Method for preventing the accidental opening of a feed valve of a reaction vessel and reaction vessel control system

Abstract

The present application provides a method for preventing the misoperation of the feed valve of a reaction kettle and a reaction kettle control system, the method comprising: before the reaction gas is introduced, according to preset detection conditions, cutting off or connecting the instrument air main pipe by controlling the valve, the instrument air main pipe being connected with all the feed valves of the reaction kettle, the control valve being connected with the instrument air main pipe; after the reaction gas is introduced, controlling the gap feeding of the reaction kettle, monitoring the pressure in the reaction kettle, and closing all the feed valves of the reaction kettle in the case of high pressure. The method of the present application solves the technical problem of the loss caused by the misoperation of the batch feeding valve in the prior art, and for the high-pressure reaction kettle with multiple batch feeding pipelines, the method provided by the present application can effectively prevent the misoperation of the personnel from causing the misoperation of the feed valve and the occurrence of the reverse flow condition, and the protection method provided by the present application greatly improves the working condition protection while saving the cost of the working condition protection.

Description

Technical Field

[0001] This invention relates to the chemical industry, and more particularly to a method for preventing the accidental opening of the feed valve of a reactor and a reactor control system. Background Technology

[0002] In existing technologies, high-pressure reaction systems involve numerous feeding valves, increasing the likelihood of valve malfunction. Misoperation of batch feeding valves often has serious consequences for safety and production, and accidental opening of batch feeding valves by personnel is one of the causes of backflow. If a feeding valve is accidentally opened during the reaction process, high-pressure materials in the reactor may flow back into the raw material storage tank, potentially causing overpressure rupture. This potential hazard cannot be avoided solely through improved management measures and requires improvements to existing technologies. Summary of the Invention

[0003] Based on the above problems, this invention proposes a method and a reactor control system to prevent accidental opening of the feed valve. This solves the technical problem of safety and production losses caused by misoperation of batch feed valves in the prior art. For high-pressure reactors with multiple batch feed pipelines, the method provided by this invention can effectively prevent backflow caused by accidental opening of the feed valve due to human error. The protection method provided by this invention greatly improves the protection of operating conditions while saving the cost of operating condition protection.

[0004] This invention proposes a method for preventing the feed valve of a reactor from being accidentally opened, comprising:

[0005] At least one control valve is installed on the instrument air main of the feed valve of the reactor. Judgment conditions and corresponding execution actions are added to the sequential control program of the reactor. The reactor adopts DCS logic to prevent the feed valve from being opened when the internal pressure of the reactor is high. The feed valve of the reactor is fed intermittently.

[0006] In addition, the control valve is a three-way solenoid valve, which is connected in series to the instrument air main pipe.

[0007] In addition, the installation of at least one control valve on the instrument air main of the feed valve of the reactor includes:

[0008] Two three-way solenoid valves are connected in series to the instrument air main of the feed valve of the reactor, and the two three-way solenoid valves are connected in front of the pressure transmitter of the instrument air main.

[0009] Furthermore, adding judgment conditions and corresponding execution actions to the sequential control program of the reactor includes:

[0010] Add the following to the sequential control procedure: close the control valve and all feed valves after the raw material feeding is completed and before the reaction gas is added.

[0011] Furthermore, adding judgment conditions and corresponding execution actions to the sequential control program of the reactor includes:

[0012] The following is added to the sequential control program: If the control valve and all feed valves are detected to be closed before the reaction gas is introduced into the reactor, then the introduction of reaction gas is permitted.

[0013] Furthermore, adding judgment conditions and corresponding execution actions to the sequential control program of the reactor includes:

[0014] If the pressure value of the instrument air main pipe is detected to be greater than a preset threshold before the reaction gas is introduced into the reactor, the introduction of reaction gas is not allowed.

[0015] Furthermore, adding judgment conditions and corresponding execution actions to the sequential control program of the reactor includes:

[0016] If the bypasses of the feed valve with protective functions are all closed before the reaction gas is introduced into the reactor, then the introduction of the reaction gas is permitted.

[0017] The present invention also proposes a reaction vessel employing the method described in any of the preceding claims for preventing accidental opening of the reaction vessel feed valve.

[0018] In addition, the reactor is a hydrogen reactor or a polymerization reactor.

[0019] The present invention also proposes a reactor control system, which employs the method described in any of the preceding claims to prevent accidental opening of the reactor feed valve.

[0020] This invention solves the technical problem of safety and production losses caused by misoperation of batch feeding valves in the prior art. For high-pressure reactors with multiple batch feeding pipelines, the method provided by this invention can effectively prevent backflow caused by accidental opening of feeding valves due to human error. The protection method provided by this invention greatly improves the protection of operating conditions while saving the cost of operating condition protection. Attached Figure Description

[0021] Figure 1 A schematic diagram illustrating the working principle of a reactor after adding a control valve, according to one embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the working principle of a reactor using DCS logic in existing technology;

[0023] Figure 3 This is a schematic diagram of the working principle of a reactor using SIS interlocking in the existing technology. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. This description is intended only to illustrate specific embodiments of the invention and does not constitute any limitation on the invention. The scope of protection of the invention is defined by the claims.

[0025] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. This description is intended only to illustrate specific embodiments of the invention and does not constitute any limitation on the invention. The scope of protection of the invention is defined by the claims.

[0026] Reference Figure 1 This invention proposes a method to prevent the feed valve of a reactor from being accidentally opened, comprising:

[0027] Before introducing the reaction gas, the instrument air main is cut off or connected by the control valve according to the preset detection conditions. The instrument air main is connected to all the feed valves of the reactor, and the control valve is connected to the instrument air main.

[0028] After the reaction gas is introduced, the feed is controlled at intervals in the reactor, and the pressure inside the reactor is monitored. If the pressure is too high, all feed valves of the reactor are closed.

[0029] Preset detection conditions include, for example, checking whether the feeding of raw materials has ended before the addition of reaction gas begins. This detection ensures that all feed valves are closed when reaction gas is introduced and during the reaction, thereby guaranteeing safe production even under high pressure conditions.

[0030] At least one control valve can be installed on the instrument air main of the reactor's feed valve by controlling the valve to cut off or connect it. Judgment conditions and corresponding actions are added to the reactor's sequential control program. Specifically, the reactor uses DCS logic to prevent the feed valve from opening when the internal pressure of the reactor is high, and the feed valve of the reactor uses intermittent feeding.

[0031] The following compares the technical solutions provided by the present invention with those provided by existing technologies for preventing the raw material feed valve from being opened when the pressure inside the reactor is high:

[0032] The following analysis uses a hydrogenation reactor with batch feeding and sequential batch operation to complete the feeding of reactants, followed by pressurization of hydrogen gas into the reactor for hydrogenation reaction. The operating pressure is 4 MPaG, and the operating temperature is 70°C. The analysis addresses the scenario where human error leads to the accidental opening of the feed valve during the hydrogenation reaction. Considering different levels of protection measures, the analysis delves into the likelihood of valve accidental opening in the event of protection failure, thereby demonstrating the economic efficiency and safety of this invention.

[0033] Comparative Example 1: Taking the use of DCS logic in a reactor as an example, this explains why the feed valve is not allowed to be opened when the pressure inside the reactor is high. DCS logic is short for logic control of the reactor's operation through a DCS system. DCS (Distributed Control System) is a distributed control system. The following explanation uses a hydrogenation reactor as an example.

[0034] Reference Figure 2 The DCS logic of the hydrogenation reactor, which prevents the raw material feed valve from being opened due to high pressure, is as follows: When personnel accidentally open the raw material feed valve through the human-machine interface, according to the interlock priority principle, the raw material feed valve may be opened only if the pressure sensor of the hydrogenation reactor or the DCS system malfunctions.

[0035] Figure 2 In this context, HMI represents the Human-Machine Interface, PT-xxx represents the pressure gauge of the instrument air main, DCS Logic represents DCS logic, IA represents instrument air, DTT represents the solenoid valve failure action, XV1 is the feed valve for raw material 1, XVn is the feed valve for raw material n, and FC is the fail-safe position (fail-off) of the feed valve.

[0036] Referring to the Layer of Protection Analysis (LOPA) guidelines, the overall probability of failure (PFD) of the DCS logic for preventing the feed valve from opening due to high pressure in a hydrogenation reactor is 0.1. If only sensor or DCS system failures are considered, calculations using exSI Lenticia software show that the PFD for a single meter or DCS system failure is approximately 0.06. The frequency of accidental valve opening due to human error is 0.1 times per year. Therefore, considering reactor pressure sensor or DCS system failures as an enabling condition for accidental valve opening due to human error reduces the event frequency to 0.006 times per year. If the consequences of high-pressure hydrogen backflow are severe (e.g., S1, S2 levels), protection based solely on preventing the feed valve from opening due to high pressure will not pass the LOPA standard.

[0037] Comparative Example 2: Taking the SIS interlock method in the reactor as an example, this example illustrates that the raw material feed valve is not allowed to be opened when the pressure inside the reactor is high.

[0038] SIS interlock, or Safety Instrumented System interlock, is an automatic safety protection system. When hazardous situations occur during industrial production, such as excessively high temperatures, excessive pressure, or abnormal liquid levels that could lead to major accidents (such as explosions, fires, or leaks of toxic or hazardous substances), SIS interlock will automatically execute a series of pre-set actions.

[0039] Reference Figure 3 The working principle of the SIS interlock for the hydrogenation reactor with a high pressure that prevents the feed valve from being opened is as follows: the feed valve cannot be opened from the human-machine interface due to human error. The feed valve can only be opened if the pressure sensor of the hydrogenation reactor or the SIS system malfunctions.

[0040] Figure 3 In this diagram, HMI represents the Human-Machine Interface, PZT-xxx represents the pressure gauge in the instrument air main, SISLogic represents SIS interlock, IA represents instrument air, DTT represents solenoid valve failure, XV1A represents the feed valve for raw material 1, XV1B represents another feed valve for raw material 1, XVnA represents the feed valve for raw material n, and XVnB represents another feed valve for raw material n. FC is the fail-safe position (fail-safe off) for the feed valve.

[0041] Considering sensor and SIS system failures, calculations using exSI LentiA software show that the failure probability (PFD) of a 2oo3 pressure gauge or SIS system is on the order of 10⁻⁴. The frequency of accidental valve opening due to human error is 0.1 times / year. Therefore, considering a failure of the reactor's pressure sensor or SIS system as an enabling condition for accidental valve opening due to human error reduces the event frequency to 10⁻⁵ times / year. Even if the consequences of high-pressure hydrogen backflow are severe, the scenario can still be controlled within an acceptable range through LOPA analysis.

[0042] However, when the hydrogenation reactor is fed in multiple batches, it is necessary to purchase multiple SIL-certified valves to reduce the risk of valves being opened accidentally due to human error, which increases production costs. Considering cost reduction and efficiency improvement, this solution is obviously not feasible.

[0043] In this invention, in addition to the protection that the raw material feed valve is not allowed to be opened under high pressure (DCS logic), an instrument air cut-off protection is added. That is, the raw material feed valve is not allowed to be opened under high pressure (DCS logic) and the instrument air is cut off to prevent the raw material feed valve from being opened accidentally. Together, these measures prevent the valve from being opened accidentally due to human error.

[0044] Moreover, the present invention prevents the raw material feed valve from being accidentally opened by controlling the valve to cut off or connect the instrument air main pipe according to preset detection conditions before the reaction gas is introduced. This allows all feed valves to be closed at the instrument air main pipe, thereby eliminating the possibility of personnel opening the feed valve through the human-machine interface or other operation buttons or by accidentally touching the valve.

[0045] Here, the instrument air main is connected to all the feed valves of the reactor, and the control valves are connected to the instrument air main. After the reaction gas is introduced, the feed into the reactor is controlled intermittently, and the pressure inside the reactor is monitored. If the pressure is too high, all the feed valves of the reactor are closed.

[0046] Optionally, in Figure 1 In the diagram, 1 represents the reactor, and the control valve at position 2 is an addition made in this invention, such as adding a three-way solenoid valve DTT, or adding two three-way solenoid valves DTT. PT-xxx represents the pressure gauge of the instrument air main, IA represents instrument air, DTT represents the solenoid valve failure action, XV1 is the feed valve for raw material 1, XVn is the feed valve for raw material n, and FC is the fail-safe position (fail-off) of the feed valve. Sequential control represents the sequential control procedure.

[0047] In this invention, a judgment condition and a corresponding execution action are added to the sequential control program of the reactor. For example, after the addition of raw material feeding is completed and before the addition of reaction gas begins, the control valve and all feed valves are closed. At this time, the passage of the instrument air main is cut off by closing the control valve, which is equivalent to cutting off the passage at the source to prevent the raw material feed valve from being accidentally opened.

[0048] Optionally, a three-way solenoid valve can be selected. To prevent the shut-off protection from failing due to valve malfunction, two or more control valves can be added for dual or multiple protection. In actual production, under the premise of cost control, adding two control valves for shut-off protection is the optimal solution.

[0049] In this invention, the enabling condition for accidental valve opening due to human error is further enhanced compared to Comparative Example 1 by adding a control valve installed on the instrument air main to cut off the instrument air main, thereby greatly strengthening the protection against accidental opening of the batch feeding valve.

[0050] The test results of the technical solution provided by this invention show that, after considering the enabling conditions, the event frequency is reduced to 6×10⁻⁵ times / year. Furthermore, this technical solution does not involve SIS interlocking, and therefore does not require a specific SIL rating for the feed valve. For high-pressure reactors (i.e., high-pressure reaction vessels) with multiple batch feed lines, the simplicity and economy of preventing backflow caused by accidental valve opening due to human error are greatly improved.

[0051] The method provided by this invention solves the technical problem of safety and production losses caused by misoperation of batch feeding valves in the prior art. For high-pressure reactors with multiple batch feeding pipelines, the method provided by this invention can effectively prevent backflow caused by accidental opening of feeding valves due to human error. The protection method provided by this invention greatly improves the protection of operating conditions while saving the cost of operating condition protection.

[0052] In one embodiment, before the reaction gas is introduced, the instrument air main is shut off or connected by a control valve according to preset detection conditions, including:

[0053] After the raw material feeding is completed and before the reaction gas is added, close all feed valves and disconnect the instrument air main.

[0054] When the reactor is in operation, the raw materials for the reaction are added first, and then the reaction gas, such as hydrogen, is introduced. If the feeding valve is accidentally opened after the hydrogen is introduced, more reaction gas, such as hydrogen, will be added to the reactor, resulting in higher temperature and pressure inside the reactor. Therefore, after the raw materials are added, i.e., after feeding is completed, all feeding valves, including the raw material feeding valve and the hydrogen feeding valve, must be closed to ensure that the reaction gas in the reactor is supplied with the preset amount for the reaction, so that the temperature and pressure inside the reactor are within a safe range.

[0055] In one embodiment, before the reaction gas is introduced, the instrument air main is shut off or connected by a control valve according to preset detection conditions, including:

[0056] Before introducing the reaction gas into the reactor, if the control valve and all feed valves are detected to be closed, then the reaction gas can be introduced, the instrument air main pipe is connected, and the reaction gas feed valve is opened.

[0057] Before introducing the reaction gas into the reactor, it is necessary to check that the control valves and all feed valves are closed. If any valve is open, the sequential control program considers the feeding process incomplete. By detecting that the control valves and all feed valves are closed before introducing the reaction gas, the feeding process is ensured to be completed before the reaction gas is introduced, thus preventing gas from entering other valves and ensuring that the amount of reaction gas introduced is the predetermined amount, allowing the subsequent reaction in the reactor to proceed safely.

[0058] In one embodiment, before the reaction gas is introduced, the instrument air main is shut off or connected by a control valve according to preset detection conditions, including:

[0059] Before introducing reaction gas into the reactor, if the pressure value of the instrument air main is detected to be greater than the preset threshold, the introduction of reaction gas is not allowed, all feed valves are closed, and the instrument air main is shut off.

[0060] Before introducing the reaction gas into the reactor, if the pressure value of the instrument air main is detected to be greater than a preset threshold, such as 1 Pa, then the instrument air main is considered to be in a venting state and has not been shut off. In this case, the introduction of reaction gas is not permitted. By detecting the pressure value of the instrument air main before introducing the reaction gas into the reactor, the amount of reaction gas introduced is ensured to be the predetermined amount, so that the subsequent reaction in the reactor can proceed safely.

[0061] In one embodiment, before the reaction gas is introduced, the instrument air main is shut off or connected by a control valve according to preset detection conditions, including:

[0062] Before introducing the reaction gas into the reactor, if it is detected that all the protective bypasses of the feed valve are closed, then the reaction gas can be introduced, the instrument air main pipe is connected, and the reaction gas feed valve is opened.

[0063] Typically, systems are designed with bypasses for the feed valves, such as MOS or OOS bypasses. If the bypass is not closed, the feed valve may be accidentally opened. Therefore, before introducing the reactant gas, it is necessary to check whether the bypass is closed. Only if it is closed can the reactant gas be allowed to enter. By checking that all bypasses of the feed valves are closed before introducing the reactant gas into the reactor, the amount of reactant gas introduced is ensured to be the predetermined amount, allowing the subsequent reaction in the reactor to proceed safely.

[0064] Reference Figure 1 The present invention also proposes a reactor control system, comprising: a reactor 1, one or more feed valves DTT, an instrument air main, and a control valve 2. The discharge end of the feed valve is connected to the reactor, the feed ends of all feed valves are connected to the instrument air main, and the control valve is connected to the instrument air main. The control valve and / or feed valve are controlled by any of the above methods to prevent accidental opening of the reactor feed valve.

[0065] exist Figure 1 In the diagram, 1 represents the reactor, and the control valve at position 2 is an addition made in this invention, such as adding a three-way solenoid valve or two three-way solenoid valves. PT-xxx represents the pressure gauge of the instrument air main, IA represents instrument air, DTT represents the solenoid valve failure action, XV1 is the feed valve for raw material 1, XVn is the feed valve for raw material n, and FC is the fail-safe position (fail-off) of the feed valve. Sequential control represents the sequential control procedure.

[0066] In this invention, a judgment condition and a corresponding execution action are added to the sequential control program of the reactor. For example, after the addition of raw material feeding is completed and before the addition of reaction gas begins, the control valve and all feed valves are closed. At this time, the passage of the instrument air main is cut off by closing the control valve, which is equivalent to cutting off the passage at the source to prevent the raw material feed valve from being accidentally opened.

[0067] Optionally, a three-way solenoid valve can be selected. To prevent the shut-off protection from failing due to valve malfunction, two or more control valves can be added for dual or multiple protection. In actual production, under the premise of cost control, adding two control valves for shut-off protection is the optimal solution.

[0068] In this invention, compared to Comparative Example 1, the enabling condition for accidental valve opening due to human error is further enhanced by the installation of a control valve on the instrument air main to shut off the instrument air main, thereby greatly improving the protection against accidental opening of batch feeding valves.

[0069] The method provided by this invention solves the technical problem of safety and production losses caused by misoperation of batch feeding valves in the prior art. For high-pressure reactors with multiple batch feeding pipelines, the method provided by this invention can effectively prevent backflow caused by accidental opening of feeding valves due to human error. The protection method provided by this invention greatly improves the protection of operating conditions while saving the cost of operating condition protection.

[0070] In one embodiment, the control valve is a three-way solenoid valve, which is connected in series to the instrument air main.

[0071] Three-way solenoid valves are chosen because they offer advantages such as flexible control of fluid flow direction, rapid and accurate switching, adaptability to various media, strong media compatibility, independence from media flow direction and pressure, high reliability, convenient and energy-saving operation, and small space occupation.

[0072] In one embodiment, two three-way solenoid valves are included, which are connected in series to the instrument air main duct.

[0073] When both three-way solenoid valves are energized simultaneously and the pressure transmitter of the instrument air main duct malfunctions, from a safety perspective, the protection capability to prevent valves from being accidentally opened during batch feeding is greatly enhanced.

[0074] If only one three-way solenoid valve is used, its failure will render the pressure cut-off action of the instrument air main ineffective. Therefore, using two three-way solenoid valves together improves reliability and ensures that the pressure cut-off action of the instrument air main is executed normally.

[0075] In one embodiment, a three-way solenoid valve is connected upstream of the pressure transmitter on the instrument air main. The instrument air main is connected to the instrument air network or instrument air storage tank and is a main instrument air line entering the system. The added three-way solenoid valve is connected in series on the instrument air main, and the pressure gauge on the instrument air main is located after the two three-way solenoid valves.

[0076] In one embodiment, the reactor is a hydrogen reactor or a polymerization reactor.

[0077] The method proposed in this embodiment can be used in both hydrogen reactors and polymerization reactors, and it can solve the technical problem of the feed valve being opened due to human error in the reactor.

[0078] The above description is merely the principle and preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several other modifications can be made based on the principle of the present invention, and these modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preventing the inadvertent opening of a feed valve of a reactor, characterized by, Comprising: Before the reaction gas is introduced, according to the preset detection condition, the instrument air main connected with all the feed valves of the reactor is cut off or connected by controlling the valve connected with the instrument air main; After the reaction gas is introduced, the reactor gap feed is controlled, and the reactor pressure is monitored. In the case of high pressure, all the feed valves of the reactor are closed. The method for preventing the feed valve of the reactor from being opened by mistake before the reaction gas is introduced according to the preset detection condition by controlling the valve to cut off or connect the instrument air main comprises: After the raw material feed is completed and before the reaction gas is added, all the feed valves are closed, and the instrument air main is cut off; The method for preventing the feed valve of the reactor from being opened by mistake before the reaction gas is introduced according to the preset detection condition by controlling the valve to cut off or connect the instrument air main comprises: Before the reaction gas is introduced into the reactor, if it is detected that the control valve and all the feed valves are closed, the reaction gas is allowed to be introduced, the instrument air main is connected, and the feed valve of the reaction gas is opened; The method for preventing the feed valve of the reactor from being opened by mistake before the reaction gas is introduced according to the preset detection condition by controlling the valve to cut off or connect the instrument air main comprises: Before the reaction gas is introduced into the reactor, if it is detected that the pressure value of the instrument air main is greater than the preset threshold value, the reaction gas is not allowed to be introduced, all the feed valves are closed, and the instrument air main is cut off.

2. The method for preventing the feed valve of a reaction kettle from being opened by mistake according to claim 1, characterized in that, The method for preventing the feed valve of the reactor from being opened by mistake before the reaction gas is introduced according to the preset detection condition by controlling the valve to cut off or connect the instrument air main comprises: Before the reaction gas is introduced into the reactor, if it is detected that the bypass with a protective effect of the feed valve is closed, the reaction gas is allowed to be introduced, the instrument air main is connected, and the feed valve of the reaction gas is opened.

3. A reactor control system, characterized by, Comprising: The reactor, one or more feed valves, the instrument air main, the control valve, the discharge end of the feed valve is connected with the reactor, the feed end of all the feed valves is connected with the instrument air main, the control valve is connected with the instrument air main, the control valve and / or the feed valve are controlled by the method for preventing the feed valve of the reactor from being opened by mistake according to any one of claims 1 or 2.

4. The reactor control system of claim 3, wherein, The control valve is a three-way electromagnetic valve, and the three-way electromagnetic valve is connected in series to the instrument air main.

5. The reactor control system of claim 4, wherein, Two three-way electromagnetic valves are connected in series to the instrument air main.

6. The reactor control system of claim 4, wherein, The three-way electromagnetic valve is connected in front of the pressure transmitter of the instrument air main.

7. The reactor control system according to claim 3, wherein The reactor is a hydrogen reactor or a polymerization reactor.

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