Device for producing a nylon salt solution

Abstract

Apparatus for producing a nylon salt solution, characterized in that it comprises the following. a suspension production device comprising a feeding device, a continuous feeding device, a high-speed shear pump, and a production vessel provided with an inlet pipe, which are connected to each other in series, wherein the high-speed shear pump and the production vessel establish a circulating connection with each other through two connecting pipes, and wherein the feeding device is used to feed the aliphatic dicarboxylic acid, and wherein the continuous feeding device is used to feed the aliphatic dicarboxylic acid into the high-speed shear pump, and wherein the aliphatic dicarboxylic acid and water can circulate between the high-speed shear pump and the production vessel to form an aliphatic dicarboxylic acid suspension; a first salt-forming vessel connected to the suspension preparation device, the first salt-forming vessel having a first diamine feed pipe for preparing the aliphatic dicarboxylic acid suspension and the dibasic amine into a primary nylon salt solution; a second salt-forming vessel connected to the first salt-forming vessel, the second salt-forming vessel having a second diamine feed pipe and a third diamine feed pipe for preparing the primary nylon salt solution and the dibasic amine into a nylon salt solution, the second salt-forming vessel further having a circulation line, and an online near-infrared monitoring device further disposed on the circulation line of the second salt-forming vessel for monitoring the molar ratio of the aliphatic dicarboxylic acid to the dibasic amine in the nylon salt solution and controlling the feed amount of the diamine in the third diamine feed pipe in accordance with the monitoring result.

Description

RELATED APPLICATIONThis application claims priority to Chinese Patent Application No. 202410624089.2 filed on May 20, 2024, entitled "Apparatus and Method for Preparing a Nylon Salt Solution", which is hereby incorporated by reference in its entirety.TECHNICAL FIELDThe present application relates to the technical field of nylon, and more particularly to an apparatus and a method for preparing a nylon salt solution.PRIOR ARTPolyamide (polyamides), abbreviated as PA and generally known as nylon (nylon), is a general term for polymers containing amide groups (-NH-C=O) in the repeating units of the main chain of a macromolecule, and polyamide can be obtained by evaporating a salt solution prepared from aliphatic dicarboxylic acid and dibasic amine and then heating it to polymerize it, e.g., nylon 66, but such a method must ensure that the dicarboxylic acid and dibasic amine have a uniform molar equilibrium in the salt solution, for example, in the preparation of nylon 66 from adipic acid (AA) and hexamethylenediamine (HMD), an imbalanced molar ratio results in a reduced molecular weight and also deteriorates the colorability of the nylon yarn.At the beginning of the industry, the molar equilibrium is generally achieved by a batch salt process in which the molar ratio of amine to acid in the salt formation vessel is continuously tested and checked, but the batch process is not suitable for large-scale industrial production. Moreover, aliphatic dicarboxylic acids such as adipic acid powder have a broad particle size distribution, resulting in a bulk density in a wide range such as 0.6-0.7 g / cm3, and the general volumetric metering method is subject to a great error, which adversely affects the achievement of a salt solution having a uniform molar ratio.CONTENT OF THE PRESENT APPLICATIONFrom the foregoing, in view of the above problem, it is necessary to provide an apparatus and a method for producing a nylon salt solution, wherein the molar ratio of the dicarboxylic acid to the dibasic amine in the nylon salt solution obtained by using the production apparatus and the production method are more accurate.An apparatus for producing a nylon salt solution, comprising: a suspension manufacturing apparatus comprising a feeding apparatus, a continuous feeding apparatus, a high-speed shear pump, and a manufacturing vessel provided with an inlet pipe, which are connected to each other in order, wherein the high-speed shear pump and the manufacturing vessel establish a circulating connection with each other through two connection lines, and wherein the feeding apparatus is used for feeding the aliphatic dicarboxylic acid, and wherein the continuous feeding apparatus is used for feeding the aliphatic dicarboxylic acid to the high-speed shear pump, and wherein the aliphatic dicarboxylic acid and water can circulate between the high-speed shear pump and the manufacturing vessel to form an aliphatic dicarboxylic acid suspension; a first salt-forming vessel connected to the suspension manufacturing apparatus, the first salt-forming vessel having a first diamine feed tube for preparing the aliphatic dicarboxylic acid suspension and the dibasic amine into a primary nylon salt solution; a second salt-forming vessel connected to the first salt-forming vessel, the second salt-forming vessel having a second diamine feed pipe and a third diamine feed pipe for preparing the primary nylon salt solution and the dibasic amine into a nylon salt solution, the second salt-forming vessel further having a circulation line, and an online near infrared monitor is further disposed on the circulation line of the second salt-forming vessel for monitoring the molar ratio of the dicarboxylic acid to the dibasic amine in the nylon salt solution and controlling the feed amount of the diamine in the third diamine feed pipe in accordance with the monitoring result.In one embodiment, the manufacturing apparatus further comprises a suspension storage tank connected to the suspension manufacturing apparatus and used to store the aliphatic dicarboxylic acid suspension prepared by the suspension manufacturing apparatus, wherein the first salt-forming vessel is connected to the suspension storage tank; and / or wherein the manufacturing apparatus further comprises a primary nylon salt storage tank connected to the first salt-forming vessel and used to store the primary nylon salt solution prepared by the first salt-forming vessel, and wherein the second salt-forming vessel is connected to the primary nylon salt storage tank; and / or wherein the manufacturing apparatus further comprises a nylon salt storage tank connected to the second salt-forming vessel and used to store the nylon salt solution prepared by the second salt-forming vessel.In one embodiment, the suspension manufacturing apparatuses are provided in a number of one set or more than 2 sets, each set of suspension manufacturing apparatuses being connected to the suspension storage tank, respectively.In one embodiment, the suspension storage tank is provided with a circulation line used so that the aliphatic dicarboxylic acid suspension can circulate in the suspension storage tank; and / or wherein the primary nylon salt storage tank is provided with a circulation line used so that the primary nylon salt solution can circulate in the primary nylon salt storage tank; and / or wherein the first salt-forming vessel is provided with a circulation line used so that the primary nylon salt solution can circulate in the first salt-forming vessel.In one embodiment, the circulation line of the suspension storage tank is further provided with an on-line densitometer which is used to monitor and feed back the concentration change of the aliphatic dicarboxylic acid suspension in real time.In an embodiment, the circulation line of the first salt-forming boiler is provided with a first heat exchanger; and / or wherein the circulation line of the second salt-forming boiler is provided with a second heat exchanger.In one embodiment, the online near-infrared monitor is a contactless online near-infrared monitor.A method for producing a nylon salt solution using the apparatus for producing a nylon salt solution, comprising the steps of: introducing water into the production vessel through an inlet pipe and starting the high-speed shear pump so that the water circulates between the production vessel and the high-speed shear pump; supplying the aliphatic dicarboxylic acid through the supply device, wherein the aliphatic dicarboxylic acid enters the high-speed shear pump through the continuous supply device and is mixed therewith, and wherein the mixture circulates between the high-speed shear pump and the production vessel to produce the aliphatic dicarboxylic acid suspension; transferring the aliphatic dicarboxylic acid suspension into the first salt-forming vessel and adding the diamine through the first diamine supply pipe into the first salt-forming vessel to produce a primary nylon salt solution; Transferring the primary nylon salt solution into the second salt-forming vessel and adding the diamine through the second diamine feed tube and the third diamine feed tube into the second salt-forming vessel to prepare a nylon salt solution; wherein the feed amount of the diamine of the third diamine feed tube is regulated by the online near infrared monitor on the circulation line of the second salt-forming vessel.In one embodiment, the aliphatic dicarboxylic acid suspension prepared in the suspension preparation apparatus is transferred to the suspension storage tank, wherein the aliphatic dicarboxylic acid suspension in the suspension storage tank is then transferred to the first salt-forming vessel; and / or wherein the primary nylon salt solution prepared in the first salt-forming vessel is transferred to the primary nylon salt storage tank, and wherein the primary nylon salt solution in the primary nylon salt storage tank is transferred to the second salt-forming vessel; and / or wherein the nylon salt solution prepared in the second salt-forming vessel is transferred to the nylon salt storage tank.In one embodiment, the manufacturing method further satisfies at least one of the following conditions: (1) the concentration of the aliphatic dicarboxylic acid suspension is 35 wt %-52 wt %; (2) the molar ratio of the dicarboxylic acid to the dibasic amine in the primary nylon salt solution is 1.5:1-3:1, and the concentration is 40 wt %-62 wt %; (3) the concentration of the nylon salt solution is 50 wt %-65 wt %.The details of one or more embodiments of the present application are illustrated in the accompanying drawings and the following description. Other features, objects and advantages of the present application will become apparent from the specification, the accompanying drawings and the claims.BRIEF DESCRIPTION OF THE DRAWINGSIn order to more clearly explain the technical solution in the embodiments of the present application or in the conventional technology, the drawings to be used in the explanation of the embodiments or the conventional technology will be briefly presented below. Obviously, the accompanying drawings described below show only some embodiments of the present application. Those skilled in the art can obtain other accompanying drawings without any creative works based on these accompanying drawings. FIG. 1 is a schematic diagram showing the structure of an apparatus for producing a nylon salt solution according to the present application. FIG. 2 is a schematic diagram of an online, near-infrared non-contact monitor used by the present application.List of reference characters10 Suspension manufacturing apparatus 11 Supply apparatus 12 Continuous feeder apparatus 13 High-speed shear pump 14 Manufacturing vessel 15 Suspension storage tank 16 First salt-forming vessel 17 Primary nylon salt storage tank 18 Second salt-forming vessel 19 Nylon salt storage tank 131 Connection line 141 Inlet pipe 142 First nitrogen pipe 151 Suspension storage tank circulation line 152 Online densitometer 161 First diamine feed pipe 162 Second nitrogen pipe 163 First salt-forming vessel circulation line 164 First heat exchanger 171 Primary nylon salt storage tank circulation line 172 Third nitrogen pipe 181 Second diamine feed pipe 182 Third diamine feed pipe 183 Fourth nitrogen pipe 184 Second salt-forming vessel circulation line 185 Online near infrared monitor 186 Second heat exchanger 185a Light source 185b Transparent segment 185c Receiver 191 Circulation line of nylon salt storage tank 192 Fifth nitrogen pipeDETAILED DESCRIPTIONIn conjunction with accompanying drawings in the embodiment of the present application, the technical solutions in the embodiment of the present application will be clearly and fully explained below. Obviously, the explained exemplary embodiments do not represent all exemplary embodiments, but only a part of exemplary embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without any creative work should be considered to be within the scope of the present application.In conjunction with accompanying drawings in the embodiment of the present application, the technical solutions in the embodiment of the present application will be clearly and fully explained below. Obviously, the explained exemplary embodiments do not represent all exemplary embodiments, but only a part of exemplary embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without any creative work should be considered to be within the scope of the present application.In order to facilitate understanding of the present application, the present application will be explained in more detail below. However, it should be understood that the present application may be embodied in many different forms and is not limited to the embodiments or embodiments discussed herein. In contrast, these embodiments or embodiments are provided so that the disclosed content of the present application can be more thoroughly and fully understood.Unless otherwise stated, all technical and scientific terms used in the specification have the same meanings as those commonly understood by those skilled in the technical field of the present application. The terms used in the description of the present application are only for explaining the specific embodiments or embodiments, rather than limiting the present application. The term "and / or" as used herein optionally includes any of two or more related listed items, as well as any combination and all combinations of related listed items, any combination and all combinations including two of the related listed items, multiple of the related listed items, or a combination of all related listed items.The weighing with a weight loss balance, i.e., gravimetric weighing, is used in the prior art to solve the problem of accurately dosing the aliphatic dicarboxylic acid during delivery. The metered aliphatic dicarboxylic acid is continuously dispersed in a single continuous stirred tank reactor while the dibasic amine and water are supplied to obtain a salt solution of a certain concentration and ratio, which is then introduced into a temporary storage tank or used in another continuous stirred tank reactor while a second strand of diamines is introduced, and through the on-line pH feedback, a third strand of diamines is introduced to obtain a salt solution having a desired balanced molar ratio.However, on the one hand, the operation of the weight loss scale is divided into two modes: weight mode and volume mode, that is, when the liquid level of the material in the intermediate storage compartment of the weight loss scale is higher, a weight signal can be continuously output to the back end by the weight change, but when the liquid level becomes increasingly lower because the reduction of the material results in a variation of the weight loss signal until the liquid level is lowered to a lower level, the mode must be switched to the volume feed mode, that is, the frequency of the weight loss scale is fixed, and weight loss signal is set before the mode change. In the volume mode, the replenishment of the intermediate storage of the weight loss compensator is completed. Although the replenishment can be completed in a relatively short period of time before being switched back to the weight mode, the fixed frequency output volume mode results in large errors and variations in the measurement of the aliphatic dicarboxylic acid, adversely affecting the desired molar ratio. Moreover, the weight loss scale is generally used after accurately measuring a smaller amount of material per unit time, which results in that, as the polyamide production capacity increases, an appropriate weight loss scale cannot be selected or high expenses for the weight loss scale must be additionally invested while further enhancing the measurement error of the aliphatic dicarboxylic acid, since switching the weight loss scale with a larger volume between the weight loss mode and the volume mode takes a longer time, all of which is unfavourable for the desired molar ratio of the salt solution. On the other hand, the solid aliphatic dicarboxylic acid is directly mixed with dibasic amine and water to prepare the brine, and the oxygen gas enclosed therein tends to oxidize the brine, resulting in undesirable colors and impairing the quality of the product.Moreover, the molar ratio of the salt solution can be adjusted by controlling the rate and the flow rate of the subsequent introduction of the diamine. As in the prior art, the dibasic amine may be added and then introduced into a recirculation line, thereby including one or more pumps, and a temperature control device such as a coil pipe, a collet, or a device having a heat exchanger, a temperature measuring device, and a regulator may also be included. The temperature control device may control the temperature of the nylon brine in the recirculation loop to prevent the nylon brine from boiling or becoming a size. That is, this recirculation line must dilute and cool the highly concentrated nylon salts to pH-appropriate operating conditions and temperatures (25°C-30°C) for on-line pH measurement. This requires additional valves, piping, heat exchangers, pumps and other equipment and instruments which are cumbersome to process and require higher investments. Most importantly, the pH requirements of the working environment are more demanding, such as variations in detection temperature and concentration variations, involve large detection errors, which in turn interferes with the adjustment of diamine replenishment by pH feedback in the above patent. It must also be ignored that, due to the dilution of the salt solution, the addition of water which is not required leads to great fluctuations in the concentration of the salt solution, which likewise has an unfavorable effect on the subsequent polymerization.As shown in Fig. 1, in the present application, there is provided an apparatus for preparing a nylon salt solution, comprising a suspension preparing apparatus for preparing the aliphatic dicarboxylic acid suspension, a first salt-forming vessel 16 for preparing the primary nylon salt solution, and a second salt-forming vessel 18 for preparing the nylon salt solution, which are connected in sequence to each other.Further, the manufacturing apparatus may comprise a suspension storage tank 15 for storing the aliphatic dicarboxylic acid suspension, which is connected to each of the suspension manufacturing apparatus and the first salt-forming vessel 16; and / or the manufacturing apparatus may further comprise a primary nylon salt storage tank 17 for storing the primary nylon salt solution, which is connected to each of the first salt-forming vessel 16 and the second salt-forming vessel 18; and / or the manufacturing apparatus may further comprise a nylon salt storage tank 19 for storing the nylon salt solution, which is connected to the second salt-forming vessel 18.Here, the suspension manufacturing apparatus comprises a feeder 11, a continuous feeder 12, a high-speed shear pump 13, and a manufacturing vessel 14, wherein the manufacturing vessel 14 is further provided with an inlet pipe 141 for introducing water used for manufacturing the suspension into the manufacturing vessel 14.In the suspension manufacturing apparatus, the feeder 11, the continuous feeder 12, and the high-speed shear pump 13 are connected in sequence to each other, the feeder 11 is used for feeding the aliphatic dicarboxylic acid, and the continuous feeder 12 is used for feeding the aliphatic dicarboxylic acid to the high-speed shear pump 13. In addition, the high-speed shear pump 13 and the manufacturing vessel 14 are connected to each other through two connection pipes 131, so that the aliphatic dicarboxylic acid and water can circulate between the high-speed shear pump 13 and the manufacturing vessel 14 to form an aliphatic dicarboxylic acid suspension.In some embodiments, feeder 11 is equipped with a shaker to aid in rapidly terminating the feeding of the aliphatic dicarboxylic acid, with continuous feeder 12 selected from a screw feeder or a rotary feeder.When the suspension manufacturing apparatus of the present application is used for manufacturing the aliphatic dicarboxylic acid suspension, the high-speed shear pump 13 may generate a micro-negative pressure when the material circulates, for example, when the water and the mixture of water and the aliphatic dicarboxylic acid circulate, a micro-negative pressure may be generated to enable the high-speed shear pump 13 to form a vacuum suction state, so that the aliphatic dicarboxylic acid can be rapidly and completely dispersed in the suspension; at the same time, the high-speed shear pump 13 may enable the water to form a water mist. When the suspension manufacturing apparatus of the present application is used to manufacture the aliphatic dicarboxylic acid suspension, agglomeration between the aliphatic dicarboxylic acid powders can be avoided, and at the same time, the water can be quickly contacted with the aliphatic dicarboxylic acid powders to form a desirable and homogeneous dispersed solution.Moreover, in the present application, the aliphatic dicarboxylic acid is directly supplied by the weight measurement such as the aliphatic dicarboxylic acid is directly acquired in ton bags, and the weight error is usually within 0.5%, which is a small error, and the supply amount can be accurately measured.Therefore, the present application can effectively solve the problem of the feeding error caused by using the measurement of the weight loss balance in the related art and make more accurate the molar ratio between the dicarboxylic acid and the dibasic amine in the nylon salt solution obtained by subsequent salt formation.Moreover, the manufacturing vessel 14 may be further provided with a first nitrogen pipe 142 to introduce nitrogen into the manufacturing vessel 14, so that in manufacturing the aliphatic dicarboxylic acid suspension using the suspension manufacturing apparatus of the present application, the air contained in the aliphatic dicarboxylic acid may be displaced by nitrogen to reduce the risk of oxidation of the subsequent salt solution.Specifically, the suspension storage tank 15 is connected to the suspension manufacturing apparatus and is used to store the aliphatic dicarboxylic acid suspension prepared by the suspension manufacturing apparatus. It will be understood that the suspension storage tank 15 is connected to the suspension manufacturing apparatus in any manner, either directly to the manufacturing vessel 14 via a pipe or via a pipe to one of the connecting lines between the manufacturing vessel 14 and the high speed shear pump 13.In some embodiments, the suspension storage tank 15 is provided with a suspension storage tank circulation line 15 that is used so that the aliphatic dicarboxylic acid suspension can circulate in the suspension storage tank 15, whereby it can be ensured that the aliphatic dicarboxylic acid suspension is in a homogeneous state. The circulation line 151 of the suspension storage tank may include a circulation pump and a nozzle, and the aliphatic dicarboxylic acid suspension flows through the line by the circulation pump and is sprayed through the nozzle to mix with the aliphatic dicarboxylic acid suspension in the suspension storage tank 15 again.Further, the circulation line 151 of the suspension storage tank is further provided with an on-line densitometer 152 which is used to monitor and feed back the concentration change of the aliphatic dicarboxylic acid suspension in real time to increase the accuracy of the molar ratio between the dicarboxylic acid and the dibasic amine in the nylon salt solution obtained by subsequent salt formation.In some embodiments, the suspension manufacturing apparatuses are provided in a number of one set or more than 2 sets, each set of suspension manufacturing apparatuses being respectively connected to the suspension storage tank 15, which is designed specifically according to the demands on the production capacity to improve the efficiency.Specifically, when no suspension storage tank 15 is present, the first salt-forming vessel is directly connected to the suspension manufacturing apparatus, when a suspension storage tank 15 is present, the first salt-forming vessel 16 is connected to the suspension storage tank 15 and is capable of accommodating the aliphatic dicarboxylic acid suspension in the suspension manufacturing apparatus or the suspension storage tank 15, and the first salt-forming vessel 16 further includes a first diamine feed pipe 161 used to introduce the dibasic amine into the first salt-forming vessel 16, and the amount of the introduced dibasic amine can be controlled by a flow meter and a control valve. In this manner, the first salt-forming vessel 16 is enabled to produce the aliphatic dicarboxylic acid suspension and dibasic amine into a primary nylon salt solution. In some embodiments, the first salt-forming vessel 16 further includes a stirrer that helps the aliphatic dicarboxylic acid suspension and the dibasic amine to quickly complete the mixing and salt formation. It is understood that the first salt-forming vessel 16 is connected to the suspension storage tank 15 in any manner, either directly to the suspension storage tank 15 via a pipe or via a pipe to the circulation line 151 of the suspension storage tank. The first salt-forming vessel 16 is connected to the suspension manufacturing apparatus in any manner, either directly to the manufacturing vessel 14 via a pipe or via a pipe to one of the connecting lines between the manufacturing vessel 14 and the high-speed shear pump 13.In some embodiments, the first salt-forming vessel 16 may be further provided with a second nitrogen pipe 162 to introduce nitrogen into the first salt-forming vessel 16 so that, in preparing the primary nylon salt solution, the air entrained in the supplied dibasic amine may be displaced by nitrogen, thereby reducing the risk of oxidation of the salt solution.In some embodiments, the first salt-forming boiler 16 is provided with a first salt-forming boiler circulating line 163 used so that the primary nylon salt solution circulates in the first salt-forming boiler, the first salt-forming boiler circulating line 163 may be provided with a circulating pump, and the first salt-forming boiler circulating line 163 is further provided with a first heat exchanger 164 so that when the primary nylon salt solution circulates in the first salt-forming boiler circulating line 163, the temperature can be controlled by the first heat exchanger 164.Specifically, the primary nylon salt storage tank 17 is connected to the first salt-forming vessel 16 and is used to store the primary nylon salt solution prepared by the first salt-forming vessel 16. It will be understood that the primary nylon salt storage tank 17 is connected to the first salt-forming vessel 16 in any manner, either directly to the first salt-forming vessel 16 via a pipe or via a pipe to the first salt-forming vessel circulation line 163.In some embodiments, the primary nylon salt storage tank 17 is provided with a primary nylon salt storage tank circulation line 171 that is used so that the primary nylon salt solution circulates in the primary nylon salt storage tank 17, wherein the primary nylon salt storage tank circulation line 171 may include a circulation pump and a nozzle, and wherein the primary nylon salt solution flows through the line by the circulation pump and is sprayed through the nozzle to mix again with the primary nylon salt solution in the primary nylon salt storage tank 17.In some embodiments, the primary nylon salt storage tank 17 may be further provided with a third nitrogen pipe 172 to introduce nitrogen into the primary nylon salt storage tank 17, thereby reducing the risk of oxidation of the primary nylon salt solution.In some embodiments, the circulation line 171 of the primary nylon salt storage tank may also be provided with an on-line densitometer which is used to monitor and feed back the change in concentration of the primary nylon salt solution in real time.Specifically, when no primary nylon salt storage tank 17 is present, the second salt-forming vessel 18 is directly connected to the first salt-forming vessel 16, when a primary nylon salt storage tank 17 is present, the second salt-forming vessel 18 is connected to the primary nylon salt storage tank 17 and is capable of storing the primary nylon salt solution in the first salt-forming vessel 16 or the primary nylon salt storage tank 17, further, the second salt-forming vessel 18 further includes a second diamine feed pipe 181 and a third diamine feed pipe 182, each used to introduce the dibasic amine into the second salt-forming vessel 18, and the amount of the introduced dibasic amine in the second diamine feed pipe 181 and the third diamine feed pipe 182 can be controlled by a flow meter and a control valve. In this manner, the second salt-forming vessel 18 is enabled to produce the primary nylon salt solution and the dibasic amine into a nylon salt solution.In some embodiments, the second salt-forming vessel 18 may be further provided with a fourth nitrogen pipe 183 to introduce nitrogen into the second salt-forming vessel 18 so that the air entrained in the supplied dibasic amine may be displaced by nitrogen, thereby reducing the risk of oxidation of the salt solution.More specifically, the second salt-forming vessel 18 further includes a second salt-forming vessel circulating line 184, and an online near-infrared monitor 185 is further disposed on the second salt-forming vessel circulating line 184 to monitor the molar ratio of the dicarboxylic acid to the dibasic amine in the nylon salt solution and control the feed amount of the diamine in the third diamine feed pipe 182 in accordance with the monitoring result, so that a nylon salt solution having a more accurate molar ratio between the dicarboxylic acid and the dibasic amine can be obtained.The present application uses an on-line near infrared monitor 185 to monitor the molar ratio of dicarboxylic acid to dibasic amine in the nylon salt solution, thereby avoiding the concentration problem caused by the addition of additional water to dilute the sample, and at the same time, the on-line near infrared monitor 185 can make a stable measurement at a temperature of ±10° C. as compared to the pH test that is temperature sensitive, in order to avoid the imbalance in molar ratio caused by the temperature effect during the pH test.Moreover, the online near infrared monitor 185 is simple to install and operate and can feed back concurrent feedback of key information such as amine group / carboxyl group ratio in the nylon salt solution, salt solution concentration, etc., and unlike the online pH detector or refractometer, etc., the online near infrared monitor does not require additional installation of a bypass loop, a heat exchanger, and special piping with a control valve and a flow meter, which significantly reduces the cost of design and use.In some embodiments of the present application, the online near-infrared monitor 185 is further a contactless online near-infrared monitor as shown in FIG. 2, wherein it comprises a large point light source 185 aand a receiver 185 c, and wherein the circulation line 184 of the second salt-forming vessel is provided with a translucent segment 185 b, such that, in contrast to the test failure that may be caused by the contact online near-infrared monitor due to the bubbles in the nylon salt solution, the use of the contactless online near-infrared monitor has more accurate monitoring results, At the same time, the usage and maintenance costs of the non-contact online near-infrared monitor are lower compared to the contact online near-infrared monitor.In some embodiments, the second salt-forming vessel 18 further includes a stirrer that assists the primary nylon salt solution and the dibasic amine in rapidly completing the mixing and salt formation. It is understood that the second salt-forming vessel 18 is connected to the first salt-forming vessel 16 in any manner, either directly to the first salt-forming vessel 16 via a pipe or via a pipe to the circulation line 163 of the first salt-forming vessel, and the second salt-forming vessel 18 is connected to the primary nylon salt storage tank 17 in any manner, either directly to the primary nylon salt storage tank 17 via a pipe or via a pipe to the circulation line 171 of the primary nylon salt storage tank.In some embodiments, the circulation line 184 of the second salt-forming boiler may be provided with a circulation pump, further, the circulation line 184 of the second salt-forming boiler is further provided with a second heat exchanger 186, so that when the nylon salt solution circulates in the circulation line 184 of the second salt-forming boiler, the temperature may be controlled by the second heat exchanger 186.Specifically, the nylon salt storage tank 19 is connected to the second salt-forming vessel 18 and is used to store the nylon salt solution prepared by the second salt-forming vessel 18. It will be understood that the nylon salt storage tank 19 is connected to the second salt-forming vessel 18 in any manner, either directly to the second salt-forming vessel 18 via a pipe or via a pipe to the circulation line 184 of the second salt-forming vessel.In some embodiments, the nylon salt storage tank 19 is provided with a nylon salt storage tank circulation line 191 that is used so that the nylon salt solution circulates in the nylon salt storage tank 19. The circulation line 191 of the nylon salt storage tank may include a circulation pump and a nozzle, and the nylon salt solution flows through the line by the circulation pump and is sprayed through the nozzle to mix with the nylon salt solution in the nylon salt storage tank 19 again.In some embodiments, the nylon salt storage tank 19 may be further provided with a fifth nitrogen pipe 192 for introducing nitrogen into the nylon salt storage tank 19, thereby reducing the risk of oxidation of the nylon salt solution in the nylon salt storage tank 19.The present application further provides a method for preparing a nylon salt solution using the manufacturing apparatus, comprising the following steps:introducing water into the manufacturing vessel 14 through an inlet pipe 141 and starting the high-speed shear pump 13 so that the water circulates between the manufacturing vessel 14 and the high-speed shear pump 13 to enable the high-speed shear pump 13 to form a micro-negative pressure, then supplying the aliphatic dicarboxylic acid through the supplying device 11, the aliphatic dicarboxylic acid entering the high-speed shear pump 13 through the continuous supplying device 12 and being mixed therewith, and the mixture circulates between the high-speed shear pump 13 and the manufacturing vessel 14 to produce the aliphatic dicarboxylic acid suspension, and transferring the aliphatic dicarboxylic acid suspension into the suspension storage tank 15 or directly into the first salt-forming vessel 16.In some embodiments, after the aliphatic dicarboxylic acid feed is completed, the continuous feeder 12 is shut down and circulation between the high speed shear pump 13 and the manufacturing vessel 14 is continued to obtain a more homogeneous aliphatic dicarboxylic acid suspension.In some embodiments, the aliphatic dicarboxylic acid suspension in the suspension storage tank 15 circulates through the suspension storage tank circulation line 151 to ensure that the aliphatic dicarboxylic acid suspension is in a homogeneous state, and an on-line densitometer 152 is used for real-time monitoring and feedback about the change in concentration of the aliphatic dicarboxylic acid suspension during circulation to facilitate accurate regulation of dosage in the preparation of the primary nylon salt.In some embodiments, the concentration of the aliphatic dicarboxylic acid suspension is 35 wt%-52 wt%, and using the manufacturing method of the present application, the concentration variation is less than 0.1 wt%, or even less than 0.05 wt%.In some embodiments, the aliphatic dicarboxylic acid is selected from C4-C12dicarboxylic acids such as butanedioic acid, glutanedioic acid, adipic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, sebacic acid, lauric acid, etc.When the aliphatic dicarboxylic acid suspension is transferred to the first salt-forming vessel 16, the dibasic amine is added to the first salt-forming vessel 16 through the first diamine feed pipe 161 to prepare a primary nylon salt solution. In some embodiments, the concentration of the aliphatic dicarboxylic acid suspension is monitored and fed back in real time by the on-line densitometer 152 and the feed rate is controlled according to the need for the molar ratio of the dicarboxylic acid and diamine in the primary nylon salt solution, and in some embodiments, the molar ratio of the dicarboxylic acid to the dibasic amine in the primary nylon salt solution is 1.5:1-3:1, the concentration is 40% by weight, 62% by weight, and in some embodiments, the molar ratio of the dicarboxylic acid to the dibasic amine is 2:1-2.5:1, the concentration is 50% by weight, 60% by weight.In some embodiments, the primary nylon salt solution in the first salt-forming vessel 16 circulates through the first salt-forming vessel circulation line 163, and the temperature is controlled to a value between 50°C and 80°C by the first heat exchanger 164.Then, the primary nylon salt solution prepared in the first salt-forming vessel 16 is transferred to the primary nylon salt storage tank 17 or directly transferred to the second salt-forming vessel 18, when the primary nylon salt solution is transferred to the second salt-forming vessel 18, the dibasic amine is added to the second salt-forming vessel 18 through the second diamine feed pipe 181 and the third diamine feed pipe 182 to prepare a nylon salt solution, the nylon salt solution directly enters the polyamide production process, or the nylon salt solution is transferred to the nylon salt storage tank 19.In some embodiments, the total amount of dibasic amine feed in the second diamine feed tube 181 and third diamine feed tube 182 is controlled according to the concentration of the desired final nylon salt solution and the molar ratio of dicarboxylic acid to dibasic amine. At this time, the feed amount of the diamine of the third diamine feed pipe 182 is regulated by the online near infrared monitor 185 at the circulation line 184 of the second salt-forming vessel, and in some embodiments, the concentration of the nylon salt solution is 50% by weight, 65% by weight, in some embodiments, the nylon salt solution in the second salt-forming vessel 18 circulates through the circulation line 184 of the second salt-forming vessel, and the temperature is controlled to a value between 60° C. and 110° C. by the second heat exchanger 186,In some embodiments, the dibasic amine is selected from C4-C12 diamines such as 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, lauryl diamine, etc.The apparatus and method for preparing a nylon salt solution will be described in detail below in connection with specific embodiments.Embodiment 1The adipic acid in ton bags is raised to the open bag position by means of an electric hoist of the feeder 11. At the same time, 1500 kg of pure water is injected into the manufacturing vessel 14, and the high-speed shear pump 13 is turned on, so that the pure water in the manufacturing vessel 14 starts to circulate between the high-speed shear pump 13 and the treatment vessel 14. When the cycle described above is made, the bags of adipic acid are opened and the adipic acid is fed into the high-speed shear pump 13 through the continuous feeder 12, the deposition of the adipic acid can be stopped in 6 minutes, and the adipic acid is mixed with water, and the mixture circulates between the high-speed shear pump 13 and the manufacturing vessel 14 to obtain an adipic acid suspension stored in the suspension storage tank 15, and a concentration of 39.9% by weight is fed back through the on-line densitometer 152.1577 kg of adipic acid suspension having a concentration of 39.9% by weight is metered and transferred to the first salt-forming vessel 16, 200 kg of hexamethylenediamine is metered and introduced into the first salt-forming vessel 16 via the first diamine feed pipe 161, the primary nylon salt solution is prepared in the first salt-forming vessel 16, and the temperature of the primary nylon salt solution is controlled to 65° C. via the first heat exchanger 164, and the concentration is 52.5% by weight. By off-line sampling and testing, the primary nylon salt solution has an amine-acid ratio of 1:2.49, which is converted to adipic acid with a measurement error of 0.39%.Comparative Example 11000 kg of adipic acid is metered by a weight loss balance while the weight loss signal is fed back to 317.8 kg of A hexamethylenediamine and 1192 kg of water, and the required hexamethylenediamine and water are metered in the same ratio to obtain the primary nylon salt solution having an amine-acid ratio of 1:2.5 and a concentration of 52.5 wt%. The 1000 kg of adipic acid is supplied by refilling three times, i.e. the volume working mode is used three times. The temperature of the primary nylon salt solution is controlled to 65°C by a heat exchanger, and off-line sampling and testing the primary nylon salt solution has an amine-acid ratio of 1:2.45 which is converted to adipic acid with a measurement error of 2%.It is apparent from Working Example 1 and Comparative Example 1 that the preparation of the primary nylon salt solution using the adipic acid suspension prepared by the manufacturing apparatus and the manufacturing method of the present application results in an amine-acid ratio closer to the target value, i.e., higher precision of adipic acid dosage.Embodiment 2By continuously controlling that the primary nylon salt solution having an amine-acid ratio of 1:2.5 and a concentration of 55 wt % is fed into the second salt-forming vessel 18 at a flow rate of 1000 kg / hr, the hexamethylenediamine is fed into the second diamine feed pipe 181 at a flow rate of 122.8 kg / hr, and simultaneously pure water is fed at a flow rate of 47 kg / hr, a nylon salt solution having an amine-acid ratio of 1:1 and a concentration of 60 wt % is prepared in the second salt-forming vessel 18. At this time, the addition of hexamethylenediamine in the third diamine feed tube 182 is controlled by the feedback of the online, near infrared non-contact monitor to obtain a nylon salt solution having an amine-acid ratio of 1:1 and a concentration of 60% by weight. After the start of the preparation, offline sampling is performed at one hour intervals, and the taken nylon salt solution is diluted to 10 wt% and cooled to 25 °C to test the amine-acid ratio for comparative monitoring; the results are shown in Table 1.Comparative Example 2Comparative Example 2 differs from Embodiment 2 only in that hexamethylenediamine in the third diamine feed pipe is controlled by the bypass line arranged with a flow meter and a control valve to receive the brine of 50 kg / hr while pure water is added in the same ratio to dilute the solution from 60 wt % to about 10 wt %, thereafter the temperature is controlled to 25±1° C. by the heat exchanger. After this heat exchanger, an online pH tester is installed to monitor the pH of the diluted and cooled brine and adjust the flow rate of hexamethylenediamine in the third diamine feed pipe according to the laboratory model feedback. After the start of the preparation, offline sampling is performed at one hour intervals and the sampled brine is diluted to 10 wt% and cooled to 25 °C to test the amine-acid ratio for comparative monitoring; the results are listed in Table 1. Table 1 Table 1Embodiment 21.00091.00041.00021.00041.00011.0003Comparative Example 21.00161.00151.00111.00100.99911.0011From Table 1, it can be seen that the present application uses an on-line near infrared monitor to adjust the hexamethylenediamine in the third diamine feed tube so that the variation in the expected amine-acid ratio is relatively small. The pH on-line monitoring is subject primarily to the effects of variations in dilution concentration, detection temperature and other higher force, and the data is subject to large variations and the variation from amine-acid ratio is not conducive to subsequent polymerization, primarily for end group control of the finished product, which greatly affects downstream applications such as the field of the spinning mill.As compared with the prior art, the present application has advantages as follows: 1. in the present application, the aliphatic dicarboxylic acid is directly supplied by the weight measurement and the supply amount can be accurately measured; 2. when the suspension manufacturing apparatus of the present application is used for manufacturing the aliphatic dicarboxylic acid suspension, the high-speed shear pump can generate a micro-negative pressure as the material circulates to enable the high-speed shear pump to form a vacuum suction state, so that the aliphatic dicarboxylic acid can be rapidly and completely dispersed in the suspension; at the same time, the high-speed shear pump can enable the water to form a water mist; When the suspension manufacturing apparatus of the present application is used to manufacture the aliphatic dicarboxylic acid suspension, agglomeration between the aliphatic dicarboxylic acid powders can be avoided, and at the same time, the water can be quickly contacted with the aliphatic dicarboxylic acid powders to form a desirable and homogeneous dispersed solution. 3. the present application uses an on-line near-infrared monitor to monitor the molar ratio of the dicarboxylic acid to the dibasic amine in the nylon salt solution, thereby avoiding the concentration problem caused by the addition of additional water to dilute the sample, simultaneously the on-line near-infrared monitor can perform stable measurement at a temperature of ±10° C. Therefore, the molar ratio of the dicarboxylic acid to the dibasic amine in the nylon salt solution obtained by using the production apparatus and the production method is more accurate.The respective technical features of the above embodiments can be combined arbitrarily. In order to simplify the explanation, not all possible combinations of the respective technical features are explained in the above embodiments, but the combinations of the technical features should be considered to be covered by the scope of the description in the case of no conflicts.The above embodiments are only some embodiments of the present application, and the explanations are relatively specific and detailed, but should not be construed as limitations on the scope of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the concept of the present application. The improvements and modifications are also intended to be considered to be within the scope of the present application. Therefore, the scope of the present application should be defined by the claims.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedCN 202410624089.2

[0001]

Claims

An apparatus for producing a nylon salt solution, characterized by comprising a suspension manufacturing apparatus comprising a feeding apparatus, a continuous feeding apparatus, a high-speed shear pump, and an inlet pipe-equipped manufacturing vessel connected in sequence to each other, wherein the high-speed shear pump and the manufacturing vessel establish a circulating connection with each other through two connection pipes, and wherein the feeding apparatus is used for feeding the aliphatic dicarboxylic acid, and wherein the continuous feeding apparatus is used for feeding the aliphatic dicarboxylic acid to the high-speed shear pump, and wherein the aliphatic dicarboxylic acid and water can circulate between the high-speed shear pump and the manufacturing vessel to form an aliphatic dicarboxylic acid suspension; a first salt-forming vessel connected to the suspension manufacturing apparatus, the first salt-forming vessel having a first diamine feed tube for preparing the aliphatic dicarboxylic acid suspension and the dibasic amine into a primary nylon salt solution; a second salt-forming vessel connected to the first salt-forming vessel, the second salt-forming vessel having a second diamine feed pipe and a third diamine feed pipe for preparing the primary nylon salt solution and the dibasic amine into a nylon salt solution, the second salt-forming vessel further having a circulation line, and an online near infrared monitor is further disposed on the circulation line of the second salt-forming vessel for monitoring the molar ratio of the aliphatic dicarboxylic acid to the dibasic amine in the nylon salt solution and controlling the feed amount of the diamine in the third diamine feed pipe in accordance with the monitoring result.The apparatus for producing a nylon salt solution according to claim 1, wherein the production apparatus further comprises a suspension storage tank connected to the suspension production apparatus and used to store the aliphatic dicarboxylic acid suspension prepared by the suspension production apparatus, wherein the first salt-forming vessel is connected to the suspension storage tank; and / or wherein the production apparatus further comprises a primary nylon salt storage tank connected to the first salt-forming vessel and used to store the primary nylon salt solution prepared by the first salt-forming vessel, and wherein the second salt-forming vessel is connected to the primary nylon salt storage tank; and / or wherein the production apparatus further comprises a nylon salt storage tank connected to the second salt-forming vessel and used to store the nylon salt solution prepared by the second salt-forming vessel.The apparatus for producing a nylon salt solution according to claim 2, wherein the suspension manufacturing apparatuses are provided in a number of one set or more than 2 sets, and each set of suspension manufacturing apparatuses is connected to the suspension storage tank, respectively.The apparatus for producing a nylon salt solution according to claim 2, wherein the suspension storage tank is provided with a circulation line of the suspension storage tank used so that the aliphatic dicarboxylic acid suspension can circulate in the suspension storage tank; and / or wherein the primary nylon salt storage tank is provided with a circulation line of the primary nylon salt storage tank used so that the primary nylon salt solution circulates in the primary nylon salt storage tank; and / or wherein the first salt-forming vessel is provided with a circulation line of the first salt-forming vessel used so that the primary nylon salt solution circulates in the first salt-forming vessel.The apparatus for producing a nylon salt solution according to claim 4, wherein the circulation line of the suspension storage tank is further provided with an on-line densitometer used to monitor and feed back the concentration change of the aliphatic dicarboxylic acid suspension in real time.The apparatus for producing a nylon salt solution according to claim 4, characterized in that a first heat exchanger is disposed on the circulation line of the first salt-forming vessel; and / or a second heat exchanger is disposed on the circulation line of the second salt-forming vessel.The apparatus for producing a nylon salt solution according to claim 1, wherein the online near-infrared monitor is an online near-infrared contactless monitor.

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