CN106283816B - Drying system and papermaking method thereof - Google Patents
Drying system and papermaking method thereof Download PDFInfo
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- CN106283816B CN106283816B CN201510289385.2A CN201510289385A CN106283816B CN 106283816 B CN106283816 B CN 106283816B CN 201510289385 A CN201510289385 A CN 201510289385A CN 106283816 B CN106283816 B CN 106283816B
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Abstract
The invention provides a drying system and a papermaking method for drying wet paper sheets by using the same, wherein the drying system comprises: the drying cylinder comprises a drying cylinder, a first air hood, a second air hood, an air supply pipeline and a heater, wherein the first air hood and the second air hood are arranged on the periphery of the drying cylinder and are used for drying wet paper passing through the periphery of the drying cylinder; the air supply pipeline is used for supplying hot air to the first air hood and the second air hood, and the heater is arranged on the air supply pipeline and used for heating the air flowing through the air supply pipeline. According to the drying system and the papermaking method for drying the wet paper sheets by using the drying system, provided by the invention, the energy is saved and the drying efficiency of the wet paper is improved by recycling the waste heat of the drying gas for many times.
Description
Technical Field
The invention relates to the technical field of papermaking processes, in particular to a drying system and a papermaking method for drying wet paper sheets by using the same.
Background
In the papermaking industry, a drying device is generally provided for drying a wet paper sheet formed in a forming section to obtain a paper sheet with a low moisture content. Generally, a drying device comprises a drying cylinder and a drying cylinder air hood, wherein high-temperature high-pressure steam is input into the drying cylinder, high-temperature hot air is input into the drying cylinder air hood, a wet paper sheet absorbs heat of the steam in the drying cylinder so as to evaporate moisture, the high-temperature hot air in the drying cylinder air hood impacts the wet paper sheet, the evaporated moisture is taken away while the paper sheet is dried, the temperature of the hot air is reduced while the hot air absorbs the moisture, and the moisture content is increased. In order to prevent the moisture content in the hot air from continuously increasing to influence the drying effect, besides a part of hot air circulates in the system, a part of hot air is discharged out of the system, and the temperature of the hot air discharged out of the system is still high, so that considerable waste heat is generated, and great waste of energy is caused.
Disclosure of Invention
The embodiment of the invention provides a drying system and a papermaking method for drying wet paper sheets by using the same, and aims to solve the technical problem of energy waste in the prior art.
In order to solve the above problem, an embodiment of the present invention provides a drying system for drying wet paper sheets in a papermaking process, including: the drying cylinder comprises a drying cylinder, a first air hood, a second air hood, an air supply pipeline and a heater, wherein the first air hood and the second air hood are arranged on the periphery of the drying cylinder and are used for drying wet paper passing through the periphery of the drying cylinder; the air supply pipeline is used for supplying hot air to the first air hood and the second air hood, and the heater is arranged on the air supply pipeline and used for heating the air flowing through the air supply pipeline.
According to a preferred embodiment of the present invention, the air supply pipeline further comprises an air inlet pipeline and a recovery pipeline, wherein one end of the air inlet pipeline is connected with an air source, and the other end of the air inlet pipeline is communicated with the air inlet of the first air hood so as to provide hot air for the first air hood; one end of the recovery pipeline is communicated with the reflux port of the first air hood, and the other end of the recovery pipeline is communicated with the air inlet of the second air hood, so that hot air flowing through the first air hood flows through the second air hood, and the heat of the hot air is recycled.
According to a preferred embodiment of the present invention, the recycling pipeline further communicates the return port of the second air box and the air inlet of the second air box, so that the hot air flowing through the second air box is reused by the second air box.
According to a preferred embodiment of the present invention, the recycling line further communicates the return port of the first air box and the air inlet of the first air box, so that the hot air flowing through the first air box is reused by the first air box.
According to a preferred embodiment of the invention, the air inlet conduit is further in communication with an air inlet of the second air cap for providing hot air to the second air cap.
According to a preferred embodiment of the present invention, the drying system further comprises a supercharger provided on the intake line and/or the recovery line.
According to a preferred embodiment of the invention, the drying system further comprises a condensate separator in communication with the return line.
According to a preferred embodiment of the invention, the drying system further comprises a main heat exchanger which communicates on the one hand with the return opening of the first air hood and/or the second air hood via a return line for heating the hot air flowing through the first air hood and/or the second air hood and on the other hand with the inlet line of the first air hood and/or the second air hood via a branch line for passing the heated air into the first air hood and/or the second air hood.
According to a preferred embodiment of the present invention, the drying system further comprises a third air hood and a fourth air hood, wherein the air inlet of the third air hood is communicated with the air inlet pipeline or communicated with the return port of one or more of the other air hoods or communicated with the return port of the third air hood, and the return port of the third air hood is communicated with the air inlet of the third air hood or communicated with the air inlet of one or more of the other air hoods; the air inlet of the fourth air hood is communicated with the air inlet pipeline or communicated with the return port of one or more of the other air hoods or communicated with the return port of the fourth air hood, and the return port of the fourth air hood is communicated with the air inlet of the fourth air hood or communicated with the air inlet of one or more of the other air hoods.
According to a preferred embodiment of the invention, the temperature of the hot air in the inlet line is between 350 ℃ and 550 ℃.
According to a preferred embodiment of the invention, the flow velocity of the air in the air supply line is 3000m/min to 6000 m/min.
According to a preferred embodiment of the present invention, the temperature of the hot air flowing into the second air hood from the return opening of the first air hood is 100 ℃ to 300 ℃.
According to a preferred embodiment of the invention, the first hood is arranged upstream in the direction of rotation of the cylinder and the second hood is arranged downstream in the direction of rotation of the cylinder.
According to a preferred embodiment of the present invention, the number of the second air hoods is two, and the two second air hoods are respectively disposed upstream and downstream of the first air hood, and the temperature of the hot air in the second air hood is lower than that of the hot air in the first air hood.
In order to solve the technical problem, the invention also provides a papermaking method for drying wet paper sheets by using the drying system, which comprises the following steps: providing pulp and forming a wet sheet; transferring and attaching the wet paper to the surface of a drying cylinder; the wet paper sheet is dried using a drying system.
According to a preferred embodiment of the present invention, in the step of drying the wet paper sheet by using the drying system, the hot and humid air exhausted from the first air hood is introduced into the second air hood to dry the wet paper sheet.
Compared with the prior art, the drying system and the papermaking method for drying the wet paper sheets by using the drying system provided by the invention have the advantages that the energy is saved and the drying efficiency of the wet paper sheets is improved by recycling the waste heat of the drying gas for many times. In addition, the wet paper is dried by arranging the air hoods, so that the paper dust phenomenon caused by fiber breakage and falling off in the drying process can be effectively prevented.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of the construction of a first embodiment of the drying system of the present invention;
FIG. 2 is a schematic diagram of a second embodiment of the drying system of the present invention;
FIG. 3 is a schematic diagram of a third embodiment of the drying system of the present invention; and
FIG. 4 is a flow chart of a preferred embodiment of the papermaking process of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be noted that the following examples are only illustrative of the present invention, and do not limit the scope of the present invention. Similarly, the following examples are only some but not all examples of the present invention, and all other examples obtained by those skilled in the art without any inventive work are within the scope of the present invention.
The papermaking equipment provided by the embodiment of the technical scheme is used for papermaking, can be used for manufacturing domestic paper, and can also be used for manufacturing coated paper, cultural paper or other paper. The papermaking apparatus includes a drying system for drying a wet paper sheet and forming a low moisture dry paper sheet. It will be appreciated that the papermaking apparatus is also provided with other necessary papermaking equipment in the upstream direction of the drying system, such as a pulp treating section, a forming section, etc. for treating the pulp and forming the fibers into a wet paper sheet. The pulp processing unit may be a pulp processing mechanism known in the art, and generally includes a pulper, a beater, a refiner, a pulp barrel, and the like, for processing raw pulp into pulp meeting the performance requirements of paper. The forming section may be a forming mechanism known in the art, and generally includes one of a forming fabric and a cylinder mould, a head box, a felt, a transfer mechanism, etc. the pulp is delivered to the forming fabric or cylinder mould through the head box to form a wet sheet, and the formed wet sheet is transported to a drying system through the felt. In addition, the papermaking equipment is also provided with other necessary papermaking equipment in the downstream direction of the drying system, such as a reeling part, and the reeling part is used for reeling the dried paper sheets into paper rolls so as to facilitate subsequent processing or treatment. Of course, one skilled in the art will appreciate that the papermaking apparatus may also include other conventional structures, such as press rolls, chemical addition systems, cleaning systems, white water systems, and the like. Within the understanding of those skilled in the art, this is not further enumerated here.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a first embodiment of a drying system according to the present invention; the drying system is used for drying a paper web. Drying systems include, but are not limited to, the following structures: a drying cylinder 12, a first hood 13, a second hood 14, supply lines as well as heaters, superchargers, etc.
Specifically, the first hood 13 and the second hood 14 are located at the outer periphery of the drying cylinder 12, and high temperature steam is introduced into the drying cylinder 12, so that the surface of the drying cylinder 12 also has high temperature, thereby evaporating water in the wet paper sheet and achieving the drying purpose. In addition, the first air hood 13 is used to blow hot air in the direction of the outer periphery of the drying cylinder 12. The supply line is connected to the first hood 13 to supply hot air to the first hood 13. Generally, the hot air is heated by the heater 132, that is, the heater 132 is connected to the other end of the supply pipeline, the heater 132 can be a heating structure in the prior art to heat the air conveyed from the first air inlet pipe 133, and the heating structure can be electric heating, steam heating, infrared heating, radiation heating, heat exchange, combustion heating, etc. Generally, in order to obtain higher and more stable temperature, the combustion heating method is preferably adopted in the present invention, that is, the heater 132 is a burner, and more preferably, the fuel used by the burner is natural gas, although in other embodiments, coal, oil, gas, etc. can be used as the fuel of the burner. And are not limited herein.
The hot air heated by the heater 132 is delivered to the first air cowl 13 through the supply duct 131 to heat and dry the wet paper sheet passing through the first air cowl 13 and attached to the surface of the drying cylinder 12. It will be appreciated that the heated hot air should have as high a temperature as possible in order to improve the efficiency of drying, but higher temperatures may cause the sheet to be damaged by high temperatures or to burn on fire due to the inflammability of the paper, so 200-700 c is a more suitable temperature, preferably 350-550 c, and more preferably the temperature of the hot air is controlled to 380-450 c, so that there is a higher drying efficiency and the sheet is less prone to damage and the risk of fire is reduced.
It can be understood that the specific shape and structure of the first air hood 13 can be the shape and structure of the air hood in the prior art, but generally speaking, the first air hood 13 has an air inlet, an air outlet (not shown in the figure), and a plurality of air flow nozzles and an air flow return port (not shown in the figure) arranged inside the first air hood 13 and facing one surface of the drying cylinder 12, the air inlet is used for connecting the supply pipeline 131 to introduce the high temperature hot air heated by the heater 132 into the first air hood 13, the high temperature hot air flow is ejected to the wet paper sheet attached to the surface of the drying cylinder 12 through the plurality of air flow nozzles facing one surface of the drying cylinder 12, and the wet hot air carrying moisture is discharged out of the first air hood 13 through the air flow return port and the air outlet.
Preferably, the surface of the first air hood 13 facing the drying cylinder 12 is an arc surface adapted to the periphery of the drying cylinder 12 and is disposed close to the surface of the drying cylinder 12, so that the gap between the air hood and the drying cylinder 12 is small, and further, when the drying cylinder 12 rotates at a high speed, the hot air or hot steam introduced into the air hood does not excessively leak from the gap between the air hood and the surface of the drying cylinder 12, thereby improving the thermal efficiency.
It will be appreciated that, in order to improve the drying efficiency of the hot air flow on the wet paper sheet as much as possible, furthermore, the hot air flow in the first air hood 13 may be pressurized, i.e. a pressure booster (not shown) is provided on the supply pipe 131, so that the hot air flow in the first air hood 13 impacts the paper surface of the wet paper sheet 100 at a high speed, thereby rapidly drying the wet paper sheet 100 and rapidly removing the evaporated moisture while reducing the risk of fire, preferably the speed of the hot air flow relative to the surface of the drying cylinder 12 should be greater than or equal to 1000m/min, and more preferably, the speed of the hot air flow is 3000m/min-6000 m/min.
Since the hot and humid air exhausted from the first air hood 13 still has a high temperature, if the hot and humid air is directly exhausted, the heat energy is wasted, and therefore, in the technical solution of the embodiment, the hot and humid air exhausted from the exhaust outlet of the first air hood 13 is collected through the recycling pipeline 140, and is conveyed to the second air hood 14 or is returned to the heater 132 after being pressurized by the supercharger 134, and then a high-temperature hot air flow leading to the first air hood 13 is formed. Preferably, the hot humid air input to the second hood has a temperature of 100 ℃ to 300 ℃, more preferably 150 ℃ to 250 ℃, and most preferably 170 ℃ to 210 ℃.
The wet paper sheet after heated evaporation from the drying cylinder 12 and drying by the hot air stream of the first hood 13 is passed to the second hood 14 and heated and dried by the hot air stream at the second hood 14.
In this embodiment, the hot and humid air discharged from the first air hood 13 is heated to a suitable temperature by the second heater 143 together with the air introduced from the second air inlet pipe 144, and is pressurized by the pressure booster 142 and then sent to the second air hood 14. More specifically, the second heater 143 may be a heat exchanger for heating the hot and humid air by steam. In some other embodiments, other forms of heaters may be employed, such as electrical heating, radiant heating, combustion heating, and the like. The heat exchanger may be a plate heat exchanger, a coil heat exchanger, a double-pipe heat exchanger, or other common heat exchangers, and is not limited herein.
In other embodiments, the high temperature steam may be introduced directly to the hot humid air stream for secondary mixing before being returned to the drying system (not shown). Furthermore, the wet and hot airflow discharged from the first air hood 13 is directly mixed with the high-temperature steam to obtain a proper high-temperature airflow, so that elements such as a heater are omitted, and the steam heat energy can be more effectively utilized in a directly mixed mode, so that the energy consumption is reduced.
The specific shape and structure of the second gas hood 14 may be the same as the first gas hood 13, and refer to the structural description of the first gas hood 13 above. It can be understood that, in order to improve the drying efficiency of the wet paper sheet by the high temperature hot and humid air as much as possible, furthermore, the high temperature hot and humid air in the second air hood 14 may be pressurized, i.e. a pressure booster 142 is provided on the steam inlet pipe 141, so that the high temperature hot and humid air in the second air hood 14 impacts the surface of the wet paper sheet at a high speed, thereby the wet paper sheet is dried quickly and the evaporated moisture is taken away quickly. In some other embodiments, the wet paper sheet may be dried by directly spraying hot air with high temperature to the paper surface, or by using an open air hood, which is not limited herein.
In the present embodiment, the second hood 14 is disposed downstream of the rotation direction of the drying cylinder 12, and the first hood 13 is disposed upstream of the rotation direction of the drying cylinder, or the second hood 14 is disposed behind the first hood 13, it can be understood that the first hood 13 is close to the wet end direction of the papermaking equipment, and more specifically, the wet paper sheet 100 conveyed from the upstream direction of the drying system through the felt is transferred to the drying cylinder 12 covered by the second hood 14 after passing through the drying cylinder 12 covered by the first hood 13 and being dried by the hot air in the drying cylinder 12 and the first hood 13, in this case, because the hot air passing through the drying cylinder 12 and the hot air in the first hood 13 is subjected to the impingement drying, the moisture of the wet paper sheet reaching the covered area of the second hood 14 is greatly reduced compared with that at the covered area of the first hood 13, and therefore, when drying is performed again, high temperatures, as in the case of the first hood 13, are no longer required, so drying with hot, humid air having a lower temperature not only requires less energy consumption but also enables the moisture content of the paper sheet to be reduced to a suitable range.
On the other hand, the high-temperature humid hot air still contains more water molecules, so that the situation of fiber breakage and separation in the drying process is greatly reduced, and the occurrence of paper powder is greatly reduced. Therefore, in this embodiment, different hot air may be introduced into the first air hood 13 and the second air hood 14. The high temperature steam to the second hood 14 can be produced by the prior art, such as by a boiler, and the high temperature steam can be saturated steam or superheated steam, which is known in the art, more specifically, the high temperature steam has a temperature of 150 ℃ to 270 ℃, and more preferably, the high temperature steam has a temperature of 170 ℃ to 200 ℃.
It will be appreciated that the steam flow carrying moisture discharged from the exhaust port still has a relatively high temperature, and if discharged directly, it will cause waste of heat energy, so it is preferable that the steam flow discharged from the exhaust port of the second air hood 14 is collected through the second air return pipe 146, reheated (143 in the figure may be represented as a heater or a mixer, where the heater is used) to a desired temperature, and then sent back to the second air hood 14 for drying the wet paper sheet again, thereby reducing waste of heat energy. Preferably, the steam airflow with moisture discharged from the exhaust port of the second air hood 14 is sent to the flow mixer 143 through the second air return pipe 146, and is mixed with the boiler steam to form a high-temperature steam airflow at a suitable temperature, although the flow mixer 143 may also be a heat exchanger, and the high-temperature steam sent through the steam manifold 144 heats the returned low-temperature steam, so as to make the returned steam airflow reach a suitable temperature again, in other embodiments, other heating methods may also be adopted to heat the returned steam airflow, such as electric heating, and the like. The returned steam airflow is heated and pressurized by the booster 142 again and then sent to the second air hood 14, so that the steam heat energy loss is reduced, and the energy consumption of the whole system is reduced.
In order to further reduce the energy consumption of the papermaking equipment of the present invention, in the present embodiment, the hot air flow carrying moisture discharged from the first air hood 13 is collected with the steam air flow discharged from the second air hood 14 through the recovery pipeline 140, and is sent to the second air hood 14 again for heating the paper sheet in the area covered by the second air hood 14 by heating of the flow mixer 143, it can be understood that in this case, since the hot air flow carrying moisture discharged from the first air hood 13 is equivalent to that a steam air flow can be directly collected with the steam air flow discharged from the second air hood 14, the condensed water separation device required in the process of guiding the hot air flow to the heater 132 can be saved. In addition, since the hot gas flow discharged from the first gas hood 13 has a higher temperature than the steam gas flow discharged from the second gas hood 14, the steam gas flow discharged from the second gas hood 14 is heated in the process of collecting the two gas flows, so that the amount of new steam introduced from the steam header 144 is reduced, and the energy consumption is further reduced.
In other embodiments, the second hood 14 can be arranged before the first hood 13, i.e. the wet paper sheet is dried by the moist hot air in the drying cylinder 12 and the second hood 14 and then dried by the high temperature hot air in the first hood 13, which is equivalent to the paper sheet being preheated and pre-dried by the moist hot air in the second hood 14 before reaching the high temperature hot air in the first hood 13. In other embodiments, a plurality of second air hoods 14 may be provided, such as two second air hoods 14 disposed before and after the first air hood 13, respectively, so that the wet paper sheet is preheated before the high-temperature hot air drying of the first air hood 13, and after the drying of the first air hood 13, the wet paper sheet is dried again by the hot and humid air, so as to achieve the purpose of sufficient drying of the paper sheet and less paper dust. In the figure 101, a dried sheet is shown.
It will be appreciated that the secondary stream of moist hot air exiting the outlet of the second hood 14 will still have a substantially higher temperature, which would result in a waste of heat if exiting directly, and therefore it is preferred that the steam exiting the return outlet of the second hood 14 can be collected via the second return air duct 146, reheated to the desired temperature and returned to the first hood 13 or the second hood 14 for drying the moist paper sheet again, thereby reducing the waste of heat energy. It is of course also possible to arrange a third air hood (not shown) after the second air hood 14 for drying the paper sheet directly after adjusting the paper sheet surface, or to introduce the second hot and humid air stream into the drying cylinder 12 for heating the drying cylinder 12, or to introduce the second hot and humid air stream into a thermoelectric power generation device or as a heat source for an absorption air conditioner for comprehensive utilization of the waste heat. Although the above-mentioned steam exhausted from the second hood 14 is returned to the first hood 13 or a third hood is provided, and a power generation device, an absorption air conditioner, etc. are not shown in the figure, the above two schemes are easily implemented according to the design concept of the present embodiment, and are not described again here. In addition, in the present embodiment, the secondary hot and humid air flow discharged from the second air hood 14 may be collected in the recovery pipeline 140, returned to the second air hood 14, and blown out.
It can be understood that, in order to enable the papermaking equipment of the present invention to meet the requirement of more paper making, the area of the drying cylinder 12 covered by the first air hood 13 and the area of the drying cylinder 12 covered by the second air hood 14 may be set according to the requirement of different paper, the ratio of the area of the drying cylinder 12 covered by the first air hood 13 to the area of the drying cylinder 12 covered by the second air hood 14 may be 1-10: 1-10, preferably 1-5: 1-2, and more preferably the area of the drying cylinder 12 covered by the first air hood 13 is approximately equivalent to the area of the drying cylinder 12 covered by the second air hood 14.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a second embodiment of the drying system of the present invention, in this embodiment, a part of the hot and humid air exhausted from the first air hood 13 can also be sent back to the heater upstream of the first air hood 13, and after being heated by the heater, the air is sent to the first air hood 13 again for drying the wet paper. At least one of a third gas hood 18 and a fourth gas hood 19 may be further disposed between the first gas hood 13 and the second gas hood 14, wherein a high-temperature hot air flow identical to that of the first gas hood 13 may be introduced into the third gas hood 18, or a high-temperature steam flow identical to that of the second gas hood 14 may be introduced into the third gas hood 18, and similarly, a high-temperature hot air flow identical to that of the first gas hood 13 or a high-temperature steam flow identical to that of the second gas hood 14 may be introduced into the second gas hood 19. Similarly, the hot and humid air exhausted from the return openings of the third and fourth air hoods 18 and 19 may also be returned to the first or second air hood 13 or 14 and itself to make full use of the heat in the hot air. The specific hot air circulation process can be deduced by those skilled in the art from the above technical description, and therefore, will not be described in detail herein.
Of course, the number of air hoods and the heating pattern can be flexibly configured according to different areas of the surface of the drying cylinder 12, i.e. in other embodiments a fourth, a fifth, a sixth air hood, etc. can be provided. This is not further enumerated here.
The areas of the drying cylinder 12 covered by the first air hood 13, the second air hood 14, the third air hood 18 and the fourth air hood 19 are S1, S2, S3 and S4, respectively, and the ratio of the area of the wet paper surface of the high temperature hot air drying to the area of the steam drying may be: s1: s2+ S3+ S4, S1+ S2: S3+ S4, S1+ S2+ S3: S4 and the like, thereby flexibly adjusting the paper surface area covered by different drying modes. It is of course also possible to supply hot air or steam air streams of different temperatures into the third hood 18 and the fourth hood 19, respectively, wherein preferably the same hot air as in the first hood is supplied into the third hood and the same hot air as in the second hood is supplied into the fourth hood; the third air hood is arranged at the upstream of the rotating direction of the drying cylinder, and the fourth air hood is arranged at the downstream of the rotating direction of the drying cylinder; further flexibility in the configuration and reduction of energy consumption of the papermaking equipment is achieved.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a third embodiment of the drying system of the present invention; in contrast to the above embodiment, in this embodiment, in order to further reduce the energy consumption of the whole system of the paper making equipment, the low-temperature steam of the system needs to be discharged, and a specific solution is to provide a condensate separator 236 on the recycling line 240 for discharging the excessive moisture in the hot and humid air stream. The water removed by the condensate separator 236 is introduced into the main heat exchanger 25 through the low temperature steam return 253, and similarly, a condensate separator 254 may be provided on the low temperature steam return 253 to ensure clean removal of the low temperature steam.
The steam heated by the main heat exchanger 25 is reintroduced into the return pipes of the first and second air hoods 23 and 24 by means of the hot steam return pipe 250 and the hot steam return branch pipes 251 and 252, thereby participating again in the drying of the paper sheet. In addition, the main heat exchanger 25 can also preheat the air entering the heater 232, so as to improve the efficiency of the heater 232 and reduce the energy consumption of the heater 232.
In addition, in the drawings, the working principle and process of the first air hood 23, the second air hood 24, the air supply pipeline 231, the first air inlet pipe 233(244), the pressure booster 234(242), the second heater (flow mixer) 243, the steam inlet pipe 241, the recovery pipeline 240 and the drying cylinder 22 refer to the related description of the first embodiment, and are not described herein again.
According to the drying system for the papermaking equipment, provided by the embodiment of the invention, the waste heat of the drying gas is recycled for many times, so that the energy is saved, and the drying efficiency of the wet paper is improved. In addition, through setting up a plurality of air hoods to let in different hot-air in different air hoods and carry out the drying to wet paper, can effectively prevent because the fibre breaks in the drying process, drops the paper powder phenomenon that produces.
In addition, the present invention also provides a papermaking method, please refer to fig. 4, fig. 4 is a flow chart of a preferred embodiment of the papermaking method of the present invention, which includes but is not limited to the following steps.
Step S400, providing pulp and forming a wet sheet.
The paper making method can be used for manufacturing household paper, and can also be used for manufacturing coated paper, cultural paper or other paper. The papermaking method of the present invention is preferably used for making wet-formed paper, and more preferably, thin tissue paper made by wet forming using cellulose fibers as a raw material. More specifically, the pulp is not limited to pulp of paper making fiber raw material such as wood pulp, straw pulp, reed pulp, and sugar cane pulp, and is not limited to long fiber pulp, short fiber pulp, softwood pulp, and hardwood pulp, which are generally known in the art. The pulp is usually processed into pulp meeting the performance requirements of paper through a pulp processing flow, which may be a pulp processing flow known in the art, and generally includes pulp scattering, pulping, pulp mixing, and the like. The wet paper sheet formed in the embodiment of the present invention may be formed by various conventional papermaking methods, such as crescent former, fourdrinier wire former, cylinder former, and the like. It is understood that there may be chemical agent adding process in the process of forming the wet paper sheet, specifically, bactericide, softening agent, wet strength agent, dry strength agent, etc., and especially, there may be filler added.
Step S410, transferring and attaching the wet paper to the surface of a drying cylinder;
after the wet paper sheet is formed, it is transferred to the dryer surface, typically using a felt, although other transfer means are possible. In order to reduce the energy consumption of the drying system, the wet paper sheet may be dewatered during the transfer process, and a conventional dewatering method such as pressing, vacuum suction, etc. may be used. The transfer and attachment process of the wet sheet is within the understanding of those skilled in the art and will not be described in detail herein.
Step S420, drying the wet paper by using a drying system;
in step S420, it should be emphasized that there are two main preferred embodiments of the drying system in the embodiment of the present invention for drying the wet paper. Firstly, hot air with different temperatures and humidities is supplied to a first air hood and a second air hood, namely high-temperature hot air is introduced into the first air hood, and wet hot steam with lower temperature is introduced into the second air hood, so that the paper powder phenomenon caused by fiber breakage and falling is prevented; secondly, the moist and hot air exhausted from the first air hood is introduced into the second air hood to dry the moist paper, so that the heat energy resource is fully utilized.
In addition, some deformation structures, generated technical effects, and working processes and working principles of the drying system of the above two preferred schemes have already been described in detail in the above embodiments of the drying system, and are not described herein again.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent devices or equivalent processes performed by the present invention through the contents of the specification and the drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (14)
1. A drying system for drying a wet sheet of paper in a papermaking process, the drying system comprising: the drying cylinder comprises a drying cylinder, a first air hood, a second air hood, an air supply pipeline and a heater, wherein the first air hood and the second air hood are arranged on the periphery of the drying cylinder and are used for drying wet paper passing through the periphery of the drying cylinder; the air supply pipeline is used for supplying hot air to the first air hood and the second air hood, and the heater is arranged on the air supply pipeline and used for heating the air flowing through the air supply pipeline;
the air supply pipeline further comprises a recovery pipeline, one end of the recovery pipeline is communicated with the reflux port of the first air hood, and the other end of the recovery pipeline is communicated with the air inlet of the second air hood, so that the hot air flowing through the first air hood flows through the second air hood;
wherein the temperature of the hot air output by the first air hood is higher than that of the hot air output by the second air hood, and the humidity of the hot air output by the first air hood is lower than that of the hot air output by the second air hood;
the drying system further comprises a third air hood and a fourth air hood, wherein the air inlet of the third air hood is communicated with the return opening of one or more of the other air hoods, and the return opening of the third air hood is communicated with the air inlet of one or more of the other air hoods; the air inlet of the fourth air hood is communicated with the return port of one or more of the other air hoods, and the return port of the fourth air hood is communicated with the air inlet of one or more of the other air hoods;
the first air hood is arranged at the upstream of the rotation direction of the drying cylinder, and the second air hood is arranged at the downstream of the rotation direction of the drying cylinder.
2. The drying system of claim 1, wherein the air supply line further comprises an air inlet line connected at one end to an air supply and at another end in communication with the air inlet of the first air hood to provide heated air to the first air hood.
3. The drying system of claim 2, wherein the recovery duct is further in communication with the return port of the second air jacket and the air inlet of the second air jacket such that the heated air flowing through the second air jacket is reused by the second air jacket.
4. The drying system of claim 2, wherein the recovery duct is further in communication with the return port of the first air hood and the air inlet of the first air hood such that the heated air flowing through the first air hood is reused by the first air hood.
5. The drying system of claim 3, wherein the air intake conduit is further in communication with an air inlet of the second air jacket for providing heated air to the second air jacket.
6. Drying system according to claim 2, further comprising a pressure booster, which is provided on the air inlet line and/or the recovery line.
7. The drying system of claim 2, further comprising a condensate separator in communication with the recovery line.
8. Drying system according to claim 7, characterized in that the drying system further comprises a main heat exchanger which communicates on the one hand with the return opening of the first air hood and/or the second air hood via a return line for heating the hot air flowing through the first air hood and/or the second air hood and on the other hand with the inlet line of the first air hood and/or the second air hood via a branch line for passing the heated air into the first air hood and/or the second air hood.
9. Drying system according to claim 2, characterised in that the temperature of the hot air in the air inlet line is 350-550 ℃.
10. The drying system of claim 6, wherein the flow velocity of air in the air supply line is from 3000m/min to 6000 m/min.
11. The drying system of claim 2, wherein the temperature of the heated air flowing into the second air jacket from the return opening of the first air jacket is between 100 ℃ and 300 ℃.
12. The drying system according to claim 2, wherein the number of the second air hoods is two, and the second air hoods are respectively arranged upstream and downstream of the first air hood, and the temperature of the hot air in the second air hoods is lower than that of the hot air in the first air hoods.
13. A method of making paper using the drying system of any one of claims 1-12 to dry a wet sheet of paper, the method of making paper comprising:
providing pulp and forming a wet sheet;
transferring and attaching the wet paper to the surface of a drying cylinder;
the wet paper sheet is dried using a drying system.
14. The method for manufacturing paper according to claim 13, wherein in the step of drying the wet paper sheet using the drying system, the hot and humid air exhausted from the first air hood is introduced into the second air hood to dry the wet paper sheet.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108426438A (en) * | 2018-06-19 | 2018-08-21 | 衢州龙游双熊猫纸业有限公司 | The box pad net impingement drying unit of one kind and its drying means |
| MX2020012752A (en) | 2018-06-27 | 2021-02-26 | Kimberly Clark Co | Through-air drying apparatus and methods of manufacture. |
| CN109853288B (en) * | 2019-03-12 | 2024-04-02 | 江苏双良低碳产业技术研究院有限公司 | Energy-saving high-temperature flue gas impact drying paper system |
| CN111560788B (en) * | 2020-05-15 | 2021-03-23 | 维达纸业(浙江)有限公司 | Drying system for paper production and drying method thereof |
| CN111943479A (en) * | 2020-08-12 | 2020-11-17 | 东莞顺裕纸业有限公司 | Waste heat recovery system of papermaking production line |
| CN114395936B (en) * | 2022-02-14 | 2024-03-15 | 湖南正鼎环境科技有限公司 | Hot air hood for paper machine and installation method thereof |
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Effective date of registration: 20211123 Address after: 226000 group 9, Gangcheng village, Changsha Town, Rudong County, Nantong City, Jiangsu Province Patentee after: Jinhongye paper (Nantong) Co.,Ltd. Address before: No.1 Jinsheng Road, Suzhou Industrial Park, Suzhou, Jiangsu Province Patentee before: GOLD HONGYE PAPER Group Co.,Ltd. |