Tangentially coal-fired boiler

NOj Control. NO control limitations are described in both Tide 1 and Tide 4 of the CAAA of 1990. Tide 4 requirements affect only coal-fired boilers and take effect at the same time that the boilers are impacted by CAAA SO2 requirements. As of 1996, EPA had estabHshed Tide 4 NO limits only for tangentially fired and waH-fired, dry-bottom boilers that would be impacted by Phase I of the CAAA SO2 regulations (Tide 4). Limits of 0.22 kg/10 kJ (0.5 lb/10 Btu) and 0.19 kg/10 kJ (0.45 lb/10 Btu) have been set for wall-fired and tangentially fired units, respectively. The EPA based these levels on what was achievable using low NO burners. However, plants can employ a number of different front- or back-end emissions controls, including a combination of options, to achieve these levels. EPA plans to announce Tide 4 NO requirements for 300 additional boilers by late 1996 or eady 1997. 

Three different types of coal fired boilers were utilized in this study. One type (A) was a dry bottom boiler with direct fired burners located on opposite walls. The second type (B), wet bottom boilers 11 and 12, was operated in parallel with the same coal stream split to feed both boilers simultaneously. The third boiler types (C D) were dry bottom, tangentially fired boilers. 

NO, emissions from power stations vary with the type of boiler as well as with other factors such as fuel type, boiler heat release rate, excess air, and mode of operation (e.g., cyclic vs. base load). Coal-fired boilers typically produce more NO, than oil- or gas-fired units. Wall-fired wet bottom and cyclone-fired boilers usually have the highest NO, emissions, while tangentially-fired and arch-fired boilers have the lowest. 

Approximate numbers and types of affected boilers 179 Coal-Fired Boilers 94 Tangentially-Fired, 85 Wall-Fired About 1,000 Coal-, Oil-, Gas-Fired Boilers of All Types All new units and existing units classified as new units due to major life extension modifications (i.e., WEPCO court order) and repoweting. 77 Coal-Fired Boilers 43 Cyclones, 18 Cell-Burners, 16 Wall-Fired 801 Coal-Fired Boilers All Types-698 Dry-Bottom 103 Wet-Bottom... 

Plant description. Two nearly identical 430-Mw(e), western, conventional pulverized-coal-utility boilers (referred to as plants A and D) were tested. Both units use tangentially fired burners and burn low-sulfur 200-mesh coal of heat content approximately 27 000 J/g. Both units are equipped with cold-side electrostatic precipitators (ESP) of design efficiency of 99.5% or greater, and a modern flue-gas desulfurization (FGD) system consisting of four verticle spray towers. 

Zolo reports an interesting example that illustrates the potential benefit of measuring temperatures in a coal-fired power plant boiler (Zolo 2009c). In this case, a nine-path ZoloBOSS system was installed on an 830 MW tangentially fired plant. As shown in Figure 14.23, six beams were placed in a 3 x 3 matrix below the boiler nose, and three parallel beams were installed at stations in the superheater sechon in an orientation perpendicular to the flow. 

Available data indicate that some coal burning wall-fired boilers can meet EPA s presumptive NO, RACT levels by application of low NO, burners at a cost effectiveness as low as 160 per ton. The data also indicate that certain tangentially-fired utility boilers may approach a cost-effectiveness level of 1300 per ton in order to meet the EPA presumptive NO, RACT levels. 

Title IV of the 1990 Amendments provides for the reduction of NO, emissions from coal-fired utility boilers in two phases. In the first phase, two categories of burners are affected dry bottom wall-fired and tangentially fired boilers (Group 1). Group 1 boilers under Phase I must meet certain performance standards by January 1, 1995. About one-quarter of all Group 1 boilers are covered in Phase I. 

Pulverized coal (PC) boilers are the most common large combustion systems for the generation of electricity in the US and the industrialized economies of the world. PC boilers include both wall-fired boilers and tangentially-fired (T-fired) boilers wall-fired boilers include both front wall and opposed wall configurations. Like cyclone boilers, they have the potential to use petroleum coke as a fuel provided that a sulfur dioxide scrubber has been installed on the unit. The vast majority of the petroleum coke fired in the USA is burned in PC boilers due to their dominance of the industry. Again the low volatility in the petroleum coke limits its use in PC boilers the typical cofiring percentage is on the order of 20 - 30 percent (calorific value basis). 

W.A. Parish Generating Station boiler 8 is a 555 MWe (net) tangentially-fired boiler supplied by Combustion Engineering (now Alstom) and commissioned in 1982. It is fired wifii Powder River Basin coal, and equipped with roller type pulverizers from CE [35]. The unit has the capacity to generate 530 kg/s (4.2x10 Ib/hr) of 165 bar/540°C/540°C (2400 psig/1000 F/1000°F) steam [36]. In 1995 tests were conducted at this generating station in collaboration with Q RL... 

Battista, J.J., and R.A. Ashworth. 1998. Co-firing Coal Water slurry Fuel on a Tangentially-Fired Boiler. Proc. 23" International Technical Conference on Coal Utilization and Fuel Systems. Coal Technology Association. Clearwater, FL. March 9 -13. pp. 361 - 370. 

CycUme Furnaces In cyclone firing (Fig. 24-l4d) the coal is not pulverized but is crushed to 4-mesh (4.76-mm) size and admitted tangentially with primary air to a horizontal cylindrical chamber, called a cydone furnace, which is connected peripherally to a boiler furnace. Secondary air also is admitted, so that most all of the coal bums within the chamber. The combustion gas then flows into the boiler furnace. In the cyclone furnace, finer coal particles burn in suspension and the... 

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