Spreader Firing: CG and RG with Spreader Stokers This is the most common method due to its very high fuel flexibility, excellent multifuel capability, very good load dynamics and operational simplicity, reliability, and safety. Combustion Process in Spreader Firing This process is characterized by a two-stage burning—suspension mode in furnace and bed mode on grate. […]

Chain or Traveling Grates with Gravity Feeding A typical gravity-fed TG is shown in Figure 11.6. These stokers were the forerunners of SS and were popular until 1960s when coals were of good quality and process industry requirements were modest. Although they are suitable for good-quality coals and lignites and especially good for abrasive fuels […]

Grate burning can be classified as (1) mass burning (MB) and (2) spreader burning (SB), depending on whether the fuel burns on the grate or partly in suspension and partly on grate. There are two designs each for MB and SB. The spreader stokers (SS) are the most common. 1. MB with gravity feeding A. […]

Stoker firing has evolved for more than a century and a half. After serving as the backbones of the industry and small power for several decades, stokers have been sidelined for the past quarter century due to: • Dwindling availability of good coals suitable for firing on stokers • Tighter pollution requirements • Increasing steam […]

Oil and gas are clean and quick-burning fuels that require smaller furnaces and lesser HS in the tube banks. The boilers are compact. This feature enables shop manufacturing of [LST- Atomizing steam valve Air Register ///// 1———— Flame detector Main burner gun (with insert retract cylinder) I Cylinder and fuel oil valve Pilot Burner Flame […]

The primary aims of a management and safety system are: • A safe startup and shutdown of the burners • A safe operation of all the burners in the boiler Burner management and safety are handled by the electronics and software portions of the burners. The complexity of the logic is directly proportional to the […]

Burning of any liquid or gaseous fuels inside a duct with a flowing stream of air or gas is carried out with the duct burners. They are mostly used in a normal boiler for • Inlet ducts of heat recovery steam generators (HRSGs) using turbine exhaust gas • Underbed PA ducts of fluidized bed combustion […]

Burner Size Burner. A burner brings together the fuels and air in right proportions and admits them into the furnace chamber to accomplish combustion in an efficient and safe manner. It mixes and burns the fuel but does not control it. The proportion and regulation are per­formed externally for fuel and air by control valves […]

Oil and Gas Firing Liquid and gaseous fuels are burner fired. Solid fuels when pulverized and mixed with air are also amenable to burner firing; this is covered in detail in Chapter 13. The new duct burners are used to fire light oils and gaseous fuels inside the confines of a duct. This chapter deals […]

Small versus Large Utility Boilers The utility or power boilers are of two types: 1. Small utility boilers ranging from 100 MW (400 tph) to 300 MW (—1000 tph) 2. Large utility boilers >300 MW (—1000 tph) A size of 1000 tph is arbitrary; the dividing line between small and large utility boilers of 400 […]