CN114775111A - Carbon fiber pre-oxidation system and high-temperature tail gas backflow method - Google Patents
Carbon fiber pre-oxidation system and high-temperature tail gas backflow method Download PDFInfo
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- CN114775111A CN114775111A CN202210529002.4A CN202210529002A CN114775111A CN 114775111 A CN114775111 A CN 114775111A CN 202210529002 A CN202210529002 A CN 202210529002A CN 114775111 A CN114775111 A CN 114775111A
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/32—Apparatus therefor
- D01F9/328—Apparatus therefor for manufacturing filaments from polyaddition, polycondensation, or polymerisation products
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F13/00—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like
- D01F13/04—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like of synthetic polymers
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
- D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
Abstract
The invention discloses a carbon fiber pre-oxidation system and a high-temperature tail gas backflow method, wherein the system comprises: the device comprises a pre-oxidation furnace, a heat exchanger, an airflow shunting unit and an airflow mixing unit. The system exchanges heat between high-temperature tail gas generated by pre-oxidation reaction and fresh air through the heat exchanger, the high-temperature tail gas is not directly contacted with the fresh air in the heat exchange process, then partial cooled tail gas flows back through the airflow shunting unit, and the tail gas is mixed with preheated air and then used as reaction gas.
Description
Technical Field
The invention relates to the technical field of carbon fiber pre-oxidation, in particular to a carbon fiber pre-oxidation system and a high-temperature tail gas reflux method.
Background
Carbon fiber is a novel fiber material, and has many excellent properties such as high strength and light weight. At present, most of carbon fibers are manufactured by using Polyacrylonitrile (PAN) protofilament as a raw material and performing two important steps of pre-oxidation and carbonization to generate the carbon fibers with high carbon content. The pre-oxidation is the step with the highest energy consumption in the carbon fiber production flow, and a large amount of reaction heat generated in the pre-oxidation furnace is quickly taken away by high-flow-rate air flow, so that precursor burnout is avoided; the gas flow entering the pre-oxidation furnace needs to be heated to a temperature suitable for reaction; the gas stream temperature distribution also needs to be as uniform as possible to improve the reaction quality. Therefore, the pre-oxidation reaction system has the requirements of high utilization efficiency of the gas flow, low energy consumption of gas flow heating, uniform temperature of the gas flow and the like, and the invention is provided.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention aims to provide a carbon fiber pre-oxidation system and a high-temperature tail gas reflux method. The invention fully utilizes the heat generated by the reaction to preheat the air entering the pre-oxidation furnace, promotes the pre-oxidation reaction, improves the reaction quality and simultaneously realizes the high-efficiency utilization of energy.
In a first aspect of the present invention, a carbon fiber pre-oxidation system is presented. According to an embodiment of the invention, the carbon fiber pre-oxidation system comprises:
the system comprises a pre-oxidation furnace, a heat treatment furnace and a heat treatment furnace, wherein the pre-oxidation furnace comprises a polyacrylonitrile protofilament inlet, a product outlet, a reaction gas inlet and a high-temperature tail gas outlet;
the heat exchanger comprises a high-temperature tail gas inlet, an air inlet, a heat-exchanged tail gas outlet and a preheated air outlet, the high-temperature tail gas outlet is connected with the high-temperature tail gas inlet, and a separator is arranged in the heat exchanger so as to divide the interior of the heat exchanger into at least two parts;
the device comprises an airflow shunting unit, a heat exchanger and a heat exchanger, wherein the airflow shunting unit comprises a heat-exchanged tail gas inlet, a backflow tail gas outlet and a discharged tail gas outlet, and the heat-exchanged tail gas inlet is connected with the heat-exchanged tail gas outlet;
the gas flow mixing unit comprises a preheated air inlet, a backflow tail gas inlet and a mixed gas outlet, the preheated air inlet is connected with the preheated air outlet, the backflow tail gas inlet is connected with the backflow tail gas outlet, and the mixed gas outlet is connected with the reaction gas inlet;
the mass flow ratio of the tail gas after heat exchange to the preheated air in the air flow mixing unit is (1-4): 1.
According to the carbon fiber pre-oxidation system provided by the embodiment of the invention, the heat exchanger is used for exchanging heat between the high-temperature tail gas generated by the pre-oxidation reaction and the fresh air, the high-temperature tail gas is not directly contacted with the fresh air in the heat exchange process, and then the partial cooled tail gas flows back through the airflow shunting unit and is mixed with the preheated air to be used as the reaction gas. Therefore, firstly, the fresh air is preheated by adopting the high-temperature tail gas, the air entering the pre-oxidation furnace is preheated by fully utilizing the heat generated by the reaction, and the heat utilization efficiency is improved. Secondly, high temperature tail gas and fresh air have sufficient heat transfer time and heat transfer area to carry out abundant heat transfer inside the heat exchanger, and the two difference in temperature is very little after the heat transfer, greatly increased the temperature degree of consistency after the two mixes, the more even air current of temperature is when the reaction, and reaction quality is higher. Thirdly, the gas flow in the pre-oxidation furnace can be increased by using the backflow tail gas under the condition of the same air input flow, more reaction heat can be taken away, meanwhile, the utilization rate of oxygen in the air is increased, the heat loss is reduced, and the efficient utilization of energy is realized.
In addition, the carbon fiber pre-oxidation system according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the present invention, the carbon fiber pre-oxidation system further comprises: the temperature adjusting unit is internally provided with a heating wire and comprises a mixed gas inlet and a reaction gas outlet, the mixed gas inlet is connected with the mixed gas outlet, and the reaction gas outlet is connected with the reaction gas inlet.
In some embodiments of the present invention, the carbon fiber pre-oxidation system further comprises: and the filtering unit is arranged on a pipeline between the high-temperature tail gas outlet and the high-temperature tail gas inlet.
In some embodiments of the present invention, the carbon fiber pre-oxidation system further comprises: a first fan disposed on the duct before the air inlet.
In some embodiments of the present invention, the carbon fiber pre-oxidation system further comprises: and the second fan is arranged on a pipeline between the mixed gas outlet and the reaction gas inlet.
In some embodiments of the present invention, the carbon fiber pre-oxidation system further comprises: and the second fan is arranged on a pipeline between the mixed gas outlet and the mixed gas inlet.
In some embodiments of the invention, the heat exchanger is a dividing wall heat exchanger.
In a second aspect of the present invention, the present invention provides a method for performing high temperature exhaust gas backflow by using the carbon fiber pre-oxidation system described in the above embodiment. According to an embodiment of the invention, the method comprises:
(1) conveying polyacrylonitrile precursor to a pre-oxidation furnace, and carrying out pre-oxidation reaction under the action of reaction gas to form high-temperature tail gas and a solid product;
(2) respectively enabling the high-temperature tail gas and the air to enter a heat exchanger for heat exchange so as to preheat the air and cool the high-temperature tail gas;
(3) enabling the cooled tail gas to enter an airflow shunting unit for shunting so as to enable part of the tail gas to enter an airflow mixing unit, and enabling preheated air to enter the airflow mixing unit for mixing so as to obtain mixed gas;
(4) and enabling the mixed gas to enter the pre-oxidation furnace to be used as the reaction gas.
According to the method of the embodiment of the invention, the high-temperature tail gas generated by the pre-oxidation reaction and the fresh air are subjected to heat exchange through the heat exchanger, the high-temperature tail gas is not directly contacted with the fresh air in the heat exchange process, and then part of the cooled tail gas is refluxed through the airflow shunting unit and is mixed with the preheated air to be used as the reaction gas. Therefore, firstly, the fresh air is preheated by adopting the high-temperature tail gas, the air entering the pre-oxidation furnace is preheated by fully utilizing the heat generated by the reaction, and the heat utilization efficiency is improved. Secondly, there are sufficient heat transfer time and heat transfer area to carry out abundant heat transfer in heat exchanger inside high temperature tail gas and fresh air, and the difference in temperature of the two is very little after the heat transfer, greatly increased the temperature degree of consistency after the two mixes, the more even air current of temperature is at the reaction time, and reaction quality is higher. Thirdly, the gas flow in the pre-oxidation furnace can be increased by using the backflow tail gas under the condition of the same air input flow, more reaction heat can be taken away, the utilization rate of oxygen in the air is increased, the heat loss is reduced, and the efficient utilization of energy is realized.
In addition, the method according to the above embodiment of the present invention may also have the following additional technical features:
in some embodiments of the invention, the oxygen content of the reaction gas entering the pre-oxidation oven is in the range of 17 to 20.7 wt%.
In some embodiments of the present invention, the temperature of the reaction gas entering the pre-oxidation furnace is 200-300 degrees Celsius.
In some embodiments of the invention, the temperature of the high temperature tail gas is less than 380 degrees celsius.
In some embodiments of the invention, the flow rate of the reactant gas entering the pre-oxidation oven is from 1 to 5 m/s.
In some embodiments of the present invention, the high temperature tail gas enters a filtering unit before entering the heat exchanger, so as to filter and remove by-products in the high temperature tail gas.
In some embodiments of the present invention, the mixed gas is introduced into a temperature adjusting unit before being introduced into the pre-oxidation furnace, so as to adjust the temperature of the mixed gas.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural view of a carbon fiber pre-oxidation system according to an embodiment of the present invention.
The system comprises a pre-oxidation furnace 100, a reaction gas inlet 101, a polyacrylonitrile precursor inlet 102, a high-temperature tail gas outlet 103, a product outlet 104, a heat exchanger 200, a high-temperature tail gas inlet 201, an air inlet 202, a tail gas outlet after heat exchange 203, a preheated air outlet 204, an airflow shunting unit 300, a tail gas inlet after heat exchange 301, a reflux tail gas outlet 302, a tail gas exhaust outlet 303, an airflow mixing unit 400, a preheated air inlet 401, a reflux tail gas inlet 402, a mixed gas outlet 403, a second fan 500, a temperature adjusting unit 600, a mixed gas inlet 601, a reaction gas outlet 602 and a first fan 700.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "central", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", and the like indicate orientations or positional relationships based on those shown in the drawings, merely for convenience of description and simplification of the description, and do not indicate or imply that the carbon fiber pre-oxidation system or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, are not to be construed as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In a first aspect of the present invention, the present invention proposes a carbon fiber pre-oxidation system, referring to fig. 1, comprising: the pre-oxidation furnace 100, the heat exchanger 200, the gas flow dividing unit 300 and the gas flow mixing unit 400. The carbon fiber pre-oxidation system according to an embodiment of the present invention is further described in detail below.
In an embodiment of the present invention, referring to fig. 1, a pre-oxidation furnace 100, the pre-oxidation furnace 100 includes a polyacrylonitrile precursor inlet 102, a product outlet 104, a reaction gas inlet 101, and a high temperature off-gas outlet 103. Polyacrylonitrile precursor enters into the chamber of the pre-oxidation furnace through the polyacrylonitrile precursor inlet 102, reaction gas enters into the chamber of the pre-oxidation furnace through the reaction gas inlet 101, the polyacrylonitrile precursor is subjected to pre-oxidation reaction under the action of the reaction gas and emits a large amount of reaction heat, a product after the reaction is discharged out of the chamber of the pre-oxidation furnace through the product outlet 104, and high-temperature tail gas generated by the reaction is discharged out of the chamber of the pre-oxidation furnace through the high-temperature tail gas outlet 103. Wherein, the high-temperature tail gas contains byproducts such as tar and the like. The specific structure of the pre-oxidation oven 100 belongs to the prior art in the field and will not be described herein.
In an embodiment of the present invention, referring to fig. 1, a heat exchanger 200 includes a high temperature tail gas inlet 201, an air inlet 202, a tail gas outlet after heat exchange 203, and an air outlet after preheating 204, the high temperature tail gas outlet 103 is connected to the high temperature tail gas inlet 201 through a pipeline, a partition is provided in the heat exchanger 200 to divide the inside of the heat exchanger 200 into at least two parts, wherein at least one part is used for passing through the high temperature tail gas, and at least another part is used for passing through fresh air, thereby ensuring that the high temperature tail gas and the fresh air do not directly contact during heat exchange. High temperature tail gas from pre-oxidation furnace chamber exhaust gets into the part that is used for holding high temperature tail gas of this heat exchanger 200 through high temperature tail gas entry 201, fresh air gets into the part that is used for holding fresh air of this heat exchanger 200 through air inlet 202, therefore, high temperature tail gas and fresh air carry out abundant heat transfer in heat exchanger 200, and high temperature tail gas and fresh air direct contact not at the heat transfer in-process, after high temperature tail gas and fresh air carried out abundant heat transfer, the difference in temperature of the two was very little. The tail gas after heat exchange is discharged out of the heat exchanger 200 through a tail gas outlet 203 after heat exchange, and the preheated air is discharged out of the heat exchanger 200 through a preheated air outlet 204. The specific structure of the heat exchanger 200 belongs to the prior art in the field, and is not described herein. As a specific example, the heat exchanger 200 is a dividing wall heat exchanger. In addition, it should be noted that the pipeline does not represent a material conveying path which is necessarily tubular in the actual device, but refers to a conveying means for the material.
In an embodiment of the present invention, referring to fig. 1, an airflow splitting unit 300, where the airflow splitting unit 300 includes a heat-exchanged tail gas inlet 301, a backflow tail gas outlet 302, and a tail gas discharge outlet 303, and the heat-exchanged tail gas inlet 301 is connected to the heat-exchanged tail gas outlet 203 through a pipeline. The cooled tail gas enters the airflow shunting unit 300 through the tail gas inlet 301 after heat exchange, and is shunted in the airflow shunting unit 300, so that a part of the tail gas is discharged through the backflow tail gas outlet 302 and enters the airflow mixing unit 400, and the rest of the tail gas is discharged through the tail gas discharge outlet 303. The specific structure of the airflow splitting unit 300 belongs to the prior art in the field, and is not described herein again.
In the embodiment of the present invention, referring to fig. 1, the gas flow mixing unit 400 includes a preheated air inlet 401, a returned tail gas inlet 402 and a mixed gas outlet 403, the preheated air inlet 401 is connected to the preheated air outlet through a pipeline, the returned tail gas inlet 402 is connected to the returned tail gas outlet 302 through a pipeline, and the mixed gas outlet 403 is connected to the reactant gas inlet through a pipeline. The cooled tail gas enters the gas flow mixing unit 400 through the backflow tail gas inlet 402, the preheated air enters the gas flow mixing unit 400 through the preheated air inlet 401, the cooled tail gas and the preheated air are fully mixed in the gas flow mixing unit 400, and are discharged from the mixed gas outlet 403 and then enter the pre-oxidation furnace 100 through the reaction gas inlet to be used as reaction gas. The specific structure of the air mixing unit 400 belongs to the prior art in the field, and is not described in detail herein.
In the embodiment of the invention, the mass flow ratio of the tail gas after heat exchange to the preheated air in the air flow mixing unit is (1-4):1, so that the oxygen content of the mixed gas is kept in a proper range, the reaction quality of pre-oxidation is further improved, meanwhile, the gas flow in the pre-oxidation furnace can be increased under the condition of the same air input flow by adopting the backflow tail gas with a proper proportion, more reaction heat can be taken away, the utilization rate of oxygen in the air is increased, the heat loss is reduced, and the efficient utilization of energy is realized.
According to the carbon fiber pre-oxidation system provided by the embodiment of the invention, the heat exchanger is used for exchanging heat between the high-temperature tail gas generated by the pre-oxidation reaction and the fresh air, the high-temperature tail gas is not directly contacted with the fresh air in the heat exchange process, and then the partial cooled tail gas flows back through the airflow shunting unit and is mixed with the preheated air to be used as the reaction gas. Therefore, firstly, the fresh air is preheated by adopting the high-temperature tail gas, the air entering the pre-oxidation furnace is preheated by fully utilizing the heat generated by the reaction, and the heat utilization efficiency is improved. Secondly, there are sufficient heat transfer time and heat transfer area to carry out abundant heat transfer in heat exchanger inside high temperature tail gas and fresh air, and the difference in temperature of the two is very little after the heat transfer, greatly increased the temperature degree of consistency after the two mixes, the more even air current of temperature is at the reaction time, and reaction quality is higher. Thirdly, the gas flow in the pre-oxidation furnace can be increased by using the backflow tail gas under the condition of the same air input flow, more reaction heat can be taken away, meanwhile, the utilization rate of oxygen in the air is increased, the heat loss is reduced, and the efficient utilization of energy is realized.
Further, the carbon fiber pre-oxidation system further comprises: and the filtering unit (not shown in the figure) is arranged on the pipeline between the high-temperature tail gas outlet and the high-temperature tail gas inlet, and the high-temperature tail gas passes through the filtering unit to remove byproducts such as tar and the like. The specific structure of the filtering unit belongs to the prior art in the field, and is not described in detail herein.
Further, referring to fig. 1, the carbon fiber pre-oxidation system further includes: the temperature adjusting unit 600 is provided with heating wires in the temperature adjusting unit 600, the temperature adjusting unit 600 comprises a mixed gas inlet 601 and a reaction gas outlet 602, the mixed gas inlet 601 is connected with the mixed gas outlet 403, and the reaction gas outlet 602 is connected with the reaction gas inlet. The temperature adjusting unit 600 is used for adjusting the temperature of the mixed gas, adjusting the temperature of the mixed gas to a temperature suitable for pre-oxidation, considering heat loss of the pipeline, if the temperature of the mixed gas is insufficient, the temperature adjusting unit 600 can raise the temperature by heating means such as electric heating, and the air flow reaching the suitable temperature enters the pre-oxidation cavity through the pipeline for reaction. The specific structure of the temperature adjustment unit 600 belongs to the prior art in the field, and is not described herein again.
Further, referring to fig. 1, the carbon fiber pre-oxidation system further includes: a first fan 700, said first fan 700 being provided on the duct before said air inlet 202, which fan forces fresh air into the heat exchanger, powering the flow of fresh air.
Further, referring to fig. 1, the carbon fiber pre-oxidation system further includes: and a second fan 500, wherein the second fan 500 is arranged on a pipeline between the mixed gas outlet 403 and the reaction gas inlet 101, and the second fan 500 provides power for the flow of the mixed gas. It is understood that, in the case where the carbon fiber pre-oxidation system includes the temperature adjusting unit 600, the second fan 500 is provided on the pipe between the mixed gas outlet 403 and the mixed gas inlet 601.
In a second aspect of the present invention, the present invention provides a method for performing high temperature exhaust gas recirculation by using the carbon fiber pre-oxidation system described in the above embodiment. According to an embodiment of the invention, the method comprises:
s100: and conveying the polyacrylonitrile precursor to a pre-oxidation furnace, and carrying out pre-oxidation reaction under the action of reaction gas to form high-temperature tail gas and a solid product.
In the step, the polyacrylonitrile protofilament enters the pre-oxidation furnace from one end of the pre-oxidation furnace, is extracted from the other end after reaction in the furnace, and as a specific example, the polyacrylonitrile protofilament can be conveyed by adopting a roller conveying device.
According to some embodiments of the present invention, the oxygen content of the reaction gas entering the pre-oxidation furnace is 17-20.7 wt%, so that the gas flow in the pre-oxidation furnace is increased while the reaction quality of pre-oxidation is further improved, more reaction heat can be taken away, the utilization rate of oxygen in air is increased, heat loss is reduced, and energy efficient utilization is realized.
According to some embodiments of the present invention, the temperature of the reaction gas entering the pre-oxidation furnace is 200-300 ℃, thereby further improving the reaction quality of pre-oxidation.
According to still other specific embodiments of the invention, the temperature of the high-temperature tail gas in the pre-oxidation furnace is less than 380 ℃, so that the polyacrylonitrile protofilament is prevented from being burnt due to overhigh temperature in the pre-oxidation furnace.
According to still other embodiments of the present invention, the flow rate of the reaction gas entering the pre-oxidation furnace is 1-5m/s, so that the proper gas flow rate in the pre-oxidation furnace is maintained, a large amount of heat generated by the pre-oxidation reaction is taken away, and the temperature of the high temperature tail gas is further ensured to be less than 380 ℃.
S200: and respectively enabling the high-temperature tail gas and the air to enter a heat exchanger for heat exchange so as to preheat the air and cool the high-temperature tail gas.
According to still other specific embodiments of the present invention, the high temperature tail gas enters a filtering unit before entering the heat exchanger, so as to filter and remove by-products in the high temperature tail gas.
S300: the tail gas enters the airflow distribution unit for distribution after cooling so as to enable part of the tail gas to enter the airflow mixing unit, and simultaneously, preheated air enters the airflow mixing unit for mixing so as to obtain mixed gas.
S400: and enabling the mixed gas to enter the pre-oxidation furnace to be used as the reaction gas.
According to still other embodiments of the present invention, the mixed gas enters a temperature adjusting unit before entering the pre-oxidation furnace, so as to adjust the temperature of the mixed gas to a temperature suitable for pre-oxidation to occur.
According to the method of the embodiment of the invention, the heat exchanger is used for exchanging heat between the high-temperature tail gas generated by the pre-oxidation reaction and the fresh air, the high-temperature tail gas is not directly contacted with the fresh air in the heat exchange process, and then the airflow shunting unit is used for refluxing part of the cooled tail gas, and the cooled tail gas is mixed with the preheated air and then used as the reaction gas. Therefore, firstly, the fresh air is preheated by adopting the high-temperature tail gas, the air entering the pre-oxidation furnace is preheated by fully utilizing the heat generated by the reaction, and the heat utilization efficiency is improved. Secondly, high temperature tail gas and fresh air have sufficient heat transfer time and heat transfer area to carry out abundant heat transfer inside the heat exchanger, and the two difference in temperature is very little after the heat transfer, greatly increased the temperature degree of consistency after the two mixes, the more even air current of temperature is when the reaction, and reaction quality is higher. Thirdly, the gas flow in the pre-oxidation furnace can be increased by using the backflow tail gas under the condition of the same air input flow, more reaction heat can be taken away, the utilization rate of oxygen in the air is increased, the heat loss is reduced, and the efficient utilization of energy is realized.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Moreover, various embodiments or examples and features of various embodiments or examples described in this specification can be combined and combined by one skilled in the art without being mutually inconsistent.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A carbon fiber pre-oxidation system, comprising:
the system comprises a pre-oxidation furnace, a heat treatment furnace and a heat treatment furnace, wherein the pre-oxidation furnace comprises a polyacrylonitrile protofilament inlet, a product outlet, a reaction gas inlet and a high-temperature tail gas outlet;
the heat exchanger comprises a high-temperature tail gas inlet, an air inlet, a heat-exchanged tail gas outlet and a preheated air outlet, the high-temperature tail gas outlet is connected with the high-temperature tail gas inlet, and a separator is arranged in the heat exchanger so as to divide the interior of the heat exchanger into at least two parts;
the device comprises an airflow shunting unit, a heat exchanger and a heat exchanger, wherein the airflow shunting unit comprises a heat-exchanged tail gas inlet, a backflow tail gas outlet and a tail gas discharge outlet, and the heat-exchanged tail gas inlet is connected with the heat-exchanged tail gas outlet;
the gas flow mixing unit comprises a preheated air inlet, a backflow tail gas inlet and a mixed gas outlet, the preheated air inlet is connected with the preheated air outlet, the backflow tail gas inlet is connected with the backflow tail gas outlet, and the mixed gas outlet is connected with the reaction gas inlet;
the mass flow ratio of the tail gas after heat exchange to the preheated air in the air flow mixing unit is (1-4) to 1.
2. The carbon fiber pre-oxidation system of claim 1, further comprising: the temperature adjusting unit is internally provided with a heating wire and comprises a mixed gas inlet and a reaction gas outlet, the mixed gas inlet is connected with the mixed gas outlet, and the reaction gas outlet is connected with the reaction gas inlet.
3. The carbon fiber pre-oxidation system of claim 1, further comprising: and the filtering unit is arranged on a pipeline between the high-temperature tail gas outlet and the high-temperature tail gas inlet.
4. The carbon fiber pre-oxidation system of claim 1, further comprising: a first fan disposed on the duct before the air inlet.
5. The carbon fiber pre-oxidation system of claim 1, further comprising: and the second fan is arranged on a pipeline between the mixed gas outlet and the reaction gas inlet.
6. The carbon fiber pre-oxidation system of claim 2, further comprising: and the second fan is arranged on the pipeline between the mixed gas outlet and the mixed gas inlet.
7. The carbon fiber pre-oxidation system of any one of claims 1-6, wherein the heat exchanger is a dividing wall heat exchanger.
8. A method for performing high temperature exhaust gas recirculation by using the carbon fiber pre-oxidation system of any one of claims 1 to 7, comprising:
(1) conveying polyacrylonitrile precursor to a pre-oxidation furnace, and carrying out pre-oxidation reaction under the action of reaction gas to form high-temperature tail gas and solid products;
(2) respectively enabling the high-temperature tail gas and the air to enter a heat exchanger for heat exchange so as to preheat the air and cool the high-temperature tail gas;
(3) enabling the cooled tail gas to enter an airflow shunting unit for shunting so as to enable part of the tail gas to enter an airflow mixing unit, and enabling the preheated air to enter the airflow mixing unit for mixing so as to obtain mixed gas;
(4) and enabling the mixed gas to enter the pre-oxidation furnace to be used as the reaction gas.
9. The method according to claim 8, wherein the oxygen content of the reaction gas entering the pre-oxidation oven is 17-20.7 wt%;
optionally, the temperature of the reaction gas entering the pre-oxidation furnace is 200-300 ℃;
optionally, the temperature of the high-temperature tail gas is less than 380 ℃;
optionally, the flow rate of the reaction gas entering the pre-oxidation oven is 1 to 5 m/s.
10. The method according to claim 8, wherein the high temperature tail gas enters a filtering unit before entering the heat exchanger so as to filter and remove by-products in the high temperature tail gas;
optionally, the mixed gas enters a temperature adjusting unit before entering the pre-oxidation furnace so as to adjust the temperature of the mixed gas.
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Citations (5)
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|---|---|---|---|---|
| JPS59116422A (en) * | 1982-12-22 | 1984-07-05 | Toray Ind Inc | Treatment of gas discharged from flame resistant treatment process in manufacture of carbon fiber |
| CN2251122Y (en) * | 1995-11-27 | 1997-04-02 | 中国科学院山西煤炭化学研究所 | External heating type furnace for preliminary heat treatment in oxidizing |
| CN101684576A (en) * | 2009-07-30 | 2010-03-31 | 合肥日新高温技术有限公司 | Pre-oxidation furnace |
| CN104213254A (en) * | 2014-08-08 | 2014-12-17 | 中国科学院宁波材料技术与工程研究所 | Device to improve temperature field uniformity of pre-oxidation furnace |
| CN217459690U (en) * | 2022-05-16 | 2022-09-20 | 清华大学 | Carbon fiber pre-oxidation system |
-
2022
- 2022-05-16 CN CN202210529002.4A patent/CN114775111A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59116422A (en) * | 1982-12-22 | 1984-07-05 | Toray Ind Inc | Treatment of gas discharged from flame resistant treatment process in manufacture of carbon fiber |
| CN2251122Y (en) * | 1995-11-27 | 1997-04-02 | 中国科学院山西煤炭化学研究所 | External heating type furnace for preliminary heat treatment in oxidizing |
| CN101684576A (en) * | 2009-07-30 | 2010-03-31 | 合肥日新高温技术有限公司 | Pre-oxidation furnace |
| CN104213254A (en) * | 2014-08-08 | 2014-12-17 | 中国科学院宁波材料技术与工程研究所 | Device to improve temperature field uniformity of pre-oxidation furnace |
| CN217459690U (en) * | 2022-05-16 | 2022-09-20 | 清华大学 | Carbon fiber pre-oxidation system |
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