mc³ 30.11 - merrick industries, inc.merrick-inc.com/legacypages/mct/mc3apps/3011_o12.pdfmc³...

MC³ 30.11.EX Solid Fuel System Controller

Operation and Maintenance Manual Version O, RFC Edition

MERRICK INDUSTRIES, INC. 10 Arthur Drive Lynn Haven, FL 32444 U.S.A Tel: +1 850.265.3611 Fax +1 850.265.9768 www.merrick-inc.com

Revision History 10/08/03 WIP. Updated. 01/09/04 WIP, theory of operation added. 01/12/04 WIP, expanded top, added links. 01/14/04 WIP, added register references. 01/23/04 WIP, Calibration, Controls. 06/08/04 WIP, Included updated 3010 material. 08/05/04 WIP, Typos and references 10/08/04 WIP, Defaults. 01/12/05 O release, RFC. PROPRIETARY NOTE The information in this manual, including technical data and copies of drawings, embodies information proprietary to Merrick Industries, Incorporated. This manual is provided to the user of equipment purchased from Merrick Industries, Inc. for use only in operation or maintenance of such equipment. Such information in this manual is not to be used, disclosed, copied, or reproduced in whole or part for any use other than that indicated above, or for any other purpose detrimental to the interests of Merrick Industries, Inc. Patents owned by Merrick Industries, Inc. have been issued or are pending on at least some of the information in this manual, and unauthorized use of this subject matter of such patents is a violation of such patents and is prohibited

CONTENTS Introduction...................................................................................................................................... 7

Safety ........................................................................................................................................... 7 In General................................................................................................................................. 7 Electrical Precautions............................................................................................................... 7

Related Publications .................................................................................................................... 7 Manual Conventions .................................................................................................................... 7

Screens .................................................................................................................................... 8 Solving Problems ......................................................................................................................... 8

Technical Support .................................................................................................................... 8 System Overview............................................................................................................................. 9

Finding your way in the Controller Screens............................................................................... 11 Main Screens ......................................................................................................................... 11 System Controls Menu Tree .................................................................................................. 13

Maintenance Screen........................................................................................................... 14 Action Menu Tree ................................................................................................................... 14 Warning Indication.................................................................................................................. 15 Fault Indication ....................................................................................................................... 15

Dynamic Control Algorithms ...................................................................................................... 16 Loss-In-Weight Feedrate Control ........................................................................................... 17

LIW parameters .................................................................................................................. 17 Weight Conditioning ........................................................................................................... 17 Weight Filter........................................................................................................................ 18 Volumetric Mode................................................................................................................. 18 Loss Calculation ................................................................................................................. 19 SP Conditioning .................................................................................................................. 19 SP filter ............................................................................................................................... 19 PID Controller ..................................................................................................................... 20 CSG Controller ................................................................................................................... 20 Arbitrator ............................................................................................................................. 21 Dynamic Protection ............................................................................................................ 22 Coke Feedrate and Weight Limits ...................................................................................... 22

Blower Control........................................................................................................................ 23 Air SP Conditioning ............................................................................................................ 23 Air PV Conditioning ............................................................................................................ 23 Blower PI Controller............................................................................................................ 24 Blower Limits ...................................................................................................................... 24

Hopper Pressure Control ....................................................................................................... 25 HPr PV Conditioning........................................................................................................... 25 PPr filtering ......................................................................................................................... 25 HPr On/Off Controllers ....................................................................................................... 26 HPr Limits ........................................................................................................................... 26

Pipe Temp and Pressure ........................................................................................................... 26 Pipe Temp measurement....................................................................................................... 26

Temp Limits ........................................................................................................................ 27 Pipe Pressure measurement.................................................................................................. 27

PPr Limits ........................................................................................................................... 27 Air Speed Calculation............................................................................................................. 27

Air Speed Limits.................................................................................................................. 28 Digital Control Sequences ......................................................................................................... 28

Blower States and Sequences ............................................................................................... 28 Feeder States and Sequences............................................................................................... 28

Setting Up Your Controller ......................................................................................................... 30 Select Units ............................................................................................................................ 30

30.11.EX O&M Manual 3 of 91 01/12/2005/Lars

Set Dec Pts ............................................................................................................................ 30 Design Capacities .................................................................................................................. 30 Control Settings...................................................................................................................... 31

Gain .................................................................................................................................... 31 Integral................................................................................................................................ 31 Derivative............................................................................................................................ 31 SCR Accel and SCR Decel ................................................................................................ 31 Average Slots ..................................................................................................................... 31 Loss Slots ........................................................................................................................... 32 Max Fdr Span, Fdr Samples............................................................................................... 32 Min Cred FR ....................................................................................................................... 32 CSG Timeout ...................................................................................................................... 32 Feed Factor ........................................................................................................................ 32

Hopper Settings...................................................................................................................... 32 Fill Point .............................................................................................................................. 33 Heel Point ........................................................................................................................... 33 Empty Weight ..................................................................................................................... 33 Fill Time .............................................................................................................................. 33 Clean Time ......................................................................................................................... 34 Empty Time......................................................................................................................... 34 Gate Time ........................................................................................................................... 34 Low Cutoff Wt ..................................................................................................................... 34 Min Preact........................................................................................................................... 34 Max Preact.......................................................................................................................... 34

Stability Settings..................................................................................................................... 34 Stable Time......................................................................................................................... 35 Stable Span ........................................................................................................................ 35 Stable Samples................................................................................................................... 35

Calibrate Settings ................................................................................................................... 35 Cal Weight .......................................................................................................................... 35 E-Cal Liveload .................................................................................................................... 35 Zero Weight ........................................................................................................................ 35 Scale Factor........................................................................................................................ 35

Quick Setup............................................................................................................................ 35 Sample Rate........................................................................................................................... 36 Dampening & Display............................................................................................................. 36

SP Filter .............................................................................................................................. 37 Displayed FR ...................................................................................................................... 37 Backlite Off ......................................................................................................................... 37 Grf Tm Incr.......................................................................................................................... 37

Set Date and Time ................................................................................................................. 37 Inputs and Outputs Menu .......................................................................................................... 37

Analog Inputs Setup............................................................................................................... 38 Coke SP selections ............................................................................................................ 38 Air SP selections................................................................................................................. 38 Analog Input Numeric Parameters ..................................................................................... 38 Unused Analog Inputs ........................................................................................................ 39

Analog Outputs Setup ............................................................................................................ 39 Analog Outputs Numeric Parameters................................................................................. 40

Digital I/O Mapping................................................................................................................. 41 Digital Inputs Setup ............................................................................................................ 42 Logical Inputs...................................................................................................................... 42 Physical Inputs.................................................................................................................... 45 Digital Outputs .................................................................................................................... 46 Logical Outputs................................................................................................................... 47 Physical Outputs................................................................................................................. 51


EMT Settings.......................................................................................................................... 51 Divisor................................................................................................................................. 51 Pulse Width......................................................................................................................... 51

Comm Settings....................................................................................................................... 52 Comm 1 Numeric................................................................................................................ 52 Comm 2 Numeric................................................................................................................ 53

Limit Switches ........................................................................................................................ 53 Feedrate Limits ................................................................................................................... 53 Weight Limits ...................................................................................................................... 53 Fdr CV Limits ...................................................................................................................... 54 Setpoint Limits .................................................................................................................... 54 Feed Factor Limits .............................................................................................................. 54

PLC Interface ............................................................................................................................. 55 PLC Overview ........................................................................................................................ 55

SCD User Defined Datatype............................................................................................... 56 PLC Public Tags Layout......................................................................................................... 57

UPB Status Bits Layout ...................................................................................................... 57 UPV Report Variables Layout............................................................................................. 63 DTB Command Bits Layout ................................................................................................ 63 DTV Control Variables Layout ............................................................................................ 65

Tags – Reported and Controlled Registers Table. ................................................................ 65 The tstc, blkc, tsts and blks DINTs ..................................................................................... 66

Command Sequences ............................................................................................................... 67 Starting and stopping the blower............................................................................................ 67 Starting and stopping the feeder ............................................................................................ 67 Reversing ............................................................................................................................... 67 Cleaning out ........................................................................................................................... 68 Emptying ................................................................................................................................ 68 Clear Warnings....................................................................................................................... 69 Clear Sub-total ....................................................................................................................... 69 Lock the MC³ Touch-Pad ....................................................................................................... 69 Manual Fill .............................................................................................................................. 69 De-pressurize the Hopper ...................................................................................................... 70 Aerate the Silo........................................................................................................................ 70 Clear Faults ............................................................................................................................ 70

Calibrating Your Controller ............................................................................................................ 71 Calibration Menu........................................................................................................................ 71

Zeroing Procedure ................................................................................................................. 72 Material Calibration ................................................................................................................ 73 Weight Procedure................................................................................................................... 73 Electronic Calibration ............................................................................................................. 75 E-Cal Factor Procedure ......................................................................................................... 76 Analog Input Procedure ......................................................................................................... 77 Start Learning......................................................................................................................... 78

Diagnosing Problems .................................................................................................................... 81 The Crash Screen...................................................................................................................... 81

Start-Up Crash ....................................................................................................................... 81 Parameter Corruption ......................................................................................................... 81 Controller Firmware Upgrade ............................................................................................. 81

Fatal Error Crash.................................................................................................................... 82 Forcing a Parameter Reset ................................................................................................ 83

Diagnostic Menus................................................................................................................... 83 HPAD Diagnostics .............................................................................................................. 83

Communication Diagnostics................................................................................................... 84 Calib History Display .............................................................................................................. 86

Analog Diagnostics............................................................................................................. 86


Digital Diagnostics.................................................................................................................. 86 Mapping view...................................................................................................................... 87 List View ............................................................................................................................. 87

Faults and Warnings Diagnostics .......................................................................................... 88 DF1 Diagnostics ................................................................................................................. 88

Register Monitor ..................................................................................................................... 88 Misc Data Diagnostics............................................................................................................ 88

Modbus Diagnostics ........................................................................................................... 89 Diagnostic Settings .................................................................................................................... 90

HPAD Settings ....................................................................................................................... 90 CAL..................................................................................................................................... 90 ZERO.................................................................................................................................. 90 GAIN ................................................................................................................................... 90 Set Status ........................................................................................................................... 90 Number of HPAD’s ............................................................................................................. 90 Allowed Difference.............................................................................................................. 91

Passwords.............................................................................................................................. 91 Register Editor........................................................................................................................ 91


INTRODUCTION

SAFETY The Merrick MC³ Controller is used for the control of process weighing equipment. To insure personnel safety please read the following instructions and precautions carefully.

In General 1. Observe all standard precautions that pertain to moving machinery. 2. Observe all standard precautions that pertain to electrical drives and electrical

controls. 3. Pay particular attentions to special notes and precautions that appear throughout

this manual. 4. Please read and familiarize yourself with this entire manual before attempting

service or repair of the Merrick MC³ Controller. If you have any questions or problems please call the Merrick Service Department for assistance.

Electrical Precautions 1. Before undertaking work on the electrical system, the drives, or the Controller,

open the main-disconnect switches and lock boxes. Work should never be performed on the Controller with power on the unit. It is recommended to disconnect the power from the controller before attempting any service procedure.

2. Verify that all grounds that are called for on the wiring diagrams are in place and are securely connected. Proper grounding not only helps insure your personal safety, but also is necessary for the proper operation of the controller.

3. If it is necessary that you must work in or near areas of live high voltage, always keep one hand clear of the machine, the cabinet, or any other conductors to avoid the possibility of electrical shock traveling across your chest.

4. NEVER impair or disable the function of a fuse or a circuit breaker. IF YOU ARE IN DOUBT ABOUT ANY PROCEDURE, CONTACT THE MERRICK SERVICE DEPARTMENT.

RELATED PUBLICATIONS You will find related publications regarding MC³ controller hardware and industrial networking capabilities at the support web site at http://www.merrick-inc.com/mct. In the rest of the manual, this is referred to as [MCT]. This document specifies the functional properties of a Petroleum Coke Feeder System controller. It is implemented in a Merrick MC³ controller and in ladder logic in an Allen-Bradley ControlLogix PLC. The following documents also apply. File Rev Date Content A40032R7Official.DWG 7 2003-12-29 Circuit diagram IOMAP_28.XLS 28 2003-12-08 Standard mapping #3011Z.XLS 1 2003-12-17 Default Specification Sheet SCD_29.ACD 29 2003-12-28 Interface PLC Ladder image

MANUAL CONVENTIONS NOTE: Any additional information that may be useful follows the note marker. CAUTION: Be careful, certain settings may cause problems.


http://www.merrick-inc.com/mct

WARNING: Follow the directions prescribed in the warning. Serious problems can occur if the recommendations are not followed. R[254] This is a register reference to a parameter, in this case register number 254. Some parameters can only be inspected or changed, using the Register Editor. See page 91.

Screens

Example Screen Shot

A graphic of this size and type will show the functions available and/or information available in diagnostic screens and special display screens.

SOLVING PROBLEMS Several methods are available for use to assist in solving problems. The application contains help buttons for giving text explanations of the current selected function or parameter. Also included in this manual is a troubleshooting section to assist in solving technical problems (Diagnosing Problems, page 81).

Technical Support Merrick provides customer technical and spare part support 24 hours a day, seven days a week. Assistance is available by calling +1.850.271.7878. After normal business hours, you will receive instructions on how to reach the support technician on call. You can also email [email protected]. When you call or email Merrick for Technical Support, please have your machine serial number or a controller serial number. This information will better help us to serve you.


SYSTEM OVERVIEW The Feeder Control System (FCS) maintains Petroleum Coke Feedrate and Air Flowrate into the furnace pneumatic transport pipe based on control data received from the Combustion Control System (CCS). Coke Feedrate, Air Flowrate and Weigh Hopper Pressure are under closed loop control. Process parameters, states and exceptions are reported back to CCS.

ddt

FeedrateControl VFD1

FILLControl

Weight

VFD2FlowrateControl

Air PV, PPr PV, Temp

Coke PV

Coke SP

PressureControl

HPr PV

Fill Gate

Seal Gate

Vent Gate

HPr SP

Feed Gate

Slow

Fast

Air SP

Figure 1 – Coke Feeding System

The Coke Feedrate is controlled by means of a Loss-In-Weight arrangement, consisting of a weigh hopper with a Rotary Airlock Feeder (RAL) as the discharge device driven by a Variable Frequency Drive (VFD). The feedrate is calculated by taking the time derivative of the weight in the hopper. The speed of the RAL is varied until the calculated Coke Feedrate (Coke PV) meets the Coke Feedrate Setpoint (Coke SP). When CCS calls for a “reversal” or “manual fill” event, the hopper is quickly filled from a storage silo to a preset limit, the Fill Point, by means of a fill gate arrangement. If filling is called for by a Reversal event, the Feed Gate is closed, and the transport pipe is purged of coke. If the Coke SP is higher than the available hopper capacity for the reversal period, an extra fill cycle is performed in between reversal events. Furthermore, if the weight in the hopper is less than another preset limit, the Heel Point, an extra fill cycle is performed unconditionally. The Air Flow is controlled by means of a Blower with VFD controlled speed and an Air Flow Meter. The speed of the blower is varied until the measured air flowrate (Air PV) meets the air flowrate setpoint (Air SP). The Pressure Controller pressurizes the hopper based on a Hopper Pressure Setpoint (HPr SP). During fill sequences, the pressure is vented out. During re-pressurization after fill, two injectors, one fast and one slow, are used. To keep the pressure constant during feeding, only the slow injector is used.


There are two control cabinets making up the Feeder Control System (FCS): 1. The Feeder Control Cabinet, (FCC) located at the feeder 2. The Blower Control Cabinet, (BCC) located at the blower

1761Net ENI

MAP80PSU

MC³30.11.EX

FCC - Feeder Control Cabinet

UPS

TRFCKTBKR

8

Feeder VFD

Blower VFD CKTBKR

FEEDER

BLOWER

Plan

t wid

e Et

hern

et/IP

BCC - Blower Control Cabinet

7

440V 15A

440V 50A

Dig Switches

Actua-tors

LoadCells

3

3

AnalogTx’s

3

AnalogOut

AnalogIn

Digital Out

DigitalIn

1794 PS13

1794 PS13

3

3

CCSFallback

Figure 2 – Control System Layout

In the FCS, the MC³, which is a dedicated controller for this application, handles the feedrate, fill, pressure and blower control. See also Merrick drawing A40855.


FINDING YOUR WAY IN THE CONTROLLER SCREENS The MC³ user display is organized in a hierarchical system of screens. There are three Main Screens, intended for system overview. From those, you can reach the System Control and Action Screens, intended for local control, maintenance, diagnostics and parameter settings.

Main Screens

Figure 3 – Controller Main Screen System

Here is a list of the text and acronyms used in the main screens: Feeding Textual representation of the coke feeding state machine. The text will vary. See

Feeder States and Sequences on page 28. Running Textual representation of the blower state machine. The text will vary. See

Blower States and Sequences on page 28. Coke WT Net weight of coke in the weigh hopper. Coke SP Coke setpoint. Coke PV Actual coke feedrate.


Coke CV Control Value for the signal driving the VFD driving the RAL. Air SP Air flow setpoint. Air PV Actual air flow. Air CV Control Value for the signal driving the VFD driving the blower. HPr SP Hopper pressure setpoint. HPr PV Actual hopper pressure. PPr PV Actual burner pipe pressure. Temp Actual burner pipe air temperature. Air speed Calculated air speed in the burner pipe FeedFact Actual Feed Factor. See CSG Controller on page 20. Loss Weight difference, per time unit. See Loss Calculation on page 19. During normal

feeding this is a negative number, with a value close to the Coke PV. During filling, this is a large positive value.

SigQuality A measurement of the stability of the Loss value. See Arbitrator on page 21. 0% indicates that the Loss value is ‘incredible’, and not useful for feedrate control. The highest possible value is 90%.

Sys Blk Indicator for the System Block logical input. Blw Go Indicator for a valid blower run permission state. See Starting and stopping the

blower on page 67. Blw Rn Indicator for the Blw Running logical output. Fdr Blk Indicator for the Feeder Block logical input. Fdr Go Indicator for a valid feeder run permission state. See Starting and stopping the

feeder on page67. Fdr Rn Indicator for the Fdr Running logical output. Good Indicator for the Good Feedrate logical output. Reverse Indicator for the Reversing logical output. Low Indicator for the Lo Fdr Error logical output. High Indicator for the Hi Fdr Error logical output.


System Controls Menu Tree Pressing the System Controls button in any of the main screens takes you to an interactive screen used to set the control mode. There are four modes: • Network Mode – the EtherNet/IP link between the PLC and the MC³ is operational and used

to pass control information. The PLC is controlling the feeder This is the preferred and fully functional control mode. On an EtherNet/IP failure, an automatic mode change to Fallback Mode takes place.

• Fallback Mode – Discrete circuits (analog and digital) are used to pass control information. The PLC is controlling the feeder. This mode is in place to handle an EtherNet/IP failure. If EtherNet/IP functionality is restored, an automatic mode change to Network Mode takes place.

• Local Mode – MC³ screens are used to control the feeder. The PLC is NOT controlling the feeder. Mode changes take place using the feeder screen.

• Maintenance Mode – Used for checking feeder actuators. It is only possible to switch to Maintenance mode when the system is stopped.

The appearance of the system controls screen depends on the mode. In Network mode, which is the normal mode of operation, the only options available are switching to Local or Maintenance mode. If the blower or feeder is running, the maintenance mode button is not available. In Local mode, most control is handled from this screen. The blower and feeder can be started and stopped, and the air and coke setpoints can be set. When the feeder is running in Local mode, a Cleanout or a Fill sequence can be initiated or aborted. In maintenance mode, you get access to the maintenance screen.


Maintenance Screen This interactive screen is intended for checking mechanical actuators. You reach it from the System Controls menu. Buttons are either toggle type or immediate type. Toggle type buttons have an “O” or “I” in them, indicating the state, Off or On, respectively, of the device. There are certain safety related limitations: • You can only open the Seal Gate if the Vent Gate

is open (Vent Gt Opened limit switch) and the pressure in the hopper is less than R[924], depressurize pressure. See HPr Limits on page 26.

• You can only operate the Fill Gate if the Seal Gate is open.

• To operate the Fast and Slow pressurization nozzles, the Seal Gate has to be closed (Seal Gt Closed limit switch), and the and the pressure in the hopper must be less than R[914], max pressure. See HPr Limits on page 26.

• To operate the Purge Vent solenoid, the Vent Gate has to be closed (Vent Gt Closed limit switch)

Turning on the Blower or Feeder allows you to control the CV signal going to the VFD’s. The default increment is 5%. It can be changed in R[904] and R[853]

Action Menu Tree Pressing the Action Menu in any of the main screens takes you to the Action Menu. See Main Screens on page 11. You can reset the total and subtotal from here. The Clean Off Screen button gives you 60 seconds of inactive touch screen, to wipe it clean without pressing any buttons. The Settings Menu button takes you a system of screens where most of the commonly used parameters are set up. See Setting Up Your Controller on page 30. The Calibrate Menu button menu takes you to the screen for all the automated calibration routines. See Calibrating Your Controller on page 71. The Diag Menu button takes you to the diagnostics system. See Diagnosing Problems on page 81.


Warning Indication A Warning indicates a potential problem and calls for your attention. Any logical input or output can be configured to qualify a warning. See Digital I/O Mapping on page 41. The Warnings button is visible in any of the main screens if there is an active warning condition or there has been a warning condition that has not been acknowledged.

Feeder Screen with Warning Indicator

Pushing the Warnings button takes you to the Warning screens. It is possible to configure up to 32 warnings. The following screen shot shows the default warnings. Your I/O configuration may be different, producing different Warnings screens.

Warnings screens

The Next Page button flips between the screens. There is an active indicator to the left of the text ( = ON = OFF). There is also a “did occur” indicator to the left of the active indicator. A “D” indicates that the warning has been disabled from the PLC. You can acknowledge one warning at a time. Use the up and down arrow buttons to move the selection box to the Warning you want to acknowledge, and push Ack. If you want to acknowledge all warnings, push the Ack All button. If the Warning is still active, the Warning button will continue to be displayed on the main screen and the Warning will continue to be indicated on this screen.

Fault Indication A Fault indicates a malfunction that prevents the system from running. Any logical input or output can be configured to qualify a fault. See Digital I/O Mapping on page 41. The Fault button is visible in any of the main screens if there is an active fault condition or there has been a fault condition that has not been acknowledged.

Feeder Screen with Faults Indicator

Pushing the Fault button takes you to the Fault screen. The following screen shots show the default faults. Your I/O configuration may be different, producing a different Faults screens.


Faults screens

The Faults Screen works just like the Warnings Screen. You can’t start the feeder if the there is an unacknowledged Fault.

DYNAMIC CONTROL ALGORITHMS There are three major dynamic control algorithms: 1. Loss-In-Weight Feedrate Control (LIW), producing a Coke feedrate (Coke PV) that follows

the Coke Setpoint (Coke SP). This is done by varying the speed of a rotary airlock (RAL), feeding coke from the weigh hopper to the burner pipe. This is, by far, the most complex and difficult component of the control system.

2. Blower Control, producing an Air flowrate (Air PV) that follows the Air Setpoint (Air SP). This is done by varying the speed of the blower that injects air into the burner pipe.

3. Hopper Pressure Control, maintaining a suitable pressure in the weigh hopper. This is done by injection solenoids, turning plant air (at 60 to 80 PSIG) on an off.

The algorithms interact with all Digital Control Sequences. See page 28. This section describes the dynamic properties of the control algorithms only.

NOTE: The 30.11.EX application is an extension of the generic 30.10.EX.E loss-in-weight application. Some parameters, primarily regarding hopper pressure and blower control are not available in the Settings Menu screens. Instead, the register editor is used to check and adjust the parameters. In these cases, the parameter is defined by its register number, i.e. R[887]. See Register Editor on page 91.


Loss-In-Weight Feedrate Control Coke is extracted from a hopper with the RAL. The hopper is placed on load cells, producing a signal proportional to the weight of the hopper and its content. The MC³ will calculate the Coke PV from the rate of loss of the hopper weight and attempt to maintain the Coke PV at the desired setpoint (Coke SP) by varying the speed of the RAL. This is done with a VFD, controlling the RAL motor speed. The control signal to the VFD is called “Coke Control Variable” (Coke CV).

The MC³ uses two different control algorithms that normally compete with each other for the control of the RAL. The PID (Proportional, Integral, and Derivative) control algorithm is suitable for high feedrates and stable rate of loss values. The CSG (Conditional Step Gravimetric) control algorithm is suitable for slow feedrates and when occasional disturbances in the weight signal are present.

Coke SP Weight

SP Conditioning

Weight Conditioning

Override

SPFilter

Weight Filter

Coke SP

Weight

Loss Calculation-

Average Weight

PIDControl

CSGControl

Arbitrator

CokeCV

Signal Quality

Loss Most applications fall in between the two categories. By keeping both algorithms active, and letting an arbitrating algorithm determine to which degree the PID and CSG are allowed to control the speed of the feeding device, it is possible to take advantage of the desired properties of both. For very slow or very fast feeders however, it is better to use only CSG or only PID control. Rudimentary volumetric control is possible in case of a load cell failure

Figure 4 – Coke Feedrate control

LIW parameters Each of the function blocks has one or more parameters associated with it. They all have to be set properly for good feedrate control. Most of them can be set automatically, by using the Quick Setup function. A Learning Cycle can also be used to further improve system tuning. Some of the parameters can be continuously updated by the controller itself, as a part of an auto-tuning scheme.

Weight Conditioning The weight signal conditioning block takes the Load Cell Signal as input, passes through an A/D converter, called the HPAD, and produces a weight value as an output. The output from the HPAD is a number between 0 and 1,000,000, called “counts”. Parameters are:


Zero Weight The weight of the hopper, RAL etc. when the hopper is empty. Set by running a Zeroing Procedure page 72. You can also set it manually. See Zero Weight on page 35.

Scale Factor A divisor to translate the load cell signal counts from the HPAD, to usable engineering units, such as lb or kg. Set by running one of the many calibration routines (Calibrating Your Controller on page 71), or manually, in Scale Factor, page 35.

Sample Time How often the controller re-calculates all internal variables. Set by Quick Setup, page 35, or manually in Sample Rate, page 36. The slower the feedrate, the longer the sample time.

The HPAD Diagnostics screen on page 83 is a good overview of weight conditioning parameters and variables. Read more about calibration procedures and Calibrating Your Controller on page 71.

Weight Filter The weight produced by the Weight Conditioning Block is normally not usable for determining the weight loss. An averaging filter is used to produce a smoother stream of values suitable for this purpose. It takes the Weight as input and produces the Average Weight as output, by calculating the arithmetic average of a settable number of samples. There is only one parameter: Average Slot Number of weight samples used to form the Average Weight. Set by Quick

Setup, page 35, by running a Start Learning procedure (page 78) or manually in Average Slots, page 31. The slower the feeder, the more the slots. If the Auto Tune Go Input is turned on, this parameter is adjusted, based on statistics from the last weigh cycle, at the start of each Fill Sequence. The default value is 100. With the default sample time of 200 ms, the averaging time is 20 seconds.

The averaged weight can be monitored in R[285].

Volumetric Mode It is possible to continue to use the system in case of a load cell related failure. The hopper weight is calculated based on inferred values. There are two level sensors in the weigh hopper, one placed high and one placed low. The calculated weight is corrected every time the level sensors change state. Coke CV is set by multiplying the Coke SP with the Feedfactor. During normal (Gravimetric) operation, the Feedfactor and the net weights corresponding to the level sensors are updated continuously. In case of a weight value failure (HPAD Underload, HPAD Overload, HPAD Failure), if the logical input Allow Vol Mode is on, an automatic switch to Volumetric Mode takes place. You can force the system into Volumetric Mode by turning on the Force Vol Mode input. The Feedfactor may be updated during a discharge cycle if the following conditions are met: • The upper level sensor disengages, • The lower level sensor disengages, • The Coke SP does not change. Parameters: R[980] Volumetric mode flag. 1 in volumetric mode, else 0. R[981] Weight at the high level sensor. During Gravimetric operation, this parameter is

updated every time the level sensor is disengaged, that is, when sensor no longer senses material presence.

R[982] Weight at the low level sensor. Updated like R[981]. R[983] High level sensor turn-off delay. Default 30 s. R[984] Low level sensor turn-off delay. Default 30 s. R[985] Calculated average Coke PV during the last discharge cycle. Used to update the

Feedfactor. Only updated when the update conditions above are met.


R[986] Limit for updates of R[981] and R[982] in Gravimetric Mode. In place to avoid a situation where a bogus disturbance on the level sensor signals causes erratic values. Default is 1 % of Design Weight.

R[987] Estimated positive rate of change of weight during fill. Default is 180 * (Fill Point – Heel Point), that is, the filling is assumed to take 20 seconds.

R[988] Feedfactor Update state variable. 0 when the discharge cycle starts, 1 when the upper level sensor has disengaged, 2 when an actual Feedfactor update has taken place.

R[989] Max allowed Feedfactor correction in Volumetric Mode. Default 1%. R[990] Calculated new Feedfactor in Volumetric Mode. This will become the new

operational Feedfactor the difference it is less than R[989]. If the difference is greater, the operational Feedfactor will change wit the value in R[989].

Loss Calculation This is where the Weight Loss is calculated, by taking the difference between two samples of the Average Weight. There is only one parameter. It is normally set to the same value as the Average Slot. Loss slots How many samples the two Average Weight values are separated to calculate

the Weight Loss. Set by Quick Setup, page 35, by running a Start Learning procedure (page 78) or manually in Loss Slots, page 32. If the Auto Tune Go Input is turned on, this parameter is adjusted, based on statistics from the last weigh cycle, at the start of each Fill Sequence. The default value is 100. With the default sample time of 200 ms, the differential time is 20 seconds.

Loss is a negative number during normal feeding, representing the change of the weight in the hopper, in kg/h. It can monitored in the numerical main screen. The Coke PV is derived from the loss, but there are several conditions added, such as the credibility of the weight variable, low pass filtering and inferred feedrates during fill etc.

SP Conditioning The Coke Setpoint (Coke SP) is taken from different sources, depending on the Control Mode: Network: ASCD[n]DTV[0]. Fallback: Normally Analog Input 1. Local: Set in System Controls Screen. If R[230] is zero, the Local setpoint is used in Fallback mode. This is useful if there is no analog signal available for the Coke SP. When an analog signal is used, the setpoint has to be calculated in a similar way as the Weight. The analog Setpoint signal is taken as an input and passes through a 20 bit A/D converter and produces a Setpoint Feedrate as an output. Parameters are: CokeSP Lo Cnt A value in counts from the A/D converter representing a Minimum

setpoint. Default is 200,000. CokeSP Hi Cnt A value in counts from the A/D converter representing a Maximum

setpoint. Default is 1,000,000. CokeSP MinVal Minimum setpoint limit, default zero. CokeSP MaxVal Maximum setpoint limit, default Design Feedrate.. The parameters SP Hi counts and SP Lo counts are set by running an Analog Input Procedure, page 77. All parameters can be set manually in Analog Input Numeric Parameters. See page 38.

SP filter When using CSG control, a fluctuating setpoint is undesirable. To avoid fluctuations due to noise on analog signals in fallback mode, this averaging filter can be used to produce a smoother value. It takes the setpoint feedrate as input and produces an averaged setpoint as output, by calculating the arithmetic average of a settable number of samples. There is only one parameter:


SP Filter Set by the Set by Quick Setup (page 35), by running a Start Learning procedure (page 78) or manually in SP Filter (page 37).

The Coke SP presented in the main screens is the filtered version. The un-filtered version can be monitored in R[228].

PID Controller This is a classic Proportional, Integral and Derivative control algorithm, taking the difference between the Coke SP and the Loss as an error input, and producing a control variable (Coke CV) as an output. PID control works well when there are no disturbances on the weight signal. The feeding device does not necessarily have to be linear and repeatable. There are three parameters, all located in Control Settings. See page 31. Gain This is the PID closed loop gain, expressed in %. The setting affects all three PID

controller components (Proportional, Integral and Derivative). Too much gain can cause the feeder to oscillate. Too little gain gives you sluggish control. A good starting point is a setting of 20% of the Feed Factor. Default is 10%. Set in Gain, page 31.

Integral The PID integral component uses the accumulated (integrated) error (Coke PV – Coke SP) over time to adjust the Coke CV. The Integral parameter, expressed in 1/seconds, determines how fast the accumulation takes place. The Integral function will, over time, make the deviation go to zero, assuming that everything else is in steady state. A good starting point is to set the parameter according to this formula:

SampleTimetsAverageSlo2Integral⋅

=

The default Sample time is 0.2 seconds per sample. See Sample Rate. The default Integral value is 0.1 1/s. Set in Integral, page 31.

Derivative The PID derivative component uses the trend of the error to adjust the Coke CV. The Derivative parameter, expressed in seconds, determines the sensitivity to trend changes. The Derivative function will react early to changes. A good starting point is to set the parameter according to this formula:

SampleTimeSlotsAverage01.0Derivative ⋅⋅=

The default value for Derivative is 0.2 s. Set in Derivative, page 31. If the Auto Tune Go Input is turned on, all three parameters are adjusted, based on statistics from the last weigh cycle, at the start of each fill sequence. The Quick Setup function (page 35), and running a Start Learning procedure (page 78) will also change them. They can also be modified manually in Control Settings. See page 31.

CSG Controller The Conditional Step Gravimetric control algorithm maintains a model of the efficiency of the RAL, resulting in a parameter called the Feed Factor. It is defined as “The Coke CV required to feed at Dsgn Feedrate”. A Feed Factor greater than 100% indicates that the Dsgn Feedrate can not be reached, because the feeding device is not efficient enough. A Feed Factor of less than 60% indicates that the capacity of the feeding device is too high (not correctly dimensioned) or there is coke leaking by the flights of the RAL. The Feed Factor is only modified when the Loss signal is stable. The CV, produced by the control algorithm, is calculated as

FeedratesgnDFactorFeedSPCokeCVCSG •=


The result is a CV that only changes when there are no disturbances. The Feed Factor can be modified manually in Control Settings (page 31), but since it is a variable, the changes you enter are temporary. This control algorithm works well when the RAL is reasonably linear and repeatable. It can handle a situation when occasional disturbances on the Weight value are present. Parameters: Min Credbl FR A low limit of the Loss signal. If it is less than this value, it is not considered

credible, and consequently, the Feed Factor will not be updated. It is used to avoid a situation where the Feed Factor shoots up because of a problem with the material flow in the RAL. Set in Min Cred FR, page 32.

FF Dampening Determines how aggressively a new Feed Factor is calculated. A higher number means that the changes to the Feed Factor are relatively smaller, producing a less aggressive control. Set in Feed Factor Limits, page 54.

Max Feedfact Upper limit for the Feed Factor. Used to avoid a situation where a temporary obstruction of the RAL creates a very high Feed Factor which will, in turn, produce a very high Coke PV when the obstruction is removed. If the Feed Factor reaches this limit, the output Hi Feedfactor goes on. Set in Feed Factor Limits, page 54.

Min Feedfact Lower limit for the Feed Factor. Used to detect a RAL that lets coke past the flights. If the Feed Factor reaches this limit, the output Lo Feedfactor goes on. Set in Feed Factor Limits, page 54.

For some hoppers, the Feed Factor varies with the weight in the hopper in a reproducible manner. It is possible to adjust the Feed Factor during the fill sequence if this is the case. This is done by mapping the Logical Inputs Use Fill Adj and Auto Fill Adj to Always On. This will engage some more parameters. HiFF Start T Time from the end of the fill sequence to the capture of the Feed Factor value at

high weight in the hopper. Hiff Stop % Weight value where the capture of the Feed Factor value at high weight is

ended, and locked in. Loff Start % Weight value where the capture of the Feed Factor at value at low weight is

started. The value is locked in right before the start of the fill sequence. All parameters are settable in Feed Factor Limits, page 54. Percentage is this context is related to the active hopper weight range, from Heel Point to Fill Point.

Arbitrator If both CSG and PID control are turned on, the Arbitrator will determine to what extent they are allowed to influence the Coke CV. In an undisturbed situation, PID dominates and vices versa. The end effect is that the control algorithm most efficient at the time is dominant. Parameters: MaxFdr Span Used to determine the stability of the Loss signal. Values around 2 % of the

Dsgn Feedrate are typical. The Loss signal is considered stable if it varies less than this parameter for Flow Samples number of samples. For the Feed Factor to be updated, the Loss must stay stable for at least the time represented by the two Slots parameters. The time can be calculated as

( ) TimeSampleSlotsLossSlotsAverageTimeStablequiredRe •+= With default values (100 slots, 0.2 s) the Required Stable Time is 40 seconds. A

frozen Feed Factor indicates that this parameter is too small. Either increase it or increase Average Slots and Loss Slots to get a more stable Loss calculation. Set in Max Fdr Span, Fdr Samples, page 32.

Flow Samples How many samples are used to determine the Loss stability.


R[266] PID/CSG adding method. The method must be 0 or 1, and must be found by trial and error. 0 is default. If you want to try a setting of 1, the Gain must be increased to around 5 times the setting used for method 0.

The arbitrator produces one output, Signal Quality, which can be monitored in the numeric main screen. Signal Quality will vary between 0% and 90%, where 90% is ‘very good’, and 0% is ‘unusable’. You should adjust Average Slot and Loss Slots or MaxFdr Span so that the Signal Quality stays between 75% and 90% while feeding, in steady state, with no disturbances present. Don’t go outside 1% - 5% of Dsgn Feedrate with MaxFdr Span. A higher MaxFdr Span will give you a more reactive control, as well as greater sensitivity to disturbances.

Dynamic Protection Some older drives did not have any protection for a rapidly increasing or decreasing CV. This can cause damage to the drive train. The Dynamic Protection limits the rate of change of the Coke CV, in percent per second. There are two parameters: SCR Accel How many percent CV is allowed to increase, per second. SCR Decel How many percent CV is allowed to decrease, per second. The parameters are set to 100%/s by default. Set in SCR Accel and SCR Decel. See page 31.

Coke Feedrate and Weight Limits All limit switch parameters are set in the Limit Switches menu. See page 52. Parameters in the Feedrate menu: Hi FeedRate Upper absolute high limit for Coke PV. Controls output Hi Fdr PV Lo Feedrate Lower absolute low limit for Coke PV. Controls output Lo Fdr PV Hi Rel Dev Upper relative limit for Coke Error, Coke PV – Coke SP, as expressed in percent

of current Coke SP. Combined with Hi Fdr Dev, below. Lo Rel Dev Lower relative limit for Coke Error. Hi Fdr Dev Upper absolute limit for Coke Error, Coke PV – Coke SP, as expressed in

feedrate units. This condition in combined with Hi Rel Dev to set the limit switch. The Coke error has to be above both of these limits for the Hi Fdr Error to go on.

Hi Fdr Dly Turn-on delay for the Hi Fdr PV output Lo Fdr Dly Turn-on delay for the Lo Fdr PV output. Hi Dev Dly Turn-on delay for the Hi Fdr Error output. Lo Dev Dly Turn-on delay for the Lo Fdr Error output. Parameters in the Weight menu: Hi Weight High limit for weight. Controls output Hi Weight Lo Weight Low limit for weight. Controls output Lo Weight Hi Wt Dly Turn-on delay for the Hi Weight output Lo Wt Dly Turn-on delay for the Lo Weight output. Parameters in the Output (Fdr CV) menu: Hi Fdr CV Upper limit for Fdr CV. Controls output Hi Fdr CV Lo Fdr CV Lower absolute low limit for Coke PV. Controls output Lo Fdr CV.

NOTE The Fdr CV signal, used to control the RAL speed, is limited with these parameters, but only when the Fdr Auto input is on. There are no limits in Feeder Manual Override mode. HiFdrCV Dly Turn-on delay for the Hi Fdr CV output LoFdrCV Dly Turn-on delay for the Lo Fdr CV output. Parameters in the Setpoint menu: Hi Fdr SP High limit for coke setpoint. Controls output Hi Fdr SP. Lo Fdr SP Low limit for weight. Controls output Lo Fdr SP.

NOTE The coke setpoint is limited only if input Clamp Fdr SP in on. The outputs are always active.


Hi SP Dly Turn-on delay for the Hi Weight output Lo SP Dly Turn-on delay for the Lo Weight output. Parameters in the Feed Factor menu are described in CSG Controller on page 20.

Blower Control Air is injected to the burner pipe with a blower. The blower motor speed is controlled by a VFD. There is a mass flow meter installed in the burner pipe, generating a 4..20 mA signal proportional to the air flow, in kg/h.

The airflow setpoint (Air SP) is taken from different sources, depending on the Control Mode: Air SP Air Flow

Meter

Air SP Conditioning

Air PV Conditioning

Override

Air SP Air PV

-

PIControl

AirCV

Network: ASCD[n]DTV[1]. Fallback: Normally Analog Input 2. Local: Set in System Controls. If R[884] is zero, the Local setpoint is used in Fallback mode. This is useful if there is no analog signal available for the Air SP.

Figure 5 – Air Flow control

Air SP Conditioning In Fallback mode, a 4..20 mA signal is normally used, connected to analog input 2. The signal passes through a 20 bit A/D converter and produces Air SP as an output. Parameters are: Air SP Lo Cnt A value in counts from the A/D converter representing a Minimum setpoint. Air SP Hi Cnt A value in counts from the A/D converter representing a Maximum setpoint. Air SP MinVal This is the minimum setpoint value, normally zero. Air SP MaxVal This is the maximum setpoint value, normally the same as the Design Feedrate

for the feeder. The parameters Air SP Hi Cnt and AirSP Lo Cnts are set by running an Analog Input Procedure, page 77. All parameters can be set manually in Analog Input Numeric Parameters. See page 38.

Air PV Conditioning The air flow is measured by a flow meter, producing a 4..20 mA output. The signal is connected to one of the analog inputs 2 – 9, normally 2, and passes through a 12 bit A/D converter, producing Air PV as output. Parameters are: R[885] Input selector. 0 for Analog Input 2, 1 for Analog input 3 etc. A value of 8 can be

used for simulation purposes, where the Air PV is generated in the PLC, and downloaded to the controller.

R[886] A/D counts for no flow (4 mA), nominally 778. R[887] A/D counts for Desgn Air Flow (20 mA), nominally 3890. R[888] A/D counts lower limit for credible analog input (3.2 mA), nominally 622. R[889] A/D counts upper limit for credible analog input (20.8 mA), nominally 4045. A

value greater than 4095 will disable the upper limit check.


R[959] Credible Analog Input forgiveness time. The A/D counts are allowed to stay outside the limits in R[888] and R[889] for this time period, without turning the Air Tx Bad output on.

NOTE: The design capacity of the flow meter has to agree with Dsgn Air Flow See Design Capacities on page 30. The live output from the A/D converter can be monitored in R[905].

Blower PI Controller This is a classic Proportional and Integral control algorithm, taking the difference between the Air SP and the Air PV as an error input, and producing a control variable (CV) as an output. For normal operation, the tuning has to be phlegmatic, to avoid pressure spikes and blower motor overloads. Parameters: R[890] This is the PID closed loop gain, expressed in %. The setting affects both PI

controller components (Proportional and Integral). Too much gain will cause drive and pressure instability problems. Too little gain gives you sluggish control. A good starting point is a setting of 10%, which is the default.

R[891] The PI integral component uses the accumulated (integrated) error (Air PV – Air SP) over time to adjust the Air CV. This parameter, expressed in 1/seconds, determines how fast the accumulation takes place. The Integral function will, over time, make the error go to zero, assuming that everything else is in steady state. The default value is 0.1 1/s.

R[909] Set to 1 for “big blowers”, having oil pressure switches and requiring a high start-up CV. This will modify the start-up sequence.

R[877] Big blower startup CV. During run-up some blowers require a high CV for proper start-up behavior.

Blower Limits R[878] Lower limit of Air CV, expressed in %. Some blower arrangements require a

minimum motor speed in order not to overheat. Default is 0%, equivalent to no lower limit.

R[879] Upper limit of Air CV, expressed in %. Default is 100%, equivalent to no upper limit.

NOTE: These limits are not enforced when the Blower Auto input is off, that is, when the blower control is in manual override mode. R[899] Max allowed error (Air SP – Air PV). If the error exceeds this limit for a longer

time than R[900], the output Lo Air PV goes on, typically causing a Fault. Default 50. This limit is active also when the Blower Auto input is off, that is, when the blower control is in manual override mode.

R[900] See above. Low Air PV forgiveness time. Default 30 s. R[903] A second lower limit of Air CV, expressed in %, used to protect the VFD from

overheating. If the Air CV stays below this value longer than the time set in R[902], the Blower VFD Go output is turned off. Default 10%.

R[902] Max time, in seconds, for the Air CV to stay below R[903]. Default 10s. R[896] VFD wake-up time. Time allowed for VFD to get ready after having been turned

off by a Fault or Emergency stop. R[897] Blower Run-Up time. Blower related parameters have to arrive within limits

during this time. If R[909] is set to 1, the Blower CV will be fixed at the value in R[877] during this time.

R[906] Blower VFD Fault allow time. This parameter was added to allow short fault indications from the Blower VFD. See also logical input Blw VFD Fault.


R[907] Blower FAR allow time. If the Blower VFD Frequency Arrival relay, connected to the Blw VFD at Spd logical input stays off longer than this time while the blower is running, the output Blw VFD NoAtSpd goes On.

R[908] Blower Oil pressure switch allow time. The Lo Blw Oil Pres logical input s allowed to stay Off for this time, before the Blw Oil Fail logical output goes On.

Hopper Pressure Control During normal feeding the pressure in the weigh hopper (HPr PV) must stay well above the pressure in the burner pipe (PPr PV). During filling, HPr PV must be reduced to the pressure in the Day Silo. Pressurization after the fill sequence is completed must happen quickly. There are two solenoid valves, operating on the secondary side of two pressure regulators, which is used for On/Off control of the HPr PV. The Hopper Pressure Setpoint (HPr SP) can be set directly by CCS, in ASCD[n].DTV[4]. This is called Override Control. It can

also be derived by adding a fixed over-pressure number to a low-pass filtered version of the burner pipe pressure (PPr PV). This is called Automatic Control. In Fallback and Local mode, Automatic Control is used. In Network Mode, the control method is selected by input Pres Auto.

HPr SP PressureTx

Air PV Conditioning

PPr PV

Low Pass Filter

Fast SolOn/Off

Slow SolOn/Off

HPr PV Conditioning The hopper pressure is measured by a pressure transmitter, producing a 4..20 mA output. The signal is connected to one of the analog inputs 2 – 9, normally 3, and passes through a 12 bit A/D converter, producing HPr PV as output. Parameters are: R[918] Input selector. 0 for Analog Input 2, 1 for Analog input 3 etc. A value of 8 can be

used for simulation purposes. R[920] A/D counts for ambient pressure (4 mA), nominally 778. R[921] A/D counts for Dsgn Pressure (20 mA), nominally 3890. R[922] A/D counts lower limit for credible analog input (3.2 mA), nominally 622. R[923] A/D counts upper limit for credible analog input (20.8 mA), nominally 4045. A

value greater than 4095 will disable the upper limit check. R[959] Credible Analog Input forgiveness time. The A/D counts are allowed to stay

outside the limits in R[922] and R[923] for this time period, without turning the Hpr Tx Bad output on.

NOTE The design pressure of the pressure transmitter has to agree with Dsgn Pressure, in Design Capacities. The live output from the A/D converter can be monitored in R[927].

PPr filtering The pipe pressure (PPr PV) is sampled at a high rate for safety reasons, and is fairly noisy. To be able to use the PPr PV to calculate the HPr PV, low pass filtering is required. Parameters: R[938] Number of PPr PV samples used to form the Average Pipe Pressure. The default

value is 20. With the default sample time of 200 ms, the averaging time is 4 seconds.


R[913] Desired difference between PPr PV and HPr PV. This value is used in Automatic Control to keep the hopper pressure above the pipe pressure.

The low pass filtered pipe pressure can be monitored in R[939].

HPr On/Off Controllers There are two different On/Off controllers, one for fast pressurization at feeder start-up or after a fill cycle, one to keep the hopper pressure constantly above the pipe pressure. Parameters: R[915] Hold-off pressure for the fast pressure solenoid. The fast solenoid is working with

a higher pressure than the slow. When HPr PV reaches HPr SP minus this hold-off pressure, the fast solenoid is turned off. This is to avoid overpressurization the hopper. Default 2.

R[916] Factor used to calculate the expected pipe pressure at start-up. The Coke SP is divided by this number, and the result is added to PPr PV and R[913] (the desired difference) to form a temporary HPr SP at feeder start-up. This is to avoid feedrate oscillations due to low hopper pressure. Default 130.

R[917] Pressure hysteresis for the slow solenoid. Default 0.1.

HPr Limits R[914] Max pressure. This is a safety limit. The HPr SP used by the On/Off controllers is

limited to this value. Default 15. R[924] Upper limit of the hopper pressure when depressurizing. The hopper pressure

has to go below this limit in order to complete a depressurizing sequence. See also De-pressurize the Hopper on page 70. Default 1.

R[925] Max allowed error (HPr SP – HPr PV). If the error exceeds this limit for a longer time than R[926], the output Lo Hpr PV goes on, typically causing a Warning. Default 2.

R[926] See R[925] above. Low PPr PV forgiveness time. Default 40 s.

PIPE TEMP AND PRESSURE The pipe temp and pressure are both measured using 4-20 mA transmitters, located between the blower and the feeder. The values found are used to calculate the air speed in the pipe. The pipe pressure value is critical to feeder operation, because it participates in setting the hopper pressure. The air speed in the pipe is critical, because is can not be allowed to go below the salination speed for the coke/air mix.

Pipe Temp measurement The pipe temperature is measured by a transmitter, producing a 4..20 mA output. The transmitter is typically located in the short section of pipe between the blower and RAL outlet. The signal is connected to one of the analog inputs 2 – 9, normally 6, and passes through a 12 bit A/D converter, producing Temp as output. Parameters are: R[940] Input selector. 0 for Analog Input 2, 1 for Analog input 3 etc. A value of 8 can be

used for simulation purposes. R[931] A/D counts for min transmitter temp (4 mA), nominally 778. R[932] A/D counts for Dsgn Temp (20 mA), nominally 3890. R[948] Temperaure at min transmitter temp, typically 0°C. R[933] A/D counts lower limit for credible analog input (3.2 mA), nominally 622. R[934] A/D counts upper limit for credible analog input (20.8 mA), nominally 4045. A


outside the limits in R[933] and R[934] for this time period, without turning the PPr Tx Bad output on.


NOTE The design temp of the transmitter has to agree with Dsgn Temp, in Design Capacities. The live output from the A/D converter can be monitored in R[949].

Temp Limits R[945] Max allowed temperature. If the temp pressure stays above this limit for the time

set in R[946], below, the logical output Hi Temp goes on. This output is typically configured to qualify a Warning. Default 145.

R[946] Low pipe pressure forgiveness time See R[935], above. Default 120 s. NOTE The output (counts) from the A/D converter can be monitored in R[949]. The engineering value is

available in R[947].

Pipe Pressure measurement The pipe pressure is measured by a pressure transmitter, producing a 4..20 mA output. The transmitter is typically located in the short section of pipe between the blower and RAL outlet. The signal is connected to one of the analog inputs 2 – 9, normally 5, and passes through a 12 bit A/D converter, producing PPr PV as output. Parameters are: R[930] Input selector. 0 for Analog Input 2, 1 for Analog input 3 etc. A value of 8 can be

used for simulation purposes. R[931] A/D counts for ambient pressure (4 mA), nominally 778. R[932] A/D counts for Dsgn Pressure (20 mA), nominally 3890. R[933] A/D counts lower limit for credible analog input (3.2 mA), nominally 622. R[934] A/D counts upper limit for credible analog input (20.8 mA), nominally 4045. A


outside the limits in R[933] and R[934] for this time period, without turning the PPr Tx Bad output on.

NOTE The design pressure of the pressure transmitter has to agree with Dsgn Pressure, in Design Capacities. The live output from the A/D converter can be monitored in R[929].

PPr Limits R[935] Min pipe pressure while running the blower. The intent with this limit is to detect a

pipe rupture. If the pipe pressure stays below this limit for the time set in R[936], below, the logical output Lo PPr PV goes on. This output is typically configured to qualify a Fault. Default 1.

R[936] Low pipe pressure forgiveness time See R[935], above. Default 0.5 s. NOTE The output (counts) from the A/D converter can be monitored in R[929]. The engineering value is

available in R[937]. There is also a low-pass filtered version in R[939]. See PPr filtering on page 25.

Air Speed Calculation The air speed in the pipe is calculated from air temp (Temp), pipe pressure (PPr PV), air flow (Air PV) and pipe diameter (Dia). The constants used in the formula are unit selection dependent. See Select Units on page 30. For °F, PSI, ft/s and Inches, the formula looks like this:

2Dia)969.14PVPrP(795.43)15.273Temp(PVAirSpeedAir•+•

+= ft/s

For °C, PSI, m/s and Inches (the default units selection):


+= m/s

For °C, kPa (kilopascal), m/s and mm:




+=

NOTE The engineering value is available in R[950].

m/s

R[953] Pipe diameter (Dia).

Air Speed Limits R[951] Min air speed while running the blower. If the speed stays below this limit for the

time set in R[952], below, the logical output Lo Air Speed goes on. This output is typically configured to qualify a Fault. Default 1 m/s.

R[952] Low pipe pressure forgiveness time See R[935], above. Default 3 s.

DIGITAL CONTROL SEQUENCES There are two perpetual control sequences, one for the Blower and one for the Feeder and hopper pressurization. They are implemented as State Machines, with a specific State Variable (State) that has an assigned integer value for every possible state.

Blower States and Sequences The bower is controlled by a state machine algorithm. The state variable, Blw State R[895], is useful for status indication and troubleshooting. There is a text representation in the Main and Graph screen of the state. See Main Screens on page 11. The states and their transitions are listed in this table. # State Text Description Normal

Exits Blw On Blw Off

0 Stopped Idle Engage 1 Engage Turn VFD on (time) Run-Up Idle 2 Run-Up Allow for blower to ramp up Running Stopping 3 Running Normal run condition Stopping 4 Stopping Allow for blower to spin down (time) Idle

Feeder States and Sequences

The feeder is controlled by a state machine algorithm. The state variable, Fdr State R[300], is useful for status indication and troubleshooting. The states and their transitions are listed in this table. A transient state is only active for one state machine tick, normally 0.2 s.

During Engage and Run-Up, the blower limit checks are not engaged. During Engage, when all blower parameters are within limits, or when the Blower Run-Up time in R[897] has expired, state changes to Running. See Blower Limits on page 24.

# State Text Description Normal Exits Fdr ON Fdr OFF Clean ON Clean OFF Fill Start Fill Stop 0 Stopped Idle Init Start 1 Init Start Transient. Weight assessment

at start Hpr Pres Up or Init Fill

Vent Stop Init Clean Init Fill

2 Hpr Pres Up Repressurize at start Hold Star Vent Stop Init Fill 3 Hold Start Stabilize after start or aborted fill Init FeederI or

Init Fill Vent Stop Hold Clean Init Fill

4 Init Feeder Transient. Set timers Feeding Vent Stop 5 Feeding Normal feeding Init Fill Vent Stop Init Clean Init Fill 6 Init Fill Transient. Set timers. Vent Fill Vent Stop Init Clean 7 Vent Fill Silo aeration, VEG open Open VEG Vent Stop Close VEG 8 Open VEG Wait for VEG open Open SEG Close SEG Close SEG 9 Open SEG Wait for SEG open Filling Close SEG Close SEG 10 Filling Wait for filled hopper Close FIG Close FIG Close FIG Close FIG 11 Close FIG Wait for FIG closed Bleed Prs Close SEG Close SEG 12 Bleed Prs Hold SEG open. Time. Close SEG Vent Stop 13 Close SEG Wait for SEG closed Close VEG Vent Stop 14 Close VEG Wait for VEG closed Re-Pressure Vent Stop 15 Re-Pressure Pressurize hopper Hold Feed Vent Stop 16 Hold Feed Stabilize after fill Init FeederI or

Init Fill Vent Stop Hold Clean Init FillI

17 Vent Stop Depressurize before stop Stopped 18 Hold Clean Stabilize before clean Cleaning or

Emptying Vent Stop Hold Start

19 Init Clean Transient. Set timers Cleaning Vent Stop 20 Cleaning Feed to empty Emptying Vent Stop Hold Start 21 Emptying Feed extra time Vent Clean Vent Stop Init Start 22 Vent Clean Depressurize after cleanout Cleaned Vent Stop Init Start 23 Cleaned Cleanout Done Stopped

29 of 91 01/12/2005/Lars 30.11.EX O&M Manual

SETTING UP YOUR CONTROLLER Most commonly used parameters are set in sub-menus of this screen.

Settings Menu

There are several parameters that can’t be reached from here. They are set, using the Register Editor. See page 91.

Select Units The MC³ supports three different set of engineering units: • All Metric • All Imperial • A popular combination of the two. This is the default. Use the Up or Down arrow buttons to scroll through the list of units until the desired combination appears in the center box, then push the Settings Menu button.

Select Units Menu

NOTE: It may be necessary, after selecting the units, to update the decimal point selection values. See below. The resolution should be reasonable, typically around 1000 divisions.

Set Dec Pts Internally, the MC³ Controller uses floating-point numbers. Any changes to the decimal point settings affect only the display of the values. It is a good idea to set the number of decimal places so that you get 3 or 4 digit representation of the value. The minimum number of decimal places is 0 and the maximum is 4.

Design Capacities These parameters are the design values relating to the maximum useful weight, feedrate, pressure, temp and air flow The Dsgn Feedrate is important for the CSG performance. This value should nominally be set to the maximum obtainable coke feedrate when the RAL s running at full speed. The Dsgn Weight is important, because it is used in Quick Setup (page 35) and for scaling the Weight analog output. The Dsgn Pressure must equal to the full scale pressure of the pressure transmitters. The Dsgn Temp must equal the full scale temp of the temp transmitter.


The Dsgn Air Flow must equal the full scale flow of the air flow transmitter.

Control Settings The MC³ uses a PID (Proportional, Integral, Derivative) as one of its control algorithms, if the PID Control logical input is ON. Another algorithm, CSG (Conditional Step Gravimetric) is used if the CSG control logical input is ON. See Logical Inputs, on page 42. If both are on, a combination of the two is used. See See Loss-In-Weight Feedrate Control on page 17. To tune the algorithms to a particular feeder, changes can be made to these parameters. It is possible to let the controller adjust the Gain, Integral, Derivative, Average Slots and Loss Slots automatically. See the Autotune input in Logical Inputs on page 42. When the MC³ is in control, it is the MC³’s job to keep the coke feedrate at the setpoint. This is accomplished by minimizing the deviation between the setpoint and the feedrate. The PID algorithm uses the deviation to adjust the Fdr CV. The CSG algorithm uses the Feed Factor. There are as many ways to tune the PID parameters as there are control engineers. We recommend you use whatever tuning method you are most familiar with.

Gain This is the PID closed loop gain, expressed in %. The settings affect all three PID controller components (Proportional, Integral and Derivative). Too much gain can cause the feeder to oscillate. Too little gain gives you sluggish control. A good starting point is a setting of 20% of the feedfactor. The feedfactor for a running feeder can be found in the Main Screens. See page 11. If you don’t know the feedfactor, assume it is 50%, and use a Gain Setting of 10%.

Integral The PID integral component uses the accumulated (integrated) deviation over time to adjust the Fdr CV. The Integral parameter, expressed in 1/sec, determines how fast the accumulation takes place. The Integral function will, over time, make the deviation go to zero, assuming that everything else is in steady state. A good starting point is to set the parameter according to this formula:

SampleTimetsAverageSlo2Integral⋅

=

See Average Slots on page 31 and Sample Rate on page 36. Typical setting is 0.1 /s.

Derivative The PID derivative component uses the trend of the deviation to adjust the Fdr CV. The derivative parameter, expressed in seconds, determines the sensitivity to trend changes. The Derivative function will react early to changes. A good starting point is to set the parameter according to this formula:

SampleTimetsAverageSlo01.0Derivative ⋅⋅=

See Average Slots on page 31 and Sample Rate on page 36. Typical setting is 0.2 s.

SCR Accel and SCR Decel These two parameters provide limitations on the rate of change of the Fdr CV, expressed in percent per second. The purpose is to avoid damage to the motor drive circuit, motor, and drive mechanism. Default is 100%/s, meaning that the output can change 100% in 1 second. Lowering this parameter makes the output move slower. If the drive is equipped with ramp limiting, it is better to keep this parameter at default and use the drive limitations instead.

Average Slots When the feeder is running, the weight may fluctuate, due to the effect of the RAL or noise. An averaging weight filter is in place to suppress this noise. This parameter determines how many weight samples are used in the averaging calculations. Generally, the longer the discharge time, the higher the number of slots. A typical setting is


50SampleTimeeTimeargDischtsAverageSlo

⋅=

The Discharge Time must be calculated in seconds, using the Fill Point, Heel point and Design Feedrate. If the Design Feedrate is expressed in kg/h or lb/h, the Discharge Time is

( )rateDesignFeed

3600intHeelPointFillPoeTimeargDisch ⋅−=

If the Design Feedrate is expressed in kg/min or lb/min, the Discharge Time is ( )

rateDesignFeed60intHeelPointFillPoeTimeargDisch ⋅−=

The permitted range is 1 to 500. There is also an upper limit, which may be lower than 500, based on the fact that the delay in the average value must be less than 10% of the Discharge Time. The default value is 100.

Loss Slots This parameter determines how many samples are used to determine the weigh loss, which is used to calculate the feedrate. It is normally set to the same value as the Average Slots. The same limits apply.

Max Fdr Span, Fdr Samples This is how much the weight loss may change over the set Fdr Samples, for the feedrate to be considered stable. The default is 2.5% of the Design Feedrate. It can be increased or decreased, depending on what kind of control is most desirable. Increasing the value also increases the Signal Quality. See Main Screens on page 11. The controller will act faster. When running both the PID and CSG control, the PID will be favored. Decreasing the value decreases the Signal Quality. The system will be less sensitive to disturbances. The controller will act slower, and favor the CSG.

Min Cred FR The Minimum Credible Feedrat

mc³ 30.11 - merrick industries, inc.merrick-inc.com/legacypages/mct/mc3apps/3011_o12.pdfmc³...

Documents