Sterilizer and sterilization method

Abstract

The invention relates to a sterilizer and a method for sterilizing a material to be sterilized. According to the invention, known steam heating methods and devices are replaced by electric heating and / or heating using thermal oil.

Description

[0001] Sterilizer and sterilization process

[0002] The invention relates to a sterilizer for thermally sterilizing material such as animal carcasses in animal carcass utilization (TKV).

[0003] Furthermore, the invention relates to a method for the thermal sterilization of material such as animal carcasses in animal carcass utilization.

[0004] Known sterilizers have a first, internal pressure vessel in which the material to be sterilized is sterilized under pressure, depending on the type and the risks associated with epidemic prevention. In animal rendering, for example, thermal sterilization is achieved by heating the material in the internal pressure vessel to at least 133°C at a process pressure of approximately 3.5 to 4 bar for 20 minutes, with the material being stirred using an agitator. The process pressure is created by the evaporation of the free water in the material to be sterilized (e.g., approximately 65% ​​for meat pulp in the TKV). The excess pressure propels the material through so-called shot lines.

[0005] The material is heated using steam heating, which is realized by at least one second outer pressure vessel arranged around the first, inner pressure vessel. Steam at a pressure of up to 8 bar is introduced into this second pressure vessel, also called a steam boiler, as a heating medium. The heating surface of known sterilizers is typically between 30 and 85 m². 2 The pressure-related complexity of the sterilizers' design leads to high production costs and extensive maintenance. The high pressures of the steam boiler require particularly high-quality materials, especially welds.

[0006] Furthermore, the generation of steam and the provision of steam at the required temperatures / pressures is associated with high energy consumption.

[0007] It is therefore an object of the invention to provide a sterilizer which at least partially overcomes the aforementioned problems.

[0008] This object is achieved according to the invention by a sterilizer according to patent claim 1.

[0009] It is a further object of the invention to provide a method for sterilization which at least partially eliminates the aforementioned problems.

[0010] This object is achieved according to the invention by a method for sterilization according to patent claim 10.

[0011] The dependent claims claim advantageous aspects of the invention.

[0012] The features of a sterilizer and a method for sterilization disclosed below are part of the invention in all executable combinations.

[0013] In various embodiments of the invention, the sterilizer or the sterilization method is designed for use in animal carcass utilization (TKV), biomass technology, on ships and / or for the sterilization of sewage sludge or sewage treatment substances.

[0014] A sterilizer according to the invention is designed for the thermal sterilization of a material and has at least one pressure vessel, at least one agitator and at least one heating device.

[0015] The pressure vessel has at least one closable opening for filling and / or removing the material to be sterilized or the sterilized material. Preferably, the pressure vessel separately has at least one filling opening for filling the material to be sterilized and at least one removal opening for removing the sterilized material. In embodiments of the invention, the pressure vessel is essentially designed as a hollow cylindrical body.

[0016] The heating device is designed at least in part as a heating jacket which at least partially encloses the pressure vessel so that it can be heated from the outside.

[0017] Heating elements are arranged in the heating jacket and are designed to generate and / or transfer thermal energy to the pressure vessel.

[0018] In advantageous embodiments of the invention, the heating jacket is divided into several heating modules in the longitudinal direction of the pressure vessel, each of which has several heating elements. In preferred embodiments of the invention, the individual heating modules, for example, fifteen different ones, can be individually controlled by the heating device, so that different heating outputs can be set in the heating modules.

[0019] The division of the heating jacket into heating modules enables, in particular, improved handling of the heating jacket during assembly / disassembly and / or maintenance.

[0020] In embodiments of the invention, the heating modules are arranged in a sleeve-like manner around the pressure vessel and lie against its surface.

[0021] In embodiments of the invention, the heating modules are divided into several, for example, eight, heating segments in the circumferential direction of the pressure vessel, each of which preferably has at least one heating element. Dividing the heating jacket or the heating modules into heating segments enables, in particular, an improved, closer arrangement of the heating segments or the respective heating elements on the curved surface of the pressure vessel and thus improved heat transfer.

[0022] Preferably, the individual heating segments are connected to each other via flexible connecting areas to enable improved contact with the surface of the pressure vessel.

[0023] Dividing the heating jacket into heating modules and / or heating segments enables precise control of the temperature profile in the product to be sterilized. This enables optimized raw material control. In embodiments of the invention, the individual heating modules and / or heating segments can be the same size or have different sizes, for example, to accommodate the sterilizer elements located on the outside of the pressure vessel.

[0024] In embodiments of the invention, the heating jacket is divided into several heating zones, for example in the circumferential direction and / or longitudinal direction of the pressure vessel.

[0025] The individual heating zones comprise several heating elements, which can be arranged on different heating segments and / or different heating modules.

[0026] In preferred embodiments of the invention, the individual, for example four different, heating zones can be individually controlled by the heating device, so that different heating outputs can be set in the heating zones.

[0027] For example, the heating jacket has a total of 120 heating elements or heating segments, with 15 heating elements or heating segments each being controllable via a common control unit and two control units each being combined to form a heating zone control.

[0028] Spatially, the heating zones in an embodiment with 4 heating zones can, for example, be arranged in such a way that the heating jacket is divided into two preferably approximately equal parts both in the longitudinal direction of the pressure vessel and in the circumferential direction.

[0029] Combining heating elements and / or heating segments into heating zones simplifies control, as this can be done jointly within a heating zone.

[0030] In embodiments of the invention, the heating jacket has a heating output of approximately 1000 kW.

[0031] The heating device is preferably free of water vapor.

[0032] According to the invention, the sterilizer can thus be implemented without the second external pressure vessel, also called a steam boiler. In embodiments of the invention, the heating device additionally comprises at least one agitator heater, with which the material to be sterilized can be heated via the agitator within the pressure vessel.

[0033] In embodiments of the invention, the heating device is designed to heat the material to be sterilized in the pressure vessel to at least 133°C.

[0034] In a first embodiment of the invention, the heating device is designed as a purely electrical heater.

[0035] In embodiments of the invention, the heating jacket of the electric heating device has at least one heating module designed as a heating sleeve, which is arranged in a ring around the pressure vessel.

[0036] Preferably, the heating jacket or the heating module has electrical heating elements, for example heating resistors, attached to the pressure vessel.

[0037] Most preferably, the heating jacket or heating module has an external insulating layer for thermal insulation. This minimizes heat losses from the heating device.

[0038] In a second embodiment of the invention, the heating device is designed as a thermal oil heater.

[0039] The thermal oil heater has a heater for heating the thermal oil, a thermal oil pump and a thermal oil line that forms a heat exchanger for heating the pressure vessel.

[0040] Preferably, the thermal oil heater has at least one expansion tank and / or at least one collecting vessel to compensate for the thermal expansion of the thermal oil during heating.

[0041] The heat exchanger can be designed, for example, as coiled pipes arranged around the outside of the pressure vessel, as a spiral pipe (half coil), as a thermal plate, or as a double jacket of the pressure vessel. The heat exchanger is preferably thermally insulated from the outside by means of an insulating layer.

[0042] To improve heat transfer between the thermal oil line and the pressure vessel, in embodiments of the invention, heat conducting material is arranged between the thermal oil line and the pressure vessel.

[0043] The thermal oil heater has thermal oil with the following properties individually or in any combination:

[0044] Low viscosity value for low operating pressure (pressure < 0.5 bar). Due to the higher fluidity of the thermal oil, the system can be operated in the specified pressure range < 0.5 bar, so it does not fall under the Pressure Equipment Directive. For example, a low viscosity thermal oil value of 5.8 mm 2 / s at 100°C.

[0045] H1 approval according to NSF International certification for lubricants

[0046] High temperature approval for the fastest possible heat-up times. A high temperature approval, for example, means a value of at least 100 to 325°C, preferably at least 200°C.

[0047] The specific heat capacity of thermal oil at a planned oil temperature of 200°C (200°C TOL temperature) is approximately 2.75 kJ / (kg K). In comparison, water vapor has a heat capacity of only 1.8 kJ / (kg K) at the maximum temperature of 180°C (at 9 bar pressure). This means that 0.95 kJ / (kg K) more energy can be stored in thermal oil, thus improving the heating efficiency compared to water vapor.

[0048] The thermal conductivity of thermal oil is 0.128 W / (m K) (200°C TOL temperature). In comparison, water vapor at 180°C has a thermal conductivity of only 0.0361 W / (m K).

[0049] Non-outgassing

[0050] Above-average heat transfer coefficient

[0051] In embodiments of the invention, the thermal oil heater comprises the thermal oil FRAGOLTHERM® FG-35 from FRAGOL AG.

[0052] In preferred embodiments of the invention, the thermal oil heater comprises an electric heater for heating the thermal oil.

[0053] Preferably, this is designed as an electric resistance heater. Most preferably, the heater for heating the thermal oil is arranged directly on the sterilizer's pressure vessel, eliminating the need for long pipes to transport the heated thermal oil to the sterilizer or pressure vessel. In addition to the obvious advantages in terms of efficiency, this arrangement saves space, especially compared to the steam heaters currently in use.

[0054] In embodiments of the invention, the heater for heating the thermal oil comprises a tube bundle exchanger.

[0055] In embodiments of the invention, at least one electric heater and at least one thermal oil heater are combined in the heating device. For example, the heating jacket is designed as a purely electric heater and the agitator heater as a thermal oil heater, or vice versa.

[0056] The sterilization process according to the invention comprises at least the following process steps:

[0057] Filling a material to be sterilized into the pressure vessel of a sterilizer, heating the material to be sterilized to at least a temperature T1 for a time of at least X1 minutes at a process pressure of at least P1 using an electric heater and / or a thermal oil heater.

[0058] In embodiments of the process, the temperature T1 is between 80°C and 140°C, the time X1 is between 40 and 130 minutes and the process pressure P1 is 3 to 5 bar.

[0059] In specific embodiments of the process, the temperature T1 is about 133°C, the time XI is about 20 minutes and the process pressure P1 is about 3 bar.

[0060] In preferred embodiments of the method, a thermal oil heater with a thermal oil having the following properties is used individually or in any combination:

[0061] Low viscosity value for low operating pressure (pressure < 0.5 bar) H1 approval according to NSF International certification for lubricants High temperature approval for the fastest possible heat-up times

[0062] Specific heat capacity: 2.75 kJ / (kg K) (200°C TOL temperature) Thermal conductivity: 0.128 W / (m K) (200°C TOL temperature) Non-outgassing

[0063] Above-average heat transfer coefficient In embodiments of the invention, the thermal oil of the thermal oil heater is heated to 150°C to 240°C, preferably at least 200°C.

[0064] In embodiments of the invention, the thermal oil of the thermal oil heater is heated to 150°C to 250°C, preferably at least 200°C.

[0065] In embodiments of the invention, a thermal oil heater with the thermal oil FRAGOLTHERM® FG-35 from FRAGOL AG is used.

[0066] In a preferred embodiment of the sterilization method according to the invention, a sterilizer according to the invention is used.

[0067] The inventive implementation of the sterilizers enables significant savings in terms of costs and energy consumption, both in production and operation. These include savings in testing costs, energy costs, and savings due to the elimination of the steam boiler (external pressure vessel) including all fittings in and on the sterilizer, condensate separators, etc.

[0068] An exemplary embodiment is described below.

[0069] On a sterilizer according to the invention, a heating power of approximately 1000 kW is provided by the heating jacket, wherein the heating jacket is divided into four heating zones, each with 30 heating segments.

[0070] One advantage of the high heating power provided is that the higher temperature achievable in the heating device allows for a steeper temperature curve. The system is typically allowed to reach a maximum of 260 °C, which is limited by the greasing of the agitator bearings. The heating elements are preferably designed for temperatures up to 700 °C, but the maximum operating temperature is preferably only 350 °C. This temperature difference of 350 °C can significantly increase the durability of the heating elements, since the system typically operates at low load.

[0071] To support and increase heating performance, a tube-bundle heat exchanger is mounted on the side of the sterilizer's pressure vessel. The system is designed to be installed close to the sterilizer's pressure vessel to ensure a compact design, facilitating installation into existing building structures and enabling the replacement of existing systems without requiring major modifications.

[0072] The tube bundle exchanger, for example, has a capacity of 250 kW, which allows it to provide approximately 1,500 liters of thermal oil (such as FRAGOLTHERM® FG-35 or a similar product) as the heating medium. The supply and discharge lines are located at the top of the pressure vessel.

[0073] The use of a shell-and-tube heat exchanger makes the heating system flexible for future expansion of heating capacity. The heating system for the thermal oil is designed for a maximum temperature of 250°C, as the thermal oil begins to crystallize at approximately 260°C. The necessary circulation is ensured by a thermal oil pump in the system.

[0074] The sterilizer's pressure vessel is preferably made of stainless steel, has a length of approximately 7,000 mm and an inner diameter of approximately 2,140 mm, and processes approximately 14,785 kg of material per batch.

[0075] The energy required to heat a filled sterilizer (one batch) is approximately 5,845,180 kJ, which corresponds to 1,624 kWh.

[0076] The total time for a batch with steam heating is approximately 141.28 minutes, including filling and emptying time (shot). The pure process time with steam is 111.3 minutes, while with electric heating it is only approximately 97.4 minutes at a heating capacity of 1,000 kW.

[0077] When comparing a steam heater with an electric heater according to the invention, an increase in production and cost savings can be achieved due to the higher efficiency and faster heating effect of the electric heater through lower energy consumption and shorter process times.

[0078] The following figures illustrate exemplary embodiments of the invention. They show:

[0079] Figure 1 : a perspective view of a sterilizer according to the invention,

[0080] Figure 2: a section of a longitudinal section through a sterilizer, Figure 3: a perspective view of a sterilizer according to the invention with a thermal oil heater, wherein the heat exchanger is designed as a pipe coil, and

[0081] Figure 4: A schematic representation of a sterilizer according to the invention with a combined electric heater and thermal oil heater.

[0082] Figure 1 shows a perspective view of a sterilizer (1) according to the invention in a schematic representation. The sterilizer (1) has a pressure vessel (2) and a heating device (3). The heating device (3) is a hybrid heating device (3) with an electric heating jacket (4) and an agitator heater (5) designed as a thermal oil heater.

[0083] The pressure vessel (2) includes a filling opening (6), a non-visible discharge opening (7) located at the opposite end, a manhole (8), and a vapor dome connection (16). In embodiments of the invention, the vapor dome connection (16) can also be used as an additional filling opening.

[0084] The agitator connection (17) is located at the visible front end of the pressure vessel (2). This is where the agitator is mounted in a fully assembled sterilizer (1) according to the invention.

[0085] The heating jacket (4) is divided into fifteen heating modules (8) designed as heating sleeves, each of which has eight heating segments (10).

[0086] The electrical heating elements (11) are arranged in the area of ​​the heating segments (10). These elements are designed for the local generation and transfer of thermal energy to the pressure vessel (2). The representation of the heating elements (11) is purely schematic. Each heating segment (10) has at least one heating element (11).

[0087] The heating modules (9) designed as heating sleeves are each closed on top of the pressure vessel (2) by means of a connector (12) so that they each rest on the pressure vessel (2) in a ring-like manner.

[0088] The heating elements (11) are controlled in groups, for example, in groups of 15, using the group control units (13). Preferably, two group control units (13) are combined to form a heating zone control unit (14), so that the heating elements (11) assigned to a heating zone can be controlled jointly.

[0089] The thermal oil heater of the agitator heater (5) has a heat exchanger (15), which is preferably designed as a tube bundle exchanger.

[0090] Figure 2 shows a section of the cross-section through a sterilizer (1) according to the invention. The interior (20) of the sterilizer (1) is defined by the outer wall (21) of the pressure vessel (2). Heating modules (9) of the electric heating jacket (4) are arranged on the outside of the outer wall (21) of the pressure vessel (2).

[0091] Figure 3 shows an embodiment of a sterilizer (1) according to the invention with a heating jacket (4). The heating jacket (4) has at least one coil (19) connected to a thermal oil heater. Using the at least one coil (19), various heating modules (9) can be realized in the longitudinal direction of the pressure vessel (2). In embodiments of the invention, these modules have separate coils (19) so that they can be heated individually.

[0092] Figure 4 shows a schematic block diagram of a sterilizer (1) according to the invention according to Figure 1 with a pressure vessel (2) enclosed by a heating jacket (4), an agitator heater (5) designed as a thermal oil heater having a heat exchanger (15) which is connected to the agitator via thermal oil lines (11), namely a supply line and a return line.

[0093] The heating jacket (4) is divided into 15 heating modules (9) in the longitudinal direction of the pressure vessel (2).

[0094] The electrical heating of the heating jacket (4) is controlled by a main control unit (22).

Claims

Patent claims 1. Sterilizer (1) for the thermal sterilization of a material, the sterilizer (1) comprising at least one pressure vessel (2), at least one agitator and at least one heating device (3), wherein the pressure vessel (2) has at least one closable opening for filling and / or removing the material to be sterilized or the sterilized material, and wherein the heating device (3) is designed to heat the material to be sterilized in the pressure vessel (2) to at least 133°C, and wherein the heating device (2) has a heating jacket (4) which at least partially encloses the pressure vessel (2) so that it can be heated from the outside, characterized in that the heating device (3) is free of water vapor and is designed as an electric heater and / or a thermal oil heater.

2. Sterilizer according to claim 1, characterized in that the heating jacket (4) is divided into several heating modules (9) in the longitudinal direction of the pressure vessel (2).

3. Sterilizer according to claim 2, characterized in that the individual different heating modules (9) can be controlled individually, so that different heating outputs can be set in the heating modules (9).

4. Sterilizer according to one of claims 1 to 3, characterized in that the heating jacket (4) is divided into several heating segments (10) in the circumferential direction of the pressure vessel (2).

5. Sterilizer according to claim 4, characterized in that the heating segments (10) can be controlled individually, so that different heating powers can be set in the heating segments (10).

6. Sterilizer according to one of claims 1 to 5, characterized in that it has a plurality of heating zones which extend in the circumferential and / or longitudinal direction of the pressure vessel (2).

7. Sterilizer according to one of claims 1 to 6, characterized in that it has at least one agitator heater (5).

8. Sterilizer according to claim 7, characterized in that the heating jacket (4) is designed as a purely electrical heater and the agitator heater (5) is designed as a thermal oil heater.

9. Sterilizer according to claim 8, characterized in that the thermal oil heater comprises a heater for heating the thermal oil, which has a heat exchanger (10) designed as a tube bundle exchanger.

10. A method for sterilizing a material to be sterilized, comprising at least the following method steps: a. filling a material to be sterilized into the pressure vessel (2) of a sterilizer (1), b. heating the material to be sterilized at least to a temperature T1 in a range from 80°C to 140°C inclusive for a time of at least X1 in a range from 40 minutes to 130 minutes inclusive at a process pressure of at least P1 in a range from 3 bar to 5 bar inclusive using an electric heater and / or a thermal oil heater.

11. Method according to claim 10, characterized in that a sterilizer (1) according to one of claims 1 to 9 is used.

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