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Process Commercialization: The 2017 Kirkpatrick Chemical Engineering Achievement Award

By Edited by Gerald Ondrey |

awardThe path to commercialization can be long and arduous, which means the engineers and chemists taking the path must have a good deal of patience, dedication and fortitude. To honor the efforts of those chemical engineers and their companies that have sucessfully commercialized a new process for the first time, Chemical Engineering magazine has been bestowing its Kirkpatrick Chemical Engineering Achievement Award since 1933.

The aim of the Award is to recognize and honor the most noteworthy chemical-engineering technology commercialized anywhere in the world during the two years prior to a given award year. The results for the 2017 Kirkpatrick Chemical Engineering Achievement Award are as follows:

Winning Award

  • CB&I (The Woodlands, Texas; www.cbi.com) and Albemarle Corp. (Charlotte, N.C.; www.albemarle.com), for the AlkyClean process — the world’s first solid catalyst alkylation process

Honor Awards

  • Chemetry Corp. (Moss Landing, Calif.; www.chemetrycorp.com): eShuttle technology
  • The Dow Chemical Company (Midland, Mich.; www.dow.com): Canvera polyolefin dispersion technology
  • The Dow Chemical Company: Paraloid Edge Technology
  • Microvi Biotech Inc. (Union City, Calif.; www.microvi.com): Denitrovi biocatalytic nitrate removal
  • Praxair, Inc. (Danbury, Conn.; www.praxair.com): Oxygen-fired combustion process with thermochemical regenerators

These companies join the long and distinguished roster of past winners, which includes such milestones as Lucite International for its Alpha process for making methyl methacrylate (2009); Cargill Dow LLC for its production of thermoplastic resin from corn (2003); Monsanto hollow-fiber membranes for gas separation (1981); Union Carbide low-pressure low-density polyethylene (1979); M.W. Kellogg single-train ammonia plants (1967); Linde zeolite adsorbents (1961); the U.S. synthetic rubber industry (1943); and Standard Oil Development Co. aviation fuels (1939). A complete list of all past winners can be found online at: www.chemengonline.com/kirkpatrick-award.

Although the staff of Chemical Engineering organizes and bestows the award, neither the editors nor others associated with the magazine play any role in the selection or judging of the winner. Instead, the winner is selected by a Board of Judges (BOJ) comprised of current chairs of chemical engineering departments at accredited U.S. and E.U. universities. The members of the BOJ are, in turn, selected by over a hundred chemical engineering department chairs of accredited U.S. and E.U. universities. It is this unbiased selection process, combined with a more than 84-year tradition that makes the Kirkpatrick Award one of the most prestigious honors that a chemical process industries (CPI) company can receive.

This article presents more details about the process technologies honored in 2017.


2017 Board of Judges

  • Lorenz T. Biegler, Carnegie Mellon University
  • Richard B. Dickinson, University of Florida
  • Mario Richard Eden, Auburn University
  • Chris Hardacre, The University of Manchester
  • Geoffrey L. Price, University of Tulsa
  • Nilay Shah, Imperial College London
  • Michael S. Wong, Rice University


 

Winning Achievement

CB&I and Albemarle:

AlkyClean® alkylation technology

AlkyClean gasoline alkylation technology is an advanced solid-catalyst alkylation process for the production of motor fuel alkylate. With AlkyClean technology, light olefins from typical petroleum-refinery sources, such as fluid catalytic cracking (FCC) units react with isoparaffins to produce alkylate. Of primary interest is the reaction of butylenes with isobutane to form high-octane trimethylpentane isomers.

General description. The novelty and success of the AlkyClean technology is the ability of petroleum refiners to completely eliminate the use of liquid acids (H2SO4 or HF) and their associated hazards and operational complexity. Solid catalyst is used in multiple fixed-bed reactors, operating in cyclical mode, to continuously produce high-quality alkylate, while those off-line are being regenerated. The chemical engineering challenge was to create the ability to fully recover catalyst activity over multiple cycles. Breakthroughs made with the catalyst formulation and the regeneration process make this possible.

For decades, scientists have been trying to replace liquid acid technologies with a safer and more environmentally friendly solid catalyst technology. HF, in particular, is extremely toxic and, upon release, forms clouds that can be lethal for miles. Prior approaches with solid catalyst failed because of poor product selectivity or inability to fully recover catalyst activity. In some cases, these catalysts also used leachable corrosive components that could migrate into the product.

CB&I and Albemarle offer a catalyst/process combination that eliminates these drawbacks entirely. Furthermore, neither acid-soluble oils, nor spent acids, are produced and there is no need for product post-treatment of any kind. Without these waste streams and the need for post-treatment, corrosion is virtually eliminated in the downstream fractionation section. With the use of particulate catalyst, liquid acids are no longer required.

Albemarle’s AlkyStar® catalyst has been designed for exclusive use with the AlkyClean process. It uses a zeolite that is well proven in the industry, along with a low concentration of a noble metal component. The strength, type and number of the zeolite’s acid sites on the catalyst are optimized to enhance hydrogen transfer reactions over multiple alkylation reactions.

The process. The AlkyClean process consists of four main sections (Figure 1): reaction, catalyst regeneration, product distillation and an optional feedstock pretreatment section (depending on the quality of the olefin feed). Olefin feed, together with isobutane recycle, enters the reaction section. The reactor operates in liquid phase in the temperature range of 50 to 90°C and a pressure of 20–30 barg. These operating conditions are quite mild and typical of other processing units within a refinery. In the AlkyClean process, multiple reactors are used to allow for continuous alkylate production, as individual reactors cycle between online alkylation and low-temperature regeneration.

Figure 1.  The four main sections of the AlkyClean process are shown here

Figure 1. The four main sections of the AlkyClean process are shown here

During regeneration, olefin addition is stopped and H2 added to achieve a low concentration of H2 in the reactor, while maintaining liquid-phase alkylation reaction conditions. This allows for a seamless switchover between alkylation and regeneration, while minimizing energy consumption. During low-temperature regeneration, H2 cleans the catalyst, thereby delaying the buildup of longer-chain hydrocarbons.

Over time, however, there is still a gradual loss of catalyst activity, which is recovered by taking the reactor off line for a high-temperature regeneration step, which fully restores the catalyst activity. With this innovative continuous regeneration scheme, the performance is maintained without any disturbances to plant operation. The swing reactor, coupled with long catalyst life, allows the refiner to tailor turnarounds in line with FCC requirements.

Development and commercialization. The AlkyClean process and catalyst were developed at Albemarle’s research center in Amsterdam with more than 60,000 h of operation on a small bench-scale pilot unit. In addition, a 10-bbl/d demonstration unit was operated in Porvoo, Finland on an actual refinery butylene stream for over two years. The data collected were used by CB&I to finalize the design basis for the technology and to successfully scale up to a commercial-sized plant.

The first commercial AlkyClean unit successfully started up in August, 2015, in Zibo, China by Shandong Wonfull Petrochemical Group Co. (Figure 2).

process commercialization

Figure 2. The two photos show the first commercial plant to use the AlkyClean process. This 2,700-bbl/d unit started up in 2015 in Zibo, China and has now been operating safely and successfully for over two years, producing an alkylate product at a quality on par with existing technologies, and meeting or exceeding all process guarantees. The RON (octane) value of the alkylate product is typically in the 95 to 97 range

Honor Achievements

Chemetry: eShuttle™ technology

Chemetry’s eShuttle technology provides a breakthrough in the synthesis of chlorinated organic compounds by eliminating chlorine generation from the traditional chlor-alkali process. The first commercial application of the technology is the chlorine-free synthesis of ethylene dichloride (EDC), an intermediate in the production of polyvinyl chloride (PVC). The next application for this platform, a process producing propylene oxide, is now in development.

General description. eShuttle replaces the chlor-alkali and direct-chlorination processes with a single, integrated process (Figure 3) that uses a circulating stream of aqueous copper chloride to transfer chloride ions from NaCl to ethylene. Specifically, the process leverages the redox states of copper to convert CuCl to CuCl2 at the anode of the electrochemical cell. The CuCl2 then reacts with ethylene to form EDC, regenerating the CuCl, which is returned to the cell. Like the processes it replaces, the eShuttle technology uses the same feedstocks — NaCl brine, water and ethylene — to produce the same products — EDC, caustic, and H2 — but at much lower energy and operating cost and without Cl2 gas generation.

Figure 3.  The electrochemical cell of eShuttle is shown here

Figure 3. The electrochemical cell of eShuttle is shown here

The novelty of the technology lies in the elimination of Cl2 as a chemical intermediate. By replacing the standard chlor-alkali anode reaction, 2Cl → Cl2 + 2e, with the copper oxidation reaction, Cu+ → Cu2+ + e, the theoretical anodic voltage is decreased by 0.6V. This voltage translates directly to electrical savings of 25% and significantly lower operating costs. Moreover, the elimination of Cl2 as an intermediate reduces the safety risk and costs associated with Cl2 compression, storage and transportation.

Cell technology. From a chemical engineering perspective, one of the most important advances in the development of the new cell is the anode structure. Unlike traditional chlor-alkali cells, which have gas-generating reactions at both the cathode (H2) and anode (Cl2), the eShuttle cell does not generate gas at the anode. This provides two significant benefits to the cell design. First, the anode half-cell reaction is strictly an electron-transfer reaction; it is non-catalytic. As a result, catalytic coatings are not needed to assist with any reaction step, including gas desorption. Secondly, the anode compartment itself can be much thinner because there are no issues with two-phase flow. This is important because a three-compartment cell would typically lead to a much thicker cell. However, the thinner anode compartment actually allows for a cell that is about half the thickness of the state-of-the-art chlor-alkali cell. This allows the eShuttle to be readily retrofittable to existing electrolyzer floor space.

Although a single-phase anolyte does have benefits, it also presents two key challenges: mass transfer and pressure balancing. The gas generation in the chlor-alkali anode provides effective mass transfer through convective flows. Without gas generation, a thick, stagnant boundary layer may form at the anode surface. Formation of such a boundary layer can lead to localized depletion of Cu+1, and diffusion-limited cell performance. To address these challenges, Chemetry utilized 3-D computational fluid dynamics (CFD) models to simulate various anode design concepts. The final design incorporates optimized electrodes with a bridged, corrugated mesh that acts as an inline static mixer for the flow. The design is optimized for high mass transfer and low pressure drop, and features an anion exchange membrane that has low resistance for Cl transport and yet blocks the migration of copper species, and a design that minimizes electrical losses and cell thickness.

Development and commercialization.The eShuttle process was transferred from laboratory to commercial demonstration scale at Chemetry’s facility in Moss Landing, Calif. with integrated operation beginning in 2014 and extensive production campaigns in 2015.

To bring the process to commercial scale, Chemetry has developed partnerships with a number of key suppliers, including FuMA-Tech for the supply of membranes, Covestro for the supply of oxygen-depolarized cathodes, and a specialized laser welding company for cell fabrication. In 2016, TechnipFMC obtained rights to license eShuttle for EDC. Recently, a confidential development partner has signed a term sheet to install a demonstration-scale plant at one of its existing production sites.

The Dow Chemical Company: Canvera™ polyolefin dispersions

Steel and aluminum containers for food and beverages are, and have been coated on the inside to protect against corrosion caused by the contents, and also to protect the contents from contact with the metal, ensuring preservation, flavor, quality and consumer food safety. Today, most interior coatings utilize epoxy, which contains bisphenol-A (BPA), which is a material of concern to some consumers.

Canvera polyolefin dispersions are made by a new manufacturing process, allowing food-and-beverage brand owners to address growing consumer interest in avoiding packaging that contains epoxy and BPA coating systems. Canvera polyolefin dispersions replace reactive, thermoset materials with high-molecular-weight thermoplastic polyolefin materials.

Polyethylene (PE) used in packaging avoids the reactive monomer issue present in thermosets. PE is made catalytically and the ethylene monomer is very volatile. The key process advance overcomes the difficulty of applying a polymerized solid to the inside of a can by forming a low-viscosity emulsion. The emulsion is easily applied and forms a uniform layer as it dries. Heating forms a defect-free coating of inert polymer.

Process description and development. A new process for making aqueous dispersions from bulk polyethylene now makes polyethylene coatings possible. Dow’s proprietary Bluewave™ mechanical-dispersion process (Figure 4) transforms polyolefins from large polymer pellets into aqueous dispersions suitable for use as liquid coatings.

Figure 4.  Dow’s Bluewave mechanical-dispersion process transforms polyolefins from large polymer pellets into aqueous dispersions suitable for use as liquid coatings

Figure 4. Dow’s Bluewave mechanical-dispersion process transforms polyolefins from large polymer pellets into aqueous dispersions suitable for use as liquid coatings

The engineering challenge was to develop and implement technology enabling the delivery of high-molecular-weight, semi-crystalline polyolefins in a low-viscosity liquid form. The inherent properties of polyolefins make this challenge formidable since they are not soluble in common industrial solvents. Utilizing Dow’s Bluewave mechanical-dispersion process, polyolefin pellets are transformed into aqueous polyolefin dispersions with individual polymer particles of approximately 1µm in diameter suspended in water. This material transformation is achieved through patented twin-screw extruder barrel configuration, element design and sequencing, as well as careful control of pressure and temperatures to simultaneously melt, disperse via a high-internal-phase emulsion (HIPE), and stabilize the polyolefins as a dispersion. The performance of these dispersions was optimized through careful composition and process experimentation, extensive high-throughput coating formulation work, and mapping of application spray and oven conditions to yield the final coating systems.

During scaleup, extensive process studies were required to move from research scale (25-mm extruder) to full production scale (58–97-mm extruders). Extruder operating conditions, including critical parameters, such as multiple temperature zones, injection water temperature, polymeric dispersant and neutralization strategy and subsequent dilution water, temperature and flows had to be optimized through sequential design-of-experimentation (DoE) methodology. In addition, extensive research was conducted on the screw element design, balancing the needed shear regime to generate the small particle size contrasted against the shear-induced temperature generation considerations. Optimized screw element layout design was critical to achieving the target particle size of the polymers. The particle size, in turn, is critical to application characteristics of the coating, affecting distribution and film weight of the coating in the can under a high-speed can manufacturing process.

The Bluewave mechanical dispersion is only part of the story. Specifically designed polyolefin resins were required and the formulation chemistry required optimization to make a superior can coating. A typical Canvera dispersion contains 3–5 polymers designed to achieve the correct balance of properties, including metal adhesion, chemical resistance, melting temperature, hardness and toughness, while ensuring dispersion stability.

Commercialization.Commercialized in December 2015, and ramped to full commercial production in 2016, Canvera dispersions are used to coat the inside of millions of metal containers in U.S. and European marketplaces, providing consumers with suitable alternatives to the incumbent epoxy-based system.

The Dow Chemical Company: Paraloid™ Edge technology

Urethane coating resins have many desirable and a few undesirable attributes. Paraloid Edge urethane coatings are made using a completely new process that is isocyanate and formaldehyde free. Paraloid Edge resins and cross-linkers retain and add to the desirable, while eliminating some of the most undesirable attributes of urethane resins. It is a superior, not a compromised, product. Paraloid Edge resins:

  • are isocyanate and formaldehyde free for safety
  • provide a very fast dry time for improved productivity
  • have a long pot life, reducing waste
  • cure at room temperature for convenience
  • are durable and weatherable
  • are polyurethanes made with a better process

The final coating forms by reacting a polycarbamate and a di-aldehyde, forming a polyurethane without isocyanates. A complete redesign of the process for urethane production gives a product that is superior to conventional urethanes (Figure 5).

Figure 5.  A complete redesign of the process for urethane production gives a product that is superior to conventional urethanes

Figure 5. A complete redesign of the process for urethane production gives a product that is superior to conventional urethanes

Dow Coating Materials developed processes for cost-effective production of a two-part, reactive urethane coating system using polycarbamates and di-aldehydes, replacing the isocyanates and polyols used in conventional urethanes. Typical polycarbamate production uses highly toxic methyl carbamate. Dow developed processes based on urea, overcoming process challenges that hampered development of urea-based routes in the past.

Polyols polymer and polymerization design. Paraloid Edge is designed to meet or exceed the specifications met by conventional urethane coatings. These properties (solution viscosity, color, clarity, hardness, dry-time, UV resistance, chemical resistance) are essential for the successful application of the paint and the final performance of the final cured coating material. The final properties of the polymeric material are dictated by the design of its molecular structure, extensive material science and engineering R&D established structural-property relationships used to design the essential details of the polymer microstructure.

Once the polymer composition was determined, the design of the polymerization reactor system and the process conditions followed. Among the multiple engineering challenges were the following:

  • Reactor temperature control due to the high heat of polymerization
  • Control of molecular weight and its distribution
  • Control of comonomer composition distribution

Extensive kinetics and process research and modeling was carried out to develop and optimize processes for the production of acrylic polyols.

Polycarbamates design and reaction. Polycarbamates are formed through the functionalization of reactions of polyols with urea. The carbamates are the cross-link point across the polymer chain, and therefore, the extent of the functionalization reaction essentially dictates the degree of crosslinking of the final coating material. Extensive material science and engineering R&D was carried out to determine the optimum degree of functionalization for each prototype. The optimum extent of reaction was proved to be vastly different, depending on the final application, for different prototypes, and it varied from 50% to 80% of the starting polyol hydroxyl functionality, across different prototypes.

Using urea in the carbamylation reaction introduces a number of process challenges, such as byproduct formation, low urea solubility in reaction media, and formation of hazy, highly colored product. The process developed by Dow overcomes these challenges, resulting in a very high urea conversion and producing a very clear and low-color acrylic carbamate.

Cross-linker. The di-aldehyde, cyclohexanedicarboxaldehyde (CHDA), is produced through hydroformylation of tetrahydrobenzaldehyde (THBA) with CO and H2 in the presence of a rhodium catalyst. Two continuously stirred tank reactors (CSTRs) under pressure, in the absence of O2, achieve >99% conversion. Process conditions, the complex operation of two CSTRs and multiple post-reaction steps, were optimized through extensive experimental and process modeling work. A proprietary process called Non-Aqueous Phase Separation, which was first commercially implemented in this technology, recovers the rhodium catalyst for reuse.

This process was first commercialized in March 2015 in the U.S.

Microvi Biotech Inc.: Denitrovi™ biocatalytic nitrate removal

Nitrate is one of the foremost drinking water challenges today, contaminating groundwater around the world and posing threats to human health. For the past ten years, Microvi has been working to provide a new solution to overcome the challenges of nitrate contamination. This technology, called Denitrovi, is based on Microvi’s MicroNiche Engineering platform, where novel materials science is used to control how microorganisms behave and perform in industrial bioprocesses.

Conventional nitrate removal. Nitrate is highly mobile in groundwater and does not adsorb, volatilize or naturally degrade in the majority of groundwater aquifers. Nitrate-contaminated groundwater can be treated through two different approaches: 1) separation of nitrate (via anion exchange, reverse osmosis or nanofiltration) or 2) degradation of nitrate. The first approach is costly, energy-intensive and produces concentrated waste streams that require secondary treatment. The second approach — biological nitrate degradation (or denitrification) — is an ancient and energetically favorable microbial metabolic process that reduces nitrate to N 2. The denitrification reaction occurs under anoxic conditions, coupling nitrate (electron acceptor) to an electron donor, such as carbon or hydrogen. Nitrate degradation is an attractive alternative to separation since it does not require high energy or inherently generate concentrated waste streams. However, conventional biological denitrification technology is characterized by major disadvantages, including organism washout, slow reaction rates and sludge production.

In conventional biological denitrification treatment, the paradigm has remained the same for more than 100 years: repeatedly grow and remove the microorganisms that remove the nutrients. This fundamental paradigm imposes limitations in five key areas that govern the size and cost of biological treatment systems in general: substrate diffusion, mixing, settling, solids production and carbon consumption. Each factor contributes to low organism densities, significant sludge production and ultimately large footprints and volumes required proportionally to high hydraulic residence times (HRTs).

Denitrovi technology. Microvi is the first company to deconstruct the dominant paradigm in biological water treatment. The company’s founder, Fatemeth Shirazi invented a new approach to microenvironmental engineering called MicroNiche Engineering. The MicroNiche Engineering platform is a combinatorial materials-science platform that can take nearly any kind of microorganism and using an in silico model, parameterize microorganism-material compositions with functionalities unachieveable using conventional techniques. Whereas conventional biological treatment technologies use various techniques to simply grow and retain biomass, MicroNiche Engineering utilizes functional cellular microenvironments that help control phenotypes, behaviors and self-organization. Denitrovi uses specially-targeted, high-performance natural microorganisms that are completely incorporated at very high density within material composites. These composites provide a protective microenvironment with unique geometry and physiochemical properties.

The Denitrovi technology provides a paradigm shift for translating natural microbial fitness-enhancing behaviors into an industrially relevant format. The synthetic Denitrovi biocatalysts, as a highly hydrated, hydrophillic polymer complex, mimics key fitness advantages found in natural microorganism communities while maintaining a controlled system over extended periods of time.

Using Denitrovi, nitrate-contaminated water enters a reactor and the nitrate is degraded by microorganisms housed in biocatalysts and converted into N2. The key chemical engineering feat achieved by the technology is that it generates no sludge.

Commercialization. In January 2017, Microvi and Sunny Slope Water Company of Pasadena, Calif. launched a new, 200-million-gal/yr facility that uses Denitrovi to remove nitrate from groundwater. At Sunny Slope, the technology reduces nitrate from ~40 mg/L to <5 mg/L in a matter of minutes of contact time, while virtually eliminating the secondary waste stream that would otherwise be associated with a biological technology. Most importantly, the technology was found to be 50% of the cost of existing treatment technologies, such as ion-exchange.

Figure 6.  The Denitrovi process (lower) requires fewer steps than conventional biological denitrification processes (upper), without generating sludge

Figure 6. The Denitrovi process (lower) requires fewer steps than conventional biological denitrification processes (upper), without generating sludge

Praxair: Oxygen-fired combustion with thermochemical regenerators

Currently, most high-temperature furnaces still operate at net energy efficiencies below 50%, despite the many advancements made in heat-recovery technology for industrial process furnaces. The main heat loss is the sensible heat in the fluegas, due to the large fluegas volume of fuel-air combustion.

Increasing efficiencies. Oxy-fuel combustion eliminates N 2 that would be present using combustion air, and hence substantially reduces the fluegas volume and the sensible heat loss. For example, oxy-fuel firing reduces fuel consumption by about 30% for steel reheat furnaces equipped with metallic recuperators to preheat air. For glass melting, in furnaces equipped with efficient regenerators for waste-heat recovery, up to 10 to 15% fuel savings are achieved by oxy-fuel conversion and NOx emissions are reduced by as much as 80%.

In the U.S., about 30% of container glass furnaces have been converted to the “best available technology” for NOx control. However, less than 10% of the world’s glass is produced using oxy-fuel combustion.

Metallic recuperators were recently developed to preheat both oxygen and fuel for recovering waste heat from oxy-fuel fired glass furnaces. Air is heated first by hot fluegas in a radiant-type recuperator and then the preheated air is used as the heat-transfer medium to heat both fuel and O2 in separate recuperators. The indirect heating design addresses corrosion and fouling concerns for the heat exchangers for O2 and fuel. The maximum O2 preheating temperature is limited to about 600°C due to material compatibility with high-temperature O2. The maximum natural gas preheating temperature is limited to about 450°C due to cracking of hydrocarbons and soot buildup. The maximum heat recovery efficiency is only about 24% of the sensible heat in the fluegas. Fuel savings achieved with this heat-recovery system are reported to be 8 to 9%. To date, there are only a few commercial systems installed due to the high capital cost of the system and its relatively low heat recovery efficiency.

Optimelt™ TCR. Praxair has developed a novel heat-recovery technology, the Optimelt Thermochemical Regenerator (TCR) that maximizes waste heat recovery by recovering waste heat in fluegas from oxy-fuel fired furnaces and returning the energy to the furnace as hot synthesis gas (syngas). The Optimelt TCR process (Figure 7) is the first known commercial oxy-fuel fired glass melting process utilizing endothermic chemical reactions for waste heat recovery.

Figure 7.  The overall concept for the Optimelt thermochemical regenerator is shown here

Figure 7. The overall concept for the Optimelt thermochemical regenerator is shown here

During the heating cycle, waste heat from the glass furnace fluegas (about 1,540°C) is collected and stored in a regenerator. During the endothermic reforming cycle, this stored heat is used to heat and reform a mixture of natural gas and recycled fluegas to produce syngas at about 1,260°C. No catalysts are required for the reforming reactions due to the high regenerator temperature. By using two regenerators, they can alternate between heating and reforming cycles, so that one is always storing heat while the other is supplying preheated syngas to the furnace. Water vapor and CO2 in the oxy-fuel combustion fluegas are synergistically utilized as reactants so the steam generation normally required for reforming reactions is eliminated. The syngas created from the reforming of natural gas contains hydrogen, carbon monoxide and a significant fraction of carbon (soot) particles. Soot particles are advantageous in the combustion process to produce a highly luminous flame for efficient heat transfer.

The Optimelt regenerators are similar in design to those used for conventional air heating but only require one third of the checker volume due to the reduced fluegas volume from oxy-fuel combustion, making retrofit an economically attractive option, especially when space is limited.

Commercialization. After verifying the technical feasibility, a pilot plant was constructed at the Praxair Technology center in Tonawanda, N.Y., with testing starting in 2012. The pilot scale TCR was about 1/40th of the expected size for a typical 300-ton/d commercial glass-container furnace, and utilized a natural gas flowrate for the reforming reactions of about 30 Nm3/h.

The demonstration of the Optimelt TCR process started in a 50-ton/d container-glass furnace at Pavisa in Mexico in late 2014 (adopted for commercial operation in mid-2015). Fuel and O2 savings of 15 to 18% and low NOx emissions were demonstrated. For a larger-scale commercial furnace, expected fuel savings are about 20% compared to oxy-fuel and about 30% compared to air-regenerator furnaces.

A larger commercial system was installed for a tableware furnace at Libbey Glass in Holland in late 2017. Application of the technology to steel and other high-temperature industrial furnaces are also being planned.

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