1. APPLICATION AND BASIC SPECIFICATIONS Model Model CS2024 CS2024 coal coal Feede Feederr is a microp microproc rocess essor or contro controll belt belt feede feederr featur featuring ing electr electroni onicc weighing and automatic speed regulation. It is used to feed precision calibrated coal to the pulverizer with functions of automatic regulation and control. The feeder is applied in a heat power plant of high degree of automatic control. It is an essential associate equipment to a coal-fired boiler of pressure or suction operation.
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BASIC SPECIFICATIONS DESCRIPTION BASIC SPECIFICATION Feedrate 10-100 Feeder Inlet Diameter 629 Center Di Distance Be Between In Inlet And 2135 Discharge Belt Drive 3 Cleanout Conveyor Motor Power 0.25
6
Feeder Over Dimensions (L×W×H) 3360×1700×1620
ITEM 1 2 3
7
Weight Of Feeder
4
UNIT T/h mm mm KW KW mm TON
2. CONSTRUCTION The feeder is comprised of feeder frame, feeder belt assembly, cleanout conveyor, weighing system, coal plug-gage and coal void signaling devices. lubrication piping and electric wiring, microprocessor control cabinet. 2.1 The feeder frame is comprised of casing, inlet and discharge end doors, side doors and internal feeder light. The casing is an enclosed weldment that can resist explosive pressure up to 0.34 0.34 MPa MPa to meet meet requir requireme ements nts specif specified ied in NFPA NFPA Code 85F by Nation National al Fire Fire Protection Association of the U.S.A. Guide plate and skirt are provided in the inlet to form fixed fixed section section of coal coal flow flow on the belt after coal is droppe dropped d into into the feeder feeder.. All parts contacting coal are made of OCr18Ni9 stainless steel. Inlet and discharge end doors are firmly bolted to the casing to ensure perfect seal. All doors are optional to open leftward or rightward. sight glasses are provided on all doors and nozzles are equipped interior of sight glasses to clear off accumulated coal dust by pressurized air or water. Internal feeder light of sealed construction enables observation of internal feeder operation. 2.2 The feeder belt assembly is comprised of motor, reducer, drive pulley, take-up pulley, tension roll, belt supporting plate and the belt. The belt is rimmed and provided with a vguide at the inner belt center to engage with grooves on rollers to keep good belt tracking. At the end of drive pulley scraper is equipped to clear off coal adhered on the outer surface of belt. The tension roll is located at the midpoint midpoint of bell travel, it keeps the belt under under a fixed tens tension ion to obta obtain in opti optimu mum m weig weighi hing ng effe effect ct.. The The belt belt tens tensio ion n vari varies es with with diffe differe rent nt temperature and with temperature variation. Intensive observations should be frequently done and make tension tension adjustment adjustment by means means of the take-up take-up screws. screws. Scaled Scaled indicator indicator is equipped interior of side door to the feeder, the tension roll should be regulated to locate its center at the midpoint of the indicator. Totally enclosed, variable frequency motor is used to
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drive the belt. Which is comprised of a 3-phase ac motor, a tacho-generator. A variable frequency driver and variable frequency motor provide an ac stepless speed regulation .It can provide a smooth and stepless speed regulation within a rather broad range. The feeder belt reducer reducer is a two-stage reducer, reducer, comprised of cylindrical gears and worm wheel. The worm wheel is oil bath lubricated while a cycloidal pump in the reducer pumps oil via a hole in the worm shaft to lubricate the gears. The drive pulley is driven through a pin type coupling which is mounted on the worm wheel shaft. 2.3 The coal void signaling device is located above the belt. When there is no coal on the belt, the paddle of signaling device deflects and causes cam on the axle of device to turn and actuate the limit switch, either to control the belt drive motor, or to initiate the coal bunker vibrator, or to output a signal back to control room to signify no coal on the belt. The customer customer may determine determine,, according according to operating operating system requireme requirements, nts, which which of these functions shall be performed. The coal void signal can also deactivate integrated weight and can prevent feeder calibration with coal on the belt. The coal plug-gage signaling device locates at the feeder discharge and is of identical construction to the coal void signaling device. The limit switch outputs signal signifying coal flow plug-gage at discharge and stops the feeder operation. 2.4 The weighing system is located between feeder inlet and drive pulley. All of the three roller surfaces are finely finished, of which two rollers are fixed on the feeder casing to form a weigh span and the third roller hangs on a pair of load cells. Coal weight on the belt acts on load cells to output a signal. Output signal from the calibrated load cells signifies unit length coal weight weight and frequency frequency signal signal from the tacho-generator signifies belt speed. The The microprocessor controls integrates both signals to obtain the feedrate. Test weights are located below the load cells and the weigh roller. During feeder operation, test weights are supported by the weigh arm and the eccentric disc to part from the weigh roller. On calibration, turn the ratchet handle so that the eccentric disc is turned to make test weights hang on the load cells to check if the weight signal is correct. 2.5 Cleanout conveyor is used to clean off coal accumulated on inner floor of the feeder. During feeder operation, coal adhered on the belt is cleaned off by a scraper and dirt accumulated on inner belt is dropped off from both ends of the self-cleansing type tension roll. As seat air also generates dirt, dirt will deposit on the inner floor to cause self-ignition if it is not timely cleaned off. Cleanout chain is driven by a motor via a reducer, wing type chain scrapes off the dirt to the feeder discharge. It is recommended that the cleanout conveyor is synchronously operated with the feed belt operation so that coal accumulation interior of the feeder is minimized. Furthermore, continue clean off is also of advantage both to reduce feedrate error and to prevent chain pin from adhesion and rustiness. The cleanout conveyor conveyor reducer is comprised comprised of cylindrica cylindricall gears gears and worm wheel. wheel. Electric Electric overload protection is provided for the cleanout conveyor drive motor, when overload the cleanout conveyor conveyor motor’s power is automatica automatically lly turn off by electroni electronicc overload overload relay to stop reducer. 2.6 Seal air inlet is located below the feeder inlet with a flange-type connection for the -2-
drive the belt. Which is comprised of a 3-phase ac motor, a tacho-generator. A variable frequency driver and variable frequency motor provide an ac stepless speed regulation .It can provide a smooth and stepless speed regulation within a rather broad range. The feeder belt reducer reducer is a two-stage reducer, reducer, comprised of cylindrical gears and worm wheel. The worm wheel is oil bath lubricated while a cycloidal pump in the reducer pumps oil via a hole in the worm shaft to lubricate the gears. The drive pulley is driven through a pin type coupling which is mounted on the worm wheel shaft. 2.3 The coal void signaling device is located above the belt. When there is no coal on the belt, the paddle of signaling device deflects and causes cam on the axle of device to turn and actuate the limit switch, either to control the belt drive motor, or to initiate the coal bunker vibrator, or to output a signal back to control room to signify no coal on the belt. The customer customer may determine determine,, according according to operating operating system requireme requirements, nts, which which of these functions shall be performed. The coal void signal can also deactivate integrated weight and can prevent feeder calibration with coal on the belt. The coal plug-gage signaling device locates at the feeder discharge and is of identical construction to the coal void signaling device. The limit switch outputs signal signifying coal flow plug-gage at discharge and stops the feeder operation. 2.4 The weighing system is located between feeder inlet and drive pulley. All of the three roller surfaces are finely finished, of which two rollers are fixed on the feeder casing to form a weigh span and the third roller hangs on a pair of load cells. Coal weight on the belt acts on load cells to output a signal. Output signal from the calibrated load cells signifies unit length coal weight weight and frequency frequency signal signal from the tacho-generator signifies belt speed. The The microprocessor controls integrates both signals to obtain the feedrate. Test weights are located below the load cells and the weigh roller. During feeder operation, test weights are supported by the weigh arm and the eccentric disc to part from the weigh roller. On calibration, turn the ratchet handle so that the eccentric disc is turned to make test weights hang on the load cells to check if the weight signal is correct. 2.5 Cleanout conveyor is used to clean off coal accumulated on inner floor of the feeder. During feeder operation, coal adhered on the belt is cleaned off by a scraper and dirt accumulated on inner belt is dropped off from both ends of the self-cleansing type tension roll. As seat air also generates dirt, dirt will deposit on the inner floor to cause self-ignition if it is not timely cleaned off. Cleanout chain is driven by a motor via a reducer, wing type chain scrapes off the dirt to the feeder discharge. It is recommended that the cleanout conveyor is synchronously operated with the feed belt operation so that coal accumulation interior of the feeder is minimized. Furthermore, continue clean off is also of advantage both to reduce feedrate error and to prevent chain pin from adhesion and rustiness. The cleanout conveyor conveyor reducer is comprised comprised of cylindrica cylindricall gears gears and worm wheel. wheel. Electric Electric overload protection is provided for the cleanout conveyor drive motor, when overload the cleanout conveyor conveyor motor’s power is automatica automatically lly turn off by electroni electronicc overload overload relay to stop reducer. 2.6 Seal air inlet is located below the feeder inlet with a flange-type connection for the -2-
customer to supply seal air into the feeder. feeder. Under pressure operation status, the feeder needs sear air to prevent pulverizer heat air from reversing into the feeder through the inlet. The seal air pressure is 60
～
245 Pa higher than
the pulverizer pulverizer inlet pressure. pressure. The required required seal air delivery delivery is the sum of air leakage leakage from hopper of downspout and the amount required to form a pressure difference between inlets of the feeder and of the pulverizer. pulverizer. The feeder itself is construed as of reliable sealed with no leak. A threaded hole is provided near the feeder inlet for adapting a pressure gauge to test the feeder internal pressure. The hole must be plugged if a pressure gauge is not equipped. If the seal air pressure is too low, it will cause the pulverizer heat air reverse back to the feeder feeder so that coal dusts will stagnate stagnate at the door frames and at protrusion protrusion parts parts to induce self-ignition. If either the seal air pressure or its flow rate is too high, it will blow coal particles off the belt to degrade weighing accuracy and to increase the load on clean out scrapers. Furthermore, if the seal air flow rate is too large, dustiness is prone to be formed interior of the sight sight glass glass to hamper hamper observ observati ation. on. Theref Therefore ore,, suitab suitable le seal seal air pressure pressure has to be adjusted. 2.7 Except that the reducer is oil bath lubricated, grease lubrication is used for all other parts. All lubricating points within the feeder are connected with hoses that extend outside the feeder so that, lubrication can be performed without opening doors to the feeder. Flexible tubes are used for electric wiring, cables are led into the feeder through the tubes so that casing seal is kept. 2.8 Control cabinet is installed on the body of the feeder. Power supply switch is located in cabinet. It can turn on or turn off the power. 2.9 Microproc Microprocessor essor control board, board, power supply board board signal signal convertin converting g board, board, variable variable frequency driver disconnect switch, transformers, fuses and relays are installed within the microprocessor control cabinet which is mounted on the feeder casing. On the panel of cabinet microprocessor display keyboard and switches SSC and FLS are equipped. For their functions. Please see CHAPTER 4-SYSTEM COMPONENT DESCRIPTION.
3. ACCEPTANCE AND INSTALLATION INSTALLATION 3.1 Completion and perfect packing should be examined on receiving the feeder. If necessary, open packing box is permissible but packing bags shall not be damaged. Having checked, repack as it was and inquire timely for any doubt. 3.2 If the feeder is not to be installed right after arriving on jobsite then proper maintenance should be carried out. 3.2.1 Properly maintain the original packing boxes to avoid being damaged. Storage area should be kept clean and carry out frequent inspections. 3.2.2 Inspect the protective film and drying-agent bags which are packed in the box before ex-3-
work delivery and keep them in good order. order. 3,2.3 Equipments are to be stored indoors, ventilated and waterproof hoods are to be provided if equipments have to be stored outdoors. Pillows should be placed under the packing box and drying-agent bags should be put within the hoods and carry out monthly inspection for assurance. 3.2.4 In order to facilitate inspection and maintenance packing box shall not be stacked one over the other. 3.2.5 Packing boxes of feeder accessory and of small hard wares are to be stored in a dry place. 3.2.6 3.2.6 Packi Packing ng boxes boxes of electr electric ic parts parts (elec (electro tronic nics), s), such such as power power supply supply cabin cabinet et and microprocessor control cabinet etc. shall be stored indoors with heatproof and ventilation means. 3.2.7 Regular inspection of drying-agent in boxes of electric parts (electronics) is of necessity. Replace if failure is found. 3.3 Regular inspection and maintenance is of necessity during period of storage. 3.3.1 Note that in each routine maintenance only open those packing in which the parts that need to be maintained are packed. Having accomplished maintain, repack them as they were. 3.3.2 Turn the belt drive motor and the cleanout conveyor drive motor by hand respectively 200 revolutions every month to make each part in motion and be lubricated. Place the belt after every turn in a different location to the previous one so that belt deformation caused by resting resting at the same location for a longs time is avoided. 3.3.3 Turn the tension roll by hand monthly. 3.3.4 Inspect monthly for the perfection of plastic packing film and for the validity of dryingagent. 3.3.5 Lubricate all bearings tri-monthly. 3.3.6 Replace lubricating oil in the reducer annually. 3.3.7 Throughly cleanse and lubricate cleanout conveyor chain links with rust-proof oil or gear lubrication oil annually. annually. 3.4 For a storage period of more than one year: 3.4.1 Fill the reducer full of lubrication oil and seal all breathers. Keep the lubrication oil until installation is to be carried out and then replace and refill the oil to specified level. 3.4.2 Remove the feeder belt and place it laterally in a dry cool place. Re-fold the belt trimonthly in order to change bend locations and to avoid bend marks. 3.4.3 Having Having removed removed the belt, turn monthly by hand the weigh rollers, the tension roll, the take-up pulley and the driven sprocket shaft of cleanout conveyor to make each part in motion and be lubricated. 3.5 Installation of equipments 3.5.1 As tension roll and weigh rollers are fixed by woodblocks when they are packed, do not dismantle for assembly until the feeder has been installed onto the foundation. 3.5.2 Beside applying the feeder accessory, a leveling ruler about 600 mm long and pillowing blocks of 100×100 mm with different thickness should also be provided for installation. -4-
3.5.3 Open the packing box and remove all packing material. However, do not take packing film off the motor and off the reducer temporarily. 3.5.4 Place the feeder onto the foundation, make alignment for anchor bolt holes, put on bolts and nuts but do not turn the nuts firmly. 3.5.5 Place both checking bars from the feeder accessory onto either side of two weigh span rollers surface, then confirm the level of feeder with the leveling ruler. Adjust the level by means of adjusting blocks under the feeder. Adjusting blocks must be placed as near to anchor bolts as possible so that the feeder casing will not buckle as anchor bolts are firmly screwed. 3.5.6 The transverse level of feeder is checked by the weigh span roller which is adjacent to the feeder inlet. 3.5.7 Make final leveling after the second grouting and then firmly screw the four anchor bolts. 3.5.8 Associated equipments such as downspout, coupling and discharge bunker etc are to be assembled only after the feeder is firmly fixed. 3.5.9 The coal valve upstream of feeder upper downspout should be closed. When the feeder is installed and the upper downspout is not yet assembled, the feeder inlet should be temporarily covered with a robust cover which should be waterproof and dustproof. 3.5.10 Connect seal air duct to the feeder seal air inlet. 3.5.11 Assemble the coal void signaling device and the coal plug-gage signaling device. 3.5.12 Replace the lubrication oil in reducers of belt drive and of cleanout conveyor drive. 3.5.13 Inspect all mechanic jointed parts. 3.5.14 Assemble the microprocessor control cabinet onto the feeder. 3.5.15 Inspect all electric parts and contactors. Rub off rust and make fixation for loosened parts. 3.5.16 Inspect and confirm that all wirings for feeder control system are correct without error avoid that circuit board for control be seriously damaged when they are energized. 3.5.17 Assemble separately packed PC boards onto the microprocessor control cabinet. 3.5.18 Connect load cells to PC boards by receptacle plugs. 3.5.19 All electric cabinets should be reliably grounded. 3.5.20 Clean out dirt and foreign material interior of the feeder. Inspect carefully the appearance of feeder and make timely repair for any damage. Replace sight-glass for any scratch mark damage. 3.5.21 After installation keep on inspection and maintenance as required for period of storage until the feeder is to be operated. 3.5.22 Do not energize until the operated is familiar with the construction of the feeder and knows how to operate it. Please inform the manufacturer one month prior to operating the feeder for detail information.
4. SYSTEM COMPONENT DESCRIPTION 4.1 FEEDER MICROPROCESSOR CONTROLS
The microprocessor feeder electronics control system is designed to operate in industrial and power plant environments where harsh conditions and frequent power disturbance exist. It -5-
uses special circuits, software subroutines, and nonvolatile memories to store data, programming and operating parameter. This allows the system to recover and keep the feeder running under control after a momentary power loss. The microprocessor is package in the feeder NEMA 4 control enclosure with a glass door for keyboard access. The keyboard is part of an environmentally sealed display panel that is gasket against the enclosure door. The feeder control consists of three hardware packages: a power supply, a CPU board, and a motor speed control. Additional input and output device are available and can be formatted to a variedly of requirements, both digital and analog. 4.1.1 Power Supply
The power supply board converts the customer’s ac power into the regulated low voltages required to operate the control electronics. Input to the power supply is 110 V ac @ 50-60 hertz. This is converted by transformers into a series of low voltages which are rectified, filtered, and regulated. The voltages and the electronics they supply listed below Voltage +5 V dc
Device Microprocessor and Transistor-Transistor Logic
(TTL) Display, and Converter Cards +10 V dc Load Cells and Amplifiers -10 V dc Amplifiers +15 V dc Calibration Probes -15 V dc Opto-coupled Inputs and Calibration Probes The ± 15 volt supplies are isolated from the logic and amplifier Supplies. In addition, there is an unregulated voltage which is used to energize relay coils, provided from the filter side of the 20 Volt supply. There are also two 20 V ac supplies for the isolated feedrate converter cards (A3) and speed demand converter cards (A2). Each converter card has on-board filters and regulators. The applied voltage from the power supply to the controller board (CPU board) is provided through a connector with six conductors. 4.1.l.1 Input/Output Circuit Description
Located on the power supply board, the input/output circuits isolate the microprocessor and its associated circuitry from the electrical and control systems of the plant to eliminate malfunction from transients or noise. All inputs to the CPU board are optically isolated at the power supply board. The system is designed to accept a maximum of twelve digital inputs or contact closures, a belt speed signal and an analog demand signal. All output signals are similarly isolated and include: seven power relays (each with two Form contacts), one read relay with two Form A contacts and two analog signals. Logic signals are transmitted to and from the power supply board to the microprocessor through a 50-pin ribbon cable. A typical isolated input operates as follows: incoming signals are used to bias a light emitting diode whose light output is directly proportional to input current. The light output of the diode is optically coupled to the base of a phototransistor. The collector lead of the transistor sinks current from the microprocessor to ground. Thus, inputs and outputs are electrically isolated. A typical isolated output operates as follows. CPU signals are used to bias a light emitting diode and an optically coupled transistor, as with inputs. However, the transistor emitter sinks current to energize a relay coil and the relay contacts provide the output signal. 4.1.1.2 Input Current to Frequency Converter Card (Al)
The function of the input signal converter is to convert the customer fuel demand signal to -6-
normalized 0 to 10 kHz signal for interfacing with the microprocessor system. The fuel demand signal is a current signal of 4
20 mA.
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4.1.1.3 Output Frequency to Current converter Card (A3)
The frequency to current converter card is used as a feedback module for customers who require a feedrate feedback. This circuit allows the digital electronics of the microprocessor to output a digital signal, while the customer receives a current feedback signal of 4
20 mA
～
. 4.1.1.4 Frequency to Current Converter Card (A2)
The frequency convert card is used to convert a digital motor speed demand signal into an analog speed demand signal for variable frequency driver. 4.1.2 CPU Board
The CPU board assembly is mounted against the interior of the door to the microprocessor control cabinet and is electromagnetic ally shielded from the rest of the feeder electrical controls. It contains the microprocessor, memories, digital interface circuits, and a keyboard/display. The analog circuits used to amplify and convert the load cell signals to a digital form are located on this board. The CPU board is the principal mechanism through which control of the system is achieved. Digital inputs and keyboard commands are processed by software algorithms which then route signals either to digital outputs or to the display as required. All digital I/O interfaces are isolated by circuits on the power supply board which prevent damage due to transients and prevent operational malfunction due to noise. Interfacing between the microprocessor and the analog parts of the system is accomplished by conversion circuits. Signals which pass from an external analog device to the microprocessor first must pass through an analog to digital converter (voltage to binary number). If the microprocessor must operate an external analog device, its output is sent in the form of a frequency to a frequency to voltage or current Converter card. This device is a digital to analog converter since its converts a binary number to either a v oltage or a current. The A/D and D/A conversions are made with a resolution of one part in 4000 or 0.025 percent. The software is contained in a permanent memory to the microprocessor control system. The software is written so that the most important system activities (such as the motor speed loop, and demand signal input) are processed fast enough to allow good control to be achieved, while less important signals (such as relay outputs) are processed at a slower speed. This time multiplexing concept in the software program allows for better control of the process when a great number of tasks must be performed. The only inputs directly accessing the CPU board are the keyboard and the load cells. All other I/0 signals pass through optical isolation circuits located on the power supply, which gives the system excellent noise immunity. 4.1.2.1 Microprocessor Memory
Programming of the microprocessor is done in assembly language, which provides the operating speed required for maximum performance and reduces the memory space required to store the operating program. The system utilizes either 8K or 16K bytes of available memory for program storage, depending on application requirements and memory circuits used. There are also 2K bytes of random-access memory (RAM) for temporary storage of -7-
data during operation, and two nonvolatile memories for permanent and noise-immune storage of operating parameters and system totalizes. The microprocessor accesses a type of permanent read only memory (ROM) called a UV erasable EPROM for all operating instructions which form the system software program. This ensures that the control program instructions are not lest during a power interruption. All operations involving the microprocessor utilize the transfer of information to and from memory. As the CPU executes its program by reading instructions from EPROM, data may be needed from one of the I/0 interface chips, EEPROM, or NVRAM. This data may be stored in RAM for later processing of stored directly in the CPU in a storage location called a register. After the data is acted upon by the CPU, it may be stored in either its original memory location or in another. In all cases, the use of memory for storage of programs, data, and even memory addresses is an essential part of the microprocessor system. 4.1.2.2 Power Interrupt Protection Circuit
During operation, a temporary power interrupt may occur. This type of power failure may be frequent and if the feeder memory data is erased during the interrupt, can shut down feeder operations even after power has been restored. To prevent this, a power interrupt protection circuit has been designed into the microprocessor controls which stores all incoming and outgoing data, and all operating parameters, as soon as the start of a power failure is detected. This allows the feeder to recover and keeps the system operating in an orderly manner when power is restored after a failure. 4.1.2.3 Display Keyboard
Commands are entered to the controls via the keyboard on the front panel of the microprocessor cabinet. To operate the keyboard, it is necessary to open the small outer door by loosening its two thumbscrews. This door must remain tightly closed when the keyboard is not being used to maintain the NEMA rating of the control enclosure. The clear window allows the operation of the feeder to be checked without opening the door.
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The keyboard contains keys of three colors: white, blue, and yellow. The white keys are the standard REMOTE-OFF-LOCAL selection of feeder operating mode and will be the keys most frequently used. The blue keys are functions and numbers that are activated simply by pressing them in the proper order. The yellow keys are additional functions and are accessed by first pressing the solid yellow SHIFT key at the lower right corner of the keyboard. REMOTE (white) allows the feeder to be controlled from the customer run permissive
contacts and demand signal. OFF (white) deactivates the feeder. (Belt JOG (blue) and feeder calibration are possible only after deactivating the feeder.) LOCAL (white) operates the feeder at a selectable speed. There cannot be material on the belt during LOCAL operation or else the feeder trips after a two-second delay. The JOG (blue) key may be pressed and held to operate the belt drive motor for as long as the key is pressed. This command is used to check motor operation or to slowly move the belt for service. The feeder must first be in the OFF mode to jog the belt. The belt drive motor can be reversibly operated by pressing OFF- SHIFT-F2 for service. Display Selection Keys
The upper eight-digit display (TCI-1) normally shows the totalized weight of material delivered in kilograms. It is also used for number entry and display of special functions. Whenever the display is not otherwise in use it reverts to show the totalized weight. There are three totalized weight display selection: gravimetric only, volumetric only, or a total of both. Gravimetric is defined as material delivered with a functioning weighing system. Volumetric is defined as material delivered when the weigh system is at fault and the amount of material is delivered using an assumed weight on the weigh span. The assumed weight is an average of what the material was known to weigh before the weighing system faulted. This weight is used to determine a nominal material density. Volumetric totalization has no -9-
guarantee of accuracy and may be at considerable error if material density is not uniform. Therefore, a separate total is kept. Total is the sum of both the gravimetric and volumetric weights. Pressing TOTAL (blue) selects the totalizer mode on the eight- digit display. Repeated pressings will cycle through each of the three modes. One of the three red indicators immediately below the display is energized to show which mode is active, GRAV, TOTAL, & or VOL. The mode being displayed in no way affects how all three of the totalizers are updated internally. Whenever one of the totalizers becomes filled to capacity, it will roll over and begin again at zero but Will have no effect on the other two totalizers. From time to time it may be desirable to reset the three totalizers back to zero. To do this, press: SHIFT (yellow) TOTAL RESET (yellow)
The lower four-digit display (FRI-1) shows the feed RATE in tons per hour, the motor speed, or the DENSITY (kg/m 3) of material on the belt. Simply pressing the correct blue selector key calls up the appropriate display. One of the three red indicators immediately below the display is energized to show which display is active. DENSITY (blue) shows the density of material on the belt in the gravimetric mode in actual
kilograms per cubic meter. In the volumetric mode, the density shown is based on an average density determined before the weight system faulted. RPM (blue) shows the feeder belt drive motor speed. RATE (blue) shows the operating feedrate of the feeder when in the gravimetric mode or the
equivalent feedrate using the average density of the material when in the volumetric mode. Display Indicators
The ten indicators on the keyboard panel give information as to the current operational status of the feeder: a. RUNNING (green) is energized whenever the belt drive motor is energized. b.
READY (green) is energized whenever the microprocessor is powered and the operation
of its core components has been verified. c.
FEEDING (green) is energized when the motor is energized and there is material on the
belt, as sensed by paddle switch (LSFB) d.
REMOTE (green) is energized when the feeder is operating in the REMOTE mode
under control of the customer's process control system. e. CALIBRATIOON (amber) is energized throughout the feeder calibration procedure. f.
ADD WEIGHT (amber) prompts the operator to mount the calibrating test weights at the
appropriate point in the calibrating procedure. g.
ALARM (red) indicates that a problem exists which requires attention but which is not
serious enough to immediately stop feeder operation. h.
TRIP (red) indicates that a problem-exists which is serious enough that feeder operation
has been stopped. i.
VOLUMETRIC (red) indicates that a fault exists in the weighing system or its
electronics which prevents the feeder from operating in the gravimetric mode. j.
MAINTENANCE (red) indicates that routine lubrication and service of the feeder is now
due. For a lubrication schedule and maintenance procedure, refer to Chapter 6 of this manual. -10-
Diagnostic Error Codes
Whenever an ALARM or TRIP condition occurs, an error code number is stored internally to identify the source of the problem. To access the error code, press: SHIFT (Yellow) ERROR RECALL (yellow)
A number will appear in the totalizer display. To decode the number, refer to Section 7.3. 4.1.2.4 Functional Specifications of Microprocessor Controls INPUT POWER: 110 V ac ±10%,5O-60 Hz @ 100 VA. DIGIAL INPUTS: Contact closures from system -15 V dc to opto-coupler input @ 20 mA,
optically isolated from low level logic signals. Functions: Material on Belt (LSFB)
Discharge Plug-gage (LSFD) Feeder Motor Starter (FFR ) Feeder Start (FS) One Spare Channel DIGITAL OUTPUTS: Relays controlled by optically isolated low
Level signals. Relays: KI-K7 each With 2 form C contacts rated at 117 V ac @ 5 A or 125 V dc @ 5 A
resistive loading. Functions: Trip (K1)
Reverse Motor (K2) Remote (K3) Feeding Volumetric (K4) Feeding Material (K5) Feeder Run (K6) Alarm (K7) Relay: K8 dry reed relay, with 2 Form A contacts, rated at 100 V dc max, 500 ma max, 10 VA max, make or break. Function: Remote data logging pulse for TCI
(Total Material Integrator) Pulse duration 200 msec on. ANALOG INPUTS: Low level dc signals of 4-20mA with input internal resistance 250 Ω
representing customer demand. Weight signals: Two Wheatstone bridge, inputs (J1 and J2) on CPU board scaled for 30 mV
full scale with 10 V dc excitation to bridge. ANALOG OUTPUTS: Current feedback signals of 4-20mA with max, load of 600 Ω
representing material feedrate. TACHOMETER INPUT: 0 to 2000 Hz sinusoid or square-wave, 3 to 50 V ac. ACCURACY: Feedarte: ±0.5%
Integrated Totalized Weight: ±0.5% 4.1.2.5 FEEDRATE MEASUREMENT AND CONTROL CIRCUIT
The feeder weighing signal is generated by two load cells which support a weigh roller. Located on each side of the weigh roller is a weigh span roller which together accurately define a given length of belt on which the material is weighed. Each load cell supports 25 percent of the weight of material on the weigh span. The output of the load cells is scaled -11-
into a signal which represents tons of material per meter of belt. This weigh data contributes to the feedrate formula from which the feeder is operated. Weight (T/M) × belt speed (M/sec) =feedrate (T/sec)
The feeder controls can accept either an internal feedrate set point or a customer feedrate demand signal. This signal is compare with a computed feedrate derived from measured weight on the belt, belt speed, and other parameters to generate the system error signal which operates the motor speed control. Compensation for system stability is provided in the software. Furthermore, since the microprocessor has stored all system parameters and limits, the error signal includes all these setting so that no adjustments are require on the speed controls. The microprocessor (software) computes the feeder delivery rate as follows: a measurement sample is taken of the output of one load cell. This signal is converted into a digital signal (binary number) by an analog to digital converter in the microprocessor having a resolution of one part in 4000 (12 bit), or 0.025 percent. This number is compared against parameters stored in permanent memory (ROM). If the signal is within acceptable limits, it is stored in temporary memory (RAM). The same operation is then performed on the other load cell. The signals are compared to each other to further test their validity. If the signals are determined to be invalid, the feeder is switched to volumetric operation and the controls use a simulated load cell output generated from a historical overage value stored in memory. If the signals are determined to be valid, the two load cell signals are summed and the tare is subtracted. The result is multiplied by a calibration factor (determined during feeder calibration) to arrive at weight of material per unit of belt length. The result obtained is stored in RAM. The belt speed is determined by measuring the period of the output frequency of an ac tachometer attached to the motor shaft. The accuracy of this measurement using the microprocessor, with a crystal as a reference oscillator, is 0.025 percent. This analog signal is converted into a digital signal (binary number) and multiplied by another calibration factor (determined during feeder calibration) to arrive at a number that represents belt travel per second. Finally, the belt speed and weights are multiplied together to arrive at the feedrate. This result is then compared to the demanded feedrate to determine the error and to operate the speed control. The feedrate is displayed in tons per hour. The federate is integrated to obtain totalized delivery in kilograms. The feeder is designed to maintain uniform material volume on the weigh span, therefore, the density is determined from the load cell output. This density measurement is also available to the operator on the display panel. 4.1.2.6 SERVICE TOOL KIT
Special tools are listed below to facilitate accomplishment of test-run, calibration of the feeder and maintenance. It is recommended that these tools be kept in their tool kits when not in use. a. Two checking bars for aligning the level of weigh roller with both weigh span rollers. b. A calibration tool kit containing 2 calibration probes (Y8406-1), 2 probe connecting wires (X9633-3) and 1 pack of retroreflective tape (W20393-1). They are used to calibrate the feeder after it starts up and after it has been operating for a period of 6 months. How to apply this tool kit is detailed in CHAPTER 5-ADJUSTMENT. 4.1.2.7 FEEDER DISCHARGE PLUCGAGE ALARM -12-
A paddle limit switch is located at the feeder discharge to sense the discharge plug-gage. When material compacts and touch the contactor which limits the paddle motion, the paddle actuates limit switch LSFD to contact closure and trip the belt drive motor. The alarm device consists of a stainless steel paddle and a limit switch mounted separately on either side of a horizontal shaft, of which the switch is located outside the feeder. The closure of unit pole contact interior of the limit switch capsule can be adjusted through a cam which is mounted on the shaft end. 4.2 PRELIMINARY START-UP 4.2.1 PRELIMINARY START-UP MEASURES
a. If the bunker is empty, open and close the valve above the feeder to deposit any foreign material in the bunker or downspout on th e feeder belt. CAUTION BEFORE ATTEMPTING ANY WORK INSIDE THE FEEDER, DEENERGIZE THE ELECTRICAL CONTROL CENTER BY LOCKING THE MAIN CIRCUIT BREAKER IN THE OFF POSITION.
b. Open all feeder doors and remove all debris from on the belt and inside the feeder. c. Check oil level of reducer.
d. Remove fibrous tape and load cells packing support. Mount load cells onto the feeder to support weigh and weigh span rollers.
e. Align the weigh roller according to the procedures in SECTION 5.3.3. Check the weigh span and weigh rollers for freedom of rotation.
f. Inspect the electronics controls for proper installation and that all P.C. cards and cable connectors are firmly in their sockets.
g. Measure the input voltage at the main feeder disconnect. If the voltage is correct, apply power. Verify that green READY indicator is energized. 4.2.2 MICROPROCESSOR CONTROL SET-UP
There are a number of job-specific physical measurements that must be entered into the microprocessor controls in order to operate a given feeder. The values are stored in permanent memory and only have to be entered once. The set-up command for each such value consists or calling upon a specific memory address Location and storing at this memory location either a value or an instruction. Each memory address consists of a two-digit number, therefore, the single-digit addresses (0-9) must be prefixed with a zero for proper recognition. An instruction is usually a single-digit number which sets the controls or display to operate in a predetermined way. A value is a feeder parameter which is used by the microprocessor in its control sequence. When appropriate the key for a particular instruction exists itself on the keyboard and can be used instead of entering the memory address location. For example, the feedrate set point address location is 00, but the RATE (blue) key can be used instead to access that m emory location. All set-up commands require use of the SET-UP (yellow) key to access memory locations. Then the desired address and parameter value are selected. To enter a value, or to alter one previously entered, type it in and press ENTER (blue) according to the following sequence: SHIFT (yellow) SET-UP (yellow) Key Or Address Location (blue) New Value (blue) ENTER (blue) -13-
When recall for reference a value previously stored by pressing: SHIFT (yellow) SET-UP (yellow) Key Or Address Location (blue) SHIFT (yellow) ? (yellow) Note that the address location is shown on the left side of the display while being operated. Each memory address location and its set point can be checked and altered by following these sequences. When the feeder is powered but in the OFF mode, the blue arrow keys may be used to proceed from one address location to another. Use the down arrow key to reach a lower-numbered address or the up arrow key to reach a higher-numbered address by pressing: ↓or ↑(blue) NEW VALUE (blue) ENTER (blue)
The arrow keys will respond only when the feeder is powered but in the OFF mode. When the feeder is in the REMOTE or LOCAL mode, then SHIFT (yellow) SET-UP (yellow) and ADDRESS LOCATION (blue) followed directly by specified commands or set-up values must be operated when a value is to enter a certain address or to read out a certain address. Use the following general instructions when entering set-up values: 1. Before entering a set-up a value if is necessary to select an address for the value and the display will become blank. If it is necessary to read out the address then press: SHIFT (yellow) ? (Yellow). When the address is read and intend to alter if, then it is
necessary to press the key according to the sequence which is require for entering a new value and revert to blank display status. 2. Enter numbers as if using a pocket calculator.
3. Do not use decimal point value (blue) unless it is indispensable. 4. No more than three numbers can be entered after the decimal point. 5. If a mistake is made press CLEAR (blue) to erase the entry and start again. 6. Press SHIFT (yellow) EXIT (yellow) to release the set-Up function without affecting the already stored Value.
7. Press ENTER (blue) to enter the value into memory. 8.
"88888888" will flash if an inappropriate entry is made. Simply start over and try again.
9. The keyboard may have a lockout feature which prevents any change from being made to the Set-up parameters. The lockout feature is either a switch or a jumper wire between terminals 107 and 117 in the microprocessor cabinet. To remove the lockout feature so that set-up parameters may be entered, either open the switch or remove the jumper wire.
10. It is recommended that the Set-up parameters be reviewed for correctness after all initial entrees have been made.
11. To exit the set-up mode after entering or verifying set-up parameters, press the OFF (white) key. If a value of 2 has been entered in Address 26, exit the set-up mode by pressing SHIFT (yellow) EXIT (yellow) 4.2.3 FEEDER PARAMETER TABLE
The following table summarizes all the operating parameters of the microprocessor control system. The values entered in the preliminary value column are to be used for guidance during equipment start-up. They should be checked and changed as required in accordance with actual jobsite conditions and, when verified, recorded, in the final value column for -14-
permanent reference. Address
Function
00 0l
Feedrate (Tons per Hour) Speed Set Point (rpm)
02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Initial Density Estimate (kg/m3) Run Mode Select Feed Display Select Maximum Feedrate (Tons per Hour) Minimum Feedrate (Tons per Hour) Totalizer Increment (Kilograms per Pulse) Demand Mode Tachometer Type Weigh Span Volume Calibration Probe Span Calibration Weight (Kgs) MSC Servo Loop Gain MSC Servo Loop Rate Feedback Gain Discharge Plug-gage Delay (Tenths of a Second) Belt Motion Monitor Delay (Seconds) Nuclear Monitor Trip Delay Weight Signal Filtering Feedback Signal filtering Feedback Filter Override Threshold (Not Used in This Application) (Not Used in This Application) Paddle Feedback Permissive Communications Unit Number Mode Select Enable/Disable FRI Output Frequency @ 1 tph Raise/Lower Contact input Response Time
Preliminary Value -----------------------------
4.2.4 INITIAL TESTS
This procedure verifies that the feeder and its controls are operating properly, simulates feeder trip conditions, and checks the principal input/output connections. 4.2.4.1 With power applied, verify that only the displays and the green READY indicator are energized. The red VOLUMETRIC indicator must not be energized. I it is, there is a problem with the weighing system, which could b e in a load cell, cable, or amplifier. 4.2.4.2 Unbalance the load cell by applying the calibration weight on one side of the weigh roller. After a two-second delay the VOLUMETRIC indicator should be energized. This closes a contact which changes the DENSITY display from approximately zero to the initial density estimate entered in Address 02. Unbalance each load cell in order to check both sides, then remove the calibration weights. 4.2.4.3 Test that all keyboard indicators and displays are operational. When this test is performed, all components will be energized for five seconds and then return off automatically. press: OFF (white) SHIFT (yellow) SELF TEST (yellow) 4 (blue)
4.2.4.4 Press and maintain the JOG (blue) key to verify belt travel in the direction of the feeder outlet.
-15-
4.2.4.5 Energize the feeder for operation at 500 rpm. Press: SHIFT (yellow) SET-UP (yellow) RPM (blue) 500 (blue) ENTER (blue) LOCAL (white)
Verify that the green RUNNING indicator is energized and check the motor speed for stability within ±5 rpm. If it is unstable, check the motor speed control servo loop gain (Address 14) and the motor speed control servo loop rate feedback gain ( Address l5) to see that those two parameters match the recommended initial settings. If they match, contact SPERI for assistance in selecting values more suitable to the particular application.
4.2.4.6 Check for proper belt tracking. Verify that the V-guide of the belt within the grooves on the pulleys and rollers, and that no humping is noticeable at any of these points. Adjust the belt for proper tracking as per SECTION 5.3.2, if necessary. 4.2.4.7 Check belt tension and adjust as per SECTION 5.3.1 if necessary. 4.2.4.8 Connect a digital tachometer to the speed pick-up signal located at wires 145 and 146 on the terminal blocks inside the microprocessor cabinet. Set the tachometer to the appropriate range for the type of feedback signal present. Select the RPM mode on the lower keyboard display and verify that the display and the tachometer readings are equal. If they are not, either the tachometer type (Address 09) is incorrectly entered, or the speed feedback jumper on the CPU board is not adjusted correctly. 4.2.4.9 De-energize the feeder and deflect the material on belt limit switch (LSFB) paddle to simulate a loaded belt. Energize the feeder in the LOCAL (white) mode to verify that the feeder operates for only two seconds in the LOCAL mode with material on the belt. After the feeder has stopped, verify that the red TRIP indicator is energized. If the feeder does not trip or if the indicator is not energized, check the adjustment of the paddle switch cams as per SECTION 5.3.4 4.2.4.10 Check the error recall function of the microprocessor controls. Press: SHIFT (yellow) ERROR RECALL (yellow).
The display should now show 08, the error code indicating material on the belt in the LOCAL mode. Return limit switch (LSFB) paddle to its in-service position. 4.2.4.11 Press the OFF (white) key and align the analog inputs and outputs according to the procedure in Section 5.2. 4.2.4.12 Calibrate the feeder according to the procedure in Section 5.1 4.2.4.13 Apply the calibration weights. Produce or simulate a feeder start permissive and apply a 100 percent demand signal. Check the motor current draw on each phase to verify that it does not exceed the nameplate rating. 4.2.4.14 Check feedrate and feedback linearity by applying demand signals of 100,75,50 and 25 percent. Compare each demand signal applied to the displayed feedrate and to the feedback signal output to verify linearity within ±0.5 percent. If simulation of maximum feedrate cannot be achieved during this test, proceed as follows: 1.
Calculate the density by the test weight(s) supplied: 2 × test weight ———————————— = density (kg/m2) volume on weigh span
2.
Press the DENSITY (blue) key on the keyboard.
3.
If the density displayed matches the calculated density but falls below 560kg /m2, the test -16-
weight mat be insufficient to simulate 100 percent federate. When this occurs, the feeder should be forced into volumetric operation by removing the test weight from one side of the weigh roller. In the volumetric mode, the density value used by the microprocessor is approximately 800kg/m3, so that a 100 percent simulated federate should be obtainable. 4.
If the density displayed differs greatly from the calculated density, then it may be that the feeder has not been correctly calibrated or that there is problem on the CPU board.
4.2.4.15 while the feeder is operating in the REMOTE (white) mode, deflect plug-gage alarm limit switch (LSFD) paddle, the feeder should be tripped as delay time set in Address 16 expires. Check if the red TRIP indicator is energized when the feeder is deactivated. If the feeder is not stopped or TRIP (red) is de-energized, adjust paddle or limit switch cams according to procedures in Section 5.3.5. 4.2.4.16 check error recall function of microprocessor controls. Press SHIFT (yellow) ERROR RECALL (yellow), the display should show 07 signifying feeder discharge plug-
gage occurs. Revert limit switch (LSFD) paddle to normal operation status and revert the feeder to operate in the REMOTE mode. 4.2.4.17 White the feeder is operating in the RMOTE mode, deflect the material on bell limit switch (LSFB) paddle and apply or simulate a demand signal from the combustion control system. Verify that the two displays respond to feeder operation and that the four green indicators, RUNNING, READY, FEEDING, and REMOTE are all energized. 4.2.4.18 Press: SHIFT (yellow) SELF TEST (yellow) 6 (blue). Verify that the lower display shows the demand signal currently being applied to the feeder. This signal will be displayed in the same unit of measure, tons per hour, as the feedrate display, and should change as the demand signal changes. In this mode, all three LEDs beneath the display will be de-energized. The controls will continue to display the demand signal until the RPM, DENSITY or RATE (blue) key is pressed. 4.2.4.19 Press: SHIFT (yellow) SELF TEST (yellow) 5 (blue) and note the number shown in the upper display. De-energize the control cabinet at the main disconnect switch and then reapply power. Press: SHIFT (yellow) SELF TEST (yellow) 5 (blue) again to verify that the number in the upper display is increased by one. 4.2.4.20 When initial feeder test has been completed successfully, press the OFF (white) key to deactivate the feeder. Note that if the feeder is put into use right after the initial test is completed, please go on test running according to procedures in section. 4.2.8. If the feeder is to be inactive for a certain period, please proceed according either to section 4.2.5 or 4.2.6 depending on the duration of being inactive. 4.2.5 Maintenance for feeder to be inactive for a short period (less than 1 year) after the initial test. 1.
Clean out all foreign material in the feeder.
2.
Thoroughly flush interior of the feeder, apply rust-protective coating onto interior of feeder after the flushing is dried.
3.
The feeder inlet should be firmly and lastingly covered to keep off moisture and foreign material.
4.
Clean out dust, dirt and accumulated water within the control cabinets, put in bags of drying-agent and keep the door tightly closed. Drying-agent bags should be put near to -17-
limit switches installed interior of the feeder to keep off rust corrosion. 5.
Mount on calibration weight and operate the feeder in the LOCAL mode for at least one hour every month.
6.
Proceed storage maintenance as detailed in section 3.2.
4.2.6 Maintenance for feeder to be inactive over one year after the initial test. 1. Proceed maintenance according to Section 4.2.5. 2.
Loosen the belt take-up screws to release the belt tension.
3.
If the feeder is to be inactive over 36 months, dismantle and store the belt according to Section 5.3.6 in order to obtain the longest possible belt life. The belt should be stored laterally and sunshade in a dry, cool place without ozone. Refold the belt every three months to change the positions of bend, the radius of bend should be as large as possible.
4.
Lubricate all bearings quarterly as detailed in SECTION 6.2.
5.
Fill the reducer with lubrication oil up to its top if the feeder is to be inactive over one year so as to prevent the forming of moisture. Seal the oil inlet with a dead plug after filling. Note that lubrication oil should be reduced to normal level before the feeder starts up.
4.2.7 INITIAL SYSTEM OPERATION
Follow these special operating instructions the first time the feeder is energized to operate according to typical operating procedures. 1.
Be sure that the calibration weights are removed from the load cells.
2.
Carefully load the feeder belt slowly opening the inlet valve to load the belt at a controlled rate. This procedure minimizes compaction of the material and thereby reduces the force necessary to start the belt moving which prolongs its life.
3.
Clear the totalizers. Press: SHIFT (yellow) TOTAL RESET (yellow).
4. Clear the error stack. Press: SHIFT (yellow) ERROR RECALL (yellow) CLEAR (blue). 5.
Reset the feeder maintenance time. Press: SHIFT (yellow) F1 (yellow).
6.
When the feeder is operating for the first time, check and adjust the belt tension every 15 minutes until the belt no longer extends.
4.3 TYPICAL OPERATING PROCEDURES
1. When filling the bunker, first close the inlet valve to minimize the filling pressure on the feeder and to avoid compaction of the material at the feeder inlet. This precaution is unnecessary if the bunker is refilled while at least 2.4-3M of material remain in it. 2.
When starting the feeder, open the inlet valve slowly to load the belt at a controlled rate and to minimize compaction at the feeder inlet.
3.
Energize the feeder controls at the circuit breaker (CB1) in the control cabinet. Observe that the green READY indicator is energized, signifying that the microprocessor is powered.
4.
Press the REMOTE (white) key. Upon receipt of a customer generated feeder start command and a demand signal from the combustion control system, the feeder begins to operate and the green RUNNING and REMOTE indicators are also energized. -18-
5.
As material fills the feeder belt, the green FEEDING indicator is energized.
6.
When the microprocessor has verified the operation of the weighing system electronics, the feedrate is displayed above the energized RATE indicator and the totalized weight is displayed above the energized GRAV indicator.
7.
The feeder will operate as outlined above and will respond automatically to the changing demands of the combustion control system until it is de-energized. During normal operation, only the four green status indicators are energized. If any of the amber or red status indicators are energized, then a problem has been detected and the feeder requires attention.
8.
For a brief feeder stop with a loaded belt, press the OFF (white) key.
9.
For a clean shutdown with an empty belt, close the inlet valve while the feeder is still running. When the belt is emptied, the feeder is automatically deactivated by paddle type limit switch on the Void Alarm device, then press the OFF (white) key. This procedure is recommended whenever the feeder will be inactive for more than a brief interval, since it eliminates the possibility of material compaction at the feeder inlet due to consolidation caused by its own weight.
10. To jog the feeder belt, press the OFF (white) key followed by the JOG (blue) key on the microprocessor keyboard for as long as motion is required. 11. Cleanout conveyor selector switch SSC is located on the panel of the microprocessor control cabinet to activate or deactivate the cleanout conveyor. 12. Illuminator switch FLS is located on the panel of the microprocessor control cabinet to turn the illuminating light on and off.
5. ADJUSTMENT 5.1 FEEDER CALLBRATION
The feeder should be calibrated at start-up, after one month of initial operation, after every six months thereafter, and after any of the following occurrences: belt replacement, weigh roller adjustment, or replacement of a load cell module, the CPU board, or the microprocessor program chip. Calibration consists of the elimination of system tare, which includes the weight of the weigh roller, load cell support assembly, and the feeder belt. It also involves measuring belt speed and its relationship to motor speed, and calibrating the load cell output with a known weight. Cancellation of feeder tare is performed by measuring the average weighing system output over exactly one belt revolution and then subtracting this amount from the total weight measurement. When the belt is running empty, it produces a zero average contribution to the totalized weight. In normal operation, the average tare is automatically subtracted from the gross weight of the belt. Therefore, only the weight on the belt is reflected as totalized weight. During the same time the empty belt is being weighed, the belt speed is accurately measured. This is done by measuring the time it takes a retro-reflective tape marker on the belt to travel between two fixed points. This parameter is measured a number of times to determine repeatability and to compensate for variations in belt thickness. From this data, -19-
the belt speed is calculated and the relationship between belt speed and motor speed is established. The feeder operates with zero belt slippage. Therefore, the ratio of belt speed to average motor speed is constant. This ratio is stored in memory and is used to determine the belt speed for any motor speed. The span of the weighing system is set after the tare has been measured. A known weight is applied to the weigh roller and the average output over exactly one belt revolution is measured. This calibrated span factor is stored in memory and used to accurately determine the value of the weight of the material on the belt. In principle, the calibration procedure involves placing a test weight on the weigh roller and precisely measuring one revolution of belt and the weight on a fixed length of belt. This date is processed using an algorithm developed from the results of material tests and guarantees the specified feeder accuracy without the need of test chains of other material tests. 5.1.1 CALIBRATION PROCEDRE NOTE
BEFORE CALIBRATING THE FEEDER. ALLOW IT TO OPERATE FOR 15 TO 30 MINUTES TO LIMBER THE BELT. 5.1.1.1 Close the inlet valve above the feeder and empty the belt. 5.1.1.2 Press the OFF (white) key. 5.1.1.3 Close the feeder discharge valve below the feeder discharge. 5.1.1.4 Open all feeder side and end access doors, as well as the door to the microprocessor control cabinet. 5.1.1.5 Adjust the belt to proper tension and tracking according to section 5.3. 5.1.1.6 Apply four strips of retro-reflective adhesive tape from the calibration kit to the belt curb on the same side as the control enclosure. Each strip should be positioned vertically on the belt curb and located entirely between two flexing slits in the belt, rather than spanning over a slit. Place one strip each outboard of the drive and take-up pulleys, a third adjacent to the weigh roller, and the fourth on the return belt beneath the third. 5.1.1.7 Verify that all four tapes are spaced at a distance greater than one calibration probe span length from each other. NOTE
THE TAPES MAY STAY ATTACHED TO THE BELT FROM ONE CALIBRATION TO THE NEXT. BEFORE SUBSEOUENT CALIBRATIONS, INSPECT AND CLEAN OFF THE TAPES AT THIS POINT IN THE PROCEDURE. 5.1.1.8 Align the weigh roller according to section 5.3.3. Clean off any dirt accumulation at each drag link pivot point. 5.1.1.9 Separately insert both probes into relevant threaded holes on the weigh plate. NOTE
ALTHOUGH THE TWO PROBES ARE NOT DEDICATED TO PARTICULAR LOCATIONS, NOTE THAT THE PROBE LOCATION NEAREST TO THE FEEDER INLET IS DESIGNATED LOCATION AND THE PROBE LOCATION A NEAREST TO THE DISCHARGE IS DESIGNATED LOCATION B. 5.1.1.10 Connect the probe cables to the probes and to the receptacles in the microprocessor -20-
control cabinet. Connect probe A to receptacle CAL A and probe B to receptacle CAL B.
5.1.1.11 Compare the total weight of the two calibration weights against the value that is stored in the microprocessor memory. To display the value stored in memory, Press: SHIFT (yellow) SET-UP (yellow) 13 (blue) SHIFT (yellow) ? (yellow)
5.1.1.12 If the calibration weight displayed from memory above is incorrect, enter the correct calibration weight as follows. Press: SHIFT SET-UP 13 ** ** ENTER
* Enter in place of the asterisks the actual value stamped on each calibration weight, accurate to two decimal places. NOTE
IF A MISTAKE IS MADE DURING ENTRY OF THE CORRECT CALIBRATION WEIGHT VALUE, PRESS CLEAR (BLUE) AND RE-ENTER ONLY THE VALUE. DO NOT RE-ENTER ANY SET-UP COMMANDS. 5.1.1.13 Verify that the calibration weight is OFF the weigh roller on each side of the feeder. 5.1.1.14 Initiate tare and belt travel calibration. Press: SHIFT (yellow) CAL 1 (yellow)
The feeder will now begin to operate under control of the microprocessor. Observe the TOTALIZED WEIGHT display to verify that the calibration is proceeding in the following manner: 1.
The display will clear and a zero will be shown at the extreme right of the display.
2.
The amber CALIBRATION indicator is energized.
3.
A 25-second delay is initiated while the belt drive motor is brought up to 1000 rpm and stabilized there.
4.
When the delay expires, the first tape passing probe A causes the display to read “.1”.The decimal point is turned off when the tape passes probe B. Each following tape turns on the decimal point when it passes probe A and turns it off when it passes probe B. In addition, as each tape passes probe A, the number on the display is increased by one.
5.
As the ninth tape crosses probe A, the belt will have traveled exactly two revolutions (or four revolutions if two tapes were applied). The drive motor is de-energized and the display shows the percentage repeatability error of the eight belt speed measurements just performed.
6.
If this error is greater than a programmed limit, the display returns to zero and the calibration is automatically repeated until a measurement accuracy within the programmed limits is obtained.
7.
If after numerous attempts the calibration still fails, press SHIFT (yellow) EXIT (yellow) to end the calibration and proceed to troubleshoot for problems in the motor speed control or with belt travel.
5.1.1.15 If tare and belt travel calibration are successful, the amber ADD WEIGHT indicator is energized and the expected value of the calibration weight appears on the display. If the value shown is incorrect, press SHIFT (yellow) EXIT (yellow) to stop the calibration. Refer to Section 5.1.1.12 for entry of the correct calibration weight value. 5.1.1.16 when the correct calibration weight is displayed, mount one calibration weight -21-
beneath each load cell. 5.1.1.17 initiate span calibration. Press: SHIFT (yellow) CAL 2 (yellow)
1.
The belt drive motor is energized and after approximately 25 seconds, the display shows zero and begins to count the passage of eight tapes as in Section 5.1.1.14.
2.
After the passage of the ninth tape (not displayed), the feeder is de-energized and its displays return to their normal functions.
5.1.2 CALIBRATION CHECK
By comparing the current calibration to the one done previous to it, the operator can determine how repeatable the calibration is and how it may have changed over the last six months. The microprocessor controls calculate the percentage change between the two calibrations when the commands are entered as follows: 5.1.2.1 To compare tare percent change, press: SHIFT (yellow) SELF TEST (yellow) 1 (blue)
5.1.2.2 To compare belt travel percent change, press: SHFT (yellow) SELF TEST (yellow) 2 (blue)
5.1.2.3 To compare span percent change, press: SHIFT (yellow) SELF TEST (yellow) 3 (blue)
The results of all three calibration checks should be 0 ±0.20 maximum. If they fall outside this limit, check the suspension of the calibration weight from the load cell for sticking or other unusual characteristics; then repeat the complete calibration procedure. NOTE
THE NUMBERS 99 AT THE EXTREME LEFT OF THE DISPLAY REPRESENT A NEGATIVE SIGN, MEANING THAT THE INOICATION IS LESS THAN 0. THE SIGN OF THE CHANGE (PLUS OR MINUS) IS SHOWN IN SUCH A WAY THAT A POSITIVE ERROR INDICATES THAT THERE WAS TOO MUCH MATERIAL BEING DELIVERED BEEORE THE CALIBRATION AND A NEGATIVE ERROR INDICATES THAT THERE WAS NOT ENOUGH MATERIAL BEING DELIVERED. 5.2 INPUT AND OUTPUT ALIGNMENT PROCEDURE
The feeder controls can respond to a federate demand signal and return isolated analog feedback signals. When the input and output modules associated with these signals are used with the plant's control system, they must be adjusted prior to operating the feeder under remote control. There is one customer input channel used in the microprocessor control system, designated A1. There are three output channels used in the control system which may require alignment, designated A2, A3,and A4. Output channels used by the customer are determined by the type of belt drive motor used in the feeder. The following are the standard output channel configurations for the three available types of motors: a.
For eddy current clutch applications , A2 is an optional analog feedback, and A3 is the
standard customer analog feedback. A4 is used internally by the microprocessor and does not require trimming. b.
For dc drive motor applications, A2 is used internally by the microprocessor for the -22-
motor speed demand output and does not require trimming, A3 is used for customer feedback, and A4 is the optional tachometer driver. c.
For ac variable frequency drive applications: A2 is used internally by the
microprocessor for the motor speed demand output and does not require trimming, A3 is the customer analog feedback, and A4 is the optional tachometer driver. Any analog input or feedback signal used by the customer must be matched or adjusted to the microprocessor controls. Two signal levels must be adjusted for each channel used. The first signal level, offset, corresponds to the lower value. The second, span, corresponds to the higher value. The internal tachometer and motor drive outputs do not require customer adjustment. Motor speed signals are processed by the microprocessor controls in a closed-loop configuration. Motor speed is monitored by the tachometer and processed by an algorithm which determines if changes in motor speed are required to match the feedrate to the demand, and then automatically makes those changes. NOTE
IF THE FEEDER IS NOT EQUIPPED WITH A REMOTE ANALOG DEMAND INPUT, THE INPUT ALIGNMENT SECTION CAN BE OMITTED. IF AN ANALOG OUTPUT SIGNAL IS NOT PRESENT, THE OUTPUT ALIGNMENT SECTION CAN BE OMITTED. When adjusting the signals to the microprocessor control, memory locations are accessed which correspond to the particular channel being adjusted. For reference, the trim address numbers and the channels they control are listed in the following table: Output Channel Trim Address Wire Numbers A3 Offset (low level) 0 139,140,141 A3 Span (high level) 1 139,140,141 A2 Offset (low level) 2 142,143,144 A2 Span (high level) 3 142,143,144 A4 Offset (low level) 4 131,132,133 A4 Span (high level) 5 131,132,133 A1 Offset (low level) 8 SIG+,SIG-,COM,S1 Al Span (high level) 9 SIG+,SIG-,COM,S1 Equipment required: (1) A ammeter. (2) An analog input demand Signal. NOTE
THE PLANT COMBUSTION CONTROL SYSTEM IS THE PREFERRED SOURCE OF THE DEMAND SIGNAL. THIS WILL PRECISELY ALIGN THE FEEDER TO THE CONTROL SYSTEM . 5.2.1 OUTPUT ADJUSTMENT NOTE
THE SPECIFIC TRIM ADDRESS NUMBERS PRESENTED IN THIS SECTION REFER TO OUTPUT CHANNEL A3 AS AN EXAMPLE. ADJUSTMENT FOR OTHER OUTPUT CHANNELS FOLLOWS IDENTICAL STEPS; HOWEVER, THE ADDRESS NUMBERS WILL CHANGE. THESE ADJUSTMENTS MUST BE PREFORMED ONLY WITH THE FEEDER OFF. 5.2.1.1 Verify that the proper current converter card is plugged into power supply board socket
-23-
A3 the customer feedback output module. 5.2.1.2 Connect an appropriate meter to the customer output feedback signal. This analog signal is generated by a precision frequency source. By setting the low and high end frequencies, the offset and span analog signals, respectively, are set. 5.2.1.3 To set the offset of channel A3, press: SHIFT (yellow) TRIM (yellow) 0 (blue)
The display shows the frequency being sent to the analog conversion card. While observing the meter connected to the output, press the blue up or down arrow keys to adjust the output to 4 mA. NOTE
PRESSING AND RELEASING AN ARROW KEY WTLL ADJUST THE FREQUENCY IN SMALL INCREMENTS. PRESSING AND HOLDING THE KEY WILL CAUSE MORE RAPID ADJUSTMENTS. 5.2.1.4 When the analog output offset is correct, press: ENTER (blue) OFF (white)
This will store the adjustment in the microprocessor control memory. 5.2.1.5 To set the span of channel A3, press: SHIFT (yellow) TRIM (yellow) 1 (blue)
Adjust the frequency with the arrow keys until the proper span adjustment 20 mA is obtained at the analog output. To store the adjustment in memory, press: ENTER (blue) OFF (white)
5.2.l.6 To save time by avoiding starting at zero to set an offset or span value, press: CLEAR (blue)
This key resets the frequency to approximate offset and span Values, 200 hertz and l000 hertz, respectively. 5.2.1.7 To exit an adjustment mode without changing a previously stored value, press: SHIFT (yellow) EXIT (yellow). 5.2.2 INPUT ADJUSTMEMT CAUTION
IMPROPER USE CAN CAUSE OPERATIONAL PROBLEMS. THESE TRIM ADJUSTMENTS ARE COMMANDS TO ACCEPT WHATEVER SIGNAL IS AT THE INPUT. DO NOT USE IT TO CHECK PREVIOUSLY STORED VALUES. (TO CHECK THE INPUT SIGNAL, USE SELF TEST 6.) THESE ADJUSTMENTS MUST BE PERFORMED ONLY WITH THE FEEDER OFF. 5.2.2.1 Verify that the proper input card is plugged into the input module socket Al. When aligning the input, minimum and maximum demand signals are given to the microprocessor. The analog demand is converted to a frequency, which is stored in the memory. 5.2.2.2 Apply a 4mA demand signal to the feeder. Use either a precision source or, preferably, a 4mA analog demand signal directly from the combustion control system. Then press: SHIFT (yellow) TRIM (yellow) 8 (blue)
The feeder display will show the demand signal as an equivalent frequency that corresponds to 4mA demand. IMPORTANT -24-
IF THE DISPLAY IS ZERO, FIRST CHECK THE FOLARITY OF THE DEMAND SIGNAL.IF THE POLARITY IS CORRECT, THE INPUT CARD MAY BE DEFECTIVE. 5.2.2.3 Apply a 20mA analog demand signal to the feeder. The press: SHIFT (yellow) TRIM (yellow) 9 (blue)
The display, will show the demand signal as an equivalent frequency a few thousand counts higher than the minimum reading; however, the absolute maximum frequency of 10 kHz should not be exceeded. 5.2.2.4 To test the linearity on the demand signal with the feeder running, press: SHIFT (yellow) SELF TEST (yellow) 6 (blue)
The display will now show the demand signal converted into an equivalent feedrate in tons per hour. All three LEDs which indicate RATE, RPM and DENSITY should be deenergized. Apply the analog signal equivalent to zero feedrate; the display should indicate the minimum feedrate as entered into the set-up parameter at Address 06. Increase the analog signal in steps of 25, 50 and l00 percent and the display should show the corresponding feedrate in tons per hour as soon as the demand signal exceeds the minimum feedrate in Address 06. To return the display to its normal operating mode, press the RATE (blue) key. 5.2.2.5 To test the linearity of the feedback signal, the feeder should be run in the REMOTE mode with the calibrating weights engaged and the material on belt paddle switch (LSFB) closed. If the switch is not closed, linearity will be affected. Until the FEEDING LED is illuminated, the rate control circuit operates the belt speed based on the density entered into the set-up parameter at Address 02. This feature prevents the feeder from running at its maximum speed while the belt is being loaded. 5.3 MECHANICAL ADJUSTMENT OF FEEDER
Following basic requirements must be ensured to keep the weighing accuracy of the feeder; proper belt tension; proper belt tracking; correct alignment of the weigh roller with weigh span rollers; the six-month feeder calibration frequency and adjustment of minimum seal air pressure for normal operation. 5.3.1 BELT TENSION
It is preferable to adjust the belt tension while the feeder is operating. Observe through the sight glass on the side door of the feeder to see if the center of tension roll is located at the middle of the scaled indicator. It is required that the tension roll fluctuates around the middle of the scaled indicator. Belt tension can be adjusted by take-up screws which are mounted on the feeder inlet end door. Both screws should be equally and alternatively adjusted to avoid damaging the screw thread. Newly mounted belt should be operating under tension no less than one hour to release belt internal stress before normal operation. If a new belt is required to operate with load immediately after it is mounted then attentively observe within the first hour and make adjustment every 15 minutes. Note that both take-up screws must be equally adjusted. Normal operation according to tension indicator can be performed after such adjustments. 5.3.2 BELT TRACKING
Belt tracking is to keep the belt travel along centers of drive pulley and take-up pulley to -25-
avoid off track while maintaining a smooth and stable travel through the weigh span to ensure weighing accuracy. At the middle of inner belt a v-guide is provided to engage with grooves on pulleys, roll and rollers to keep the belt travel centrally. The belt surface must be flat as it travels, tracking adjustment should be made if belt humping occurs as it passes through pulleys or rollers. Belt tracking can be accomplished by adjusting take-up screws. Screw or unscrew the left-of right-side screw can cause the belt to travel leftward or rightward and thus tracking the belt. Practical amount of adjustment is determined during test run.
V-GAIDE
BELT
PULLEYSAND ROLLERS
BELT TRACKING ADJUSTMENT
5.3.2.1
BELT
TRACKING PROCEDURES WHILE
THE
FEEDER IS
NOT
OPERATING
It is most convenient to track the belt while the feeder is not operating, because all end and side doors may be opened and belt humping can be clearly observed. 1.
Open the feeder end door and turn on the internal feeder light.
2.
When the belt is changed, verify its perpendicularity to the take-up pulley.
3.
Properly adjust the belt tension.
4. Draw a cross chalk mark on the belt surface for determining the number of belt revolutions. Initiate the feeder and operate it at low speed, attentively observe belt travel for at least 5 revolutions to check if there is any belt humping. Then operate at high speed for at least 20 revolutions. Belt tracking can be construed as perfect if no belt humping occurs. 5.
If belt humping occurs, then first make it correctly tracked on the drive pulley by adjusting
take-up screws to move and center the belt. Then operate the belt successively at low and high speed for 5 and 20 revolutions respectively to check for belt humping until the belt travels to perfection. Some belt will reciprocately offset along the axis of drive pulley as it travels, adjustment should then be made to cause the offset align with the midpoint of drive pulley. 6.
In general, correct tracking is obtained after above adjustment as a crown is machined on
the surface of take-up pulley. Whenever belt humping is found at the take-up pulley, turn the eccentric bushing on any side of the tension roll for an angle of 90° clockwise or anti-clockwise depending on which side the belt off tracks. If belt humping still exists after operation of 20 revolutions, then turn the eccentric bushing on the other side of the tension roll 90° in a reverse -26-
direction and further observe belt operation for at least 20 revolutions. Thereafter, in-between holes on the eccentric bushing can be used for adjustment until belt humping is totally eliminated. Whenever belt tracking has been adjusted on the take-up pulley then, check again the tracking on the drive pulley and make re-adjustment if necessary. 7.
After the belt tracking is accomplished, re-adjust belt tension to locate the center of tension
roll at the middle of the scaled indicator and verify that both take-up screws have been equally adjusted lest that another belt off-track is induced.
Side Doo r Fram
Side Doo r Fram
Tension Roller Arm
Tension Roller Arm
Sc ale
Sc ale
Indicator (The C entre of Tension Roller)
Belt too Tight
Indicator (The C entre of Tension Roller)
Belt Tension Proper
Side Doo r Fram
Tension Roller Arm Scale Indicator (The C entre of Tension Roller)
Belt too Loose
5.3.2.2 It is hard to find out belt humping by observing while the feeder is operating with
material on the belt. The only possibility of evaluating belt off-track is to observe carefully to see if the distance between either side of belt and roller is equal. Observe the belt travel attentively while adjusting to be ready for a prompt reverse of adjustment, because the belt is traveling at high speed and any maladjustment will instantly off-track the belt to damage it.
-27-
Adjust both take-up screws equally for proper belt tension after the belt tracking is accomplished. 5.3.3 INLET SKIRT
The inlet skirt should be mounted upright and parallel to the material flow. It should not contact the belt and there should be a clearance between both parts.
k c a t B l n e B e e d w t n e a B t e r c i k a S p S
Si de Ski rt
Coal Secti onal Vi ew 165-180m m
1 m 1 1 m 0 1 6
e d i t S l n e B e e d w t n e a B t e r c i k a S p S
0 0 m 0 m 3 1 0 1
Space Between Ski rt and Bel t 5.3.4 WEIGH ROLLERS
The weigh roller is to be horizontally lineal with both weigh span rollers. The linearity should fall within 0.05 mm to ensure weighing accuracy. Put on standard calibration weights to load the cells. 1.
Add weights. Let the load cells loaded.
2.
Place both checking bars from the feeder accessory beside either side of the belt and on
weigh span rollers, machined surface of checking bar between the surfaces of weigh span rollers. 3.
Apply feeler gauge and adjust the adjusting units on load cells so the checking bars contact
all three rollers at once. Make orderly adjustment on either side of weigh span rollers. 4.
Raise standard calibration weights.
5.
The feeder shall be recalibrated after weigh rollers have been adjusted. ADJUSTMENT OF WEIGH ROLLER
5.3.5 CLEANOUT CONVEYOR 5.3.5.1 ABNORMAL OPERATION
The wing type cleanout conveyor only scrapes off a small amount of material while the feeder is operating. If material is excessively accumulated to overload drive system then abnormal operation is to happen. Excessive accumulation may be caused by an excessive clearance the inlet skirt; a cleanout scraper failure or an excessive flow rate of seal air to blow material from on the belt. 5.3.5.2 TAKE-UP OF CONVEYOR CHAIN
Take-up screws which are mounted against interior of inlet end door can be used for the take-28-
up of conveyor chain. Proper chain take-up is performed if droop of approximate 50 mm exists between drive sprocket top circle and the lower chain. As the chain elongates so indiscernibly that take-up re-adjustment is only necessary after a normal operation of three to four years. 5.3.6 MATERIAL ON BELT SIGNALLING DEVICE (LSFB)
PADDLE (No Coal on Belt)
PADDLE(Coal on belt) SPACER
BELT
ADJUSTMENT OF COAL SIGNAL DEVICE (MATERIAL ON THE BELT) 1. Place a spacer of 38 mm thick between paddle of signaling device and the belt so that the paddle is raised toward the direction of material flow. 2. Adjust the location of cam interior of the signaling device to make a just closure of limit switch. 3. Apply set screw to fix the cam at its adjusted location. 4. Remove all adjusting blocks from the bell. 5.3.7 MATERIAL PLUGGAGE SIGNALING DEVICE (LSFD)
-29-
CLEANOU T CON VEYOR CHAIN FEEDER BODY
PADDLE (Coal Plugged)
PADDLE
PLUGGAGE SIGNALING DEVICE (LSFD)
1. Move the paddle of plug signaling device 38 mm toward the feeder inlet. 2. Adjust the location of cam interior of the signaling device to make a just closure of limit switch. 3. Apply set screw to fix the cam to its adjusted location. 5.3.8 BELT CHANGING 5.3.8.1 CHANGING PROCEDURES
1. Close the valve above feeder and clear off material on the belt.
2. Before attempting and word inside of the feeder, be sure both the feeder operating switch and the main circuit breaker are de-energized. 3. Open all end doors and side doors of the feeder. 4. Place woodblock under the tension roll to make the roll rest on the block and part from the belt.
5. Remove the tension indicator. 6.
Remove lubrication tube connected to the tension roll.
7. Remove weigh roller connecting plates from under the load cells. 8.
Remove the linking rods.
9. Dismount and remove weight rollers from under the load cells through the side door of the feeder and then take away calibration weights
10. Unscrew take-up screws to release the belt to its utmost relaxation. Take-up screws must be alternatively unscrewed to avoid damaging the threads and never impact the wrench.
11. Push the roll dismantle prop into under the tension roll and bolt the prop onto the door frame. Threaded holes may be provided on the door frame for fixing the prop.
-30-
DISMANTLE OF TENSION ROLL 12. Remove tension roll from the tension roll arm.
13. Pull out tension roll with the roll dismantle prop. 14. Dismantle and remove weigh span rollers. 15. Prop up belt cleanout scrapers to part them from the belt.
16. Mount the roll raiser into from the feeder discharge end door and adjust the turn buckle to make the non-drive end of drive pulley rest on the raiser.
-31-
DISMANTLE OF DRIVE PULLEY 17. Dismantle bearing cap from the pillow block on the non-drive end of drive pulley with pillow block remains on the pulley shaft.
18. Push the roll dismantle prop into between the belt and the drive pulley with until the prop is laid on the feeder casing and bolt the prop onto the feeder casing
19. Dismantle the roll raiser, the drive pulley and the roll dismantle prop in order. 20. Remove the inlet skirt. 21. Remove bolts from the belt supporting plate. 22. Remove bolts which are used for fixing of the upper and the lower guide rail and of the take-up screw frame.
23. Remove take-up screw frame and take-up screws. Mount on the extended rail. 24. Remove lubrication tube from the take-up pulley.
25. Pull out take-up pulley and belt from the feeder inlet end door. Dismantle drive pulley, belt supporting plate and then the belt. 26. Put on a new belt in reverse order as that mentioned above.
-32-
DISMANTLE OF TAKE-UP PULLEY 5.3.8.2 NOTICES ON CHANGING
1. When remount the drive pulley after changing the belt, note that the half coupling on drive pulley shaft shall be kept 3 mm away from the other half on the output shaft of the reducer. 2. Make sure that the center of belt is aligned before being take-up so that the V-guide on inner bell is sure to engage with grooves on pulleys and rolls.
3. Make sure that either take-up screw frame is kept equally apart from the slide so that the perpendicularity of take-up pulley is ensured.
4. Adjust the belt tension properly. 5.
Perform correct belt tracking.
6. Recalibrate the feeder after belt changing. 5.3.9 SEAL AIR .
Adjust the seal air flow rate so that pressure difference between the feeder and the pulverizer falls within 60
245 Pa.
～
Pressure gauge may be equipped on the feeder casing for checking internal pressure. After the pressure is suitably adjusted. Confirm the opening of seal air inlet valve on the air duct so that relocation is possible once the valve is open up o r close down.
6. MAINTENANCE 6.1 INSPECTION AND REGULATION SCHEDULE To inspect regulate and calibrate the feeder at regular interval is the basis for its safe, reliable and functional operation and is also the guaranty of the feeder to operate according to the -33-
engineering design standard.
(1) Before attempting any work inside the feeder, be sure that the selector switch is deenergized and that the main circuit breaker is set at the OFF position.
(2) Daily inspection: belt tension, belt tearing. (3) Weekly inspection: belt tension, belt tearing or laminating, reducer oil level. (4) Monthly inspection: accomplishment of routine lubrication. (5) Tri-monthly inspection: replacement of oil in reducer. (6) Biannual inspection: de-energize the feeder and inspect. a. All anti-friction and pivot bearings for any damage and all gears for wear. b. The feeder for any excessive wear and erosive parts. c. Free movement of weighing system (tie-rod, load cell, weigh roller etc.) d. The belt for excessive abrasion. e. The belt cleanout scraper. f.
The load cell and keep it clean.
g. All electric contacts to rub off any rust; all wire terminals for firm connection. h. The interior of feeder to cleanout all accumulated material. i. j.
The inlet skirt for correct location and status of wear. The accomplishment of routine lubrication.
k. The tension of cleanout conveyor chain and the agility of chain link pivot. l. (7)
The accomplishment of feeder calibration. Additional regular inspection that should be considered:
a. Newly mounted belt should be inspected for proper tension, and check belt tracking 2 to 3 times each operating shift until the belt travels stably and its internal stress is fully released. Thereafter check belt tracking every week.
b. Re-check the status of belt supporting rolls whenever one of the following changes are made: replacement of a load cell module, belt changing or adjustment of weigh roller.
c. Take every opportunity to inspect the cleanout conveyor when end doors to the feeder are opened.
(8) In addition to the six-month feeder calibration frequency, the feeder must be recalibrated whenever one of the following changes are made: belt changing or adjusting, adjustment of weigh roller or replacement of a load cell module. 6.2 LUBRICATION OF THE FEEDER
-34-
LUBE POINTS ON FEEDER Lube points are marked on the attached drawing. Carry out routine lubrication according to following schedule and notice reference remarks. (1) Lubrication Schedule LUBE PT.
LOCATION
1
Belt Take-up Mechanism
2
Cleanout Scraper Take-up device
3
Weigh Span Roller Shaft
4
Tension Roll Arm
5
Tension Roll
6
Weigh Roller
7
Belt Drive Reducer
8
Belt Drive Shaft
9
Cleanout conveyor Reducer
10
Cleanout conveyor Reducer
11
Cleanout Scraper Shaft
12 13
Material on The Belt signaling Device Material Plug-gage Signal Device
14
Shaft of Weight Checking Bar
15
Belt Drive Motor
16
Cleanout conveyor Drive Motor
17
Belt Drive Reducer
18
Cleanout conveyor Reducer
NO.OF LUBE PT. 4
PERIOD
REF.PEMARKS
Monthly
1.3
2 Places on the shaft 2 Places on the shaft 2 Places on the shaft 2 Places on the shaft 2 Places on the shaft 1 Places on Reducer 1 Places on the shaft 2 Places on Top
Monthly
3
Biannually
3
Biannually
3
Biannually
3
Biannually
3
Monthly
3
Monthly
3
Tri- Monthly
3
Monthly
3
Monthly
3
Monthly
3
Monthly
3
Biannually
3
Biannually
2.3.4
Biannually
2.3.5
1 Places on Reducer 1 Places on the shaft 1 Places on the shaft 1 Places on the shaft 2 Places on the shaft Depends on Motor 2 Places on the shaft 4.5 6 liter ～
3.5
6 liter
～
-35-
See Remarks 6 See Remarks 6
(2) Remarks for Lubrication
a.
Grease take-up mechanism and shaft monthly.
b. Remove the plug, press in grease until fully filled, reset the plug. c. If grade of grease is to be changed, be sure of the possibility of mixing both grades in order not to deteriorate the grease and cause lubrication failure. It is preferable to thoroughly cleanse the old grease before filling in the new grade of grease.
d. Since the plug and the nipple parts from each other, power supply must be de-energized before filling in the grease. Turn the motor by hand when it is de-energized until the nipple is seen and located at the center of the hole and then fill in greases.
e. After the filling of grease, operate the motor for about 10 minutes so that grease is completely and depressurizely delivered, then put on the plug.
f.
After the first month operation of the feeder, thoroughly cleanse the filled grease and refill in new grease. Then refill grease after every six months of operation or after operation of 2500 hours.
g. When another grade of grease is intended, whether the latter grade matches with the previous one should be carefully studied. It is preferable to thoroughly cleanse the previous grade before filling in the other grade.
h. The applied lubricant should be stored according to its specified requirements to avoid from filling of decomposed and deteriorated lubricant. (3) LUBRICATION GREASE
According to jobsite ambient temperature, calcium grease or compound calcium grease or compound aluminum grease of water repelling property is optional. Notice how the operating temperature changes with seasonal variation so that suitable grade of grease can be selected. (4) LUBRICATION OIL
Usually engine oil HQ-15 is used for the reducer lubrication, however, other grades of oil may be used to suit seasonal variation and jobsite ambient temperature. Condensation Point of the oil is to be 5
6℃ lower than the lowest ambient temperature.
～
6.3 CALIBRATION OF THE FEEDER
The feeder must be recalibrated after its first month of operation. Thereafter, in addition to the six-month feeder calibration frequency, the feeder must be recalibrated whenever one of the following changes are made: adjustment of weigh roller, belt changing, or replacement of a load cell module, the CPU board or the microprocessor program chip.
7. TROUBLESHOOTING GUIDE 7.1 DIANGOSTIC LED INDICATORS
The four red LED indicators on the door of the microprocessor cabinet are energized to signal that the feeder or its controls requires attention. These indicators, and the appropriate response to each of them, are listed below. 7.1.1 Alarm -36-
This indicates that a problem exists which requires attention, but which is not serious enough to immediately stop feeder operation. To learn the code number of the problem, press: SHIFT (yellow) ERROR RECALL (yellow)
The error code number will be displayed above the LED panel. Refer to Section 7.3 for a translation of the error code and for suggested corrective action. To reset the alarm and deenergize the indicator when the problem has been corrected, press any of the while keys. If the feeder is in operation, press the white key corresponding to its current operating mode once again to reset the alarm. 7.1.2 Trip
This indicates that a problem exists which is serious enough that feeder operation has been stopped. This occurs, for example, when the feedback signal is lost: when a motor starter fault, gross speed error or feeder discharge plug-gage is detected, or when material is present on the belt in the LOCAL mode or during the calibration procedure. To learn the code number of the problem, press: SHLFT (yellow) ERROR RECALL (yellow)
The error code number will be displayed above the LED panel. Refer to Section 7.3 for a translation of the error code and for suggested corrective action. To reset the trip and deenergize the indicator when problem has been corrected, press any of the white keys. 7.1.3 Volumetric
This indicates that a fault exists in the weighing system or its electronics which prevents the feeder from operating in the gravimetric mode. Check for a defective load cell or for a defective analog-to-digital converter. The indicator will be de-energized when the microprocessor determines that the feeder can again operate in the gravimetric mode. 7.1.4 Maintenance
This indicates that routine lubrication and service of the feeder is now due. To reset the 720 hour running timer and de-energize the indicator when servicing is completed, press: SHIFT (yellow) F1 (yellow) NOTE
RESETTING THE FEEDER RUNNING TIMER ALSO RESETS THE RESTART COUNTER. REFER TO SECTION 7.4 7.2 ERROR RECALL
An alarm or trip is always associated with an error code number which can be examined in the TOTALIZED WEIGHT display by pressing in sequence the SHLFT (yellow) and ERROR RECALL (yellow) keys. The displayed response to this command activity
depends upon the mode the feeder is currently operating in: Remote Mode
The error code for the most recent alarm or trip will be displayed for five seconds while the feeder continues to run. Off Mode -37-
In this mode, the codes of the eight previous alarms and trips can be examined. The error code is displayed with an index number to its left indicating the specific error being displayed. The most recent error has a zero index. The following is an example of error conditions that might have occurred. Index
Error Code 0
13
1
09
2
04
3
01
4
03
5
00
6
00
7
00
When the ERROR RECALL keys is invoked, the latest error code, 13 in this example, follows the zero in the display, indicative of the most recent alarm of trip. To examine what specific error occurred before this, press the down arrow key ↓ (blue) causing the display to show the index number 1 and error code 09. This means that the error having the code number 09 happened prior to the error having code number 13. To proceed back into the history of feeder alarms and trips, press the down arrow ↓ (blue) key. To go forward to ward the most recent error, press the up arrow key ↑ (blue) When in ERROR RECALL mode, all error code numbers can be cleared by pressing CLEAR. For units equipped with the keyboard lock feature, the error list can be cleared only when the keyboard is enabled. In this example, only five error occurred since the index 5, 6, and 7 was last cleared. The error recall mode must be terminated by pressing the OFF (blue) key before the feeder can be operated in the REMOTE or LOCAL mode. If the microprocessor keyboard mode select switches have been disabled by entering a value of 2 into set-up parameter 26, the error recall mode is terminated by pressing SHFT (yellow) EXIT (yellow). 7.3 ERROR CODES
The following are translations of the error codes with suggested areas of corrective action. Error Description Alarm/ Possible Cause Number Trip 01 A/D converter over range Alarm Defective load cell and/or cable. Defective A /D converter (analog front 02 03
05
A/D not converting Loss of tachometer feedback
EEPROM write error
end components). Alarm Defective A/D converter Trip The electronics does not sense the belt drive motor turning. The motor can still be jogged, but cannot be run in LOCAL or REMOTE. Stalled or defective motor. Alarm
-38-
Defective tachometer. Defective U43, device or socket.
06
NVRAM defective
07
Feeder discharge plugged
08
Material on belt in LOCAL or CALIBRATE
Alarm
Defective U44 device, power down sense circuits, or too low of a power loss threshold. Feeder discharge valve closed or pluggage in feeder outlet hopper or downspout. Maladjusted feeder discharge Switch
Trip
Trip
paddle or limit switch LSFD cams. Close the inlet valve above the feeder any empty the belt. Check for defective valve operator or valve position
09
Remote TCI error (TOTALIZED WEIGHT
Alarm
display)
10
Feedrate error
indicator,
if one
is
supplied. The total material integrator pulses cannot keep up with the delivery rate and some pulses are being lost. Operating parameter #07 is set too small for too large a federate. A maximum of five pulses per second can be generated. Increase parameter #07 setting Per
Alarm
Section 4.2.2. The demand federate has not been met, usually because of an empty belt. Verify that the green FEEDING indicator is Deenergized. Check that the federate demand may be too high for the density of the material even with the belt operating at maximum
11
Motor starter fault
Trip
12
Motor speed control error
Trip
speed. The belt drive motor starter does not open or close upon command. The belt drive motor or motor speed control is producing a serious motor speed deviation from the desired speed. The system will trip if the motor speed discrepancy is greater than±100 rpm for more than 30 seconds.
7.4 SELF TEST SUMMARY
1.
To compare tare percent change from the previous feeder calibration, press:
SHIFT (yellow) SELF TEST (yellow) 1 (blue)
2.
To compare belt travel percent change from the previous feeder calibration, press:
SHIFT (yellow) SELF TEST (yellow) 2 (blue)
3.
To compare span percent change from the previous feeder calibration, press: SHIFT (yellow) SELF TEST (yellow) 3 (blue)
4.
To test all indicator lamps and displays, press:
SHIFT (yellow) SELF TEST (yellow) 4 (blue)
All displays and indicators will be energized for five seconds and then return off automatically. This test can be performed only with the feeder in the OFF mode. 5.
The restart counter monitors the power supply to the controls by incrementing one
count for each time power is reapplied. To check the number in the counter, press:
-39-
SHIFT (yellow) SELF TEST (yellow) 5 (blue)
To reset the total in the counter to zero, press: SHIFT (yellow) F1 (yellow) NOTE
RESETTING THE RESTART COUNTER ALSO RESETS THE FEEDER RUNNING TIMER WHICH IS USED TO INDICATE WHEN ROUTINE SERVICE OF THE FEEDER IS DUE. 6.
If run mode 0, 1 or 2 is programmed as the set-up parameter in Address 03, the input
demand signal will be displayed in tons per hour. If run mode 3, 4 or 5 is programmed in Address 03, the motor running speed will be displayed in rpm. To check the input demand signal or motor speed, press: SHIFT (yellow) SELF TEST (yellow) 6 (blue)
7.
To identify the program chip currently installed in the microprocessor board, press:
SHIFT (yellow) SELT TEST (yellow) 8 (blue)
The upper display on the microprocessor keyboard will read, for example, “2712812”; and the lower display will read, for example, “20”. The displays can be understood as follows: 27128 = IC manufacturer’s number 12
= program family number
2
= program revision number
0
= manufacturing number irrelevant to field use.
8.
To view the raw A/D reading from the load cells, press:
SHIFT (yellow) SELF TEST (yellow) 9 (blue)
The upper display on the microprocessor keyboard will show the signal from load cell J1; the lower display will show the signal from cell J2. NOTE
SELF TEST 9 CAN BE PERFORMED ONLY WHEN THE FEEDER IS OPERATING IN THE LOCAL OR OFF MODE.
8. SPECIAL ACCESSORY Special accessory supplied with the feeder is for adjustment and calibration. The accessory is to be properly stored so that damage or deform does not occur. Electrical instrument is to be humid-proof stored. (1)
CHECKING BAR
In checking the linearity of weigh and weigh span roller, both checking bars are respectively placed on roller surface at either side of the belt and then check and regulate with a gauge ruler. On installation of the feeder, checking bar is also used to level the feeder. (2)
ROLL DISMANTLE PROP
Roll dismantle prop is used to replace the belt and to mount or dismantle the roller by sliding the roller in or out of the feeder sideways. (3)
ROLL RAISER
When dismantling the drive pulley, open the discharge end door and hang the roll raiser on corresponding holes on the inner wall of the feeder. Turn the adjusting nut of the raiser to -40-
