CN116143956A - On-line monitoring and intelligent regulating method for chloroethylene polymerization reaction rate - Google Patents
On-line monitoring and intelligent regulating method for chloroethylene polymerization reaction rate Download PDFInfo
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- 238000006116 polymerization reaction Methods 0.000 title claims abstract description 59
- 238000000034 method Methods 0.000 title claims abstract description 52
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical group ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 title claims abstract description 33
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- 239000002131 composite material Substances 0.000 claims abstract description 56
- 239000000498 cooling water Substances 0.000 claims abstract description 49
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- 150000001875 compounds Chemical class 0.000 claims abstract description 9
- 238000001514 detection method Methods 0.000 claims abstract description 7
- 239000000178 monomer Substances 0.000 claims abstract description 7
- 238000012545 processing Methods 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 38
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- 238000004519 manufacturing process Methods 0.000 abstract description 16
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- 229920000915 polyvinyl chloride Polymers 0.000 abstract description 7
- 239000004800 polyvinyl chloride Substances 0.000 abstract description 7
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Abstract
The invention discloses an online monitoring and intelligent adjusting method for vinyl chloride polymerization reaction rate, which comprises the following steps: s1, online detecting input parameters, including circulating cooling water flow, inlet and outlet cooling water temperature difference, cooling water pressure, cooling water temperature, cooling water valve position and vinyl chloride monomer addition amount; s2, online detection data processing; s3, obtaining cold water parameters, heat transfer efficiency and risk indexes of the online polymerization reaction; s4, obtaining the adjustment quantity of the corresponding composite initiator in the next kettle according to the data obtained in the step S3. The invention not only obtains the timely compound initiator dosage through collecting, analyzing and calculating working condition data in real time and effectively controls the polymerization reaction rate, but also can realize emergency treatment and ensure safe operation, thereby greatly realizing the yield of polyvinyl chloride resin production.
Description
Technical Field
The invention relates to the technical field of automatic control of vinyl chloride polymerization reaction, in particular to an online monitoring and intelligent adjusting method of vinyl chloride polymerization reaction rate.
Background
The polymerization process of suspension method polyvinyl chloride resin production is intermittent operation, exothermic reaction and constant temperature control (resin transformation caused by reaction temperature deviation), and at present, all processes such as cold water feeding, isothermal water feeding, hot water feeding and the like are adopted. In the process of high molecular polymerization, the reaction rate is determined by the type and amount of the initiator in the formula. The same initiator has the advantages of small dosage, long reaction period, low conversion rate and small yield; the same initiator is used in a large amount, the polymerization reaction is severe, the period is short, the utilization rate and the productivity of equipment are improved, and meanwhile, the dangers of overtemperature and overpressure can be caused by untimely heat transfer under the control of constant temperature.
The heat transfer process of the polymerization reaction is to carry heat through a jacket circulating cooling water, and the circulating cooling water is circularly used after air cooling and cooling. Therefore, the temperature of the circulating cooling water changes along with the change of the climate temperature, the temperature of the circulating cooling water is up to more than 32 ℃ in summer in the south of China, and the yield of resin production is restricted by the reduction of the heat transfer capacity of the polymerization reaction. Only by adjusting the dosage of the initiator, the safety of resin production is ensured.
However, in the production process of vinyl chloride polymerization resin, in order to shorten the reaction period and improve the utilization rate of equipment, the amount of the compound initiator is manually adjusted by process technicians according to the conditions of production, process conditions, equipment heat exchange capacity and the like, so that the reaction time is shortened and the purpose of increasing the yield is achieved.
Because of human factors, the knowledge, the capacity, the experience and the like inevitably have differences, and in the production process of vinyl chloride polymer resin, the polymerization kettle equipment cannot operate in an optimal state and the productivity is maximized, and production accidents such as overtemperature, overpressure, material running and the like can be caused by improper operation. Therefore, the method can effectively control the polymerization reaction rate of the vinyl chloride to achieve the aim of increasing the yield and ensure the production safety, and is a problem which needs to be solved by the technicians in the prior art.
Disclosure of Invention
The invention aims to solve the technical problem of providing an online monitoring and intelligent adjusting method for the vinyl chloride polymerization reaction rate, which can effectively control the vinyl chloride polymerization reaction rate, thereby achieving the purpose of increasing yield and effectively ensuring production safety.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows.
The on-line monitoring and intelligent regulating method for vinyl chloride polymerization rate includes the following steps: s1, online detecting input parameters, including circulating cooling water flow, inlet and outlet cooling water temperature difference, cooling water pressure, cooling water temperature, cooling water valve position and vinyl chloride monomer addition amount; s2, online detection data processing; s3, obtaining cold water parameters, heat transfer efficiency and risk indexes of the online polymerization reaction; s4, obtaining the adjustment quantity of the corresponding composite initiator in the next kettle according to the data obtained in the step S3.
Preferably, the method for processing the online detection data in step S2 includes smoothing filtering, first-order lag filtering and downsampling.
Preferably, in the step S3, the cold water parameter is a daily movement track of the circulating cooling water temperature through online monitoring of the circulating cooling water temperature, specifically, the highest and lowest temperatures and time distribution, average temperature and maximum temperature difference of each day are calculated through comparison and screening, and the change trend information of the water temperature is obtained by using the change rate of the temperature.
Preferably, the online calculation of the heat transfer efficiency in step S3 obtains the approximate instantaneous heat transfer efficiency according to the temperature, pressure and flow rate of the circulating cooling water by using the ratio of the instantaneous flow rate to the maximum flow rate.
Preferably, in the step S3, the on-line calculation of the risk index is performed by considering that the instantaneous thermal efficiency reaches an extreme value as the risk index, and memorizing the information of the occurrence time and duration of the risk index.
Preferably, in the step S4, the linguistic variable is set according to the instantaneous maximum heat transfer and the average heat transfer efficiency:
x 1 : (risk index ∈0.9 ∈t > 30 s);
x 2 : (risk index ∈0.9 ∈t < 30 s);
x 3 : risk index < 0.9;
x 4 : risk index < 0.6;
x 5 : the heat transfer efficiency is [75%,85 ]]；
x 6 : the heat transfer efficiency is more than 80 percent;
x 7 : the heat transfer efficiency is [70%,80 ]]；
x 8 : the heat transfer efficiency is less than 60%;
x 9 : the heat transfer efficiency is [60%,70 ]]；
Wherein, sigma t is the accumulated time length;
the composite initiator comprises a low-activity initiator A and a high-activity initiator B, wherein the adjustment amount of the low-activity initiator A is delta A respectively 1 、ΔA 2 And delta A 3 The adjustment amounts of the high-activity initiator B are respectively delta B 1 、ΔB 2 And DeltaB 3 The method comprises the steps of carrying out a first treatment on the surface of the Setting a desired output adjustment amount (kg): ΔA 1 ＝0.2；ΔA 2 ＝0.4；ΔA 3 ＝0.6；ΔB 1 ＝0.1；ΔB 2 ＝0.2；ΔB 3 ＝0.3。
Preferably, the adjustment amount of the corresponding compound initiator in the next kettle in the step S4 is as follows:
when the terminating agent is added due to high temperature and high pressure, the unconditional decrement of the compound initiator is [ -delta A 3 ，-ΔB 3 ]；
When x is 1 Is true and x 6 When true ((risk index is more than or equal to 0.9)/(sigma t > 30 s) and heat transfer efficiency is more than 80%), the composite initiator decrement is as follows: [ -DeltaA 2 ，-ΔB 2 ]；
When x is 2 Is true and x 6 When the risk index is equal to or greater than 0.9 # (Σt < 30 s) and the heat transfer efficiency is more than 80%, the composite initiator decrement is [ -delta A 1 ，-ΔB 1 ]；
When x is 1 Is true and x 7 Is true ((risk index is more than or equal to 0.9) [ lambda ] (Σt > 30 s) and heat transfer efficiency is [70%,80 ]]) In the process, the reduction of the composite initiator is determined in four cases:
(1) when the kettle operation time T [16,6 ] is started]The temperature difference of circulating water is more than 5 ℃, the risk value appears in the initial stage of the reaction, the composite initiator decrement is [0, -delta B 1 ]；
(2) When the kettle operation time T [16,6 ] is started]The temperature difference of circulating water is more than 5 ℃, the risk value appears in the middle and later stages of the reaction, and the composite initiator is reduced to [ -delta A 1 ，0]；
(3) When the kettle is started to operateNon-time T [16,6 ]]Or the temperature difference of the circulating water is small, or the risk appears in the initial stage of the reaction, the composite initiator is reduced to be [0, -delta B 2 ]；
(4) When the kettle operation is started for a period of time T [16,6 ]]Or the temperature difference of the circulating water is small, or the risk value appears in the middle and later stages of the reaction, the composite initiator is reduced to [ -delta A 2 ，0]；
When x is 2 Is true and x 7 Is true ((risk index is more than or equal to 0.9) [ lambda ] (Σtis less than 30 s) and heat transfer efficiency is [70%,80 ]]) In this case, the composite initiator is determined in two ways:
(5) the risk value appears in the initial stage of the reaction, the composite initiator is reduced to be [0 ] -delta B 1 ]；
(6) The risk value appears in the middle and later stages of the reaction, and the composite initiator is reduced to [ -delta A 1 ，0]；
When x is 3 Is true and x 5 Is true (risk index < 0.9 and heat transfer efficiency of [75%, 85%)]) When the method is used, the adjustment of the composite initiator is not needed;
when x is 3 Is true and x 7 Is true (risk index < 0.9 and heat transfer efficiency is [70%, 80%)]) When the composite initiator is added, the addition amount of the composite initiator is [ delta A ] 1 ，ΔB 1 ]；
When x is 3 Is true and x 9 Is true (risk index < 0.9 and heat transfer efficiency is [60%, 70%)]) When the composite initiator is added, the addition amount of the composite initiator is [ delta A ] 2 ，ΔB 2 ]；
When x is 4 Is true and x 8 When the composite initiator is true (risk index < 0.6 and heat transfer efficiency < 60%), the composite initiator is added in [ delta A ] 3 ，ΔB 3 ]。
Preferably, if the risk index is greater than 0.99 # (Sigma t is greater than 120 s), judging whether the kettle temperature and the kettle pressure reach the set highest limit value; when the maximum limit value is reached, calculating the change rate, and if the change rate of the kettle temperature and the change rate of the kettle pressure are both greater than 0, controlling the change rate of the kettle temperature and the kettle pressure below zero in a mode of adding a terminating agent.
By adopting the technical scheme, the invention has the following technical progress.
The invention not only obtains the timely compound initiator dosage through collecting, analyzing and calculating working condition data in real time and effectively controls the polymerization reaction rate, but also can realize emergency treatment and ensure safe operation, thereby greatly realizing the yield of polyvinyl chloride resin production.
Drawings
Fig. 1 is a functional block diagram of the present invention.
Detailed Description
The invention will be described in further detail with reference to the drawings and the detailed description.
An on-line monitoring and intelligent regulating method for the polymerization rate of vinyl chloride is used to control the reaction rate in the polymerization process of polyvinyl chloride resin, and features that under the condition of ensuring safety of heat exchange capacity of polymerizing reactor, the intelligent control of polyvinyl chloride polymerization rate is composed by DCS control system, artificial intelligent technique, numerical calculation and soft measurement technique. As shown in connection with fig. 1, the method comprises the following steps:
s1, detecting input parameters on line.
The on-line detection of input parameters includes: the method comprises the steps of circulating cooling water flow, inlet and outlet cooling water temperature difference, cooling water pressure, cooling water temperature, cooling water valve position and vinyl chloride monomer addition, wherein the circulating cooling water flow, inlet and outlet cooling water temperature difference (the difference between inlet water temperature and outlet water temperature) can calculate heat taken away (removed) instantaneously; the cooling water pressure directly influences the circulating cooling water flow; the cooling water temperature can memorize the daily movement track, and the highest, lowest and temperature difference and time distribution; the valve position of the cooling water can obtain the circulating cooling water flow area; the total exotherm of the polymerization can be calculated by the monomer addition.
S2, online detection data processing.
The input parameters detected on line are preprocessed, and the processing method comprises smoothing filtering, first-order lag filtering, downsampling and the like, so that preparation is made for the next step.
S3, obtaining cold water parameters, heat transfer efficiency and risk indexes of the online polymerization reaction.
The numerical calculations of cold water parameters, heat transfer efficiency and risk index for the on-line polymerization reaction are specifically as follows:
1. cold water parameter calculation for on-line polymerization
The circulating cooling water is cooled by the air cooling tower and recycled, and the temperature of the cooling water can be changed due to the change of the environmental climate, so that the polymerization heat removal effect is directly affected.
The cold water parameters are the daily movement track of the circulating cooling water temperature through on-line monitoring of the circulating cooling water temperature, specifically, the highest and lowest temperatures and the time distribution, average temperature and maximum temperature difference of the highest and lowest temperatures are calculated every day through comparison and screening, and the change rate of the temperature is utilized to obtain the information such as the change trend of the water temperature.
Maximum temperature Tmax, time profile [ t ] a ，t b ]The method comprises the steps of carrying out a first treatment on the surface of the Minimum temperature Tmin, time profile [ t ] c ，t d ]The method comprises the steps of carrying out a first treatment on the surface of the Daily average temperature Ta; the daily temperature difference Td.
2. Heat transfer efficiency calculation for in-line polymerization
The heat transfer efficiency is obtained by the ratio of the actual heat transfer amount to the maximum heat transfer amount of the process equipment; the method can be obtained by the ratio of the instantaneous flow accumulation of the circulating cooling water to the maximum flow accumulation of the process equipment; the average heat transfer efficiency can also be estimated by circulating cooling water flow area.
The heat transfer rate of the polymerization kettle equipment is determined by the heat transfer area, the temperature difference between the kettle and the jacket and the heat transfer coefficient; the flow of the process circulating cooling water, the temperature of the cooling water, the process conditions and the like are main factors of heat transfer of the polymerization reaction.
Heat transfer rate Q (kJ/h or kcal/h) and heat transfer area F (m) 2 ) Temperature difference delta T m Proportional to (DEG C), the proportionality coefficient is the heat transfer coefficient K=W/(m) 2 ·K)＝kcal/(h·m 2 ·℃)。
The polymerization reaction releases heat, the constant temperature reaction is ensured by cooling and heat removal of a jacket, and the heat balance equation is as follows:
wherein M is 1 、M 2 The mass flow rates of the hot fluid and the cold fluid are kg/s respectively; i.e 1 、i 2 Enthalpy, J/kg, of the hot fluid and the cold fluid, respectively.
By numerical calculation and analysis, for Q Efficiency of The actual problem is difficult to build a mathematical model and can be obtained by approximate calculation
For the heat transfer efficiency of the polymerization reaction, only the temperature, the pressure and the flow rate of the circulating cooling water are considered, wherein the flow rate can be calculated through the cooling water flow in a time period, and the approximate instantaneous heat transfer efficiency can be obtained by utilizing the ratio of the instantaneous flow rate to the maximum flow rate under the condition of good quality of constant temperature control.
Error estimation, Q Efficiency of In order for the value to be accurate,
is of approximate value, with an error E (Q) of
E (Q) can be used as a truncation according to numerical calculation analysis and error estimation.
3. Risk index calculation for in-line polymerization
When the heat transfer reaches the maximum capacity and is still smaller than the heat release amount of the polymerization reaction in the process of heat release of the polymerization reaction, the constant temperature control is ineffective control in the process of the reaction, and the longer the duration, the larger the risk index.
The risk index is monitored on line, namely the instant time-shifting thermal efficiency is considered to reach an extreme value to be used as the time-shifting thermal risk index, and information such as the occurrence time and the occurrence time length of the instant time-shifting thermal efficiency is memorized, so that the reference basis for the adjustment of the composite initiator is facilitated.
S4, obtaining the adjustment quantity of the corresponding composite initiator in the next kettle according to the data obtained in the step S3.
In the vinyl chloride polymerization process, the initiator is decomposed into a first-stage reaction, the initiator plays a role in initiating in the elementary reaction of the vinyl chloride free radical polymerization, and the production capacity of the kettle is improved to the greatest extent on the basis of reasonably selecting the initiator and enabling the initiator to be close to a uniform reaction as much as possible. A high activity complex initiator with a short half-life and a low activity complex initiator with a long half-life are generally used to meet the polymerization rate at different stages of the reaction process.
In the present invention, the initiator is selected from complex initiators (BNP, CNP), which can be classified into: low activity initiator A and high activity initiator B. When the polymerization feeding is finished, the temperature in the kettle is increased, in the process, the temperature in the kettle is gradually increased, the high-activity initiator B is decomposed in preference to the low-activity initiator A, and the high-activity initiator B and vinyl chloride monomer are subjected to polymerization reaction, so that the reaction heat release is beneficial to the temperature increase in the kettle, and a temperature condition is provided for the boundary of the low-activity initiator A. Therefore, the high activity initiator is to decompose at a slightly lower temperature, while the low activity initiator enables a relatively smooth overall exothermic reaction.
The polyvinyl chloride resin is produced by vinyl chloride polymerization, which is carried out by adding dispersion medium, dispersant, regulator, initiator and vinyl chloride monomer into a polymerization kettle, sealing, and the dosage of the initiator can not be adjusted in the reaction process, only according to the related data of the operation of the last kettle: and reasonably adjusting parameters such as risk index, average heat transfer efficiency, daily temperature movement track of heat transfer cooling circulating water and the like of the initiator of the next kettle.
First, the desired control and adjustment is determined: the average heat transfer efficiency is controlled between 75 and 85 percent, and the risk index is controlled below 0.95; setting the adjustment amounts of the low-activity initiator A to be delta A respectively 1 、ΔA 2 And delta A 3 The adjustment amounts of the high-activity initiator B are respectively delta B 1 、ΔB 2 And DeltaB 3 。
Secondly, according to the actual working condition, the addition amount of the initiator is adjusted in a mode of gradually approaching through micro-acceleration and deceleration, so that the intelligent control of the polymerization rate is realized.
Setting linguistic variables according to the instantaneous maximum heat transfer and the average heat transfer efficiency, namely defining the running state x of the reaction kettle 1 ～x 4 Heat transfer efficiency x 5 ～x 9 ：
x 1 : (risk index ∈0.9 ∈t > 30 s);
x 2 : (risk index ∈0.9 ∈t < 30 s);
x 3 : risk index < 0.9;
x 4 : risk index < 0.6;
x 5 : the heat transfer efficiency is [75%,85 ]]；
x 6 : the heat transfer efficiency is more than 80 percent;
x 7 : the heat transfer efficiency is [70%,80 ]]；
x 8 : the heat transfer efficiency is less than 60%;
x 9 : the heat transfer efficiency is [60%,70 ]]。
Wherein, sigma t is the accumulated time length; x is x 1 The expression means: the risk index is more than or equal to 0.9, and the cumulative time is more than 30 seconds, which indicates that the heat transfer regulation is in a near-uncontrolled state in the period.
Setting a desired output adjustment amount (kg): ΔA 1 ＝0.2；ΔA 2 ＝0.4；ΔA 3 ＝0.6；ΔB 1 ＝0.1；ΔB 2 ＝0.2；ΔB 3 ＝0.3。
When the terminating agent is added due to high temperature and high pressure, the unconditional decrement of the compound initiator is [ -delta A 3 ，-ΔB 3 ][-ΔA 3 ，-ΔB 3 ]；
When x is 1 Is true and x 6 When true ((risk index is more than or equal to 0.9)/(sigma t > 30 s) and heat transfer efficiency is more than 80%), the composite initiator decrement is as follows: [ -DeltaA 2 ，-ΔB 2 ]；
When x is 2 Is true and x 6 When the risk index is equal to or greater than 0.9 # (Σt < 30 s) and the heat transfer efficiency is more than 80%, the composite initiator decrement is [ -delta A 1 ，-ΔB 1 ]；
When x is 1 Is trueAnd x7 is true ((risk index ∈0.9) ∈t > 30 s) and the heat transfer efficiency is [70%,80 ]]) In the process, the reduction of the composite initiator is determined in four cases:
(1) when the kettle operation time T [16,6 ] is started]The temperature difference of circulating water is more than 5 ℃, the risk value appears in the initial stage of the reaction, the composite initiator decrement is [0, -delta B 1 ]。
(2) When the kettle operation time T [16,6 ] is started]The temperature difference of circulating water is more than 5 ℃, the risk value appears in the middle and later stages of the reaction, and the composite initiator is reduced to [ -delta A 1 ，0]。
(3) When the kettle operation is started for a period of time T [16,6 ]]Or the temperature difference of the circulating water is small, or the risk appears in the initial stage of the reaction, the composite initiator is reduced to be [0, -delta B 2 ]。
(4) When the kettle operation is started for a period of time T [16,6 ]]Or the temperature difference of the circulating water is small, or the risk value appears in the middle and later stages of the reaction, the composite initiator is reduced to [ -delta A 2 ，0]。
When x is 2 Is true and x 7 Is true ((risk index is more than or equal to 0.9) [ lambda ] (Σtis less than 30 s) and heat transfer efficiency is [70%,80 ]]) In this case, the composite initiator is determined in two ways:
(5) the risk value appears in the initial stage of the reaction, the composite initiator is reduced to be [0 ] -delta B 1 ]。
(6) The risk value appears in the middle and later stages of the reaction, and the composite initiator is reduced to [ -delta A 1 ，0]。
When x is 3 Is true and x 5 Is true (risk index < 0.9 and heat transfer efficiency of [75%, 85%)]) In this case, no adjustment of the complex initiator is necessary.
When x is 3 Is true and x 7 Is true (risk index < 0.9 and heat transfer efficiency is [70%, 80%)]) When the composite initiator is added, the addition amount of the composite initiator is [ delta A ] 1 ，ΔB 1 ]；
When x is 3 Is true and x 9 Is true (risk index < 0.9 and heat transfer efficiency is [60%, 70%)]) When the composite initiator is added, the addition amount of the composite initiator is [ delta A ] 2 ，ΔB 2 ]；
When x is 4 Is true and x 8 True (Risk finger)When the number is less than 0.6 and the heat transfer efficiency is less than 60 percent, the composite initiator is added with [ delta A ] 3 ，ΔB 3 ]。
The invention realizes the adjustment of the optimal vinyl chloride polymerization reaction rate (period) under the existing process and working condition by machine learning and training an optimization algorithm.
Meanwhile, in the exothermic process of the vinyl chloride polymerization reaction, the reaction temperature is ensured to be constant by heat transfer of circulating cooling water, and the temperature of the circulating cooling water is changed along with sudden change of the ambient temperature. To ensure safe operation, polymerization production safety must be ensured. Therefore, the emergency treatment method is added in the reaction process, firstly, whether the risk index is larger than 0.99 and the accumulated time length is larger than 120s is judged, and if so, whether the kettle temperature and the kettle pressure reach the set highest limit value is judged; when the maximum limit value is reached, calculating the change rate, and if the change rate of the kettle temperature and the change rate of the kettle pressure are both greater than 0, controlling the change rate of the kettle temperature and the kettle pressure below zero in a mode of adding a terminating agent.
In the operation of vinyl chloride polymerization process operation, the invention can use the original DCS control system (hardware and software equipment meeting the application requirements) of a customer, and can also add control equipment again, and on a control software platform (with numerical calculation, logic operation module and the like) of the control equipment, programming configuration is carried out according to the principle and block diagram of the online monitoring and intelligent adjusting method of the vinyl chloride polymerization reaction rate; dynamic response test and calculation of the aggregate production process, determination of relevant data, and control of online downloading and debugging (open loop simulation) of programming configuration software to achieve the expected effect; and adjusting and setting process parameters and control parameters, putting into a closed loop, performing online parameter setting, and putting into normal safe production operation after meeting process and control requirements.
According to the invention, the DCS control system is used for collecting working condition data in real time, analyzing and calculating the heat exchange efficiency and risk index of process operation in the reaction process and the average heat transfer efficiency in the polymerization process on line, so that the method is used for adjusting the amount of the initiator, thus not only obtaining the amount of the compound initiator in time, effectively controlling the polymerization reaction rate, maximally realizing the yield of polyvinyl chloride resin production, but also realizing emergency treatment and ensuring safe operation.
Claims (8)
1. The on-line monitoring and intelligent adjusting method for the vinyl chloride polymerization reaction rate is characterized by comprising the following steps: the method comprises the following steps:
s1, online detecting input parameters, including circulating cooling water flow, inlet and outlet cooling water temperature difference, cooling water pressure, cooling water temperature, cooling water valve position and vinyl chloride monomer addition amount;
s2, online detection data processing;
s3, obtaining cold water parameters, heat transfer efficiency and risk indexes of the online polymerization reaction;
s4, obtaining the adjustment quantity of the corresponding composite initiator in the next kettle according to the data obtained in the step S3.
2. The method for on-line monitoring and intelligent adjusting of vinyl chloride polymerization rate according to claim 1, wherein: the method for processing the online detection data in the step S2 includes smoothing filtering, first-order lag filtering and downsampling.
3. The method for on-line monitoring and intelligent adjusting of vinyl chloride polymerization rate according to claim 1, wherein: the cold water parameters in the step S3 are daily movement tracks of the circulating cooling water temperature through on-line monitoring of the circulating cooling water temperature, specifically, the highest temperature and the lowest temperature each day and time distribution, average temperature and maximum temperature difference are calculated through comparison and screening, and the change trend information of the water temperature is obtained through the change rate of the temperature.
4. The method for on-line monitoring and intelligent regulation of vinyl chloride polymerization rate according to claim 3, wherein: and the online calculation of the heat transfer efficiency in the step S3 obtains the approximate instantaneous heat transfer efficiency by utilizing the ratio of the instantaneous flow rate to the maximum flow rate according to the temperature, the pressure and the flow rate of the circulating cooling water.
5. The method for on-line monitoring and intelligent regulation of vinyl chloride polymerization rate according to claim 4, wherein: in the step S3, the on-line calculation of the risk index is actually performed by considering that the instantaneous thermal efficiency reaches an extremum, and the instantaneous thermal efficiency is taken as the risk index, and the occurrence time and duration information of the instantaneous thermal efficiency are memorized.
6. The method for on-line monitoring and intelligent regulation of vinyl chloride polymerization rate according to claim 5, wherein: in the step S4, a linguistic variable is set according to the instantaneous maximum heat transfer and the average heat transfer efficiency:
x 1 : (risk index ∈0.9 ∈t > 30 s);
x 2 : (risk index ∈0.9 ∈t < 30 s);
x 3 : risk index < 0.9;
x 4 : risk index < 0.6;
x 5 : the heat transfer efficiency is [75%,85 ]]；
x 6 : the heat transfer efficiency is more than 80 percent;
x 7 : the heat transfer efficiency is [70%,80 ]]；
x 8 : the heat transfer efficiency is less than 60%;
x 9 : the heat transfer efficiency is [60%,70 ]]；
Wherein, sigma t is the accumulated time length;
the composite initiator comprises a low-activity initiator A and a high-activity initiator B, wherein the adjustment amount of the low-activity initiator A is delta A respectively 1 、ΔA 2 And delta A 3 The adjustment amounts of the high-activity initiator B are respectively delta B 1 、ΔB 2 And DeltaB 3 The method comprises the steps of carrying out a first treatment on the surface of the Setting a desired output adjustment amount (kg): ΔA 1 ＝0.2；ΔA 2 ＝0.4；ΔA 3 ＝0.6；ΔB 1 ＝0.1；ΔB 2 ＝0.2；ΔB 3 ＝0.3。
7. The method for on-line monitoring and intelligent regulation of vinyl chloride polymerization rate according to claim 6, wherein: the adjustment amount of the corresponding compound initiator in the next kettle in the step S4 is as follows:
when the terminating agent is added due to high temperature and high pressure, the unconditional decrement of the compound initiator is [ -delta A 3 ，-ΔB 3 ]；
When x is 1 Is true and x 6 When true ((risk index is more than or equal to 0.9)/(sigma t > 30 s) and heat transfer efficiency is more than 80%), the composite initiator decrement is as follows: [ -DeltaA 2 ，-ΔB 2 ]；
When x is 2 Is true and x 6 When the risk index is equal to or greater than 0.9 # (Σt < 30 s) and the heat transfer efficiency is more than 80%, the composite initiator decrement is [ -delta A 1 ，-ΔB 1 ]；
When x is 1 Is true and x 7 Is true ((risk index is more than or equal to 0.9) [ lambda ] (Σt > 30 s) and heat transfer efficiency is [70%,80 ]]) In the process, the reduction of the composite initiator is determined in four cases:
(1) when the kettle operation time T [16,6 ] is started]The temperature difference of circulating water is more than 5 ℃, the risk value appears in the initial stage of the reaction, the composite initiator decrement is [0, -delta B 1 ]；
(2) When the kettle operation time T [16,6 ] is started]The temperature difference of circulating water is more than 5 ℃, the risk value appears in the middle and later stages of the reaction, and the composite initiator is reduced to [ -delta A 1 ，0]；
(3) When the kettle operation is started for a period of time T [16,6 ]]Or the temperature difference of the circulating water is small, or the risk appears in the initial stage of the reaction, the composite initiator is reduced to be [0, -delta B 2 ]；
(4) When the kettle operation is started for a period of time T [16,6 ]]Or the temperature difference of the circulating water is small, or the risk value appears in the middle and later stages of the reaction, the composite initiator is reduced to [ -delta A 2 ，0]；
When x is 2 Is true and x 7 Is true ((risk index is more than or equal to 0.9) [ lambda ] (Σtis less than 30 s) and heat transfer efficiency is [70%,80 ]]) In this case, the composite initiator is determined in two ways:
(5) the risk value appears in the initial stage of the reaction, the composite initiator is reduced to be [0 ] -delta B 1 ]；
(6) The risk value appears in the middle and later stages of the reaction, and the composite initiator is reduced to [ -delta A 1 ，0]；
When x is 3 Is true and x 5 Is true (risk index < 0.9 and heat transfer efficiency of [75%, 85%)]) When the method is used, the adjustment of the composite initiator is not needed;
when x is 3 Is true and x 7 Is true (risk index < 0.9 and heat transfer efficiency is [70%, 80%)]) When the composite initiator is added, the addition amount of the composite initiator is [ delta A ] 1 ，ΔB 1 ]；
When x is 3 Is true and x 9 Is true (risk index < 0.9 and heat transfer efficiency is [60%, 70%)]) When the composite initiator is added, the addition amount of the composite initiator is [ delta A ] 2 ，ΔB 2 ]；
When x is 4 Is true and x 8 When the composite initiator is true (risk index < 0.6 and heat transfer efficiency < 60%), the composite initiator is added in [ delta A ] 3 ，ΔB a ]。
8. The method for on-line monitoring and intelligent regulation of vinyl chloride polymerization rate according to claim 7, wherein: the risk index in the kettle (the risk index is more than 0.99) [ lambda ] ([ sigma ] t is more than 120 s), judging whether the kettle temperature and the kettle pressure reach the set highest limit value; when the maximum limit value is reached, calculating the change rate, and if the change rate of the kettle temperature and the change rate of the kettle pressure are both greater than 0, controlling the change rate of the kettle temperature and the kettle pressure below zero in a mode of adding a terminating agent.
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| US20070238844A1 (en) * | 2006-04-10 | 2007-10-11 | Hokyung Lee | Method for optimization of process by adjustment of initiator in polymerization system |
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| US20070238844A1 (en) * | 2006-04-10 | 2007-10-11 | Hokyung Lee | Method for optimization of process by adjustment of initiator in polymerization system |
| CN107151281A (en) * | 2017-05-04 | 2017-09-12 | 宜宾天原集团股份有限公司 | Substance law PVC polymeric reaction temperature autocontrol methods |
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