JP2009268431A - Steam-mixing-type heat sterilizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam-mixing-type heat sterilizer can stably conducting a high-quality sterilizing treatment in accordance with a practical sterilizing treatment situation. <P>SOLUTION: The steam-mixing-type heat sterilizer includes a heating system functioning to mix steam into a to-be-heat-sterilized fluid to heat the fluid, and a sterilizing treatment system functioning to conduct a sterilizing treatment on the thus heated fluid; wherein the heating system includes at least a steam-mixing pump 4 as a powered mixer functioning to convey a fluid under pressure rise by the action of a rotor and mix steam into the fluid under conveyance, and. In addition, the heating system includes a pressure sensor 19 functioning to detect the pressure of a fluid on the entrance side of the pump 4 and a pressure control section PIC-1 functioning to control the revolution level of the rotor in response to the pressure value detected by the sensor 19 and, based on the result, control the pressure of the fluid on the pump entrance side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steam mixing type heat sterilization apparatus that heats a fluid by directly mixing the steam with the fluid.

  This type of sterilization apparatus requires a short heating time, and has little influence on the fluid and can prevent deterioration of the quality. For example, liquids that are easily burnt, such as coffee fresh and soy milk, or are easily discolored, such as green juice. It tends to be suitably used for sterilizing liquids.

For example, in Patent Document 1 below, an injection heater that heats the liquid to the sterilization temperature by blowing steam directly into the liquid to be sterilized, and a heated liquid disposed on the downstream side of the injection heater. A steam blow type direct heating sterilization apparatus provided with a holding pipe that performs sterilization of liquid by holding for a predetermined time is disclosed. A rotary pump for pumping liquid toward the injection heater is disposed on the upstream side of the injection heater, and a back pressure valve is disposed on the downstream side of the holding pipe.
JP 2004-201533 A

  In the sterilization apparatus described in Patent Document 1, it is desirable to set the pump back pressure as high as possible in consideration of the pressure loss of the liquid. In that case, the pressure of the liquid supplied to the injection heater is high. Therefore, a very high vapor pressure is required to mix the vapors. In this case, since the high-temperature vapor comes into contact with the liquid, it locally heats more than necessary beyond the required sterilization temperature, which may cause thermal damage to the liquid to be heated, and consequently deterioration of the quality of the liquid. There is not preferable.

  On the other hand, when liquids with relatively high viscosity, such as food and drink, are subject to sterilization, pressure fluctuations are likely to occur. In many cases, the state of the processing system fluctuates. Therefore, a highly accurate heat sterilization apparatus that can quickly respond to these fluctuations is required. In this regard, in the sterilization apparatus described in Patent Document 1, the flow rate of the liquid passing through the holding tube is only measured, and whether or not the sterilization process is continued is determined based on the measured value. There is no disclosure or suggestion of means for controlling according to actual processing conditions.

  In view of the above circumstances, according to the present invention, it is a technical problem to be solved by the present invention to provide a steam-mixing type heat sterilizer capable of stably performing high-quality sterilization treatment according to the actual sterilization treatment situation. To do.

  The present invention has been made to solve the above problems. That is, the steam mixing type heat sterilization apparatus according to the present invention includes a heating system that heats a fluid by mixing steam with a fluid to be heat sterilized, and a fluid that is connected to the downstream side of the heating system and heated in the heating system. In the steam mixing type heat sterilization apparatus provided with a sterilization processing system that performs sterilization processing on the heating, the heating system is a power for transferring the fluid with pressure increase by the action of the rotor and mixing the steam with the fluid in the middle of the transfer A pressure detector that detects at least the fluid pressure on the inlet side of the powered mixer, and a rotation that controls the rotational speed of the rotor according to the pressure value detected by the pressure detector And a number control unit.

  In this way, by providing a powered mixing device that enables mixing of steam with respect to a fluid transferred with increased pressure, it is possible to supply steam at a pressure lower than that in the prior art. Therefore, the steam to be supplied needs to be at a relatively low temperature, and thermal damage to the fluid can be suppressed to prevent deterioration of quality. Furthermore, by mixing the steam with the fluid in the middle of the pressure increase, the pressure can be increased even after the mixing of the steam, so that cavitation that may occur due to the temperature rise of the liquid can be avoided as much as possible. As a result, the vapor can be uniformly dissolved in the fluid, and a stable heat treatment with little variation is possible.

  Moreover, according to the said structure, it becomes possible to detect the pressure of the fluid in the inlet side of a power mixing apparatus, and to adjust the rotation speed of a power mixing apparatus according to the detected pressure value. Here, in the case of the mixing device having the above configuration (for example, a pump), the gradient of the pressure increase increases with the increase in the number of rotations of the rotor, and thus the heat sterilization should be performed by adjusting the number of rotations as described above. The fluid pressure at the inlet side of the mixing device can be appropriately set according to the type of fluid and the state of the fluid during actual sterilization treatment. From the above, the pressure balance of the fluid at the time of heating is not influenced by the pressure (back pressure) on the secondary side of the mixing device by the pressure increasing action of the powered mixing device and the interaction with the rotation speed control unit. Highly accurate and stable heat sterilization treatment can be performed while maintaining a suitable state.

  In this case, you may make it control by the rotation speed control part so that the pressure of the fluid in the inlet side of a motive power mixing apparatus may become more than the saturated vapor pressure in sterilization temperature. By controlling in this way, it is possible to set the fluid pressure on the inlet side of the mixing device to such an extent that all the vapor can be reliably dissolved in the fluid. Therefore, the heat sterilization treatment can be performed while maintaining a suitable pressure balance without excessively reducing the fluid pressure on the inlet side of the mixing apparatus and without being influenced by the back pressure setting pressure. Moreover, the damage by heating can be minimized by making the pressure difference with the mixed steam as small as possible.

  The above-mentioned heat sterilizer can be suitably used for heat sterilization treatment of various fluids. Above all, like food and drink fluids, fine and high-precision treatment is necessary to ensure quality unique to foods such as flavor and color. It is particularly suitable for the fluid to be used. The “eating and drinking fluid” here includes not only foods having fluidity to the extent that the heat sterilization is possible, but also liquids such as beverages. Also included are foods and other beverages (raw materials such as food) that are processed after heat sterilization. Moreover, what is necessary is just to have fluidity | liquidity to the extent that the said heat sterilization is possible as a whole, and the thing in which the fine granular material (including other fine solid matter) is mixed is also included. Moreover, regardless of the way of ingestion, for example, nutrients (enteral nutrients) provided for various enteral nutrition methods such as tube feeding are also included.

  In this case, in order to wash or sterilize the heating system and the sterilization processing system in the apparatus, the system may be sterilized by flowing water in place of the eating and drinking fluid and heating it. In such a case, the fluid or water for eating or drinking may be alternatively switched and connected to the powered mixing device. In this case, the switching position between the fluid and water for eating or drinking is determined by the pressure detection unit. It may be positioned upstream of the fluid pressure detection position. With this configuration, when the processing fluid is switched, the pressure of the fluid, particularly the fluid pressure on the inlet side of the powered mixing device, is reduced due to the difference in viscosity and pressure loss between the eating fluid and water. Can be suppressed. For this reason, the occurrence of cavitation associated with a rapid change (decrease) in pressure can be suppressed as much as possible, and the time and effort for sterilization can be saved. In addition, it is possible to immediately realize a stable sterilization treatment state in response to a temperature change of the fluid accompanying switching from water to a fluid for eating and drinking.

  Further, the sterilization treatment system may have at least a holding tube that holds the heated fluid, and in that case, a back pressure control unit may be disposed on the outlet side of the holding tube. If it does in this way, it will avoid that the influence of the pressure change in the secondary side (downstream side) of a back pressure control part reaches the primary side (upstream side), and stabilizes the back pressure of a motive power mixing device. be able to. Here, since the back pressure control unit is disposed on the outlet side of the holding tube, the influence of the pressure fluctuation on the secondary side of the back pressure control unit on the fluid in the holding tube is eliminated, and a more stable sterilization treatment is performed. Can be implemented. Further, since the back pressure is stabilized, the pressure fluctuation of the fluid on the inlet side of the powered mixing apparatus can be further reduced, and the inlet side pressure can be controlled with high accuracy.

  In this case, it is preferable that the back pressure control unit sets the fluid pressure on the outlet side of the powered mixing device to be higher than the fluid pressure in the mixing region with the steam. In this way, the steam mixed fluid can be maintained at a high pressure so that the steam once dissolved in the fluid does not cause cavitation, and more stable heat sterilization can be performed. In addition, the combination of the rotational speed control unit and the back pressure control unit of the powered mixing device can manage the pressure state of the fluid from the inlet side to the outlet side of the powered mixing device to the holding pipe with high accuracy and flexibility. Can do.

  The heating system may further include a steam amount control unit that controls the amount of steam supplied to the fluid based on the measured temperature value of the fluid on the outlet side of the powered mixer. In this way, for example, the heating temperature can be finely adjusted by adjusting only the supply amount of steam having a constant vapor pressure. In particular, when the pressure state of the fluid is kept constant in the above-described rotation speed control unit and back pressure control unit, the pressure of the fluid in the steam supply region in the powered mixer is stably controlled. Therefore, efficient and highly accurate heat sterilization can be performed by adjusting only the steam supply amount.

  The heating system according to the present invention controls the transfer capacity of the transfer device based on the fluid transfer device disposed upstream of the powered mixing device and the fluid flow rate measurement value on the outlet side of the transfer device. It may have a flow control part further. If it does in this way, the flow volume of the fluid in the sterilization processing system (for example, holding | maintenance pipe | tube) arrange | positioned downstream of a motive power mixing apparatus can be made constant. Therefore, the processing flow rate in the sterilization processing system can be made constant, and the sterilization time can be stabilized. In particular, when the back pressure of the powered mixing device is controlled to be constant by the back pressure control unit, it is preferable because the flow rate controllability of the fluid is also improved.

  Thus, according to the present invention, it is possible to provide a steam-mixing type heat sterilizer that can stably perform high-quality sterilization according to the actual sterilization status.

  Hereinafter, an embodiment of a steam mixing type heat sterilization apparatus according to the present invention will be described with reference to the drawings.

  The steam mixing type heat sterilization apparatus shown in FIG. 1 is used, for example, for heat sterilization of liquids such as eating and drinking fluids. The liquid tank 1 stores and discharges liquids to be heat sterilized, and the liquid tank 1 The liquid sent from the transfer pump 2 is mixed with a transfer pump 2 as a transfer device for transferring the liquid to a heat exchanger 3 and a steam mixing pump 4 as a powered mixing device to be described later. A heat exchanger 3 for preheating to bring the temperature close to the temperature of the steam to be heated, a vapor mixing pump 4 for mixing the vapor with the liquid preheated by the heat exchanger 3 and heating the liquid to the sterilization temperature, A hold pipe 5 which is disposed downstream of the mixing pump 4 and holds the liquid heated by the vapor mixing for a certain period of time, and a liquid which has been sterilized by the hold pipe 5 is cooled to a temperature equal to or lower than a predetermined temperature. A main back pressure valve 6 as a back pressure control unit disposed between the rejection unit 7, the hold pipe 5 and the main cooler 7, and a sub back pressure valve 8 disposed on the downstream side of the main cooler 7. As the main component.

  In FIG. 1, reference numeral 9 denotes a water tank that stores and discharges water used for cleaning or sterilizing a fluid system (mainly a heating system and a sterilization processing system) in the steam mixing type heat sterilization apparatus. ing. Reference numeral 10 denotes a connection between the liquid tank 1 and the inlet side of the steam mixing pump 4 and a connection between the water tank 9 and the inlet side of the steam mixing pump 4 according to the operating conditions. The 1st switching valve which switches alternatively is shown. Here, the first switching valve 10 is disposed on the upstream side of the transfer pump 2. A second switching valve 11 is disposed downstream of the main cooler 7 and the auxiliary back pressure valve 8 mainly for the purpose of collecting the water after the system sterilization treatment. And a connection between the recovery line of the sterilized liquid and a connection between the recovery line of the water after the system sterilization process can be appropriately switched.

  Also, in the figure, reference numeral 12 denotes a drainage cooling system that cools the treated liquid to flow to a recovery line (for example, a drainage line) without any trouble at the time of system sterilization treatment or when a sterilization treatment failure occurs. The reference numeral 13 denotes a drainage back pressure valve which is provided downstream of the drainage cooler 12 and keeps the back pressure of the drainage line constant. Furthermore, when the liquid temperature on the outlet side of the steam mixing pump 4 (downstream side of the discharge port 42 described later) or the liquid temperature on the outlet side of the hold pipe 5 deviates from the sterilization temperature range to be set, The 3rd switching valve for sending a processed liquid to a collection line (drainage line) is shown. In this embodiment, on the downstream side of the drain back pressure valve 13, a connection between the drain back pressure valve 13 side and the drain recovery line and a connection between the liquid sterilization treatment line and For example, when a predetermined sterilization temperature is not reached and sufficient sterilization processing is not performed, the corresponding liquid can be returned to the liquid sterilization processing line. It is configured.

  Further, in the figure, reference numerals 16, 17 and 18 denote a hot water tank for securing a predetermined amount of hot water used for the preheating heat exchanger 3, a hot water tank 16 and a heat exchanger 3, respectively. The figure shows a circulation pump for circulating hot water between them, and a heater for raising the temperature of hot water sent from the circulation pump 17 to a predetermined temperature.

  In this embodiment, a control unit for measuring or controlling the pressure, temperature, and flow rate of various fluids is provided. For example, in FIG. 1, reference numeral PIC- 1 detects the temperature of the liquid on the inlet side of the steam mixing pump 4 by a pressure sensor 19 as a pressure detection unit, and the number of rotations of the steam mixing pump 4 based on the detected value. And a pressure control unit for controlling the pressure of the liquid on the inlet side of the pump. In this case, the liquid pressure on the pump outlet side is maintained at a predetermined value by the main back pressure valve 6 disposed on the downstream side of the steam mixing pump 4, so that the pump rotational speed is substantially equal to the steam mixing pump. The pressure of the liquid on the inlet side of 4 is controlled. In this pressure control (rotation speed control), for example, a value of the inlet side pressure of the steam mixing pump 4 is set according to a desired sterilization temperature for each liquid, and the set value and the above-described pressure detection value are set. Based on this difference, the rotation speed of the rotor 44 of the steam mixing pump 4 to be described later is adjusted to a predetermined value as needed by frequency control of the converter.

  Further, in FIG. 1, the symbol TICA-1 measures the temperature of the liquid on the outlet side of the steam mixing pump 4 with a temperature sensor, and based on this measured value, the liquid temperature at the measurement location falls within the required temperature range. The sterilization temperature control part which adjusts the supply_amount | feed_rate of the steam to the steam mixing pump 4 so that it may be settled is shown. Specifically, a steam control valve 20 for adjusting the amount of steam supplied is provided upstream of a steam supply port 46 provided in the steam mixing pump 4 described later, and the opening degree of the steam control valve 20 is sterilized. By controlling the temperature control unit TICA-1, the supply amount of steam is set to a predetermined value. Similarly, the symbol TICA-2 measures the temperature of the liquid on the outlet side of the main cooler 7, and based on this measured value, the liquid temperature at the same measurement location is transferred to the main cooler 7 so as to be within a required temperature range. The TICA-3 is a cooling temperature control unit that adjusts the cooling water supply amount, and the temperature of the liquid at the outlet side of the heat exchanger 3 is measured. Based on this measured value, the liquid temperature at the same measurement location is required. The preheat temperature control part which adjusts the temperature (for example, heating amount by the heater 18) used for the heat exchanger 3 so that it may be settled in a temperature range is each shown.

  Moreover, in FIG. 1, the code | symbol TIA-1 is installed in order to monitor whether sterilization is performed reliably, measures the temperature of the liquid in the exit side of the hold pipe 5, and this measured value If (temperature) is not within the required sterilization temperature range, the operation of the liquid is stopped according to the information, or the information is transmitted to the third switching valve 14 or a switching signal is transmitted. The sterilization temperature monitoring part is shown. Further, the symbol FICA-1 measures the flow rate of the liquid on the outlet side of the transfer pump 2, and based on the measured value, the rotation speed of the transfer pump 2 so that the flow rate of the liquid at the measurement location becomes a predetermined value. The flow control part which adjusts (here the frequency of an inverter) is shown.

  Next, the configuration of the steam mixing pump 4 will be described.

  FIG. 2 is a cross-sectional view perpendicular to the axis of the steam mixing pump 4. As shown in the figure, the vapor mixing pump 4 is accommodated in a casing 43 having a liquid inlet 41 and an outlet 42, and inside the casing 43, and is rotatably connected to a drive shaft of a motor (not shown). A rotor 44 as a rotor, a liquid pressure increasing channel 45 formed between the inner wall 43a of the casing 43 and the rotor 44, a steam supply port 46 provided in the casing 43 and opening to the pressure increasing channel 45, It has. With this configuration, when the rotor 44 rotates and when steam is introduced, a steam supply region 47 for supplying steam to the liquid introduced into the pump 4 is formed in the opening portion of the steam supply port 46 in the pressure increasing flow path 45. Is done.

  In this embodiment, the steam mixing pump 4 is mainly composed of a cascade pump. A partition wall 48 is formed between the inflow port 41 and the discharge port 42, and a pressure increasing flow channel 45 serving as a fluid flow path extends along the outer periphery of the disk-shaped rotor 44. Are formed in a ring shape so as to connect each other. As a result, the liquid that has flowed in from the inflow port 41 flows about one round of the rotor 44 (through the pressurizing flow path 45) and is discharged from the discharge port 42 to the outside. The rotor 44 is a so-called impeller in this illustrated example, and has a plurality of blade grooves 44a along the outer periphery thereof. Further, in this embodiment, the steam supply port 46 is, in this embodiment, a circumferentially intermediate position of the pressure-rising channel 45 that is partially annular (more precisely, the distance to the inlet 41 and the distance to the outlet 42 are equal). It is opened on the side closer to the inlet 41 than the position).

  Next, an example of a liquid heat sterilization process using the heat sterilization apparatus having the above configuration will be described.

  First, as shown in FIG. 1, the liquid discharged from the liquid tank 1 is sent to the heat exchanger 3 by the transfer pump 2, and preheating treatment (for example, 50 ° C. or more and 100 ° C. or more for bringing the temperature close to the heat treatment described later) Less than ° C). The liquid thus preheated is transferred to the vapor mixing pump 4 located on the downstream side.

  As shown in FIG. 2, the liquid sent to the vapor mixing pump 4 is introduced into the pressure increasing channel 45 from the direction of the arrow a through the inlet 41. At this time, by driving a motor (not shown), the rotor 44 connected to the drive shaft of the motor rotates, and in this illustrated example, in the direction from the inlet 41 to the outlet 42 along the pressure increasing channel 45. The liquid that rotates and is introduced into the pressure increasing channel 45 is transferred to the discharge port 42 side with pressure increasing. At the same time, steam is introduced from the steam supply port 46 provided in the casing 43 into the pressure increasing channel 45 from the direction of the arrow b, so that a steam supply region 47 formed in the opening portion of the steam supply port 46. , Vapor is supplied to the liquid under pressure transfer. Here, the liquid is heated (heated) to the heat sterilization temperature by supplying the steam whose steam temperature at the steam supply port 46 is set to be equal to or higher than the temperature at which the heat sterilization is performed. The liquid supplied with the vapor is dynamically mixed (stirred) by the rotor 44 and is sent to the discharge port 42 through the pressure increasing flow path 45 while being pressurized. And discharged outside (in the direction of arrow c in FIGS. 1 and 2).

  At this time, the pressure control unit PIC-1 detects the pressure of the liquid on the inlet side of the steam mixing pump 4 by the pressure sensor 19, and based on this detection value, the rotational speed of the rotor 44 of the steam mixing pump 4 is predetermined. Is controlled at any time. Specifically, during the sterilization process, the rotation speed of the rotor 44 is controlled by the inverter so that the pressure detection value by the pressure sensor 19 exceeds the saturated vapor pressure at the sterilization temperature determined for each liquid to be sterilized by a predetermined amount. Is done.

  In this embodiment, the temperature of the liquid on the outlet side of the steam mixing pump 4 is measured by the temperature sensor by the sterilization temperature control unit TICA-1, and based on this measurement value, during the sterilization treatment, The amount of steam supplied to the steam mixing pump 4 is adjusted so that the liquid temperature falls within the required temperature range. Specifically, the steam supply amount is adjusted by controlling the opening degree of the steam control valve 20 disposed upstream of the steam supply port 46 by the sterilization temperature control unit TICA-1.

  The liquid heated to a predetermined temperature (heat sterilization temperature) as described above is held for a certain period of time by the hold pipe 5 located on the downstream side of the vapor mixing pump 4 to perform a substantial sterilization treatment of the fluid. . At this time, the discharge port 42 of the steam mixing pump 4 and the liquid located downstream thereof are kept at a constant flow rate by the main flow pressure control unit FICA-1 and the main back pressure valve 6 disposed downstream of the hold pipe 5. And maintained at a constant pressure. Accordingly, the liquid passing through the hold pipe 5 is continuously sterilized for a predetermined time.

  Thereafter, the liquid sterilized by the hold pipe 5 is cooled to a temperature not higher than a predetermined temperature (for example, less than 100 ° C.) by the main cooler 7, thereby completing the heat sterilization process.

  After the heat sterilization treatment of the liquid, the first switching valve 10 is switched to connect to the water tank 9 and the transfer pump 2, and the second switching valve 11 is switched to configure the hold pipe 5 and the main cooler 7. By connecting the sterilization system to the drainage recovery line, the heat sterilization system is sterilized. In this case, for example, sterilization is performed by flowing water heated to a temperature equal to or higher than the heat sterilization temperature of the liquid to the heat sterilization system. After the sterilization treatment with water is completed, various control units PIC-1, TICA-1, -2, -3, TIA-1, and FICA-1 are set under the same conditions as in the heat sterilization treatment according to the next step. The first switching valve 10 and the like are switched to switch the treatment liquid from water to a liquid to be heat sterilized. At this time, the pressure control unit PIC-1 and the sterilization temperature control unit TICA-1 appropriately adjust the pump rotation speed and the steam supply amount based on the actual liquid pressure and temperature. Therefore, the heat sterilization process is continuously performed on the new liquid at an appropriate temperature.

  As described above, while using the vapor mixing pump 4 capable of transferring the liquid while increasing the pressure and mixing the vapor during the transfer, the main back pressure valve 6 is disposed on the downstream side of the pump 4, and The fluid pressure on the pump inlet side is adjusted by the pressure control unit PIC-1 and the supply amount of steam is adjusted by the sterilization temperature control unit TICA-1 as described above, and the following pressure state (saturated vapor pressure at the sterilization temperature) <( By adjusting the pump inlet side pressure) <(liquid pressure in the steam supply area) <(steam inlet pressure) <(pump outlet side pressure) And the stable heat sterilization process can be performed. Therefore, even in the heat sterilization treatment of a food and drink fluid that requires fine adjustment, the sterilization temperature required for each food can be accurately and easily adjusted.

  Further, the fluid pressure at the inlet side of the steam mixing pump 4 is used as a detection parameter, and the pump rotation speed is controlled by the pressure control unit PIC-1 based on the value of this parameter. When switching to liquid heat sterilization treatment, the pump rotation speed is reduced even if the fluid pressure on the pump inlet side temporarily decreases due to the difference in viscosity between liquid and water and the difference in path length. The fluid pressure can be restored to a predetermined value. Therefore, it is possible to immediately realize a stable sterilization state in response to a temperature change of the liquid (herein, the fluid for eating and drinking) accompanying the switching of the processing liquid. Further, in this embodiment, since the third switching valve 14 is disposed on the downstream side of the main back pressure valve 6, a large difference is caused on the secondary side of the main back pressure valve 6 due to the difference in pressure loss when the processing liquid is switched. Even when a pressure loss occurs, it is possible to eliminate the influence of the pressure loss on the sterilization system as much as possible and perform a stable sterilization treatment.

  As described above, the heat sterilization apparatus according to the present invention can stably carry out high-quality sterilization processing according to the actual sterilization processing status, and therefore uses other high-quality sterilization, for example, aseptic sterilization. Etc. can also be suitably used. For example, when performing heat sterilization by steam mixing in a sterilization environment such as aseptic sterilization, it is necessary to eliminate the valve mechanism from the sterilization system as much as possible from the viewpoint of preventing slight liquid leakage at the time of valve switching. . That is, as shown in FIG. 4, the configuration shown in FIG. 1 adopts a configuration in which the third switching valve 14 provided on the outlet side of the hold pipe 5 is omitted. However, in this case, even if the temperature of the liquid is lowered when switching from water to liquid, the liquid with insufficient sterilization cannot be released because there is no third switching valve 14. Therefore, it is necessary to switch to water again and perform system sterilization. Therefore, the heat sterilization apparatus according to the present invention can quickly cope with a temperature change particularly when switching from water to liquid. Therefore, it is possible to eliminate the unstable temperature state that has conventionally occurred at the time of switching as much as possible, and to construct a sterilization system having excellent temperature stability.

  In the above embodiment, since the main back pressure valve 6 is provided on the downstream side of the hold pipe 5 and on the upstream side of the third switching valve 14, the influence of pressure fluctuation on the secondary side of the main back pressure valve 6 is eliminated. Thus, the sterilization temperature or time in the hold pipe 5 can be managed with high accuracy.

  In the above embodiment, a so-called cascade pump (vortex pump) is used as the steam mixing pump 4. This type of pump can exhibit a very high pressure-increasing action as compared with other pumps. Therefore, like this type of heat sterilization treatment, it is very suitable for an application that requires a high pressurization action simultaneously with heating for the purpose of smoothly introducing steam as low pressure as possible into the liquid and preventing cavitation.

  Although one embodiment of the steam mixing type heat sterilization apparatus according to the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made within the scope of the present invention.

  For example, in the above-described embodiment, a case has been described in which a control unit for measuring and controlling the pressure, temperature, and flow rate of various fluids is provided to control the heat sterilization process. That is, the fluid pressure at the pump inlet side and the liquid temperature at the pump outlet side are used as detection parameters, and the heat sterilization temperature and the pressure in the steam mixing pump 4 are controlled based on these detection parameters using the pump rotation speed and steam supply amount as control parameters. Although the case of controlling the balance has been described, of course, it is not necessary to limit to this control mode. Other control modes are optional as long as at least the fluid pressure on the pump inlet side is detected and the pump rotational speed is controlled based on the detected value. For example, in the sterilization temperature control unit TICA-1, the opening of the steam control valve 20 may be adjusted by feeding back the steam pressure measured between the steam control valve 20 and the steam supply port 46. Alternatively, the liquid temperature at the outlet side of the hold pipe 5 may be detected by an appropriate temperature sensor, and the opening degree of the steam control valve 20 may be adjusted based on the detected value. Further, the fluid pressure on the pump outlet side may be measured, and the valve opening degree of the main back pressure valve 6 may be controlled based on the measured value.

  Here, as described above, the main back pressure valve 6 may be one that can adjust the opening / closing of the valve by a command from another control unit, and the structure that can automatically control the back pressure by adjusting the air pressure or the like. It may have. Of course, as long as the back pressure of the steam mixing pump 4 can be maintained, the specific mode is not particularly limited, and another back pressure control unit may be provided instead of the back pressure valve. The same applies to the other back pressure valves 8 and 13.

  Moreover, although the case where the eddy current pump was applied was demonstrated as the steam mixing pump 4 in the said embodiment, it is also possible to use pumps other than this. For example, if it is a non-volume type, a spiral pump can be used, and if it is a rotary volume type, a rotary type or screw type pump can be used. The shape of the rotor 44 does not matter. Of course, any mixing device can be used without being limited to the pump, as long as it has a rotor (rotor) and can perform the fluid pressure boosting and the dynamic mixing of the steam simultaneously by the rotating action. .

  The steam mixing type heat sterilization apparatus according to the above description can be applied to the heat sterilization treatment of various fluids, and soy milk having a relatively low sterilization temperature by utilizing its excellent heating temperature control performance and its stability. It is possible to use suitably for the fluids for eating and drinking. In addition, the heat sterilization apparatus according to the present invention is also effective for liquid medicines (including quasi-drugs) that require precise heat sterilization treatment as well as food and drink fluids.

  In order to prove the usefulness of the steam mixing type heat sterilization apparatus according to the present invention, various fluids (water, soy milk, milk, fresh cream) were heat sterilized by the sterilization apparatus, and the performance was evaluated.

  Specifically, in the configuration according to FIG. 1, the main back pressure valve 6 sets the liquid pressure P2 [MPa] on the pump outlet side (downstream of the discharge port 42 of the steam mixing pump 4) to a predetermined value, Based on the detected pressure value detected by the pressure sensor 19, the pressure control unit PIC-1 adjusts the pump rotation speed n [Hz] to maintain the liquid pressure P1 [MPa] on the pump inlet side within a predetermined value or a predetermined range. I did it. Further, the opening degree of the steam control valve 20 is adjusted by the sterilization temperature control unit TICA-1 based on the temperature T2 [° C.] on the pump outlet side so that the liquid after steam mixing becomes the heat sterilization temperature T0 [° C.] to be set. Thus, the amount of steam supplied to the steam mixing pump 4 is controlled. Further, the flow rate control unit FICA-1 was used to adjust the flow rate Q1 of the fluid on the outlet side of the transfer pump 2 to be constant, and a sterilization treatment experiment was performed on each fluid.

  FIG. 3 shows the experimental results. Here, T1 is the temperature [° C.] of the liquid at the pump inlet side, P3 is the steam introduction pressure [MPa] (the left side in the same column indicates the original pressure of the introduced steam, and the right side indicates the vapor pressure at the steam supply port). Each is shown. From the experimental results shown in the figure, it can be seen that high-precision sterilization temperature control with very few errors is performed at any set temperature and regardless of the type of treatment liquid. Further, in this case, it is understood that the supplied steam pressure (steam introduction pressure P3) is larger than the pump inlet side pressure P1 and smaller than the pump outlet side pressure P2. In any case, the saturated vapor pressure and the pump inlet side pressure P1 are equal to or higher than the saturated vapor pressure at the heat sterilization temperature T0 (eg, 0.216 at 135 ° C., 0.378 MPa at 150 ° C.) It turns out that it is set to. In addition, when comparing the control state between different liquids, for example, water and soy milk at a set temperature of 120 ° C., both sterilization temperature control is performed with high accuracy, while the pump inlet side pressure P1 is the same, Only the pump speed n is greatly different. Similar results were obtained when water and milk at a set temperature of 135 ° C. were observed. From these results, it was found that the means for controlling the fluid pressure on the pump inlet side based on the detected pressure value is also effective for heat sterilization of food and drink fluid having a viscosity higher than that of water.

  Further, in order to prove the effectiveness of the present invention at the time of switching from water to a liquid to be treated, the temperature of the fluid (water and liquid) on the outlet side of the steam mixing pump 4 before and after switching from water to liquid. And the change of pressure was evaluated. Specifically, as shown in FIG. 1 or FIG. 4, the pressure P1 of the fluid on the pump inlet side is measured, and the pump rotational speed n is appropriately controlled according to this measured value (Example) And a constant pump rotation speed n (comparative example), respectively, and heat sterilization is performed, and the change in the pump outlet pressure P2 and the temperature T2 before and after switching from water to liquid (soy milk in this case) Was evaluated for changes. The set temperature T0 was 120 ° C. Other conditions are the same as in the first embodiment.

  FIG. 5 shows the result of the comparative example, and FIG. 6 shows the result of the example. First, from the experimental results shown in FIG. 5, in the state where the pump rotational speed n is constant as in the comparative example, after switching from water to liquid (soy milk), the pump inlet side pressure P1 greatly decreases and the pump outlet side It can be seen that the pressure P2 and the temperature T2 fluctuate greatly and are in an unstable state. This is considered because the heated liquid causes so-called flushing because the pump inlet side pressure P1 is lower than the saturated vapor pressure at the sterilization temperature (120 ° C. in this case). On the other hand, from the experimental results shown in FIG. 6, in the example, the rotation speed control unit (pressure control unit PIC-1) causes the inlet side pressure P1 of the steam mixing pump 4 to be equal to or higher than the saturated vapor pressure at the sterilization temperature. Therefore, it can be seen that the introduced steam can be surely dissolved in the fluid, and that high-quality sterilization is performed.

It is the schematic which shows one structural example of the steam mixing type heat sterilization apparatus which concerns on this invention. It is an axis orthogonal sectional view of a pump for steam mixing. 3 is a table showing the results of a heat sterilization test according to Example 1. It is the schematic which shows the other structural example of a steam mixing type heat sterilizer. It is a figure which shows the result of the heat sterilization experiment of the comparative example which concerns on Example 2. FIG. It is a figure which shows the result of the heat sterilization experiment of the Example which concerns on Example 2. FIG.

Explanation of symbols

1 Liquid tank 2 Transfer pump (transfer device)
3 Heat exchanger 4 Steam mixing pump (powered mixing device)
5 Hold pipe 6 Main back pressure valve 7 Main cooler 9 Water tank 19 Pressure sensor 20 Steam control valve PIC-1 Pressure control unit TICA-1 Sterilization temperature control unit TICA-2 Cooling temperature control unit TICA-3 Preheating temperature control unit TIA- 1 Sterilization temperature monitoring unit FICA-1 Flow control unit

Claims (7)

A heating system that heats the fluid by mixing steam with the fluid to be heat sterilized, and a sterilization processing system that is connected to the downstream side of the heating system and that sterilizes the fluid heated in the heating system In a steam mixing type heat sterilizer equipped with
The heating system has at least a powered mixing device that transfers the fluid with pressure by the action of a rotor and mixes the vapor with the fluid in the middle of transfer, and
A pressure detection unit for detecting the pressure of the fluid on the inlet side of the powered mixing device; and a rotation speed control unit for controlling the rotation speed of the rotor according to the pressure value detected by the pressure detection unit. A steam mixing type heat sterilizer characterized by having.   The steam mixing type heat sterilizer according to claim 1, wherein the rotation speed control unit controls the pressure of the fluid on the inlet side of the powered mixer to be equal to or higher than a saturated vapor pressure at a sterilization temperature.   The steam mixed heat sterilizer according to claim 1 or 2, wherein the fluid is a fluid for eating and drinking.   The eating fluid or water can be selectively switched and connected to the powered mixing device, and the switching position between the eating fluid and the water is the pressure of the fluid by the pressure detector. The steam mixed heat sterilizer according to claim 3, which is located upstream of the detection position.   The said sterilization processing system has at least a holding tube for holding the heated fluid, and a back pressure control unit is disposed on the outlet side of the holding tube. Steam mixing type heat sterilizer.   The heating system further includes a steam amount control unit that controls a supply amount of the steam to the fluid based on a temperature measurement value of the fluid on an outlet side of the powered mixing device. The steam mixing type heat sterilization apparatus as described.   The heating system controls the transfer capacity of the transfer device based on the fluid transfer device disposed on the upstream side of the powered mixing device and the measured flow rate of the fluid on the outlet side of the transfer device. The steam mixing type heat sterilizer according to any one of claims 1 to 6, further comprising a flow rate control unit.

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