Using CompactRIO and LabVIEW to Reduce NOx Emissions from Ship Engines

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"The LabVIEW graphical user interface allows the customer to easily and efficiently monitor and control the SCR system."

- Andreas Gamborg, DANSK TEKNOLOGI

The Challenge:
Reducing NOx (nitrogen oxide and nitrogen dioxide) emissions from the Danish naval fleet to fulfill stringent environmental regulations.

The Solution:
Rapidly developing a low-cost selective catalyst reduction (SCR) system for ship engines with NI CompactRIO and LabVIEW.

Author(s):
Andreas Gamborg - DANSK TEKNOLOGI

Ships are one of the biggest sources of NOx in the world and cause pollution over land and eutrophication of the seas. On a global scale, NOx pollution is responsible for thousands of premature deaths, millions of lost work and school days, and tens of thousands of  heart attacks and hospital admissions. In the oceans, its damage includes oxygen depletion and reduced fish and shellfish populations.

The International Maritime Organization has introduced new legislation that requires progressive NOx emission reductions in new ship engines by the year 2016.

Airless Selective Catalyst Reduction Technology

The most efficient way to decrease NOx emission from diesel engines is to implement the selective catalyst reduction (SCR) technique. In this approach, a mixture of urea and deionised water, known as AdBlue, is sprayed into the exhaust gases. The heat of the exhaust system transforms urea into ammonia, which reacts with the NOx in a catalytic converter, converting emissions into harmless nitrogen gas and water vapor.

Figure 2. The Principle of the Selective Catalyst Reduction

Traditionally, the urea is sprayed into the exhaust with compressed air. However, compressed air has high energy costs and space requirements. As a result, our team at DANSK TEKNOLOGI developed an airless injection system with lower installation and running costs.

The airless technology was originally developed for use on heavy trucks and will in the future be the preferred technology within the truck industry. The heart of the system is derived from the innovative digital dosing pump technology that our team developed for Grundfos, one of the world's largest manufacturers of pumps for industrial uses. Using our expertise in this area, we aimed to develop an SCR system suited especially for marine engines.

Using CompactRIO and LabVIEW for Control

Our requirements for the control unit of the SCR system included the need for fast and reliable hardware with a real-time OS. We also required powerful software programming capabilities, and were faced with a short application development time. In addition, because the SCR system will be installed on a ship, we needed to develop a control system with marine certified hardware.

LabVIEW graphical system design software and CompactRIO hardware offered all the needed capabilities, including an efficient graphical development environment to help us meet our deadlines. We based our system on the NI cRIO-9073 chassis, which offers a real-time OS and a user-programmable field-programmable gate array (FPGA) chip. The open FPGA technology coupled with the NI 9853 CAN module allowed us to develop a custom communication protocol for the automotive NOx sensors.

We used two NI 9478 digital output modules  to control 29 valve relays in the system, and an NI 9265 analog output module to control the  pumps. The NI 9215 analog input modules measure urea pressure , engine revolution, fuel consumption and exhaust backpressure . For temperature measurements, we selected an NI 9217 RTD module.

Figure 3. The SCR System’s Graphical User Interface in LabVIEW

Results

Our customer was pleased with the new SCR system and the application delivery time. In particular, the LabVIEW graphical user interface allows the customer to easily and efficiently monitor and control the SCR system.

The Danish Navy installed the first SCR system controlled by CompactRIO and LabVIEW in October 2009 and has experienced up to a 90 percent reduction in NOx emissions. As a result, the first vessel using the system fulfills the 2016 International Maritime Organization directive years before the deadline.

Author Information:
Andreas Gamborg
DANSK TEKNOLOGI
Østre Teglværksvej 24, 3450 Allerød
Denmark
Tel: +45 48 13 50 23
aag@dansk-teknologi.dk

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