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First, the processing of process water interruption
(1) Fault phenomenon
1. The process water pressure is low and the alarm signal is sent.
2. Water is interrupted everywhere in the production site.
3. The liquid level of the relevant slurry tank drops.
4. The vacuum belt dewatering machine and the vacuum pump trip.
(2) Analysis of the cause
1. The running process water pump is faulty, and the backup pump linkage is unsuccessful.
2. The process water pump outlet door is closed.
3. The process tank level is too low and the process water pump trips.
4. The process water pipe is broken.
(3) Processing method
1. Confirm that the vacuum belt dewatering machine and vacuum pump are connected normally.
2. Stop the gypsum discharge pump operation.
3. Stop feeding immediately and stop the filtrate pump operation.
4. Identify the cause of the process water interruption, report the value of the long and divided points in time, and restore the water supply as soon as possible.
5. Stop the corresponding pump operation according to the flushing water tank and the filter cake flushing water tank liquid level.
6. During the treatment process, closely monitor the temperature of the absorption tower, the liquid level and the change of the liquid level of the limestone slurry tank, and if necessary, deal with the short-term shutdown.
Second, the desulfurization booster fan failure
(1) Fault phenomenon
1. The "desulfurization booster fan trips" sound and light alarm is issued.
2. The indicator light of the desulfurization booster fan is red, the yellow light is on, and the motor stops rotating.
3. The desulfurization bypass baffle and the absorption tower ventilation baffle are automatically opened, and the inlet and outlet flue gas baffles are automatically closed.
4. If the slurry system is automatically injected, the chain stops feeding.
(2) Analysis of the cause
1. The accident button is pressed.
2. The desulfurization booster fan loses power.
3. The absorption tower recirculation pump is completely stopped.
4. The pressure loss of the desulfurization device is too large or the inlet and outlet flue gas baffles are not in place.
5. The temperature of the booster fan bearing is too high.
6, the motor bearing temperature is too high.
7. The motor coil temperature is too high.
8. The fan bearing vibration is too large.
9, electrical faults (overload, overcurrent protection, differential protection action).
10. The booster fan surges.
11. The dust content in the hot flue gas is too large.
12. The boiler load is too low.
(3) Processing method
1. Confirm that the desulfurization bypass baffle and the absorption tower ventilation baffle are automatically opened, and the inlet and outlet flue gas baffles are automatically closed. If the chain is bad, it should be handled manually.
2. Check the cause of the booster fan trip. If it is caused by a chain action, it should be restarted after the system returns to normal.
3. If it is caused by the failure of the fan equipment, it should report the value of the length and the field in time, and contact the maintenance personnel for processing. It is strictly forbidden to restart the fan until the fault has been verified.
4. If the operation cannot be resumed within a short period of time, it shall be treated according to the provisions of short-term shutdown.
Third, the absorption tower recirculation pump stops
(1) Fault phenomenon
1. The "recirculation pump trip" sound and light alarm signal is sent.
2. The red light of the recirculation pump is off, the green light is on, and the motor stops rotating.
3. Open the bypass baffle and the exhaust baffle in the chain, stop the booster fan, and close the flue gas baffle of the desulfurization inlet and outlet of the two units.
(2) Analysis of the cause
1, 6KV power supply is interrupted.
2. The absorption tower liquid level is too low.
3. Absorption tower liquid level control loop failure
(3) Processing method
1. Confirm that the chain action is normal. Confirm that the desulfurization bypass baffle of the two units and the ventilation baffle of the absorption tower are automatically opened, and the booster fan is tripped; the flue gas baffle of the two units is automatically closed. If the booster fan is not tripped and the baffle is not working properly, it should be handled manually. .
2. Identify the cause of the trip of the recirculation pump and dispose of it according to relevant regulations.
3. Report the value and length of the report in time, and notify the relevant maintenance personnel if necessary.
4. If the operation cannot be resumed within a short period of time, it shall be handled according to the relevant provisions of short-term shutdown.
5. Depending on the temperature of the smoke in the absorption tower, turn on the defogger flushing water to prevent damage to the absorber liner and the demister.
Fourth, 6KV power interruption
(1) Fault phenomenon
1, 6KV bus voltage disappears, sound and light alarm signal is issued, CRT alarm;
2. The desulfurization equipment in operation trips, and the 6KV motor corresponding to the busbar is stopped;
3. The corresponding 380V busbar in this section will lose power, and the corresponding 380V load will be tripped.
(2) Analysis of the cause
1, 6KV busbar failure;
2. The generator of the unit trips and the backup power supply fails to be put into operation;
3. Desulfurization failure The backup power supply failed to be invested.
(3) Processing method
1. Confirm whether the desulfurization interlocking tripping action is completed. If the flue baffles are not working properly, they should be automatically cut into manual operation immediately.
2. Confirm that the USP segment and DC system are powered normally, the working power switch and the standby power switch are in the off position, and disconnect the load switches;
3, the contact value and electrical maintenance personnel, to find out the cause of the failure to restore power;
4. If the feeding system interlocking does not work, the feeding should be stopped manually;
5, pay attention to monitor the changes in the temperature of the flue gas system, if necessary, manually open the defogger flushing watergate;
6. Close the booster fan regulating baffle to the minimum position and prepare to restart the desulfurization device;
7. If the 6KV power supply cannot be recovered in a short time, follow the relevant regulations of the shutdown, and discharge the slurry in the pipeline and the pump body as soon as possible to avoid deposition;
8. If the 380V power supply is interrupted, handle it according to the corresponding regulations.
Five, 380V power supply interruption
(1) Fault phenomenon
1, 380V power supply interruption "acoustic alarm signal is sent;
2, 380V voltage indication to zero, low voltage motor trip;
3, work lighting trip, accident lighting input;
(2) Analysis of the cause
1. The corresponding 6KV busbar fault;
2. Desulfurization low pressure trip;
3, 380V bus failure.
(3) Processing method
1. If it is caused by a 6KV power failure, it will be stopped according to short-term shutdown;
2. If it is a 380V single-stage fault, check the cause of the fault and the operation of the equipment, and disconnect the power switch and each load switch from the section and report it in time;
3. When the 380V power supply is completely interrupted and the power supply cannot be recovered within 8 hours, all the pumps and pipelines should be drained and flushed in time using spare equipment;
4. The power supply caused by the electrical protection action is strictly forbidden to send power blindly.
Sixth, GGH failure
(1) Fault phenomenon
GGH failure
(2) Analysis of the cause
1. Motor motor overload or transmission failure;
2, the seal is too tight or stuck;
3. The debris is stuck;
4. Guide bearing or support bearing is damaged
(3) Processing method
1. Identify the cause for processing;
2. If the current is too large and the motor overheats, stop the GGH operation and contact the maintenance.
Seven, gypsum discharge pump failure
(1) Fault phenomenon
1. The CRT sends an alarm signal.
2. The inlet pressure of the gypsum cyclone is 0.
(2) Analysis of the cause
1, the pump protection stops,
2. The accident button action.
(3) Processing method
1. It should be confirmed that the standby pump has been started and reported to the squad leader to contact the inspection and repair;
2. If both gypsum slurry pumps fail and stop, and the concentration of the slurry in the absorption tower exceeds 15%, the report value is long and the FGD operation is exited.
Eight, gypsum cyclone failure
(1) Fault phenomenon
The underflow of the cyclone is reduced.
(2) Analysis of the cause
The cyclone is fouled and the pipe is clogged.
(3) Processing method
1. When the hydrocyclone and its pipeline fouling affect the operation, stop the gypsum slurry pump operation, then manually flush the cyclone and its pipeline.
2. If the patrol is invalid when reporting, please contact the squad leader and contact us for troubleshooting.
Nine, limestone slurry pump failure
(1) Fault phenomenon
1. The CRT sends an alarm signal, and the exit flow indication is 0.
(2) Analysis of the cause
1, the pump protection stops,
2, accident button action
(3) Processing method
1. It should be confirmed that the standby pump has been started and reported to the squad leader for contact with the maintenance.
2. If both limestone slurry pumps fail, and the pH value of the absorption tower is continuously decreasing, the report value is long and the FGD operation is exited.
X. Overflow tank and return tank agitator failure
(1) Fault phenomenon
CRT sends an alarm signal
(2) Analysis of the cause
1, protection stops,
2, accident button action
(3) Processing method
Report to the squad leader, contact the overhaul to deal with it, and put it into operation as soon as possible.
The agitator is allowed to shut down for 8 hours.
Eleven, limestone slurry tank agitator failure
(1) Fault phenomenon
The CRT sends an alarm signal.
(2) Analysis of the cause
1, protection stops,
2. The accident button action.
(3) Processing method
1. Report to the squad leader, contact the overhaul to handle it, and put it into operation as soon as possible.
2. If the agitator is faulty for a long time, the system cannot be pulped, and the pH value of the absorption tower is continuously decreasing. Reporting value is long, exit FGD operation
Twelve, star feeder failure
(1) Fault phenomenon
CRT sends an alarm signal
(2) Analysis of the cause
1. Feeder protection stop, 2, chain failure, 3. Feeder card, 4. Accident button action.
(3) Processing method
1. It should be confirmed that the spare feeder has been started and reported to the squad leader to contact the inspection and repair.
2. If both feeders fail, the pulp cannot be pulped. When the pH value of the absorption tower drops continuously, the report value is long and the FGD operation is exited.
Thirteen, instrument air compressor failure
(1) Fault phenomenon
1. The CRT sends an alarm signal.
2. The export pressure is 0.
(2) Analysis of the cause
1. Protection stops.
2. The accident button action.
(3) Processing method
1. It should be confirmed that the air compressor for the standby instrument has been started and reported to the squad leader for contact with the maintenance.
2. If both air compressors are used, the fault will be stopped, the report value will be long, and the FGD operation will be exited.
Fourteen, process water pump failure
(1) Fault phenomenon
1. The CRT sends an alarm signal.
2. The export pressure is 0.
(2) Analysis of the cause
1, protection stop, 2, motor failure,
3. The accident button action.
(3) Processing method
1. It should be confirmed that the standby process water pump has been started and reported to the squad leader for contact with the maintenance.
2. If both process pumps fail, the report will be long and the FGD will be exited.
Fifteen, defogger flushing pump failure
(1) Fault phenomenon
1. The CRT sends an alarm signal. 2. The outlet pressure is 0.
(2) Analysis of the cause
1, protection stop, 2, motor failure, 3, accident button action. (3) Processing method
1. It should be confirmed that the standby defogger pump has been started and reported to the squad leader for contact with the maintenance.
2. If both demister pumps are faulty, the report will be long and the FGD will be exited.
Sixteen, defogger failure
(1) Fault phenomenon
1. The CRT sends out an alarm signal. 2. The demister has a higher pressure drop.
(2) Analysis of the cause
1. The defogger is not clean enough. 2. The defogger is fouled.
(3) Processing method
1. The scale area should be determined through on-site inspection, and the flushing of the scale area should be increased by the modification of the cleaning program to reduce the flushing of other areas.
2. If the defogger alarm is issued in the control room, the operator will manually clean it after confirming.
Seventeen, smoke system failure
(1) Fault phenomenon
1. The CRT sends an alarm signal.
2. Flue gas pressure and temperature are not normal.
(2) Analysis of the cause
1. FGD inlet flue gas pressure and temperature are not satisfied
2. GGH is grayed out.
(3) Processing method
1. First, check whether the FGD inlet flue gas pressure and temperature meet the requirements. If the requirements are not met, the report value is required to increase the temperature and pressure of the flue gas; if the flue gas meets the requirements, this may be GGH ashing and application process water cleaning.
2. If the GGH fails, it is necessary to determine whether it is necessary to stop the GGH and the entire FGD system according to the specific situation.
3. If the GGH is not faulty and the exit smoke temperature is low, this may be caused by the ash on the heated surface, and the purge should be strengthened.
Eighteen, oxidizing air
If the three oxidizing air compressors are not operational, the FGD system can still operate for about 6 hours. At this time, the pH setting of the absorption tower slurry should be reduced to 5.0. The content of CaSO3?1/2H2O in the absorption tower needs to be measured every hour.
If there is no oxidizing air for a long time in the oxidizing air nozzle, the piping must be cleaned.
Nineteen, the filter is blocked
If the pressure before the circulation pump and the gypsum discharge pump is too low, the filter screen may be blocked and an alarm signal will be generated in the control room. At this point, the standby circulation pump must be started and the circulating pump that issued the alarm must be stopped. After the operation is stopped, the process water will automatically clean the filter. After cleaning, the circulation pump can be restarted or used as a backup.
Twenty, the baffle seal fan failure
When the running sealed fan trips and the backup sealed fan can't start automatically, the report value is long. Contact the maintenance to deal with the fault and put it into operation as soon as possible.
When both sealed fans are out of service and the FGD is bypassed, consider that a small amount of flue gas leaks into the absorption tower of the original flue gas inlet baffle. For cooling, open a flushing water gate of the demisters.
Twenty-one, boiler oil operation
If the boiler is put into operation and the electrostatic precipitator is not put into use, the report value is long and the flue gas of the unit is withdrawn from the operation of the FGD system.
Twenty-two, electrostatic precipitator failure
FGD is in operation. If there are two or more electric field faults on one side of the electrostatic precipitator, the FGD outlet flue gas contains more than 350mg/Nm3, the report value is long, and the flue gas of the unit is exited in the operation of the FGD system.
Twenty-three, the grave is heavily ash
Severe dust accumulation in the FGD's inlet flue and bypass flue has an effect on the normal switching of the baffle. When the FGD system and boiler are out of service, check and clean up the dust.
Twenty-four, SO2 removal efficiency is low
Approach
1 calibration SO2 measuring instrument
2 calibration pH meter
3 If possible, add a layer of running spray layer
4 If possible, add a layer of running spray layer
5 Check the limestone slurry dose; increase the limestone slurry feed amount; check the limestone reaction performance
6 check the number of circulating pumps and the output of the pump
7 Start the operation of the wastewater (if it is not running at this time)
8 Check GGH sealing fan and low leakage fan
Twenty-five, the absorption tower slurry concentration is high
Approach
1 check density measuring instrument
2 reduce boiler load
3 reduce boiler load
4 check the outlet pressure and flow, start the standby pump
5 increase the number of swirls in operation
6 Check the outlet pressure and flow rate of the gypsum discharge pump
7 cleaning gypsum cyclone
8 check concentration measuring instrument
9 Check the concentration of the underflow of the cyclone
Twenty-six, vacuum belt conveyor system failure
(1) Fault phenomenon
1. Insufficient slurry
2, vacuum seal water flow is insufficient
3, belt track offset
4, vacuum pump failure
5, vacuum pipeline system leakage
6, the dust concentration is high
7, anti-wear with damage
8, the belt conveyor speed is abnormal
(2) Processing method
1. Check valve opening and strengthen feeding
2, check the filter cloth rinse pump
3, check the belt deviation control module
4, check the vacuum pump
5, check the vacuum line, whether there is a strange sound
6, check the filter cake thickness control module
7, check the tension of the filter cloth
8, inspection, belt machine operation
Twenty-seven, FGD detection instrument failure
(1) Fault phenomenon
1. PH meter failure 2. Density measurement fault 3. Liquid flow measurement fault 4. SO2 meter fault 5. Flue pressure measurement fault 6. Liquid level measurement fault 7. Flue gas flow measurement fault
(2) Processing method
1, automatically do not count this value. The pH meter needs to be flushed at this time. Repair as soon as possible. It must be tested manually once per hour, and then root 2, according to the actual pH value to control the amount of limestone slurry added. The PH meter must be repaired immediately and put into service as soon as possible after calibration.
3, the density needs manual measurement; the density meter should be repaired as soon as possible, and put into use as soon as possible after calibration.
4. Clean or re-calibrate with process water.
5. Turn off the meter and purge with compressed air. The operator should immediately check and make parameter control.
6. Purge or mechanically clean with compressed air.
7. Use process water or manual cleaning.
8. Purge with compressed air. When the flue gas flow cannot be accurately measured, the addition of limestone slurry should be changed to manual. Also pay attention to the trend of PH value to make corresponding adjustments.
Twenty-eight, accident non-interlocking shutdown
When the following phenomena occur, the desulfurization system should be isolated as soon as possible for the protection of the equipment and appropriate measures should be taken.
1. When the GGH original flue gas side or the net flue gas side differential pressure is greater than 0.75KPa, after the high pressure water flushing is invalid, the operation should be stopped;
2. The imported smoke temperature is normal, GGH works normally, the inlet smoke temperature of the absorption tower is low, and the alarm signal is issued. There is no obvious change after stopping the oxidation fan, and the operation should be stopped.
3. When two limestone pulping pipelines fail to make pulp, they should be shut down after operation;
4. When the accident occurs in the production site and control room, which endangers the equipment and personal safety, it should be stopped immediately;
5. In the process of handling FGD outage, the possibility of slurry deposition in the slurry tank, tank and pump body should be considered first, and the slurry in the pipeline and the vessel should be drained and flushed as appropriate.
Twenty-nine, the common causes of the factors affecting the quality of desulfurized gypsum
The dust in the smoke is high. The dust in the flue gas will enter the slurry during the desulfurization process due to washing. When the content of impurities in the slurry is high, it cannot be completely discharged with dehydration, which increases the content of impurities in the finished gypsum and affects the quality of the gypsum. The reason for the high dust content in the flue gas is mainly caused by poor coal quality and poor electrostatic dust removal. When the dust content in the inlet flue gas exceeds the standard, contact the boiler to check the electric dust removal operation in time, and properly close the small vane fan vane opening degree. Enter the amount of flue gas desulfurization, and resume the normal operation of the desulfurization system after the electric dust removal returns to normal. It is also possible that after the dehydration, the waste water is discharged less, and the impurities of the absorption tower are accumulated more and more.
The absorption tower slurry has a high content of calcium sulfite. The main reason for the increase in calcium sulfite content is caused by insufficient oxidation. Under normal circumstances, due to the low oxygen content in the flue gas (about 4% to 8%), the sulfur oxides in the flue gas generated after combustion of the boiler are mainly Sulfur dioxide, in the process of desulfurization, the slurry absorbs sulfur dioxide to form calcium sulfite. The desulfurization system supplies air to the absorption tower through the oxidation fan, forcibly oxidizes calcium sulfite to form calcium sulfate, and calcium sulfate combines with two water molecules to form gypsum molecules. When the gypsum reaches After a certain degree of saturation, the crystals are precipitated, and after dehydration, the finished gypsum is produced. However, for various reasons, the calcium sulfite cannot be fully oxidized (causes that the oxidizing air flow rate is insufficient; the oxidizing air pressure does not meet the requirements; the absorption efficiency of the absorption tower agitator is not good, etc.), and the content of calcium sulfite in the slurry rises. High, eventually the quality of the finished gypsum is reduced, and at the same time, it will cause a series of adverse effects such as poor dewatering effect, poor desulfurization efficiency of the desulfurization system, and increased consumption of limestone. At this time, check the operation of the oxidation fan (pressure, current, flow, etc.), whether there is air leakage in the oxidized air mother pipe, and appropriately reduce the amount of smoke if necessary; or discharge part of the absorption tower slurry, add fresh water, and wait for the absorption tower. The internal slurry quality is improved and then resumes normal operation.
The absorption tower slurry has a high content of calcium carbonate. As a desulfurization absorbent, calcium carbonate should be continuously replenished during the operation of the desulfurization system. In order to ensure the desulfurization effect, the absorption tower should maintain a certain pH value, and sometimes the pH value is kept high, so that the calcium carbonate content in the slurry will be Higher; it is also possible that limestone activity is poor. After the limestone slurry is replenished into the absorption tower, it cannot be fully ionized in a short time, and it cannot react with sulfur dioxide, and eventually enters the gypsum with dehydration. Both of these conditions also affect the quality of the gypsum. In the operation, it is necessary to properly control the PH value, taking into account the de-rate effect and the gypsum quality. At the same time, pay attention to the replenishment amount of the limestone slurry. When the large amount of limestone is added and the pH rise is not obvious, the limestone activity may be poor, and the limestone must have sufficient time. Ionization in the absorption tower.
The filter cake is not fully rinsed. The main function of the filter cake washing is to reduce the concentration of chloride ions in the gypsum. Normally, the concentration of chloride ions in the finished gypsum is less than 100PPm. The flushing of the filter cake can meet this requirement. Sometimes, due to insufficient flow of filter cake flushing water, it is possible The concentration of chloride ions in the gypsum will exceed the standard; it is also possible that the concentration of chloride ions in the gypsum slurry is high, and the content in the gypsum is also high. This is likely to be the content of hydrogen chloride in the flue gas, or it may be that the amount of waste in the dehydration process is small, and finally The chloride ion concentration in the slurry in the absorption tower is continuously increased. The method is to increase the flow of filter cake flushing water while increasing the amount of wastewater discharged.
The dehydration effect is not good and the water content exceeds the standard. There are many reasons for the poor dehydration effect. It may be that the pressure of entering the hydrocyclone at the first stage of dehydration is too low. The effect of the first dehydration is not good, and the overall dehydration effect is not good, but the effect is generally small. The pressure can be appropriately increased; the dehydration vacuum is insufficient to cause the dehydration effect to be bad. At this time, check the operation of the vacuum pump (current, vacuum pump seal water, vacuum degree, vacuum tube, blockage, vacuum pipe leakage, filtrate) Whether the liquid level of the water tank is low, so the vacuum cannot be maintained), check whether the sealing water of the vacuum belt is normal, whether the thickness of the filter cake is too high, whether the vacuum belt is uneven, whether the crack of the filter cake on the vacuum belt causes a large leak.
(Source: Chemical 707)
[Editor: Chen Guofang]
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