Linde's Combustion Test Facility

Paper from the AFRC 2013 conference titled Linde's Combustion Test Facility by Andrew Richardson

"Linde has developed a very well equipped combustion test facility in Conshohocken, PA. This facility is being upgraded to develop advanced combustion technologies including the effects of oxygen enrichment for a variety of applications in the metals, chemicals and refining industries. This facility includes a wide range of furnaces and thermal oxidizers from 1 - 40 MM BTU/hr. The combustion test facility is also equipped with pollution control equipment including a particulate filter, scrubber and quench system. Both liquid and gaseous feedstock can be handled at this facility. The combustion test facility also has state-of-the-art analytical equipment to test emissions."

Page | 1 Linde's Combustion Test Facility Andrew Richardson, Linde Gas, Murray Hill, NJ and Goutam Shahani, Linde Engineering North America, Blue Bell, PA Linde has developed a very well equipped combustion test facility in Conshohocken, PA. This facility is being upgraded to develop advanced combustion technologies including the effects of oxygen enrichment for a variety of applications in the metals, chemicals and refining industries. This facility includes a wide range of furnaces and thermal oxidizers from 1 - 40 MM BTU/hr. The combustion test facility is also equipped with pollution control equipment including a particulate filter, scrubber and quench system. Both liquid and gaseous feedstock can be handled at this facility. The combustion test facility also has state-of-the-art analytical equipment to test emissions. Page | 2 I. Introduction In North America, vast quantities of ‘shale gas' have recently become recoverable due to advances in horizontal drilling and well fracturing or ‘fracking'. Shale gas has become an attractive fuel and chemical feed stock, which has brought about a renaissance in manufacturing. The advent of inexpensive shale gas has been referred to as a potential ‘game-changer', which could make North America energy independent and revitalize manufacturing. In refining and petrochemicals, the driver will be cheaper feedstock and energy costs. For metals, growth will be driven by automobiles and more robust drilling and pipeline activity. For this trend to be sustainable, it is essential to focus on environmental factors in addition to energy considerations. In the last 20 years, manufacturing operations have successfully reduced effluents and emissions by reusing and recycling wastes. This has been achieved by innovative process designs to produce the desired end product efficiently and minimize the amount of wastes that are generated. However, it is not possible to reduce wastes to zero. This creates a need for waste destruction and efficient energy utilization using thermal oxidation. This paper will outline the capabilities of Linde's combustion test facility for energy utilization and waste destruction in the refining, petrochemical and metals industry. North America is a major manufacturing center based on the availability of raw materials, relatively well trained labor and highly developed infrastructure. While manufacturing jobs have declined in the recent past due to off shoring and out sourcing, this trend is likely to be reversed due to the inexpensive shale gas that is now coming to market. Inexpensive shale gas is providing North America with a competitive advantage in the global market place. In order to understand this evolving dynamic, it is instructive to examine trends in energy and emissions as these are important factors for manufacturing. The US Energy Information Page | 3 Administration compiles and publishes some very insightful statistics which are shown below in Figure 1. Figure 1: Energy and Emissions Source: U.S. Energy Information Administration, Annual Energy Outlook 2013 It is useful to examine the energy and emissions (as represented by CO2) per unit of GDP expressed in 2005 dollars. It can be seen that energy and emissions per GDP has been declining since 1980. This is due to the fact that services Page | 4 constitute a greater part of GDP and vehicles and appliances have become more efficient. CO2 emissions per unit GDP have declined more than energy due to a shift to less carbon intensive fuels such as natural gas. It is also interesting to note that energy use per capita has been declining due to more efficient appliances and automobiles. While these trends are definitely positive, further development of manufacturing capacity will necessitate paying close attention to both energy and emissions. To support this approach, Linde has developed several combustion technology centers worldwide to serve its gases and engineering divisions. One of these is a large scale pilot facility located in Conshohocken, PA. II. Linde's Conshohocken Combustion Test Facility The Conshohocken combustion test facility is located close to Linde's corporate offices in Pennsylvania and New Jersey. This facility was erected in 2000, as an extension to the T-Thermal pilot plant established at this location in the early 1950's. Subsequently, this plant was modified to incorporate Thermamtrix technology in 2002. The technology center has multiple uses including:  Research and development of combustion technologies  Trials of waste material under controlled conditions  Customer demonstrations As an EPA-permitted test facility, this combustion test facility has been used to perform demonstrations for various governmental agencies such as the US EPA, the DOE, and the DOD as well as many chemical, pharmaceutical and refining companies. The combustion test facility includes a combination of permanent and modular systems used for testing process operations. The modular units provide a Page | 5 system of "building" customized combustion systems for a given need. Currently, the inventory of combustion equipment at the facility will allow configuration as either a water-cooled or refractory-lined design with heat releases up to 40MM BTU/hr (11.6 MW). In addition, alternate equipment can be arranged for tail gas clean up such as a partial quench, wet scrubbers and fabric filter to demonstrate dry inorganic particulate removal compliance with environmental emission regulations. Waste feed options can handle a wide diversity of both gases and liquids. A local control room contains both the monitoring and control equipment to operate the systems in the combustion test facility. These systems are fully instrumented with automatic operation and safety interlocks. High temperature cameras located on select furnaces provide a visual insight into the internal combustion conditions. A continuous emission monitoring system (CEMs) with auto calibration and data logging can monitor stack gas components including O2, CO2, CO, SO2, NOx (NO and NO2), and total hydrocarbons (THC). Particulates and toxic emissions such as dioxins and furans can be measured. A chemical laboratory in close proximity to the control room and a working office is available for visitors with telephone and high speed internet connections. The facility systems include:  Down fired Sub-X® thermal oxidizer with a submerged quench, high-energy venturi scrubber, and a packed column for acid gas treatment. This unit may be used for testing with waste gases and liquids. Capacity: 3 MM BTU/hr (0.9 MW)  Two-stage combustor (reducing-oxidizing). Capacity: 3 MM BTU/hr (0.9 MW)  Thermal oxidizer with a countercurrent, spray quench and combination venturi / packed column scrubber using sub-cooled scrubber liquor applicable to waste gases and liquids  Large test furnace for conventional combustion development and testing. Capacity: 40 MM BTU/hr (11.6 MW). See Figure 6 Page | 6  GR flameless thermal oxidizer (waste gases) with internal heat recovery to minimize support fuel requirements  GH12 flameless thermal oxidizer for waste gas oxidation. Capacity: 5 MM BTU/hr (1.5 MW)  Capability to configure any of the above units for a broad range of oxygen enriched combustion of fuels and waste streams  Trailer mounted LoTOx™ system for NOx removal from flue gases This equipment is highly flexible and modular in nature and can be quickly and readily adapted for specific experimental purposes or customer needs. Recent customers include: Evonik, DuPont, Aramco, Dow Corning, and Eli Lilly. III. Current Programs The facility at Conshohocken is used by Linde's business units for the evaluation, development and demonstration of new technologies. Some current programs are summarized below. i. Combustion Development A current area of investigation concerns alternate firing strategies for blast furnace stoves. While there have been several instances of operating stoves with low levels of oxygen enrichment, additional benefits can be achieved by higher levels of oxygen enrichment. For example, a blast furnace stove can be fired with a low calorific value blast furnace gas using oxygen enrichment of the combustion air or a mixture of pure oxygen and recycled flue gas. The conventional method is to fire medium calorific value coke oven gas and a blast furnace gas blend with air. The oxygen/recycled flue gas process is shown in Figure 2 below. Process modeling Page | 7 reported elsewhere1 has indicated that not only can costs be reduced by significantly reducing the amounts of the higher value enrichment fuel used, but that it can allow reduced stove cycle times and harder firing resulting in higher average blast temperatures and lower coke consumption; and create a final effluent stream of higher CO2 concentration more amenable to capture and sequestration. Figure 2: Blast Furnace Stove Operation with Recycled Flue Gas It is fairly easy to determine the oxidant and fuel compositions required to match a flame temperature or combustion product temperature within the stove. However, actual flame behavior in an existing stove is more difficult to predict. Page | 8 These issues can be investigated using kinetic models and bench scale studies. However questions still remain on the true behavior with typical burner designs and stoves. A further question also lies in the performance of the regenerators or the checker pack with a change in the composition of the products of combustion. Increases in heat transfer coefficients of up to 13.5% are predicted when operating at constant volumetric flow rate and temperature when operating in a flue gas recycle mode owing to the higher CO2 levels. This may be exploited by reducing gassing times and improving efficiencies. To address some of these unknowns Linde has built a new 1.7 MM BTU/hr (0.5 MW) combustion test stand incorporating a combustion chamber coupled to a regenerator pack to evaluate both changes in combustion behavior on suitably scaled burner sections and the heat transfer from the combustion products. Figure 3: Combustor-regenerator test stand ii. Oxygen enrichment for metals - REBOXTM The Conshohocken facility is also used to develop oxy-fuel combustion in more typical applications. Oxy-fuel technologies have been employed in high temperature process heating applications for many years owing to the potential to improve efficiencies, production rates, process stability and product quality, while reducing flue gas volumes, emissions and equipment size and cost. Page | 9 Despite there being no change in the fundamental combustion reactions, the oxy-fuel combustion technologies have changed and adopted techniques familiar to those in the air-fuel combustion industry. Burners have evolved from early water cooled devices that typically yielded short intense flames that could cause localized overheating, to non-water cooled low-momentum burners that may employ staging or flat jet flames to distribute the heat. Such heat distribution allows even greater thermal input while avoiding local hot spots and reducing peak flame temperatures reducing NOx emissions further. Over the past 20 years Linde has pioneered the use of oxy-fuel in the steel reheat industry to the point where it is now a common practice. Of the more than 130 furnaces converted by Linde to oxy-fuel firing to date some 50 employ Linde's REBOXTM flameless oxy-fuel technology. In such a flameless approach furnace gases are entrained into and dilute the flame, reducing the flame temperatures and achieving more homogeneous heating of the steel load. This approach creates a system with reduced NOx formation that is very much less sensitive to air ingress. Page | 10 Figure 4: REBOXTM Concept Linde has recently completed and reported (2,3) on two REBOXTM flameless oxyfuel systems within the USA. Linde's burners are dual mode: below 1400 ºF, the burners operate as conventional oxy-fuel burners; and above an auto-ignition temperature of 1400 ºF, the burners switch to flameless combustion. In pusher reheat 2, and rotary hearth3 furnaces, these installations have demonstrated over 60% reduction in specific fuel consumption and 30% increase in throughput, while reducing scale formation and improving temperature uniformity. Page | 11 Figure 5: REBOXTM Burner Conventional mode ( < 1400 ºF) Flameless mode ( > 1400 ºF) There is interest in other process heating areas, e.g. glass and copper melting and blast furnace stove heating, which can benefit from diffuse combustion for uniform heating and a reduction of emissions on. To assist in the adoption and transfer of flameless or dilute combustion techniques into other areas, Linde is extending its oxy-fuel firing capability to include provision for oxy-fuel firing in a large 40 MMBTU/hr test furnace. iii. Flameless Thermal Oxidation Flameless Thermal Oxidation (FTO) was originally developed as a highly efficient energy recovery technology. Initial development was conducted at the Lawrence Livermore Laboratories, under the auspices of the United States Department of Energy. Further refinement was supported by private funding and with the expertise of individuals originally associated with the project, later organized as Thermatrix Inc. In 2002, Selas Fluid Processing acquired Thermatrix. The FTO technology is synergistic with the Company's thermal oxidizers, liquid Page | 12 incinerators, burners, and unique scrubbing systems. An operating demonstration unit is installed at the Technology Center in Conshohocken, PA. Flameless Thermal Oxidation is a process that thermally decomposes waste gases with air to convert organic compounds to their oxidized state, and release heat without producing a flame. This is accomplished by heating the compounds above their auto ignition temperature under controlled conditions in a specially designed reactor that absorbs and dissipates the heat of reaction. A stable oxidation zone is maintained at a precise temperature and residence time sufficient to compensate for variations in waste flow and composition. The reactor consists of a refractory lined, cylindrical vessel (material of construction varies with application) with a central inlet dip tube. The vessel is approximately half filled with randomly packed, inert ceramic media to form a uniform matrix below and around the dip tube. Electric heating elements or a preheat burner heat the ceramic matrix to the operating temperature for start up only. Depending on the waste composition, dilution air and fuel are trimmed so the mixture never exceeds 85% of the lower flammability limit (LFL). This also ensures that the velocity of the gases flowing through the matrix equals the velocity of the reaction to maintain a stable reaction zone in the matrix. The volume of the chamber and the amount of ceramic matrix above the oxidation zone is designed to ensure a retention time at which destruction efficiencies exceed 99.99%. The system can be turned down to 33% of its rated capacity. Linde's FTO technology has repeatedly demonstrated an organic waste destruction efficiency of 99.99+ %, virtually undetectable NOx and CO emissions and dioxin and furan emissions less than 0.1 ng/m3 TEQ with chlorinated hydrocarbons. This unique performance assures a high degree of regulatory compliance. Recent customers include: Dow Chemical, Pfizer Chemicals, Chevron Chemical and Lyondell Chemical. The FTO facility is currently being upgraded. Page | 13 iv. LoTOxTM The patented LoTOxTM system is a non-catalytic, low temperature oxidation process for the removal of NOx from flue gases. Oxygen is converted to ozone in an ozone generator. The ozone is injected into the flue gas stream where it reacts with relatively insoluble NO and NO2 to form N2O3 and N2O5, which are highly water soluble, and are easily removed and neutralized in a wet scrubbing system. The LoTOxTM system is very selective for NOx removal, oxidizing only the NOx. LoTOxTM was initially developed by Linde to treat exhaust from boilers, furnaces, refining, sulfuric acid and steel pickling operations. In practice, NOx reductions of more than 99 percent have been achieved. Linde has developed a special trailer mounted system which is equipped to generate ozone. This system can be easily deployed at the combustion test facility or a customer site to demonstrate the efficacy of the LoTOxTM process. Building on the success of LoTOxTM in the refining industry, Linde is now exploring other industries, including petrochemicals, cement, glass, and non-ferrous metals. IV. Summary Linde is proactively upgrading its combustion test facility in Conshohocken, PA to address the resurgence in North American manufacturing activity brought about by the commercial exploitation of shale gas. This facility is used for the research and development of Linde's combustion technologies as well as customer demonstrations of waste materials under controlled conditions. The combustion test facility is equipped with pollution control equipment and state-of-the-art analytical equipment to measure emissions. The effects of oxygen enrichment for a variety of applications in the metals, chemicals and refining industries are being investigated, demonstrating Linde's commitment to solving important Page | 14 energy and environmental issues in partnership with local manufacturing companies. V. References 1. Cameron et al, Flameless oxy-fuel combustion in cowper stoves. A basis for reducing CO2 emissions by 30 %, METEC 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry 2011 2. Heine et al, EVRAZ Claymont Steel Pusher Reheat Furnace 100% Oxyfuel Conversion, AISTech 2013 3. Sleder et al. Increased Heating Throughput and 63% Less Fuel with Flameless Oxyfuel at MST - Seamless Tube & Pipe, South Lyon, MI, AISTech 2013 4. U.S. Energy Information Administration, Annual Energy Outlook 2013 Page | 15 Figure 6: "Big Red" Furnace (40 MM BTU/hr) Page | 16 Figure 7: Redox Thermal Oxidizer with Quench and Scrubber (3MM BTU/hr) Page | 17 Figure 8: Flameless Thermal Oxidizer (FTO) with APC System Page | 18 Figure 9: Incinerator with Air Pollution Control System (2MM BTU/hr)