Preventing corrosion with membrane degassing (TiA)

Plant operators face a number of challenges for the provision of treated water for production, operations, site expansion, and commissioning of new schemes.

Mark Dyson
Veolia Mobile Water Services

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Article Summary

These challenges include maintaining and refurbishing plants to prevent age-related mechanisms such as erosion, fatigue, and corrosion.

Preventing corrosion of critical parts of any system is vital to efficient plant operations and longevity. In the past, typical degassing technology involved on-site chemical usage including the use of heat and hydrazine. However, new technology developments mean it is now possible to achieve the same results, chemical-free and in a mobile water degassing treatment format.

Chemical-free water degasification
Membrane degassers can achieve reductions from oxygen saturation levels in feed water to levels lower than 10 ppb without the use of chemicals.  A membrane system is installed in a container and can be used to reduce the oxygen and carbon dioxide content from process water in a flexible, fast and efficient way.

Preventative maintenance and refurbishment of permanent water treatment or degassing plants need to be carried out without interrupting the production schedule. A temporary water treatment system may be deployed to either provide the full replacement or partial part of the various processes you may have during this interim need.

Long-term interim solution before planned shutdown
A petrochemical site in Spain experienced a thermal degasser breakdown but could not replace or repair the equipment until the next full plant shutdown.
Therefore the company requested a rental mobile membrane degasser to bridge a period of five years to treat up to 90 m3/h of demineralised water. The conductivity required was O2 <10 ppb. Mobile Water Services provided a Remox-50S skid based unit plus an additional booster pump that fitted perfectly in the tight area of the plant. The Remox skid lowers oxygen levels from 15 ppm at the inlet to <10 ppb at a flow rate of 80-90 m3/h.

Flexible and fast delivery after the breakdown of the on-site thermal degasser meant that the petrochemical producer avoided production loss and also benefited from an economical rental solution to bridge the period until the next plant shutdown.

Continuous production during maintenance
Due to maintenance works on the fixed plant deaerator, a petrochemical plant in Belgium was not able to thermally remove oxygen from demineralised water. The solution was to bypass the onsite deaerator with a Remox-50C from Mobile Water Services, which reduced the oxygen through membrane degassing. This bypass made it possible for the customer to continue production. Oxygen demand was <20 ppb at 50 m³/h.

The containerised Remox-50C was able to deliver 50 m³/h of deoxygenated water to meet the required quality. A special internal recycle over the feed tank covered fluctuating quantity demands as continuous production on peak flow was possible. The quality demanded was exceeded as <10 ppb O2 during the full production period. The project lasted three weeks.

This short case study originally appeared in PTQ's Technology In Action Feature - Q4 2021 Issue.

For more information: mobilewaterservices@veolia.com

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