Circulating fluidized bed boilers (CFB boilers) and bubbling fluidized bed boiler main differences in furnace gas flow rates increase at the furnace outlet set separators, and be carried by smoke exhaust Chamber of small solid particles, following the separator, and then sent back loop combustion. Fluidized bed combustion abbreviation FBC (fluidized bed combustion), referred to as CFB or circulating fluidized-bed boiler CFBC (circulating fluidizedbed combustion). Pressurized fluidized bed boilers combustion fluidized bed is carried out under pressure, referred to as PFBC (pressurized flu-idized bed combustion), is the stage of further development of circulating fluidized bed boiler.

1. Circulating fluidized bed boiler (CFB
boiler) working principle
Circulating fluidized bed boilers (CFB boilers) and bubbling fluidized bed boiler main differences
in furnace gas flow rates increase at the furnace outlet set separators, and be carried by smoke
exhaust Chamber of small solid particles, following the separator, and then sent back loop
combustion. Fluidized bed combustion abbreviation FBC (fluidized bed combustion), referred to
as CFB or circulating fluidized-bed boiler CFBC (circulating fluidizedbed combustion).
Pressurized fluidized bed boilers combustion fluidized bed is carried out under pressure,
referred to as PFBC (pressurized flu-idized bed combustion), is the stage of further development
of circulating fluidized bed boiler.
Boiler (CFB boiler) solid coal grain in gas or liquid role Xia into stream of State of process is to
stream of speed of increased and bed layer resistance of changes for features of, as stream of speed
of increased, boiler (CFB boiler) bed layer expansion, followed by after fixed bed State, and drum
bubble stream of bed State, and slugging bed State, and turbulence bed State and fast bed State.
Airflow speed lower, solid particles basic not moving of State was called fixed bed; drum bubble
stream of bed State is boiling burning State, bed within formed by bubble phase and emulsion
phase composed of two-phase State, has obviously of bed layer demarcation surface; slugging bed
State is a not normal of stream state of State, its features is bed layer in the bubble aggregate grew
up, then caused bubble layer of rupture, such cycle, caused bed laminated drop very not stable,
actual application in the should as avoid slugging bed State of appeared; Dang stream of speed
enough big Shi, Boiler (CFB boilers) bed reduces pressure fluctuations and tend to be relatively
steady, turbulent bed bed into State, characterized by bubbles in bed size is no longer with the
increase of the flow rate and the aggregate grew up, but increasing number and density of the
bubbles. Bed layer interface fuzzy, furnace within formed upper solid particles concentration small
of dilute phase district and lower particles concentration big of key phase district; Dang stream of
speed is greater than particles with out speed Shi, large particles was with out combustion
chamber, and as airflow speed of increased, particles with out volume also increases, can said
particles and airflow almost all full has throughout furnace space, furnace upper and lower of
particles concentration difference significantly reduces, bed within particles of within cycle rate is
high. In order to maintain the fast bed status, must take the air out of the separate particles,
collected them, circular movements then returned to bed quickly, that's circulating fluidized bed
boilers (CFB boilers). Therefore effective in circulating fluidized bed combustion process to be
completed, except for fluidized bed furnace, combustion needs of distributor and main combustion
equipment such as air chambers, a separator and devices that require high efficiency.

2. The circulatory system is made up of the furnace of CFB boilers, separators, risers and feeders and
other parts of the back, this system can fly out of the furnace of thick combustible solids through
separator and trap down, hearth via risers, back valve, Figure 2-18 shows a work flow diagram of
the circulatory system. Seen from the figure, after coal by coal into the furnace, part of which in
the dense-phase zone combustion, another part with the air flow upward and into the separator.
Furnace combustion of a highly dilute phase can be divided into the dense-phase zone of
combustion and combustion.
Enter the separator material with the fluid up into the separator in two parts of the coal-fired ones
and circulating materials, recycle items are to be considered through the hearth burning weight
loss. The air required for combustion from the wind and the air distributor plate into the boiler
(CFB boilers) furnace burned generates flue gases from the furnace after the separator from the
circulatory system. Steady state there is always a certain amount of material flows in the system,
the system will be in the cycle running.
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