The Analysis Controlled Injection System (ACIS) SCR controller monitors and controls all functions of an SCR, SCR/Oxidation, or SCR/DPF system: urea injection rate, ancillary system control and protection, alarming, and system monitoring/data logging.
Two control strategies are available to suit various applications: Open Loop Control or Closed Loop Control.
Either control system works with the same urea pumps, compressors, etc., working from a common urea handling system architecture.
Open Loop Control, ACIS-3 System
The ACIS-3 Open Loop Control system utilizes engine load and exhaust temperature to determine the required urea flow rate to satisfy the NOx limit. It continuously monitors urea injection rate and compares to the desired rate and adjusts accordingly.
Operator interface is via a powerful yet simple HMI with graphical representation of the entire emission system. An operator can see at a glance critical operating information such as temperatures, injection rate, exhaust pressure, etc. Additionally, if a Continuous Emissions Monitoring System (CEMS) is present, the ACIS-3 can take a NOx input from the CEMS for Closed Loop Control.
Closed Loop Control, ACIS-2 System
The ACIS-2 Closed Loop Control system builds on the Open Loop control system by adding on-board measurement of post-SCR NOx values, which it then uses to adjust urea injection to constantly achieve a specific NOx target. NOx targets of 5 ppm or lower, with concurrent low ammonia slip, can be maintained with the ACIS-2 control system.
Like the ACIS-3, the ACIS-2 has a powerful HMI which makes monitoring and setting up the system simple.
Features shared by both systems include:
- PLC based system
- User-friendly HMI interface with built-in help screens
- On-board data logging of critical operating parameters (exhaust temperatures, urea flow, differential pressure, alarms, etc.)
- Modbus TCP/IP for communicating to common BAS or SCADA systems
- Ethernet port for remote troubleshooting
Options are available to tailor the Control to the application such as HVAC for extreme ambient conditions, alternate communication protocols, ammonia flow control in lieu of urea, and others.