Air supply system and method for airlift device

Abstract

To provide an air supply system of an air lift device and a method which can save power relating to supply of air.SOLUTION: An air supply system of an air lift device includes an air lift device 1 for performing air lift which supplies air to a mixture of a granular solid and a liquid, and conveys the solid in the liquid, a high pressure air source 8 for supplying air for air lift to the air lift device 1 at high pressure, and a low pressure air source 9 for supplying air for air lift to the air lift device 1 at low pressure, wherein an air supply source for the air lift device 1 is configured so as to be switchable between the high pressure air source 8 and the low pressure air source 9.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system and method for supplying conveying air to an airlift device that supplies air to a mixture of granular solids and liquid to transport the solids. [Background technology]

[0002] Conventionally, in wastewater purification facilities, a type of filtration device has been used in which raw water to be purified is introduced into a filtration tank containing filtering media such as sand, and the raw water is filtered and purified by the filtering media while the filtering media is moved within the tank to be cleaned. This type of filtration device is called a moving bed type, and Figure 5 shows an example of such a moving bed type filtration device. Figure 5 shows a type of moving bed type filtration device, specifically one called an upflow continuous type.

[0003] The filtration device 1 is configured by housing a filter medium 3, which is a granular solid such as sand, inside a filter tank 2. The filter tank 2 is a tank having a space defined by a body 2a and a reduced diameter portion 2b connected to the bottom of the body 2a. The body 2a is cylindrical overall, and the reduced diameter portion 2b is in the shape of an inverted cone whose diameter decreases downward from the bottom end of the cylindrical body 2a. The filter medium 3 is deposited from the middle to the bottom within the body 2a, forming a layer (filtration layer) that passes through and filters raw water, and is also distributed within the reduced diameter portion 2b.

[0004] An air lift pipe 4 is installed inside the filtration tank 2 along the central axis, vertically penetrating the body section 2a and the reduced diameter section 2b. The air lift pipe 4 is a pipe for transporting and cleaning the filter medium 3 by air, and is configured as a double pipe with an air supply pipe 4a on the inside and an outer sheath pipe 4b on the outside. The air lift pipe 4 is positioned so that its middle to lower section is embedded in the layer of filter medium 3, and its lower end opens into the layer of filter medium 3.

[0005] The lower end of the air supply pipe 4a is located slightly above the lower end of the outer sheath pipe 4b, and the lower end of the air supply pipe 4a opens into the space inside the outer sheath pipe 4b.

[0006] Meanwhile, the upper end of the air supply pipe 4a protrudes above the set water level in the filter tank 2, while the upper end of the outer sheath pipe 4b is located below the set water level in the filter tank 2. A cup-shaped drainage receiver 4c is attached around the upper end of the outer sheath pipe 4b, surrounding the upper end of the outer sheath pipe 4b. A distribution section 4d is connected to the bottom of the drainage receiver 4c, surrounding the outer wall of the upper end of the outer sheath pipe 4b and extending downward. A labyrinth structure with irregularities is formed between the inner wall of the distribution section 4d and the outer wall of the outer sheath pipe 4b. As described below, the filter media 3 in the drainage receiver 4c is discharged into the space within the filter tank 2 through this labyrinth structure, while the water in the filter tank 2 rises into the drainage receiver 4c through the labyrinth structure. A drainage pipe 4e is connected to the drainage receiver 4c to guide the stored wastewater outside the filter tank 2.

[0007] Raw water is introduced into the filtration tank 2 through a raw water inlet line 5. The raw water inlet line 5 is configured to include an inlet pipe 5a and a distribution section 5b.

[0008] The inlet pipe 5a is a pipe for introducing raw water from the outside to the inside of the filtration tank 2, and its outlet end is connected to the center pipe 5c of the distribution section 5b.

[0009] The distribution section 5b includes a center pipe 5c and a discharge section 5d. The center pipe 5c is a pipe provided coaxially with the air lift pipe 4 so as to surround the periphery of the middle section of the air lift pipe 4, and the outlet end of the inlet pipe 5a is connected to its upper end. From the lower end of the center pipe 5c, the discharge section 5d extends radially around the periphery like the ribs of an umbrella. The discharge section 5d is arranged horizontally at a height near the lower end of the body section 2a within the filtration tank 2, and a raw water discharge port (not shown) is provided on the lower surface of the discharge section 5d.

[0010] A filtered water recovery unit 6 is provided at a set height above the water surface in the upper part of the filtration tank 2. The filtered water recovery unit 6 is equipped with a cup-shaped filtered water receiver 6a and a recovery pipe 6b that is connected to the bottom of the filtered water receiver 6a and extends to the outside of the filtration tank 2, so that filtered water that has overflowed the side wall of the filtered water receiver 6a and entered the filtered water receiver 6a is recovered through the recovery pipe 6b.

[0011] Furthermore, a filter medium guide 7 is provided at a position above the reduced diameter section 2b within the filter tank 2. The filter medium guide 7 is a plate-like member with a substantially conical surface that is arranged coaxially with the reduced diameter section 2b. The upper end, which corresponds to the apex of the conical surface of the filter medium guide 7, is located at a height near the lower end of the body 2a, from which the conical surface of the filter medium guide 7 extends downward while expanding in diameter, and its lower end reaches the middle of the reduced diameter section 2b. There is a gap between the lower end, which corresponds to the base of the conical surface of the filter medium guide 7, and the inner wall of the reduced diameter section 2b, and the filter medium 3 can move through this gap below the filter medium guide 7 by its own weight.

[0012] When the filtration device 1 is in operation, raw water is introduced into the filtration tank 2 through the raw water inlet line 5 (note that in Figure 5, the flow of water, such as raw water, filtered water after purification, and wastewater after cleaning the filter media 3, is represented by arrows marked with the letter W). The raw water is discharged from the discharge section 5d of the distribution section 5b of the raw water inlet line 5, and from here moves upward within the layer of the filter media 3. During this time, pollutants contained in the raw water are captured between the filter media 3, and the raw water is purified. The purified filtered water is collected from the filtered water collection section 6 at the water level above the filtration tank 2.

[0013] When purifying raw water using the filter media 3 in this way, in order to maintain the purification capacity, it is necessary to wash away the substances trapped between the filter media 3. In the filtration device 1, the filter media 3 can be washed by sending air into the filtration tank 2 (called air lift).

[0014] When air is sent into the air supply pipe 4a of the air lift pipe 4 from the upper end, the air is discharged from the lower end located within the layer of filter media 3. The discharged air rises in the space between the air supply pipe 4a and the outer sheath pipe 4b, causing the particles of filter media 3 to rise in the same space (the movement of the filter media particles is shown by the arrows marked M in Figure 5). During this process, the particles of filter media 3 are agitated in the water together with the air, and the captured contaminants are scraped off. The dislodged contaminants float in the surrounding water and rise within the space together with the water.

[0015] When the water containing pollutants reaches the upper end of the outer sheath pipe 4b, it is stored in the drain receiver 4c and discharged through the drain pipe 4e. Here, the inlet end of the drain pipe 4e is located above the bottom of the drain receiver 4c, and the filter material 3 sinks downward within the drain receiver 4c due to its own weight, so the filter material 3 is almost never discharged from the drain pipe 4e along with the wastewater.

[0016] The filter media 3 that accumulates at the bottom of the drain receptacle 4c descends under its own weight through the labyrinth structure between the sorting section 4d and the outer sheath pipe 4b and returns to the layer of filter media 3 in the filter tank 2. The pollutants contained in the wastewater in the drain receptacle 4c have a lower specific gravity than the filter media 3 and float in the wastewater. Therefore, they do not easily pass through the labyrinth structure like the filter media 3. Furthermore, the water level inside the drain receptacle 4c is adjusted to be lower than the water level outside the drain receptacle 4c in the filter tank 2. This difference in height creates a downward-to-upward water flow in the labyrinth structure. The lighter pollutants are retained in the drain receptacle 4c by this water flow, while the heavier filter media 3 can pass downward through the labyrinth structure under its own weight regardless of the water flow. (Note that the rising water in the space between the air supply pipe 4a and the outer sheath pipe 4b described above is also driven by this difference in height.)

[0017] The particles of filter medium 3 that descend from sorting section 4d are deposited on top of the layer of filter medium 3 in filter tank 2. The layer of filter medium 3 gradually descends within filter tank 2 due to its own weight. The particles of filter medium 3 that reach the bottom of narrowing section 2b are lifted up into air lift pipe 4 by air as the air lift operates, washed, and returned to the top of the layer again.

[0018] Here, the particles of filter medium 3 that descend from sorting section 4d first accumulate near the central axis within filter tank 2, but because conical filter medium guide section 7 is provided below that, the particles of filter medium 3 that accumulate above filter medium guide section 7 are first guided to the outer periphery by filter medium guide section 7, and only the amount of particles that pass between the inner wall of narrowing section 2b and the lower end of filter medium guide section 7 moves downwards in each case. This prevents the load of filter medium 3 particles that have accumulated high near the central axis from concentrating excessively on the lower end of air lift pipe 4.

[0019] In this way, in the filtration device 1, raw water can be continuously purified by the filter medium 3 while maintaining its purification capacity by circulating the filter medium 3 while cleaning it with the air lift.

[0020] Incidentally, examples of documents describing the technology relating to such moving bed filtration devices include Patent Documents 1 and 2 listed below. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-094769 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-262045 Summary of the Invention [Problem to be solved by the invention]

[0022] In the moving-bed filtration system described above, when the air lift is restarted after a long period of inactivity, a higher air pressure is required to supply air compared to when the air lift is running continuously. Without air to lift the filter media 3, the filter media 3 near the lower end of the air lift pipe 4 is gradually compacted by the weight of the filter media 3 stacked above. It is believed that a higher air pressure is required to agitate the compacted filter media 3. However, high air pressure is only required for a short time immediately after the air lift is started; lower air pressure is sufficient for subsequent continuous operation. However, with conventional systems using compressors and air tanks, it is difficult to freely adjust the pressure of the supplied air according to the required pressure. Ultimately, even during continuous operation when lower air pressure is sufficient, high air pressure must be used, resulting in wasted power.

[0023] SUMMARY OF THE INVENTION In view of the above circumstances, the present invention aims to provide an air supply system and method for an air lift device that can reduce the power required for supplying air. [Means for solving the problem]

[0024] The present invention provides an air lift device that supplies air to a mixture of granular solids and liquid to perform air lift, transporting the solids within the liquid; a high-pressure air source that supplies high-pressure air for air lift to the air lift device; a low-pressure air source that supplies low-pressure air for air lift to the air lift device; an operation monitoring unit that monitors the operation status of the air lift in the air lift device, The high pressure is a pressure that can start the air lift that has been stopped, The low pressure is a pressure at which the air lift can be continuously operated, The air supply source for the air lift device is configured to be switchable between the high-pressure air source and the low-pressure air source based on data acquired from the operation monitoring unit. The present invention relates to an air supply system for an air lift device characterized by the above.

[0025] The present invention provides an air lift device that supplies air to a mixture of granular solids and liquid to perform air lift, transporting the solids within the liquid; a high-pressure air source that supplies high-pressure air for air lift to the air lift device; a low-pressure air source that supplies air for air lift at low pressure to the air lift device; The high pressure is a pressure that can start the air lift that has been stopped, The low pressure is a pressure at which the air lift can be continuously operated, the high-pressure air source is a cylinder; The air supply source for the air lift device is configured to be switchable between the high-pressure air source and the low-pressure air source. The present invention relates to an air supply system for an air lift device characterized by the above.

[0026] In the air supply system for the air lift device of the present invention, the operation monitoring unit can be at least one of a pressure gauge that measures the pressure of the air supplied to the air lift device, a microphone that detects the operating sound of the air lift device, and a camera that optically grasps the operating status of the air lift device.

[0027] The air supply system of the air lift device of the present invention can also be configured to switch the air supply source for the air lift device from the high-pressure air source to the low-pressure air source based on the time since the air lift operation was started in the air lift device.

[0029] In the air supply system for the air lift device of the present invention, the low pressure air source may be a blower.

[0030] In the air supply system for the air lift device of the present invention, the air lift device may be a moving bed type filtration device.

[0031] The present invention also provides an air lift device that supplies air to a mixture of granular solids and liquid to carry out air lift, transporting the solids within the liquid, comprising: When operating the air lift, high pressure air is supplied at the start of the air lift, then it switches to low pressure air supply, Switching the supply of air to the air lift device from high pressure to low pressure based on the operating status of the air lift in the air lift device; The high pressure is a pressure that can start the air lift that has been stopped, The low pressure is a pressure that allows continuous operation of the air lift. To The present invention relates to an air supply method for an air lift device, characterized by the above.

[0033] In the air supply method for an air lift device of the present invention, the supply of air to the air lift device can be switched from high pressure to low pressure based on the time since the air lift operation was started in the air lift device.

[0034] The air supply method for an air lift device of the present invention can be applied to a moving bed type filtration device. [Effects of the Invention]

[0035] According to the air supply system and method for an air lift device of the present invention, it is possible to achieve the excellent effect of reducing the power required for supplying air. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a block diagram showing an example of the configuration of an air supply system for an air lift device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram showing an example of the configuration of an air supply system for a conventional air lift device, as a reference example of the present invention. [Figure 3] 10 is a graph showing an example of fluctuations in air pressure when an air lift is started. [Figure 4] 1 is a flowchart showing an example of the procedure of an air supply method for an air lift device according to an embodiment of the present invention. [Figure 5] FIG. 1 is a front cross-sectional view showing an example of a moving bed type filtration device as an air lift device. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0038] Fig. 1 shows an example of the configuration of an air supply system for an air lift device according to the present invention. In the embodiment shown here, a filtration device 1 similar to the example shown in Fig. 5 is assumed as the air lift device, and therefore the following explanation will refer to Fig. 5 and the reference numerals shown in the figure as necessary.

[0039] The air supply system of this embodiment is characterized by being equipped with a high-pressure air source 8 that supplies high-pressure air and a low-pressure air source 9 that supplies low-pressure air as air supply sources for the air lift device (filtration device) 1, and being configured so that the air supply source can be switched between the high-pressure air source 8 and the low-pressure air source 9 when the air lift is in operation. Here, in this specification, with regard to air pressure, "high pressure" means a pressure at which the air lift can be started up after being stopped, and is a pressure higher than "low pressure." "Low pressure" means a pressure at which the air lift can be operated continuously, and is a pressure lower than "high pressure." The specific configurations of the high-pressure air source 8 and the low-pressure air source 9 will be described later.

[0040] Air sent out from high-pressure air source 8 and low-pressure air source 9 is supplied to filtration device 1 via air supply lines 10. Air supply lines 10 extend from the air outlet sides of high-pressure air source 8 and low-pressure air source 9, respectively, merge midway, and are connected downstream to air supply pipe 4a (see Figure 5) of air lift pipe 4 provided in filtration device 1. Filtration device 1 is the same as filtration device 1 shown in Figure 5, and is configured by housing filter medium 3 inside filtration tank 2 equipped with air lift pipe 4, raw water inlet line 5, filtered water recovery section 6, and filter medium guide section 7.

[0041] On the upstream side of the joining point of the air supply line 10, on-off valves 11 and 12 for opening and closing the air flow path are provided at positions downstream of the high pressure air source 8 and the low pressure air source 9, respectively.

[0042] The opening and closing of the on-off valves 11 and 12 is controlled by a control unit 13. The control unit 13 is a control device that monitors and controls the operation of various parts of the system, including the filtration device 1, high-pressure air source 8, low-pressure air source 9, etc., and opens and closes the on-off valves 11 and 12 in response to signals input from an operation monitoring unit 14 and turning the air lift on and off, as will be described later.

[0043] The operation monitoring unit 14 is a device that monitors the operating state of the air lift in the air lift device 1. The operation monitoring unit 14 can be, for example, a pressure gauge that measures the pressure of the air supplied to the air lift device 1, a microphone that detects the operating sound of the air lift device 1, or a camera that optically monitors the operating state of the air lift device 1. Note that FIG. 1 illustrates the operation monitoring unit 14 as a pressure gauge. Measurement data acquired by the operation monitoring unit 14 (the content of the measurement data varies depending on the configuration of the operation monitoring unit 14, such as pressure values, audio data, image data, etc.) is input as a data signal to the control unit 13. Based on the signal input from the operation monitoring unit 14, the control unit 13 determines whether the air lift device 1 is currently in continuous air lift operation. Note that, here, "continuous operation" of the air lift refers to a state in which the air lift continues to operate after a certain amount of time has passed since its activation, even though the supply pressure of the air required for the air lift has become low. As mentioned above, when an air lift is started after being stopped for a long period of time, the pressure required to operate the air lift rises significantly immediately after startup, and then stabilizes at a low pressure after a short period of time has passed (this will be explained again later).

[0044] When the operation monitoring unit 14 is a pressure gauge, for example, as shown in Fig. 1, the operation monitoring unit 14, which is a pressure gauge, is installed in a position just before the air lift device 1 in the air supply line 10, and measures the pressure of the air supplied to the air lift device 1. The air pressure at this position is zero when the air lift is stopped, and when the air lift is started, it rises from zero to a high pressure value in a short time, and then becomes almost stable at a low pressure. Therefore, for example, if the pressure value remains within a certain range for a certain period of time or more, it can be determined that the air lift is in continuous operation.

[0045] For example, in an operation test conducted by the inventors of the present application, the pressure value during continuous air lift operation in a certain filtration device was almost stable at about 0.1 MPa. Therefore, for this filtration device, the pressure value range for determining continuous operation can be set to 0.04 MPa or more and 0.2 MPa or less, and after the start of air lift operation, the pressure value can be measured every 10 seconds. If a pressure value within this range is measured twice in a row, it can be determined that continuous operation is established.

[0046] The specifications of the filtration device and the properties of the filter media used in the test are as follows: (Filtering device specifications) Filtration area (cross-sectional area of ​​the body 2a of the filtration tank 2): 1 m 2 Inner diameter of air supply pipe 4a: 32 mm (cross-sectional area: approx. 8.04 cm 2 ) Injection depth (distance from the water surface (water surface in the filter tank 2 other than the drainage receiver 4c and the filtered water collection unit 6) to the bottom end of the air supply pipe 4a): Approximately 3,429 mm Height of the filtration layer (average distance from the surface of the filter layer 3 to the bottom of the air supply pipe 4a): Approximately 2,500 mm (Properties of filter media) Effective particle diameter: 1.48mm Uniformity factor: 1.35 ·Porosity: 0.4

[0047] The specific pressure value and range at which continuous operation is considered to be established may vary depending on conditions such as the specifications of the air lift device and the properties of the filter material. In other words, the values ​​described above are merely examples, and the actual pressure values ​​used for the determination should be individually set to suit the air lift device in question. Furthermore, the time interval for measuring the pressure value and the conditions for determining that a certain range of pressure value is continuing may also be changed as appropriate. For example, instead of measuring the pressure every 10 seconds, the pressure value fluctuations may be measured every moment, and continuous operation may be determined to be established if a certain range of pressure value continues for 10 consecutive seconds.

[0048] When the operation monitoring unit 14 is a microphone, the operation monitoring unit 14, which is a microphone, is installed near the air lift device 1 to detect the operation sound generated from the air lift device 1. While the air lift is being performed, noise is generated according to the operating state, so it can be determined that the air lift is in continuous operation if, for example, a sound of a specific frequency is generated at a volume above a certain level for a certain period of time or more.

[0049] When the operation monitoring unit 14 is a camera, it is installed in a position where the state inside the filtration tank 2 can be optically observed (such as inside the filtration tank 2 or outside a window provided in the filtration tank 2), and an image of the inside of the filtration tank 2 is input as a data signal to the control unit 13. While the air lift is operating, the air lift causes the filter media 3 to circulate, and if this is detected by a function such as image recognition, it can be determined that the air lift is operating continuously.

[0050] In addition, any suitable device or sensor may be adopted as the operation monitoring unit 14 as long as it can appropriately monitor the operating state of the air lift in the air lift device 1. Note that multiple types of mechanisms may be used in combination as the operation monitoring unit 14.

[0051] A regulator 15 for preventing backflow of air is provided in the air supply line 10 downstream of the high-pressure air source 8 and upstream of the on-off valve 11. The regulator 15 is, for example, a check valve of a general structure, and opens the air flow path only when air pressure equal to or greater than a set pressure value is applied from upstream. Note that such a regulator for preventing backflow is considered particularly necessary in the flow path on the high-pressure air source 8 side, where high-pressure air flows, and in the example shown here, the regulator 15 is provided only on the high-pressure air source 8 side. However, a similar regulator may also be provided on the low-pressure air source 9 side, depending on the pressure values ​​that may actually occur during system operation.

[0052] In an actual system, a filter for removing dust from the supplied air, a regulating valve for adjusting the air volume, a flow meter for measuring the air flow rate, etc. are installed, but illustrations and descriptions of such components that are not directly related to the gist of the present invention have been omitted as appropriate.

[0053] FIG. 2 shows an example of a conventional air supply system as a reference example of the present invention. Unlike the above-described embodiment (see FIG. 1), this reference example has only one air source system for the air lift device (filtration device) 1. The air source in this reference example is configured with an air tank 16 and a compressor 17 to continuously supply high-pressure air for long periods of time. The compressor 17 takes in outside air, compresses it, and sends it into the air tank 16. The air tank 16 stores the compressed air and sends it to the air lift device 1 through the air supply line 10. A pressure switch 18 is provided at the outlet side of the air tank 16. The pressure switch 18 switches the motor of the compressor 17 on and off depending on the air pressure at the outlet side of the air tank 16, and operates the motor of the compressor 17 only when a certain range of air pressure is applied from upstream. That is, for example, when the pressure of the air sent out from air tank 16 is below a certain threshold, the motor of compressor 17 is turned on to start supplying compressed air to air tank 16 and store the compressed air in air tank 16, and when the pressure of the air sent out from air tank 16 reaches or exceeds another threshold (a value higher than the threshold), the motor of compressor 17 is stopped to stop storing the compressed air. In this way, air tank 16 is always configured to store a constant amount of compressed air.

[0054] Figure 3 shows an example of fluctuations in air pressure (pressure at a position immediately before the air lift device 1) when an air lift is started in a supply system such as that shown in Figure 2. When air supply is started at time t0 after the operation of the air lift has been stopped for a long period of time (for example, one hour or more), the pressure value rises rapidly from that point until time t1. After reaching a maximum value at time t1, the pressure value begins to decline, and after time t2, although there are some fluctuations, it stabilizes at a generally constant low pressure.

[0055] As mentioned above, such fluctuations in pressure value occur because, over a long period of time when the filter material 3 is not stirred or lifted by air, the filter material 3 near the lower end of the air lift pipe 4 becomes compacted by the load, and high-pressure air is required to stir the compacted filter material 3.It is also thought that once the filter material 3 has been stirred by high-pressure air, the compaction of the filter material 3 is released, allowing it to be transported smoothly.

[0056] According to operational tests conducted by the inventors of the present application, the time from the start of air lift operation (time t0) to the start of stable continuous operation (time t2) is approximately several seconds to 10 seconds. Furthermore, in operational tests of a certain filtration device, the maximum pressure detected after the air lift was started (pressure value at time t1) was approximately 0.43 MPa, and the stable pressure value after the start of continuous operation (pressure value after time t2) was approximately 0.1 MPa. However, the time required from the start of air lift to the start of stable continuous operation and the specific pressure values ​​at each time point will, of course, vary depending on the conditions of use of the air lift device, etc.

[0057] In a system like the reference example shown in Figure 2, assuming such pressure fluctuations that accompany air lift operation, the capacity of the air source (air tank 16 and compressor 17) is set based on the maximum pressure value that occurs immediately after the air lift is started. That is, if the pressure value at time t1 is, for example, 0.43 MPa, the capacity of the air source is set to provide a slight margin and supply air at a pressure of approximately 0.6 MPa or higher. More specifically, if the threshold value for turning on and off the compressor 17 via the pressure switch 18 is set to, for example, 0.65 MPa (when on) and 0.8 MPa (when off), then theoretically, air can be supplied to the air lift device 1 at a pressure of 0.65 MPa or higher, allowing for the high pressure that occurs immediately after the air lift is started.

[0058] On the other hand, once continuous operation of the air lift begins (after time t2), the air lift can continue at a pressure of about 0.1 MPa. Even if a margin is taken into account, an air pressure of about 0.2 MPa is sufficient. However, when using a conventional air supply system like the one shown in Figure 2, it is not possible to reduce the pressure of the air supplied from the air source accordingly, and continuous operation after time t2 must ultimately be carried out at a high pressure of about 0.6 MPa or higher. Generally, the higher the discharge pressure of a compressor, the greater the power consumption. For example, the power consumption when the discharge pressure is 0.2 MPa differs by about twice as much as when the discharge pressure is 0.6 MPa. In a conventional system like the one shown in Figure 2, this difference was wasted as surplus energy during continuous operation after time t2.

[0059] 1, when an air lift is performed in the air lift device (filter device) 1, high-pressure air is supplied from the high-pressure air source 8 to the filter device 1 only for a short time after startup when a supply of high-pressure air is required. After startup is complete, the air supply source is switched to supply low-pressure air from the low-pressure air source 9 to the filter device 1 during continuous operation. The air supply source can be switched by opening and closing the on-off valves 11 and 12. When the air lift is stopped, both on-off valves 11 and 12 are closed. After the air lift is started, the on-off valve 11 on the high-pressure air source 8 side is first opened to supply high-pressure air from the high-pressure air source 8 to the air lift device 1. After continuous low-pressure air lift operation begins, the on-off valve 11 on the high-pressure air source 8 side is closed and the on-off valve 12 on the low-pressure air source 9 side is opened.

[0060] Such air lift operation can be automatically performed in accordance with a flowchart such as that shown in Figure 4, for example, based on the input of air lift operation commands to the air lift device 1 and data obtained from the operation monitoring unit 14 (data regarding the operating status of the air lift in the air lift device 1).

[0061] While air lift operation is stopped, the control unit 13 waits while monitoring whether or not an air lift operation command has been input (step S1). If an air lift operation command has not been input, the control unit 13 closes both the on-off valves 11 and 12 on the high-pressure air source 8 side and the low-pressure air source 9 side, which are provided in the air supply line 10 (step S2). Since both the on-off valves 11 and 12 are closed while air lift operation is stopped, the closed state is maintained in step S2.

[0062] When a command to operate the air lift is input, the process moves from step S1 to step S3. In step S3, the signal input from the operation monitoring unit 14 is referenced to determine whether or not continuous operation of the air lift is currently established in the air lift device (step S3). As described above, whether or not continuous operation is established can be determined based on the pressure value, operating sound, image data, etc.

[0063] Immediately after the air lift operation command is input, continuous operation is not established, so the process moves from step S3 to step S4, and air lift using high-pressure air is started. That is, the on-off valve 11 on the high-pressure air source 8 side is opened. The on-off valve 12 on the low-pressure air source 9 side is kept closed.

[0064] Next, the process returns to step S1. At this point, a command for air lift operation has been input, so the process proceeds to step S3, where a determination is made again as to whether continuous operation has been established. For a while after air lift operation has started (between time t0 and time t2 in FIG. 3), continuous operation has not yet been established, so steps S1, S3, and S4 are repeated to continue air lift using high-pressure air (a state in which the high-pressure side on-off valve 11 is open and the low-pressure side on-off valve 12 is closed).

[0065] When a sufficient amount of time has passed since the start of air lift operation, continuous operation is established, and a determination to that effect is made in step S3. If continuous operation is established, the process proceeds to step S5, where air lift using low-pressure air is started. That is, the on-off valve 11 on the high-pressure air source 8 side is closed, and the on-off valve 12 on the low-pressure air source 9 side is opened. After switching the on-off valves 11 and 12 in this way, the process returns to step S1.

[0066] Thereafter, while the air lift operation command is on, steps S1, S3, and S5 are repeated, and continuous operation using low-pressure air continues. When the air lift operation command is turned off, the process moves from step S1 to step S2, and both on-off valves 12 are closed to stop the air lift. Then, steps S1 to S2 are repeated and the system waits until the air lift operation command is turned on again.

[0067] In this way, by switching between high and low pressure air sources to perform air lift, high pressure air is supplied from high pressure air source 8 only while high pressure air is needed during air lift operation (time t0 to time t2 in Figure 3), and low pressure air is supplied from low pressure air source 9 after continuous operation with low pressure air becomes possible (after time t2), thereby making it possible to significantly reduce the energy required for operation after time t2.

[0068] Furthermore, when switching the air supply source from high pressure to low pressure, this can be done automatically and suitably based on the operating status of the air lift ascertained by the operation monitoring unit 14.

[0069] Furthermore, a method of switching the air source based on the passage of time may be adopted, without relying on monitoring the operating state of the air lift in the air lift device 1. For example, in the above procedure shown in the flowchart of FIG. 4, a determination regarding the passage of time may be made instead of step S3 (determination of the operating state). In this determination step, it is determined whether a certain set time (the time corresponding to time t0 to time t2 in FIG. 3, or a sufficient time longer) has elapsed since it was determined that the air lift operation command was on in the current operation. The air lift using high-pressure air is continued until the set time has elapsed (step S4), and after the set time has elapsed, the air lift is switched to an air lift using low-pressure air (step S5). In this way, even if the air supply source is switched based on the time since the air lift operation was started in the air lift device 1, operation similar to that using the operation monitoring unit 14 is possible. In addition, various configurations and procedures other than those described here can be adopted as the system and method for air supply, as long as they can appropriately switch between high-pressure and low-pressure air.

[0070] The configuration of the air supply source will now be described. The high-pressure air source 8 may be equipped with a mechanism consisting of an air tank and a compressor similar to the air source shown in Figure 2, but when the air source is switched to operate the air lift as described above, the time period during which high-pressure air is required is short, only a few to 10 seconds per operation. In other words, the ability to continuously supply high-pressure air for long periods of time is not necessarily required. Therefore, for example, a replaceable cylinder may be used as the high-pressure air source 8. If a small cylinder is replaced every time the air lift is operated a specified number of times or more, a large-scale device such as an air tank or compressor is not required as the high-pressure air source, and the installation space and equipment costs can be reduced.

[0071] The low-pressure air source 9 may also be a mechanism consisting of an air tank and compressor similar to the air source shown in Figure 2, but the required air pressure for the low-pressure air source 9 is lower than that of the air source in the system shown in Figure 2. Therefore, depending on the pressure value required in the actual system, a simple mechanism such as a blower that delivers air at low pressure may be used as the low-pressure air source 9, rather than an air tank or compressor. A blower can also reduce equipment costs compared to installing a compressor and air tank.

[0072] Although the airlift device described here is a moving bed type filtration device 1 as shown in Figure 5, various other devices that perform airlift can be considered as airlift devices to which the system and method of the present invention can be applied. Note that the airlift here refers to supplying air to a mixture of granular solids and liquid to transport the solids within the liquid.

[0073] According to tests conducted by the applicants, the pressure-switching airlift operation described above is considered to be effective at least in a moving-bed filtration system with the following specifications: However, the following specifications are merely a guideline, and the method of the present invention can also be applied to filtration systems other than those specified below, or to various other airlift systems. Inner diameter of air supply pipe: 20mm to 100mm Length of air lift pipe: 2,500mm to 5,000mm Height of the filter layer (average distance from the surface of the filter layer to the bottom of the air supply pipe): 1,000 mm or more and 4,000 mm or less Injection depth (distance from the water surface to the bottom of the air supply pipe): 2,300 mm to 4,800 mm Air volume (speed of air sent into the air lift pipe when the air lift is operating): 0.3 m / s or more, 1.5 m / s or less

[0074] As described above, the air supply system for the air lift device of this embodiment is characterized by comprising an air lift device (filter device) 1 that supplies air to a mixture of granular solids (filter material 3) and liquid (water W) and performs air lift to transport the solids (filter material) 3 within the liquid (water) W, a high-pressure air source 8 that supplies air for the air lift to the air lift device 1 at high pressure, and a low-pressure air source 9 that supplies air for the air lift to the air lift device 1 at low pressure, and is configured so that the air supply source for the air lift device 1 can be switched between the high-pressure air source 8 and the low-pressure air source 9.

[0075] Furthermore, in the air supply method for the air lift device of the present embodiment, air is supplied to a mixture of granular solids (filter material 3) and liquid (water W), and the air lift device 1 performs an air lift to transport the solids (filter material) 3 within the liquid (water) W. When the air lift is in operation, high-pressure air is supplied when the air lift is started, and then the supply of low-pressure air is switched over to.

[0076] In this way, continuous operation using low-pressure air becomes possible when performing air lift, and energy required for subsequent operations can be significantly reduced.

[0077] In addition, the air supply system of the air lift device of this embodiment is equipped with an operation monitoring unit 14 that monitors the operating status of the air lift in the air lift device 1, and is configured to be able to switch the air supply source for the air lift device 1 from the high-pressure air source 8 to the low-pressure air source 9 based on the data obtained from the operation monitoring unit 14.

[0078] In addition, in the air supply method for the air lift device of this embodiment, the supply of air to the air lift device 1 is switched from high pressure to low pressure based on the operating status of the air lift in the air lift device 1.

[0079] In this way, the air supply source can be automatically and suitably switched during operation of the air lift.

[0080] In addition, in the air supply system of the air lift device of this embodiment, the operation monitoring unit 14 can be at least one of a pressure gauge that measures the pressure of the air supplied to the air lift device 1, a microphone that detects the operating sound of the air lift device 1, and a camera that optically grasps the operating status of the air lift device 1.

[0081] In addition, the air supply system of the air lift device of this embodiment can also be configured to be able to switch the air supply source for the air lift device 1 from the high-pressure air source 8 to the low-pressure air source 9 based on the time since the air lift operation in the air lift device 1 is started.

[0082] In addition, in the air supply method for the air lift device of this embodiment, the supply of air to the air lift device 1 can be switched from high pressure to low pressure based on the time since the air lift operation in the air lift device 1 was started.

[0083] In this way, the air supply source can be automatically and suitably switched during operation of the air lift.

[0084] In the air supply system of the air lift device of this embodiment, the high-pressure air source 8 can be a cylinder. In this way, the installation space and equipment costs for the machine serving as the high-pressure air source 8 can be reduced.

[0085] In the air supply system of the air lift device of this embodiment, the low pressure air source 9 can be a blower. In this way, the cost of the equipment for the low pressure air source 9 can be reduced.

[0086] In the air supply system for the air lift device of this embodiment, the air lift device 1 is a moving bed type filtration device.

[0087] The air supply method of the air lift device of this embodiment can be applied to the moving bed type filtration device 1.

[0088] In this way, the same effects as those described above can be achieved in a moving bed type filtration device.

[0089] Therefore, according to the present embodiment, it is possible to save power required for supplying air.

[0090] It should be noted that the air supply system and method for the air lift device of the present invention are not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. [Explanation of symbols]

[0091] 1. Air lift device (filtration device) 3 Solid (filter media) 8. High-pressure air source 9 Low pressure air source 14 Operation monitoring section W Liquid (water)

Claims

1. an air lift device that supplies air to a mixture of granular solids and liquid to perform air lift, transporting the solids within the liquid; a high-pressure air source that supplies high-pressure air for air lift to the air lift device; a low-pressure air source that supplies low-pressure air for air lift to the air lift device; an operation monitoring unit that monitors the operation status of the air lift in the air lift device, The high pressure is a pressure that can start the air lift that has been stopped, The low pressure is a pressure at which the air lift can be continuously operated, The air supply source for the air lift device is configured to be switchable between the high-pressure air source and the low-pressure air source based on data acquired from the operation monitoring unit. An air supply system for an air lift device, characterized by:

2. an air lift device that supplies air to a mixture of granular solids and liquid to perform air lift, transporting the solids within the liquid; a high-pressure air source that supplies high-pressure air for air lift to the air lift device; a low-pressure air source that supplies air for air lift at low pressure to the air lift device; The high pressure is a pressure that can start the air lift that has been stopped, The low pressure is a pressure at which the air lift can be continuously operated, the high-pressure air source is a cylinder; The air supply source for the air lift device is configured to be switchable between the high-pressure air source and the low-pressure air source. An air supply system for an air lift device, characterized by:

3. The operation monitoring unit a pressure gauge for measuring the pressure of the air supplied to the air lift device; a microphone for detecting the operation sound of the air lift device; a camera for optically grasping the operating status of the air lift device; 2. The air supply system for an air lift device according to claim 1, wherein the air supply system is at least one of the above.

4. The air lift device is configured to be able to switch the air supply source for the air lift device from the high-pressure air source to the low-pressure air source based on the time elapsed since the air lift operation was started in the air lift device.

3. The air supply system for an air lift device according to claim 1 or 2.

5. 5. The air supply system for an air lift device according to claim 1, wherein the low-pressure air source is a blower.

6. 6. The air supply system for an air lift device according to claim 1, wherein the air lift device is a moving bed type filtration device.

7. An air lift device that supplies air to a mixture of granular solids and liquid to carry out an air lift that transports solids within the liquid, When operating the air lift, high pressure air is supplied at the start of the air lift, then it switches to low pressure air supply, Switching the supply of air to the air lift device from high pressure to low pressure based on the operating status of the air lift in the air lift device; The high pressure is a pressure that can start the air lift that has been stopped, The low pressure is a pressure that allows continuous operation of the air lift. An air supply method for an air lift device.

8. Switching the supply of air to the air lift device from high pressure to low pressure based on the time since the air lift operation was started in the air lift device.

8. The air supply method for an air lift device according to claim 7,

9. 9. The air supply method for an air lift device according to claim 7 or 8, wherein the method is applied to a moving bed type filtration device.

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