Industrial Automation and Process Control

Kriel Power Station – Lime Slurry Makeup Plant

This project concerns the automation of a hydrated lime slurry preparation and transfer system for Kriel Power Station. The process includes bulk lime storage, intermediate hopper replenishment, variable-speed lime dosing, water-flow regulation, slurry mixing and transfer to two dilution tanks.

Project focus: PLC control philosophy, sequential control, instrumentation, interlocking and alarm management.

Engineering scope

The documented control system incorporates automatic silo filling, level-based hopper replenishment, dosing screw control, mixing tank level regulation, pump routing and automated flushing. Operating sequences define the required equipment start/stop order, valve-position verification, process permissives and responses to abnormal conditions.

The control philosophy also specifies major and minor equipment failure responses, process alarms, emergency shutdown procedures and backup-power requirements for selected equipment.

Key automation concepts

Sequential PLC control and equipment coordination.
Process instrumentation and 4–20 mA analog signals.
Flow and level control loops.
Variable-speed drive setpoint calculations.
Equipment permissives, interlocks and feedback monitoring.
Automated pump flushing and valve sequencing.
Alarm handling and controlled shutdown/restart procedures.

Project images

Siemens SIMATIC HMI process overview for the lime slurry makeup plant, showing silo, bin, mixing tank, water control manifold, pumps and holding tanks. — Process tanks and pipework at the lime slurry plant.

Outdoor view of the lime slurry plant's large process tanks, pipework and access platforms. — HMI process overview showing the lime slurry preparation and transfer system.

Personal contribution

Contributed to control-system design, PLC programming, documentation review, simulation and testing. Commissioning activities are not included in this contribution.

Engineering value

This project provides a practical example of how process requirements are translated into structured automation requirements, linking instrumentation, equipment operation, process control and fault handling into a coordinated control philosophy.