Oxidation reaction system and control method

Abstract

The application discloses an oxidation reaction system and a control method thereof. The oxidation reaction system comprises a first oxidation reaction kettle, a first detection module and a first control module. The first detection module acquires a first oxidation reaction kettle temperature of the first oxidation reaction kettle and / or a first tail oxygen concentration of a first tail gas output end of the first oxidation reaction kettle, and outputs an air set value to the first control module according to the first oxidation reaction kettle temperature and / or the first tail oxygen concentration. When the air set value is reduced, the first control module first reduces a first air feed flow rate, and then proportionally reduces a reactant feed flow rate. In the application, when an abnormal working condition occurs, the first air feed flow rate is first reduced, so that the oxidation reaction kettle is prevented from being overheated or internally exploded. Meanwhile, the reactant feed flow rate is proportionally reduced, so that qualified products can still be obtained after the air feed flow rate is reduced, and the loss of the production process caused by directly stopping the production process in the abnormal working condition is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical engineering, and particularly relates to an oxidation reaction system and a control method. BACKGROUND

[0002] The oxidation process, such as isoneraldehyde oxidation process, is a process of a dangerous chemical which is under strict supervision, and a large amount of heat is released in the reaction process, and air and combustible materials react, if the temperature / tail oxygen content cannot be effectively controlled, the internal explosion or over-temperature of the reaction kettle may occur, and the oxidation reaction kettle needs to control the feeding ratio of reactants and air to ensure the product quality. Based on the above status, the oxidation reaction kettle has a great risk of over-temperature and over-pressure, so it is necessary to effectively control the tail oxygen and temperature to avoid abnormal conditions, over-temperature or internal explosion of the oxidation reaction kettle, and cause personnel casualties.

[0003] However, the existing abnormal condition control will directly stop when the abnormal condition occurs, causing loss to the production process. SUMMARY

[0004] Therefore, it is necessary to provide an oxidation reaction system and a control method for solving the technical problem that the existing technology directly stops when the abnormal condition occurs, causing loss to the production process.

[0005] The present application provides an oxidation reaction system, comprising: a first oxidation reaction kettle, a first detection module and a first control module, the first oxidation reaction kettle comprises a first oxidation reaction kettle air input end, a first oxidation reaction kettle reactant input end, a first oxidation reaction kettle tail gas output end and a first oxidation reaction kettle product output end, the first detection module obtains a first oxidation reaction kettle temperature of the first oxidation reaction kettle and / or a first tail oxygen concentration of the first oxidation reaction kettle tail gas output end, outputs an air set value to the first control module according to the first oxidation reaction kettle temperature and / or the first tail oxygen concentration, the first control module controls a first air feeding flow of the first oxidation reaction kettle air input end and a reactant feeding flow of the first oxidation reaction kettle reactant input end according to the air set value, and when the air set value decreases, the first control module first decreases the first air feeding flow, and then decreases the reactant feeding flow in proportion.

[0006] Further, the first detection module comprises an override selection block, a first oxidation reactor tail gas line oxygen table, a function module and a temperature transmitter, wherein the first oxidation reactor tail gas line oxygen table measures the first tail oxygen concentration of the first oxidation reactor tail gas output end, the output end of the first oxidation reactor tail gas line oxygen table is in communication connection with the function module, the output end of the function module is in communication connection with one input end of the override selection block, the temperature transmitter measures the temperature of the first oxidation reactor, the output end of the temperature transmitter is in communication connection with another input end of the override selection block, the output end of the override selection block is in communication connection with the first control module, the function module outputs a first set value to the override selection block according to the first tail oxygen concentration measured by the first oxidation reactor tail gas line oxygen table, the temperature transmitter outputs a second set value to the override selection block according to the temperature of the first oxidation reactor measured, and the override selection block selects the first set value or the second set value as the air set value and outputs to the first control module.

[0007] Further,

[0008] When the measured value of the first oxidation reactor tail gas line oxygen table is higher than the upper limit of the control range, the function module adjusts the first set value according to the measured value of the first oxidation reactor tail gas line oxygen table, and the first set value is negatively correlated with the measured value of the first oxidation reactor tail gas line oxygen table.

[0009] When the measured value of the first oxidation reactor tail gas line oxygen table is lower than the upper limit of the control range, the first set value is the initial set air feed set value.

[0010] Further, the first control module comprises a first flow transmitter, a second flow transmitter, a high selection controller, a low selection controller, a first valve, a second valve, a divider and a multiplier, the output end of the first detection module is in communication connection with one input end of the high selection controller and one input end of the low selection controller respectively, another input end of the high selection controller is in communication connection with the measurement end of the first flow transmitter, the output end of the high selection controller is in communication connection with the input end of the second flow transmitter through the divider, the measurement end of the second flow transmitter is in communication connection with another input end of the low selection controller through the multiplier, and the output end of the low selection controller is in communication connection with the input end of the first flow transmitter.

[0011] The measurement end of the first flow transmitter measures the first air feed flow of the first air feed end, one end of the first valve is in communication with the first air feed end, and the other end is in communication with the air input end of the first oxidation reactor, and the output end of the first flow transmitter is in communication connection with the control end of the first valve.

[0012] The measuring end of the second flow transmitter measures the reactant feed flow of the reactant feed end, one end of the second valve is in communication with the reactant feed end, and the other end is in communication with the reactant input end of the first oxidation reactor, and the output end of the second flow transmitter is in communication connection with the control end of the second valve.

[0013] Further, it further comprises a heat exchanger, one end of the product output end of the first oxidation reactor is in communication with the reflux end of the first oxidation reactor through the heat exchanger, and the other end is in communication with the discharge end or the second oxidation reactor, and the cooling medium discharge flow of the heat exchanger is adjusted according to the temperature of the first oxidation reactor.

[0014] Further, it further comprises a second oxidation reactor and a second control module, the second control module comprises a third flow transmitter, a second oxidation reactor tail gas line oxygen table and a third valve, the second oxidation reactor comprises a second oxidation reactor air input end, a second oxidation reactor reactant input end, a second oxidation reactor tail gas output end and a second oxidation reactor product output end, the first oxidation reactor product output end is in communication with the second oxidation reactor reactant input end, the second oxidation reactor tail gas line oxygen table measures the second tail oxygen concentration of the second oxidation reactor tail gas output end, the output end of the second oxidation reactor tail gas line oxygen table is in communication connection with the input end of the third flow transmitter, one end of the third valve is in communication with the second air feed end, and the other end is in communication with the second oxidation reactor air input end, the output end of the third flow transmitter is in communication connection with the control end of the third valve, and when the second tail oxygen concentration is outside the control range, the third flow transmitter controls the transmitter set value of the third flow transmitter according to the second tail oxygen concentration.

[0015] Further, when the first tail oxygen concentration is outside the control range, the third flow transmitter further adjusts the output value of the third flow transmitter according to the first tail oxygen concentration.

[0016] Further, it further comprises a limiting module and a first oxidation reactor tail gas line oxygen table for measuring the first tail oxygen concentration, and the first oxidation reactor tail gas line oxygen table is in communication connection with the input end of the third flow transmitter through the limiting module.

[0017] When the first tail oxygen concentration is less than the preset upper limit concentration value, the limiting module outputs the first tail oxygen concentration to the third flow transmitter.

[0018] When the first tail oxygen concentration is greater than or equal to the preset upper limit concentration value, the limiting module outputs the upper limit concentration value to the third flow transmitter.

[0019] The application provides a control method of the oxidation reaction system, comprising:

[0020] obtaining the first oxidation reaction kettle temperature and / or the first tail oxygen concentration of the first oxidation reaction kettle tail gas output end;

[0021] determining the air set value according to the first oxidation reaction kettle temperature and / or the first tail oxygen concentration, when the air set value is reduced, the first air feed flow is reduced first, and then the reactant feed flow is reduced in proportion.

[0022] Further, the oxidation reaction system comprises a second oxidation reaction kettle, a third flow transmitter and a third valve, the second oxidation reaction kettle comprises a second oxidation reaction kettle air input end, a second oxidation reaction kettle reactant input end, a second oxidation reaction kettle tail gas output end and a second oxidation reaction kettle product output end, the first oxidation reaction kettle product output end is communicated with the second oxidation reaction kettle reactant input end, one end of the third valve is communicated with the second air feed end, the other end is communicated with the second oxidation reaction kettle air input end, the output end of the third flow transmitter is communicated with the control end of the third valve, and the method further comprises:

[0023] obtaining the second tail oxygen concentration of the second oxidation reaction kettle tail gas output end, when the second tail oxygen concentration is out of the control range, the transmitter set value of the third flow transmitter is controlled according to the second tail oxygen concentration; and / or

[0024] obtaining the first tail oxygen concentration, when the first tail oxygen concentration is out of the control range, the output value of the third flow transmitter is adjusted according to the first tail oxygen concentration.

[0025] The application detects the tail oxygen concentration and the reaction kettle temperature through the first detection module, controls the first air feed flow and the reactant feed flow in proportion through the first control module according to the first air set value output by the first detection module, and when the air set value is reduced, the first air feed flow is reduced first, and then the reactant feed flow is reduced in proportion. Therefore, when the abnormal working condition occurs, the over-temperature or internal explosion of the oxidation reaction kettle is avoided by reducing the first air feed flow first, and meanwhile, the qualified product can still be obtained after the air feed flow is reduced, so that the loss of the production process caused by directly stopping the production in the abnormal working condition is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is an embodiment of the application, and the structure of the oxidation reaction system is shown in the figure;

[0027] Figure 2A structure schematic diagram of an oxidation reaction system for another embodiment of the present application;

[0028] Figure 3 A work flow chart of a control method of the oxidation reaction system for an embodiment of the present application.

[0029] Legend

[0030] 1 - first oxidation reaction kettle; 11 - first oxidation reaction kettle air input end; 12 - first oxidation reaction kettle reactant input end; 13 - first oxidation reaction kettle tail gas output end; 14 - first oxidation reaction kettle product output end; 15 - reflux end; 2 - first detection module; 21 - override selection block; 22 - first oxidation reaction kettle tail gas pipeline oxygen table; 23 - function module; 24 - temperature transmitter; 3 - first control module; 31 - first flow transmitter; 32 - second flow transmitter; 33 - high selection controller; 34 - low selection controller; 35 - first valve; 36 - second valve; 37 - divider; 38 - multiplier; 39 - input module; 4 - first air feed end; 5 - reactant feed end; 6 - heat exchanger; 61 - pump; 62 - cooling medium feed end; 63 - fourth valve; 64 - cooling medium discharge end; 7 - second oxidation reaction kettle; 71 - second oxidation reaction kettle air input end; 72 - second oxidation reaction kettle reactant input end; 73 - second oxidation reaction kettle tail gas output end; 74 - second oxidation reaction kettle product output end; 8 - second control module; 81 - third flow transmitter; 82 - second oxidation reaction kettle tail gas pipeline oxygen table; 83 - third valve; 84 - limiting amplitude module; 85 - second air feed end; 9 - tail gas discharge end; 10 - product discharge end. DETAILED DESCRIPTION

[0031] The specific embodiments of the present application are further described below with reference to the accompanying drawings. Identical parts are denoted by identical reference numerals in the drawings. It should be noted that the words "front", "back", "left", "right", "up", and "down" used in the following description are words of convenience and are not to be construed as limiting terms. In addition, the words "interior" and "exterior" refer to directions toward and away from, respectively, the geometric center of the device and component under discussion.

[0032] As Figure 1The structure of the oxidation reaction system is shown in the embodiment of the application, which comprises a first oxidation reaction kettle 1, a first detection module 2, and a first control module 3. The first oxidation reaction kettle 1 comprises a first oxidation reaction kettle air input end 11, a first oxidation reaction kettle reactant input end 12, a first oxidation reaction kettle tail gas output end 13, and a first oxidation reaction kettle product output end 14. The first detection module 2 obtains the first oxidation reaction kettle temperature of the first oxidation reaction kettle 1 and / or the first tail oxygen concentration of the first oxidation reaction kettle tail gas output end 13, and outputs an air set value to the first control module 3 according to the first oxidation reaction kettle temperature and / or the first tail oxygen concentration. The first control module 3 controls the first air feed flow of the first oxidation reaction kettle air input end 11 and the reactant feed flow of the first oxidation reaction kettle reactant input end 12 according to the air set value, and when the air set value decreases, the first control module 3 first decreases the first air feed flow and then decreases the reactant feed flow in proportion.

[0033] Specifically, the first oxidation reaction kettle air input end 11 inputs air from the first air feed end 4, and the first oxidation reaction kettle reactant input end 12 inputs reactant from the reactant feed end 5. The reactant is preferably a liquid-phase reactant. The reactant and the air perform an oxidation reaction in the first oxidation reaction kettle 1, which is preferably anisonaldehyde oxidation reaction. The product after the oxidation reaction is output from the first oxidation reaction kettle product output end 14, which is in communication with the product discharge end 10 to output the product. At the same time, the tail gas is output from the first oxidation reaction kettle tail gas output end 13 in communication with the tail gas discharge end 9.

[0034] The first detection module 2 obtains the first oxidation reaction kettle temperature of the first oxidation reaction kettle 1 and / or the first tail oxygen concentration of the first oxidation reaction kettle tail gas output end 13, and outputs an air set value to the first control module 3 according to the first oxidation reaction kettle temperature and / or the first tail oxygen concentration. The tail oxygen concentration is the oxygen concentration in the tail gas.

[0035] When the temperature and the first tail oxygen concentration are normal, the air set value output by the first detection module 2 is unchanged.

[0036] When the temperature or the first tail oxygen concentration is abnormal, the air set value output by the first detection module 2 decreases, so that the first control module 3 first decreases the first air feed flow and then decreases the reactant feed flow in proportion.

[0037] In the abnormal working condition of the oxidation reaction kettle temperature or the oxygen content, the embodiment realizes maximum guarantee of stable operation of the reaction kettle through temperature / tail oxygen combined staged adjustment, avoids internal explosion or over-temperature of the reaction kettle, and avoids loss of the production process caused by direct shutdown of the abnormal working condition.

[0038] Preferably, when the air setpoint increases, the first control module 3 first increases the reactant feed flow rate, and then increases the first air feed flow rate proportionally.

[0039] This invention uses a first detection module to detect the tail oxygen concentration and reactor temperature, and a first control module to control the first air feed flow rate and the reactant feed flow rate proportionally based on the first air setpoint output by the first detection module. When the air setpoint decreases, the first air feed flow rate is reduced first, followed by a proportional reduction in the reactant feed flow rate. Therefore, in the event of abnormal operating conditions, reducing the first air feed flow rate first prevents the oxidation reactor from overheating or internally exploding, while proportionally reducing the reactant feed flow rate ensures that qualified products can still be obtained even after reducing the air feed flow rate, avoiding production losses caused by direct shutdown due to abnormal operating conditions.

[0040] like Figure 1 The diagram shown is a system schematic of an oxidation reaction system according to another embodiment of the present invention, including: a first oxidation reactor 1, a first detection module 2, a first control module 3, and a heat exchanger 6. The first oxidation reactor 1 includes a first oxidation reactor air inlet 11, a first oxidation reactor reactant inlet 12, a first oxidation reactor tail gas outlet 13, and a first oxidation reactor product outlet 14. One end of the first oxidation reactor product outlet 14 is connected to the reflux outlet 15 of the first oxidation reactor 1 through the heat exchanger 6, and the other end is connected to the product outlet 10 or a second oxidation reactor 7. The cooling medium outlet flow rate of the heat exchanger 6 is determined according to the first oxidation reactor 1. The temperature of the oxidation reactor is adjusted. The first detection module 2 obtains the temperature of the first oxidation reactor 1 and / or the first tail oxygen concentration at the tail gas output terminal 13 of the first oxidation reactor. Based on the temperature of the first oxidation reactor and / or the first tail oxygen concentration, it outputs an air setpoint to the first control module 3. The first control module 3 controls the first air feed flow rate at the air input terminal 11 of the first oxidation reactor and the reactant feed flow rate at the reactant input terminal 12 of the first oxidation reactor based on the air setpoint. When the air setpoint decreases, the first control module 3 first reduces the first air feed flow rate and then reduces the reactant feed flow rate proportionally.

[0041] The first detection module 2 comprises an override selection block 21, a first oxidation reactor tail gas pipeline oxygen table 22, a function module 23 and a temperature transmitter 24, wherein the first oxidation reactor tail gas pipeline oxygen table 22 measures the first tail oxygen concentration of the first oxidation reactor tail gas output end 13, the output end of the first oxidation reactor tail gas pipeline oxygen table 22 is in communication connection with the function module 23, the output end of the function module 23 is in communication connection with an input end of the override selection block 21, the temperature transmitter 24 measures the temperature of the first oxidation reactor 1, the output end of the temperature transmitter 24 is in communication connection with another input end of the override selection block 21, the output end of the override selection block 21 is in communication connection with the first control module 3, the function module 23 outputs a first set value to the override selection block 21 according to the first tail oxygen concentration measured by the first oxidation reactor tail gas pipeline oxygen table 22, the temperature transmitter 24 outputs a second set value to the override selection block 21 according to the measured first oxidation reactor temperature, the override selection block 21 selects the first set value or the second set value as the air set value and outputs to the first control module 3;

[0042] When the measured value of the first oxidation reactor tail gas pipeline oxygen table 22 is higher than the upper limit of the control range, the function module 23 adjusts the first set value according to the measured value of the first oxidation reactor tail gas pipeline oxygen table 22, and the first set value is negatively correlated with the measured value of the first oxidation reactor tail gas pipeline oxygen table 22;

[0043] When the measured value of the first oxidation reactor tail gas pipeline oxygen table 22 is lower than the upper limit of the control range, the first set value is the initial set air feed set value;

[0044] The first control module 3 comprises a first flow transmitter 31, a second flow transmitter 32, a high selection controller 33, a low selection controller 34, a first valve 35, a second valve 36, a divider 37 and a multiplier 38, the output end of the first detection module 2 is in communication connection with an input end of the high selection controller 33 and an input end of the low selection controller 34 respectively, another input end of the high selection controller 33 is in communication connection with the measurement end of the first flow transmitter 31, the output end of the high selection controller 33 is in communication connection with the input end of the second flow transmitter 32 through the divider 37, the measurement end of the second flow transmitter 32 is in communication connection with another input end of the low selection controller 34 through the multiplier 38, the output end of the low selection controller 34 is in communication connection with the input end of the first flow transmitter 31;

[0045] The measuring end of the first flow transmitter 31 measures the first air feed flow of the first air feed end 4, one end of the first valve 35 is communicated with the first air feed end 4, and the other end is communicated with the first oxidation reactor air input end 11, and the output end of the first flow transmitter 31 is in communication connection with the control end of the first valve 35;

[0046] The measuring end of the second flow transmitter 32 measures the reactant feed flow of the reactant feed end 5, one end of the second valve 36 is communicated with the reactant feed end 5, and the other end is communicated with the first oxidation reactor reactant input end 12, and the output end of the second flow transmitter 32 is in communication connection with the control end of the second valve 36.

[0047] Specifically, the first detection module 2 includes an override selection block 21, a first oxidation reactor tail gas pipeline oxygen table 22, a function module 23, and a temperature transmitter 24. The first oxidation reactor tail gas pipeline oxygen table 22 measures and outputs the first tail oxygen concentration of the first oxidation reactor tail gas output end 13, and the first tail oxygen concentration is converted by the function module 23 into a first set value and delivered to the override selection block 21. The temperature transmitter 24 detects the temperature of the first oxidation reactor 1 and converts it into a second set value and delivers it to the override selection block 21.

[0048] The override selection block 21 performs override control, that is, the control logic relationship required by the process operation in some special cases is superimposed into the normal automatic control, which is also called an override control system or a replacement control system.

[0049] In this application, under normal conditions, the override selection block 21 outputs the first set value, and the air and reactant feed of the first oxidation reactor 1 are controlled by the first tail oxygen concentration. Since the second set value has a corresponding relationship with the temperature, the override selection block 21 determines whether the temperature of the first oxidation reactor 1 exceeds the safe critical value according to the second set value. When the temperature of the first oxidation reactor 1 exceeds the safe critical value, the second set value will drop below the preset safety threshold, at which time the override selection block 21 selects the second set value output. When the temperature of the first oxidation reactor 1 is lower than the safe critical value, the second set value is greater than the preset safety threshold, at which time the override selection block 21 selects the first set value output.

[0050] The first control module 3 comprises a first flow transmitter 31, a second flow transmitter 32, a high select controller 33, a low select controller 34, a first valve 35, a second valve 36, a divider 37 and a multiplier 38. The first flow transmitter 31 measures the first air feed flow of the first air feed end 4, and controls the opening of the first valve 35 according to the comparison result between the first air feed flow and the transmitter set value of the first flow transmitter 31, so that the first air feed flow approaches or is consistent with the transmitter set value of the first flow transmitter 31. The second flow transmitter 32 measures the reactant feed flow of the reactant feed end 5, and controls the opening of the second valve 36 according to the comparison result between the reactant feed flow and the transmitter set value of the second flow transmitter 32, so that the reactant feed flow approaches or is consistent with the transmitter set value of the second flow transmitter 32. The transmitter set value of the first flow transmitter 31 is set by the input end of the first flow transmitter 31, and the transmitter set value of the second flow transmitter 32 is set by the input end of the second flow transmitter 32.

[0051] When the first oxidation reactor 1 temperature is lower than the safety threshold value, and the tail oxygen concentration of the first oxidation reactor 1 increases, the first oxidation reactor tail gas pipeline oxygen table 22 is output to the function module 23 for processing, and after the function module 23 processing, it is output to the override selection block 21 for processing. The air set value output by the override selection block 21 is reduced, and at this time the output of the override selection block 21 is divided into two paths: the high selection controller 33 and the low selection controller 34. One of the outputs is output to an input end of the high selection controller 33, and the other input end of the high selection controller 33 is in communication connection with the measurement end of the first flow transmitter 31 to receive the air feed pipeline flow of the first oxidation reactor 1, that is, the first air feed flow. Because the high selection controller 33 selects a larger value, and the air set value is reduced, the high selection controller 33 outputs the first air feed flow. The first air feed flow and the air / reactant set ratio are input into the divider 37 for logical calculation. The air / reactant set ratio can be pre-set or input through the input module 39. The divider 37 divides the first air feed flow by the air / reactant set ratio, and outputs the calculation result to the second flow transmitter 32. The transmitter set value of the second flow transmitter 32 remains unchanged, and the reactant feed flow remains unchanged. Preferably, the reactant is a liquid phase reactant, so the liquid phase reactant feed flow remains unchanged. The other output of the override selection block 21 enters the low selection controller 34, and at the same time, the multiplier 38 is in communication connection with the measurement end of the second flow transmitter 32 to receive the reactant feed amount of the first oxidation reactor 1. The multiplier 38 multiplies the reactant feed flow by the air / reactant set ratio to obtain the air feed amount that maintains the set ratio, and simultaneously inputs the air feed amount and the other output of the override selection block 21 into the low selection controller 34. The air / reactant set ratio can be pre-set or input through the input module 39. Because the air set value is reduced, the low selection controller 34 selects a smaller value, so the air set value output by the override selection block 21 is taken as the output of the low selection controller 34, which is input into the first flow transmitter 31 as the transmitter set value of the first flow transmitter 31, thereby reducing the first air feed flow. After the above steps are completed, the first air feed flow of the first oxidation reactor 1 is reduced, but the reactant feed flow remains unchanged.

[0052] Then the first air feed flow and the air set value output by the override selection block 21 are input into the high selection controller 33 again, and the output flow of the high selection controller 33 is reduced compared with the first output flow. The output of the divider 37 is also reduced, and is input into the second flow transmitter 32, so that the transmitter set value of the second flow transmitter 32 is reduced, and finally the reactant feed flow is reduced.

[0053] In case the oxygen concentration in the first oxidation reactor exhaust line increases, the air feed flow is first reduced, and then the reactant feed is proportionally reduced. The oxygen concentration in the first oxidation reactor is reduced to the process set value while keeping the reactant to air feed ratio constant, avoiding internal explosion of the first oxidation reactor.

[0054] The logic of the function module 23 is as follows:

[0055] If the measured value of the first oxidation reactor exhaust line oxygen meter 22 is higher than the upper limit of the control range, the first set value output by the function module 23 decreases as the measured value of the first oxidation reactor exhaust line oxygen meter 22 increases, i.e. the first set value is negatively correlated with the measured value of the first oxidation reactor exhaust line oxygen meter 22.

[0056] If the measured value of the first oxidation reactor exhaust line oxygen meter 22 is lower than the upper limit of the control range, the first set value output by the function module 23 maintains the initial set air feed set value.

[0057] The first oxidation reactor product output end 14 is connected to the reflux end of the first oxidation reactor 1 through the heat exchanger 6 at one end, and is connected to the product discharge end 10 or the second oxidation reactor 7 at the other end. The first oxidation reactor product output end 14 can be provided with a pump 61 (M in the figure is a motor symbol) to improve the conveying efficiency. The cooling medium discharge flow of the heat exchanger 6 is adjusted according to the first oxidation reactor temperature, which can be controlled by the temperature transmitter 24, for example, by controlling the opening degree of the fourth valve 63 of the cooling medium feed end 62 of the heat exchanger 6. However, if abnormal process fluctuations occur, adjusting the cooling medium flow of the external circulation heat exchanger may not be able to reduce the first oxidation reactor temperature to an acceptable range.

[0058] Preferably, when the air set value is increased, the first control module 3 first increases the reactant feed flow, and then proportionally increases the air feed flow.

[0059] When the first oxidation reactor 1 temperature is lower than the safety threshold value, and the first oxidation reactor 1 tail oxygen concentration is reduced, the first oxidation reactor tail gas pipeline oxygen table 22 is output to the function module 23 for processing, and the function module 23 is output to the override selection block 21 for processing. The air set value output by the override selection block 21 is increased, and the output of the override selection block 21 is divided into two paths: the high selection controller 33 and the low selection controller 34. One output of the override selection block 21 enters the low selection controller 34, and the multiplier 38 is in communication connection with the measurement end of the second flow transmitter 32 to receive the reactant feed amount of the first oxidation reactor 1. The multiplier 38 multiplies the reactant feed flow by the air / reactant set ratio to obtain the air feed amount that maintains the set ratio, and enters the low selection controller 34 at the same time as the other output of the override selection block 21. Since the air set value is increased, the low selection controller 34 selects a smaller value, so the air feed amount is output as the output of the low selection controller 34 and input to the first flow transmitter 31, and finally as the transmitter set value of the first flow transmitter 31, thereby maintaining the first air feed flow. The other output enters an input end of the high selection controller 33. Since the high selection controller 33 selects a larger value, and the air set value is increased, the high selection controller 33 outputs the air set value. The air set value and the air / reactant set ratio enter the divider 37 for logical calculation. The divider 37 divides the air set value by the air / reactant set ratio, and outputs the calculation result to the second flow transmitter 32. The transmitter set value of the second flow transmitter 32 is increased, and the reactant feed flow is increased. After the above steps are completed, the first air feed flow of the first oxidation reactor 1 remains unchanged, but the reactant feed flow is increased.

[0060] The multiplier 38 then multiplies the increased reactant feed flow by the air / reactant set ratio again to obtain the air feed amount that maintains the set ratio with the increased reactant feed flow, and enters the low selection controller 34 at the same time as the other output of the override selection block 21. Since the air feed amount that maintains the set ratio with the increased reactant feed flow is also increased, and is input to the first flow transmitter 31, the transmitter set value of the first flow transmitter 31 is increased, and finally the first air feed flow is increased.

[0061] Finally, in the case that the first oxidation reactor tail gas pipeline oxygen concentration is reduced, the reactant feed flow is first increased, and the first air feed flow is increased in proportion.

[0062] In one embodiment, the product after the oxidation reaction of the first oxidation reactor 1 is output from the first oxidation reactor product output end 14, which is in communication with the product discharge end 10 to output the product. At the same time, the tail gas is output from the first oxidation reactor tail gas output end 13, which is in communication with the tail gas discharge end 9.

[0063] Therefore, the embodiment increases the processing of temperature abnormal conditions. When the temperature of the first oxidation reactor 1 is higher than the safety threshold, the tail oxygen concentration of the first oxidation reactor 1 is reduced, and the oxygen meter 22 of the first oxidation reactor tail gas pipeline outputs to the function module 23 for processing. At this time, the output of the function module 23 maintains the initial air feed setting value, and the function module 23 and the temperature transmitter 24 simultaneously output to the override selection block 21. After processing by the override selection block 21, the second setting value output by the temperature transmitter 24 is the output of the override selection block 21. At this time, although the oxygen content of the first oxidation reactor is lower than the upper limit of the control index, the temperature of the first oxidation reactor is increased to the process safety threshold, so the air setting value output by the override selection block 21 is reduced.

[0064] Similar to the foregoing, the output of the override selection block 21 at this time is divided into two paths: a high selection controller 33 and a low selection controller 34. One path of the output goes to an input end of the high selection controller 33, and the other input end of the high selection controller 33 is in communication connection with the measurement end of the first flow transmitter 31 to receive the air feed pipeline flow of the first oxidation reactor 1, i.e., the first air feed flow. Since the high selection controller 33 selects a larger value and the air setting value is reduced, the high selection controller 33 outputs the first air feed flow. The first air feed flow and the air / reactant setting ratio enter the divider 37 for logical calculation. The air / reactant setting ratio can be pre-set or input through the input module 39. The divider 37 divides the first air feed flow by the air / reactant setting ratio and outputs the calculation result to the second flow transmitter 32. The transmitter setting value of the second flow transmitter 32 remains unchanged, and the reactant feed flow remains unchanged. Preferably, the reactant is a liquid phase reactant, so the liquid phase reactant feed flow remains unchanged. The other path of the output of the override selection block 21 enters the low selection controller 34, and at the same time, the multiplier 38 is in communication connection with the measurement end of the second flow transmitter 32 to receive the reactant feed amount of the first oxidation reactor 1. The multiplier 38 multiplies the reactant feed flow by the air / reactant setting ratio to obtain the air feed amount that maintains the setting ratio and enters the low selection controller 34 at the same time as the other path of the output of the override selection block 21. The air / reactant setting ratio can be pre-set or input through the input module 39. Since the air setting value is reduced, the low selection controller 34 selects a smaller value, so the air setting value output by the override selection block 21 is the output of the low selection controller 34, which is input to the first flow transmitter 31 and ultimately serves as the transmitter setting value of the first flow transmitter 31, thereby reducing the first air feed flow. After the above steps are completed, the first air feed flow of the first oxidation reactor 1 is reduced, but the reactant feed flow remains unchanged.

[0065] Then the first air feed flow, the air set value outputted by the over-ride selection block 21 enters the high selection controller 33 again, the output flow of the high selection controller 33 is reduced compared with the first output flow, the output flow through the divider 37 is also reduced, and is inputted to the second flow transmitter 32, so that the transmitter set value of the second flow transmitter 32 is reduced, and finally the reactant feed flow is reduced.

[0066] Finally, in the case that the temperature of the first oxidation reactor 1 is higher than the safety critical value, the air feed flow is reduced first, and then the reactant feed flow is reduced in proportion.

[0067] The embodiment can ensure stable operation of the reactor to the greatest extent, avoid internal explosion or over-temperature of the reactor, and avoid loss of the production process caused by direct shutdown in abnormal conditions, by the above scheme under abnormal conditions of the temperature of the oxidation reactor or the oxygen content.

[0068] As shown in Figure 2 The system principle diagram of an oxidation reaction system in another embodiment of the present application is shown in the figure, which comprises a first oxidation reactor 1, a first detection module 2, a first control module 3, a heat exchanger 6, a second oxidation reactor 7, and a second control module 8. The first oxidation reactor 1 comprises a first oxidation reactor air input end 11, a first oxidation reactor reactant input end 12, a first oxidation reactor tail gas output end 13, and a first oxidation reactor product output end 14. One end of the first oxidation reactor product output end 14 is in communication with the reflux end of the first oxidation reactor 1 through the heat exchanger 6, and the other end is in communication with the second oxidation reactor 7. The cooling medium discharge flow of the heat exchanger 6 is adjusted according to the first oxidation reactor temperature. The first detection module 2 obtains the first oxidation reactor temperature of the first oxidation reactor 1 and / or the first tail oxygen concentration of the first oxidation reactor tail gas output end 13, and outputs an air set value to the first control module 3 according to the first oxidation reactor temperature and / or the first tail oxygen concentration. The first control module 3 controls the first air feed flow of the first oxidation reactor air input end 11 and the reactant feed flow of the first oxidation reactor reactant input end 12 according to the air set value. When the air set value is reduced, the first control module 3 reduces the first air feed flow first, and then reduces the reactant feed flow in proportion.

[0069] The first detection module 2 comprises an override selection block 21, a first oxidation reactor tail gas pipeline oxygen table 22, a function module 23 and a temperature transmitter 24, wherein the first oxidation reactor tail gas pipeline oxygen table 22 measures the first tail oxygen concentration of the first oxidation reactor tail gas output end 13, the output end of the first oxidation reactor tail gas pipeline oxygen table 22 is in communication connection with the function module 23, the output end of the function module 23 is in communication connection with an input end of the override selection block 21, the temperature transmitter 24 measures the temperature of the first oxidation reactor 1, the output end of the temperature transmitter 24 is in communication connection with another input end of the override selection block 21, the output end of the override selection block 21 is in communication connection with the first control module 3, the function module 23 outputs a first set value to the override selection block 21 according to the first tail oxygen concentration measured by the first oxidation reactor tail gas pipeline oxygen table 22, the temperature transmitter 24 outputs a second set value to the override selection block 21 according to the measured first oxidation reactor temperature, the override selection block 21 selects the first set value or the second set value as the air set value and outputs to the first control module 3;

[0070] When the measured value of the first oxidation reactor tail gas pipeline oxygen table 22 is higher than the upper limit of the control range, the function module 23 adjusts the first set value according to the measured value of the first oxidation reactor tail gas pipeline oxygen table 22, and the first set value is negatively correlated with the measured value of the first oxidation reactor tail gas pipeline oxygen table 22;

[0071] When the measured value of the first oxidation reactor tail gas pipeline oxygen table 22 is lower than the upper limit of the control range, the first set value is the initial set air feed set value;

[0072] The first control module 3 comprises a first flow transmitter 31, a second flow transmitter 32, a high selection controller 33, a low selection controller 34, a first valve 35, a second valve 36, a divider 37 and a multiplier 38, the output end of the first detection module 2 is in communication connection with an input end of the high selection controller 33 and an input end of the low selection controller 34 respectively, another input end of the high selection controller 33 is in communication connection with the measurement end of the first flow transmitter 31, the output end of the high selection controller 33 is in communication connection with the input end of the second flow transmitter 32 through the divider 37, the measurement end of the second flow transmitter 32 is in communication connection with another input end of the low selection controller 34 through the multiplier 38, the output end of the low selection controller 34 is in communication connection with the input end of the first flow transmitter 31;

[0073] The measuring end of the first flow transmitter 31 measures the first air feed flow of the first air feed end 4, one end of the first valve 35 is in communication with the first air feed end 4, and the other end is in communication with the first oxidation reactor air input end 11, and the output end of the first flow transmitter 31 is in communication connection with the control end of the first valve 35;

[0074] The measuring end of the second flow transmitter 32 measures the reactant feed flow of the reactant feed end 5, one end of the second valve 36 is in communication with the reactant feed end 5, and the other end is in communication with the first oxidation reactor reactant input end 12, and the output end of the second flow transmitter 32 is in communication connection with the control end of the second valve 36;

[0075] The second control module 8 includes a third flow transmitter 81, a second oxidation reactor tail gas line oxygen table 82, a third valve 83, and a limiting module 84, the second oxidation reactor 7 includes a second oxidation reactor air input end 71, a second oxidation reactor reactant input end 72, a second oxidation reactor tail gas output end 73, and a second oxidation reactor product output end 74, the first oxidation reactor product output end 14 is in communication with the second oxidation reactor reactant input end 72, the second oxidation reactor tail gas line oxygen table 82 measures the second tail oxygen concentration of the second oxidation reactor tail gas output end 73, the output end of the second oxidation reactor tail gas line oxygen table 82 is in communication connection with the input end of the third flow transmitter 81, one end of the third valve 83 is in communication with the second air feed end 85, and the other end is in communication with the second oxidation reactor air input end 71, the output end of the third flow transmitter 81 is in communication connection with the control end of the third valve 83, when the second tail oxygen concentration is outside the control range, the third flow transmitter 81 controls the transmitter set value of the third flow transmitter 81 according to the second tail oxygen concentration, and when the first tail oxygen concentration is outside the control range, the third flow transmitter 81 also adjusts the output value of the third flow transmitter 81 according to the first tail oxygen concentration.

[0076] In one embodiment, the first oxidation reactor tail gas line oxygen table 22 is in communication connection with the input end of the third flow transmitter 81 through the limiting module 84;

[0077] When the first tail oxygen concentration is less than the preset upper concentration limit value, the limiting module 84 outputs the first tail oxygen concentration to the third flow transmitter 81;

[0078] When the first tail oxygen concentration is greater than or equal to the preset upper concentration limit value, the limiting module 84 outputs the upper concentration limit value to the third flow transmitter 81.

[0079] Specifically, the first detecting module 2 comprises an override selection block 21, a first oxidation reactor tail gas line oxygen table 22, a function module 23 and a temperature transmitter 24. The first oxidation reactor tail gas line oxygen table 22 measures and outputs the first tail oxygen concentration of the first oxidation reactor tail gas output end 13, and the first tail oxygen concentration is converted by the function module 23 into a first set value and delivered to the override selection block 21. The temperature transmitter 24 detects the temperature of the first oxidation reactor 1 and converts it into a second set value and delivers it to the override selection block 21.

[0080] The first control module 3 comprises a first flow transmitter 31, a second flow transmitter 32, a high selection controller 33, a low selection controller 34, a first valve 35, a second valve 36, a divider 37 and a multiplier 38. The first flow transmitter 31 measures the first air feed flow of the first air feed end 4, and according to the comparison result of the first air feed flow and the transmitter set value set by the first flow transmitter 31, the opening degree of the first valve 35 is controlled so that the first air feed flow approaches or is consistent with the transmitter set value set by the first flow transmitter 31. The second flow transmitter 32 measures the reactant feed flow of the reactant feed end 5, and according to the comparison result of the reactant feed flow and the transmitter set value set by the second flow transmitter 32, the opening degree of the second valve 36 is controlled so that the reactant feed flow approaches or is consistent with the transmitter set value set by the second flow transmitter 32. The transmitter set value of the first flow transmitter 31 is set by the input end of the first flow transmitter 31, and the transmitter set value of the second flow transmitter 32 is set by the input end of the second flow transmitter 32.

[0081] When the first oxidation reactor 1 temperature is lower than the safety threshold value, and the tail oxygen concentration of the first oxidation reactor 1 increases, the first oxidation reactor tail gas pipeline oxygen table 22 is output to the function module 23 for processing, and after the function module 23 processing, it is output to the override selection block 21 for processing. The air set value output by the override selection block 21 is reduced, and at this time the output of the override selection block 21 is divided into two paths: the high selection controller 33 and the low selection controller 34. One of the outputs is output to an input end of the high selection controller 33, and the other input end of the high selection controller 33 is in communication connection with the measurement end of the first flow transmitter 31 to receive the air feed pipeline flow of the first oxidation reactor 1, that is, the first air feed flow. Because the high selection controller 33 selects a larger value, and the air set value is reduced, the high selection controller 33 outputs the first air feed flow. The first air feed flow and the air / reactant set ratio are input into the divider 37 for logical calculation. The air / reactant set ratio can be pre-set or input through the input module 39. The divider 37 divides the first air feed flow by the air / reactant set ratio, and outputs the calculation result to the second flow transmitter 32. The transmitter set value of the second flow transmitter 32 remains unchanged, and the reactant feed flow remains unchanged. Preferably, the reactant is a liquid phase reactant, so the liquid phase reactant feed flow remains unchanged. The other output of the override selection block 21 enters the low selection controller 34, and at the same time, the multiplier 38 is in communication connection with the measurement end of the second flow transmitter 32 to receive the reactant feed amount of the first oxidation reactor 1. The multiplier 38 multiplies the reactant feed flow by the air / reactant set ratio to obtain the air feed amount that maintains the set ratio, and simultaneously inputs the air feed amount and the other output of the override selection block 21 into the low selection controller 34. The air / reactant set ratio can be pre-set or input through the input module 39. Because the air set value is reduced, the low selection controller 34 selects a smaller value, so the air set value output by the override selection block 21 is taken as the output of the low selection controller 34, which is input into the first flow transmitter 31 as the transmitter set value of the first flow transmitter 31, thereby reducing the first air feed flow. After the above steps are completed, the first air feed flow of the first oxidation reactor 1 is reduced, but the reactant feed flow remains unchanged.

[0082] Then the first air feed flow and the air set value output by the override selection block 21 are input into the high selection controller 33 again, and the output flow of the high selection controller 33 is reduced compared with the first output flow. The output of the divider 37 is also reduced, and is input into the second flow transmitter 32, so that the transmitter set value of the second flow transmitter 32 is reduced, and finally the reactant feed flow is reduced.

[0083] In case the oxygen concentration in the first oxidation reactor exhaust line increases, the air feed flow is first reduced, and then the reactant feed is proportionally reduced. The oxygen concentration in the first oxidation reactor is reduced to the process set value while maintaining the reactant to air feed ratio of the oxidation reactor, thus avoiding internal explosion of the first oxidation reactor.

[0084] The logic of the function module 23 is as follows:

[0085] If the measured value of the first oxidation reactor exhaust line oxygen meter 22 is higher than the upper limit of the control range, the first set value output by the function module 23 decreases as the measured value of the first oxidation reactor exhaust line oxygen meter 22 increases, i.e. the first set value is negatively correlated with the measured value of the first oxidation reactor exhaust line oxygen meter 22.

[0086] If the measured value of the first oxidation reactor exhaust line oxygen meter 22 is lower than the upper limit of the control range, the first set value output by the function module 23 maintains the initial set air feed set value.

[0087] The first oxidation reactor product output end 14 is connected to the reflux end of the first oxidation reactor 1 through the heat exchanger 6 at one end, and is connected to the second oxidation reactor 7 at the other end. The first oxidation reactor product output end 14 can be provided with a pump 61 to improve the delivery efficiency. The cooling medium discharge flow of the heat exchanger 6 is adjusted according to the temperature of the first oxidation reactor, which can be controlled by the temperature transmitter 24. However, if abnormal process fluctuations occur, adjusting the cooling medium flow of the external circulation heat exchanger may not be able to reduce the temperature of the first oxidation reactor to an acceptable range.

[0088] The product after oxidation reaction of the first oxidation reactor 1 is output from the first oxidation reactor product output end 14 to the second oxidation reactor 7. The final product is output from the second oxidation reactor product output end 74, which is connected to the product discharge end 10, and the tail gas is output from the first oxidation reactor exhaust output end 13 and the tail gas discharge end 9, and the second oxidation reactor exhaust output end 73 is connected to another tail gas discharge end 9 to output tail gas.

[0089] Therefore, the embodiment increases the processing of temperature abnormal conditions. When the temperature of the first oxidation reactor 1 is higher than the safe critical value, the tail oxygen concentration of the first oxidation reactor 1 is reduced, and the oxygen meter 22 of the first oxidation reactor tail gas pipeline outputs to the function module 23 for processing. At this time, the output of the function module 23 maintains the initial air feed setting value, and the function module 23 and the temperature transmitter 24 simultaneously output to the override selection block 21. After processing by the override selection block 21, the second setting value output by the temperature transmitter 24 is the output of the override selection block 21. At this time, although the oxygen content of the first oxidation reactor is lower than the upper limit of the control index, the temperature of the first oxidation reactor is increased to the process safety critical value, so the air setting value output by the override selection block 21 is reduced.

[0090] Similar to the foregoing, the output of the override selection block 21 at this time goes to two paths: the high selection controller 33 and the low selection controller 34. One path of the output goes to an input end of the high selection controller 33, and the other input end of the high selection controller 33 is in communication connection with the measurement end of the first flow transmitter 31 to receive the air feed pipeline flow of the first oxidation reactor 1, i.e., the first air feed flow. Since the high selection controller 33 selects a larger value and the air setting value is reduced, the high selection controller 33 outputs the first air feed flow. The first air feed flow and the air / reactant setting ratio enter the divider 37 for logical calculation. The air / reactant setting ratio can be pre-set or input through the input module 39. The divider 37 divides the first air feed flow by the air / reactant setting ratio and outputs the calculation result to the second flow transmitter 32. The transmitter setting value of the second flow transmitter 32 remains unchanged, and the reactant feed flow remains unchanged. Preferably, the reactant is a liquid phase reactant, so the liquid phase reactant feed flow remains unchanged. The other path of the output of the override selection block 21 enters the low selection controller 34, and at the same time, the multiplier 38 is in communication connection with the measurement end of the second flow transmitter 32 to receive the reactant feed amount of the first oxidation reactor 1. The multiplier 38 multiplies the reactant feed flow by the air / reactant setting ratio to obtain the air feed amount of the setting ratio, and simultaneously enters the low selection controller 34 with the other path of the output of the override selection block 21. The air / reactant setting ratio can be pre-set or input through the input module 39. Since the air setting value is reduced, the low selection controller 34 selects a smaller value, so the air setting value output by the override selection block 21 is the output of the low selection controller 34, which is input to the first flow transmitter 31 and finally serves as the transmitter setting value of the first flow transmitter 31, thereby reducing the first air feed flow. After the above steps are completed, the first air feed flow of the first oxidation reactor 1 is reduced, but the reactant feed flow remains unchanged.

[0091] Then the first air feed flow, the air set value outputted by the over-ride selection block 21 enters the high selection controller 33 again, the output flow of the high selection controller 33 is reduced compared to the first output flow, the output flow through the divider 37 is also reduced, and is inputted to the second flow transmitter 32, so that the transmitter set value of the second flow transmitter 32 is reduced, and finally the reactant feed flow is reduced.

[0092] Finally, in the case that the temperature of the first oxidation reactor 1 is higher than the safe critical value, the air feed flow is reduced first, and then the reactant feed flow is reduced in proportion.

[0093] In addition, for the second oxidation reactor 7, the transmitter set value of the third flow transmitter 81 is the target air flow. The third flow transmitter 81 calculates the output value of the third flow transmitter 81 according to the comparison result of the second air feed flow and the target air flow, controls the opening of the third valve 83 through the output value of the third flow transmitter 81, and finally makes the second air feed flow close to or consistent with the target air flow.

[0094] At the same time, the second tail oxygen concentration of the second oxidation reactor tail gas output end 73 is measured through the second oxidation reactor tail gas pipeline oxygen table 82. When the second tail oxygen concentration is outside the control range, the third flow transmitter 81 controls the transmitter set value of the third flow transmitter 81 according to the second tail oxygen concentration. When the second tail oxygen concentration is outside the control range, the second tail oxygen concentration is negatively related to the transmitter set value of the third flow transmitter 81.

[0095] The third flow transmitter 81 is adjusted based on proportional, integral and differential (Proportional Integral Derivative, PID) control. The output value of the third flow transmitter 81 is determined according to the difference between the target air flow and the measured value.

[0096] When the second tail oxygen concentration is within the control range, the transmitter set value of the third flow transmitter 81 is unchanged. When the second tail oxygen concentration is outside the control range, the transmitter set value of the third flow transmitter 81 is set according to the second tail oxygen concentration.

[0097] When the tail oxygen concentration of the second oxidation reactor 7 increases to be greater than the upper limit value of the control range, the transmitter set value of the third flow transmitter 81 is reduced, that is, the target air flow is reduced, so that the second air feed flow of the second oxidation reactor 7 is reduced, thereby increasing the adjustment speed of adjusting the second air feed flow to the target air flow. When the tail oxygen concentration of the second oxidation reactor 7 decreases to be less than the lower limit value of the control range, the transmitter set value of the third flow transmitter 81 is increased, so that the second air feed flow of the second oxidation reactor 7 is increased, and the adjustment speed of adjusting the second air feed flow to the target air flow is also increased.

[0098] On the other hand, since the second oxidation reactor 7 receives the product from the first oxidation reactor 1 as the reactant of the second oxidation reactor 7, it is also necessary to monitor the first oxidation reactor 1. To this end, the first tail oxygen concentration is monitored, and the third flow transmitter 81 adjusts the output value of the third flow transmitter 81 according to the first tail oxygen concentration. Specifically, the first tail oxygen concentration is obtained from the first oxidation reactor tail gas line oxygen meter 22.

[0099] When the first tail oxygen concentration is within the control range, the output value of the third flow transmitter 81 is not corrected.

[0100] When the first tail oxygen concentration is outside the control range, the output value of the third flow transmitter 81 is corrected according to the first tail oxygen concentration.

[0101] Specifically, the output value of the third flow transmitter 81 is generated by the third flow transmitter 81 according to the existing PID algorithm according to the comparison result of the measured second air feed flow and the transmitter set value of the third flow transmitter 81. The output value generated is obtained. When the first tail oxygen concentration is outside the control range, the output value of the third flow transmitter 81 is further corrected according to the first tail oxygen concentration to correct the opening of the third valve.

[0102] When the first tail oxygen concentration is outside the control range, when the first tail oxygen concentration decreases to less than the lower limit of the control range, it indicates that in the first oxidation reactor 1, the oxygen reacts too much, and since the total input of the reactant is certain, the oxygen that reacts in the second oxidation reactor 7 needs to be reduced, so the output value of the third flow transmitter 81 is corrected to reduce the second air feed flow. As an example, when the first tail oxygen concentration decreases to less than the lower limit of the control range, the output value of the third flow transmitter 81 can be reduced to reduce the second air feed flow.

[0103] When the first tail oxygen concentration is outside the control range, when the first tail oxygen concentration rises to greater than the upper limit of the control range, it indicates that in the first oxidation reactor 1, the oxygen reacts too little, and since the total input of the reactant is certain, the oxygen that reacts in the second oxidation reactor 7 needs to be increased, so the output value of the third flow transmitter 81 is corrected to increase the second air feed flow. As an example, when the first tail oxygen concentration rises to greater than the upper limit of the control range, the output value of the third flow transmitter 81 can be increased to increase the second air feed flow.

[0104] And in order to avoid the influence of the first tail oxygen concentration being too high on the adjustment of the second oxidation reactor 7, a limiting module 84 is added, which only limits the high value.

[0105] In one embodiment, the limiting module 84 is disposed between the oxygen meter 22 of the tail gas pipeline of the first oxidation reactor and the input of the third flow transmitter 81.

[0106] When the first tail oxygen concentration is less than the preset upper limit value, the limiting module 84 outputs the first tail oxygen concentration to the third flow transmitter 81.

[0107] When the oxygen concentration at the first tail is greater than or equal to the preset upper limit value, the limiting module 84 outputs the upper limit value of the concentration to the third flow transmitter 81.

[0108] The limiting module 84 only restricts high values; it bypasses the flow when the oxygen meter 22 in the tail gas pipeline of the first oxidation reactor is below the upper concentration limit. This embodiment includes a limiting module to prevent the output value of the third flow transmitter from becoming too high.

[0109] Finally, the final reaction product is discharged from the product output terminal 74 of the second oxidation reactor.

[0110] This embodiment provides comprehensive protection for the two-stage oxidation reactors through the aforementioned solution. Under abnormal operating conditions of temperature or oxygen content in the oxidation reactors, the combined temperature and tail oxygen levels are adjusted in stages to ensure stable operation of both reactors to the greatest extent possible, preventing internal explosions or overheating, and avoiding production losses due to direct shutdown under abnormal conditions. Furthermore, based on the tail oxygen concentration in the first oxidation reactor, the second air feed flow rate can be adjusted to improve the final product yield.

[0111] This embodiment includes the input of initial parameters for the oxidation reactor: including the normal operating temperature of the oxidation reactor, the process safety temperature, the normal oxygen index of the oxidation reactor tail, and the ratio of air to reactants based on a specific conversion rate.

[0112] like Figure 2 As shown, the preferred embodiment of the present invention is an isononal oxidation reactor.

[0113] 1. Input of initial parameters for isononal oxidation reactor: including the operating temperature of the oxidation reactor, the critical temperature for process safety, the normal indicators of tail oxygen in the oxidation reactor, and the ratio of air to liquid reactants based on a specific conversion rate;

[0114] 2. The temperature of the isononal oxidation reactor is below the safety threshold, resulting in an increase in the oxygen concentration in the tail.

[0115] The first isononalaldehyde oxidation reactor is also known as the first oxidation reactor 1, and the second isononalaldehyde oxidation reactor is also known as the second oxidation reactor 7.

[0116] The temperature of the first isonitrosoaldehyde oxidation reactor is adjusted by adjusting the flow of the cooling medium of the external circulation heat exchanger 6. When the temperature of the isonitrosoaldehyde oxidation reactor is lower than the safety threshold value of the process, and the tail oxygen concentration of the isonitrosoaldehyde oxidation reactor increases, it is the case of "the temperature of the isonitrosoaldehyde oxidation reactor is lower than the safety threshold value, and the tail oxygen concentration increases". In this case, the first set value output by the oxygen table 22 of the first oxidation reactor exhaust gas pipeline is processed by the function module 23, and then the first set value is reduced. The first set value output by the function module 23 and the second set value output by the temperature transmitter 24 are simultaneously input into the override selection block 21 for processing, and then the first set value output by the function module 23 is taken as the output of the override selection block 21, and the output air set value is reduced. At this time, the output of the override selection block 21 goes to two ways: the high selection controller 33 and the low selection controller 34. One of the outputs, the isonitrosoaldehyde oxidation reactor air feed pipeline flow measured by the first flow transmitter 31, is output to the high selection controller 33, and the high selection controller 33 outputs the oxidation reactor air feed pipeline flow, that is, the first air feed flow. The oxidation reactor air feed pipeline flow and the air / reactant set ratio enter the divider 37 for logical calculation, and the liquid phase reactant feed flow remains unchanged; the other output, and the air feed amount which maintains a set ratio with the oxidation reactor liquid phase reactant feed amount measured by the second flow transmitter 32 at this time, simultaneously enter the low selection controller 34, the output of the override selection block 21 is taken as the output of the low selection controller 34, and finally as the set value of the first flow transmitter 31, the air feed flow is reduced. After the above steps are completed, the air feed flow of the isonitrosoaldehyde oxidation reactor is reduced, and the liquid phase reactant feed remains unchanged;

[0117] The logic of the function module 23 is as follows:

[0118] If the output of the first oxidation reactor exhaust gas pipeline oxygen table 22 is higher than the upper limit of the control range, the first set value output by the function module 23 decreases with the increase of the oxygen table output, and the air set value decreases;

[0119] If the output of the first oxidation reactor exhaust gas pipeline oxygen table 22 is lower than the upper limit of the control range, the first set value output by the function module 23 maintains the initial air feed set value.

[0120] Then the actual feed flow of the air pipeline and the air set value output by the override selection block 21 enter the high selection controller 33 again, and the output flow of the high selection controller 33 is reduced compared with the first output flow, and the liquid phase reactant feed flow of the isonitrosoaldehyde oxidation reactor is reduced, and finally the tail oxygen concentration of the isonitrosoaldehyde oxidation reactor is reduced to the process set value while maintaining the ratio of the liquid phase reactant and the air feed of the oxidation reactor, avoiding internal explosion of the oxidation reactor.

[0121] When the temperature of the isoneraldehyde oxidation reactor is higher than the safe critical value and the tail oxygen concentration is reduced:

[0122] When the temperature of the isoneraldehyde oxidation reactor is higher than the safe critical value and the tail oxygen concentration is reduced:

[0123] Finally, for the second oxidation reactor 7, the transmitter set value of the third flow transmitter 81 is the target air flow. When the second tail oxygen concentration is outside the control range, the third flow transmitter 81 controls the transmitter set value of the third flow transmitter 81 according to the second tail oxygen concentration.

[0124] On the other hand, the third flow transmitter 81 obtains the first tail oxygen concentration from the first oxidation reactor tail gas pipeline oxygen table 22. When the first tail oxygen concentration is within the control range, the output value of the third flow transmitter 81 is not corrected.

[0125] When the first tail oxygen concentration is outside the control range, the third flow transmitter 81 corrects the output value of the third flow transmitter 81 according to the first tail oxygen concentration.

[0126] Specifically, when the first tail oxygen concentration is outside the control range, when the first tail oxygen concentration is reduced to less than the lower limit of the control range, it indicates that too much oxygen is reacted in the first oxidation reactor 1, and since the total input of reactants is constant, the oxygen that reacts in the second oxidation reactor 7 needs to be reduced, so the output value of the third flow transmitter 81 is corrected to reduce the second air feed flow. When the first tail oxygen concentration is outside the control range, when the first tail oxygen concentration rises to be greater than the upper limit of the control range, it indicates that too little oxygen is reacted in the first oxidation reactor 1, and since the total input of reactants is constant, the oxygen that reacts in the second oxidation reactor 7 needs to be increased, so the output value of the third flow transmitter 81 is corrected to increase the second air feed flow.

[0127] In order to avoid the influence of the first tail oxygen concentration on the adjustment of the second oxidation reactor 7, a limiting module 84 is added, which indicates limiting the high value.

[0128] The limiting module 84 is arranged between the first oxidation reactor tail gas pipeline oxygen meter 22 and the input of the third flow transmitter 81.

[0129] When the first tail oxygen concentration is less than the preset upper limit concentration, the limiting module 84 outputs the first tail oxygen concentration to the third flow transmitter 81.

[0130] When the first tail oxygen concentration is greater than or equal to the preset upper limit concentration, the limiting module 84 outputs the upper limit concentration to the third flow transmitter 81.

[0131] Finally, the second oxidation reactor product output end 74 outputs the final reaction product.

[0132] As shown in Figure 3 The working flowchart of the control method of the oxidation reaction system is shown in the embodiment of the present application, which comprises:

[0133] Step S301, obtaining the first oxidation reactor temperature of the first oxidation reactor 1 and / or the first tail oxygen concentration of the first oxidation reactor tail gas output end 13.

[0134] Step S302, determining the air set value according to the first oxidation reactor temperature and / or the first tail oxygen concentration, when the air set value is reduced, first reducing the first air feed flow, and then reducing the reactant feed flow in proportion.

[0135] Specifically, for the oxidation reaction system as shown in Figure 1 or Figure 2 First, step S301 is performed to obtain the first oxidation reactor temperature of the first oxidation reactor 1 and / or the first tail oxygen concentration of the first oxidation reactor tail gas output end 13. The first oxidation reactor temperature can be obtained by the temperature transmitter 24, and the first tail oxygen concentration can be obtained by the first oxidation reactor tail gas pipeline oxygen meter 22.

[0136] Then, step S302 is performed to determine the air set value according to the first oxidation reactor temperature and / or the first tail oxygen concentration, when the air set value is reduced, first reducing the first air feed flow, and then reducing the reactant feed flow in proportion. Specifically, the first control module 3 can first reduce the first air feed flow, and then reduce the reactant feed flow in proportion.

[0137] Preferably, when the air set value is increased, first increase the reactant feed flow, and then increase the first air feed flow in proportion.

[0138] The application detects the tail oxygen concentration and the temperature of the reaction kettle through the first detection module, and controls the first air feed flow and proportionally controls the reactant feed flow according to the first air set value output by the first detection module through the first control module, and when the air set value is reduced, the first air feed flow is reduced first, and then the reactant feed flow is proportionally reduced. Therefore, when an abnormal working condition occurs, by reducing the first air feed flow first, the over-temperature or internal explosion of the oxidation reaction kettle is avoided, and at the same time, by proportionally reducing the reactant feed flow, it is ensured that after the air feed flow is reduced, qualified products can still be obtained, and the loss of the production process caused by directly stopping the production under abnormal working conditions is avoided.

[0139] In one of the embodiments, the oxidation reactant system comprises a second oxidation reaction kettle 7, a third flow transmitter 81 and a third valve 83, the second oxidation reaction kettle 7 comprises a second oxidation reaction kettle air input end 71, a second oxidation reaction kettle reactant input end 72, a second oxidation reaction kettle tail gas output end 73 and a second oxidation reaction kettle product output end 74, the first oxidation reaction kettle product output end 14 is communicated with the second oxidation reaction kettle reactant input end 72, one end of the third valve 83 is communicated with a second air feed end 85, and the other end is communicated with the second oxidation reaction kettle air input end 71, the output end of the third flow transmitter 81 is communicated and connected with the control end of the third valve 83, and the method further comprises:

[0140] obtaining a second tail oxygen concentration of the second oxidation reaction kettle tail gas output end 73, and when the second tail oxygen concentration is outside the control range, controlling the transmitter set value of the third flow transmitter 81 according to the second tail oxygen concentration; and / or

[0141] obtaining the first tail oxygen concentration, and when the first tail oxygen concentration is outside the control range, adjusting the output value of the third flow transmitter 81 according to the first tail oxygen concentration.

[0142] Specifically, for the oxidation reaction system as shown in Figure 2 the control method further comprises adjusting the second air feed flow of the second oxidation reaction kettle air input end 71 to a target air flow.

[0143] Then, the second tail oxygen concentration of the second oxidation reaction kettle tail gas output end 73 is obtained from the second oxidation reaction kettle tail gas pipeline oxygen table 82, and when the second tail oxygen concentration is outside the control range, the transmitter set value of the third flow transmitter 81 is controlled according to the second tail oxygen concentration, so as to control the adjustment speed, the adjustment speed being the speed of adjusting the second air feed flow to the target air flow; and / or

[0144] The first tail oxygen concentration is obtained from the first oxidation reactor tail gas line oxygen meter 22 and / or the limiting module 84, and when the first tail oxygen concentration is outside the control range, the output value of the third flow transmitter 81 is adjusted according to the first tail oxygen concentration.

[0145] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An oxidation reaction system characterized by, The application relates to a first oxidation reactor, a first detection module and a first control module, wherein the first oxidation reactor comprises a first oxidation reactor air input end, a first oxidation reactor reactant input end, a first oxidation reactor tail gas output end and a first oxidation reactor product output end; the first detection module obtains a first oxidation reactor temperature of the first oxidation reactor and / or a first tail oxygen concentration of the first oxidation reactor tail gas output end, outputs an air set value to the first control module according to the first oxidation reactor temperature and / or the first tail oxygen concentration, the first control module controls a first air feed flow of the first oxidation reactor air input end and a reactant feed flow of the first oxidation reactor reactant input end according to the air set value, and when the air set value decreases, the first control module first decreases the first air feed flow and then decreases the reactant feed flow in proportion. The first detection module comprises an override selection block, a first oxidation reactor tail gas pipeline oxygen table, a function module and a temperature transmitter, wherein the first oxidation reactor tail gas pipeline oxygen table measures the first tail oxygen concentration of the first oxidation reactor tail gas output end, the output end of the first oxidation reactor tail gas pipeline oxygen table is in communication connection with the function module, the output end of the function module is in communication connection with an input end of the override selection block, the temperature transmitter measures the temperature of the first oxidation reactor, the output end of the temperature transmitter is in communication connection with another input end of the override selection block, the output end of the override selection block is in communication connection with the first control module, the function module outputs a first set value to the override selection block according to the first tail oxygen concentration measured by the first oxidation reactor tail gas pipeline oxygen table, the temperature transmitter outputs a second set value to the override selection block according to the first oxidation reactor temperature measured by the temperature transmitter, the override selection block selects the first set value or the second set value as the air set value and outputs to the first control module. When the measured value of the first oxidation reactor tail gas pipeline oxygen table is higher than the upper limit of the control range, the function module adjusts the first set value according to the measured value of the first oxidation reactor tail gas pipeline oxygen table, and the first set value is negatively related to the measured value of the first oxidation reactor tail gas pipeline oxygen table. When the measured value of the first oxidation reactor tail gas pipeline oxygen table is lower than the upper limit of the control range, the first set value is an initial air feed set value. ​ The first control module comprises a first flow transmitter, a second flow transmitter, a high selection controller, a low selection controller, a first valve, a second valve, a divider and a multiplier, the output of the first detection module is communicatively connected with an input of the high selection controller and an input of the low selection controller, another input of the high selection controller is communicatively connected with a measurement end of the first flow transmitter, the output of the high selection controller is communicatively connected with an input of the second flow transmitter through the divider, a measurement end of the second flow transmitter is communicatively connected with another input of the low selection controller through the multiplier, and the output of the low selection controller is communicatively connected with an input of the first flow transmitter; The measurement end of the first flow transmitter measures the first air feed flow of the first air feed end, one end of the first valve is in communication with the first air feed end, and the other end is in communication with the air input end of the first oxidation reactor, and the output of the first flow transmitter is communicatively connected with the control end of the first valve; The measurement end of the second flow transmitter measures the reactant feed flow of the reactant feed end, one end of the second valve is in communication with the reactant feed end, and the other end is in communication with the reactant input end of the first oxidation reactor, and the output of the second flow transmitter is communicatively connected with the control end of the second valve.

2. The oxidation reaction system according to claim 1, characterized by Further comprising: A heat exchanger, one end of the product output end of the first oxidation reactor is in communication with the reflux end of the first oxidation reactor through the heat exchanger, and the other end is in communication with the discharge end or the second oxidation reactor, and the cooling medium feed flow of the heat exchanger is adjusted according to the temperature of the first oxidation reactor.

3. The oxidation reaction system of claim 1, wherein Further comprising: A second oxidation reactor and a second control module, the second control module comprises a third flow transmitter, a second oxidation reactor tail gas line oxygen table and a third valve, the second oxidation reactor comprises a second oxidation reactor air input end, a second oxidation reactor reactant input end, a second oxidation reactor tail gas output end and a second oxidation reactor product output end, the product output end of the first oxidation reactor is in communication with the reactant input end of the second oxidation reactor, the second oxidation reactor tail gas line oxygen table measures the second tail oxygen concentration of the second oxidation reactor tail gas output end, the output of the second oxidation reactor tail gas line oxygen table is communicatively connected with the input of the third flow transmitter, one end of the third valve is in communication with the second air feed end, and the other end is in communication with the second oxidation reactor air input end, the output of the third flow transmitter is communicatively connected with the control end of the third valve, and when the second tail oxygen concentration is out of the control range, the third flow transmitter controls the transmitter set value of the third flow transmitter according to the second tail oxygen concentration.

4. The oxidation reaction system of claim 3, wherein When the first tail oxygen concentration is out of the control range, the third flow transmitter also adjusts the output value of the third flow transmitter according to the first tail oxygen concentration.

5. The oxidation reaction system of claim 3, wherein Further comprising: The limiting module and a first tail oxygen concentration measuring first oxidation reactor tail gas pipeline oxygen meter, the first oxidation reactor tail gas pipeline oxygen meter is connected with the input end of the third flow transmitter through the limiting module; When the first tail oxygen concentration is less than the preset upper limit concentration value, the limiting module outputs the first tail oxygen concentration to the third flow transmitter; When the first tail oxygen concentration is greater than or equal to the preset upper limit concentration value, the limiting module outputs the upper limit concentration value to the third flow transmitter.

6. A method of controlling an oxidation reaction system as claimed in any one of claims 1 to 5, characterized in that It comprises: Obtaining the first oxidation reactor temperature and / or the first tail oxygen concentration of the first oxidation reactor tail gas output end; According to the first oxidation reactor temperature and / or the first tail oxygen concentration, the air set value is determined, when the air set value is reduced, the first air feed flow is reduced first, and then the reactant feed flow is reduced in proportion.

7. The control method of the oxidation reaction system according to claim 6, characterized by, The oxidation reaction system comprises a second oxidation reactor, a third flow transmitter and a third valve, the second oxidation reactor comprises a second oxidation reactor air input end, a second oxidation reactor reactant input end, a second oxidation reactor tail gas output end and a second oxidation reactor product output end, the first oxidation reactor product output end is communicated with the second oxidation reactor reactant input end, one end of the third valve is communicated with the second air feed end, and the other end is communicated with the second oxidation reactor air input end, the output end of the third flow transmitter is communicated with the control end of the third valve, and the method further comprises: Obtaining the second tail oxygen concentration of the second oxidation reactor tail gas output end, when the second tail oxygen concentration is out of the control range, the transmitter set value of the third flow transmitter is controlled according to the second tail oxygen concentration; and / or Obtaining the first tail oxygen concentration, when the first tail oxygen concentration is out of the control range, the output value of the third flow transmitter is adjusted according to the first tail oxygen concentration.

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