RU2151634C1 - Water aerator - Google Patents

Abstract

FIELD: devices for saturation of water with air; flotation plants for sewage treatment. SUBSTANCE: proposed device includes pump, upper supply pipe line and lower discharge pipe line and air supply pipe line, flow divider and pressure-reducing valve; pressure pipe is mounted vertically and is connected to discharge pipe line by its upper; its lower part is connected to pressure-reducing valve; flow divider is mounted inside pressure pipe; air supply pipe line is made in form of capillary tube. Pressure-reducing valve consists of two disks forming radial slot. Outlet of pressure-reducing valve may be connected with gas- and-liquid separator. EFFECT: increased concentration of air bubbles in water; reduced sizes; enhanced stability of operation. 3 cl, 3 dwg

Description

 The invention relates to a device for saturating water with air and can be used, for example, as part of a flotation plant for wastewater treatment.

 There are various designs of water aerators. Some of them are based on the atomization of air in water in the form of small bubbles through the use of various kinds of fibrous-porous bodies (see, for example, RF patent N 2048456, class C 02 F 1/74, 3/02, publ. 20.11. 95). In such structures, the typical size of the bubbles is usually from 2 to 5 mm, which does not provide high quality of the flotator due to the small surface of the bubbles and their high ascent rate (about 0.2 m / s).

 Other aeration devices are based on preliminary dissolution of air in water at a pressure of 0.3-1.0 MPa and subsequent decompression of water, as a result of which air is released from the supersaturated solution in the form of small bubbles with a diameter of 50-100 microns. Such devices contain a pressure tank, a pressure reducing valve, and a pump (see, for example, the book A. Kopylov, Wastewater treatment and compaction of pulp and paper sludge. M., 1983, p. 42). The disadvantage of these devices is the need to use pressure tanks of large volume and the inability to obtain bubbles with a diameter of less than 50 microns.

 Closest to the proposed technical solution, selected as a prototype, is a device for water aeration, used as part of a flotation unit (see A. Kopylov’s book "Wastewater treatment and compaction of sludge from pulp and paper production", M., 1983, p.24). It contains a pump supplying the lower and upper discharge pipes and the air supply pipe.

 The device operates as follows. The water to be saturated in the supply pipe is mixed with the air pumped through the supply pipe. The water-air mixture is emulsified in the impeller of the pump and enters the discharge pipe.

 However, the known device has significant disadvantages. The main ones are the low concentration of dissolved air, because only a small part of the air dissolves in water due to the short contact time of air bubbles with water and relatively low pressure, as well as the unstable operation of the device due to air separation in the inlet and outlet pipes and the ingress of a large amount of air into the impeller of the pump.

 The problem solved by the invention is the improvement of the device for aeration of water.

 The technical result from the use of the invention is to increase the concentration of air bubbles in water, reduce their size and increase the stability of the device.

 This result is achieved in that the device for aeration of water, consisting of a pump supplying the lower and outlet upper pipelines and the air supply pipe, is equipped with a pressure pipe, a flow divider and a pressure reducing valve, and the pressure pipe is installed vertically and connected with its upper part to the discharge pipe, the lower part is connected to the pressure reducing valve, the flow divider is installed inside the pressure pipe, and the air supply pipe is made in the form of a capillary tube. The pressure reducing valve is made in the form of two disks forming a radial gap. The outlet of the pressure reducing valve can be connected to a gas-liquid separator.

 In FIG. 1 shows a water aeration device; in FIG. 2 - flow divider; in FIG. 3 - pressure reducing valve.

 The device comprises a high pressure pump 1, for example, of a plunger type, the inlet of which is connected to a water tank 2, a lower supply pipe 3 and an air supply pipe 4, made in the form of a capillary tube with a diameter of less than 1 mm, with a compressor 5. The output of the pump 1, located above its inlet, is connected by the outlet upper pipe 6 to the upper part of the pressure pipe 7. The pressure pipe 7 is installed vertically, a flow divider 8 is installed inside it in the upper half, the lower part of the pressure pipe 7 is connected to the reduction a valve 9 containing a throttle 10 and made in the form of two disks 11, 12 forming a radial slot 13. If necessary, the output of the pressure reducing valve 9 can be connected to a gas-liquid separator 14. The flow divider 8 is made in the form of a cone with holes 15 (Fig. 2 )

 The device operates as follows. Water from the water tank 2 under a pressure of 0.2-0.6 MPa is supplied to the inlet of the high pressure pump 1. Pump 1 is installed so that the pump inlet is below its outlet. The air from the compressor 5 under a pressure of 0.1-0.2 MPa higher than the pressure of the water in the water tank 2, is supplied through the capillary tube 4 (its length regulates the hydraulic resistance and, therefore, the air supply) to the lower supply pipe 3 of the pump 1. General volumetric air flow should not exceed 1.5-2.0% of the water flow, which ensures the stability of the pump. Next, the flow of the water-air mixture at a pressure of 3.0-10.0 MPa through the outlet upper pipe 6 is supplied to the upper part of the pressure pipe 7. Inside the pressure pipe, a flow divider 8 is installed, which ensures equalization of the flow along its cross section, as well as additional dispersion of the flow. Water passing through the pressure pipe 7 completely dissolves the incoming air in a time of not more than 10 seconds. This is due to the increased pressure in it, 5-15 times higher than the traditional, as well as intensive spraying and mixing of water and air in the pressure pipe 7.

 Then, a stream of water with dissolved air passes through the throttle 10 of the pressure reducing valve 9, where small air bubbles with a diameter of 10-20 μm are released. In traditional designs with a pressure in the saturator of 0.3-0.7 MPa, the diameter of the bubbles is at least 50-100 microns. To maintain a high pressure inside the pressure pipe 7, it is necessary to use a throttle of a very small diameter of about 1 mm, so the water flow velocity in the throttle opening reaches 100 m / s or more. This leads, firstly, to the formation of bubbles of 10-20 μm in diameter, which is favorable for flotation processes, and, secondly, to strong coalescence of the bubbles due to the dynamic separation of the gas-liquid flow, which reduces the efficiency of the device.

 To eliminate or reduce this negative factor, the pressure reducing valve 9 is made in the form of two disks 11 and 12, forming a radial slot 13 and lowering the flow rate by tens of times.

 To remove large bubbles resulting from residual coalescence, for example, due to non-optimal carrying out of the process or other reasons, a separator 14 is installed at the output of the device. A stream of water containing bubbles of various diameters enters the upper part of the separator and then leaves through its drain pipe lower part. Small bubbles are carried away by the flow, and large ones with a diameter of more than 2 mm accumulate in the upper part of the separator, forming a gas cavity, which gradually displaces water from the separator. As soon as the water level reaches the set minimum, the excess air relief valve opens. Thus, the production of water saturated with very small bubbles is ensured, which increases the stability of the device and allows you to effectively float particles in systems of flotation or water purification.

Claims (3)

 1. Water aeration device for a flotation plant, consisting of a pump, supplying the lower and exhaust upper pipelines and the air supply pipe, characterized in that it is equipped with a pressure pipe, a flow divider and a pressure reducing valve, the pressure pipe being installed vertically and connected with its upper part to the discharge pipe, the lower part to the pressure reducing valve, a flow divider is installed inside the pressure pipe, and the air supply pipe is made in the form of a capillary tube.  2. The device according to claim 1, characterized in that the pressure reducing valve is made in the form of two disks forming a radial gap.  3. The device according to claim 1, characterized in that the outlet of the pressure reducing valve is connected to a gas-liquid separator.

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