Designing & engineering a central energy supply station

Challenge

The site of Ludwig Weinrich GmbH & Co. KG is located in the heart of Herford. Surrounded by mixed area and residential buildings, the company has been producing high-quality chocolate since 1895. The corporate concept of the Ludwig Weinrich chocolate factory is based on the three cornerstones "tradition", "claim" and "responsibility". The previous heat supply of the production was provided by a steam boiler in a separate boiler building. In the course of the energetic restructuring of the entire site and production, it had to be checked whether some production processes could be converted from steam to hot water.

The existing boiler house was to make way for a new building to expand production, so that a completely new location had to be found on the factory premises for energy generation, which was in line with the immission control approval situation and the internal processes. In addition, production should not be ready for use without heat for longer than absolutely necessary during the changeover to the supply from the new energy center.  

• Centralized energy supply with high efficiency
• Challenging environment with high request in relation to noise and air-pollution

Solution

In order to increase the efficiency of production and to save costs, a new gas-powered CHP plant was installed in a new energy centre building, which serves to supply the chocolate factory with hot water, warm water and cold water. For sound insulation reasons, the energy centre consists of a massive hall with a partial basement in order to meet the high requirements for the protection of the environment and the surrounding area. The combined heat and power plant on the ground floor delivers around 800 kW of electrical power and 930 kW of thermal power. Part of the thermal energy is used for the production of cold water in an absorption chiller with a cooling capacity of 300 kW. Three storage tanks with 48 m³ hot water, 11 m³ hot water and 48 m³ cold water volumes are used to compensate for load fluctuations. By combining the cooling transfer stations in the existing buildings with the energy centre, the existing sprinkler basin can also be used as a cold storage tank. If the stored heating and cooling quantities are not sufficient, a new peak load boiler with 1,000 kW, an existing hot water boiler and several existing compression chillers can be used.

In the basement of the energy center are the water distributors and one of the return heat utilization stations. In the return heat utilisation station, heat is transferred from the return of the hot water network (flow temperature: 105 °C, target return temperature at the CHP or boiler 70 °C, return temperature from the plant 60 to 85 °C) to the hot water network (flow temperature 50 to 60 °C) with a maximum output of 200 kW. Another return heat utilisation station was built in one of the production buildings. Here, the return heat from a mould washing system is used to heat rooms and tanks as well as for domestic hot water preparation. At this point, the return temperature in the hot water network can be reduced from over 90 °C to a maximum of 70 °C.

• Holistic energy-supply-approach with high efficiency by using a gas engine and a absorption-chilling-machine
• Creating an architectural highlight combining technical and environmental requirements
• Reducing CO₂-emission by transferring energy demand from steam to hot water
• Using heat recovery in production process for reducing waste heat and increase plant efficiency