Rick explains the challenges that are presented when designing scrubbers: “On a ship, there is an exhaust pipe or funnel (chimney). A scrubber installation is approximately 11 metres high and variable in diameter from 2 to 6 metres. It is placed in the exhaust pipe or funnel or, if it cannot be fitted here, the installation will be placed on the back of the ship as a ‘backpack’. Exhaust gas rises through the outlet and passes through a kind of shower of pumped-up seawater. This misting, dispersed via spray nozzles, causes the saltwater to sag downwards as a blanket of spray and bind with the sulfur particles. The contaminated water is then discharged below the waterline. Scrubbers remove around 99% of sulfur dioxide and particulate matter from the exhaust gases.”
 
Seawater is used to clean the exhaust gases in the gas cleaning installation. An aggressive corrosive environment is created by combining saltwater with the high temperatures produced from exhaust gases. There are two important challenges in the design of the installation. The exhaust pipe or funnel needs to be made of Alloy 254 SMO, a highly resistant stainless steel and therefore also resistant to corrosive seawater. "Rubber mounts are used for mounting the scrubber as the heat causes the pipe or funnel to expand by several centimetres and, of course, vibrations and ship motions may also occur", says Rick. "Adjusting the resistance of the ship's engine is also a very precise job, as it must be exactly right."
 
In addition to saltwater and heat, another very important challenge is the available space. Frans Nieuwkoop, Mechanical Engineer at Iv-Consult, has seen the significance of this challenge on a number of ships around the world: ”I have conducted several surveys on ships where we needed to install scrubbers. What was especially noticeable was the number of different piping systems crammed into a small space such as the funnel (chimney) of the ship. It was, therefore, quite a challenge for us to identify available space to install our system components and connect the pipework.”

To make the fitting and measuring easier, especially in the funnel, engine room and the areas surrounding existing pipework, Iv-Consult, in collaboration with Iv-Infra, developed an innovative working method for the 3D scanning of sea-going vessels, cruise ships, oil tankers, bulk carriers and container ships. This method allows both the supplier VDL-AEC and shipowners to select the appropriate scrubber for the ship in question. Various CAD packages are combined with the 3D scan data which allows a 3D model to be generated very quickly.

“What actually makes this project program even more special is that about 15 to 18 employees of Iv are involved in each project and these are not just people from Iv-Consult. The team consists of employees from Iv-Consult, Iv-Industrie, Iv-Infra, Iv-Offshore & Energy, Iv-Water and Nevesbu. Having a diverse team means we can go beyond the conventional markets in which we operate."

The extensive article can be found in our magazine.