Normally, the prevention of possible disturbances in the process is handled by the
instrumentation.
The most important parts of the process have an alarm in the control room. All the
equipment is interlocked in such a way that disturbances should not cause any serious
damage. In the case of equipment breaking or stopping, the cause of the disturbance
can easily be determined from the interlocking sequence. Should a power failure
occur, the chemical and steam valves will close automatically.
Loss of Electrical Power
When the electricity is cut off for some reason, one must first ensure that the feeding
of chemicals and steam have stopped. Second, ensure that the dilution valves of tanks
have been closed. After this the starting of the plant is begun from the end of the
process in the normal fashion (from end to beginning).
Loss of Water
If the fresh water supply should be cut off, or a low flow of fresh water makes proper
operation of the plant impossible, then stop the pulp flow. If possible, flush the press
prior to stopping the wash water.
Normally the cleanest water is used at the end of the process, for dilution at the
dilution conveyor and wash water in the press. If this water is not available, do not
operate the press. Without wash liquor, the distribution plate inside the press will
become plugged. Without dilution to the dilution conveyor, there is a substantial risk
of plugging the dilution conveyor or downstream equipment by not regulating the pulp
consistency sufficiently.
When the water supply has been restored, start up from the end of the system.
Normally, the prevention of possible disturbances in the process is handled by theinstrumentation.The most important parts of the process have an alarm in the control room. All theequipment is interlocked in such a way that disturbances should not cause any seriousdamage. In the case of equipment breaking or stopping, the cause of the disturbancecan easily be determined from the interlocking sequence. Should a power failureoccur, the chemical and steam valves will close automatically.Loss of Electrical PowerWhen the electricity is cut off for some reason, one must first ensure that the feedingof chemicals and steam have stopped. Second, ensure that the dilution valves of tankshave been closed. After this the starting of the plant is begun from the end of theprocess in the normal fashion (from end to beginning).Loss of WaterIf the fresh water supply should be cut off, or a low flow of fresh water makes properoperation of the plant impossible, then stop the pulp flow. If possible, flush the pressprior to stopping the wash water.Normally the cleanest water is used at the end of the process, for dilution at thedilution conveyor and wash water in the press. If this water is not available, do notoperate the press. Without wash liquor, the distribution plate inside the press willbecome plugged. Without dilution to the dilution conveyor, there is a substantial riskof plugging the dilution conveyor or downstream equipment by not regulating the pulpconsistency sufficiently.When the water supply has been restored, start up from the end of the system.
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