Method for thermal disinfection, in particular sterilization, and subsequent cooling of a centrifuge

Abstract

Method for thermal disinfection, in particular sterilization, and for subsequent cooling of a centrifuge after the centrifugal processing of a product batch, wherein the centrifuge is assigned a product inlet, a solids outlet and a cooling circuit (K) with a tank (3) for water and with a heat exchanger (4), comprising the following steps: A) steam is passed through the centrifuge (1) and the centrifuge (1) is heated, in particular to above 121°C, until disinfection, in particular sterilization, is achieved; B) sterile water in the tank (3) is heated to an initial cooling temperature; the sterile water in the tank (3) is heated in a heating circuit (W), C) when the disinfection step A) is completed and when the initial cooling temperature of step B) is reached, the water at the initial cooling temperature of step B) is circulated in the cooling circuit K through the centrifuge (1), the tank (3) and the heat exchanger (4); and D) the water circulating in the cooling circuit (K) of step C) is cooled with the heat exchanger (4) and the centrifuge (1) is cooled below a limit temperature, E) wherein one or more identical devices, including one and the same heat exchanger (4), are used in the heating circuit (W) and in the cooling circuit (K).

Description

[0001] The invention relates to a method for thermal disinfection, in particular sterilization, and subsequent cooling of a centrifuge.

[0002] Regarding the state of the art, reference is made to Hauser, Gerhard, Hygienic Apparatus and Systems, Chapters 4 and 6, Wiley-Verlag, Weinheim, 2014, ISBN 978-3527-322916, and to US 2015 / 0 018 191 A1.

[0003] Then, a method for thermal disinfection, in particular sterilization, and subsequent cooling of a system with the steps A) to D) of claim 1 - generally directed to a system - is known from the document "Britsch Anlagentechnik, see the sections "CIP / SIP systems" and "Pharma-CIP / SIP systems", Renchen, 2014, company publication (see: http: / / web.archive.org / web / 20140820074410 / http: / / britsch-anlagentechnik.de / fileadmin / template_neu / Folder_CIP_SIP.pdf and http: / / web.archive.org / web / 20140820063208 / http: / / britsch-anlagentechnik.de / fileadmin / template_neu / Folder_Pharma_CIP_SIP_Anlagen.pdf

[0004] The thermal disinfection process is used to reduce the germ count on the surfaces of the flow paths (including those of the drum) of a centrifuge having a rotating drum used for the centrifugal processing of a product.

[0005] During the centrifugal processing of certain products, i.e., in certain applications, it is necessary not only to clean the centrifuge—for example, using a CIP process—but also to disinfect it, specifically sterilize it, to kill germs. Steam sterilization is typically used for this purpose.

[0006] For cleaning, CIP cleaning (cleaning in place) can be carried out, whereby the centrifuge is cleaned and rinsed with liquids such as acids, alkalis or water.

[0007] During steam sterilization, hot steam is passed through the centrifuge under pressure. Centrifuges such as separators use steam at a temperature of at least 121 °C. Therefore, the centrifuge is fed with steam under pressure. Steam sterilization typically takes place at 127 °C and 2.5 bar.

[0008] This disinfection process is primarily suitable for applications in the biotechnology / pharmaceutical sector where thermal sterilization is required. The goal is therefore a sufficient reduction of relevant germs and microorganisms (depending on the standard or application).

[0009] For such germ reduction / inactivation, some required temperatures and times are given in Table 1 below. Heat resistance Resistance level Organism / pathogen Temperature (°C) Time (min) I Pathogenic streptococci, listeria, polioviruses 61,5 30 II most vegetative bacteria, yeasts, molds, all viruses except hepatitis B 80 30 III Hepatitis B viruses, most fungal spores 100 5-30 IV Bacillus anthracis spores 105 5 V Bacillus stearothermophilus spores 121 15 VI Prions 132 60

[0010] Since the centrifuge, especially its drum, heats up considerably during disinfection, it must be cooled below a suitable limit temperature for processing - e.g. 80°C - before a product batch can be centrifugally processed again, or cooled down to accelerate the cooling time.

[0011] According to the current state of the art, this cooling is achieved either by convection without any additional active cooling or by circulating and / or flushing the centrifuge with cool sterile air. While this method of cooling has proven effective, the cooling process is relatively long and can take up to 10 hours, depending on the machine type.

[0012] The invention therefore has the object of creating a further developed method of the type mentioned at the outset with a shortened cooling time after disinfection, in particular sterilization.

[0013] The invention solves this problem by the method of claim 1.

[0014] The cooling time, especially for the drum, is significantly reduced - by several hours - and the processing of a new product batch can be started earlier.

[0015] It is advantageous and simple for the water in the tank to be heated in a heating circuit, which uses one or more components that are also used in the cooling circuit. These components include the heat exchanger.

[0016] Advantageous embodiments of the invention can be found in the subclaims.

[0017] The invention is described in more detail below using an exemplary embodiment with reference to the drawing. It shows: Fig. 1 a separator for processing a flowable product with a system for cooling the separator after processing a product batch.

[0018] Fig.1 shows a centrifuge designed as a separator 1. Insofar as a separator is described below, the method can also be transferred to or applied to centrifuges of other designs, such as solid-bowl screw centrifuges. The separator 1 is designed here in a preferred but not mandatory configuration as a disc separator with a vertical axis of rotation and a separating disc stack arranged in a drum of the separator 1. Furthermore, the separator 1 is preferably designed for the continuous processing of a flowable product, which is clarified of solids in the separator 1 and / or separated into two liquid phases of different densities. The centrifuge - here the separator 1 - is further assigned a cooling circuit K (the elements of which are outlined in dashed lines) for cooling the separator after a high temperature (in particular the drum) has been reached.

[0019] Centrifuge 1 has a centrifuge inlet line with line sections 100, 101, into which a valve 10, in particular a switchable 1- / 2-way valve, is connected. Centrifuge 1 further has at least one liquid outlet and one solids outlet.

[0020] The liquid outlet of the centrifuge 1 is assigned a clear phase discharge 102 for discharging a flowable clear phase clarified from solids, and the solids discharge is assigned a solids discharge with here three line sections 103, 104, 105 for discharging a solid phase (solids).

[0021] A pump 2 is connected between the line sections 103, 104 of the solids discharge line to pump out the solid phase or water flowing out of the drum. Another valve 11, preferably a 1-way / 2-way valve, is connected between the other line sections 104, 105 of the solids discharge line. The valve 11 can be used to open and close the solids discharge line between the line sections 104, 105 of the solids discharge line, or to open and close a connection between the line section 104 of the solids discharge line and a line 107 leading into a tank 3.

[0022] The line 107 and the tank 3 form part of a cooling circuit K for cooling the centrifuge drum, in particular for cooling after sterilization of the centrifuge 1 and its drum at a temperature of over 100°C, in particular over 120°C after processing a product batch of a product to be processed centrifugally.

[0023] This cooling circuit K is constructed here in an exemplary, but preferably simple, design as follows.

[0024] The cooling circuit K includes tank 3 for holding sterile cooling water. Tank 3 can be filled with sterile water via a water supply line 106.

[0025] A tank drain with two line sections 108, 109 is connected to the tank 3, between which a pump 5 is connected to pump the water in the cooling circuit K.

[0026] With the pump 5, the water can be pumped out of the tank 3 and into the pipe section 109, which leads into a heat exchanger 4.

[0027] The heat exchanger 4 is permeable, on the one hand, to the water pumped out of the tank 3 and, on the other hand, to a heating and / or cooling medium that can be fed into the heat exchanger 4 via a supply line 110 and flows through it. The heating or cooling medium is preferably steam or water, with the sterile water being heated with the steam and cooled with water.

[0028] From the heat exchanger 4, the heated or cooled water flowing in through line section 109 is discharged through a line with line sections 111 and 112, between which another valve 12 is connected. Line section 112 opens into valve 10.

[0029] With the valve 10, which is preferably designed as a directional control valve, either the product inlet through the centrifuge inlet with the line sections 100, 101 can be released into the drum of the centrifuge 1 or the line section 100 is shut off so that water pumped out of the tank 3 can be guided through the line section 112, the valve 10 and the line section 101 of the centrifuge inlet into the drum of the centrifuge 1.

[0030] The sterile water used for cooling is drained from the drum of centrifuge 1 through the solids discharge and line section 103, pumped out by pump 2, and directed through the solids discharge line. By switching the additional valve 11 in the solids discharge line, the water flowing out of the centrifuge and pumped out through line 103 can be directed back into tank 3.

[0031] The line section 111 between the heat exchanger 4 and the second valve 12 has a branch into a branch line 113, which is connected to the tank 3. A valve 13 is connected into the branch line 113.

[0032] If valve 12 is closed and valve 13 is opened, water can be pumped directly from tank 3 through line sections 108 and 109 with pump 5, heat exchanger 4, and the branch line in another circuit—a heating circuit W—that does not pass through centrifuge 1. It is structurally simple to use one and the same heat exchanger 4 in the heating circuit W (the elements of which are outlined here in dot-dash lines) and the cooling circuit K. However, it is also conceivable to use two or more heat exchangers.

[0033] With this arrangement, the following procedure for thermal sterilization and subsequent active rapid cooling of the centrifuge 1 after the centrifugal processing of a product batch can be carried out: A) steam is passed through the centrifuge 1 and the centrifuge is heated, in particular to above 121°C until sterilization is achieved; B) sterile water in the tank 3 is heated to an initial cooling temperature, in particular above 85°C and below the boiling temperature of water, preferably to 90°C, wherein the water in the tank 3 is heated in a heating circuit W with the heat exchanger 4; C) when the initial cooling temperature of step B is reached and the disinfection process is completed, the water at the initial cooling temperature of step B is circulated in the cooling circuit K through the centrifuge 1, the tank 3 and the heat exchanger 4; D) the water circulating in the cooling circuit is cooled by the heat exchanger 4 and the centrifuge 1 is cooled from over 121°C to below a limit temperature of preferably 80°C.

[0034] Before step A), a production process for processing a product batch with centrifuge 1 is terminated in a preceding step A'). The product feed line is stopped. Accordingly, the product is no longer fed through valve 10 and line sections 100, 101 to centrifuge 1. It may be necessary to perform a CIP (Cleaning In Place) cleaning process with liquid flushing after the production process.

[0035] In step A), an SIP process (SIP = "Sterilization In Place") is started for the centrifuge 1. Instead of the product to be processed, hot steam at over 121°C, in particular 130°C, is passed through the valve 10, through the centrifuge 1, through the solids pump 2, the valve 11 and the inlet and outlet lines and line sections 100, 101, 102, 103, 104, 105, and the centrifuge is heated, in particular to over 121°C, until thermal sterilization is achieved. The tank 3 is filled with sterile water via the water supply line 106, preferably during step A) (if it is not already filled with water).

[0036] In step B, the water in tank 3 is heated to an initial cooling temperature, in particular above 85°C and below the boiling point of water, preferably to 90°C. The initial cooling temperature is selected such that the centrifuge 1, which is highly heated by sterilization, is not damaged when water is introduced at this initial cooling temperature. Heating the water to this temperature is preferably and simply achieved by pumping the water in tank 3 with the aid of pump 5 through the lines / line sections 108, 109, 111, 113, the heat exchanger 4, and the valve 13 in the heating circuit W, and in the process, heating it with steam—preferably in the heat exchanger 4.

[0037] Once the initial cooling temperature of step B) is reached and the SIP process from step A) is completed, valve 13 is closed and valve 12 is opened. The warm / hot water at the initial cooling temperature of step B) (here from tank 3 through line sections 108, 109, pump 5, heat exchanger 4, line 111, valve 12, line 112, valve 10, and line 101, through centrifuge 1, through pump 2, valve 11, and line sections 103, 104, and 107) is circulated back into tank 3 in the cooling circuit K.

[0038] The heat exchanger 4 is now no longer heated with steam, but cooled with water below, in particular significantly below, the initial cooling temperature (preferably with 20-30°C warm water). This cools the water circulating in the cooling circuit K from step C to a lower temperature, and thus the centrifuge 1 is cooled in a controlled and rapid manner from over 121°C below a limit temperature, for example, of 80°C. The cooling process time can thus be reduced from more than 10 hours (normal convection) to often less than 2 hours. For cooling, the water can alternatively / optionally be returned to tank 3 via the liquid drain instead of the solids drain (not shown here).

[0039] After the temperature in centrifuge 1 falls below the limit temperature - e.g. 80°C - the pumps 2 and 5 are stopped and the valves 10 and 11 are switched to their original flow direction according to the processing of the product and the centrifuge 1 and the tank 3 are emptied.

[0040] The system with centrifuge 1 is now easily sterilized and quickly cooled down to such an extent that another production process for the centrifugal processing of a product batch can be started. Reference symbol 1 centrifuge 2 pumps 3 tanks 4 heat exchangers 5 Pump 10 Valve 11 Valve 12 valve 13 Valve 100, 101 line sections 102 Clear phase derivation 103, 104, 105 line sections 107 Line 106 Sterile water supply line 108, 109 line sections 110 supply line 111 and 112 line sections 113 Branch Management K Cooling circuit W Heating circuit

Claims

[1] Method for thermal disinfection, in particular sterilization, and for subsequent cooling of a centrifuge after the centrifugal processing of a product batch, wherein the centrifuge is assigned a product inlet, a solids outlet and a cooling circuit (K) with a tank (3) for water and with a heat exchanger (4), comprising the following steps: A) steam is passed through the centrifuge (1) and the centrifuge (1) is heated, in particular to above 121°C, until disinfection, in particular sterilization, is achieved; B) sterile water in the tank (3) is heated to an initial cooling temperature; the sterile water in the tank (3) is heated in a heating circuit (W), C) when the disinfection step A) is completed and when the initial cooling temperature of step B) is reached, the water at the initial cooling temperature of step B) is circulated in the cooling circuit K through the centrifuge (1), the tank (3) and the heat exchanger (4); and D) the water circulating in the cooling circuit (K) of step C) is cooled with the heat exchanger (4) and the centrifuge (1) is cooled below a limit temperature, E) wherein one or more identical devices, including one and the same heat exchanger (4), are used in the heating circuit (W) and in the cooling circuit (K). [2] Method according to claim 1, characterized bythat before step A) in a preceding step A') a production process for processing a product batch with the centrifuge (1) is ended, wherein a product feed into the centrifuge (1) is stopped, wherein further preferably after the end of the production process before step A) a cleaning process CIP = Cleaning In Place is carried out. [3] Method according to claim 1 or 2, characterized by that in step A), instead of the product to be processed, the steam is passed through the valve (10), through the centrifuge (1), through the pump (2), the valve (11) and several line sections (100, 101, 102, 103, 104, 105) and the centrifuge (1) is heated - in particular heated to above 121°C - until thermal sterilization is achieved. [4] Method according to one of the preceding claims, characterized bythat in step B) the water in the tank (3) is heated to a temperature above 85°C and below the boiling point of water, preferably to 90°C as the initial cooling temperature. [5] Method according to one of the preceding claims, characterized by that in step C) the water is first circulated through the cooling circuit (K) at the initial cooling temperature of step B). [6] Method according to one of the preceding claims, characterized by that after falling below a limit cooling temperature, the centrifuge (1) and the tank (3) are emptied so that another product batch can be processed centrifugally.

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