Technology
Scrubber technology is not something new. It is proven technology and well documented. Experienced companies can engineer systems to meet performance requirements. One issue, when installing on a ship, is that the requirement changes with the area the ship operates.
The 0.5% requirement is global. The 0.1% requirement applies to ECA zones like EU. Furthermore, there is a ban on liquid discharge in some ports.
Technology
Scrubber technology is not something new. It is proven technology and well documented. Experienced companies can engineer systems to meet performance requirements. One issue, when installing on a ship, is that the requirement changes with the area the ship operates.
The 0.5% requirement is global. The 0.1% requirement applies to ECA zones like EU. Furthermore, there is the ban on liquid discharge in some ports.
To meet the different requirements, scrubber vendors have come up with three different modes of operation
Open loop
Let’s start by considering the open loop operation first, as it is the most simple, and most cost effective operation. In this mode the flue gas is simply sprayed with seawater which is used only once, hence the term open loop, as it really is no loop at all.
In open loop mode the scrubber will absorb SOx in seawater. SOx is acidic and seawater contains some alkalinity. Provided that we use sufficient amounts of water, the spent liquid may be discharged directly to the sea. The requirement is that pH > 6.5 and that the depth of discharge is >4m.
Hybrid
When the ship operates in waters where salinity is low, like freshwater or brackish waters, some caustic agent may be added to the loop. This is typically termed caustic assisted scrubbing or hybrid mode. The hybrid mode is much like the open loop mode, with the exception that some source of alkalinity is added to the liquid to assist scrubbing performance and ensure compliance.
Closed loop mode differs from the two other modes in several ways. As the name implies, the circulation loop is closed and scrubber liquid is reused. The scrubber liquid will absorb heat from the flue gas. To avoid excessive temperatures the liquid is cooled with seawater, indirectly, in a heat exchanger.
Closed loop
During closed loop operation, no liquid is discharged to sea directly. Zero liquid discharge is a requirement in certain ports. The Liquid is kept in buffer tanks. When the ship moved to a zone where discharge is allowed, the water may be discharged after some physical treatment (filtering).
To comply with the IMO Marpol 2020 regulations one will need to follow either MEPC.259(68), Scheme A or Scheme B. Most (all?) scrubber vendors follow scheme B for which the requirement is to install continuous measurements of SO2 and CO2 in off-gas and pH, PAH and turbidity for liquid discharge.
Marked leading return on investment is ensured through optimized design and engineering.
Thorough risk assessments are paramount to secure efficient project execution.
With extensive experience in engineering, installation as well as service and operations, Pure Maritime has all the experience required to deliver successful projects.
Marked leading return on investment is ensured through optimized design and engineering.
Thorough risk assessments are paramount to secure efficient project execution.
With extensive experience in engineering, installation as well as service and operations, Pure Maritime has all the experience required to deliver successful projects.
