September 2022 – Slovakian Energy Scouts save 6,000 € per year by updating compressed air system

KraussMaffei Technologies spol. s r.o. is a subsidiary of the German injection molding machine manufacturer KraussMaffei Group. In 2008 they opened the production plant in Sučany, north of Slovakia. Today, around 620 employees produce injection molding machines as well as machines and equipment for reactive processing.

The energy-saving “classic”, replacing the conventional lighting by efficient LED-lighting, has just been implemented in the factory, therefore Energy Scouts Zuzana Nagyová and Martin Girgoško looked for other energy efficiency options. In their Energy Scout trainings of the German-Slovakian Chamber of Commerce and Industry, they came across the topic of compressed air systems and accepted the challenge. The goal of their practical project was:

  1. to evaluate the current state of the compressed air system,
  2. analyzing the possibilities of energy savings and
  3. to propose solutions, which reduce energy consumption and environmental impact.

In production Hall 1 there is a compressor room with two stationary air-cooled screw compressors with built-in air dryers and an air tank. But due to the gradual expansion of production capacities and modernization, most machines and processes needing compressed air are nowadays located in Hall 2. Shortening the distance of compressor to consumer is important in an efficient and low maintenance distribution system. Therefore, the general relocation of the compressor station from Hall 1 to Hall 2 is now being considered but the actual realization of this change will take some time. But the two Energy Scouts wanted results fast and went on “scouting”.

In order to increase energy efficiency, they looked into the compressor station, the distribution system and finally the downstream activities where the compressed air is used. Regular inspection of the distribution system and connections are key – the life and wear of the materials can cause minor and major leaks, leading to air losses. They scheduled more regular inspections for preventive maintenance using an ultrasonic leak detector. Then they proposed to close unused branches – the warehouse and export workplaces are without compressed air process needs, but the air pipes are still routed there. Reducing the length of the pipes by closing it with a ball valve will reduce the total air demand and need for maintenance in this area.

On the consumer side they proposed a pressure reduction for air guns. The installed production machinery requires a minimum air pressure value according to technical parameters. For each piece of equipment, there is also an air gun installed, which is used to clean the manufactured piece. The gun is connected to the same branch, it has the same pressure as the machinery. But the guns do not need the same pressure as the machinery, a lower pressure is suitable.

In addition, pneumatic hand tools can be replaced by electrically driven ones. In Hall 1 only three machines require compressed air. By replacing the pneumatic hand tools with electric ones, they can shut down the entire distribution system on that workstation in Hall 1. After calculating the cost-effectiveness and potential savings, the Energy Scouts evaluated the proposed measures as follows:

With an investment of about 10,000€ the two Energy Scouts reduce the annual electricity consumption by 50 MWh and decrease costs by 6,000€. After only 1.7 years the investment pays off. The measures reduce the companies’ emissions by 8 tons of CO2 per year. The Slovakian expert jury rewarded Zuzana and Martin from KraussMaffei with the third place in the competition.

The next idea for an energy efficiency project is already at hand – the compressors produce heat, which is not utilized yet, so called waste heat. Turning heat into useful energy, for example hot water, reduces the need to purchase energy. These reductions might lead again to lower operating costs and less CO2 emissions.

Compressed Air Systems

  • Industry sector: mechanical engineering
  • Energy source: electrical energy
  • Energy saving potential: 46.66 MWh/year
  • Savings potential CO2: 7.72 tons of CO2/year
  • Potential cost reduction:  6,020 €/year
  • Investment costs: 10,000 €
  • Payback period: 1.7 years
The connection of terminal equipment to the compressor distribution system with unused connections (©Krauss Maffei)
The Energy Scouts control the pressure drop of the compressed air ...
... and check the parameter settings of the GA 45 compressor (©Krauss Maffei)
The two Energy Scouts Zuzana Nagyová and Martin Girgoškoholten won third place in the national Energy Scout competition (©Krauss Maffei)