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Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project 1.1.5 COMBUSTION AND PULVERIZED COAL FIRING SYSTEM 1.1.5.1 In-Furnace Blending Technique July 7, 2014 Traditionally, blending coals of differing ranks complicates the combustion system design for boilers and requires over-sizing and compromising of optimal performance as individual equipment is required to operate in a non-ideal mode. In such a scenario, effectively, the equipment must try to meet the differing needs of both coals at the same time which means that it won’t be operating as efficiently as would otherwise be the case. B&W has extensive experience with a wide range of coals sourced world-wide and recognizes that for a design that will utilize differing ranks of fuels, such as those proposed here, a better design solution is required. For this project, B&W is proposing to utilize an In-Furnace Blending Technique and has designed the equipment to complement this strategy while still providing maximum fuel flexibility for 100% operation on either Coal A or Coal B. In practice, B&W has developed a strategy for blending Coal A and Coal B in the furnace rather than in the coal handling system. The In-Furnace Blending Technique simplifies the coal handling system and reduces associated costs by eliminating the need for coal blending equipment in the coal yard. It also allows the pulverizers to operate more efficiently and reduces the total number required, because the more difficult to grind coal is isolated in particular mills. Each coal is fed, without need for blending, to the selected raw coal storage silos. All silos can be filled with Coal A, all with Coal B, or any combination of silos with either Coal A or Coal B. This provides fuel flexibility while minimizing equipment requirements. All feeders, pulverizers, and control hardware remain identical among the six supplied pulverizers. This provides for 100% MCR operation firing Coal A and 100% MCR operation firing Coal B. Blending is accomplished by distributing the coals into the appropriate number of mills. It is envisioned that for the Performance Blend (70% Coal A, 30% Coal B by weight), three mills would handle Coal A and two mills would handle Coal B as shown in Figure 1 below. B&W Proposal P-043049 Page 1 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 Figure 1: Example of In-Furnace Blending scenario for performance blend firing The In-Furnace Blending practice will reduce the quantity of pulverizers required from eight to six, while still meeting n-1 operation (one pulverizer out of service) at 100% MCR load firing the Performance Blend. All of the low NOx DRB-XCL® burners are also identical and suitable for firing either Coal A or Coal B to the maximum rated heat input. All of the burners served by a given pulverizer are situated in a single horizontal row. This results in three burner rows on the front wall and three on the rear wall of the furnace. In order to provide maximum fuel flexibility, the pulverizers/combustion system is designed to accommodate differences in coal throughput depending upon which coal is in use in a given pulverizer. For example, to operate at the same firing rate on the respective burners, the pulverizer(s) using Coal A would operate at approximately 40% higher coal feed rate compared to the pulverizer(s) using Coal B. B&W Proposal P-043049 Page 2 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 Typically, certain pulverizer groups and their related coal silos would be dedicated to either Coal A or Coal B, when both coals were simultaneously in use. In any case, the differences in coal properties make it clear which pulverizers are operating with which coal. Pulverizers operating with Coal A will require much higher primary air temperature into the pulverizer in order to sufficiently dry this coal, due to the higher coal moisture, and due to the higher coal HGI, will demand less power consumption and pressure drop during pulverization. The coal/air temperature leaving the mill will be 130-140°F (54 – 60°C) with Coal A. Conversely, pulverizers grinding Coal B will operate with higher power consumption and pressure drop, due to the lower coal HGI, and considerably lower mill inlet temperatures for coal/air exit temperatures of 170-185°F (77-85°C) due to the lower coal moisture content. It is not possible (or desirable) to operate with Coal A and outlet temperatures over ~60°C, thus making clear to the operator which fuel is in use in a given pulverizer. Normally all in-service burners are fired at the same thermal input. However, this combustion system is designed to facilitate bias firing to provide even greater fuel flexibility. Bias firing refers to operation at somewhat different firing rates (thermal inputs) on different burner rows. Bias firing therefore requires the ability to balance combustion air to firing rate on a per burner row (per pulverizer) basis. This enables the most efficient operation with minimum NOx emissions. Combustion air management is provided by the compartmented windbox burner arrangement shown in Figures 2 and 3 below. B&W Proposal P-043049 Page 3 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 Figure 2: Compartmented Windbox with Feeder Ducts and Pitot Grid Array (Typical) As illustrated, all burners fed from a particular pulverizer are located in a single row. Each burner row is separated by partition plates from the other burner rows, effectively providing individual windbox compartments for each burner row. Feeder ducts supply secondary air to each end of each compartment. Each feeder duct is equipped with a pitot grid array to provide an accurate indication of secondary air flow. Each feeder duct is also equipped with an automated damper to regulate the secondary air flow per compartment in accordance with the associated pulverizer operating conditions. B&W Proposal P-043049 Page 4 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 Figure 3: Compartmented Windbox (outlined orange) with Feeder Ducts (shaded blue) In summary, in-furnace blending provides a more efficient means of handling coals with widely different characteristics. It eliminates the need for coal blending equipment in the coal yard, and reduces the necessary grinding penalties on some of the pulverizers. In this case it reduced the pulverizer quantity from eight to six, while enabling use of the coals singly or in combination. The compartmented windbox burner arrangement provides greater operating flexibility while managing air/fuel on a per-pulverizer basis. B&W Proposal P-043049 Page 5 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project 1.1.5.2 July 7, 2014 B&W’s Burner Technology for Low NOx Combustion Babcock & Wilcox has a long history of innovation and successful application of combustion systems to effectively and reliably reduce NOx emissions on coal-fired boilers. B&W has sold more than 115,000 MWe of low NOx combustion equipment since the early 1970’s. This includes B&W’s robust and well proven DRB-XCL™ burner design capable of producing low NOx in both staged and un-staged modes of operation with over 22,000 MW of installations. The Dual Register XCL burner is B&W’s second generation low NOx burner. The DRB-XCL® is mechanically designed for long service life and reliable operation. The functional design is very well suited and proven for firing a wide variety of coals, ranging from lignite and sub-bituminous to bituminous. This makes the DRB-XCL® particularly well suited for the Duyen Hai 3 project, where coals with widely different characteristics are intended for use. The DRB-XCL® is physically arranged as shown in the illustration below. The burner nozzle is equipped with Conical Diffuser/Deflector hardware to accomplish the necessary fuel mixing. The majority of the pulverized coal (PC) enters the burner nozzle along the outer radius of the B&W Proposal P-043049 Page 6 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 burner elbow due to centrifugal forces. The deflector at the entrance of the burner nozzle redirects the PC into the bullet portion of the conical diffuser where the dense stream is dispersed. The dispersed PC is shaped by the conical shroud around the bullet to form a fuel rich ring near the wall of the coal nozzle, and fuel lean in the center. This fuel pattern serves to improve the rate of ignition and flame stability of the burner. The burner is specifically designed to generate rapid heating and high temperatures in the fuel rich flame core. This causes more of the coal to burn as volatile matter and releases a larger portion of the fuel nitrogen early in the combustion process, leaving less in the char. By limiting available oxygen in the flame core, NOx formation is minimized. At the same time, reducing species are generated from the volatile materials. These propagate into the flame to aid in reducing NOx formed in the later zones of the flame. Char oxidation occurs last at reduced temperature and oxygen concentrations, thereby limiting NOx formation during char burnout. NOx ports can be added when further NOx reduction is required. Typical B&W DRB-XCL® Burner Staged & Unstaged Low NOx Sliding Air Damper Conical Diffuser Air Measuring Pitot Grid Stationary Vane Outer Zone Adjustable Vane Inner Zone Adjustable Vane Pulverized Coal and Primary Air Inlet Secondary Air (SA) flow to the burner is regulated by a sliding air damper. The slide damper can be positioned by an automated actuator (as illustrated for use in open windboxes) or by a ratchet jack device for use in compartmented windboxes. An impact/suction pitot tube grid is located in the burner barrel to provide a local indication of secondary air flow for each burner. With this information, the secondary air can be more uniformly distributed among all the burners in a given compartment, by appropriately adjusting the sliding air dampers. B&W Proposal P-043049 Page 7 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 Downstream of the pitot tube grid are the inner and outer air zones. Adjustable vanes in the inner zone impart sufficient swirl to stabilize ignition at the burner nozzle tip. The outer zone, the main SA path, is equipped with two stages of vanes. The upstream set is fixed and improves peripheral air distribution within the burner. The downstream set is adjustable and provides proper mixing of this secondary air into the flame. The DRB-XCL® is designed for long service life and reliability. This framework and structure was first developed by B&W in the 1980’s and has proven to reliably withstand the rigorous conditions prevalent in utility coal fired boilers. The DRB-XCL® benefits from experience and refinements incorporated into the mechanical design over many years. The burner nozzle is lined with ceramic tile to protect the nozzle from erosion. The conical diffuser and deflector are constructed from nitride bonded silicon carbide and provide excellent resistance erosion. All of the front end elements of the burner are fabricated from high quality stainless steel to protect against overheat damage. The structure of the burner includes a system of longitudinal stiffeners to accommodate thermal expansion, while avoiding distortion or loss of function. Each burner is equipped with shop-installed thermocouples to provide indications of front end burner temperatures to guard against overheat. An Advanced Over Fire Air System is integrated with the DRB-XCL® burners for this project. The rugged, adjustable Dual Zone NOx ports supply the remaining over-fire air (OFA) necessary to complete combustion. Correct separation between the OFA system and burners provides time for more NOx reduction, and provides more complete char burnout ahead of the OFA system. The DRB-XCL® burners were sized for the Duyen Hai 3 application by considering the specified Coal A and Coal B being fired in setting the optimum burner velocities. The range coals as well as the additional coals specified in Section 1.1.1 were considered in order to check that acceptable velocities were also attained while firing these coals. The adjustable Dual Zone NOx ports were sized by considering the performance design coal being fired in setting the optimum burner velocities at an overall design burner zone stoichiometric ratio of 0.95. The range coals as well as the coals listed in Section 1.1.1 were considered in order to check that acceptable jet penetration velocities were also attained through the Dual Zone NOx ports while firing these coals at the expected design stoichiometric ratio. B&W Proposal P-043049 Page 8 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project 1.1.5.3 July 7, 2014 Burners and NOx Ports Each unit will be supplied with thirty (30) Babcock & Wilcox Dual Register DRB-XCL® coal burners, ten (10) heavy fuel start-up oil burners, and one level of ten (10) Babcock & Wilcox Overfire Air Ports. Each burner includes the following:  Ceramic-lined coal elbow at inlet  Coal nozzle with conical silicon carbide diffuser  Silicon carbide deflector for optimum distribution of coal in the nozzle  Adjustable inner and outer air zone spin vanes to control air swirl  Air slide disk, with manual actuator, to adjust burner air flow and to permit burnerto- burner air balancing  Local burner air flow indicator  Class I ignitor with high energy spark system  Flame detector sighting tube  Observation door Each of the lowest level of burners will also be supplied with the following:  One heavy fuel oil start-up burner B&W Dual Zone NOx ports of the Advanced OFA system are designed and arranged to reduce NOx emissions by air staging. The unique dual zone design improves mixing capability, in order to reduce NOx while minimizing unburned combustibles. A sliding sleeve, is manually adjustable to optimize, regulates airflow to each port. The air then proceeds to either the central core zone or the outer air zone. The core zone provides an axial jet of air to penetrate and mix with flames further out in the furnace. Air through the outer zone is swirled to better mix with flames and gases closer to the wall. B&W Proposal P-043049 Page 9 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. All rights reserved Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project July 7, 2014 Each Dual Zone NOx port includes the following:  Manual actuator to adjust secondary airflow through the sliding sleeve  Manually adjustable disk to regulate airflow to the core zone  Manually adjustable vanes in the outer zone  Pitot grid to locally indicate NOx port airflow Typical Dual Air Zone NOx Port With Total Air Flow Control B&W Proposal P-043049 Page 10 of 22 PROPRIETARY AND CONFIDENTIAL Copyright © 2014 Babcock & Wilcox Power Generation Group, Inc. 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