JPS63307289A - Pressure control device for ion exchange membrane method electrolytic cell - Google Patents

Abstract

PURPOSE:To stably realize control of differential pressures is a region of high pressures and good efficiency by operating large and small flow rate control valves respectively provided to chlorine and hydrogen output pipelines from an electrolytic cell by controllers based on the respective pressures. CONSTITUTION:The 1st and 2nd large and small flow rate control valves 13, 14; 18, 19 are provided in parallel to the Cl2, H2 output pipelines 5, 6 of the electrolytic cell 1. The 1st and 2nd controllers 15, 16 with a gap function and ordinary function are inputted with a measured pressure value PV1 and set value SV1 and make P.I.D. control computation with deviations for the parts where the respective deviations exceed the gap width. The opening degrees of the valves 13, 14 are controlled by outputs MV11, MV12. A sensor 17 measures the differential pressure DELTAPV of Cl2 and H2 The 3rd, 4th controllers 20, 21 with the gap function and ordinary function are inputted with the measured value DELTAPV and set value DELTASV and control the opening angles of the valves 18, 19 by the respective outputs MW21, MV22 in the same manner as mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in pressure control of output chlorine and output hydrogen of an ion exchange removal cell for producing chlorine, hydrogen and caustic soda from salt water.

・〈Prior art 2〉 An example of the conventional technology will be explained based on FIG. 2. Reference numeral 1 denotes a battery container for performing ion exchange, which is divided into an anode chamber 101 and a cathode chamber 102 by an ion exchange membrane 2.

3 is an input pipe for introducing salt water to the anode chamber 101, 4 is an input pipe for introducing circulating catholyte to the cathode chamber 102, 5 is an output pipe for chlorine after ion exchange, and 6 is an output pipe for hydrogen after ion exchange. This is the output pipe.

7 is a pressure sensor installed in the chlorine output line, P
V + is the measured value, and 8 is a flow control valve also provided in the output pipe. 9 is a chlorine pressure regulator, which has an operational output M that controls the difference between the measured value PVI and the set value SVI.
The opening degree of the control valve 8 is controlled by V + to control the output pressure of chlorine to S V +.

10 is a pressure sensor installed in the hydrogen output pipe, P
V2 is the measured value, and 11 is a flow control valve also provided in the output pipe. Reference numeral 12 denotes a hydrogen pressure regulator, which operates the opening of the control valve 11 using the operation output M V 2 obtained by controlling and calculating the difference between the measured value P V 2 and the set value SV 2 to adjust the hydrogen output pressure to SV 2. Control.

In such a battery case, chlorine is generated on the sub-electrode side and hydrogen is generated on the cathode side with the ion-exchange membrane 2 as a boundary.

If more than a few percent of hydrogen gas enters chlorine gas, there is a possibility of an explosion, so it is necessary to operate at a mixing rate of 0.5% or less.

For this reason, the pressure on the chlorine side is controlled to be slightly higher than the pressure on the hydrogen side so that hydrogen does not enter the chlorine side even if there is a small membrane tear in the ion exchange membrane.

Therefore, in the configuration shown in FIG. 2, SV+-8v2+Δ
Set each pressure regulator according to P and operate.

<Problems to be solved by the invention> Generally, in order to increase electrolysis efficiency, it is preferable to operate at a high pressure, but the problem with such individual pressure settings is that The differential pressure ΔP must be controlled to several hundred mm H2O, and stable control is difficult considering the accuracy of the pressure sensor and controller, and the differential pressure balance is easily lost, so it is possible to achieve this by lowering the pressure and using a small range. I had no choice.

Furthermore, if the differential pressure setting is too large, it will cause membrane rupture, and if it is too small, it will not be possible to prevent hydrogen from entering when the membrane ruptures, so the setting value is delicate and requires highly accurate control. .

An object of the present invention is to construct a control device that can stably control differential pressure in a high-pressure and efficient region.

・Means for solving the problems> The structural feature of the present invention is that in a pressure control device for a battery tank in an ion-exchange membrane electric field plant that outputs chlorine and hydrogen, the chlorine output pipe from the battery tank is A first large-flow suspension control valve and a first small-flow inter-flow control valve provided in the passage, and a gap function that operates the large-flow control valve by an operation output based on the pressure measurement value and set value of the chlorine output pipe. a first controller means of;
a second controller means that commonly receives the pressure measurement value and the set value and operates the small flow control valve according to its operation output; The second control valve and the second small flow group control valve are operated by the operation output based on the differential pressure set value such as the differential pressure measurement value between the pressure measurement value of the chlorine output pipe and the pressure measurement value of the hydrogen output pipe. a third adjustment section J1 means with a gap function for operating the dog flow suspension control valve; and a third adjustment section J1 means for commonly receiving the differential pressure measurement value and the differential pressure setting value and operating the second small flow control valve using the operation output thereof. 4 controller means.

・Function]・ A large flow rate control valve and a small flow control valve are provided in the chlorine output line from the tank, and a controller 5 with a gap function is installed to input the pressure measurement value and set value of the chlorine output line. The large flow control valve is operated by the operation output of the means, and the small flow control valve is operated by the operation output of the normal function controller which receives the pressure measurement value and the set value in common.

A large flow rate control valve and a small flow control valve are installed in the hydrogen output line from the battery tank, and the differential pressure measurement value and differential pressure setting between the pressure measurement value of the chlorine output line and the pressure measurement value of the hydrogen output line is provided. The large flow rate control valve is operated by the operation output of the controller means with a gap function that inputs the value, and the small flow control valve is operated by the operation output of the normal function controller that receives the differential pressure measurement value and the differential pressure set value in common. The valve is operated.

<Example> The present invention will be explained in detail based on FIG. Components that are the same as those described in FIG. 2 are given the same reference numerals, and their description will be omitted.

°13 is the first large flow rate control valve provided in the chlorine output line 5;
14 is a first small flow control valve provided in parallel with 13.

15 is the first controller with a gap function, which inputs the measured pressure value P V + and the set value S V +, and performs P, I, and D control when the deviation exceeds the gap width. The calculation is executed, and the opening degree of the first canine flow control valve 13 is controlled based on the operation output MV++.

16 is a second controller with normal function, and the pressure measurement value P V
+ and set value SV+ are input in common with 15, P, I, and D control operations are executed for the deviation deviation, and the opening degree of the first small flow control valve 14 is controlled by the operation output MVI2. .

17 is a differential pressure sensor 9'' which measures the differential pressure between the output pipes 5 and 6, that is, the differential pressure between chlorine and hydrogen. ΔPV is the measured value.

18 is a second large flow rate control valve provided in the hydrogen output pipe 6;
9 is a second small flow control valve installed in parallel with 18.

20 is a third adjustment t1 having a gap function, which inputs the measured differential pressure value ΔPV and the set differential pressure value ΔSv, and adjusts P and I for the portion where the deviation exceeds the gap width.

D control calculation is executed, and the second
The opening degree of the large flow rate control valve 18 is controlled.

21 is the fourth controller with normal function, and the differential pressure measurement value ΔPV
and differential pressure setting value ΔSv are input in common with 20, and P, 1. Executes D control calculation and outputs its operation output MV2
2 to control the opening degree of the second small flow control valve 19.

As described above, the first feature of the present invention is that the pressure control on the chlorine side and the hydrogen side is performed between a large flow control valve operated by a controller with a gap function and a small flow control valve operated by a controller with a normal function. The control valves are controlled in parallel, and when the deviation is small and within the gap width, the small flow control valve performs high precision pressure control, and when the deviation exceeds the gap width, the large flow control valve is operated. In this way, uniform and highly accurate control of the pressure within the measurement span is achieved.

In this case, if the gap gain is changed to be larger than zero, even if the deviation is within the gap width, the large flow rate control valve can be operated gently and more stable control can be achieved.

The second feature of the present invention is that the hydrogen side is controlled by differential pressure control based on the stably controlled pressure on the chlorine side, resulting in stable and highly accurate differential pressure control. is realized.

<Effects of the Invention> As explained above, according to the present invention, it is possible to easily realize a device that can control the pressure in the anode chamber and the cathode chamber at a high level with a constant differential pressure, stably, and with high accuracy. , it is possible to operate to increase the efficiency of the electric field process of the ion exchange membrane method,
It can contribute to energy saving.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of the prior art.

Claims (1)

[Claims] In a pressure control device for a battery tank in an ion-exchange membrane method electric field plant that outputs chlorine and hydrogen, a first large flow rate control valve and a first small flow rate control valve provided in a chlorine output pipe from the battery tank, a first controller means with a gap function that operates the large flow rate control valve with a manipulated output based on the pressure measurement value and set value of the output pipe; a second controller for operating a small flow control valve; a second large flow control valve and a second small flow control valve provided in the hydrogen output line from the battery tank;
A third valve with a gap function that operates the second large flow rate control valve by an operation output based on a differential pressure measurement value and a differential pressure setting value between the pressure measurement value of the chlorine output pipe and the pressure measurement value of the hydrogen output pipe. An ion exchange membrane method cell pressure control device comprising a controller means, and a fourth controller means that receives the differential pressure measurement value and the differential pressure set value in common and operates the second small flow rate control valve by the operation output thereof. .