E-25-2.4-380D Steam Boiler Control System

The automated control system serves the E-25-2.4-380D natural-circulation steam boiler, which burns natural gas and produces superheated steam for process use. Its stated design parameters are 25 tonnes per hour, 24 kgf/cm² steam pressure after the boiler and a steam temperature of 380°C.

During the control-system upgrade, variable-frequency drives were added to the forced-draught fan and induced-draught fan, the gas train and gas fittings were replaced, and the superheater was reconstructed. The upgrade aimed to widen the boiler’s control range and improve efficiency, particularly at reduced load.

Monitoring and control functions

• Collect measurements every 0.5 seconds, including temperature, flow and pressure in the steam–water, gas–air and fuel paths, drum level, flue-gas oxygen and actuator positions;
• Check measurement validity and calculate derived parameters, including flow speeds, temperature differences, water and steam properties, and technical and economic indicators;
• Display process information as diagrams, trends and tables, with visual, audible and text warning and emergency alarms;
• Regulate boiler heat load, furnace draught, combustion-air supply with oxygen correction, and outlet steam temperature;
• Provide equipment protections for gas pressure, drum level, steam temperature, air and feedwater pressure, furnace conditions and fan operation;
• Automate boiler start-up and shutdown sequences, including tightness testing, ventilation, ignition, planned shutdown and emergency shutdown;
• Archive trends, event logs and operating records.

Control hardware and software

The lower level uses a SIMATIC S7-300 industrial controller with a CPU315 processor. Its listed signal modules include four SM 331-1KF01 modules for 4–20 mA signals, an SM 321-1BL00 digital-input module and an SM 322-1BL00 digital-output module. The controller software was developed in STEP 7 using S7-SCL.

An industrial PC with an LCD monitor and keyboard forms the operator station. It provides visualisation, archiving, alarms and information transfer. The upper-level SCADA software is Termocont, developed at KPI. The controller communicates with the workstation through an MPI interface using an OPC server.