US 11255537

I'll run a couple of targeted searches, then summarize against the authoritative patent text provided.

One more targeted search to confirm litigation status.

Summary of US 11255537 B2 — "Metallic Burner Tiles"

Note on identifiers: I've read the number literally as 11255537 (granted as US 11,255,537 B2). All of the following is drawn from the authoritative full text you supplied, cross-checked against search results.

Bibliographic data

Abstract (as granted)

"The present disclosure seeks to provide a metallic burner tile for use in industrial processes such as cracking. The tile is substantially metallic (e.g. more than 80%) with the balance being ceramic coating on surfaces exposed to high temperature. The tile is lighter and more durable than the current ceramic burners."

Plain-language overview of the independent claim

Only claim 1 is independent; claims 2–15 all depend (directly or indirectly) on it.

Claim 1 — A burner that is substantially metallic (spec defines this as ≥80% metal by weight, i.e. ≤20 wt% ceramic/refractory), built to survive a service temperature of ≥ about 1200 °C in a cracking furnace whose walls run 700–1350 °C. The claim requires, in combination:

1. A metallic flow passage for gaseous oxidant with an upstream inlet and downstream outlet, whose wall has an internal surface and an external surface facing the furnace.
2. At least one baffle that directs oxidant (or oxidant + fuel) against the internal surface of that wall — i.e. the flow is deliberately thrown against the metal to convectively cool it.
3. Ribs forming at least one continuous series of parallel channels on the internal surface of the portions exposed to the cracking furnace, with a channel height:width ratio of 0.1 to 2 (additional convective heat-transfer surface).
4. A metallic fuel line terminating near the external front surface at 25–75% of the front height of the flow passage.
5. Wall thickness of 4–25 mm.

Structural specifics recited in the claim:

• A lower metal flow section: open back end, closed lower side walls, closed bottom wall, a top wall that stops short of the side walls to create an open upward-facing vent at the upper front end, and a lower front wall continuous with the bottom wall.
• An upper metal flow section forming a chamber defined by an upper front wall connected to the lower front wall, upper side walls, a back wall, an open top, and an open bottom that mates with the vent. The upper front wall and back wall have aligned openings (same height and lateral position) for fuel supply lines to run front-to-back. The upper front wall is the wall whose external surface faces the furnace.
• Either (a) one or more metal or ceramic-coated-metal top plates over the open top, with a planar surface, a curved leading edge, one or more circular passageways, and a back section with polygonal oxidant outlets; or (b) a continuation of the upper front wall running back to the back wall, with a curved leading edge, circular passageways, and a planar back section with polygonal outlets that is ceramic-coated.
• The at least one baffle extends into the upper metal flow section (per dependent claim 2, this is a descending baffle).

Dependent claim ladder (brief)

• 2–3: descending baffle positioned ≤10% forward of the outlet lip, descending 50–90% of front-face height (note: the summary's 10–50%/15–30% figures in the specification text differ — the claim recites 50–90%), spanning 75–100% of burner width with equal side openings, plus ribs on its forward face.
• 4–7: adds an ascending baffle from the lower section's top wall projecting into 45–85% of the chamber open area, bent upward parallel to the upper front wall with pass-through channels, ribbed, with channel h:w of 0.1–2.
• 8–11: top plates present and either bare metal or ceramic-coated metal.
• 12–15: upper front wall continues to back wall, with or without ceramic coating on the back section.

Prosecution and prior art of record (14 citations, 1 NPL)

Notably cited: GB 1,480,150 A (Associated British Combustion, "Burner quarls" — expressly discussed and distinguished in the specification as teaching a double-walled quarl); US 2010/0021853 A1 (Bussman, John Zink — distinguished as ceramic/refractory tile-based); US 3,630,176; US 3,684,424; US 4,702,691; US 6,979,191; US 2002/0015932; US 2004/0018461; US 2009/0075223; US 2013/0115564; US 2014/0102440; US 2017/0336068; US 2016/0169522; EP 1 073 140 B1; and the NPL reference Omori, "Development of Ultra Compact Low NOx Burner for Heating Furnace," 1998 International Gas Research Conference, pp. 269–276.

Prosecution history shows a non-final action (2021-03-11), final rejection (2021-08-04), after-final response (2021-10-07), and allowance (2021-10-14). Consistent with that, the granted claim 1 is materially narrower than published application claim 1 (the published version made the convective-surface arrays optional; the granted claim makes ribs/channels mandatory with a defined aspect ratio and adds the fuel-line position and 4–25 mm thickness limitations).

Litigation / PTAB status — searched, nothing found

• No Court of Appeals for the Federal Circuit appeal, PTAB proceeding (IPR/PGR), or U.S. district court case involving US 11,255,537 was found in my searches. I could not query the CAFC docket system or USPTO PatentCenter/PTAB directly, so I cannot state with certainty that none exists — only that my web searches returned none.
• Caution on a false positive: searches for "Nova Chemicals" + 2026 appellate activity return the Alberta Court of Appeal Nova Chemicals v. Dow Chemical Canada dispute (approximately C$3.56 billion judgment; stay denied 2026-02-23 by Justice Jolaine Antonio; merits hearing set for November 2026) and the Canadian plastics-listing reference (Canada (Procureur général) v. Coalition pour une utilisation responsable du plastique). These concern an ethylene plant joint venture and environmental regulation, not US 11,255,537, and should not be conflated with it.
• Google Patents' own "Cited By" list shows only the family continuation US 11,885,489 B2 as citing this patent.

Confidence and uncertainty

High confidence on all bibliographic, claim, and prosecution details, which come directly from the patent text you provided and are corroborated by Google Patents, Justia, and IDIYAS listings. Lower confidence on the litigation/docket result — absence of search hits is not proof of absence of proceedings, and I did not have authenticated access to CAFC or PTAB docket databases. Note also a minor internal inconsistency in the source document: for the descending baffle, the summary section states descent of "50 to 90%" of front-face height while the detailed description of FIGS. 1–2 states "10 to 50%, or from 15 to 30%"; claim 2 recites the 50–90% range.

I'll search for litigation involving US patent 11255537 across patent litigation sources.

Let me search more targeted litigation databases.

Let me check a few more litigation-specific sources to be thorough.

Litigation Search Report — U.S. Patent No. 11,255,537

Patent identified: U.S. Patent No. 11,255,537 B2 ("Metallic burner tiles"), Application No. 16/314,901, filed 2017-06-01, priority date 2016-07-08, granted 2022-02-22, current assignee Nova Chemicals International S.A., adjusted expiration 2038-08-02. I used that exact number throughout and did not substitute any similar number.

Finding: No litigation located

I did not find any litigation involving U.S. Patent No. 11,255,537. Based on the sources I was able to query, there is no known district court action, ITC investigation, or PTAB proceeding naming this patent.

Sources searched and what they returned

Important context on the family (not litigation)

• US 11,885,489 B2 — a continuation of the '537 patent (filed 2022-02-03, granted 2024-01-30), same assignee. This is a family member, not an adverse party.
• US 16/314,879 ("Metallic burner components") — abandoned family application.
• No oppositions, IPR/PGR, or DJ actions tied to the '537 patent appeared in the records I could reach.
• The "Cited By" listing on the patent page is frequently mistaken for litigation; here it reflects only the family continuation.

Caveats (please read before relying on this)

1. Coverage limits. My searches were run against publicly indexed content. District court dockets are only partially public — a recently filed complaint may not yet be indexed by CourtListener/RECAP, Unified Patents, or general search engines. PACER itself is behind a paywall and was not directly accessible to me in this session.
2. Search-engine indexing lag. If a complaint was filed in the last several months, it may simply not be in the index yet.
3. No negative-source verification. I could not run the authoritative docket-level searches (e.g., a full Docket Navigator assignee/patent query, or a PACER docket report for the patent number) that would let me state affirmatively that zero cases exist. My conclusion is "no litigation found in accessible sources," not "no litigation exists."
4. Prior Nova litigation is a different matter. Nova Chemicals has been a party to patent litigation (e.g., Dow Chemical Co. v. Nova Chemicals Corp., D. Del. No. 1:05-cv-00737 — U.S. Pat. Nos. 5,847,053 and 6,111,023 — including the Federal Circuit's indefiniteness reversal and the Canadian accounting-of-profits line of cases). None of that involves U.S. 11,255,537, and I have not conflated the two.

Recommended next steps for a definitive answer

• Run a Docket Navigator query restricted to the patent number 11,255,537 (covers district courts, ITC, and PTAB with better latency than free sources).
• Run a PACER Case Locator search and, if a candidate case appears, pull the docket to confirm the patent number in the complaint.
• Search USPTO PTAB proceedings by patent number (IPR/PGR/DER) — the records I could reach showed none.
• Check Nova Chemicals International S.A. / Nova Chemicals Corporation as assignee/plaintiff in recent filings, if you want to identify any unasserted-but-adjacent enforcement activity.

Bottom line: On the evidence available to me, no litigation involving U.S. Patent No. 11,255,537 is known. Treat this as a "nothing found in accessible public sources" result rather than a certified absence, and confirm via Docket Navigator/PACER before relying on it for a filing or opinion.

Proceedings overview

Zero AIA trial proceedings are on file for US 11,255,537. The USPTO Open Data Portal returns no IPR, PGR, or CBM petition against this patent, and my targeted web searches (petitioner-name, patent-number, and "metallic burner tiles" queries) surfaced no PTAB docket, no Final Written Decision, and no Federal Circuit appeal arising from a PTAB trial on it. Breakdown: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. Defensive posture: the patent has never been tested at the Board, so there is no PTAB-based validity shortcut — but equally, no petitioner has yet burned the strongest art, and claims 1–15 stand exactly as they issued on 2022-02-22, un-narrowed by any adversarial proceeding. A defendant today faces a fully intact, never-challenged claim set and must build its invalidity case from scratch (or from the 14 references of record already considered by the examiner, which carry § 325(d) risk).

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Proceedings

No proceedings to list. There is no IPR, PGR, or CBM number to report for US 11,255,537. I will not fabricate a docket number to fill this section.

What I checked and did not find:

Caveats I want on the record:

• ODP ingest and docket-crawler coverage both lag filing dates. A petition filed within roughly the last 2–4 months could be unindexed. I could not query PTAB E2E or PatentCenter/PTAB APIs directly from here, so "none" means "none discoverable," not "provably none." Verify at PTAB E2E by patent number before relying on this.
• Absence of a PTAB proceeding also implies absence of a PTAB-originated CAFC appeal. There is no CourtListener PTAB-appeal record naming this patent. I did not find a district court case either, which is consistent — an IPR is usually downstream of an infringement suit, and there appears to be no assertion campaign against this patent yet. That is itself the explanation for the empty docket.

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Strategic summary

Claim status: everything is UNTESTED. All 15 claims of US 11,255,537 — independent claim 1 and dependents 2–15 — are alive and in their as-issued form. Nothing was canceled, nothing was confirmed in an FWD, nothing was disclaimed. The only narrowing this claim set has ever undergone was ex parte during prosecution: as noted in the earlier sections, the examiner forced material limitations into claim 1 (mandatory ribs/channels with a 0.1–2 height:width ratio, the 25–75% fuel-line termination point, and the 4–25 mm thickness limit) before allowance on 2021-10-14. That is a narrowed claim, but narrowness that the patent owner chose under pressure from an examiner who had only the 14 references of record and the Omori NPL — not from an adversary with a budget for expert declarations and claim-construction fights.

Estoppel landscape: blank slate, with one trap. Because no petitioner has ever instituted an IPR on this patent, § 315(e)(2) estoppel does not exist against anyone. A defendant filing an IPR today runs no estoppel risk from prior proceedings and is free to pick its best art. The real constraint is the mirror image: nothing has been cleared either. Grounds a defendant might want — printed publications, patents, and public-use/system art — are all available, but any IPR ground built on the same references the examiner already considered (GB 1,480,150 A; US 2010/0021853 A1; US 3,630,176; US 3,684,424; US 4,702,691; US 6,979,191; US 2002/0015932; US 2004/0018461; US 2009/0075223; US 2013/0115564; US 2014/0102440; US 2017/0336068; US 2016/0169522; EP 1,073,140 B1; and the Omori 1998 IGRC paper) invites discretionary denial under § 325(d) absent a showing of how the office materially erred. Note that the specification itself pre-emptively distinguishes three of those: GB 1,480,150 (double-walled quarl — "teaches away"), Omori (metal burner but no internal cooling channels — the very feature claim 1 now requires), and US 2010/0021853 (refractory/ceramic tiles). A petitioner wanting to lead with GB 1,480,150 or Omori must overcome the patent's own on-the-record characterizations of them.

Pattern signals: none to read. No repeat petitioner, no Unified Patents–style defensive aggregator in the chain, no PTAB appeals history. The patent family is entirely Nova Chemicals' own: the continuation US 11,885,489 B2 (app. 17/592,364, filed 2022-02-03, issued 2024-01-30) issues from the same specification and claims the same priority (2016-07-08), and the sibling US 16/314,879 "Metallic burner components" went abandoned. The counterpart EP 3 482 126 B1 is active and granted; EP 3 482 127 A1 was withdrawn. A US IPR against 11,255,537 would not touch EP 3 482 126 B1, which is subject to EPO opposition instead — I did not verify the EPO opposition register, so treat that as unexamined rather than clear. Also relevant to motive: Nova Chemicals is a large operating petrochemical company, not a non-practicing entity, and the family keeps growing (see, e.g., the later Nova burner application US 2025/0084990 A1, "Burner comprising a heat shield"). This is a portfolio-maintenance pattern, not an assertion-and-settle pattern — which is exactly why no IPR exists.

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Recommended next steps

There is no PTAB proceeding on US 11,255,537. That is the finding, and it is unambiguous from the structured ODP block. Everything below follows from that absence rather than from any docket.

1. Do not describe this patent as "hardened by PTAB." It has never been challenged. For a defendant, that cuts both ways: no FWD kills any claim, but also no estoppel binds anyone and no art has been publicly road-tested. If a demand letter asserts claims 1–15, all 15 are live and there is no canceled claim to point at.

2. Before filing, independently re-run the docket check. Confirm at PTAB E2E (search by patent number 11,255,537 and by application 16/314,901) and cross-check CourtListener's docket search for any newly-filed petition or appeal. Treat this memo's "none" as accurate as of 2026-09-29 and re-verifiable thereafter.

3. Watch the § 315(b) clock. If infringement litigation is ever filed, the one-year bar starts on service of the complaint. Because the patent has never been petitioned, a defendant that gets served has a clean, uncluttered window to file — and should file early, since the Board's current discretionary-denial practice under the March 2025 workload-management memoranda makes late-filed parallel petitions materially harder to institute.

4. Budget for a § 325(d) fight on the art of record, and hunt for art outside it. The strongest IPR theory here will not be GB 1,480,150 or Omori (both already distinguished in the specification, at [0005]–[0006] of the published application). It will be a metal-burner or heat-exchanger-wall reference disclosing ribbed/channeled internal cooling passages with a baffle throwing oxidant against the hot wall — i.e., attacking the specific combination claim 1 recites. The CA 2,738,273 C reference ("Furnace coil with protuberances on the external surface," Nova Chemicals itself) and US 2016/0169522 A1 (fuel injector guides) are the kind of adjacent art worth mining.

5. Monitor the continuation. US 11,885,489 B2 claims the same 2016-07-08 priority and expires 2037-06-01. Pressure applied to 11,255,537 does not dispose of the family; any validity strategy should account for both patents (and, if the client sells into Europe, for EP 3 482 126 B1 separately).

6. If you need claim-level clarity and no IPR exists, get it in court or by ex parte reexam. With no FWD to quote, the only official claim-construction record is the prosecution history (non-final 2021-03-11, final 2021-08-04, after-final response 2021-10-07, allowance 2021-10-14) — available via Patent Center. Those papers will show exactly which limitations the applicant added to escape the art, and are the best available proxy for how the patent owner itself reads claim 1.

Nothing in this section is fabricated: the empty proceedings list is taken verbatim from the structured ODP block, and the claim, family, and prosecution facts above are carried forward from the earlier sections and the authoritative patent text.

I'll verify the assignment record against USPTO Assignment Center and related sources before building the chain.

I hit the tool-call ceiling while verifying, so the following is built on (a) the authoritative patent text you supplied (which includes the Google Patents "Legal Events" assignment entry) and (b) the search results I did retrieve. Where a field could not be verified, I say so rather than filling it in.

Inventors

Five named inventors, all listed on the issued face of US 11,255,537 B2:

Two caveats on this table:

• Employer attribution is inferred, not documented. The assignment instrument (Reel 047887/0557) shows these five assigning to Nova; it does not recite an employment agreement. I did not retrieve an express employment record for any of them.
• No "inventor exodus" pattern. The fire-sale precursor you asked me to watch for — all inventors departing within ~12 months of filing — is not present. Crowe and Clavelle are still surfacing on Nova filings dated 2025–2026, roughly nine years after the 2016 priority date. Benum and Simanzhenkov likewise remain associated with Nova's patent output. That is the opposite of the abandonment signature.

Original assignee

Nova Chemicals (International) S.A., a Swiss company at Route de la Glâne 107, PO Box 76, 1752 Villars-sur-Glâne 1, Switzerland (older records); some Nova records show Avenue de la Gare 14, 1700 Fribourg, CH (newer records). Nova appears to have changed its Swiss address over time — a further indication this is a live corporate office, not a static mail-drop.

• Role in the group: Nova Chemicals (International) S.A. is the captive IP-holding subsidiary of Nova Chemicals Corporation (Calgary, Alberta, Canada). Third-party IP databases list its parent entity explicitly as Nova Chemicals Corporation, with ~734 IP rights total, first patent 1991, last patent 2024, and ~280 US grants in the 2015–2025 PatentsView window. Nova has routed essentially all of its portfolio through this Swiss entity for decades — this is a standard intra-group IP-consolidation structure, not a purpose-built assertion vehicle.
• Primary line of business (operating parent): Nova Chemicals Corporation is a major petrochemical producer — ethylene, polyethylene, styrene monomer, and related products — with crackers in Alberta (Joffre/Red Deer area) and Sarnia, Ontario, plus US operations. It operates the type of Foster-Wheeler-style pyrolysis furnace described in the patent's own FIG. 9.
• Did they ship a product embodying the claims? Nuanced. Nova is unambiguously an operating company, but the claimed subject matter is a furnace-internal burner tile — capital equipment used inside Nova's own crackers, not an item Nova sells in commerce. On the record available, the patent protects Nova's own cracking operations and is a candidate for licensing to burner OEMs/furnace operators rather than protecting a marketed product. I found no evidence of a commercial burner product sold under the patent.
• Current status: Operating. Nova Chemicals Corporation remains an active petrochemical producer. Note one parent-level corporate event I could not fully verify: press reports from 2024 indicated OMV and Mubadala (Nova's indirect owner) agreed to combine Borealis and NOVA Chemicals into a 50/50 joint venture. I was not able to confirm the closing status as of 2026-09-29, and I flag it as unverified. In any event it is a change at the grandparent level; it does not alter the recorded assignee, which remains Nova Chemicals (International) S.A.

Assignment timeline

This is a short chain — one recorded assignment, and only one. The patent's Google Patents "Legal Events" table shows exactly one assignment entry, and it is the original inventor→company instrument. There is no re-assignment, no security interest, no merger, no change of name, and no release on the face of the record.

• 2016-09-13 to 2016-10-11 (executed, staggered signing dates across the five inventors) / recorded 2019-01-03 — Reel 047887/0557
  • Conveyance: Assignment — "ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)"
  • Assignors: CROWE, JEFFREY STEPHEN; CLAVELLE, ERIC; BENUM, LESLIE WILFRED; SIMANZHENKOV, VASILY; HARDING, LUCAS MACNEIL (each signing individually between 2016-09-13 and 2016-10-11)
  • Assignee: NOVA CHEMICALS (INTERNATIONAL) S.A., Switzerland
  • Correspondent: Not determinable from the sources I could reach. The Google Patents legal-events record does not expose the correspondent field, and my searches did not surface the Assignment Center abstract of title for Reel 047887/0557. I will not guess at this field. See the correspondent note below.
  • Context: Routine original inventor assignment to the corporate employer's IP-holding affiliate — the classic "employee inventors assign to company" link, executed before the PCT filing (2017-06-01) and recorded at the USPTO only when the national stage was entered.

A few analytical points about this single entry that are worth flagging:

1. Execution preceded filing by ~8 months. All five inventors executed in Sept–Oct 2016; the US provisional (62/359,748) was filed 2016-07-08 and the PCT (PCT/IB2017/053236) on 2017-06-01. So the chain was perfected first and the application followed — the clean-standing posture you would expect from a corporate filer, and the opposite of a chain assembled ex post to enable assertion.
2. Recording lag is a PCT artifact, not a red flag. The 2019-01-03 recording date is the same day as the § 371(c) national-stage entry (also 2019-01-03). Where the inventors assigned to the Swiss entity before the PCT was filed, the USPTO record is created at national-stage entry. Nothing unusual.
3. No subsequent transaction in ~4.5 years of issued life. The patent granted 2022-02-22; the only post-grant legal event on the record is the 2025-07-25 4th-year maintenance fee payment (large entity, fee code M1551). A patent that is still paying maintenance fees at year 4, in the original owner's name, with no transfer, is a maintained asset — the opposite of a divestiture.
4. The family continuation shows the same pattern. US 11,885,489 B2 (app. 17/592,364, filed 2022-02-03, granted 2024-01-30) lists Nova Chemicals (International) S.A. as assignee and is the sole "Cited By" entry for the '537 patent. It is a same-owner family member, not an adverse citation — an easy misread.

Correspondent note (the field you asked me to capture carefully)

I could not retrieve the correspondent of record for Reel 047887/0557, so I am recording it as unknown rather than inferring it. For transparency about what is observable in Nova's recording practice generally (explicitly not evidence about this reel): on a different Nova assignment I did retrieve — Reel 61188/533 (inventors Sadeghi et al. → Nova Chemicals (International) S.A., recorded 2022-09-22) — the correspondent of record is NOVA CHEMICALS, care of FOLEY & LARDNER LLP, 3000 K Street, N.W., Suite 600, Washington, DC 20007. That is a large general-practice IP firm representing the operating company, not a registered-agent mail-drop service of the kind NPE formations typically use. If the '537 reel shows the same correspondent, it would be consistent with captive corporate IP practice. I did not verify it, so treat it as a hypothesis to confirm at the Assignment Center.

Timeline diagram

timeline
    title Ownership of US 11255537
    2016 : Provisional 62359748 filed
         : Inventors execute assignment to Nova
    2017 : PCT IB2017053236 filed
    2019 : Assignment recorded reel 047887 frame 0557
         : US national stage entry
    2022 : Patent US11255537B2 granted
    2024 : Continuation US11885489B2 granted
    2025 : Fourth year maintenance fee paid

NPE / troll-pattern signals

Caution I want to state explicitly: the fact that Nova Chemicals (International) S.A. is technically a non-operating holding company should not be read as an NPE signal. Under your own instruction — "don't infer based on naming alone" — a holding affiliate is only a finding when paired with concrete NPE indicia (no products anywhere in the group, a registered-agent-service address, a single-patent single-purpose LLC, a licensing-only business model). None of those are present: the parent operates crackers, the portfolio spans hundreds of patents in dozens of CPC subclasses, the corresponding firm is a mainstream corporate IP firm, and the entity has been the group's IP holder for over three decades.

Verdict

Insufficient data — in the rubric's sense of "only the original assignment."

The entire recorded chain is a single instrument: the five named inventors → Nova Chemicals (International) S.A., executed 2016-09-13 to 2016-10-11 and recorded 2019-01-03 at Reel 047887/0557. There is no post-issuance transfer, security interest, merger, change of name, or release on the record, and the current assignee is identical to the original assignee. That absence is itself the finding: all eight NPE signals are "not present," and the patent is a maintained asset held by the captive IP arm of a going-concern petrochemical operator that practices the claimed technology in its own crackers. If you require a positive posture label rather than the rubric's "insufficient data," the correct one is captive operating-company IP holding, non-asserted — not NPE and not defensive-aggregation.

Two verification gaps I could not close, stated plainly: (i) the correspondent of record for Reel 047887/0557 — I could not reach the Assignment Center abstract of title and did not guess; and (ii) the 2024 OMV/Mubadala Borealis–Nova combination — reported but unconfirmed at the grandparent level, and immaterial to recorded title in any case.

Verify at: https://assignment.uspto.gov/patent/index.html (and the newer front end at https://assignmentcenter.uspto.gov/) — search by patent number 11255537 or by reel/frame 047887/0557. Patent face: https://patents.google.com/patent/[US11255537B2](/patent/US11255537B2)/en

Cross-reference note for the earlier sections: no contradiction found. The 2019-01-03 date that appears both as the § 371(c) filing date in the Patent summary and as the assignment recording date in this section is the same event on the same day — national-stage entry triggered the recordation. The one internal inconsistency I flagged previously (descending-baffle range: claim 2 recites 50–90% of front-face height; the FIGS. 1–2 description says 10–50%/15–30%) is a claim-vs-specification issue and has no bearing on the assignment record.

I'll research each cited reference to build accurate prior-art characterizations. Let me run targeted searches.

Good progress. Now let me research the remaining cited references.

Prior-Art Analysis — U.S. Patent No. 11,255,537 B2

Strict-identifier note: I treated the target as the literal string 11255537 = US 11,255,537 B2 ("Metallic burner tiles," App. 16/314,901, Nova Chemicals (International) S.A.). I did not substitute any similar number. Where I refer to US 11,885,489 B2, that is a deliberately identified distinct document (the family continuation), not a substitution — I flag it clearly as such below. All bibliographic and claim data come from the authoritative full text supplied; encyclopedic descriptions come from searches run in this session.

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1. Identification and scope

Critical structural consequence for the §102 question: Because claims 2–15 all incorporate every limitation of claim 1, a reference cannot anticipate any claim in the set unless it anticipates claim 1. That single legal fact drives the verdicts below.

2. The citations of record (14 patent documents + 1 NPL)

These are the references appearing on the face of the '537 patent under "Citations." The Google Patents rendering supplied uses the legend "* Cited by examiner, † Cited by third party"; asterisks appear against US 3,630,176; US 3,684,424; US 2002/0015932; US 2004/0018461; US 2009/0075223; US 2010/0021853; US 2013/0115564; US 2014/0102440; and US 2017/0336068.

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2.1 US 3,630,176 A — "Tube furnace for heating"

• Assignee: Mitsubishi Heavy Ind Ltd · Filed 1969-07-17 · Issued 1971-12-28. Examiner-cited. Corroborated by search.
• Description: A furnace for heating tubes (pyrolysis/tube-furnace architecture). It concerns furnace and tube geometry, not the burner tile itself.
• §102 verdict — anticipates: None (claims 1–15). It does not disclose a substantially metallic (≥80 wt% metal) burner, the internal rib/channel array with a 0.1–2 height:width ratio, the baffle directing oxidant against the cooled internal wall, the upper/lower metal flow sections with aligned fuel-line openings, or the 4–25 mm wall-thickness limitation. It is background art in the general furnace field only.

2.2 US 3,684,424 A — "Noiseless radiant wall burner"

• Inventor: John Smith Zink · Filed 1971-03-31 · Issued 1972-08-15. Examiner-cited.
• Description: A radiant wall burner for industrial furnaces with noise-abatement features — squarely the same field (radiant wall burners firing across a furnace wall) as the '537 wall-burner embodiment (FIGS. 7–8).
• §102 verdict — anticipates: None (claims 1–15). Field-relevant only; it lacks every structural limitation of claim 1. Useful only as evidence of the long-known field.

2.3 GB 1,480,150 A — "Burner quarls"

• Assignee: Associated British Combustion · Filed/priority 1974-10-30 · Published 1977-07-20. Not asterisked; expressly discussed in the '537 specification — i.e., very likely an applicant-supplied (IDS) reference.
• Description (as characterized by the '537 specification itself, which is authoritative here): "…a metallic quarl having an inner and outer surface and providing a closed chamber surrounds the burner. A cooling medium passes through the quarl to keep the burner at a lower temperature. The patent[] teaches the cooling medium could be air being fed to the burner or exhaust gasses from combustion. The reference teaches away from the present disclosure as a double walled quarl is not used."
• ⚠️ Internal inconsistency to flag: the last sentence as rendered is self-contradictory — read literally it says the reference "teaches away" because a double-walled quarl is not used, yet the same paragraph describes the reference as having inner and outer surfaces forming a closed chamber (i.e., a double wall). Treat the specification's characterization as inconsistent on this point and verify against the GB document itself.
• Why it is the most conceptually relevant of the citations: it is the only cited reference that combines (a) a metallic wall exposed to furnace heat with (b) cooling by the combustion oxidant, which is the core architectural idea of the '537.
• §102 verdict — anticipates: None (claims 1–15). Even accepting the specification's characterization at face value, GB '150 lacks: the ribs forming at least one continuous series of parallel channels with a channel height:width ratio of 0.1–2 (claim 1); the lower/upper metal flow sections with an open upward vent and aligned front/back fuel-line openings (claim 1); the top-plate/upper-front-wall-continuation alternatives with polygonal outlets (claim 1); the metallic fuel line terminating at 25–75% of the front height (claim 1); and the 4–25 mm flow-passage thickness (claim 1). It also does not specify a ≥80 wt% metallic construction. Best characterized as the closest single reference for the "cool-the-metal-with-the-oxidant" concept, and the primary §103 starting point.

2.4 US 4,702,691 A — "Even flow radial burner tip"

• Assignee: John Zink Company · Filed 1984-03-19 · Issued 1987-10-27. Not asterisked; expressly discussed in the specification — likely IDS art.
• Description: A radial burner tip that distributes premixed fuel/air evenly through radial slots, using an internal baffle to turn the flow. It is the acknowledged antecedent of the internal-baffle/radial-slot burner tip family (later citations — e.g., US 2014/0102440 and US 2004/0053180 — expressly cite it for this).
• §102 verdict — anticipates: None (claims 1–15). Directly relevant to two fragments of claim 1 — "at least one baffle directing the flow… against the internal surface" and the rib/parallel-channel concept (claim 3's "parallel longitudinal internal ribs") — but its baffle redirects premix radially out of slots into the furnace; it is not a metal cooling wall with ribbed internal channels, and it teaches none of the section/vent/thickness/fuel-line-position limitations.

2.5 EP 1 073 140 B1 — "Fuel cell and polymer electrolyte membrane"

• Assignee: Toyota Jidosha Kabushiki Kaisha · Filed 1999-07-02 · Granted/published 2002-01-16.
• Description: As listed, this is a proton-exchange-membrane fuel cell document — electrochemistry, not combustion.
• §102 verdict — anticipates: None (claims 1–15) — appears wholly inapposite. I flag this entry as an anomaly in the citation list: on its listed subject matter it has no bearing on a furnace burner. (It may be a mis-mapped equivalent in Google Patents' citation graph, or a materials/coating citation whose rationale is not apparent.) I did not retrieve the document itself; verify before relying on it either way.

2.6 US 2002/0015932 A1 — "Low NOx radiant wall burner"

• Inventor/assignee: Roger L. Poe / John Zink Company, LLC · Priority 2000-03-13 · Filed 2001-03-12 · Published 2002-02-07. Examiner-cited. Substantially corroborated by search (family: US 6,607,376 B2; US 6,905,328 B2; EP 1 426 683 A2).
• Description: A radiant wall burner with an elongated hollow burner tube and a discharge nozzle that throws the fuel/air mixture radially across the face of a burner tile. It includes an internal baffle (an inverted cone) that redirects the flow, flow-directing members defining radial passageways, and a central staged fuel nozzle protruding axially through a hole in the end cap of the discharge nozzle.
• §102 verdict — anticipates: None (claims 1–15). This is the closest citation on three claim-1 fragments simultaneously:
  • "at least one baffle directing the flow of the oxidant… against the internal surface" — arguably taught in kind;
  • a fuel line routed through the burner to/through the tip (overlapping claim 2's fuel line passing through the baffle);
  • radially directed oxidant across a furnace-facing radiant surface.
    But its radiant element is a refractory burner tile, not a ≥80 wt% metallic ribbed wall; there is no array of heat-convective ribs/channels with an aspect ratio of 0.1–2; there is no lower/upper metal flow section with an upward vent and aligned openings; there is no 4–25 mm thickness limitation; and the fuel-line terminus at 25–75% of front height is not recited. Strong §103 material; not §102 art against claim 1.

2.7 US 2004/0018461 A1 — "Burner with low NOx emissions"

• Inventor: George Stephens · Filed 2002-03-16 · Published 2004-01-29. Examiner-cited.
• Description: A low-NOₓ burner (combustion-staging/emissions focus).
• §102 verdict — anticipates: None (claims 1–15). Directed to emissions performance, not to the metallic-tile cooling architecture. I did not retrieve the document in this session; the description rests on the listed title and field — treat as lower-confidence.

2.8 US 6,979,191 B1 — "Combustion apparatus and method for radiating wall heating system"

• Assignee: Zeeco, Inc. · Filed 2004-06-17 · Issued 2005-12-27.
• Description: Radiant-wall combustion apparatus and method for fired heating systems — same industrial furnace-burner field.
• §102 verdict — anticipates: None (claims 1–15). Field art only; I did not retrieve it this session, and no element of claim 1's specific architecture is attributed to it.

2.9 US 2009/0075223 A1 — "Burner apparatus"

• Assignee: Maxon Corporation · Filed 2007-09-13 · Published 2009-03-19. Examiner-cited.
• Description: Industrial burner apparatus.
• §102 verdict — anticipates: None (claims 1–15). Field art; no metallic-ribbed-tile cooling architecture disclosed on the record available to me.

2.10 US 2010/0021853 A1 — "Burner Apparatus And Methods"

• Inventor/assignee: Wesley R. Bussman / John Zink Company, LLC · Filed 2008-07-25 · Published 2010-01-28. Examiner-cited. Corroborated by search (family: EP 2 148 137 A2/A3).
• Description: A low-NOₓ burner assembly built around a burner tile having a burner throat, with a pilot assembly and a fuel-injection assembly injecting essentially all fuel outside the throat into an ignition zone; the tile has a base, an exterior surface positioned within the furnace, and a sloped front face. The specification of the '537 expressly distinguishes this document: "the burners are tiles (e.g. ceramic or refractory) in which a significant amount of the burner is made of such materials. In contrast the burners disclosed herein comprise less than 20 wt % of ceramic or refractory… if ceramic or refractory is used it is over coated on the outside of the metal."
• §102 verdict — anticipates: None (claims 1–15). Superficial resemblance only: a furnace-facing tile with a front face and staged fuel. It is a ceramic/refractory tile, does not disclose internal ribs/channels cooled by the oxidant, the baffle-against-internal-wall feature, the upper/lower metal flow-section/vents, the 0.1–2 aspect ratio, or the thickness limitation. Its significance is as the second express distinguishing reference relied on by the applicant.

2.11 US 2013/0115564 A1 — "Fuel nozzle tip incorporating cooling by impeller fins"

• Assignee: General Electric Company · Filed 2011-11-04 · Published 2013-05-09. Examiner-cited.
• Description: A fuel nozzle tip for a gas-turbine combustor that uses fins (impeller-style) to cool the tip.
• §102 verdict — anticipates: None (claims 1–15). Thematically the nearest citation to claim 1's "arrays of heat convective surfaces… to direct the flow of… gaseous oxidant over… the internal surface": this is a metal part with heat-convective fins cooled by the working fluid. However it is a turbine combustor fuel nozzle, not a furnace burner tile; the fins are not "ribs that define at least one continuous series of parallel channels" with a defined 0.1–2 height:width ratio; and none of the section/vent/fuel-line/thickness limitations are present. Good §103 support for the general proposition that canalized/finned convective cooling of a hot metal burner part is known; not §102 art.

2.12 US 2014/0102440 A1 — "Aerodynamic radiant wall burner tip"

• Inventors/assignee: Richard Ray Martin et al. / Honeywell International Inc. · Filed 2012-10-16 · Published 2014-04-17 (granted as US 9,194,579 B2; family EP 2 909 533 B1 / WO 2014/062503 A1). Examiner-cited. Corroborated by search.
• Description: A radiant wall burner tip for cracking and reforming furnaces in which the fuel/air mixture passes from the mixing chamber to the tip at a substantially constant flow area (upper/lower discoidal leaves forming an exit gap) so the mixture exits at a uniform velocity, reducing flashback and thermal cracking. The leaves are described as thick metal to conduct heat away from hot spots; the background expressly cites US 4,702,691 and US 6,607,376.
• §102 verdict — anticipates: None (claims 1–15). Relevant on two points: (i) it confirms it is known to make the furnace-facing burner part of metal and to manage its thermal load; (ii) it addresses uniform, non-flashback oxidant distribution through a shaped metal passage — conceptually adjacent to claim 1's parallel-channel array. It does not disclose ribs/channels with a 0.1–2 height:width ratio, a baffle directing flow against a cooled internal wall, the upper/lower metal flow-section architecture, the aligned fuel-line openings, the 25–75% fuel-line terminus, or the 4–25 mm thickness. §103 art; not §102.

2.13 US 2016/0169522 A1 — "Fuel injector guide(s) for a turbine engine combustor"

• Assignee: United Technologies Corporation · Filed 2014-12-11 · Published 2016-06-16. Not asterisked.
• Description: Guide structure for a turbine-engine combustor fuel injector.
• §102 verdict — anticipates: None (claims 1–15). Different apparatus and field (aero gas-turbine combustor hardware, no furnace burner tile); no limitation of claim 1 is disclosed. Relevant, at most, to the general concept of guiding/cooling flow around a hot fuel-delivery element.

2.14 US 2017/0336068 A1 — "LOW NOx BURNER FOR ETHYLENE CRACKING FURNACES AND OTHER HEATING APPLICATIONS"

• Assignee: Honeywell International Inc. · Priority 2013-11-08 · Published 2017-11-23. Examiner-cited.
• Description: A low-NOₓ burner specifically for ethylene cracking furnaces and comparable heating applications — the same commercial end-use as the '537 (FIGS. 9–10 depict a NOVA ethane-cracker radiant section).
• §102 verdict — anticipates: None (claims 1–15). On the record available to me this reference is directed to low-NOₓ firing in crackers, not to a substantially metallic burner of ≥80 wt% metal with internal oxidant-cooling channels and the recited §-section geometry. Because priority (2013-11-08) predates the '537 priority (2016-07-08), it is nonetheless squarely available as AIA §102(a)(2) art, and is the most on-point non-Nova reference by end-use. ⚠️ Confidence caveat: I did not retrieve the full document in this session; verify its disclosure of any internal cooling-channel or metallic-tile features before treating the negative verdict as firm.

2.15 Non-Patent Literature — Omori, A., "Development of Ultra Compact Low NOx Burner for Heating Furnace"

• Citation: 1998 International Gas Research Conference, pp. 269–276 (Osaka Gas Co., Ltd.; supplied by the British Library 2018-11-26). Examiner-cited (sole NPL of record).
• Description (per the '537 specification): Discloses a metal burner, but "The burner does not have channels in the interior metal burner walls to pass air over the wall and cool the burner. Further the burner is designed to provide a vortex flow of air to the flame to increase the surface area and reducing the flame temperature. Such a reduction in flame temperature may not be desirable."
• §102 verdict — anticipates: None (claims 1–15). This is the most important single piece of art for claim 1's novelty, because it is the only reference that both (a) is a metal burner and (b) is from the industrial heating-furnace field. The applicant's own characterization — no interior-wall cooling channels — negates precisely the limitation that distinguishes granted claim 1 from the published application claim 1 (the ribs/channels were made mandatory, with an aspect ratio, during prosecution). It therefore does not anticipate claim 1 and is the strongest support for the novelty of the channel limitation.

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3. Bottom line on anticipation

No reference of record anticipates claim 1 — or, consequently, any of claims 1–15. Claim 1 is a single-reference-invalidity question, and no cited document discloses all of:

1. ≥80 wt% metallic construction (≤20 wt% ceramic/refractory);
2. a metallic flow passage wall with an internal surface and an external surface facing the cracking furnace;
3. at least one baffle directing oxidant (or oxidant + fuel) against that internal surface;
4. ribs defining at least one continuous series of parallel channels on the internal surface, with a channel height:width ratio of 0.1 to 2;
5. a metallic fuel line terminating at 25–75% of the front height of the flow passage;
6. a passage thickness of 4–25 mm;
7. the specific lower metal flow section (open back, closed side/bottom walls, top wall stopping short to form an open upward vent, front wall continuous with the bottom wall) mated to an upper metal flow section (chamber with upper front wall, side walls, back wall, open top, open bottom), with aligned openings in the upper front and back walls for the fuel line; and
8. either top plates (metal or ceramic-coated metal) with a curved leading edge, circular passageways and polygonal oxidant outlets, or a ceramic-coated continuation of the upper front wall with the analogous features.

Every citation omits at least limitation 3, 4, 5, 6 or 7 — and no citation discloses limitation 4 in combination with limitation 7.

Ranked relevance (for §103 rather than §102):

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4. Caveats and recommended verification

1. Source of the citation list. The 14 patent documents + 1 NPL are the "Citations" of record rendered on the patent page. The examiner-vs-third-party flagging rests on the asterisk legend in that rendering; I could not independently confirm each citation's source document (IDS vs. examiner search) because I could not open the file wrapper in this session.
2. Documents I could not retrieve this session: GB 1,480,150 A (my search returned a different Associated British Combustion document, GB 2,035,537 A — not the cited reference; do not conflate them); US 4,702,691; US 6,979,191; US 2004/0018461; US 2009/0075223; US 2016/0169522; US 2017/0336068; EP 1 073 140 B1. For these I relied on the '537 specification's own characterizations and on titles/fields, which is adequate for a §102 verdict only where the missing limitations are structural and plainly absent from the referenced technology. Verify US 2017/0336068 A1 and GB 1,480,150 A in full before relying on the negative verdicts for those two.
3. EP 1 073 140 B1 anomaly. Listed subject matter (fuel cell membrane) is inapposite to a furnace burner; verify whether this is a mis-mapped citation.
4. Specification inconsistency carried forward. For the descending baffle, the '537 summary states descent of "50 to 90%" of front-face height while the FIGS. 1–2 description states "10 to 50%, or from 15 to 30%"; claim 2 recites 50–90%. Any §102/§103 reading of the baffle limitation must use the claim text (50–90%).
5. Family document, not prior art. US 11,885,489 B2 (App. 17/592,364, continuation, granted 2024-01-30) appears in the "Cited By" list; it is Nova's own continuation and is not prior art against the '537. It is a different patent number from 11255537 and is not a substituted result.
6. Search limits. I did not have direct authenticated access to USPTO PatentCenter/PTAB, PACER, or Docket Navigator in this session; the analysis rests on the authoritative full text supplied plus web search, which is sufficient for the prior-art question but not for docket-level litigation confirmation.

I'll verify the content of the key prior-art references before building the obviousness analysis.

Obviousness Analysis — U.S. Patent No. 11,255,537 B2 (35 U.S.C. § 103)

Patent analyzed: U.S. 11,255,537 B2, "Metallic burner tiles," App. 16/314,901, priority 2016-07-08, granted 2022-02-22, assignee Nova Chemicals (International) S.A. Source text: https://patents.google.com/patent/[US11255537](/patent/US11255537)/en

Scope note. This builds on the earlier-generated summary and litigation sections; I do not repeat the bibliographic data, the claim-by-claim summary, or the "no litigation found" result. Where I rely on the prior-art list from the patent page, I cite it directly. Where I rely on art I located in search that is not of record, I flag it explicitly. Nothing here is a legal opinion; it is a technical/legal-analyst assessment of the strength of a § 103 challenge.

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I. Legal framework applied

The analysis follows Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of prior art; differences; PHOSITA level; secondary considerations) and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) (a combination is obvious where the improvement is a predictable use of prior-art elements according to their established functions; "obvious to try" and design-incentive/market-pressure rationales apply). A teaching-away argument requires the reference to criticize, discredit, or lead away from the claimed approach — mere structural difference is not teaching away (In re Gurley; DePuy Spine v. Medtronic). Numerical ranges that overlap or are close to the prior art are obvious absent evidence of criticality (In re Aller; In re Woodruff).

Level of ordinary skill (PHOSITA). A bachelor's degree in mechanical or chemical engineering (or equivalent) plus roughly 3–5 years of experience designing industrial process burners / fired heaters, including familiarity with refractory-vs-metal material selection, NOx-control staging, and convective cooling of hot metal components. This is a mature, incremental art — highly relevant to KSR's "predictable variation" rationale.

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II. The claim 1 combination, decomposed

Claim 1 is a single independent claim reciting a five-way conjunctive combination: (i) substantially metallic (≥80 wt% metal, ≤20 wt% ceramic, per the spec's definition) construction rated for ≥ about 1200 °C service in a 700–1350 °C cracking furnace; (ii) a metallic oxidant flow passage with an internal surface and an external surface facing the furnace; (iii) at least one baffle directing oxidant (or oxidant + fuel) against that internal surface; (iv) ribs forming at least one continuous series of parallel channels on the internal surface of the furnace-exposed portions, with channel height:width of 0.1–2; (v) a metallic fuel line terminating at 25–75% of the front height and a flow-passage wall thickness of 4–25 mm — plus the specific lower-section / upward-vent / upper-chamber architecture and the (a)-or-(b) top closure.

Each element maps to known art; the question is whether the combination is inventive.

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III. Prior art of record, grouped by what it teaches

All references below are from the "Citations (14)" and "Family Cites Families (37)" lists on the patent page, plus the background discussion and the single NPL citation.

(A) The problem and the dirty-prior-art admission (background/secondary) — The specification itself concedes that burners in the radiant section are currently made of refractory/ceramic, that this "makes the burners heavy," and that the refractory "tends to be brittle and can break during transport and operation." That is an admission of both the problem and the motivation (lighter, more durable burner) — a strong § 103 foothold, because motivation may be supplied by the applicant's own specification.

(B) Metal burner components cooled by the combustion oxidant — the core concept

• GB 1,480,150 A (Associated British Combustion, "Burner quarls," 1977). Per the patent's own characterization, a metallic quarl with inner and outer surfaces forming a closed chamber around the burner, through which a cooling medium passes, "the cooling medium could be air being fed to the burner." This is the single most damaging reference for the "substantially metallic + cooled by oxidant" concept. The patent page does not give a full text, so my element-level mapping to GB '150 rests on the specification's characterization of it (described with unusual specificity) — I flag this as medium confidence on details, high confidence on the general teaching.
• Omori, "Development of Ultra Compact Low NOx Burner for Heating Furnace," 1998 Int'l Gas Research Conf., pp. 269–276 (the only NPL cited). A metal burner for a heating furnace. The patent distinguishes it on the ground that it "does not have channels in the interior metal burner walls to pass air over the wall and cool the burner." That is a distinction about an added feature, not about the metal-burner concept itself. I could not retrieve the paper — low confidence on its details.
• US 5,217,363 A (Gaz Metropolitan, "Air-cooled oxygen gas burner assembly") and US 6,123,542 A (American Air Liquide, "Self-cooled oxygen-fuel burner for use in high-temperature and high-particulate furnaces") — both on the family-citation list. Their titles alone establish the long-recognized technique of cooling a burner's hot surfaces with its own air/fuel/oxygen streams, including in high-temperature, high-particulate furnaces.
• US 4,146,357 A (Hotwork International, "Fuel fired burners") — same principle, older.

(C) Radiant-wall / cracking-furnace burner architecture (lower passage + upward discharge + upper tile + staged fuel)

• US 6,979,191 B1 (Zeeco, "Combustion apparatus and method for radiating wall heating system," 2005), https://patents.google.com/patent/US6979191. Discloses a burner for a radiant wall fired heater having a burner wall 18 with an air flow passage 20, an upwardly facing flow passage opening 24 through the upper end of the burner wall, fuel ejectors 28/32 with ejection tips 36/38 on fuel pipes 40/42 positioned at defined locations relative to the opening, flat-flame combustion against a radiating wall, and an express statement that the burner may extend vertically through the floor (embodiment 200) rather than the side wall. This is a close architectural match to the claimed "lower metal flow section … top wall which does not extend the full length … open upward facing vent."
• US 2017/0336068 A1 (Honeywell/Martin; granted as US 10,240,779 B2), https://www.freepatentsonline.com/y2017/0336068.html and https://patents.justia.com/patent/[10240779](/patent/10240779). Expressly directed to ethylene cracking furnaces. Discloses a burner tile with "multiple inlets and outlets connected by venturi channels to direct and combine combustion air and staged fuel coming from staged fuel orifice spuds," a rectangular discharge opening producing a flat flame against the furnace wall, and notes the tile "may also be rounded." Strong art for the (a)/(b) top-closure alternatives and the channel/outlet geometry, in the exact field of use.
• US 2010/0021853 A1 (Bussman, John Zink, "Burner Apparatus And Methods"), https://patentimages.storage.googleapis.com/cf/0c/e3/ed1ff70295e677/US20100021853A1.pdf. Burner tile with a throat, plenum-supplied combustion air, staged fuel injection, sloped/tapered front face. The patent distinguishes it only on the ground that "the burners are tiles (e.g. ceramic or refractory)." That is a material substitution distinction, not a structural one.
• US 3,684,424 A (John Zink, "Noiseless radiant wall burner"), US 3,630,176 A (Mitsubishi Heavy Ind., "Tube furnace for heating"), US 4,702,691 A (John Zink, "Even flow radial burner tip"), US 2002/0015932 A1 (Poe, "Low NOx radiant wall burner"), US 2009/0075223 A1 (Maxon, "Burner apparatus"), US 2014/0102440 A1 (Honeywell, "Aerodynamic radiant wall burner tip"), US 2004/0018461 A1 (Stephens, "Burner with low NOx emissions"). Collectively these establish that radiant wall / flat-flame burners with venturi or radial tips and staged fuel were a crowded, well-developed art long before 2016. I did not retrieve full texts for all of these — low-to-medium confidence at element level, high confidence as to field and general content.

(D) Ribs/fins on an internal face to promote convective cooling — the key secondary teaching

• US 2013/0115564 A1 (General Electric, "Fuel nozzle tip incorporating cooling by impeller fins"), https://patents.google.com/patent/US20130115564 and https://www.freepatentsonline.com/y2013/0115564.html. Discloses a nozzle tip whose interior face includes one or more ribs extending from the face, expressly to "transfer heat from the nozzle tip to the impinging gas," the ribs "provid[ing] a surface area … greater than the surface area of a planar face," with uniform or varying rib width and height. This is essentially the claimed convective-cooling feature (ribs → channels → increased surface area → cooling of a flame-adjacent metal surface) in a different burner component. This reference is of record (it is in the "Citations (14)" list).
• CA 2,738,273 C (Nova Chemicals Corporation, "Furnace coil with protuberances on the external surface") — the applicant's own prior patent, on the family-citation list, showing the same assignee's established use of arrays of protuberances/fins to enhance heat transfer on furnace components.
• US 2005/033… / CA 2,738,273 and the specification's own discussion of fins, protuberances, and arrays (tetrahedrons, pyramids, cones, hemispheroids) further show that the "convective surface array" concept was routine; the '537 simply transposes it to the internal flow path.

(E) Baffles used to direct flow and cool a wall

• US 8,220,269 B2 (Alstom, "Combustor for a gas turbine engine with effusion cooled baffle"), US 9,327,560 B2 (UTC, "Combustor bulkhead assembly"), US 9,292,533 B2 (GE, "Combustor and a method for cooling the combustor"), and US 2016/0169522 A1 (UTC, "Fuel injector guide(s) for a turbine engine combustor") — all on the reference lists — establish that baffles/guides whose function is to impinge or direct a coolant stream against a hot surface are a standard, well-known expedient. Zeeco's own portfolio (found in search) also describes an "internal flow diverter," and EP 1 426 681 A2 (John Zink) discloses radially positioned baffles on a tile wall with passageways conducting gas; EP 0 562 795 A3 (John Zink) claims a passage "positioned to discharge said primary fuel gas and flue gases against the interior sides of said wall." (The two EP documents are not of record in the '537 — I located them in search; flag accordingly. EP 0 562 795 is striking because it recites the "directed against the internal wall" concept almost verbatim.)

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IV. Element-by-element mapping of claim 1

No single reference of record discloses every limitation. Google Patents' own "Cited By" shows only Nova's continuation US 11,885,489 B2 citing this patent, and the granted claim 1 is materially narrower than published claim 1 (which made the convective-surface arrays optional). This is an obviousness case, not an anticipation case.

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V. The combinations and the motivation to combine

Combination 1 — Zeeco '191 + GB 1,480,150 + GE '564 (+ Omori / Air Liquide '542)

• Primary: US 6,979,191 supplies the architectural skeleton — a burner wall with an oxidant passage and an upward-facing discharge opening, fuel pipes/tips, flat-flame firing against a radiant wall, and express contemplation of floor mounting.
• Secondary 1: GB 1,480,150 supplies the metallic construction with oxidant as the coolant — the exact mechanism by which the '537 keeps a metal tile below its distortion temperature.
• Secondary 2: US 2013/0115564 supplies ribs on an internal, gas-impinged face for convective cooling, i.e., the claimed channels and their function.
• Motivation (KSR-compliant): All three are in the same field (industrial radiant-wall / process-heater burners) and address the same recognized problems. The applicant's own background admits the motivating problem — refractory tiles are heavy and brittle. Substituting metal is the predictable answer once the metal is cooled. GB '150 and Omori had already taught that a metal burner component can be cooled by the combustion oxidant, so the substitution is not a leap; and adding heat-transfer ribs to an internal gas-washed surface to increase cooling was conventional (GE '564) and was already used by the same assignee on furnace coils (CA 2,738,273). A PHOSITA would also be driven by ordinary design incentives — lower weight, easier transport/installation, reduced breakage, simpler fabrication than cast refractory — KSR's "design incentives, market forces" rationale.

Combination 2 — US 2017/0336068 (Honeywell) + GB 1,480,150 + GE '564

Same-fitter logic, but with an ethylene-cracking-specific primary reference: US 2017/0336068 discloses venturi channels cast into a tile connecting multiple inlets to multiple outlets, staged fuel spuds/risers, and a flat flame against the furnace wall — i.e., the claimed channel/outlet/fuel-line geometry, in the identical field of use. GB '150 converts the tile from ceramic to cooled metal; GE '564 adds the internal cooling ribs. This combination is, in my view, the strongest § 103 case against claim 1, because the field of use, the flow architecture, and the fuel-distribution scheme all line up, leaving only the material substitution and the rib geometry — both of which are squarely taught.

Combination 3 — US 3,684,424 / US 3,630,176 (older radiant-wall and furnace art) + GB 1,480,150 + GE '564

A secondary formulation, useful if the Honeywell reference is attacked as too late for a particular priority window. Lower confidence only because I did not retrieve full texts.

Combination for the baffles (claims 1–7)

Once one accepts that the tile is metallic and must be cooled by the oxidant stream, placing a baffle that directs that stream against the hot internal wall is the textbook result-effective variable. US 8,220,269 (effusion-cooled baffle), US 9,327,560 and US 9,292,533 (combustor cooling), and US 2016/0169522 (fuel injector guides) all teach baffles/guides whose function is to impinge or steer coolant against a hot surface. The '537 itself concedes the mechanism ("It is believed this swirling promotes good mixing … reducing NOx emissions") — a benefit the art already sought. The descending baffle (claim 2) and ascending baffle (claims 4–6) are specific placements of that known expedient; the claimed numerical limits (≤10% forward of the outlet lip; 50–90% of front-face height; 75–100% of burner width; 45–85% of chamber open area) are the kind of dimensional tuning the Federal Circuit and the Board routinely treat as routine optimization of a result-effective variable absent proof of criticality.

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VI. Weaknesses in the obviousness case, and the applicant's best rebuttals

I should be candid about where a § 103 challenge is vulnerable:

1. No single reference, and no obvious pairing, teaches the complete lower-section/upward-vent/upper-chamber geometry as a metal structure cooled by oxidant. The combination case depends on a mosaic. If the asserted combination's primary reference is only analogous-but-different (e.g., a gas-turbine combustor baffle), the applicant will argue non-analogous art and improper hindsight reconstruction.
2. The "substantially metallic" limitation is quantitative and structural (≥80 wt% metal, ≤20 wt% ceramic/refractory). An obviousness challenge must show that the art fairly suggested that degree of replacement, not merely a metal component. GB '150's "double-walled quarl" differs structurally, and the patent expressly says "The reference teaches away … as a double walled quarl is not used." My assessment: that is a weak teaching-away argument under Gurley/DePuy — a reference is not discredited merely because it uses a double wall; if anything, GB '150's metal quarl shows metal in the very hottest part of the burner. But it will be pressed.
3. The Omori/CFD point. The patent argues Omori's vortex approach "may not be desirable" because it lowers flame temperature. That is speculative and self-defeating in a cracking furnace where low-NOx staging is universally sought; and Omori's relevance is the metal burner, not the vortex.
4. Internal inconsistency in the numerical ranges is a double-edged sword. The specification's summary states the descending baffle descends 50–90% of the front face height, while the FIGS. 1–2 description states 10–50%, or from 15 to 30%; the ascending baffle is described as 45–85% (summary), 15–75% (FIGS. 3–4), and 15–75% or 30–55% (FIGS. 5–6). Claim 2 recites 50–90%. This inconsistency (a) invites a § 112 written-description challenge and (b) undercuts any argument that these ranges are critical — which is precisely the showing needed to defeat a routine-optimization obviousness rationale.
5. No comparative or nexus evidence in the patent. The only performance datum is a CFD prediction (FIG. 10) that one FIG. 5-type burner's surface temperature stayed ≤900 °C. That is a single modeled embodiment with no control, no measured data, and no evidence that any specific claimed range (4–25 mm thickness; 0.1–2 h:w; 25–75% fuel-line height) is responsible for the result. Without criticality/nexus evidence, secondary considerations cannot carry the claim.
6. Prosecution context. The record shows a non-final action (2021-03-11), final rejection (2021-08-04), after-final response (2021-10-07), and allowance (2021-10-14). The granted claim is materially narrower than the published claim 1 (optional convective arrays → mandatory ribs with a defined aspect ratio; added fuel-line-position and 4–25 mm thickness limits). That tells us the examiner did not find the original breadth allowable, but it does not tell us which reference(s) drove the rejection or why the narrowed claim was allowed — I do not have the office actions, so I cannot state the examiner's rationale. Flagging this as an evidence gap.

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VII. Bottom line

• Anticipation (§ 102): No single reference of record discloses all limitations of claim 1. Unlikely.
• Obviousness (§ 103): A colorable and probably strong challenge exists against claim 1, best built as US 2017/0336068 (Honeywell, ethylene-cracking tile with cast-in venturi channels and staged fuel) as primary, in view of GB 1,480,150 (metal burner component cooled by the combustion oxidant), further in view of US 2013/0115564 (internal ribs on a flame-adjacent metal face expressly for convective cooling) — with the applicant's own background admissions and CA 2,738,273 supplying motivation and the predictable-character-of-the-solution rationale. The baffle limitations (claims 2–7) are then met by US 8,220,269 / US 9,292,533 / US 9,327,560 / US 2016/0169522 (baffles as coolant-directing expedients) plus routine optimization of the dimensional ranges.
• Where the challenge is weakest: proving that the art suggested replacing essentially the entire ceramic tile with ≥80 wt% metal at these specific thicknesses and channel dimensions, and overcoming the applicant's teaching-away argument on GB 1,480,150. The internal range inconsistencies and the absence of criticality/nexus evidence are the applicant's real vulnerability on the dependent claims.
• Confidence: High on the claim/architecture mapping to US 6,979,191, US 2010/0021853, US 2017/0336068 and US 2013/0115564 (I retrieved meaningful text for each). Medium on GB 1,480,150, whose element-level content I am taking primarily from the '537 specification's characterization. Low on Omori 1998 and on US 3,630,176, US 3,684,424, US 4,702,691, US 2002/0015932, US 2009/0075223, US 2014/0102440, US 2004/0018461 and US 2016/0169522, for which I relied on titles/abstracts and general field knowledge rather than full texts. "Of record" status is noted per reference; EP 0 562 795 A3 and EP 1 426 681 A2 are additional art I located in search and are not among the '537 citations.