Fluidized Bed Combustion

Question 1

State the abbreviation used for fluidized bed combustion.

a) FC
b) FBCB
c) FBC
d) FBBC
e) FB

Answer 1

c) FBC

Question 2

The abbreviation FGD stands for

a) flue gas desulphurization
b) fuel gauge diameter
c) flow gas density
d) fluid gas detector

Answer 2

a) flue gas desulphurization

Question 3

State the abbreviation for a “fluid catalytic cracker”.

a) CC
b) FC
c) FCCB
d) CFC
e) FCC

Answer 3

e) FCC

Question 4

FCC, with regard to the refining industry means

a) Federal Communications Commission
b) Fresh condensate control
c) Fluid catalytic cracker
d) Federated consumer costs
e) Fuel Combustion Code

Answer 4

c) Fluid catalytic cracker

Question 5

AFBC stands for

a) Alberta/Federal boiler calculations
b) Alberta foot board control
c) after-fired boiler circuitry
d) atmospheric fluidized bed combustion
e) automatically flooded boiler condenser

Answer 5

d) atmospheric fluidized bed combustion

Question 6

PFBC stands for

a) Provincial/Federal boiler calculations
b) Provincial footboard control
c) pre-fired boiler circuitry
d) petroleum fired boiler control
e) pressurized fluidized bed combustion

Answer 6

d) petroleum fired boiler control

Question 7

With the AFBC, the combustion air pressure is typically
25 cm of water pressure at the FD fan,16 cm at
the base of the active bed, and _______________ at the
top of the combustion mass.
a) at boiler pressure
b) at flue gas exit temperature
c) negative pressure
d) atmospheric pressure
e) absolute pressure

Answer 7

d) atmospheric pressure

Question 8

With the AFBC, the three pressure zones are typically as
follows at the FD fan, the base of the active bed, and at
the top of the combustion mass respectively.
a) 25 cm of water pressure, 16 cm and atmospheric
b) 20 cm of water pressure, 14 cm and atmospheric
c) 15 cm of water pressure, 10 cm and below atmospheric
d) 30 cm of water pressure, 20 cm and above atmospheric
e) 40 cm of water pressure, 25 cm and above atmospheric

Answer 8

a) 25 cm of water pressure, 16 cm and atmospheric

Question 9

In FBC, the fuel content by mass of the turbulent inert
material is usually less than
a) 5 percent
b) 3 percent
c) 2 percent
d) 4 percent
e) 1 percent

Answer 9

c) 2 percent

Question 10

AFBC units permit the reduction of furnace temperatures from

a) 1600 to 850 degrees Celsius
b) 1800 to 650 degrees Celsius
c) 1700 to 750 degrees Celsius
d) 1550 to 900 degrees Celsius
e) 1350 to 500 degrees Celsius

Answer 10

a) 1600 to 850 degrees Celsius

Question 11

Reducing furnace bed temperatures by use of AFBC units reduces
as well
a) production of hot flue gases
b) efficiency of operation
c) production of NOx’s
d) the turbulence of the furnace interior
e) the steam generating capacity

Answer 11

c) production of NOx’s

Question 12

Crushed coal mixed with pulverized limestone in an AFBC unit
does what?
a) lower the combustion bed temperature
b) act as a desulphuring agent
c) create the perfect fuel; hydrogen
d) pressurizes the fluidized bed
e) produces no gaseous effluent

Answer 12

b) act as a desulphuring agent

Question 13

What is the percentage of SOx reduction which can be gained
by adding an excess amount of limestone to the bed of an
AFBC unit?
a) 40 - 50 percent
b) 50 - 65 percent
c) 70 - 80 percent
d) 80 - 90 percent
e) 90 - 95 percent

Answer 13

d) 80 - 90 percent

Question 14

About the only thing limiting the kind of fuel burned in a
FBC is
a) how well the material has been mixed prior to burning
b) the heating value of the material being burned
c) the amount of slag the fuel will produce
d) the size of the plant using the fuel
e) the size of the burners

Answer 14

b) the heating value of the material being burned

Question 15

The gradual loss of the fluidized bed in an FBC furnace is
called
a) attrition
b) fluidation
c) carryover
d) reduction
e) starving

Answer 15

c) carryover

Question 16

The ash content of a fuel which can be burned in a FBC unit
and which will not burn successfully in any other type of
furnace is
a) 10 percent
b) 30 percent
c) 55 percent
d) 60 percent
e) 70 percent

Answer 16

e) 70 percent

Question 17

Large “clinkers” are not produced in FBC furnaces because
of
a) lower furnace temperatures
b) the fluidized bed created by air passage through the furnace
c) the kind of fuel used
d) the introduction of limestone into the combustion mixture
e) not burning gaseous fuels

Answer 17

a) lower furnace temperatures

Question 18

The reason FBC plants can be built smaller than plants
currently in vogue is because of
a) higher steam temperatures and pressures
b) higher heat transfer rates and the absence of wet
exhaust gas scrubbing equipment
c) lower maintenance costs and the ability to burn a wide
variety of fuels
d) less slag production and the elimination of soot-
blowing equipment
e) the burners being smaller

Answer 18

b) higher heat transfer rates and the absence of wet

exhaust gas scrubbing equipment

Question 19

Steam generators of the FBC type can be reduced in size by
up to
a) 35 percent
b) 15 percent
c) 45 percent
d) 25 percent
e) 10 percent

Answer 19

d) 25 percent

Question 20

Because of the one quarter reduction in size of FBC plants a
significant saving is gained in
a) fuel and waste costs
b) material and construction costs
c) heat and light costs
d) "Clinker" and soot blowing costs
e) fuel storage costs

Answer 20

b) material and construction costs

Question 21

Feedthrough tubes are located?

a) in the furnace windbox
b) in the furnace ceiling
c) in the furnace walls
d) in the corners of the furnace
e) in the furnace bottom

Answer 21

e) in the furnace bottom

Question 22

An especially important point in the operation of fluidized
beds composed of fine particles is
a) feedwater temperature
b) solids injection rate
c) bubble size
d) waste solids handling
e) the colour of the limestone

Answer 22

c) bubble size

Question 23

Operating a PFBC furnace at low temperatures results in

a) the formation of “clinkers”
b) a restricted type of fuel used
c) the need for the installation of soot blowers
d) the generation of wet steam
e) steam temperature limited over the period of heat supply

Answer 23

e) steam temperature limited over the period of heat supply

Question 24

Carryover in FBC units results in
a) lower efficiency and higher costing dust collectors
b) lower furnace temperatures and the need for higher
furnace ceilings
c) lower tube location and higher combustion rates
d) lower steam pressures and higher water temperatures
e) overheating of the breeching

Answer 24

a) lower efficiency and higher costing dust collectors

Question 25

One way of increasing combustion control at low operating rates
in FBC units is to
a) add fuel gas to the combustion process
b) add more expensive control equipment
c) add hot steam to the fluidized bed
d) add an electrical charge to the pulverized limestone
e) close all the air dampers

Answer 25

b) add more expensive control equipment

Question 26

To what temperature must the inert bed material of a FBC unit
be heated before the introduction of coal to the furnace for
burning?
a) about 350 degrees Celsius
b) about 500 degrees Celsius
c) about 600 degrees Celsius
d) about 750 degrees Celsius
e) about 900 degrees Celsius

Answer 26

c) about 600 degrees Celsius

Question 27

What is the ignition temperature of coal?

a) 300 degrees Celsius
b) 450 degrees Celsius
c) 550 degrees Celsius
d) 600 degrees Celsius
e) 900 degrees Celsius

Answer 27

d) 600 degrees Celsius

Question 28

The typical time needed to heat a FBC unit bed to fuel ignition
temperature prior to the introduction of coal is
a) one hour
b) one half hour
c) two hours
d) three hours
e) six hours

Answer 28

a) one hour

Question 29

Due to various differences in the operation of FBC plants the
following is required:
a) a considerably larger floor space
b) better qualified operators
c) a taller furnace stack
d) using new technology in the construction of boiler tubes
e) a considerably different control system

Answer 29

e) a considerably different control system

Question 30

In order to get maximum heat transfer in a FBC furnace it is
required to
a) increase the fuel consumption per hour
b) ensure that the boiler tubes are covered by the expanded bed
c) build larger FBC’s
d) add fuel gas to the regular fuel being burned
e) line the floor and ceiling of the furnace with steel plates

Answer 30

b) ensure that the boiler tubes are covered by the expanded bed