Fuel gas indirect heating type carbon fiber production line pre-oxidation furnace

Abstract

The utility model relates to the technical field of oxidation furnaces, in particular to a fuel gas indirect heating type carbon fiber production line pre-oxidation furnace which comprises a furnace body and a combustible gas combustion indirect type heater connected with the furnace body. The combustion chamber is arranged in the furnace body, the heat exchange tube bundle is communicated with the combustion chamber, one end of the exhaust pipeline is communicated with the tail end of the heat exchange tube bundle, the other end of the exhaust pipeline is communicated with a chimney, and the exhaust pipeline is used for exhausting smoke; the combustible gas combustion indirect type heater further comprises a combustor communicated with the combustion chamber, a fuel gas pipeline communicated with the combustor and a fresh air pipeline communicated with the combustor, a preheater is arranged on the exhaust pipeline, and the fresh air pipeline is preheated through the preheater. Electric heating is replaced by fuel gas, so that energy consumption is reduced, and cost is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of oxidation furnaces, in particular to a gas-fired indirect heating type pre-oxidation furnace for a carbon fiber production line. Background Art

[0002] The pre-oxidation furnace on the carbon fiber production line refers to a heat treatment furnace used to perform oxidation heat treatment on the precursor to prepare oxidized fibers. As the component with the highest energy consumption in the entire carbon fiber production line, its research direction is mostly focused on heat treatment efficiency, temperature uniformity and other aspects;

[0003] In the prior art, a Chinese utility model patent with publication number CN202913112U disclosed a carbon fiber preoxidation furnace on May 1, 2013, which adopts electric heating and blows air from the middle of the furnace body to both ends. It is a system consisting of several heat treatment chambers connected in series and presenting a certain temperature gradient, and adopts a PLC temperature control module, so that the preoxidation process has the characteristics of high temperature control accuracy and high temperature stability.

[0004] However, the inventors found that the use of electric heating will lead to a sharp increase in electricity consumption, and when electricity consumption is restricted in some areas, the pre-oxidation furnace will not work. Therefore, how to achieve energy saving and cost reduction has become a technical problem that needs to be solved urgently. Utility Model Content

[0005] In view of at least one of the above technical problems, the utility model provides a gas-fired indirect heating carbon fiber production line preoxidation furnace, which uses combustible gas instead of electricity as a heat source to reduce the cost during the operation of the preoxidation furnace.

[0006] According to a first aspect of the utility model, a gas-fired indirect heating carbon fiber production line preoxidation furnace is provided, comprising a furnace body and a combustible gas combustion indirect heater connected to the furnace body, the combustible gas combustion indirect heater comprising a combustion chamber arranged in the furnace body and a heat exchange tube bundle connected to the combustion chamber, the combustible gas combustion indirect heater also comprising an exhaust pipe having one end connected to the tail end of the heat exchange tube bundle and the other end connected to the chimney, for exhausting smoke;

[0007] The combustible gas combustion indirect heater also includes a burner connected to the combustion chamber, a gas pipeline connected to the burner, and a fresh air pipeline connected to the burner. The exhaust pipeline is provided with a preheater, and the fresh air pipeline is preheated by the preheater.

[0008] In some embodiments of the utility model, the furnace body further has an air flow baffle, and the process air flow flows through the combustion chamber and the outer wall of the heat exchange tube bundle in sequence under the guidance of the air flow baffle to be heated.

[0009] In some embodiments of the present invention, the combustion chamber and the heat exchange tube bundle are arranged horizontally, and the air flow baffle is arranged at the top or bottom of the combustion chamber and the heat exchange tube bundle.

[0010] In some embodiments of the present invention, the combustion chamber and the heat exchange tube bundle are arranged vertically, and the airflow baffle is disposed on one side of the combustion chamber and the heat exchange tube bundle and is located on one side in the flow direction of the process airflow.

[0011] In some embodiments of the utility model, a guide plate is further included, which is arranged on a side of the combustion chamber and the heat exchange tube bundle away from the air flow baffle, and the guide plates are respectively fixed to the top and bottom of the furnace body, and the two guide plates are arranged opposite to each other, and their openings are arranged toward the combustion chamber.

[0012] In some embodiments of the present invention, the cross-section of the combustion chamber is in the shape of a water drop, including an arc segment and a tip connected to the arc segment to form a closed curved surface.

[0013] In some embodiments of the present invention, the heat exchange tube bundle is communicated with the tip, and the heat exchange tube bundle includes a plurality of ventilation tubes arranged in parallel and at intervals, and the ventilation tubes are symmetrically arranged along the surface to which the tip points.

[0014] In some embodiments of the present invention, the plurality of ventilation tubes are connected in a circuitous structure.

[0015] In some embodiments of the utility model, among the multiple ventilation tubes, half of the ventilation tubes close to the tip are connected to the same side of the other half of the ventilation tubes, so that the heated airflow can flow in parallel and circuitously through the multiple ventilation tubes at the same time.

[0016] In some embodiments of the utility model, the furnace body includes a main chamber and a side chamber connected to one end and the middle of the main chamber, the combustible gas combustion indirect heater is arranged in the side chamber, the side chamber also has a filter and a fan, the end of the main chamber has an air sealing structure, the process airflow enters from the main chamber into the side chamber, and then enters into the middle of the main chamber through the fan, forming a circulating process airflow.

[0017] The beneficial effects of the utility model are as follows: the utility model uses a combustible gas combustion indirect heater instead of electricity as a heat source in the carbonization process of carbon fiber precursor in the pre-oxidation furnace. During the specific heating, the combustible gas burns in the combustion chamber and discharges the hot gas through the heat exchange tube bundle, the combustion chamber and the heat exchange tube bundle are heated, and the process airflow in the furnace body passes through the outer wall of the combustion chamber and the gaps between the heat exchange tube bundles, the process airflow is heated, that is, the heat exchange effect of the process airflow and the combustible gas after heating is achieved. Compared with the electricity in the prior art, it not only reduces energy consumption, but also saves costs; in addition, in the utility model, the fresh air is heated by a preheater, waste heat recovery is achieved, and thermal efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the structure of a pre-oxidation furnace for a carbon fiber production line indirectly heated by gas in an embodiment of the utility model;

[0020] Figure 2 It is a schematic structural diagram of a combustible gas combustion indirect heater arranged horizontally in an embodiment of the utility model;

[0021] Figure 3 It is a schematic structural diagram of a combustible gas combustion indirect heater arranged longitudinally in an embodiment of the utility model;

[0022] Figure 4 It is a structural schematic diagram of the furnace body in the embodiment of the utility model. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0026] like Figures 1 to 4 The gas-fired indirect heating type carbon fiber production line preoxidation furnace shown comprises a furnace body 1 and a combustible gas combustion indirect heater 2 connected to the furnace body 1, the combustible gas combustion indirect heater 2 comprises a combustion chamber 21 arranged in the furnace body 1 and a heat exchange tube bundle 22 connected to the combustion chamber 21, the combustible gas combustion indirect heater 2 also comprises an exhaust pipe 25 having one end connected to the tail end of the heat exchange tube bundle 22 and the other end connected to the chimney, for exhausting flue gas;

[0027] The combustible gas combustion indirect heater 2 also includes a burner 23 connected to the combustion chamber 21 , a gas pipeline 24 connected to the burner 23 , and a fresh air pipeline 26 connected to the burner 23 . The exhaust pipeline 25 is provided with a preheater 27 , and the fresh air pipeline 26 is preheated by the preheater 27 .

[0028] When heating the process gas flow, Figure 2 As shown in , the circulating process gas flow in the pre-oxidation furnace first flows through the side wall of the high-temperature combustion chamber 21 to be heated once, and then flows through the heat exchange tube bundle 22 to be further heated before leaving the combustible gas combustion indirect heater 2; Figure 1 As shown in , in some embodiments of the utility model, the combustible gas can be natural gas, liquefied petroleum gas or any other high calorific value, low-cost combustible gas; the combustible gas is mixed with air in the burner 23, and then enters the combustion chamber 21 to burn and generate high-temperature gas, which flows through the heat exchange tube bundle 22 and exchanges heat with the process airflow, and finally the preheated gas flows through the preheater 27 and is discharged to the chimney. In the embodiment of the utility model, the ambient fresh air flows through the preheater 27 before entering the burner 23, and the residual heat remaining after the combustion and heat exchange of the combustible gas is used to heat the ambient fresh air in the preheater 27; through the above-mentioned arrangement, energy is further utilized and waste is reduced.

[0029] In the above embodiment, the indirect heater 2 burning combustible gas is used instead of electricity as the heat source in the carbonization process of the carbon fiber precursor in the pre-oxidation furnace. During the specific heating, the combustible gas is burned in the combustion chamber 21 and the hot gas is discharged through the heat exchange tube bundle 22. The combustion chamber 21 and the heat exchange tube bundle 22 are heated. When the process airflow in the furnace body 1 passes through the outer wall of the combustion chamber 21 and the gap between the heat exchange tube bundles 22, the process airflow is heated, that is, the heat exchange effect of the process airflow and the combustible gas after heating is achieved. Compared with the electricity in the prior art, it not only reduces energy consumption but also saves costs. In addition, in the utility model, the fresh air is heated by the preheater 27, so that waste heat recovery is achieved and thermal efficiency is improved.

[0030] On the basis of the above embodiments, in some embodiments of the present invention, in order to further improve the heating uniformity of the process airflow, such as Figure 2 As shown in the figure, the furnace body 1 is also provided with an air flow baffle 3, and the process air flow flows through the combustion chamber 21 and the outer wall of the heat exchange tube bundle 22 in sequence under the guidance of the air flow baffle 3 to be heated. It should be pointed out here that in some embodiments of the utility model, the combustion chamber 21 and the heat exchange tube bundle 22 are arranged horizontally, and the air flow baffle 3 is arranged at the top or bottom of the combustion chamber 21 and the heat exchange tube bundle 22. Through this arrangement, the process air flow, under the action of the air flow baffle 3, all flows through the combustion chamber 21 first and then flows through the heat exchange tube bundle 22, thereby ensuring that the process air flow can be evenly heated.

[0031] In another embodiment of the present invention, Figure 3 As shown in , the combustion chamber 21 and the heat exchange tube bundle 22 are arranged vertically, and the airflow baffle 3 is arranged on one side of the combustion chamber 21 and the heat exchange tube bundle 22, and is on the side in the flow direction of the process airflow. It also includes a guide plate 31, which is arranged on the side of the combustion chamber 21 and the heat exchange tube bundle 22 away from the airflow baffle 3. The guide plates 31 are respectively fixed to the top and bottom of the furnace body 1, and the two guide plates 31 are arranged oppositely, and the openings of the two are arranged toward the combustion chamber 21. Through the arrangement of this structural form, a chamber for changing the direction of the process airflow is formed between the airflow baffle 3 and the guide plate 31, and the combustion chamber 21 and the heat exchange tube bundle 22 are both in the chamber. Through the arrangement of this structural form, the heat loss can be reduced and the heat utilization rate can be further improved.

[0032] In the embodiment of the utility model, there is no restriction on the structural form of the air flow baffle 3 and the guide plate 31, which can be an arc-shaped or airfoil-shaped structure. In addition, in some embodiments of the utility model, the structural form of the combustion chamber 21 and the heat exchange tube bundle 22 is improved, such as Figure 2 and Figure 3As shown in the figure, the cross section of the combustion chamber 21 is in the shape of a water drop, including a circular arc segment and a tip 21b connected with the circular arc segment to form a closed curved surface. Through the arrangement of this water drop-shaped structure, when the process gas flow passes through the outer wall of the combustion chamber 21, it will flow along the outer wall of the combustion chamber 21, thereby improving the efficiency of heating and ensuring the stability of the gas flow.

[0033] Please continue to refer to Figure 2 and Figure 3 In some embodiments of the present invention, the heat exchange tube bundle 22 is connected to the tip 21b, and the heat exchange tube bundle 22 includes a plurality of vent pipes 22a arranged in parallel and spaced apart, and the vent pipes 22a are symmetrically arranged along the surface pointed by the tip 21b. Through this arrangement, the process airflow flowing through the surface of the combustion chamber 21 directly enters the gap between each vent pipe 22a along the tip 21b, thereby achieving further heating.

[0034] In addition, please continue to refer to Figure 1 In order to improve the heat exchange effect of the high-temperature gas after combustion of the gas in the heat exchange tube bundle 22, the multiple ventilation pipes 22a are connected in a circuitous structure. However, the inventors have found that if the total length of the circuitous structure is too long, it will cause the accumulation of heat at the front end. In order to reduce the occurrence of this situation, in some embodiments of the utility model, such as Figure 1 As shown in the figure, among the multiple vent pipes 22a, half of the vent pipes 22a near the tip 21b are connected to the same side of the other half of the vent pipes 22a, so that the heated airflow flows in parallel and circuitously from the multiple vent pipes 22a at the same time. By connecting one side of the general vent pipe 22a to the same side of the other half of the vent pipes 22a, the simultaneous flow of multiple pipes is achieved, the flow pressure is reduced, the stability of the high-temperature gas flow is improved, and the uniform reliability of heat exchange is improved.

[0035] Please refer to Figure 4 In some embodiments of the utility model, the furnace body 1 includes a main chamber 11 and a side chamber 12 connected to one end and the middle of the main chamber 11. The indirect heater 2 for combustion of gas is arranged in the side chamber 12. The side chamber 12 also has a filter 13 and a fan 14. The end of the main chamber 11 has an air seal structure 15. The process airflow enters the side chamber 12 from the main chamber 11, and then enters the middle of the main chamber 11 through the fan 14 to form a circulating process airflow. It should be pointed out here that the main chamber 11 is the chamber where the wire-cutting channel is located, and the side chamber 12 is a non-wire-cutting chamber. In the embodiment of the utility model, the indirect heater 2 for combustion of gas can be located behind the filter 13 and before the fan 14, or behind the fan 14 and before the central distributor, or located at any position in the side chamber 12 that can heat the process airflow.

[0036] Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the description are only for explaining the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which are within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A gas-fired indirect heating type carbon fiber production line preoxidation furnace, characterized in that: The indirect heater for combustion of combustible gas comprises a furnace body and a combustible gas combustion indirect heater connected to the furnace body, wherein the combustible gas combustion indirect heater comprises a combustion chamber arranged in the furnace body and a heat exchange tube bundle connected to the combustion chamber, and the combustible gas combustion indirect heater also comprises an exhaust pipe connected to the tail end of the heat exchange tube bundle at one end and to the chimney at the other end for exhausting flue gas; The combustible gas combustion indirect heater also includes a burner connected to the combustion chamber, a gas pipeline connected to the burner, and a fresh air pipeline connected to the burner. The exhaust pipeline is provided with a preheater, and the fresh air pipeline is preheated by the preheater.

2. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 1, characterized in that: The furnace body is also provided with an air flow baffle, and the process air flow flows through the combustion chamber and the outer wall of the heat exchange tube bundle in sequence under the guidance of the air flow baffle to be heated.

3. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 2, characterized in that: The combustion chamber and the heat exchange tube bundle are arranged horizontally, and the air flow baffle is arranged at the top or bottom of the combustion chamber and the heat exchange tube bundle.

4. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 2, characterized in that: The combustion chamber and the heat exchange tube bundle are arranged vertically, and the air flow baffle is arranged on one side of the combustion chamber and the heat exchange tube bundle and is located on one side in the flow direction of the process air flow.

5. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 4, characterized in that: It also includes a guide plate, which is arranged on the side of the combustion chamber and the heat exchange tube bundle away from the air flow baffle. The guide plates are respectively fixed to the top and bottom of the furnace body, and the two guide plates are arranged opposite to each other, and their openings are arranged toward the combustion chamber.

6. The gas-fired indirect-heated carbon fiber production line preoxidation furnace according to any one of claims 1 to 5, characterized in that: The cross section of the combustion chamber is in the shape of a water drop, comprising an arc segment and a tip connected with the arc segment to form a closed curved surface.

7. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 6, characterized in that: The heat exchange tube bundle is communicated with the tip end, and the heat exchange tube bundle includes a plurality of ventilation tubes arranged in parallel and at intervals, and the ventilation tubes are symmetrically arranged along the surface to which the tip end points.

8. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 7, characterized in that: The plurality of ventilation pipes are connected in a circuitous structure.

9. The gas-fired indirect heating carbon fiber production line preoxidation furnace according to claim 8, characterized in that: Among the multiple ventilation tubes, half of the ventilation tubes close to the tip are connected to the same side of the other half of the ventilation tubes, so that the heated airflow can flow in parallel and circuitously through the multiple ventilation tubes at the same time.

10. The gas-fired indirect heating type carbon fiber production line preoxidation furnace according to claim 1, characterized in that: The furnace body includes a main chamber and a side chamber connected to one end and the middle of the main chamber. The combustible gas combustion indirect heater is arranged in the side chamber. The side chamber also has a filter and a fan. The end of the main chamber has an air sealing structure. The process airflow enters the side chamber from the main chamber, and then enters the middle of the main chamber through the fan to form a circulating process airflow.

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