A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy

Abstract

The present invention discloses a concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy, which includes a light-emitting device, a near-infrared spectrometer, a test pipeline, a flowmeter, a mixer and a detection probe; the test pipeline includes an inlet horizontal channel at the starting end, an outlet horizontal channel at the end, and a test channel with two ends respectively connected to the inlet horizontal channel and the outlet horizontal channel; the detection probe is vertically installed with an opening in the test channel of the test pipeline, and the front end of the detection probe is located in the middle of the inner cavity of the test channel of the test pipeline; the outgoing optical fiber led out from the rear end of the detection probe is connected to the light-emitting device, and the receiving optical fiber led out from the rear end of the detection probe is connected to the near-infrared spectrometer. The detection system of the present invention has the advantages of fast detection speed, high analysis efficiency, good stability and repeatability.

Description

Technical Field

[0001] The present invention relates to a detection system for the concentration of nitrocellulose aqueous suspension based on near-infrared spectroscopy, belonging to the technical field of on-line detection of suspension concentration. Background Technique

[0002] For a long time, the concentration test of nitrocellulose aqueous suspension has been carried out by methods of sampling, separation, drying and weighing. This method has a long test period. In addition, there are also situations where the test results fluctuate greatly due to sampling reasons. Since this material system is particularly prone to sedimentation, it is difficult to achieve on-line concentration detection. There is no report on the successful commercial use of a mature on-line detection system in this material system. Developing an on-line detection system for the concentration of nitrocellulose aqueous suspension has a positive promoting effect on improving the automation and intelligent level of nitrocellulose production.

[0003] Near-infrared spectroscopy technology is a non-destructive detection technology that has developed rapidly in recent years. It can be used for detecting the component content and related properties of organic materials containing carbon and hydrogen elements. It has the advantages of simple operation, no need for sample pretreatment, and easy to achieve rapid analysis, and has been widely applied to fields such as medicine, petrochemical, feed, fruits and food. So far, there is no case of on-line concentration detection applied to nitrocellulose aqueous suspension materials.

[0004] Previous experiments showed that when using a general near-infrared spectrometer on the market to test the concentration of nitrocellulose aqueous suspension, the deviation of modeling analysis is relatively large, and the average deviation of most results is greater than 5%, which cannot meet the requirements of production process control for test accuracy. Through a large number of experimental studies, it is found that the main reason for the fluctuation of test data is that the nitrocellulose aqueous suspension has a strong shielding effect on ultraviolet-visible-near-infrared light, and the concentration cannot be tested by using the transmitted light signal. Similarly, due to the large amount of water in the nitrocellulose material system, when using the diffuse reflection method for testing, the signal intensity received by the detector is also very weak, resulting in a large interference of system noise on the concentration test, so the concentration test accuracy is poor. In addition, since the nitrocellulose material is fibrous and its density is higher than that of water, the sedimentation speed is very fast. If the stirring intensity is not enough, the dispersion uniformity of the material will become poor, directly affecting the repeatability of the test results and the test accuracy. Summary of the Invention

[0005] The purpose of the present invention is to provide a detection system for the concentration of nitrocellulose aqueous suspension based on near-infrared spectroscopy in order to solve the problems of poor repeatability and low test accuracy existing in the traditional concentration detection equipment for nitrocellulose aqueous suspension.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to the present invention includes a light-emitting device, a near-infrared spectrometer, a test pipeline, a flow meter, a mixer, and a detection probe;

[0008] The test pipeline includes an inlet horizontal channel at the starting end, an outlet horizontal channel at the ending end, and a test channel with two ends respectively connected to the inlet horizontal channel and the outlet horizontal channel. The test channel extends obliquely upward from the inlet horizontal channel to the outlet horizontal channel, and the vertical cross-sectional areas of the test channel, the inlet horizontal channel, and the outlet horizontal channel are all equal;

[0009] The detection probe includes a probe housing, a collimating mirror, a quartz window, an outgoing optical fiber, and a receiving optical fiber;

[0010] The probe housing is a cylindrical encapsulation housing;

[0011] The front end plate of the probe housing is provided with an opening for fixing the quartz window. The collimating mirror is fixed in the inner cavity of the probe housing. The front spherical head of the collimating mirror is closely attached to the quartz window. The outgoing optical fiber and the receiving optical fiber are led out from the rear end of the collimating mirror and pass through the rear end plate of the probe housing;

[0012] The detection probe is vertically installed in the test channel of the test pipeline with an opening, and the front end of the detection probe is located in the middle of the inner cavity of the test channel of the test pipeline; the outgoing optical fiber led out from the rear end of the detection probe is connected to the light-emitting device, and the receiving optical fiber led out from the rear end of the detection probe is connected to the near-infrared spectrometer.

[0013] It ensures that the nitrocellulose material is in a dispersed state during the detection process. A flow meter and a mixer are installed in the inlet horizontal channel of the test pipeline.

[0014] The flow meter is an electromagnetic flow meter.

[0015] The mixer is a magnetic stirring type mixer or a turbine type mixer.

[0016] The light-emitting device is a tungsten halogen lamp.

[0017] Sealant and / or gaskets are filled between the quartz window and the front end plate of the probe housing for sealing.

[0018] The outgoing optical fiber is bundled by 1, 6, or 9 pure quartz optical cores, and the core diameter range of each optical core in the outgoing optical fiber is 200μm - 800μm; the receiving optical fiber is composed of 1 pure quartz optical core with a core diameter range of 200μm - 800μm; the ratio of the sum of the cross-sectional areas of all the optical cores in the outgoing optical fiber to the cross-sectional area of the optical core of the receiving optical fiber is 1.0 - 5.0.

[0019] The thickness range of the quartz window is 2 - 8 mm.

[0020] The lens diameter range of the collimating mirror is 5 - 20 mm.

[0021] The wavelength range of the detector used in the near-infrared spectrometer is 900 - 1800 nm.

[0022] Working process

[0023] Connect the feed inlet and the discharge outlet at both ends of the test pipeline to the production and transportation pipeline of the nitrocellulose material. Detect the flow rate of the nitrocellulose material through a flow meter. When the material flow rate is greater than 0.5 m / s, start the concentration detection. The light-emitting device emits near-infrared light, which is transmitted through the outgoing optical fiber to the inside of the test probe. After passing through the collimating mirror and transmitting through the quartz window, it acts on the nitrocellulose material flowing in the test channel of the test pipeline. Part of the light is absorbed by the nitrocellulose material, and the other part of the diffusely reflected light passes through the quartz window and enters the inside of the detection probe. This light passes through the collimating mirror and is transmitted to the near-infrared spectrometer through the receiving optical fiber, and the near-infrared spectrometer obtains the corresponding spectral data. According to the corresponding relationship between the spectral data pre-tested and the concentration of the nitrocellulose material, the real-time concentration of the nitrocellulose material can be obtained.

[0024] Beneficial effects

[0025] The detection system of the present invention, through the new structure design of the material flow channel and the configuration of a flow meter and a mixer, ensures a good material dispersion state at the probe part during the detection process. Compared with other concentration test systems, the test accuracy is significantly improved; the detection system of the present invention, through the innovative probe structure design, has the advantages of fast detection speed, high analysis efficiency, good stability and repeatability.

[0026] The detection system of the present invention can greatly reduce the detection cost and improve the test efficiency. It is not only applicable to nitrocellulose water suspensions of various specifications, but also can be used for on-line concentration detection of other material systems mainly composed of nitrocellulose. The relative deviation of the test of the nitrocellulose concentration of the detection system of the present invention is reduced from more than 5% to less than 2%, thus meeting the basic requirements of the production line for the test accuracy of the concentration. Description of the drawings

[0027] Figure 1 It is a schematic structural diagram of the detection system of the present invention;

[0028] Figure 2 It is a schematic structural diagram of the detection probe in the detection system of the present invention;

[0029] In the figure, 1 is a light-emitting device, 2 is a near-infrared spectrometer, 3 is a test pipeline, 31 is an inlet horizontal channel, 32 is a test channel, 33 is an outlet horizontal channel, 4 is a detection probe, 41 is a probe housing, 42 is a collimating mirror, 43 is a quartz window, 44 is an outgoing optical fiber, 45 is a receiving optical fiber, 5 is a flowmeter, and 6 is a mixer. Detailed implementation mode

[0030] The content of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] Embodiment

[0032] As Figure 1 shown, a detection system for the concentration of nitrocellulose aqueous suspension based on near-infrared spectroscopy of the present invention includes a light-emitting device 1, a near-infrared spectrometer 2, a test pipeline 3 and a detection probe 4;

[0033] The test pipeline 3 includes an inlet horizontal channel 31 at the starting end, an outlet horizontal channel 33 at the end, and a test channel 32 with two ends respectively connected to the inlet horizontal channel 31 and the outlet horizontal channel 33. The test channel 32 extends obliquely upward from the inlet horizontal channel 31 to the outlet horizontal channel 33, and the vertical cross-sectional areas of the test channel 32, the inlet horizontal channel 31 and the outlet horizontal channel 33 are all equal;

[0034] As Figure 2 shown, the detection probe 4 includes a probe housing 41, a collimating mirror 42, a quartz window 43, an outgoing optical fiber 44 and a receiving optical fiber 45;

[0035] The probe housing 41 is a cylindrical encapsulation housing;

[0036] The front end plate of the probe housing 41 is perforated and fixed with the quartz window 43. The collimating mirror 42 is fixed in the inner cavity of the probe housing 41. The front spherical head of the collimating mirror 42 is closely attached to the quartz window 43. The outgoing optical fiber 44 and the receiving optical fiber 45 are led out from the rear end of the collimating mirror 42 and pass through the rear end plate of the probe housing 41;

[0037] The detection probe 4 is vertically installed in the test channel 32 of the test pipeline 3 through an opening, and the front end of the detection probe 4 is located in the middle of the inner cavity of the test channel 32 of the test pipeline 3; the outgoing optical fiber 44 led out from the rear end of the detection probe 4 is connected to the light-emitting device 1, and the receiving optical fiber 45 led out from the rear end of the detection probe 4 is connected to the near-infrared spectrometer 2.

[0038] A flowmeter 5 and a mixer 6 are installed in the inlet horizontal channel 31 of the test pipeline 3.

[0039] The light-emitting device 1 is a tungsten halogen lamp.

[0040] A sealant and / or gasket is filled between the quartz window 43 and the front end plate of the probe housing 41 for sealing.

[0041] The outgoing optical fiber 44 is formed by bundling 9 pure quartz optical cores with a core diameter of 0.3 mm, and the receiving optical fiber 45 is composed of 1 pure quartz optical core with a core diameter of 0.6 mm.

[0042] The lens diameter of the collimating mirror is 5 mm, that is, the spot diameter is 5 mm.

[0043] The thickness range of the quartz window is 2 mm.

[0044] The wavelength range of the detector used in the near-infrared spectrometer 2 is 900 - 1800 nm.

[0045] The flowmeter is an electromagnetic flowmeter.

[0046] The mixer is a magnetic stirring type mixer or a turbine type mixer.

[0047] Before the test, first connect the feed inlet and the discharge outlet at both ends of the test pipeline 3 to the production and transportation pipeline of the nitrocellulose material. Detect the flow rate of the nitrocellulose material through the flowmeter. When the material flow rate is greater than 0.5 m / s, start the concentration detection. The light-emitting device 1 emits near-infrared light and transmits it through the outgoing optical fiber 44 to the inside of the test probe. It passes through the collimating mirror 42 and passes through the quartz window 43 to act on the nitrocellulose material flowing in the test channel 32 of the test pipeline 3. Part of the light is absorbed by the nitrocellulose material, and the other part of the light that undergoes diffuse reflection passes through the quartz window 43 and enters the detection probe 4. This light passes through the collimating mirror 42 and is transmitted to the near-infrared spectrometer 2 through the receiving optical fiber 45. The near-infrared spectrometer 2 obtains the corresponding spectral data. The real-time concentration of the nitrocellulose material can be obtained according to the corresponding relationship between the spectral data pre-tested and the concentration of the nitrocellulose material.

Claims

1. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy, characterized in that: it includes a light-emitting device, a near-infrared spectrometer, a test pipeline, a flowmeter, a mixer and a detection probe; the test pipeline includes an inlet horizontal channel at the starting end, an outlet horizontal channel at the ending end, and a test channel with two ends respectively connected to the inlet horizontal channel and the outlet horizontal channel. The test channel extends obliquely upward from the inlet horizontal channel to the outlet horizontal channel, and the vertical cross-sectional areas of the test channel, the inlet horizontal channel and the outlet horizontal channel are all equal; the detection probe includes a probe housing, a collimating mirror, a quartz window, an outgoing optical fiber and a receiving optical fiber; the probe housing is a cylindrical encapsulation housing; a quartz window is fixedly installed through an opening on the front end plate of the probe housing, the collimating mirror is fixed in the inner cavity of the probe housing, the front spherical head of the collimating mirror is closely attached to the quartz window, and the outgoing optical fiber and the receiving optical fiber are led out from the rear end of the collimating mirror and pass through the rear end plate of the probe housing; the detection probe is vertically installed through an opening in the test channel of the test pipeline, and the front end of the detection probe is located in the middle of the inner cavity of the test channel of the test pipeline; the outgoing optical fiber led out from the rear end of the detection probe is connected to the light-emitting device, and the receiving optical fiber led out from the rear end of the detection probe is connected to the near-infrared spectrometer; a flowmeter and a mixer are installed in the inlet horizontal channel of the test pipeline; the wavelength range of the detector used by the near-infrared spectrometer is 900 - 1800 nm.

2. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, characterized in that: the flowmeter is an electromagnetic flowmeter.

3. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, characterized in that: the mixer is a magnetic stirring type mixer or a turbine type mixer.

4. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, characterized in that: the light-emitting device is a tungsten halogen lamp.

5. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, characterized in that: sealant and / or gaskets are filled between the quartz window and the front end plate of the probe housing for sealing.

6. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, characterized in that: the outgoing optical fiber is bundled by 6 or 9 pure quartz cores, and the core diameter range of each core in the outgoing optical fiber is 200μm - 800μm; the receiving optical fiber is composed of 1 pure quartz core with a core diameter range of 200μm - 800μm; the ratio of the sum of the cross-sectional areas of all cores in the outgoing optical fiber to the cross-sectional area of the core of the receiving optical fiber is 1.0 - 5.

0.

7. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, characterized in that: the thickness range of the quartz window is 2 - 8 mm.

8. A concentration detection system for nitrocellulose aqueous suspension based on near-infrared spectroscopy according to claim 1, The characteristics are as follows: The lens diameter of the collimating mirror ranges from 5 to 20 mm.

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