Across the 76 companies in the ranked assignee list, one applicant leads with 310 records, well ahead of the fifth-ranked company at 50 and the tenth-ranked at 26. That gap suggests a single applicant family has filed continuously on this technology rather than a cluster of similarly sized competitors. The ranking covers only the entities the data endpoint returns, not every company that has ever touched the space, so smaller or newer entrants may not show up prominently yet.

Both modes appear in the search scope for this dataset, and they are typically claimed as switchable operating states within the same demethanizer and reflux architecture rather than as separate plants. Patents in this space tend to claim the column-overhead reflux and residue-gas compression control logic that lets an operator toggle between the two modes depending on ethane market value. Because the underlying hardware overlaps heavily, freedom-to-operate analysis usually needs to look at the control and reflux claims rather than treating recovery and rejection as distinct technology families.

The dataset shows filings climbing from 23 in 2017 to a peak of 35 in 2018, the highest single year recorded in this scope. Filings compared on complete years fell from 10 in 2021 to 7 in 2024, a -30% change, though this should not be read as the technology losing relevance — dense early filing on core cryogenic separation architectures can itself reduce the number of clearly patentable follow-on filings. Readers should also note that 2025 and 2026 counts are still incomplete because publication typically lags actual filing by around 18 months.

US20210156613A1, assigned to Linde Engineering North America and filed in 2021, claims a pressure-management sub-system that connects a demethanizer column's overhead (or an NGL expander) through a separator and pump into a nitrogen rejection unit's distillation column. It blocks that specific conduit-and-pump sequence, not nitrogen rejection as a general concept. Designs using turbines, ejectors or direct compression to manage pressure between the demethanizer and NRU sit outside the embodiments this filing describes, so a targeted clearance review of the exact process flow is more useful than assuming blanket coverage.

The IPC composition data points to three thin branches relative to the dominant F25J classification: F01K (steam and thermal power plant integration, 0.6% of the 980 records), B01J (catalytic and physical processes, 1.5%), and F17C (pressure vessels and gas storage, 2.6%). None of these appear among the most-cited records in the dataset, meaning there is no concentrated incumbent to design around there — the main risk for a new filer is obscure single-applicant prior art rather than a blocking portfolio held by a market leader.