JPS62213897A - Method and apparatus for aerating dam reservoir - Google Patents

Abstract

PURPOSE:To contrive to improve water quality, by forming a water lifting flow passage in a water area and sending air bubbles of compressed air into said flow passage from a lower area to dissolve and mix oxygen as much as possible. CONSTITUTION:An air bubble generator 2 of compressed air is arranged inside the lower part of a cylindrical air bubble tower 1a having a water introducing port 1a opened to a deep water layer at the lower end part thereof and a water introducing port 1b at the upper end part thereof. Compressed air is supplied to the air bubble generator 2 from a compressor C through a transfer hose T to generate and supply air bubbles. The length of the tower 1a is regulated corresponding to the depth of water to regulate the amount of air and an air bubble rising speed corresponding to the capacity of a water area and the compressor C is operated to send compressed air to the air bubble generator 2. Generated air bubbles have a fast rising speed and oxygen is sufficiently dissolved-in and mixed with the water present in the tower to enhance DO-concn. By this method, effective aeration is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aeration method and apparatus for use as a water quality conservation measure in dam reservoirs, lakes, etc.

As is well known, in dam reservoirs, etc., from spring to summer when the temperature rises, unlike in autumn and winter when convective circulation occurs naturally, the water area is divided into surface layer E, variable layer M, and deep water as shown in Figure 1. The stratification is fixed with layer H, and natural convective circulation throughout the water body does not occur. Therefore, during this period, the water in the deep water layer T1 no longer mixes with the water in the surface water layer E, and dissolved oxygen (Do > 11 degrees) decreases significantly, and in some cases progresses to zero, and the water at the bottom of the water. This leads to extremely undesirable situations such as the outflow of nutrients and the elution of harmful substances.

[Conventional technology]

Therefore, full-layer aeration devices have been provided as a water quality conservation measure of this type. For example, a bubble generator is installed in the underwater area, and air supplied from a land-based compressor is directly blown out to increase the DO1 degree of water in the deep water layer. This device usually generates air bubbles as small as possible in order to increase the contact area with water in order to facilitate the dissolution of air into water as much as possible.

[Problem that the invention seeks to solve]

However, on the other hand, bubbles with small diameters below a certain size have a slow rate of rise, so they are not able to force convection throughout the large volume of water in the dam reservoir pipe.
This method was limited to local oxygen supply, did not substantially improve water quality, and was extremely problematic.

In this respect, the aeration device according to the invention disclosed in Japanese Patent Publication No. 42-25987M provides an air reservoir in the pipe, and when a certain amount of air accumulates, the air mass rises inside the pipe at once, causing a siphon effect. This causes the water mass at the bottom to be sucked into the pipe, while also blowing it up.
Pump water up to the water surface and spread it horizontally on the water surface,
This forms a convection system, and can be said to be an intermittent aeration system that overcomes the drawbacks of the previous systems.

However, this device is extremely poor at dissolving and supplying oxygen directly to water; rather, it only causes forced convective circulation.
Since this method involves mixing water bodies, thereby destroying the stratification and supplying oxygen, there is a problem in that it takes a considerable amount of time to increase the DO concentration in the entire body of water such as a reservoir. Moreover, since this device forcibly mixes the water in the deep water layer with the surface water layer, the stratification is fixed and the DOI of the deep water layer is fixed.
After the water level reaches a low or zero level, water quality in the surface water layer will definitely be impaired, which is extremely undesirable.

Therefore, the purpose of this invention is to solve all of the above-mentioned problems by directly supplying oxygen to water in the deep water layer where the DOI level is low or zero. It is possible to locally increase the 0Ofa degree, and at the same time generate forced convection circulation sufficient to uniformly mix the entire predetermined water area, thereby dramatically improving the 001 degree temperature in the entire water body. The present invention is intended to provide an aeration method and apparatus.

[Means for solving problems]

In order to achieve the above object, the present invention constructs a pumping channel that is relatively long in the vertical direction and has a limited electric space in a predetermined water body, and connects the pumping channel from the lower area to the pumping channel. Compressed air bubbles with a relatively small diameter that can be dispersed and filled as much as possible are sent in, and in this pumping flow path, oxygen is dissolved and mixed as much as possible, and the buoyancy of the rising bubbles and the water mass are The buoyancy caused by the reduction in specific gravity generates an upward flow toward the upper region of the channel, and the water is continuously fed from the lower region to the upper region through the pumping channel, and is forced horizontally in the upper region. We adopted an aeration method for dams and reservoirs that is characterized by diffusion and forced circulation convection of metal bodies within a predetermined water area to increase the dissolved oxygen concentration in the entire water area. Furthermore, in carrying out the method invention, this invention includes a relatively long cylindrical bubble column having a water inlet opening into the deep water layer in the lower part and an outlet in the upper part; A compressed gas bubble generator is disposed inside or near the lower part of the cylindrical bubble column, and generates and supplies bubbles with a relatively small diameter to the water present in the column. Inside the tower, these bubbles rising in a dispersed state dissolve and mix oxygen into the water as much as possible, and at the same time generate an upward water flow toward the upper part of the bubble tower. An aeration device for a dam reservoir or the like is used, which is equipped with an impeller that forcibly diffuses water with a high dissolved oxygen concentration flowing out from the outlet in a circumferential direction and horizontally.

[Effect]

By adopting the above-mentioned configuration, this invention improves the Do concentration locally and instantly by dissolving the compressed gas in the form of relatively small-diameter air bubbles in the water of the deep water layer, and at the same time, the air bubbles in the pumping flow path As the bubbles rise in the tower, the water mass rises in a diffused state, and this upward flow flows out from the pumping channel to the outside, where it is diffused horizontally in the circumferential direction by a forced diffusion means such as an impeller. . This not only directly improves the water quality of water in the deep water layer where the Do concentration is low or zero, but also improves the DO concentration through forced convective circulation throughout the predetermined water body.

In particular, if the designated water area is a sub-layer water area, D.

The water mass in the surface water layer with high concentration is also sent to the deep water layer, and the Do concentration is increased synergistically.

Furthermore, if the predetermined water area is limited to the deep water layer, appropriate aeration can be performed without destroying the variable water layer at all.

〔Example〕

FIG. 1 is a schematic diagram showing an embodiment of an aeration apparatus used in carrying out the method according to the present invention, and shows the state of use when sublayer aeration is applied.

That is, 1 is a relatively long cylindrical bubble column having a water mass inlet 1a opening into the deep water layer H at the lower end and a water mass outlet 1b at the upper end. A compressed gas bubble generator 2 is disposed inside the lower part of the bubble column 1. This bubble generator 2 generates and supplies bubbles with a relatively small diameter to the water mass existing in the tower, and the compressed gas is sent from a compressor C installed on the ground via a transfer hose T. ing. On the other hand, 3 is a float provided on the upper part of this cylindrical bubble column, and is fixed vertically in the water body by the buoyancy balance with the anchor 4 attached to the lower part of the cylindrical bubble column. Further, reference numeral 5 denotes an impeller provided in the upper part of the bubble column, and is designed to rotate naturally by the upward flow of the water mass that rises in a diffused state inside the bubble column. Note that 6 is a bearing for the rotating shaft of the impeller 5.

Further, in this embodiment, the cylindrical bubble column 2 is configured as an expandable tube that can be expanded and contracted in the vertical direction, and a bellows structure 7 is disposed in the middle part of the bubble column as an expansion and contraction means.

Therefore, when using this aeration device for full-layer aeration, first adjust the pipe length according to the water depth, adjust the air volume and bubble rising speed according to the water area capacity, and then operate the compressor C. Compressed air, which is a compressed gas, is fed into the bubble generator 2 to generate bubbles under optimal conditions. Since these bubbles have a fast rising speed and a relatively small diameter, they can sufficiently dissolve and mix oxygen into the water mass existing in the tower, increasing the Do concentration, and due to the buoyancy force of the rising bubbles. Since the amount of air occupied inside the tower rises by an amount equivalent to the volume, and the specific gravity becomes lighter than that of the water mass outside the tower, a dramatic upward flow develops. Due to this upward flow, fresh air flows from the inlet 1a again.

Water with a low concentration in the deep water layer 1 is introduced, while water with a high Do concentration is discharged to the outside of the tower from the outlet 1b. The discharged water is forcefully dispersed horizontally in the circumferential direction by the rotating impeller 5. Therefore, due to these water flows, a convection system is generated throughout the water area from the deep water layer T1 to the surface water layer E, and water circulation is performed.

By the way, in this embodiment, the cylindrical bubble column is constructed with an expandable tube in order to adjust the tube length according to the water depth and also to be compatible with the deep water layer aeration type described later. It is not limited to. There is no problem in keeping the length of the pipe constant depending on the water depth of the reservoir, etc. Furthermore, in this embodiment, the rotational force of the impeller 5 is given by the water flow rising inside the tower, and the diffusion effect is exerted only by natural rotation, so to speak. It is only natural that it is okay to do so. It may be adopted as appropriate depending on the size of the water area, etc. Further, the means for fixing the entire apparatus is not limited to this embodiment which employs a float type, and various conventionally employed means may be used as appropriate.

By the way, the aeration device according to this embodiment can be applied not only to low-layer aeration but also to deep-water layer aeration. That is, as shown in FIG. 2, if the pipe length is adjusted according to the thickness of the deep water layer H, the length of the pipe can be reduced by 1q. In particular, in the case of deep-water layer aeration, the pipe length is shorter than in full-layer aeration, so the upward flow generated within the tower is reduced accordingly, and the impeller 5 also reduces the horizontal flow. Since the diffused air bubbles are dispersed, it is possible to directly supply oxygen to only the deep water layer without destroying not only the surface water layer E but also the variable water layer M. Convection circulation occurs and deep water layer aeration can be carried out extremely quickly. In addition, in the case of this type of aeration, in addition to the pipe length, the pipe diameter,
Deep aeration is carried out under optimal conditions by appropriately adjusting the bubble diameter, air size, or bubble rising speed generated from the bubble generator.

Therefore, by employing the aeration mechanism described above, it is fully possible to employ an aeration device that targets only the deep water layer.

〔Effect of the invention〕

As described above, this invention provides a function to directly or locally increase the DO concentration by supplying and dissolving compressed gas directly to the water mass in the deep water layer where the DO concentration is low or zero, and Because it simultaneously has the function of generating forced convective circulation sufficient to uniformly mix the DO, it has become possible to exhibit the effect of increasing the DO concentration synergistically and in an extremely short period of time throughout the entire water body. .

Therefore, the processing time and processing amount for the water mass in the deep water layer, which had been a problem unique to the conventional full-layer aeration type, are both satisfactorily satisfied at the same time. It does not cause any deterioration of water quality in the surface water layer by pumping water into the layer, and it also suppresses the accumulation of nutrients at the bottom, and provides extremely effective aeration. On the other hand, it can also be applied to deep water layer aeration, and has provided an extremely significant aeration method and apparatus that will contribute to this technical field.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the aeration device according to the present invention.
FIG. 2 is a schematic diagram showing a usage state when deep aeration is applied in the same embodiment. FIG. 2 is a schematic diagram showing a usage state when deep aeration is applied in the same embodiment.

Claims (9)

[Claims] (1) relatively long in the vertical direction within a given body of water;
and constructing a pumping channel having a limited fixed space, and feeding compressed air bubbles with a relatively small diameter into the pumping channel from a lower region so as to be able to disperse and fill the entire channel as much as possible,
In this pumping channel, oxygen is dissolved and mixed as much as possible, and the buoyant force of the rising bubbles and the buoyant force accompanying the light specific gravity of the water mass generate an upward flow toward the upper region of the channel, and the water is continuously delivered from the lower region to the upper region through the pumping channel, and is forcibly diffused horizontally in the upper region, causing forced circulation convection throughout the entire predetermined water area, and reducing the dissolved oxygen concentration in the entire water area. A method for aerating a dam reservoir, etc., characterized in that the aeration is increased. (2) The method for aerating a dam reservoir, etc., according to claim 1, wherein the pumping channel is relatively long beyond the variable water layer and has a limited fixed space. (3) The aeration method according to claim 1, wherein the hot water flow path is relatively long and has a limited fixed space within a range that does not exceed the variable water layer. (4) Has a water inlet opening into the deep water layer in the lower part,
A cylindrical bubble column with a relatively long tube length and an outlet in the upper part, and bubbles that are arranged inside or near the lower part of the cylindrical bubble column and have a relatively small diameter relative to the water present in the column. It has a compressed gas bubble generator that generates and supplies
Inside the cylindrical bubble column, these bubbles rising in a dispersed state dissolve and mix oxygen into the water as much as possible, and at the same time generate an upward water flow toward the upper part of the bubble column. An aeration device for a dam reservoir, etc., characterized in that it is provided with an impeller that horizontally and forcefully diffuses water with a high dissolved oxygen concentration flowing out from the outlet in an upward flow in a circumferential direction. (5) The aeration device for a dam reservoir or the like according to claim 4, wherein the cylindrical bubble column has a relatively long pipe length that extends beyond the variable water layer. (6) The aeration device for a dam reservoir or the like according to claim 4, wherein the cylindrical bubble column has a relatively long pipe length that does not exceed the variable water layer. (7) The aeration device for a dam reservoir or the like according to claim 4, wherein the cylindrical bubble column is an expandable tube that can be expanded and contracted in the vertical direction. (8) An aeration device for a dam reservoir or the like according to claim 4, 5, 6, or 7, in which the impeller is rotated by a rising water flow. (9) An aeration device for a dam reservoir or the like according to claim 4, 5, 6, or 7, in which the impeller is forcibly rotated by motor drive.