Bosch steam boiler system cleverly combined with solar heat
An increase in production capacity provided Fixkraft Futtermittel GmbH, a producer of animal feed based in the Danube port town of Enns, Austria, with the opportunity to restructure its energy supply. A system concept from plant construction company Ing. Aigner Wasser - Wärme - Umwelt GmbH in Neuhofen/Krems, Austria was introduced. It comprises a Bosch steam boiler plant combined with solar heat. With the new energy supply, Fixkraft is able to reduce its CO2 emissions by around 85 tons per year and make energy cost savings of approximately 15 per cent compared against the old system.
The UNIVERSAL UL-S steam boiler from Bosch with an output of 2,500 kg/h provides the process heat required to produce the animal feed. The saturated steam is introduced directly into the product, meaning that the amount of condensate that is returned is very low. A solar system with an installed collector area of 320 m² is used to help preheat the feed water.
The fresh water needed is taken from the company's own well, treated and then supplied to a 6,000-litre heat storage tank. The solar collectors absorb the sun's energy and pass it on to the water in the heat storage tank via a heat exchanger.
The WSM-V water service module deaerates the make-up water. It is heated to 103 °C. The gases contained in the water dissolve and leave the deaeration system with a small quantity of steam, known as exhaust vapour. The VC vapour cooler uses the thermal energy contained in the exhaust vapour and feeds it back to the water service module. Heating-up steam is saved and the energy efficiency of the system increased.
The feed water itself is heated further in the economiser, reducing the flue gas temperature of the boiler. In order to make additional use of the flue gas condensate, a condensing heat exchanger made of stainless steel is installed downstream of the economiser. The make-up water preheated by solar heat absorbs the condensation heat before it is supplied to the feed water tank via the exhaust vapour heat exchanger and deaerator dome.
The boiler equipment also includes the low-emission natural gas firing system with oxygen control. This continually measures the oxygen content in the flue gas and controls the air supply accordingly. Modern touchscreen controls with a teleservice connection enable the system to be operated reliably and based on individual requirements.
Thanks to the use of solar energy and heat recovery facilities, Fixkraft benefits from a highly efficient and environmentally-friendly steam supply. Energy use is reduced and efficiency increased.