Customer application 21 September 2017
I/O System for Exhaust Gas Cleaning aboard Ships

Emission limits are in effect in many harbors and coastal zones; however, the majority of ships that use conventional fuels cannot comply with them. Therefore, shipping companies must retrofit their fleets with appropriate technologies in order to continue their international operations without limitations. ETB Energietechnik Bremen develops and sells specialized exhaust gas post-treatment systems that significantly reduce emissions. The control and monitoring equipment used in this technology must withstand harsh conditions at sea. For this reason, ETB chose the WAGO-I/O-SYSTEM.

International shipping primarily uses fuels that have problematic emissions, like high levels of soot, nitrogen oxides and sulfur oxide. This contaminates the air, primarily in coastal areas and in harbor cities, more than is permitted. In the past few years, numerous regulations on emissions from ships have been enacted, affecting sulfur oxides (SOx), nitrogen oxides (NOx), ozone depleting agents (including CFCs), incineration of garbage and trash on board, energy efficiency (EEDI) and the introduction of “Emission Control Areas” (ECAs).

Propulsion Control – Here’s How WAGO Supports You:

  • The WAGO-I/O-SYSTEM 750 XTR is temperature-resistant from −40 °C to +70 °C

  • Vibration-proof up to 5g

  • Immunity to impulse voltages as per EN 60870-2-1

New Upper Limits

MARPOL, Annex VI, the “International Convention for the Prevention of Pollution from Ships,” now applies stricter limits on ship fuels throughout the world. Shipping companies are obligated to install specialized filter systems in order to reduce exhaust gas residues. For example, since 2010, the North and Baltic Seas, as ECA areas, have set a limit of 1 % for sulfur in ship’s fuel, which was lowered to 0.1 % on January 1, 2015. ETB Energietechnik equips both new and old ships with exhaust gas cleaning systems that ensure compliance with these emission limits. The company has years of experience in the energy and environmental sectors and specializes in technologies including diesel particle filters.

Approximately 99 % of the Particles Are Filtered Out

ETB recently provided the exhaust gas post-treatment system for a new construction project involving a 105-meter private yacht. ETB’s system uses ceramic honeycomb filters to remove around 99 % of the solid particles from the engine exhaust gas. The residues collect in the honeycomb filters and are oxidized into water vapor and carbon dioxide due to the high temperatures that occur during operation. “Using our system, we achieve an extremely high filtering effect, whereas gas cleaning systems, so-called scrubbers, can only bind around 50 % of the soot particles,” explains Michael Bajohr, Technical Manager at ETB. In addition to the improved cleaning effect, he also emphasizes the reduced spatial and maintenance requirements of his filter systems. “We don’t have any moving parts. In addition, maintenance for ash deposits only has to be carried out approximately every 2,500 to 4,000 operating hours. In contrast, scrubbers are significantly larger, they constantly produce a large amount of wastewater, or the systems are only operated in harbors. Our technology has become the standard, especially on passenger ships.”

Limited Space and Extreme Conditions

The cleaning performance and energy consumption of the filter systems are constantly controlled and optimized by an electronic control system. “The control system components are accommodated in a control cabinet. However, we have very little space on board for this and often have to cope with extreme environments. Since many ship owners want to avoid air-conditioning the control cabinet to prevent the buildup of condensation, we had to seek out suitable electrical and electronic components,” says ETB’s Technical Manager, listing some of the challenges for their system.

Robust and Suitable for −40 °C to +70 °C

On ships, the salt-laden air, high temperature fluctuations, strong vibrations, shock loads and large electrical voltage fluctuations in the on-board power supply demand a high level of fail safety in the electrical equipment and electronic controllers. ETB therefore required a very robust and compact I/O system that could withstand average environmental temperatures from −5 °C to +55 °C and wouldn’t fail during hot or cold spikes. After checking into multiple suppliers, ETB decided on the WAGO-I/O-SYSTEM 750 XTR. In addition to maritime certifications, by Germanischer Lloyd (GL) among others, the electromagnetic compatibility, resistance to interference, fail safety and fieldbus-independent interfaces tipped the scales in favor of the automation system manufactured in Minden.

Better Control and Minimal Energy Demand

The exhaust gas flows from the diesel engines are divided into separate strands for better control and to minimize the energy consumed by the incineration process. They are then fed separately through the filtration system. The temperature of each air flow is individually monitored according to the exhaust gas volume of the engine. Sensors constantly record the engine load, pressure and temperature. ETB relies on an 852-111 ETHERNET Switch, a 750-352/040-000 Fieldbus Coupler and corresponding I/O modules for analog and digital inputs and outputs in order to manage these data inputs and forward them to the controller. The fieldbus coupler generates a digital process image from the physical inputs and outputs, and the higher-level controller accesses the process image via MODBUS/TCP.

Robust Technology, Good Service

In addition, ETB developed new software for the private yacht project that incorporates additional convenience functions, including an ash monitoring model. During maintenance of the filter elements, the yacht’s operator is thus no longer simply dependent on rule of thumb estimates, the accuracy of which can vary, since they depend on the amount of lubricant used, the type of lubricant and the level of contamination in the fuel. The new software constantly monitors the operating status of the filter and, thanks to the improved control, reduces energy consumption by approximately one-third. “We chose the right technology with the WAGO-I/O-SYSTEM 750 XTR, and we also want to use it in other projects,” says Michael Bajohr, confirming that his experiences with WAGO have been positive.


  • For Extreme Environments

  • Immunity to electromagnetic interference and impulse voltages

  • Vibration and shock resistance

  • Explosion protection

Author: Norman Südekum

Photos: Martin Ortgies

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