How to deal with voltage fluctuations in the reforming unit? Experts, please help!
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How to deal with voltage fluctuations in the reforming unit? Experts, please help! Thank you! In the event of a long power outage, such as for several hours, does the reforming reactor need to maintain its temperature and pressure?
⒈Quickly close the valve for delivering hydrogen gas, pre-activate the waste hydrogen discharge valve of the hydrogen gas-liquid separation tank, and keep the system under pressure by holding it in place； Close the outlet valve of the pre-hydrogenation feed pump and the liquid delivery valve of the pre-hydrogenation gas-liquid separation tank. ⒉By opening the steam vent and condensate drain of the turbine, it will be possible to get the lubrication oil pump back online as soon as possible ； ⒊Inspect the furnace; if the eternal flame goes out, shut off the gas cut-off valve promptly and blow steam into the furnace chamber ； If the eternal flame remains lit, shut off the gas cut-off valve promptly while keeping the eternal flame intact ； ⒋Close the outlet valve of the pump that is to be shut down ； ⒌Upon receiving the call, promptly start the reforming cycle unit and the pre-hydrogenation cycle unit in accordance with the operating procedures to establish a hydrogen circulation, paying attention to the liquid level in the gas-liquid separation tank ； ⒍Heating of the batch reactor ； ⒎Introduce refined oil into the reformer, and gradually increase the temperature while continuing with the adjustment procedures ； ⒏Introduce reformed hydrogen into pre-hydrogenation; use pre-hydrogenation to start up the feedstock processing ； ⒐Once the pre-hydrogenation refined oil passes the testing, the entire process is activated.
7.3.1 Handling of power outage incidents
7.3.1.1 Symptoms of the incident
(1) All pumps and machines stop operating; flow indicators return to zero.
(2) All lights go out and do not turn back on immediately.
7.3.1.2 Cause of the incident
The power grid ceases to supply electricity.
7.3.1.3 Confirmation of the incident
On-site pumps and air-cooling fans have stopped operating.
7.3.1.4 Measures to handle the incident
(1) Immediate actions
① Extinguish all heating furnaces.
② Maintain pressure in the reforming reaction system and pre-hydrogenation reaction system.
③ Manually control all control valves to prevent overheating or overpressure.
(2) Operational objectives
① Extinguish heating furnaces to prevent overheating of the catalyst beds.
② Maintain system pressure to facilitate a smooth restart of operations.
③ Prevent high-pressure fluid from flowing into low-pressure sections, thereby avoiding secondary incidents.
(3) Potential problems
① Overheating of catalyst beds.
② High-pressure fluid flowing into low-pressure sections, leading to secondary incidents.
③ Excessive and rapid drop in system pressure.
(4) Operating procedures
**Level A operations**
1. Make contact with relevant personnel.
2. Immediately extinguish all heating furnaces.
3. Maintain pressure in both hydrogen-containing and non-hydrogen-containing systems.
4. Stabilize liquid levels in high- and low-pressure separators to prevent high-pressure fluid from entering low-pressure sections.
5. Handle reciprocating compressors and centrifugal pumps accordingly.
6. Manage the waste heat boiler properly.
7. Manage towers as required.
**Contingency state:** Pre-hydrogenation furnaces are extinguished and pressure is maintained; reforming furnaces are likewise extinguished and pressure is maintained.
**Level B operations**
1. Make contact with production dispatch to determine the extent of the power outage.
Report the situation to shift supervisors and members of the emergency response team.
Notify the diesel hydrotreating unit to prepare for prolonged interruption of hydrogen supply.
Notify the jet fuel desulfurization unit to prepare for prolonged interruption of hydrogen supply.
Notify the hydrogenated dewaxing (diesel hydrorefining) unit to prepare for prolonged interruption of hydrogen supply.
2. Immediately extinguish all heating furnaces.
(P) Verify that interlocks have caused F-102 and F-201–F-204 furnaces to shut down.
Close all burner valves and extinguish pilot lights.
Shut down main burners in reboilers at tower bottoms and extinguish their pilot lights.
3. Maintain pressure in both hydrogen-containing and non-hydrogen-containing systems.
Close pressure control valve D-201.
Close manual valve at hydrogen outlet point No. 25 on D-201.
Close pressure control valve D-102.
Close manual valve at hydrogen outlet point No. 25 on D-102.
Close pressure control valves D-101, D-103, and D-203.
(P) Verify that pressures in high-pressure separators and reflux drums remain within safe limits.
(P) Verify that reactor bed temperatures stay within acceptable ranges; if overheating occurs, open appropriate high-pressure separator pressure control valves to relieve pressure.
4. Stabilize liquid levels in high- and low-pressure separators to prevent high-pressure fluid from entering low-pressure sections.
Close level control valves for high-pressure separators.
Close level control valves for low-pressure separators.
(P) Verify that liquid levels in high-pressure separators remain above 40%.
If levels drop too rapidly, close upstream and downstream valves of the respective level control valves.
(P) Verify that liquid levels in low-pressure separators remain above 40%.
If levels drop too rapidly, close upstream and downstream valves of the respective level control valves.
On-site, close inlet and outlet valves of all pumps.
5. Handle reciprocating compressors and centrifugal pumps.
In the control room, press emergency stop buttons for all reciprocating compressors.
Close seal oil supply valves; monitor oil supply from the overhead oil tank of unit K-201 closely and keep track of coast-down time.
After compressors stop running, turn their shafts once every three minutes at 180° intervals.
Set load levers of reciprocating compressors to 0%; close inlet and outlet valves, open interconnecting valves, vent all gas from the compressor casing, then close vent valves.
6. Manage the waste heat boiler.
Vent steam from D-401 to the atmosphere.
7. Manage towers as required.
Try to maintain tower top pressure within the range specified in process specifications.
Ensure liquid levels in all towers and reflux drums remain within normal process limits.
Contingency state: Pre-hydrogenation furnaces are extinguished and pressure is maintained; reforming furnaces are likewise extinguished and pressure is maintained.
7.3.1.5 Resuming operations after power restoration
1. Conduct single-tower circulation for each tower.
(P) Verify that liquid levels at tower bottoms remain above 50%; if below 50%, use refined oil to raise levels to 70%.
Start circulation pumps at tower bottoms.
Ignite burner flames in reboilers at tower bottoms following normal startup procedures; adjust operating parameters to maintain single-tower circulation.
2. Verify that the waste heat boiler operates normally.
(P) Verify that P-401 continues circulating.
(P) Verify that liquid level in D-401 remains normal.
3. Start recycle hydrogen compressor K-201 and ignite the “four-in-one” furnace.
(P) Verify that pressure in D-201 remains no lower than 0.8 MPa(g).
Off-site personnel and compressor operators jointly start K-201 per standard startup procedures and bring it to full load.
Ignite burner flames in the “four-in-one” furnace following normal procedures.
Raise temperature in the fourth reforming reactor at a rate of 15–20°C until reaching 370°C, then hold steady.
4. Start recycle hydrogen compressor K-101 and ignite F-101.
(P) Verify that pressure in D-102 (PIIC2102) remains no lower than 2.0 MPa(g).
Off-site personnel and compressor operators jointly start K-101 per standard startup procedures and bring it to 100% load.
Ignite burner flames in F-102 following normal procedures.
Raise outlet temperature of F-101 at a rate of 15–20°C until reaching 200°C, then hold steady.
5. Feed oil into the reforming system.
Resume chlorine and water injection into the reaction system.
Reconfigure pipelines so that refined oil from the tank farm flows into the plant; prime pump P-105/2.
(P) Verify that outlet temperatures of F-201–F-204 reach 370°C.
Start P-105/2 to pump refined oil into C-102 as a cushion.
(P) Verify that bottom liquid level in C-102 (LIC-2106) exceeds 70%.
Start P-108 to feed oil into the reforming reaction system.
Once oil appears in high-pressure separator D-201, raise its temperature at a rate of 15–20°C/h northward toward the fourth reforming reactor.
When liquid level in D-201 exceeds 50%, feed oil into D-203.
When liquid level in D-203 exceeds 50%, feed oil into C-201.
When liquid level in C-201 (LIC-2206) exceeds 60%, transfer excess oil to the oil storage facility.
(P) Verify that the reforming reaction system generates hydrogen and that pressure in D-201 (PIC-2201) rises.
(P) Verify that pressure in D-201 (PIC-2201) reaches 1.20 MPa; switch PIC-2201 to automatic control mode with a setpoint of 1.20 MPa, and route waste hydrogen to the plant-wide gas network.
6. Feed oil into the pre-hydrogenation system.
(P) Verify that hydrogen purity in D-201 exceeds 75% (V).
Start K-202 per normal procedures and bring it to 100% load to supply hydrogen to the pre-hydrogenation system.
(P) Verify that pressure in D-102 (PIC-2102) reaches 4.0 MPa(g).
Switch PIC-2102 to automatic control mode with a setpoint of 4.0 MPa.
Start P-101 to pump reforming feedstock into C-101.
(I) Verify that liquid level in C-101 (LIC-2101) exceeds 70%.
Start P-105/1 to pump bottom oil from C-101 into the pre-hydrogenation reaction system.
(P) Verify that liquid level in D-102 (LIC-2103) exceeds 60%.
Open LIV-2103 to reduce oil flow into C-102 while maintaining D-102 liquid level between 40% and 50%.
Stop operation of P-105/2 while keeping C-102 liquid level between 45% and 55%.
7. After all systems are interconnected, adjust operating parameters accordingly.
(P) Verify that all systems are fully interconnected; increase reforming feed rate to normal levels.
Adjust all operating parameters per process specifications.
Notify and supply hydrogen to all hydrotreating units.
Resume corrosion inhibitor injection.
Verify that inlet and outlet valves of all idle pumps remain closed.
**Note:**
1. (1) When pressure in the reforming system exceeds 0.8 MPa and pressure in the pre-hydrogenation system exceeds 2.0 MPa, the pre-hydrogenation system may be started first. After producing qualified refined oil, this oil can be used to start up the reforming system. (2) When the pressure in the reforming system is below 0.8 MPa while the pressure in the pre-hydrogenation system is high, hydrogen can be introduced into the reforming system via pre-hydrogenation to ensure that its pressure remains above 0.8 MPa. In such cases, the refined oil from the tank area should be used to start the reforming system first, followed by starting the pre-hydrogenation system. (3) When it is not possible to ensure that the pressure in the reforming system is greater than 0.8 MPa, first introduce the refined oil from the tank area into the hydrogen production system; use the crude hydrogen produced to start up the reforming system, and then feed it into the pre-hydrogenation system. 2. The ignition of each heating furnace must be carried out in strict accordance with the \"Heating Furnace Operation Procedures\"
7.3.1.1 Symptoms of the incident
(1) All pumps and machines stop operating; flow indicators return to zero.
(2) All lights go out and do not turn back on immediately.
7.3.1.2 Cause of the incident
The power grid ceases to supply electricity.
7.3.1.3 Confirmation of the incident
On-site pumps and air-cooling fans have stopped operating.
7.3.1.4 Measures to handle the incident
(1) Immediate actions
① Extinguish all heating furnaces.
② Maintain pressure in the reforming reaction system and pre-hydrogenation reaction system.
③ Manually control all control valves to prevent overheating or overpressure.
(2) Operational objectives
① Extinguish heating furnaces to prevent overheating of the catalyst beds.
② Maintain system pressure to facilitate a smooth restart of operations.
③ Prevent high-pressure fluid from flowing into low-pressure sections, thereby avoiding secondary incidents.
(3) Potential problems
① Overheating of catalyst beds.
② High-pressure fluid flowing into low-pressure sections, leading to secondary incidents.
③ Excessive and rapid drop in system pressure.
(4) Operating procedures
**Level A operations**
1. Make contact with relevant personnel.
2. Immediately extinguish all heating furnaces.
3. Maintain pressure in both hydrogen-containing and non-hydrogen-containing systems.
4. Stabilize liquid levels in high- and low-pressure separators to prevent high-pressure fluid from entering low-pressure sections.
5. Handle reciprocating compressors and centrifugal pumps accordingly.
6. Manage the waste heat boiler properly.
7. Manage towers as required.
**Contingency state:** Pre-hydrogenation furnaces are extinguished and pressure is maintained; reforming furnaces are likewise extinguished and pressure is maintained.
**Level B operations**
1. Make contact with production dispatch to determine the extent of the power outage.
Report the situation to shift supervisors and members of the emergency response team.
Notify the diesel hydrotreating unit to prepare for prolonged interruption of hydrogen supply.
Notify the jet fuel desulfurization unit to prepare for prolonged interruption of hydrogen supply.
Notify the hydrogenated dewaxing (diesel hydrorefining) unit to prepare for prolonged interruption of hydrogen supply.
2. Immediately extinguish all heating furnaces.
(P) Verify that interlocks have caused F-102 and F-201–F-204 furnaces to shut down.
Close all burner valves and extinguish pilot lights.
Shut down main burners in reboilers at tower bottoms and extinguish their pilot lights.
3. Maintain pressure in both hydrogen-containing and non-hydrogen-containing systems.
Close pressure control valve D-201.
Close manual valve at hydrogen outlet point No. 25 on D-201.
Close pressure control valve D-102.
Close manual valve at hydrogen outlet point No. 25 on D-102.
Close pressure control valves D-101, D-103, and D-203.
(P) Verify that pressures in high-pressure separators and reflux drums remain within safe limits.
(P) Verify that reactor bed temperatures stay within acceptable ranges; if overheating occurs, open appropriate high-pressure separator pressure control valves to relieve pressure.
4. Stabilize liquid levels in high- and low-pressure separators to prevent high-pressure fluid from entering low-pressure sections.
Close level control valves for high-pressure separators.
Close level control valves for low-pressure separators.
(P) Verify that liquid levels in high-pressure separators remain above 40%.
If levels drop too rapidly, close upstream and downstream valves of the respective level control valves.
(P) Verify that liquid levels in low-pressure separators remain above 40%.
If levels drop too rapidly, close upstream and downstream valves of the respective level control valves.
On-site, close inlet and outlet valves of all pumps.
5. Handle reciprocating compressors and centrifugal pumps.
In the control room, press emergency stop buttons for all reciprocating compressors.
Close seal oil supply valves; monitor oil supply from the overhead oil tank of unit K-201 closely and keep track of coast-down time.
After compressors stop running, turn their shafts once every three minutes at 180° intervals.
Set load levers of reciprocating compressors to 0%; close inlet and outlet valves, open interconnecting valves, vent all gas from the compressor casing, then close vent valves.
6. Manage the waste heat boiler.
Vent steam from D-401 to the atmosphere.
7. Manage towers as required.
Try to maintain tower top pressure within the range specified in process specifications.
Ensure liquid levels in all towers and reflux drums remain within normal process limits.
Contingency state: Pre-hydrogenation furnaces are extinguished and pressure is maintained; reforming furnaces are likewise extinguished and pressure is maintained.
7.3.1.5 Resuming operations after power restoration
1. Conduct single-tower circulation for each tower.
(P) Verify that liquid levels at tower bottoms remain above 50%; if below 50%, use refined oil to raise levels to 70%.
Start circulation pumps at tower bottoms.
Ignite burner flames in reboilers at tower bottoms following normal startup procedures; adjust operating parameters to maintain single-tower circulation.
2. Verify that the waste heat boiler operates normally.
(P) Verify that P-401 continues circulating.
(P) Verify that liquid level in D-401 remains normal.
3. Start recycle hydrogen compressor K-201 and ignite the “four-in-one” furnace.
(P) Verify that pressure in D-201 remains no lower than 0.8 MPa(g).
Off-site personnel and compressor operators jointly start K-201 per standard startup procedures and bring it to full load.
Ignite burner flames in the “four-in-one” furnace following normal procedures.
Raise temperature in the fourth reforming reactor at a rate of 15–20°C until reaching 370°C, then hold steady.
4. Start recycle hydrogen compressor K-101 and ignite F-101.
(P) Verify that pressure in D-102 (PIIC2102) remains no lower than 2.0 MPa(g).
Off-site personnel and compressor operators jointly start K-101 per standard startup procedures and bring it to 100% load.
Ignite burner flames in F-102 following normal procedures.
Raise outlet temperature of F-101 at a rate of 15–20°C until reaching 200°C, then hold steady.
5. Feed oil into the reforming system.
Resume chlorine and water injection into the reaction system.
Reconfigure pipelines so that refined oil from the tank farm flows into the plant; prime pump P-105/2.
(P) Verify that outlet temperatures of F-201–F-204 reach 370°C.
Start P-105/2 to pump refined oil into C-102 as a cushion.
(P) Verify that bottom liquid level in C-102 (LIC-2106) exceeds 70%.
Start P-108 to feed oil into the reforming reaction system.
Once oil appears in high-pressure separator D-201, raise its temperature at a rate of 15–20°C/h northward toward the fourth reforming reactor.
When liquid level in D-201 exceeds 50%, feed oil into D-203.
When liquid level in D-203 exceeds 50%, feed oil into C-201.
When liquid level in C-201 (LIC-2206) exceeds 60%, transfer excess oil to the oil storage facility.
(P) Verify that the reforming reaction system generates hydrogen and that pressure in D-201 (PIC-2201) rises.
(P) Verify that pressure in D-201 (PIC-2201) reaches 1.20 MPa; switch PIC-2201 to automatic control mode with a setpoint of 1.20 MPa, and route waste hydrogen to the plant-wide gas network.
6. Feed oil into the pre-hydrogenation system.
(P) Verify that hydrogen purity in D-201 exceeds 75% (V).
Start K-202 per normal procedures and bring it to 100% load to supply hydrogen to the pre-hydrogenation system.
(P) Verify that pressure in D-102 (PIC-2102) reaches 4.0 MPa(g).
Switch PIC-2102 to automatic control mode with a setpoint of 4.0 MPa.
Start P-101 to pump reforming feedstock into C-101.
(I) Verify that liquid level in C-101 (LIC-2101) exceeds 70%.
Start P-105/1 to pump bottom oil from C-101 into the pre-hydrogenation reaction system.
(P) Verify that liquid level in D-102 (LIC-2103) exceeds 60%.
Open LIV-2103 to reduce oil flow into C-102 while maintaining D-102 liquid level between 40% and 50%.
Stop operation of P-105/2 while keeping C-102 liquid level between 45% and 55%.
7. After all systems are interconnected, adjust operating parameters accordingly.
(P) Verify that all systems are fully interconnected; increase reforming feed rate to normal levels.
Adjust all operating parameters per process specifications.
Notify and supply hydrogen to all hydrotreating units.
Resume corrosion inhibitor injection.
Verify that inlet and outlet valves of all idle pumps remain closed.
**Note:**
1. (1) When pressure in the reforming system exceeds 0.8 MPa and pressure in the pre-hydrogenation system exceeds 2.0 MPa, the pre-hydrogenation system may be started first. After producing qualified refined oil, this oil can be used to start up the reforming system. (2) When the pressure in the reforming system is below 0.8 MPa while the pressure in the pre-hydrogenation system is high, hydrogen can be introduced into the reforming system via pre-hydrogenation to ensure that its pressure remains above 0.8 MPa. In such cases, the refined oil from the tank area should be used to start the reforming system first, followed by starting the pre-hydrogenation system. (3) When it is not possible to ensure that the pressure in the reforming system is greater than 0.8 MPa, first introduce the refined oil from the tank area into the hydrogen production system; use the crude hydrogen produced to start up the reforming system, and then feed it into the pre-hydrogenation system. 2. The ignition of each heating furnace must be carried out in strict accordance with the \"Heating Furnace Operation Procedures\"
On the upper floor, the second-to-last one – are you saying to use hydrogen from pre-hydrogenation for the reverse reforming process? This will not poison the reforming catalyst. Is there a problem?
At this time, does the hydrogen production booster stop?
The method for dealing with a sudden power outage in a catalytic reforming unit depends on the actual circumstances. 1. If both the high-voltage and low-voltage electrical equipment of the device are powered off for an extended period, I believe the following measures should be taken: (1) Turn off all heating furnaces. (2) Stabilize the reforming and pre-hydrogenation reaction systems by maintaining pressure. (3) Confirm that all operating equipment is shut down ； And be ready to ship at any time. (4) Wait for power restoration and the order to start up the equipment. (5) Make all preparations for commencement of work.
This post was last edited by Purification on 2009-5-10 22:38. Pre-hydrogenated hydrogen must under no circumstances flow back into the reformer; if pressure supplementation is required in the reformer, startup hydrogen must be used. The principle for handling accidents is to protect the catalyst and the reactor. Pressure holding is necessary; it is required for the safety of the entire system as well as to enable rapid operation. If the circulating hydrogen is interrupted, the temperature inside the heating furnace will rise rapidly in a short period of time, leading to undesirable consequences; it is necessary to stop feeding material and cut off the gas supply immediately. Under no circumstances should the gas supply be kept on while trying to maintain the temperature” ； If the recycle hydrogen compressor remains operational and the recycle hydrogen flow is normal, the boiler’s forced circulation pump will inevitably stop due to the power outage; as a result, the heating furnace must be shut down, and insulation becomes impossible. The determining factor in handling the incident is whether the reforming cycle hydrogen compressor is shut down and whether the cycle hydrogen supply is interrupted. Answering the original poster’s second question: During a power outage, if the booster pump is motor-driven, it has stopped operating ； If the booster is a turbine and is not shut down, the anti-rotation valve can be manually opened first, the hydrogen outlet valve closed, the speed of the booster reduced, in order to maintain the pressure in the reforming reaction and recontact sections. After finishing other tasks and confirming that power supply cannot be restored in the short term, it’s not too late to shut down the system.
Personal opinion: In an emergency, ignore all the lengthy procedures outlined in the guidelines; focus on the key points: 1. The liquid level in the product separation tank and the contact tank must not reach full capacity – immediately start the pump at the bottom of the separation tank and adjust the flow path to bypass the contact tank； 2. Check whether the circulating hydrogen compressor is shut down. If it isn’t shut down, then there is no major issue. If it is shut down, conditions for restarting it must be met as soon as possible, both indoors and outdoors. If power is available, the compressor can be restarted promptly (if the booster is still running, stop it first) ； 3. If the cycle hydrogen compressor stops, the heating furnace and feed system also shut down in a cascade; the operator on duty closes the burner control valve, and the operator outside confirms this ； 4. Pay attention to the drum liquid level; it should neither be full nor empty.
Just follow the emergency shutdown procedures. The person on the 3rd floor was too wordy; the one on the 2nd floor was more concise and practical.
Just follow the emergency shutdown procedures. The person on the 3rd floor was too wordy; the one on the 2nd floor was more concise and practical.
This post was last edited by athunder on 2009-5-13 22:07. Based on years of experience in managing reformation units, there are mainly 5 key points: 2 pieces of equipment, 2 pumps, and 2 series valves. That is, there are 5 key factors to pay attention to: the temperature in the furnace of the heating furnace, the high-pressure levels in the reforming and pre-hydrogenation units, the pre-hydrogenation temperature as well as the temperatures in the four reactors, and the positions where the high- and low-pressure phases are connected. It is important to keep the temperature in the heating furnace below 800 degrees, to prevent excessive high pressures in both units, and to control the temperatures of the six reactors properly; if possible, bed shutdown operations should be carried out. Note that if the furnace temperature in all furnaces is not very high, try to avoid using steam for cooling in order to save time when restarting operations. Be careful to prevent high pressure from leaking into low pressure areas, such as between the pre-hydrogenation high-pressure stream and the evaporator tower, between the reforming high-pressure stream and the inlet of the pre-hydrogenation compressor, at the outlet of the reforming feed pump, and at the outlet of the pre-hydrogenation feed pump. The two units, namely the pre-hydrogenation compressor and the reforming compressor, are core equipment of the reforming unit; proper attention must be paid to them in order to prevent overpressure and overheating. The two pump units are the pre-hydrogenation feed pump and the reforming feed pump; be sure to close the outlet valves to prevent backpressure and excessive current. Because having a shut-off valve at the outlet of some pumps can cause overcurrent in the pump. The two valve trains, namely the valves connecting the outlet of the reforming feed pump to the pre-hydrogenation unit and those in the reforming unit, must be closed. The two valves leading from the high-pressure hydrogen from the reforming unit to the buffer tank at the inlet of the pre-hydrogenation compressor also need to be closed, while the backflow valve should be opened. Following these principles will prevent any problems. As for some small pumps, towers, air coolers, and small tanks, they can be ignored during the processing stage; they can be dealt with after the above key steps have been completed. Otherwise, you’ll die of exhaustion trying to finish all that work, and accidents will still happen in the end. Let the tower fill up; just ignore it as long as there’s no overpressure. The above are the principles for handling shutdown situations. Of course, these same steps can be applied in case of an emergency restart; it’s just that in such cases, only the 5 key elements need to be considered – the 2 devices, 2 pumps, and 2 series valves. Sometimes no actions are required at all, and as long as those 5 key elements are taken care of, there’s no need to worry! ! ! The above are the experiences accumulated over the years, and can be applied to dealing with power outages and DCS screen failures. Please leave your comments.