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Project: Cement Factory Automation (Crusher, Mill, Preheater, Cooler)

1. Process Overview

This project provides a comprehensive automation solution for four key units within a cement production line. The scope covers the control and monitoring of:

  • Crusher Unit: Primary raw material crushing and handling.

  • Material Mill Hall: Raw material grinding and separation.

  • Preheater Unit: Multi-stage preheating and calcination of raw mix.

  • Cooler Unit: Clinker cooling (e.g., grate cooler) and heat recovery.

2. VFD (Variable Frequency Drive) Application

VFDs are essential for process control and energy optimization across all major drives in the plant. The scope includes the engineering and integration of:

  • Medium Voltage (MV) VFDs:

    • Preheater/Kiln: Main Kiln Drive (for precise speed control), Preheater ID Fans, and ESP/Baghouse Fans (for optimized draft control and massive energy savings).

    • Material Mill: Main Mill Motor (for soft-starting and process optimization) and Mill Separator Fan.

    • Crusher: Main Crusher Motor (to manage high-inertia loads and prevent mechanical shock).

  • Low Voltage (LV) VFDs:

    • Cooler: Grate Cooler Fans (for precise cooling air control), Cooler Drive, and clinker transport conveyors.

    • Crusher & Mill: All material handling conveyors, feeders (e.g., Apron Feeders), and dosing units to ensure a stable, controlled flow of material.

3. Control System Architecture

The technical solution is a distributed control system (DCS), leveraging two different Siemens PLC series for optimized performance and cost:

  • Main Process Control (S7-1500):

    • Eight (8) CPU 1516-3 PN/DP controllers will be used for the high-speed, complex, and high I/O-count processes (Preheater/Kiln, Material Mill, and Crusher units). This ensures maximum performance and reliability for the plant’s core operations.

  • Local/Package Control (S7-1200):

    • Six (6) CPU 1215C DC/DC/DC controllers will be used for smaller, decentralized, or standalone package units, such as the Cooler, local dosing skids, or material transport sub-systems.

    • The CB 1241 (RS485) communication boards will be used to integrate third-party devices (e.g., weigh-feeders, instruments) via Modbus RTU.

4. Project I/O Bill of Materials

A. S7-1500 System (Main Process):

  • CPU: 8 x (CPU 1516-3 PN/DP)

  • Digital Input: 29 x (DI 32x24VDC BA)

  • Digital Output: 24 x (DQ 32x24VDC/0.5A BA)

  • Analog Input: 36 x (AI 8xU/I/RTD/TC ST)

  • Analog Output: 28 x (AQ 8xU/I HS)

B. S7-1200 System (Local/Package Control):

  • CPU: 6 x (CPU 1215C DC/DC/DC)

  • Digital I/O Combo: 23 x (SM 1223 DI16/DQ16)

  • Analog Input (Voltage/Current): 9 x (SM 1231 AI8)

  • Analog Input (RTD): 7 x (SM 1231 AI8 x RTD)

  • Analog Output: 9 x (SM 1232 AQ4)

  • Serial Communication: 6 x (CB 1241 RS485)