JPS6070192A - Method and installation for electrolyzing sea water or aqueous salt solution - Google Patents

Abstract

PURPOSE:To enable stable production of NaClO water having high concn. in the stage of electrolyzing sea water and salt water by providing a gas vent tank and a separator tank in the mid-way of plural electrolytic cells and attaching degassing valves having a specific construction thereto. CONSTITUTION:A gas vent tank G and a separator S provided with degassing valves in the mid-way of an electrolytic cell array are disposed in the stage of disposing plural electrolytic cells EC for sea water or salt water in series and producing NaClO by DC electrolysis. Float type valves are used for the valves V and are opened and closed by the ascending and descending of the electrolyte contg. the gaseous H2 generated by the electrolysis as foam. The diameter d(cm) of the discharge port thereof is set at the value expressed by the equation ( I ) and the electrolytic cell pressure for drawing the NaClO soln. having a high concn. is set at <=(0.1-10)kg/cm<2>G in the value expressed by the equation (II). There is no increase in the electric resistance of the electrolyte owing to the presence of foamy H2 and the electrolytic operation is continued with the stable voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for electrolyzing seawater or salt water and improvements to electrolysis equipment thereof.

The production of available chlorine (equivalent to ct2 represented by NaCW) by electrolysis of seawater or salt water is normally carried out under atmospheric pressure, and electrolytic cells are installed singly or in series in a non-diaphragm installation piece. Electrolysis equipment is no exception, and it is known that forced pressurization is not performed.

Particularly in the operation of a single large electrolytic cell or electrolytic cells arranged in series, in order to increase the effective chlorine concentration, the hydrogen gas concentration also increases in proportion to this concentration.

Therefore, the hydrogen gas capacity in the electrolyte increases, and as the hydrogen gas capacity increases, the electrical resistance of the electrolyte containing gas increases. The flow also becomes unstable, causing fluctuations in voltage increases and decreases, making stable electrolysis operation impossible.

In order to stabilize this type of unstable electrolytic operation and perform efficient electrolysis, it is necessary to perform degassing in the middle of the electrolytic equipment. For example, when generating an effective chlorine concentration of 0.5 f/ or more, the pressure inside the electrolytic cell must be increased to increase the effective chlorine concentration, otherwise the bubbles will be smaller in order to electrolyze the electrolyte that encloses hydrogen gas bubbles. It is necessary to reduce the electrical resistance of the electrolyte, increase capacity, and perform stable operation.

Therefore, as shown in Figure 1, the conventional method is to provide head tanks H, T with a height of 5 m to 10 m in the middle or final part of the electrolytic equipment to degas the decomposed liquid in box 1. How to perform stable electrolytic operation, or as shown in Figure 2, 5~
An electrolyte receiving tank with a height of 10 tn is installed, and the electrolyte in each electrolytic tank E and C is pressurized to perform stable electrolysis operation, but...
In the conventional method, a part of the electrolysis equipment requires a high structure and a large number of piping systems, which inevitably complicates equipment and maintenance management.

On the other hand, forcibly pressurizing the electrolyte by 1Kf10n2
G, 2 Ky/cm2G, 5K17cm"G and 4Ky/1yn2G, etc., the gas volume in the electrolyte decreases to "S' In other words, the fluctuations in voltage increases and decreases are two times and three times, respectively.

Stable electrolytic operation can be performed until an effective chlorine concentration of 4 or 5 times is reached.

The present inventor has successfully developed the present invention as a result of various studies and experiments to eliminate the various defects of the conventional method.
The technical structure of the present invention is specified in each claim, and will be explained in detail with reference to FIG. 3, which shows a specific example of the present invention.

Figures 3 and 4 are flow sheets showing preferred examples for carrying out the electrolytic method of the present invention, and E and C are electrolytic cells arranged in series. A gas liquid tank G and a separator S are provided at the same height as the tank, and a degassing valve V is provided in these gas liquid tank G and separator S. The degassing valve V controls the pressure at the middle and outlet of the electrolytic cell group to a predetermined pressure, that is, 0.1 to 10 Ky/crn2G.
The electrolytic efficiency is maintained at a desired value.

The degassing valve V is preferably a float type valve as shown in FIG. This type of float valve is a valve mechanism that opens and closes as the electrolytic solution containing bubbles of hydrogen gas generated by electrolysis rises and falls. The pressure of 0, 1
It can be held under pressure of ~10Kg/Cm2G. Note that the valve mechanism is not limited to the one shown in FIG. 5, and the planar shape of the gas outlet may not be circular or polygonal, and may have a valve portion that opens and closes as the electrolyte rises and falls. can also be used.

As a result of experiments as shown in Table 1, it was found that the pressurized state can be maintained by setting the gas discharge port diameter d to d≦0.4×number of electrolytic cells X [KA, H]. .

Table 1 (Operating pressure 0.1 to 4.5 sales 4-〇) Electrolysis current Number of electrolytic cells Coefficient (KA) at degassing valve (tank)
Coverage 6.3 8 0.496 Ashiro, 3 8 0.397 None 3.5 13 0.3!10 None 3.5 13 0.440 Ash 2-0 13 0.30B None 5.5 12 By setting the coefficient to 0.4 or less based on the experimental results of 0.190 or more, stable operation of the stain removal tank group can be performed by forced pressurization.

In addition, an experiment in which the effective chlorine concentration was varied by controlling the flow rate was conducted in a group of 8 stone row type electrolytic cells at an electrolytic current of 520A. 30 Yes 0.730 1.75 No 0.750 2.18 No 1.022 1.75 Horse mackerel 1.0222.15 No 1.499 2.75 Yes 1.504 2.90 No 1.7953.10 A υ 1.805 3.59 None 2.044 3.55 Ap 2.0563.90 None When the experimental results in Table 2 above were plotted, a graph as shown in FIG. 6 was obtained.

From the above results, in electrolysis to maintain the effective chlorine concentration at a high concentration of 0.6 t/ or more, the pressure is forced to be in a region that is further pressurized from the straight line in Figure 6, that is, in the region above the straight line. By using the pressurizing method and providing a separator with a degassing valve, the stain removal tank can be operated stably.

The limit straight line shown in Figure 6 shows the effective chlorine concentration (Ct/l)
If 1 absolute pressure (1'#/-2) is P: C= 0.
52 + 0.53 (P-1).

As detailed above, by the configuration of the present invention,
Stable and efficient electrolyzing operation can be performed without adding high structures and numerous piping systems to electrolysis equipment as in conventional methods, and the equipment has excellent effects such as easy maintenance and management. It was successful in achieving the desired effect.

[Brief explanation of drawings]

Figures 1 and 2 are flow sheets of conventional electrolysis equipment, Figures 3 and 4 are flow sheets showing several examples of the present invention, and Figure 5 is a cross section showing an example of a flow valve used in the present invention. 6 is a graph showing the relationship between pressure and available chlorine according to the present invention. In the figure, E and C are electrolytic cells.)1. T is the head tank, ■ is the degassing valve, G is the degassing tank, and S is the separator. d indicates the gas outlet diameter of the degassing valve.

Claims (1)

[Scope of Claims] (1) In the electrolysis of seawater or salt aqueous solutions, a single electrolytic cell or a series electrolytic cell is pressurized and maintained at a predetermined pressure by providing a degassing mechanism that can degas it. , at least 0.
An electrolysis method for seawater or salt aqueous solution, characterized by producing a highly concentrated effective chlorine electrolyte of 6 t/L or more. (2) The predetermined pressure is 0.1 to 101Ly/cm2G
J.) The method for electrolyzing seawater or J salt aqueous solution according to claim 1 below. (3) The electrolytic cell is operated stably by setting the pressure above the pressure to obtain the necessary effective chlorine concentration as shown in the formula: % formula %) [In the above formula, C is the effective chlorine concentration and P is the absolute pressure] The method for electrolyzing seawater or salt aqueous solution according to claim 1. (4) In electrolysis equipment for seawater or salt aqueous solutions, the gas discharge port diameter dc of the degassing mechanism installed in a single electrolytic cell or a series electrolytic cell
Seawater or salt solution electrolysis equipment characterized in that ln is: d≦0.4 x number of electrolytic cells x (KAHI). (5) A patent claim in which the planar shape of the gas outlet is circular, polygonal, etc. Seawater or salt water solution electrolysis equipment according to claim 4. (61) Seawater or salt water bath liquid electrolysis equipment according to claim 4, wherein the gas outlet is a valve mechanism. (7) Gas outlet valve mechanism Seawater or salt water solution electrolysis equipment according to claim 4, comprising a valve corresponding to the shape of the outlet. (8) Claim 4, wherein the gas outlet valve mechanism is a float type valve. Seawater or salt water solution electrolysis equipment as described in Section 1.