Case study - Corrosion protection in a pulp and paper industry

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Courtesy of Bioconservacion SA

It is widely accepted that corrosion has an important economic impact at an industrial scale. As an example, results of a study carried out in the US showed that the total annual estimated direct cost of corrosion in the country was $276 billion, which was approximately 3.1% of the nation’s Gross Domestic Product (GDP). Thus, within the last few decades, an important effort has been made to solve this issue and corrosion management has improved significantly in terms of better solutions, including enhancement of the already existing equipment and new advanced materials for this purpose.

But what do we understand when talking about “corrosion”? Corrosion can be defined in many ways. Among different meanings, corrosion could be the deterioration of materials by chemical interaction within their environment. The term 'corrosion' is sometimes also applied to the degradation of plastics, concrete and wood, but generally refers to metals.

The main problem is the corrosion that occurs in major industrial plants, such as electrical power plants or chemical processing plants. Plant shutdowns can and do occur as a result of corrosion. This is just one of its many direct and indirect consequences. Some consequences are economic, and end up with the replacement of corroded equipment, expensive preventive maintenance, shutdown of equipment due to corrosion failure, contamination of a product or loss of efficiency, among others.

Specifically, the pulp and paper industry suffers from severe equipment corrosion attacks and, for this reason, has been trying to extend equipment life by installing special devices that reduce corrosion levels. The harsh processing environments of these facilities make corrosion control especially costly and challenging.

Project description

Bioconservacion has wide experience in this sector and within the last few years has improved the solutions suggested to avoid equipment failure due to corrosion. Within the last 4 years, Bioconservacion has supplied a blend composed of BiOn ISORB and Bi-On DOD to pulp and paper company, UPM Fray Bentos, in Uruguay. The plant is located on the banks of the Uruguay River in the province of Rio Negro and it has a production capacity of 1.3 million tons per year of bleached eucalyptus short fiber to manufacture coated and tissue paper.

At this plant a PBS (Parallel Bed Scrubber) was installed in order to prevent electrical component deterioration due to corrosion. A PBS is an equal system to a SAH but where media is packed in bulk instead of modules. This kind of device can treat horizontal streams between 425 and 54,000 m3/h. Specifically, this equipment is composed of two treatment steps, each containing specific media in order to obtain the maximum efficiency in the removal of complex air emissions.

Solution

After studying the composition of the main pollutants existing in the installation, Bioconservacion suggested packing the PBS machine with two specific media, that in combination might successfully abate most of the problematic compounds present in the stream. This specific blend is composed of Bi-On ISORB and Bi-On DOD.

Media description:

Bi-On ISORB is designed to successfully treat a wide range of gases. It is especially recommended for the control of acid gases, N-containing compounds, sulphur compounds and low molecular weight gases. Bi-On ISORB uses the combination of two processes for pollutant elimination. One consists of mere physical adsorption by trapping the molecules inside the pellet due to its large internal surface area and a second by chemical oxidation. Oxidized gases are converted into harmless products. Bi-On ISORB’s unique properties allow for successful performance in environments with up to 95% relative humidity.

This media has been designed to be used in applications such as sewage treatment plants, pulp and paper plants, airports, chemical plants, refineries or laser cutting and engraving, among others.

In turn, Bi-On DOD is an active carbon with a very high purity and large surface area which is a bi-impregnated product which neutralizes acids with a reagent that improves its neutralizing efficiency.

Bi-On DOD is widely employed in installations such as wastewater treatment plants due to its high H2S absorption capacity, as well as for the treatment of other compounds with low threshold limits such as mercaptans and some other volatile organic compounds. This product is specially designed to neutralize acidic compounds.

Performance evaluation

Within the last 4 years, our customer has been employing the same blend and the efficiency of the PBS device is avoiding corrosion. As a result, the customer has saved an important amount of money by increasing equipment life and avoiding maintenance tasks.

Bioconservacion has also offered to perform a remaining life analysis halfway through the media life so that the municipality can plan ahead for the next change-out and potentially optimize the mix of media in case the real field conditions have changed from the initial characterization.

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