Babcock Power Environmental Inc. (BPE),  (formerly Babcock Borsig Power, Inc.)  has been integrating the United States and German technology for wet flue gas desulfurization (WFGD) in the United States since 1994. Our knowledge of both limestone and lime reagent process systems for a variety of fuels, including lignite, low/high sulfur coal and Orimulsion®, account for greater than 50,000 MW of  BPE’s licensor designed flue gas desulfurization (FGD) systems operating worldwide.  BPE offers to the North American marketplace proven flue gas desulfurization technologies, integrating the knowledge and experience of the former companies of Deutsche Babcock Anlagen, Steinmüller, Noell-KRC, and its affiliate Riley Power Inc. (RPI) (previously DB Riley).  Their combined application of these technologies is greater than any other WFGD supplier.  In addition, BPE has the most experience with gypsum by-products, with 48,000 MW of installed systems.

TECHNOLOGY IMPROVEMENTS

Dual Flow Nozzle – The challenge within the industry has been to maintain the required liquid limestone slurry to flue gas flow.  Older absorber designs accomplished this with the use of the largest slurry pump possible and multiple levels of spray headers into the vessel.  However, each level of spray header increased the height of the absorber, requiring larger foundations, greater stack height and higher installation costs.  BPE was one of the first suppliers to use a dual flow up/down slurry nozzle.  Essentially, each level of spray header can therefore provide twice the limestone slurry to the flue gas.  This approach minimizes nozzles, headers, associated pumps, and power consumption thereby significantly reducing capital costs.

Absorber with Integral Stack – An additional cost saving design is the integration of the stack with the absorber.  This design is beneficial when there is little real estate available for the new WFGD system. There is also a considerable reduction in the cost of materials and labor that would typically be required from the absorber outlet to the stack inlet.  A common foundation reduces sub-soil foundation costs to a minimum.

Largest Shippable Components – The higher cost and shortage of labor during outage periods became a concern during the OTAG Selective Catalytic Reduction Program.  The design philosophy used by  BPE to modularize equipment and ship in the largest component configuration resulted in  a decrease in jobsite labor costs and schedule.  We have proven that the additional design and shop fabrication costs far outweighs the field labor costs of shipping smaller, untested assemblies to the jobsite.  Each  BPE project team has an assigned Construction Specialist involved in the design phase of the project to insure that these cost savings are realized.  Skid-mounted equipment is functionally checked for operation in the shop before shipment to minimize on-site activities and costs.

Cooling Tower Stack Discharge – This innovation has been successfully applied on BPE units to eliminate the need to construct a wet stack. BPE uses a Fiberglass Reinforced Plastic duct to transport the Absorber flue gas discharge into the base of a cooling Tower.  There are also capital costs and better dispersion benefits often associated with this arrangement.

Multi-pollutant Control – Babcock Power’s (BPE & RPI) market leadership position in SCR installations led to a more complete understanding of SO3 and its generation within a complete air pollution control system.   BPE’s Wet Electrostatic Precipitator (WESP) is a proven technology for effective SO3 and fine particulate material removal.  Recent improvements by BPE include the integration of the WESP within the WFGD absorber.  This design brings together a single system for the removal of SO2, HCl, SO3, Hg and fine particulates.

Computer Assisted Design & Project Management - BPE has devoted a team of engineers and project management individuals to the development of a program to enhance, optimize and reduce the costs associated with WFGD system design, procurement, fabrication and erection.  The two key elements of this program are our parametric three-dimensional design platform and project collaboration software.

Parametric Three-dimensional Design – Utlizing this tool, Babcock Power has the ability to take the process design calculations and electronically produce design specifications, a three-dimensional model, requests for purchase, construction packages, fabrication design drawings, training manuals and operation & maintenance manuals.  Equipment, site layouts and “what if” scenarios can all be analyzed, and refined in total collaboration with the client, equipment suppliers, fabricators and construction team.

Project Collaboration Software – BPE has recognized that sufficient information is often not available in a timely manner to all the individuals involved on capital projects.  Drawing review cycles lag development of the final design and delay equipment purchase and ultimately site installation.  BPE has developed a worldwide web-based collaboration approach that will allow any individual with www access and a password to acquire data from an electronic project file system.  This file system includes all the most recent drawings for the project.  Drawing review is electronic with the ability for all team members to comment on the “live” document.  We believe this access will allow typical 90-day drawing review to the final cycle status to be reduced to less than 10 days.  An additional value of this approach will be the completion of as-built drawings the day construction is completed.

Supplier Alliances - As a result of its successful Selective Catalytic Reduction Programs, BPE and its affiliate RPI have proven the positive benefits of Alliance Programs.  The ability to control capital expense and to build flexibility into the delivery and scheduling of equipment and materials reduces overall project costs.  Since there will be fewer qualified sub-vendors in today’s marketplace, BPE will continue to promote this concept to offer increased value to our Clients for our WFGD programs.

Babcock Power Inc., through its various subsidiary companies, has not been waiting for the WFGD Market to “hit” in the United States. BPE has been active in solving the air pollution control concerns of our Clients worldwide.  Babcock Power’s complete line of technologies, including low NOx burners, boiler modifications, Neural Networks, Selective Catalytic Reduction systems, Dry Flue Gas Desulfurization systems, Wet Electrostatic Precipitators and Wet Flue Gas Desulfurization systems, are all available to the US market.  BPE has FGD experience dating back to 1980.  We have continued to develop innovative technologies and solutions for our Clients to position Babcock Power as the world’s leading provider in Flue Gas Desulfurization technologies.

Babcock Power Environmental Inc. and its affiliate Riley Power Inc. (together referred to as Babcock Power) are the leading technology designers for utility and waste-to-energy Selective Catalytic Reduction (SCR) systems in North America. Babcock Power designed and built the largest Selective Catalytic Reduction system operating in the world. We have experience with a wide range of fossil fuels including Powder River Basin Coal, refinery bottoms, Pet Coke, and high sulfur coals. Babcock Power also has the technology base to design Selective Catalytic Reductions for fuels with high levels of catalyst poisons including arsenic. Babcock Power, in the US, has over 36,000 MWs of SCRs commissioned, in design or evaluation and under construction. In addition, our technology has over 26,000 MWs of SCRs operating in Europe. This broad base of experience coupled with our state-of-the-art boiler design capabilities provides Babcock Power with the expertise to furnish SCR systems that are reliable, flexible in operating parameters and meet current economic and environmental challenges.

Babcock Power’s scope of supply is the complete SCR system. It typically includes reactors, all associated support steel, ductwork, isolation/bypass dampers, expansion joints, access/testing provisions, platforms/stairs, initial catalyst charge, fans if required, complete reagent unloading, storage and injection systems. Babcock Power has installed anhydrous and aqueous ammonia systems, as well as various urea systems. This broad base of experience allows Babcock Power to select the most advantageous technology for any specific application.

The experience Babcock Power has attained provides the capability to minimize the impact of arsenic poisoning and SO3 emissions that can be problematic with certain US coals. For utility SCR applications, Babcock Power offers high temperature, and tail end systems, as well as tail end system SCRs for waste-to-energy plants.

DELTA WING® MIXING TECHNOLOGY
One of the primary technology advantages that Babcock Power offers is the application of the proprietary Delta Wing® Technology. The SCR systems furnished utilize technology under an exclusive license from Balcke Dürr GmbH and from other Riley Power Inc. proprietary sources. The application of this technology to SCR installations allows both gas mixing and reagent injection in one simple application, with no moving parts in the gas stream. This advantage has provided Babcock Power with easy, expeditious SCR startups and minimizes the need for extensive tuning during commissioning or annual "tuning" of installed SCR systems.  With the application of Delta Wing®technology, startups usually require about one week from start of operation to commercial operation.

It is quite common to have temperature or constituent concentration differences in any flow stream. A typical non-uniform flow stream would be the flue gas leaving a boiler with less than a full complement of burners in service. For example, the temperature or oxygen concentration can be different from "side-to-side" exiting the boiler even though the gas has passed through tube bundles and been in a turbulent flow regime. This turbulent gas flow does not necessarily generate homogeneous flue gas. There is no "side-to-side" mixing.

The Delta Wing®Mixer receives this boiler exit gas and makes it homogeneous. It mixes all gas characteristics: temperature, oxygen concentration, dust concentration, NOx concentration, ammonia concentration, SO3 concentration, etc. The mixer itself is a stationary obstruction in the duct, usually a disk or triangular plate, oriented at a slant to the flow direction. Upstream of this device is turbulent but not necessarily homogeneous flue gas. Immediately downstream of this device are large violent vortices. The duct may have four or five mixers over a 40-foot wide duct and the resulting vortices cover the whole cross sectional area of the duct. If the test model of the system indicates it is necessary, a second set of mixing devices can be added downstream of the first set, usually at a 90° turn just before the reactor. The result of these vortices, as they flow downstream and mix with adjacent vortices, is a well-mixed homogenous gas.

These vortices consistently form in relation to the mixing device size, position, and orientation in the ductwork system. Because of this, Babcock Power is assured of two key things:

1. The vortices can be well modeled, i.e. predetermined, in a 3D model based on a scaled geometry of the ductwork system and mixing device size, position and orientation.
2. The vortices are not dependent on gas flow quantity and therefore will consistently form over a wide range of gas flows and boiler outlet conditions.

These two key factors have been proven numerous times by scale models used in all of our projects and by the close correlation between the "modeled" and "real world" performance measurements in the actual installations. The Delta Wing® technology has consistently performed well over a range of gas flows exceeding the normal turndown range of the boiler.

For SCR System applications, the vortex zone immediately downstream of the mixer is the location of the ammonia injection nozzle. The best means of assuring uniform ammonia distribution in combination with uniform NOx distribution and flue gas temperature is to achieve a well-mixed homogeneous gas.

This condition is also achieved at reduced load conditions. Other systems, such as grid ammonia injection systems, are "tuned" to perform best at full load gas flow. A typical grid system uses a large number (hundreds) of nozzle injection points and, when tuned, each point may be required to deliver different ammonia flow quantities. As the total flue gas quantity is reduced, the gas characteristics, such as temperature distribution and NOx distribution, change. The ammonia flow also changes with flue gas quantity. At part load conditions, the grid system goes "out of tune" and performs less than optimally. This can result in poor NOxreduction, excessive ammonia usage, and higher than allowable ammonia slip.

Other so-called "static mixing devices" or "riffles" are applied by others to SCR Systems and have not proven effective. They attempt, by passing the gas through multiple non-parallel channels, to redirect the gas from one position of the cross section of the duct to a different position. They are not effective when compared to vortex mixing and have limited application in very large ducts. Furthermore, they are subject to the same difficulties when faced with mixing reduced gas flows, especially the dust component.

With the Babcock Power vortex mixing technology, the performance is consistently optimal over the entire load range because homogeneity is achieved over the entire load range. This mixing advantage allows the Delta Wing® system to consistently reach NOx reductions of greater than 90%.

Babcock Power also offers an integrated solution for Catalyst Management. We can provide independent consultation services to any SCR installation. Babcock Power is not tied to any catalyst manufacture or process, therefore, analysis and recommendations will be based solely on your economics and needs. Babcock Power is the largest technology provider of NOx, SO2 and mercury control systems in the world.

Riley Power Inc.'s CCV® (Controlled Combustion Venturi) low NOx burner is designed for wall-fired coal, and coal and oil combination applications. It has also been successfully installed in numerous cell burner installations as a retrofit burner without pressure part modifications. Almost 2000 CCV® burners have already been installed on coal fired units.

NOx control is achieved with Riley Power Inc.'s patented venturi coal nozzle and low-swirl spreader located in the center of the burner.

The venturi nozzle concentrates the fuel and air in the center of the coal nozzle creating a very fuel-rich mixture. As this mixture passes over the coal spreader, the blades divide the coal stream into four distinct streams. These streams enter the furnace in a gradual helical pattern, resulting in gradual mixing of the coal and secondary air. Secondary air is introduced to the furnace through the air register, supported by the burner front plate, and then through the burner barrel and over the secondary air diverter. Devolatilization of the coal in the fuel-rich mixture occurs at the burner exit in an oxygen-lean primary combustion zone, resulting in lower fuel NOx conversion. Peak flame temperature is also reduced, thus suppressing thermal NOx formation.

Riley Power Inc.'s CCV® ( Controlled Combustion Venturi ) Dual Air Zone Burner Demonstrates 20% Additional NOx Reduction beyond the original Single Register Burner.

Full scale test results confirmed that the low NOx CCV® Dual Air Zone Burner allows Riley Power Inc. to offer an enhansed option for controlling NOx emissions from pulverized coal-fired boilers. Riley Power Inc. does not intend to replace the CCV® Single Register low NOx Burner which has been used successfully for many years. We will review each low NOx burner application carefully and select the appropriate low NOx burner solution which will be most appropriate to meet the requirements of a particular application.

The CCV® Dual Air Zone low NOx burner utilizes the same low NOx venturi coal nozzle design used in the CCV® Single Register burner, which produces a fuel-rich flame core, but also incorporates a dual air zone arrangement. This provides additional control of burner zone stoichiometry at the coal nozzle discharge for further NOx control.

Features and Benefits of CCV® Dual Air Zone Burners

Typical NOx levels achieved for CCV® Dual Air Zone burners range from 0.38 lb/mmbtu for firing E. bituminous coal unstaged to 0.15 lb/mmbtu for firing sub-bituminous coal staged.

Selection of Single Register or Dual Air Zone CCV® Burners for a particular unit depends on many factors. These include NOx emission reduction requirements, budget restraints, and the specific application.



The TSV® Burner is a low NOx replacement burner for the downward-firing Directional Flame Burners applicable to Riley Power Inc's TURBO® Furnace units. Increased reduction of NOx results from distributing, controlling and gradual mixing of coal and air. Tertiary air is added through outboard tertiary air ports or a separate tertiary air zone within the burner itself.

Riley Power Inc. continues to improve the design of its low NOx Directional Flame Burners (DF) used in coal fired TURBO® Furnaces.

The latest improvement incorporates a patented tilting coal nozzle. The new design allows for on-line adjustment of the nozzle tip to alter the direction of the coal entry into the furnace. The tilting coal nozzle design is capable of up and down movement typically + / - 20° from the normal burner axis. The result is better control of steam temperature, flame attachment, NOx emissions, and furnace slagging.

The tip is constructed of high-grade alloy materials to extend wear life and mechanical reliability. Adjacent sets of coal nozzle tips are manually operated in unison by an actuator on the burner front.

DF Burner Upgrade Features and Benefits

Low NOx Solution
The titling coal nozzle can be included in the Directional Flame (DF) burner system for controlling steam temperature and NOx emissions on coal fired TURBO® furnaces.

The system includes the DF burner with internal windbox partitioning, tilting coal nozzles, and overfire air (OFA), all optimized through the use of in-house CFD modeling. The special windbox partitioning enables the OFA to be controlled independently from the main combustion air feeding the burners.