JP2013192977A - Sodium hypochlorite injection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sodium hypochlorite injection apparatus which in spite of being simple in structure can prevent irregular variation of the amount of sodium hypochlorite injected and can therefore perform the injection of sodium hypochlorite into an injection site with good accuracy.SOLUTION: A sodium hypochlorite injection apparatus 1 includes a tank 2 for storing sodium hypochlorite, a pump 3 which sucks sodium hypochlorite from the tank 2 and delivers it, and a transport pipe 4 which is connected to the delivery port 3b of the pump 3, transports the sodium hypochlorite to an injection site, and releases it. The relationship between the inside diameter D of the delivery port 3b of the pump 3 and the inside diameter d of the transport pipe 4 satisfy the requirement of formula (1): 0.25D≤d<D.

Description

  The present invention is also referred to as a sodium hypochlorite injecting device (hereinafter referred to as “hypo-injecting device”) that injects sodium hypochlorite (hereinafter also referred to as “hypoa”) into water to be purified at a water purification plant or the like. )

  In water purification plants, sub-a is indispensable to make it easier to remove unnecessary components contained in raw water and to disinfect water. Hya is mainly injected into the landing well, and is also injected at the exit of the sedimentation basin and in front of the water purification pond. Sub-injection to such an injection point is performed by a hypo-injection apparatus.

  FIG. 1 is a diagram schematically showing a configuration of a conventional sodium hypochlorite injection device. As shown in the figure, a hypochlorous injection device 101 includes a tank 2 that stores hypochlorous acid, a pump 3 that is a power source for sending the hypochlorous in the tank 2 to an injection point A, and a hypoxia from the pump 3. And a transportation pipe 4 for transporting and discharging the fuel to the injection point A. FIG. 1 shows an example in which the injection point A is a landing well.

  An inlet pipe 5 from the tank 2 is connected to the suction port 3 a of the pump 3, and a transport pipe 4 having the same inner diameter as that of the discharge port 3 b is connected to the discharge port 3 b of the pump 3. As the pump 3, a reciprocating pump such as a diaphragm pump or a rotary pump such as a uniaxial eccentric screw pump is used. The transport pipe 4 is laid from the pump 3 to the injection point A. Normally, in the water purification plant, the tank 2 and the pump 3 are installed together in the management building B, and the injection point A is installed in a place far from the management building B. For this reason, the transport piping 4 tends to be long, and the total length thereof often exceeds 100 m.

  By driving the pump 3, the hypochlorite in the tank 2 is sucked into the pump 3 from the suction port 3 a of the pump 3 through the introduction pipe 5 and discharged from the discharge port 3 b of the pump 3 to the transport pipe 4. The next discharge discharged from the pump 3 is transported through the transport pipe 4, discharged from the outlet 4 b of the transport pipe 4, and injected into the injection point A.

  By the way, hypochlorous has the property of being easily decomposed to generate gas (oxygen). Due to this property, gas may be generated in the path in the process of flowing through the pump 3 and further in the process of flowing through the transport pipe 4. In this case, the sub-injection apparatus 101 irregularly changes the injection amount of sub-aqueous discharged from the outlet 4b of the transport pipe 4 due to the influence of the generated gas, so that the sub-injection to the injection point A is accurate. I can't do it well.

  Here, in the hypo-injection apparatus 101 using the reciprocating pump as the pump 3, if gas is contained in the sub-circulation flowing through the pump 3, the pump 3 is gas-locked, and stable sub-injection is prevented. . In order to solve this problem, in a reciprocating pump, when gas is mixed or generated in the liquid flowing through the internal path, pressure is applied to the internal path and the gas is forcibly discharged downstream of the path. There is a gas discharge mechanism that prevents the occurrence of gas lock by this gas discharge mechanism (see, for example, Patent Document 1).

  On the other hand, the uniaxial eccentric screw pump is useful as the pump 3 of the hypo-injection apparatus 101 because the structure does not cause gas lock. In the hypoinjection device 101 using the uniaxial eccentric screw pump, as shown in FIG. 1, a flow meter 6 for pump control is provided in the vicinity of the inlet 4 a of the transport pipe 4 (near the outlet 3 b of the pump 3). Is provided, and a controller (not shown) sequentially adjusts the driving of the pump 3 based on the measurement value of the flow meter 6 and feedback-controls the amount of injection of the sublimation (see, for example, Patent Document 2).

JP 2003-65243 A JP 2009-235976 A

  However, the irregular fluctuation of the hypoinjection amount described above still occurs regardless of the type of the pump 3. From this, it can be said that the irregular fluctuation of the hypochlorous injection amount is caused by the generation of gas in the process in which the hypoxia flows through the transport pipe 4. For this reason, in the hypo-injection apparatus, in order to prevent irregular fluctuations in the hypo-injection amount and to carry out the sub-injection to the injection point A with high accuracy, in the process where the hypo-circulation flows through the transport pipe 4. Establishment of technology that can suppress the generation of gas is strongly desired.

  In response to this requirement, the simplest is that the total length of the transport pipe 4 is short. This is because, when the total length of the transport pipe 4 is short, Hya is released from the transport pipe 4 before generating gas in the process of flowing through the transport pipe 4. However, in order to realize this, it is necessary to install the pump 3 near the injection point A, the number of buildings that accommodate the tank 2 together with the pump 3 increases, and the management of the pump 3 and the tank 2 becomes complicated. For this reason, shortening the overall length of the transport pipe 4 is not practical.

  In addition, it is conceivable to cover the transport pipe 4 with a heat insulating material such as a heat insulating material or a cooling jacket, and to secure the temperature of the hypoxia flowing through the transport pipe 4 at a low temperature. This is because, when the temperature of hypochlorous is low, decomposition of hypochlorous is suppressed and generation of gas is suppressed. However, in order to realize this, it is necessary to cover the transport pipe 4, which tends to be long in the first place, with a cold insulating material over the entire length, and it cannot be denied that enormous costs are required. For this reason, it is not realistic to cover the transport pipe 4 with a cold insulating material.

  The present invention has been made in view of the above problems, and has a simple configuration, prevents irregular fluctuations in the hypochlorous injection amount, and performs hypochlorous acid that can accurately inject hypochlorous acid into the injection point. An object is to provide a sodium injection device.

  In order to achieve the above-mentioned object, the inventors conducted a sub-injection test of the actual machine under various conditions to investigate the temporal behavior of the sub-injection amount, as shown in the examples described later, and conducted intensive studies. Repeated. As a result, the knowledge shown in the following (a) and (b) was obtained.

  (A) By simply adopting a transport pipe having an inner diameter smaller than the inner diameter of the pump discharge port, the flow rate of the sub-aqueous flowing through the transport pipe becomes faster than the flow rate of the sub-flow flowing through the pump discharge port. Irregular fluctuations in the injection quantity of the hypochlorous discharged from the transportation pipe can be prevented. However, if the inner diameter of the transport pipe is remarkably smaller than the inner diameter of the pump discharge port, an irregular variation of the sub-injection amount occurs.

  (B) By installing a back pressure valve or a gas vent pipe in the transport pipe, it is possible to expect irregular fluctuations in the hypoinjection amount.

The present invention has been completed based on the above findings (a) and (b), and the gist thereof is the following sodium hypochlorite injection device. In other words, a hypochlorous comprising a tank for storing hypochlorous, a pump that sucks and discharges hypochlorous in the tank, and a transport pipe that is connected to the discharge port of the pump and transports and discharges hypoxia to the injection point. A hypo-injection device in which the relationship between the inner diameter D of the discharge port of the pump and the inner diameter d of the transport pipe satisfies the condition of the following expression (1).
0.25D ≦ d <D (1)

In the hypochlorous injection device, the relationship between the flow velocity V of sodium hypochlorite flowing through the discharge port of the pump and the flow velocity v of sodium hypochlorite flowing through the inside of the transport pipe is expressed by the following equation (2): It is preferable to satisfy the following conditions.
V <v ≦ 10V (2)

  In addition, the hypo-injection apparatus can be configured such that a back pressure valve is provided in a path near the outlet of the transport pipe.

  Further, the hypo-injection apparatus can be configured such that a gas vent pipe is connected to the route of the transport pipe.

  And in said hypo-injection apparatus, it is preferable that the said pump is a uniaxial eccentric screw pump.

  According to the hypo-injection apparatus of the present invention, by simply adopting the transport pipe satisfying the above formula (1), irregular fluctuations in the hypo-injection amount can be prevented, and the hypo- Can be accurately injected.

It is a figure which shows typically the structure of the conventional sodium hypochlorite injection apparatus. It is a figure which shows typically the structure of the sodium hypochlorite injection apparatus which is 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the uniaxial eccentric screw pump which is an example of the pump used for the sodium hypochlorite injection apparatus of this invention. It is a figure which shows typically the structure of the sodium hypochlorite injection apparatus which is 2nd Embodiment of this invention. It is a figure which shows typically the structure of the sodium hypochlorite injection apparatus which is 3rd Embodiment of this invention. Test No. in Examples It is a figure which shows the time-dependent behavior of the hypoinjection amount as a test result of 1. Test No. in Examples It is a figure which shows the time-dependent behavior of the hypoinjection amount as a test result of 2. Test No. in Examples FIG. 6 is a diagram showing the temporal behavior of the hypoinjection amount as a test result of 3. Test No. in Examples FIG. 4 is a diagram showing the temporal behavior of the hypoinjection amount as a test result of FIG. Test No. in Examples FIG. 5 is a diagram showing the temporal behavior of the hypoinjection amount as a test result of FIG. Test No. in Examples FIG. 6 is a diagram showing the temporal behavior of the hypoinjection amount as a test result of FIG. Test No. in Examples FIG. 7 is a diagram showing the temporal behavior of the hypoinjection amount as a test result of FIG.

  Below, the embodiment is explained in full detail about the sodium hypochlorite injection device of the present invention.

<First Embodiment>
FIG. 2 is a diagram schematically showing the configuration of the sodium hypochlorite injection device according to the first embodiment of the present invention. The first sub-injection apparatus 1 of the first embodiment shown in the figure is based on the configuration of the conventional sub-injection apparatus 101 shown in FIG. 1, and the same components are denoted by the same reference numerals, and overlapping explanations are omitted. Omitted as appropriate.

  As shown in FIG. 2, the hypo-injection apparatus 1 of the present embodiment includes a tank 2, a pump 3, and a transport pipe 4, and an inlet pipe 5 from the tank 2 is connected to a suction port 3 a of the pump 3. A transport pipe 4 is connected to the three discharge ports 3b. The tank 2 and the pump 3 are collectively installed in the management building B, and the transport pipe 4 is laid from the pump 3 to the injection point A.

In this embodiment, the transport pipe 4 connected to the discharge port 3b of the pump 3 is such that the relationship between the inner diameter D of the discharge port 3b of the pump 3 and the inner diameter d of the transport pipe 4 satisfies the condition of the following expression (1). Is adopted.
0.25D ≦ d <D (1)

  The reason for prescribing the condition of the above formula (1) is as follows.

  When the inner diameter d of the transport pipe 4 is a condition of d <D, that is, a condition that is smaller than the inner diameter D of the discharge port 3b of the pump 3, the sub-flow velocity v flowing inside the transport pipe 4 is It becomes faster than the sub-flow velocity V flowing through the outlet 3b. Thereby, the hypo discharge discharged from the pump 3 circulates in the transport pipe 4 at a higher speed and is discharged from the transport pipe 4 at an earlier stage than in the case of the conventional hypo-injection apparatus 101 shown in FIG. For this reason, even if Hya is released from the transport pipe 4 before generating the gas in the process of flowing through the transport pipe 4, and the gas is generated in the transport pipe 4, the generated gas is in a fine bubble state. It is sent out as it is. For this reason, the injection quantity of the hypochlorous discharged from the outlet 4b of the transport pipe 4 is stabilized without fluctuating irregularly. Moreover, when the instructed injection amount is changed as necessary, the sub-injection amount discharged from the transport pipe 4 follows the changed instruction injection amount in a timely manner.

  Therefore, if the inner diameter d of the transport pipe 4 satisfies the condition of d <D, it is possible to suppress the generation of gas in the process of the flow of the sub-flow through the transport pipe 4, and as a result, Irregular fluctuations can be prevented, and the next sub-injection to the injection point A can be performed with high accuracy. In order to suppress the generation of gas more effectively, d ≦ 0.8D, and more preferably d ≦ 0.6D.

  However, the inner diameter d of the transport pipe 4 is not necessarily small. If the inner diameter d of the transport pipe 4 is significantly smaller than the inner diameter D of the discharge port 3b of the pump 3, the flow velocity v of the secondary flow flowing inside the transport pipe 4 becomes too fast. Fluctuations occur. Therefore, in order to prevent irregular fluctuations in the amount of hypochlorous injection occurring as the flow velocity v of the sub-arc in the transport pipe 4 becomes excessive, the inner diameter d of the transport pipe 4 is 0.25D ≦ d. Satisfy the conditions. More preferably, 0.35D ≦ d, and still more preferably 0.4D ≦ d.

  The type of the transport pipe 4 is not particularly limited except that the inner surface of the transport pipe 4 reacts with the sub-corrosion and corrodes because the transport target is the sub-hya. For example, an HIV pipe (hard vinyl chloride pipe) is suitable. A so-called blade hose that is lightweight, has high pressure resistance and is flexible is also suitable.

  In addition, the transport pipe 4 usually has several bent elbow parts on the route to the injection point A. Generally, pressure loss occurs in the elbow part, and the pressure loss tends to increase according to the number of elbow parts installed. For this reason, it is speculated that the number of elbows installed may affect the condition of the above equation (1), but the normal number of installations hardly affects the condition of the above equation (1).

Corresponding to the above-mentioned regulation (condition (1)) regarding the inner diameter D of the discharge port 3b of the pump 3 and the inner diameter d of the transport pipe 4, the sub-flow velocity V flowing through the discharge port 3b of the pump 3 and the transport pipe 4 It is preferable that the relationship between the flow velocity v of the sub-flow flowing through the inside satisfies the condition of the following formula (2).
V <v ≦ 10V (2)

  If the sub-flow velocity v in the transport pipe 4 satisfies the condition of V <v, the generation of gas in the flow process will be suppressed as the sub-stream flows through the transport pipe 4 at high speed. As a result, it is possible to prevent irregular fluctuations in the hypochlorous injection amount, and to perform the sublimation injection into the pouring point A with high accuracy. For this reason, it is preferable that the sub-flow velocity v in the transport pipe 4 satisfies the condition of V <v. More preferably, 1.5V ≦ v, and still more preferably 2.5V ≦ v.

  On the other hand, if the sub-flow velocity v in the transport pipe 4 satisfies the condition of v ≦ 10 V, it is possible to prevent irregular fluctuations in the hypo-injection amount that occurs as the flow velocity v becomes excessive. This is because it is possible to perform the next-subject injection to the injection point A with high accuracy. For this reason, it is preferable that the sub-flow velocity v in the transport pipe 4 satisfies the condition of v ≦ 10V. More preferably, v ≦ 8V, and further preferably v ≦ 6V.

  In the present embodiment, it is assumed that a uniaxial eccentric screw pump is used as the pump 3, and a flow meter 6 for pump control is provided in the path near the outlet 4 b of the transport pipe 4 (near the injection point A). Yes. With this flow meter 6, the sub-amount of flow flowing in the vicinity of the outlet 4 b of the transport pipe 4 is sequentially measured. The measurement value obtained by the flow meter 6 corresponds to the injection amount of hypochlorous discharged from the outlet 4 b of the transport pipe 4. And based on the measured value by the flowmeter 6, the controller which is not illustrated adjusts the drive of the pump 3 sequentially and feedback-controls the amount of hypo-subsequent injection. As a result, in the hypo-injection apparatus 1 of the present embodiment, the flow meter 6 for pump control is in the vicinity of the inlet 4a of the transport pipe 4 (the discharge port of the pump 3), like the hypo-injection apparatus 101 shown in FIG. The sub-injection amount can be feedback-controlled more accurately than that provided in the path 3b).

  In the present embodiment, the flow meter 7 is also provided in the route in the vicinity of the inlet 4 a of the transport pipe 4. The flow meter 7 measures the sub-injection quantity discharged from the pump 3 in the vicinity of the discharge port 3b of the pump 3 for monitoring, and the measured value by the flow meter 7 It is not used for feedback control. But the feedback control of the pump 3 may use the measured value by either of the flow meters 6 and 7.

  The hypo-injection apparatus 1 of the present embodiment can use a reciprocating pump such as a diaphragm pump in addition to a rotary pump such as a uniaxial eccentric screw pump as the pump 3. When using a reciprocating pump, it is common not to install the flow meter 6 for pump control.

  FIG. 3 is a longitudinal sectional view of a uniaxial eccentric screw pump which is an example of a pump used in the sodium hypochlorite injection device of the present invention. As shown in the figure, the pump 3 is a uniaxial eccentric screw pump and includes a male screw rotor 31 and a female screw stator 32. The rotor 31 has a true circular cross section and is formed in a spiral shape with a single thread. The stator 32 has an inner hole 32a through which the rotor 31 is inserted. A double thread having a pitch twice that of the rotor 31 is formed in the inner hole 32a, and the inner hole 32a has an oval cross section. The rotor 31 is arranged eccentrically from the central axis of the inner hole 32a of the stator 32, and rotation power is transmitted from a main shaft 51 of a motor, which will be described later, thereby centering on the central axis of the inner hole 32a of the stator 32. Rotates while revolving.

  The outer periphery of the stator 32 is held by an outer cylinder 33. At the front end of the outer cylinder 33, an endstat 34 serving as a discharge port 3b is attached. A transport pipe 4 having an inner diameter d that satisfies the condition of the above-described expression (1) is connected to the front end of the endstat 34. A cylindrical front housing 35 is attached to the rear end of the outer cylinder 33 of the stator 32, and a bottomed cylindrical rear housing 36 is attached to the rear end of the front housing 35. Near the rear end of the front housing 35, a suction pipe 35a serving as a suction port 3a protrudes. The suction pipe 35a is connected to the introduction pipe 5 (see FIG. 2) from the tank 2 described above.

  Here, the uniaxial eccentric screw pump 3 shown in FIG. 3 is a magnet coupling pump that transmits power from the motor to the rotor 31 by magnetism. For this reason, it has the following configuration.

  A motor (not shown) is disposed behind the rear housing 36. This motor is fixed to the front housing 35 or the rear housing 36, and has a main shaft 51 on the central axis of the inner hole 32 a of the stator 32. A cylindrical driving side magnet holding member 52 surrounding the rear housing 36 is attached to the main shaft 51 of the motor. A driving magnet 53 is joined to the inner periphery of the driving magnet holding member 52 so as to face the outer peripheral surface of the rear housing 36.

  A cylindrical driven magnet holding member 42 is accommodated in the rear housing 36. A driven magnet 43 is embedded in the outer periphery of the driven magnet holding member 42 so as to face the driving magnet 53. A drive shaft 38 as a driven shaft is coupled to the axial center portion of the driven magnet holding member 42. The drive shaft 38 extends to the vicinity of the rear end of the front housing 35, and has a flange portion 38a at the front end thereof. A coupling rod 40 is connected to the flange portion 38a via a universal joint 39 such as a universal joint. The male threaded rotor 31 is connected to the coupling rod 40 via a universal joint 41 such as a universal joint. ing.

  The drive shaft 38 is rotatably supported at its front end side by a plain bearing housing 37. The plain bearing housing 37 is sandwiched between the front housing 35 and the rear housing 36 so as to partition the insides of the front housing 35 and the rear housing 36.

  In the magnet coupling type uniaxial eccentric screw pump 3 shown in FIG. 3 having such a configuration, the drive-side magnet holding member 52 rotates integrally with the main shaft 51 of the motor. Along with this, the driven magnet holding member 42 rotates synchronously by the action of the magnetic attractive force of the driving magnet 53 and the driven magnet 43, and the drive shaft 38 rotates integrally therewith. As a result, the male threaded rotor 31 connected to the drive shaft 38 via the universal joint 39, the coupling rod 40 and the universal joint 41 revolves around the central axis of the inner hole 32a of the female threaded stator 32 while rotating. To do. In this way, the space formed between the rotor 31 and the inner hole 32a of the stator 32 is sequentially fed out from the rear end to the front end of the stator 32. As a result, the sub-arc is introduced into the front housing 35 from the suction port 3a. While being sucked in, the sucked hypoxia is discharged from the discharge port 3b.

  The magnetic coupling type uniaxial eccentric screw pump 3 can discharge a constant amount of fluid continuously without pulsation, and can completely enclose the fluid by the rear housing 36. Is particularly suitable.

  In the uniaxial eccentric screw pump 3 shown in FIG. 3, the transport pipe 4 is connected to the endstat 34, and the introduction pipe 5 from the tank 2 is connected to the suction pipe 35 a of the front housing 35. On the contrary, the transport pipe 4 may be connected to the suction pipe 35 a and the introduction pipe 5 may be connected to the endstat 34. This is because if the main shaft 51 of the motor is rotated in the reverse direction, it is possible to suck in the hypochlorous from the endstat 34 and discharge the sucked hypochlorous acid into the transport pipe 4 from the suction pipe 35a.

Second Embodiment
FIG. 4 is a diagram schematically showing a configuration of a sodium hypochlorite injection device according to the second embodiment of the present invention. The sub-injection apparatus 1 of the second embodiment shown in the figure is different from the sub-injection apparatus 1 of the first embodiment shown in FIG. 2 in the following points.

  As shown in FIG. 4, in the hypo-injection apparatus 1 of the present embodiment, a back pressure valve 8 is provided in the path near the outlet 4 b of the transport pipe 4 (side the injection point A). The back pressure valve 8 plays a role of keeping the secondary pressure flowing through the transport pipe 4 at a constant pressure (for example, 0.1 MPa as a gauge pressure) over the entire upstream side of the back pressure valve 8. Thereby, since the pressure in the transport pipe 4 constantly increases to a constant pressure, the generation of gas in the transport pipe 4 is suppressed. For this reason, suppression of irregular fluctuations in the hypo-injection amount can be greatly expected.

  However, in the hypo-injection apparatus 1 of the present embodiment, when the instructed injection amount is changed, a response delay of the sub-injection amount actually discharged from the transport pipe 4 occurs with respect to the instructed injection amount. There is an inconvenience that the followability of the actual hypo-injection amount is inferior. This is due to the fact that when the sub-a contains gas in the transport pipe 4, the sub-a appears to be a compressible fluid and blunts the opening / closing operation of the back pressure valve 8.

<Third Embodiment>
FIG. 5 is a diagram schematically showing a configuration of a sodium hypochlorite injection device according to the third embodiment of the present invention. The sub-injection apparatus 1 of the third embodiment shown in the figure is different from the sub-injection apparatus 1 of the first embodiment shown in FIG. 2 in the following points.

  As shown in FIG. 5, in the hypo-injection apparatus 1 of the present embodiment, a gas vent pipe 9 is provided in the route of the transport pipe 4. The gas vent pipe 9 is open to the atmosphere and plays a role of discharging the gas in the transport pipe 4 out of the path. As a result, even if gas is generated in the transport pipe 4 and the gas is contained in the secondary pipe in the transport pipe 4 along with this, the gas passes through the gas vent pipe 9 to the transport pipe 4. It is discharged out of the route. For this reason, suppression of the irregular fluctuation | variation of a hypochlorous injection amount is expectable not a little.

  Although the installation position of the degassing pipe 9 is not particularly limited, as shown in FIG. 5, the vicinity of the outlet 4b of the transport pipe 4 (side the injection point A) is preferable. This is because if gas is generated in the transport pipe 4, the gas gradually increases toward the downstream side of the path. Moreover, if the gas vent pipe 9 is installed downstream of the path, there is an advantage that the height of the gas vent pipe 9 can be lowered. This is because if the gas vent pipe 9 is installed on the upstream side of the path, it is necessary to install a gas vent pipe 9 having a long height in anticipation of the pipe resistance.

  However, in the hypo-injection apparatus 1 of the present embodiment, there is a possibility that irregular fluctuations in the hypo-injection amount cannot be effectively suppressed only by installing one gas vent pipe 9. Since the gas flowing in the transport pipe 4 is a part of the sub-a, while the gas is exhausted in the gas vent pipe 9, the flow rate of the sub-arc in the transport pipe 4 after the gas vent pipe 9 is This is because the gas volume decreases. For this reason, it is preferable to install a plurality of gas vent pipes 9.

  However, when a plurality of gas vent pipes 9 are installed, there is a disadvantage that the cost required for the installation increases. Further, since the gas vent pipe 9 is open to the atmosphere due to its function, if the transport pipe 4 downstream of the gas vent pipe 9 is clogged or a valve operation error (fully closed) occurs, the gas vent pipe 9 Nexta is overflowing. Since the next liquid is a dangerous liquid, it is common to take measures such as returning the gas vent pipe 9 to a place where it does not become a problem even if it overflows (for example, the tank 2) or installing a sensor that can detect when it overflows. is there. For this reason, when a plurality of gas vent pipes 9 are installed, the incidental facilities become complicated and the cost increases.

  Further, in the hypo-injection apparatus 1 of the present embodiment, when the instructed injection amount is changed, the followability of the actual sub-injection amount is inferior to the instructed injection amount, as in the second embodiment. There is an inconvenience.

  The degassing pipe 9 applied to the hypo-injection apparatus 1 of the present embodiment can be added to the hypo-sub-injection apparatus 1 of the second embodiment.

  Using the hypo-injection apparatus shown in FIGS. 1 to 5, a hypo-injection test of the actual machine was performed under the conditions shown in Table 1 below, and the temporal behavior of the hypo-injection amount was investigated. This hypoinjection test was conducted in the summer when Hypoia is likely to generate gas. Moreover, the feedback control of the pump was performed using the measured value by the flowmeter provided in the vicinity of the exit of the transportation piping.

[Test conditions]
Test No. In any of 1 to 7, the inner diameter of the discharge port of the pump was constant at 16 mm, and the total length of the transport piping was uniform at about 100 m. Test No. 1 and 2 are tests using a conventional hypo-injection apparatus, and a transport pipe having an inner diameter of 16 mm (d = D), the same as the inner diameter of the pump discharge port, was adopted. Of these, test no. 1 employs a single-shaft eccentric screw pump as the pump. In No. 2, a diaphragm pump was used as the pump.

  In addition, Test No. In any of 3 to 7, a uniaxial eccentric screw pump was adopted as the pump. Of these, test no. Nos. 3 and 4 are tests using a hypo-injection apparatus that satisfies the condition of the expression (1) defined in the first embodiment of the present invention. In No. 3, the transport pipe is changed to one having an inner diameter of 8 mm (d = 0.5D). In No. 4, the inner diameter of the transport pipe is the test No. 4 mm (d = 0.25D), which is smaller than 3.

  Furthermore, test no. 5 is a test for confirming the effectiveness of the vent pipe in the hypo-injection apparatus of the third embodiment of the present invention, and one vent pipe was installed in the transport pipe. Test No. 6 is a test for confirming the effectiveness of the back pressure valve in the hypo-injection apparatus of the second embodiment of the present invention, and the back pressure valve was installed in the transport pipe. Test No. 7 is a test using the hypo-injection apparatus according to the second embodiment of the present invention, in which a back pressure valve was installed in the transport pipe and the transport pipe was changed to one having an inner diameter of 8 mm (d = 0.5D). . Test No. The back pressure valves in 6 and 7 were set to a gauge pressure of 0.1 MPa.

[Test results]
6 to 12 show the test numbers. It is a figure which shows the time-dependent behavior of the hypoinjection amount as a test result of 1-7. 6 to 12 show the following.

  As shown in FIG. In No. 1, since a uniaxial eccentric screw pump is employed, the measured injection amount in the vicinity of the pump discharge port follows the indicated injection amount and is constantly stable. However, due to the influence of the gas generated in the transport pipe, the measured injection volume in the vicinity of the transport pipe outlet, that is, in the vicinity of the injection point, is greatly disturbed with respect to the indicated injection volume, and the response delay is conspicuous.

  As shown in FIG. 2, test no. The injection state is almost the same as in FIG. In particular, when the operation is started, when the operation is stopped, and when the command injection amount is changed, the followability of the actual injection amount with respect to the command injection amount is relatively poor, and no feedback control is performed using a diaphragm pump (proportional control). Therefore, it can be understood that the injection amount is not corrected when a difference occurs between the instructed injection amount and the measured injection amount.

  As shown in FIG. 3, since the transportation piping that satisfies the condition of the expression (1) is adopted, the disturbance of hypoinjection due to the influence of gas can be greatly reduced. In addition, followability is good at the start of operation, when the operation is stopped, and when the command injection amount is changed.

  As shown in FIG. 4 can greatly reduce the disturbance of hypo-injection due to the effect of gas. Since the transport pipe having an inner diameter smaller than 3 is employed, the effect of reducing the disturbance of the hypoinjection amount is small.

  As shown in FIG. In No. 5, since one degassing pipe is installed in the transport pipe, there is a tendency that the influence of the gas can be slightly reduced. For this reason, if a plurality of degassing pipes are installed, the effect of reducing the disturbance of the sub-injection amount can be expected to increase.

  As shown in FIG. In No. 6, since the back pressure valve is installed in the transport pipe, it can be seen that the disturbance of the sub-injection due to the influence of gas can be greatly reduced. However, when the operation is started, when the operation is stopped, and when the command injection amount is changed, the followability of the actual injection amount with respect to the command injection amount is deteriorated.

  As shown in FIG. In No. 7, since a back pressure valve was installed in the transport pipe after the transport pipe satisfying the condition of the expression (1) was adopted, test no. As in the case of No. 6, the disturbance of sub-injection due to the influence of gas can be greatly reduced. However, the followability at the start of operation, at the time of operation stop, and at the time of changing the indicated injection amount is determined by test no. Not as bad as 6, but getting worse.

  From the above results, it is possible to easily prevent irregular fluctuations in the amount of hypochlorous injection by adopting a transportation pipe that satisfies the condition of the formula (1), and to accurately inject the sublimation into the pouring point. It becomes clear that it can be done.

  The sodium hypochlorite injection device of the present invention can be effectively used for water purification treatment at a water purification plant or the like.

1: Sodium hypochlorite injection device 2: Sodium hypochlorite storage tank,
3: pump, 3a: suction port, 3b: discharge port,
4: Transport piping, 4a: Inlet, 4b: Outlet,
5: Introduction piping, 6: Flow meter for pump control, 7: Flow meter for monitoring,
8: Back pressure valve, 9: Gas vent pipe,
31: Male threaded rotor, 32: Female threaded stator, 32a: Inner hole,
33: outer cylinder, 34: endstat,
35: Front housing, 35a: Suction pipe,
36: Rear housing, 37: Slide bearing housing,
38: Drive shaft, 38a: Flange part,
39: Universal joint, 40: Coupling rod, 41: Universal joint,
42: driven side magnet holding member, 43: driven side magnet,
51: Spindle of motor, 52: Driving side magnet holding member, 53: Driving side magnet,
A: Injection point, B: Management building

Claims (5)

A tank that stores sodium hypochlorite, a pump that sucks and discharges sodium hypochlorite in this tank, and a transport that is connected to the discharge port of this pump to transport and discharge sodium hypochlorite to the injection point A sodium hypochlorite injection device comprising a pipe,
A sodium hypochlorite injection device characterized in that the relationship between the inner diameter D of the discharge port of the pump and the inner diameter d of the transport pipe satisfies the condition of the following expression (1).
0.25D ≦ d <D (1) The relationship between the flow velocity V of sodium hypochlorite flowing through the discharge port of the pump and the flow velocity v of sodium hypochlorite flowing through the inside of the transport pipe satisfies the condition of the following formula (2): The sodium hypochlorite injection device according to claim 1.
V <v ≦ 10V (2)   3. The sodium hypochlorite injection device according to claim 1, wherein a back pressure valve is provided in a route near an outlet of the transport pipe.   The sodium hypochlorite injection device according to any one of claims 1 to 3, wherein a gas vent pipe is connected to a route of the transport pipe.   The sodium hypochlorite injection device according to any one of claims 1 to 4, wherein the pump is a uniaxial eccentric screw pump.

Images