Introduction

With over seven years of operational service, the Golar Eskimo’s engineering team was continuously open to further improving the vessel’s efficiency, reducing maintenance and impacting positively on the bottom line. As technology provider, Evoqua was able to identify how these improvements could be met and performance expectations exceeded by turning attention to the floating storage and regasification unit’s (FSRU) marine growth prevention system.

Challenge

The Golar Eskimo’s marine growth prevention system is essential to treat the vessel’s cooling water to protect and prolong the life of its equipment. If left untreated, the presence of mussels and barnacles, combined with bacteria and algae, significantly restricts the flow of the seawater used to cool heat exchanger surfaces. Furthermore, it accelerates corrosion of assets by restricting oxygen diffusion. Historically, chlorination was used by vessels to treat this fouled seawater but there are significant safety risks associated with the bulk storing of chemicals, as well as increased maintenance and cost requirements.

To provide a safer, more effective alternative, Evoqua designed its Chloropac® systems, a patented* design utilising concentric tube electrolysis cells. The system works by taking a small amount of water (28 or 57 GPM) from a sea water line which remains constantly under pressure. The water passes – at high velocity – through the electrolytic cells where part of the naturally occurring salt in seawater is converted to sodium hypochlorite. This dilute, safe solution of sodium hypochlorite is directly injected into the water circulation, preventing the growth of common marine species. This immediately frees vessels, such as Golar Eskimo, from the cost and risk of purchasing, handling and storing potentially dangerous chemicals.

The Golar Eskimo had in place two original Chloropac MKII systems to treat the ship’s cooling water. Whilst these were performing to treat the water and prevent marine growth, Evoqua identified how the system could be upgraded to improve efficiency and reduce operational costs. However, there was a further consideration. To keep the ship operational, installation of any new technology had to ensure zero downtime for the vessel. This meant any potential solution had to guarantee this, as well as minimal installation time and meet tight cost parameters, both in terms of capital expenditure and lifetime costs, as well as reduce ongoing maintenance.

Solution

Having worked in partnership with the Golar Eskimo’s engineers for over seven years, Evoqua had a deep understanding of the vessel’s exact requirements and operational needs. The team therefore knew the Chloropac MKIV systems would deliver significant benefits.

The MKIV systems are the latest version of Evoqua’s industry leading Chloropac® systems, based on more than 40 years of proven application. The technology is based around a single piece electrolysing cell, whereas the MKII was a two-piece design. This is just one new feature that enables the systems to be smaller, more efficient and easier to maintain. This key difference between the two systems offers significant reductions in maintenance and lifetime ownership costs.

Furthermore, the performance of the MKIV system is enhanced. The cell has a higher surface area to increase output per cell by up to six times. It also offers users operational flexibility with temperature and salinity variations 5-32oC and 25 – 45 PSU (14-25g/l.). The higher seawater velocity through the cell offers better self-cleaning, which reduces maintenance.

Key for the Golar Eskimo, the modular design of the MKIV system means it can be simply fitted in to an existing engine room space. This meant one of the existing MK2 lines could be moth balled and MKIV installed in a matter of days by the ship’s engineers, with minimal downtime for the system and zero downtime for the vessel.

Results

The Golar Eskimo’s upgrade to the MKIV Chloropac system has delivered against objectives. The Evoqua Chloropac systems are designed to last the lifetime of the vessel, with cell upgrades available as and when vessels require them. The system will continue to offer benefits for the Golar Eskimo, including cost savings of up to 300% against copper anode – an alternative technology – over a 20 year lifespan.