Patent EP-2404887-A1 (EP)
Inventor: HARTMANN STEFFEN
IPC: C05C3/00
Filed: 2011-06-08
Abstract: The method comprises initially introducing an ammonium salt solution (5) in an evaporator vessel I (4) containing water, where the ammonium salt solution is subjected with a defined temperature from a heat exchanger I (2) without temperature control over an inlet (6), and providing a low pressure, which is required for boiling and concentrating the ammonium salt solution in the evaporator vessel and for concentrating a saturated steam emerging from the evaporator vessel and introducing into the heat exchanger II, by a vacuum generation stage I. The method for producing fertilizer from fermentation residue occurring in biogas plant in a two-stage evaporator system, comprises initially introducing an ammonium salt solution (5) in an evaporator vessel I (4) containing water, where the ammonium salt solution is subjected with a defined temperature from a heat exchanger I (2) without temperature control over an inlet (6), providing a low pressure, which is required for boiling and concentrating the ammonium salt solution in the evaporator vessel and for concentrating a saturated steam emerging from the evaporator vessel and introducing into the heat exchanger II, by a vacuum generation stage I, collecting the condensate obtained from the heat exchanger II in a condensate container assigned to the first evaporator stage, removing the condensate of the condensate container from the process, thickening the condensate in a second evaporator stage II, in which fermentation residual liquid increases at a lower temperature level and at higher vacuum as in the evaporator vessel up to the crystallization at a vessel bottom of the evaporator vessel II, pressing the fermentation residual liquid, which is held continuously at working level, in a circuit over the heat exchanger II, again spraying the fermentation residual liquid in the evaporator vessel II by a nozzle (10), treading steam occurring in later in contact with a tube spiral heat exchanger integrated in the evaporator vessel II, and guiding the occurred condensate collected in the condensate container by stage II into a buffer container for pressing a buffer solution mixed with an inorganic acid, where the buffer center is actively connected with the evaporator vessel of the first evaporator stage over the inlet. For maintaining pH-value of constantly less than 6 in the first evaporator stage, the inorganic acid such as sulfuric acid is used for processing the buffer solution, which is deposited in the buffer container. The concentrated ammonium salt solution (up to 40%) taken up to the evaporator vessel and the fermentation residue discharged from the evaporator vessel as spreadable solid manure are introduced for itself individually or jointly on useful areas of the agricultural land. The heat exchanger I is flowed through with cooling water from a cogeneration plant, where the input temperature of the heat exchanger is 90[deg] C and the output temperature of the heat exchanger is 70[deg] C. The operational vacuum temperature-dependently adjustable in the first evaporator stage and the second evaporator stage is regulated to 200-500 mbar. The waste heat obtained from a re-cooler is used for further drying the concentrate from the evaporator vessel II. An independent claim is included for a device for realization of a method for producing fertilizer from fermentation residue.