CN104130130A

CN104130130A - Nylon salt solution preparation processes with trim diamine mixing

Info

Publication number: CN104130130A
Application number: CN201410141681.3A
Authority: CN
Inventors: 罗伯特·J·韦尔奇; 利恩·曼斯特; 保罗·诺米科斯
Original assignee: Scientific & Technical Corp Of English Weida
Current assignee: Invista Textiles UK Ltd
Priority date: 2013-05-01
Filing date: 2014-04-10
Publication date: 2014-11-05
Anticipated expiration: 2034-04-10
Also published as: TW201446730A; CN104130130B; WO2014179064A1

Abstract

Disclosed are nylon salt solution preparation processes including a trim diamine feed. The trim diamine is added to a recirculation loop in a continuous stirred tank reactor, where it is blended with the nylon salt solution via a pump. The nylon salt solution is prepared by feeding a dicarboxylic acid monomer and a diamine monomer to a single continuous stirred tank reactor. The dicarboxylic acid is metered, based on weight, from a loss-in-weight feeder to the reactor. The nylon salt solution is formed continuously and has low variability from a target pH and/or a target salt solution concentration. The nylon salt solution is transferred directly to a storage tank, without further monomer addition, pH adjustment, or salt solution adjustment after exiting the continuous stirred tank reactor.

Description

Use and supplement the nylon salt solution manufacturing method that diamines mixes

the cross reference of related application

The application requires to enjoy in the right of priority of the U. S. application 61/818067 of submitting on May 1st, 2013, the full content of this application and disclose incorporated herein.

Technical field

The present invention relates to the preparation of nylon salt solution, relate in particular to the preparation of using the nylon salt solution that supplements diamines charging.This supplementary diamines charging can be combined with nylon salt solution by pump in continuous stirred tank reactor recirculation line.This pump can affect mixing.

Background technology

Polymeric amide can be used for engineering thermoplasties, electronics, Sports facilities and the various industrial application of the molding portion of weaving, clothes, packing, tire enhancing, carpet, automobile conventionally.Nylon is a kind of high performance material, and it can be used for plastics and fiber aspect that requirement possesses excellent weather resistance, thermotolerance and toughness.The fatty polyamide that is called as nylon can be prepared by the salts solution of dicarboxylic acid and diamines.To after described salts solution evaporation, heat so that its polymerization.A challenge in this kind of production method is exactly to guarantee that dicarboxylic acid has consistent mol balance with diamines in last polymeric amide.For example, when producing nylon-6 by hexanodioic acid (AA) and hexanediamine (HMD), 6 o'clock, inconsistent mol balance can adversely cause molecular weight to reduce, and affected the dyeability of nylon.By utilization salt technique at intermittence, realized mol balance, but batch technology is not suitable for large-scale industrial production.In addition, mol balance also can be realized by a plurality of reactors under continuous mode, and in the production of salt, each reactor all has independent diamines supply.

US2130947 has described a kind of suc as formula H ₂nCH ₂rCH ₂nH ₂shown diamines and formula HOOCCH ₂r ' CH ₂the salts solution of the dicarboxylic acid shown in COOH, wherein, R and R ' are that R has the chain length that is at least two carbon atoms not containing olefinic and the undersaturated bivalent hydrocarbon radical of acetylene series.Measure the pH value of salts solution, and definite flex point.Then described salts solution is fed in reactor, to form polymeric amide.

US2012/0046439 has described the preparation method of a kind of diacid for the preparation of polymeric amide and diamine salts solution.The method comprises mixes at least two kinds of diacid and at least one diamines, wherein the weight concentration of salt is 40～70%, described method comprises: in the first step, utilize a kind of diacid and a kind of diamines to prepare the aqueous solution of diacid and diamines, wherein the mol ratio of diacid and diamines is less than 1, and in second step, adjust the mol ratio of diacid and diamines to 0.9-1.1, and by the weight concentration that adds another kind of sour with optionally extra water and/or diamines to revise salt.

US2010/0168375 has described the salts solution of diamines and diacid, the strong solution of hexamethylene-diamine adipate especially, and it can be used as the parent material of producing polymeric amide, especially producing PA66.Described solution can be by mixing (wherein the weight concentration of salt is 50-80%) by diamines and diacid in the first step, so that the aqueous solution (wherein the mol ratio of diacid/diamine is greater than 1.1) of diacid and diamines to be provided, and in second step by adding diamines that the mol ratio of diacid/diamine is adjusted into 0.9-1.1, preferred 0.99-1.01, and optionally add wherein water to prepare to revise the weight concentration of salt.

US4233234 has described the method for the aqueous solution of the salt of a kind of alkane dicarboxylic acid of a continuous production 6-12 carbon atom and the alkane diamine of 6-12 carbon atom, by specific alkane dicarboxylic acid and specific alkane diamine are reacted and prepared in the aqueous solution of the salt that will prepare.The aqueous solution of salt is circulated to the first mixing zone from the first mixing zone by transmission range and the second mixing zone, and liquid alkane diamines and alkane dicarboxylic acid's aqueous solution are introduced between the first mixing zone and the second mixing zone.Introducing is less than the alkane diamine of equivalent, and the liquid alkane diamines of residual content adds after the second mixing zone, and the aqueous solution of described salt shifts out from the first mixing zone with the speed of its formation.

US6995233, US6169162, US5674794 and US3893811 all disclose polymerization reactor.

Although attempted improving technique to obtain target component, as the salt concn in suitable pH value, mol balance and/or nylon salt solution, but still existed challenge.Especially dicarboxylic acid, is more particularly hexanodioic acid, and it is the powder with variable particle size, thereby makes bulk density change very large.Adopt dicarboxylic acid powder will introduce another variable, thereby make to be difficult to the consistence of realize target parameter in continuous processing.Volumetric feeder for dicarboxylic acid powder has aggravated this difficulty.Consider the conforming difficulty of realize target parameter in continuous processing, in prior art, by series reaction device, add the diamines of stoichiometric amount.In addition, use series reaction device to increase amount, cost of investment and the cost of energy of equipment.

Summary of the invention

In first embodiment, the present invention relates to a kind of method of controlling nylon salt solution continuous production, comprising: a) generate for setting the target feed speed of dicarboxylic acid powder and with generation, there is the model of the nylon salt solution of target pH value; B) by the dicarboxylic acid powder from weight-loss type feeder to feed pipe based on weight metering, and the variability of control dicarboxylic acid powder feed rate, described feed pipe enters single continuous stirred tank reactor by dicarboxylic acid powder with target feed rate transitions; C) diamines and water are introduced to single continuous stirred tank reactor with the first feeding rate and the second feeding rate respectively, wherein the first feeding rate and/or the second feeding rate are based on model; D) supplementary diamines charging is introduced in the recirculation loop of single continuous stirred tank reactor continuously with the 3rd feeding rate, wherein the 3rd feeding rate is based on model; E) use the variation that detects the pH value of nylon salt solution in the on-line pH value measurement that supplements the nylon salt solution in diamines introducing downstream; And f) adjust the variation that the 3rd feeding rate responds pH value, to produce, there is the pH value that departs from objectives and be less than ± 0.04 and the nylon salt solution of the pH value of variation.The method can further comprise produces the nylon salt solution with target salt concn, described target salt concn is selected from the scope of 50-65wt.%, and the method comprises the following steps: g) use the salt concn of measuring the nylon salt solution in recirculation loop at the one or more refractometers that supplement diamines introducing downstream; And h) regulate the second feeding rate, with based target salt concn, control the salt concn of nylon salt solution, wherein the salt concn of nylon salt solution depart from objectives salt concn be less than ± 0.5% and change.In certain aspects, the method can further comprise: the sample part that g) obtains nylon salt solution in the downstream that supplements diamines introducing; H) dilution cooling this sample part are to form the nylon salt solution of the dilution of the temperature with the concentration of 5-15% and 15-40 ℃; I) use the variation of pH value that detects the nylon salt solution of this dilution in the on-line pH value measurement that supplements diamines and introduce the nylon salt solution in downstream; And j) regulate the 3rd feeding rate to respond the variation of pH value of the nylon salt solution of dilution.In other respects, the method can further comprise: g) from the nylon salt solution supplementing diamines introducing downstream, shift out sample, for the nylon salt solution of the aqueous solution being carried out to off-line pH value at the temperature at 15-40 ℃, measure; H) determine the deviation that on-line pH value is measured and off-line pH value is measured; I) use the variation that detects the pH value of nylon salt solution in the on-line pH value measurement devious that supplements the nylon salt solution in diamines introducing downstream; And j) adjust the variation that the 3rd feeding rate responds pH value, to produce, there is the pH value that departs from objectives and be less than ± 0.04 and the nylon salt solution of the pH value of variation.Recirculation loop can comprise the pump of the group of selecting free vane pump, piston pump, flexible element pump, lobe pump, toothed gear pump, impeller pump, circumference piston pump and spiral pump composition, and supplementary diamines charging is introduced from the upstream of pump.Recirculation loop can comprise one or more on line analyzers, and for obtaining on-line pH value measuring result, and supplementary diamines charging is introduced in the upstream of these one or more on line analyzers.The 3rd feeding rate can be controlled by valve, and the middle-grade flow providing by the 20-60% of this valve is provided described valve.The diamines of introducing by the first feeding rate can form the 80-99% that feeds the total diamines in single continuous stirred tank reaction.The diamines of introducing by the 3rd feeding rate can form the 1-20% that feeds the total diamines in single continuous stirred tank reaction.Continuous stirred tank reactor can remain at the temperature of 60-110 ℃, and can under inert atmosphere, remain on normal pressure.Target pH value can be selected from the scope of 7.200-7.900.Described dicarboxylic acid can be hexanodioic acid, and described diamines can be hexamethylene-diamine, and wherein said nylon salt solution comprises hexamethylene-diamine adipate.Can be by the polymerization of described hexamethylene-diamine adipate to form nylon 6,6.

In second embodiment, the present invention relates to a kind of continuation method of producing nylon salt solution, comprise: a) based on weight, the dicarboxylic acid powder of metering from weight-loss type feeder to feed pipe, thereby the variability of controlling the feeding rate of dicarboxylic acid powder, described feed pipe enters dicarboxylic acid powder transfer in single continuous stirred tank reactor; And respectively diamines and water are introduced in single continuous stirred tank reactor with the first feeding rate and the second feeding rate, to produce the nylon salt solution with target pH value; B) supplementary diamines is constantly introduced in the recirculation loop of single continuous stirred tank reactor with the 3rd feeding rate, wherein this recirculation loop comprises the pump of the group of selecting free vane pump, piston pump, flexible element pump, lobe pump, toothed gear pump, impeller pump, circumference piston pump and spiral pump composition, and supplementary diamines charging is introduced from the upstream of pump; And c) nylon salt solution is taken out continuously from the recirculation loop of single continuous stirred tank reactor and directly in importing hold-up vessel, wherein this nylon salt solution has the salt concn of 50-65wt.%, pH value depart from objectives pH value be less than ± 0.04 and change.

Accompanying drawing explanation

Below by infinite accompanying drawing, the invention will be further described, wherein:

Fig. 1 is the production technique schematic diagram of the nylon salt solution of corresponding one embodiment of the invention;

Fig. 2 is the schematic diagram of weight-loss type feeder used in producing nylon salt solution of corresponding one embodiment of the invention;

Fig. 3 is the schematic diagram of single continuous stirred tank reactor used in producing nylon salt solution of corresponding one embodiment of the invention;

Fig. 4 is the sectional view of single continuous stirred tank reactor used in producing nylon salt solution of corresponding one embodiment of the invention;

Fig. 5 is the schematic diagram of the nylon salt solution producing process of corresponding one embodiment of the invention;

Fig. 6 is the schematic diagram of the Working Procedure Controlling for nylon salt solution producing process of corresponding one embodiment of the invention;

Fig. 7 is the schematic diagram of the Working Procedure Controlling with secondary control for nylon salt solution process of corresponding one embodiment of the invention;

Fig. 8 is the schematic diagram of the Working Procedure Controlling with three grades of controls for nylon salt solution process of corresponding one embodiment of the invention;

Fig. 9 is the schematic diagram of the Working Procedure Controlling measured of the on-line pH value of carrying out under laboratory condition for having of nylon salt solution process of corresponding one embodiment of the invention;

Figure 10 is the nylon-6 of corresponding one embodiment of the invention, the schematic diagram of 6 production technique;

Figure 11-13rd, the figure of the variability of the feeding rate of the hexanodioic acid from weight-loss type feeder of the corresponding one embodiment of the invention of demonstration.

Specific embodiment mode

Term used herein only, for the object of describing particular, is not intended to limit the present invention.Unless clearly shown other situation in context, singulative " " and " being somebody's turn to do " also comprise plural form as used herein.It should also be understood that, the term using in this manual " comprises " and/or has illustrated when " including " and have described feature, integral body, step, operation, parts and/or member, but do not hinder existence or the interpolation of one or more other features, integral body, step, operation, parts group, member and/or member group.

For example " comprise ", term and the variant thereof of " comprising ", " having ", " containing " or " relating to " should understand widely, and comprises listed main body and equivalent, also has unlisted other main body.In addition, when " being comprised " by transitional term, " comprising " or " containing " while drawing component, parts group, technique or method steps or any other statement, be to be understood that and also considered identical component, parts group, technique or method steps herein, or have transitional term before the record of this component, parts group, technique or method steps or any other statement " substantially by ... form ", " by ... form " or any other statement of " choosing freely ... the group of formation ".

If applicable words, the device of corresponding structure, material, action and all functions in claim or the equivalent of step comprise that the miscellaneous part for specifically stating with claim carries out any structure, material or the action of function in combination.Specification sheets of the present invention provides for the object of introducing and describing, but be not exhaustive or limit the invention to disclosed form.Do not departing under the prerequisite of scope and spirit of the present invention, many changes and variant are apparent for the person of ordinary skill of the art.Here select and described some embodiments, object is that principle of the present invention and practical application are carried out to best explanation, and other those of ordinary skill that make this area can be understood different embodiments of the present invention and have multiple variation, as being suitable for this specific end use.Correspondingly, although the present invention is described according to embodiment, yet those skilled in the art will recognize that, the present invention can change to some extent ground and implement within the spirit and scope of claims.

Now with detailed reference to specific disclosed theme.Although disclosed theme is described in connection with cited claim, however be appreciated that they not by disclosed subject matter restricted in these claims.On the contrary, disclosed theme has covered all replacement schemes, change and equivalent, within these can be contained in the scope of disclosed theme defined by the claims.

Foreword

The present invention relates to the continuation method for the production of nylon salt solution, comprise weight-loss type feeder and continuous stirred tank reactor, for example single continuous stirred tank reactor.By the metering of weight-loss type feeder, the feeding rate with low variability enters in single continuous stirred tank reactor with diamines dicarboxylic acid powder together with water.Diamines adds in single continuous stirred tank reactor with two portions, and described two portions are: as aqueous solution part and diamines feeding part as a supplement.Supplement diamines charging and add by pump, make it possible to obtain the mixing of improvement of nylon salt solution and supplementary diamines.The method is advantageously utilized and is supplemented the pH value that diamines charging is adjusted in the nylon salt solution in single continuous stirred tank reactor, to form the nylon salt solution of homogeneous.The method is improvements over the prior art, because the low variability of dicarboxylic acid powder makes the upstream that can measure in the pH of nylon salt solution value add supplementary diamines.Due to the mixing effect of pump to diamines and nylon salt solution, the transient measurement nearly that supplements diamines and make it possible to realize the effect of supplementing diamines charging by pump is added in the upstream of measuring in pH value.Therefore the method realizes the homogeneity of nylon salt solution and for existing method, has reduced equipment, energy cost and fund cost.

Be applicable to the optional free oxalic acid of dicarboxylic acid of the present invention, propanedioic acid, succsinic acid, pentanedioic acid, pimelic acid, hexanodioic acid, suberic acid, nonane diacid, sebacic acid, undecane diacid, dodecanedioic acid, toxilic acid, propene dicarboxylic acid, traumatic acid, muconic acid, 1, 2-or 1, 3-cyclohexyl dicarboxylic acid, 1, 2-or 1, 3-phenylene oxalic acid, 1, 2-or 1, 3-cyclohexyl oxalic acid, m-phthalic acid, terephthalic acid, 4, 4 '-phenyl ether dioctyl phthalate, 4, 4-benzophenone base dicarboxylic acid, 2, 6-naphthyl dicarboxylic acid, p-tert-butyl isophthalic acid, 2, the group that 5-furans dicarboxylic acid and composition thereof forms.In a specific embodiment, described dicarboxylic acid monomer comprises at least 80% hexanodioic acid, as at least 95% hexanodioic acid.

Hexanodioic acid (AA) is to prepare nylon-6,6 dicarboxylic acid that adapt to most, and its form with powder is used.Conventionally can obtain pure AA, the impurity that contains minute quantity.Typical impurity comprises other acids (monoprotic acid and lower diprotic acid), nitrogenous material, trace-metal (as iron (being less than 2ppm) and other heavy metals (be less than 10ppm or be less than 5ppm)), arsenic (being less than 3ppm) and the hydrocarbon ils (be less than 10ppm or be less than 5ppm) that is less than 60ppm.

Be applicable to diamines of the present invention and select free ethanol diamines, trimethylene diamines, putrescine, cadaverine, hexamethylene-diamine, 2-methyl-five methylene diamine, heptamethylene diamines, 2-methyl hexamethylene-diamine, 3-methyl hexamethylene-diamine, 2, 2-dimethyl five methylene diamine, eight methylene diamine, 2, 5-dimethyl hexamethylene-diamine, nine methylene diamine, 2, 2, 4-and 2, 4, 4-trimethylammonium-hexamethylene-diamine, decamethylene diamine, 5-methylnonane diamines, isophorone diamine, 11 methylene diamine, ten dimethylene diamines, 2, 2, 7, 7-tetramethyl--eight methylene diamine, two (p-aminocyclohexyl) methane, two (aminomethyl) norbornane, optionally by one or more C ₁-C ₄the C that alkyl replaces ₂-C ₁₆aliphatie diamine, aliphatic poly ether diamine and furans diamines, (aminomethyl) furans as two in 2,5-, and composition thereof.The boiling point of selected diamines can be higher than dicarboxylic acid, and described diamines is not preferably xylyene diamine.In a specific embodiment, described diamine monomer comprises at least 80% hexamethylene-diamine, as at least 95% hexamethylene-diamine.Hexamethylene-diamine (HMD) is most commonly used to prepare nylon-6,6.HMD solidifies at about 40-42 ℃, conventionally adds water to reduce its temperature of fusion, and it is easily processed.Therefore, the HMD of strong solution form, as concentration, being 80～100wt.% or 92～98wt.%, diamines is that business is available.

Except the independent polymeric amide based on dicarboxylic acid and diamines, add other monomers sometimes to have superiority.When the ratio of adding is lower than 20wt.%, when lower than 15wt.%, also these monomers can be joined in nylon salt solution under the premise of not departing from the present invention.This type of monomer can comprise monofunctional carboxylic acids, as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, phenylformic acid, caproic acid, enanthic acid, sad, n-nonanoic acid, capric acid, undecanoic acid, dodecylic acid, tetradecanoic acid, tetradecenoic acid, palmitinic acid, Zoomeric acid, hexadecylenic acid (sapienic acid), stearic acid, oleic acid, elaidic acid, octadecenoic acid, linolic acid and erucic acid etc.This type of monomer also can comprise lactams, as α-beta-lactam, α-azetidinone, azetidinone, butyrolactam, δ-Valerolactim, γ-Valerolactim and hexanolactam etc.This type of monomer also comprises lactone, as α-second lactone, α-propiolactone, beta-propiolactone, gamma-butyrolactone, δ-valerolactone, γ-valerolactone and caprolactone etc.This type of monomer also can comprise the alcohols of two functional groups, as mono-vinyl ethylene glycol, DIETHYLENE GLYCOL, 1,2-PD, 1, ammediol, diallyl ethylene glycol, 1,2-butyleneglycol, 1,3 butylene glycol, 1,4-butyleneglycol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, ethohexadiol (etohexadiol), p-menthane-3,8-glycol, 2-methyl-2,4-pentanediol, 1,6-hexylene glycol, 1,7-heptanediol and 1,8-ethohexadiol.Also can use high functionality molecule, as glycerine, TriMethylolPropane(TMP) and Triethanolamine 99(TEA 99) etc.Suitable oxyamine also can be selected such as thanomin, diethanolamine, 3-amino-1-propyl alcohol, 1-amino-2-propyl alcohol, 4-amino-n-butyl alcohol, 3-amino-n-butyl alcohol, 2-amino-n-butyl alcohol, 4-amino-2-butanols, amylalcohol amine and hexanol amine etc.Be understandable that, under the prerequisite not departing from the scope of the present invention, also can adopt the mixture of monomer described in any one.

To introducing other additives in polymerization technique, be also favourable sometimes.These additives can comprise thermo-stabilizer, as mantoquita, potassiumiodide or any other antioxidant well known in the prior art.Examples of such additives also can comprise polymerizing catalyst, as metal oxide, acidic cpd, containing metal-salt or other compounds well known in the prior art of oxygen phosphorous compound.Examples of such additives also can be matting agent and tinting material, as titanium dioxide, carbon black or other pigment, dyestuff and tinting material well known in the prior art.Additive used also can comprise defoamer, as silica dispersions, silicone copolymers or other defoamers well known in the prior art.Also can use lubricating auxiliary agent, as Zinic stearas, stearyl erucicamide, stearyl alcohol, aluminium distearate, vinyl bis-stearamides or other polymeric lubricants well known in the prior art.In mixture, also can comprise nucleator, as pyrogenic silica or aluminum oxide, molybdenumdisulphide, talcum powder, graphite, Calcium Fluoride (Fluorspan), phenyl-phosphonite salt or other auxiliary agents well known in the prior art.Also can in polymerization technique, add other known typical additives of prior art, as the filler of fire retardant, softening agent, impact modifier and other types.

In the following description book, term hexanodioic acid (AA) and hexamethylene-diamine (HMD) are for representing dicarboxylic acid and diamines.Yet this method is also for above-mentioned other dicarboxylic acid of mentioning and other diamines.

The present invention obtains comprising the nylon salt solution of the AA/HMD salt with target pH value easily.Especially, the present invention uses the container fewer than traditional technology number to obtain target pH value, especially at single reactor, obtain target pH value in forming therein the single continuous stirred tank reactor (CSTR) (CSTR) of nylon salt solution.In continuous processing, advantageously adopt single reactor, can access the productivity higher than batch technology.In batch technology, for obtaining time quantum and the equipment investment cost required with the obtainable similar productivity of continuous processing, make batch technology unrealistic.Described target pH value can be any pH value that those skilled in the art selects, and can select according to required final polymeric articles.Be not subject to theoretical constraint, target can be selected from the highest flex point of pH curve, and it is best level for the scope of polymeric articles for expection.

In some exemplary embodiments, the target pH value of nylon salt solution can be the value between 7.200～7.900, preferably the value between 7.400～7.700.The variation of the target pH value of the actual pH of nylon salt solution and nylon salt solution can be lower than ± 0.04, more preferably less than ± 0.03, most preferably lower than ± 0.015.Thereby as when target pH value is 7.500, the pH value of nylon salt solution is between 7.460～7.540, more preferably between 7.470～7.530 so.So, for example, when target salt concn is 60%, the variability of the salt concn of nylon salt solution is between 59.5%-60.5% so uniformly, more preferably between 59.9%～60.1%.In order to realize object of the present invention, the variability of pH value refers to the variation of mean rate in operate continuously.This variability is very little, lower than ± 0.53%, more preferably less than ± 0.4%, obtains having the nylon salt solution of homogeneous pH value.The uniform nylon salt solution that has low variability and depart from objectives pH value is conducive to improve a reliability for polymerization technique, uniform to produce, high-quality polymeric articles.The nylon salt solution with homogeneous pH value also makes it possible to stabilised quality ground charging in polymerization technique.Described target pH value can change according to production site.Generally, based on free and chemically combined AA and HMD, 7.620 the pH value of measuring under 25 ℃ and 9.5% salt concn, it is 1 nylon salt solution that generation has AA/HMD mol ratio.In order to realize object of the present invention, mol ratio can change according to target pH value in the scope of 0.8:1.2.The pH value with homogeneous also means that the mol ratio of nylon salt solution has corresponding low variability.

Except target pH value, the present invention also can reach target salt concn.Target salt concn can be the salt concn arbitrarily that those skilled in the art select, and can select according to required final polymeric articles and the consideration of storage.The water-content of nylon salt solution can be between 35-50wt.%.The salt concn of nylon salt solution can be 50～65wt.%, as 60～65wt.%.Nylon salt solution can be lower than 110 ℃, as 60～110 ℃ or the 100-105 ℃ form with liquid under normal pressure is preserved.Concentration higher than 65wt.% needs higher temperature and may need pressurization to make nylon salt solution remain liquid, as homogeneous liquid.Salt concn can affect storing temp, conventionally under lower temperature and normal pressure, can effectively store nylon salt solution.Yet lower salt concn can adversely be increased in the energy expenditure of the front concentrated nylon salt solution of polymerization.

When producing continuously nylon salt solution according to the present invention, the salt concn variability of nylon salt solution is preferably very low, as the salt concn that departs from objectives is lower than ± 0.5%, lower than ± 0.3%, lower than ± 0.2% or lower than ± 0.1%.In order to realize object of the present invention, the variability of salt concn refers to the variation of mean rate in operate continuously.Target salt concn can change according to production site.

The temperature of nylon salt solution is independent of the mol ratio of AA and HMD and controls.Although the mol ratio in nylon salt solution and solids concn affect the temperature of nylon salt solution, technique relies on heat exchanger, coil pipe and/or jacketed type CSTR from technique, to remove heat, thereby controls the concentration of nylon salt solution.The temperature of nylon salt solution can be controlled at and depart from interior variation of the temperature required scope lower than ± 1 ℃.The temperature of nylon salt solution can be chosen in to the boiling point lower than nylon salt solution, but higher than the Tc of nylon salt solution.For example, the boiling point of the nylon salt solution that solid content is 63% under normal pressure is 108-110 ℃.Therefore, temperature is controlled at lower than 110 ℃, as lower than 108 ℃, but higher than Tc.

In order to realize the low variability of nylon salt, existing technical scheme concentrates on uses a plurality of reactors to adjust AA:HMD mol ratio in salts solutions and the concentration of HMD.This small part that is concentrated to is variability and the poor flow characteristics due to the volume density of AA powder, has caused the intrinsic unpredictability of AA powder feed.When using volumetric feeder that AA powder is fed to reactor, the variability of the volume density of AA powder is exaggerated.Due to the high melt temperature of AA, so AA supplies with the form of powder conventionally, thereby increased the difficulty of processing AA.The median size of AA powder, conventionally at 75～500 microns, changes in 100～300 microns.This fine powder has in fact larger surface-area and more causes the particle of assembling to contact.Preferably, in AA powder, contain be less than 20%, as being less than 10% the particle of 75 microns of being less than.Because the AA powder volume that the form based on powder directly enters in reactor conventionally measures, thereby the variable effect of powder size feeds bulk packages and the density of the AA powder in nylon salt reactor.The variation of these bulk packages and density and then cause nylon salt pH value in solution and the variation of AA and HMD mol ratio.Consider that these change, and are provided with a series of salt reactor in prior art scheme.For example, referring to US2012/0046439 and US2010/0168375.This traditional method has been used the mensuration of target component, and monomer is fed in series reaction device.Yet this technique needs a large amount of reactor, measurement and adjustment, thereby increase cost and limited productivity.In addition, compare with continuous processing, this traditional method may be more suitable for batch technology.Finally, this traditional method can not use a model to predict pH value and/or salt concn, thereby need to constantly adjust so that nylon salt solution reaches target component.

In the prior art of adding AA and HMD with a plurality of reactors, stated and AA powder fed to the relevant particle size of nylon salt technique and the effect of distribution of sizes.It is found that, during based on weight rather than based on volume metering AA powder, the variability of AA feeding rate can reduce greatly.In certain aspects, the feeding rate of the AA powder AA powder feed rate that can depart from objectives changes lower than ± 5%, as lower than ± 3% or ± 1%.By this stable charging, disclosed technique allows to use single reactor to have the nylon salt solution of target component to form, and does not need a plurality of reactors of series connection.There is no the stable charging of AA, utilize the single reactor operate under high continuous productivity to be difficult to control the depart from objectives variation of pH value and target salt concn of nylon salt solution, this is limited in one's ability due to adjustment monomer.There is stable AA charging and make technology controlling and process can utilize the feed forward rate of HMD, and make to adjust and supplement HMD and adjust pH value, to reach target pH value.Advantageously, desired embodiment provides a kind of more disclosed more simply design than in the past by reducing the number of the unit operation in technique.Therefore, the technique of the disclosure has been omitted and has been thought indispensable step in the past.It has reduced floor space and cost of investment.The further polymerization of nylon salt solution obtaining can be obtained to required polymeric amide.

In the suitability for industrialized production of nylon salt solution, for realizing acceptable production, can adopt continuous processing to produce nylon salt solution.Gap technique needs obviously larger container and reactor.Further, batch technology is difficult to pass more small-sized continuous producing apparatus with regard to obtainable productivity.In polymerization, originate in and there is the pH value of homogeneous and the nylon salt solution of salt concn is useful.Small variation can cause the product quality problems of polymerization, thereby needs extra monitoring control and the adjustment of polymerization technique.

Fig. 1 provides according to the technique general line of the production nylon salt solution of embodiment of the present invention.As shown in Figure 1, nylon salt solution process 100 comprises: hexanodioic acid is fed to weight-loss type feeder 110 by pipeline 102, and it produces the hexanodioic acid charging 139 after the metering of introducing in continuous stirred tank reactor 140.In addition, the water by pipeline 103 and the HMD by pipeline 104 are mixed to get the aqueous solution of HMD in static mixer 105, and it feeds in continuous stirred tank reactors 140 by pipeline 106.Liquid containing nylon salt solution is withdrawn from from reactor 140 by recirculation loop 141, is then back to reactor 140.Be referred to herein as the extra HMD that supplements HMD, can be by pipeline 107 pH value with adjusting nylon salt in tie point 142 joins liquid before analyzing pH value or salt concn.Nylon salt solution is withdrawn from and is entered pipeline 144 at tie point 143 from recirculation loop 141.Nylon salt solution stream in pipeline 144, is then collected in hold-up vessel 195 to remove impurity through filter 190.Generally, these impurity can comprise corroding metal, and can comprise the impurity from monomer feed, as AA powder 102.Described nylon salt solution can move into polymerization process 200 by pipeline 199.Described nylon salt solution can be kept in hold-up vessel 195 until polymerization needs.In some embodiments, hold-up vessel 195 is movably.

nylon saline solution means

aA powder material feeder based on weight

In a specific embodiments, as shown in Figure 2, utilize weight-loss type feeder 110 that AA powder 102 is fed in continuous stirred tank reactor 140.Weight-loss type feeder 110 metering AA powder 102 are to produce the AA powder feed stream 139 with low variability feeding rate, and it can consider the variation of the density of AA powder 102 in fill process.As mentioned above, volume density and the flow characteristics of AA powder 102 alter a great deal, thereby cause introducing the imbalance of mol ratio, and the inhomogenous pH value that produces nylon salt solution.For can not realizing the feeder of determining volume feeder or other types of feeding rate of low variability of AA powder, the present invention has advantage.For realizing object of the present invention, the feeding rate of the low variability of AA powder is in the scope of target feed speed ± 5% of AA powder, as in ± 3% scope, in ± 2% scope or in ± 1% scope.In order to realize object of the present invention, the variability of feeding rate refers to the variation of mean rate in operate continuously.Due to the low variability of AA feeding rate, the feeding rate of AA is stable and measurable, therefore can use single reactor, by customizing the feeding rate of diamines and water, obtains target pH value and/or target salt concn.Due to the depart from objectives low variability of feeding rate of AA powder feed rate, do not need other reactor for mixing or adjusting.

Conventionally, weight-loss type feeder 110 adds goods charging bucket 111 in supplemental stages, and at the material of charging stage distribution hopper 111.Preferably, this supplement-charging stage circulation is enough at least 50% time, as at least 67% time is received the feedback signal from weight-loss type feeder 110.In a specific embodiments, supplemental stages accounts for the amount of total cycle time (as charging stage and supplementary total time) can be lower than 20%, as lower than total cycle time 10% or lower than 5% of total cycle time.The time of supplemental stages and total cycle stage can be depending on throughput rate.In the charging stage, the material in hopper 111 is distributed to feed pipe 112, its by pipeline 139 by AA powder transfer in continuous stirred tank reactor 140.In addition, in supplemental stages, the AA remaining in hopper 111 also can be assigned to feed pipe 112, and feed pipe 112 obtains the continuous supply of AA powder thus.Controller 113 can be used for management and control weight-loss type feeder 110.Controller 113 can be can output function dcs (DCS) or the programmable logic controller (PLC) of the input message received of response.In a specific embodiment, can there be a plurality of controllers for the different assemblies of system.For example, PLC can be used for management and control supplemental stages, and the targeted rate that DCS can be used for by being set in DCS is controlled by the feeding rate of feed pipe 112.

As shown in Figure 2, delivery system 114 packs AA powder 102 in supply storehouse 115 into.Delivery system 114 can be machinery or pneumatic conveyor system, and hexanodioic acid is shifted out from loose bags, lining bulk bag, lining box container or hopper rail car depot.Mechanical conveying system can comprise spiral or haulage chain.Pneumatic conveyor system can comprise the pipeline of sealing, utilizes the nitrogen of forced air, evacuated air or loop line that AA powder 102 is delivered to supply storehouse 115.In some embodiments, delivery system 114 can provide mechanical function to destroy the block of AA powder in the process that loads supply storehouse 115.Supply storehouse 115 can have moulding cylindric, trapezoidal, square or that other are suitable, at its top, has entrance 116.The moulding having with the limit at angle can help AA powder 102 to flow out from supply storehouse 115.The top edge in supply storehouse 115 can be positioned at system ground elevation 130 above lower than 20 meters of, as preferably lower than 15m.System ground elevation 130 refers to the plane of the different device stop of producing nylon salt solution, and conventionally defines the plane that does not have monomer to pass through.System ground elevation can be on the entrance of CSTR.Because supply storehouse 115 is lower with respect to the height of system ground elevation 130, need less energy to drive delivery system 114 and load supply storehouse 115.

Supply storehouse 115 also has lower valve 117, when lower valve 117 is closed, just defines the internal cavity of preserving AA powder 102.Lower valve 117 can be rotary feeder, feeding screw, rotational flow device or the clustered aggregates that contains feeder and valve.When filling described internal cavity with AA powder 102, lower valve 117 keeps closing condition.When supplemental stages, lower valve 117 can be opened, and based on volume, AA powder 102 is sent to hopper 111.When lower valve is sent to hopper 111 by AA powder, AA powder can be loaded into supply storehouse 115.Lower valve 117 can comprise one or more rim strips that form sealing when closing.In one embodiment, AA powder 102 can be sent to hopper 111 from supply storehouse 115 by travelling belt (not shown).In other embodiments, AA powder can be transmitted by gravity in supply storehouse 115.The loading in supply storehouse 115 can be independent of the loading of hopper 111.

The capacity in supply storehouse 115 can be greater than hopper 111, preferred described capacity be at least 2 times of hopper 111 or at least 3 times large.The capacity in supply storehouse 115 should be enough to supplement the whole volume of hopper 111.AA powder 102 comparablely will be grown in the time cycle of supply storehouse 115 interior preservations in hopper 111, and depended on moisture concentration, and AA powder 102 can form agglomerate.In the bottom in supply storehouse 115, can use mechanical rotor or vibration (not shown) that agglomerate is broken.

The upper limb of hopper 111 can be positioned at system ground elevation 130 tops lower than 15m place, as preferably lower than 12m place.Hopper 111 can have round shape, the moulding that trapezoidal, square or other are suitable, and has entrance 118 at its top.Preferably, the internal surface of hopper for tilt to prevent the bridging of AA powder.In a specific embodiment, the angle of internal surface is 30-80 °, as 40-65 °.Described internal surface can be U-type or V-type.Hopper 111 also can have movably lid (not shown), has the hole for entrance 118 and ventilation opening on lid.Hopper 111 can be arranged on pipe 119, and it couples together hopper 111 and feed pipe 112.In a specific embodiment, hopper 111 has the equivalent volume that can maintain required throughput rate.For example, hopper 111 can have the capacity of at least 4 tons.The maximum diameter of pipe 119 is less than the maximum diameter of hopper 111.As shown, pipe 119 has rotary feeder 120 or similar transport unit, for the material in hopper 111 is distributed to feed pipe 112 by exporting 129.Rotary feeder 120 can turn round opening or closing under pattern, or speed of rotation can be controlled as the function of required feeding rate.In other embodiment, pipe 119Ke Buhan internally feeding mechanism.The type that depends on weight-loss type feeder, available outside push-and-pull oar or the vibrator that the effluent of hopper 111 can be dispensed to feed pipe 112 replaces rotary type feeder 120.Outlet 129 can have mechanical means and break AA agglomerate.In another embodiment, weight-loss type feeder 110 can clean (not shown) containing moisture eliminator or dry gas, to remove the moisture in AA powder, prevents the coalescent and formation obstruction in hopper 111 of AA powder.

Weight measurement subsystem 121 is connected with hopper 111.Weight measurement subsystem 121 can contain a plurality of sensors 122, described sensor 122 ponderable quantity hoppers 111, and the signal that shows weight is offered to controller 113.In some embodiments, can there be three or four sensors.Sensor 122 can be connected with the outside of hopper 111, and can weigh tare weight with explanation hopper 111 and the initial weight that is connected to any other equipment on hopper 111.In other embodiment, sensor 122 can be arranged on hopper 111 below.According to the signal from weight measurement subsystem 121, controller 113 is controlled supplemental stages and charging stage.The weight that controller 113 more regularly measures, to determine the weight of the AA powder 102 of distributing to feed pipe 112 within for some time.Controller 113 can also be controlled the speed of rotating screw thruster 123, described in below.

In other embodiment, weight measurement subsystem 121 can be arranged under hopper 111, pipe 119 and feed pipe 112, to measure the weight of the material in these positions of weight-loss type feeder 110.

Feed pipe 112 can be positioned at pipe 119 tops, and receives AA powder 102.In one embodiment, feed pipe 112 can be installed on pipe 119.Feed pipe 112 may extend to the plane that is basically perpendicular to pipe 119 outlet 129, or extends to described plane and be 0-45 °, as 5-40 ° of angle, and orientating reaction device 140.Feed pipe 112 is containing at least one rotating screw thruster 123, and described rotating screw thruster 123 is delivered to AA powder 102 in reactor 140 by open outlet 124.Rotating screw thruster 123 is driven by engine 125, and can comprise screw rod.Also can use the configuration of twin screw.Engine 125 is to fix or variable speed driving rotating screw thruster 123.In one embodiment, feed pipe 112 is sent to reactor 140 by AA powder 102 with the feeding rate of low variability.The feeding rate of AA can regulate according to required throughput rate.So just allow to set up fixing AA feeding rate and use model described herein, then changing the feeding rate of other solution components to obtain required salt concn and/or pH target value.Controller 113 receives the feedback signal from weight-loss type feeder 110, and adjusts the speed of rotating screw thruster 123.Controller 113 is also adjusted the feeding rate of feed pipe 112 according to the signal from weight measurement subsystem 113.The command signal that gives rotating screw thruster 123 affects the speed of engine, increases, maintains or the speed that the reduces engine weight loss to obtain setting.

In other embodiment, feeding line 112 as herein described can be any that be equal to, controlled feeder type, as belt feeding machine, feeder compartment, apron feeder, oscillating feeder etc.Feed pipe 112 also can comprise vibroshock (not shown).In addition, feeding line 112 can contain one or more gas port (not shown), for nitrogen injection to remove oxygen.

Hopper 111 also can contain high-order probe 127 and low level probe 128.Should be understood that, although for simplicity, only show a high-order probe and a low level probe, can have a plurality of probes.Described probe can be combined with weight measurement subsystem 121.In order to realize the present invention, described probe can be some position telltale or a capacitive proximity sensor.The position of high-order probe 127 and low level probe 128 can be in the interior adjusting of hopper 111.High-order probe 127 is positioned in the top that approaches hopper 111.When the material in hopper 111 detects by high-order probe 127, finish supplemental stages, and start the charging stage.Otherwise low level probe 128 is positioned at and is positioned under high-order probe 127, and more approach the bottom of hopper 111.Low level probe 128 can make to possess in supplemental stages enough residual contentes of the AA powder 102 being assigned with.When low level probe 128 detects while there is no material in its position in hopper 111, supplemental stages starts.As mentioned above, in supplemental stages, charging can continue.

AA solid is corrosive.Weight-loss type feeder 110 can by the 304a corrosion resistant material as austenitic stainless steel or as 304,304L, 316 and 316L or other can provide the material structure of the suitable erosion resistance of the economically feasible sexual balance between equipment life and cost of investment to form.In addition, corrosion resistant material can prevent the corrosion contamination of product.Other corrosion resistant material are preferably compared with carbon steel, and the attack of AA is had to higher resistivity.High density, carbon steel is not had to corrodibility as the HMD higher than 65%, so carbon steel can be used for storing dense HMD, and stainless steel can be used for storing compared with the HMD of dilute concentration.

Although only show an exemplary weight-loss type feeder 110, other acceptable weight-loss type feeders can comprise Acrison Models402/404,403,405,406 and 407; Merrick Model570; K-Tron Models KT20, T35, T60, T80, S60, S100 and S500; And BrabenderFlexWall ^tMplus and FlexWall ^tMclassic.Acceptable weight-loss type feeder 110 must be able to reach the feeding rate that is enough to continuous business running.For example, feeding rate can be at least 500Kg/hr, as 1000Kg/hr at least, and at least 5,000Kg/hr or at least 10,000Kg/hr.Also can use higher feeding rate in embodiments of the invention.

reactor

In one embodiment, the present invention comprises the reactor for the production of nylon salt solution, described reactor comprises the continuous stirred tank reactor of producing nylon salt solution, described continuous stirred tank reactor comprises: for dicarboxylic acid powder being introduced to the first entrance of continuous stirred tank reactor, for the first diamines charging being introduced to the second entrance of continuous stirred tank reactor, wherein the second entrance is adjacent with the first entrance; Be arranged at the one or more baffle plates on the inwall of continuous stirred tank reactor (CSTR); Extend to the stir shaft at the center of continuous stirred tank reactor (CSTR), wherein stir shaft comprises at least one top impeller and at least one bottom impeller; And comprise for introduce the recirculation loop of the binding site of the second diamines charging in the upstream of pump and sample loop; And for nylon salt solution is directly transferred to the pipeline of hold-up vessel from the recirculation loop of continuous stirred tank, wherein said pipeline does not select free dicarboxylic acid, diamines and its entrance in conjunction with other monomers of the group forming containing any for introducing, thereby prevent other monomer transfer to this pipeline or enter hold-up vessel, wherein said reactor comprises single reactor.

As shown in Figure 3, nylon salt solution is prepared in single continuous stirred tank reactor (CSTR) 140.Reactor 140 produces enough turbulent flows to produce the nylon salt solution of homogeneous phase.In order to realize the present invention, " continuous stirred tank reactor (CSTR) " relates to a reactor, do not comprise a plurality of reactors.The present invention can obtain uniform nylon salt solution in single container, does not need a plurality of vessel cascade as used in traditional technology.Applicable continuous stirred tank reactor is single container reactor, as the reactor of non-series connection.Advantageously, this can reduce the capital contribution of producing nylon salt solution on commercial size.When being used in conjunction with weight-loss type feeder described herein, continuous stirred tank reactor can access the even nylon salt solution that reaches target pH value and target salt concn.

From reactor 140, take out nylon salt solution and be directly transferred to hold-up vessel 195.During nylon salt solution is fetched into from continuous stirred tank reactor 140 enters hold-up vessel 195, there is no the introducing of follow-up monomer A A or HMD.More particularly, nylon salt solution is withdrawn from from recirculation loop 141 by pipeline 144, and does not have monomer to add in pipeline 144.On the one hand, pipeline 144 is not for introducing the entrance of additional monomers, and described additional monomers can comprise dicarboxylic acid and/or diamines.Therefore, the pH value of nylon salt solution does not need further by introduce extra monomer in pipeline, to regulate, especially without adding extra HMD to regulate.As required, nylon salt solution can be carried out to extra mixing and filtration, but just as described in this article, monomer only need be supplied with single continuous stirred tank reactor.Therefore the technique of the disclosure avoids needing the sequence of a plurality of containers and pH value is in succession measured and the step of adjustment, and it is required that it is considered to the AA and the stable stoichiometric balance between HMD that maintain for the manufacture of nylon 6,6 before.

Reactor 140 has between 1.5-6, as the aspect ratio between 2-5.Reactor 140 can by select free Hastelloy carbon, aluminum oxide and as 304,304L, 316 and the austenitic stainless steel of 316L and other can between equipment life and cost of investment, provide the material structure of the group that the suitable corrosion resistant material of economically feasible sexual balance forms to form.The selection of material can be undertaken by the temperature in consideration continuous stirred tank reactor 140.The residence time in continuous stirred tank reactor 140 changes according to size and feeding rate, and it is less than 45min conventionally, as is less than 25min.Liquid is withdrawn from and is entered recirculation loop 141 at outlet at bottom 148, and nylon salt solution is withdrawn from pipeline 144.

Conventionally, suitable continuous stirred tank reactor comprises that at least one is for introducing the monomer entrance of AA, HMD and/or water.Described entrance points to the top of reactor.In some embodiments, monomer splashes in liquid.In other embodiments, dip-tube is used in and in liquid level, supplies with monomer.Can exist for introducing a plurality of entrances of each component of reaction medium.Exemplary continuous stirred tank reactor as shown in Figure 3.As shown in Figure 3, it has AA entrance 145 and HMD entrance 146.Diamines can or comprise 20-55wt.% with pure HMD, as the HMD of 30-45wt.% and 45-80wt.%, as the form of the aqueous solution 106 of the water of 55-70wt.%, introduce.The aqueous solution 106 can be introduced by entrance 146, and described entrance 146 is adjacent with the entrance 145 of dicarboxylic acid powder 139.In a specific embodiment, entrance 146 can be 0.3-1m from entrance 145.The aqueous solution 106 contributes to dissolve, and can dissolve at least partly the dicarboxylic acid powder 139 feeding in reactor 140.Water can be introduced together with diamines.Optionally, can be useful on the entrance 147 that is introduced separately into water.Water also can be introduced by reactor recovery tower 131.In certain aspects, recovery tower 131 is vent condenser.

Liquid in reactor 140 can be withdrawn from and continuously by recirculation loop 141.Recirculation loop 141 can comprise one or more pumps 149.In recirculation loop 141, also can comprise temperature-control device, as coil pipe, chuck or containing device, temperature measuring apparatus and the controller of heat exchanger.Temperature-control device can be controlled the temperature of the nylon salt solution in recirculation loop 141, thereby prevents boiling or the oar of nylon salt solution.As extra HMD, when supplemented HMD and introduce by pipeline 107, preferably at the tie point 142 of one or more pumps 149 upstreams and at the upstream of any pH value or salt concn analyser introducing HMD.As what further describe herein, supplementing can be containing the 1-20% that forms the required HMD of nylon salt solution, as the 1-10% of required HMD in HMD107.Tie point 142 can be the opening for feed of recirculation loop 141.Except making liquid recirculation, pump 149 also can play the effect of secondary mixer.Pump can be used for being incorporated into recirculation loop 141 and will supplementing HMD and the liquid mixing of taking out from reactor supplementing HMD.The group that the optional free vane pump of described pump, piston pump, flexible element pump, lobe pump, toothed gear pump, circumference piston pump and spiral pump form.In some embodiments, pump 149 is arranged on tie point 142 places.In other embodiments, as shown, pump 149 is arranged on the downstream of tie point 142, but before being positioned at tie point 143.Preferably secondary mixes to occur in and adds the supplementary HMD comprising by pipeline 107 after interior all HMD, and before any analysis or taking-up enter hold-up vessel 195.In optional embodiment, one or more static mixer (not shown) can be arranged in the recirculation loop 141 in downstream of pump 149.Exemplary static mixer is at Perry, Robert H., and Don W.Green.Perry's Chemical Engineers'Handbook.7th ed.New York:McGraw-Hill, further describes in 1997:18-25to18-34, and its mode is by reference incorporated into herein.

At tie point 143, nylon salt solution is withdrawn from pipeline 144.The residence time in pipeline 144 can change according to the position of hold-up vessel 195 and strainer 190, is usually less than 600 seconds, as lower than 400 seconds.In one embodiment, valve 150 is for controlling the pressure of nylon salt solution.Although only show a valve, be construed as in recirculation loop 141 and can use extra valve.In the downstream of tie point 143, do not have monomer to introduce as AA or HMD, or do not have monomer to join in pipeline 144 as AA or HMD.In addition, under normal operational condition, do not have monomer to be incorporated in hold-up vessel 195.

Recirculation loop 141 also can comprise for regulating the heat exchanger 151 of the fluid temperature of reactor 140.The temperature regulator (not shown) that temperature can be positioned at reactor 140 or continuous stirred tank reactor 140 outlet (not shown) by use regulates.The temperature of liquid can be utilized inner heat exchanger, as coil pipe or jacketed reactor (not shown) regulate.Can heat exchanger 151 water coolants of supplying with more than the zero pour of the salt that maintains given concentration.In one embodiment, heat exchanger can be indirectly shell-and-tube exchanger, volution or plate and frame heat exchanger, or for carrying out the reboiler of the recovery heat of autoreactor 140.Temperature in reactor 140 maintains in the scope of 60-110 ℃, in case grouting liquid forms and crystallization formation.When water-content increases, maintain the required temperature of solution and decline.In addition, the temperature in reactor 140 maintains low temperature to prevent the oxidation of HMD.Also can provide nitrogen blanket to prevent the oxidation of HMD.

As shown in Figure 3, in a specific embodiment, reactor 140 has inner coil pipe 152, to described inner coil pipe 152, feeds refrigerant to regulate the temperature of reactor in the scope of 60-110 ℃.In another specific embodiment, reactor 140 also can have the chuck (not shown) with refrigerant.Inner coil pipe also can react the heat producing by recovery and regulate temperature.

Except temperature regulator, reactor 140 also can have atmospheric steam exhaust mouth with vent condenser to maintain the barometric point in reactor 140.Pressure controller can contain inside and/or outside pressure transmitter.

In a specific embodiment, also can there is sample line 153, for measuring pH value and/or the salt concn of nylon salt.Sample line 153 can exist liquid to exchange with recirculation loop 141, and preferably therefrom receives fix mobile the impact of analyser is minimized by flowing.On the one hand, sample line 153 can withdraw from be less than 1%, the nylon salt solution that is arranged in recirculation loop 141 more preferably less than 0.5%.At sample line 153, can there be one or more analysers 154.In some embodiments, sample line 153 can comprise strainer (not shown).In another embodiment, sample line 153 can comprise suitable heating or refrigerating unit, if heat exchanger is to adjust and the temperature of Quality control stream.Similarly, sample line 153 can comprise for adding water to regulate the water charge line (not shown) of concentration to sample stream.If add water in sample stream, water can be deionized water.The water that calculating provides by sample line 153 to be to maintain target salt concn, and other water charging of capable of regulating.Analyser 154 can comprise the on line analyzer of measuring in real time.According to the type of sampling, the part of testing can be back in reactor 140 or be emitted by pipeline 155.Sample line 153 can return by recirculation loop 141.Alternatively, sample line 153 can be back in independent position reactor 140.

Continuous stirred tank reactor 140 keeps at least 50% completely, as at least 60% full liquid level.Select described liquid level to make the oar that nylon salt solution can submergence CSTR, thereby prevent that nylon salt solution from forming foam.Nitrogen or other rare gas elementes can be incorporated into liquid level 156 superjacent air spaces by pore 157.

The inside of continuous stirred tank reactor 140 can provide enough mixing to obtain having the nylon salt solution of homogeneous pH value.As shown in Figure 4, there is the stir shaft 159 that extends perpendicularly to reactor 140 and pass reactor 140 center.Preferably, stir shaft 158 extends along the medullary ray of reactor 140, but in certain embodiments, stir shaft 158 can pass center.In optional embodiment, stir shaft can be for tilting.As long as can cross the stirring that reaches required, also can use eccentric stir shaft.

Stir shaft 158 can contain one or more impellers 159, as stirring rake, hurricane band, anchor, spiral, water screw and/or turbine type.Preferably axial-flow impeller is used for mixing AA and HMD, and this is because this class impeller trend prevents that solid particulate is in the sedimentation of the bottom of reactor 140.In some other embodiment, impeller can be flat oar radial turbine, and it has the several equidistant blade around disk.At whole stir shaft 158, can contain 2-10 impeller, as 2-4 impeller.Blade 160 on impeller 159 can be for straight, curved formula, recessed formula, protruding formula, angled or oblique.The number of blade 160 changes between can be at 2-20, as 2-10.If necessary, blade 160 also can have static organ (not shown) or scraper (not shown).

As shown in Figure 4, it has shown three inclination turbine assemblings 161.Oblique leaf turbine 162 and the oblique leaf turbine 163 at least one bottom that stir shaft 158 comprises at least one top.In three inclination turbine assemblings 161, preferably setover mutually in the inclined-plane 164 ' of the oblique leaf turbine 163 in 164Yu bottom, inclined-plane of the oblique leaf turbine 162 in top.

Also can use the multiple stir shaft with dissimilar impeller, as helical stir axle and anchor formula stir shaft.Can also use side mounted stir shaft, especially ship propeller.

Be back to Fig. 3, stir shaft 158 is driven by outer 165, and it can be at 50-500rpm, as the speed mixing liquid of 50-300rpm.Stir shaft 158 is removably mounted on engine driven axle 166 at junctor 167 places.The speed of motion is variable, but generally, the whole surface-area that described speed must enough maintain solid particulate contacts with liquid phase, thereby guarantees that interfacial area is for the maximum availability of the mass transfer of solid-liquid.

Reactor 140 also can comprise one or more baffle plates 168, for mixing and preventing that dead angle from forming.The number of baffle plate 168 can, at 2-20, as changed in the scope of 2-10, and be evenly distributed on the periphery of reactor 140.Baffle plate 168 can be arranged on the inwall of reactor 140.Conventionally use vertical baffle, but also can use curved baffle.Baffle plate 168 may extend to higher than the liquid level 156 in reactor 140.

In one embodiment, reactor 140 comprises for removing the venting port of tail gas by pipeline 135 and for compressible HMD being back to the recovery tower 131 of reactor 140.Water 132 can be fed in recovery tower 131, and is recovered in the bottom 133 of recovery tower 131.Water 132 feeds to maintain the efficiency of recovery tower 131 with minimum speed.Calculate the water yield to maintain target salt concn, and adjustable other water charging.Discharge gas 134 and can be condensed to reclaim any water and monomer tail gas, and can be back to pipeline 133.The gas of the incoagulability that comprises nitrogen and air can be used as tail gas stream 135 and is removed.When recovery tower 131 is vent condenser, recovery tower 131 can be used for reclaiming tail gas and removes non-condensable gases.

the storage of nylon salt solution

As shown in Figure 3, after nylon salt solution forms, it is supplied into hold-up vessel 195, and described nylon salt solution can be stored in hold-up vessel 195 until polymerization needs.In some embodiments, hold-up vessel 195 can comprise recirculation loop 193, in order to the nylon salt solution that circulates.Can use internal spray mixing tank 194 to maintain the circulation in hold-up vessel 195.In a specific embodiment, internal spray mixing tank 194 can be arranged on apart from hold-up vessel 195 0.3-1.5m places, bottom, preferably 0.5-1m place.In addition, in some embodiments, at least partly nylon salt solution can be back in reactor 140, to prevent that process pipeline from freezing and/or adjust nylon salt solution when system confusion or target pH value and/or target salts solution need to change.Any untapped nylon salt solution from polymerization technique 200 also can be back to hold-up vessel 195.

Hold-up vessel 195 can be by selecting free austenitic stainless steel, and as 304,304L, 316 and 316L, or other can provide the material structure of the group that the suitable corrosion resistant material of economically feasible sexual balance forms to form between equipment life and cost of investment.According to the volume of the size of hold-up vessel and nylon salt solution to be stored, hold-up vessel 195 can comprise one or more hold-up vessels.In some embodiments, nylon salt solution is stored at least two hold-up vessels, at least 3 hold-up vessels, at least 4 hold-up vessels or at least 5 hold-up vessels.Hold-up vessel 195 can be maintained at the temperature higher than solution solidifies point, as between 60-110 ℃.Because the salt concn of nylon salt solution is 60-65wt.%, so temperature can remain between 100-110 ℃.In hold-up vessel, can there is interior heater 196.In addition, recirculation loop can contain one or more well heaters 197, for providing heat to hold-up vessel.For example, hold-up vessel can have and holds the capacity that reaches 5 days stocks, more preferably reaches 3 days stocks' nylon salt solution.Hold-up vessel can keep normal pressure or be slightly higher than normal pressure in nitrogen atmosphere.

In some embodiments, before entering hold-up vessel 195, nylon salt solution can filter to remove impurity.Nylon salt solution can pass through at least one strainer 190, as at least two strainers or at least three strainers filter.Strainer 190 can in parallel or series connection setting.Suitable strainer can comprise the membrane filter containing polypropylene, Mierocrystalline cellulose, cotton and/or glass fibre.In some embodiments, the aperture of strainer is between 1-20 micron, between 2-10 micron.Described strainer also can be ultra filtration filter, micro-filtration unit, nanofiltration strainer or activated charcoal filter.

supplement HMD

Described in above, form two positions of nylon salt solution HMD used in described technique and add distinct portions, main HMD and supplementary HMD.For the nylon salt solution that allows to use single continuous stirred tank reactor and form homogeneous, once nylon salt solution is taken out and enters pipeline 144 and enter subsequently hold-up vessel 165 from reactor 140, do not add HMD.The parameter that departs from objectives as the control of the difference of target pH value can be by comprising as shown in Figure 5 at tie point 142 places to come further accurately via the supplementary HMD of pipeline 107.The minimum part of the HMD that supplementary HMD normally added, as the trickle adjustment of nylon salt pH, this is owing to comparing with main HMD charging, using less valve can control better the minor variations of flow.Due to the adjustment of main HMD and the delay between pH pH-value determination pH, the feeding rate of the main HMD of less preferred employing adjustment or the method for flow rate are controlled the pH value of nylon salt solution.In addition, because supplementary HMD is the minimum part that joins the HMD of CSTR, supplementary HMD makes to adjust more accurately the pH value of nylon salt solution, and pH analyser provides nearprompt feedback.Supplement the upstream that HMD measures at pH and add, in measurement, add and supplement diamines to the delay aspect the impact of pH value reducing.When adjusting supplementary HMD, also can adjust water feeding rate to control the solids concn in nylon salt solution.As described herein, the refractometer in the available controller setting of this adjustment available sample line 153 is monitored.

Supplementary HMD107 can mix with nylon salt solution before it enters pipeline 144.Although there is no theoretical constraint, can think that supplementing HMD107 can react with any remaining free AA in nylon salt solution.In addition, as mentioned above, add and supplement the pH value that HMD107 can be used for adjusting nylon salt solution.

In one embodiment, the present invention relates to the AA powder from weight-loss type feeder 110 to feed pipe based on weight metering, by the AA powder feed 139 of metering, the input speed with low variability is transferred in continuous stirred tank reactor 140 described feed pipe; Individually the aqueous solution 106 that comprises the HMD104 of first part and water 103 is incorporated into and in continuous stirred tank reactor 140, forms nylon salt solution; And pass through pipeline 107 by second section HMD, for example supplement HMD and be incorporated in nylon salt solution.Can supplementary HMD107 be joined in the nylon salt solution in recirculation loop 141 at tie point 142.Supplement HMD107 and be constantly added in recirculation loop 141 with certain feeding rate, described certain feed rate can make the flow that supplements HMD107 for by the middle-grade flow of valve, as 20-60%, and 40-50%, or approximately 50%.Middle-grade flow refers to that the continuous flow maintaining by valve is out of hand to prevent.

For obtaining having the target pH value of low variability, described technique comprises the constant feeding rate of utilizing weight-loss type feeder 110 that AA powder 102 is provided, and the feeding rate of adjustment HMD and water is controlled with response technique.Advantageously, from continuous processing, obtain high productivity.When changing salt throughput rate, because AA feeding rate changes within the discrete timed interval, HMD feeding rate can be adjusted pro rata.The feeding rate of HMD can be by changing the feeding rate of main HMD charging or the feeding rate of supplementary HMD regulates.In a preferred embodiment, for given salt throughput rate, can regulate the feeding rate of supplementing HMD107, and the feeding rate of the feeding rate of HMD104 or HMD aqueous solution charging 106 can be constant.In optional embodiment, if necessary, the feeding rate of supplementing HMD107 can be set as constant speed, and the feeding rate of the feeding rate of adjustable HMD104 or HMD aqueous solution charging 106 is to reach target pH value and/or target salt concn.In some other embodiment, the feeding rate of the feeding rate of adjustable HMD104 and supplementary HMD107 or the HMD aqueous solution 106 is to reach target pH value and/or salt concn.

Supplementary HMD107 can have identical HMD source with HMD104.HMD104 can comprise the 80-99% of total HMD in nylon salt solution, as 90-99%.Supplementary HMD107 can comprise the 1-20% of total HMD in nylon salt solution, as 1-10%.The ratio of HMD104 and supplementary HMD107 can regulate according to target pH value and target salt concn.As discussed herein, the ratio of HMD104 and supplementary HMD107 can be by the model specification for total HMD feeding rate.

HMD can be with the form supply of pure HMD, as containing 99.5wt.%HMD at least, and as 100%HMD and anhydrous, or with the form supply of the aqueous solution containing 80-99.5wt.%HMD.Supplementary HMD107 can be with the form charging of pure HMD or the HMD aqueous solution to nylon salt solution.When supplementary HMD107 is the HMD aqueous solution, the aqueous solution that supplements HMD107 can comprise the HMD of 50-99wt.%, as the HMD of 60-95wt.% or 70-90wt.% at least.When this aqueous solution is when the HMD104, the source that the amount of water can be based on HMD and the target salt concn of nylon salt solution regulate.Advantageously, the HMD concentration of supplementing HMD107 is 90-100wt.%, thereby in the minimized while of impact that supplementary HMD107 is controlled salt concn, improves the impact that it is controlled pH value.

Supplementing HMD107 joins in the nylon salt solution in recirculation loop in the upstream of pump 149 and sample line 153.After adding supplementary HMD107, can on sample line 153, with analyser 154, measure the pH value of nylon salt solution in recirculation loop 141.This just makes to regulate between pH value and pH pH-value determination pH and have little delay in the feeding rate by supplementary HMD107.Do not have extra AA to join in recirculation loop 141.Except supplementing HMD107, do not have HMD to join in recirculation loop 141.Supplement HMD107 and add in the upstream of pH pH-value determination pH, to allow to comprise the pH pH-value determination pH that supplements HMD.

Be different from the existing technique shown in US2010-0168375 and US4233234, supplement HMD and after pH pH-value determination pH, do not add.After pH pH-value determination pH, add membership and cause the HMD adding in mensuration on the large delay in the impact of pH value, this is because the HMD adding must flow through reactor before determined.Thereby, add by this way HMD can lower than or surpass target pH value, this will cause that these techniques move inefficiently by pursuing of goal pH value constantly.Advantageously, the present invention adds supplementary HMD in the upstream of pH pH-value determination pH, thereby makes the impact that supplements HMD only cause little delay, and has avoided the problem below or above target pH value.In addition, because valve maintains middle-grade flow, in the present invention, constantly add and supplement HMD107.

technology controlling and process

As described herein, in prior art processes for generation of polyamide salt solution, as in the continuous processing of nylon salt solution, the target component in nylon salt solution, comprises pH value and salt concn, has variability.This variability of target component can be caused by AA powder feed rate uncertain and fluctuation at least partly.This unpredictability and fluctuation make technique be difficult to control, this be because this technique must be in the downstream of initial reactor, constantly monitor and regulate before storing.Thereby the single reactor of operation is difficult to effectively overcome this uncertain AA powder feed rate with fluctuating continuously.Traditionally, in order to overcome this unpredictability and fluctuation, adopt several reactors, mixing tank and a plurality of monomer feed position especially to add the position of HMD to produce to have the nylon salt solution of target component.According to the present invention, adopt single continuous stirred tank reactor to remove the ability of adjusting the nylon salt solution in several reactors.Yet, by using weight-loss type feeder to reduce unpredictability and the fluctuation of AA powder feed rate, can obtain changing the AA powder feed rate lower than ± 5%, the present invention can utilize the feed forward control based on model, in conjunction with or not in conjunction with feedback information, to obtain having the nylon salt solution of target pH value and target salt concn.

feed forward control

Between the continuous processing of producing nylon salt solution starts, the productivity of nylon salt solution that can be based on required is set up reaction model.Based on described productivity, set AA powder feed rate, the pH value of then setting objectives and target salt concn.Then by stoichiometric ratio, calculate HMD feeding rate and water feeding rate to reach target pH value and target salt concn.HMD feeding rate comprises main HMD and supplementary HMD.Water feeding rate comprises the water in all sources that feed reactor 140.It should be understood that the target mol ratio of target pH value reflection AA and HMD.In further embodiment, extra feature can join in described model, includes but not limited to temperature of reaction and reaction pressure.This model is used to and enters the HMD of continuous stirred tank reactor and/or the feeding rate of water arranges feed forward control.

The feeding rate of the AA powder being provided by described herein weight-loss type feeder by input in some embodiments, is set up model.For a given productivity, the feeding rate of AA should be constant.Just as described in this article, weight-loss type feeder can comprise discrete control to produce the AA powder feed rate with low variability.From the AA powder feed rate of weight-loss type feeder serially, semi-continuously or in discrete time interval, model as described in every 5 minutes, every 30 minutes or per hour offering.In other respects, due to the low variability of AA powder feed rate, once AA powder feed rate is set, described model can be set the feeding rate of HMD and the feeding rate of water.These feeding rates are by described model specification, to obtain target pH value and target salt concn.

Described model can be dynamic, and can be according to regulating from feedback signal online or off-line type analyser.For example, if need to change productivity, pH value and salt concn, can adjust model.Described model can be kept in the storer of controller, as programmable logic controller (PLC) controller, dcs (DCS) controller or proportional-integral-differential (PID) controller.In one embodiment, the PID controller that there is feedback signal can be used for illustrating model calculates and flow measurement in error.

Owing to using the feeding rate that volumetric feeder can not Accurate Prediction AA powder, the nylon salt solution that entirely forms by feed forward control the parameter low rate of change that departs from objectives is unpractical before.This at least a portion is the variation due to the AA powder feed rate of using volumetric feeder to cause.Due to the variability of AA powder feed, cannot set up model for controlling the ratio of AA and HMD.Therefore, these traditional technologys can be used feedback control, thereby need to adjust continually or for batch technology.Yet when entering the AA powder of continuous stirred tank reactor based on weight metering, feed forward control is just enough to produce continuously with the depart from objectives nylon salt solution of parameter of low rate of change.

Thereby, in one embodiment, the present invention relates to one for controlling the technique of the continuous production of nylon salt solution, comprising: generate for setting the model of the target feed speed of dicarboxylic acid powder, to produce the nylon salt solution with target pH value; Based on weight, the dicarboxylic acid powder of metering from weight-loss type feeder to feed pipe, thereby the variability of control dicarboxylic acid powder feed rate, described feed pipe enters dicarboxylic acid powder in single continuous stirred tank reactor with target feed rate transitions; Respectively diamines and water are introduced in single continuous stirred tank reactor with the first feeding rate and the second feeding rate, wherein the first feeding rate and/or the second feeding rate are based on model; And nylon salt solution is taken out and directly sends into hold-up vessel continuously from single continuous stirred tank reactor, the pH value of nylon salt solution of wherein taking out and the deviation value of target pH are lower than ± 0.04.

In order to further illustrate according to technology controlling and process scheme of the present invention, as Fig. 6 has shown schematic diagram.In order to simplify, in Fig. 6, do not show a plurality of pumps, recirculation loop and well heater.The many under meters for the flow of measuring system in Fig. 6, have been shown, as coriolis mass flowmeters, positive displacement flow meter, magnetic flow meter and turbo flow meter etc.In some embodiments, under meter also can be measured temperature and/or density.The output signal of under meter is input in controller 113 serially or termly.Preferably, in the upstream of each under meter valve, all there is at least one under meter.In some embodiments, these under meters and under meter valve can be whole, and provide together with the form of compact apparatus.Although only show a controller, in some embodiments, can have a plurality of controllers.As shown in Figure 6, AA powder feeds in weight-loss type feeder 110, to produce the AA powder feed 139 of metering by pipeline 102.Controller 113 is delivered to rotating screw thruster 123 by signal 211.Signal can be wireless signal.Utilize model, the feedforward feeding rate model of HMD and water can be stored in controller 113.As mentioned above, weight-loss type feeder 110 regulates the variability of AA powder, thereby the AA powder feed 139 of the metering that low variability departs from objectives feeding rate is provided.For example, weight-loss type feeder 110 can use the feedback loop from weight measurement subsystem 121, to regulate the speed of rotating screw thruster 123.

Controller 113 sends feed-forward signal 213 and under meter valve 214, with adjusting, by pipeline 106, enters the flow of the water 103 of reactor 140.Similarly, thus controller 113 sends feed-forward signals 215 regulates the flow that enters the HMD104 of reactor 140 by pipeline 106 under meter valve 216.These feed-forward signals by model specification to reach target pH value and target salt concn.In another embodiment, controller 113 sends feed-forward signal (not shown) and under meter valve (not shown), with adjusting, enters the feeding rate of the HMD aqueous solution 106 of reactor 140.Therefore because feed-forward signal 213 and 215 is for entering HMD and the water of reactor 140, it not is essential the HMD aqueous solution 106 being carried out to online or off-line type measures.In addition, there is the feed-forward signal 217 that flows under meter valve 218, to regulate the flow of the supplementary HMD107 that enters recirculation loop 141.Model can be determined by the relative quantity of the HMD charging of main HMD and supplementary HMD.Regulate feed-forward signal 217 take and guarantee that the under meter valve 217 of supplementary HMD is middle-grade output flow.In one embodiment, model can be set up feeding rate, and it reaches flow metering valve 218 by feed-forward control signals 217, to guarantee to maintain the constant flow from supplementing HMD107, i.e. middle-grade flow.

secondary process is controlled

Except using feed forward control, technology controlling and process can comprise that feedback signal controls as secondary process based on modeling as shown in Figure 6, to obtain target pH value and target salt concn.These feedback signals can be from for adjusting HMD and water charging, especially supplement HMD and the under meter of water charging and the observed value of on line analyzer 154.On line analyzer 154 can comprise pH probe, refractometer and its combination.These pH probes and refractometer can in parallel or series connection.

Just as described in this article, when based on weight metering AA powder, the feeding rate of AA powder has low variability.This low variability provides reliable AA powder feed rate, has improved the ability that reaches target pH value and target salt concn and the ability that regulates HMD and water feeding rate based on feedback signal.Therefore, in a specific embodiment, the present invention relates to one for controlling the technique of the continuous production of nylon salt solution, comprising: generate for setting the model of the target feed speed of dicarboxylic acid powder, to produce the nylon salt solution with target pH value; Based on weight, the dicarboxylic acid powder of metering from weight-loss type feeder to feed pipe, thereby the variability of control dicarboxylic acid powder feed rate, described feed pipe enters dicarboxylic acid powder in single continuous stirred tank reactor with target feed rate transitions; And respectively diamines and water are introduced to single continuous stirred tank reactor with the first feeding rate and the second feeding rate, to produce the nylon salt solution with target pH value; With the 3rd feeding rate, supplementary diamines is incorporated in the recirculation loop of single continuous stirred tank reactor continuously; In the downstream that introduce to supplement diamines, utilize the variation of pH value of the online pH observed value monitoring nylon salt solution of nylon salt solution; Adjust the variation that the 3rd feeding rate responds pH value, to produce pH value, depart from objectives pH lower than ± 0.04 nylon salt solution.

As shown in Figure 7, the online analyser 154 of technology utilization, produce feedback signals as online pH meter 154, to measure the pH value of the nylon salt solution in recirculation loop 141.In order to be conducive to the on-line measurement of the pH value of nylon solution, nylon salt solution is taken out continuously from reactor, and at least a portion nylon salt solution is imported to recirculation loop 141 and sample line 153.Recirculation loop 141 can comprise under meter (not shown) and under meter valve.In another specific embodiment, recirculation loop 141 can comprise pressure controller (not shown), to control flowing of nylon salt solution.Preferably, the flow through flow of nylon salt solution of recirculation loop 141 is constant.Sample line 153 comprises the device measured as pH meter and/or salt concn for the device of pH pH-value determination pH as refractometer.In a specific embodiment, the pH value of at least a portion nylon salt solution is measured under reactor condition, without any dilution or cooling.Then this at least a portion nylon salt solution directly or be back to reactor 140 by vent condenser 131.When this at least a portion nylon salt solution is back to reactor by vent condenser 131, nylon salt solution can replace feeding the water of vent condenser.Sample line 153 also can comprise for the water cooler (not shown) of cooling nylon salt solution before mensuration pH value with for measuring the temperature sensor (not shown) of temperature before measuring pH value.In some specific embodiments, before pH value determination, nylon salt solution is cooled to target temperature.This target temperature can be in the target zone of the low 5-10 of nylon salt solution ℃ than existing in reactor 140.This temperature can depart from objectives temperature lower than ± 1 ℃, as changed lower than ± 0.5 ℃.Can there is temperature sensor (not shown), to monitor the temperature of measuring the nylon salt solution of upstream at pH.

Then online pH meter 154 provides output signal 226 to controller 113.The pH value that this output signal 226 records online pH meter passes to controller 113.Online pH meter is for being determined at the variation of the pH value of continuous processing nylon salt solution.In other words, due to the condition changing, online pH meter can be measured pH value that can be different from target pH value, but when the pH value of measuring changes, controller 113 is adjusted the charging of monomer.In preferred embodiments, the variation of the pH value of nylon salt solution is lower than ± 0.04, as lower than ± 0.03 or lower than ± 0.015.Due to the skew of online pH meter observed value, online pH meter is for measuring the variability of pH but not pH absolute value.This ascribes feed forward control that can target setting pH value at least in part to.If pH value changes, by using online pH meter to measure, can detect the variation in production technique.Employing secondary is controlled, and the variation of pH value can cause at least one the corresponding adjustment in the feeding rate of sending into respectively under meter valve 216 and 218 by signal wire 215 and 217.For providing sensitive pH value to regulate, by line 217, signal is delivered to valve 218 and supplement HMD107 to adjust.The adjustment amount that supplementary HMD107 is made can take in by the corresponding change of making through 216 couples of main HMD104 of under meter valve.This adjustment responds, once not show that pH value changes, it should be able to be recovered to the feeding rate that feed forward control is set.On supplementing the adjustment of HMD107, also can affect the salt concn of nylon salt solution.The variation of this kind of salt concn can be adjusted and be controlled by the water of under meter valve 214 by signal 213.

Because the described technique that is used to form nylon salt solution is continuous, the pH observed value in online pH meter 154 is (as continuously) or obtain closely in real time in real time.In some embodiments, every 60 minutes of pH pH-value determination pH, carries out as every 45 minutes, every 30 minutes, every 15 minutes or every 5 minutes.The tolerance range of pH meter is in ± 0.05 scope, in ± 0.02 scope.

Except online pH meter 154, described technique can further comprise the salt concn of utilizing refractometer to measure nylon salt solution, and adjusts water feeding rate.In one embodiment, can regulate by feeding the water of recovery tower 131 feeding rate of water.Salt concn can regulate by adding or remove water in the nylon salt solution to reactor downstream.

According to the required adjustment based on feedback, model also can control to adjust main HMD and water with secondary.When pH tends to cause the long-run adjustment that supplements HMD107, this control is particularly favourable.

Except the feedback information from online pH meter 154, each under meter provides information or quality feeding rate can to controller 113.As shown in Figure 7, each under meter valve is all connected with under meter, and described under meter preferably can measurement quality flow.Under meter 214 ' provides information to controller 113 by pipeline 213 '.Under meter 216 ' provides feedback information to controller 113 by pipeline 215 '.Under meter 218 ' provides feedback information to controller 113 by pipeline 217 '.From the Information Availability of under meter in maintaining total feeding rate.

Utilize the existing technique of the pH value of pH probe measurement nylon salt solution to be disclosed.Referring to US4233234 and US2010/0168375.Yet each these existing technique is all measured the pH value of nylon salt solution, then add extra diamines and/or acid to adjust pH value.Extra diamines and/or the effect of diacid until extra diamines and/or diacid be mixed into reactor and from reactor, withdraw from again and measure and can determine.This method causes " chasing " pH value, and causes and can surpass or lower than insensitive technology controlling and process of target pH value.

In the present invention, as shown in Fig. 3,5,6,7,8 and 9, supplementary HMD107 preferably adds in the upstream of online pH meter.Thereby the HMD supplementing in HMD107 mixes in reactor recirculation loop with nylon salt solution, and measures the pH value of nylon salt solution before it is recycled by reactor 140.

Having the secondary process of measuring online experiment chamber controls

As mentioned above, the pH value of controlling from secondary process is measured must not reflect target pH value, but for the variation of pH value is described.In order to improve the susceptibility of pH pH-value determination pH, secondary process is controlled also can relate to the pH value of measuring nylon salt solution under the control of laboratory.Although be not bound by theory, owing to having improved the susceptibility of the pH value measurement at nearly yield-point place under the concentration reducing and temperature condition, the pH value of measuring nylon salt solution under therefore controlling in laboratory has improved the tolerance range of measuring.This can make it possible to detect under reaction conditions, may note less than the variation of little pH.In order to realize object of the present invention, laboratory condition refers at 15-40 ℃, as 20-35 ℃ or measure nylon salt solution example at the temperature of 25 ± 0.2 ℃.The nylon salt solution example of measuring under laboratory condition has 8-12%, the salt concn as 9.5%.The mensuration of the pH value under laboratory condition can be carried out online by the nylon salt solution in dilution and cooling sample line 153.

Therefore, in one embodiment, the present invention relates to one for controlling the technique of the continuous production of nylon salt solution, comprising: generate for setting the target feed speed of dicarboxylic acid powder and with generation, there is the model of the nylon salt solution of target pH value; Based on weight, the dicarboxylic acid powder of metering from weight-loss type feeder to feed pipe, thereby the variability of control dicarboxylic acid powder feed rate, described feed pipe enters dicarboxylic acid powder in single continuous stirred tank reactor with target feed rate transitions; And respectively diamines and water are introduced in single continuous stirred tank reactor with the first feeding rate and the second feeding rate, to produce the nylon salt solution with target pH value; With the 3rd feeding rate, supplementary diamines is incorporated in the recirculation loop of single continuous stirred tank reactor continuously; In the downstream of introducing supplementary diamines, obtain the sample part of nylon salt solution; Sample is partly diluted with cooling, to form the nylon salt solution with the concentration of 5-15% and the dilution of 15-40 ℃ of temperature; The variation of the pH value of the nylon salt solution that the online pH observed value monitoring that utilizes introducing to supplement the nylon salt solution in diamines downstream is diluted; Adjust the variation that the 3rd feeding rate responds pH value, to produce pH value, depart from objectives pH value lower than ± 0.04 nylon salt solution.

As shown in Figure 9, in order to be conducive to the pH value to nylon salt solution under laboratory condition, carry out on-line testing, nylon salt solution is withdrawn from continuously from reactor, and by least a portion nylon salt solution, as being less than 1% importing recirculation loop 141 and sample line 153.Sample line 153 comprises the device for pH value determination under laboratory condition.Sample line 153 also can comprise water cooler (not shown), with cooling nylon salt solution.In other embodiment, this water cooler can omit.The temperature of the nylon salt solution in sample line 153 and concentration can be by adding water to regulate through pipeline 220.The sub-fraction of total water feeding rate that this water is calculated by model.This water is to add under being enough to reach for the add-on of the required temperature of the nylon salt solution example of the dilution of pH pH-value determination pH and concentration and temperature condition.In described technique, also can comprise sample further cooling to dilution.The pH value of at least a portion nylon salt solution is measured under laboratory condition, and this at least a portion nylon salt solution reactor 140 that is back to as described herein then.Then online pH meter offers controller 113 by output signal 226.

As described above, online pH meter 154 is for measuring the variability of the pH value of nylon salt solution.In preferred embodiments, the variation of the pH value of nylon salt solution is lower than ± 0.04, as lower than ± 0.03, or lower than ± 0.015.The pH value being similar under reaction conditions is measured, and due to the skew of online pH meter observed value, the online pH meter under laboratory condition is used to measure variation rather than the target pH value of pH.This is due to feed forward control that can target setting pH value at least partly.If pH value changes,, by utilizing online pH meter to measure, the variation of production technique can be detected.Be similar to secondary process and control, can to feeding rate, regulate by sending a signal under meter valve 216 and 218 to pipeline 215 and 217.These adjustings also can affect the salt concn of nylon salt solution.The variation of this kind of salt concn can be controlled and be controlled by the water of under meter valve 214 by signal 213.

Because the described technique that is used to form nylon salt solution is continuous, the pH value measuring result in online pH meter 154 is (as continuously) or acquisition closely in real time in real time.In some embodiments, the measurement of pH can be every 60 minutes, carries out as every 45 minutes, every 30 minutes, every 15 minutes or every 5 minutes.The tolerance range of the measuring method of pH value is ± 0.05, as ± 0.03 or ± 0.01.

three grades of technology controlling and process

Although adopt feed forward control and feedback signal can contribute to reduce the variability of nylon salt solution parameter as shown in Fig. 6,7 and 9, can adopt the off-line type pH value analysis of carrying out under further analysis, especially laboratory condition to monitor the homogeneity of nylon salt solution.These offline process under laboratory condition are controlled, and referred to as three grades of technology controlling and process, can comprise that pH value is measured and/or the measurement of salt concn.In one embodiment, the pH value of nylon salt solution can be carried out off-line type mensuration under laboratory condition, to determine whether to reach target pH value.Off-line type pH value is measured and any plant issue or adjustable deviation also can be detected.The pH value of the nylon salt solution recording at laboratory condition off-line in another embodiment, also can be used for adjusting the signal pipe line 215 and 217 that is connected under meter valve 216 and 218.The measurement of the off-line type pH value under laboratory condition can be measured pH value ± 0.01.

Thereby, in one embodiment, the present invention relates to one for controlling the technique of the continuous production of nylon salt solution, comprising: generate for setting the model of the target feed speed of dicarboxylic acid powder, to produce the nylon salt solution with target pH value; Based on weight, the dicarboxylic acid powder of metering from weight-loss type feeder to feed pipe, thereby the variability of control dicarboxylic acid powder feed rate, described feed pipe enters dicarboxylic acid powder in single continuous stirred tank reactor with target feed rate transitions; And respectively diamines and water are introduced to single continuous stirred tank reactor with the first feeding rate and the second feeding rate, to produce the nylon salt solution with target pH value; With the 3rd feeding rate, supplementary diamines is incorporated in the recirculation loop of single continuous stirred tank reactor continuously; From the nylon salt solution introducing the downstream that supplements diamines, shift out sample, for the aqueous solution at 15-40 ℃, carry out the off-line type pH value of nylon salt solution and measure; Determine the deviation that online pH value is measured and off-line type pH value is measured; Utilization is positioned at and supplements diamines and introduce the variation that the on-line pH value measuring result devious of the nylon salt solution in downstream is monitored the pH value of nylon salt solution; And adjust the variation that the 3rd feeding rate responds pH value, to produce pH value, depart from objectives pH value lower than ± 0.04 nylon salt solution.

As shown in Figure 8, at least a portion of the nylon salt solution in sample line 153 is directed to by online pH meter 154, obtain therein pH value measuring result, and output signal 226 is directed to controller 113.Sample line 153 also can comprise water cooler (not shown), so as before the pH meter 154 of flowing through cooling nylon salt solution.At least a portion of nylon salt solution in sample line 153 can shift out by pipeline 221, and measures with laboratory pH meter 222.Water by pipeline 220 add in pipeline 221 with by diluted sample to specific concentration, then it is cooled to target temperature again, as between 15-40 ℃ or nearly 25 ℃.In one embodiment, water coolant can be used for dilution and cooling sample.The pH value of the nylon salt solution in pipeline 221 is measured, and output signal 226 is sent to controller 113.The nylon salt solution part of then testing under laboratory condition can combine with the sample after tested of return line 155, then by pipeline 224, is back to reactor 140.The nylon salt solution part of testing under laboratory condition in some embodiments, can be fallen from the outside drain of technique 100 by pipeline 223.

For reaching laboratory condition temperature and concentration, the nylon salt solution example shifting out from recirculation loop can be used the water adding through pipeline 220 to dilute and be cooling.Also can carry out with temperature bath the nylon salt solution example of cooling dilution.Sample can be withdrawn from as required, every 4-6 hour for example, every day or per week.When system is chaotic, sample can be more continually, as per hour, is removed.Conventionally, off-line type pH analyser can be used for illustrating the Deviation of equipments of on line analyzer.For example, if target pH value is 7.500, online pH analyser can record 7.400 and off-line analysis instrument can survey 7.500, and this just shows the Deviation of equipments of online pH analyser.In one embodiment, when carrying out off-line measurement, exponentially weighted moveing average can be used for automatically departing from line analyzer.In certain embodiments, the output of off-line analysis instrument can be used for proofreading and correct any deviation or the skew of on line analyzer.In other embodiments, although on line analyzer is not corrected, can utilize off-line analysis instrument monitoring skew or deviation.In this respect, rely on line analyzer to determine the variation of pH value, as be positioned at outside default acceptable variability.

In other embodiments, available off-line analysis instrument is measured the target salt concn of nylon salt solution.The salt concn measuring result of off-line also can detect any plant issue or adjustable deviation.When using a plurality of refractometer, each refractometer can be setovered independently.

nylon polymerization

Nylon salt solution described herein can be directed in polymerization technique 200, and to form polymeric amide, especially nylon 6,6.Nylon salt solution can directly be delivered to polymerization technique 200 by continuous stirred tank reactor 140, or is first stored in hold-up vessel 195, then delivers to polymerization technique 200, as shown in Figure 10.

Nylon salt solution of the present invention has the pH value of homogeneous, and it can improve the performance of polymerizing polyamide technique.The nylon salt solution with homogeneous pH value provides reliable starting raw material for producing different polyamide products.This has just improved the reliability of polymerization product greatly.Conventionally, polymerization technique comprises that from nylon salt solution vaporize water is to concentrate nylon salt solution, and makes concentrated nylon salt carry out polymerization to form polyamide product by polycondensation.Described technique can be used one or more vaporizers 202.Evaporation of water can or add in vacuum to depress and carries out, to remove at least 75% of water in nylon salt solution, and more preferably at least 95% of the water in nylon salt solution.Concentrated nylon salt 203 can comprise the water of 0-20wt.%.Polycondensation can be carried out in batch technology or continuous processing.According to required final polymeric articles, can in polymerization reactor 204, add extra AA and/or HMD.In some embodiments, additive can be combined with polyamide product.

In order to realize object of the present invention, suitable polyamide product can at least 85% carbochain between amide group be aliphatics.

When nylon salt solution is transferred to vaporizer 202 by hold-up vessel 195, its temperature is maintained at it more than fusing point.This can be avoided blocking pipeline.In some embodiments, the steam obtaining from vaporizer 202 can be used for holding temperature.In other embodiments, also can use the water coolant of heating.

Polymerization can be carried out in single-stage reactor or multistage polycondensation reactor 204.Extra monomer, AA or HMD, but preferably HMD can add by pipeline 205, to produce different nylon product 208.Reactor 204 can comprise for mixing the agitator of nylon salt.Reactor 204 can have chuck, utilizes heat exchange medium to adjust temperature.Polycondensation in reactor 204 can be carried out in inert atmosphere, can in reactor 204, add nitrogen.According to initial dicarboxylic acid and diamines, polymerization temperature can change, but usually above the melt temperature of nylon salt, more preferably higher than at least 10 ℃ of melt temperatures.The melt temperature of the nylon salt that for example, comprises hexamethylene-diamine adipate is 165-190 ℃.Therefore, polycondensation can be at 165-350 ℃, as carried out under the temperature of reactor of 190-300 ℃.Polycondensation can be carried out under barometric point or pressurization atmosphere.Nylon product 208 can free-pouring solid phase prod form from reactor, take out.

The water producing in polycondensation can be removed by reactor draft tube liner 209 in the mode of vapour stream.Vapour stream can be condensed, and the gas phase monomer of escaping together with water, can be returned to reactor as diamines.

Also can carry out follow-up processing, as extrude, spinning, stretching or tensile deformation, to produce polyamide product.The group that polyamide product can select free nylon 4,6, nylon 6,6, nylon 6,9, nylon 6,10, nylon 6,12, nylon 11 and nylon 12 to form.In addition, polyamide product can be multipolymer, as nylon 6/6,6.

The embodiment of following indefiniteness has described technique of the present invention.

Embodiment

Embodiment 1

Adopt mechanical conveying system (being screw rod/haulage chain) or pneumatic conveyor system (being forced air, evacuated air or closed loop nitrogen), by Shipping Sack discharging, the discharging of liner Shipping Sack, the discharging of liner box container or hopper rail car discharge terminal, AA powder is moved to supply container from discharge system.

Supply container moves into weight-loss type (L-I-W) material feeder by required AA powder, and it adopts low level and the high position of PLC based on selected L-I-W hopper to regulate.Supply container measures AA powder by screw transporter or rotary type feeder with enough loading rates, described enough loading rates make to equal at largest interval, and be preferably less than 1/2nd of minimum L-I-W discharging time from a high position to low level L-I-W storehouse and fill L-I-W material feeder hoppers, so that receive the feedback signal of L-I-W material feeder feeding rate when at least 67% time.

L-I-W feed system is adjusted the speed of L-I-W feed worm, as detected in L-I-W hopper pressure measuring unit, feeding rate is maintained to the feeding rate target of receiving from dispersing control system (DCS).

As shown in figure 11, the feeding rate variability of the hexanodioic acid by weight-loss type feeder has the feeding rate variability lower than ± 5% within the continuously feeding cycle of 48h.As shown in figure 12, within the cycle of 40h, the variability of feeding rate can be lower than ± 3%.As shown in figure 13, within the cycle of 18h, the variability of feeding rate can be lower than ± 1%.By eliminating the disturbance due to the hexanodioic acid feeding rate of using volumetric feeder to cause, using can improved feeding rate variability performance for the weight-loss type feeder of hexanodioic acid.

Embodiment 2

For producing nylon salt solution according to continuous processing, set up model.Described nylon salt solution comprises water and hexamethylene-diamine adipate.Described model is set, to reach in nylon salt solution 63% salt concn and to obtain 7.500 target pH value.The feeding rate of AA is determined in the production of the nylon salt solution based on required.Salt concn based on reaching and pH value, can determine the feeding rate of HMD and water.Hexanodioic acid moves to weight-loss type feeder with low variability as described in Example 1 from powder discharge system.

AA powder from weight-loss type feeder is directly supplied with continuous stirred tank reactor by charging conduit, and described charging conduit is that nitrogen is with 20-30nm ³the speed of/h is sprayed to clean continuously the steam skewed slot producing in feeding machine and reactor.

The DCS model of the object library storage that the salt feeding rate of utilization based on from salt reactor continuous stirred tank reactor and salt store, determines the DCS set-point of weight-loss type hexanodioic acid input speed.The feeding rate of described salt can be passed through coriolis mass flow meter measurement, and it can be based on inventory model but not directly use hexanodioic acid feeding rate to be intervally adjusted to target value can set.Typically, hexanodioic acid feeding rate can be directly used together with feeding back to the feeding rate of weight-loss type feeder of DCS.

Concentration is that 98% HMD solution stores recirculating main from pressure controlled HMD and supplies with online static mixer.Utilization provides the coriolis mass flow meter measurement of input to DCS, DCS utilizes the adjustment of feedforward ratio control circuit to enter the feeding rate of the HMD incoming flow of static mixer, thereby accurately control based on AA powder feed rate, joins the HMD in continuous stirred tank reactor.This main HMD charging accounts for approximately 95% of the required HMD charging of technique.

By adjust the setting point of DCS HMD proportional flow controller for supplementing feedback loop that the output of HMD valve controls, with maintain supplement HMD valve be output as middle-grade, thereby guarantee that described valve is positioned at controlled range continuously.

Deionized water is supplied with online static mixer from pressure-controlling deionized water supply main.Utilization provides the coriolis mass flow meter measurement of input to DCS, DCS utilizes the adjustment of feedforward ratio control circuit to feed the deionized water feed fluid flow rate of static mixer, accurately to control the water concentration of AA and HMD in continuous stirred tank reactor.The feeding rate of deionized water is set in DCS, so that deionized water enters the vent condenser of reactor with required rate of injection.

Online static mixer product flow directly enters the top of the CSTR that is positioned at hexanodioic acid feed chute 0.3-1.0 rice, and this specific position is conducive to help the dissolving of the hexanodioic acid charging that enters.

Utilization is arranged in the pH meter pH value determination continuously of the redundancy of sample recirculation loop after the filtration that the recirculating pump by reactor provides, temperature and flow control.Utilize the pH value input of a pair of on-line pH value measuring result of the selected continuous comparison of DCS, DCS adjusts the feeding rate of supplementary HMD to maintain the target set point of pH value in DCS.Supplement HMD charging and be about 5% of total HMD charging in technique.

Utilize and carry out in the discrete interval of reactor downstream, and thereby the condition concentration that is 9.5% and 25 ℃ reach the sample pH value value analysis as the most sensitive of acid/amine balance of the function of pH value, or by from constantly diluting/adjust the product of reactor or from the continuous input of the pH value of the on line analyzer of the concentration of the product to 9.5% of subsequent storage container (if preferably words) and 25 ℃, the set-point based on statistical algorithms adjustment pH value controller.

During the pump that supplements HMD and be injected into the recirculation loop of main reactor is inhaled, to reach the fastest response time to pH meter, and guarantee, within the shortest time, reactor product is adjusted to target.Pump is for HMD and reactor product salt are mixed, so that guarantee that pH meter and densitometer are homogeneous phase solution when measuring respectively.

CSTR comprises reactor chamber and recirculation loop.Recirculation loop comprises a part of nylon salt solution circulated to the first loop of reactor with by a part of nylon salt solution guiding value pH meter, is then back to the sample line of reactor.Sample line can comprise water cooler, with the cooling about 5-10 ℃ of temperature during from its outflow reactor by nylon salt solution.Measure continuously the pH value of cooling nylon salt solution.Cooled nylon salt solution is back to reactor.By the measurement feedback of pH value to technology controlling and process counter, and adjustment model.Described model is adjusted the feeding rate of HMD.

By a part of nylon salt solution off-line, then by this part nylon salt solution pH value determination under laboratory condition.Nylon salt solution in order to measure under laboratory condition, is diluted to concentration by nylon salt solution with water and is about 9.5%.By temperature bath, the nylon salt solution of dilution is cooled to approximately 25 ℃.Under laboratory condition, measure the pH value of nylon salt solution, and with target pH value and the comparison of on-line pH value measuring result.Then adjustment model is to provide the feeding rate of the HMD that can guarantee the low variability compared with target pH value.

The refractometer same spline filter that the recirculating pump of utilization by reactor provides, temperature and the redundancy in controlled sample recirculation loop that flows is measured the concentration in reactor continuously.Utilize the concentration input of a pair of online measurement of concetration result of the selected continuous comparison of DCS, DCS adjusts the set-point of DCS deionized water ratio flow director to maintain the target set point of concentration in DCS by feedback loop.

By the water level in reactor, control reactor product is sent to salt storage place continuously.This transmission comprises at least one group of filter cartridge type filter be arrangeding in parallel, and it for there being the 34.5kPa(5 of being to the maximum pound/square inch when flowing to the maximum instantaneous salts solution transfer rate of storage place) initial cleaning pressure falls and designs.When using synthon degree of depth filter core or folded membrane filter core, filter core is got rid of efficiency and is had the absolute nominal value that minimum is 10 μ m, maybe, when using winding cotton fibre filter core, has the rated value that minimum is 1 μ m.The selection of strainer is the filter core of rated value of the service temperature of 110 ℃ based on having for minimum.

The constantly recirculation of nylon salt solution is by salt hold-up vessel, preferably uses the tank injector mixer being arranged at from 0.5-1 rice at the bottom of tank, for changing the soonest so that mixing efficiency maximizes of tank concentration.

Salt concn for 63%, the steam flow speed that the temperature of salt hold-up vessel flows through recirculation line heat exchanger by adjustment is controlled at 100-105 ℃.Nylon salt solution in hold-up vessel has 7.500 ± 0.0135 homogeneous pH value.

Embodiment 3

As prepared nylon salt solution in embodiment 2, difference is to carry out online pH mensuration under laboratory condition: at approximately 25 ℃, and concentration approximately 9.5%.

Comparative example A

Imitate as the model in embodiment 2 and technique, difference is to use volumetric feeder but not weight-loss type feeder.Because the variation of AA powder feed is very large, model is unpractical.The pH value of the nylon salt solution pH value that departs from objectives is greater than 0.120 and change.Thereby, the vicissitudinous Tc of nylon salt solution tool and boiling temperature.Therefore, the poor controllability of pH value causes obviously higher zero pour, thereby needs higher processing temperature with the danger of pre-crystallization-preventive.Due to the boiling point changing, the controlled of this difference also causes the boiling of nylon salt solution, so reduces the output of nylon salt solution.

Comparative example B

Imitate as the model in embodiment 2 and technique, without part, be to use second CSTR.Nylon salt solution takes out from first CSTR, and feeds second CSTR.Between first CSTR and second CSTR, measure the pH value of nylon salt solution.According to pH value and target pH value, extra HMA and/or water are joined in second CSTR.From second CSTR, migrate out nylon salt solution, and measure its pH value.PH value departs from objectives 0.120 pH value cell of pH value and changes.Need extra CSTR further to regulate the pH value of this nylon salt solution, thereby cause the increase of cost of investment and running cost.

Comparative example C

Imitate as the model in embodiment 2 and technique, without part, be 100% HMD directly to feed in reactor.The pH value of the nylon salt solution pH value that departs from objectives is greater than 0.1 pH value cell and changes.

Comparative example D

Imitate as the model in embodiment 2 and technique, without part, be that inapplicable pump comes in conjunction with HMD and nylon salt solution.The pH value of the nylon salt solution pH value that departs from objectives is greater than 0.1 pH value cell and changes.

Although the present invention be have been described in detail, the revision in scope and spirit of the present invention it will be apparent to those skilled in the art that.All publications discussed above and document mode are by reference incorporated into herein.In addition, should be understood that, the aspect of the present invention of recording and a plurality of embodiment and a plurality of feature can be integrally or are partly carried out combination or exchange.In aforesaid a plurality of embodiment, those of skill in the art would recognize that mention other embodiments these embodiments can with the suitable combination of other embodiments.Further, those skilled in the art recognize aforesaid explanation by embodiment only for explaining the present invention, do not form any limitation of the invention.

Claims

1. a method of controlling nylon salt solution continuous production, comprising:

A) generate for setting the target feed speed of dicarboxylic acid powder and with generation, there is the model of the nylon salt solution of target pH value;

B) by based on weight metering the dicarboxylic acid powder from weight-loss type feeder to feed pipe control the variability of dicarboxylic acid powder feed rate, described feed pipe enters dicarboxylic acid powder in single continuous stirred tank reactor with target feed rate transitions;

C) diamines and water are introduced in single continuous stirred tank reactor with the first feeding rate and the second feeding rate respectively, wherein the first feeding rate and/or the second feeding rate are based on model; With

D) supplementary diamines charging is introduced in the recirculation loop of single continuous stirred tank reactor continuously with the 3rd feeding rate, wherein said the 3rd feeding rate is based on model;

E) use the variation that detects the pH value of nylon salt solution in the on-line pH value measurement that supplements the nylon salt solution in diamines introducing downstream; And

F) regulate described the 3rd feeding rate to respond the variation of pH value, to produce, there is the pH value that departs from objectives and be less than ± 0.04 and the nylon salt solution of the pH value that changes.

2. method according to claim 1, further produces the nylon salt solution with the target salt concn being selected within the scope of 50-65wt.%, comprises the following steps:

G) use the salt concn of measuring the nylon salt solution in recirculation loop at the one or more refractometers that supplement diamines introducing downstream; And

H) regulate the second feeding rate, with based target salt concn, control the salt concn of nylon salt solution, wherein the salt concn of nylon salt solution depart from objectives salt concn be less than ± 0.5% and change.

3. method according to claim 1, described method further comprises:

G) in the downstream that supplements diamines introducing, obtain the sample part of nylon salt solution;

H) dilution cooling described sample part, to form the nylon salt solution of the dilution of the temperature with the concentration of 5-15% and 15-40 ℃;

I) use the variation of pH value that detects the nylon salt solution of described dilution in the on-line pH value measurement that supplements diamines and introduce the nylon salt solution in downstream; And

J) regulate the 3rd feeding rate to respond the variation of pH value of the nylon salt solution of dilution.

4. method according to claim 1, described method further comprises:

G) from the nylon salt solution supplementing diamines introducing downstream, shift out sample, for the nylon salt solution of the aqueous solution being carried out to off-line pH value at the temperature at 15-40 ℃, measure;

H) determine the deviation that on-line pH value is measured and off-line pH value is measured;

I) use the variation that detects the pH value of nylon salt solution in the on-line pH value measurement devious that supplements the nylon salt solution in diamines introducing downstream; And

J) adjust the variation that the 3rd feeding rate responds pH value, to produce, there is the pH value that departs from objectives and be less than ± 0.04 and the nylon salt solution of the pH value of variation.

5. method according to claim 1, wherein, described recirculation loop comprises the pump of the group of selecting free vane pump, piston pump, flexible element pump, lobe pump, toothed gear pump, impeller pump, circumference piston pump and spiral pump composition, and supplementary diamines charging is introduced from the upstream of pump.

6. method according to claim 1, wherein, recirculation loop comprises one or more on line analyzers, for obtaining on-line pH value measuring result, and supplementary diamines charging is introduced in the upstream of described one or more on line analyzers.

7. method according to claim 1, wherein, described the 3rd feeding rate is controlled by valve, and the middle-grade flow providing by the 20-60% of described valve is provided described valve.

8. method according to claim 1, wherein, consists of the 80-99% of the total diamines in the single continuous stirred tank reaction of infeed the diamines of the first feeding rate introducing.

9. method according to claim 1, wherein, consists of the 1-20% of the total diamines in the single continuous stirred tank reaction of infeed the diamines of the 3rd feeding rate introducing.

10. method according to claim 1, wherein said continuous stirred tank reactor is maintained at the temperature of 60-110 ℃, and is maintained at normal pressure under inert atmosphere.

11. methods according to claim 1, wherein, target pH value is selected from the scope of 7.200-7.900.

12. methods according to claim 1, wherein, described dicarboxylic acid selects free oxalic acid, propanedioic acid, succsinic acid, pentanedioic acid, pimelic acid, hexanodioic acid, suberic acid, nonane diacid, sebacic acid, undecane diacid, dodecanedioic acid, toxilic acid, propene dicarboxylic acid, traumatic acid, muconic acid, 1, 2-or 1, 3-cyclohexyl dicarboxylic acid, 1, 2-or 1, the sub-phenylene-diacetic acid class of 3-, 1, 2-or 1, 3-cyclohexyl oxalic acid, m-phthalic acid, terephthalic acid, 4, 4 '-phenyl ether dioctyl phthalate, 4, 4-benzophenone base dicarboxylic acid, 2, 6-naphthyl dicarboxylic acid, p-t-butyl m-phthalic acid and 2, 5-furans dicarboxylic acid, and composition thereof the group that forms.

13. methods according to claim 1, wherein, described diamines selects free ethanol diamines, trimethylene diamines, putrescine, cadaverine, hexamethylene-diamine, 2-methyl-five methylene diamine, heptamethylene diamines, 2-methyl-hexamethylene-diamine, 3-methyl-hexamethylene-diamine, 2, 2-dimethyl-penta methylene diamine, eight methylene diamine, 2, 5-dimethyl-hexamethylene-diamine, nine methylene diamine, 2, 2, 4-and 2, 4, 4-trimethylammonium-hexamethylene-diamine, decamethylene diamine, 5-methylnonane diamines, isophorone diamine, 11 methylene diamine, ten dimethylene diamines, 2, 2, 7, 7-tetramethyl--eight methylene diamine, two (p-aminocyclohexyl) methane, two (aminomethyl) norbornane, the C2-C16 aliphatie diamine optionally being replaced by one or more C1-C4 alkyl, aliphatic poly ether diamine and furans diamines, as 2, two (aminomethyl) furans of 5-, and composition thereof the group that forms.

14. methods according to claim 1, wherein, described dicarboxylic acid is hexanodioic acid, and described diamines is hexamethylene-diamine, and described nylon salt solution comprises hexamethylene-diamine adipate.

15. methods according to claim 14, wherein, by the polymerization of hexamethylene-diamine adipate to form nylon-6,6.