Breakthrough for composite tubes in waste incineration

Citation

(2001), "Breakthrough for composite tubes in waste incineration", Anti-Corrosion Methods and Materials, Vol. 48 No. 3. https://doi.org/10.1108/acmm.2001.12848cab.001

Breakthrough for composite tubes in waste incineration

Breakthrough for composite tubes in waste incineration

Keywords Sandvik Steel, Tubing, Steel

Sandvik Steel has confirmed that its composite tubes have been installed in a new boiler at the Renova municipal waste incineration plant in Gothenburg (Plate 1). Considered by Sandvik as a major breakthrough, its composite stainless and carbon tubes have been selected by Renova in preference to the carbon steel tubes normally used in waste incineration boilers.

Plate 1 Boiler installation of Sandvik composite tubes

Composite tubes consist of an inner component of carbon steel and an outer of stainless steel mechanically bonded together. They have a long history of use in black liquor recovery boilers in the pulp and paper industry where they are the normal choice for waterwalls and where demands on corrosion properties are extremely high. Yet, in waste incineration boilers the use of carbon steel predominates even at the points of highest corrosion and where, due to the processes, the potential for corrosion is even greater than in the pulp and paper industry. Improvements in waste incineration boiler design to optimise operating conditions continue to place increasing demands on tube performance.

Renova operates three waste incineration boilers at its plant in Gothenburg and composite tubes have reportedly been used to good effect on several occasions for repair and refurbishment of the existing boilers. As a result, there is said to be ongoing experience of improved corrosion resistance and of a much longer life for the parts of the boiler where composite tubes have been installed.

Sandvik Steel's composite tubes comprising, in this case, a stainless steel Sanicro 28 grade outer and a grade 4L7 carbon tube inner were, therefore, specified for a 300 square metre panel in the waterwall of a new boiler. The decision to use composite tubes was reportedly supported by the fabricator of the panel, Kvaerner Pulping of Gothenburg which brought its installation knowledge and experience to the project having installed composite tubes in more than 100 black liquor recovery boilers.

According to Sandvik the cost argument for composite tubes is that, although they are initially more expensive than carbon steel tubes, life cycle costing, with repair and downtime costs included, need to be taken into account. It can then be shown that the investment is soon recovered and composite tubes are a cost effective solution to corrosion problems.

Urban Forsberg, product manager at Sandvik Steel comments, "Construction of a completely new boiler with composite tubes will provide an excellent reference point for the waste incineration industry. The manufacturers of waste incineration boilers are not the same as those for black liquor recovery boilers. We are therefore particularly pleased with the involvement of Kvaerner Pulping which has a well documented expertise in fabrication of boilers with composite tubes".

The new Renova boiler will incinerate 15 tonnes of waste every hour. The thermal energy produced will be used for energy production and district heating.

Renova's three boilers in Gothenburg generate enough electricity to supply 60,000 households and to keep 100,000 households in heating and hot water. This production of energy replaces an equivalent oil burn of 100,000 tonnes per annum and at the same time, reduces landfill requirements by up to 95 per cent.

Details are available from: Sandvik Steel. Tel: +44 (0)1922 728800; Fax: +44 (0)1922 728827; Web site: www.steel.sandvik.com