EP1609524A1 - Method and device for conditioning of organic substrate - Google Patents

Abstract

In a process to prepare vegetable matter for fermentation, the raw materials descent vertically through a screw mixer prior to arrival at a cutting tooth mixer station. The power applied to the vertical worm mixer and/or the toothed cutting mixer is varied in accordance with the consistence of the raw material. Water is admixed as required to the incoming raw materials. Also claimed is a commensurate assembly in which there is a sheer gradient between the worm mixer and cutting tooth mixer station.

Description

The invention relates to a method for conditioning of substrate as a precursor of a Fermentation and a device for carrying out the method.

In the comminuted or ground state provided organic substrates for fermentation due to their difficult wettability and frequent subsequent swelling process in the suspension major technological problems for a safe and trouble-free handling.

The usual practice of treating various fermentable substances in a large-volume intake and dosing storage in front of the fermentation reactor to mix together fails in particular often in the increasingly used renewable resources in Form of energy plants. These are ground, crushed or crocheted delivered. In powdered form they are difficult to wet, while the frequent Hardened silage due to the preserved to a large extent undestroyed remained plant cells inclusions of gases and storage materials with densities smaller than that of water. As a result of poor wettability, Inclusions and the processing-related particle shapes, the clumping and Prevent entanglement of the substances, it comes in feeding the described Substrate in the storage container repeatedly due to malfunction floating debris. These are with the usual practice in the containers installed mixer and agitators not or only very ineffective mix.

In many cases, therefore, trying to solve the problem by direct dosing in the Bypass fermenter. It uses piston or screw feeder including lock chambers to keep the substrates dry against the static Press the pressure of the liquid level into the reactor. Except for the operational risk of this method, the problem remains more framing Swimming layers, reinforced by the flotation effect of the biogas. The Floating cover control systems commonly used in fermentation reactors are not designed to contain dominant amounts of re-floating material Constantly re-mixing, but ultimately circling it as the process disturbing substances. However, this practice is for a substrate which is still well fermentable not suitable.

The invention is based on the object, a method of the type mentioned and an apparatus for carrying out the method in such a way that a efficient and economical conditioning of also very different substrates for the subsequent fermentation is guaranteed.

This object is achieved procedurally according to the invention that the Substrate is placed a vertically downwardly promoting screw agitator and subsequently to a cutting stirrer provided below the screw agitator, is handed over.

Under Schneidrührer are all conceivable stirrers to understand, in addition to a Mixing function, also a comminution function, in particular cutting function, exhibit. With particular advantage Zahnscheibenrührer be used.

In this way, an efficient and cost-effective conditioning of the above described input substrates in a fermentation plant for use on the market available technology components in a new combination with surprising Ensures effects. It is next to the wetting and lump-free Mixing the materials in a given liquid in particular a extensive digestion of intact plant cells. This will be Flotation-promoting inclusions are released and at the same time, their immediate Availability for bacterial anaerobic metabolism of process engineering Improved fermentation efficiency.

The invention is based on the idea of using a separate stirring machine high energy density within a small volume using special To ensure stirring systems that ensure a defined wetting in the catchment area and at the same time segregation and digestion of still undestroyed plant cells enable.

In principle, known agitating systems come into consideration, which are centric generate vertical outflow, so that surface material is constantly sucked in and out is mixed again in the liquid. Known systems of this type are Worm stirrer, propeller stirrer and inclined blade stirrer. Disadvantageous for the defined However, use case is that they produce strong directional flows, however a small cutting effect on slip-poor with the flow Have solid particles. In addition, the vertical suction effect in the fast decreases running propeller and Schrägblattrührern with increasing media consistency. In In the stirrer area, tixotropic, pasty materials create a local area Media liquefaction in consequence of shear, in which by extensive stirring energy dissipation Strong unwanted warming takes place without being in the tough Outside of the medium a noteworthy further mixture takes place. The same undesirable side effect occurs when high-speed toothed disc stirrers, which in themselves in low concentrated solid suspension a good crushing effect have to be used in highly viscous suspensions.

Surprisingly, in a combination according to the invention, a vertical one appears downwardly conveying worm stirrer with one below the worm stirrer installed stirrer, in particular toothed disc stirrer, a favorable conveyor, Mixing and comminution effect in solid suspensions over a wide Concentration or digestion area and the associated Viscosity changes.

Due to the suction effect of the worm stirrer is constantly surface material sucked in and mixed again. The supply of fresh solids and as needed dilution water is preferably carried out in this defined centric effluent, so that a good wetting and suspension is guaranteed.

At the same time, this material is constantly pressed into the zone of action of the cutting stirrer, so that even with highly viscous tixotropy no stagnation zone around the Schneidrührers can arise, but a defined forced exchange of Medium is guaranteed.

The performance of the worm stirrer and / or the Schneidrührers is preferably adjusted to changing toughness of the substrate to be supplied adjusted. The Toughness of the substrate can vary widely between water-like and pasty during the Ansetzzeit fluctuate. An adjustable stirrer drive allows the preferred automatic adjustment of stirrer speed and power consumption to the changing process conditions.

The invention further relates to a device for conditioning substrate with a a fermentation reactor upstream conditioning.

On the device side, the object is achieved by the fact that the conditioner means a downwardly conveying screw agitator and a arranged below the Schneckenrührers Schneidrührers, in particular Sprocket stirrer having.

The desired comminuting effect is supported for the digestion of the organic material by an arrangement of Zahnscheibenrührers near the ground the conditioning device. This results in a large shear gradient between stirrer and container, whereby particle slippage and thus the crushing effect of Stirrer can be improved.

As a particularly suitable device has been described for the Intended use an adapted variant of from the paper industry and Bioabfallwirtschaft known Pulpers proven. For this purpose, the pulper without systems for contaminant removal and with a combined screw / Schneidrührerrührsystem equipped and with a defined feeder for the material to be mixed in the Schneckenrührerabstrom provided.

Strombrecher can in a known manner, the rotation of the entire Suppress suspension amount in the container and thus the construction of Support shear force gradients.

The process described preferably runs in batch mode for the respective generation a Dosiercharge, as thus digestion and homogenization of Batch quality are best to regulate.

However, it is also a continuous flow possible, especially if the Main attention to the interference to produce a stable suspension and less directed to the defined particle disruption.

Claims (7)

A method of conditioning substrate as a precursor of a fermentation, characterized in that the substrate is fed to a vertically downwardly conveying screw mixer and then passed to a provided below the Schneckenrührers Schneidrührerr. Process According to claim 1, characterized in that the substrate is transferred to a cutting stirrer designed as a toothed disc stirrer. A method according to claim 1 or 2, characterized in that the performance of the worm stirrer and / or the Schneidrührers is adapted to changing toughness of the substrate to be supplied adjusted. Method according to one of claims 1 to 3, characterized in that fresh substrate and / or dilution water is introduced into the flow directed downwards by the screw stirrer. Device for conditioning of substrate with a conditioning device upstream of a fermentation reactor, characterized in that the conditioning device has a downwardly conveying worm stirrer and a cutting stirrer arranged below the worm stirrer. Apparatus according to claim 5, characterized in that the cutting stirrer is designed as a toothed disc stirrer. Apparatus according to claim 5, characterized in that the cutting stirrer is arranged near the bottom of the conditioning, so that a shear gradient between Schneidrührer and bottom arises.