Peracetic acid aqueous solution delivery system

Abstract

To more accurately measure the peracetic acid concentration of a peracetic acid aqueous solution.SOLUTION: The present invention relates to a peracetic acid aqueous a liquid feeding system 1 of a peracetic acid aqueous solution that circulates the peracetic acid aqueous solution between sterilizing means 2 that sterilizes objects to be sterilized with a peracetic acid aqueous solution and a peracetic acid aqueous solution tank 3 that stores the peracetic acid aqueous solution. Peracetic acid concentration detection means 10, cooling means 11 for cooling the peracetic acid aqueous solution by cooling water, and a flow rate adjustment valve 29 for adjusting a flow rate of the cooling water are provided in a concentration detection pipe 9 branched from a supply pipe 4. Cooling water temperature detection means 30 for detecting a temperature B of the cooling water is provided in a cooling water pipe 27. A target temperature A obtained by adding a predetermined temperature to the temperature B of the cooling water detected by the cooling water temperature detecting means 30 is set, and a temperature C of the peracetic acid aqueous solution flowing through the concentration detection pipe 9 is cooled to the target temperature A by controlling the flow rate adjustment valve 29.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid feeding system for an aqueous peracetic acid solution, and more particularly to a liquid feeding system for an aqueous peracetic acid solution provided with peracetic acid concentration detecting means for detecting the concentration of the aqueous peracetic acid solution.

Background Art

[0002] Conventionally, in a beverage filling line for filling beverages into containers such as PET bottles, the PET bottles are sterilized before filling the beverages, and an aqueous peracetic acid solution as a sterilizing medium is sprayed onto the PET bottles. As a liquid feeding system for supplying an aqueous peracetic acid solution to the sterilizing means for sterilizing the PET bottles, there is known a system configured to circulate the aqueous peracetic acid solution between the sterilizing means and a peracetic acid aqueous solution tank for storing the aqueous peracetic acid solution (Patent Document 1). On the other hand, in order to sterilize the PET bottles, it is necessary to keep the peracetic acid concentration of the aqueous peracetic acid solution within a certain range. The liquid feeding system of Patent Document 1 is provided with peracetic acid concentration detecting means for measuring the peracetic acid concentration and monitors the concentration. As the peracetic acid concentration detecting means, there is known a so-called electrochemical measurement method, that is, a current is passed through a pair of electrodes in contact with an aqueous peracetic acid solution to cause an oxidation-reduction reaction on these electrodes and measure the current value, and a required conversion formula is applied to this current value to calculate the concentration (see Patent Document 2, particularly column 0040).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, peracetic acid solution is susceptible to temperature changes, and prolonged exposure to high temperatures can easily cause peracetic acid to decompose into acetic acid and hydrogen peroxide. Therefore, it is desirable to cool the peracetic acid solution when measuring its concentration. However, in the liquid delivery system described in Patent Document 1, since the tank is equipped with a means for detecting the peracetic acid concentration, it is necessary to cool all the peracetic acid aqueous solution in circulation before measuring its concentration, which has the problem of being thermally inefficient and wasteful. Furthermore, while it is conceivable to perform heat exchange between the peracetic acid solution and cooling water to cool the peracetic acid solution, if the temperature of this cooling water changes depending on the environment, the temperature variation of the cooled peracetic acid solution becomes large, leading to problems such as unstable concentration measurement by peracetic acid concentration detection means using electrochemical measurement. In view of these problems, the present invention provides a peracetic acid aqueous solution delivery system that can more accurately measure the peracetic acid concentration of the peracetic acid aqueous solution. [Means for solving the problem]

[0005] In other words, the peracetic acid aqueous solution delivery system according to the present invention comprises a sterilization means for sterilizing an object to be sterilized with a peracetic acid aqueous solution, a peracetic acid aqueous solution tank for storing the peracetic acid aqueous solution, a supply pipe for supplying the peracetic acid aqueous solution from the peracetic acid aqueous solution tank to the sterilization means, a return pipe for returning the peracetic acid aqueous solution from the sterilization means to the peracetic acid aqueous solution tank, a heating means provided in the middle of the supply pipe for heating the peracetic acid aqueous solution, a peracetic acid concentration detection means for measuring the concentration of the peracetic acid aqueous solution, and a control means for controlling these, in a peracetic acid aqueous solution delivery system, Upstream of the heating means in the supply piping, a concentration detection pipe is branched off to allow the peracetic acid solution flowing through the supply piping to be returned to a peracetic acid solution tank. This concentration detection pipe is equipped with a peracetic acid concentration detection means and a peracetic acid temperature detection means for detecting the temperature of the peracetic acid solution. Upstream from the peracetic acid concentration detection means and the peracetic acid temperature detection means in the concentration detection piping, a cooling means is provided to perform heat exchange with the cooling water piping through which the cooling water flows, a flow rate adjustment valve is provided to adjust the flow rate of the cooling water in the cooling water piping, and a cooling water temperature detection means is provided to detect the temperature of the cooling water. The control means is characterized by setting a target temperature by adding a predetermined temperature to the temperature of the cooling water detected by the cooling water temperature detection means, and further controlling the flow rate adjustment valve to cool the temperature of the peracetic acid aqueous solution in the concentration detection piping to the target temperature. [Effects of the Invention]

[0006] According to the above invention, a concentration detection pipe is branched from the circulation path formed between the peracetic acid aqueous solution tank and the sterilization means, and a peracetic acid concentration detection means and a cooling means are provided in the concentration detection pipe. As a result, it becomes possible to measure the concentration without cooling all of the circulating peracetic acid aqueous solution, enabling efficient concentration measurement. Furthermore, when measuring the peracetic acid concentration of the peracetic acid solution, a target temperature for the peracetic acid solution is set, and this target temperature is varied according to the temperature change of the cooling water, while the solution is cooled so that the actual temperature of the peracetic acid solution reaches the target temperature. This makes it possible to more accurately measure the peracetic acid concentration in a peracetic acid solution, regardless of changes in the cooling water temperature. [Brief explanation of the drawing]

[0007] [Figure 1] Circuit diagram of the fluid delivery system according to this embodiment [Figure 2] A diagram showing the relationship between cooling water temperature, peracetic acid solution temperature, and target temperature. [Modes for carrying out the invention]

[0008] The following describes the illustrated embodiment. Figure 1 shows a liquid delivery system 1 that delivers a peracetic acid aqueous solution to sterilize a PET bottle, which is the object to be sterilized. The liquid transfer system 1 described above is installed in a container sterilization device that constitutes a beverage filling line, and comprises a sterilization means 2 for sterilizing PET bottles with a peracetic acid aqueous solution, a peracetic acid aqueous solution tank 3 for storing the peracetic acid aqueous solution, a supply pipe 4 for supplying the peracetic acid aqueous solution from the peracetic acid aqueous solution tank 3 to the sterilization means 2, a return pipe 5 for returning the peracetic acid aqueous solution from the sterilization means 2 to the peracetic acid aqueous solution tank 3, and a heating means 6 installed in the middle of the supply pipe 4 for heating the peracetic acid aqueous solution. Furthermore, the liquid transfer system 1 includes a peracetic acid concentrate supply means 7 for supplying peracetic acid concentrate to the peracetic acid solution tank 3 and a water supply means 8 for supplying water to the peracetic acid solution tank 3, in order to create a new peracetic acid solution by supplying peracetic acid concentrate and water when the amount of peracetic acid solution in the peracetic acid solution tank 3 decreases. Furthermore, the liquid delivery system 1 is configured to constantly measure the concentration of the peracetic acid aqueous solution, and includes a concentration detection pipe 9 branched off from the supply pipe 4, a peracetic acid concentration detection means 10 provided in the concentration detection pipe 9, and a cooling means 11 for cooling the peracetic acid aqueous solution flowing through the concentration detection pipe 9. Furthermore, the liquid delivery system 1 of this embodiment is controlled by the control means 12.

[0009] Since the above-mentioned sterilization means 2 is conventionally known, a detailed explanation will be omitted, but the other end of the supply pipe 4 and the other end of the return pipe 5 are connected, and it is equipped with a spray nozzle that sprays the peracetic acid solution supplied via the supply pipe 4 onto the PET bottle, and a recovery means that collects the peracetic acid solution that has fallen after being sprayed and discharges it to the return pipe 5. In this embodiment, the liquid delivery system provides, as an example, an aqueous peracetic acid solution with a temperature of 55-65°C and a peracetic acid concentration of 2000-2500 ppm to the sterilization means 2.

[0010] The peracetic acid aqueous solution tank 3 is capable of storing a predetermined amount of peracetic acid aqueous solution. One end of the supply pipe 4 is connected to the lower part of the peracetic acid aqueous solution tank 3, and one end of the return pipe 5 is connected to the upper part. The peracetic acid solution supplied from the peracetic acid solution tank 3 to the sterilization means 2 via the supply pipe 4 is used to sterilize PET bottles, then recovered by the sterilization means 2, and returned to the peracetic acid solution tank 3 via the return pipe 5. Here, when the peracetic acid solution is sprayed into the PET bottle using the sterilization means 2, the total amount of the peracetic acid solution decreases due to evaporation, etc. Therefore, a level sensor 3a is provided in the peracetic acid solution tank 3 to monitor the amount of the peracetic acid solution.

[0011] The supply piping 4 is equipped with a first pump 13 that delivers the peracetic acid solution from the peracetic acid solution tank 3 to the sterilization means 2, and downstream of the first pump 13 is equipped with the heating means 6 that heats the peracetic acid solution. The first pump 13 described above is used to deliver the peracetic acid aqueous solution used in the sterilization means 2, and in this embodiment, it is possible to deliver the solution at a flow rate of, for example, 26,000 L / h. The heating means 6 is composed of a heat exchanger 6a, to which the supply pipe 4 and the heating pipe 14 are connected. Superheated steam is supplied to the heating pipe 14 from the steam supply source 31. Heat exchange takes place between the superheated steam flowing through the heating pipe 14 and the peracetic acid aqueous solution flowing through the supply pipe 4 via the heat exchanger 6a, thereby heating the peracetic acid aqueous solution to 55-65°C before it is sent to the sterilization means 2. The return pipe 5 described above returns the peracetic acid solution used in the sterilization means 2 back to the peracetic acid solution tank 3, and the temperature of the peracetic acid solution used in the sterilization means is cooled to about 40°C. Therefore, the peracetic acid aqueous solution tank described above is designed to store peracetic acid aqueous solution at approximately 40°C that is being circulated.

[0012] The peracetic acid stock solution supply means 7 is composed of a stock solution tank 15 for storing the peracetic acid stock solution, a peracetic acid stock solution supply source 16 for supplying the peracetic acid stock solution to the stock solution tank 15, a stock solution supply pipe 17 disposed between the peracetic acid aqueous solution tank 3 and the stock solution tank 15, and a second pump 18 provided in the stock solution supply pipe 17. When the level sensor 3a provided in the peracetic acid aqueous solution tank 3 detects a decrease in the liquid level, the control means 12 controls the second pump 18 to feed a predetermined amount of the peracetic acid stock solution toward the peracetic acid aqueous solution tank 3. Also, when a decrease in the concentration of the peracetic acid aqueous solution is detected, the control means 12 controls the second pump 18 to feed a predetermined amount of the peracetic acid stock solution toward the peracetic acid aqueous solution tank 3.

[0013] The water supply means 8 is composed of a water supply source 19 for supplying water (hereinafter also referred to as cooling water), a water tank 20 for temporarily storing the water, a water supply pipe 21 disposed between the peracetic acid aqueous solution tank 3 and the water tank 20, and a third pump 22 provided in the water supply pipe 21. An on-off valve 24 controlled by the control means 12 is provided in a water supply pipe 23 provided between the water supply source 19 and the water tank 20. The water supply means 8 of the present embodiment is also configured to supply cooling water to the cooling means 11 provided in the concentration detection pipe 9. When the level sensor 3a provided in the peracetic acid aqueous solution tank 3 detects a decrease in the liquid level, the control means 12 controls the third pump 22 to feed a predetermined amount of water stored in the water tank 20 toward the peracetic acid aqueous solution tank 3. The on-off valve 24 is opened when a decrease in the liquid level is detected by a level sensor (not shown) provided in the water tank 20, and water from the water supply source 19 is supplied to the water tank 20. Here, the temperature of the water supplied by the water supply source 19 is not managed to be constant, and it changes according to the time of use under the influence of the outside air. For example, the temperature of the cooling water during the day is higher than that in the early morning and late at night (see Figure 2).

[0014] The concentration detection pipe 9 is branched off from the supply pipe 4 at a position upstream of the heating means 6, and its end is connected to the peracetic acid aqueous solution tank 3. Therefore, the peracetic acid solution discharged from the peracetic acid solution tank 3 flows through the concentration detection piping 9 and is then returned to the peracetic acid solution tank 3. The concentration detection piping 9 is equipped with a peracetic acid concentration detection means 10 for measuring the concentration of the peracetic acid solution, as well as a fourth pump 25 for supplying the peracetic acid solution, a cooling means 11 for cooling the peracetic acid solution, and a peracetic acid temperature detection means 26 for measuring the temperature of the peracetic acid solution. The fourth pump 25, installed in the concentration detection piping 9, is set to deliver a lower flow rate than the first pump 13 installed in the supply piping 4. For example, while the first pump 13 in the supply piping 4 delivers liquid at a flow rate of 26,000 L / min, the fourth pump 25 is set to deliver liquid at a flow rate of 100 L / min.

[0015] The peracetic acid concentration detection means 10 described above measures the peracetic acid concentration of an aqueous peracetic acid solution based on a so-called electrochemical measurement method, and for example, the one described in Patent Document 2 can be used. A detailed explanation of the peracetic acid concentration detection means 10 will be omitted, but it works by passing an electric current through a pair of electrodes in contact with a peracetic acid aqueous solution to cause an oxidation-reduction reaction in these electrodes, measuring the current value of the current that passes through the peracetic acid aqueous solution, and applying a required conversion formula to the measured current value to calculate the peracetic acid concentration of the peracetic acid aqueous solution. Furthermore, in order to calculate the peracetic acid concentration of the peracetic acid aqueous solution using the peracetic acid concentration detection means 10, the peracetic acid becomes unstable and easily decomposes into acetic acid and hydrogen peroxide when the temperature of the peracetic acid aqueous solution is 40°C or higher. Therefore, in this embodiment, the peracetic acid concentration is measured when the peracetic acid aqueous solution is cooled to a target temperature A of less than 40°C by the cooling means 11.

[0016] The cooling means 11 includes a heat exchanger 11a provided in the concentration detection pipe 9, a cooling water pipe 27 branched off from the water supply pipe 21 connected to the water tank 20 which constitutes the water supply means 8, a fifth pump 28 provided in the cooling water pipe 27, and a flow rate adjustment valve 29 controlled by the control means 12. Furthermore, a cooling water temperature detection means 30 for measuring the temperature of the cooling water is provided in the water supply pipe 23 installed between the water supply source 19 and the water tank 20. The cooling water pipe 27 is branched off from the water supply pipe 21 and connected to the water tank 20, and the cooling water in the water tank 20 is circulated through the cooling water pipe 27. The heat exchanger 11a is connected to the concentration detection pipe 9 and the cooling water pipe 27. Heat exchange takes place between the peracetic acid aqueous solution flowing through the concentration detection pipe 9 and the cooling water flowing through the cooling water pipe 27, thereby cooling the peracetic acid aqueous solution to the target temperature A. The flow rate adjustment valve 29 installed in the cooling water piping 27 is controlled by the control means 12 to adjust the flow rate of the cooling water, thereby making it possible to adjust the degree of cooling of the peracetic acid aqueous solution in the heat exchanger 11a.

[0017] In this embodiment, the liquid supply system 1 is configured such that the temperature of the cooling water supplied from the water source 19 fluctuates due to the influence of the outside air, and if the temperature fluctuation range of the peracetic acid solution is large, the concentration value detected by the peracetic acid concentration detection means 10 becomes unstable. Therefore, the cooling of the peracetic acid solution is controlled by fluctuating the target temperature A according to the temperature of the cooling water measured by the cooling water temperature detection means 30 installed in the water supply pipe 23. Specifically, the target temperature A is set to a temperature obtained by adding 2°C to the temperature of the cooling water.

[0018] The operation of the liquid delivery system 1 according to the above embodiment will be described below. First, a predetermined amount of peracetic acid solution is contained in the peracetic acid solution tank 3. From this state, the first pump 13, which is installed in the supply pipe 4, is activated and the peracetic acid solution is sent to the sterilization means 2. At this time, the amount of liquid sent by the first pump 13 is set to, for example, 26,000 L / h. In the supply pipe 4 described above, the peracetic acid aqueous solution passes through the heat exchanger 6a of the heating means 6, and heat exchange takes place with the heated steam flowing through the heating pipe 14, heating the peracetic acid aqueous solution to 55-65°C. The heated peracetic acid solution is sprayed onto the outer and inner surfaces of the PET bottle in the sterilization means 2. The sprayed peracetic acid solution is then collected in the sterilization means 2 and returned to the peracetic acid solution tank 3 via the return pipe 5. At this point, the peracetic acid solution used in the sterilization means 2 has cooled to approximately 40°C. When the amount of peracetic acid solution in the peracetic acid solution tank 3 decreases due to use in the sterilization means 2, the level sensor 3a detects the drop in the liquid level, and the control means 12 activates the second pump 18, which constitutes the peracetic acid concentrate supply means 7, and the third pump 22, which constitutes the water supply means 8, to send a predetermined amount of peracetic acid concentrate and water to the peracetic acid solution tank 3, thereby replenishing the peracetic acid solution.

[0019] On the other hand, in the liquid delivery system 1 of this embodiment, the temperature of the peracetic acid aqueous solution is adjusted to 55-65°C and the concentration to 2000-2500 ppm before being delivered to the sterilization means 2. The concentration is measured by circulating a portion of the peracetic acid aqueous solution from the peracetic acid aqueous solution tank 3 through the concentration detection piping 9. The control means 12 operates the fourth pump 25 of the concentration detection piping 9 to circulate a portion of the peracetic acid aqueous solution flowing through the supply piping 4 into the concentration detection piping 9. At this time, for example, the liquid flow rate of the fourth pump 25 is set to 100 L / h, which is less than the flow rate of the first pump 13 of the supply piping 4. On the other hand, the temperature of the peracetic acid solution discharged from the peracetic acid solution tank 3 to the supply pipe 4 is approximately 40°C, and the concentration of the peracetic acid solution exceeding 40°C cannot be accurately measured. Therefore, the concentration detection piping 9 is equipped with a cooling means 11 upstream of the peracetic acid concentration detection means 10, so that the peracetic acid aqueous solution is reliably cooled to a target temperature A of less than 40°C before the concentration is measured.

[0020] In this way, the peracetic acid aqueous solution cooled to the target temperature A by the cooling means 11 is measured for concentration by the peracetic acid concentration detection means 10. As described above, the peracetic acid concentration detection means 10 measures the current value flowing through the peracetic acid aqueous solution using an electrochemical measurement method, and calculates the concentration by applying a required conversion formula to this current value. Figure 2 is a graph illustrating the target temperature A in the control means 12 described above, with the vertical axis representing temperature and the horizontal axis representing time. Figure 2(a) shows a diagram illustrating the method for setting the target temperature A according to the present invention, and Figure 2(b) shows the case where the target temperature A is kept constant. Figure 2 also shows the target temperature A, the cooling water temperature B measured by the cooling water temperature detection means 30, and the peracetic acid solution temperature C measured by the peracetic acid temperature detection means 26. As mentioned above, the cooling water temperature B fluctuates throughout the day, with temperatures being higher during the day than in the early morning and at night. Furthermore, this trend is not consistent daily due to weather conditions and may be affected by other factors.

[0021] To explain the method for setting the target temperature A according to the present invention shown in Figure 2(a), the control means 12 measures the cooling water temperature B measured by the cooling water temperature detection means 30, and then sets a predetermined temperature, for example 2°C, added to the cooling water temperature B as the target temperature A. As described above, the cooling water supplied from the water source 19 undergoes temperature changes as shown in Figure 2(a), so the target temperature A fluctuates according to the cooling water temperature B. Specifically, if the measured coolant temperature B is 23°C, the target temperature A is set to 25°C, and if the coolant temperature B rises to 24°C, the target temperature A is changed to 26°C. Meanwhile, the control means 12 measures the peracetic acid solution temperature C, which is the temperature of the peracetic acid solution flowing through the concentration detection pipe 9, using the peracetic acid temperature detection means 26, and the control means 12 cools the peracetic acid solution using the cooling means 11 so that the peracetic acid solution temperature C becomes the target temperature A. At this time, the control means 12 controls the flow rate adjustment valve 29 installed in the cooling water piping 27 based on the temperature difference between the target temperature A and the measured peracetic acid aqueous solution temperature C, thereby adjusting the flow rate of the cooling water, so that the peracetic acid aqueous solution temperature C of the peracetic acid aqueous solution flowing through the concentration detection piping 9 is cooled to the target temperature A.

[0022] In this way, the peracetic acid aqueous solution cooled by the cooling means 11 is configured to have its concentration measured as it passes through the peracetic acid concentration detection means 10. Here, the current value measured by the peracetic acid concentration detection means 10 is obtained from the peracetic acid aqueous solution actually flowing through the concentration measurement pipe 9, but the actual temperature C of the peracetic acid aqueous solution at this time may differ from the target temperature A. In other words, the peracetic acid aqueous solution temperature C measured by the peracetic acid temperature detection means 26 shown in Figure 2(a) fluctuates in a zigzag pattern up and down over time, because the peracetic acid temperature detection means 26 measures the temperature at predetermined intervals. In other words, during the measurement interval by the peracetic acid temperature detection means 26, the control means 12 controls the flow rate adjustment valve 29 to adjust the flow rate of the cooling water. As a result, temperatures that have been excessively cooled and have dropped to near the cooling water temperature B, and temperatures that have exceeded the target temperature A where cooling is insufficient, are detected, resulting in the zigzag measurement results described above. Therefore, in this embodiment, as shown in Figure 2(a), the target temperature A is set to follow the cooling water temperature B, and the peracetic acid aqueous solution temperature C is cooled to follow the target temperature A. As a result, the amount of displacement in the zigzag temperature change of the peracetic acid aqueous solution temperature C detected by the peracetic acid temperature detection means 26 can be reduced, thereby stabilizing the concentration detected by the peracetic acid concentration detection means 10.

[0023] In contrast, as shown in Figure 2(b), if the target temperature A is set to a constant value and the cooling means 11 is configured to make the peracetic acid aqueous solution temperature C follow the target temperature A, the difference between the target temperature A and the cooling water temperature B becomes large, for example, during times when the cooling water temperature B is low, such as early morning or late at night. In this case, because the peracetic acid temperature detection means 26 measures the temperature at predetermined intervals, the difference between the decreased value close to the cooling water temperature B and the increased value close to the target temperature A becomes large. In other words, the temperature fluctuation range of the peracetic acid aqueous solution temperature C, which is being measured, became large, causing the concentration value detected by the peracetic acid concentration detection means 10 to fluctuate significantly and making it impossible to detect properly.

[0024] While the sterilization means 2 is performing sterilization on the PET bottles, the peracetic acid concentration detection means 10 constantly measures the concentration of the peracetic acid solution. If the concentration deviates from a concentration suitable for use in the sterilization means 2, the control means 12 controls the peracetic acid stock solution supply means 7 to supply the peracetic acid stock solution to the peracetic acid solution tank 3, or controls the water supply means to supply water to the peracetic acid solution tank 3, thereby maintaining a constant concentration of the peracetic acid solution.

[0025] According to the above embodiment, since a portion of the peracetic acid solution supplied from the peracetic acid solution tank 3 to the sterilization means 2 is branched to the concentration detection pipe 9 for concentration measurement, only a portion of the circulating peracetic acid solution needs to be cooled by the cooling means 11, and the concentration can be measured more efficiently compared to when the entire amount of peracetic acid solution is cooled. Furthermore, in this embodiment, a target temperature A is set for the peracetic acid aqueous solution whose concentration is to be measured, and this target temperature A is varied to follow the change in the cooling water temperature B. By making the actual temperature C of the peracetic acid aqueous solution follow the target temperature A, the range of temperature fluctuations in the peracetic acid aqueous solution whose concentration is to be measured is reduced, making it possible to perform more accurate concentration measurement.

[0026] In the above embodiment, the target temperature A is set to the cooling water temperature B plus 2°C, but it is not limited to this value; for example, it could be set to the cooling water temperature B plus 3°C. Furthermore, although the sterilization means 2 in the above embodiment is used to sterilize PET bottles, it is also possible to sterilize other items as the object to be sterilized. [Explanation of Symbols]

[0027] 1. Liquid delivery system 2. Sterilization means 3 Peracetic acid aqueous solution tank 9 Piping for concentration measurement 10 Peracetic acid concentration detection means 11 Cooling means 12 Control means 19 Water supply source 26 Peracetic acid temperature detection means 27 Cooling water piping 29 Flow rate adjustment valve 30 Cooling water temperature detection means A Target temperature B Cooling water temperature C Peracetic acid aqueous solution temperature

Claims

1. A peracetic acid solution delivery system comprising: a sterilization means for sterilizing an object to be sterilized with a peracetic acid solution; a peracetic acid solution tank for storing the peracetic acid solution; a supply pipe for supplying the peracetic acid solution from the peracetic acid solution tank to the sterilization means; a return pipe for returning the peracetic acid solution from the sterilization means to the peracetic acid solution tank; a heating means provided in the middle of the supply pipe for heating the peracetic acid solution; a peracetic acid concentration detection means for measuring the concentration of the peracetic acid solution; and a control means for controlling these, wherein Upstream of the heating means in the supply piping, a concentration detection pipe is branched off to allow the peracetic acid solution flowing through the supply piping to be returned to a peracetic acid solution tank. This concentration detection pipe is equipped with a peracetic acid concentration detection means and a peracetic acid temperature detection means for detecting the temperature of the peracetic acid solution. Upstream from the peracetic acid concentration detection means and the peracetic acid temperature detection means in the concentration detection piping, a cooling means is provided to perform heat exchange with the cooling water piping through which the cooling water flows, a flow rate adjustment valve is provided to adjust the flow rate of the cooling water in the cooling water piping, and a cooling water temperature detection means is provided to detect the temperature of the cooling water. The control means sets a target temperature by adding a predetermined temperature to the temperature of the cooling water detected by the cooling water temperature detection means, and further controls the flow rate adjustment valve to cool the temperature of the peracetic acid solution in the concentration detection piping to the target temperature, thereby providing a peracetic acid solution liquid delivery system.

2. The peracetic acid aqueous solution delivery system according to claim 1, characterized in that the flow rate of the peracetic acid aqueous solution flowing through the concentration detection piping is less than the flow rate of the peracetic acid aqueous solution flowing through the supply piping.

Images