NOVELTY - The apparatus comprises a pre-conditioning tank (1) for receiving solid and/or liquid organic substances, a loading device (15) for filling a hydrolyzer (8) with organic substrates from the pre-conditioning tank, a relaxation device (20), which has an expander tank (12) for releasing the pressure of the substrate after the treatment in the hydrolyzer and a steam separator (10) that is upstreamly arranged to the expander tank and downstreamly arranged to a pressure orifice plate, and a device for directly admitting the supplied organic substrates with hot steam separated from the separator.    USE - Apparatus for discontinuous hydrolysis of organic substrates such as energy crops and vegetable and animal refuse, where the apparatus is a part of a biogas plant (claimed).    ADVANTAGE - The apparatus is energetically optimized and compact, achieves quasi-continuous operation, increases the energy efficiency of the biogas plant with increased gas production and improved gas quality, and ensures efficient and simple discontinuous hydrolysis of the organic substrates with high throughput, high degradation rate and increased product quality without yeasts, molds and other harmful microorganisms.    DETAILED DESCRIPTION - The apparatus comprises a pre-conditioning tank (1) for receiving solid and/or liquid organic substances, a loading device (15) for filling a hydrolyzer (8) with the organic substrates from the pre-conditioning tank, a relaxation device (20), which has an expander tank (12) for releasing the pressure of the substrate after the treatment in the hydrolyzer and a steam separator (10) that is upstreamly arranged to the expander tank and downstreamly arranged to a pressure orifice plate, and a device for directly admitting the supplied organic substrates with a hot steam separated from the steam separator. The steam separator is designed as cyclone and has a steam distribution unit e.g. nozzle assembly unit, which is directly arranged in the pre-conditioning tank for the organic substrates. An expander tube originating from the steam separator is guided through the pre-conditioning tank, directly flows into the expander tank and is formed for delivering a contact waste heat to the contents of the pre-conditioning tank. The steam separator is directly arranged over the pre-conditioning tank and the expander tube guiding vertically into the pre-conditioning tank has a volume of withdrawal load from the hydrolyzer. An agitator is arranged in the pre-conditioning tank. The loading device has a pressure container, which has a valve-controlled connection line that is arranged next to a valve-controlled loading line for the hydrolyzer to produce a temperature and pressure balance with the hydrolyzer. The pressure container is equipped with a sieve unit, which serves for dewatering the substrates supplied from the pre-conditioning tank. A recirculation line originating from the sieve unit and guiding for pre-conditioning tank is provided for the liquid substrate pressed into the sieve unit. The recirculation line is guided over a heat exchanger integrated in the expander tank. The loading device has a conveying screw for conveying a superficial floating case, which consists of solid, fibrous components of plant refuse. The conveying screw has a further sieve unit, which serves for pre-dewatering the conveyed substrates. A device is provided for supplying hot exhaust gases of a cogeneration unit of a biogas plant for heating the hydrolyzer. An INDEPENDENT CLAIM is included for a method for discontinuous hydrolysis of organic substrates such as energy crops and vegetable and animal refuse.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of an apparatus for discontinuous hydrolysis of organic substrates.    Pre-conditioning tank (1)    Hydrolyzer (8)    Steam separator (10)    Expander tank (12)    Loading device (15)    Relaxation device. (20)