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[31]: Soot blower

Function blocks

Description

This function block represents the function of a soot blower control unit and has the following function:

  • If the start soot blowing sequence (impulse on the DI 1) and the soot blower release (DI 2) are active and the overload protection has not been triggered, the steam shut-off valve is opened (DO 5). Any pending alarms are reset with the start impulse (except overload protection).

  • After 2s the monitoring of the limit position (DI 5) of the steam shut-off valve is activated. If the valve is not open, the activation is reset and an error is output (DO 6 and DO 3).

  • If the steam shut-off valve is open (DI 5) and the steam pressure was built up during the next 3s (DI 6), the soot blower is started. To do this, the output DO 4, depending on the parameterization, is activated for 5s (Type 1) or continuously (Types 2 and 3). If the revolutions are counted by "limit position without stopping" (Type 2) or by time (Type 3), the output is activated continuously until the sequence has ended or the time has elapsed for X revolutions.

  • In the case of control types 1 or 2, the soot blower reaches the limit position after each complete revolution and is switched off (external hardware wiring). Pressing the limit switch also sets the input DI 7. A positive edge at the input also increases the revolution counter by 1. If the counter is less than the number of parameterized revolutions, the soot counter is restarted (for Type 1 only).

  • If there is a fault, the soot blower can be manually operated (external hardware wiring required). To do this, the software control must be deactivated by withdrawing the soot blower release (DI 2).

Function block inputs

[Type] Revolution counter

This parameter can be used to count the revolutions by timing instead of using the limit position of the soot blower. To do this, the set revolution time is taken as the basis (number of revolutions = time / revolution time). Monitoring, whether the soot blower has actually completed the corresponding number of revolutions, is not possible in this case.

If the revolutions are counted by the limit position, stopping may be switched off when the limit is reached (reduces relay switching cycles). This is not possible when revolutions are counted by timing.

0 Function switched off
1 revolutions counted using the limit position with stop for each revolution.
2 Revolutions counted using the limit position without stopping.
3 Revolutions counted using the revolution time without stopping.
[Rn] Revolutions: Number

This parameter is used to set the number of revolutions of the soot blower for each start process. Each revolution is monitored via the set time. If the time has elapsed and the soot blower has still not reached the limit position, an alarm is triggered.

  • Valid values are: 1-255

[Rt] Revolution: Duration

This parameter sets the time which the soot blower requires for one complete revolution.

  • Valid values are: 0-255s

  • The time should be selected so that it is 2-5s longer than the time actually required for one revolution.

[DI 1] Start

An ascending edge is expected as start signal.

  • The input signal is not optional and must be parameterized.

  • If an external release is available and an ascending edge was detected at the input, the soot blowing sequence is started.

  • The ascending edge at the input resets any existing faults before start-up (if this is possible).

  • If several modules are switched in succession, this input must be connected to the output DO 7 of the module switched beforehand.

[DI 2] External release

A TRUE permanent signal is expected at the input.

  • The input signal is optional. If the channel ID is parameterized to 0 or the parameterized channel is switched off, the signal is set internally to TRUE.

  • If the input is activated, the soot blower control unit is released.

  • If the release is withdrawn during operation, the soot blower control unit is reset to the initialization state.

  • If the steam shut-off valve is open, it is closed again.

  • If the revolutions are counted by the limit position, the soot blower motor is not switched off until the limit position is reached. This is specified by the hardware structure (self-retaining) and cannot be influenced by the software.

[DI 3] Operating status

A TRUE permanent signal is expected at the input.

  • The input signal is optional. If the channel ID is parameterized to 0 or the parameterized channel is switched off, the signal is internally simulated and set to TRUE at a given time.

  • If the soot blower is activated, the input must be set within 2s.

  • If the soot blower is started but the input is not set or not set in good time, the error is signaled by the output DO 1.

[DI 4] Overload protection status

A FALSE permanent signal is expected at the input.

  • The input signal is optional. If the channel ID is parameterized to 0 or the parameterized channel is switched off, the signal is set internally to FALSE.

  • Wire breakage protection must be obtained by inverting the channel.

  • If the overload protection switch is triggered or manually switched off, the input is activated.

  • A detected error is signaled by the output DO 1.

[DI 5] Steam valve: Status

A TRUE permanent signal is expected at the input.

  • The input signal is optional. If the channel ID is parameterized to 0 or the parameterized channel is switched off, the signal is internally simulated and set to TRUE at a given time.

  • The input is occupied by the "Limit position open" contact of the steam shut-off valve.

  • If the steam shut-off valve is activated, the input must be activated within 2s.

  • If the input is not activated or not activated in good time, the error is signaled by the output DO 6.

[DI 6] Steam pressure: > MIN

A TRUE permanent signal is expected at the input.

  • The input signal is optional. If the channel ID is parameterized to 0 or the parameterized channel is switched off, the signal is internally simulated and set to TRUE at a given time.

  • The input is occupied by the "> MIN" contact of the steam pressure switch.

  • If the limit switch "steam shut-off valve open" is actuated, the input must be activated within 3s.

  • If the input is not activated or not activated in good time, the error is signaled by the output DO 2.

  • Due to the wire breakage protection, the contact must be a "normally open contact" and close at steam pressure > MIN.

[DI 7] Revolution: Limit position

An ascending edge is expected at the input.

  • If the control system is configured as Type 1 or 2, the input signal is not optional and must be parameterized.

  • If the control system is configured as Type 3, the input signal is not used.

  • The control types 1 and 2 use the limit position "soot blower rotation" for counting revolutions. The soot blower reaches the limit position after each complete revolution. Pressing the limit switch generates an ascending edge at the input, causing the revolutions counter to increase by 1.

[DI 8] Fault: External

A FALSE permanent signal is expected at the input.

  • The input signal is optional. If the channel ID is parameterized to 0 or the parameterized channel is switched off, the signal is set internally to FALSE.

  • If the input is activated, the fault is connected through to the output "collective alarm" (required to link modules).

[DI 9] Acknowledge: Fault

An ascending edge is expected as acknowledgment signal.

  • The input signal is not optional and must be parameterized.

  • If the input is set (impulse), all error messages detected and saved by the software are reset.

  • The overload protection error cannot be reset, as this depends on the position of the protection switch.

Function block outputs

[DO 1] Soot blower: Fault

If a fault occurs at a frequency of 1Hz, the output is set to the TRUE value.

  • The output signal is optional.

  • The "Soot blower fault" alarm is triggered if the "Soot blower not operating" fault is detected or the overload protection is triggered.

  • Wire breakage protection can be obtained by inverting the channel.

  • The output is intended to activate the signal lamp on the control cabinet.

[DO 2] Steam pressure: Fault

If a fault occurs at a frequency of 1Hz, the output is set to the TRUE value.

  • The output signal is optional.

  • The alarm output is activated if "Steam pressure < MIN" error is detected.

  • Wire breakage protection can be obtained by inverting the channel.

  • The output is intended to activate the signal lamp on the control cabinet.

[DO 3] Common alarm

If a fault occurs, the output is set to the TRUE value.

  • The output signal is optional.

  • The alarm output is activated if at least one fault is detected.

  • The alarm output is deactivated for 3s if another fault is detected.

  • Acknowledgment of the alarms (DI 6) does not directly influence the collective alarm.

  • Wire breakage protection can be obtained by inverting the channel.

[DO 4] Start soot blower

If the soot blower is to be started, the output is set to the TRUE value.

  • The output signal is not optional and must be parameterized.

[DO 5] Steam valve: Open

If the steam shut-off valve is to be opened, the output is set to the TRUE value.

  • The output signal is not optional and must be parameterized.

[DO 6] Soot blowing: Fault

If a fault occurs, the output is set to the TRUE value.

  • The output signal is optional.

  • The alarm output is activated if one or more of the following faults occur during the soot blowing sequence:

    1. Overload protection

    2. Soot blower not in operation

    3. Steam shut-off valve not open

    4. Steam pressure < MIN

    5. Limit position is not reached within the given revolution time

  • Acknowledgment of the alarms (DI 6) does not directly influence the alarm output.

  • Wire breakage protection can be obtained by inverting the channel.

[DO 7] Soot blowing: Successful

When soot blowing has been successfully completed, the output is set to the TRUE value.

  • The output signal is optional.

  • The output signal is reset during the next start-up.

  • The output can be used as a start signal for the following module.

Reference

FUP title

Soot blower

DOC-740308455