Method and apparatus for adapting operating settings for frequency sweep measurements of polymer products - Patents.com

Abstract

1. A method for adapting an operating setting for a frequency sweep measurement of a polymer product, comprising the steps of: (S1) providing at least one set of operating setting parameters including at least one frequency range for a frequency sweep measurement of a polymer product, the at least one frequency range including a plurality of specific measurement frequencies; (S2) optimizing the frequency range by eliminating at least one of the plurality of specific measurement frequencies in a lower half of the frequency range, resulting in a first optimized frequency range; and (S3) optimizing the first optimized frequency range by determining a value of the measurement frequency present per decade of frequencies in at least one subrange of the frequency range and reducing the determined value of the measurement frequency present per decade in the at least one subrange of the frequency range by eliminating at least one measurement frequency in the at least one subrange, resulting in a second optimized frequency range.

Description

[Technical field]

[0001] The present invention relates to a method for the rheological characterization of polymers by fast frequency sweeps, and in particular to a method and apparatus for adapting the operating settings for frequency sweep measurements of polymer products. [Background technology]

[0002] In order to monitor and control the properties of the polymer during production, reactor samples must be collected at regular intervals and characterized in an optimal manner to characterize the materials or parameters that define the operational dynamics.

[0003] The measurement feedback frequency, which is typically every 4-6 hours for classical general-use reactors, limits the choice of characterization methods to only those that can provide results within this time frame. For example, the total measurement time includes sample acquisition, sample preparation, measurement preparation, sample heating, and the actual measurement. Furthermore, additional limitations related to the technical expertise level and plant resources are added.

[0004] Ideally, one would need to know the actual molecular weight distribution since it is the basis for all secondary properties (rheological, mechanical), however in practice this is all but prohibitive for a full-scale plant environment (high levels of resources required in terms of experts, materials, and long measurement times).

[0005] Therefore, there is a need to improve the rheological characterization of polymers used in current polymer reactors. Summary of the Invention [Means for solving the problem]

[0006] These and other objects are solved by the subject matter of the present invention as defined by the independent claims. Further embodiments are defined by the dependent claims.

[0007] According to a first aspect of the present invention, there is provided a method for adapting an operating setup for frequency sweep measurements of a polymer product.

[0008] The method includes providing at least one set of operational setting parameters including at least one frequency range for frequency sweep measurement of the polymer product, the at least one frequency range including a plurality of specific measurement frequencies.

[0009] The method includes optimizing the frequency range by eliminating at least one measurement frequency of a plurality of particular measurement frequencies in a lower half of the frequency range, resulting in a first optimized frequency range.

[0010] The method includes optimizing the first optimized frequency range by determining a value of a measured frequency present per decade of frequency in at least one subrange of the frequency range and by reducing the determined value of a measured frequency present per decade in the at least one subrange of the frequency range by removing at least one measured frequency in the at least one subrange, resulting in a second optimized frequency range.

[0011] In other words, the present invention provides a set of specialized operating settings for frequency sweep measurements that advantageously result in significant reductions in measurement time while maintaining method accuracy at a level appropriate to the plant control needs.

[0012] Furthermore, the invention advantageously enables said setup to lead to a significant reduction in measurement time.

[0013] According to one exemplary embodiment of the present invention, after optimizing the frequency range by removing at least one measurement frequency, the first optimized frequency range is further optimized by distributing the remaining specific measurement frequencies equally within the lower half of the frequency range or within the complete frequency range.

[0014] According to one exemplary embodiment of the present invention, after optimizing the first optimized frequency range, a second optimized frequency range is further optimized by equally distributing the remaining specific measurement frequencies within a subrange or the complete frequency range of said frequency range.

[0015] According to one exemplary embodiment of the present invention, the method further includes verifying the consistency of the second optimized frequency range by comparing the calculated complex viscosity value with the melt flow index value measured using the second optimized frequency range.

[0016] According to one exemplary embodiment of the present invention, the method further comprises applying the second optimized frequency range to a quality control measurement of the polymer product.

[0017] According to one exemplary embodiment of the present invention, the method further comprises applying the second optimized frequency range to currently used melt flow index measurements, which may be combined with the above-mentioned step of applying the second optimized frequency range to quality control measurements of polymer products.

[0018] According to one exemplary embodiment of the present invention, the method further comprises generating said second optimized frequency range for a particular polymer grade of interest of the polymer product.

[0019] According to one exemplary embodiment of the present invention, by generating said second optimized frequency range for a particular polymer grade of interest of the polymer product, a frequency sweep fingerprint for that particular polymer grade is defined.

[0020] According to one exemplary embodiment of the present invention, the set of operational settings parameters includes at least one shear rate.

[0021] According to a second aspect of the present invention there is provided a computer program product comprising computer readable instructions which, when loaded and executed on a processor, performs a method according to any one of the embodiments of the first aspect or the first aspect itself.

[0022] According to a third aspect of the present invention there is provided an apparatus configured for adapting an operational setting for frequency sweep measurements of a polymer product, the apparatus comprising a data memory and a processor.

[0023] The data memory is configured to provide at least one set of operational setting parameters including at least one frequency range for frequency sweep measurement of the polymer product, the at least one frequency range including a plurality of specific measurement frequencies.

[0024] The processor is configured to optimize the frequency range by eliminating at least one measurement frequency of a plurality of particular measurement frequencies in a lower half of the frequency range, resulting in a first optimized frequency range.

[0025] The processor is configured to optimize the first optimized frequency range by determining values ​​of measured frequencies present per decade of frequencies in at least one subrange of the frequency range, and by reducing the determined values ​​of measured frequencies present per decade in the at least one subrange of the frequency range by removing at least one measured frequency in the at least one subrange, resulting in a second optimized frequency range.

[0026] According to one embodiment of the invention, the processor is further configured to optimize the first optimized frequency range by distributing the remaining specific measurement frequencies equally within the lower half of the frequency range or within the complete frequency range.

[0027] According to one embodiment of the invention, the processor is further configured to optimize a second optimized frequency range by equally distributing the remaining specific measurement frequencies within a sub-range or the complete frequency range of the frequency range.

[0028] According to one embodiment of the invention, the processor is further configured to apply said second optimized frequency range to a quality control measurement of the polymer product.

[0029] According to one embodiment of the invention, the processor is further configured to apply the second optimized frequency range to a currently used melt flow index measurement.

[0030] The computer program for carrying out the method of the present invention may be stored on a computer readable medium, which may be a floppy disk, a hard disk, a CD, a DVD, a Universal Serial Bus (USB) storage device, a Random Access Memory (RAM), a Read Only Memory (ROM) and an Erasable Programmable Read Only Memory (EPROM).

[0031] The computer readable medium may also be a data communications network, for example the Internet, which allows the program code to be downloaded using a connection via WLAN or 3G / 4G or any other wireless data technology.

[0032] The methods, systems, and devices described herein may be implemented as software in a Digital Signal Processor (DSP), microcontroller, or any other side processor, or as hardware circuitry in an application specific integrated circuit, ASIC, CPLD, or FPGA.

[0033] The invention may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them, for example in available hardware of conventional mobile devices or in new hardware specifically adapted for processing the methods described herein. [Brief description of the drawings]

[0034] A more complete appreciation of the present invention and its attendant advantages may be better understood by reference to the following schematic drawings, which are not to scale.

[0035] [Figure 1] FIG. 1 shows a schematic diagram of a method for adapting an operating setup for frequency sweep measurements of a polymer product according to an exemplary embodiment of the present invention. [Diagram 2] FIG. 2 shows a schematic diagram of an apparatus for adapting an operating setup for frequency sweep measurements of a polymer product according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The illustrations in the drawings are schematic and not to scale. In different drawings, similar or identical elements are provided with the same reference numbers. Generally, the same parts, units, entities or steps are provided with the same reference numbers in several figures.

[0037] FIG. 1 shows a schematic diagram of a method for adapting an operating setup for frequency sweep measurements of a polymer product according to an exemplary embodiment of the present invention.

[0038] In particular, FIG. 1 illustrates a method for adapting an operating setup for frequency sweep measurements of a polymer product, the method comprising the steps of:

[0039] The first step of the method involves providing S1 at least one set of operational setting parameters including at least one frequency range for frequency sweep measurement of the polymer product, the at least one frequency range including a plurality of specific measurement frequencies.

[0040] As a second step of the method, a step S2 of optimizing a frequency range by eliminating at least one measurement frequency of a plurality of specific measurement frequencies in the lower half of the frequency range is performed, resulting in a first optimized frequency range.

[0041] As a third step of the method, a step S3 of optimizing the first optimized frequency range is carried out by determining values ​​of measured frequencies present per decade of frequency in at least one subrange of the frequency range and by reducing the determined values ​​of measured frequencies present per decade in the at least one subrange of the frequency range by removing at least one measured frequency in the at least one subrange, resulting in a second optimized frequency range.

[0042] The method of adapting the operating settings to frequency sweep measurements of polymer products refers to a special operating setting for frequency sweep measurements, where fast frequency sweeps result in a significant reduction in measurement time while maintaining method accuracy at a level appropriate for plant control needs. The temperatures are the same for both the standard and special operating settings.

[0043] According to an exemplary embodiment of the present invention, for polyethylene, the test temperature is set, for example, at 190° C., the same as for the MFI measurement.

[0044] According to an exemplary embodiment of the present invention, two method parameters that contribute to reducing the measurement time are modified. i. Frequency range (or equivalent shear rate) - low frequency measurements are the slowest (measurement point time is proportional to the inverse of the frequency). Removing low frequency measurements leads to significant time savings. The frequency range is narrowed, for example, from 628-0.01 rad / s to 250-0.1 rad / s. ii. Measurement points per decade – This corresponds to the amount of measurement points measured per “decade” (referring to a logarithmic scale) within the intended frequency range. This parameter has been changed, for example, from 5 points / decade to 3 points / decade.

[0045] According to an exemplary embodiment of the present invention, the setup leads to a significant reduction in measurement time. Suggestively, frequency sweep sample preparation and measurement times vary between 60-120 minutes depending on the rheological properties of the sample, i.e., high viscosity polymers require longer measurement times. Using the above setup, the measurement time is reduced to the range of 10-15 minutes.

[0046] The method of adapting the operating settings to frequency sweep measurements of polymer products makes the method attractive for use in a plant environment.

[0047] A fast frequency sweep can provide faster experimental results. The sample preparation method is comparable to the currently used melt index method. The complexity of the method equipment and the required technical skills are at the same level as the MFI method.

[0048] The method, which adapts the operating settings to frequency sweep measurements of the polymer product, provides a more complete rheological insight into its complex shear viscosity curve compared to the MFI corresponding to a single point on the complex shear viscosity curve (at unknown shear rate); the obtained complex viscosity curve is a unique fingerprint of the characterized polymer, reflecting its microstructure in terms of MWD and comonomer content.

[0049] Conversely, the MFI can be misleading since different MWDs may result in the same MFI value.

[0050] The reduced shear rate range of the process still provides adequate feedback information for a range of plant monitoring and control.

[0051] FIG. 2 shows a schematic diagram of an apparatus for adapting an operating setup for frequency sweep measurements of a polymer product according to an exemplary embodiment of the present invention.

[0052] An apparatus 100 for adapting an operating setting for frequency sweep measurements of a polymer product is provided, the apparatus 100 including a data memory 10 and a processor 20 .

[0053] The data memory 10 is configured to provide at least one set of operational setting parameters including at least one frequency range for frequency sweep measurement of the polymer product, the at least one frequency range including a plurality of specific measurement frequencies.

[0054] The processor 20 is configured to optimize the frequency range by eliminating at least one measurement frequency of a plurality of particular measurement frequencies in the lower half of the frequency range, resulting in a first optimized frequency range.

[0055] The processor 20 is configured to optimize the first optimized frequency range by determining values ​​of measured frequencies present per decade of frequency in at least one subrange of the frequency range, and by reducing the determined values ​​of measured frequencies present per decade in the at least one subrange of the frequency range by removing at least one measured frequency in the at least one subrange, resulting in a second optimized frequency range.

[0056] The processor 20 may be implemented as a digital signal processor (DSP), in a microcontroller, or in any other side processor, or as a hardware circuit within an application specific integrated circuit, ASIC, CPLD or FPGA.

[0057] Processor 20 may be implemented as a Field Programmable Gate Array in terms of an integrated circuit containing a large number of identical logic cells.

[0058] The continuing need for advanced characterization methods for plant quality monitoring and control has been established. QC methods that can exceed MFI capabilities but still be used in a plant environment would allow a level of plant monitoring and control that is better than current polymer plants.

[0059] Furthermore, more efficient detailed kinetic, molecular property oriented model predictive control models are being developed. New modeling features can monitor and control polymer molecular properties and further estimate the corresponding rheological properties. Although model predictive control is a powerful process tool, it nevertheless requires constant process feedback to ensure the validity of the predictions.

[0060] For this new control concept, the melt index value is useful but not sufficient; feedback of the MWD or complex viscosity over a large shear rate range is required. Thus, limited control feedback is a bottleneck in the model predictive control process.

[0061] It should be noted that embodiments of the present invention are described with reference to different subject matter: in particular, some embodiments are described with reference to method type claims, whereas other embodiments are described with reference to device type claims.

[0062] However, those skilled in the art will understand from the above and following description that, unless otherwise noted, any combination of features belonging to one type of subject matter as well as any combination between features relating to different subjects is considered to be disclosed in this application, however all features may be combined to provide synergistic effects that exceed the simple sum of the features.

[0063] While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description is to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0064] In the claims, the term "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or controller or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. 1. A method for adapting an operating setting for frequency sweep measurements of a polymer product, comprising: providing (S1) at least one set of operational setting parameters comprising at least one frequency range for said frequency sweep measurement of said polymer product, said at least one frequency range comprising a plurality of specific measurement frequencies; optimizing the frequency range by eliminating at least one measurement frequency of the plurality of particular measurement frequencies in a lower half of the frequency range (S2), resulting in a first optimized frequency range; optimizing the first optimized frequency range (S3) by determining the value of the measured frequency present per decade of frequency in at least one subrange of the frequency range and by reducing the determined value of the measured frequency present per decade in the at least one subrange of the frequency range by removing at least one measured frequency in the at least one subrange, resulting in a second optimized frequency range; A method comprising:

2. 2. The method of claim 1, wherein after the step (S2) of optimizing the frequency range by removing at least one measurement frequency, the first optimized frequency range is further optimized by distributing the remaining specific measurement frequencies equally within the lower half of the frequency range or within the complete frequency range.

3. 3. The method according to claim 1 or 2, wherein after the step (S3) of optimizing the first optimized frequency range, the second optimized frequency range is further optimized by equally distributing the remaining specific measurement frequencies within the partial or complete frequency range of the frequency range.

4. 4. The method according to claim 1, further comprising the step (S4) of verifying the consistency of the second optimized frequency range by comparing the calculated complex viscosity value with the melt flow index value measured using the second optimized frequency range.

5. applying the second optimized frequency range to quality control measurements of the polymer product (S5); and / or applying the second optimized frequency range to currently used melt flow index measurements (S6); The method of any one of claims 1 to 4, further comprising:

6. 6. The method according to any one of claims 1 to 5, further comprising the step (S7) of generating the second optimized frequency range for a particular polymer grade of interest of the polymer product.

7. 7. The method of claim 6, wherein the step (S7) of generating the second optimized frequency range for the particular polymer grade of interest of the polymer product defines a frequency sweep fingerprint for the particular polymer grade.

8. The method of any one of claims 1 to 7, wherein the set of operational settings parameters includes at least one shear rate.

9. 1. An apparatus (100) for adapting operating settings to frequency sweep measurements of a polymer product, comprising: a data memory (10) configured to provide at least one set of operational setting parameters including at least one frequency range for said frequency sweep measurement of said polymer product, said at least one frequency range including a plurality of specific measurement frequencies; a processor (20) configured to optimize the frequency range by eliminating at least one measurement frequency of the plurality of particular measurement frequencies in a lower half of the frequency range to result in a first optimized frequency range; the processor (20) is further configured to optimize the first optimized frequency range by determining a value of a measured frequency present per decade of frequency in at least one subrange of the frequency range, and by reducing the determined value of a measured frequency present per decade in the at least one subrange of the frequency range by removing at least one measured frequency in the at least one subrange, resulting in a second optimized frequency range. Device.

10. 10. The apparatus of claim 9, wherein the processor (20) is further configured to optimize the first optimized frequency range by distributing remaining specific measurement frequencies equally within the lower half of the frequency range or within the complete frequency range.

11. 11. The apparatus of claim 9 or claim 10, wherein the processor (20) is further configured to optimize the second optimized frequency range by distributing remaining specific measurement frequencies equally within the sub-range or complete frequency range of the frequency range.

12. 12. The apparatus of claim 9, wherein the processor is further configured to verify the consistency of the second optimized frequency range by comparing a calculated complex viscosity value with a melt flow index value measured using the second optimized frequency range.

13. 13. The apparatus of any one of claims 9 to 12, wherein the processor (20) is further configured to generate the second optimized frequency range for a particular polymer grade of interest of the polymer product.

14. the processor (20) is further configured to apply the second optimized frequency range to a quality control measurement of the polymer product; and / or The processor (20) is further configured to apply the second optimized frequency range to a currently used melt flow index measurement. Apparatus according to any one of claims 9 to 13.

15. A computer readable medium comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method of any one of claims 1 to 8.

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