JPS6115159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid supply method for uniformly supplying liquid to each unit cell of a filter press type electrolytic cell. A filter press type electrolytic cell usually has a structure in which liquid is supplied to a plurality of unit cells in parallel from a common inlet header, and is similarly drawn out in parallel to a common drain header (referred to as an outlet header). In order to operate such a filter press type electrolytic cell efficiently, one premise is to supply the same amount of liquid to each unit cell. That is,
For example, in an ion-exchange membrane salt electrolyzer, if there is a 10% variation in the amount of brine supplied to each unit cell, the desalination rate (concentration) and PH
This causes variations in the chlorine content, which in turn has an adverse effect on the performance of the battery cell, and in some cases may even reduce the purity of the produced chlorine. However, normally, due to gas generated by electrolytic reactions in each unit container, a flow of a different shape occurs in each unit container, and the flow resistance of the liquid is not equal. Fluid resistance also occurs depending on the length of the connecting hose (usually a flexible hose) extending from the inlet and outlet headers to the unit battery case, the degree of bending, etc. Due to these various factors, it is quite difficult to guarantee the same flow rate for each unit container.
In particular, for large batteries with an effective height of 1 m or more, and even for ion-exchange membrane method alkali metal salt electrolyzers, the need for equal flow distribution to each unit battery is even greater. , there is a strong tendency for equal flow rate distribution to become difficult. Therefore, the present invention provides a means for solving the above-mentioned difficulties. That is, the present invention is applicable to filter press type electrolyzers, particularly electrolyzers used for ion exchange membrane method alkali metal salt electrolysis, which are large-scale devices that normally have difficulty distributing equal flow rates, such as electrolyzers with an effective height of 1 m or more. As a method of supplying liquid almost equally to each unit cell of the tank, the difference between the internal pressure of the inlet header and the internal pressure of the outlet header is set to 1500 mm or more of water column, preferably 2000 mm of water column or more. Furthermore, as mentioned above, a preferred method for creating a pressure difference between both the inlet and outlet headers is to create a pressure difference by changing the shape, i.e., the inner diameter and length, of the flexible hose that connects each unit battery case and each header. It is. As described above, the present invention provides a pressure difference (P ₁ ) between the inlet header internal pressure (P 1 ) and the outlet header internal pressure (P ₂ ) _.
-P ₂ =ΔP), it is extremely effective in that almost the same amount of solution can be easily supplied to each unit container. Normally, in a filter press type inlet container, each unit container and the hoses for supplying and draining liquid thereto are manufactured to have the same shape as possible. However, as mentioned above, there are various differences between each unit container, and it is difficult to guarantee the supply of the same flow rate to each unit container.However, in the present invention, from among many factors, the They discovered that by controlling the pressure difference between the two, it is possible to control the flow rate distribution as a summation of these various factors. Therefore, the present invention is not applicable to a case where unit cells constituting a filter press electrolytic cell have extremely different structures. The present invention will be explained below using the drawings. FIG. 1 is a schematic diagram of a filter press type ion exchange membrane method electrolytic cell. In the figure, 1 is an anode, 2 is a cathode, 3 is a cation exchange membrane, and 4 is a partition wall. Each unit battery case is
An anode chamber A consisting of an ion exchange membrane 3 to a partition wall 4 containing an anode 1, and an ion exchange membrane 3 containing a cathode 2.
- A cathode chamber K consisting of a partition wall 4. Here, for example, saline solution is supplied from the inlet header 5 and introduced into each anode chamber through each flexible hose 6.
Further, the discharged liquid is discharged from each anode chamber to an outlet header 8 by each flexible hose 7. Similarly, on the cathode chamber side, water or an aqueous caustic soda solution is introduced into the cathode chamber from an inlet header 9 through a flexible hose 10, and the aqueous caustic soda solution is discharged through a flexible hose 11 to an outlet header 12. Therefore, in the present invention, the difference between the internal pressure of the inlet header 5 and the internal pressure of the outlet header 8 and/or
It is essential that the difference between the internal pressure of the inlet header 9 and the internal pressure of the outlet header 12 be 2000 water columns or more. FIG. 2 is a diagram showing a unit battery case. For example, if it is explained as an anode chamber, the inlet header 5 is
The pressure gauge PG attached to this confirms that it is _P1 . The solution reaches the anode chamber inlet nozzle of the unit cell via a flexible hose 6. In this figure, the liquid is uniformly supplied into the anode chamber from the bottom of the tank by the tank internal distribution pipe 13. As the liquid rises, it undergoes an electrolytic reaction and generates bubbles, becoming a gas-liquid mixture at the top of the anode chamber and reaching the outlet nozzle. From the anode chamber outlet nozzle, it enters the outlet header 8 as a gas-liquid multiphase flow via a flexible hose 7. Most of the gas and liquid are separated within the outlet header, and the internal pressure can be determined by the pressure gauge PG. Furthermore, since the header internal pressure distribution can be almost ignored since the header diameter is extremely larger than the nozzle diameter in each unit container, the installation position of each pressure gauge is not particularly limited. Example A filter press type ion exchange membrane salt electrolytic cell consisting of 26 pairs of unit cells having bipolar electrodes with an electrode area of 1.6 m ² was used. Separately measured Nafion electrolytic cell with a current efficiency of 78% ± 2% was used in this electrolytic cell. 315 (cation exchange membrane made by DuPont) is installed to perform salt electrolysis. In addition, Teflon bellows-type flexible hoses are used from the inlet header to each unit battery case and from each unit battery case to the outlet header, and by changing the length of these hoses, the inlet header Internal pressure P ₁ and outlet header internal pressure P ₂
We examined the variation in the amount of salt water supplied to each unit tank by giving various differences between The degree of variation in the amount of salt water supplied was determined by the variation in PH at the outlet of each unit cell. In addition, the electrolysis conditions are raw material salt water concentration 4.1 normal PH = 0.4
It is prepared and supplied, and recovered at an average concentration of 4.0 normal PH = 2.0. The results are shown in the table below. 【table】

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a filter press type electrolytic cell using an ion exchange membrane, and FIG. 2 is an explanatory diagram of a unit cell of the filter press type electrolytic cell. In the figure, 1 is an anode, 2 is a cathode, 3 is an ion exchange membrane,
4 is a bulkhead, 5 and 9 are inlet headers, 8 and 12
is an outlet header, and 6, 7, 10, and 11 are flexible hoses. Also, PG represents a pressure gauge.

Claims (1)

[Scope of Claims] 1. A method for supplying liquid to an electrolytic cell, characterized in that when supplying liquid to a filter press type electrolytic cell, the difference between the internal pressure of the inlet header and the internal pressure of the outlet header is 2000 mm or more of water column. 2. The method according to claim 1, wherein the electrolytic cell has bipolar electrodes. 3. The method according to claim 1, wherein the electrolytic cell is a cell for electrolyzing alkali metal salts using an ion exchange membrane method. 4. A flexible hose is used between the electrolytic cell and the inlet header and/or the outlet header, and by adjusting the inner diameter and length of the hose, a pressure difference between the inlet header and the outlet header is created appropriately. A method according to claim 1.