Hot water cleaning system and hot water cleaning method

Abstract

To provide a hot water cleaning system which enables energy saving in generation of hot water needed for cleaning of a membrane, and to provide a hot water cleaning method.SOLUTION: A hot water cleaning system according to an embodiment includes: a hot water generation unit 20 which uses a heating medium to heat cleaning water; a cleaning unit 30 which uses cleaning water heated by the hot water generation unit 20 to clean a membrane module 2; a heat accumulation / radiation unit 40 which accumulates heat energy of the cleaning water used for cleaning the membrane module 2 in the cleaning unit 30 and discharges the accumulated heat energy; and a control device 10 which controls heat accumulation and heat radiation of the heat accumulation / radiation unit 40.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a hot water cleaning system and a hot water cleaning method. [Background technology]

[0002] For example, the amount of electricity used for sludge treatment and incineration at sewage treatment plants accounts for approximately 27% of the plant's total power consumption, making it necessary to reduce sludge and improve energy efficiency in sludge treatment. One method for reducing sludge is to use a membrane separation activated sludge process, which involves filtering sludge using a membrane (hereinafter referred to as membrane filtration sewage treatment). With membrane filtration sewage treatment, high-concentration activated sludge remains in the treated water for a long period of time, which is expected to reduce sludge through the self-decomposition of the sludge.

[0003] The membranes used in membrane filtration sewage treatment must be periodically cleaned to remove deposits on the membrane surface or within the membrane pores. In addition to using chemicals, membranes can also be cleaned with warm water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-212438 Summary of the Invention [Problem to be solved by the invention]

[0005] When cleaning filtration membranes with hot water, a large amount of heat energy is consumed from the start to the end of the cleaning process and to keep the membrane module containing the filtration membrane warm. Therefore, there is a need to reduce the energy required for generating hot water for membrane cleaning. The embodiments of the present invention have been made in consideration of the above circumstances, and an object of the present invention is to provide a hot water cleaning system and a hot water cleaning method that realize energy saving in hot water generation associated with membrane cleaning. [Means for solving the problem]

[0006] The hot water cleaning system according to the embodiment includes a hot water generating unit that heats cleaning water using a heating medium, a cleaning unit that cleans a membrane module using the cleaning water heated in the hot water generating unit, a heat storage / discharge unit that stores thermal energy of the cleaning water used to clean the membrane module in the cleaning unit and releases the stored thermal energy, and a control device that controls the heat storage and heat release in the heat storage / discharge unit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a water treatment plant in which a hot water cleaning system according to an embodiment is operated. [Figure 2] FIG. 2 is a diagram schematically illustrating a configuration example of a warm water cleaning system according to an embodiment. [Figure 3] FIG. 3 is a diagram for explaining the function of the heat storage material of the heat storage tank provided in the hot water cleaning system of the embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of the operation of the control device in the warm water washing system of the embodiment. [Figure 5] FIG. 5 is a diagram showing an example of operation of the warm water cleaning system in the normal cleaning mode according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of operation of the warm water cleaning system in the backup cleaning mode according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. 1 is a diagram showing an example of the configuration of a water treatment plant in which a hot water cleaning system according to an embodiment is operated. In the following description, the hot water cleaning system according to the embodiment is assumed to be operated in a sewage treatment plant that performs sewage treatment by membrane filtration, for example.

[0009] A sewage treatment plant in which the hot water cleaning system of the embodiment is operated includes at least a reaction tank 1 having a membrane module 2. The sewage treatment plant to which the hot water cleaning system of the embodiment is applied may also have a structure for performing other water treatment processes. For example, the sewage treatment plant in the embodiment may also have a structure for performing other water treatment processes, such as an inflow adjustment tank or an anoxic tank, upstream of the reaction tank 1.

[0010] The membrane module 2 is a module used for filtering treated water, for example, in a water treatment process. In this embodiment, the membrane module 2 is provided inside a reaction tank 1 of a sewage treatment plant. The membrane module 2 incorporates, for example, a module in which a number of hollow tubular filtration membranes are bundled together. The filtration membrane incorporated in the membrane module 2 is, for example, a UF membrane, an RO membrane, or the like.

[0011] The reaction tank 1 decomposes raw water containing organic matter, such as sewage, that flows into it, and discharges clear treated water. The reaction tank 1 includes a blower B installed at the bottom on the upstream side, a membrane module 2 installed at the bottom on the downstream side, and a pump P installed at the bottom on the downstream side. Raw water (water to be treated), from which solids have been removed using a fine mesh screen or the like, flows into the reaction tank 1. By supplying air to the reaction tank 1 from the blower B, the organic matter contained in the water to be treated that has flowed into the reaction tank 1 comes into contact with the activated sludge in the reaction tank 1 and is decomposed. After that, in the reaction tank 1, the water to be treated after the decomposition treatment is filtered by the membrane module 2, and the activated sludge and treated water are separated. The reaction tank 1 discharges the produced treated water to the outside.

[0012] The activated sludge separated by the membrane module 2 is extracted from the reaction tank 1 by a pump P and collected. In the reaction tank 1, a portion of the collected activated sludge is returned upstream (internal circulation), and the remainder is discharged as excess sludge. The discharged excess sludge is dehydrated and incinerated within the sewage treatment plant and then disposed of externally.

[0013] Next, a warm water washing system according to an embodiment will be described. FIG. 2 is a diagram schematically illustrating a configuration example of a warm water cleaning system according to an embodiment. The hot water cleaning system is operated in a sewage treatment plant that performs sewage treatment by membrane filtration as described above, for example, and cleans the filtration membrane used in the sewage treatment with hot water. The hot water cleaning system includes a control device 10, a switching valve 11, a water storage tank 12, a hot water generating unit 20, a cleaning unit 30, and a heat storage and dissipation unit 40.

[0014] The switching operation of the switching valve 11 is controlled by the control device 10, and switches between opening and closing a path through which the heating medium is introduced into the hot water generator 20 and a path through which the heating medium is discharged from the hot water generator 20. The switching valve 11 includes valves 11a, 11b, 11c, and 11d.

[0015] Valves 11a and 11b are valves that switch between opening and closing of a path through which a heating medium is introduced into hot water generator 20. In the embodiment, valve 11a switches between opening and closing of a path through which exhaust heat air generated during the incineration of excess sludge, for example, as the heating medium, is introduced into hot water generator 20. Valve 11b switches between opening and closing of a path through which heat dissipation air released from heat storage and dissipation unit 40 is introduced into hot water generator 20 as the heating medium.

[0016] Valves 11c and 11d are valves that switch between opening and closing the path through which the heating medium is discharged from the hot water generator 20. Valve 11c switches between opening and closing the path through which the heating medium discharged from the hot water generator 20 is exhausted to the outside. Valve 11d switches between opening and closing the path through which the heating medium discharged from the hot water generator 20 is introduced into the heat storage and release unit 40.

[0017] In the hot water cleaning system of the embodiment, the water tank 12 is a water tank that stores the cleaning water discharged from the heat storage and release unit 40. For example, the cleaning water discharged from the heat storage and release unit 40 may be temporarily stored in the water tank 12 and then discharged from the water tank 12 to the reaction tank 1 or upstream of the reaction tank 1 in the sewage treatment plant. Alternatively, the hot water cleaning system may be configured to omit the configuration of the water tank 12 and directly discharge the cleaning water from the heat storage and release unit 40 to the reaction tank 1 or upstream of the reaction tank 1.

[0018] The hot water generating section 20 heats the wash water using the introduced heating medium and outputs the heated wash water to the washing section 30. The hot water generating section 20 includes a first heat exchanger 21, a boiler 22, and a thermometer 23.

[0019] The first heat exchanger 21 exchanges heat between the introduced heating medium and the wash water, thereby heating the wash water. The first heat exchanger 21 uses the thermal energy of the heating medium introduced from a path including valves 11a and 11b to heat wash water introduced from the outside for washing the filtration membrane. The first heat exchanger 21 introduces the heated wash water into the boiler 22. The first heat exchanger 21 also discharges the heating medium used to heat the wash water into a path including valves 11c and 11d.

[0020] The boiler 22 is controlled by the control device 10 and heats the cleaning water introduced from the first heat exchanger 21 to a predetermined temperature. For example, the boiler 22 heats the cleaning water introduced from the first heat exchanger 21 to approximately 70°C under the control of the control device 10. The boiler 22 outputs the cleaning water introduced from the first heat exchanger 21 to the cleaning section 30 regardless of whether or not the cleaning water has been heated. The boiler 22 is, for example, an electric boiler or the like.

[0021] The thermometer 23 is located in a path leading to the cleaning water from the first heat exchanger 21 to the boiler 22, and measures the temperature of the cleaning water. The thermometer 23 is controlled by the control device 10, and transmits the measured temperature of the cleaning water to the control device 10. Alternatively, the thermometer 23 transmits a signal to the control device 10 indicating whether the measured temperature of the cleaning water exceeds a predetermined temperature. The predetermined temperature is, for example, a threshold value used to set the cleaning water for the membrane module 2 to be cleaned within an appropriate temperature range, and is 70°C in this embodiment.

[0022] The cleaning unit 30 cleans the membrane module 2 using cleaning water heated in the hot water generation unit 20. The membrane module 2 is removed from the water tank of the water treatment plant periodically or when the filtration efficiency decreases, and is installed in the cleaning unit 30. The cleaning unit 30 is controlled by the control device 10, cleans the membrane module 2 using cleaning water introduced from the boiler 22, and discharges the cleaned cleaning water into the heat storage and release unit 40. For example, the cleaning unit 30 cleans the membrane module 2 by flowing the cleaning water in the opposite direction to the direction in which the water is passed through the filtration membrane, or by agitating the cleaning water in a cleaning tank in which the membrane module 2 is placed, thereby removing deposits on the membrane surface and in the pores. The cleaning unit 30 may be configured to clean multiple membrane modules 2 at once.

[0023] The cleaning unit 30 may also be part of a water treatment plant that performs membrane filtration using the membrane module 2. For example, in an embodiment, the cleaning unit 30 may be part of a reaction tank in a sewage treatment plant, and may be configured to clean the membrane module 2 by flowing cleaning water into the reaction tank 1 from the downstream side where treated water is discharged.

[0024] The heat storage and release section 40 stores the thermal energy of the cleaning water used to clean the membrane module 2 in the cleaning section 30 and can release the stored thermal energy. The heat storage and release section 40 includes a second heat exchanger 41, a blower 42, a humidifier 43, a heat storage tank 44, and a moisture meter 45.

[0025] The second heat exchanger 41 exchanges heat between the wash water discharged from the washing unit 30 and the heating medium discharged from the hot water generator 20. For example, the second heat exchanger 41 recovers thermal energy from the wash water discharged from the washing unit 30 and heats the heating medium discharged from the hot water generator 20. The second heat exchanger 41 discharges the wash water from which the thermal energy has been recovered to the water tank 12. The second heat exchanger 41 also directs the heated heating medium to the blower 42. The second heat exchanger 41 is, for example, a heat pump.

[0026] The blower 42 is controlled by the control device 10 and delivers the introduced air to the heat storage tank 44. In this embodiment, while the hot water washing system is operating in a normal washing mode described later, the heating medium is introduced from the second heat exchanger 41 to the blower 42, and the blower delivers the heating medium to the heat storage tank 44 that includes an object to be heated. Also, while the hot water washing system is operating in a backup washing mode described later, the blower 42 delivers moist air, which is obtained by humidifying air drawn in from the outside, to the heat storage tank 44.

[0027] The humidifier 43 is controlled by the control device 10 and humidifies the air drawn from the outside into the blower 42. When the air drawn from the outside into the blower 42 is moist air such as outside air, the configuration of the humidifier 43 may be omitted.

[0028] The heat storage tank 44 stores and releases heat by introducing air from the blower 42. The heat storage tank 44 is filled with a heat storage material capable of storing and releasing heat. It is assumed that the heat storage material contained in the heat storage tank 44 is a heat storage material capable of storing low-temperature heat of 40°C or above, such as an amorphous aluminum hydroxide silicate and silicate composite, for example, HASClay (registered trademark).

[0029] FIG. 3 is a diagram for explaining the function of the heat storage material of the heat storage tank provided in the hot water cleaning system of the embodiment. In this embodiment, when the heat storage material in the heat storage tank 44 adsorbs moisture, it releases low-temperature, high-humidity air (moisture) and stores thermal energy by introducing high-temperature air such as exhaust heat. When the heat storage material is dry, it adsorbs moisture and releases thermal energy by introducing moist air such as outside air, and discharges high-temperature, low-humidity air. The heat storage material can be reused by alternately storing and releasing heat as described above.

[0030] The moisture meter 45 measures the moisture content of the heat storage material contained in the heat storage tank 44. The moisture meter 45 is controlled by the control device 10, and transmits the measured value of the moisture content of the heat storage material to the control device 10. The moisture meter 45 is preferably a device that can quickly measure the internal moisture content including the center of the heat storage material, such as a microwave moisture meter.

[0031] As described above, the heat storage material in the heat storage tank 44 has the property that it can store heat when it adsorbs moisture and can release heat when it is dry. The hot water cleaning system of this embodiment uses the above property to monitor the heat storage state of the heat storage material by measuring the moisture content of the heat storage material with the moisture meter 45. Specifically, the control device 10 controls the blower 42 using the value of the moisture content when the heat storage material is at its heat storage limit (first threshold value) and the value of the moisture content when the heat storage material is at its heat release limit (second threshold value), causing the heat storage material to store and release heat.

[0032] The control device 10 includes at least one processor such as a CPU (Central Processing Unit) and a storage unit (memory or auxiliary storage device) that stores a program executed by the processor, and executes the program. The storage unit of the control device 10 pre-stores a predetermined temperature value, a first threshold value, and a second threshold value required for the processing of the control device 10, which will be described later. Note that all or part of the functions of the control device 10 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be stored in a computer-readable storage medium. Examples of the computer-readable storage medium include portable media such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and storage devices such as a hard disk built into a computer system. The program may be transmitted via a telecommunications line.

[0033] The control device 10 executes each function of the warm water washing system in the embodiment by executing a stored program. The control device 10 controls the heat storage and heat release of the heat storage and release unit 40. Specifically, the control device 10 controls the blower 42 to guide the heating medium introduced into the blower 42 from the second heat exchanger 41 to the heat storage tank 44, causing the heat storage material in the heat storage tank 44 to store heat. The control device 10 also controls the blower 42 and the humidifier 43 to guide the moist air introduced into the blower 42 from the outside to the heat storage tank 44, causing the heat storage material in the heat storage tank 44 to release heat.

[0034] Next, the operation of the hot water washing system of the embodiment and the washing modes of the hot water washing system will be described. The hot water washing system of the embodiment selectively executes two washing modes: a normal washing mode in which the filtration membrane is washed with washing water heated by utilizing waste heat from the outside and the thermal energy of the washing water discharged after washing is stored, and a backup washing mode in which the filtration membrane is washed by heating washing water using the thermal energy stored in the heat storage material.

[0035] FIG. 4 is a flowchart showing an example of the operation of the control device in the warm water washing system of the embodiment. First, the control device 10 determines whether the normal washing mode has been selected by the administrator (step S1). The control device 10 accepts the mode selection by the administrator, for example, by input from an operation interface (not shown) or communication from an external terminal. If the control device 10 determines that the normal washing mode has been selected (step S1: YES), it operates the warm water washing system of the embodiment in the normal washing mode by performing operations from steps S11 to S18, which will be described later. If the control device 10 determines that the backup washing mode has been selected (step S1: NO), it operates the warm water washing system of the embodiment in the backup washing mode by performing operations from steps S21 to S29, which will be described later.

[0036] The control device 10 may also set either the normal washing mode or the backup washing mode as a default in advance, and determine whether to change the mode set in step S1. For example, when the normal washing mode is set as the default, the control device 10 proceeds to step S11 if it is selected not to change the mode, and proceeds to step S21 if it is selected to change the mode.

[0037] In addition, the control device 10 may determine whether or not a facility that generates waste heat and in which the hot water cleaning system of the embodiment is operated is operating in step S1. For example, the control device 10 proceeds to step S11 if the facility is operating, and proceeds to step S21 if the facility is not operating.

[0038] First, an example of the operation of the control device 10 when the normal cleaning mode is selected will be described. FIG. 5 is a diagram showing an example of operation of the warm water cleaning system in the normal cleaning mode according to the embodiment. When the control device 10 determines that the normal cleaning mode has been selected (step S1: YES), it opens valves 11a and 11d and closes valves 11b and 11c (step S11). By opening valves 11a and 11d, the control device 10 introduces the exhaust heat air generated when excess sludge is incinerated in the facility into the first heat exchanger 21, and also guides the exhaust heat air that has exchanged heat with cleaning water in the first heat exchanger 21 and is discharged to a path leading to the second heat exchanger 41.

[0039] The first heat exchanger 21 exchanges heat between the introduced exhaust hot air and cleaning water that flows in from the outside via a water supply pipe, thereby heating the cleaning water. The cleaning water that flows in from the outside may be a clear liquid. For example, the cleaning water is treated water that has undergone membrane filtration and is generated in a water treatment facility where the hot water cleaning system of the embodiment is operated. The first heat exchanger 21 introduces the heated cleaning water into the boiler 22. The first heat exchanger 21 also discharges the exhaust hot air that has been used to heat the cleaning water into a path in which the valve 11d is interposed.

[0040] The control device 10 determines whether the temperature of the cleaning water led from the first heat exchanger 21 to the boiler 22 exceeds a predetermined temperature (step S12). The control device 10 controls the thermometer 23 to measure and acquire the temperature of the cleaning water. The control device 10 determines whether the acquired temperature of the cleaning water exceeds a predetermined temperature that has been set in advance. Alternatively, the control device 10 may determine whether a signal indicating whether the temperature of the cleaning water exceeds the predetermined temperature has been acquired from the thermometer 23.

[0041] If the control device 10 determines in step S12 that the temperature of the wash water does not exceed the predetermined temperature (step S12: NO), the control device 10 proceeds to step S13. On the other hand, if the control device 10 determines that the temperature of the wash water exceeds the predetermined temperature (step S12: YES), the control device 10 skips the process of step S13 and proceeds to step S14.

[0042] If the temperature of the cleaning water does not exceed a predetermined temperature, the control device 10 operates the boiler 22 (step S13). The control device 10 controls the boiler 22 to heat the cleaning water introduced from the first heat exchanger 21 to a predetermined temperature. The heated cleaning water is led out from the boiler 22 to the cleaning section 30.

[0043] The control device 10 uses the cleaning water heated and introduced in the hot water generation unit 20 to clean the membrane module 2 in the cleaning unit 30 (step S14). For example, the control device 10 cleans the membrane module 2 in the cleaning unit 30 by passing the cleaning water through the cleaning unit 30 in a direction opposite to the direction in which treated water is passed through the filtration membrane in the water treatment process. The cleaning water after cleaning the membrane module 2 in the cleaning unit 30 is discharged from the cleaning unit 30 to the second heat exchanger 41 of the heat storage / discharge unit 40.

[0044] The second heat exchanger 41 exchanges heat between the wash water discharged from the washing section 30 and the exhaust air discharged from the hot water generator 20. For example, the second heat exchanger 41 recovers the thermal energy of the wash water discharged from the washing section 30 and heats the exhaust air. The second heat exchanger 41 directs the exhaust air that has undergone heat exchange to the blower 42. The second heat exchanger 41 also discharges the wash water that has undergone heat exchange into the water tank 12.

[0045] The control device 10 determines whether the moisture content of the heat storage material in the heat storage tank 44 is below a first threshold value (step S15). The control device 10 controls the moisture meter 45 to measure and acquire the moisture content of the heat storage material. The control device 10 determines whether the acquired moisture content of the heat storage material is below a preset first threshold value. Here, the value of the first threshold value is, for example, the moisture content of the heat storage material in the heat storage tank 44 when it is at its heat storage limit.

[0046] When the control device 10 determines that the moisture content of the heat storage material in the heat storage tank 44 is not below the first threshold value (step S15: NO), the control device 10 operates the blower 42 (step S16). The control device 10 controls the blower 42 to blow the exhaust heat air introduced from the second heat exchanger 41 into the heat storage tank 44. Furthermore, if the blower 42 is already operating, the control device 10 continues its operation. After controlling the blower 42, the control device 10 returns to step S12.

[0047] The heat storage tank 44 stores heat in the heat storage material filled therein by blowing exhaust heat air that has recovered thermal energy from the cleaning water after cleaning the membrane module 2 from the blower 42. In addition, the heat storage tank 44 stores heat in the heat storage material by blowing the exhaust heat air, and discharges moisture released from the heat storage material into the water tank 12.

[0048] That is, the control device 10 repeatedly performs the processes from step S12 to step S16 while the moisture content of the heat storage material included in the heat storage tank 44 is above the first threshold value. As a result, the control device 10 causes the hot water cleaning system to clean the membrane module 2 while the moisture content of the heat storage material is above the first threshold value, and also controls the blower 42 to guide the exhaust heat air introduced from the second heat exchanger 41 to the blower 42 to the heat storage tank 44 to store heat in the heat storage material.

[0049] On the other hand, when the control device 10 determines that the moisture content of the heat storage material in the heat storage tank 44 is below the first threshold value (step S15: YES), the control device 10 determines whether the blower 42 is operating (step S17).

[0050] If the control device 10 determines that the fan 42 is operating (step S17: YES), it stops the operation of the fan (step S18) and returns to step S12. On the other hand, if the control device 10 determines that the fan 42 is not operating (step S17: NO), it returns to step S12 without performing the operation of step S18.

[0051] That is, the control device 10 stops the operation of the blower 42 when the moisture content of the heat storage material in the heat storage tank 44 falls below the first threshold value. The control device 10 repeats the cleaning operation of the membrane module 2 without storing heat while the moisture content of the heat storage material is below the heat storage limit moisture content.

[0052] The hot water cleaning system of the embodiment operates as described above in the normal cleaning mode, cleaning the filtration membrane with cleaning water heated using external waste heat and storing the thermal energy of the cleaning water discharged after cleaning. For example, when the hot water cleaning system of the embodiment is operated in a sewage treatment plant, the waste heat supplied from the exhaust heat pipe can be the waste heat generated and discarded during sludge incineration. In sewage treatment plants, sludge incineration is often performed continuously, and the temperature of the discarded waste heat is high, about 200°C, so the cleaning water can often be heated to a predetermined temperature without operating the boiler 22. Therefore, the normal cleaning mode has a longer operating time and is more energy efficient than the backup cleaning mode described below.

[0053] Next, the operation of the control device 10 when the backup cleaning mode is selected will be described. FIG. 6 is a diagram illustrating an example of operation of the warm water cleaning system in the backup cleaning mode according to the embodiment. When the control device 10 determines that the backup cleaning mode has been selected (step S1: NO), it opens the valves 11b and 11c and closes the valves 11a and 11d (step S21). By opening the valves 11b and 11c, the control device 10 opens the path leading from the heat storage tank 44 to the first heat exchanger 21 and also opens the path leading to the exhaust pipe that exhausts the heat-dissipating air discharged from the first heat exchanger 21.

[0054] The control device 10 determines whether the moisture content of the heat storage material in the heat storage tank 44 exceeds a second threshold value (step S22). The control device 10 controls the moisture meter 45 to measure and acquire the moisture content of the heat storage material. The control device 10 determines whether the acquired moisture content of the heat storage material is below a preset second threshold value. Here, the value of the second threshold value is, for example, the moisture content of the heat storage material in the heat storage tank 44 when it is at its heat dissipation limit.

[0055] When the control device 10 determines that the moisture content of the heat storage material in the heat storage tank 44 does not exceed the second threshold value (step S22: NO), it controls the blower 42 and the humidifier 43 to blow moist air that has been taken in from the outside and humidified by the humidifier 43 into the heat storage tank 44 (step S23). Furthermore, if the blower 42 and the humidifier 43 are already operating, the control device 10 continues their operation.

[0056] The heat storage tank 44 is filled with heat storage material, which dissipates heat when moist air is blown from the blower 42. The heat dissipating air released from the heat storage tank 44 is led to the first heat exchanger 21 through a path including the valve 11b.

[0057] The first heat exchanger 21 uses the introduced heat radiating air as a heating medium to exchange heat between the heat radiating air and cleaning water that flows in from the outside via a water supply pipe, thereby heating the cleaning water. The first heat exchanger 21 introduces the heated cleaning water into the boiler 22. The first heat exchanger 21 also discharges the heat radiating air used to heat the cleaning water into a path (exhaust pipe) in which the valve 11c is located.

[0058] The control device 10 determines whether the temperature of the cleaning water led from the first heat exchanger 21 to the boiler 22 exceeds a predetermined temperature (step S24). The control device 10 controls the thermometer 23 to measure and acquire the temperature of the cleaning water. The control device 10 determines whether the acquired temperature of the cleaning water exceeds a predetermined temperature that has been set in advance. Alternatively, the control device 10 may determine whether a signal indicating whether the temperature of the cleaning water exceeds the predetermined temperature has been acquired from the thermometer 23.

[0059] If the control device 10 determines in step S24 that the temperature of the wash water does not exceed the predetermined temperature (step S24: NO), the control device 10 proceeds to step S25. On the other hand, if the control device 10 determines that the temperature of the wash water exceeds the predetermined temperature (step S24: YES), the control device 10 proceeds to step S26 without performing the process of step S25.

[0060] If the temperature of the cleaning water does not exceed a predetermined temperature, the control device 10 operates the boiler 22 (step S25). The control device 10 controls the boiler 22 to heat the cleaning water introduced from the first heat exchanger 21 to a predetermined temperature. The cleaning water heated in the boiler 22 is led to the cleaning section 30.

[0061] The control device 10 uses the cleaning water heated and introduced in the hot water generating unit 20 to clean the membrane module 2 in the cleaning unit 30 (step S26). For example, the control device 10 cleans the membrane module 2 in the cleaning unit 30 by passing the cleaning water through the cleaning unit 30 in a direction opposite to the direction in which treated water is passed through the filtration membrane in the water treatment process. The cleaning water after cleaning the membrane module 2 in the cleaning unit 30 is discharged from the cleaning unit 30 to the water storage tank 12.

[0062] That is, the control device 10 repeatedly performs the processes from step S22 to step S26 while the moisture content of the heat storage material in the heat storage tank 44 is below the second threshold. As a result, in the hot water cleaning system of the embodiment, while the moisture content of the heat storage material is below the second threshold, the control device 10 controls the blower 42 and the humidifier 43 to guide moist air introduced into the blower 42 from the outside to the heat storage tank 44 to cause the heat storage material to dissipate heat, and to clean the membrane module 2 with cleaning water heated using the heat dissipating air released from the heat storage material.

[0063] On the other hand, if the control device 10 determines that the moisture content of the heat storage material in the heat storage tank 44 exceeds the second threshold value (step S22: YES), it determines whether the blower 42 and the humidifier 43 are operating (step S27).

[0064] If the control device 10 determines that the blower 42 and the humidifier 43 are operating (step S27: YES), it stops the operation of the blower (step S28) and proceeds to step S24. On the other hand, if it determines that the blower 42 and the humidifier 43 are not operating (step S27: NO), it proceeds to step S24 without performing the operation of step S28.

[0065] That is, when the moisture content of the heat storage material in the heat storage tank 44 exceeds the second threshold value, the control device 10 stops the operation of the blower 42 and the humidifier 43. While the moisture content of the heat storage material exceeds the heat storage limit moisture content, the control device 10 repeats the cleaning operation of the membrane module 2 without performing heat dissipation.

[0066] The hot water cleaning system of the embodiment operates in the backup cleaning mode as described above, heating the cleaning water using the thermal energy stored in the normal cleaning mode to clean the filtration membrane. In the backup cleaning mode, the thermal energy of the cleaning water stored in the heat storage material after being used for cleaning in the normal cleaning mode is reused, resulting in higher energy efficiency than when the cleaning water is heated only by a boiler.

[0067] It should be noted that when the control device 10 is performing the processing of each of the above steps, if it receives an instruction to end the operation from, for example, an administrator, it ends the processing of FIG.

[0068] As described above, according to this embodiment, it is possible to provide a hot water cleaning system and a hot water cleaning method that realize energy saving in hot water generation associated with membrane cleaning.

[0069] That is, according to this embodiment, after generating hot water using the exhaust heat generated in the water treatment plant and performing membrane cleaning, the thermal energy of the hot water after cleaning can be recovered in a heat storage material, and the thermal energy stored in the heat storage material can be used to generate hot water for membrane cleaning.

[0070] High-temperature exhaust heat generated in water treatment plants is mainly used for power generation turbines and the like within the same treatment plant, but low-temperature exhaust heat after use is often discarded outside. However, in the normal cleaning mode of the embodiment, even low-temperature exhaust heat after primary use can be used as a heating medium as described above, resulting in high energy efficiency.

[0071] In the embodiment, the heat storage material that stores thermal energy is a heat storage material that can store low-temperature heat of 40°C or higher, as described above. This allows heat to be stored even at the temperature of hot water used for membrane cleaning.

[0072] In addition, in the embodiment, the control device 10 measures the moisture content of the heat storage material provided in the heat storage tank 44 and controls the blower 42. As a result, according to the present embodiment, the blower can be automatically stopped after the heat storage limit or heat release limit of the heat storage material is reached, thereby reducing unnecessary energy consumption.

[0073] In the above embodiment, the hot water cleaning system has been described as being operated in a sewage treatment plant, but the facility in which the hot water cleaning system is operated is not limited to a sewage treatment plant. The hot water cleaning system can be operated in any facility that performs water treatment using a filtration membrane, such as a water purification plant or a seawater desalination plant, and that includes equipment for membrane cleaning using hot water.

[0074] The program according to this embodiment may be transferred in a state where it is stored in an electronic device, or in a state where it is not stored in an electronic device. In the latter case, the program may be transferred via a network, or in a state where it is stored in a storage medium. The storage medium is a non-transitory tangible medium. The storage medium is a computer-readable medium. The storage medium may be in any form, such as a CD-ROM or a memory card, as long as it is capable of storing the program and is computer-readable.

[0075] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0076] 1... reaction tank, B... blower, P... pump, 2... membrane module, 10... control device, 11... switching valve, 11a, 11b, 11c, 11d... valves, 12... water tank, 20... hot water generation section, 21... first heat exchanger, 22... boiler, 23... thermometer, 30... cleaning section, 40... heat storage and release section, 41... second heat exchanger, 42... blower, 43... humidifier, 44... heat storage tank, 45... moisture meter

Claims

1. a hot water generating unit that heats cleaning water using a heating medium; a cleaning unit that cleans the membrane module using the cleaning water heated in the hot water generating unit; a heat storage / dissipation unit that stores thermal energy of the cleaning water used to clean the membrane module in the cleaning unit and releases the stored thermal energy; a control device that controls heat storage and heat release of the heat storage and release section.

2. The heat storage and dissipation unit is a heat storage tank having a heat storage material capable of storing and releasing heat; The warm water washing system according to claim 1 , further comprising: a blower controlled by the control device and configured to guide the introduced air to the heat storage tank.

3. The heat storage / dissipation unit further includes a heat exchanger that exchanges heat between the cleaning water and the heating medium discharged from the hot water generating unit, The warm water washing system according to claim 2 , wherein the control device controls the blower to guide the heating medium introduced from the heat exchanger to the blower into the heat storage tank to store heat in the heat storage material.

4. The warm water washing system according to claim 3 , wherein the control device acquires a moisture content of the heat storage material in the heat storage tank, and stops operation of the blower when the moisture content falls below a first threshold value.

5. The membrane module is used for sewage treatment by membrane filtration in a sewage treatment plant, 5. The warm water washing system according to claim 1, wherein the heating medium is exhaust heated air generated when excess sludge is incinerated during the sewage treatment by membrane filtration.

6. The control device controls the blower to guide moist air introduced from the outside into the blower into the heat storage tank and cause the heat storage material to dissipate heat, thereby discharging heat-dissipating air from the heat storage tank; The warm water washing system according to claim 2 , wherein the warm water generating unit heats the washing water using the heat radiating air as the heating medium.

7. The warm water washing system according to claim 6, wherein the control device acquires a moisture content of the heat storage material in the heat storage tank, and stops operation of the blower when the moisture content exceeds a second threshold value.

8. A hot water washing method performed by a hot water washing system including a hot water generating unit that heats washing water, a washing unit that washes a membrane module, a heat storage tank having a heat storage material that can store and release heat, a blower that guides introduced air into the heat storage tank, and a control device that controls the blower, Heating the cleaning water using a heating medium; Washing the membrane module with the heated washing water; heat exchange is performed between the cleaning water and the heating medium; The hot water cleaning method further comprises introducing the heating medium into the heat storage tank to store heat in the heat storage material.

9. A hot water washing method performed by a hot water washing system including a hot water generating unit that heats washing water, a washing unit that washes a membrane module, a heat storage tank having a heat storage material that can store and release heat, a blower that guides introduced air into the heat storage tank, and a control device that controls the blower, The moist air is guided into the heat storage tank to dissipate heat from the heat storage material; Heating the cleaning water using thermal energy obtained by heat dissipation from the heat storage material; A hot water cleaning method, in which the membrane module is cleaned using the heated cleaning water.

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