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Kotkamills to adopt closed-loop solution to boost chemical recycling

By the turn of 2020-2021, forest products company Kotkamills Group will adopt a closed-cycle solution to boost chemical recovery at its Kotkamills board and paper mill in Kotka, Finland. The chemical oxygen demand (COD) of the wastewater treatment plant (WWTP) will fall by around 20 percent and the fossil carbon dioxide (CO2) emissions will decline by approximately 3 500 tonnes. The solution will be implemented by Adven.

Kotkamills Group will adopt a closed-cycle solution to boost chemical recovery at its Kotkamills board and paper mill in Kotka, Finland. The solution will be implemented by industrial energy utility Adven.

In July 2018, Kotkamills Oy and Kotkamills Absorbex Oy, both subsidiaries of Kotkamills Group Oyj, signed a long term service contract with Adven, a supplier of tailored corporate energy and water solutions, concerning the improvement of the evaporation process in the Group’s Kotka pulp mill.

The service includes adding new black liquor evaporators and replacing obsolete parts of the existing evaporation plant of the pulp mill and will improve Kotkamills energy efficiency significantly by reducing the energy consumption in the evaporation of black liquor in the pulp production process, decrease environmental emissions and enable future production capacity increases of the pulp mill.

We are continually developing our production to become more resource-wise. Effective use of incoming raw materials is not enough, but it is also important to be able to utilise by-products from the production process more efficiently. Projects like this are rewarding because, in addition to cost benefits, there are significant positive environmental effects, said Petri Hirvonen, CFO at Kotkamills.

Methanol to energy and sulphur recovery

The service agreement will be implemented in two phases, the first phase is estimated to be operational in September 2019 and the new evaporation plant fully operational in September 2020. The service contract will be valid until 2035.

The new project is a continuation of Kotkamills’ and Adven’s previous black liquor evaporation service in which Adven is modernising and renewing Kotkamills’ evaporation plant into one of the most energy-efficient plants in the world. Now Adven will implement a new odorous gas boiler and sulphur recovery plant for the mill.

We are looking to further deepen the utilisation of Adven’s comprehensive offering of top-of-the-line energy and water solutions for the paper and board industry’s needs together with Kotkamills. Our smooth co-operation in the first project and our shared intent on increasing environmental friendliness were factors that contributed to the new agreement said Teemu Kivimäki, Sales Manager from Adven.

Double benefit for the mill

Adven’s black liquor evaporation plant allows the recovery of methanol. The new project will make it possible to burn the methanol together with the 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 fossil carbon dioxide (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.

With the new solution, the chemical oxygen demand (COD) load on the wastewater treatment plant (WWTP) at Kotkamills will be substantially lowered, thus also reducing the environmental load. The mill’s total emissions will decrease, and its energy efficiency will improve.

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