ENERGY OPTIMIZATION OF POWDER COATING LINE WITH LARGE SAVINGS

At Moldow we have together with  Scanenergi A/S and Bramidan A/S worked on energy optimization of their powder coating line. This  automated powder coating line we designed and installed in the beginning of 2020 for powder coating of their vertical balers.

Due to the high electricity and gas prices, Bramidan initiated a collaboration with energy consultant Kasper Holmgaard from Scanenergi in 2022 to investigate at the efficiency of the installed line and the possibilities for energy optimizations.

– The line was from the beginning designed to be efficient and energy-conserving as this was a crucial factor for Bramidan. Among other things, the curing oven includes heat recovery and transition zones before and after the oven to reduce energy losses, and the pre-treatment tunnel is our usual, efficient design, explains Technical Manager at Moldow, Lars Holm.

There are often several energy-saving solutions to consider if you wish to optimize your painting line and achieve large savings and reduce CO₂ emission – and this applies to both new and existing lines.

Already Highly Efficient Line

Kasper Holmgaard made the first measurements in 2022 to determine the energy use of the line.

– With the measurements from the installed energy meter, I could conclude that the line was already very efficient. The energy consumption of the pretreatment is very low – approx. 50-65 kW depending on load, excluding the heating hour. The heat exchanger on the curing oven reuses the approx. 190°C hot exhaust air to preheat the replacement air. The efficiency of the heat exchanger was 48-55% measured over a month and after 2.5 years of operation without cleaning or any maintenance, Kasper Holmgaard from Scanenergi says.

Kasper Holmgaard identified several energy efficiency opportunities, which he presented to Bramidan together with an overview of savings, government grants and payback time.

– In January 2023, we installed heat recovery so we could reuse the heat from the extracted air from the powder booth and the drying oven to heat the supply air to the hall. In addition, we also made some changes to the pre-treatment to reduce standby consumption and thus make that part even more efficient than already, says Lars Holm from Moldow.

– We also reduced the electricity and heat consumption for the powder booth quite significantly. Before, the booth was constantly ventilated in accordance with the requirements with people present. As this is rarely the case, we have installed a door switch and created two operation modes. In addition, through tests we have concluded that the ventilation of the powder booth is very efficient, thanks to the special inlet ceiling among other things. Therefore, we have been able to reduce the airflow and still maintain the quality of the coating. With these changes, we have been able to reduce the amount of extracted air by 40% for 90% of the operation time, Lars Holm explains.

Energy Savings of approx. 600,000 kWh/year

These are investments that quickly pay off.

– With these changes, Bramidan has achieved energy savings of 591,225 kWh per year, which corresponds to an annual saving of DKK 430,700 (57,730 EUR) based on an average spot price of DKK 0.7 (0.09 EUR)/kWh for electricity and DKK 4.3 (0.58 EUR)/m³ for gas and one-shift, explains Kasper Holmgaard, and continues:

– Bramidan had the opportunity to receive a government grant for the project, and with the grant, the payback time of the investment is 1.1 years, while the payback period without the grant would have been a little less than 1.7 years.