collegeppt.ppt
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Transcript of collegeppt.ppt
MAIN PROJECT PRESENTATION
2012
THANGAL KUNJU MUSALIAR INSTITUTE OF TECHNOLOGY
THREE ELEMENT CONTROL ON DRUM
LEVEL USING EMBEDDED SYSTEMS
GUIDED BY PRESENTED BY
Mrs. BeenaRani B B Anju J [ 8406 ]
Lect. EI Dept. Arya M S [ 8412 ]
Devika S [ 8420 ]
Neethu Raj [ 8434 ]
Sibimol Luke [ 8449 ]
DONE AT
The Kerala Minerals and Metals Ltd.Chavara, Kollam
INTRODUCTION
Boiler is a steam generating unit.
AIM- Controlling water level in boiler drum.
3 control strategies :single element.
two element and
three-element control
3 element control implemented using embedded programmable
controller Yokogawa YS1700.
BOILER
A closed vessel made of steel in which water or other fluid is heated
to generate steam.
Slave plant or utility plant and it is maintained at negative pressure
Used to generate steam for doing mechanical work, heating,
producing vacuums, and augmenting chemical processes
An important variable to measure and control in a continuous
boiler is the level of water in the “steam drum”
This vessel’s primary function is to provide a surface area and
volume near the top of the boiler where separation of steam from
water can occur
WATER TUBE BOILER
• Used for high steam demand and pressure requirements
• Capacity range of 4,500 – 120,000 kg/hour
• Combustion efficiency enhanced by induced draft provisions
• Lower tolerance for water quality and needs water treatment plant
BOILER IN KMML
BOILER BLOCK DIAGRAM
DM WATER
TANKDEAERATOR ECONOMISER
BOILER
DRUM
STEAM
BOILER AIR SCHEME
AIR FD FAN DAMPER WIND BOX
BURNER
FLAME
OIL
BOILER FUEL SCHEME
OIL STORAGE
TANK
OIL HEATER
OIL CONTROL
VALVE
BURNER
DRUM LEVEL CONTROL
OBJECTIVE OF THE PROJECT
Operator adjustment of the set point.
Compensation for the shrink and swell effects.
Automatic control of drum level.
Bump less transfer between auto and manual modes.
Indication of drum level and steam flow.
Indication of feed water valve position and feed water flow.
Absolute/deviation alarms for drum level.
SINGLE ELEMENT CONTROL
PID CVMEASUREMENT
SET POINT
Single-Element control is the simplest strategy
Single element drum level control measures drum level only
This is a simple feedback control loop
Only one analogue input and one analogue output required
Can only be applied to single boiler / single feed pump configurations
with relatively stable loads since there is no relationship between drum
level and steam- or feed water flow
Possible inadequate control option because of the swell effect
During startup of a boiler, it is effective to use single-element control in
which the feed water controller is bypassed and the drum level
controller directly controls the feed water control valve
TWO ELEMENT CONTROL
15
LEVEL
PIDSET POINT
INFLOW
PID
CV
SET
PV PV
The two element control scheme utilizes steam flow in addition to drum
level
This is a simple feedback plus feed forward control system with a
secondary variable that has a predictable relationship with the
manipulated variable
The secondary variable, steam flow, causes the manipulated variable to
change the primary variable
Tighter control of drum level than with only one element
Steam flow acts as feed forward signal to allow faster level adjustments
Can best be applied to single boiler / single feed pump configurations
with a constant feed water pressure
THREE ELEMENT CONTROL
DRUM LEVEL
LAG
PIDSET
SAT FLOW
SUP FLOW
ADD
MATH
WATER FLOW
PV
PIDSET
PV
CV
Three element control utilizes steam and water flow in addition to
drum level
This is a simple feedback, feed forward, and cascade control loop.
The steam flow adjusts the feed water control valve based on the
steam flow signal and the drum level controller signal
The three-element system provides tighter control for drum level with
fluctuating steam load.
Ideal where a system suffers from fluctuating feed water pressure or
flow
More sophisticated level of control required
Additional input for feed water flow required
SCHEMATIC DIAGRAM
PERFORMANCE
Single element Two element Three element
APPLICATION CHART FOR DRUM LEVEL CONTROL SYSTEM
System Classification
Load Change Capabilities
Typical Applications
Magnitude Rate
Single-element Moderate Slow Institutional and industrial heating plantsSteady process conditions
Two-element Moderate Moderate Industrial plants with essentially continuous type processes and good feed water pressure regulation
Three-element Wide Fast Combination of batch and continuous type operations such that plant steam load characteristics varies continuously and usually unpredictably. Most industrial power applications fall into this category.
EMBEDDED SYSTEM
Embedded Systems is a special purpose computer system/board, which
encapsulates all the devices such as processor, memory, interface and
control in single package or board to perform only a specific application
tasks.
EXISTING CONTROLLER ‘BCE 760’
Single station ,single loop controllers having P, PI, PID functions.
LIMITATIONS
Dedicated registers. So it cannot be used for other purposes.
Lag cannot be provided directly.
No peer to peer communication.
It can do only one control action.
No graphical monitoring is possible.
Cannot be employed in emergency situations.
YOKOGAWA YS1700 PROGRAMABLE CONTROLLER
YS1700 is a programmable logic controller
Each YS1700 can run two PID control
algorithms, and the corresponding 4 ~
20mA output signal
YS1700 can also be used without
programming multi-function controller
The YS1700 Programmable Indicating
Controller includes over one-hundred
computation modules
RS-485 communication protocol for the
YS1000 series
FEATURES
Function block programming: GUI-based programming
method.
Large programming capacity.
More powerful control and calculation functions.
Function selection mode (needs no programming).
Expandable I/O.
Nonvolatile memory for memory backup.
Dual power supply.
YSS 1000 SOFTWARE BASIC OPERATION
FLOW CHART
START
READ DRUM LEVEL
READ SAT
FLOW
READ SUP
FLOW
READ FEED WATER FLOW
√ √X GAIN + BIAS
√
X GAIN + BIAS
X GAIN + BIAS
X GAIN + BIAS
DLC MODE = MANUAL SUM FIC
MODE = MANUAL
SUM - 50
C = A+B
MV = MAN O/P
SET = PV
PI ALGORITHM
FIC MODE =
AUTO
C = SET
PI ALGORITHM
MV = MAN O/PSET = PV
FW_CV END
YES
NO
YES
NO
NO
YES
PROGRAM
Program for Three Element Control
LD X4; drum level signal
LD P8; gain
*
LD P9; bias
+
ST T16;
LD P1; first order lag time in second
LAG 1
ST T1
ST Y2; retransmission drum level to recorder A02
LD X3; feed water flow signal
LD P10; gain
*
LD P11; bias
+
ST T2
ST P30; to display feed water flow in drum level controller face
plate
LD X1; sat steam flow signal
LD P2; 0.666 gain for ranging
*
ST T3
LD X2; super heated steam flow
LD P3; 0.333 gain for ranging
*
ST T4
LD T3
+
ST T5
ST Y3; for pressure controlling flow feed forward signal AO3
ST P6; for display total steam flow in feed water controller
face plate
LD P4; gain of total steam flow for correction if necessary now it
is 1
*
LD P5; 50 %( subtractor from drum level cont4roller output
-
ST T6
ST FF1; feed forward signal modify drum level controller
output by “T6”
LD SV2; six lines after this is for ascertaining the drum level
controller output in” T15”
LD P6
-
ST T14
LD P5
+
ST T15
LD DI1; 1=single element,0=three element
LD P7; 100=single element, 0=three element
OR
ST PRDF; true= (single element), false= (three element)
LD CAMF1; true when controller1 LIC in auto mode
NOT
GIFSUB @ abc; jump to subroutine 4 trading the PV by SV of
LIC in manual mode
LD T1; compensated drum level
LD T2; feed water flow
CSC; cascade
ST Y1; output to feed water control valve
LD PHF1; true when high level alarm occurs
ST DO3; digital output of high alarm
LD PLF1; true when low level alarm occurs
ST DO2; digital output of low alarm
LD X1
ST P12
LD X2
ST P13
LD T2
ST P14
LD T1
ST P15
LD T15 ST P16
LD CAMF2
NOT
GIFSUB @ def
END; end of main program
SUB@abc
LD PV1
ST SVI
RTN
SUB @ def
LD PV2
ST SV2
RTN
SUB @ SIMPR; test program
LD P21
ST X1
LD P22
ST X2
LD P23
ST X3
LD P24
ST X4
RTN
CONCLUSION
Successfully controlled the boiler drum level using YS1700
programmable controller.
QUESTIONS