4:01-cv-00209
Zeeco Inc v. John Zink Co
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Zeeco, Inc. (Oklahoma)
- Defendant: John Zink Company, LLC (Delaware); Hitachi Zosen Corporation (Japan)
- Plaintiff’s Counsel: Fellers, Snider, Blankenship, Bailey & Tippens
- Case Identification: 4:01-cv-00209, N.D. Okla., 03/22/2001
- Venue Allegations: Venue is asserted based on the principal places of business for both Plaintiff Zeeco, Inc. and Defendant John Zink Company, LLC being located within the Northern District of Oklahoma.
- Core Dispute: Plaintiff seeks a declaratory judgment that its industrial burner products do not infringe Defendant's patent related to multi-stage combustion methods, and/or that the patent is invalid, following infringement accusations from Defendant.
- Technical Context: The technology concerns methods for operating industrial combustion furnaces to minimize the formation of nitrogen oxides (NOx), a regulated pollutant.
- Key Procedural History: The complaint states that patent owner Hitachi Zosen Corporation granted an exclusive license to John Zink Company, LLC, which subsequently charged Plaintiff Zeeco, Inc. with infringement of the patent-in-suit. This charge of infringement forms the basis for the court's declaratory judgment jurisdiction.
Case Timeline
| Date | Event |
|---|---|
| 1978-06-09 | '306 Patent Priority Date |
| 1985-01-29 | U.S. Patent No. 4,496,306 Issues |
| 1993-12-07 | Hitachi grants exclusive license to John Zink Company |
| 2001-03-22 | Complaint for Declaratory Judgment Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 4,496,306 - "Multi-Stage Combustion Method for Inhibiting Formation of Nitrogen Oxides," issued January 29, 1985
The Invention Explained
- Problem Addressed: The patent addresses the formation of harmful nitrogen oxides (NOx) during industrial combustion, which arise from multiple chemical pathways described as "fuel NO," "prompt NO," and "thermal NO" (’306 Patent, col. 1:16-31). Existing methods for NOx reduction were allegedly unable to effectively suppress "prompt NO" without impairing the stability of the combustion process (’306 Patent, col. 1:49-58).
- The Patented Solution: The invention proposes a multi-stage combustion method. In a first stage, primary fuel is burned with a significant excess of air (an air-to-fuel ratio of at least 1.4), creating a lower-temperature zone that inhibits NOx formation (’306 Patent, col. 5:11-14). In a second stage, secondary fuel is injected without additional air into the vicinity of the first zone. This secondary fuel is diluted by the surrounding hot, inert combustion gases and combusts using the excess oxygen from the first stage, creating a second, moderately-burning, low-NOx zone (’306 Patent, col. 4:50-68).
- Technical Importance: This method provided a targeted approach to inhibit specific NOx formation pathways, particularly prompt NO, that were difficult to control with then-conventional two-stage air supply techniques (’306 Patent, col. 1:49-58).
Key Claims at a Glance
The complaint seeks a declaration of non-infringement of the ’306 Patent generally, without specifying claims (Compl. ¶ 11). Independent claim 1 is representative of the core invention.
- Independent Claim 1:
- A method comprising injecting a primary fuel and primary air into a furnace to form a first-stage combustion zone.
- The primary air is supplied at a rate such that the ratio of actual air to stoichiometrically-required air is "at least 1.4" in the first-stage zone.
- The method further comprises injecting "only a secondary fuel in the absense of air" into the furnace near the first-stage zone.
- This secondary fuel is injected at a rate approximately equal to that required to consume the excess oxygen from the first stage.
- The method includes "diluting the secondary fuel with surrounding combustion gas prior to combusting" to form a second-stage combustion zone.
III. The Accused Instrumentality
- Product Identification: The complaint identifies the accused instrumentalities as "certain commercial/industrial oil and gas burners" manufactured and/or offered for sale by Zeeco (Compl. ¶ 9).
- Functionality and Market Context: The complaint does not provide any specific details regarding the technical operation, product models, or market position of the accused burners. It only notes that Zeeco has been making and/or offering them for sale for the six years preceding the complaint's filing date (Compl. ¶ 9). No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
The complaint, being an action for declaratory judgment of non-infringement, does not contain affirmative infringement allegations or a claim chart. It states that Defendant JZC "has charged Zeeco with infringement" and that "Zeeco denies that any of its burner products infringe the ’306 Patent" (Compl. ¶ 10). The complaint does not provide sufficient detail for analysis of specific infringement theories.
V. Key Claim Terms for Construction
The Term: "a ratio of air... is at least 1.4 in the first-stage combustion zone"
- Context and Importance: This numerical limitation is a cornerstone of the claimed invention for inhibiting prompt and thermal NOx. The dispute may turn on how and where this ratio is measured within an operating industrial burner, and whether an average or point-specific measurement is required to meet the limitation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim language refers to the ratio "in the first-stage combustion zone," which could suggest an average value across the entire defined zone rather than a specific point.
- Evidence for a Narrower Interpretation: The specification explicitly links the "at least 1.4" ratio to a sharp decrease in NOx concentration, as shown in FIG. 5, and states this is a preferable air ratio (’306 Patent, col. 4:46-49, col. 5:11-14). This may support a requirement that this specific ratio must be demonstrably achieved, not just approximated.
The Term: "injecting only a secondary fuel in the absense of air"
- Context and Importance: Practitioners may focus on this term because it is a negative limitation that distinguishes the invention from prior art methods that supplied air in multiple stages. The central question is whether "in the absense of air" requires a complete, literal absence of any entrained air or merely the lack of a dedicated, forced secondary air supply.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: An argument could be made that the term is meant to be read in the context of controlled air supplies, thereby allowing for incidental or ambient air entrainment that is not part of a formal "supply."
- Evidence for a Narrower Interpretation: The patent repeatedly contrasts its method with prior art two-stage air supply methods (’306 Patent, col. 1:35-44). The explicit use of "only a secondary fuel" and "in the absense of air" may be interpreted strictly to mean no air is introduced with the secondary fuel stream.
The Term: "diluting the secondary fuel with surrounding combustion gas prior to combusting"
- Context and Importance: This limitation defines the mechanism for the second combustion stage. The dispute will likely focus on what actions meet the definition of "diluting...prior to combusting" and what level of proof is needed to show this specific phenomenon occurs in the accused burners.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification describes this process generally, stating that inert gas "is drawn into the stream by the energy of injection, thereby diluting the injected fuel" (’306 Patent, col. 4:53-56), which could support a finding that any such mixing caused by the injection itself meets the limitation.
- Evidence for a Narrower Interpretation: The patent discloses a specific embodiment with an "aspirator cylinder" (19) designed to enhance this dilution effect (’306 Patent, FIG. 2; col. 4:10-18). This could support an argument that the term requires a more deliberate or structured form of dilution than incidental mixing.
VI. Other Allegations
This section is not applicable as the complaint is for declaratory judgment and does not contain allegations of indirect or willful infringement.
VII. Analyst’s Conclusion: Key Questions for the Case
A primary issue will be one of claim construction: can the limitation "in the absense of air" be interpreted to allow for the incidental entrainment of air common in industrial burners, or does it impose a strict requirement of no air whatsoever with the secondary fuel injection?
A central evidentiary question will be one of operational proof: assuming a construction is reached, what evidence can be presented to demonstrate that Zeeco’s accused burners, during operation, actually achieve the specific method steps of Claim 1, particularly the "air ratio of at least 1.4" in the first stage and the mechanism of "diluting...prior to combusting" in the second?
The case also presents a fundamental question of patent validity: as pleaded in the complaint (Compl. ¶ 12), can Zeeco demonstrate with clear and convincing evidence that the combination of an oxygen-rich first stage and a fuel-only second stage was anticipated or rendered obvious by prior art combustion techniques that existed before June 1978?