DCT
3:18-cv-00279
Nalco Co v. Wisconsin Public Service Corp
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Nalco Company (Delaware)
- Defendant: Wisconsin Public Service Corporation, d/b/a Weston Power Plant (Unit 3) (Wisconsin)
- Plaintiff’s Counsel: Boardman & Clark LLP; Farney Daniels PC
- Case Identification: 3:18-cv-00279, W.D. Wis., 04/18/2018
- Venue Allegations: Venue is alleged to be proper in the Western District of Wisconsin because Defendant operates the accused power plant within the district, thereby regularly transacting business and committing the alleged acts of infringement there.
- Core Dispute: Plaintiff alleges that Defendant’s process for removing mercury from emissions at its coal-fired power plant infringes a patent related to treating flue gas.
- Technical Context: The technology concerns methods for reducing toxic mercury emissions from coal-fired power plants, a significant environmental and regulatory concern for the energy industry.
- Key Procedural History: The patent-in-suit, U.S. Patent No. 6,808,692, was the subject of an Inter Partes Reexamination, which concluded with the issuance of a Reexamination Certificate on April 7, 2014, affirming the patentability of the amended claims. This history suggests the patent has already withstood a validity challenge at the USPTO, a factor that may be relevant in the litigation.
Case Timeline
| Date | Event |
|---|---|
| 2002-02-14 | ’692 Patent Priority Date |
| 2004-10-26 | ’692 Patent Issue Date |
| 2014-04-07 | ’692 Patent Inter Partes Reexamination Certificate Issued |
| 2015 | Defendant began testing the accused mercury removal process |
| 2016 | Defendant sought to permanently implement the accused process |
| 2018-04-18 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,808,692 - "Enhanced Mercury Control in Coal-Fired Power Plants"
- Patent Identification: U.S. Patent No. 6,808,692, "Enhanced Mercury Control in Coal-Fired Power Plants," issued October 26, 2004.
The Invention Explained
- Problem Addressed: The patent addresses the difficulty of removing elemental mercury from the flue gas of coal-fired power plants (Compl. ¶23). A further problem is that directly injecting molecular bromine, a chemical effective at oxidizing mercury, is impractical due to its corrosive nature (Compl. ¶25). Prior methods were either inefficient or rendered the resulting fly ash, a byproduct of combustion, unsuitable for recycling in cementitious applications (’692 Patent, col. 3:31-48).
- The Patented Solution: The invention proposes injecting a "thermolabile molecular bromine precursor" into the hot flue gas. This precursor is a stable compound (e.g., calcium bromide) that is not corrosive at ambient temperatures but decomposes under the high heat of the flue gas to release molecular bromine (’692 Patent, col. 4:4-16; Compl. ¶26). The released bromine then reacts with elemental mercury to form mercuric bromide, a compound that can be adsorbed onto alkaline particles and captured by existing pollution control equipment like electrostatic precipitators (’692 Patent, Abstract).
- Technical Importance: This method allows for the effective removal of mercury by leveraging the reactive properties of bromine without requiring the direct handling and injection of the corrosive chemical itself (Compl. ¶25-26).
Key Claims at a Glance
- The complaint asserts independent Claim 1, as amended by the Inter Partes Reexamination Certificate.
- The essential elements of the amended Claim 1 are:
- A method of treating coal combustion flue gas containing mercury, comprising:
- injecting a bromide compound that is a thermolabile molecular bromine precursor into said flue gas to effect oxidation of elemental mercury to a mercuric bromide and
- providing alkaline solid particles in said flue gas ahead of a particulate collection device, in order to adsorb at least a portion of said mercuric bromide.
- The complaint does not explicitly reserve the right to assert dependent claims, but infringement allegations focus exclusively on Claim 1.
III. The Accused Instrumentality
Product Identification
- The accused instrumentality is the "Chem-Mod Process" used by Defendant at its Weston Power Plant to produce "Refined Coal" for mercury emission control (Compl. ¶72, 74).
Functionality and Market Context
- The Chem-Mod Process involves treating conventional coal with a "Chem-Mod Solution" before the coal is pulverized and injected into the plant's furnace (Compl. ¶74, 78). This solution contains two key additives: "MerSorb," which is a mixture of calcium bromide and water, and "S-Sorb," a dry, alkaline powder composite (Compl. ¶75-77).
- When the treated "Refined Coal" is combusted, the heat allegedly causes the MerSorb (calcium bromide) to decompose and release bromine, which oxidizes elemental mercury in the flue gas. The resulting mercuric bromide is then allegedly adsorbed by the alkaline particles from the S-Sorb and captured by the plant's existing emission control systems (Compl. ¶79). The complaint alleges Defendant adopted this process to reduce emissions and obtain tax credits (Compl. ¶82).
IV. Analysis of Infringement Allegations
The complaint extensively argues for its interpretation of key claim terms, anticipating potential non-infringement arguments. It alleges that Defendant's use of the Chem-Mod process literally infringes at least Claim 1 of the ’692 Patent and, in the alternative, infringes under the doctrine of equivalents (Compl. ¶97, 117). The complaint references Figure 2 of the Madden patent (an exhibit) to support its interpretation of "injecting," describing it as showing that introducing an additive mixed with fuel into a furnace is considered "injecting... into the flue gas" (Compl. ¶65-66).
’692 Patent Infringement Allegations
| Claim Element (from Independent Claim 1, as amended) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A method of treating coal combustion flue gas containing mercury... | Defendant’s own regulatory filings for the Chem-Mod process allegedly describe it as a method for treating flue gas to reduce mercury pollutants. | ¶88 | col. 9:41-42 |
| injecting a bromide compound that is a thermolabile molecular bromine precursor into said flue gas | The Chem-Mod Process adds MerSorb (calcium bromide, a thermolabile bromine precursor) to coal, and this mixture is injected into the furnace, which allegedly contains "flue gas" upon combustion. | ¶89, 91-92 | col. 9:46-50 |
| to effect oxidation of elemental mercury to a mercuric bromide | At the high temperatures in the furnace, the MerSorb allegedly decomposes to release bromine, which reacts with and oxidizes elemental mercury to form mercuric bromide. | ¶79, 105 | col. 9:48-50 |
| and providing alkaline solid particles in said flue gas ahead of a particulate collection device | The process adds S-Sorb, an alkaline material, to the coal before it is injected into the furnace. The furnace is located ahead of the plant’s particulate collection devices. | ¶106-108 | col. 9:50-53 |
| in order to adsorb at least a portion of said mercuric bromide | The mercuric bromide allegedly adsorbs onto the alkaline particles from S-Sorb, which are then captured by downstream filtering equipment. | ¶109-110 | col. 9:53-54 |
- Identified Points of Contention:
- Scope Questions: The complaint dedicates significant space (Compl. ¶30-69) to pre-emptively arguing the construction of "flue gas" and "injecting," suggesting these will be the central disputes.
- Does the term "flue gas" refer only to the post-combustion gas stream, or does it also encompass the environment within the combustion zone itself? The infringement allegation depends on the latter, as the precursor is introduced with the coal.
- Does the limitation "injecting a bromide compound... into said flue gas" require introducing the precursor as a separate stream, or can it be construed to cover a process where the precursor is pre-mixed with the fuel source before being introduced into the furnace?
- Technical Questions: What evidence will be presented to establish that the "Refined Coal," when combusted, releases bromine that then interacts with "flue gas" in the manner required by the claim, as opposed to reacting with coal components or other substances during the combustion process itself?
- Scope Questions: The complaint dedicates significant space (Compl. ¶30-69) to pre-emptively arguing the construction of "flue gas" and "injecting," suggesting these will be the central disputes.
V. Key Claim Terms for Construction
The Term: "flue gas"
- Context and Importance: The definition of this term is critical. The accused process introduces the bromine precursor with the coal into the combustion zone. If "flue gas" is construed to mean only the gas stream after combustion is complete, Defendant may argue it does not inject anything "into" the flue gas. Practitioners may focus on this term because the entire infringement theory rests on a broad definition that includes the combustion zone.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The complaint argues that the patent's statement that the method is "preferably" performed after the "superheater" section implies that treatment elsewhere, including in the combustion zone, is contemplated (’692 Patent, col. 4:1-3; Compl. ¶43).
- Evidence for a Narrower Interpretation: The common technical understanding of "flue gas" is the gaseous product resulting from combustion, which could support an argument that it does not exist until after the primary combustion reaction is complete.
The Term: "injecting... into said flue gas"
- Context and Importance: This term's construction is central to whether pre-mixing an additive with fuel constitutes infringement. Defendant’s process does not appear to involve a separate injection of the bromine precursor into a gas stream; rather, the precursor is a component of the fuel itself.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The complaint heavily relies on extrinsic evidence (other patents, expert declarations) to argue that a person of ordinary skill in the art would understand "injecting" to include co-injection with fuel (Compl. ¶59-69). The patent itself does not explicitly define the term or provide an embodiment of co-injection with fuel.
- Evidence for a Narrower Interpretation: The claim language recites two distinct steps: treating "flue gas" by "injecting" a compound into it. This structure could support an argument that the flue gas must pre-exist the act of injection, favoring a narrower construction that requires a separate injection stream into a downstream flue.
VI. Other Allegations
- Willful Infringement: The complaint alleges that Defendant’s infringement has been "willful and deliberate, with full knowledge of Nalco's rights in the '692 Patent" (Compl. ¶118). The pleading does not specify the factual basis for this alleged knowledge (e.g., pre-suit notice), stating it is based on "information and belief."
VII. Analyst’s Conclusion: Key Questions for the Case
The resolution of this case appears to hinge almost entirely on claim construction, a point underscored by the plaintiff's extensive pre-emptive arguments in the complaint. The central questions for the court will be:
- A core issue will be one of temporal and spatial scope: Can the term "flue gas" be construed to exist simultaneously with the act of combustion, such that introducing an additive with the fuel constitutes injection "into" the flue gas, or is it strictly a post-combustion product?
- A related key issue will be one of process definition: Does the claim term "injecting", in the context of the patent, encompass the act of pre-mixing a chemical agent with solid fuel before combustion, or does it require the introduction of a separate fluid stream into an existing gaseous environment?