CN117055476A - Safety pre-warning method for vinyl chloride spherical tank in polyvinyl chloride production - Google Patents
Safety pre-warning method for vinyl chloride spherical tank in polyvinyl chloride production Download PDFInfo
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- CN117055476A CN117055476A CN202210489236.0A CN202210489236A CN117055476A CN 117055476 A CN117055476 A CN 117055476A CN 202210489236 A CN202210489236 A CN 202210489236A CN 117055476 A CN117055476 A CN 117055476A
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- vinyl chloride
- spherical tank
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- pressure
- water injection
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- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 title claims abstract description 479
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 39
- 239000004800 polyvinyl chloride Substances 0.000 title claims abstract description 27
- 229920000915 polyvinyl chloride Polymers 0.000 title claims abstract description 26
- 239000007788 liquid Substances 0.000 claims abstract description 253
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 230
- 238000002347 injection Methods 0.000 claims abstract description 151
- 239000007924 injection Substances 0.000 claims abstract description 151
- 238000007599 discharging Methods 0.000 claims abstract description 42
- 238000005507 spraying Methods 0.000 claims abstract description 36
- 238000011084 recovery Methods 0.000 claims abstract description 20
- 238000010992 reflux Methods 0.000 claims abstract description 14
- 238000005520 cutting process Methods 0.000 claims abstract description 5
- 238000004886 process control Methods 0.000 claims abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 130
- 239000007921 spray Substances 0.000 claims description 91
- 229910052757 nitrogen Inorganic materials 0.000 claims description 65
- 238000006116 polymerization reaction Methods 0.000 claims description 33
- 239000007789 gas Substances 0.000 claims description 29
- 230000001105 regulatory effect Effects 0.000 claims description 22
- 238000007789 sealing Methods 0.000 claims description 18
- 230000000630 rising effect Effects 0.000 claims description 15
- 230000002159 abnormal effect Effects 0.000 claims description 13
- 238000012790 confirmation Methods 0.000 claims description 10
- 230000001502 supplementing effect Effects 0.000 claims description 9
- 238000009833 condensation Methods 0.000 claims description 8
- 230000005494 condensation Effects 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 7
- 230000001276 controlling effect Effects 0.000 claims description 6
- 238000003825 pressing Methods 0.000 claims description 6
- 238000003860 storage Methods 0.000 claims description 6
- 230000003111 delayed effect Effects 0.000 claims description 5
- 238000007670 refining Methods 0.000 claims description 5
- 230000003068 static effect Effects 0.000 claims description 5
- CXAFSGPCNGYTOZ-UHFFFAOYSA-N chloroethene hydrate Chemical compound O.ClC=C CXAFSGPCNGYTOZ-UHFFFAOYSA-N 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 3
- 230000018044 dehydration Effects 0.000 claims description 3
- 238000006297 dehydration reaction Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 2
- 238000005070 sampling Methods 0.000 claims description 2
- 239000000047 product Substances 0.000 description 6
- 230000005856 abnormality Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003348 petrochemical agent Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM]
- G05B19/4184—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] characterised by fault tolerance, reliability of production system
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/31—From computer integrated manufacturing till monitoring
- G05B2219/31088—Network communication between supervisor and cell, machine group
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Quality & Reliability (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Polymerisation Methods In General (AREA)
Abstract
The invention relates to a safety precaution method of vinyl chloride spherical tank in polyvinyl chloride production, setting SIS control system and DCS control system independent hardware, software system, setting SIS signal priority at the same time, setting SIS control system and spherical tank liquid level, pressure, temperature meet certain high-low limit index chain, setting SIS vinyl chloride spherical tank liquid level meter A, vinyl chloride spherical tank liquid level meter B and vinyl chloride feed valve B, vinyl chloride discharge valve B chain; a vinyl chloride spherical tank pressure gauge is arranged to be interlocked with a vinyl chloride recovery valve; a chloroethylene temperature display instrument is arranged to be interlocked with a spraying system; the DCS control system is arranged to control the whole process of feeding, discharging, refluxing, tank cutting, water injection, spraying and alarm process control of the three vinyl chloride spherical tanks, the spherical tanks are used as control centers, and the spherical tank feeding system, the spherical tank discharging system, the spherical tank early warning system, the spherical tank water injection system and the spherical tank spraying system are arranged, so that the system is stable in operation, the labor intensity is reduced, the full-automatic operation is realized, and the working efficiency and the safety and reliability are improved.
Description
Technical Field
The invention relates to the technical field of vinyl chloride spherical tank equipment in polyvinyl chloride production, in particular to a safety early warning method for a vinyl chloride spherical tank in polyvinyl chloride production.
Background
In the suspension method polyvinyl chloride (PVC) production process, a great danger source of a vinyl chloride branch plant, namely a vinyl chloride gas cabinet and a spherical tank, is added with a cutting device at an inlet and an outlet, so that safe production is ensured. The method comprises the steps of dewatering, condensing and liquefying crude chloroethylene gas sent from a compression station, fractionating, refining into chloroethylene meeting indexes, dewatering the chloroethylene, sending the chloroethylene to a chloroethylene storage tank, refining the rectified chloroethylene, dewatering the chloroethylene by a chloroethylene dewatering section, sending the chloroethylene to a spherical tank, and sending part of chloroethylene in the spherical tank back to the spherical tank by a chloroethylene feeding pump, and filtering the part of chloroethylene by a chloroethylene filter, and sending the chloroethylene to a polymerization section. The vinyl chloride water injection principle when leakage occurs is as follows: the density of the chloroethylene is 910Kg/m 3 The density of water is 1000Kg/m 3 The density of water is greater than that of liquid vinyl chloride, and the vinyl chloride and water are mutually insoluble, and in general, the bottom of the spherical tank is subjected to emergency water sealing in a bottom pipeline water injection mode. Typically, the above process is operated and controlled using a DCS control system.
In the known control system, a DCS system is Distributed Control System decentralized control system, is a process control system and is real-time and dynamic and needs manual timely intervention, so that human misoperation is possibly caused; the SIS is static, and human intervention is not needed, so that the setting can avoid human misoperation; the SIS control system is Safety Interlocking System (Safety Instrument System) safety interlock system/safety instrumented system abbreviation. SIS is a "static" system. The system is used for monitoring the operation condition of the production device, rapidly processing abnormal working conditions, minimizing the possibility of faults and ensuring that people and the device are in a safe state; under normal working conditions, the device is always monitored to operate, the system output is unchanged, and the production process is not influenced; under abnormal working conditions, the device carries out logic operation according to a pre-designed strategy, so that the production device is safely stopped; DCS is a "dynamic" system. The method is used for continuously detecting, calculating and controlling process variables (continuous, sequential, intermittent and the like), dynamically controlling the production process, ensuring the stable operation of the production device and ensuring the product quality and the product. The SIS has stricter requirements on reliability and usability than the DCS, and the SIS and the DCS hardware are required to be independently arranged in standards such as IEC61508, IEC61511 and the like. Such systems are often used in high-risk industries such as petrochemicals, where once an action is a factory-wide stop, a line of security is ensured.
The problems existing at present are:
1. because the liquid level of the vinyl chloride spherical tank is low, a vinyl chloride pump is empty, equipment and facilities are damaged, and accordingly, the leakage of vinyl chloride is caused to cause fire explosion accidents;
2. when the spherical tank leaks abnormally, most of the operations of filling water at the bottom of the spherical tank are judged and operated by operators according to experience;
3. when the liquid level of the vinyl chloride spherical tank in the original feeding procedure of the polymerization workshop is low, only a simple process alarm prompt is provided, but if the operation is not timely performed by a post operator or the alarm is ignored because the post operator is busy with other steps, equipment and facilities are damaged, and safety accidents occur;
4. the liquid accumulation in the spherical tank can have influence on the vinyl chloride amount of the next process, and coarse material hidden danger is generated;
5. the operation intensity of operators can be increased by the timing pollution discharge of the operators;
6. the method for continuously feeding the spherical tank and setting the pressure and the liquid level by setting the DCS control system is not clear;
7. the on-site spherical tank is extremely serious in consequence of abnormal evacuation once occurring, and leakage of liquid vinyl chloride is possible.
8. Vinyl chloride is inflammable, explosive, volatile and improper in treatment, and can generate potential safety hazards, so that the gas detector is one of important safety control instruments.
Disclosure of Invention
The invention aims to provide a safe production method for vinyl chloride, which is beneficial to storage, safety protection and emergency control of vinyl chloride, in particular to a safe early warning method for a vinyl chloride spherical tank in polyvinyl chloride production in vinyl chloride production.
The technical scheme adopted for solving the technical problems is as follows: a vinyl chloride spherical tank safety pre-warning method in polyvinyl chloride production is provided with an SIS control system and a DCS control system which are independent hardware and software systems, SIS signals are set to be preferential at the same time, the SIS control system is set to be interlocked with a spherical tank liquid level, pressure and temperature meeting certain high and low limit indexes, and an SIS vinyl chloride spherical tank liquid level meter A and a vinyl chloride spherical tank liquid level meter B are set to be interlocked with a vinyl chloride feed valve B and a vinyl chloride discharge valve B; a vinyl chloride spherical tank pressure gauge is arranged to be interlocked with a vinyl chloride recovery valve; a vinyl chloride temperature display instrument is arranged and interlocked with a vinyl chloride feed valve B, a high-pressure spray water valve and a vinyl chloride spherical tank spray system; setting a DCS control system to control the whole process of feeding, discharging, refluxing, tank cutting, water injection and alarm process control of three vinyl chloride spherical tanks, wherein a vinyl chloride spherical tank A is set as a standby recovery spherical tank, and a vinyl chloride spherical tank B/C is set as a polymerization feeding spherical tank; the system comprises a DCS automatic control mode and a manual control mode, wherein the manual control mode is that a central control operation station of a DCS control system opens and closes a static and dynamic equipment valve, a pump and a detection instrument on a spherical tank according to the detection conditions of pressure, liquid level, temperature and a gas detector; the DCS automatic control mode takes a spherical tank as a control center, and five sets of systems are arranged, namely a spherical tank feeding system, a spherical tank discharging system, a spherical tank early warning system, a spherical tank water injection system and a spherical tank spraying system; the vinyl chloride spherical tank starts five sets of systems according to the real-time production condition:
The spherical tank feeding system is used for refining the vinyl chloride after rectifying the vinyl chloride, dehydrating the vinyl chloride in a vinyl chloride dehydration section, and then delivering the vinyl chloride into a vinyl chloride spherical tank, wherein a part of the vinyl chloride is vinyl chloride in a reflux system; when a DCS automatic control mode and a linkage mode are started by a vinyl chloride feed valve A and a vinyl chloride feed valve B in the spherical tank feeding system, the vinyl chloride feed valve A is started to be suddenly stopped by the DCS under control of the DCS, the vinyl chloride feed valve B19 is stopped by the SIS under control of the SIS, a spherical tank liquid level measuring range SL is set, a high reporting liquid level L1 is set, the SIS control system closes the vinyl chloride feed valve B when the high reporting value L1 meets the limiting liquid level or more, and the high reporting liquid level L2 prompts that the alarm information does not link the vinyl chloride feed valve B when the L2 meets the limiting liquid level or more; setting a low report liquid level L3, prompting the alarm information to be not linked with the vinyl chloride discharge valve B when the L3 is smaller than or equal to the limiting liquid level, setting a low report liquid level L4, prompting the alarm information and simultaneously closing the vinyl chloride discharge valve B22 when the L4 is smaller than or equal to the limiting liquid level; the DCS control system respectively closes the vinyl chloride feeding valve A and the vinyl chloride discharging valve A according to the same interlocking condition;
The triggering condition of the SIS control system is met, and the program automatically acts: the vinyl chloride spherical tank 13 liquid level measurement vinyl chloride spherical tank liquid level meter A and the vinyl chloride spherical tank liquid level meter B are both more than or equal to 8.00m, 2 is taken and put into use in a chain way, namely 1 liquid level meter is abnormal, and prompt and alarm are given; and if the 2 liquid level meters are abnormal, the vinyl chloride ball tank vinyl chloride feeding valve B is started to be closed, the auxiliary operating desk lamp is on, and the buzzer sounds.
The emergency operation is manual operation: the emergency stop button of the auxiliary console is pressed, the vinyl chloride feeding valve B of the interlocking vinyl chloride spherical tank is closed, the auxiliary console lamp is on, and the buzzer sounds.
Reset confirmation before normal operation of the operation: if the two conditions are not met, pressing a SIS operation picture reset button in an operation station or an engineer station, and if the auxiliary operation station has the reset button, pressing and confirming; if the reset confirmation is not carried out in the computer, the vinyl chloride feeding valve B of the vinyl chloride spherical tank is opened, the auxiliary operating desk lamp is turned off, and the buzzer does not sound.
Before the normal operation of the operation, the reset confirmation is needed by an operator.
The spherical tank discharging system is characterized in that when DCS automatic control mode is set up to be chloroethyleneThe vinyl ball tank A is a standby recovery ball tank, the vinyl chloride ball tank B/C is a polymerization feeding ball tank, and the vinyl chloride liquid level of each ball tank is greater than 1.5m 3 When the method is used, the polymerization can be fed, namely, a spherical tank discharging system can be started, a vinyl chloride conveying pump is arranged to a conveying flow of a polymerization kettle, a vinyl chloride discharging valve A is arranged to control the emergency stop by a DCS, and a vinyl chloride discharging valve B is arranged to control the emergency stop by a SIS;
the spherical tank discharging system is provided with a vinyl chloride spherical tank liquid level low reporting liquid level L2=1.50m, when the L2 is less than or equal to 1.50m and is delayed for three seconds, a DCS control picture prompts the liquid level low alarm, the continuous delay is carried out for 2 seconds, the liquid level is low and does not rise, an immediate DCS automatic control mode is started to close the spherical tank discharging system, a vinyl chloride discharging valve A, a vinyl chloride discharging valve B, a polymerization kettle and a polymerization kettle vinyl chloride feeding valve, and the polymerization feeding fault is prompted to stop.
The spherical tank early warning system is characterized in that a pressure safety range value, a liquid level safety range value and a temperature safety range value of the vinyl chloride spherical tank are set:
the storage coefficient of the vinyl chloride spherical tank is not more than 85% in the early warning system; in the windy weather with the pressure above thunderstorm or seven levels, the total volume of the vinyl chloride in the vinyl chloride spherical tank is not more than 60% of the total volume; setting the monitoring index of a chloroethylene gas detector within the allowable range, and setting the chloroethylene content of sampling analysis to be less than 0.40%; the information is not satisfied, and emergency and alarm measures are started;
The early warning system detects the pressure safety range value in real time, and sets the pressure high report P1=0.35 Mpa, the pressure high report P2=0.35 Mpa, the pressure low report P2=0.15 Mpa and the pressure low report P2=0.10 Mpa, so that the condition prompting alarm information is met;
the early warning system detects the liquid level safety range value in real time: setting a liquid level height report L1=8.00 m, a height report L2=7.50 m, a low report L3=2.00 m and a low report L4=1.50 m, and meeting the condition and prompting alarm information;
the early warning system detects the temperature safety range value in real time: setting a temperature high report T1=42 ℃, a temperature high report T2=40 ℃, a temperature low report T3= -10 ℃ and a temperature low report T4= -13 ℃ and meeting a condition prompt alarm message;
the spherical tank water injection system comprises a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve, a buffer liquid seal inlet valve, a buffer liquid seal tank, a buffer liquid seal nitrogen maintaining valve, a buffer liquid seal outlet valve, a vinyl chloride spherical tank liquid level meter A, a vinyl chloride spherical tank pressure meter and a vinyl chloride spherical tank liquid level meter B; the buffer liquid seal tank is a central control area, and a spherical tank liquid seal automatic water supplementing chain is arranged, so that the automatic water supplementing chain is generally ensured to be in a use state; ensuring that the liquid level of the buffer liquid seal tank is higher than 0.65m, and setting a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve and a buffer liquid seal inlet valve to be in a closed state; when detecting abnormal leakage of the vinyl chloride spherical tank, a central control personnel confirms leakage of a sealing point at the bottom of the spherical tank again, and starts operation of switching the standby tank of the vinyl chloride spherical tank; and closing the corresponding leakage spherical tank feed cut-off valve, starting the non-leakage vinyl chloride spherical tank feed cut-off valve, and switching the feed to the non-leakage vinyl chloride spherical tank. DCS automatically starts the spherical tank water injection system, switches the spherical tank feed valve, closes the vinyl chloride discharge valve A and the vinyl chloride discharge valve B, opens the spherical tank high-pressure water injection valve, the water injection nitrogen pressure maintaining valve, the water injection regulating valve, the buffer liquid seal inlet valve, the buffer liquid seal nitrogen protection valve and the buffer liquid seal outlet valve, and injects high-pressure fire fighting water into the vinyl chloride spherical tank through pressure difference or nitrogen pressure compensation. Realizing the water seal at the bottom of the vinyl chloride spherical tank and preventing the leakage of liquid vinyl chloride; setting the liquid level rising speed of the leaking spherical tank to be 0.05m/min, judging whether the liquid level rising speed is regularly rising or not, judging whether the liquid level rising speed meets the conditions, if so, the liquid level rising speed shows that the water injection quantity into the spherical tank is larger than the liquid vinyl chloride leakage quantity, controlling the liquid level to be smaller than the height report L1=8.00 m until the water flowing out of the corresponding leaking spherical tank leakage point is all water, after the water injection is finished, after the normal leakage treatment, closing a spherical tank high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve and a buffer liquid seal inlet valve 8, and opening a vinyl chloride spherical tank condensation valve, discharging the water in the spherical tank until the liquid vinyl chloride is discharged, standing for 24 hours, and detecting that the liquid vinyl chloride water content in the corresponding leaking vinyl chloride spherical tank is smaller than 300PPm; and if the condition is not met, repeating the water injection and discharge operation.
The pressure of the corresponding leaking vinyl chloride spherical tank of the water injection system is more than 0.38MPa, and an automatic opening corresponding leaking vinyl chloride spherical tank recovery cut-off valve is arranged;
the pressure of the pipe network of the high-pressure water injection pipe is ensured to be at least more than 0.50 MPa;
the liquid level of the buffer liquid seal tank is higher than 0.65m, so as to ensure continuous effective liquid seal;
the operation station operation picture is matched with an operation panel of 'water injection and use' and 'water injection release';
any valve or system abnormality and alarm described above must be manually released from the alarm condition.
The spherical tank spraying system comprises a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure-maintaining valve, a spray system pressure display instrument, a vinyl chloride spherical tank spraying system and a vinyl chloride gas detector, wherein the vinyl chloride spherical tank spraying system is arranged at the top of a vinyl chloride ball tank, the vinyl chloride gas detector detects in real time, when the volume content of vinyl chloride is more than or equal to 0.50%, a DCS automatically starts the high-pressure spray water pipe, the high-pressure spray water valve, the spray nitrogen pressure-maintaining valve and the vinyl chloride spherical tank spraying system in the spherical tank spraying system until the vinyl chloride gas detector detects that the volume content of vinyl chloride is less than or equal to 0.35%, stops the spraying system, and closes the high-pressure spray water pipe, the high-pressure spray water valve, the spray nitrogen pressure-maintaining valve and the vinyl chloride spherical tank spraying system; when the temperature of the spherical tank is detected to be higher than or equal to 40 ℃ in real time by the system, starting a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure-maintaining valve and a vinyl chloride spherical tank spray system in the spherical tank spray system; stopping the spraying system until the temperature of the spherical tank meets the temperature set value and is less than or equal to 30 ℃.
The safety pre-warning method for the vinyl chloride spherical tank in the polyvinyl chloride production comprises the steps that the SIS control system and the DCS control system are composed of hardware and software, wherein the hardware comprises a site control station, an operation station, an engineer station, a communication network cable and the like; the software comprises an operating system platform and SIS and DCS configuration software for industrial control.
The early warning device comprises a vinyl chloride conveying main pump, a vinyl chloride conveying pump backup pump, a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve, a buffer liquid seal inlet valve, a buffer liquid seal tank, a buffer liquid seal nitrogen maintaining valve, a buffer liquid seal outlet valve, a vinyl chloride spherical tank liquid level meter A, a vinyl chloride spherical tank, a vinyl chloride recovery valve, a vinyl chloride spherical tank pressure meter, a vinyl chloride spherical tank liquid level meter B, a vinyl chloride temperature indicator, a vinyl chloride feed valve A, a vinyl chloride feed valve B, a vinyl chloride reflux valve, a vinyl chloride discharge valve A, a vinyl chloride discharge valve B, a polymerization kettle vinyl chloride feed valve, a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure maintaining valve, a spray system pressure indicator, a vinyl chloride spherical tank spray system, a vinyl chloride gas detector and a spherical tank condensation valve; the components take the vinyl chloride spherical tank as the center, a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve, a buffer liquid seal inlet valve, a buffer liquid seal tank, a buffer liquid seal nitrogen maintaining valve, a buffer liquid seal outlet valve, a vinyl chloride feed valve A, a vinyl chloride feed valve B, a vinyl chloride reflux valve, a vinyl chloride discharge valve A, a vinyl chloride discharge valve B and a spherical tank condensation valve are arranged at the lower part of the vinyl chloride spherical tank, and a vinyl chloride spherical tank liquid level meter A, a vinyl chloride spherical tank liquid level meter B and a vinyl chloride temperature display are arranged at the middle part of the vinyl chloride spherical tank; the top of the vinyl chloride spherical tank is provided with a vinyl chloride recovery valve, a vinyl chloride spherical tank pressure gauge, a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure-maintaining valve, a spray system pressure display instrument, a vinyl chloride spherical tank spray system and a vinyl chloride gas detector; and the vinyl chloride discharge valve A and the vinyl chloride discharge valve B are sequentially connected with a vinyl chloride conveying main pump, a vinyl chloride conveying pump standby pump, a polymerization kettle and a polymerization kettle vinyl chloride feed valve.
The vinyl chloride spherical tank liquid level meter A and the vinyl chloride spherical tank liquid level meter B are arranged in a redundant mode so as to ensure safety and reliability.
The main chloroethylene conveying pump and the auxiliary chloroethylene conveying pump are arranged in a redundant mode so as to ensure safety and reliability.
The buffer liquid seal tank is arranged at the bottom of the vinyl chloride spherical tank, and the inlet of the buffer liquid seal tank is sequentially connected with a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve and a buffer liquid seal inlet valve, and is mainly used for setting the functions of an automatic water supplementing chain of the spherical tank liquid seal and daily micro-leakage manual treatment liquid seal water supplementing, so that the buffer liquid seal tank is safer and more reliable.
The bottom of the buffer liquid seal tank is provided with a buffer liquid seal inlet valve, and the lower part of the tank body side of the buffer liquid seal tank is provided with a buffer liquid seal nitrogen-protecting valve; the top of the device is provided with a buffer liquid seal outlet valve which is connected with a vinyl chloride spherical tank.
The pressure of the high-pressure water injection pipe and the high-pressure spray pipe is kept above 0.50Mpa so as to ensure the pressure during water injection or spraying.
The water injection nitrogen pressure maintaining valve is arranged on the high-pressure water injection pipe and is needed for ensuring the pressure of the water injection system.
The spray nitrogen pressure maintaining valve is arranged on the high-pressure spray water pipe to ensure the pressure during spraying.
Preferably, all pressures and liquid levels on the vinyl chloride spherical tank and the buffer liquid seal tank, the gas detector, the state of the self-control valve and the opening and closing are connected with the DCS control system, so that the operation is more convenient, safe and reliable.
According to the safety pre-warning method for the vinyl chloride spherical tank in the polyvinyl chloride production, in the embodiment, the preset temperature, pressure, liquid level and vinyl chloride content reference values can be taken as many as required by experience, and the specific values have extremely important relations with the size, equipment characteristics and the like of the vinyl chloride spherical tank.
The invention mainly improves the control and hardware devices of the vinyl chloride spherical tank 13, and other devices are the same as the prior art.
Compared with the prior art, the invention provides a safety pre-warning method for a vinyl chloride spherical tank in polyvinyl chloride production, wherein the spherical tank is used as a control center, five sets of systems are arranged, and a liquid level chain is used as a core for controlling the spherical tank feeding system and the spherical tank discharging system respectively; the spherical tank early warning system takes pressure, temperature and liquid level as core linkage indexes; when the spherical tank water injection system leaks abnormally, the spherical tank bottom water injection operation is controlled as a core; the density of water is higher than that of liquid vinyl chloride, and the vinyl chloride and the water are mutually insoluble; the sealing point at the bottom of the vinyl chloride spherical tank is leaked, the water quantity injected into the vinyl chloride spherical tank through a water injection pipeline is larger than or equal to the water quantity flowing out of the leakage point, so that water flows out of the leakage point instead of liquid vinyl chloride, emergency water sealing at the bottom of the vinyl chloride spherical tank is realized, the buffer liquid sealing tank is a spherical tank water injection central control area, a spherical tank liquid sealing automatic water supplementing chain is arranged, and leakage chains are arranged in the same way, so that leakage of liquid vinyl chloride is prevented; the spherical tank spraying system takes the detection index of the gas detector as a spraying start core index, is safe and reliable, is beneficial to the storage, safety protection and emergency control of vinyl chloride, and is especially suitable for a safety early warning method of a vinyl chloride spherical tank in the production of polyvinyl chloride in the production of vinyl chloride, and all the pressure, liquid level, self-control valve state and opening and closing of the vinyl chloride spherical tank are connected with a DCS control system, so that the operation is more convenient, safe and reliable. The control system is displayed on a DCS control system, the core index is controlled in the SIS control system, meanwhile, the SIS control system is independently arranged with independent hardware and software systems of the DCS control system, the operation is stable, the labor intensity is reduced, the full-automatic operation is realized, and the working efficiency and the safety and reliability are improved.
Drawings
FIG. 1 is a schematic view of the apparatus of the present invention.
In fig. 1: 1 is a main chloroethylene conveying pump; 2 is a chloroethylene conveying pump; 3 is a high-pressure water injection pipe; 4 is a high-pressure water injection valve; 5 is a water injection nitrogen pressure maintaining valve; 6 is a water injection regulating valve; 7 is a water injection bypass cut-off valve; 8 is a buffer seal inlet valve; 9 is a buffer sealing tank; 10 is a buffer liquid seal nitrogen protection valve; 11 is a buffer seal outlet valve; 12 is a vinyl chloride spherical tank liquid level meter A;13 is a vinyl chloride spherical tank; 14 is a chloroethylene recovery valve; 15 is a vinyl chloride spherical tank manometer; a 16 chloroethylene spherical tank liquid level meter B;17 is a chloroethylene temperature display; 18 is a vinyl chloride feed valve A;19 is a vinyl chloride feed valve B;20 is a chloroethylene reflux valve; 21 is a chloroethylene discharge valve A;22 is a chloroethylene discharge valve B;23 is a polymerization kettle, 24 is a polymerization kettle vinyl chloride feed valve; 25 is a high-pressure spray water pipe; 26 is a high pressure spray water valve; 27 is a spray nitrogen pressure maintaining valve; 28 is a spray system pressure display; 29 is a vinyl chloride spherical tank spray system; 30 is a chloroethylene gas detector; 31 is a spherical tank dephlegmator valve.
Detailed Description
As shown in figure 1, in the safety pre-warning method of the vinyl chloride spherical tank in the polyvinyl chloride production, an SIS control system and a DCS control system are arranged to be independent hardware and software systems, SIS signals are arranged to be preferential at the same time, the SIS control system is arranged to be interlocked with the liquid level, the pressure and the temperature of the spherical tank to meet certain high and low limit indexes, and an SIS vinyl chloride spherical tank liquid level meter A12 and a vinyl chloride spherical tank liquid level meter B16 are arranged to be interlocked with a vinyl chloride feed valve B19 and a vinyl chloride discharge valve B22; a vinyl chloride spherical tank pressure gauge 15 is arranged to be interlocked with the vinyl chloride recovery valve 14; the vinyl chloride temperature display 17 is arranged to be interlocked with a vinyl chloride feed valve B19, a high-pressure spray water valve 26 and a vinyl chloride spherical tank spray system 29; setting a DCS control system to control the whole process of feeding, discharging, refluxing, tank cutting, water injection and alarm process control of three vinyl chloride spherical tanks, wherein a vinyl chloride spherical tank A is set as a standby recovery spherical tank, and a vinyl chloride spherical tank B/C is set as a polymerization feeding spherical tank; the system comprises a DCS automatic control mode and a manual control mode, wherein the manual control mode is that a central control operation station of a DCS control system opens and closes a static and dynamic equipment valve, a pump and a detection instrument on a spherical tank according to the detection conditions of pressure, liquid level, temperature and a gas detector; the DCS automatic control mode takes a spherical tank as a control center, and five sets of systems are arranged, namely a spherical tank feeding system, a spherical tank discharging system, a spherical tank early warning system, a spherical tank water injection system and a spherical tank spraying system; the vinyl chloride spherical tank starts five sets of systems according to the real-time production condition:
The spherical tank feeding system is used for refining a product obtained after rectifying vinyl chloride, dehydrating the product through a vinyl chloride dehydration section and then delivering the product into a vinyl chloride spherical tank 13, wherein a part of the product is vinyl chloride of a reflux system; when a DCS automatic control mode and a linkage mode are started by a vinyl chloride feed valve A18 and a vinyl chloride feed valve B19 in the spherical tank feeding system, the emergency stop of the spherical tank early warning system is started by the DCS control of the vinyl chloride feed valve A18 and the emergency stop of the vinyl chloride feed valve B19 by the SIS control, a spherical tank liquid level range SL=12.00m is set, a high reporting liquid level L1=8.00m is set, alarm information is prompted when a high reporting value L1 is more than or equal to 8.00m, meanwhile, the SIS control system closes the vinyl chloride feed valve B19, a high reporting liquid level L2=7.50m, and when L2 is more than or equal to 7.50m, alarm information is prompted to not link the vinyl chloride feed valve B19; setting a low reporting liquid level L3=2.00m, when L3 is less than or equal to 2.00m, prompting alarm information to be not linked with the vinyl chloride discharge valve B22, setting a low reporting liquid level L4=1.50m, and when L4 is less than or equal to 1.50m, prompting alarm information to be closed simultaneously; the DCS control system respectively closes the vinyl chloride feeding valve A18 and the vinyl chloride discharging valve A21 according to the same interlocking condition;
the triggering condition of the SIS control system is met, and the program automatically acts: the liquid level of the vinyl chloride spherical tank 13 is measured, the liquid level meter A12 of the vinyl chloride spherical tank and the liquid level meter B16 of the vinyl chloride spherical tank are both more than or equal to 8.00m, 2 is taken and put into use in linkage, namely 1 liquid level meter is abnormal, and prompt and alarm are given; and if the 2 liquid level meters are abnormal, the vinyl chloride ball tank 13 is started to be in linkage use, the vinyl chloride feed valve B19 is closed, the auxiliary operating desk lamp is on, and the buzzer sounds.
The emergency operation is manual operation: the emergency stop button of the auxiliary console is pressed, the vinyl chloride feeding valve B19 of the interlocking vinyl chloride spherical tank 13 is closed, the auxiliary console is on, and the buzzer sounds.
Reset confirmation before normal operation of the operation: if the two conditions are not met, pressing a SIS operation picture reset button in an operation station or an engineer station, and if the auxiliary operation station has the reset button, pressing and confirming; if the reset confirmation is not carried out in the computer, the vinyl chloride feeding valve B19 of the vinyl chloride spherical tank 13 is opened, the auxiliary operating desk lamp is turned off, and the buzzer does not sound.
Before the normal operation of the operation, the reset confirmation is needed by an operator.
The spherical tank discharging system is characterized in that when a DCS automatic control mode is adopted, a vinyl chloride spherical tank A is set as a standby recovery spherical tank, a vinyl chloride spherical tank B/C is set as a polymerization feeding spherical tank, and the vinyl chloride liquid level of each spherical tank is respectively greater than 1.5m 3 When the method is used, polymerization feeding can be performed, namely a spherical tank discharging system can be started, a vinyl chloride conveying pump is arranged to a conveying flow of a polymerization kettle 23, a vinyl chloride discharging valve A21 is arranged to control emergency stop by a DCS, and a vinyl chloride discharging valve B22 is arranged to control emergency stop by an SIS;
the spherical tank discharging system is provided with a vinyl chloride spherical tank 13, the liquid level is low, the liquid level is L < 2 > =1.50 m, when L < 2 > -1.50 m is delayed for three seconds, a DCS control picture prompts a liquid level low alarm, the liquid level is delayed for 2 seconds continuously, the liquid level is low and does not rise, an immediate DCS automatic control mode is started to close the spherical tank discharging system, a vinyl chloride discharging valve A21, a vinyl chloride discharging valve B22, a polymerization kettle 23 and a polymerization kettle vinyl chloride feeding valve 24, and a polymerization feeding fault is prompted to stop.
The spherical tank early warning system is provided with a pressure safety range value, a liquid level safety range value and a temperature safety range value of the vinyl chloride spherical tank 13:
the storage coefficient of the vinyl chloride spherical tank 13 is set to be not more than 85% by the early warning system; in the case of thunderstorm or windy weather with pressure above seven levels, the total volume of vinyl chloride in the vinyl chloride spherical tank 13 should not exceed 60% of the total volume; setting the monitoring index of the vinyl chloride gas detector 30 within the allowable range, and setting the sample analysis vinyl chloride content to be less than 0.40%; the information is not satisfied, and emergency and alarm measures are started;
the early warning system detects the pressure safety range value in real time, and sets the pressure high report P1=0.35 Mpa, the pressure high report P2=0.35 Mpa, the pressure low report P2=0.15 Mpa and the pressure low report P2=0.10 Mpa, so that the condition prompting alarm information is met;
the early warning system detects the liquid level safety range value in real time: setting a liquid level height report L1=8.00 m, a height report L2=7.50 m, a low report L3=2.00 m and a low report L4=1.50 m, and meeting the condition and prompting alarm information;
the early warning system detects the temperature safety range value in real time: setting a temperature high report T1=42 ℃, a temperature high report T2=40 ℃, a temperature low report T3= -10 ℃ and a temperature low report T4= -13 ℃ and meeting a condition prompt alarm message;
the spherical tank water injection system comprises a high-pressure water injection pipe 3, a high-pressure water injection valve 4, a water injection nitrogen pressure maintaining valve 5, a water injection regulating valve 6, a water injection bypass cut-off valve 7, a buffer liquid seal inlet valve 8, a buffer liquid seal tank 9, a buffer liquid seal nitrogen maintaining valve 10, a buffer liquid seal outlet valve 11, a vinyl chloride spherical tank liquid level meter A12, a vinyl chloride spherical tank 13, a vinyl chloride spherical tank pressure meter 15 and a vinyl chloride spherical tank liquid level meter B16; the buffer liquid seal tank 9 is a central control area, and is provided with a spherical tank liquid seal automatic water supplementing chain, so that the automatic water supplementing chain is generally ensured to be in a use state; the liquid level of the buffer liquid seal tank 9 is ensured to be higher than 0.65m, and then a high-pressure water injection valve 4, a water injection nitrogen pressure maintaining valve 5, a water injection regulating valve 6, a water injection bypass cut-off valve 7 and a buffer liquid seal inlet valve 8 are arranged in a closed state; when detecting the abnormal leakage of the vinyl chloride spherical tank 13, the central control personnel confirms the leakage of the sealing point at the bottom of the spherical tank 13 again, and starts the operation of switching the standby vinyl chloride spherical tank; and closing the corresponding leakage spherical tank feed cut-off valve, starting the non-leakage vinyl chloride spherical tank feed cut-off valve, and switching the feed to the non-leakage vinyl chloride spherical tank. DCS automatically starts the spherical tank water injection system, switches the spherical tank feed valve, closes the vinyl chloride discharge valve A21 and the vinyl chloride discharge valve B22, and opens the spherical tank high-pressure water injection valve 4, the water injection nitrogen pressure maintaining valve 5, the water injection regulating valve 6, the buffer liquid seal inlet valve 8, the buffer liquid seal nitrogen protection valve 10 and the buffer liquid seal outlet valve, and injects high-pressure fire-fighting water into the vinyl chloride spherical tank 13 through pressure difference or nitrogen pressure compensation. Realizing the water seal at the bottom of the vinyl chloride spherical tank 13 and preventing the leakage of liquid vinyl chloride; setting the liquid level rising speed of the leaking spherical tank to be 0.05m/1min, judging whether the liquid level rising speed is regularly rising or not, and if the liquid level rising speed meets the condition, the liquid level rising speed indicates that the water injection amount into the spherical tank is larger than the leakage amount of liquid vinyl chloride, controlling the liquid level to be smaller than the height of L1 = 8.00m until all water flowing out of the corresponding leakage point of the leaking spherical tank is water, after the water injection is finished, after the normal leakage treatment, closing the spherical tank high-pressure water injection valve 4, the water injection nitrogen pressure maintaining valve 5, the water injection regulating valve 6 and the buffer liquid seal inlet valve 8, the buffer liquid seal nitrogen preserving valve 10, releasing the water injection linkage, simultaneously opening the condensation valve 31 of the vinyl chloride spherical tank 13, discharging the water in the spherical tank until the liquid vinyl chloride is discharged, standing for 24 hours, and detecting the liquid vinyl chloride water content in the corresponding leaking vinyl chloride spherical tank to be smaller than 300PPm; and if the condition is not met, repeating the water injection and discharge operation.
The pressure of the water injection system corresponding to the leaked vinyl chloride spherical tank 13 is more than 0.38MPa, and an automatic opening corresponding to the leaked vinyl chloride spherical tank recovery cut-off valve is arranged;
the pressure of the pipe network of the high-pressure water injection pipe 3 is ensured to be at least more than 0.50 MPa;
the liquid level of the buffer liquid seal tank 9 is higher than 0.65m, so as to ensure continuous effective liquid seal;
the operation station operation picture is matched with an operation panel of 'water injection and use' and 'water injection release';
any valve or system abnormality and alarm described above must be manually released from the alarm condition.
The spherical tank spraying system comprises a high-pressure spray water pipe 25, a high-pressure spray water valve 26, a spray nitrogen pressure-maintaining valve 27, a spray system pressure display instrument 28, a vinyl chloride spherical tank spraying system 29 and a vinyl chloride gas detector 30, wherein the vinyl chloride spherical tank spraying system 29 is arranged at the top of a vinyl chloride tank 13, the vinyl chloride gas detector 30 detects in real time, when the volume content of vinyl chloride is more than or equal to 0.50%, the DCS automatically starts the high-pressure spray water pipe 25, the high-pressure spray water valve 26, the spray nitrogen pressure-maintaining valve 27 and the vinyl chloride spherical tank spraying system 29 in the spherical tank spraying system until the volume content of vinyl chloride detected by the vinyl chloride gas detector is less than or equal to 0.35%, and stops the spraying system; when the system detects the temperature of the spherical tank 13 in real time and the temperature of the spherical tank is higher than or equal to 40 ℃, starting a high-pressure spray water pipe 25, a high-pressure spray water valve 26, a spray nitrogen pressure-maintaining valve 27 and a vinyl chloride spherical tank spray system 29 in the spherical tank spray system; stopping the spraying system until the temperature of the spherical tank meets the temperature set value and is less than or equal to 30 ℃.
The safety pre-warning method for the vinyl chloride spherical tank in the polyvinyl chloride production comprises the steps that the SIS control system and the DCS control system are composed of hardware and software, wherein the hardware comprises a site control station, an operation station, an engineer station, a communication network cable and the like; the software comprises an operating system platform and SIS and DCS configuration software for industrial control.
The early warning device comprises a vinyl chloride conveying main pump 1, a vinyl chloride conveying pump backup pump 2, a high-pressure water injection pipe 3, a high-pressure water injection valve 4, a water injection nitrogen pressure maintaining valve 5, a water injection regulating valve 6, a water injection bypass cut-off valve 7, a buffer liquid seal inlet valve 8, a buffer liquid seal tank 9, a buffer liquid seal nitrogen maintaining valve 10, a buffer liquid seal outlet valve 11, a vinyl chloride spherical tank liquid level meter A12, a vinyl chloride spherical tank 13, a vinyl chloride recovery valve 14, a vinyl chloride spherical tank pressure meter 15, a vinyl chloride spherical tank liquid level meter B16, a vinyl chloride temperature display 17, a vinyl chloride feed valve A18, a vinyl chloride feed valve B19, a vinyl chloride reflux valve 20, a vinyl chloride discharge valve A21, a vinyl chloride discharge valve B22, a spray pot 23, a polymeric kettle vinyl chloride feed valve 24, a high-pressure spray water pipe 25, a high-pressure spray water valve 26, a spray nitrogen pressure maintaining valve 27, a spray system pressure display 28, a vinyl chloride spherical tank system 29, a vinyl chloride gas detector 30, and a spherical tank spray valve 31; the components are centered on the vinyl chloride spherical tank 13, and a high-pressure water injection pipe 3, a high-pressure water injection valve 4, a water injection nitrogen pressure maintaining valve 5, a water injection regulating valve 6, a water injection bypass cut-off valve 7, a buffer seal inlet valve 8, a buffer seal tank 9, a buffer seal nitrogen retaining valve 10, a buffer seal outlet valve 11, a vinyl chloride feed valve A18, a vinyl chloride feed valve B19, a vinyl chloride reflux valve 20, a vinyl chloride discharge valve A21, a vinyl chloride discharge valve B22 and a spherical tank condensation valve 31 are arranged at the lower part of the vinyl chloride spherical tank 13; the middle part of the vinyl chloride spherical tank 13 is provided with a vinyl chloride spherical tank liquid level meter A12, a vinyl chloride spherical tank liquid level meter B16 and a vinyl chloride temperature display 17; the top of the vinyl chloride spherical tank 13 is provided with a vinyl chloride recovery valve 14, a vinyl chloride spherical tank pressure gauge 15, a high-pressure spray water pipe 25, a high-pressure spray water valve 26, a spray nitrogen pressure maintaining valve 27, a spray system pressure display instrument 28, a vinyl chloride spherical tank spray system 29 and a vinyl chloride gas detector 30; the vinyl chloride discharge valve A21 and the vinyl chloride discharge valve B22 are sequentially connected with the vinyl chloride conveying main pump 1, the vinyl chloride conveying pump standby pump 2, the polymerization kettle 23 and the polymerization kettle vinyl chloride feed valve 24.
The vinyl chloride spherical tank liquid level meter A12 and the vinyl chloride spherical tank liquid level meter B16 are arranged in a redundant mode so as to ensure safety and reliability.
The main chloroethylene conveying pump 1 and the spare chloroethylene conveying pump 2 are arranged in a redundant mode so as to ensure safety and reliability.
The buffer liquid seal tank 9 is arranged at the bottom of the vinyl chloride spherical tank 13, and the inlet of the buffer liquid seal tank is sequentially connected with the high-pressure water injection pipe 3, the high-pressure water injection valve 4, the water injection nitrogen pressure maintaining valve 5, the water injection regulating valve 6, the water injection bypass cut-off valve 7 and the buffer liquid seal inlet valve 8, and is mainly used for setting the functions of automatic water supplement interlocking and daily micro-leakage manual liquid seal water supplement of the spherical tank liquid seal, so that the buffer liquid seal tank is safer and more reliable.
The bottom of the buffer liquid seal tank 9 is provided with a buffer liquid seal inlet valve 8, and the lower part of the tank body side is provided with a buffer liquid seal nitrogen protection valve 10; the top of the device is provided with a buffer liquid sealing outlet valve 11 which is connected with a vinyl chloride spherical tank 13.
The pressure of the high-pressure water injection pipe 3 and the high-pressure spray water pipe 25 is kept above 0.50Mpa so as to ensure the pressure during water injection or spraying.
The water injection nitrogen pressure maintaining valve 5 is arranged on the high-pressure water injection pipe 3 and is needed for ensuring the pressure of the water injection system.
The spray nitrogen pressure maintaining valve 27 is arranged on the high-pressure spray water pipe 25 to ensure the pressure during spraying.
Preferably, all the pressure, the liquid level, the gas detector, the self-control valve state and the opening and closing of the vinyl chloride spherical tank 13 and the buffer liquid seal tank 9 are connected with the DCS control system, so that the operation is more convenient, safe and reliable.
According to the safety pre-warning method for the vinyl chloride spherical tank in the polyvinyl chloride production, in the embodiment, the preset temperature, pressure, liquid level and vinyl chloride content reference values can be taken as many as required by experience, and the specific values have extremely important relations with the size, equipment characteristics and the like of the vinyl chloride spherical tank.
The invention mainly improves the control and hardware devices of the vinyl chloride spherical tank 13, has very effective effect on the safety early warning, and is the same as the prior art.
Claims (12)
1. A safety pre-warning method for a vinyl chloride spherical tank in polyvinyl chloride production is characterized in that an SIS control system and a DCS control system are arranged to be independent hardware and software systems, SIS signals are arranged to be preferential at the same time, the SIS control system is arranged to be interlocked with a spherical tank liquid level, pressure and temperature meeting certain high and low limit indexes, and an SIS vinyl chloride spherical tank liquid level meter A and a vinyl chloride spherical tank liquid level meter B are arranged to be interlocked with a vinyl chloride feed valve B and a vinyl chloride discharge valve B; a vinyl chloride spherical tank pressure gauge is arranged to be interlocked with a vinyl chloride recovery valve; a vinyl chloride temperature display instrument is arranged and interlocked with a vinyl chloride feed valve B, a high-pressure spray water valve and a vinyl chloride spherical tank spray system; setting a DCS control system to control the whole process of feeding, discharging, refluxing, tank cutting, water injection, spraying and alarm process control of three vinyl chloride spherical tanks, wherein a vinyl chloride spherical tank A is set as a standby recovery spherical tank, and a vinyl chloride spherical tank B/C is set as a polymerization feeding spherical tank; the system comprises a DCS automatic control mode and a manual control mode, wherein the manual control mode is that a central control operation station of a DCS control system opens and closes a static and dynamic equipment valve, a pump and a detection instrument on a spherical tank according to the detection conditions of pressure, liquid level, temperature and a gas detector; the DCS automatic control mode takes a spherical tank as a control center, and five sets of systems are arranged, namely a spherical tank feeding system, a spherical tank discharging system, a spherical tank early warning system, a spherical tank water injection system and a spherical tank spraying system; the vinyl chloride spherical tank starts five sets of systems according to the real-time production condition:
The spherical tank feeding system is used for refining the vinyl chloride after rectifying the vinyl chloride, dehydrating the vinyl chloride in a vinyl chloride dehydration section, and then delivering the vinyl chloride into a vinyl chloride spherical tank, wherein a part of the vinyl chloride is vinyl chloride in a reflux system; when a DCS automatic control mode and a linkage mode are started by a vinyl chloride feed valve A and a vinyl chloride feed valve B in the spherical tank feeding system, the vinyl chloride feed valve A is started to be suddenly stopped by the DCS under control of the DCS, the vinyl chloride feed valve B19 is stopped by the SIS under control of the SIS, a spherical tank liquid level measuring range SL is set, a high reporting liquid level L1 is set, the SIS control system closes the vinyl chloride feed valve B when the high reporting value L1 meets the limiting liquid level or more, and the high reporting liquid level L2 prompts that the alarm information does not link the vinyl chloride feed valve B when the L2 meets the limiting liquid level or more; setting a low report liquid level L3, prompting the alarm information to be not linked with the vinyl chloride discharge valve B when the L3 is smaller than or equal to the limiting liquid level, setting a low report liquid level L4, prompting the alarm information and simultaneously closing the vinyl chloride discharge valve B22 when the L4 is smaller than or equal to the limiting liquid level; the DCS control system respectively closes the vinyl chloride feeding valve A and the vinyl chloride discharging valve A according to the same interlocking condition;
The triggering condition of the SIS control system is met, and the program automatically acts: the vinyl chloride spherical tank 13 liquid level measurement vinyl chloride spherical tank liquid level meter A and the vinyl chloride spherical tank liquid level meter B are both more than or equal to 8.00m, 2 is taken and put into use in a chain way, namely 1 liquid level meter is abnormal, and prompt and alarm are given; if the 2 liquid level meters are abnormal, the vinyl chloride ball tank vinyl chloride feeding valve B is started to be closed, the auxiliary operating desk lamp is on, and the buzzer sounds;
the emergency operation is manual operation: an emergency stop button of the auxiliary console is pressed, a vinyl chloride feeding valve B of the linked vinyl chloride spherical tank is closed, the auxiliary console lamp is on, and a buzzer sounds;
reset confirmation before normal operation of the operation: if the two conditions are not met, pressing a SIS operation picture reset button in an operation station or an engineer station, and if the auxiliary operation station has the reset button, pressing and confirming; if the reset confirmation is not carried out in the computer, the vinyl chloride feeding valve B of the vinyl chloride spherical tank is opened, the auxiliary operating desk lamp is turned off, and the buzzer does not sound;
before the normal operation of the operation, the reset confirmation is carried out, and an operator needs to carry out manual reset confirmation;
the spherical tank discharging system is characterized in that when a DCS automatic control mode is adopted, a vinyl chloride spherical tank A is set as a standby recovery spherical tank, a vinyl chloride spherical tank B/C is set as a polymerization feeding spherical tank, and the vinyl chloride liquid level of each spherical tank is respectively greater than 1.5m 3 When the method is used, the polymerization can be fed, namely, a spherical tank discharging system can be started, a vinyl chloride conveying pump is arranged to a conveying flow of a polymerization kettle, a vinyl chloride discharging valve A is arranged to control the emergency stop by a DCS, and a vinyl chloride discharging valve B is arranged to control the emergency stop by a SIS;
the spherical tank discharging system is provided with a vinyl chloride spherical tank liquid level low reporting liquid level L2=1.50m, when the L2 is less than or equal to 1.50m and is delayed for three seconds, a DCS control picture prompts the liquid level low alarm, the liquid level is delayed for 2 seconds continuously, the liquid level is low and does not rise, an immediate DCS automatic control mode is started to close the spherical tank discharging system, a vinyl chloride discharging valve A, a vinyl chloride discharging valve B, a polymerization kettle and a polymerization kettle vinyl chloride feeding valve, and prompts the polymerization feeding failure to stop;
the spherical tank early warning system is characterized in that a pressure safety range value, a liquid level safety range value and a temperature safety range value of the vinyl chloride spherical tank are set:
the storage coefficient of the vinyl chloride spherical tank is not more than 85% in the early warning system; in the windy weather with the pressure above thunderstorm or seven levels, the total volume of the vinyl chloride in the vinyl chloride spherical tank is not more than 60% of the total volume; setting the monitoring index of a chloroethylene gas detector within the allowable range, and setting the chloroethylene content of sampling analysis to be less than 0.40%; the information is not satisfied, and emergency and alarm measures are started;
The early warning system detects the pressure safety range value in real time, and sets the pressure high report P1=0.35 Mpa, the pressure high report P2=0.35 Mpa, the pressure low report P2=0.15 Mpa and the pressure low report P2=0.10 Mpa, so that the condition prompting alarm information is met;
the early warning system detects the liquid level safety range value in real time: setting a liquid level height report L1=8.00 m, a height report L2=7.50 m, a low report L3=2.00 m and a low report L4=1.50 m, and meeting the condition and prompting alarm information;
the early warning system detects the temperature safety range value in real time: setting a temperature high report T1=42 ℃, a temperature high report T2=40 ℃, a temperature low report T3= -10 ℃ and a temperature low report T4= -13 ℃ and meeting a condition prompt alarm message;
the spherical tank water injection system comprises a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve, a buffer liquid seal inlet valve, a buffer liquid seal tank, a buffer liquid seal nitrogen maintaining valve, a buffer liquid seal outlet valve, a vinyl chloride spherical tank liquid level meter A, a vinyl chloride spherical tank pressure meter and a vinyl chloride spherical tank liquid level meter B; the buffer liquid seal tank is a central control area, and a spherical tank liquid seal automatic water supplementing chain is arranged, so that the automatic water supplementing chain is generally ensured to be in a use state; ensuring that the liquid level of the buffer liquid seal tank is higher than 0.65m, and setting a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve and a buffer liquid seal inlet valve to be in a closed state; when detecting the abnormal leakage of the vinyl chloride spherical tank 13, the central control personnel confirms the leakage of the sealing point at the bottom of the spherical tank again, and starts the operation of switching the standby tank of the vinyl chloride spherical tank; closing the corresponding leakage spherical tank feeding cut-off valve, starting the non-leakage vinyl chloride spherical tank feeding cut-off valve, and switching the feeding to the non-leakage vinyl chloride spherical tank; the DCS automatically starts a spherical tank water injection system, switches a spherical tank feed valve, closes a vinyl chloride discharge valve A and a vinyl chloride discharge valve B, opens a vinyl chloride reflux valve, opens a spherical tank high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a buffer liquid seal inlet valve, a buffer liquid seal nitrogen protection valve and a buffer liquid seal outlet valve, and injects high-pressure fire fighting water into the vinyl chloride spherical tank through pressure difference or nitrogen pressure compensation; realizing the water seal at the bottom of the vinyl chloride spherical tank and preventing the leakage of liquid vinyl chloride; setting the liquid level rising speed of the leaking spherical tank to be 0.05m/min, judging whether the liquid level rising speed is regularly rising or not, judging whether the liquid level rising speed meets the condition, then, the spherical tank liquid level rising indicates that the water injection quantity into the spherical tank is larger than the liquid vinyl chloride leakage quantity, controlling the liquid level to be smaller than the height report L1=8.00 m until all water flowing out of the corresponding leaking spherical tank leakage point is water, after the water injection is finished, after the leaking treatment is normal, closing a spherical tank high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve and a buffer liquid seal inlet valve, releasing the water injection linkage, simultaneously, opening a vinyl chloride spherical tank condensation valve, discharging water in the spherical tank until the liquid vinyl chloride is discharged, standing for 24 hours, and detecting that the liquid vinyl chloride water content in the corresponding leaking vinyl chloride spherical tank is smaller than 300PPm; if the condition is not met, repeating the water injection and discharge operation;
The pressure of the corresponding leaking vinyl chloride spherical tank of the water injection system is more than 0.38MPa, and an automatic opening corresponding leaking vinyl chloride spherical tank recovery cut-off valve is arranged;
the pressure of the pipe network of the high-pressure water injection pipe is ensured to be at least more than 0.50 MPa;
the liquid level of the buffer liquid seal tank is higher than 0.65m, so as to ensure continuous effective liquid seal;
the operation station operation picture is matched with an operation panel of 'water injection and use' and 'water injection release';
any valve or system is abnormal and alarms, and the alarm state must be manually released;
the spherical tank spraying system comprises a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure-maintaining valve, a spray system pressure display instrument, a vinyl chloride spherical tank spraying system and a vinyl chloride gas detector, wherein the vinyl chloride spherical tank spraying system is arranged at the top of a vinyl chloride ball tank, the vinyl chloride gas detector detects in real time, when the volume content of vinyl chloride is more than or equal to 0.50%, a DCS automatically starts the high-pressure spray water pipe, the high-pressure spray water valve, the spray nitrogen pressure-maintaining valve and the vinyl chloride spherical tank spraying system in the spherical tank spraying system until the vinyl chloride gas detector detects that the volume content of vinyl chloride is less than or equal to 0.35%, stops the spraying system, and closes the high-pressure spray water pipe, the high-pressure spray water valve, the spray nitrogen pressure-maintaining valve and the vinyl chloride spherical tank spraying system; when the temperature of the spherical tank is detected to be higher than or equal to 40 ℃ in real time by the system, starting a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure-maintaining valve and a vinyl chloride spherical tank spray system in the spherical tank spray system; stopping the spraying system until the temperature of the spherical tank meets the temperature set value and is less than or equal to 30 ℃.
2. The method for pre-warning the safety of a vinyl chloride spherical tank in the production of polyvinyl chloride according to claim 1, wherein the SIS control system and the DCS control system are provided with independent hardware and software systems, and the hardware comprises a site control station, an operation station, an engineer station, a communication network cable and the like; the software comprises an operating system platform and SIS and DCS configuration software for industrial control.
3. The method for pre-warning the safety of a vinyl chloride spherical tank in the production of polyvinyl chloride according to claim 1, wherein the preset temperature, pressure, liquid level and vinyl chloride content reference values can be taken as a plurality of values according to experience requirements, and the specific values have extremely important relations with the size, equipment characteristics and the like of the vinyl chloride spherical tank.
4. The early warning device realized by the vinyl chloride spherical tank safety early warning method in the production of the polyvinyl chloride according to claim 1 is characterized in that the device comprises a vinyl chloride conveying main pump, a vinyl chloride conveying pump backup pump, a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve, a buffer liquid sealing inlet valve, a buffer liquid sealing tank, a buffer liquid sealing nitrogen retaining valve, a buffer liquid sealing outlet valve, a vinyl chloride spherical tank liquid level meter A, a vinyl chloride spherical tank, a vinyl chloride recovery valve, a vinyl chloride spherical tank pressure gauge, a vinyl chloride spherical tank liquid level meter B, a vinyl chloride temperature indicator, a vinyl chloride feed valve A, a vinyl chloride feed valve B, a vinyl chloride return valve, a vinyl chloride discharge valve A, a vinyl chloride discharge valve B, a polymerization kettle vinyl chloride feed valve, a high-pressure spray pipe, a high-pressure spray water valve, a nitrogen pressure maintaining valve, a spray system pressure indicator, a vinyl chloride spherical tank system, a vinyl chloride gas detector and a spherical tank condensation valve; the components take the vinyl chloride spherical tank as the center, and a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve, a buffer liquid seal inlet valve, a buffer liquid seal tank, a buffer liquid seal nitrogen maintaining valve, a buffer liquid seal outlet valve, a vinyl chloride feeding valve A, a vinyl chloride feeding valve B, a vinyl chloride reflux valve, a vinyl chloride discharging valve A, a vinyl chloride discharging valve B and a spherical tank condensation discharging valve are arranged at the lower part of the vinyl chloride spherical tank; the middle part of the vinyl chloride spherical tank is provided with a vinyl chloride spherical tank liquid level meter A, a vinyl chloride spherical tank liquid level meter B and a vinyl chloride temperature display instrument; the top of the vinyl chloride spherical tank is provided with a vinyl chloride recovery valve, a vinyl chloride spherical tank pressure gauge, a high-pressure spray water pipe, a high-pressure spray water valve, a spray nitrogen pressure-maintaining valve, a spray system pressure display instrument, a vinyl chloride spherical tank spray system and a vinyl chloride gas detector; and the vinyl chloride discharge valve A and the vinyl chloride discharge valve B are sequentially connected with a vinyl chloride conveying main pump, a vinyl chloride conveying pump standby pump, a polymerization kettle and a polymerization kettle vinyl chloride feed valve.
5. The pre-warning device for realizing the safety pre-warning method of the vinyl chloride spherical tank in the production of the polyvinyl chloride according to claim 4, wherein the vinyl chloride spherical tank liquid level meter A and the vinyl chloride spherical tank liquid level meter B are arranged in a redundant mode.
6. The pre-warning device for realizing the safety pre-warning method for the vinyl chloride spherical tank in the production of the polyvinyl chloride according to claim 4, wherein the main vinyl chloride conveying pump and the auxiliary vinyl chloride conveying pump are arranged in a redundant mode.
7. The early warning device for realizing the safety early warning method for the vinyl chloride spherical tank in the production of the polyvinyl chloride according to claim 4, wherein the buffer liquid sealing tank is arranged at the bottom of the vinyl chloride spherical tank, and the inlet of the buffer liquid sealing tank is sequentially connected with a high-pressure water injection pipe, a high-pressure water injection valve, a water injection nitrogen pressure maintaining valve, a water injection regulating valve, a water injection bypass cut-off valve and a buffer liquid sealing inlet valve.
8. The early warning device for realizing the safety early warning method of the vinyl chloride spherical tank in the production of the polyvinyl chloride according to claim 4, wherein the buffer liquid seal tank is provided with a buffer liquid seal inlet valve at the bottom and a buffer liquid seal nitrogen protection valve at the lower part of the tank body side; the top of the device is provided with a buffer liquid seal outlet valve which is connected with a vinyl chloride spherical tank.
9. The device for realizing the safety precaution method for the vinyl chloride spherical tank in the production of polyvinyl chloride according to claim 4, wherein the pressure of the high-pressure water injection pipe and the high-pressure spray water pipe is kept above 0.50 Mpa.
10. The device for realizing the safety precaution method for the vinyl chloride spherical tank in the production of polyvinyl chloride according to claim 4, wherein the water injection nitrogen pressure maintaining valve is arranged on the high-pressure water injection pipe.
11. The pre-warning device for realizing the safety pre-warning method for the vinyl chloride spherical tank in the production of polyvinyl chloride according to claim 4, wherein the spray nitrogen pressure-maintaining valve is arranged on a high-pressure spray water pipe.
12. The pre-warning device for realizing the safety pre-warning method for the vinyl chloride spherical tank in the production of the polyvinyl chloride according to claim 4, wherein all the pressure and the liquid level on the vinyl chloride spherical tank and the buffer liquid sealing tank, the gas detector, the self-control valve state and the opening and closing are connected with a DCS control system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210489236.0A CN117055476A (en) | 2022-05-07 | 2022-05-07 | Safety pre-warning method for vinyl chloride spherical tank in polyvinyl chloride production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210489236.0A CN117055476A (en) | 2022-05-07 | 2022-05-07 | Safety pre-warning method for vinyl chloride spherical tank in polyvinyl chloride production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117055476A true CN117055476A (en) | 2023-11-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210489236.0A Pending CN117055476A (en) | 2022-05-07 | 2022-05-07 | Safety pre-warning method for vinyl chloride spherical tank in polyvinyl chloride production |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117055476A (en) |
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2022
- 2022-05-07 CN CN202210489236.0A patent/CN117055476A/en active Pending
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