Scrubbers at a glance
Sixteen months before the 2020 sulphur cap takes effect, time for choosing a compliance strategy is running out. A quick overview of scrubber technology.
Exhaust gas cleaning systems (EGCS), or scrubbers, are becoming a more frequently used technology for ships to achieve compliance with the 2020 sulphur cap. A scrubber sprays seawater or fresh water mixed with a caustic chemical into the exhaust gas stream in several stages. The pollutant – mainly sulphur dioxide – reacts with the alkaline water, forming sulphuric acid. In the case of an open-loop system, the resulting wash water is discharged back into the sea.
In areas and ports where open-loop scrubbing is prohibited, ships can use closed-loop systems and collect the accumulated sludge on board for subsequent disposal at a suitable in-port facility.
Hybrid scrubber systems can operate either in closed-loop or in open-loop mode, offering more flexibility. A multi-inlet scrubber can treat the exhaust gas from several engines, whereas a single-inlet scrubber serves one engine only. It is important to weigh all options for a given ship and trading pattern carefully to ensure the economic sustainability of the chosen solution
![Closed-loop vs. open-loop scrubbers](/siteassets/images/contact-images/mf_industry_067_closed-loop-vs.-open-loop-scrubbers.jpg?mode=crop&scale=both&quality=90&format=webp&width=768)
![Scrubber](/siteassets/images/contact-images/kp_industry_067_scrubber.jpg?mode=crop&scale=both&quality=90&format=webp&width=768)
Closed-loop scrubbers
Closed-loop systems add chemicals, such as caustic soda, to the wash water to boost its alkalinity. The wash water is then recirculated through the system and partially purged.
![Scrubber](/siteassets/images/contact-images/kp_industry_067_scrubber.jpg?mode=crop&scale=both&quality=90&format=webp&width=768)
Open-loop scrubbers
Open-loop systems use seawater, which is alkaline by nature, to wash the SOX out of the exhaust. The resulting discharge water must meet MARPOL requirements before being discharged.
![Scrubber](/siteassets/images/contact-images/kp_industry_067_scrubber.jpg?mode=crop&scale=both&quality=90&format=webp&width=768)
Growing demand
Time is pressing; the 2020 sulphur cap forces shipowners and operators to act. There are currently almost 1,300 ships with confirmed scrubber projects.
![Scrubber](/siteassets/images/contact-images/kp_industry_067_scrubber.jpg?mode=crop&scale=both&quality=90&format=webp&width=768)
The current market
The majority of the recently signed projects are for bulk and oil/chemical vessels. Open-loop scrubbers are the most popular. But for the vessels operating inside areas where wash water discharge to sea is restricted, closed-loop or hybrid systems are required.
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