Arrangement and method for pasteurization and subsequent solids separation of a slurry

Abstract

Arrangement (1) for pasteurizing and subsequently separating solids from a slurry containing solid and liquid components, comprising: • a heating device (2) for heating the slurry containing solid and liquid components, • a storage container (5) for the slurry upstream of the heating device (2), namely a biogas plant, • a pasteurization device (3) downstream of the heating device (2) for pasteurizing the slurry containing solid and liquid components, • a pressing device (4), preferably a screw press separator, further downstream for separating the solids from the previously pasteurized slurry, • a combined heat and power plant (7) that can be operated by burning a gas phase (6), preferably biogas, escaping from the slurry stored in the storage container (5), wherein the heating device (2) for heating the slurry is designed to utilize at least part of the waste heat from the combined heat and power plant (7).and• a gassing vessel (8) for directly heating the slurry contained therein by direct supply and / or dispersion of a waste heat stream (13), namely a hot exhaust gas stream, from the combined heat and power plant (7) into the slurry.

Description

The invention relates to an arrangement and a method for pasteurizing and subsequently depositing solid material from a slurry containing solid and liquid constituents, in particular liquid manure.DE 101 13 359 A1 relates to a method for hygienizing an organic residue by heating it, wherein the heating is effected by applying pressure to the organic residue in a compaction method for producing a granular or particulate form of the organic residue and by supplying heat.DE 10 2007 034 642 A1 relates to a method and a plant for the treatment of organically highly contaminated wastes, in particular slaughter wastes, with a biological treatment of the waste in a fermenter, with a block heating power plant converting the gas formed in the fermenter during the fermentation of the waste into electrical energy and process heat, with a treatment of the fermentation residual material remaining after the fermentation.DE 38 16 822 A1 discloses a pasteurization plant transportable in a container framework for the preparation and hygienization of pasty substrates, such as e.g. liquid manure.DE 10 2013 012 289 A1 shows a method and a device for hygienizing (pasteurizing) flowable and pumpable fermentation substrate of category 3 according to VO (EG) 1069 / 2009, which is discharged from a fermenter after biogas extraction and in a first method step is heated in a preheating container in a traversing manner to a substrate core temperature of at least 70° C. by pumping the substrate for circulation through a ring line and a heat exchanger and in that in the second method step the heated substrate is converted from the preheating container into a second container, a hygienizer and is subjected to a hygienization (pasteurization) in a circulating manner at a minimum temperature of 70° C. for a period of time of at least 60 min, wherein the thermal energy for both heat exchangers is preferably coupled out from a BHKW.CH 706 449 A2 shows a method and a device for thickening liquid solutions for reducing weight and volume by evaporating the liquid phase by means of gases to be saturated.A disadvantage of a pasteurization arrangement may be that either only the concentrate from the solids components of the treated slurry is pasteurized, whereas the solids-reduced liquid phase of the treated slurry is used unpasteurized or is discharged as waste water. Or that the solids-reduced liquid phase of the treated slurry has to be post-treated in a further water-disinfecting apparatus according to physical and / or chemical and / or biological process methods for waste water treatment, for example in a UV thin-film plant, clarifier, flocculation, etc. This results in a substantial disadvantage in an arrangement of pasteurization subsequently for solids separation by a deterioration with regard to a generally desired plant-efficient design, in that separate apparatus lines each having containers, apparatuses, piping, measurement and control technology have to be provided for each of the two separation phases. However, higher plant complexity regularly entails higher planning, investment and operating costs. This usually also results in the disadvantage of greater susceptibility to faults, especially before the aspect of starting and running-off behavior and / or input substances varying in their composition and properties.A further disadvantage in a pasteurization arrangement in which a concentrate, which has been previously pressed out in a pressing device, preferably in a pressing screw separator, is pasteurized from the solids components of the treated slurry lies in inhomogeneous heating, based on all volume elements of the concentrate. This is because, due to the more difficult heat transfer into the interior of the agglomerates (shell-core model), which are typically formed in the pressed-out concentrate from the solids components, a significantly increased residence time at pasteurization temperature is necessary in order to ensure homogeneous heating as required.It is therefore an object of the present invention to specify an arrangement which enables energy-efficient, reliable pasteurization of the slurry containing solid and liquid constituents. In the context of the invention, safe pasteurization also means that the products produced in the arrangement, namely after the pressing device, on the one hand formed as a concentrate from the solids contents of the treated slurry and, on the other hand, formed as a solids-reduced liquid phase of the treated slurry, are also pasteurized and thus safely marketable and / or further processable and / or storable and / or compostable for the environment and / or during operation. At the same time, a further object of the invention is to provide a system-efficient, namely as integral as possible, design of the pasteurization.This object is achieved by the features of the independent claims. The dependent claims are subject of advantageous embodiments of the invention.The object is thus achieved by an arrangement for pasteurization and subsequent deposition of solid from a slurry containing solid and liquid constituents.The arrangement according to the invention comprises a heating device for heating the slurry containing solid and liquid constituents, a pasteurization device subsequent to the heating device for pasteurizing the slurry containing solid and liquid constituents, a pressing device, preferably a press screw separator, further subsequent to the separation of the previously pasteurized slurry, a storage container for the slurry containing solid and liquid constituents, namely a biogas plant, particularly preferably a fermenter and / or a secondary fermenter, and a combined heat and power plant, which can be operated by combustion of a gas phase, preferably biogas, exiting the slurry stored therein in the storage container. The heating device for heating the pulp comprises, for utilizing at least a part of the waste heat of the combined heat and power plant, a gas injection container to which a waste heat stream, namely a hot exhaust gas stream, can be directly supplied from the combined heat and power plant for directly heating the pulp contained therein and / or in which the hot exhaust gas stream can be dispersed in the pulp.In this arrangement according to the invention, pasteurization of the slurry (also called slurry) yields the basic advantage of good homogenizability by mixing and thus uniform heat transfer.Prior art press screw separators typically comprise a cylindrical screen disposed in a housing. A driven worm is rotatably arranged in the cylindrical screen, wherein the external diameters of the worm spirals arranged on the worm shaft are dimensioned such that they sweep along the inner circumference of the cylindrical screen. This causes the slurry containing solid and liquid constituents to be forced out into a filter cake and, along the screw conveying direction, causes the deposited solid constituents of the treated slurry to be increasingly concentrated. On the other, outer screen side, on the other hand, the liquid phase of the treated pulp, which liquid phase is reduced in solid constituents, flows off as filtrate. Depending on the mode of operation, the construction of the screw with the helical screws and the operating pressures present at the outlet of the press screw separator, even filter cake greatly enriched in its dry substance content can be achieved, i.e. up to compactates which can be achieved. Such products can optionally also be subjected to a drying step.Alternative extrusion apparatuses comprise all filtration apparatuses known from the prior art, for example chamber filter presses and all apparatuses for mechanical solid-liquid separation.It is therefore an additional advantage of the invention to bring about an even increased energy efficiency by introducing and / or optimizing possible apparatuses for heat recovery. The heat terms are recovered from the arrangement according to the invention itself. Connected devices include machines and / or installations, in particular also thermal installations, such as, for example, combined heat and power stations operated with biogas from a biogas installation.Preferably, the gas injection container is filled independently, according to the principle of communicating tubes, with the slurry flowing from the storage container through the liquid pressure column in contact; the heating device is designed and arranged for this purpose, for example connected to the storage container via a filling line which can preferably be shut off by means of a valve and / or tap.The arrangement preferably comprises a temperature control device for controlling and / or regulating the heating device such that the slurry fed to the pasteurization device lies in a defined setpoint temperature interval. For the purposes of successful pasteurization, it is preferable to set a setpoint temperature interval with a minimum temperature of 70° C., more preferably of 80° C., even more preferably of 95° C. in the fed slurry.The temperature control device can function according to the principle of partial use of the waste heat from the combined heat and power plant based on the heat energy content. Preferably, therefore, the heating device comprises a dividing device controlled and / or regulated by the temperature control device. In this case, by means of the dividing device, preferably by means of a throttle valve, the hot exhaust gas stream from the combined heat and power plant can be divided into a portion used by the heating device and into another portion unused by the heating device.In the pasteurization device, the slurry containing solid and liquid constituents preheated in the heating device is kept at the highest possible temperature for the longest possible time, so that pasteurization of the slurry takes place. The pasteurization device is preferably designed in an insulated construction.The heating device is preferably located outside the pasteurization device, so that the heating does not take place in, but before, the pasteurization device.Preferably, the pasteurization device comprises a suction device and / or an injection device. The suction device serves for suctioning the gas phase from the respective gas space above the pulp. By means of the injection device, the recirculated gas phase and / or fresh air and / or inert gas can be injected into the slurry. The suction device and the injection device are connected via a pipeline, wherein a heating system through which flow is preferably directed in-line is preferably installed.The pasteurization apparatus preferably comprises means for regulating and / or controlling complete pasteurization, preferably for ensuring a residence time of the slurry to be pasteurized of at least one hour at a minimum temperature of the slurry of 70° C., more preferably of 80° C., even more preferably of 95° C. The residence time can result from different modes of operation of the pasteurization apparatus which comprise the following known residence time models: discontinuous (also referred to as discontinuous stirred tanks or batch operation) and / or (quasi) continuous, on the one hand flow tube (also referred to as plug flow) and / or on the other hand continuous stirred tanks.In order to allow a sufficient residence time of the solid in the pasteurization apparatus, the pasteurization apparatus is dimensioned sufficiently large. A large dimensioning of the pasteurization device optionally also serves as a buffer function when the operation of the subsequent pressing device is temporarily stopped, for example at night hours and / or at weekend.In addition and / or as an alternative to a sufficiently large dimensioning of the pasteurization device itself for the purpose of a buffer function, preferably at least one intermediate storage container with buffer function is arranged between pasteurization device and the extrusion device, preferably the preswell separator. This is advantageous in particular for the reason that preferred extrusion apparatuses are distinguished by high throughput rates and short residence times; it can accordingly occur that the extrusion apparatus is not operated over relatively long standstill times in the arrangement in comparison with the pasteurization apparatus. The intermediate storage container is preferably designed as described as advantageous for the pasteurization apparatus.Advantageously, the pasteurization apparatus comprises a mixing apparatus for mixing, in particular homogenization, the slurry to be pasteurized, preferably by continuously pumping slurry out of the pasteurization apparatus and recycling it back into the pasteurization apparatus.Preference is further given to oblique positions of the inner container base of the pasteurization apparatus, preferably with a gravity outlet toward the outlet end, and / or vertical wall fittings for separating individual chambers, each with an overflow.The invention furthermore comprises a method for pasteurization and subsequent deposition of solid from a slurry containing solid and liquid constituents, for operating an arrangement according to the invention. The advantageous configurations described within the scope of the arrangement are correspondingly advantageously also used for the method.The method provides for a deposition of solid from a slurry containing solid and liquid constituents only after its ideally complete pasteurization. This aim is supported particularly advantageously by the design of the method according to the invention by utilizing a thermal conductivity which is better in principle in a liquid phase. For this purpose, a process stage for heating the slurry containing solid and liquid constituents to the pasteurization temperature is first provided, wherein the heating can advantageously take place, namely to compensate for heat losses, to a somewhat higher excess temperature.As described above, heat recovery takes place in the form of the at least partial use of the waste heat of a combined heat and power plant operated by combustion of a gas phase, preferably biogas, exiting from the slurry stored therein in the storage container.The control and / or regulation of the method according to the invention or of the individual method stages and / or devices can comprise all methods of a measurement and regulation technique known in the process technology state of the art; in this case, in particular sensors and / or measurement sensors and / or measurement devices for temperature, fill level, volume flow, pressure, viscosity, turbidity level, particle size, pH value, electrical conductivity are used. In particular in the case of biological methods, it is also customary to subject samples taken at specific measurement sites and / or at specific process times to online and / or offline laboratory analysis.The process according to the invention or the individual process stages can be designed or operated discontinuously and / or quasi(continuously). All residence time models described above with reference to the pasteurization apparatus are also included independently for all other individual process stages.The last process stage of the process according to the invention, namely the pressing out of the previously pasteurized slurry containing solid and liquid constituents, is left by two product phases which are produced and are then respectively pasteurized: firstly a concentrate of the separated solids contents of the treated slurry, which can then optionally be subjected to a drying step; secondly a solid-reduced liquid phase of the treated slurry. Depending on the field of application of the method according to the invention and the value retention of the pulp and / or raw material feed processed in the method, only one of the product phases produced will be the target product or both. Frequent forms of utilization include, where appropriate, deposition, placement in soils and / or on agricultural soils, animal feed utilization, etc.In order to ensure safe handling and / or further use and / or transfer of the product phases produced for humans and animals, generally for the environment, standard methods of biological laboratory analysis have become established in the prior art, which characterize the degree of pasteurization by a remaining maximum microbial count concentration of the following bacterial strains, considered as markers, and make them analytically loadable comparable. These comprise in particular the following known markers in the case of a representative sample train, in particular with regard to representative samples taken during or immediately after the storage:Escherichia Coli:less than 5,000 [seed number], preferably less than 1,000 [seed number] per 1 g sample, particularly preferablyless than 1,000 [number of seeds] in 5 from 5 1 g samples to be tested and / orEnterococci:less than 5,000 [seed number], preferably less than 1,000 [seed number] per 1 g sample, particularly preferablyless than 1,000 [number of seeds] in 5 from 5 1 g samples to be tested and / orSalmonella:0 [Seed Number] per 25 g samples, particularly preferred0 [Seed Number] at 5 out of 5 25 g samples to be tested.Further details, advantages and features of the present invention are evident from the following description of an exemplary embodiment with reference to the drawing. It shows: FIG. 1 shows an arrangement according to the invention according to an exemplary embodiment.In the exemplary embodiment of FIG. 1, the arrangement 1 for pasteurization and subsequent deposition of solid from a slurry containing solid and liquid constituents comprises a heating device 2 for heating the slurry containing solid and liquid constituents. The slurry subsequently passes from the heating device 2 into a pasteurization device 3 in a form already heated to the minimum temperature necessary for adequate pasteurization.According to FIG. 1, the transfer of the slurry from the heating device 2 into the pasteurization device 3 takes place without active delivery by, for example, a pump, namely by independent filling via a filling line 10, in that the slurry flows in simply on account of the liquid pressure column present from an upstream storage container 5.According to FIG. 1, the arrangement 1 comprises, subsequent to the pasteurizing device 3, a pressing device 4 for pressing out the previously pasteurized pulp, namely a pressing screw separator. The operation of the illustrated press screw separator is based on a construction having a cylindrical screen arranged in the housing and a rotationally driven screw arranged in the screen. During the rotary operation of the screw, the slurry is increasingly pressed out along its conveying direction in that its liquid constituents pass radially outwards through the screen and flow off as a solids-reduced liquid phase of the treated slurry 20. From the filter cake which is increasingly built up on the screen along the conveying direction, a concentrate is formed from the separated solids contents of the treated pulp 19 towards the outlet of the press screw separator, which concentrate falls out of the press screw at its outlet end, in FIG. 1 at its left end, simply following the force of gravity. The latter concentrate from the separated solids contents of the treated slurry 19 can preferably be collected directly in a collecting container.According to FIG. 1, the storage container 5 for the pulp is arranged upstream of the heating device (as shown on the right in FIG. 1 ), which container represents a biogas plant, for example a fermenter and / or a secondary fermenter.Above the liquid level of the slurry stored therein, the gas phase 6 emerging therefrom collects, here a biogas. From the space of the emerging gas phase 6, this gas phase is taken off via a connecting line for the (quasi)continuous combustion operation of the combined heat and power plant 7. In the combustion operation of the combined heat and power plant 7, some of the chemical energy bound in the gas phase 6 is in turn used for heating 23 the contents of the storage container 5; thus, the pulp that has been re-fermentation therein is often present at about 30° C. as a temperature condition promoting biological processes. Another part of the energy is used for the schematically illustrated power generation 24.In the heating device 2, a part of the waste heat stream 13 from the combustion operation of the combined heat and power plant 7 is used to heat the slurry to be pasteurised.This takes place here in a gas introduction container 8 of the heating device 2, into which the utilized portion 9 of the waste heat stream 13 from the combined heat and power plant 7 is directly fed for the direct heating of the pulp located therein in the sense of a heat recovery stage. According to FIG. 1, the utilized portion 9 of the waste heat stream 13 is a hot waste gas stream from the combined heat and power plant 7, which is divided in the dividing device 25 connected between the combined heat and power plant 7 and the gas injection container, in this case embodied as a throttle valve.Furthermore, condensation of the moisture content in the exhaust gas takes place in the gas introduction container 8, so that only the gaseous content, in particular CO 2, leaves the latter. Furthermore, preferably, means for very finely dispersing the used fraction 9 of the hot exhaust gas stream into the slurry located in the gassing container 8 in the form of very finely divided gas bubbles, for example rotating splitter disks and / or nozzles, can also be additionally arranged, which improve the heat recovery by enlarging the phase boundary surface.According to the principle of the communicating tubes (as indicated in FIG. 1 with reference to the liquid levels of the same level), an independent filling with turbidity continuously flowing through the applied liquid pressure column takes place from the storage container 5 to the gassing container 8 via the filling line 10.The slurry flows from the gassing container 8 further to the pasteurization device 3 as supplied slurry 12 in the already heated state, wherein a temperature control device 11 controls and / or regulates the heating device 2 in such a way that a setpoint temperature is maintained, for example of 80° C., in order to ensure pasteurization at at least 70° C. in the isolated pasteurization device 3. For this purpose, the installation of a temperature sensor as a means 18 for regulating and / or controlling a complete pasteurization is only shown symbolically in the pasteurization apparatus 3, according to which, for example, a dwell time of the slurry to be pasteurized of at least one hour at a temperature of at least 70° C. must be ensured. In this case, such a temperature sensor, as indicated in FIG. 1, should be arranged expediently in the outer zones of the slurry present in the pasteurization apparatus, since these are subjected to a more rapid cooling.According to FIG. 1, the temperature control device 11 for the slurry 12 supplied to the pasteurization device 3 functions according to the principle of a division of the waste heat flow 13 by the division device 25, based on the heat energy content, in this case in the form of a throttle valve, which introduces only a utilized portion 9 of the waste heat flow, namely the hot exhaust gas flow, from the combined heat and power plant 7 into the separate gas introduction container 8, but, on the other hand, discharges the remaining partial flow as an unused portion 14, for example (not shown here) emitted via an exhaust pipe or discharged via a chimney.According to FIG. 1, it is further shown that in the pasteurization apparatus 3 preferably a mixing apparatus 15 for mixing and / or homogenization of the slurry to be pasteurised is arranged; in this example, by continuously conveying slurry out of the pasteurization apparatus 3 via a pump 16 and recycling it 17 back into the pasteurization apparatus 3. To assist this, at least one stirrer (not shown here) can also be arranged in the pasteurization apparatus 3.In addition to the above written description of the invention, for the purpose of supplementary disclosure thereof, explicit reference is hereby made to the graphical representation of the invention in FIG. 1.List of reference characters1 Arrangement 2 Heating device 3 Pasteurization device 4 Pressing device 5 Storage container 6 Emerging gas phase 7 Combined heat and power plant 8 Gas introduction container 9 Used fraction of the waste heat stream 10 Filling line 11 Temperature control device 12 Supplied pulp 13 Waste heat stream 14 Unused fraction of the waste heat stream 15 Mixing device 16 Pump 17 Circulation recirculation 18 Means for regulating and / or controlling 19 Concentrate from the solids fractions of the treated pulp 20 Solids-reduced liquid phase of the treated pulp 22 Feed pulp 23 Heating of storage container 24 Power generation Combined heat and power plant 25 Dividing device

Claims

Arrangement (1) for pasteurizing and subsequent separation of solid from a slurry containing solid and liquid constituents, comprising: • a heating device (2) for heating the slurry containing solid and liquid constituents, • a storage container (5) for the slurry upstream of the heating device (2), namely a biogas plant, • a pasteurizing device (3) downstream of the heating device (2) for pasteurizing the slurry containing solid and liquid constituents, • a pressing device (4), preferably a pressing screw separator, further subsequently for separating the solid from the previously pasteurized slurry, • a combined heat and power plant (7) which can be operated by combustion of a gas phase (6), preferably biogas, exiting in the storage container (5) from the slurry stored therein, wherein the heating device (2) for heating the pulp is designed to use at least a part of the waste heat from the combined heat and power plant (7), and • a gas injection container (8) for directly heating the pulp located therein by directly supplying and / or dispersing a waste heat stream (13), namely a hot waste gas stream, from the combined heat and power plant (7) into the pulp.Arrangement according to claim 1, characterised in that the biogas plant is a fermenter and / or a secondary fermenter.Arrangement according to one of the preceding claims, characterized in that the gassing container (8) is designed and arranged for automatic filling via a filling line (10) with the slurry flowing from the storage container (5) through the applied liquid pressure column.Arrangement according to one of the preceding claims, characterized bya temperature control device (11) for controlling and / or regulating the heating device (2) in such a way that the slurry (12) fed to the pasteurization device (3) lies in a setpoint temperature interval.Arrangement according to Claim 4, characterized in that • the heating device (2) comprises a dividing device (25) controlled and / or regulated by the temperature control device (11), • it being possible by means of the dividing device (25) to divide the waste heat stream (13), namely the hot exhaust gas stream, from the combined heat and power plant (7) into a portion (9) used by the heating device (2) and into another portion (14) unused by the heating device (2).Arrangement according to one of the preceding claims, characterized in that the pasteurization apparatus (3) comprises a mixing apparatus (15) for mixing and / or homogenizing the slurry to be pasteurised, preferably wherein the mixing apparatus (15) comprises a pump (16) and a circulation return (17) which are designed for mixing and / or homogenizing the slurry to be pasteurised by continuously conveying slurry via the pump (16) out of the pasteurization apparatus (3) and returning the circulation return (17) thereof back into the pasteurization apparatus (3).Arrangement according to one of the preceding claims, characterized in that the pasteurization device (3) comprises a temperature sensor as a means (18) for regulating and / or controlling complete pasteurization, preferably for ensuring a dwell time of the slurry to be pasteurised of at least one hour at a temperature of the slurry of at least 70°C.Method for pasteurizing and subsequent separation of solid from a slurry containing solid and liquid constituents, for operating an arrangement (1) according to one of the preceding claims, comprising the following steps: • burning the gas phase (6), preferably biogas, emerging from the slurry stored therein in the storage container (5) in the combined heat and power plant (7), • directly heating the slurry containing solid and liquid constituents in the gassing container (8) of the heating device (2) using at least part of the waste heat of the combined heat and power plant (7) by directly supplying and / or dispersing the waste heat stream (13), namely the hot waste gas stream, from the combined heat and power plant (7) into the slurry, • Pasteurizing the slurry containing solid and liquid constituents directly following the heating device (2) with the pasteurizing device (3) and • Pressing out the previously pasteurized slurry containing solid and liquid constituents for at least partial separation of the liquid constituents and concentration of the solid constituents therefrom with the pressing-out device (4).

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