JP2005138015A - Aeration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aeration device which can bring out a washing effect by pulsing motion on the whole of an aeration pipe. <P>SOLUTION: The on and off operation of a first valve 61 and a second valve 62 performs switching between a first air supply and exhaust pipe 58 and a second air supply and exhaust pipe 59, which serve as pipelines for supplying air to the aeration pipe 55. The on and off operation of a third valve 63 and a fourth valve 65 performs switching between the first air supply and exhaust pipe 58 and the second air supply and exhaust pipe 59, which serve as pipelines for discharging air from the aeration pipe 55, and switching between a first exhaust opening 64 and a second exhaust opening 66. While supplying air to the aeration pipe 55, the air is exhausted through the first air supply and exhaust pipe 58 or the second air supply and exhaust pipe 59. Tank liquid is made to flow backward from air exhaust openings 67 into the aeration pipe 55 to wash the aeration pipe 55. The washing is intermittently repeated by using the pulsing motion caused by a pressure change in the aeration pipe 55. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a diffuser and relates to a technique for aeration of a mixed liquid in a tank in a membrane separation activated sludge method or the like.

  Conventionally, in the membrane separation activated sludge method, an air diffuser is disposed below the membrane separator immersed in the aeration tank, and the mixed liquid in the tank containing activated sludge in the aeration tank by the air diffused from the air diffuser The membrane surface of the membrane separation device is washed by the upward flow of the solid-gas / liquid mixed phase generated by the rise of the diffused air.

  As an air diffuser used in the membrane separation activated sludge method, there is one described in Patent Document 1. As shown in FIG. 3, a diffuser 2 and a membrane separation device 3 disposed above the diffuser 2 are immersed in the aeration tank 1, and the membrane separator 3 is an organic flat membrane type as a separation membrane. A plurality of membrane cartridges using those are arranged in parallel in the vertical direction with a predetermined interval, and a flow path is formed between adjacent membrane cartridges. Each membrane cartridge communicates with a membrane permeate flow path (not shown) and operates with the water head (gravity) in the tank or the pump suction pressure as the driving pressure.

  The air diffuser 2 has an air diffuser case 4 surrounding a lower region of the membrane separation device 3 and an air diffuser pipe 5 disposed below the air diffuser case 4. The air diffuser 5 has a predetermined diameter arranged in the horizontal direction. It consists of a main pipe 6 made of a large diameter pipe and a plurality of branch pipes 7 made of a small diameter pipe having a predetermined diameter arranged below the main pipe 6.

  The trunk pipe 6 communicates with the blower 8 serving as an air supply source on the proximal end side, and an aeration drain pipe 9 is connected to the distal end side. The branch pipe 7 has an inverted T-shape and communicates with the main pipe 6 at one upper end, and both lower ends open as air jets 10 at positions below the main pipe 6.

  The diffused drain pipe 9 is open at the tip side as an exhaust port 11 at a position above the main pipe 6 and is provided with a drain valve 12 in the middle. In the present embodiment, the exhaust port 11 is opened under atmospheric pressure on the water surface, but the exhaust port 11 may be disposed below the water surface.

  In this configuration, during normal aeration operation, the drain valve 12 is in a closed state, and the air supplied from the blower 8 passes through the main pipe 6 and from the air outlet 10 of each branch pipe 7 to the tank of the aeration tank 1. It spouts into the inner mixed liquid.

  The diffused air aerates the mixed liquid in the tank, and ascends to cause an upward flow of the solid-gas mixed phase. This upward flow stirs and mixes the mixed liquid in the tank, and supplies the mixed liquid in the tank to the flow path between the membrane cartridges of the membrane separation device 3 by cross flow. The membrane separation device 3 filters the mixed liquid in the tank through the filtration membrane of each membrane cartridge, and the upward flow flows as a sweep along the membrane surface, thereby suppressing the cake from adhering to the membrane surface of each membrane cartridge.

  During the cleaning operation, the drain valve 12 is opened while air of a predetermined pressure is supplied from the blower 8 to the main pipe 6, and the air supplied to the main pipe 6 is discharged from the exhaust port 11 to the atmospheric pressure through the diffused drain pipe 9. Exhaust.

  At this time, the mixed liquid in the tank flows back into the trunk pipe 6 through the branch pipe 7, and the mixed liquid in the tank that has flowed in reversely rinses and cleans sludge adhering to the inside of the branch pipe 7 and the trunk pipe 6. Together with the air flowing through the pipe 6, the air is discharged from the exhaust port 11 through the diffused drain pipe 9. Sludge adhering to the inside of the branch pipe 7 and the trunk pipe 6 is dried by the air at the time of air diffusion, but peeling of the sludge is promoted by infiltration of the mixed liquid in the tank into the sludge.

  The balance between the liquid phase and the gas phase of the gas-liquid mixed phase flow in the diffuser drain pipe 9 changes depending on the inflow amount of the liquid in the tank, and the liquid phase acts as a resistance as the inflow amount increases, It becomes difficult to entrain the liquid in the tank, and the liquid in the tank staying in the diffuser drain pipe 9 increases, and the exhaust is inhibited.

Inhibition by the liquid in the tank causes pulsation in the main pipe 6 and the diffused drain pipe 9, and the liquid in the tank flowing into the branch pipe 7 and the main pipe 6 from the air outlet 10 is discharged from the diffused drain pipe 9 by this pulsation. The cleaning state to be performed and the diffused state in which air is ejected from the air outlet 10 by being inhibited by the liquid in the tank staying in the diffuser drain tube 9 are repeated repeatedly. The rapid inflow of the mixed liquid in the tank to the branch pipe 7 repeatedly causes the sludge adhering to the inside of the branch pipe 7 to be repeatedly washed without repeating manual valve opening and closing operations by a control device. And sludge can be effectively removed.
JP 2002-166290 A

  However, in the configuration described above, the liquid in the tank flows into the branch pipe 7 and the main pipe 6 from the air outlet 10 and flows into the diffused drain pipe 9 from the downstream side of the main pipe 6, so that it is located on the most upstream side. The liquid in the tank does not flow into the diffuser pipe 5 on the upstream side of the branch pipe 7, and the cleaning effect cannot be given.

  This invention solves the above-mentioned subject, and it aims at providing the diffuser which can exert the washing | cleaning effect by a pulsation to the whole diffuser tube.

  In order to solve the above-described problem, an air diffuser according to claim 1 of the present invention includes an air diffuser that is immersed in a tank and arranged in a horizontal direction, and a plurality of air jets are provided at a lower portion. First and second air supply / exhaust pipes communicating with each of both ends of the trachea, air communicating with the first air supply / exhaust pipe via the first valve, and air communicating with the second air supply / exhaust pipe via the second valve A first exhaust port communicating with the first air supply / exhaust pipe via a third valve, and a second exhaust port communicating with the second air supply / exhaust pipe via a fourth valve; Switch between the first air supply / exhaust pipe and the second air supply / exhaust pipe as a pipe that vents to the diffuser pipe by opening and closing the two valves, and as a pipe that exhausts from the diffuser pipe by opening and closing the third and fourth valves Switching between the first air supply / exhaust pipe and the second air supply / exhaust pipe, and switching between the first exhaust port and the second exhaust port While supplying air to the air diffuser, the air is exhausted through the first air supply / exhaust pipe or the second air supply / exhaust pipe, and the liquid in the tank is reversely flowed into the air diffuser from the air outlet to clean the air diffuser. Washing is repeated intermittently using the pulsation resulting from the change.

  With the configuration described above, a rapid inflow of the liquid in the tank is repeatedly generated because the cleaning state in which the liquid in the tank flowing into the diffuser pipe is discharged from the first or second air supply / exhaust pipe is intermittently generated by pulsation. Effectively cleans sludge adhering to the inside of the air diffuser.

  The sludge adhered to the inside of the air diffuser is dried by the air at the time of air diffusion, but the liquid in the tank infiltrates the sludge to promote the separation of the sludge, and the peeled sludge is exhausted with the liquid in the tank. At the same time, it is discharged from the exhaust port.

  Therefore, it is possible to utilize the pulsation caused by the liquid in the tank flowing back into the pipe by a simple operation of opening the valve once without repeating the operation of opening and closing the valve by manual operation or automatic operation. The diffusing tube cleaning of the diffusing device can be repeated.

  Further, the first and second valves are opened / closed to switch the first and second supply / exhaust pipes as conduits for venting to the diffusion pipe, and the third and fourth valves are opened / closed to exhaust from the diffuser pipe. The operation of switching between the first air supply / exhaust pipe and the second air supply / exhaust pipe as the pipe line to be performed and the operation of switching between the first exhaust port and the second exhaust port are performed at a constant cycle, so that the inside of the tank in the diffuser pipe is cleaned. Either the direction in which the liquid flows or any of the supply / exhaust pipes in which the liquid in the tank flows is switched at a constant cycle, and the cleaning effect by pulsation can be exerted on the diffuser pipe and the entire supply / exhaust pipes.

  As described above, according to the present invention, it is derived from the liquid in the tank flowing backward into the pipe by a simple operation of opening the valve once without repeating the operation of opening and closing the valve by manual operation or automatic operation. By using the pulsation that occurs, the diffuser cleaning of the diffuser can be repeated, and the cleaning effect is exerted on the entire diffuser by switching the direction in which the liquid in the tank flows in the diffuser at regular intervals. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, an aeration device 52 and a membrane separation device 53 disposed above the aeration device 52 are immersed in the aeration tank 51. The membrane separation device 53 is not essential for the aeration tank 51, but is used as a means for separating activated sludge in the membrane separation activated sludge method according to the present embodiment.

  The membrane separation device 53 can use various types of separation membranes such as organic flat membrane type, tube type, and ceramic type. Here, a plurality of membrane cartridges using organic flat membrane type separation membranes are vertically arranged. And arranged in parallel at a predetermined interval, and a flow path is formed between adjacent membrane cartridges. Each membrane cartridge communicates with a membrane permeate flow path (not shown) and operates with the water head (gravity) in the tank or the pump suction pressure as the driving pressure.

  The air diffuser 52 has an air diffuser case 54 surrounding a lower region of the membrane separation device 53 and an air diffuser 55 disposed below the air diffuser case 54. The air diffuser 55 has a predetermined diameter arranged in the horizontal direction. It consists of a main pipe 56 made of a large diameter pipe and a plurality of branch pipes 57 made of a small diameter pipe having a predetermined diameter arranged below the main pipe 56.

  A first air supply / exhaust pipe 58 and a second air supply / exhaust pipe 59 communicate with each of both side ends of the trunk pipe 56, and the base ends of the first air supply / exhaust pipe 58 and the second air supply / exhaust pipe 59 branch in two directions. The branched one communicates with the air supply source blower 60 via the first valve 61 and the second valve 62, and the other branched first air supply / exhaust pipe 58 communicates with the first valve 61 via the third valve 63. The other end of the second air supply / exhaust pipe 59 communicates with the second exhaust port 66 through the fourth valve 65.

The branch pipe 57 has an inverted T-shape and communicates with the main pipe 56 at one upper end, and both lower ends open as air jets 67 at positions below the main pipe 56.
In the present embodiment, the first exhaust port 64 and the second exhaust port 66 are opened under atmospheric pressure on the water surface. However, the first exhaust port 64 and the second exhaust port 66 may be disposed below the water surface. It is. The air diffusion case 54 is not shown in the figure but is fixed to the bottom of the tank. It is also possible to replace the first valve 61 and the third valve 63 with a single three-way valve, and replace the second valve 62 and the fourth valve 65 with a single three-way valve.

  Hereinafter, the operation of the above-described configuration will be described. During normal aeration operation, one of the first valve 61 and the second valve 62 is opened and the other is closed, and the third valve 63 and the fourth valve 65 are closed. In the following description, the first valve 61 is opened and the second valve 62, the third valve 63, and the fourth valve 65 are closed.

In this state, air supplied from the blower 60 flows into the main pipe 56 through the first air supply / exhaust pipe 58, and is ejected from the air outlet 67 of each branch pipe 57 into the liquid mixture in the aeration tank 51.
The diffused air aerates the mixed liquid in the tank, and the upward flow causes an upward flow of the solid-gas mixed phase. This upward flow stirs and mixes the mixed liquid in the tank, and supplies the mixed liquid in the tank to the flow path between the membrane cartridges of the membrane separation device 53 by crossflow. The membrane separation device 53 filters the mixed liquid in the tank through the filtration membrane of each membrane cartridge, and the upward flow flows as a sweep along the membrane surface, thereby suppressing the cake from adhering to the membrane surface of each membrane cartridge.

  During the cleaning operation, the fourth valve 65 is opened while air at a predetermined pressure is supplied from the blower 60 to the main pipe 56 through the first supply / exhaust pipe 58, and the air supplied to the main pipe 56 is supplied to the second supply / exhaust pipe 59. The air is exhausted from the second exhaust port 66 through the atmospheric pressure.

  At this time, the second exhaust port 66 is opened under atmospheric pressure at a position above the trunk pipe 56, and the air outlet 67 is opened at a position below the trunk pipe 56, so that the main flow of air in the trunk pipe 56 is The pressure (static pressure) acting on the trunk pipe 56 decreases toward the second exhaust port 66 having a smaller resistance, and is caused by the pressure difference from the pressure (determined by the water level in the tank) acting on the air outlet 67. Then, the mixed liquid in the tank flows back into the main pipe 56 through the branch pipe 57.

  The mixed liquid in the tank that has flowed in reversely washes and removes sludge adhering to the inside of the branch pipe 57 and the trunk pipe 56, and is discharged from the second exhaust port 66 through the second air supply / exhaust pipe 59 together with the air flowing through the trunk pipe 56. Is done. Sludge adhering to the inside of the branch pipe 57 and the trunk pipe 56 is dried by the air at the time of air diffusion, but peeling of the sludge is promoted by infiltration of the mixed liquid in the tank into the sludge.

  The balance between the liquid phase and the gas phase of the gas-liquid mixed phase flow in the second air supply / exhaust pipe 59 changes depending on the inflow amount of the liquid in the tank, and as the inflow amount increases, the liquid phase acts as a resistance. It becomes difficult to entrain the mixed liquid in the tank, and the mixed liquid in the tank staying in the second air supply / exhaust pipe 59 is increased and the exhaust is inhibited.

  The inhibition by the mixed liquid in the tank causes pulsation in the trunk pipe 56 and the second supply / exhaust pipe 59, and the mixed liquid in the tank flowing into the branch pipe 57 and the trunk pipe 56 from the air outlet 67 passes through the second supply / exhaust pipe 59. The cleaning state discharged from the second exhaust port 66 is repeated repeatedly and intermittently.

  The rapid inflow of the mixed liquid in the tank to the branch pipe 57 repeatedly causes the sludge adhering to the inside of the branch pipe 57 to be repeatedly washed without performing manual and control valve opening / closing operations repeatedly. And sludge can be effectively removed.

  However, in the above-described cleaning operation, the mixed liquid in the tank does not flow into the main pipe 56 upstream of the branch pipe 57a located on the most upstream side in the flow direction of the mixed liquid in the tank flowing through the main pipe 56, The cleaning effect is not effective.

  Therefore, the first valve 61 is closed, the second valve 62 is opened, the aeration operation is performed with the third valve 63 and the fourth valve 65 closed, and the second supply from the blower 60 is performed during the cleaning operation. The third valve 65 is opened in a state where air of a predetermined pressure is supplied to the main pipe 56 through the exhaust pipe 59, and the air supplied to the main pipe 56 is supplied from the first exhaust port 64 through the first supply / exhaust pipe 58 to the atmospheric pressure. The washing state in which the mixed liquid in the tank flowing into the branch pipe 57 and the trunk pipe 56 from the air outlet 67 is discharged from the first exhaust port 64 through the first air supply / exhaust pipe 58 is intermittently repeated by pulsation. Let it repeat. In this cleaning operation, the cleaning effect reaches the part where the mixed liquid in the tank did not flow in the previous cleaning operation, that is, the downstream side from the branch pipe 57a (upstream side in the previous cleaning operation).

  As described above, the operation of switching the first air supply / exhaust pipe 58 and the second air supply / exhaust pipe 59 as a conduit for ventilating the air diffusion pipe 55 by the opening / closing operation of the first valve 61 and the second valve 62, the third valve 63, An operation of switching the first air supply / exhaust pipe 58 and the second air supply / exhaust pipe 59 as a pipe line that exhausts from the diffuser pipe 55 by opening / closing the 4 valve 65, and an operation of switching the first exhaust port 64 and the second exhaust port 66. When the cleaning operation is performed at regular intervals, for example, every time the cleaning operation is performed, any of the supply / exhaust pipes 58 and 59 in which the mixed liquid in the tank flows and the mixed liquid in the tank flows in the diffusing pipe 55 during the cleaning is fixed. Thus, the cleaning effect by pulsation can be exerted on the diffuser pipe 55 and the entire supply / exhaust pipes 58 and 59.

  As shown in FIG. 2, the air diffusion pipe 55 can be formed in a loop shape, and the first air supply / exhaust pipe 58 and the second air supply / exhaust pipe 59 can be connected to an intermediate position.

It is a front view which shows the aeration apparatus in embodiment of this invention. It is a perspective view which shows the diffuser tube in other embodiment of this invention. It is a front view which shows the conventional diffuser.

Explanation of symbols

51 Aeration tank 52 Air diffuser 53 Membrane separation device 54 Air diffuser case 55 Air diffuser pipe 56 Trunk pipe 57 Branch pipe 58 First air supply / exhaust pipe 59 Second air supply / exhaust pipe 60 Blower 61 First valve 62 Second valve 63 Third valve 64 1st exhaust port 65 4th valve 66 2nd exhaust port 67 Air outlet

Claims (1)

A diffuser pipe which is immersed in the tank and arranged in the horizontal direction and provided with a plurality of air jets in the lower part, first and second supply / exhaust pipes communicating with each of both side ends of the diffuser pipe, and a first valve An air supply source that communicates with the first air supply / exhaust pipe via the second valve, and an air supply source that communicates with the first air supply / exhaust pipe via the third valve; And a second exhaust port communicating with the second air supply / exhaust pipe via the fourth valve, and a first air supply / exhaust pipe as a conduit for ventilating the diffuser pipe by opening and closing the first and second valves, and a second Switching between the supply and exhaust pipes, switching between the first and second supply and exhaust pipes as a conduit for exhausting from the diffuser pipe by opening and closing the third and fourth valves, and the first and second exhaust ports and the second exhaust The mouth is switched and exhausted through the first air supply / exhaust pipe or the second air supply / exhaust pipe while supplying air to the diffuser pipe In the tank, the liquid in the tank is caused to flow backward from the air outlet into the air diffuser to clean the air diffuser, and the cleaning is intermittently repeated using the pulsation caused by the pressure change in the air diffuser. Air diffuser to do.

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