Reducing Kotkamills’ environmental load through evaporation and chemical recycling

Partnership stories Pulp & Paper

Finnish forest industry company Kotkamills relies on Adven’s evaporation and chemical recycling in its production process. The black liquor evaporation solution implemented by Adven is estimated to be the most energy efficient in its class in the world. Kotkamills and Adven have plans to further develop the recycling process, and the mill’s carbon dioxide emissions are expected to decrease by approximately 3,500 tonnes a year.

Kotkamills manufactures paper and board products, including the company’s flagship product, plastic-free board, which is unique in the world.

In Kotkamills’ mill area, Adven implemented a new evaporation plant that has enabled a significant reduction in steam consumption and energy production emissions. The previous evaporation solution consumed high volumes of steam, much of which was produced using natural gas.

Adven invested in a new black liquor evaporation plant that employs a closed steam cycle based on mechanical vapor recompression (MVR) technology. Adven is responsible for producing the evaporation service for Kotkamills’ production. Black liquor evaporation is part of the pulp mill’s chemical recovery process.

“The mill’s energy efficiency improved significantly, as the new evaporation plant has cut steam consumption by more than half. At the same time, carbon dioxide emissions have decreased considerably. By implementing the evaporation plant through us as a service, Kotkamills can focus its resources on developing its paper and board business,” says Adven’s Sales Manager, Joni Kalapudas.

The Ministry of Economic Affairs and Employment of Finland granted a new investment support of 3.2 meur for the concept. At Kotkamills, MVR technology is being used in the evaporation process to a considerably greater extent than ever before.

Chemical recycling reduces environmental load by thousands of tones

As a continuation of the evaporation plant project, Adven is implementing a closed-cycle solution to boost chemical recovery at Kotkamills. In the project, Adven will implement a new odorous gas boiler and sulphur recovery plant for the mill.

With chemical recovery, the chemical oxygen demand of the wastewater treatment plant will fall by around 20 per cent and the carbon dioxide emissions will decline by approximately 3,500 tonnes per year.

“It is important for us to be able to make increasingly efficient use of the by-products generated in the production process. These kinds of projects are rewarding, because in addition to the cost benefits, we achieve significant positive environmental impacts,” says Kotkamills’ CFO Petri Hirvonen.

In the black liquor evaporation plant previously implemented by Adven, methanol is recovered. With the chemical recycling project, raw methanol will be combusted together with the concentrated odorous gases from the mill’s production to recover their energy content.

The steam produced during the incineration process will reduce the mill’s natural gas consumption, resulting in an estimated annual reduction of 3,500 tonnes in the mill’s CO2 emissions. The sulphur contained in the flue gases from the incineration process will also be recovered, which will reduce the mill’s need for make-up chemicals.

Thanks to the new solution, the chemical oxygen demand (COD) of Kotkamills’ wastewater plant will substantially decline, thus also reducing the environmental load. This will lower the mill’s total emissions and improve its energy efficiency.