Rejection Units utilize cryogenic tolerance of austenitics
About this Tech Article
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