TW201501794A - Systems and methods for cleaning or maintaining venting system of agitated autoclave - Google Patents

Abstract

Agitated autoclave venting systems and related methods of cleaning and/or maintaining venting systems of the same are disclosed. The method can include introducing a polymerizable composition including a polyamide salt into an agitated autoclave having an agitator and a venting valve associated with a venting system, venting the agitated autoclave through a first flow path, and during at least a portion of the venting step, injecting a fluid through a second flow path into the venting valve. The venting system can include a vent line operably connected with the venting valve of the autoclave for venting the autoclave through the first flow path of the venting valve. The venting system can also include an injector associated with the venting valve and configured to inject a fluid into the venting valve through a second flow path.

Description

System and method for cleaning or maintaining an agitated autoclave exhaust system

This invention relates to a method and apparatus for cleaning and/or maintaining an exhaust system of an agitated autoclave during the preparation of a polyamide polymer. The invention also relates to an agitated autoclave.

Complex chemical engineering methods can be used on a relatively large scale to synthesize polyamine polymers, such as nylon 6,6. Such chemical engineering methods may include, for example, a salt paste step in which a polyamine (e.g., nylon 6,6) salt solution is prepared, an evaporation step in which some water from a salt solution is evaporated, and an autoclave method (in which salt is used) The solution is placed under heat and pressure for polymerization and the extrusion/cutting step in which the final polymerization starting material is substantially formed. Other steps that are generally understood by those skilled in the art may also be included.

Such chemical engineering processes can be batch or continuous, and in the case of autoclaves, there are a variety of available autoclaves with acceptable results. Regardless of the autoclave selected for use, the venting valve and line blockage/clogging during the venting of the autoclave can be difficult to resolve. This can be especially difficult to solve when manufacturing large batches. Accordingly, the discovery and utilization of various techniques for maintaining exhaust valves and lines during polymer manufacturing processes will be an advancement in the art.

The invention herein relates to the preparation of polymers, in particular such as nylon Method and apparatus for cleaning and/or maintaining an exhaust system of an agitated autoclave during the 6,6 polyamidamide polymer. The method includes introducing a polymerizable composition comprising a polyamine salt into an agitated autoclave having an agitator and an exhaust valve associated with the exhaust system, venting the agitated autoclave via the first flow path and During at least a portion of the venting step, fluid is injected into the vent valve via the second flow path. The exhaust system can include an exhaust line operatively coupled to the exhaust valve of the autoclave to vent the autoclave via the first flow path of the exhaust valve. The exhaust system may also include a syringe associated with the exhaust valve and configured to inject fluid into the exhaust valve via the second flow path. In one aspect, an exhaust system including an exhaust valve may have some pre-existing deposits in the exhaust line or valve. In such cases, the above methods can be used to clean and remove all or a portion of such deposits and to prevent or reduce the formation of other new deposits.

In another embodiment, an agitated autoclave and an exhaust system are provided. The agitated autoclave and exhaust system can include an agitated autoclave including an agitator and an exhaust valve configured to vent the agitated autoclave along a first flow path; associated with the exhaust valve and grouped a syringe that injects fluid into the vent valve along a second flow path; and a syringe module adapted to control fluid injected from the injector into the vent valve.

Other features and advantages of the present invention will be apparent from the following embodiments, which illustrate the features of the invention.

10‧‧‧Agitated autoclave

18‧‧‧A new bar

20‧‧‧ autoclave container

22‧‧‧ container wall

24‧‧‧heating components

26‧‧‧heating components

28‧‧‧Squeezing valve opening

30‧‧‧Agitator/Auger

32‧‧‧ flow pattern

44‧‧‧Inlet valve

46‧‧‧Exhaust valve

48‧‧‧Exhaust line

50‧‧‧ Controller

60‧‧‧heating module

70‧‧‧ Pressure Control Module

80‧‧‧Exhaust module

90‧‧‧Syringe module

92‧‧‧Syringe

100‧‧‧Stirring autoclave

110‧‧‧Exhaust valve

120‧‧‧ scrubber

130‧‧‧ pump

140‧‧‧Manual valve

150‧‧‧Blocking valve

160‧‧‧Restricted holes

170‧‧‧ check valve

180‧‧‧Manual valve

190‧‧‧ fluid injector

1 is an illustration depicting the relative curves of pressure, heat, and exhaust relative to each other during a batch cycle in accordance with an embodiment of the present invention; and FIG. 2A is a schematic illustration of an agitated autoclave useful in accordance with an embodiment of the present invention. 2B is a schematic cross-sectional view of an agitated autoclave that can be used in place of an agitated autoclave in accordance with an embodiment of the present invention; and FIG. 3 shows an implementation of an agitated autoclave having an exhaust system including a fluid injector. A general flow chart of an example.

It is to be noted that the drawings are only illustrative of the embodiments of the invention and are not intended to limit the scope of the invention.

While the invention is described in the following detailed description, it will be understood by those skilled in the art

Accordingly, the following embodiments are set forth without any loss of generality to any claimed invention and without imposing limitations to any claimed invention. Before the present invention is described in more detail, it is understood that the invention is not limited to the specific embodiments described, as these embodiments may vary. It is also understood that the terms used herein are for the purpose of describing the particular embodiments and are not intended to limit the scope of the invention, as the scope of the invention is limited only by the scope of the appended claims. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

The singular forms "a", "the", and "the" Thus, for example, reference to "exhaust line" includes a plurality of exhaust lines.

The term "polymerizable composition" or "polymerizable solution" means added to an agitated autoclave according to an example of the present invention, and can be formed when the polymerizable composition is processed in an autoclave under a certain heat and pressure profile. A solution of a polymer that is extruded or otherwise collected for other uses. However, it is noted that when the polymerizable composition begins to polymerize in the autoclave, the solution will begin to thicken into a polymer. Therefore, it is difficult to describe when it is no longer a polymerizable composition compared to a thickened polymer. Thus, for convenience, the term "polymerizable solution" may be used herein to describe a composition in an autoclave, regardless of its state of polymerization. In addition, the term "solution" is not intended to describe each component of the composition, as some materials Or the additive may actually be dispersed in a liquid, such as titanium dioxide. The term "solution" is used for convenience only as some material that will be in solution at the beginning.

The term "polyammonium salt" refers to a salt included in a polymerizable composition, as appropriate, along with other additives, which provides a substantially polymerizable material for forming a polyamide polymer. If the polyamine polymer is, for example, nylon 6,6, a salt can be prepared by a condensation reaction between adipic acid and hexamethylenediamine. Other additives may also be included in the polyamine solution, introduced prior to the agitated autoclave or introduced directly into the agitated autoclave. For example, titanium dioxide may optionally be introduced directly into the autoclave, while other additives, such as catalysts, defoamers or the like, may be more suitable for polymerizable salts prior to introduction of the polymerizable composition into the agitated autoclave. Doping, although the order or even the presence of such or other additives is not desired.

The term "cycle" refers to the stage of a batch polymerization process in a stirred autoclave that is primarily defined by a pressure curve. The first cycle (Cycle 1) occurs at the beginning of the batch process when the pressure is increased from a lower pressure to a relatively higher pressure. The second cycle (Cycle 2) occurs when the relatively high pressure is maintained for a period of time (usually assisted by pressure exhaust). The third cycle (Cycle 3) occurs when the relatively high pressure decreases back to a lower pressure (which may be a lower pressure than the initial low pressure, as the case may be). The fourth cycle (Cycle 4) occurs while maintaining (vacuum) low pressure for a period of time. A fifth cycle (Cycle 5) occurs when the polymer produced in the autoclave is extruded by a pressurized self-stirring autoclave vessel.

The term "relatively higher pressure" refers to the pressure within a batch process wherein the pressure is substantially at its highest level. Therefore, the pressure is "high" relative to other pressure levels during the batch cycle process. For example, the initial low pressure can be increased to a relatively high pressure during cycle 2. Consider the pressure curve of the 5 cycle batch, when the pressure is about the highest pressure of the batch curve, the "relatively higher pressure" has been reached. In some examples shown herein, a relatively high pressure of about 230 to 300 psi is shown, although other pressure profiles may provide relatively high pressure outside of this range.

The term "stirring" refers to the state of the agitator when the agitator is operated at a level sufficient to allow at least some of the polymerizable composition or resulting polymer to mix. In one example, the agitator can be an auger that rotates in the agitated autoclave at up to 100 RPM (but can vary, for example, from 5 RPM to 90 RPM).

When the term "base" or "valve" is used to describe a valve, particularly a component of an exhaust valve, refers to a surface, generally a fixed surface on which the second moving portion of the valve is placed or which is relative to It is pressed. For the purposes of the present invention, valves known in the art as having a valve seat include ball valves, butterfly valves, check valves, throttle valves, diaphragm valves, gate valves, needle valves, pinch valves, and plug valves. And other valves known in the art or that can be readily used or modified for use in an exhaust system in accordance with examples of the present invention.

In the present invention, "comprises/comprising", "containing" and "having" and the like may have the meaning attributed to them in the U.S. Patent Law and may mean "including" Include/including) and the like, and is generally interpreted as an open term. The term "consisting of" is a closed term and includes only devices, methods, compositions, components, structures, steps or the like that are specifically listed and in accordance with U.S. Patent. When "consisting essentially of or consists essentially" or the like is applied to the device, method, composition, component, structure, step or the like of the present invention, it is referred to herein. The elements of the elements disclosed are disclosed, but may contain other structural families, composition components, method steps, and the like. However, such other devices, methods, compositions, components, structures, procedures, or the like do not significantly affect the basic and novel characteristics of the device, composition, method, etc. (as compared to the corresponding devices disclosed herein) , characteristics of compositions, methods, etc.). In further detail, when "consisting essentially of or consists essentially" or the like is applied to the apparatus, method, composition, composition, structure, step or the like of the present invention. Has the meaning attributed to the US patent law and the term is open, allowing the existence of more than the meaning as long as the meaning is The present or novel features are not altered by the existence of the meaning, but do not include prior art embodiments. When using open terminology such as "contains" or "includes", it should be understood that the language "consisting mainly of" and the language "consisting of" should be directly supported (as expressly stated).

Phrases such as "suitable to provide", "sufficient to cause" or "sufficient to yield" or the like refer to time and temperature in the context of a synthetic method. The solvent, reactant concentration, and similar reaction conditions are varied within the skill of the experimenter to provide a suitable amount or yield of the reaction product. The desired reaction product need not be the sole reaction product or the starting material need not be completely consumed, with the proviso that the desired reaction product can be isolated or used for other purposes.

It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed in the form of ranges herein. It is to be understood that the scope of the invention is to be construed as a The range, such as each value and sub-range, includes "about "x" to about "y"". For purposes of illustration, a concentration range of "about 0.1% to about 5%" should be interpreted to include not only the stated concentrations of from about 0.1% to about 5% by weight, but also a single concentration within a specified range (eg, 1%, 2%, 3%, and 4%) and sub-ranges (eg, 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%). In one embodiment, the term "about" can include conventional rounding based on a significant number of values. In addition, the phrase "about "x" to "y"" includes "about "x" to about "y"".

When the term "about" as used herein is an index value or range, the value or range is allowed to vary to some extent, such as within 10% of the stated threshold value of the stated value or range, or in one aspect, Within 5%.

In the event that the features or aspects of the invention are described in the context of a list or a Markush group, those skilled in the art will recognize that the invention also has any individual member of the Marcuse group or The member subgroup form is described. For example, if X is described In the group selected from the group consisting of bromine, chlorine and iodine, the claim that X is bromine and the claim that X is bromine and chlorine (as listed separately) are fully described. For example, where the features or aspects of the present invention are described in the form of a list, those skilled in the art will recognize that the present invention is therefore in the form of a list or any individual member or member subgroup of the Marcuse group. Any combination of the descriptions. Thus, if X is described as being selected from the group consisting of bromine, chlorine, and iodine, and Y is described as being selected from the group consisting of methyl, ethyl, and propyl, then the claim that X is bromine and Y is methyl is fully described and supported. .

Unless otherwise stated, all compositions % are given as % by weight as used herein. When referring to a component solution, percentages refer to the weight percent of the composition including the solvent (eg, water), unless otherwise indicated.

Unless otherwise stated, all polymer molecular weights (Mw) are weight average molecular weights as used herein.

It will be apparent to those skilled in the art after reading this disclosure that each of the individual embodiments described and illustrated herein have discrete components and features that can be readily combined with any of the other embodiments. The features are separated or combined without departing from the scope or spirit of the invention. Any of the methods described can be performed in the sequence of events or in any other order that is logically possible.

It should be noted in the present invention that when describing an agitated autoclave or method, individual or separate descriptions are considered to be applicable to each other, whether or not explicitly recited in the context of particular examples or embodiments. For example, when discussing a particular agitator or auger itself, method embodiments are also essentially included in the discussion, and vice versa.

In view of the above, there are several different types of autoclaves for preparing polymeric feedstocks. One particular type of autoclave is an agitated autoclave that includes a stirring member, such as a auger, to aid in the polymerization process. The agitator or auger achieves the autoclave container by providing salt flow mixing and continuous mixing (no stratification effect) of the contents in the autoclave, controlling heat transfer, reducing vortex, stretching the polymer through the autoclave Higher yield, provide viscometer for measurement Relative viscosity (RV), etc. to help the method.

Before discussing some of the methods and systems of the present invention, it will be appreciated that a general curve of pressure, temperature, and venting of an autoclave in one embodiment of a five cycle process for preparing a polymer may be suitable. Figure 1 shows the general curve of pressure, temperature and exhaust over a five cycle process. In particular, the first cycle (Cycle 1) occurs at the beginning of the batch process when the pressure is increased from a lower pressure to a relatively higher pressure. The second cycle (Cycle 2) occurs when the relatively high pressure is maintained for a period of time. Thus, as the temperature rises, thereby inherently increasing the pressure, the pressure can be substantially maintained at a relatively high pressure by venting the autoclave (as indicated by Cycle 2 in the exhaust curve of Figure 1). A third cycle (Cycle 3) occurs when the relatively high pressure is reduced to a pressure that is even lower than the initially presented pressure, which may be reduced to vacuum in some instances for the fourth cycle (Cycle 4) Degree, in this example, the fourth cycle occurs when the lower (vacuum) pressure is maintained for a period of time. The fifth cycle (Cycle 5) occurs when the pressure is again increased for the purpose of extruding the polymer from the agitated autoclave vessel.

A more detailed description of an embodiment of a five cycle process for preparing a polymer, such as that shown in Figure 1, is described below. In preparing the starting polymer preparation process, the salt solution can be introduced into the agitated autoclave from the evaporator at a concentration of 80% to 84% by weight. During the first cycle (Cycle 1), the pressure can be increased to a specified level by introducing the polymerizable composition into the container, by a pressure source, by heat, or the like. The pressure level in this system can range from a vacuum pressure to about 300 psi. Typically, during most or all of Cycle 1, there is little to no venting of the autoclave, as one goal is to increase the pressure of the vessel.

In the second cycle (Cycle 2), the pressure remains substantially constant at relatively high pressures, such as 230 psi to 300 psi. As the autoclave temperature increases, the pressure is maintained substantially constant at relatively high pressures by venting the autoclave (including the maximum venting in some embodiments). In this particular example, the maximum exhaust gas is displayed at 2000 kg/h (exhaust gas ranges from 0 to 2000 kg/h), but it should be noted that the maximum exhaust gas can be between 1500 and 2500 The level in the range of kg/h depends, for example, on the local system, but exhaust levels outside this range can also be used. During autoclave venting, the venting valve may become viscous or clogged/blocked frequently due to monomer, oligomer or polymer residue deposited on the vent valve. Such deposits can occur during a single batch cycle or after multiple batch cycles. Such deposits may inhibit or completely eliminate the exhaust gas control of the autoclave, which in turn may result in loss or reduction in control of the autoclave pressure. In addition to causing problems with the exhaust valve, deposits of such residues may also form in the exhaust line, which may cause blockage/clogging of such lines.

During the cycle of exhaust gas, a syringe can be used with the autoclave to inject a fluid, such as water, into the exhaust valve of the autoclave to reduce and suppress monomer, oligomers in the exhaust valve itself or in the exhaust line. Or deposition of a polymer. At the exhaust valve itself, and not only in the exhaust line just downstream of the valve, the injection inhibits and/or removes the deposit itself and the accumulation of deposits in the exhaust line. Injection in the exhaust line just downstream of the exhaust valve may act to prevent deposits from forming in the exhaust line itself, but may not prevent deposit formation in the valve or valve region. Deposits in or near the valve can cause the valve to stick or become sealed, preventing the valve from functioning properly, which in turn results in the need to shut down the reactor. Typically, the injector is configured to enter the exhaust valve at a different location than the typical exhaust fluid flow path that the valve is used to vent. In one example, the second fluid flow path can be introduced into the valve by drilling or otherwise providing a port into the valve near the valve seat or valve seat such that the valve can be injected with water, steam or another fluid Keep the valve clean and free from depositing monomers, oligomers or polymers.

Typically, the second fluid flow path is located adjacent to the venting valve of the valve seat, typically downstream of the valve seat, on the low pressure side. In one example, the valve is modified to inject water or other fluid on the low pressure side of the right side of the valve outlet. By injecting water (or other fluid) at this location, the water provides a more water-rich environment in the exhaust line that helps prevent deposit build-up and in turn helps keep the line clean. In addition, the valve that maintains the pressure in the reactor is also free of deposits (monomers, oligomers, polymers, etc.) by injecting water on the low pressure side in close proximity to the valve. When through the injection end This condition can occur when the water of the mouth comes into contact with the steam and the hot surrounding surface of the autoclave, that is, the valve itself and the tube are flashed. This provides little to no chance of any deposit adhering to the valve surface. Since the precipitate tends to form in the low pressure region, the deposit can be minimized by injection on the low pressure side of the valve seat because the flash water does not allow such deposits to settle in the valve. In the absence of this injection line, there is a tendency for deposit build-up at the valve outlet and can result in irregularities in the valve that regulates the pressure in the autoclave, for example the valve will start to open more and travel faster (fast up and down Move) to adjust the pressure. In addition, the movement of the valve sometimes allows for displacement of the deposit, resulting in a more abrupt movement of the valve, resulting in more monomer, oligomers and/or polymer being lifted from the melt pool through the vent line. This problem can be alleviated by injecting water, steam or other suitable fluid at the valve seat (usually on the downstream, low pressure side).

In more detail, by way of an example, water injection can have a pressure of about 100 psi at the injection point. Thus, water injection can be stopped when the autoclave pressure is less than 100 psia to prevent any water from the water injection from returning to the autoclave and creating a cold spot in the polymer pool, which in turn causes casting problems when the polymer is extruded from the autoclave. Therefore, we can manipulate the pressure of the injected water and continue to inject water at a pressure below 100 psi (as long as the autoclave pressure is higher than the water pressure at the injection point).

As also shown in Figure 1, the third cycle (Cycle 3) is primarily defined by pressure reduction. As can be seen, some venting can also occur during Cycle 3. This venting can be accompanied by injection of fluid from the syringe into the vent valve. However, it is worth noting that fluid injection during venting typically stops when the pressure within the autoclave drops below about 100 psi. Injection of fluid into the venting valve at a pressure below about 100 psi can cause fluid to enter the autoclave, which can cause problems with the polymer process. Therefore, it is more efficient to inject fluid into the exhaust valve while the exhaust valve is venting because the pressure in the agitated autoclave is 100 psi or more. At the end of cycle 3, the specific reference nylon 6,6, again, for example, may have a relative viscosity of from about 16 to 20 units and a water concentration of from about 0.002 to 0.006 g/g.

The fourth cycle (Cycle 4) may be characterized by a pressure that is even lower than the pressure initially exhibited at the beginning of the autoclave process, and may be obtained using vacuum pressure. Furthermore, during the fourth cycle, there may be a descent of the agitator RPM. At the end of cycle 4, again with respect to nylon 6,6, the relative viscosity can be from about 32 to 55 units (RV) and the water content can be from about 0.001 to 0.004 g/g. The fifth cycle (Cycle 5) may be characterized by a casting or extrusion cycle in which the formed polymer is extruded and pelletized for further use. Other steps after extrusion are generally performed as understood by those skilled in the art.

In view of the foregoing, the present invention is directed to a method and apparatus for cleaning and/or maintaining an exhaust system of an agitated autoclave during the preparation of a polymer, particularly a polyamidamide polymer such as nylon 6,6. The method includes introducing a polymerizable composition comprising a polyamine salt into an agitated autoclave having an agitator and an exhaust valve associated with the exhaust system, venting the agitated autoclave via the first flow path and During at least a portion of the venting step, fluid is injected into the vent valve via the second flow path. In one aspect, an exhaust system including an exhaust valve may have some pre-existing deposits in the exhaust line or valve. In such cases, the above methods can be used to clean and remove all or a portion of such deposits and to prevent or reduce the formation of other new deposits. In addition, the cleaning/maintenance system can function to maintain proper operation of the valve over an extended period of time when the syringe is in close proximity to the valve, such as near the valve seat.

Also, the present invention also provides an agitated autoclave and an exhaust system. The agitated autoclave and exhaust system can include an agitated autoclave including an agitator and an exhaust valve configured to vent the agitated autoclave along a first flow path; associated with the exhaust valve and grouped a syringe that injects fluid into the vent valve along a second flow path; and a syringe module adapted to control fluid injected from the injector into the vent valve.

In one example, the autoclave can be vented after the first cycle, such as after obtaining and maintaining a relatively high pressure during the second cycle. Injection of fluid into the exhaust valve may be performed during substantially the entire second cycle or may be part of the second cycle if necessary It is activated and deactivated during the period. Alternatively, the timing of fluid injection can be adapted to effect injection based on opening and closing of the vent valve or when the venting is above a certain level (or pressure within the autoclave). In one aspect, the fluid injection can be performed at least twice during the second cycle. The pressure during the second cycle can generally be maintained from about 230 psi to about 300 psi throughout the second cycle, so it can be beneficial to inject fluid into the vent valve during the second cycle. However, it should be noted that the autoclave can be vented during a portion of the third cycle, such as shown with respect to FIG. Therefore, it is also possible to inject fluid into the exhaust valve during such an exhaust event. In embodiments of the invention, fluid injection may be stopped after the pressure in the autoclave is reduced to or below a predetermined level, such as a level of about 100 psi or more, whenever the venting and concomitant fluid injection occurs. As mentioned, continued injection of fluid into the vent valve when the autoclave pressure is reduced below 100 psi may cause the fluid to descend into the autoclave (rather than exit via the vent line) and have a negative impact on the polymer product, although Depending on the system, it is not necessary to exclude injection of fluid at these lower pressure levels.

The fluid injected by the syringe can be any fluid that is effective to keep the vent valve and/or vent line clean and substantially free of monomer/oligomer/polymer deposits. The fluid can be a gas or a liquid. In an embodiment, the fluid can be water, steam, or a combination thereof. In another embodiment, the fluid can be an aqueous solution that can include a small amount of a cleaning agent suitable for removing monomer, oligomer or polymer deposits. In another embodiment, the fluid can be water. The fluid temperature can be ambient temperature or it can have a high temperature. The fluid can be sourced from any location or source. In an embodiment, the fluid may be sourced from a scrubber associated with the autoclave as part of an exhaust system. The fluid injected by the syringe can be injected under high pressure. In one embodiment, the high pressure can range from about 100 psig to about 200 psig. The flow rate of fluid into the vent valve can range from about 0.5 gallons per minute to about 5 gallons per minute, or from about 2 gallons per minute to about 4 gallons per minute.

Turning now to Figures 2A and 2B, a schematic cross-sectional view of an embodiment of an agitated autoclave is shown. These figures are not necessarily drawn to scale and do not indicate that they may be present in a stirred autoclave. Each and every detail is instead selected to show a schematic representation of features particularly relevant to the present invention. Thus, in this example, the agitated autoclave 10 can include an autoclave vessel 20 and an agitator or auger 30. The container includes a container wall 22, which is typically a coated container wall, and the container wall and/or other structure is adapted to support one or more types of heating assemblies 24, 26. In this example, the outer jacket heating assembly is shown at 24 and the inner heating assembly is shown at 26. Figure 2A shows the internal heating assembly near the wall of the vessel, while Figure 2B shows the internal heating assembly closer to the agitator or auger. Also shown in Figure 2B is a pair of re-bars 18 that work with a central agitator or auger to regenerate the polymer. Basically, the agitator operates to move the polymer up the central portion, and a new bar pair is used to renew the molten polymer from the sidewall surface while agitating the molten polymer. This configuration improves heat transfer within the system and reduces the vortex height caused by agitation.

The outer sheath heating assembly can be used to raise the temperature and pressure of the polymerizable composition or polymer contained within the container, and the internal heating assembly is particularly useful for other purposes to prevent the polymer from becoming adhering to the interior surface of the container wall. It should be noted that the internal heating components are shown schematically in cross section, but it should be understood that any shape or configuration of the internal heating components can be used. It should also be noted that the heating assembly can be configured or adapted to carry any fluid known in the art to provide heat to the autoclave, including gases and/or liquids. In addition, the bottom end of the autoclave vessel is a squeeze valve opening 28. The valve is not shown, but this is where the polymer prepared in the autoclave is extruded for further processing.

For the particular agitation method described herein, in the configuration shown, the agitator or auger 30 will carry the polymerizable composition (or polymer formed therefrom) up with the flow pattern 32 shown in Figure 2A. It is directed to the central region of the autoclave vessel 20 and down to the vessel wall 22. A similar flow pattern will be present in the autoclave shown in Figure 2B, except that the new rod 18 will provide additional re-mixing near the vessel wall 22. In either case, when the auger is agitated, the auger can be moved according to the mode shown to cause RPM levels sufficient to cause at least some mixing of the polymerizable composition or polymer. For example, auger or agitator can be used in agitated autoclaves 100 RPM rotation, but typically set at a speed of, for example, 5 RPM to 90 RPM or 70 RPM to 90 RPM. RPM levels external to this range as would be understood by those skilled in the art can also be used.

Inlet valve 44 can be used to add a polymerizable composition, other additives or gases to increase the pressure within the autoclave vessel. Typically, the pressure within the container is modulated by introducing a polymerizable composition and a modulated heating profile. In addition, an exhaust system is also provided that includes an autoclave exhaust valve 46, an exhaust line 48, and a syringe 92. An exhaust system is presented for exhausting gas from the autoclave vessel via the exhaust valve and discharged into the exhaust line 48 to reduce or maintain the pressure of the autoclave. It is worth noting that any type of valve known in the art can be used for either the exhaust valve or other valves discussed herein. In addition, it should be noted that regardless of the description of the inlets and valves and the location shown, etc., it may be used for any purpose designed by the user (as will be understood by those skilled in the art) and used otherwise. port. As previously described, during the second cycle of the polymerization process within the autoclave, the pressure is brought to a relatively high pressure and maintained substantially constant during the cycle (although there is a combination of increased heat and autoclave venting). For example, the pressure during the second cycle can be maintained from about 230 psi to about 300 psi during the entire second cycle, although pressure profiles external to this range can also be used in some embodiments. In general, the second cycle can last from 10 to 45 minutes, although the duration of the change can be adjusted. As mentioned, the exhaust system of the autoclave further includes a syringe associated with the exhaust valve and configured to inject fluid into the exhaust valve. Although not shown in Figures 2A and 2B, as further detailed in Figure 3, the syringe can be coupled to a fluid source for injection into the vent valve. The syringe can be configured to abut the valve seat of the exhaust valve, and in one example, at the valve seat or slightly upstream or downstream of the valve seat (because it is related to the flow of the exhaust gas (first flow path)) fluid. In an embodiment, the syringe can be positioned such that fluid is injected onto or near the valve seat of the exhaust valve via the sidewall of the exhaust valve (along the second fluid flow path). Thus, in one example, the first flow path can be defined as a flow path from the interior of the autoclave via the exhaust valve and into the exhaust line 48. Second flow path Defined as the flow path from the injector via the exhaust valve and into the exhaust line. In this configuration, the first flow path and the second flow path are different but become joined within the exhaust or exhaust line.

With regard to the autoclave, in further detail, in some embodiments, one or more of the autoclaves may be automated. For example, as shown in Figures 2A and 2B, the autoclave can include a controller 50 that can include various modules 60, 70, 80, 90 and can be used to automatically perform the general or method steps of the agitated autoclave. For example, the heating assemblies 24, 26 can be controlled by the heating module 60. The pressure of the autoclave can be controlled by a pressure control module 70 that controls the inlet valve 44 and the exhaust valve 46 of the autoclave. It should be noted that the pressure can also be controlled, for example by increasing the heat in the autoclave. Therefore, the pressure control module can also alternatively control the heating assembly. The exhaust system including the exhaust valve 46 and the injector 92 can be controlled by the exhaust module 80 and the injector module 90, respectively. The vent and injector module can be programmed to inject fluid into the vent valve when, for example, the vent valve is opened and the autoclave is at a predetermined pressure of at least 100 psi. The modules can work together to circulate the system in a manner that causes predictable batch polymerization of the polymerizable composition. Thus, Figure 1 illustrates an example in which the heating module, pressure control module, and exhaust module work together to achieve acceptable polymerization results. In addition, and in accordance with the present invention, a syringe module can also be used with such other modules to help prevent clogging/clogging of the exhaust or exhaust line by monomer, oligomer, and/or polymer deposits or Obstruction. Other benefits include faster processing of the batch; thus the ability to increase yield.

3 shows a general flow diagram of an embodiment of a stirred autoclave 100 having an exhaust system including a fluid injector 190 and an exhaust valve 110, in accordance with an example of the present invention. As can be seen in this figure, the autoclave and exhaust valve are associated with an exhaust system that includes a scrubber 120, a pump 130, and the aforementioned injectors. As shown in the flow chart, the injector can include a check valve 170 that prevents fluid from flowing back into the syringe from the exhaust valve, a restriction orifice 160 configured to maintain fluid flow at a desired flow rate, and is configured to initiate A shut-off valve 150 for the fluid flow of the syringe. In some embodiments, manual is included at one or both ends of the syringe The ease with which the valves 140, 180 permit maintenance or replacement may be suitable.

As also shown in Figure 3, the exhaust valve 110 is coupled to a scrubber 120 located downstream of the exhaust valve. The fluid connection can be via an exhaust line (not shown). It should be noted that the arrows shown in Figure 3 may represent fluid lines or conduits as will be understood by those skilled in the art. The scrubber can be of any type known in the art. Although not shown, the scrubber can be operatively coupled to an exhaust valve of a plurality of autoclaves, each of which has its own injector. In certain embodiments, fluid from the scrubber (eg, water and/or steam) may be recirculated from the scrubber and pumped back to the injector 190 by the pump 130. The pump acts to pressurize the fluid in the syringe.

It is worth noting that these methods and agitated autoclaves and associated exhaust systems can provide several advantages over similar methods or autoclave exhaust systems that do not include the injectors described herein. For example, the inclusion of a syringe significantly reduces the blockage/clogging of the exhaust valve and/or associated exhaust line of the exhaust system or the suppression of proper function. This allows for less downtime required to clean or otherwise maintain the exhaust and exhaust lines. For example, each blockage/clogging in the vent line or vent valve can take about 5 days of downtime and loss of thousands of kilograms of polymer.

In addition, the use of a syringe in an agitated autoclave allows for a larger batch size in the autoclave, the larger the batch size, and the less head space left in the autoclave. Generally, a reduction in headspace distance between the top of the polymeric material and the autoclave can result in increased problems of clogging the exhaust valve and/or the exhaust line or inhibiting its function. In addition, the use of a syringe allows the scrubber of the exhaust system to be placed further away from the autoclave, which in turn allows the same scrubber to be used simultaneously on a plurality of autoclaves. Using the same scrubber for multiple autoclaves reduces manufacturing-related costs and allows for more efficient use of space within the manufacturing facility.

Turning now to example polymers which can be prepared using the methods and apparatus described herein, we can consider the preparation of polyamine polymers, and in particular nylon 6,6. Typical batch sizes according to examples of the invention may range from about 1000 Kg to about 3000 Kg, and batches that may be in the autoclave The cycle is about 100 to about 360 minutes or more than 360 minutes. In one aspect, the cycle duration can range from about 100 minutes to about 180 minutes. In another aspect, the cycle duration can be from about 100 minutes to about 160 minutes. In another aspect, the cycle duration can be less than about 155 minutes. In another aspect, the cycle duration can be from about 100 minutes to about 155 minutes. Batch sizes and timings outside of these ranges may also be used depending on equipment and polymer options, or other considerations within the knowledge of those skilled in the art.

As mentioned, the polyamine polymer prepared according to the examples of the present invention may be a nylon type polyamine, such as nylon 6,6. The polymerizable composition for forming the nylon 6,6 polymer can be prepared, for example, first by using a salt paste method in which adipic acid and hexamethylenediamine are reacted. The water present in the composition may be removed when the salt solution is introduced into the evaporator (in the form of a solvent carrying the reactant or introduced by a condensation reaction of adipic acid and hexamethylenediamine) for introduction into A portion of the water was previously removed in the agitated autoclave as described herein. This solution, referred to herein as a polymerizable composition, may include nylon 6,6 salts, as well as other additives generally known in the art, such as antifoaming agents, catalysts, antioxidant stabilizers, antimicrobial additives, optical enhancements. Brighteners, acid dyeable polymers, acid dyes or other dyes or the like. Titanium dioxide may also be included if the goal is to whiten the product, but is usually added directly to the autoclave to avoid coalescence. When prepared for polymerization in an autoclave, a polyamidamine salt (such as a nylon 6,6 salt) can be present in the polymerizable composition, for example, in an amount ranging from about 50 wt% to 95 wt%.

If a catalyst is added, the catalyst may be present in the polymerizable polyamide composition in an amount ranging from 10 ppm to 1,000 ppm by weight. In another aspect, the catalyst can be present in an amount ranging from 10 ppm to 100 ppm by weight. Catalysts can include, but are not limited to, phosphoric acid, phosphorous acid, low phosphoric acid, arylphosphoric acid, arylphosphinic acid, salts thereof, and mixtures thereof. In one embodiment, the catalyst may be sodium hypophosphite, manganese hypophosphite, sodium phenylphosphinate, sodium phenylphosphonate, potassium phenylphosphinate, potassium phenylphosphonate, bisphenylphosphinic acid Diammonium, potassium tolylphosphinate or a mixture thereof. In one aspect, the catalyst can be hypophosphorous acid sodium.

Polyamine compositions prepared in accordance with the embodiments disclosed herein can be modified for whiteness by the addition of optical brighteners, such as titanium dioxide. Such polyamines can exhibit permanent whiteness improvement and can be retained by such operations as heat setting. In an embodiment, the optical brightener may be present in the polymerizable polyamine in an amount ranging from 0.01 wt% to 1 wt%.

Additionally, such polymerizable polyamines may contain antioxidant stabilizers or antimicrobial additives known in the art. Additionally, the polymerizable composition can contain an antifoaming additive. In an embodiment, the antifoam additive may be present in the polymerizable composition in an amount ranging from 1 ppm to 500 ppm by weight.

The polymerizable composition according to an embodiment of the present invention may be acid dyeable in nature, but may also be rendered alkaline by modifying the polymer or copolymer with a cationic dye copolymerized in the polymer. Dyeing form. This modification makes the composition particularly susceptible to coloring with basic dyes.

It should also be noted that some of the functional units described in this specification have been labeled as "modules" to more explicitly emphasize their construction independence. For example, a "module" can be constructed as a hardware loop that includes a conventional VLSI circuit or gate array, an off-the-shelf semiconductor such as a logic die, a transistor, or other discrete components. Modules can also be constructed in programmable hardware devices, such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like. Modules can also be built into software for execution by various types of processors. The executable code authentication module can, for example, comprise one or more blocks of computer instructions that can be organized into objects, programs or functions. Nonetheless, the executables of the authentication module need not be physically located together, but may include different instructions stored in different locations, including modules and achieving the stated purpose of the modules when logically joined together.

In fact, the modules of executable code can be a single instruction or multiple instructions, and can even be distributed across several different code segments, in different programs, and across multiple memory devices. class The operational data may be identified and described herein within the module and may be implemented in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set or may be distributed via different locations, including through different storage devices. The modules can be passive or active, including agents that are operable to perform the required functions.

Instance Example 1 Autoclave in the case of traditional circulation

A commercial autoclave having an ability to produce 1000 to 1300 kg of nylon-6,6 per cycle was filled with an aqueous solution of adipic acid and hexamethylenediamine. The temperature was raised from 150 ° C to 280 ° C. Commercial autoclaves are equipped with pressure control valves that are discharged into the exhaust line. When the pressure in the autoclave reached approximately 300 psia, the control valve was fully opened to maintain the pressure at 300 psia. Both the water in the solution and the water precipitated by the condensation reaction of adipic acid and hexamethylenediamine are controllably released into the exhaust line from the autoclave via a control valve. Water containing at least a small amount of solids (diamine, adipic acid, and a very small amount of short-chain nylon-6,6 polymeric material) condenses on the inner wall of the exhaust line and at least a portion due to pressure drop across the control valve and exhaust line The solid precipitates to form a highly adherent deposit on the inner wall and, in some cases, at the valve seat or near the valve seat.

Example 2 Comparative clogging rate - long cycle time

Example 1 was repeated with different cycle times. At long cycle times greater than 360 minutes, the solids deposition rate in the exhaust line is low. The cycle time is gradually shortened, and the blockage rate per unit time is increased. Moderate blockage was observed in the exhaust line at a cycle time of 180 minutes. It should be noted that clogging can also occur at or near the valve (eg, valve seat) under similar conditions.

Example 3 Comparative clogging rate - medium cycle time

The polymerization cycle of Example 1 was repeated for 182 minutes and then gradually shortened to 153 minutes. As production rates increase, the problem (blocking exhaust line) is getting worse. At 153 points Significant solid deposits were observed during the clock cycle. This accumulation represents a technical problem that is limited by the production rate because further reduction in cycle time triggers more solid deposition and blocks the exhaust line over a shorter period of time.

Example 4 Increased production time and shorter cycle time

The polymerization cycle of Example 1 was repeated at a cycle time of 153 min. Blockage of the exhaust line proves a persistent problem, with 0.7 vent lines being blocked per autoclave per month. This blockage rate causes economic losses in four aspects. First, plugging limits total polymer production (the number of batches per month) because it takes a lot of time to clean the exhaust line (the autoclave goes offline for 1-2 days), and in many cases, the autoclave itself needs overhaul (autoclave offline) 5-10 days), because the blocked exhaust line can freeze the nylon-6,6 polymer in the autoclave. Second, due to the non-standard diamine loss that occurs during the cycle, the last few batches before the exhaust line is completely blocked must be degraded. Third, maintenance costs increase because of the need to add full-time mechanisms to each shift to clean the blocked exhaust line. Fourth, it can cause an increase in the total cost per metric ton of polymer because the autoclave cannot be operated in a shorter cycle time, which reduces the amount of total polymer produced.

Example 5- Fluid injection for cleaning/maintaining exhaust line and/or valve function

The polymerization cycle of Example 1 was repeated except that water was injected into the exhaust line. Significant improvements in pressure drop through the exhaust line were observed almost immediately. In the first group of autoclaves, the vent line was not mechanically cleaned prior to the installation of the water injection, but the pressure drop became lower as the water was injected. The exhaust line of the test clearly shows that it is cleaner, although experience has shown that these exhaust lines should be more dirty and accumulate deposits. This clearly shows that water injection helps keep the vent line clean, and can even act to clean the vent line with accumulated deposits prior to introduction of water.

Although not all of the vent lines were cleaned prior to introduction of water injection, only one blocked vent line was observed during the first 30 days after the introduction of water injection in all autoclaves. Therefore, the problem ratio is reduced from 0.7 clogging of the exhaust line per autoclave per month to 0.05 clogging of the exhaust line per autoclave per month. After the first 30 days, the exhaust line The blockage problem is almost eliminated and the regional exhaust line only becomes blocked under extreme conditions of external problems such as power failure.

Although the subject matter has been described with specific reference to the structural features and/or operation, it is understood that the subject matter defined in the appended claims is not necessarily limited to the specific features and operations described. To be precise, the specific features and acts described above are disclosed in the form of examples of the scope of the application. Many modifications and alternative configurations can be devised without departing from the spirit and scope of the technology.

10‧‧‧Agitated autoclave

18‧‧‧A new bar

20‧‧‧ autoclave container

22‧‧‧ container wall

24‧‧‧heating components

26‧‧‧heating components

28‧‧‧Squeezing valve opening

30‧‧‧Agitator/Auger

44‧‧‧Inlet valve

46‧‧‧Exhaust valve

48‧‧‧Exhaust line

50‧‧‧ Controller

60‧‧‧heating module

70‧‧‧ Pressure Control Module

80‧‧‧Exhaust module

90‧‧‧Syringe module

92‧‧‧Syringe

Claims (38)

A method of cleaning or maintaining an exhaust system of an agitated autoclave during preparation of a polyamidamide polymer, comprising: introducing a polymerizable composition comprising a polyamidamine salt to an agitator and associated with an exhaust system In an agitated autoclave of an exhaust valve, the exhaust system includes an exhaust line operatively coupled to the exhaust valve of the autoclave to vent the autoclave via a first flow path of the exhaust valve, The exhaust system also includes a syringe associated with the exhaust valve and configured to inject fluid through a second flow path of the exhaust valve; exhausting the agitated autoclave via the first flow path; During at least a portion of the venting step, fluid is injected via the second flow path. The method of claim 1, wherein the venting step is performed after the first cycle of increasing the pressure to a relatively higher pressure, and maintaining the relatively higher pressure during the second cycle by the venting step. The method of claim 2, wherein the injection of the fluid is performed substantially throughout the second cycle. The method of claim 2, wherein the injection of the fluid is performed during a portion of the second cycle. The method of claim 2, wherein the injection of the fluid is performed at least twice during the second cycle. The method of claim 2, wherein the preparing of the polyamide polymer comprises a third cycle, which also includes venting the agitated autoclave during at least a portion of the third cycle. The method of claim 2, wherein the pressure during the second cycle is throughout the Maintained between about 230 psi and about 300 psi during the second cycle. The method of claim 1, wherein the fluid is water, steam, or a combination thereof. The method of claim 1, wherein the fluid is water. The method of claim 9, wherein the water system is derived from a scrubber that is part of the exhaust system. The method of claim 1, wherein the injection of the fluid is stopped after the pressure in the agitated autoclave is reduced to a level equal to or lower than about 100 psig. The method of claim 1, wherein the flow system is injected at a pressure of from about 100 psig to about 200 psig. The method of claim 1, wherein the injection of the fluid into the venting valve has an injection flow rate of from about 0.5 gallons per minute to about 5 gallons per minute. The method of claim 13, wherein the injection flow rate is from about 2 gallons per minute to about 4 gallons per minute. The method of claim 1, wherein the fluid injected into the exhaust valve inhibits formation of deposits in the exhaust valve and the exhaust line. The method of claim 1, wherein the polyamine salt is a nylon 6,6 salt. The method of claim 1, wherein the polyamine salt is prepared from adipic acid and hexamethylenediamine. The method of claim 1, wherein the syringe injects the fluid in close proximity to a valve seat of the exhaust valve. The method of claim 18, wherein the syringe injects the fluid on a downstream side of a valve seat of the exhaust valve. The method of claim 1, wherein the injector includes a check valve that prevents fluid from flowing from the exhaust valve into the syringe. The method of claim 1, wherein the injector includes a restriction aperture configured to maintain syringe fluid flow to the exhaust valve from about 0.5 gallons per minute to about 5 gallons per minute in. The method of claim 1, wherein the injector comprises a block valve configured to initiate syringe fluid flow. The method of claim 1, wherein the injector is controlled by a syringe module that is programmed to inject the fluid to the exhaust when the exhaust valve opens and the autoclave reaches a predetermined pressure of at least 100 psi In the valve. The method of claim 1, wherein the exhaust system has pre-existing deposits in the exhaust valve, exhaust line, or both, and the injection fluid is for removing at least a portion of the pre-existing deposits. An agitated autoclave and an exhaust system comprising: an agitated autoclave comprising an agitator and an exhaust valve configured to vent the agitated autoclave along a first flow path; and the exhaust valve a syringe associated and configured to inject fluid into the exhaust valve along a second flow path; and a syringe module adapted to control injection of the fluid from the injector to the exhaust valve. The agitation autoclave and exhaust system of claim 25, wherein the fluid is water, steam, or a combination thereof. The agitated autoclave and exhaust system of claim 25, wherein the fluid is water. The agitated autoclave and exhaust system of claim 27, wherein the injector is configured to inject the water at a high pressure within the agitated autoclave while the exhaust valve is vented. The agitation autoclave and exhaust system of claim 28, wherein the high pressure is from about 100 psig to about 200 psig. The agitated autoclave and exhaust system of claim 27, wherein the exhaust system includes a scrubber downstream of the exhaust valve that scrubs water in the system and recycles the water For further use. The agitation autoclave and exhaust system of claim 30, wherein the exhaust system further comprises a pump that pumps the water from the scrubber to the injector. The agitated autoclave and exhaust system of claim 30, wherein the scrubber of the exhaust system is operatively coupled to a plurality of agitated autoclaves, each of the plurality of autoclaves having a respective injector . The agitated autoclave and exhaust system of claim 25, wherein the vent valve has a valve seat and the syringe injects the fluid proximate the valve seat of the vent valve. The agitated autoclave and exhaust system of claim 33, wherein the injector injects the fluid immediately adjacent the valve seat of the exhaust valve. The agitated autoclave and exhaust system of claim 25, wherein the injector includes a check valve that prevents fluid flowing from the exhaust valve from entering the injector. The agitation autoclave and exhaust system of claim 25, wherein the injector includes a restriction orifice configured to maintain fluid flow into the exhaust valve from about 0.5 gallons per minute to about 5 gallons per minute. The agitation autoclave and exhaust system of claim 25, wherein the injector includes a block valve configured to initiate flow from the injector. The agitation type autoclave and exhaust system of claim 25, wherein the injector module is programmed to inject the fluid into the exhaust valve when the exhaust valve is opened and the agitated autoclave is vented .