Digestate dryers
Drying plants for digestate
We are the Italian company that has designed and produced the largest number of digestate dryers, i.e. the separated solid and liquid fraction. The dehydration process operates by recovering the heat from hot cooling water or from hot fumes from cogeneration groups. We are committed to satisfying even the most specific needs of our customers and, for this reason, we have also created installations in different sectors with different types of digestate.
Drying plant for digestate from a biomethane plant
On behalf of an important company in the environmental sector, we have created a digestate dryer from a biomethane plant. The plant, fed with Forsu and supported by ‘semi dry’ technology, dries the separated liquid fraction to a suitable final humidity. In this way the product leaving the plant can be mixed with vegetable biomass before being sent for composting.
The system recovers the thermal necessary for the process from hot water derived from the cogeneration group which allows to obtain a temperature of 80 ° C. It is also designed for the application of a biogas burner which would allow the process air temperature to be increased up to 130-140 ° C and to increase production capacity.
Digestate drying plants from a biogas plant
A second digestate dryer was combined with a plant that uses corn and pig slurry as a recipe. This particular dryer has a great advantage: being “zero impact” on the environment because the digestate leaving the plant is treated with a phase separator.
The separated solid fraction and the filtered part are conveyed to the dryer while the separated liquid fraction is subjected to a particular treatment. In fact, through a membrane system, the process allows to obtain a liquid wastewater. The remaining filtered condensate is sent to the drying plant and mixed with the separated solid fraction to be dried at 90% of SS. The dried digestate can be integrated with other minerals, diced and marketed as fertilizer.
Dryer for digestate from a biogas plant from sludge for slaughter
The third digestate dryer was built for an important company in the food sector where a biogas plant is installed that uses sludge from slaughterhouses. In this case, the plant was built on several levels because the space available for insertion in the production line was very limited. To insert the system and keep the existing structure unchanged, the system was installed on the ground floor, the heat generator unit on an elevated level and the scrubber on the roof of the building connected with an existing biofilter on site.
Characteristics of the plant
The evaporative capacity of the plant is 2000 Kg / h of water, the thermal is recovered from the hot water of the cogeneration group. A biogas fueled burner is also provided to supplement the hot water temperature or to replace it during the period in which the cogenerator could be stopped for maintenance. In this case, being a food industry, the separated digestate is dried from 22% to 80% of SS and sent to trade as a fertilizer.
The drying process makes it possible to reduce the weight of the material to be disposed of by about 70%. This allows to obtain a very interesting result also from the economic point of view considering the continuous increase in disposal costs.
All drying systems for digestate are designed with suitable materials (Aisi 304) in compliance with current regulations for emissions into the atmosphere. Normally, for the saturated process air at the outlet, a wet treatment with horizontal scrubbers or with double tower and / or biofilter is foreseen. Ammonium sulphate is recovered from the scrubber with a 6% nitrogen which is fully included in fertilizers.
If there is no heat to be recovered, it is possible to use fuels such as biomethane, natural gas or LPG. In this case, thermal recovery in the saturated outgoing air can be expected to be used as preheating of the incoming ambient air. The system allows to increase the thermal efficiency of the system by about 15-20%.
All our dryers meet the requirements of the European plan for Industry 4.0 and the Circular Economy. Thus it is possible to request the incentives provided for these types of plants and reduce depreciation times and costs.
