Sandvik Materials Technology has supplied its Sandvik Sanicro 28 composite tubes to a eucalyptus pulp mill in Uruguay, helping to avoid loss of production time and also reduce costs for the customer.
An important part of the pulp production process involves the use of superheater panels manufactured from composite steel tubes which are used with chloride within the pulp bleaching process. Accumulations of the chemical, in conjunction with the high temperatures involved, were having a detrimental effect on the existing carbon steel tubes. Despite the installation of a chloride removal system, the chemical is still a vital part of the overall process and it therefore cannot be completely eradicated from the production environment.
Depending on the size of recovery boiler the production loss could be as high as $0.5 – 1.5 million per day. It varies case by case, but downtime during superheater maintenance causes remarkable profit loss regardless of the type of boiler. In addition to the amount of tube replacements that were needed on a regular basis, the issues of increased production downtime, inspection and maintenance required were also major areas of concern. Andritz, one of the world’s leading fabricators of pulp and paper equipment, was brought in to undertake a replacement project of the original superheater equipment. The company carried out a full evaluation of the site and processes and carefully examined the previous carbon steel tube usage. Computer modeling was then used to seek the best solution and to recommend a better, alternative solution for the mill.
Based upon the findings of the evaluation and Andritz’s previous experience with Sandvik products, the decision was taken to select Sandvik SanicroTM28 composite tubes for the superheaters, which were installed and have since proved to be an excellent choice by reducing the amount of downtime required and enabling continuous production.
Sandvik SanicroTM28 is a high alloy, multi-purpose austenitic stainless steel, developed especially for use in highly corrosive conditions. Offering good weldability, its characteristics include high resistance to strong acids, resistance to stress corrosion cracking and pitting and crevice corrosion, as well as intergranular corrosion in certain environments.
One year after the installation of the Sandvik SanicroTM28, Andritz has reported there are no defects or corrosion damage found in the composite tubes.
Timo Peltola, Global Product Manager – Composite and Boiler Tubes for Sandvik Materials Technology, said: “This is an excellent example of how selecting quality composite tubes will provide a reliable solution for customers when compared to some of the cheaper, inferior products on the market. We’ve worked with Andritz on a number of similar projects in the past and they are familiar with our products and their ability to deliver the right result for the end customer. Loss of production time is something that any manufacturer wants and needs to avoid, and ensuring they have the best equipment made from superior materials will inevitably reduce the amount of costly downtime.”