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Pulverized Coal Injection Systems
Ironmaking
Pulverized Coal Injection
2
Coal Preparation and Pulverized Coal InjectionEquipment in Main Structure
MAINBAGFILTERS
RAW COALSTORAGE BIN
VERTICALROLLER MILL
CONVEYING(INJECTION)
HOPPERS
PULVERIZEDCOAL STORAGE
BIN
STORAGE BINBAGFILTERS
PRESSURIZINGGAS VESSELS
DRYING GASMAIN FANS
DRYING GASGENERATORS
3
MAINBAGFILTERS
PRESSURIZINGGAS VESSEL
DRYING GASMAIN FAN
VERTICALROLLER MILL CONVEYING
(INJECTION)HOPPERS
STORAGE BINBAGFILTERS
EMERGENCYINERTIZING GAS
VESSELS
RAW COALSTORAGE BIN
DRYING GASGENERATOR
PULVERIZEDCOAL STORAGE
BIN
Pulverized Coal Injection
4
Grinding and Drying of Coal in Inert Conditions
Blast Furnace Gas Based Drying
Blast Furnace Gas Based Drying, Dilution Air
Drying energy supply based on blast furnace gas combustion.
Inert conditions produced by closed loop circulation of waste drying gas as a dilution gas for drying gas temperature control (self inertizing process).
High dew point in drying gas due to waste drying gas recirculation.
Drying energy supply based on blast furnace gas combustion.
Inert conditions produced by closed loop circulation of waste drying gas as a dilution gas for drying gas temperature control (self inertizing process).
Dew point in drying gas lowered by means of cold dilution air injection up to the oxygen limit value for inert conditions.
COMBUSTION
AIR FAN
HIGH CALORIFIC
POWER GAS
BLAST FURNACE GAS
DRYING GAS
GENERATOR
VERTICAL
ROLLER MILL
DYNAMIC
CLASSIFIER
MILL CHARGING
CONVEYOR
RAW COAL
STORAGE BIN
SIEVING MACHINE
ROTARY VALVE
MAIN BAGFILTERRAW COAL
SUPPLY CONVEYOR
DRYING GAS
MAIN FAN
DRYING GAS
MAIN FAN
RAW COAL
SUPPLY CONVEYOR
RAW COAL
STORAGE BIN
MILL CHARGING
CONVEYOR
DYNAMIC
CLASSIFIER
COMBUSTION
AIR FAN
HIGH CALORIFIC
POWER GAS
BLAST FURNACE GAS
DRYING GAS
GENERATOR
VERTICAL
ROLLER MILL
MAIN BAGFILTER
ROTARY VALVE
SIEVING MACHINE
DILUTION AIR FAN
5
Blast Furnace Gas Based Drying, Condenser
Stove Waste Gas Based Drying
Drying energy supply based on blast furnace
gas combustion.
Inert conditions produced by closed loop circulation of waste drying gas as a
dilution gas for drying gas temperature control (self
inertizing process).
Dew point in drying gas lowered by means of
water vapor condensation in a spray cooler.
Drying energy supply based
on inert stove waste gas,
complemen-tary on blast furnace gas combustion.
Low dew point due to stove waste gas and little or no waste
drying gas recirculation.
DRYING GAS
MAIN FAN
RAW COAL
SUPPLY CONVEYOR
RAW COAL
STORAGE BIN
MILL CHARGING
CONVEYOR
DYNAMIC
CLASSIFIER
COMBUSTION
AIR FAN
HIGH CALORIFIC
POWER GAS
BLAST FURNACE GAS
DRYING GAS
GENERATORVERTICAL
ROLLER MILL
MAIN BAGFILTER
ROTARY VALVE
SIEVING MACHINE
COOLING
WATER
SPRAY COOLER FOR
WASTE DRYING GAS
RAW COAL
SUPPLY CONVEYOR
RAW COAL
STORAGE BIN
MILL CHARGING
CONVEYOR
DYNAMIC
CLASSIFIER
COMBUSTION
AIR FAN
HIGH CALORIFIC
POWER GAS
BLAST FURNACE GAS
DRYING GAS
GENERATOR
VERTICAL
ROLLER MILL
MAIN BAGFILTER
ROTARY VALVE
SIEVING MACHINE
HOT BLAST
STOVE PLANT
STOVE WASTE
GAS FAN
DRYING GAS
MAIN FAN
Pulverized Coal Injection
FT
FT
FC FYFC FY
WT
PC
WT
PC PC
WT WTFS
FSFC
FY FT
FT
FT
WT
FC FY FC FY
FC
FC FC
WT WT
FC
FY FT
6
Unit Operations of Pulverized Coal Injection
PRESSURIZING
GAS VESSEL
NITROGEN
GLOBAL
FLOW RATE
CLOSED LOOP
CONTROL
CONVEYING
HOPPERS
STATIC
DISTRIBUTOR
INJECTION
LINES
PULVERIZED
COAL TUYERES
CONVEYING
LINE
CLOSED LOOP CONTROL)
INDIVIDUAL FLOW RATE
(may be replaced by
NITROGEN
PRESSURIZING
GAS VESSEL
CONTROL
EQUIPMENT
INJECTION
LINES
DISTRIBUTION
HOPPER
PRESSURIZED
BAGFILTER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
CONVEYING
HOPPERS
CONVEYING
NITROGEN
GLOBAL
CLOSED LOOP
CONTROL
FLOW RATE
INJECTION
PRESSURIZING
GAS VESSEL
COMPRESSED AIR
LOCK AND
WEIGHING HOPPER
NITROGEN
DISTRIBUTION
HOPPER
INDIVIDUAL
FLOW RATE
CONTROL
LINES
LINE
FT
FT
FC FYFC FY
WT
PC
WT
PC PC
WT WTFS
FSFC
FY FT
FT
FT
WT
FC FY FC FY
FC
FC FC
WT WT
FC
FY FT
7
Metering
Global pulverized flow supplied to the Blast Furnace as well as individual flows supplied to the hot blast tuyeres shall be controlled. Flow rate control may be of• closedlooptypeor• statictype(onlyforindividualflows).
Distribution
Global flow rate to be injected has to be split up onto the hot blast tuyeres by means of a Distribu-tion Device. Distribution Device may contain• apuverizedcoalbuffervolume(HoppertypeDis-
tribution Device) or• nopulverizedcoalbuffervolume(Splittertype
Distribution Device).
Inward Transfer
Hot blast backpressure as well as pressure drops in pneumatic conveying lines and flow rate control devices require a pressurizing of pulverized coal from atmosphere pressure level to overpressure level.
After pressurizing, pulverized coal is transferred into a Distribution Device. Transfer may be • bygravityor• bypneumaticconveying.
Pneumatic Conveying
Pneumatic transfer of pulverized coal into the Dis-tribution Device as well as conveying of individual flows from the Distribution Device into the hot blast tuyeres are performed by means of pneumatic con-veying.
Pneumatic conveying may be of• thedensephasetypeor• thedilutephasetype.
The pulverized coal injection technology is based on a combination of several unit operations.Main unit operations include:
Pulverized Coal Injection
PC PC
WT WT
FS
FSFC
FY FT
FT
FT
FC FYFC FY
WT
PC
WT
PC
WT
FT
FT
WT
FC FY FC FY
FC
FT
FT
WT
FC FY FC FY
FC
FC FC
WT WT
FC
FY FT
8
Basic Combinaisons of Inward Transfer and DistributionTransfer without Pressurizing Gas Recovery
Transfer by Gravity Transfer by Pneumatic Conveying
Continuous transfer into a Splitter type Distribution Device
Discontinuous transfer into a Hopper type Distribution Device
Continuous transfer into a Hopper type Distribution Device
GLOBAL
FLOW RATE
CLOSED LOOP
CONTROL
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
STATIC
DISTRIBUTOR
INJECTION
LINES
PULVERIZED
COAL TUYERES
CONVEYING
LINE
CLOSED LOOP CONTROL)
INDIVIDUAL FLOW RATE
(MAY BE REPLACED BY
INJECTION
PRESSURIZING
GAS VESSEL
COMPRESSED AIR
LOCK AND
WEIGHING HOPPER
NITROGEN
DISTRIBUTION
HOPPER
INDIVIDUAL
FLOW RATE
CONTROL
LINES
CONVEYING
LINE
CONTROL
EQUIPMENT
INJECTION
LINES
DISTRIBUTION
HOPPER
PRESSURIZED
BAGFILTER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
NITROGEN
NITROGEN
PRESSURIZING
GAS VESSEL
CONVEYING
HOPPER
CONTROL
EQUIPMENT
INJECTION
LINES
DISTRIBUTION
HOPPER
PRESSURIZED
BAGFILTER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
CONVEYING
HOPPERS
NITROGEN
CONVEYING
LINE NITROGEN
PRESSURIZING
GAS VESSEL
GLOBAL
CLOSED LOOP
CONTROL
FLOW RATE
FYFC
FC FY
FT
FT
PC
WT
PC
WT
PC
WT
FC
FY FT
WT WT
FT
FT
FC FYFC FY
WT
PC
FT
FT
WT
FC FY FC FY
FC
FC FC
WT WT
FT
FT
WT
FC FY FC FY
FC
FC
FY FT
PC
WT
PC
WT
PC
WT
9
Continuous transfer into a Splitter type Distribution Device
Discontinuous transfer into a Hopper type Distribution Device
Continuous transfer into a Hopper type Distribution Device
Transfer with Pressurizing Gas Recovery by means of Pressure Equalizing between parallel Hoppers
Transfer by Gravity Transfer by Pneumatic Conveying
CONVEYING
LINE
STATIC
DISTRIBUTOR
INJECTION
LINES
CONTROL
EQUIPMENT
GLOBAL
CLOSED LOOP
CONTROL
CONTROL
EQUIPMENT
FLOW RATE
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
COAL DISTRIBUTION)
STATIC PULVERIZED
(MAY BE REPLACED BY
INJECTION
INDIVIDUAL
FLOW RATE
CONTROL
LINES
PRESSURIZING
GAS VESSEL
PARALLEL LOCK
AND WEIGHING
NITROGEN
DISTRIBUTION
HOPPER
HOPPERS
CONTROL
EQUIPMENT
INJECTION
LINES
DISTRIBUTION
HOPPER
PRESSURIZED
BAGFILTER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
CONVEYING
HOPPERS
NITROGEN
CONVEYING
LINE NITROGEN
PRESSURIZING
GAS VESSEL
CONTROL
EQUIPMENT
INJECTION
LINES
DISTRIBUTION
HOPPER
PRESSURIZED
BAGFILTER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
NITROGEN
GLOBAL
CLOSED LOOP
CONTROL
FLOW RATE
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
CONVEYING
LINE
Pulverized Coal Injection
10
Inward Transfer
Sequences of Parallel Conveying HoppersSequences of two Con-veying Hoppers, operated without pressurizing gas recovery
Sequences linked by• continuoustransferof
pulverized coal to the Distribution Device
Sequences of three Convey-ing Hoppers, operated with pressurizing gas recovery.
Sequences linked by• continuoustransferof
pulverized coal to the Distribution Device
• pressurebalancingbetween Conveying Hop-pers for pressurizing gas recovery.
Sequences of three Con-veying Hoppers, operated without pressurizing gas recovery.
Sequences linked by• continuoustransferof
pulverized coal to the Distribution Device.
SURIZING
PRESSURE
WEIGHT
PRESSURE
WEIGHT
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES- PRESSU-
RIZING
TIME
FILLINGINJECTION INJECTION
FILLINGINJECTIONFILLING
CONVEYING
HOPPER '1'
CONVEYING
HOPPER '2'
HOPPER '3’
WEIGHING PE FPDE DEPRES-SURIZING
DE : DEPRESSURIZING by PRESSURE EQUALIZING
PE : PRESSURIZING by PRESSURE EQUALIZING
FP : FINAL PRESSURIZING
PRESSURE
WEIGHT
PRESSURE
WEIGHT
PRESSURE
WEIGHT
TIME
WEIGHINGDE DEPRES-SURIZING
WEIGHING PE FPDE DEPRES-SURIZING
PE FP
WEIGHING PE FPDE DEPRES-SURIZING
INJECTIONFILLING FILLING
INJECTION FILLING
INJECTIONFILLINGINJECTION
CONVEYING
HOPPER '1'
CONVEYING
HOPPER '2'
CONVEYING
PRESSURE
WEIGHT
PRESSURE
WEIGHT
PRESSURE
WEIGHT
TIME
INJECTIONINJECTION
INJECTIONINJECTION
INJECTIONINJECTION
DEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
WEIGHINGDEPRES-
SURIZING
PRESSU-
RIZING
FILLINGFILLING
FILLING
FILLINGFILLING
FILLING
CONVEYING
HOPPER '1'
CONVEYING
HOPPER '2'
CONVEYING
HOPPER '3’
FT
FT
FC FYFC FY
WT
PC
WT
PC PC
WT WT
FS
FSFC
FY FT
11
Transfer by Gravity - Advantages• Largertransferflowratesobtainable.• Loweroperatinganddesignpressurelevels.• Lessprocessgasrequirement.• Nopneumaticconveyingequipmentrequired.
Transfer by Gravity - Disadvantages• Transferflowratestronglyconditionedby
flowability of pressurized pulverized coal.• Largerheightofequipmentarrangement.• Moreequipmentinstalledclosetoblastfur-
nace.
Transfer by Pneumatic Conveying - Advantages
• Transferflowratelessconditionedbyflowabilityofpressurizedpulverized coal.
• DirectGlobalFlowRateControlpossibleincaseofcontinuoustransfer.• Lowerheightofequimentarrangement.• LessequipmentinstalledclosetoBlastFurnace.
Transfer by Pneumatic Conveying - Disadvantages• Transferflowratesbasicallysmaller.• Higheroperatinganddesignpressurelevels.• Largerprocessgasrequirement.
Gravity Transfer versus Pneumatic Transfer
GLOBAL
FLOW RATE
CLOSED LOOP
CONTROL
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
STATIC
DISTRIBUTOR
INJECTION
LINES
PULVERIZED
COAL TUYERES
CONVEYING
LINE
CLOSED LOOP CONTROL)
INDIVIDUAL FLOW RATE
(MAY BE REPLACED BY
INJECTION
PRESSURIZING
GAS VESSEL
COMPRESSED AIR
LOCK AND
WEIGHING HOPPER
NITROGEN
DISTRIBUTION
HOPPER
INDIVIDUAL
FLOW RATE
CONTROL
LINES
Pulverized Coal Injection
12
Distribution
Splitter Type Distribution Device
Distribution Splitter at ArcelorMittal Gijón BF ’A’ & ’B’
Distribution structure at Cockerill Sambre Seraing BF ‘6’
Splitter Type Distribution Device - Advan-tages• Directglobalflowratecontrolpossibleinthe
upstream Conveying Line.• Reducedspacerequirementforequipment.• Reducedscopeofequipment.
Splitter Type Distribution Device - Disadvan-tages
• Individualflowratecontrolindownstreamindivid-ual Injection Lines less efficient.
• Largerconveyinggasinputintoblastfurnace.
13
Hopper Type Distribution Device
Distribution Hopper at ROGESA Dillingen BF ‘5’
Hopper Type Distribution Device - Advantages
• Nomutualdisturbingofoperationofdownstream individual Injec-tion Lines.
•Maximumaccuracyofindividualflowratecontrolindownstreamindividual Injection Lines.
•Minimumconveyinggasinputintoblastfurnace.
Hopper Type Distribution Device - Disadvantages
• Efficientdirectglobalflowratecontroldifficult.• Slightlyincreasedprocessgasrequirement,causedbysecond
fluidizing of pulverized coal at the inlets of the downstream indi-vidual Injection Lines.
• Largerspacerequirementforequipment.• Largerscopeofequipment.
Pulverized Coal Injection
e-T
dW / dt
WY WT
PT
e-T
W(t+dt) - W(t)
X X
Int
Div
SumWY WT
PT
ST
DT
ET ST
DT
ET
e-T
dW / dt
WT
PT
WY
e-T
W(t+dt) - W(t)
X
Int
Div
WT
PT
WY
ST
DT
ET
14
MeteringDeterminingofPulverizedCoalFlowRate
By Means of Weighing System of Lock or Distribution Hopper:
• Indirectflowratedeterminingbasedonweightdifferencesdivided by time interval durations.
• Givesabsolutevalues[kg/s].• Quickerresponsereducesaccuracyandvice-versa.• OnlygivesvalueoftotalflowratesuppliedbyHopper.
ByMeansofCorrelativeFlowRateMeasurementDevicein Coal Conveying Line:
• Directdeterminingofrelativeflowratevalueincoalconveyingline.
• Givesrelativevalues[mA].• Requiressecondlevelweighingsystemforturningrelativevalues[mA]intoabsolutevalues[kg/s].
• Quickerresponsethanweighingsystembasedflowratedeter-mining.
• Givesindividualflowratevaluesinmultiple parallel lines.
DISTRIBUTION
HOPPER
ABSOLUTE FLOW RATE
ABSOLUTE FLOW RATES
CONVEYING
HOPPER
ABSOLUTE FLOW RATE
ABSOLUTE FLOW RATE
PT PT
15
FactorsDeterminingPulverizedCoalFlowRateinLine
FixedValueFactors,maybeusedinStaticFlowRateControl:
• Length,routingofline.• Innerdiameterofline.• Singlestaticflowresistance
(e.g. orifice, tuyere with sub-critical expansion).• Criticalexpansiondevice
(tuyere with critical expansion).
Variable Value Factors, may be used in Closed Loop Flow RateControl:
• Lineinletpressurelevel.• (Lineoutletpressurelevel).• Conveyinggasflowrate.• Singlevariableflowresistance
(mechanical flow control valve).• Externalflowratedeterminingdevice
(e.g. variable speed rotary valve).
FIXED VALUE FACTORS CONDITIONING
CONVEYING FLOW RATE
- LENGTH OF LINE
- ROUTING OF LINE
- INNER DIAMETER OF LINE
- SINGLE STATIC RESISTANCE
- CRITICAL EXPANSION TUYERE
VARIABLE VALUE FACTORS CONDITIONING
CONVEYING FLOW RATE
- LINE INLET PRESSURE
- LINE OUTLET PRESSURE
- CONVEYING GAS FLOW RATE
- SINGLE VARIABLE RESISTANCE
Pulverized Coal Injection
FLOW RATE CONTROLMETHOD
Diameter balanced flowresistances of Lines
Equalized flow resistanceof Lines (length, bends)
Equalized flow resistanceplus Subcritical Tuyeres
Critical Expansion Tuyeresin (arbitrary) Lines
DISTRIBUTIONPATTERN
Uniform, fixed
Uniform, fixed
Uniform, fixed
Arbitrary,may be changed
PRESSURE LOSSDUE TO CONTROL
none
none
About 1 - 2 bar
P > P * 1.65in out
ACCURACY
4 %
i n c
r e
a s
i n
g
1
2
3
4
1 2
3 4
16
Static Flow Rate Control
MeansofStaticFlowRateControl
EQUAL DISTRIBUTION BY DIAMETER BALANCED LINES EQUAL DISTRIBUTION BY LENGTH BALANCED LINES
EQUAL DISTRIBUTION BY LENGTH BALANCED LINES AND SUBCRITICAL TUYERES FLOW CONTROL BY CRITICAL EXPANSION TUYERES
SUBCRITICAL EXPANSION TUYERE
DIAMETER INCREASE BALANCED LINE LENGTH
BALANCED LINE LENGTH CRITICAL EXPANSION TUYERE
Metering
6 7 8 9 10 11 12 7 8 9 10 11 12 13
0 10 20 30 40 50 60 70
[bar a] [kg/nm ]3
[m/s]
5
0 10 20 30 40 50 60 70 80 90 100
0
2
4
6
8
10
12
14
16
18
20
[bar a]
# 1 # 2 # 3 # 4 # 5
17
Static Flow Rate Control by Critical Expansion Tuyeres
Acceleration requires gas pressure decrease and causes gas density decrease. Decreases in conver-gent nozzle are limited to critical values. In critical conditions, flow rate is only determined by pressure and density upstream of nozzle and by nozzle minimum cross section area.
Pressure drops due to critical expansion are minimized in an “optimum” tuyere, the variable minimum cross section fitting exactly with any flow rate requested. Actually, flow rate range is split into few subranges, each having a tuyere exactly fitting with the lowest flow rate in the subrange.
GAS PRESSURE
MEAN VELOCITYOF MIXTURE
GAS DENSITY
Pin / Pmin = 1.65
CRITICAL
EXPANSION
TUYERE
FOR
COAL
GAS
MIX-
TURE
INJECTIONFLOW RATE [%]
PRESSURE LEVEL
CONVEYINGHOPPER
CONVEYINGLINE
STATICDISTRIBUTOR
CRITICALEXPANSIONTUYERE
INJECTIONLINE
CRITICAL EXPANSION
ACTUAL TUYERE INLET
CONVEYING HOPPER
HOT BLAST TUYERE
(maximum pressure level)
OPTIMUM (variable cross
section) TUYERE INLET
CRITICAL EXPANSION TUYERE SIZE
SHORT LINE TUYERE OUTLET
LONG LINE TUYERE OUTLET
Pulverized Coal Injection
18
MeteringStatic Flow Rate Control
StaticFlowRateControlbymeansofInjectionLineswithequalizedflowresistancepluspulverizedcoaltuyereswithsubcriticalexpansion.Onlyproducesuniformdistribution.
StaticFlowRateControlbymeansofpulverizedcoaltuyereswithcriticalexpansioninstalledinInjec-tion Lines with various line length. May produce uniform distribution as well as arbitrary distribution patterns.
FLOW RATEDETERMINING
Weighing Systemon Hopper
Flow RateMeasurementDevice in Line
Weighing Systemon Hopper
Flow RateMeasurementDevice in Line
Weighing Systemon Hopper
Flow RateMeasurementDevice in Line
PRESSURE LOSSDUE TO CONTROL
none
none
none
none
1 - 2 bar
1 - 2 bar
FLOW RATE CONTROLMETHOD
Pressure Variationin Hopper
(Global Flow only)
Pressure Variationin Hopper
(Global Flow only)
Dilution GasInjection into
Conveying Line
Dilution Gas Injection intoConveying orInjection Line
Coal Flow RateControl Valve
in Conveying Line
Coal Flow Rate Con-trol Valve in Convey-ing or Injection Line
ACCURACY(approximately)
2 - 4 %
2 - 4 %
2 - 3 %
1 - 2 %
2 - 3 %
1 - 2 % (Conv.)or
0.5 - 1 % (Injec.)
19
Closed Loop Flow Rate Control
Depressurizing control valve used in hopper pressure control Coal Flow Rate Control Valve for Conveying Line (Global Flow Rate Control)
MeansofClosedLoopFlowRateControl
Pulverized Coal Injection
20
Closed Loop Flow Rate Control
Coal Flow Rate Measurement Devices in Injection Lines, downstream of Coal Flow Rate Control Valves installed beneath the Distribution Hopper at ArcelorMittal Gijón BF ’A’ & ’B’
Coal Flow Rate Control Valves installed beneath the Distribution Hopper at Rogesa Dillingen BF ‘5’
Coal Flow Rate Control Valves installed downstream of Splitter type Distribution Device at ArcelorMittal Gijón BF ’A’ & ’B’
Metering
PULVERIZEDCOAL STORAGE
BIN
LOCK ANDWEIGHING
HOPPER
DISTRIBUTIONHOPPER
COAL FLOWRATE CONTROL
VALVES
PRESSURIZINGGAS VESSELS
COAL FLOWRATE MEASUREMENT
DEVICES
INJECTIONLINES
21
Closed Loop Flow Rate Control
Injection Structure at Rogesa Dillingen BF ‘5’
Pulverized Coal Injection
t
Ho
Hm
ax
H Ho
H(t)
22
Pneumatic ConveyingDense Phase Pneumatic Conveying
Pulverized coal has outstanding fluidizability and gas retaining characteristics. These are the basis for dense phase pneumatic conveying of pulverized coal in fluidized state.
Fluidizing of pulverized coal is performed in fluid-izing compartments connected to the coal outlet nozzles of the Conveying Hoppers or Distribution Hopper.
Pulverized coal may also be conveyed in conven-tional dilute phase conveying.
Fluidizing Compartment below a Conveying Hopper at Cockerill Sambre Seraing BF ‘6’ (upward coal flow)
Fluidizing Compartments below the Distribution Hopper at Rogesa Dillingen BF ‘5’ (downward coal flows)
SOLID MATERIAL SUPPLYand PRESSURE MAINTAINING
FLUIDIZING GAS INPUT
NO FLOW
DISCHARGINGFLUIDIZED BED
FLUIDIZING
DISCHARGING
DEVIATION
GAS VELOCITY
SOLID MATERIALVELOCITY
TIME
NOFLOW
FLUIDIZING DEGASSING NOFLOW
FLUIDIZING GAS
(CONSTANT FLOW RATE)
MATERIAL HEIGHT
FLUIDIZINGTIME
GAS RETEN-TION TIME
0 2 4 6 8 10 12 14 16 18 20
0
10
20
30
40
50
60
70
80
90
[kg/kg]
[bar a]
95 %
90 %
80 %
70 %
60 %
23
Dilute Phase Conveying versus Dense Phase Conveying
Load in pneumatic dense phase conveying (ratio of solid flow rate to gas flow rate) is conditioned by the pressure level existing in the fluidizing device upstream of the coal conveying line.
Dense Phase Pneumatic Conveying Line at Sollac Fos-sur-Mer BF ‘2’
VOID
DILUTE PHASE CONVEYING
DENSE PHASE CONVEYING
PULVERIZED COAL PARTICLE
CONVEYING GAS
GAS MEAN VELOCITY
SOLID MATERIALMEAN VELOCITY
PULVERIZED COAL PARTICLE
CONVEYING GAS
GAS MEAN VELOCITY
SOLID MATERIALMEAN VELOCITY
SOLID TO GAS RATIO (LOAD)
PRESSURE
Pulverized Coal Injection
24
Dilute Phase Conveying versus Dense Phase Conveying
DILUTEPHASECONVEYING
High solid material velocity, requiring
• abrasionprotectioninbends.
Low ratio of solid material flow rate to conveying gas flow rate in coal conveying line, meaning
• higherconveyinggasrequirement (conditioned by void).
More pneumatic energy in conveying gas per solid material unit mass, meaning
• lowerpressuredropincoalconveyingline
• lowerpressurelevel,lesspressurizinggasandless pressure maintaining gas required in Con-veying Hopper.
Design criteria: solid material velocity > minimum velo city, meaning
• conveyinggasflowrateconstantwhensolidmaterial flow rate is decreasing
• specificconveyinggasrequirementisincreas-ing with decreasing solid material flow rate
• turn-downratioofconveyingflowrateisunlim-ited.
Transportability is based on action of gas turbu-lence on individual solid particle, meaning
• conveyingislessconditionedbybulksolidmaterial properties
• conveyingislesssensitive.
DENSEPHASECONVEYING
Low solid material velocity, requiring
• noabrasionprotectioninbends.
High ratio of solid material flow rate to conveying gas flow rate in coal conveying line, meaning
• lowerconveyinggasrequirement (conditioned by line inlet pressure).
Less pneumatic energy in conveyinggas per solid material unit mass, meaning
• higherpressuredropincoalconveyingline
• higherpressurelevel,morepressurizinggasand more pressure maintaining gas required in Conveying Hopper.
Design criteria: conveying time duration (travel-ling time) < maximum possible duration, meaning
• conveyinggasflowrateisdecreasingwithsolid material flow rate
• specificconveyinggasrequirementisnearlyconstant, independently of solid material flow rate
• conveyingdistanceandturn-downratioofcon-veying flow rate are limited.
Transportability is based on fluidizing ofbulk solid material, meaning
• conveyingismoreconditionedbybulksolidmaterial properties (fluidizability, flowability, gas retaining capacity)
• conveyingismoresensitive.
Pneumatic Conveying
25
Dense Phase Pneumatic Conveying
Main Structure of PCI-System at Cockerill Sambre Charleroi
BF ‘4’ and BF ‘5’
Conveying of pulverized coal from the PCI-System
Main Structure to Cockerill Sambre Charleroi BF ‘4’, total conveying distance
about 1000 m
Pulverized Coal Injection
PC
WT
PC
WT
PC
WT
FC
FY FTFT
FT
WT
FC FY FC FY
FC
FT
FT
FYFC
FYFC
PC
WT
PC
WT
PC
WT
FC
FY FT
PC
WT
PC
WT
PC
WT
FC
FY FT
FS
FS
26
Preheating of Pulverized CoalPreheating and Injection Equipment Arrangement
Pulverized coal is pre-heated in the Conveying Line upstream of the Distribution Hopper.
Residualmoistureisseparated in the Distri-bution Hopper.
Preheating and Degassing of Pulverized Coal
Preheating of Pulverized Coal
Pulverized coal is pre-heated in the Conveying Line upstream of the Splitter type Distribu-tion Device.
Closed loop individual injection flow rate con-trol is performed down-stream of the Splitter type Distribution Device.
Pulverized coal is pre-heated in the Conveying Line upstream of the Splitter type Distribu-tion Device.
Static individual flow rate control is per-formed down stream of the Splitter type Distri-bution Device.
Preheating of Pulverized Coal
GLOBAL
CLOSED LOOP
CONTROL
FLOW RATE
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
HEATING
FLUID
CONTROL
EQUIPMENT
INJECTION
LINES
DISTRIBUTION
HOPPER
PRESSURIZED
BAGFILTER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
NITROGEN
HEAT
EXCHANGER
INDIVIDUAL
FLOW RATE
CLOSED LOOP
CONTROL
CONTROL
EQUIPMENT
INJECTION
LINES
GLOBAL
CLOSED LOOP
CONTROL
FLOW RATE
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
HEAT
EXCHANGER
HEATING
FLUID
STATIC
DISTRIBUTOR
CONTROL
EQUIPMENTCONVEYING
LINE
CONVEYING
LINE
HEAT
EXCHANGER
HEATING
FLUID
CONTROL
EQUIPMENT
GLOBAL
CLOSED LOOP
CONTROL
FLOW RATE
PRESSURIZING
GAS VESSEL
NITROGEN
CONVEYING
HOPPERS
STATIC
DISTRIBUTOR
INJECTION
LINES
PULVERIZED
COAL TUYERES
STATIC
PULVERIZED COAL
DISTRIBUTION
27
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VINCOTTE
ISO 9001ISO 14001
BUREAU VERITASCertification
N° BXL 05000141 / N° BEL BXL 153669
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