Device for controlling concentration of brine discharged from tank of chlor-alkali device

Abstract

A device for controlling the concentration of brine discharged from a tank of a chlor-alkali device comprises a secondary refined salt pump, and a liquid outlet of the secondary refined salt pump is connected with a liquid inlet of a feeding pipeline of an electrolytic tank; a liquid outlet of the electrolytic bath feeding pipeline is connected with a liquid inlet of the electrolytic bath, and a liquid outlet of the electrolytic bath is connected with a liquid inlet of the gas-liquid separator; a liquid outlet in the tower bottom of the gas-liquid separator is connected with a first feeding hole of the anolyte storage tank; a discharge hole of the anolyte storage tank is connected with a liquid inlet of the anolyte circulating pump; a liquid outlet of the anolyte circulating pump is connected with one end of a reflux pipeline, the other end of the reflux pipeline is connected with a second feeding hole of the anolyte storage tank, and a light salt brine concentration meter is arranged on the reflux pipeline. The device for controlling the concentration of the brine discharged from the tank of the chlor-alkali device aims to solve the technical problems that the concentration recovery time of light salt brine is long and the control effect is poor in the existing technology for controlling the concentration of the brine discharged from the tank.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical equipment, in particular to the technical field of chlor-alkali devices, and specifically to a device for controlling the concentration of brine discharged from a chlor-alkali device. Background Art

[0002] Chlor-alkali plants are a key component of chemical production, primarily producing caustic soda, chlorine, and hydrogen through the electrolysis of saturated sodium chloride solutions. Improper control of the brine at the outlet of the electrolysis tank can negatively impact product quality and production efficiency. For example, low chlorine purity and high hydrogen content in the chlorine, along with prolonged concentrations below 180g / l, can cause ion exchange membrane blistering and pinholes, resulting in decreased current efficiency and even membrane failure.

[0003] The current traditional technology for controlling the concentration of brine out of the tank is: by measuring the specific gravity and temperature, querying the concentration of brine out of the tank according to the brine specific gravity-temperature correspondence table, and then manually intervening to adjust the brine flow rate into the tank to control the concentration of brine out of the tank.

[0004] However, this approach has the following problems:

[0005] 1) Due to the complex production environment of the chlor-alkali plant and the large fluctuations in brine concentration, adjustments must be made to each circuit, which results in a large workload, long reaction observation time, and a long recovery time for the brine concentration.

[0006] 2) This method requires high skills and experience of the operator, otherwise it is difficult to ensure the adjustment effect;

[0007] 3) This method cannot respond to changes in brine concentration in real time, resulting in poor control effect. Summary of the Invention

[0008] The purpose of the utility model is to solve the technical problems of long recovery time of brine concentration and poor control effect in the existing out-tank brine concentration control technology, and to propose a device for controlling the out-tank brine concentration of a chlor-alkali device.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A device for controlling the concentration of brine discharged from a chlor-alkali device comprises a secondary refined brine pump, wherein the liquid outlet of the secondary refined brine pump is connected to the liquid inlet of an electrolytic cell feed pipe; the liquid outlet of the electrolytic cell feed pipe is connected to the liquid inlet of the electrolytic cell, and the liquid outlet of the electrolytic cell is connected to the liquid inlet of a gas-liquid separator; the liquid outlet at the bottom of the gas-liquid separator is connected to the first feed inlet of an anode liquid storage tank; the discharge port of the anode liquid storage tank is connected to the liquid inlet of an anode liquid circulation pump; the liquid outlet of the anode liquid circulation pump is connected to one end of a reflux pipe, and the other end of the reflux pipe is connected to the second feed inlet of the anode liquid storage tank, and a brine concentration meter is provided on the reflux pipe.

[0011] A brine flow feed pneumatic valve is provided on the electrolytic cell feed pipe.

[0012] The liquid outlet of the circulation pump is connected to the production pipeline at the same time, and the output material of the production pipeline enters the dechlorination process.

[0013] The electrolytic cell feed pipe is equipped with a brine flow feed pneumatic valve.

[0014] The circulation pump is connected to the production pipeline, and the production pipeline is connected to the dechlorination process.

[0015] Compared with the prior art, the present invention has the following technical effects:

[0016] 1) Through precise equipment selection and optimized structural design, this device can achieve efficient control of the brine concentration at the outlet of the chlor-alkali unit. For example, the selection of a specific model of secondary refined brine pump and electrolytic cell feed pipe ensures stable and uniform brine delivery to the electrolytic cell, laying the foundation for subsequent concentration control.

[0017] 2) The synergistic effect of the anolyte circulation pump and return piping, combined with a high-precision brine concentration meter, enables real-time monitoring and automatic adjustment of brine concentration. A specific model of circulation pump provides stable flow and pressure, ensuring the brine circulates throughout the system, while the fast response and accurate measurement of the concentration meter provide the basis for automatic adjustment, significantly improving control effectiveness and reducing brine concentration recovery time.

[0018] 3) The pneumatic valve for brine flow in the electrolytic cell feed pipe can precisely control the brine flow rate. Working in conjunction with a brine concentration meter and automatic control system, this valve achieves even more precise concentration control. Specific models of pneumatic valves offer fast response and high control accuracy, enabling timely adjustment of the brine flow rate based on concentration changes, effectively improving process stability.

[0019] 4) The compact overall structure and stable operation of this device reduce the frequency of human intervention, lowering the workload and skill requirements for operators. Furthermore, the system's high degree of automation enables real-time response to changes in brine concentration and prompt adjustments, effectively improving production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0021] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0022] like Figure 1As shown, a device for controlling the concentration of brine discharged from a chlor-alkali device comprises a secondary refined brine pump 1, the liquid outlet of the secondary refined brine pump 1 is connected to the liquid inlet of an electrolytic cell feed pipe 2; the liquid outlet of the electrolytic cell feed pipe 2 is connected to the liquid inlet of an electrolytic cell 3, and the liquid outlet 4 of the electrolytic cell is connected to the liquid inlet of a gas-liquid separator 5; the liquid outlet at the bottom of the gas-liquid separator 5 is connected to the first feed inlet of an anolyte storage tank 6; the discharge port 7 of the anolyte storage tank is connected to the liquid inlet of an anolyte circulation pump 8; the liquid outlet of the anolyte circulation pump 8 is connected to one end of a reflux pipe 9, the other end of the reflux pipe 9 is connected to the second feed inlet of the anolyte storage tank 6, and a brine concentration meter 10 is provided on the reflux pipe 9.

[0023] A brine flow feed pneumatic valve 11 is provided on the electrolytic cell feed pipe 2.

[0024] The liquid outlet of the circulation pump 8 is also connected to the production pipeline 12 , and the production pipeline 12 outputs the material into the dechlorination process 13 .

[0025] The electrolytic cell feed pipe 2 is provided with a brine flow feed pneumatic valve 11 .

[0026] The circulating pump 8 is connected to the production pipeline 12, and the production pipeline 12 is connected to the dechlorination process 13.

[0027] As an optimal multivariable automatic control system, it includes electrolytic cell concentration detection value, brine concentration detection value, satisfied conditions, execution process, fault alarm, controller parameters, etc., wherein the brine concentration count value is associated with the electrolytic cell brine concentration detection value.

[0028] As the preferred concentration detection value, the upper and lower limits of the brine concentration manually set values on a single electrolytic cell are used to adjust the concentration detection value, which mainly serves to limit the adjustment range of the concentration detection value.

[0029] The preferred detection value of the dilute brine concentration is the upper and lower limits of the online concentration setting range of the dilute brine out of the tank. The controller determines whether the manual setting value of the brine concentration needs to be adjusted based on the upper and lower limit settings of this function block.

[0030] The preferred conditions are that the rectifier is running and the current is greater than 8KA, the current rise and fall exceeds one hour, the upper and lower limits of the concentration detection value adjustment have been set, the upper and lower limits of the brine concentration have been set, and the adjustment cycle adjustment step has been set.

[0031] As a preferred execution process, when the online concentration of the light salt water exceeds the upper limit or lower limit of the range, the controller adjusts according to the set adjustment cycle and adjustment step. When the online concentration of the light salt water reaches the upper limit and lower limit of the range, the controller stops adjusting.

[0032] As a preferred fault alarm, when the online concentration of the dilute brine does not change within one hour or the change range is greater than 5g / L within one hour, a pop-up alarm will be issued, the control switch will be automatically cut off, and the operation of the process instrument will be checked immediately.

[0033] The preferred controller parameters are the brine concentration detection cycle setting and the adjustment step setting.

[0034] In this utility model, the secondary refined brine pump can be a ThyssenKrupp Wude Chlorine Engineering Technology Co., Ltd. FTND2015D31SL pump. The secondary refined brine flowing from the secondary refined brine storage tank (optional model V-1501) is pumped into the manifold of each electrolytic cell and then diverted to each anode chamber, where it is separated into chloride ions and sodium ions. A flow controller is installed on the brine input line at the inlet of each electrolytic cell to measure the flow rate of the secondary refined brine. This equipment has a flow rate Q of 221m³ / h, a head H of 30m, and a power P of 37kW.

[0035] The gas-liquid separator can be a gas-liquid separator compatible with the nxBiTACplus896 electrolyzer from ThyssenKrupp Wude Chlorine Engineering Technology Co., Ltd. The brine and wet chlorine overflowing from each anode chamber enter a manifold mounted on each electrolyzer for gas-liquid separation. The brine from the manifold flows by gravity through branch pipes and a main pipe into the anolyte storage tank (optional model V-2001), while the chlorine is delivered to the boundary area (chlorine treatment unit).

[0036] The brine from the anolyte storage tank is pumped to the dechlorination unit through level control; a portion of the brine in the anolyte storage tank is mixed with fresh secondary refined brine and returned to the electrolytic cell for recycling.

[0037] The device for controlling the concentration of brine discharged from a chlor-alkali device adopts the following steps when in operation:

[0038] 1) Start the secondary refined brine pump 1 to feed the secondary brine into the electrolytic cell 3 through the electrolytic cell feed pipe 2, and at the same time feed the alkali solution diluted with pure water into the cathode chamber of the electrolytic cell 3;

[0039] 2) Direct current is introduced to carry out electrolysis reaction. The chlorine gas and the dilute brine obtained at the anode enter the gas-liquid separator 5 through the electrolytic cell outlet 4 for separation. The chlorine gas overflows from the top of the tower and is collected in the chlorine recovery main pipe for dechlorination treatment process.

[0040] 3) The brine flows out from the bottom of the tower to the anolyte storage tank 6. A portion of the brine in the anolyte storage tank 6 flows back to the anolyte storage tank 6 from the anolyte storage tank outlet 7 via the anolyte circulation pump 8 and the reflux pipe 9. The other portion is processed in the dechlorination process 13 and returned to the primary brine distribution tank. A brine concentration meter 10 is provided on the reflux pipe 9 for real-time monitoring of the brine concentration.

[0041] 4) When the concentration of the light brine is lower than the set value, the signal is fed back to the controller, and the controller automatically adjusts the brine flow feed pneumatic valve 11 to increase the brine flow into the tank.

[0042] During system operation, if the brine concentration exceeds the set range, the controller will automatically adjust according to the set adjustment cycle and adjustment step. When the online brine concentration reaches between the upper and lower limits of the range, the controller stops adjusting. Furthermore, if the online brine concentration does not change within an hour or changes by more than 5g / L within an hour, the system will issue a fault alarm and automatically cut off the control switch, prompting the operator to immediately check the operation of the process instrumentation.

Claims

1. A device for controlling the concentration of brine discharged from a chlor-alkali plant, characterized in that: The invention comprises a secondary refined brine pump (1), wherein the liquid outlet of the secondary refined brine pump (1) is connected to the liquid inlet of the electrolytic cell feed pipe (2); the liquid outlet of the electrolytic cell feed pipe (2) is connected to the liquid inlet of the electrolytic cell (3); the liquid outlet of the electrolytic cell (4) is connected to the liquid inlet of the gas-liquid separator (5); the liquid outlet at the bottom of the gas-liquid separator (5) is connected to the first feed inlet of the anolyte storage tank (6); the material outlet (7) of the anolyte storage tank is connected to the liquid inlet of the anolyte circulation pump (8); the liquid outlet of the anolyte circulation pump (8) is connected to one end of the reflux pipe (9), the other end of the reflux pipe (9) is connected to the second feed inlet of the anolyte storage tank (6), and a salt water concentration meter (10) is provided on the reflux pipe (9).

2. The device according to claim 1, characterized in that A brine flow feed pneumatic valve (11) is provided on the electrolytic cell feed pipe (2).

3. The device according to claim 1, characterized in that The liquid outlet of the circulation pump (8) is also connected to the production pipeline (12).

4. The device according to claim 1, characterized in that The electrolytic cell feed pipe (2) is provided with a brine flow feed pneumatic valve (11).

5. The device according to claim 1, characterized in that The circulating pump (8) is connected to the extraction pipeline (12).

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