Thanks to the installation of vacuum-tube-collectors at their facade, the Hack Gastro-Service oHG saves a lot of energy in the cleaning process. The subsidiary of the Hack AG from Kurscheid produces frozen and fresh baked goods. A very important product group are cream-cakes for which more than 4 tons of cream is processed daily. Currently 100 employees work at the Hack Gastro-Service oHG, 75 of which work directly in the production. Currently 100 employees work at the Hack Gastro-Service oHG, 75 of which work directly in the production.
Due to the products, predominantly cream and sugar residues remain on the production line and the tools; those residues have to be completely removed after each production day due to reasons of hygiene. Due to the products, predominantly cream and sugar residues remain on the production line and the tools; those residues have to be completely removed after each production day due to reasons of hygiene. For that final cleaning, the complete production equipment has to be lathered with a cleaning solution and thoroughly rinsed with more than 10 m³ of hot water, to remove fats, sugar and further contaminants. The heat demand for this cleaning process is around 200 MWh/a.
Before the solar process heat plant was taken into operation in April 2014, the heating of the required fresh water was done by heat recovery and a gas boiler. Now at sunny summer days the solar system reduces the gas demand for the cleaning process by approx. two thirds. Around 100 m² vacuum-pipe-collectors (55.8 m²ap), which were installed on the south facade (as the picture shows), provide the heat. Over the course of one year, the solar process heat plant achieves solar fraction of about 30 % regarding the cleaning process.
The installation of the 20 vacuum-pipe-collectors at the facade would not have been necessary by static reasons; the company Hack still chose this type of installation to increase the visibility and therefore the attention for the use of solar process heat. They even accepted a longer installation time and therefore higher costs for that reason. They even accepted a longer installation time and therefore higher costs for that reason.
Despite the relatively steep inclination of the collectors, the solar yield has noticeably exceeded the estimated yield and is now at about 600 kWh/m²bruttoa. The depicted hydraulic shows the general scheme of the solar process heat plant for the hot water supply for cleaning.
Before the solar plant was built, the cleaning water supply was done by a cascade of three tanks of 6.5 m³ in total (on the right-hand side of the image). The water is pre heated in the first two buffer tanks by heat recovery from the cold supply. The third tank (on the far right) is heated up to the required temperature by a conventional auxiliary heater. T he water for the cleaning process is taken from that third tank.
Two additional tanks of 1.5 m³ each were installed for the solar plant. Those tanks feed the two bigger buffers of the storage cascade via an external heat exchanger. At sufficient radiation they are heated up to 95 °C. After the actual production of the baked goods, the hot water, which can be additionally heated by the gas boiler, is taken from the tanks and used at 65 °C to rinse the production equipment, which has been lathered before.
Each year the installed solar plant provides around 60 MWh of heat energy for the cleaning process. Due to the reduction of natural gas consumption by more than 6,000 m³, the solar plant reduces the yearly CO2-emmissions by around 14 tons.
50 % of the plant’s overall costs of circa 93,000 € were covered by the market incentive programme, resulting in an amortisation period of noticeably less than ten years.