Hygienisation process
Usually, the generation of methane gas through fermentation of biological waste products requires a heat treatment of the substances in the inlet and outlet area, in order to render germs and bacteria harmless or to avoid spreading of them. This should be handled with utmost care. There are two different methods for this heat treatment: hygienisation (at 70°C, with a resting time of 60 minutes) and pasteurization (at 133°C, with a resting time of 20 minutes). While the hygienisation process can be executed without pressure, the pasteurization process can only take place in pressure-resistant containers and is therefore more expensive. The available heat from the CHP (combined heat and power unit, max. 95°C) is used in biogas plants for this hygienisation process. Higher temperatures can be reached at the exhaust gas heat exchanger. TEWE Elektronic is one of the leading suppliers of this technology and has been dealing with the production of hygienisation technology for more than 10 years. TEWE Elektronic has developed different systems during this time, all of them meeting exactly the customers' requirements. The following items have to be considered for the design and construction of biogas plants: Quantities, operating times, substances, heat, heat recovery, odour nuisance, grain sizes as well as the requirements of the local veterinary inspection offices, which might differ from region to region. In addition to the effect of hygienic, the hygienisation process often offers also advantages with regard to the digestion of substrates and the related material decomposition.
Some photos below: A biogas plant under construction, consisting of 2 containers with a capacity of approx. 8 m³ and integrated heating technology, adapted agitation technology, pointed-cone bottom for optimal discharge. This system is fully insulated and fitted with 3 weighing bases (feet). The daily capacity is 50 to.
A container, made of stainless steel 1.4571, with integrated heat technology used for heat recovery resp. transmission to the next, cold substrate. This procedure can be very efficient when being used in plants with a good heating concept.
This is a plant design consisting of heat exchanger, hygienisation tank and heat recovery unit.
The hygienisation of small amounts, below 20 to./day, is always made in tanks. In accordance with the safety regulations, these tanks may neither be loaded nor discharged during the hygienisation process. This is prevented by technical installations. All processes are registered by a temperature recorder with regard to the time when being executed. The loading and discharging of the tank should be made very quickly in order to save time for the actual hygienisation process, since the required temperature peaks of max. 95°C are often not reached or reached for a short time only, so that the process flow is delayed.
Based on the substrates used for hygienisation, high-quality materials and components are used for the design and construction of biogas plants resulting thus in a long service-life. The control of such plants can be executed manually, automatically in an autarchic way or as integrated module within a TEWE control system for biogas plants – depending on the customer's requirements and on the price.
Please contact our sales team for further information.
