Ash Handling System in Thermal Power Plant
Table of Contents
We generate a lot of energy from coal in thermal power plants. These power plants produce a lot of ash because coal has a high ash content. Therefore, the ash handling system needs to be highly efficient. Ash handling systems are essential for upholding environmental regulations and industry standards. The following are the main interlocks in thermal power plants‘ ash handling systems.
- Conveying pressure not low
- Instrument air pressure not low
- Silo level not high
Ash Handling System
The control panel for the ash handling system has the following components.
- Vessel Pressure Switch
- Dome Cylinder Solenoid Valve
- Conveying Back Pressure Switch
- Conveying Air Solenoid Valve
- Push-button, Indication lamp, Selector switch
- Level Switches
Seal Pressure Switch
If the seal pressure exceeds the set point indication, this is used to continuously monitor it and connect its signal to the PLC. If this signal appears on the PLC, the operator should check the system to see if there are any other issues that could be causing the seal to become damaged, such as cylinder link problems, pneumatic hose damage, or other issues.
Vessel Pressure Switch
The vessel pressure switch will be activated if there is any obstruction in the vessel line. The blockage is still not cleared as the purging process continues. In this instance, the operator must clear the block and open the line.
Conveying Back Pressure Switch
Conveying back pressure switches are used to turn the system off after a period of continuous conveying.
Dome Cylinder Solenoid Valve
The dome cylinder’s open and close operations are controlled by the solenoid valve. That ash then goes to the silo.
Conveying Air Solenoid Valve
When the conveying air solenoid is open after deposit, the ash in the vessel conveying air moves the ash to the silo.
Ash level identification can be done using a level switch of the RF admittance or ultrasonic type. So The high-level switch is used for probe mode and timer mode instrument interlock. Electrical trips can also be made with a high-high level switch.
Push-button, Indication lamp, Selector switch
Local start stop available.
Conveying air push button.
Indicator lamp is used to provide a simple LED display i.e. on or off status.
Modes of Operation
Ash handling system can run in two modes
- Timer mode
- Probe mode
Timer mode Principle
In PLC or DCS, Ash collection determines how long each ash handling system operates for. When the system first starts, the purging will occur automatically to initially clear the lines. If the line has a choke vessel pressure high indication, the purging will continue continuously to clear the choke until it enters the PLC or DCS. The solenoid valve receives the command to open the seal after the dome seal uses a pneumatic cylinder to do so. The vessel will hold the ash for a specific amount of time. The air-conveying solenoid is turned on after the dome seal has been closed. So The ash is carried by the conveying air and deposits in the silo. When the high-level switch is activated, the timing of the ash handling system will once again change.
Probe Mode Principle
When the high-level switch is activated, the system will operate continuously in this mode. After the level has returned to normal, the system will be shut down.