A soft measurement method for PVC moisture content in PVC drying equipment
By using the PVC water content soft measurement method in the PVC drying device, an energy balance model was established, and the wind temperature and steam valve opening were adjusted in real time, which solved the problems of hysteresis and energy waste during the PVC drying process, and achieved efficient and stable PVC drying process.
Patent Information
- Application Number
- CN202210805693.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-08
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2042-07-08
AI Technical Summary
There is a hysteresis in the process of PVC drying, and it is difficult to control the PVC water content in a timely manner, resulting in energy waste and unstable product quality.
Using the PVC water content soft measurement method of the PVC drying device, the energy balance model is established by measuring the PVC water content of each bed room, and the regression coefficient is calculated using polynomial regression to obtain the PVC water content soft measurement model of each bed room, and the wind temperature is adjusted in real time Steam valve opening.
Real-time control of the PVC drying process is realized, energy consumption is reduced, product quality is improved, and energy conservation and environmental protection is met.
Smart Images
Figure CN115284484B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of PVC drying automatic control, and in particular relates to a soft measurement method for PVC water content of a PVC drying device. Background Art
[0002] Polyvinyl chloride (PVC) is a widely used chemical raw material. In the PVC production process, PVC drying is a key link in the production process. PVC drying devices often use internally heated horizontal multi-chamber fluidized bed. The drying device uses air volume to make the PVC material in the bed in a boiling state, that is, the PVC material is tumbling in the bed, forming the basic conditions for the operation of the drying bed, and then uses hot air and steam passed into the tubes in the bed to heat the PVC material, remove volatiles in the PVC, and complete the drying of the PVC. The moisture content of the dried PVC needs to be less than 0.4% to meet the process requirements. If the moisture content is too high, it will affect the quality of the PVC product. If the moisture content is too low, it will generate static electricity and waste energy.
[0003] Since the PVC drying process is through ventilation and steam heating of the drying device, the energy transfer and water evaporation take time, so the whole PVC drying process is a process with a large lag. In the production process, if only the PVC moisture content at the drying outlet is detected, and manual intervention control is performed when the moisture exceeds the standard, there will be lag and it is difficult to meet the control requirements. Therefore, in order to ensure the quality of PVC products, excessive heat is often introduced into the drying device to fully ensure that the moisture content of PVC meets the standard, but this method will lead to energy waste and does not meet the requirements of energy saving and environmental protection. Summary of the invention
[0004] In view of the above technical problems, the present invention proposes a soft measurement method for the PVC moisture content of a PVC drying device. The method can obtain the PVC moisture content of the drying device in time by measuring the PVC moisture content of one bed and one chamber, one bed and two chambers, and two beds of the drying device, which is used to guide the control of the PVC moisture content, make the production process more stable, and reduce energy consumption in the production process.
[0005] In order to realize the soft measurement of PVC moisture content in each bed chamber of the PVC device, the technical scheme provided by the present invention is as follows: A soft measurement method of PVC moisture content in a PVC drying device comprises the following steps:
[0006] Step S01: Establishing an energy balance model for each bed chamber of the PVC drying device;
[0007] Step S02: Calculate the average working efficiency of each bed chamber according to the number of tubes and air volume of each bed chamber;
[0008] Step S03: estimating the PVC water content of each bed chamber according to the average working efficiency of one bed and one chamber, the average working efficiency of one bed and two chambers, and the average working efficiency of two beds;
[0009] Step S04: According to the air temperature of one bed and one chamber, the opening of the steam valve of one bed and one chamber, the water content of the PVC entering the drying bed, the current of the centrifuge, the estimated water content of the PVC leaving one bed and one chamber, the air temperature of one bed and two chambers, the opening of the steam valve of one bed and two chambers, the estimated water content of the PVC leaving one bed and two chambers, the air temperature of two beds, the opening of the steam valve of two beds, the estimated water content of the PVC leaving two beds, and the historical data of the water content of the PVC leaving two beds, the regression coefficient of the energy balance model of each bed chamber is calculated by using polynomial regression;
[0010] Step S05: according to the model regression coefficient, the relationship between the material amount of each bed chamber and the centrifuge current, obtain a one-bed-one-chamber PVC moisture content soft measurement model, a one-bed-two-chamber PVC moisture content soft measurement model and a two-bed PVC moisture content soft measurement model;
[0011] Step S06: Based on the obtained one-bed-one-chamber PVC moisture content soft measurement model, one-bed-two-chamber PVC moisture content soft measurement model and two-bed PVC moisture content soft measurement model, substitute the real-time centrifuge current, one-bed-one-chamber air temperature, one-bed-one-chamber steam valve opening, one-bed-two-chamber air temperature, one-bed-two-chamber steam valve opening, two-bed air temperature and two-bed steam valve opening to obtain the PVC moisture content of each bed chamber of the drying device.
[0012] Furthermore, the step S01 is specifically as follows: according to the energy balance and material balance of the drying bed, the energy and material balance relationship of each bed chamber of the PVC drying device is established, and then:
[0013] Energy and material balance formula for one bed and one room:
[0014]
[0015] Energy and material balance formula for one bed and two chambers:
[0016]
[0017] Energy and material balance of the second bed:
[0018]
[0019] Where K w1 , K s1 , b1, K w2 , K s2 , b2, K w3 , K s3 , b3 represents the model regression coefficient, Q w1 Indicates the wind temperature of one bed and one room, Q s1 Indicates the opening of the steam valve for one bed and one chamber, Xm Indicates the water content of PVC entering the drying bed, X f represents the centrifuge current, Indicates the estimated water content of PVC in one bed and one room, X f1 Indicates the amount of material in one bed and one chamber, Q w2 Indicates the wind temperature of one bed and two rooms, Q s2 Indicates the opening of the steam valve of the second chamber of the first bed. Indicates the estimated water content of PVC in one bed and two chambers, X f2 Indicates the amount of material in one bed and two chambers, Q w3 Indicates the air temperature of the second bed, Q s3 Indicates the opening of the steam valve of the second bed, Indicates the estimated water content of the second bed PVC, Y f Indicates the amount of material in the second bed.
[0020] Furthermore, the step S02 is specifically as follows: the number of tubes per bed and per room is N. s1 、The number of tubes in one bed and two rooms is N s2 、The number of tubes in the second bed is N s3 , air volume per bed and room N w1 、Air volume of one bed and two rooms N w2 , Second bed air volume N w3 , calculate the average work efficiency of each bed room:
[0021] Steam efficiency of one bed and one chamber: R s1 =N s1 / (N s1 +N s2 +N s3 ) Formula 4
[0022] Steam efficiency of one bed and two chambers: R s2 =N s2 / (N s1 +N s2 +N s3 ) Formula 5
[0023] Second bed steam efficiency: R s3 =N s3 / (N s1 +N s2 +N s3 ) Formula 6
[0024] Air volume efficiency per bed and room: R w1 =N w1 / (N w1 +N w2 +N w3 ) Formula 7
[0025] One bed two room air volume efficiency: R w2 =Nw2 / (N w1 +N w2 +N w3 ) Formula 8
[0026] Second bed air volume efficiency: R w3 =N w3 / (N w1 +N w2 +N w3 ) Formula 9
[0027] Average work efficiency of one bed and one room R1 in R s1 and R w1 The average working efficiency of one bed and two rooms is R2. s2 and R w2 The average working efficiency of the second bed is R3. s3 and R w3 between.
[0028] Furthermore, the step S03 is specifically as follows:
[0029] Estimated moisture content of PVC for one bed and one room:
[0030] Estimated moisture content of PVC in one bed and two chambers:
[0031] Estimated moisture content of PVC out of the second bed:
[0032] Where Y m It shows the measured value of PVC moisture content of the second bed.
[0033] Furthermore, the step S04 is specifically as follows:
[0034] The relationship between the amount of material in one bed and one chamber and the centrifuge current is as follows:
[0035]
[0036] Combining the energy and material balance formula of one bed and one chamber, and the estimated moisture content of PVC of one bed and one chamber, the model regression coefficient K is calculated based on the polynomial regression algorithm. w1 , K s1 and b1;
[0037] The relationship between the amount of material in one bed and two chambers and the centrifuge current is as follows:
[0038]
[0039] Combining the energy and material balance formula of one bed and two chambers, the estimated water content of PVC in one bed and two chambers, and the polynomial regression algorithm, the model regression coefficient K is calculated. w2 , Ks2 and b2;
[0040] The relationship between the amount of material in the second bed and the centrifuge current is as follows:
[0041]
[0042] Combining the energy and material balance of the second bed and the estimated water content of the PVC in the second bed, the model regression coefficient K is calculated based on the polynomial regression algorithm. w3 , K s3 and b3.
[0043] Furthermore, the step S05 is specifically as follows:
[0044] Calculate the soft measurement model of PVC moisture content in one bed and one chamber, the relationship formula between the material volume in one bed and one chamber and the centrifuge current, and the energy and material balance formula in one bed and one chamber. As an unknown variable, have to:
[0045]
[0046]
[0047]
[0048] Solved
[0049]
[0050] Taking a positive value, we can get the soft measurement model of PVC moisture content in one bed and one room:
[0051]
[0052] Calculate the soft measurement model of PVC moisture content in one bed and two chambers, combined with the relationship formula between the material amount in one bed and two chambers and the centrifuge current and the energy and material balance formula in one bed and two chambers. As an unknown variable, have to:
[0053]
[0054]
[0055] Solved
[0056]
[0057] Taking a positive value, we can get the soft measurement model of PVC moisture content in one bed and two chambers:
[0058]
[0059] Calculate the soft measurement model of the PVC moisture content of the second bed, combine the relationship formula between the second bed material amount and the centrifuge current and the energy and material balance formula of the second bed, then As an unknown variable, have to:
[0060]
[0061]
[0062]
[0063] Solved
[0064]
[0065] Taking a positive value, we can get the soft measurement model of the moisture content of the second bed PVC:
[0066]
[0067] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:
[0068] By using the soft measurement method of the present invention to obtain the moisture content of each bed chamber of the PVC device, the operator or the automatic control program can be guided in time to control the moisture content of the PVC, making the production process more stable, and "edge-carding" production can also be carried out to reduce over-drying and reduce energy consumption in the production process. BRIEF DESCRIPTION OF THE DRAWINGS
[0069] Figure 1 This is a schematic diagram of energy and material balance of PVC drying equipment;
[0070] Figure 2 The present invention is a schematic flow chart of a soft measurement method for PVC moisture content in a PVC drying device. DETAILED DESCRIPTION
[0071] The specific implementation process of the present invention is described in detail below in conjunction with the drawings and embodiments of the present invention. Obviously, the described implementation process is only a part of the examples of the present invention, rather than all the examples.
[0072] like Figure 1-2 As shown, the present invention is a soft measurement method for PVC moisture content of a PVC drying device. The PVC drying device of the present invention is an internally heated horizontal multi-chamber fluidized bed with a one-bed-one-chamber, one-bed-two-chamber, or two-bed structure, comprising the following steps:
[0073] Step S01: Establishing an energy balance model for each bed chamber of the PVC drying device;
[0074] According to the energy balance and material balance of the drying bed, the energy and material balance relationship of each bed chamber of the PVC drying device is established. The energy and material diagram is shown in the figure. Figure 1 As shown, we have:
[0075] Energy and material balance formula for one bed and one room:
[0076]
[0077] Energy and material balance formula for one bed and two chambers:
[0078]
[0079] Energy and material balance of the second bed:
[0080]
[0081] Where K w1 , K s1 , b1, K w2 , K s2 , b2, K w3 , K s3 , b3 represents the model regression coefficient, Q w1 Indicates the wind temperature of one bed and one room, Q s1 Indicates the opening of the steam valve for one bed and one chamber, X m Indicates the water content of PVC entering the drying bed, X f represents the centrifuge current, Indicates the estimated water content of PVC in one bed and one room, X f1 Indicates the amount of material in one bed and one chamber, Q w2 Indicates the wind temperature of one bed and two rooms, Q s2 Indicates the opening of the steam valve of the second chamber of the first bed. Indicates the estimated water content of PVC in one bed and two chambers, X f2 Indicates the amount of material in one bed and two chambers, Q w3 Indicates the air temperature of the second bed, Q s3 Indicates the opening of the steam valve of the second bed, Indicates the estimated water content of the second bed PVC, Y f Indicates the amount of material in the second bed.
[0082] Step S02: Calculate the average work efficiency of each bed room according to the number of tubes and the air volume of each bed room; the number of tubes in one bed and one room is Ns1, the number of tubes in one bed and two rooms is Ns2, the number of tubes in two beds is Ns3, the air volume of one bed and one room is Nw1, the air volume of one bed and two rooms is Nw2, and the air volume of two beds is Nw3, calculate the average work efficiency of each bed room.
[0083] Steam efficiency of one bed and one chamber: R s1 =N s1 / (N s1+N s2 +N s3 ) Formula 4
[0084] Steam efficiency of one bed and two chambers: R s2 =N s2 / (N s1 +N s2 +N s3 ) Formula 5
[0085] Second bed steam efficiency: R s3 =N s3 / (N s1 +N s2 +N s3 ) Formula 6
[0086] Air volume efficiency per bed and room: R w1 =N w1 / (N w1 +N w2 +N w3 ) Formula 7
[0087] One bed two room air volume efficiency: R w2 =N w2 / (N w1 +N w2 +N w3 ) Formula 8
[0088] Second bed air volume efficiency: R w3 =N w3 / (N w1 +N w2 +N w3 ) Formula 9
[0089] The average work efficiency of one bed and one room can be obtained by R1 in R s1 and R w1 The average working efficiency of one bed and two rooms is R2. s2 and R w2 The average working efficiency of the second bed is R3. s3 and R w3 between.
[0090] Step S03: estimating the PVC water content of each bed chamber according to the average working efficiency of one bed and one chamber, the average working efficiency of one bed and two chambers, and the average working efficiency of two beds;
[0091] Estimated moisture content of PVC for one bed and one room:
[0092] Estimated moisture content of PVC in one bed and two chambers:
[0093] Estimated moisture content of PVC out of the second bed:
[0094] Step S04: According to the air temperature of one bed and one chamber, the opening of the steam valve of one bed and one chamber, the water content of the PVC entering the drying bed, the current of the centrifuge, the estimated water content of the PVC leaving one bed and one chamber, the air temperature of one bed and two chambers, the opening of the steam valve of one bed and two chambers, the estimated water content of the PVC leaving one bed and two chambers, the air temperature of two beds, the opening of the steam valve of two beds, the estimated water content of the PVC leaving two beds, and the historical data of the water content of the PVC leaving two beds, the regression coefficient of the energy balance model of each bed chamber is calculated by using polynomial regression;
[0095] The relationship between the amount of material in one bed and one chamber and the centrifuge current is as follows:
[0096]
[0097] Combining "Formula 1", "Formula 10" and "Formula 13", based on the polynomial regression algorithm, the model regression coefficient K is calculated w1 , K s1 and b1.
[0098] The relationship between the amount of material in one bed and two chambers and the centrifuge current is as follows:
[0099]
[0100] Combining "Formula 2", "Formula 11" and "Formula 14", based on the polynomial regression algorithm, the model regression coefficient K is calculated w2 , K s2 and b2.
[0101] The relationship between the amount of material in the second bed and the centrifuge current is as follows:
[0102]
[0103] Combining "Formula 3", "Formula 12" and "Formula 15", based on the polynomial regression algorithm, the model regression coefficient K is calculated w3 , K s3 and b3.
[0104] Step S05: according to the model regression coefficient, the relationship between the material amount of each bed chamber and the centrifuge current, obtain a one-bed-one-chamber PVC moisture content soft measurement model, a one-bed-two-chamber PVC moisture content soft measurement model and a two-bed PVC moisture content soft measurement model;
[0105] Calculate the soft measurement model of PVC moisture content in one bed and one room, and substitute "Formula 13" into "Formula 1". As an unknown variable, have to:
[0106]
[0107]
[0108]
[0109] Solved
[0110]
[0111] Taking a positive value, we can get the soft measurement model of PVC moisture content in one bed and one room:
[0112]
[0113] Calculate the soft measurement model of PVC moisture content in one bed and two chambers, and substitute "Formula 14" into "Formula 2". As an unknown variable, have to:
[0114]
[0115]
[0116]
[0117] Solved
[0118]
[0119] Taking a positive value, we can get the soft measurement model of PVC moisture content in one bed and two chambers:
[0120]
[0121] Calculate the soft measurement model of the PVC moisture content of the second bed, and substitute "Formula 15" into "Formula 3". As an unknown variable, have to:
[0122]
[0123]
[0124]
[0125] Solved
[0126]
[0127] Taking a positive value, we can get the soft measurement model of the moisture content of the second bed PVC:
[0128]
[0129] Step S06: Based on the obtained one-bed-one-chamber PVC moisture content soft measurement model, one-bed-two-chamber PVC moisture content soft measurement model and two-bed PVC moisture content soft measurement model, substitute the real-time centrifuge current, one-bed-one-chamber air temperature, one-bed-one-chamber steam valve opening, one-bed-two-chamber air temperature, one-bed-two-chamber steam valve opening, two-bed air temperature and two-bed steam valve opening to obtain the PVC moisture content of each bed chamber of the drying device.
[0130] Example 1
[0131] It is known that the number of tubes in one bed and one chamber of the PVC drying device is 10, the number of tubes in one bed and two chambers is 8, the number of tubes in two beds is 5, the air volume of one bed and one chamber is 37740Nm3 / h, the air volume of one bed and two chambers is 25160Nm3 / h, and the air volume of two beds is 20100Nm3 / h.
[0132] Step S01: Establishing an energy balance model for each bed chamber of the PVC drying device;
[0133] Use "Formula 1", "Formula 2" and "Formula 3" to establish the energy balance formula for each bed room.
[0134] Step S02: Calculate the average working efficiency of each bed room according to the number of tubes in each bed room and the air volume; the number of tubes in one bed room is N s1 =10, the number of tubes in one bed and two rooms is N s2 =8, the number of tubes in the second bed is N s3 =5, air volume per bed per room N w1 =37740Nm3 / h, one bed two chamber air volume N f2 =25160, air volume of bed 2 N w3 =20100, calculate the average working efficiency of each PVC drying device bed chamber.
[0135] According to "Formula 4" to "Formula 9", we can get:
[0136] Steam efficiency of one bed and one chamber:
[0137] Steam efficiency of one bed and two chambers:
[0138] Second bed steam efficiency:
[0139] Air volume efficiency per bed and room:
[0140] One bed two room air volume efficiency:
[0141] Second bed air volume efficiency:
[0142] Get the average efficiency of one bed and one room R1 in Rs1 and R w1 The average working efficiency of one bed and two rooms is R2. s2 and R w2 The average working efficiency of the second bed is R3. s3 and R w3 One bed and one chamber and one bed and two chambers are generally in constant speed drying, so the drying efficiency of one bed and one chamber is approximately taken as the upper limit R1 = 0.45, the drying efficiency of one bed and two chambers is approximately taken as the upper limit R2 = 0.35, and the last two-bed efficiency R2 = 0.2.
[0143] Step S03: estimating the PVC water content of each bed chamber according to the average working efficiency of one bed and one chamber, the average working efficiency of one bed and two chambers, and the average working efficiency of two beds;
[0144] According to "Formula 10" to "Formula 12", we can get:
[0145] Estimated moisture content of PVC for one bed and one room:
[0146]
[0147] Estimated moisture content of PVC in one bed and two chambers:
[0148]
[0149] Estimated moisture content of PVC out of the second bed:
[0150]
[0151] Step S04: According to the air temperature of one bed and one chamber, the opening of the steam valve of one bed and one chamber, the water content of the PVC entering the drying bed, the current of the centrifuge, the estimated water content of the PVC leaving one bed and one chamber, the air temperature of one bed and two chambers, the opening of the steam valve of one bed and two chambers, the estimated water content of the PVC leaving one bed and two chambers, the air temperature of two beds, the opening of the steam valve of two beds, the estimated water content of the PVC leaving two beds, and the historical data of the water content of the PVC leaving two beds, the regression coefficient of the energy balance model of each bed chamber is calculated by using polynomial regression;
[0152] The historical data obtained from DCS are known to be:
[0153] PVC water content entering the drying bed
[0154] X m =[20, ...
[0155] Centrifuge current
[0156] X f =[959.9898,960.6766,960.6766,960.6766,961.4695,961.4695,961.4695,962.8806,962.8806,964.6827,964.6827,964.6827,966.5558,966.5558,966.5558,967.2399,967.2399,967.2399,968.2561,968.2561,9 68.7822,968.7822,968.7822,969.0177,969.0177,969.0177,969.0177,968.6261,968.6261,968.6261,968.7274,968.7274,968.7274,968.7274,968.7274,968.7274,969.2899,969.2899,969.6951,969.6951,969.6951,970.0254…………]
[0157] One bed one room wind temperature
[0158] Q w1 =[70.18522,70.18522,70.18227,70.18227,70.18227,70.18193,70.18193,70.18193,70.17501,70.17501,70.18316,70.18316,70.18316,70.19501,70.19501,70.205,70.205,70.19837 ,70.19837,70.19837,70.20314,70.20314,70.20314,70.20732,70.20732,70.20732,70.21532,70.21532,70.21532,70.21316,70.21316,70.21316,70.21316,70.22871,70.22871,70.23032,70.23032…………]
[0159] One bed one steam valve opening
[0160] Q s1=[49.6062,49.62636,49.62636,49.62636,49.6248,49.6248,49.6248,49.725,49.725,49.725,49.9499,49.9499,50.03474,50.03474,50.03474,49.88897,49.88897,49.88897,49.75253,49.75 253,49.75253,49.63682,49.63682,49.63682,49.63385,49.63385,49.63385,49.60633,49.60633,49.60633,49.58096,49.58096,49.58096,49.4339,49.4339,49.4339,49.3885,49.3885…………]
[0161] PVC moisture content of the second bed
[0162] Y m =[0.2201142,0.2201222,0.2201222,0.2201222,0.2201079,0.2201079,0.2201079,0.2201214,0.2201214,0.2201214,0.2201214,0.2201231,0.2201231,0.2201233,0.2201233,0.2192688,0.2192688,0.2191315,0.2191 315,0.2191315,0.2199955,0.2199955,0.2199955,0.2201111,0.2201111,0.2201111,0.2201111,0.2201225,0.2201225,0.2201225,0.2201232,0.2201232,0.2201156,0.2201156,0.2201223,0.2201223,0.2201223,0.2201384…………]
[0163] Put X m and Y m Substitute the estimated moisture content formula of PVC per bed and per chamber in step S03 to obtain
[0164] Put Xm , X f and Substitute into "Formula 13" to get the material quantity per bed and per room
[0165] X f1 =[888.8722108,889.727575,889.727575,889.727575,890.9750225,890.9750225,890.9750225,891.6812818,891.6812818,891.6812818,891.681281 8,892.1880733,892.1880733,892.1880733,892.5706902,892.5706902,892.5706902,892.0927541,892.0927541,892.0927541,892.0995281,892.0995 281,892.0995281,892.1226485,892.1226485,892.1226485,891.8935883,891.8935883,891.8935883,891.8935883,891.4531746,891.4531746,891.45 31746,891.5148517,891.5148517,891.5148517,890.9667664,890.9667664,890.9667664,889.8938312,889.8938312,889.8938312,889.0540597…………]
[0166] Substituting the above data into "Formula 1", we can get K by using multiple linear regression: w1 =-1.8704, K s1 =-0.3029, b1=241.7709.
[0167] The historical data obtained from DCS are known to be:
[0168] Drying bed PVC water content
[0169] X m =[20, ...
[0170] Centrifuge current
[0171] X f =[959.9898,960.6766,960.6766,960.6766,961.4695,961.4695,961.4695,962.8806,962.8806,964.6827,964.6827,964.6827,966.5558,966.5558,966.5558,967.2399,967.2399,967.2399,968.2561,968.2561,9 68.7822,968.7822,968.7822,969.0177,969.0177,969.0177,969.0177,968.6261,968.6261,968.6261,968.7274,968.7274,968.7274,968.7274,968.7274,968.7274,969.2899,969.2899,969.6951,969.6951,969.6951,970.0254…………]
[0172] One bed one room wind temperature
[0173] Q w2 =[70.18522,70.18522,70.18227,70.18227,70.18227,70.18193,70.18193,70.18193,70.17501,70.17501,70.18316,70.18316,70.18316,70.19501,70.19501,70.205,70.205,70.19837 ,70.19837,70.19837,70.20314,70.20314,70.20314,70.20732,70.20732,70.20732,70.21532,70.21532,70.21532,70.21316,70.21316,70.21316,70.21316,70.22871,70.22871,70.23032,70.23032…………]
[0174] Steam valve opening of one bed and one chamber
[0175] Q s2=[6.333407,6.333407,6.333407,6.200297,6.200297,6.200297,6.055783,6.055783,6.055783,5.924506,5.924506,5.924506,5.742271,5.742271,5.742271,5.552552,5.552552,5.42 7139,5.427139,5.427139,5.254878,5.254878,5.254878,5.059584,5.059584,5.059584,4.868194,4.868194,4.868194,4.665702,4.665702,4.665702,4.46069,4.46069,4.46069,4.296043…………]
[0176] PVC moisture content of the second bed
[0177] Y m =[0.2231437,0.2231597,0.2231597,0.2231597,0.2231655,0.2231655,0.2231243,0.2231243,0.2231243,0.2231382,0.2231382,0.2231382,0.2231193,0.2231193,0.2231414,0.2231414,0.2231441,0.2231441,0.2231441 31441,0.2210083,0.2210083,0.2210083,0.2193909,0.2193909,0.2193909,0.2182808,0.2182808,0.2182808,0.2182808,0.2173982,0.2173982,0.2173982,0.2171505,0.2171505,0.2171505,0.217131,0.217131,0.217131,0.2171171,0.2171171…………]
[0178] Put X m , and Y m Substitute the estimated moisture content formula of PVC in one bed and two chambers in step S03 to obtain
[0179]
[0180] Put X m , X f and Substitute into "Formula 14" to get the material volume of one bed and two chambers
[0181] X f2 =[824.2362862,825.1212121,825.1212121,825.1212121,825.6388713,825.6388713,825.6388713,826.1235846,826.1235846,826.1235846,826. 3604037,826.3604037,826.3604037,826.3604037,826.7554733,826.7554733,826.7554733,826.769368,826.769368,826.6312523,826.6312523, 826.6312523,826.3733069,826.3733069,826.3733069,826.3550488,826.3550488,826.3550488,826.018807,826.018807,826.018807,826.01880 7,825.5865473,825.5865473,825.5865473,824.9687888,824.9687888,824.9687888,824.4497892,824.4497892,824.4497892,824.1228338…………]
[0182] Substituting the above data into "Formula 2", we can get K by using multiple linear regression: w2 =-0.6167, K s2 =-0.0106, b2=107.4623.
[0183] The historical data obtained from DCS are known to be:
[0184] Drying bed PVC water content
[0185] X m =[20, ...
[0186] Centrifuge current
[0187] X f =[975.5849,976.7946,976.7946,976.7946,977.3351,977.3351,977.3351,976.8039,976.8039,976.8039,976.8108,976.8108,976.5169,976.5169,976.5169,975.7399,975.7399,975.7399,975.7399,975.7399,973.8231,973.8 231,973.8231,972.4662,972.4662,972.4662,971.6118,971.6118,971.6118,970.9789,970.9789,970.9789,970.5648,970.5648,970.5648,970.6761,970.6761,970.6761,971.4583,971.4583,971.4583,972.0311,972.0311…………]
[0188] Second bed air temperature
[0189] Q w3 =[72.35353,72.34954,72.34954,72.34954,72.34699,72.34699,72.34699,72.36195,72.36195,72.36195,72.35388,72.35388,72.35388,72.34925,72.34925,72.35365,72.35365,72.3604,72.3604,72.35 52,72.3552,72.3552,72.35472,72.35472,72.35472,72.35915,72.35915,72.35915,72.35915,72.35301,72.35301,72.35301,72.34594,72.34594,72.34594,72.35538,72.35538,72.35538,72.35835,72.35835…………]
[0190] Second bed steam valve opening
[0191] Q s3=[27.77851,27.7719,27.7719,27.7719,27.83441,27.83441,27.83441,27.90846,27.90846,27.90846,28.03874,28.03874,28.03874,28.14145,28.14145,28.01435,28.01435,28.06706,28.06706,27 .97021,27.97021,27.97021,27.8765,27.8765,27.8765,28.0461,28.0461,28.0461,28.1805,28.1805,28.19052,28.19052,28.19052,28.19052,28.19782,28.19782,28.19782,28.19008,28.19008…………]
[0192] PVC moisture content of the second bed
[0193] Y m =[0.2226267,0.2226267,0.2226267,0.223076,0.223076,0.223076,0.2231245,0.2231245,0.2231245,0.2231245,0.2239978,0.2239978,0.2239978,0.2241095,0.2241095,0.2241425,0.2241425,0.2241425,0.2241428,0.2241428 41428,0.2241085,0.2241085,0.2241085,0.2241195,0.2241195,0.2241195,0.22414,0.22414,0.22414,0.2241463,0.2241463,0.2241463,0.2241166,0.2241166,0.2241166,0.2241282,0.2241282,0.2241258,0.2241258,0.2241258 …………]
[0194] Put X m , and Y m Substitute into the formula for estimating the moisture content of the second bed PVC in step S103, and we get
[0195]
[0196] Put X m , X f and Substitute into "Formula 15" to get the material volume of the second bed
[0197] Y f =[786.6450598,787.0763042,787.0763042,787.0763042,787.1627805,787.1627805,787.1627805,787.2434795,787.2434795,787.2434795,787.243479 5,787.1695791,787.1695791,787.1695791,787.284834,787.284834,787.284834,786.9928211,786.9928211,786.9928211,786.8712043,786.8712043,78 6.8712043,786.6617236,786.6617236,786.6617236,786.7698131,786.7698131,786.7698131,786.7194729,786.7194729,786.7194729,786.3241901,786 .3241901,786.3241901,786.3709906,786.3709906,786.3709906,786.2279042,786.2279042,786.2279042,786.2277202,786.2277202,786.2277202…………]
[0198] Substituting the above data into "Formula 3", we can get K by using multiple linear regression: w3 =-2.5278, K s3 =-0.0018, b3=215.3529.
[0199] Step S05: according to the model regression coefficient, the relationship between the material amount of each bed chamber and the centrifuge current, obtain a one-bed-one-chamber PVC moisture content soft measurement model, a one-bed-two-chamber PVC moisture content soft measurement model and a two-bed PVC moisture content soft measurement model;
[0200] K w1 =-1.8704, K s1 =-0.3029, b1=241.7709 are substituted into "Formula 16" to obtain the soft measurement model of PVC moisture content in one bed and one room:
[0201]
[0202] K w2 =-0.6167, K s2 =-0.0106, b2 = 107.4623 are substituted into "Formula 17" to obtain the soft measurement model of PVC moisture content in one bed and two chambers:
[0203]
[0204] K w3 =-2.5278, K s3 =-0.0018, b3=215.3529 are substituted into "Formula 18" to obtain the soft measurement model of the moisture content of the second bed PVC:
[0205]
[0206] Step S06: Based on the obtained one-bed-one-chamber PVC moisture content soft measurement model, one-bed-two-chamber PVC moisture content soft measurement model and two-bed PVC moisture content soft measurement model, substitute the real-time centrifuge current, one-bed-one-chamber air temperature, one-bed-one-chamber steam valve opening, one-bed-two-chamber air temperature, one-bed-two-chamber steam valve opening, two-bed air temperature and two-bed steam valve opening to obtain the PVC moisture content of each bed chamber of the drying device.
[0207] K w1 =-1.8704, K s1 =-0.3029, b1=241.7709.
[0208] It is known that the moisture content of PVC entering the drying device is X m =20%, centrifuge X f =959.9898A, air temperature per bed per room Q w1 =70.1823℃, one bed one chamber steam valve opening Q s1 =49.6264.
[0209] Substituting the above values into "Formula 16", we get the PVC moisture content of one bed and one room:
[0210]
[0211] It is known that the moisture content of PVC entering the drying device is X m =20%, centrifuge X f =959.9898A, air temperature Q for one bed and two rooms w2 =70.8508℃, steam valve opening of one bed and two chambers Q s2 =6.3334, PVC moisture content of one bed and one room One bed one room load
[0212] Substituting the above values into "Formula 17", we get the PVC moisture content of one bed and two chambers:
[0213]
[0214] It is known that the moisture content of PVC entering the drying device is X m =20%, centrifuge X f =959.9898A, air temperature of bed 2 Q w3 =72.3604℃, second bed steam valve opening Q s3 =28.0671, one bed two chamber PVC moisture content One bed two room load
[0215]
[0216] In the actual production process, the data calculated by soft measurement can be Adjust the air temperature and steam valve opening in real time to keep the PVC moisture content within the desired range.
[0217] The invention discloses a soft measurement method for PVC moisture content of a PVC drying device. The method uses a parameter regression method to establish a mathematical model of moisture content of each bed chamber of the PVC device according to a material energy balance relationship. The PVC moisture content of each bed chamber is measured in real time according to the model, and the PVC moisture content of each bed chamber can be reflected in time. By real-time detection of PVC moisture content by the invention to guide the production process, the PVC drying device can reduce energy and stabilize the PVC moisture content.
[0218] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.
Claims
1. A soft measurement method for PVC moisture content in a PVC drying device, characterized in that: The steps include: Step S01: Establishing an energy balance model for each bed chamber of the PVC drying device; Step S02: Calculate the average working efficiency of each bed chamber according to the number of tubes and air volume of each bed chamber; Step S03: estimating the PVC water content of each bed chamber according to the average working efficiency of one bed and one chamber, the average working efficiency of one bed and two chambers, and the average working efficiency of two beds; Step S04: According to the air temperature of one bed and one chamber, the opening of the steam valve of one bed and one chamber, the water content of the PVC entering the drying bed, the current of the centrifuge, the estimated water content of the PVC leaving one bed and one chamber, the air temperature of one bed and two chambers, the opening of the steam valve of one bed and two chambers, the estimated water content of the PVC leaving one bed and two chambers, the air temperature of two beds, the opening of the steam valve of two beds, the estimated water content of the PVC leaving two beds, and the historical data of the water content of the PVC leaving two beds, the regression coefficient of the energy balance model of each bed chamber is calculated by using polynomial regression; Step S05: according to the model regression coefficient, the relationship between the material amount of each bed chamber and the centrifuge current, obtain a one-bed-one-chamber PVC moisture content soft measurement model, a one-bed-two-chamber PVC moisture content soft measurement model and a two-bed PVC moisture content soft measurement model; Step S06: Based on the obtained one-bed-one-chamber PVC moisture content soft measurement model, one-bed-two-chamber PVC moisture content soft measurement model and two-bed PVC moisture content soft measurement model, substitute the real-time centrifuge current, one-bed-one-chamber air temperature, one-bed-one-chamber steam valve opening, one-bed-two-chamber air temperature, one-bed-two-chamber steam valve opening, two-bed air temperature and two-bed steam valve opening to obtain the real-time PVC estimated moisture content of each bed chamber in the drying device; The step S01 specifically includes: establishing the energy and material balance relationship of each bed chamber of the PVC drying device according to the energy balance and material balance of the drying bed, and then: Energy and material balance formula for one bed and one room: Energy and material balance formula for one bed and two chambers: Energy and material balance of the second bed: Where K w1 , K s1 , b1, K w2 , K s2 , b2, K w3 , K s3 , b3 represents the model regression coefficient, Q w1 Indicates the wind temperature of one bed and one room, Q s1 Indicates the opening of the steam valve for one bed and one chamber, X m Indicates the water content of PVC entering the drying bed, X f represents the centrifuge current, Indicates the estimated water content of PVC in one bed and one room, X f1 Indicates the amount of material in one bed and one chamber, Q w2 Indicates the wind temperature of one bed and two rooms, Q s2 Indicates the opening of the steam valve of the second chamber of the first bed. Indicates the estimated water content of PVC in one bed and two chambers, X f2 Indicates the amount of material in one bed and two chambers, Q w3 Indicates the air temperature of the second bed, Q s3 Indicates the opening of the steam valve of the second bed, Indicates the estimated water content of the second bed PVC, Y f Indicates the amount of material in the second bed; The step S02 is specifically as follows: the number of tubes in one bed and one room is Ns1, the number of tubes in one bed and two rooms is Ns2, the number of tubes in two beds is Ns3, the air volume in one bed and one room is Nw1, the air volume in one bed and two rooms is Nw2, the air volume in two beds is Nw3, and the average working efficiency of each bed room is calculated: Steam efficiency of one bed and one chamber: R s1 =N s1 / (N s1 +N s2 +N s3 ) Formula 4 Steam efficiency of one bed and two chambers: R s2 =N s2 / (N s1 +N s2 +N s3 ) Formula 5 Second bed steam efficiency: R s3 =N s3 / (N s1 +N s2 +N s3 ) Formula 6: Air volume efficiency per bed per room: R w1 =N w1 / (N w1 +N w2 +N w3 ) Formula 7: Air volume efficiency of one bed and two rooms: R w2 =N w2 / (N w1 +N w2 +N w3 ) Formula 8 Second bed air volume efficiency: R w3 =N w3 / (N w1 +N w2 +N w3 ) Formula 9 Average work efficiency of one bed and one room R1 in R s1 and R w1 The average working efficiency of one bed and two rooms is R2. s2 and R w2 The average working efficiency of the second bed is R3. s3 and R w3 between; The step S03 is specifically as follows: Estimated moisture content of PVC for one bed and one room: Estimated moisture content of PVC in one bed and two chambers: Estimated moisture content of PVC out of the second bed: Where Y m It shows the measured value of PVC moisture content in the second bed; The step S04 is specifically as follows: The relationship between the amount of material in one bed and one chamber and the centrifuge current is as follows: Combining the energy and material balance formula of one bed and one chamber, and the estimated moisture content of PVC of one bed and one chamber, the model regression coefficient K is calculated based on the polynomial regression algorithm. w1 , K s1 and b1; The relationship between the amount of material in one bed and two chambers and the centrifuge current is as follows: Combining the energy and material balance formula of one bed and two chambers, the estimated water content of PVC in one bed and two chambers, and the polynomial regression algorithm, the model regression coefficient K is calculated. w2 , K s2 and b2; The relationship between the amount of material in the second bed and the centrifuge current is as follows: Combining the energy and material balance of the second bed and the estimated water content of the PVC in the second bed, the model regression coefficient K is calculated based on the polynomial regression algorithm. w3 , K s3 and b3; The step S05 is specifically as follows: Calculate the soft measurement model of PVC moisture content in one bed and one chamber, the relationship formula between the material volume in one bed and one chamber and the centrifuge current, and the energy and material balance formula in one bed and one chamber. As an unknown variable, have to: Solved Taking a positive value, we can get the soft measurement model of PVC moisture content in one bed and one room: Calculate the soft measurement model of PVC moisture content in one bed and two chambers, combined with the relationship formula between the material amount in one bed and two chambers and the centrifuge current and the energy and material balance formula in one bed and two chambers. As an unknown variable, have to: Solved Taking a positive value, we can get the soft measurement model of PVC moisture content in one bed and two chambers: Calculate the soft measurement model of the PVC moisture content of the second bed, combine the relationship formula between the second bed material amount and the centrifuge current and the energy and material balance formula of the second bed, then As an unknown variable, have to: Solved Taking a positive value, we can get the soft measurement model of the moisture content of the second bed PVC:
Citation Information
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