CN109518224B - Emergency PLC control process for caustic soda system - Google Patents

Emergency PLC control process for caustic soda system Download PDF

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Publication number
CN109518224B
CN109518224B CN201811279823.7A CN201811279823A CN109518224B CN 109518224 B CN109518224 B CN 109518224B CN 201811279823 A CN201811279823 A CN 201811279823A CN 109518224 B CN109518224 B CN 109518224B
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regulating valve
measuring point
chlorine
pressure
dcs
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CN109518224A (en
Inventor
史万敬
王金峰
叶得强
李刚
于凤刚
沙剑
裴英鸽
苏青天
李雪玲
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Jinchuan Group Chemical New Materials Co ltd
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Jinchuan Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Automation & Control Theory (AREA)
  • Inorganic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Abstract

The invention discloses a caustic soda system emergency PLC control system and process, wherein key process index points of the system are selected, a relay and a switching button are adopted for switching between a DCS control system and a PLC control system in a system fault state, and a PLC control cabinet and a PLC control computer are used for controlling the operation of each key process index point and equipment in the system fault state; the DCS control cabinet and the DCS operating computer control the operation of each key process index point and equipment in a normal state of the system. Aiming at the problem that the system cannot be stopped due to the failure of the DCS in the normal production process of the caustic soda system, the invention scientifically selects key process index points of the system, designs the emergency PLC system, realizes the safe stop of the DCS in the fault state and ensures the life safety and equipment safety in the production process of the system.

Description

Emergency PLC control process for caustic soda system
Technical Field
The invention belongs to the field of chemical processes, relates to a safety guarantee system for a caustic soda device, and particularly relates to an emergency PLC control system and process for a caustic soda system.
Background
The production process of the chlor-alkali system relates to dangerous chemicals such as caustic soda, hydrochloric acid, chlorine, hydrogen and the like, and has harmful factors such as flammability, explosiveness, strong toxicity, corrosion and the like. Because the degree of automation of the system is high, the operation in the production process mostly depends on the DCS system, and therefore, the reliability of the DCS system is very important. Although the existing instrumentation and control technology is very mature, the problems of DCS system faults, such as communication interruption, system failure and the like, are still unavoidable, so that the whole system is in an out-of-control state, even an emergency stop device fails, a great safety risk is brought, equipment is damaged if the equipment is not used, and casualties are caused if the equipment is used. The existing DCS has a single operation way, and cannot provide enough safety guarantee without arranging a separate emergency control system.
Disclosure of Invention
The invention aims to provide an emergency PLC control system which is simple and easy to operate and convenient to operate aiming at the safety risk when a caustic soda DCS system fails, and the safety and the stability of production of the caustic soda system are guaranteed.
The technical scheme adopted by the invention is as follows: an emergent PLC control system of a caustic soda system comprises an electrolytic cell, wherein a dilute brine receiving cell is positioned at the rear end of the electrolytic cell and is connected with a chlorine outlet of the electrolytic cell; the alkali liquor receiving tank is positioned at the rear end of the electrolytic tank and is connected with a chlorine outlet of the electrolytic tank, and a nitrogen purging pipeline is arranged on the alkali liquor receiving tank and is controlled by a nitrogen switch valve; the dilute brine receiving tank is connected with a chlorine compressor through a chlorine main pipe, a first regulating valve for regulating the chlorine pressure of the main pipe and a first switch valve for closing a pipeline in case of failure are arranged on the pipe, a first pressure measuring point is arranged on the pipe in front of the first regulating valve and used for monitoring the pressure of the chlorine main pipe in front of the first regulating valve on line, a pipe section between the first regulating valve and the first switch valve of the pipe is communicated with a tail gas absorption pipeline, and a chlorine emptying regulating valve is arranged on the pipeline;
the alkali liquor receiving tank is connected with a hydrogen compressor through a hydrogen main pipe, and a second regulating valve for regulating the hydrogen pressure of the main pipe and a second switch valve for closing the pipeline during system failure are arranged on the pipe; a second pressure measuring point is arranged on the pipe and positioned in front of the second regulating valve and used for monitoring the pressure of the hydrogen main pipe in front of the second regulating valve on line; a third pressure difference measuring point for measuring the pressure difference between the second pressure measuring point and the first pressure measuring point 5 is arranged between the second pressure measuring point and the first pressure measuring point, and a pipe section on the pipe, which is positioned between the second regulating valve and the second switch valve, is communicated with an emptying pipeline provided with a hydrogen emptying regulating valve;
the operation of the first regulating valve, the first switch valve, the second regulating valve, the second switch valve, the chlorine evacuation regulating valve, the hydrogen evacuation regulating valve, the nitrogen switch valve, the first pressure measuring point, the second pressure measuring point, the third pressure difference measuring point, the electrolytic bath, the chlorine compressor and the hydrogen compressor is controlled by a DCS control cabinet which is matched with a DCS operation computer in a DCS control system;
still be used for the PLC control system who switches with DCS control system during including system fault state, DCS switch board and relay electricity link, the relay links with the switching button electricity, and the switching button links with the PLC switch board electricity that the PLC control computer matched with in the PLC control system and uses.
The emergency PLC control process for the caustic soda system by adopting the system specifically comprises the following steps:
step (1) when the system normally operates, the first regulating valve, the first switch valve, the second regulating valve and the second switch valve are all opened and are in a controllable state, the chlorine emptying regulating valve, the hydrogen emptying regulating valve and the nitrogen switch valve are in a closed state and are in a controllable state, the first pressure measuring point, the second pressure measuring point and the third pressure difference measuring point are displayed normally, the electrolytic cell, the chlorine compressor and the hydrogen compressor operate normally, various data are displayed normally, and the operating signals of the system are transmitted to a DCS control cabinet and then transmitted to a DCS operating computer to operate normally;
step (2), when the operation picture of the DCS operation computer is in fault and the system can not be normally operated, the system operation signal is switched and transmitted to the PLC control cabinet through the relay and the switching button and then transmitted to the PLC control computer, the DCS operation system is thoroughly disconnected, and the caustic soda system is subjected to emergency operation;
step (3), when the switching button is started, the electrolytic cell, the chlorine compressor and the hydrogen compressor stop running, the first switch valve and the second switch valve are automatically closed, and the nitrogen switch valve is automatically opened; the first regulating valve and the chlorine evacuation regulating valve effectively control the pressure of the first pressure measuring point, the second pressure measuring point and the third pressure difference measuring point, and the system safety is guaranteed.
The invention has the beneficial effects that: aiming at the problem that the system cannot be stopped due to the failure of a DCS (distributed control system) in the normal production process of the caustic soda system, the key process index points of the system are scientifically selected and used for switching between the DCS control system and the PLC control system in a system fault state through a relay and a switching button, and the PLC control cabinet and a PLC control computer are used for controlling the operation of each key process index point and equipment in the system fault state; the DCS control cabinet and the DCS operating computer control the operation of each key process index point and equipment in a normal state of the system. By the emergency PLC system, safe shutdown of the DCS in a fault state is realized, and life safety and equipment safety in the system production process are guaranteed.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is an emergency PLC control diagram of the present invention;
in the figure: 1-an electrolytic cell; 2-dilute brine receiving tank; 3-receiving alkali liquor in a tank; 4-nitrogen switch valve; 5-a first pressure measurement point; 6-a second pressure measurement point; 7-a third differential pressure measuring point; 8-a first regulating valve; 9-a first on-off valve; 10-chlorine evacuation regulating valve; 11-a chlorine compressor; 12-a second regulating valve; 13-a second on-off valve; 14-hydrogen evacuation regulating valve; 15-a hydrogen compressor; 16-a relay; 17-a switch button; 18-PLC control cabinet; 19-a DCS control cabinet; 20-PLC control computer; 21-DCS operating computer.
Detailed Description
An emergent PLC control system of a caustic soda system comprises an electrolytic cell 1, wherein a light brine receiving tank 2 is positioned at the rear end of the electrolytic cell 1 and is connected with a chlorine outlet of the electrolytic cell 1; the alkali liquor receiving tank 3 is positioned at the rear end of the electrolytic tank and is connected with a chlorine outlet of the electrolytic tank 1, and a nitrogen purging pipeline is arranged on the alkali liquor receiving tank 3 and is controlled by a nitrogen switch valve 4; the dilute brine receiving tank 2 is connected with a chlorine compressor 11 through a chlorine header pipe, a first regulating valve 8 for regulating the pressure of the chlorine in the header pipe is arranged on the pipe, and a first switch valve 9 for closing the pipe is arranged on the pipe when a system fails, a first pressure measuring point 5 is arranged on the pipe in front of the first regulating valve 8 and used for monitoring the pressure of the chlorine header pipe in front of the first regulating valve 8 on line, the pipe section between the first regulating valve 8 and the first switch valve 9 of the pipe is communicated with a tail gas absorption pipeline, and a chlorine emptying regulating valve 10 is arranged on the pipeline and used for controlling the emptying of the chlorine;
the alkali liquor receiving tank 3 is connected with a hydrogen compressor 15 through a hydrogen main pipe, and a second regulating valve 12 for regulating the hydrogen pressure of the main pipe and a second switch valve 13 for closing the pipeline when a system fails are arranged on the pipe; a second pressure measuring point 6 is arranged on the pipe and positioned in front of the second regulating valve 12 and used for monitoring the pressure of the hydrogen main pipe in front of the second regulating valve 12 on line; and a third pressure difference measuring point 7 for measuring the pressure difference between the second pressure measuring point 6 and the first pressure measuring point 5 is arranged between the first pressure measuring point and the second pressure measuring point. The pipe section of the pipe between the second regulating valve 12 and the second switch valve 13 is communicated with an emptying pipeline provided with a hydrogen emptying regulating valve 14 and used for controlling the emptying of hydrogen;
the operation of the first regulating valve 8, the first switch valve 9, the second regulating valve 12, the second switch valve 13, the chlorine evacuation regulating valve 10, the hydrogen evacuation regulating valve 14, the nitrogen switch valve 4, the first pressure measuring point 5, the second pressure measuring point 6, the third pressure difference measuring point 7, the electrolytic tank 1, the chlorine compressor 11 and the hydrogen compressor 15 is controlled by a DCS control cabinet 19 which is matched with a DCS operating computer 21 in a DCS control system;
still be used for the PLC control system who switches with DCS control system during including system fault state, DCS switch board 19 links with relay 16 electricity, and relay 16 links with switching button 17 electricity, and switching button 17 links with PLC control system in with PLC control system and PLC switch board 18 electricity that cooperatees and use is connected.
Examples
The emergency PLC control process for the caustic soda system by adopting the system specifically comprises the following steps:
step (1) when the system normally operates, the first regulating valve 8, the first switch valve 9, the second regulating valve 12 and the second switch valve 13 are all opened and are in a controllable state, the chlorine evacuation regulating valve 10, the hydrogen evacuation regulating valve 14 and the nitrogen switch valve 4 are in a closed state and are in a controllable state, the first pressure measuring point 5, the second pressure measuring point 6 and the third pressure difference measuring point 7 are in a normal display state, the electrolytic cell 1, the chlorine compressor 11 and the hydrogen compressor 15 are in a normal operation state, and all data are in a normal display state, the operation signals of the system are transmitted to the DCS control cabinet 19 and then transmitted to the DCS operation computer 21 for normal operation;
step (2), when the operation picture of the DCS operation computer 21 is in fault and the system can not be normally operated, the system operation signal is switched and transmitted to the PLC control cabinet 18 through the relay 16 and the switching button 17 and then transmitted to the PLC control computer 20, the DCS operation system is thoroughly disconnected, and the caustic soda system is subjected to emergency operation;
step (3), when the switching button 17 is started, the electrolytic cell 1, the chlorine gas compressor 11 and the hydrogen gas compressor 15 stop running, the first switch valve 9 and the second switch valve 13 are automatically closed, and the nitrogen switch valve 4 is automatically opened; the first regulating valve 8 and the chlorine evacuation regulating valve 10 effectively control the pressure of the first pressure measuring point 5, the second pressure measuring point 6 and the third pressure difference measuring point 7, and the system safety is guaranteed.

Claims (1)

1. The utility model provides a caustic soda system emergency PLC control process, adopts caustic soda system emergency PLC control system, its characterized in that: the system comprises an electrolytic cell, wherein a dilute brine receiving cell is positioned at the rear end of the electrolytic cell and is connected with a chlorine outlet of the electrolytic cell; the alkali liquor receiving tank is positioned at the rear end of the electrolytic tank and is connected with a chlorine outlet of the electrolytic tank, and a nitrogen purging pipeline is arranged on the alkali liquor receiving tank and is controlled by a nitrogen switch valve; the dilute brine receiving tank (2) is connected with a chlorine compressor (11) through a chlorine main pipe, a first regulating valve (8) for regulating the chlorine pressure of the main pipe and a first switch valve (9) for closing a pipeline when a fault occurs are arranged on the pipe, a first pressure measuring point (5) is arranged on the pipe and positioned in front of the first regulating valve (8) and used for monitoring the pressure of the chlorine main pipe in front of the first regulating valve (8) on line, a pipe section between the first regulating valve (8) and the first switch valve (9) of the pipe is communicated with a tail gas absorption pipeline, and a chlorine emptying regulating valve (10) is arranged on the pipeline;
wherein, the alkali liquor receiving tank (3) is connected with a hydrogen compressor (15) through a hydrogen main pipe, and a second regulating valve (12) for regulating the hydrogen pressure of the main pipe and a second switch valve (13) for closing the pipeline when the system fails are arranged on the pipe; a second pressure measuring point (6) is arranged on the pipe and positioned in front of the second regulating valve (12) and used for monitoring the pressure of the hydrogen main pipe in front of the second regulating valve (12) on line; a third pressure difference measuring point (7) for measuring the pressure difference between the second pressure measuring point (6) and the first pressure measuring point (5) is arranged between the second pressure measuring point and the first pressure measuring point, and a pipe section on the pipe, which is positioned between the second regulating valve (12) and the second switch valve (13), is communicated with an emptying pipeline provided with a hydrogen emptying regulating valve (14);
the operation of the first regulating valve (8), the first switch valve (9), the second regulating valve (12), the second switch valve (13), the chlorine evacuation regulating valve (10), the hydrogen evacuation regulating valve (14), the nitrogen switch valve (4), the first pressure measuring point (5), the second pressure measuring point (6), the third pressure difference measuring point (7), the electrolytic cell (1), the chlorine compressor (11) and the hydrogen compressor (15) is controlled by a DCS control cabinet (19) which is matched with a DCS operating computer (21) in a DCS control system;
the system also comprises a PLC control system used for switching with the DCS control system when in a system fault state, wherein the DCS control cabinet (19) is electrically connected with the relay (16), the relay (16) is electrically connected with the switching button (17), and the switching button (17) is electrically connected with a PLC control cabinet (18) which is matched with a PLC control computer (20) in the PLC control system;
the emergency PLC control system is adopted for emergency PLC control, and specifically comprises the following steps:
step (1) when the system normally operates, the first regulating valve (8), the first switch valve (9), the second regulating valve (12) and the second switch valve (13) are all opened and are in a controllable state, the chlorine evacuation regulating valve (10), the hydrogen evacuation regulating valve (14) and the nitrogen switch valve (4) are in a closed state and are in a controllable state, the first pressure measuring point (5), the second pressure measuring point (6) and the third pressure difference measuring point (7) are in a normal display state, the electrolytic cell (1), the chlorine compressor (11) and the hydrogen compressor (15) operate normally, all data are in a normal display state, the operation signals of the system are transmitted to a DCS control cabinet (19) and then transmitted to a DCS operation computer (21) to perform normal operation;
step (2), when an operation picture of a DCS operation computer (21) breaks down and the system cannot be normally operated, a system operation signal is switched and transmitted to a PLC control cabinet (18) through a relay (16) and a switching button (17) and then transmitted to a PLC control computer (20), the DCS operation system is thoroughly disconnected, and emergency operation is carried out on the caustic soda system;
step (3), when the switching button (17) is started, the electrolytic tank (1), the chlorine compressor (11) and the hydrogen compressor (15) stop running, the first switch valve (9) and the second switch valve (13) are automatically closed, and the nitrogen switch valve (4) is automatically opened; the pressure of the first pressure measuring point (5), the pressure of the second pressure measuring point (6) and the pressure of the third pressure difference measuring point (7) are effectively controlled by the first regulating valve (8) and the chlorine evacuation regulating valve (10), and the safety of the system is guaranteed.
CN201811279823.7A 2018-10-30 2018-10-30 Emergency PLC control process for caustic soda system Active CN109518224B (en)

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CN111519208A (en) * 2020-04-21 2020-08-11 新疆中泰创新技术研究院有限责任公司 Electrolytic cell differential pressure control device and method
CN111538357A (en) * 2020-04-21 2020-08-14 新疆中泰创新技术研究院有限责任公司 Single-cell overpressure protection device and method for electrolytic cell
CN116516413B (en) * 2023-07-03 2023-12-12 氢联(江苏)高科技有限公司 Control method and system for multi-tank parallel electrolytic hydrogen production

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US4836903A (en) * 1988-06-17 1989-06-06 Olin Corporation Sodium hydrosulfite electrolytic cell process control system
CN101768753B (en) * 2008-12-29 2011-09-28 河北盛华化工有限公司 Rapid combination method for chlorine gas and hydrogen gas of electrolysis bath
CN102021603A (en) * 2010-09-02 2011-04-20 天辰化工有限公司 Chlorine zero-pressure control method applied to process for preparing alkali by utilizing zero-pole ionic membrane electrolytic cell
CN102681435B (en) * 2011-03-10 2014-04-16 陈丰 Emergency controller based on automatic control system
CN203320134U (en) * 2013-06-30 2013-12-04 金川集团股份有限公司 Chlorine and hydrogen differential pressure adjusting device for ionic membrane electrolytic tank

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Effective date of registration: 20220513

Address after: 737100 No.1 Lanzhou Road, Jinchuan District, Jinchang City, Gansu Province

Patentee after: Jinchuan Group Chemical New Materials Co.,Ltd.

Address before: 737103 No. 98, Jinchuan Road, Jinchang, Gansu

Patentee before: JINCHUAN GROUP Co.,Ltd.