Project Scope

Design, engineering, supply, installation, and commissioning of a complete control system including PLCs (Programmable Logic Controllers), field instruments, VFD-based MCC (Variable Frequency Drive-based Motor Control Center) panels, and SCADA (Supervisory Control and Data Acquisition) for a rotary kiln-based activated carbon factory.

Background

Activated carbon production is a vital industrial process used in various applications, from air and water purification to gold extraction and pharmaceuticals. However, many activated carbon factories face issues with consistent error states during production, leading to variations in the quality and properties of the produced activated carbon, ultimately impacting its efficiency and effectiveness.

Primary Contributors to Error States:

• Variation in Raw Material Feed Rate: Fluctuations in moisture levels within the raw materials can result in inconsistent feed rates, leading to disparities in the final product’s characteristics.
• Variation in Steam Quantity: The activation process relies on the controlled application of steam within the rotary kiln. Inaccuracies in the amount of steam applied can cause deviations in the porosity and adsorption capacity of the activated carbon.
• Temperature Variations: The temperature range of 800 to 950 degrees Celsius is crucial for achieving the desired properties of activated carbon. Inconsistent temperatures can lead to variations in the final product’s hardness and porosity.
• Variation in Air Quantity: The controlled introduction of air into the kiln is critical. Irregularities in the air quantity can disrupt chemical reactions and impact the quality of the activated carbon.

The client utilized a steam-based activation process where charcoal is heated within a rotary kiln to create activated carbon. Steam enhances the porosity of the carbon’s surface, optimizing its adsorption capacity. The goal was to produce activated carbon with high adsorption capacity and maintained hardness. To achieve consistent and optimal production conditions, automation was necessary.

System Description

A fully automated control system was developed, spanning from supply, installation, and commissioning of field instruments, wireless communication systems, PLC control systems, VFD-MCC packages, and SCADA.

Key Components:

• Field Instruments: Level transmitters for silo level measurement, air and steam flow meters, steam pressure transmitters, thermocouples/RTDs (Resistance Temperature Detectors) for temperature measurements, and steam control valves for closed-loop control of the steam line.
• Control System: Mitsubishi Electric IQR series modular PLCs, A800 Series VFDs, and Genesis64 SCADA with robust communication protocol CCLINK (speed up to 1GBPS).

Base Feed Rate Control:

• Material feed was regulated and fed to the weigh feeder via a rotary valve, allowing synchronized control of both components. The system provided real-time indications for feeder running status, overload status signals, underload status, total material feed in the kiln, etc.

Precise Temperature Regulation:

• To ensure meticulous temperature management, the kiln was divided into five distinct zones for comprehensive monitoring and accurate recording of temperature variations. Alarms were configured for high and low temperatures.
• Real-time temperature data from five zones of the kiln were integrated into the SCADA system using RF (Radio Frequency) wireless technology. The wireless component was powered by a battery, ensuring continuous operation.

Steady Steam Flow Regulation:

• A consistent steam flow rate into the kiln was maintained using a combination of a steam flow transmitter (orifice-based DP measurement) and a pressure control valve (electro-pneumatic) in a closed-loop flow control system.

Motor Control Center (MCC):

• A complete MCC was deployed for all motor starters. Motor speed was efficiently managed through the SCADA system in auto mode, with manual control allowing for motor start and stop actions from local control stations. Continuous silo level, temperature, and air flow monitoring were implemented. Interlocks were placed to ensure safety and prevent backfires.

SCADA Integration:

• The entire process was visually represented through a process flow diagram integrated with comprehensive data on SCADA. Data recording was facilitated for in-depth future studies and analytics.

Result

• Consistent Quality: Thorough regulation of raw material feed rates, temperature, and steam levels has resulted in consistent and superior quality carbon generation.
• Improved Efficiency: The automated control system’s seamless operation, coupled with safety interlocks, has improved production efficiency and fortified safety measures, boosting overall operational excellence.
• Milestone Achievement: Establishment of the first fully automated activated carbon plant in India, managed seamlessly from the control room.
• Industry 4.0 Ready: The implemented solution is Industry 4.0 ready, simplifying the customer’s ability to roll out digitalization initiatives in the upcoming phase.