Online monitoring system and method for pulp freshness in paper-making reconstituted tobacco production process

Abstract

The invention belongs to the field of paper-making reconstituted tobacco production and processing, and particularly relates to an online monitoring system and method for pulp freshness in the paper-making reconstituted tobacco production process. The pulp freshness online monitoring system in the paper-making reconstituted tobacco production process comprises an automatic sample injection control unit and a detection and automatic analysis unit. According to the system and the method, the reconstituted tobacco pulp is filtered step by step, then the pulp enters an on-line solid-phase extraction column to remove pigment and other components in filtrate, then the purified filtrate enters a sample detection pool, the nitrate content in the pulp is calculated, a detection model is established, and the freshness of the pulp is analyzed. Therefore, freshness and product quality of the slurry in the reconstituted tobacco production process are guaranteed, and the problems that when the slurry runs at about 50 DEG C in the reconstituted tobacco production process, the retention time of the slurry is long, the slurry is sour and deteriorated, and the sensory quality and production efficiency of the product are affected can be solved.

Description

Technical Field

[0001] The invention belongs to the field of production and processing of reconstituted tobacco by papermaking method, and in particular relates to an online monitoring system and method for the freshness of pulp in the production process of reconstituted tobacco by papermaking method. Background Art

[0002] The production of reconstituted tobacco leaves by papermaking draws on the pulping and papermaking technology in the papermaking industry. Pulping is the process of using a pulper to separate the fibers in tobacco stems or tobacco dust under the action of mechanical force. The pulping process will separate a large amount of protein, polysaccharides, inorganic salts and other components. During the operation of the pulp, the temperature is generally maintained at around 50°C. Protein, starch, pectin and other substances in the system are easily eroded by microorganisms. If the pulp is retained for a long time, it will cause the pulp to become sour and deteriorate, affecting the sensory quality of the product, and causing pollution to the production line, affecting production efficiency.

[0003] At present, some enterprises evaluate the freshness of pulp based on production operation experience and sensory quality assessment of the final product, and the control of pulp quality is uncertain and lagging; some enterprises use the change of nitrate ions in the pulp to evaluate the freshness and availability of the pulp. Although this method has solved the uncertainty and lag problem of the quality evaluation of pulp for reconstituted tobacco production to a certain extent, this method is an offline detection, which requires sampling and then taking the sample to the laboratory for component determination and then feeding back to the workshop, which has a certain lag and increases the detection workload of laboratory personnel.

[0004] The Chinese patent with publication number CN113514583A (publication date is October 19, 2021) discloses a method for characterizing the freshness of reconstituted tobacco slurry. The patent characterizes the relationship between the change in characteristic components of the freshness of reconstituted tobacco slurry and the sensory organs, finds characteristic substances such as the freshness of reconstituted tobacco slurry, and uses the established method to determine NO3 in the reconstituted tobacco slurry. - The method solves the uncertainty and lag in the quality evaluation of the pulp on the net in the production of reconstituted tobacco, but the laboratory test results will bring a certain lag to the production, and increase the workload and work pressure of laboratory personnel.

[0005] A Chinese patent with publication number CN108523207A (publication date September 14, 2018) discloses a method for maintaining the freshness of materials in a papermaking process reconstituted tobacco production system. The process method uses one or a combination of two or more of microwave, ultrasonic, ultraviolet and high temperature methods, and mainly includes online physical sterilization of extracts and extracted materials, finished slurry, washing liquid, dirty condensed water, and white water. After online physical sterilization, the extracts and extracted materials, finished slurry, dirty condensed water, washing water, and white water can meet online retention of 24h, 26h, 192h, and 240h respectively. The method can achieve that the reconstituted tobacco product has no odor when compared with the corresponding fresh sample, and the total number of colonies is less than the corresponding critical value of the total number of colonies and the odorous sample that has not been physically sterilized online. However, this invention patent only protects the materials in the papermaking reconstituted tobacco production line, and does not monitor the freshness and availability of the pulp in real time online. There are certain risks in the freshness and quality of the pulp in the reconstituted tobacco production. At the same time, there are hidden dangers in the quality of the reconstituted tobacco products and the pollution of the production system.

[0006] Based on this, the present invention provides an online monitoring system and method for the freshness of pulp in the production process of reconstituted tobacco leaves by a papermaking method. The system first filters the reconstituted tobacco leaf pulp step by step, then the pulp enters an online solid phase extraction column to remove components such as pigments in the filtrate, and then the purified filtrate enters a sample detection pool, the nitrate content in the pulp is calculated, and a detection model is established to analyze the freshness of the pulp, thereby ensuring the freshness of the pulp and the product quality in the production process of reconstituted tobacco leaves, and avoiding production system pollution caused by stale pulp. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides an online monitoring system and method for the freshness of pulp in a papermaking process of reconstituted tobacco leaf production. The reconstituted tobacco leaf pulp is filtered step by step through an automatic sampling control unit, a detection unit and an automatic analysis unit. The pulp enters an online solid phase extraction column to remove components such as pigments in the filtrate. The purified filtrate then enters a sample detection pool. The nitrate content in the pulp is calculated, and a detection model is established to analyze the freshness of the pulp, thereby ensuring the freshness of the pulp and the product quality in the reconstituted tobacco leaf production process, so as to solve the problem that when the pulp in the reconstituted tobacco leaf production process is operated at around 50°C, the pulp retention time is long, which may cause the pulp to become sour and deteriorate, affecting the product sensory quality and production efficiency, and the like.

[0008] Based on the above purpose, the present invention adopts the following technical solutions:

[0009] An online monitoring system for pulp freshness in a papermaking process of reconstituted tobacco leaf production, comprising an automatic sampling control unit, and a detection and automatic analysis unit;

[0010] The automatic injection control unit comprises a first liquid pump, a plate filter, a second liquid pump, a bag filter and a ceramic microfiltration membrane filter;

[0011] The liquid inlet end of the plate filter is connected to a first liquid inlet pipe, the first liquid pump is arranged on the first liquid inlet pipe, the liquid outlet end of the plate filter is connected to a first liquid outlet pipe, the second liquid pump is arranged on the first liquid outlet pipe;

[0012] The bag filter is provided with a feed port, a discharge port and a slag discharge port;

[0013] The liquid outlet end of the plate filter is connected to the feed inlet of the bag filter through the first liquid outlet pipe;

[0014] The discharge port of the bag filter is connected to the feed end of the ceramic microfiltration membrane filter through the first feed pipe; the discharge end of the ceramic microfiltration membrane filter is connected to the first discharge pipe;

[0015] The detection and automatic analysis unit includes a WION-2000NO3 ion selective electrode type online nitrate ion detection device, an online solid phase extraction column (SPE purification column), a slurry temporary storage tank, a first slurry outflow pipe and a second slurry outflow pipe;

[0016] The WION-2000NO3 ion selective electrode type online nitrate ion detection device includes valve I, valve II, water sample detection pool, nitrate detection unit, A / D acquisition module, and processor storage module;

[0017] The nitrate detection unit comprises a nitrate separation or color development module and an electrochemical detector;

[0018] The valve II is provided with a first inlet end, a second inlet end, a first outlet end, and a second outlet end;

[0019] The valve 1 is provided with a third inlet end, a fourth inlet end, a third outlet end and a fourth outlet end;

[0020] The first discharge pipe is connected to the first inlet end of the valve II, the first outlet end of the valve II is connected to the inlet end of the online solid phase extraction column (SPE purification column) through a pipeline, the outlet end of the online solid phase extraction column (SPE purification column) is connected to the third inlet end of the valve I through a pipeline, and the third outlet end of the valve I is connected to the feed end of the water sample detection pool through a pipeline;

[0021] The electrochemical detector is provided with a detection end and a water quality signal output end. The detection end of the electrochemical detector is connected to the water sample detection pool and can detect the water quality in the water sample detection pool.

[0022] The water quality signal output end of the electrochemical detector is connected to the nitrate separation or color development module signal, and the nitrate separation or color development module can convert the water quality signal emitted by the electrochemical detector into an analog signal and connect it to the A / D acquisition module signal;

[0023] The A / D acquisition module is provided with an analog signal input terminal and a digital signal output terminal, and the A / D acquisition module can convert the analog signal sent by the nitrate separation or color development module into a digital signal that can be processed by the processor storage module;

[0024] The analog signal output terminal of the nitrate separation or color development module is signal-connected to the signal input terminal of the A / D acquisition module; the processor storage module is provided with a digital signal input terminal, and the digital signal output terminal of the A / D acquisition module is signal-connected to the digital signal input terminal of the processor storage module.

[0025] Specifically, a grid is provided inside the plate filter for filtering out larger fibers and other larger solid particles.

[0026] Specifically, a filter bag is arranged in the bag filter.

[0027] Specifically, a cleaning liquid inlet is also provided in the middle of the bag filter, and the cleaning liquid inlet is connected to a cleaning pipe. By passing an external water source into the cleaning pipe and entering the bag filter through the cleaning liquid inlet, it is used to clean the slag discharge port, keep the bag filter clean and the slurry entering the bag filter fresh.

[0028] Specifically, the inlet end of the cleaning pipe is connected to an external water source, and the outlet end of the cleaning pipe extends into the interior of the bag filter. A cleaning pump is also provided on the cleaning pipe. By turning on the cleaning pump, water from the external water source is pumped into the bag filter and then discharged through the slag discharge port, thereby cleaning the slag discharge port. The cleaning pump can be a peristaltic pump or a metering pump.

[0029] Specifically, the automatic sampling control unit also includes a backwashing drug adding box (which is provided with a backwashing solution, the specific composition of which is a 0.5-1% by mass sodium hydroxide solution or a 1% by mass nitric acid solution or a 1% by mass aminosulfonic acid solution) and a membrane cleaning water tank.

[0030] Specifically, the backwash dosing box is connected to the feed end in the middle of the ceramic microfiltration membrane filter through the backwash dosing pipe, and the membrane cleaning water tank is connected to the first feed pipe through the water washing pipe; when the ceramic microfiltration membrane filter is not working, the ceramic microfiltration membrane filter can be cleaned in sequence using the backwash solution in the backwash dosing box and the pure water in the membrane cleaning water tank. Specifically, it is cleaned once with the backwash solution and then cleaned 3-5 times with pure water.

[0031] Specifically, the first liquid pump and the second liquid pump are peristaltic pumps or metering pumps.

[0032] Specifically, the nitrate detection unit is an anion chromatography electrochemical method or an ultraviolet spectrophotometry or NO3 - Ion selective electrode detection unit.

[0033] Specifically, the nitrate separation or color development module, electrochemical detector, A / D acquisition module and processor storage module all use conventional equipment and components in the prior art. Their structures, connection methods, working principles and signal transmission methods are all conventional equipment in the field and are not the inventive point of the present invention, so they will not be elaborated.

[0034] Specifically, the water sample detection pool is also connected to a storage tank for storing slurry in the next process through a first slurry outflow pipe, and a first solenoid valve is provided on the first slurry outflow pipe;

[0035] The water sample detection pool is also connected to the inlet end of the slurry temporary storage tank through a second slurry outflow pipe, and a second solenoid valve is provided on the second slurry outflow pipe. The processor storage module is interlocked with the first solenoid valve and the second solenoid valve for control. In the default state, the first solenoid valve and the second solenoid valve are both in a closed state.

[0036] When the processor storage module receives a signal indicating that the test is up to standard, the processor storage module sends an opening signal to the first solenoid valve, the first solenoid valve opens, and the slurry enters the storage tank of the next process; when the processor storage module receives a signal indicating that the test is not up to standard, the processor storage module sends an opening signal to the second solenoid valve, the second solenoid valve opens, and the slurry enters the slurry temporary storage tank for post-processing;

[0037] Specifically, the interlocking control method between the processor storage module and the first solenoid valve and the second solenoid valve can adopt conventional means in the prior art, and is not the inventive point of the present invention, so it will not be described in detail.

[0038] Further, based on a general inventive concept, the present invention also provides a monitoring method using the online monitoring system, comprising the following steps:

[0039] (I) Pretreatment of slurry samples

[0040] 1) using a first liquid pump to transport the reconstituted tobacco slurry into a plate filter, and filtering it using a grid of the plate filter;

[0041] 2) using a second liquid pump to deliver the slurry filtered by the grid into a bag filter;

[0042] 3) filtering through a bag filter to obtain a slurry filtrate, feeding the slurry filtrate into a ceramic microfiltration membrane filter through a first feed pipe for re-filtration, and filtering through the ceramic microfiltration membrane filter to obtain a membrane-filtered slurry filtrate, which is the sample to be tested after slurry pre-treatment;

[0043] (II) Online determination of nitrate ions in the filtrate sample after slurry pretreatment

[0044] 4) injecting the sample to be tested after slurry pretreatment into valve II through the first inlet port in an automatic injection manner, and simultaneously introducing pure water into valve II, so that the sample is brought into an online solid phase extraction column (SPE purification column) by the pure water;

[0045] The matrix (pigment) in the sample is retained in the online solid phase extraction column (SPE purification column), and the nitrate ions are not retained. Then the sample enters valve I and then enters the subsequent water sample detection pool through valve I;

[0046] 5) using the detection end of the electrochemical detector to detect the nitrate of the sample in the water sample detection pool, the nitrate separation or color development module can convert the water quality signal emitted by the electrochemical detector into an analog signal, and the nitrate separation or color development module then transmits the detected water quality analog signal to the A / D acquisition module, and then the A / D acquisition module converts the analog signal emitted by the nitrate separation or color development module into a digital signal that can be processed by the processor storage module, and transmits it to the processor storage module, and performs calculations;

[0047] (III) Online sample analysis

[0048] 6) Collect newly prepared slurry, use step (1) and step (2) to detect the content of nitrate ions in the newly prepared slurry, calculate the average value of the nitrate content in the newly prepared slurry, sample the newly prepared slurry, dry it, prepare it into a substrate, conduct sensory evaluation, establish a slurry freshness determination model, and determine the freshness of the tested slurry based on the spectral detection results of the slurry samples.

[0049] Furthermore, the grid aperture of the plate filter is 50-100 meshes, and when the first liquid pump is a peristaltic pump, the operating pressure is ≤0.25 MPa; when the first liquid pump is a metering pump, the operating pressure is ≤60 MPa.

[0050] Furthermore, the filter bag of the bag filter has an aperture of 500-800 mesh, which can remove fine fibers and smaller solid particles in the slurry.

[0051] Furthermore, the pore size of the microfiltration membrane in the ceramic microfiltration membrane filter is 0.22-0.80 μm, the operating pressure is ≤6.0 BAR, and the retention molecular weight is 100,000-500,000 substances, as well as impurities such as fine fibers, particles, and proteins.

[0052] Furthermore, the automatic sampling method can use a plunger pump connected to the S position (i.e., the first inlet end) of valve II to deliver the membrane filtered sample at a constant flow, pass through the quantitative loop and the first outlet end (C position) of valve II in sequence, and then deliver it to the online solid phase extraction column (SPE purification column), with a delivery flow rate of 0.1-50mL / min and a pressure of ≤60MPa.

[0053] Furthermore, the filler of the online solid phase extraction column (SPE purification column) can be any one of activated carbon, C18 silica gel, Florisil, and magnesium silicate, and the filler particle size range is 40-60nm.

[0054] Furthermore, in step (4), when the matrix (pigment) in the sample is retained in the online solid phase extraction column (SPE cleanup column), the sample matrix (pigment) retained on the online solid phase extraction column (SPE cleanup column) is cleaned into the waste liquid using pure water and acetonitrile in turn, and the online solid phase extraction column (SPE cleanup column) is cleaned and regenerated using valve II, and the flow rate of pure water and acetonitrile is 1-5 mL / min.

[0055] Furthermore, the nitrate detection method is a cadmium reduction method or a chromotropic acid method, and the standard solution used in the detection is a nitrogen-nitrate standard solution (10-500 mg / L).

[0056] Furthermore, the slurry freshness determination model formula is:

[0057]

[0058] Where: K: pulp freshness judgment value at a certain time, dimensionless; C0: average content of nitrate ions in newly prepared pulp at the start of reconstituted tobacco production, mg / L; C 新鲜 : The nitrate ion content in the last sample rated as fresh pulp, mg / L; Cx: The nitrate ion content in the reconstituted tobacco pulp at a certain moment during the production run, mg / L;

[0059] According to step (1) and step (2), the content of nitrate ions in the production running slurry is detected. According to the model judgment result, when K is less than 1, the slurry enters the next production process freshly; when K is greater than 1 or K is equal to 1, the slurry is temporarily stored and processed after judgment.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1. The present invention provides an online monitoring system and method for the freshness of pulp in the production process of reconstituted tobacco leaves by papermaking. In view of the problem that the pulp in the production process of reconstituted tobacco leaves runs at about 50°C, the pulp retention time is long, which will cause the pulp to become sour and deteriorate, affecting the sensory quality and production efficiency of the product. First, the reconstituted tobacco leaf pulp is sent into the grid by a pump, and after filtering the larger particulate matter such as larger fibers in the pulp sample through the grid, it enters the bag filter, and then passes through the ceramic microfiltration membrane filter to obtain the pulp filtrate. The pulp filtrate after microfiltration membrane filtration passes through a binary gradient valve and a quantitative loop and enters an online solid phase extraction column to remove the pigment and other components in the filtrate. Then, the purified filtrate enters the sample detection pool (at the same time, the standard solution enters the sample detection pool), passes through the nitrate detection unit, the A / D acquisition module, and the processor storage module in sequence, and establishes a detection model to calculate the K value using the detected nitrate content, wherein a K value less than 1 indicates that the pulp is fresh and enters the next process, and a K value greater than or equal to 1 indicates that the pulp is no longer fresh and cannot enter the next production process, and enters the pulp temporary storage tank to wait for further processing.

[0062] 2. The online monitoring system and monitoring method ensure that only fresh reconstituted tobacco pulp can enter the next production process, ensuring the freshness of the pulp and product quality in the reconstituted tobacco production process, avoiding the pollution of the production system caused by stale pulp, and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 The figure is a component connection relationship and a flow chart of the automatic injection control unit in Example 1;

[0064] Figure 2 1. The figure shows the component connection relationship and flow chart of the detection and automatic analysis unit in Example 1. DETAILED DESCRIPTION

[0065] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0066] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0067] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0068] Example 1

[0069] like Figure 1 , 2As shown, an online monitoring system for pulp freshness in a papermaking process of reconstituted tobacco leaf production includes an automatic sampling control unit, and a detection and automatic analysis unit;

[0070] like Figure 1 As shown, the automatic sampling control unit includes a first liquid pump 11, a plate filter 12, a second liquid pump 13, a bag filter 14, a ceramic microfiltration membrane filter 15 (specifically a KQ-GLQ-2 type precision filter), a backwashing and dosing box 16, and a membrane cleaning water tank 17;

[0071] The plate filter 12 is provided with a grid for filtering out larger fibers and other larger solid particles;

[0072] The liquid inlet end of the plate filter 12 is connected to a first liquid inlet pipe, the first liquid pump 11 is arranged on the first liquid inlet pipe, the liquid outlet end of the plate filter 12 is connected to a first liquid outlet pipe, and the second liquid pump 13 is arranged on the first liquid outlet pipe;

[0073] A feed port is provided in the middle of the bag filter 14, and a discharge port 143 and a slag discharge port 142 are provided at the bottom of the bag filter 14;

[0074] The bag filter 14 is provided with a filter bag 141;

[0075] The liquid outlet end of the plate filter 12 is connected to the feed inlet in the middle of the bag filter 14 through the first liquid outlet pipe.

[0076] The discharge port 143 at the bottom of the bag filter 14 is connected to the feed end at the bottom of the ceramic microfiltration membrane filter 15 through the first feed pipe 151; the discharge end at the top of the ceramic microfiltration membrane filter 15 is connected to the first discharge pipe 152.

[0077] A cleaning liquid inlet is also provided in the middle of the bag filter 14, and a cleaning pipe 144 is connected to the cleaning liquid inlet. By passing an external water source into the cleaning pipe 144 and entering the bag filter 14 through the cleaning liquid inlet, it is used to clean the slag discharge port 142, thereby keeping the bag filter 14 clean and the slurry entering the bag filter 14 fresh.

[0078] The backwashing dosing box 16 is connected to the feed end in the middle of the ceramic microfiltration membrane filter 15 through the backwashing dosing pipe, and the membrane cleaning water tank 17 is connected to the first feed pipe 151 through the water washing pipe;

[0079] Specifically, the first liquid pump 11 and the second liquid pump 13 are peristaltic pumps or metering pumps.

[0080] The detection and automatic analysis unit in the present invention is improved on the basis of WION-2000NO3 ion selective electrode type online nitrate ion detection equipment (with an SPE purification column added), specifically, Figure 2As shown, the detection and automatic analysis unit includes a WION-2000NO3 ion selective electrode type online nitrate ion detection device, an online solid phase extraction column (SPE purification column) 22, a slurry temporary storage tank 28, a first slurry outflow pipe (not marked in the figure) and a second slurry outflow pipe (not marked in the figure);

[0081] The WION-2000NO3 ion selective electrode type online nitrate ion detection device comprises valve I 23 (six-way valve), valve II 21 (six-way valve), water sample detection pool 24, nitrate detection unit (specifically NO3 - Ion selective electrode detection unit), A / D acquisition module 26, processor storage module 27;

[0082] Further, the nitrate detection unit includes a nitrate separation or color development module 251 and an electrochemical detector 252;

[0083] Among them, the nitrate detection unit, the A / D acquisition module 26, and the processor storage module 27 are all parts of the WION-2000NO3 ion selective electrode type online nitrate ion detection device, and are not independent devices;

[0084] A quantitative loop is provided on valve II 21. Both valve I 23 and valve II 21 are six-way valves commonly used in HPLC equipment. The structures of valve I 23 and valve II 21 are not the inventive point of the present invention, so they will not be described in detail.

[0085] The valve II 21 is provided with a first inlet end, a second inlet end, a first outlet end and a second outlet end;

[0086] The valve I 23 is provided with a third inlet port, a fourth inlet port, a third outlet port and a fourth outlet port;

[0087] The first discharge pipe 152 is connected to the first inlet end of the valve II 21, the first outlet end of the valve II 21 is connected to the inlet end of the online solid phase extraction column (SPE purification column) 22 through a pipeline, the outlet end of the online solid phase extraction column (SPE purification column) 22 is connected to the third inlet end of the valve I 23 through a pipeline, the third outlet end of the valve I 23 is connected to the feed end of the water sample detection pool 24 through a pipeline, and the fourth inlet end is the standard solution inlet end;

[0088] The electrochemical detector 252 is provided with a detection end and a water quality signal output end. The detection end of the electrochemical detector 252 is connected to the water sample detection pool 24 and can detect the water quality in the water sample detection pool 24.

[0089] The water quality signal output end of the electrochemical detector 252 is connected to the nitrate separation or color development module 251, and the nitrate separation or color development module 251 can convert the water quality signal emitted by the electrochemical detector 252 into an analog signal and is connected to the A / D acquisition module 26;

[0090] The A / D acquisition module 26 is provided with an analog signal input terminal and a digital signal output terminal, and the A / D acquisition module 26 can convert the analog signal sent by the nitrate separation or color development module 251 into a digital signal that can be processed by the processor storage module 27;

[0091] The analog signal output terminal of the nitrate separation or color development module 251 is signal-connected to the signal input terminal of the A / D acquisition module 26; the processor storage module 27 is provided with a digital signal input terminal, and the digital signal output terminal of the A / D acquisition module 26 is signal-connected to the digital signal input terminal of the processor storage module 27;

[0092] Specifically, the nitrate separation or color development module 251, the electrochemical detector 252, the A / D acquisition module 26 and the processor storage module 27 all use conventional equipment and components in the prior art, and their structures, connection methods, working principles, and signal transmission methods are all conventional equipment in the art, and are not the inventive point of the present invention, so they will not be repeated;

[0093] The water sample detection pool 24 is also connected to a storage tank (not shown in the figure) for storing slurry in the next process through a first slurry outflow pipe, and a first solenoid valve is provided on the first slurry outflow pipe;

[0094] The water sample detection pool 24 is also connected to the inlet end of the slurry temporary storage tank 28 through the second slurry outflow pipe. The second slurry outflow pipe is provided with a second solenoid valve. The processor storage module 27 is interlocked with the first solenoid valve and the second solenoid valve. In the default state, the first solenoid valve and the second solenoid valve are both closed.

[0095] When the processor storage module 27 receives a signal indicating that the test is up to standard, the processor storage module 27 sends an opening signal to the first solenoid valve, the first solenoid valve opens, and the slurry enters the storage tank of the next process; when the processor storage module 27 receives a signal indicating that the test is not up to standard, the processor storage module 27 sends an opening signal to the second solenoid valve, the second solenoid valve opens, and the slurry enters the slurry temporary storage tank 28 for post-processing;

[0096] Specifically, the interlocking control method between the processor storage module 27 and the first solenoid valve and the second solenoid valve can adopt conventional means in the prior art, and is not the inventive point of the present invention, so it will not be described in detail.

[0097] Example 2

[0098] Example 2 provides a monitoring method using the online monitoring system described in Example 1, and the specific steps are as follows:

[0099] (I) Pretreatment of slurry samples:

[0100] 1) Using a first liquid pump 11 (specifically a peristaltic pump or a metering pump) to transport the reconstituted tobacco slurry (mass fraction of about 2%-5%) into a plate filter 12, and filtering using the grid of the plate filter 12 to remove larger fibers and other larger solid particles. The grid aperture of the plate filter 12 is 50-100 meshes. When the first liquid pump 11 is a peristaltic pump, the operating pressure is ≤0.25MPa; when the first liquid pump 11 is a metering pump, the operating pressure is ≤60MPa;

[0101] 2) Using a second liquid pump 13 (specifically a peristaltic pump or a metering pump) to send the slurry after removing larger fibers and other larger solid particles into a bag filter 14, the filter bag 141 of the bag filter 14 has a pore size of 500-800 meshes, which can remove fine fibers and smaller solid particles in the slurry;

[0102] A slag discharge port 142 is provided at the bottom of the bag filter 14, and a cleaning liquid inlet is also provided in the middle of the bag filter 14. The cleaning liquid inlet is connected to a cleaning pipe 144. By passing an external water source into the cleaning pipe 144 and entering the bag filter 14 through the cleaning liquid inlet, the slag discharge port 142 is cleaned to keep the bag filter 14 clean and the slurry entering the bag filter 14 fresh.

[0103] Specifically, in this embodiment, the cleaning pipe 144 is arranged at the middle and lower part of the bag filter 14, the inlet end of the cleaning pipe 144 is connected to the external water source, and the outlet end of the cleaning pipe 144 extends into the interior of the bag filter 14. The cleaning pipe 144 is also provided with a cleaning pump. By turning on the cleaning pump, water from the external water source is pumped into the bag filter 14, and then discharged through the slag discharge port 142, so as to achieve the cleaning of the slag discharge port 142. The cleaning pump can be a peristaltic pump or a metering pump; wherein, the operating pressure of the peristaltic pump is ≤0.25MPa, and the operating pressure of the metering pump is ≤60MPa;

[0104] 3) After filtering through the bag filter 14, a slurry filtrate is obtained, and the slurry filtrate is sent to the ceramic microfiltration membrane filter 15 through the first feed pipe 151 for re-filtration. The pore size of the microfiltration membrane in the ceramic microfiltration membrane filter 15 is 0.22-0.80 μm, the operating pressure is ≤6.0 Bar, and the molecular weight cutoff is 100,000-500,000 substances, as well as fine fibers, particles, proteins and other impurities. The slurry filtrate after membrane filtration is obtained by filtering through the ceramic microfiltration membrane filter 15, which is the sample to be tested after slurry pre-treatment;

[0105] The automatic sampling control unit also includes a backwashing and dosing box 10 (which is provided with a backwashing liquid, the specific composition of which is a sodium hydroxide solution with a mass fraction of 0.5-1% or a nitric acid solution with a mass fraction of 1% or an aminosulfonic acid solution with a mass fraction of 1%) and a membrane cleaning water tank 17. When the ceramic microfiltration membrane filter 15 is not working, the backwashing liquid in the backwashing and dosing box 10 and the pure water in the membrane cleaning water tank 17 can be used in sequence to clean the ceramic microfiltration membrane filter 15. Specifically, the backwashing liquid is used for cleaning once, and then the pure water is used for cleaning 3-5 times;

[0106] (II) Online determination of nitrate ions in the filtrate sample after slurry pre-treatment:

[0107] 4) If Figure 2 As shown, 1-5 mL of the sample to be detected after slurry pretreatment is injected into valve II 21 through the first inlet end in an automatic injection manner. The automatic injection manner can be connected to the S position (i.e., the first inlet end) of valve II 21 by a plunger pump, and the sample after membrane filtration is transported at a constant flow rate, sequentially passes through the quantitative loop and the first outlet end (C position) of valve II 21, and then is sent to the online solid phase extraction column (SPE purification column) 22, the delivery flow rate is 0.1-50 mL / min, and the pressure is ≤60 MPa. At the same time, pure water is introduced into the P position (second inlet end) of valve II 21, and the sample is brought into the online solid phase extraction column (SPE purification column) 22 by 15-20 mL of pure water at a flow rate of 1-5 mL / min. The filler of the online solid phase extraction column (SPE purification column) 22 can be any one of activated carbon, C18 silica gel, Florisil, and magnesium silicate, and the filler particle size range is 40-60 nm;

[0108] The matrix (pigment) in the sample is retained in the online solid phase extraction column (SPE purification column) 22, and the nitrate ions are not retained. Then the sample enters the valve I 23, and then enters the subsequent water sample detection pool 24 through the valve I 23;

[0109] Then, pure water and acetonitrile are used in turn to clean the sample matrix (pigment) trapped on the online solid phase extraction column (SPE purification column) 22 into the waste liquid, and valve II 21 is used to realize the cleaning and regeneration of the online solid phase extraction column (SPE purification column) 22 (specifically, acetonitrile is introduced from the P position (second inlet end) of valve II 21, transported to the online solid phase extraction column (SPE purification column) 22 through the C position (first outlet end), and then transported to the W position (fourth outlet end) of valve I 23 through the S position (third inlet end) of valve I 23, and the waste liquid is discharged to complete the cleaning and regeneration of the SPE purification column), and the flow rate of pure water and acetonitrile is 1-5 mL / min;

[0110] 5) Using the detection end of the electrochemical detector 252 to detect the nitrate of the sample in the water sample detection pool 24, the nitrate separation or color development module 251 can convert the water quality signal emitted by the electrochemical detector 252 into an analog signal, and the nitrate separation or color development module 251 then transmits the detected water quality analog signal to the A / D acquisition module 26, and then the A / D acquisition module 26 converts the analog signal emitted by the nitrate separation or color development module 251 into a digital signal that can be processed by the processor storage module 27, and transmits it to the processor storage module 27, and performs calculations;

[0111] The nitrate detection method is the cadmium reduction method or the chromotropic acid method, and the standard solution used in the detection is the nitrogen-nitrate standard solution (10-500 mg / L);

[0112] Among them, when the cadmium reduction method is used to determine the nitrate ion content, reagent A is concentrated sulfuric acid, reagent B is p-aminobenzenesulfonic acid gentisic acid solution, reagent C is sodium hydroxide solution, and the detection wavelength is 500nm; when the chromotropic acid method is used to determine the nitrate ion content, reagent A is concentrated sulfuric acid, reagent B is pure water, reagent C is sodium hydroxide solution (5.0mol / L), and the detection wavelength is 410nm;

[0113] (III) Online analysis of samples:

[0114] 6) C 新鲜 Determination: ① Collect the newly prepared slurry of different brands at the start of production on the production line, use steps (a) and (b) to detect the content of nitrate ions in the newly prepared slurry, and calculate the average value of the nitrate content in the newly prepared slurry during the production of the brand as the fresh slurry of the brand, recorded as C0; ② Take a sample of the newly prepared slurry and place it in a constant temperature shaking incubator at 50°C, place it in a sealed state, and take samples every 0.5 hours to detect NO3 - The pulp is prepared into a substrate, dried at 90℃~120℃, cut into shreds and rolled into cigarettes; then a sensory evaluation is performed with reference to "YC / T 498-2014 Sensory Evaluation Method for Reconstituted Tobacco (Papermaking Method)"; among them, the one with natural tobacco aroma, sufficient tobacco flavor and no rancid smell is fresh pulp, and the nitrate ion content in the last sample determined as fresh pulp is taken as C 新鲜 ;

[0115] 7) Model establishment: ① The content of nitrate ions in the slurry sample at a certain moment is taken as Cx, and the K value at a certain moment is calculated using formula (1); the formula (1) is implanted into the data processor storage module 27 to complete the establishment of the slurry freshness determination model; ② The K value is calculated according to formula (1), when K>1, it means that white water is unavailable; when K<1, it means that white water is available;

[0116] 8) Determine the freshness of the tested slurry based on the spectral detection results of the slurry sample: Detect the content of nitrate ions in the production slurry according to step (1) and step (2), and according to the model judgment result, when K < 1, the slurry is fresh and enters the next production process; when K > 1 or K = 1, the slurry enters the slurry temporary storage tank 28 for post-processing;

[0117]

[0118] Formula (1) is the calculation formula for determining the freshness of the slurry at a certain moment;

[0119] Where: K: the freshness judgment value of the pulp at a certain moment, dimensionless;

[0120] C0: average content of nitrate ions in the newly prepared pulp at the start of reconstituted tobacco production, mg / L;

[0121] C 新鲜 : The nitrate ion content in the last sample of the fresh slurry determined in step 6), mg / L;

[0122] Cx: The content of nitrate ions in the reconstituted tobacco slurry at a certain moment during production operation, mg / L.

[0123] Application Example 1

[0124] The system described in Example 1 and the method described in Example 2 are applied to the production of reconstituted tobacco. Specifically, the reconstituted tobacco is TS-01 brand reconstituted tobacco. The specific steps are as follows:

[0125] (I) Pretreatment of slurry samples:

[0126] 1) Using a first liquid pump 11 (specifically a peristaltic pump) to transport 3% of reconstituted tobacco slurry by mass into a plate filter 12, filtering is performed using a grid of the plate filter 12, the grid aperture is 80 meshes, and larger fibers and other larger solid particles in the slurry are retained in the grid, and the operating pressure of the peristaltic pump is ≤0.25 MPa;

[0127] 2) The slurry after the removal of larger fibers and other larger solid particles is sent to the bag filter 14 by using the second liquid pump 13 (specifically a peristaltic pump). The filter bag 141 of the bag filter 14 has a pore size of 500 meshes, which can remove fine fibers and smaller solid particles in the slurry;

[0128] 3) After filtering through the bag filter 14, a slurry filtrate is obtained, and the slurry filtrate is sent to the ceramic microfiltration membrane filter 15 through the first feed pipe 151 for re-filtration. The pore size of the microfiltration membrane in the ceramic microfiltration membrane filter 15 is 0.45 μm, the operating pressure is 3.0 Bar, and the molecular weight cutoff is 100,000-500,000. The fine fibers and smaller solid particles in the slurry enter the slag discharge port 142 of the bag filter 14. The slag discharge port 142 is cleaned with clean water five times to remove impurities such as fine fibers, particles, and proteins, and a clear, slightly yellow filtrate is obtained, which is the sample to be tested after slurry pretreatment;

[0129] (II) Online determination of nitrate ions in filtrate samples

[0130] 4) 4 mL of slurry filtrate is automatically injected into valve II 21 at a flow rate of 1 mL / min using a plunger pump, and then the sample is brought into an online solid phase extraction column (SPE purification column) 22 (filler particle size range is 45 nm, dosage is 300 mg) by 16 mL of pure water. The filler of the online solid phase extraction column (SPE purification column) 22 is activated carbon, and the pigment in the slurry sample is retained in the online solid phase extraction column (SPE purification column) 22, while the nitrate ions are not retained. Then the sample enters valve I 23, and then enters the subsequent water sample detection pool 24 through valve I 23;

[0131] Then, pure water and acetonitrile are used in turn to clean the sample matrix (pigment) trapped on the online solid phase extraction column (SPE purification column) 22 into the waste liquid, and valve II 21 is used to realize the cleaning and regeneration of the online solid phase extraction column (SPE purification column) 22 (specifically, acetonitrile is introduced from the P position (second inlet end) of valve II 21, transported to the online solid phase extraction column (SPE purification column) 22 through the C position (first outlet end), and then transported to the W position (fourth outlet end) of valve I 23 through the S position (third inlet end) of valve I 23, and the waste liquid is discharged to complete the cleaning and regeneration of the SPE purification column), the flow rate of pure water and acetonitrile is 2mL / min, and the cleaning process is to first rinse with pure water for 5min, then rinse with acetonitrile for 5min, and so on. The cleaning cycle;

[0132] 5) Using the detection end of the electrochemical detector 252 to detect the nitrate of the sample in the water sample detection pool 24, the nitrate separation or color development module 251 can convert the water quality signal emitted by the electrochemical detector 252 into an analog signal, and the nitrate separation or color development module 251 then transmits the detected water quality analog signal to the A / D acquisition module 26, and then the A / D acquisition module 26 can convert the analog signal emitted by the nitrate separation or color development module 251 into a digital signal that can be processed by the processor storage module 27, and transmit it to the processor storage module 27, and perform calculations;

[0133] The nitrate ion content in the water sample detection pool 24 was determined by the chromic acid method. The nitrogen-nitrate standard solution was 10 mg / L. The solution was reacted at room temperature (25±5°C) for 10 min under concentrated sulfuric acid conditions, then cooled to room temperature, and the pH was adjusted to neutral using a sodium hydroxide solution (5.0 mol / L). The solution was measured at 410 nm (blank was automatically deducted).

[0134] (III) Online automatic analysis of samples

[0135] 6) C 新鲜 Determination: ① For the newly prepared pulp of reconstituted tobacco brand TS-01 at the start of production, use steps (a) and (b) to detect the content of nitrate ions in the newly prepared pulp, and calculate the average value of the nitrate content in the newly prepared pulp during the production of the brand as the fresh pulp of the brand, recorded as C0; ② Then take a sample of the newly prepared pulp and place it in a constant temperature shaking incubator at 50°C, place it in a sealed state, and take a sample every 0.5 hours to detect NO3 - The pulp is prepared into a base sheet, dried at 90℃~120℃, cut into shreds and rolled into cigarettes; then refer to "YC / T 498-2014 Sensory Evaluation Method for Reconstituted Tobacco (Papermaking Method)", and the pulp with natural tobacco aroma, sufficient tobacco flavor and no rancid smell is fresh pulp. The nitrate ion content in the last sample determined as fresh pulp is taken as C 新鲜 , the specific data are shown in Table 1; According to Table 1, C0 is 38.72 mg / L, C 新鲜 22.63 mg / L;

[0136] 7) Model establishment: ① The content of nitrate ions in the slurry sample at a certain moment is taken as Cx, and the K value at a certain moment is calculated using formula (1); ② Formula (1) is implanted into the data processor storage module 27 to complete the establishment of the slurry freshness determination model; the K value is calculated according to formula (1), when K>1, it means that white water is unavailable; when K<1, it means that white water is available;

[0137] 8) Determine the freshness of the tested slurry based on the spectral detection results of the slurry sample: Detect the content of nitrate ions in the production slurry according to step (1) and step (2), and according to the model judgment result, when K < 1, the slurry is fresh and enters the next production process; when K > 1 or K = 1, the slurry enters the slurry temporary storage tank 28 for post-processing;

[0138]

[0139] Formula (1) is the calculation formula for determining the freshness of the slurry at a certain moment;

[0140] Where: K: the freshness judgment value of the pulp at a certain moment, dimensionless;

[0141] C0: average content of nitrate ions in the newly prepared pulp at the start of reconstituted tobacco production, mg / L;

[0142] C 新鲜 : The nitrate ion content in the last sample of the fresh slurry determined in step 6), mg / L;

[0143] Cx: The content of nitrate ions in the reconstituted tobacco slurry at a certain moment during the production operation, mg / L. The test results and sensory evaluation results are shown in Table 1. As shown in Table 1, the simulated production of reconstituted tobacco slurry, the nitrate ion concentration in the newly prepared slurry is 38.72 mg / L, recorded as C0. When the slurry is placed in a constant temperature incubator at 50°C for 5.5 hours, the nitrate ion concentration in the slurry is 22.63 mg / L. The sensory evaluation is that the tobacco aroma is natural, the tobacco flavor is sufficient, and there is no rancid smell. The sensory evaluation is marked as fresh slurry. When the slurry is placed in a constant temperature incubator at 50°C for 6 hours, the sensory evaluation is that the tobacco aroma is weak, the tobacco flavor is light, and there is a small amount of acidic smell. The evaluation conclusion is that it is no longer fresh. When it is placed for 5.5 hours, the nitrate ion concentration is marked as C fresh.

[0144] Table 1 Slurry C 新鲜 Determination

[0145]

[0146] Table 2 shows the freshness and operating status of the pulp when the production line is continuously running for 24 hours based on the pulp marked as fresh C0 and C in Table 1. Table 2 shows that this method can be used to monitor the freshness of reconstituted tobacco pulp, ensuring the freshness of the pulp and product quality in the reconstituted tobacco production process, and avoiding pollution of the production system caused by stale pulp.

[0147] Table 2 Slurry monitoring of the production line running continuously for 24 hours

[0148] Detection time Cx(mg / L) K Value Judgment result Processing Flow October 7, 8:00 36.21 K＜1 Fresh Next process October 7, 9:00 35.14 K＜1 Fresh Next process October 7, 10:00 28.12 K＜1 Fresh Next process October 7, 11:00 30.25 K＜1 Fresh Next process October 7, 12:00 32.33 K＜1 Fresh Next process October 7, 13:00 35.26 K＜1 Fresh Next process October 7, 14:00 30.87 K＜1 Fresh Next process October 7, 15:00 32.56 K＜1 Fresh Next process October 7, 16:00 29.15 K＜1 Fresh Next process October 7, 17:00 32.32 K＜1 Fresh Next process October 7, 18:00 33.23 K＜1 Fresh Next process October 7, 19:00 33.12 K＜1 Fresh Next process October 7, 20:00 32.45 K＜1 Fresh Next process October 7, 21:00 30.25 K＜1 Fresh Next process October 7, 22:00 29.78 K＜1 Fresh Next process October 7, 23:00 31.56 K＜1 Fresh Next process October 7, 24:00 31.23 K＜1 Fresh Next process October 8, 01:00 31.25 K＜1 Fresh Next process October 8, 02:00 31.56 K＜1 Fresh Next process October 8, 03:00 30.12 K＜1 Fresh Next process October 8, 04:00 29.33 K＜1 Fresh Next process October 8, 05:00 28.45 K＜1 Fresh Next process October 8, 06:00 26.46 K＜1 Fresh Next process October 8, 07:00 22.32 K≈1 To be determined Slurry storage tank October 8, 08:00 26.89 K＜1 Fresh Next process

[0149] The system and method of the present invention realizes the online monitoring and prediction of the freshness of reconstituted tobacco slurry without causing pollution of the production system and products due to slurry quality problems, thereby improving production efficiency and ensuring product quality and safety.

[0150] The beneficial effects of the present invention are as follows: it realizes the online monitoring and prediction of the freshness of reconstituted tobacco slurry in the tobacco industry, solves the long-standing industry problem of delayed evaluation of reconstituted tobacco slurry and inability to predict in real time, improves the utilization rate of tobacco resources, reduces material loss, reduces waste emissions, improves the clean production level of reconstituted tobacco, effectively ensures product quality and safety, and provides strong support for the green and sustainable development of the tobacco industry.

[0151] Finally, it should be noted that the above are only preferred embodiments of the present invention and the principles of the application technology. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include more other effective embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An online monitoring system for pulp freshness in the production process of reconstituted tobacco leaves by papermaking method, characterized in that: It includes an automatic sampling control unit, and a detection and automatic analysis unit; The automatic injection control unit comprises a first liquid pump, a plate filter, a second liquid pump, a bag filter and a ceramic microfiltration membrane filter; The liquid inlet end of the plate filter is connected to a first liquid inlet pipe, the first liquid pump is arranged on the first liquid inlet pipe, the liquid outlet end of the plate filter is connected to a first liquid outlet pipe, the second liquid pump is arranged on the first liquid outlet pipe; The bag filter is provided with a feed port, a discharge port and a slag discharge port; The liquid outlet end of the plate filter is connected to the feed inlet of the bag filter through the first liquid outlet pipe; The discharge port of the bag filter is connected to the feed end of the ceramic microfiltration membrane filter through the first feed pipe; the discharge end of the ceramic microfiltration membrane filter is connected to the first discharge pipe; The detection and automatic analysis unit includes a WION-2000NO3 ion selective electrode type online nitrate ion detection device, an online solid phase extraction column, a slurry temporary storage tank, a first slurry outflow pipe and a second slurry outflow pipe; The WION-2000NO3 ion selective electrode type online nitrate ion detection device includes valve I, valve II, water sample detection pool, nitrate detection unit, A / D acquisition module, and processor storage module; The nitrate detection unit comprises a nitrate separation or color development module and an electrochemical detector; The valve II is provided with a first inlet end, a second inlet end, a first outlet end, and a second outlet end; The valve 1 is provided with a third inlet end, a fourth inlet end, a third outlet end and a fourth outlet end; The first discharge pipe is connected to the first inlet end of the valve II, the first outlet end of the valve II is connected to the inlet end of the online solid phase extraction column through a pipeline, the outlet end of the online solid phase extraction column is connected to the third inlet end of the valve I through a pipeline, and the third outlet end of the valve I is connected to the feed end of the water sample detection pool through a pipeline; The electrochemical detector is provided with a detection end and a water quality signal output end. The detection end of the electrochemical detector is connected to the water sample detection pool and can detect the water quality in the water sample detection pool. The water quality signal output end of the electrochemical detector is connected to the nitrate separation or color development module signal, and the nitrate separation or color development module can convert the water quality signal emitted by the electrochemical detector into an analog signal and connect it to the A / D acquisition module signal; The A / D acquisition module is provided with an analog signal input terminal and a digital signal output terminal, and the A / D acquisition module can convert the analog signal sent by the nitrate separation or color development module into a digital signal that can be processed by the processor storage module; The analog signal output terminal of the nitrate separation or color development module is signal-connected to the signal input terminal of the A / D acquisition module; the processor storage module is provided with a digital signal input terminal, and the digital signal output terminal of the A / D acquisition module is signal-connected to the digital signal input terminal of the processor storage module.

2. The online monitoring system for pulp freshness in the papermaking process of reconstituted tobacco according to claim 1 is characterized in that: The plate filter is equipped with a grille; the bag filter is equipped with a filter bag.

3. The online monitoring system for pulp freshness in the papermaking process of reconstituted tobacco according to claim 1 is characterized in that: A cleaning liquid inlet is also provided in the middle of the bag filter, and a cleaning pipe is connected to the cleaning liquid inlet.

4. The online monitoring system for pulp freshness in the papermaking process of reconstituted tobacco according to claim 1 is characterized in that: The automatic sampling control unit also includes a backwashing and dosing tank and a membrane cleaning water tank.

5. The online monitoring system for pulp freshness in the papermaking process of reconstituted tobacco according to claim 1 is characterized in that: The water sample detection pool is also connected to a storage tank for storing slurry in the next process through a first slurry outflow pipe, and a first solenoid valve is provided on the first slurry outflow pipe; The water sample detection pool is also connected to the inlet end of the slurry temporary storage tank through a second slurry outflow pipe. A second solenoid valve is provided on the second slurry outflow pipe. The processor storage module is interlocked with the first solenoid valve and the second solenoid valve for control.

6. A monitoring method using the online monitoring system according to any one of claims 1 to 5, characterized in that: The steps include: (I) Pretreatment of slurry samples 1) using a first liquid pump to transport the reconstituted tobacco slurry into a plate filter, and filtering it using a grid of the plate filter; 2) using a second liquid pump to deliver the slurry filtered by the grid into a bag filter; 3) filtering through a bag filter to obtain a slurry filtrate, feeding the slurry filtrate into a ceramic microfiltration membrane filter through a first feed pipe for re-filtration, and filtering through the ceramic microfiltration membrane filter to obtain a membrane-filtered slurry filtrate, which is the sample to be tested after slurry pre-treatment; (II) Online determination of nitrate ions in the filtrate sample after slurry pretreatment 4) injecting the sample to be tested after slurry pretreatment into valve II through the first inlet port in an automatic injection manner, and simultaneously introducing pure water into valve II, so that the sample is brought into the online solid phase extraction column by the pure water; The matrix in the sample is retained in the online solid phase extraction column, and the nitrate ions are not retained. Then the sample enters valve I and then enters the subsequent water sample detection pool through valve I; 5) using the detection end of the electrochemical detector to detect the nitrate of the sample in the water sample detection pool, the nitrate separation or color development module can convert the water quality signal emitted by the electrochemical detector into an analog signal, and the nitrate separation or color development module then transmits the detected water quality analog signal to the A / D acquisition module, and then the A / D acquisition module converts the analog signal emitted by the nitrate separation or color development module into a digital signal that can be processed by the processor storage module, and transmits it to the processor storage module, and performs calculations; (III) Online sample analysis 6) Collect newly prepared slurry, use step (1) and step (2) to detect the content of nitrate ions in the newly prepared slurry, calculate the average value of the nitrate content in the newly prepared slurry, sample the newly prepared slurry, dry it, prepare it into a substrate, conduct sensory evaluation, establish a slurry freshness determination model, and determine the freshness of the tested slurry based on the spectral detection results of the slurry samples.

7. The method according to claim 6, characterized in that The grid aperture of the plate filter is 50-100 meshes. When the first liquid pump is a peristaltic pump, the operating pressure is ≤0.25MPa; when the first liquid pump is a metering pump, the operating pressure is ≤60Mpa.

8. The method according to claim 6, characterized in that The pore size of the filter bag of the bag filter is 500-800 mesh; the pore size of the microfiltration membrane in the ceramic microfiltration membrane filter is 0.22-0.80μm, and the operating pressure is ≤6.0BAR.

9. The method according to claim 6, characterized in that The filler of the online solid phase extraction column is any one of activated carbon, C18 silica gel, Florisil, and magnesium silicate, and the filler particle size ranges from 40 to 60 nm.

10. The method according to claim 6, characterized in that The nitrate detection method is the cadmium reduction method or the chromic acid method; the slurry freshness determination model formula is: Where: K: pulp freshness judgment value at a certain time, dimensionless; C0: average content of nitrate ions in newly prepared pulp at the start of reconstituted tobacco production, mg / L; C 新鲜 : The nitrate ion content in the last sample rated as fresh pulp, mg / L; Cx: The nitrate ion content in the reconstituted tobacco pulp at a certain moment during the production run, mg / L; According to step (1) and step (2), the content of nitrate ions in the production running slurry is detected. According to the model judgment result, when K is less than 1, the slurry enters the next production process freshly; when K is greater than 1 or K is equal to 1, the slurry is temporarily stored and processed after judgment.

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