JPS5850794B2 - Pressurized injection device for sodium hypochlorite solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressurized injection device for injecting an aqueous sodium hypochlorite solution into water for the purpose of disinfection.

As a source of chlorine added to water for disinfection purposes, sodium hypochlorite has attracted attention as an alternative to chlorine gas due to its safety, and has already reached the stage of practical application.

Sodium hypochlorite is generally used in the form of an aqueous solution with a constant concentration of about 10%, and is equivalent to about 1 to 1% in terms of chlorine.
Added to water to a concentration of 8 ppm.

Therefore, in order to obtain a stable disinfection effect, it is necessary to inject the sodium hypochlorite solution into the water at a predetermined constant flow rate.

This injection is generally carried out using a pump, but sodium hypochlorite solution is susceptible to changes in pH, temperature increase, sunlight irradiation, mechanical stirring, etc.
→, 2 NaCl +0□ reaction is likely to occur and oxygen gas is generated, and this gas causes gas lock of the pump, making it difficult to inject at a stable flow rate.

Furthermore, the generated air bubbles cause an error in the electromagnetic flowmeter, which hinders accurate flow rate measurement.

An object of the present invention is to provide a pressurized injection device capable of stably injecting a sodium hypochlorite aqueous solution into water at a desired constant flow rate.

Next, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, symbols A and B respectively indicate pressurized tanks having essentially the same construction.

One pressurized tank A is connected to the yarn path 11 via a filling valve 1a in order to inject a sodium hypochlorite solution supplied from a storage tank (not shown) into the pressurized tank A.
Also, in order to increase the internal pressure, the compressor 12
It is connected to a yarn path 13 that is connected to a thread line 13 via a pressure valve 2a.

A pressure regulating valve 14 is provided in the yarn path 13.

Further, the sodium hypochlorite solution in the pressurized tank A is sent out to the yarn path 15 via the injection valve 3a.

Note that 4a represents a pressure gauge for detecting the pressure within the pressurized tank, and 5a represents a leak valve.

Further, the pressurized tank A is provided with a level meter 6a in order to detect the liquid level of the sodium hypochlorite solution contained therein.

As shown in FIG. 2, this level meter 6a indicates when the liquid level of the solution in the pressurized tank A has reached three preset levels: high level HL, low level LL, and injection level. It has a function of detecting and generating a detection signal respectively.

Since the other pressurized tank B also has the same configuration, corresponding parts are indicated by the same reference numerals with the symbol "a" added thereto instead of the symbol "a", and the explanation thereof will be omitted.

That is, in the pressurized injection device of the present invention, two pressurized tanks A and B are arranged side by side, and injection and filling of the sodium hypochlorite aqueous solution are performed alternately.

The sodium hypochlorite solution sent from the pressurized tank A or B to the thread path 15 passes through a flow meter 17 and a flow rate control valve 16, and then enters a mixing device for mixing the sodium hypochlorite solution with treated water. sent to the inlet.

The flow rate regulator 18 calculates the ratio of the flow rate of sodium hypochlorite to the treated water from the signal indicating the flow rate of the treated water and the signal obtained from the flow meter 17, and adjusts the ratio so that the ratio becomes the set value. The flow control valve 16 is controlled.

The alternating operation of the pressurized tanks A and B is achieved by controlling the filling valves 1a and 1b, the pressurizing valves 2a and 2b, and the injection valves 3a and 3b according to the liquid level detected by the level meters 6a and 6b. ).

FIG. 3 shows an example of temporal changes in the liquid levels in the pressurized tanks A and B during the pressurized injection operation.

When the solution in the pressurized tank A is being injected, only the pressurizing valve 2a and the injection valve 3a are opened, and the other valves are closed, according to a command from the controller.

Therefore, in this state, only the solution in the pressurized tank A is delivered to the yarn path 15.

When the solution in the pressurized tank A decreases and the liquid level drops to the low level LL, the output signal of the level meter 6a is sent to the controller, and the output signal from the controller that receives this sends the pressure valve 2b and the injection Valve 3b is opened.

At this time, the pressurizing valve 2a and the injection valve 3a also remain open, and are closed when the liquid level in the pressurizing tank A falls to the injection level.

That is, until the liquid level in the pressurized tank A reaches the low level LL, only the solution in the pressurized tank A is sent to the thread path 15, but the time from when the liquid level reaches the low level LL until it drops to the injection level In the zone, solution is pumped from both pressurized tanks A and B.

When the injection level is reached, the pressurizing valve 2a and the injection valve 3a are closed to stop supplying the solution from the pressurizing tank A, and the filling valve 1a and the leak valve 5a are opened instead. is filled with new sodium hypochlorite solution, and the air in the pressurized tank A is released to the outside from the leak valve 5a.

The new solution is supplied until the liquid level in the pressurized tank A rises to the high level HL, and then the filling valve 1a and the leak valve 5a are closed, and the liquid level in the other pressurized tank B is increased. It waits until it reaches the low level LL.

By repeating this operation, sodium hypochlorite solution is alternately supplied from pressurized tanks A and B, and during the simultaneous injection period when the supply from one of them approaches the end point, it is supplied from both pressurized tanks A and B. Solution is supplied.

Note that the simultaneous injection time period can also be set on a timer.

Experiments have confirmed that this simultaneous injection is extremely important for stably injecting the sodium hypochlorite solution at a constant flow rate.

For example, if supply from one pressurized tank is started and supply from the other pressurized tank is stopped at the same time, as shown in FIG. 4A, the injection amount will fluctuate significantly when the supply is switched.

However, when a simultaneous injection time period is provided, as shown in FIG. 4B, fluctuations in the injection amount at the time of switching are effectively suppressed.

In addition, the flow from the storage tank to the pressurized tanks A and B is as follows:
Gravity is preferable, and even if a pump is used, the head must be low.

If the lift height is increased, this pump will cause problems such as gas lock, making it impossible to achieve the intended purpose.

As described above, according to the present invention, the sodium hypochlorite solution is sent out in a pressurized state in the pressurized tanks A and B, so that bubbles are generated, which is a phenomenon peculiar to sodium hypochlorite solutions. is suppressed, and the flow rate can be measured and controlled accurately.

Furthermore, since no pump is used, there are no problems such as gas lock.

Moreover, since injection is carried out alternately using the two pressurized tanks A and B, and a simultaneous injection time period is provided when switching the injection, a stable injection amount can be maintained and fluctuations at the time of switching are extremely small.

Furthermore, when a pressure regulating valve 14 is provided in the thread path 13 leading from the compressor 12 to the pressurized tanks A and H, the pressure in the pressurized tanks A and B, that is, the injection amount, can be adjusted within a wide range. It is also possible to easily adapt to cases where the flow rate of treated water is different.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a pressurized injection device according to an embodiment of the present invention, FIG. 2 is a vertical sectional view schematically showing a pressurized tank used in the device, and FIG. 3 is a system diagram of the pressurized injection device according to an embodiment of the present invention. FIGS. 4A and 4B are graphs showing changes in the injection amount over time in the two pressurized tanks. FIGS. 4A and 4B are graphs showing changes in the injection amount when the simultaneous injection time period is not provided and when it is provided. A, B...pressurized tank, la, lb...
・Filling valve, 2a, 2b... Pressure valve, 3a, 3b
......Injection valve, 4a, 4b...Pressure gauge, 5a, 5b...Leak valve, 6a, 6b...
...Level/L-; Total, 12...Compressor, 14...Pressure control valve, 16...
Flow rate control valve, 17... Flow meter, 18...
・Flow rate regulator.

Claims (1)

[Scope of Claims] 1. A pair of pressurized tanks each equipped with a filling valve, a pressurizing valve, an injection valve, and a level meter, and the hypochlorite contained therein by the pressure applied through the pressurizing valves. A thread path leading the sodium hypochlorite solution from the injection valve to the injection port, and a thread path that leads the sodium hypochlorite solution from the injection valve to the injection port, and while the sodium hypochlorite solution is being fed into the system from one pressurized tank, the filling valve is installed in the other pressurized tank. The above-mentioned filling valve, pressurizing valve, and A pressurized injection device for a sodium hypochlorite solution, comprising a controller that controls an injection valve based on a detection signal from the level meter. 2. Hypochlorous acid according to claim 1, comprising a compressor for pressurizing the insides of both pressurizing tanks via the pressurizing valve, and a pressure regulating valve provided in the pressure supply line. Pressurized injection device for sodium solution.