Papermaking process and system for tobacco sheet semi-hybrid counter-current extraction

Abstract

The present application relates to the technical field of tobacco sheet, and mainly relates to a papermaking tobacco sheet semi-division semi-combination type mixed countercurrent extraction process and system. The present application realizes the process target of first separation and extraction by separately processing tobacco stems, removes most of the undesirable components in the tobacco stems, and retains the fiber content while defibrating the processed tobacco stems. The present application directly puts wood pulp into a mixed pulper for processing, thereby omitting a special wood pulp processing path and equipment, avoiding the problems of formula deviation caused by additional liquid introduced by wood pulp pretreatment, and the like. The present application uses an extraction buffer tank to realize the continuous mixing extraction target of "batching of material mixing and continuous of subsequent extraction". The present application uses a mixing pump with high concentration tolerance to reduce process mixing, reduce the amount of liquid added, and ensure that the concentration of the first extraction liquid is controlled. The process of the present application is simple, the equipment investment is small, the occupied area is small, the realization efficiency is high, and the present application has good application value and economic value for the current production of tobacco sheets.

Description

Technical Field

[0001] This invention relates to the field of tobacco sheet technology, and in particular to a semi-separated and semi-combined countercurrent extraction process and system for tobacco sheets in papermaking. Background Technology

[0002] Tobacco sheets produced by papermaking are tobacco products made from tobacco waste such as tobacco stems and tobacco leaves from cigarette production, processed and reconstituted using papermaking technology. They are characterized by low density, high filling value, excellent processability, and strong plasticity in terms of product quality and style. Driven by the goal of improving the quality of Chinese-style cigarette products, the production technology and quality of tobacco sheets have developed rapidly, and in recent years they have become an important raw material for Chinese-style cigarettes.

[0003] Currently, the tobacco sheet production industry adopts a "separate-then-combined" integrated process. This involves first soaking the tobacco raw material in hot water (also known as extraction), then squeezing it dry to achieve solid-liquid separation. The liquid phase (extract) is then purified, concentrated, and flavored to form a coating liquid. The solid phase (slurry) undergoes pulping, fiber addition (mainly wood pulp), and filler addition (mainly light calcium carbonate), followed by sheet forming to create a substrate. The coating process then applies the coating liquid to the substrate for recombination, followed by drying and slitting to form tobacco sheets suitable for cigarette processing. As the understanding and research of extraction processes deepen within the tobacco sheet industry, extraction techniques are gradually evolving towards mixed extraction: 1) Pre-soaking the tobacco stems, also known as pre-extraction, removes some undesirable components; 2) After pre-extraction, the tobacco stems are mixed with the tobacco sheet powder, followed by multi-stage extraction to separate the solid and liquid components of the tobacco, a process known as "semi-separate, semi-combined" mixed extraction.

[0004] However, within the tobacco sheet production industry, the application of the mixed extraction mode varies among different manufacturers. For example: 1) One manufacturer's mixed extraction process mainly involves mixing tobacco stems and tobacco flakes, with an additional processing path and corresponding equipment for wood pulp to achieve process objectives such as pulping, loosening, beating, and blending. This process suffers from problems such as complex process paths, high equipment investment, numerous control points, and low controllability of blending ratios (blending accuracy is affected by multiple metering units); 2) In another manufacturer's mixed extraction process, the wood pulp is pre-crushed to approximately 1.0*1.0cm and mixed into the tobacco flake storage tank, then enters the mixing pulper along with the tobacco flakes. This process still requires additional equipment. The separate wood pulp pretreatment process and corresponding crushing and metering equipment have several drawbacks: 1) The wood pulp fragments are difficult to disperse evenly after entering the pulper, and there are metering errors between batches (tanks); 2) In the mixed extraction process of three manufacturers, the material after squeezing and separation is mixed with extraction water and then pumped into the extraction spiral, resulting in a series of problems such as excessive material accumulation in the extraction spiral, difficulty in cleaning, unsatisfactory mixing effect, and leakage; 3) In the mixed extraction process of four manufacturers, tobacco stems are dry-crushed to about 0.5cm before being pre-extracted together with wood pulp, which severely damages the length of the fiber material in the tobacco stems and affects the function of the fibers. As for other manufacturers that do not use the mixed extraction process, they adopt a separate extraction and separate pulping mode, which has a more complex process path, requires more equipment investment and occupies more space, and is no longer conducive to the development of existing process technologies.

[0005] Therefore, it is of great significance to improve the existing mixed extraction process and design a semi-separate and semi-combined mixed countercurrent extraction process with a simpler process path, more economical equipment investment, and smaller footprint. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a semi-separated and semi-combined mixed countercurrent extraction process and system for tobacco sheets in papermaking. By implementing a mixed countercurrent extraction mode in which tobacco stems and tobacco leaves are extracted separately first and then mixed for extraction, without adding additional wood pulp processing paths and equipment, and without damaging the fibers in the tobacco stems, higher extraction and separation efficiency is achieved with a simpler process flow and less equipment investment, which has good application value.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] The first aspect of this invention provides a semi-separated and semi-combined countercurrent extraction process for tobacco sheets in a papermaking method, comprising the following steps:

[0009] 1) Pre-extraction of tobacco stems: Add hot water for extraction, heated stem liquid and tobacco stems to a tobacco stem pulper, mix and stir to obtain mixture one; perform vibration screening on mixture one to obtain extracted tobacco stems and free liquid; perform defiberization treatment on the extracted tobacco stems, and perform solid-liquid separation on the defiberized material to obtain pre-extracted tobacco stems and liquid phase;

[0010] 2) Mixed extraction and pulping: Add secondary extract, primary extract, wood pulp, wood chips and pre-extracted tobacco stems to a mixed pulper, mix and stir to obtain extract material one;

[0011] 3) Continuous extraction: The first-stage material is squeezed dry to obtain a first-stage squeezed material and a first-stage extract. The first-stage squeezed material is sent to a second-stage mixing pump to mix with the third-stage extract. After the second-stage extraction, it is squeezed dry again to obtain a second-stage squeezed material and a second-stage extract. The second-stage extract is recycled back to the second-stage squeezed material, which is then sent to a third-stage mixing pump to mix with hot water for extraction. After the third-stage extraction, it is squeezed dry again to obtain a third-stage squeezed material and a third-stage extract. The third-stage squeezed material is mixed with diluted white water and then sent to the pulping section. The first-stage and second-stage extracts are recycled back to the mixing pulper, and the third-stage extract is recycled back to the second-stage mixing pump.

[0012] A second aspect of the present invention provides a semi-separated and semi-combined countercurrent extraction system for tobacco sheets in a papermaking process, comprising a pre-extraction unit, a mixing extraction unit, and a continuous extraction unit;

[0013] The pre-extraction unit includes a tobacco stem pulper, a tobacco stem vibrating screen, a defiberizer, and a tobacco stem desqueezer. The tobacco stem pulper has an extraction hot water inlet, a heated stem liquid inlet, a tobacco stem inlet, and a mixed material outlet. The tobacco stem vibrating screen has a mixed material inlet, a free liquid outlet, and an extracted tobacco stem outlet; the mixed material inlet is connected to the mixed material outlet of the tobacco stem pulper. The defiberizer has an extracted tobacco stem inlet and a defibered material outlet; the extracted tobacco stem inlet is connected to the extracted tobacco stem outlet of the tobacco stem vibrating screen. The tobacco stem desqueezer has a defibered material inlet, a pre-extracted tobacco stem outlet, and a liquid phase outlet; the defibered material inlet is connected to the defibered material outlet of the defiberizer.

[0014] The mixing and extraction unit includes a mixing pulper and an extraction buffer tank; the mixing pulper is provided with a secondary extract inlet, a primary extract inlet, a wood pulp inlet, a pre-extracted tobacco stem inlet, a chip inlet, and an extraction material outlet; the pre-extracted tobacco stem inlet is connected to the pre-extracted tobacco stem outlet of the tobacco stem dewatering machine of the pre-extraction unit; the inlet of the extraction buffer tank is connected to the extraction material outlet of the mixing pulper.

[0015] The continuous extraction unit includes a primary extruder, a primary extractant tank, a secondary mixing pump, a secondary extruder, a secondary extractant tank, a tertiary mixing pump, a tertiary extruder, and a tertiary extractant tank; the primary extruder, the secondary mixing pump, the secondary extruder, the tertiary mixing pump, and the tertiary extruder are connected sequentially; the primary extruder has an inlet for the extraction material and an outlet for the primary extractant, the inlet for the extraction material being connected to the outlet of the extraction buffer tank of the mixing extraction unit; the secondary mixing pump has an inlet for the tertiary extractant; and the secondary extruder has an outlet for the tertiary extractant. The three-stage mixing pump is equipped with an extraction hot water inlet; the three-stage extruder is equipped with a three-stage extruded material outlet and a three-stage extract outlet; the three-stage extruded material outlet is connected to the pulping section; the inlet of the first-stage extract tank is connected to the first-stage extract outlet of the first-stage extruder, and the outlet is connected to the first-stage extract inlet of the mixing pulper of the mixing extraction unit; the second-stage extraction tank is connected to the second-stage extract outlet of the second-stage extruder and the second-stage extract inlet of the mixing pulper of the mixing extraction unit; the third-stage extraction tank is connected to the third-stage extract inlet of the second-stage mixing pump.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The papermaking tobacco sheet semi-separate and semi-combined countercurrent extraction process provided by this invention achieves the process goal of separate extraction by treating tobacco stems separately, thereby removing most of the undesirable components in the tobacco stems. While defiberizing the treated tobacco stems, the fiber content is retained. The wood pulp is directly fed into the mixing pulper for processing, eliminating the need for a dedicated wood pulp processing process and corresponding equipment, and avoiding problems such as formula deviation caused by the introduction of additional liquids during wood pulp pretreatment. The continuous mixing extraction goal of "batch mixing of materials and continuous subsequent extraction" is achieved by using an extraction buffer tank. The concentration-tolerant mixing pump is used to reduce process mixing and the amount of liquid added, ensuring that the concentration of the primary extract is controlled.

[0018] 2. The papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction system provided by the present invention achieves the goal of continuous mixing and extraction by batch mixing of various materials and continuous subsequent extraction through the interaction between the extraction buffer tank volume and the mixing volume of the mixing pulper.

[0019] 3. Compared with other extraction processes, the papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction process provided by this invention is simple, requires less equipment investment, occupies less space, and achieves high efficiency. It has good application and economic value for the current production of tobacco sheets. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a semi-separated and semi-combined countercurrent extraction system for tobacco sheet processing according to an embodiment of the present invention.

[0021] Figure reference numerals: 1-Tobacco stem pulper; 2-Tobacco stem vibrating screener; 3-Fiber debonder; 4-Tobacco stem depressor; 5-Mixing pulper; 6-Extraction buffer tank; 7-Primary depressor; 8-Primary extract tank; 9-Secondary mixing pump; 10-Secondary depressor; 11-Secondary extract tank; 12-Tertiary mixing pump; 13-Tertiary depressor; 14-Tertiary extract tank; 15-Primary feed pump; 16-Extraction hot water tank; 17-Stem broth collection tank; 18-Tobacco stem pump; 19-Pre-extraction post-tobacco stem buffer silo; 20-Stem broth heating tank; 21-Discharge pump; 22-Pre-tap mixing pump; 23-Dilution white water pump; 24-Pre-tap pulp tank; 25-Flakes buffer silo. Detailed Implementation

[0022] The following details the semi-separated and semi-combined countercurrent extraction system and process for tobacco sheet processing in the papermaking method of this invention.

[0023] To overcome the problems existing in the current process, the inventors achieved the process goal of separate extraction by treating tobacco stems separately, thereby removing most of the undesirable components from the tobacco stems while retaining their fiber content and integrity. By directly feeding the wood pulp into the mixing pulper, the process eliminates the need for a separate wood pulp treatment process path and corresponding equipment, thus avoiding the introduction of additional liquids that could cause formulation deviations during wood pulp pretreatment. The use of an extraction buffer tank achieves the goal of batch mixing of various materials and continuous subsequent extraction, resulting in a simple process with low equipment investment, small footprint, and high efficiency in achieving the desired results.

[0024] This invention provides a semi-separated and semi-combined countercurrent extraction process and system for tobacco sheets in papermaking, the specific technical solution of which is as follows:

[0025] A papermaking process for tobacco sheets using a semi-separated, semi-combined, countercurrent extraction method includes the following steps:

[0026] 1) Pre-extraction of tobacco stems: Add hot water for extraction, heated stem liquid and tobacco stems to a tobacco stem pulper, mix and stir to obtain mixture one; perform vibration screening on mixture one to obtain extracted tobacco stems and free liquid; perform defiberization treatment on the extracted tobacco stems, and perform solid-liquid separation on the defiberized material to obtain pre-extracted tobacco stems and liquid phase;

[0027] 2) Mixed extraction and pulping: Add secondary extract, primary extract, wood pulp, wood chips and pre-extracted tobacco stems to a mixed pulper, mix and stir to obtain extract material one;

[0028] 3) Continuous extraction: The first-stage material is squeezed dry to obtain a first-stage squeezed material and a first-stage extract. The first-stage squeezed material is sent to a second-stage mixing pump to mix with the third-stage extract. After the second-stage extraction, it is squeezed dry again to obtain a second-stage squeezed material and a second-stage extract. The second-stage extract is recycled back to the second-stage squeezed material, which is then sent to a third-stage mixing pump to mix with hot water for extraction. After the third-stage extraction, it is squeezed dry again to obtain a third-stage squeezed material and a third-stage extract. The third-stage squeezed material is mixed with diluted white water and then sent to the pulping section. The first-stage and second-stage extracts are recycled back to the mixing pulper, and the third-stage extract is recycled back to the second-stage mixing pump.

[0029] In some embodiments of the present invention, in step 1), when the tobacco stem pulper is started, hot water for extraction and hot stem liquid are added simultaneously, and then tobacco stems are added.

[0030] In some embodiments of the present invention, in step 1), based on absolutely dry material, the total volume of extraction hot water and heating stem liquid added per 100 kg of tobacco stems is 0.55–0.65 m³. 3 The volume percentage of hot water used for extraction is 55%–65%, and the volume percentage of heated stem broth is 35%–45%.

[0031] In some embodiments of the present invention, in step 1), the mixing and stirring time is 15 to 25 minutes.

[0032] In some embodiments of the present invention, in step 1), the dryness of the extracted tobacco stems is 12% to 17%.

[0033] In some embodiments of the present invention, in step 1), the dryness of the pre-extracted tobacco stems is 33% to 37%.

[0034] In some embodiments of the present invention, step 2), specifically involving adding secondary extract, primary extract, wood pulp, tobacco flakes, and pre-extracted tobacco stems to the mixing pulper, includes: simultaneously adding secondary extract and primary extract when starting the mixing pulper; adding wood pulp when the added amounts of secondary and primary extracts reach 20-25 times the weight of the wood pulp; stirring for 3-8 minutes; and simultaneously adding tobacco flakes and pre-extracted tobacco stems after the addition of secondary and primary extracts is complete. Preferably, the secondary and primary extracts are added at a constant flow rate for easy control.

[0035] In some embodiments of the present invention, in step 2), the mass ratio of the added tobacco flakes to the added tobacco stems in step 1) is 40-60:40-60, based on the amount of absolutely dry material; and the weight of wood pulp added per 100 kg of tobacco stems and tobacco flakes is 9-11 kg, based on the amount of absolutely dry material.

[0036] In some embodiments of the present invention, in step 2), based on absolutely dry material, the total volume of the secondary extract and primary extract added per 100 kg of tobacco stems and tobacco flakes is 0.55–0.65 m³. 3 The volume percentage of the secondary extract is 55%–65%, and the volume percentage of the primary extract is 35%–45%.

[0037] In some embodiments of the present invention, in step 2), the mixing and stirring time is 15 to 25 minutes.

[0038] In some embodiments of the present invention, in step 3), the processing efficiency of the first-stage squeezing, second-stage squeezing, and third-stage squeezing is kept consistent, and the squeezing dryness is 33% to 37% for each stage. The material squeezed in each stage falls directly into the next stage mixing pump and mixes with the next stage extraction liquid.

[0039] In some embodiments of the present invention, in step 3), based on absolutely dry material, the amount of tertiary extract added at the secondary mixing pump is 0.30–0.40 mg / L. 3 The extraction hot water added at the three-stage mixing pump is 0.30–0.40 m³. 3 .

[0040] A second aspect of the present invention provides a semi-separated, semi-combined, countercurrent extraction system for tobacco sheets used in papermaking, such as... Figure 1 As shown, it includes a pre-extraction unit, a mixed extraction unit, and a continuous extraction unit;

[0041] The pre-extraction unit includes a tobacco stem pulper 1, a tobacco stem vibrating screen 2, a defiberizer 3, and a tobacco stem desqueezer 4. The tobacco stem pulper 1 has an extraction hot water inlet, a heated stem liquid inlet, a tobacco stem inlet, and a mixed material outlet. The tobacco stem vibrating screen 2 has a mixed material inlet, a free liquid outlet, and an extracted tobacco stem outlet; the mixed material inlet is connected to the mixed material outlet of the tobacco stem pulper 1. The defiberizer 3 has an extracted tobacco stem inlet and a defibered material outlet; the extracted tobacco stem inlet is connected to the extracted tobacco stem outlet of the tobacco stem vibrating screen 2. The tobacco stem desqueezer 4 has a defibered material inlet, a pre-extracted tobacco stem outlet, and a liquid phase outlet; the defibered material inlet is connected to the defibered material outlet of the defiberizer 3.

[0042] The mixing and extraction unit includes a mixing pulper 5 and an extraction buffer tank 6; the mixing pulper 5 is provided with a secondary extract inlet, a primary extract inlet, a wood pulp inlet, a pre-extracted tobacco stem inlet, a chip inlet, and an extraction material outlet; the pre-extracted tobacco stem inlet is connected to the pre-extracted tobacco stem outlet of the tobacco stem dewatering machine 4 of the pre-extraction unit; the inlet of the extraction buffer tank 6 is connected to the extraction material outlet of the mixing pulper 5;

[0043] The continuous extraction unit includes a primary extruder 7, a primary extract tank 8, a secondary mixing pump 9, a secondary extruder 10, a secondary extract tank 11, a tertiary mixing pump 12, a tertiary extruder 13, and a tertiary extract tank 14; the primary extruder 7, the secondary mixing pump 9, the secondary extruder 10, the tertiary mixing pump 12, and the tertiary extruder 13 are connected sequentially; the primary extruder 7 has an extraction material inlet and a primary extract outlet, the extraction material inlet being connected to the outlet of the extraction buffer tank 6 of the mixing extraction unit; the secondary mixing pump 9 has a tertiary extract inlet; and the secondary extruder 10 has a secondary... The extraction liquid outlet is provided by the three-stage mixing pump 12, which has an extraction hot water inlet; the three-stage desqueezer 13 has a three-stage desqueezed material outlet and a three-stage extraction liquid outlet, and the three-stage desqueezed material outlet is connected to the pulping section; the inlet of the first-stage extraction liquid tank 8 is connected to the first-stage extraction liquid outlet of the first-stage desqueezer 7, and the outlet is connected to the first-stage extraction liquid inlet of the mixing pulper 5 of the mixing extraction unit; the second-stage extraction tank 11 is connected to the second-stage extraction liquid outlet of the second-stage desqueezer 10 and the second-stage extraction liquid inlet of the mixing pulper 5 of the mixing extraction unit; and the third-stage extraction tank 14 is connected to the third-stage extraction liquid inlet of the second-stage mixing pump 9.

[0044] In some embodiments of the present invention, a primary feed pump 15 is provided on the connecting pipeline between the extraction buffer tank 6 and the primary extruder 7, for conveying the extracted material in the extraction buffer tank 6 to the primary extruder 7.

[0045] In some embodiments of the present invention, the volume of the extraction buffer tank 6 is 1.3 to 1.5 times the mixing volume of the mixing pulper 5, and the mixing volume of the mixing pulper 5 is 1.4 to 1.6 times the output volume of the primary feed pump 15, in order to ensure continuous discharge from the extraction buffer tank 6.

[0046] In some embodiments of the present invention, a pre-extracted tobacco stem buffer silo 19 is provided on the connecting pipeline between the tobacco stem depresser 4 and the mixing pulper 5. The inlet of the pre-extracted tobacco stem buffer silo 19 is connected to the pre-extracted tobacco stem outlet of the tobacco stem depresser 4, and the outlet of the pre-extracted tobacco stem buffer silo 19 is connected to the pre-extracted tobacco stem inlet of the mixing pulper 5.

[0047] In some embodiments of the present invention, an extraction hot water tank 16 is also included, the extraction hot water tank 16 having an outlet one and an outlet two, the outlet one being connected to the extraction hot water inlet of the tobacco stem pulper 1 of the pre-extraction unit, and the outlet two being connected to the extraction hot water inlet of the three-stage mixing pump 12 of the continuous extraction unit.

[0048] In some embodiments of the present invention, the pre-extraction unit further includes a stem liquid collection tank 17 and a stem liquid heating tank 20; the stem liquid collection tank 17 is provided with a free liquid inlet, a squeeze dryer liquid phase inlet and a stem liquid outlet, the free liquid inlet is connected to the free liquid outlet of the tobacco stem vibrating screen 2, and the squeeze dryer liquid phase inlet is connected to the liquid phase outlet of the tobacco stem squeeze dryer 4; the stem liquid heating tank 20 is provided with a stem liquid inlet and a heated stem liquid outlet, the stem liquid inlet is connected to the stem liquid outlet of the stem liquid collection tank, and the heated stem liquid outlet is connected to the heated stem liquid inlet of the tobacco stem pulper 1.

[0049] In some embodiments of the present invention, both the secondary mixing pump 9 and the tertiary mixing pump 12 are high-concentration solid-liquid mixing screw pumps. The high-concentration solid-liquid mixing screw pumps have high concentration tolerance and can transport media with a solid phase concentration of 14% to 18%. By using high-concentration solid-liquid mixing screw pumps in the continuous extraction unit, the present invention can reduce the amount of mixing and conveying equipment and the amount of liquid added, thereby ensuring that the concentration of the primary extract is controllable.

[0050] In some embodiments of the present invention, the pre-stress mixing pump 22 is a medium-concentration solid-liquid mixing screw pump, which can transport a medium with a solid concentration of 5% to 7%, which is convenient for pulping.

[0051] The following detailed description of specific embodiments of the present invention, in conjunction with preferred embodiments, further illustrates the invention. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the invention, both endpoints of each numerical range, as well as any value between the two endpoints, may be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art. Process equipment or apparatus not specifically specified in the following embodiments employs conventional equipment or apparatus in the field of papermaking tobacco sheets, such as various extraction tanks, transfer pumps, extrusion separation, liquid metering and control, etc. In addition to the specific methods, equipment, and materials used in the embodiments, if those skilled in the art possess the prior art and understand the description of the present invention, any prior art methods, equipment, and materials similar to or equivalent to those described, used in the embodiments of the present invention can be used to implement the present invention.

[0052] Example 1

[0053] A papermaking process for tobacco sheets employs a semi-separated, semi-combined, countercurrent extraction process, using methods such as... Figure 1 The system includes the following steps:

[0054] 1) Pre-extraction of tobacco stems: Start tobacco stem pulper 1, and simultaneously add 5.00m of extraction hot water to the container of tobacco stem pulper 1. 3 (From extraction hot water tank 16), heated stem liquid 4.00m 3(From the stem liquid heating tank), then add 1500 kg of tobacco stems, stir and mix for 20 minutes to obtain mixture one; mixture one is sent to tobacco stem vibrating screen 2 via tobacco stem pump 18, and the free liquid is removed by the vibrating screen to a dryness of 15% to obtain extracted tobacco stems; the extracted tobacco stems are sent to defibering machine 3 for defiberization, and the defiberized material is separated into solid and liquid by tobacco stem dewatering machine 4 to obtain pre-extracted tobacco stems and liquid phase with a dryness of 35%. The pre-extracted tobacco stems are sent to pre-extracted tobacco stem buffer silo 19 for later use; the free liquid removed by tobacco stem vibrating screen 2 and the liquid phase obtained by solid-liquid separation by tobacco stem dewatering machine 4 are sent to stem liquid collection tank 17. Part of the stem liquid in stem liquid collection tank 17 is refined and concentrated and then sent to stem liquid heating tank 20, and is returned to the container of tobacco stem pulper 1 as heated stem liquid for reuse.

[0055] 2) Mixing, Extraction, and Pulping: Start the mixing and pulping machine 5, and simultaneously add the secondary extract (from the secondary extract tank 11) and the primary extract (from the primary extract tank 8) into the container of the mixing and pulping machine 5. Continue adding until the volume reaches 7.00 ml. 3 Add 300 kg / can of wood pulp and stir for about 5 minutes; wait until the amount of secondary extract added reaches 11.00 m³. 3 / can, 7.00m of primary extract 3 When adding 1500 kg / can of tobacco flakes (from flake buffer silo 25) and pre-extracted tobacco stems (from pre-extracted tobacco stem buffer silo 19), stir for 20 minutes and then discharge the material into the extraction buffer tank 6 in one go via discharge pump 21 to obtain the first extraction material.

[0056] 3) Continuous extraction: The material to be extracted is fed through a primary feed pump at a rate of approximately 15m... 3 A continuous flow rate of / h is pumped into the primary squeezer 7 to obtain primary squeezed material and primary extract. The primary extract is sent to the primary extract tank 8 and then returned to the mixing and pulping machine 5 in step 2) for reuse. The primary squeezed material and the tertiary extract are mixed at the secondary mixing pump 9. The amount of tertiary extract used is 11.00m³ relative to 3000kg of tobacco raw material. 3 The extracted material is pumped into a secondary squeezer via a secondary mixing pump 9 to obtain secondary squeezed material and secondary extract. The secondary extract is sent to a secondary extract tank 11 and returned to the mixing and pulping machine 5 in step 2) for reuse. The secondary squeezed material is then mixed with extraction hot water at a tertiary mixing pump 12. The amount of extraction hot water used is 11.00 m³ relative to 3000 kg of tobacco raw material. 3The extracted material is pumped into a three-stage extruder 13 via a three-stage mixing pump 12, resulting in three-stage extruded material and three-stage extract. The three-stage extruded material is sent to a pre-extrusion mixing pump 22 and mixed with diluted white water pump 23 before being sent to a pre-extrusion slurry tank 24. The three-stage extract is sent to a three-stage extract tank 14 and then returned to a two-stage mixing pump 9 for reuse. The operating frequency of the first, second, and third-stage extruders is kept consistent at 16Hz, and the extrusion dryness is 35.0±1.5%. The extruded material obtained from each stage of extrusion separation falls directly into the inlet of the next stage mixing pump and is mixed with the corresponding liquid.

[0057] In this embodiment, a semi-separate and semi-combined continuous mixing extraction method is adopted to achieve the process objectives of mixing, extraction, and separation of tobacco stems, tobacco flakes, wood pulp, and extraction water. The final output dryness of the three-stage extruder is 35.5%, the concentration of the first-stage extract is 8.7%, the relative extraction rate of tobacco stem pre-extraction can reach 68%, and the relative extraction rate of the three-stage extraction can reach 89%.

[0058] One manufacturer's mixed extraction process primarily involves mixing tobacco stems and tobacco flakes. An additional processing pathway and corresponding equipment are set up for wood pulp to achieve process objectives such as pulping, loosening, beating, and blending. Since wood pulp is not involved in the mixed extraction, it cannot achieve the "network synergy" effect of squeezing the tobacco raw materials (wood pulp fibers can form a cross-network in the mixture, which can hold fine tobacco fragments, further increasing the squeezing dryness; increased squeezing dryness leads to a higher relative extraction rate). In this mixed extraction process, the final squeezing dryness is 30.0% ± 1.5%, the first-stage extract concentration is 7.0%-7.5%, the relative extraction rate of tobacco stem pre-extraction is 45%-50%, and the relative extraction rate of tertiary extraction is 80%-83%.

[0059] In the mixed extraction process of two manufacturers, the wood pulp is pre-crushed to approximately 1.0*1.0cm and mixed into a chip storage tank. Then, it enters the high-consistency pulper mixed pulper along with the chipped wood. Due to the lack of a necessary separate combing process for the wood pulp, the uniformity of the wood pulp in the mixed pulp is poor, resulting in a lower squeeze dryness compared to processes where the wood pulp is pre-compressed separately. However, it is superior to the process of manufacturer one, where the final squeeze dryness of the mixed extraction is 32.0% ± 1.5%, the first-stage extract concentration is 7.5%-8.0%, the relative extraction rate of tobacco stem pre-extraction is 50%-55%, and the relative extraction rate of tertiary extraction is 82%-84%.

[0060] Although the relevant parameters and data of the three manufacturers are basically the same, their equipment layout is more complex and has a series of problems such as excessive material accumulation in the extraction spiral, difficulty in cleaning, unsatisfactory mixing effect, and leakage.

[0061] Because a certain manufacturer cuts the tobacco stems, the length of the fiber material in the tobacco stems is severely damaged. In order to maintain the improvement and stability of the extraction and squeezing dryness, the proportion of wood pulp used is generally between 13% and 15%, resulting in a higher content of wood pulp fiber in the final tobacco sheet product. As a result, the flavor retention of the final product is not as good as that of Example 1.

[0062] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A semi-separated, semi-combined, countercurrent extraction process for tobacco sheets in a papermaking method, characterized in that, Includes the following steps: 1) Pre-extraction of tobacco stems: Add hot water for extraction, heated stem liquid and tobacco stems to a tobacco stem pulper, mix and stir to obtain mixture one; perform vibrating sieve screening on mixture one to obtain extracted tobacco stems and free liquid; perform defiberization treatment on the extracted tobacco stems, and perform solid-liquid separation on the defiberized material to obtain pre-extracted tobacco stems and liquid phase; 2) Mixing, extraction and pulping: Add the secondary extract, primary extract, wood pulp, tobacco flakes and pre-extracted tobacco stems from step 3) to a mixing pulper, mix and stir to obtain extract material one; The specific operation of adding secondary extract, primary extract, wood pulp, tobacco flakes, and pre-extracted tobacco stems to the mixing pulper includes: when starting the mixing pulper, simultaneously adding secondary extract and primary extract at a constant flow rate; when the amount of secondary extract and primary extract added reaches 20 to 25 times the weight of wood pulp, adding wood pulp and stirring for 3 to 8 minutes; when the addition of secondary extract and primary extract is completed, simultaneously adding tobacco flakes and pre-extracted tobacco stems; the mixing and stirring time is 15 to 25 minutes. Based on oven-dry material, the mass ratio of the added tobacco leaves to the tobacco stems added in step 1) is 40-60:40-60; based on oven-dry material, the corresponding weight of wood pulp added per 100 kg of tobacco stems and leaves is 9-11 kg; based on oven-dry material, the total volume of the secondary and primary extracts added per 100 kg of tobacco stems and leaves is 0.55-0.65 m³. 3 The volume percentage of the secondary extract is 55% to 65%, and the volume percentage of the primary extract is 35% to 45%. The obtained extract material is fed into the extraction buffer tank, and then continuously output from the extraction buffer tank to step 3) for continuous extraction. 3) Continuous extraction: The first-stage extraction material is squeezed dry to obtain a first-stage squeezed material and a first-stage extract. The first-stage squeezed material is sent to a second-stage mixing pump to mix with the third-stage extract. After second-stage extraction, it is squeezed dry again to obtain a second-stage squeezed material and a second-stage extract. The second-stage squeezed material is sent to a third-stage mixing pump to mix with hot water for extraction. After third-stage extraction, it is squeezed dry again to obtain a third-stage squeezed material and a third-stage extract. The third-stage squeezed material is mixed with diluted white water and then sent to the pulping section. The first-stage and second-stage extracts are recycled to the mixing pulper, and the third-stage extract is recycled to the second-stage mixing pump.

2. The papermaking process for tobacco sheets using a semi-separated, semi-combined, countercurrent extraction method as described in claim 1, characterized in that, Step 1) includes one or more of the following features: (1a) When starting the tobacco stem pulper, add extraction hot water and heating stem liquid simultaneously, and then add tobacco stems; (1b) Based on oven-dry material, the total volume of hot water for extraction and heating liquor added per 100 kg of tobacco stems is 0.55~0.65 m³. 3 The volume percentage of hot water used for extraction is 55%–65%, and the volume percentage of heated stem broth is 35%–45%. (1c) The mixing time is 15~25 min; (1d) The dryness of the extracted tobacco stems is 12%~17%; (1e) The dryness of the pre-extracted tobacco stems is 33%~37%.

3. The papermaking process for tobacco sheets using a semi-separated, semi-combined, countercurrent extraction method as described in claim 1, characterized in that... Step 3) includes one or more of the following features: (3a) The processing efficiency of the first-stage squeezing, second-stage squeezing and third-stage squeezing is consistent, and the squeezing dryness is 33%~37%. The material squeezed in each stage falls directly into the next stage mixing pump and mixes with the next stage extraction liquid. (3b) Based on oven-dry material, the amount of tertiary extract added at the secondary mixing pump for every 100 kg of tobacco stems and tobacco flakes is 0.30~0.40 m³. 3 The extraction hot water added at the three-stage mixing pump is 0.30~0.40 m³. 3 .

4. A semi-separated, semi-combined, countercurrent extraction system for tobacco sheets used in papermaking, characterized in that, It includes a pre-extraction unit, a mixed extraction unit, and a continuous extraction unit; The pre-extraction unit includes a tobacco stem pulper (1), a tobacco stem vibrating screener (2), a defiberizer (3), and a tobacco stem desqueezer (4); the tobacco stem pulper (1) is provided with an extraction hot water inlet, a heating stem liquid inlet, a tobacco stem inlet, and a mixed material outlet; the tobacco stem vibrating screener (2) is provided with a mixed material inlet, a free liquid outlet, and an extracted tobacco stem outlet, the mixed material inlet being connected to the mixed material outlet of the tobacco stem pulper (1); the defiberizer (3) is provided with an extracted tobacco stem inlet and a defibered material outlet, the extracted tobacco stem inlet being connected to the extracted tobacco stem outlet of the tobacco stem vibrating screener (2); the tobacco stem desqueezer (4) is provided with a defibered material inlet, a pre-extracted tobacco stem outlet, and a liquid phase outlet, the defibered material inlet being connected to the defibered material outlet of the defiberizer (3); The mixing and extraction unit includes a mixing pulper (5) and an extraction buffer tank (6); the mixing pulper (5) is provided with a secondary extract inlet, a primary extract inlet, a wood pulp inlet, a pre-extracted tobacco stem inlet, a chip inlet, and an extraction material outlet; the pre-extracted tobacco stem inlet is connected to the pre-extracted tobacco stem outlet of the tobacco stem dewatering machine (4); the inlet of the extraction buffer tank (6) is connected to the extraction material outlet of the mixing pulper (5); The continuous extraction unit includes a primary squeeze dryer (7), a primary extract tank (8), a secondary mixing pump (9), a secondary squeeze dryer (10), a secondary extract tank (11), a tertiary mixing pump (12), a tertiary squeeze dryer (13), a tertiary extract tank (14), and a pre-extraction mixing pump (22); the primary squeeze dryer (7), the secondary mixing pump (9), the secondary squeeze dryer (10), the tertiary mixing pump (12), and the tertiary squeeze dryer (13) are connected in sequence; the primary squeeze dryer (7) is provided with an extraction material inlet and a primary extract outlet, the extraction material inlet is connected to the outlet of the extraction buffer tank (6), and the secondary mixing pump (9) is provided with a tertiary extract inlet. The secondary squeeze dryer (10) is provided with a secondary extract outlet, the tertiary mixing pump (12) is provided with an extraction hot water inlet, the tertiary squeeze dryer (13) is provided with a tertiary squeezed material outlet and a tertiary extract outlet, and the tertiary squeezed material outlet is connected to the pulping section; the inlet of the primary extract tank (8) is connected to the primary extract outlet of the primary squeeze dryer (7), and the outlet is connected to the primary extract inlet of the mixing pulper (5); the secondary extract tank (11) is connected to the secondary extract outlet of the secondary squeeze dryer (10) and the secondary extract inlet of the mixing pulper (5); the tertiary extract tank (14) is connected to the tertiary extract inlet of the secondary mixing pump (9).

5. The papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction system as described in claim 4, characterized in that, The volume of the extraction buffer tank (6) is 1.3 to 1.5 times the mixing volume of the mixing pulper (5).

6. The papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction system as described in claim 4, characterized in that, A pre-extracted tobacco stem buffer silo (19) is provided on the connecting pipeline between the tobacco stem depresser (4) and the mixing pulper (5). The inlet of the pre-extracted tobacco stem buffer silo is connected to the pre-extracted tobacco stem outlet of the tobacco stem depresser (4), and the outlet of the pre-extracted tobacco stem buffer silo (19) is connected to the pre-extracted tobacco stem inlet of the mixing pulper (5).

7. The papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction system as described in claim 4, characterized in that, It also includes an extraction hot water tank (16), which has an outlet one and an outlet two. The outlet one is connected to the extraction hot water inlet of the tobacco stem pulper (1) of the pre-extraction unit, and the outlet two is connected to the extraction hot water inlet of the three-stage mixing pump (12) of the continuous extraction unit.

8. The papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction system as described in claim 4, characterized in that, The pre-extraction unit further includes a stem liquid collection tank (17) and a stem liquid heating tank (20); the stem liquid collection tank (17) is provided with a free liquid inlet, a squeeze dryer liquid phase inlet and a stem liquid outlet, the free liquid inlet is connected to the free liquid outlet of the tobacco stem vibrating screen (2), and the squeeze dryer liquid phase inlet is connected to the liquid phase outlet of the tobacco stem squeeze dryer (4); the stem liquid heating tank (20) is provided with a stem liquid inlet and a heated stem liquid outlet, the stem liquid inlet is connected to the stem liquid outlet of the stem liquid collection tank (17), and the heated stem liquid outlet is connected to the heated stem liquid inlet of the tobacco stem pulper (1).

9. The papermaking tobacco sheet semi-separated and semi-combined countercurrent extraction system as described in claim 4, characterized in that, The secondary mixing pump (9) and the tertiary mixing pump (12) are both high-concentration solid-liquid mixing screw pumps; and / or, the pre-pump mixing pump (22) is a medium-concentration solid-liquid mixing screw pump.

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