CN100475325C - Intelligent control method of PTA particle diameter in fine terephthalic acid production device - Google Patents

Abstract

An intelligent method for controlling the granularity of PTA particles in refined terephthalic acid (PTA) production includes such steps as selecting the temp and discharge flow of hydrogenating reactor, and the liquid levels and temp of the first and the second crystallizers and using them as the input variables of the soft measuring system of granularity, creating the affection relation of primary operating parameters to PTA granularity, real-time continuous acquisition of procedure data as the soft measured values, determining the difference between settings and measured values, and automatically controlling the liquid levels and temp of the first and the second crystallizers.

Description

The intelligence control method of PTA particle diameter in p-phthalic acid's process units

One, technical field

The invention belongs to Chemical Engineering and automation field, relate to p-phthalic acid (hereinafter to be referred as PTA, i.e. Pure TerephthalicAcid) produce in the intelligence control method of PTA product cut size.

Two, background technology

PTA is the important source material of producing polyester (PET), adopt PTA direct esterification polycondensating process owing to produce PET more, therefore all multifactor (as crystal size, the impurity content etc.) of related PTA product quality to esterification, and influences bigger to the preparation of EG/PTA slurry and conveying etc.Secondly, introduce one of PTA product granularity index according to MIRES crystallization theory and relevant technologies data---average grain diameter increases, and helps PTA slurry stability and paste-forming properties.Along with the purposes of polyester more and more widely, the continuous increase of demand, what promoted greatly that PTA produces develops rapidly, simultaneously the quality of PTA product is had higher requirement.Therefore further investigation influences the principal element of PTA crystallization process, and the PTA product cut size is stablized control, has realistic meaning to improving the PTA competitiveness of product in market.

The production technology of PTA is broadly divided into two classes: 1. two step method: at first with paraxylene (PX) through air oxidation, make crude terephthalic acid (TA), and then TA be refined into PTA; 2. one-step method: PX only obtains terephthalic acid (TPA) through peroxidization.Among the PTA that makes with two step method, its representational impurity---usually below 25ppm, and 4-CBA content is 200～300ppm among the PTA that one-step method makes to the content of carboxyl benzaldehyde (4-CBA).

In the two step method production technology, can be divided three classes again by the process for purification difference: the first kind is applied hydrofinishing methods such as Mitsui petro-chemical corporation, U.S. Amoco company, Britain ICI company; Second class is applied accurate oxidizing process such as Mitsubishi changes into, Eastman Kodak company; The 3rd class is dimethyl terephthalate (DMT) (DMT) method for refining that Dynamitonobel company etc. implements.Wherein first kind method is because production cost is lower, product quality is more stable, is to produce be most widely used in the middle of the method for PTA a kind of at present.Accounting for the product of PTA product total output more than 70% in the world all is to adopt this method to produce.The present invention is promptly at the hydrofining technology in the PTA two step method.

Usually, the hydrofining technology flow process is: on the technology the thick TA water behind the oxidation unit drying crystalline is dissolved into certain density slurry, is heated to and requires to deliver to hydrogenation reactor after the solution temperature.With Pd/C (palladium/carbon) is catalyst, by catalytic hydrogenation reaction, makes that impurities is converted into water-soluble substances in the crude terephthalic acid.Hydrogenation reaction solution is sent to centrifuge step by step after the decrease temperature and pressure and is separated in the crystallizer of series connection, the filter cake that obtains is again with the deionized water making beating, then after filtration and dry, makes fibre-grade p-phthalic acid (PTA).

The major influence factors that influences the PTA particle diameter has: 1) slurry concentration; 2) mould temperature distributes; 3) time of staying in the crystallizer; 4) agitator structure shape and stirring intensity; 5) pH value of solvent, impurity.Wherein, mould temperature distributes more main with the time of staying, and they also are the major parameters of regulating particle size in the actual production process.

In the PTA production process, with regard to present prior art, can't carry out online actual measurement to particle size, normally every day is by manually the mixed sample of multiple spot collection once being analyzed.Because manual analysis exists bigger analysis to lag behind, like this under the situation that the PTA particle diameter changes, often can't in time adjust the operation operating mode, perhaps, owing to there is more influence factor, only rely on the manually-operated experience, can't quantitatively regulate simultaneously a plurality of performance variables, may cause " toning " or the regulating action of product cut size slow, these all will directly have influence on product quality.

Three, summary of the invention

The objective of the invention is: the intelligence control method that a kind of PTA particle diameter is provided.Nerual network technique prediction average grain diameter is used in this invention; Utilize the soft measured value of this average grain diameter simultaneously, crystallizer pressure, liquid level, as regulated variable according to the adjusting priority of each variable, are realized the automatic adjustment to each regulated variable, to satisfy the control requirement of particle diameter.The present invention seeks under many influence factors condition, provide a kind of and in time the operation operating mode is adjusted, guarantee the more accurate adjusting of product cut size, thereby guarantee product quality by particle diameter control.

The object of the present invention is achieved like this: utilize charging, first mould temperature, first mould liquid level, second mould temperature of hydrogenation reaction actuator temperature, hydrogenation reactor, the real-time image data of second mould liquid level, use nerual network technique prediction average grain diameter; Utilize the soft measured value of this average grain diameter simultaneously, get the first crystallizer pressure, first mould liquid level, the second crystallizer pressure, second mould liquid level as regulated variable, according to the adjusting priority of each variable, realize automatic adjustment, to satisfy the control requirement of particle diameter to each regulated variable.

At first, utilize nerual network technique, set up the soft measuring system of average grain diameter.The input variable of this system has 5, is respectively: the temperature difference between (1) hydrogenation reactor and first crystallizer, Δ T ₁The time of staying of (2) first crystallizers, τ ₁The temperature difference between (3) first crystallizers and second crystallizer, Δ T ₂The time of staying of (4) second crystallizers, τ ₂(5) the PTA granularmetric analysis value in the preceding moment.

Simultaneously, consider the different time of different variablees,, need choose the current time input variable data of different unit interval according to concrete commercial plant situation to grain diameter influence.As suppose that the soft measured value of particle diameter only considers the second crystallizer exit, when then choosing the data of hydrogenation reactor correlated variables (as temperature and flow), need choose preceding two units of current time data constantly; When choosing the data of the first crystallizer correlated variables (as temperature), need choose the previous unit of current time data constantly; When choosing the data of the second crystallizer correlated variables, need choose the data of current time.

Utilize formula (1), obtain system's input variable:

$\left\{\begin{array}{c}{x}_1={\mathrm{\&Delta;<figure-callout\; id="1"\; label="T"\; filenames="C20041001499600131.png,C20041001499600151.png"\; state="\{\{state\}\}">T</figure-callout>}}_1=T_{\mathrm{reactor}}(t-t_1)-{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="C20041001499600131.png,C20041001499600151.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1\mathrm{st}-\mathrm{crys}}(t-t_2)\\ x_2={\mathrm{\&tau;}}_1={\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C20041001499600131.png,C20041001499600151.png"\; state="\{\{state\}\}">L</figure-callout>}}_{1\mathrm{st}-\mathrm{crys}}(t-t_2)/F_{\mathrm{reactor}}(t-t_1)\\ x_3={\mathrm{\&Delta;<figure-callout\; id="2"\; label="T"\; filenames="C20041001499600131.png,C20041001499600141.png"\; state="\{\{state\}\}">T</figure-callout>}}_2={\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="C20041001499600131.png,C20041001499600151.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1\mathrm{st}-\mathrm{crys}}(t-t_1)-T_{2\mathrm{nd}-\mathrm{crys}}\left(t\right)\\ x_4={\mathrm{\&tau;}}_2=L_{2\mathrm{nd}-\mathrm{crys}}\left(t\right)/F_{\mathrm{reactor}}(t-t_1)\\ x_5=G_{i-1}\end{array}\right.---\left(1\right)$

Here, T _Reactor(t-t ₁) the preceding t of expression current time ₁Temperature of reactor constantly, T _1st-crys(t-t ₂) the preceding t of expression current time ₂First mould temperature constantly, L _1st-crys(t-t ₂) the preceding t of expression current time ₂First mould liquid level constantly, F _Reactor(t-t ₁) the preceding t of expression current time ₁Reactor flow constantly, T _2nd-crys(t) second mould temperature of expression current time, L _2nd-crys(t) second mould liquid level of expression current time, G _T-1The particle size values of expression previous moment.

Utilize formula (2), the input variable of above-mentioned soft-sensing model is carried out normalized;

${\mathrm{sx}}_i=\frac{x_i-x_{\min }^i}{x_{\max }^i-x_{\min }^i}*({\mathrm{sx}}_{\max }^i-{\mathrm{sx}}_{\min }^i)+{\mathrm{sx}}_{\min }^i,i=\mathrm{1,2,3,4,5},---\left(2\right)$

(2) in the formula, x _iBe the actual measured value of i input variable of soft-sensing model (being independent variable), sx _iRepresent after i the input variable normalization value as the neutral net input,

Expression collects the excursion of i input variable, and the excursion of input independent variable is after the normalization

Here, the BP neutral net of employing three-decker is set up the soft measuring system of particle diameter.In the soft measuring system of this neutral net, the node number of input layer is i (i=5), and the hidden layer number of plies in intermediate layer is l (l=1～100), and each the number of hidden nodes is j (j=2～100), and the output layer node is k (k=1).Historical data by acquisition system input, output variable is trained network, after precision meets the demands, and record network structure and weights.

After obtaining the soft measured value of particle diameter, just can be according to the control setting value requirement of particle diameter, selected performance variable is automatically adjusted, select first mould liquid level, the first crystallizer pressure, second mould liquid level, the second crystallizer pressure here as performance variable.

Owing to comprised the influence of first mould liquid level, first mould temperature, second mould liquid level, second mould temperature in the soft measuring system to particle diameter, and, direct linear correlation between each mould temperature and the pressure, promptly can change temperature by pressure parameter, and further influence particle diameter, therefore, can pass through these technology adjustable parameters, carry out the control of particle diameter.At first need to determine the adjusting priority of each regulated variable, be as supposition adjusting priority orders:

First mould liquid level＞first crystallizer the pressure＞second mould liquid level＞second crystallizer the pressure

Then in the adjustment process of particle diameter, the adjusting of first mould liquid level will at first be carried out in allowing opereating specification, utilize soft measuring system to making linearization process near the current operating point in the adjustment process, and the dichotomy that utilizes one dimension to optimize in the searching algorithm carries out choosing of first mould liquid level optimization operating point, if first mould liquid level has arrived the adjustable range border, then begin to carry out the adjusting of the first crystallizer pressure; By that analogy, all arrive the control border until the control requirement of satisfying particle diameter or regulated variable.

Calculate the regulated variable of flex point for soft measuring system occurring, promptly regulated variable does not satisfy the linear transformation principle with particle diameter, then gets and the most close operating point of the current operation operating mode of this variable.

Characteristics of the present invention: the intelligence control method that a kind of PTA particle diameter is provided.This method can be carried out particle diameter and carry out real-time soft measurement by other process variables (as flow, temperature, liquid level etc.) that easily detects.Simultaneously, adopt programme-control, can a plurality of major influence factors that influence particle diameter be automatically adjusted.Owing to adopt the soft measuring system of neutral net to carry out the particle diameter real-time estimate, improved the precision of prediction and the fault freedom of particle diameter greatly, further guaranteed the control quality.The present invention can generally be applicable to the production technology of utilizing the hydrofinishing method to produce PTA.

In addition, also can promptly introduce the soft measuring system that variablees such as slurry density, stir current, the 3rd mould temperature and liquid level, the 4th mould temperature and liquid level, the 5th mould temperature are set up the PTA particle diameter by the just amount that increases, method is consistent with the thinking of mentioning in this invention.And regulated variable equally also can expand to these newly-increased adjustable variables on original basis.

Four, description of drawings

PTA hydrofining technology FB(flow block) has been described among Fig. 1,

Wherein: corresponding numeral is 1 to enter the load flow of hydrogenation reactor; 2. hydrogenation reaction actuator temperature indication; 3. first mould temperature indication; 4. first mould liquid level indication; 5. second mould temperature indication; 6. second mould liquid level indication.As shown in Figure 1, the artificial sample analysis of PTA product cut size records in discharging place of PTA product.

Fig. 2 is the soft measuring system block diagram of PTA granularity neutral net, the x in 5 the input variables difference counterparty's formulas (1) shown in the figure ₁～x ₅The node of input layer is i (i=5), and the hidden node in intermediate layer is j (j=7), and the output layer node is k (k=1), and the input variable of soft measuring system is carried out normalized, and the normalization scope of choosing here is [0.2 0.8].

Fig. 3 is a PTA particle diameter automatic control program block diagram.

Five, the specific embodiment

The invention will be further described below in conjunction with accompanying drawing and by embodiment:

Load flow and temperature, first mould temperature and liquid level, second mould temperature and liquid level according to hydrogenation reactor, and the granularmetric analysis value of previous moment, by computer system (as DCS system or real-time data base), obtain before the hydrogenation reactor current time 1 hour load flow and temperature value, temperature and the level value of half an hour before the first crystallizer current time, the temperature of the second crystallizer current time and level value.

By historgraphic data recording, choose 100 groups of data of above-mentioned variable, utilize equation (1) to obtain the input data of the soft measuring system of neutral net, and carry out normalized, utilize the current manual analysis value of particle diameter to do desired value.With 50 groups of neural network trainings,, trained and one group of weights that predicated error is less with 50 groups of prediction neutral net generalization abilities; Here, the neutral net input variable is 5, and choosing the hidden node number is 7, and output variable is 1.Can choose the different hidden layer numbers of plies and hidden node number according to requirement to soft measuring system precision; In general, the increase hidden layer number of plies in the proper range and the number of node thereof can the soft measuring system precision of corresponding raising.After training, obtain following one group of weights:

w ₁₁＝--0.55531 w ₁₂＝0.63814 w ₁₃＝0.85929 w ₁₄＝-0.13105 w ₁₅＝0.4398

w ₂₁＝0.34733 w ₂₂＝0.57198 w ₂₃＝0.13712 w ₂₄＝-0.4362 w ₂₅＝0.40703

w ₃₁＝-0.52782 w ₃₂＝0.26804 w ₃₃＝-0.39269?w ₃₄＝-0.01?8656?w ₃₅＝0.83147

w ₄₁＝0.11692 w ₄₂＝2.2245 w ₄₃＝-0.44579?w ₄₄＝-0.1445 w ₄₅＝0.68512

w ₅₁＝-0.5777 w ₅₂＝0.55799 w ₅₃＝-0.46309?w ₅₄＝-0.20686 w ₅₅＝0.171

w ₆₁＝0.32117 w ₆₂＝1.0526 w ₆₃＝-0.242 w ₆₄＝0.066991 w ₆₅＝0.87777

w ₇₁＝-0.35918 w ₇₂＝0.7199 w ₇₃＝0.25523 w ₇₄＝-0.2242 w ₇₅＝-0.38332

ww ₁＝-2.676 ww ₂＝2.371 ww ₃＝2.1013 ww ₄＝-2.686 ww ₅＝-2.2008

ww ₆＝3.6055 ww ₇＝3.6055

b ₁＝-0.94256?b ₂＝1.7425 b ₃＝1.1609?b ₄＝0.025712?b ₅＝2.3402?b ₆＝-0.19773

b ₇＝0.32666

bpb ₁＝-3.8373

(w wherein _IjBe the weights of i node to j node; Ww _jBe the weights of j node of middle hidden layer to k node of output layer; b _jThreshold value for j node of middle hidden layer; Bpb _kThreshold value for the output layer node)

It more than is the off-line simulation process, in the real time execution of device, then need go up the establishment that realizes the said process control language at the AM/APM of the DCS of PTA process units system (APPLICATION MODULE/ADVANCED PROCESS MANAGER), real-time, continuous acquisition by DCS systematic procedure data (referring to each input variable data in the soft measuring system here), the weights and the threshold value that train are brought into and calculated, just can obtain the real-time soft measurement predicted value of PTA particle diameter; The soft measuring system output valve that obtain this moment is utilized (3) formula between [0.1,0.9], carry out anti-normalized, obtains the actual value of particle diameter.

G _t＝(sG _t-sG _min)/(sG _max-sG _min)*(G _max-G _min)+G _min (3)

In addition, for guarantee soft measuring system accurately, effectively the operation, utilize the manual analysis value carry out " rollings " correction.

As choose the corresponding value constantly of on-the-spot each variable, then obtain soft measuring system input variable x according to equation (1) ₁～x ₅Be respectively 38.6570,0.2399,28.4619,0.2352,100, after arriving between [1 1] after the normalization, numerical value is respectively 0.0771, and-0.0202,0.3975 ,-0.0296,0, then calculate by the soft measuring system of neutral net:

net1＝w ₁₁*x ₁+w ₁₂*x ₂+w ₁₃*x ₃+w ₁₄*x ₄+w ₁₅*x ₅+b ₁ (4)

net2＝w ₂₁*x ₁+w ₂₂*x ₂+w ₂₃*x ₃+w ₂₄*x ₄+w ₂₅*x ₅+b ₂ (5)

net3＝W ₃₁*x ₁+w ₃₂*x ₂+w ₃₃*x ₃+w ₃₄*x ₄+w ₃₅*x ₅+b ₃ (6)

net4＝w ₄₁*x ₁+w ₄₂*x ₂+w ₄₃*x ₃+w ₄₄*x ₄+w ₄₅*x ₅+b ₄ (7)

net5＝w ₅₁*x ₁+w ₅₂*x ₂+w ₅₃*x ₃+w ₅₄*x ₄+w ₅₅*x ₅+b ₅ (8)

net6＝w ₆₁*x ₁+w ₆₂*x ₂+w ₆₃*x ₃+w ₆₄*x ₄+w ₆₅*x ₅+b ₆ (9)

net7＝w ₇₁*x ₁+w ₇₂*x ₂+w ₇₃*x ₃+w ₇₄*x ₄+w ₇₅*x ₅+b ₇ (10)

out1＝2/(1+exp(-2*net(1)))-1 (11)

out2＝2/(1+exp(-2*net(2)))-1 (12)

out3＝2/(1+exp(-2*net(3)))-1 (13)

out4＝2/(1+exp(-2*net(4)))-1 (14)

out5＝2/(1+exp(-2*net(5)))-1 (15)

out6＝2/(1+exp(-2*net(6)))-1 (16)

out7＝2/(1+exp(-2*net(7)))-1 (17)

net8＝ww ₁*out1+ww ₂*out2+ww ₃*out3+ww ₄*out4+ww ₅*out5+ww ₆*out6+ww ₇*out7+bpb ₁

(18)

out8＝net8 (19)

out9＝(out8-0.05)*150+70 (20)

When bringing weights, threshold value to (4)～(20) into, out9 is the particle diameter predicted value that the soft measuring system of neutral net calculates, and error is within ± 5% between grain diameter measurement value that obtains and the manual analysis value.

After obtaining the particle diameter predicted value of soft measuring system, can control it.The adjustment priority of setting regulated variable is:

First mould liquid level＞first crystallizer the pressure＞second mould liquid level＞second crystallizer the pressure

If the setting value of current first mould liquid level is 50%, allowing adjustable range is [20 70]; The setting value of the first crystallizer pressure is 3.6MPa, and allowing adjustable range is [2.6 4.6]; The setting value of second mould liquid level is 50%, and allowing adjustable range is [20 70]; The setting value of the second crystallizer pressure is 2.6MPa, and allowing adjustable range is [1.6 3.6].

And, obtained the conversion relational expression of temperature and pressure:

T1=181+18*P1=245 ℃; (first mould temperature and pressure transformational relation)

T2=169+23*P2=228.8 ℃; (second mould temperature and pressure transformational relation)

Read current operation operating mode, calculating current particle diameter by soft measuring system is 120 μ m, if require particle diameter to be controlled within [100 110] μ m, illustrates that then current particle diameter does not meet the demands, and need regulate.

At first, if first mould liquid level satisfies near the condition of the available linearization of operating point, then can calculate first mould liquid level in the particle size values on 20%, 70% border, under the constant situation of other variable according to soft measuring system, its result of calculation is respectively 90,140, and then explanation can be by only realizing the control requirement of particle diameter to the adjustment of first mould liquid level.Therefore, between liquid level adjustable range [20 70], can utilize one dimension to optimize searching method,, seek an operating point and make the soft measuring system calculated value of particle diameter within [100 110] μ m as dichotomy, Fibonacci method etc.Then, install in the bottom control loop realization particle diameter control requirement under the optimal value that liquid level is calculated.

If technology allows the adjustable range of first crystallizer to narrow down, promptly only allow between [45 65], to regulate, then utilizing the particle size values on the operational boundaries that soft measuring system calculates is 112 and 125, only illustrates can't to realize the control requirement of particle diameter by the adjustment to first mould liquid level.Like this, just need operate under the situation of low limit value (45%), carry out adjusting the first crystallizer Pressure/Temperature at first mould liquid level.Control method is similar to the liquid level adjustment process, and at first the particle diameter calculated value of calculating pressure on [2.6 4.6] operational boundaries if the particle size values that obtains then can be passed through optimization method within [100 110] μ m, sought suitable force value to satisfy the control requirement; If the particle size values that obtains does not still satisfy within [100 110] μ m, then carry out next variable, i.e. the adjustment of second mould liquid level.By that analogy, until satisfying particle diameter control requirement, perhaps all variable has all arrived operational boundaries.

In the process that above-mentioned variable is regulated, if the condition that certain variable does not satisfy near the available linearization of operating point occurs, then in two segment limits of flex point and operational boundaries, search for the adjusting parameter that meets the demands respectively, then the current operation operating mode of new operating point and this variable is compared, get the shortest operating point of both normal form distances as new technological operation point.

The condition of above-mentioned requirements all can satisfy, so this invention has universality in most PTA process units.

Claims (3)

1, a kind of intelligence control method of commercial plant PTA particle diameter, it is characterized in that utilizing the process variables that easily detects in the production process, be flow, the temperature of 2 unit interval before the hydrogenation reactor current time, 1 unit temperature and liquid level, the temperature of the second crystallizer current time and granularmetric analysis value of liquid level and previous moment constantly before the first crystallizer current time, the incidence relation of existing DCS system data and PTA particle diameter is set up model with nerual network technique; By real-time, continuous acquisition to above-mentioned model input variable, the weights and the threshold value that train are brought into and calculated, obtain the real-time estimate value of PTA particle diameter; Then, according to model a plurality of major influence factors that influence particle diameter are realized regulating automatically; The neutral net flexible measurement method of PTA particle diameter is: the difference Δ T of the temperature in 1 unit moment before the temperature of choosing 2 unit interval before the hydrogenation reactor current time and the first crystallizer current time ₁, 1 time of staying τ constantly of unit before the first crystallizer current time ₁, the difference Δ T of the temperature of the temperature of 2 unit interval and the second crystallizer current time before the hydrogenation reactor current time ₂, the second crystallizer current time time of staying τ ₂And the granularmetric analysis value of previous moment, as the input variable of the soft measuring system of neutral net, with the current particle diameter of real-time estimate.

$\left\{\begin{array}{c}{x}_1=\mathrm{\&Delta;}{T}_1=T_{\mathrm{reactor}}(t-t_1)-T_{1\mathrm{st}-\mathrm{crys}}(t-t_2)\\ x_2={\mathrm{\&tau;}}_1=L_{1\mathrm{st}-\mathrm{crys}}(t-t_2)/F_{\mathrm{reactor}}(t-t_1)\\ x_3=\mathrm{\&Delta;}{T}_2=T_{1\mathrm{st}-\mathrm{crys}}(t-t_1)-T_{2\mathrm{nd}-\mathrm{crys}}\left(t\right)\\ x_4={\mathrm{\&tau;}}_2=L_{2\mathrm{nd}-\mathrm{crys}}\left(t\right)/F_{\mathrm{reactor}}(t-t_1)\\ x_5=G_{t-1}\end{array}\right.---\left(1\right)$

T _Reactor(t-t ₁) the preceding t of expression current time ₁Temperature of reactor constantly, T _1st-crys(t-t ₂) the preceding t of expression current time ₂First mould temperature constantly, L _1st-crys(t-t ₂) the preceding t of expression current time ₂First mould liquid level constantly, F _Reactor(t-t ₁) the preceding t of expression current time ₁Reactor flow constantly, T _2nd-crys(t) second mould temperature of expression current time, L _2nd-crys(t) second mould liquid level of expression current time, G _T-1The particle size values of expression previous moment; The input variable of neural network model is: Δ T ₁(x ₁, ℃), τ ₁(x ₂, mins), Δ T ₂(x ₃, ℃), τ ₂(x ₄, mins), G _T-1(x ₅,

), and carry out normalized:

${\mathrm{sx}}_i=\frac{x_i-x_{\min }^i}{x_{\max }^i-x_{\min }^i}*({\mathrm{sx}}_{\max }^i-{\mathrm{sx}}_{\min }^i)+{\mathrm{sx}}_{\min }^i$ i＝1，2，3，4，5(2)

(2) in the formula, x _iBe the actual measured value of i input variable of soft-sensing model (being independent variable), sx _iRepresent after i the input variable normalization value as the neutral net input,

Expression collects the excursion of i input variable, and the excursion of input independent variable is after the normalization

To collecting n1 group data, wherein every group of data comprise [x ₁, x ₂, x ₃, x ₄, x ₅, G _t], after normalization [sx ₁, sx ₂, sx ₃, sx ₄, sx ₅, sG _t], form training sample.To PTA particle diameter G _tNeural network model, with [sx ₁, sx ₂, sx ₃, sx ₄, sx ₅] as the input of network, corresponding PTA particle diameter sG _tAs desired value, training network; The adjustment priority of setting regulated variable is:

First mould liquid level＞first crystallizer the pressure＞second mould liquid level＞second crystallizer the pressure

If the setting value of current first mould liquid level is 50%, allowing adjustable range is [2070]; The setting value of the first crystallizer pressure is 3.6MPa, and allowing adjustable range is [2.64.6]; The setting value of second mould liquid level is 50%, and allowing adjustable range is [2070]; The setting value of the second crystallizer pressure is 2.6MPa, and allowing adjustable range is [1.63.6]; The conversion relational expression of temperature and pressure:

T1=181+18*P1=245 ℃ of first mould temperature and pressure transformational relation;

T2=169+23*P2=228.8 ℃ of second mould temperature and pressure transformational relation.

2, by the intelligence control method of the described commercial plant PTA of claim 1 particle diameter, it is characterized in that soft measuring system predicted value at set intervals with the manual analysis value to soft measuring system output carry out online " rollings " and optimize correction.

3,, it is characterized in that according to the soft measuring system of particle diameter, to first mould liquid level, pressure, the operating condition of second mould liquid level, pressure is regulated in real time by the intelligence control method of the described commercial plant PTA of claim 1 particle diameter; And carry out the linearization process of current operating point in adjustable range according to soft measuring system; For the regulated variable that flex point occurs, get and the most close operating point of the current operation operating mode of this variable.

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