JP2013032608A - Method for processing exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing exhaust gas in a manufacturing process of flameproof fibers or carbon fibers that is to solve problems such as an operation rate, and decreases in energy consumption and atmospheric environmental load of an exhaust gas treatment, and is also inexpensive and excellent from a viewpoint of global environment.SOLUTION: There is provided a method for processing exhaust gas in production processes of flameproof fibers and/or carbon fibers. The method is used in a process for producing flameproof fibers which has a flameproofing furnace for flameproofing precursor fibers by a heated oxidative gas and/or in a process, after the process for producing flameproof fibers, for producing carbons fibers which has a carbonization furnace for carbonizing the flameproof fibers by a heated inert gas. In the method, exhaust gases in the furnaces and/or in the ambient atmosphere of the furnaces are collected and subjected to a degradation treatment. In the exhaust gases, at least an exhaust gas in the flameproofing furnace, an exhaust gas in an ambient atmosphere of the flameproofing furnace, and an exhaust gas in an ambient atmosphere of the carbonization furnace are subjected to a degradation treatment using a heat storage type exhaust gas treatment equipment.

Description

  The present invention relates to an exhaust gas treatment method in a production process of flameproof fiber or carbon fiber. More specifically, the present invention relates to an exhaust gas treatment method in which at least a part of exhaust gas is subjected to exhaust gas treatment with a regenerative exhaust gas treatment facility.

  The flame resistant fiber is usually a precursor of acrylic fiber or pitch fiber, which is a precursor, in a heat treatment furnace called a flame resistant furnace or an infusible furnace (hereinafter collectively referred to as a flame resistant furnace in the present invention). Obtained by heat treatment in an oxidizing gas such as air at 200 to 400 ° C. (hereinafter collectively referred to as flameproofing treatment), and the carbon fiber is heated to a higher temperature in a carbonization furnace. It is manufactured by heating and carbonizing in an inert gas such as nitrogen and argon. In addition, when manufacturing carbon fiber, the manufacturing process of the flame-resistant fiber (hereinafter referred to as flame resistance process) and the subsequent manufacturing process of carbon fiber (hereinafter referred to as carbonization process) are usually manufactured in a continuous line. It may be manufactured separately on a separate line. Further, the flameproofing furnace in the flameproofing process and the carbonizing furnace in the carbonizing process are not limited to one furnace each, and may be processed in a plurality of divided furnaces.

  Here, the exhaust gas discharged in the flame-proofing process (hereinafter referred to as flame-resistant exhaust gas) and the exhaust gas discharged in the carbonization process (hereinafter referred to as carbonized exhaust gas) are the exhaust gas extracted from the flame-proofing furnace and the furnace body of the carbonizing furnace, Depending on the type of gas, it is composed of exhaust gas that collects ambient gas around the furnace for the purpose of collecting the gas leaked from the inlet / outlet of the furnace body. It contains a wide variety of compounds resulting from the thermal decomposition of the oil agent, ammonia, carbon monoxide, carbon dioxide, methane, hydrogen cyanide, vaporized tar components, etc. It is necessary to release it to the atmosphere after detoxifying it. Therefore, in Patent Document 1, the flame-resistant exhaust gas and the carbonized exhaust gas are introduced and mixed outside the flame-resistant furnace and the carbonized furnace, respectively, and the mixed gas is contained in the gas in an oxidation catalyst type or direct combustion type exhaust gas treatment facility. Components are decomposed and released to the atmosphere.

  However, in this oxidation catalyst formula, the solid matter deposited by treatment clogs the catalyst over time, so depending on the amount of compound to be treated contained in the exhaust gas, the maintenance cycle is short, which affects the operating rate of the manufacturing process. May end up. In particular, in the flameproofing step, when a silicon-based oil is applied to the precursor fiber, a large amount of silicon-based compounds resulting from thermal decomposition in the flameproofing furnace are contained in the flameproof exhaust gas. Further, in the carbonization process, heating is performed in the carbonization furnace at a much higher atmospheric temperature than in the flameproofing furnace, so that a large amount of heat loss occurs in the precursor fibers, and a large amount of pyrolyzate is contained in the carbonized exhaust gas. When the thermal decomposition product goes out of the carbonization furnace and the temperature decreases, it condenses as a tar component and dramatically increases the deterioration rate of the oxidation catalyst device. Therefore, as an exhaust gas treatment method in the production process of flameproof fiber or carbon fiber, it is usual to use a direct combustion type exhaust gas treatment facility (for example, see Patent Document 2).

  On the other hand, in the direct combustion type, fuel such as kerosene, LNG, LPG is always burned and the exhaust gas is decomposed in a high-temperature atmosphere (about 750 ° C or higher), so it is generated by energy consumption and fuel combustion and released to the atmosphere. The amount of carbon dioxide and nitrogen compounds to be produced is enormous. Therefore, as in Patent Document 2 or Patent Document 3, waste heat of exhaust gas after combustion is recovered by a heat exchanger such as a tube type, a multi-tube type, or a plate type to preheat the exhaust gas before combustion, and supply the flameproofing furnace. Although it is used for preheating of air, etc., it is necessary to increase the equipment size in order to increase the heat transfer surface area due to the equipment structure, and in the equipment size considering industrial equipment cost profitability Waste heat recovery is not enough and energy consumption is still large.

  As another type of exhaust gas treatment facility, a heat storage type exhaust gas treatment facility as disclosed in, for example, Patent Document 4 is generally known. The heat storage type is similar to the direct combustion type, but is characterized by having a plurality of heat storage regions containing a heat storage material as preheating heat exchange before the combustion region for burning exhaust gas. The exhaust gas is passed through any one of a plurality of heat storage regions, introduced into the combustion region, decomposed in the combustion region, and then operated to discharge the other heat storage region as an outlet. . Since the heat storage material accommodated in the heat storage area serving as the outlet gradually becomes hot when operation is continued for a while, the heat storage area serving as the inlet and the heat storage area serving as the outlet are sequentially switched every predetermined time, and the heat storage area becomes high temperature. The exhaust gas is operated from the exhaust gas. As described above, the heat storage type exhaust gas treatment facility performs the decomposition treatment of the exhaust gas while minimizing the energy brought out by the exhaust gas after combustion and effectively utilizing the energy for preheating the exhaust gas. In addition, the heat storage material in the heat storage region has a structure with a large heat transfer surface area, such as a honeycomb, and is a tube type, multi-tube type, plate type, etc. heat exchanger for direct combustion exhaust gas treatment equipment. In comparison, since the amount of heat exchange per unit size is large, the waste heat recovery rate is high, and the energy consumption can be greatly suppressed.

  The heat storage area of the heat storage type exhaust gas treatment facility has a very small problem of clogging compared to the oxidation catalyst method described above, but it is still difficult to operate for a long time depending on the solid amount of the compound contained in the exhaust gas. An example of direct application to exhaust gas treatment in a fiber or carbon fiber production process has not been known. In particular, when a conventional heat storage type exhaust gas treatment facility is applied as it is to a flameproof yarn manufacturing process or a carbonized yarn manufacturing process, the condensate of the tar component contained in the carbonized exhaust gas causes the heat storage region to become clogged, resulting in an extreme maintenance cycle. There was a problem that would decrease.

JP 59-142826 A JP 2009-174078 A JP 2010-223471 A Japanese Patent Laid-Open No. 9-264521

  The problem to be solved by the present invention is to solve the problem of the prior art, which is the reduction of the operating rate of exhaust gas treatment equipment, the energy consumption and the atmospheric environmental load, and is excellent from the viewpoint of the global environment at low cost. An object of the present invention is to provide an exhaust gas treatment method in a process for producing flame-resistant fibers or carbon fibers.

The present invention has the following configuration in order to solve the above problems. That is,
(1) A process for producing a flame-resistant fiber having a flame-resistant furnace for making the precursor fiber flame-resistant by a heated oxidizing gas, and / or a process for producing the flame-resistant fiber, and then heating the flame-resistant fiber to be inert. In the manufacturing process of carbon fiber having a carbonization furnace that is carbonized by gas, in the manufacturing process of flame-resistant fiber and / or carbon fiber that collects and decomposes the exhaust gas in the furnace and / or the exhaust gas in the atmosphere around the furnace An exhaust gas treatment method, wherein at least a part of the exhaust gas in the furnace of the flameproofing furnace, the exhaust gas in the atmosphere around the furnace of the flameproofing furnace, and the exhaust gas in the atmosphere around the furnace of the carbonization furnace among the exhaust gas is a regenerative exhaust gas treatment facility An exhaust gas treatment method comprising:

  (2) It has a drying process which has a dryer which dries the carbon fiber which adhered sizing processing liquid with hot air in the latter process of the manufacturing process of the above-mentioned carbon fiber, and at least a part of the exhaust gas of the above-mentioned dryer is the above-mentioned The exhaust gas treatment method according to claim 1, wherein the decomposition treatment is performed in a heat storage type exhaust gas treatment facility.

  (3) The exhaust gas treatment method according to (1) or (2), wherein the exhaust gas other than the exhaust gas to be processed by the regenerative exhaust gas treatment facility is decomposed by the direct combustion exhaust gas treatment facility. .

  (4) On the introduction side of the regenerative exhaust gas treatment facility, there is a line that allows the direct combustion exhaust gas treatment facility to decompose exhaust gas, and a line that enables the thermal storage exhaust gas treatment facility to decompose exhaust gas. The exhaust gas treatment method according to (3), further comprising switching means for switching both lines.

  (5) The exhaust gas according to any one of (1) to (4), wherein a means for collecting a solid of a silicon compound contained in the exhaust gas is provided before the introduction of the heat storage type exhaust gas treatment facility. Processing method.

  (6) The exhaust gas treatment method according to (5), wherein a bag filter is used as means for collecting the solids of the silicon-based compound contained in the exhaust gas.

  According to the present invention, it is possible to greatly improve the waste heat recovery rate after exhaust gas treatment without impairing the operation rate of the exhaust gas treatment facility, thereby suppressing the consumption of energy fuel and reducing the cost by reducing the fuel cost. It becomes feasible. At the same time, the amount of carbon dioxide and nitrogen compounds generated by fuel combustion is reduced, and excellent production can be performed from the viewpoint of ecology by reducing the atmospheric environmental load.

It is a schematic block diagram of the heat processing furnace which concerns on one embodiment of this invention. It is a schematic block diagram of the heat processing furnace which concerns on one embodiment of this invention. It is a schematic block diagram of the heat processing furnace which concerns on one embodiment of this invention. It is a general schematic block diagram of the heat processing furnace conventionally used. It is a schematic block diagram of the heat processing furnace which concerns on one embodiment of this invention. It is a schematic block diagram of the heat processing furnace which concerns on another one aspect | mode used conventionally.

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. In addition, this invention is not limited to the embodiment described in drawing.

  FIG. 1 is a schematic configuration diagram of an exhaust gas treatment method according to an embodiment of the present invention.

  The precursor fiber 1 is guided in the order of a flameproofing furnace 2 in a heated oxidizing gas atmosphere, and a carbonizing furnace A 3 and a carbonizing B furnace 4 in a heated inert gas atmosphere, where ordinary heating and firing are performed. As a result, the flame-resistant fiber 5 and the carbon fiber 6 are produced. Here, the treatment by the flameproofing furnace 2 is classified as a flameproofing process, and the treatment by the carbonizing A furnace 3 or the carbonizing B furnace 4 is classified as a carbonizing process, but the number of separate furnaces is not limited in each process, and further divided into a plurality. It may be processed in a furnace. The flameproofing step can be performed by heating and baking at 200 to 400 ° C., the carbonization step can be performed at a maximum of about 1800 ° C., and depending on the specific product, further heating and baking can be performed at a maximum of about 3000 ° C.

  Further, the flameproofing furnace 2, the carbonization A furnace 3, and the carbonization B furnace 4 are supplied with an oxidizing gas flameproof supply air 7, an inert gas carbonization furnace A supply air 8, and a carbonization B furnace supply air 9, and are flame resistant. Exhaust gas in the furnace 10, exhaust gas 11 in the carbonization furnace A, and exhaust gas 12 in the carbonization furnace B are exhausted to clean the inside of the furnace. Further, in-furnace gas leaks from the entrance / exit of the precursor fiber 1 in the flameproofing furnace 2, the carbonization A furnace 3, and the carbonization B furnace 4, and the precursor fiber itself and the applied oil agent are contained in the gas. Because it contains a wide variety of compounds, harmful components, vaporized tar components, etc. resulting from the thermal decomposition of methane, the flame exhaust furnace ambient atmosphere exhaust gas 13 and the carbonized A furnace ambient atmosphere exhaust gas are used to prevent effects on the work environment. 14. Local exhaust is performed with carbonized B furnace ambient atmosphere exhaust gas 15. Here, the flame exhaust furnace ambient atmosphere exhaust gas 13, the carbonization A furnace ambient atmosphere exhaust gas 14, and the carbonization B furnace ambient atmosphere exhaust gas 15 indicate local exhaust in an unsealed space from the furnace body, and are a seal box / seal Exhaust gas in a space sealed by connecting to a furnace body such as a pipe enters into the flame-resistant furnace exhaust gas 10, the carbonized A furnace exhaust gas 11, and the carbonized B furnace exhaust gas 12. Note that the flow rates of the flue gas 10 in the refractory furnace, the flue gas 11 in the carbonization A furnace, the flue gas 12 in the carbonization B furnace, the flue gas around the flame refractory furnace 13, the flue gas around the carbonization furnace A 14, and the flue gas around the carbonization B furnace Although not shown in the drawing, it is desirable in terms of production management to enable individual control using a manual adjustment damper, more preferably an automatic adjustment damper based on feedback control of flow rate detection.

  Further, the flue gas 10 in the flameproofing furnace, the flue gas 11 in the carbonizing furnace A, the flue gas 12 in the carbonizing furnace B, the flue gas around the flameproofing furnace 13, the flue gas around the carbonizing furnace A 14, and the flue gas around the carbonizing furnace B 15 are led to the outdoors. Although it is released to the atmosphere, the harmful components are decomposed before being released to the atmosphere. Here, the exhaust gas treatment equipment to be treated is classified according to the characteristics of each exhaust gas, specifically, the characteristics and amount of the compound contained in the exhaust gas. In the present embodiment, at least a part of the flame-resistant furnace exhaust gas 10, the flame-resistant furnace ambient atmosphere exhaust gas 13, the carbonized A furnace ambient atmosphere exhaust gas 14, and the carbonized B furnace ambient atmosphere exhaust gas 15 is stored in the regenerative exhaust gas treatment facility 16. The other gas is directly processed by the combustion type exhaust gas processing equipment 17. Control of the flow rate of the exhaust gas processed by the regenerative exhaust gas treatment facility 16 and the flow rate of the exhaust gas processed by the direct combustion exhaust gas treatment facility 17 can be performed by a switching means such as a direct combustion type damper 18. Although the direct combustion type damper 18 may be a manual adjustment damper, it is preferable in terms of production management to use an automatic adjustment damper by feedback control of flow rate detection.

  Exhaust gas to be processed by the regenerative exhaust gas treatment facility 16 is harmful to the exhaust gas in a high temperature atmosphere by burning fuel in the regenerative combustion area 21 via the regenerative A heat exchanger 20 in the exhaust gas line of the regenerative A line 19. Decompose components. The high-temperature exhaust gas after the treatment is heat-exchanged in the regenerative B heat exchanger 22 and the temperature is lowered, and then discharged to the atmosphere through the regenerative exhaust gas blower 23. Thereafter, the heat storage type A line 19 and the heat storage type B line 25 are switched by the heat storage type line switching damper 24, and the heat storage type B line 25 is introduced from the heat storage type B heat exchanger 22 which has become a high temperature and exchanges heat. After being preheated sufficiently by the heat storage, the decomposition process is performed in the regenerative combustion region 21, and this time the heat is exchanged in the regenerative A heat exchanger 20 and the temperature is lowered, and then the heat is discharged to the atmosphere via the regenerative exhaust gas blower 23. To. Further, by alternately switching between the heat storage type A line 19 and the heat storage type B line 25, preheating of the heat storage type exhaust gas is always performed, and the fuel consumption in the heat storage type combustion region 21 can be suppressed to a small amount. it can. In addition, as a timing which switches a line alternately, the introduction direction of untreated exhaust gas and the discharge direction of treated exhaust gas are reversed every predetermined time (for example, refer patent document 4), for example, every predetermined time. However, it is preferable to measure the change in the exhaust gas temperature and the temperature of the heat storage material in the vicinity of the heat storage type A heat exchange 20 and the heat storage type B heat exchange 22 and to switch by feedback based on the output.

  On the other hand, in the direct combustion type exhaust gas treatment facility 17, the regenerative exhaust gas treatment facility 16 out of the flame resistant furnace exhaust gas 10, the flame resistant furnace surrounding atmosphere exhaust gas 13, the carbonized A furnace surrounding atmosphere exhaust gas 14, and the carbonized B furnace surrounding atmosphere exhaust gas 15. The exhaust gas other than that treated with the above, the carbonized A furnace exhaust gas 11 and the carbonized B furnace exhaust gas 12 are subjected to decomposition treatment.

  Since the carbonization A furnace 3 and the carbonization B furnace 4 are heated at an atmosphere temperature much higher than that of the flameproofing furnace 2, the flameproofing fiber 5 undergoes a large heating loss on a weight basis, and a large amount of pyrolyzate is generated. The pyrolyzate in the carbonized A exhaust gas 11 and the carbonized B exhaust gas 12 is condensed as a tar component when it comes out of the furnace, and this condensate is stored in the heat storage type A of the heat storage type exhaust gas treatment facility 16. The blockage of the heat exchanger 20 and the regenerative B heat exchanger 22 is promoted, and the maintenance cycle is extremely reduced. Therefore, the carbonized A in-furnace exhaust gas 11 and the carbonized B in-furnace exhaust gas 12 are not suitable for treatment by the regenerative exhaust gas treatment facility 16, and therefore, as in the present embodiment, In particular, it is preferable to perform treatment using the direct combustion type exhaust gas treatment equipment 17 which is not easily affected by the compounds contained in the exhaust gas.

  Further, since the main component of the carbonized A in-furnace exhaust gas 11 and the carbonized B in-situ exhaust gas 12 is an inert gas, an oxidizing gas is required for combustion in the direct combustion exhaust gas treatment facility 17. For this reason, air such as outside air may be newly supplied. However, in this embodiment, for further energy saving, the flue gas 10 in the flame-resistant furnace, the ambient gas 13 around the flame-resistant furnace, the ambient gas 14 around the carbonized A furnace, the carbonization B atmosphere surrounding exhaust gas 15 is to be substituted. The carbonized A furnace ambient atmosphere exhaust gas 14 and the carbonized B furnace ambient atmosphere exhaust gas 15 contain an inert gas, but can also be used as an oxidizing gas since the outside air is also sucked and mixed at the same time. Note that the amounts of the flue gas 10 in the flame-proofing furnace, the flue gas around the flame-proofing furnace 13, the flue gas around the carbonized A furnace 14 and the flue gas around the carbonized B furnace 15 which are directly taken to the flue gas treatment facility 17 are as follows. From the viewpoint of energy saving, it is preferable to use only the oxidizing gas necessary to burn the internal exhaust gas 11 and the carbonized B furnace exhaust gas 12 and bring the exhaust gas amount to the regenerative exhaust gas treatment facility 16 with as little fuel consumption as possible. preferable. Further, at least a part of the necessary oxidizing gas can be taken from outside without using the exhaust gas, for example, the atmosphere. The amount of the flue gas 10 in the flameproofing furnace and the ambient exhaust gas around the flameproofing furnace 14 and the ambient exhaust gas 14 around the carbonization A furnace 14 and the ambient exhaust gas 15 around the carbonization B furnace introduced into the direct combustion exhaust gas treatment equipment 17 are the direct combustion exhaust gas treatment equipment. The oxygen concentration in the exhaust gas to be treated is preferably 19% by volume or less and 13% by volume or more, and more preferably 17% by volume or less and 15% by volume or more. In addition, it becomes possible to raise energy-saving efficiency by making oxygen concentration into 19 volume% or less, and combustibility can be ensured by setting it as 13 volume% or more. A part of the amount of the flue gas 10 in the flameproofing furnace, the atmospheric exhaust gas 13 around the flameproofing furnace, the ambient exhaust gas 14 around the carbonization A furnace, and the ambient exhaust gas 15 around the carbonization B furnace processed directly by the direct combustion exhaust gas treatment facility 17 is directly The flow rate is controlled by the combustion type damper 18 and the fuel is burned in the direct combustion type combustion region 28 via the direct combustion type heat exchanger 27 in the exhaust gas line of the direct combustion type A line 26, and in the exhaust gas in a high temperature atmosphere. Decomposes harmful components. By direct heat exchange with the exhaust gas after combustion in the direct combustion type heat exchanger 27, the exhaust gas of the direct combustion type A line 26 is preheated, thereby suppressing the fuel consumption in the direct combustion type combustion region 28. it can.

  On the other hand, since the carbonized A in-furnace exhaust gas 11 and the carbonized B in-situ exhaust gas 12 contain a large amount of thermal decomposition products of precursor fibers as described above, in order to reduce condensation of tar components, direct combustion type B In line 29, heat is maintained by an electric heater 30 for exhaust gas in the carbonization furnace, and it is sent directly to the combustion type combustion region 28. The heat insulation of the electric heater 30 for exhaust gas in the carbonization furnace is preferably set to 200 ° C. or higher, more preferably 500 ° C. or higher. The direct combustion type B line 29 is connected to the direct combustion type heat exchange 27 like the direct combustion type A line 26 in order to prevent the direct combustion type heat exchange 27 from being blocked by the condensate of the tar component in the exhaust gas. It is preferable to connect directly to the combustion combustion zone 28 without going through. The exhaust gas of the direct combustion type A line 26 sent to the direct combustion type combustion region 28 and the exhaust gas of the direct combustion type B line 29 are mixed and subjected to decomposition treatment of harmful components in the exhaust gas in a high temperature atmosphere. After that, it is discharged directly to the atmosphere through the combustion exhaust gas blower 31.

  FIG. 2 is a schematic configuration diagram of an exhaust gas treatment method according to another embodiment of the present invention. When the heat storage type exhaust gas treatment facility 16 is maintained, the heat storage type damper 32 is fully closed and the direct combustion type damper 18 is fully opened so that all exhaust gases are directly processed by the direct combustion type exhaust gas treatment facility 17. If the exhaust gas treatment capacity of the combustion exhaust gas treatment facility 17 is set and designed, it is possible to perform maintenance of the regenerative exhaust gas treatment facility 16 while continuing production. At that time, by adjusting the flow rate with the damper 33 for the direct combustion type combustion region, the exhaust gas is directly combusted up to the upper limit of the flow rate according to the equipment size of an appropriate direct combustion type heat exchanger 27 determined from the installation space and equipment cost. If the exhaust gas having a flow rate higher than that through the outbound A line 26 is directly connected to the combustion combustion region 28, the operation mode is preferable from the viewpoint of energy saving considering the recovery of waste heat as much as possible. Further, the direct combustion type combustion region-bound damper 33 may be a manual adjustment damper, but it is preferable in terms of production management to use an automatic adjustment damper by feedback control of flow rate detection.

  FIG. 3 is a schematic configuration diagram of an exhaust gas treatment method according to still another embodiment of the present invention. This is a particularly preferable embodiment in which a silicon-based oil agent is applied to the precursor fiber 1 and the exhaust gas 10 in the flameproofing furnace contains a large amount of a solid material of a silicon compound resulting from the thermal decomposition of the oil agent. Here, in order to prevent the heat storage type A heat exchange 20 and the heat storage type B heat exchange 22 from being blocked by the solid material of the silicon compound, the flue gas 10 in the flameproofing furnace is not directly stored in the heat storage type exhaust gas treatment facility 16. If a line is configured to treat with the combustion type exhaust gas treatment equipment 17, and the flow rate to the direct combustion type heat exchanger 27 and the direct combustion type combustion region 28 can be adjusted by the exhaust gas damper 34 in the flameproofing furnace, It becomes possible to obstruct the direct combustion type heat exchanger 27 or avoid the upper limit of the flow rate of the direct combustion type A line 26. In addition, the flame-resistant furnace exhaust gas damper 34 may be a manual adjustment damper, but it is preferable in terms of production management to use an automatic adjustment damper by feedback control of flow rate detection.

  Further, assuming that the silicon-based compound solids are contained in the flue gas around the refractory furnace 13 as well, after the heat storage type damper 32, the heat storage type A line 19 and the heat storage type B line 25 The dust catching means 35 is installed before branching. The dust capturing means 35 includes an electric dust collector, a centrifuge, a bag filter, and the like, but a bag filter is most desirable from the viewpoint of installation space and equipment cost. The bag filter may be used for a general boiler or the like, but has a heat-resistant temperature of 200 ° C. or higher and a dust collection efficiency of 99% or higher, and dust accumulated by compressed air or the like can be periodically removed and discarded separately. If it is a thing, the lifetime improvement of a bug filter can be anticipated and it is more preferable.

  FIG. 5 is a schematic configuration diagram of an exhaust gas treatment method according to still another embodiment of the present invention. FIG. 5 includes a dryer 36 that dries carbon fibers to which a sizing treatment liquid is applied in order to improve the high-order workability after the carbonization step in FIG. 1, and is one of particularly preferable embodiments. The dryer 36 only needs to have a structure capable of collecting exhaust gas discharged from equipment such as a drum dryer or a hot air dryer, and there is no particular limitation on the number of dryers, and the dryer 36 is divided into a plurality of dryers. It may be a dryer. In addition, it is preferable to perform a drying process at 100 to 400 degreeC in oxidizing gas atmosphere.

  The exhaust gas 38 in the dryer is led to the outside and released to the atmosphere, but it is desirable to perform a harmful component decomposition process before releasing to the atmosphere. Since the exhaust gas 38 in the dryer includes harmful components generated by evaporation of the sizing treatment liquid, vaporized tar components, and the like, the exhaust gas in the exhaust gas treatment facility is the same as other exhaust gases other than the exhaust gas 38 in the dryer in FIG. It is desirable to decompose the harmful components contained in the product before releasing it into the atmosphere. In the present embodiment, at least a part of the exhaust gas 38 in the dryer is treated by the heat storage type exhaust gas treatment facility 16 like the other exhaust gases. A part of the amount of the exhaust gas 38 in the dryer to be processed by the direct combustion type exhaust gas treatment facility 17 is controlled by the dryer exhaust gas damper 42, and the direct combustion type heat exchange is performed in the exhaust line of the direct combustion type A line 26. 27, the fuel is burned in the direct combustion type combustion region 28 to decompose the harmful components in the exhaust gas in a high temperature atmosphere.

  5 is a mechanism that can control the flow rate of the exhaust gas 38 in the dryer to the regenerative exhaust gas treatment facility 16 and the direct combustion exhaust gas treatment facility 17 by the dryer exhaust gas damper 42. The exhaust gas 38 in the dryer may be connected in front of the pipe branch point 41, and the flow rate may be controlled by the direct combustion type damper 18 and the regenerative type line switching damper 24, which is limited to the mode specifically disclosed in FIG. It is not done.

  Since the exhaust gas 38 in the dryer contains harmful components generated by evaporation of the sizing treatment liquid, vaporized tar components, and the like as described above, the direct combustion type C line 40, C-line 39 for the regenerative type, C-line 39 for the regenerative type connected to the B-line 25 for the regenerative type, the line to the regenerative combustion region 21, and the C-line 40 for the direct combustion type become the A-line 26 for the direct combustion The line to the regenerative combustion region 28 after being connected is heated and kept warm by the electric heater 43 for exhaust gas in the dryer, and sent directly to the combustion combustion region 28 and the regenerative combustion region 21. The heating and keeping temperature of the electric heater 43 for exhaust gas in the dryer is preferably set to 100 ° C. or higher, more preferably 200 ° C. or higher. Other aspects are the same as in FIG.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
A yarn in which 12,000 PAN-precursor single yarns having a thickness of 1.1 dtex were bundled was subjected to flame resistance and carbonization treatment in the process flow as shown in FIG. However, the number of furnaces of the flameproofing furnace 2 is two, and the number of furnaces of the carbonization A furnace 3 and the carbonization B furnace 4 is one each. The atmosphere gas in the flameproofing furnace 2 uses air, and the atmosphere gas in the carbonization A furnace 3 and the carbonization B furnace 4 uses nitrogen. Each exhaust gas amount is 12,000 ³ / hr, carbonizing A furnace exhaust gas 11 is 1,000 Nm ³ / hr, carbonizing B furnace flue gas 12 together 2 furnace in oxidization furnace exhaust gas 10 is controlled by 500 Nm ³ / hr, The flame exhaust furnace ambient atmosphere exhaust gas 13, the carbonization A furnace ambient atmosphere exhaust gas 14, and the carbonization B furnace ambient atmosphere exhaust gas 15 are all 16,000 Nm ³ / hr. The carbonized A in-furnace exhaust gas 11 and the carbonized B in-furnace exhaust gas 12 are heated and kept at 500 ° C. by an electric heater 30 for carbonized furnace exhaust gas.

The heat storage type damper 32 is fully open, the direct combustion type damper 18 is an automatic flow rate adjustment type, the flow rate of the direct combustion type A line 26 is 5,000 Nm ³ / hr, the heat storage type A line 19 or the heat storage type B line. The flow rate of 25, that is, the amount of exhaust gas treated by the regenerative exhaust gas treatment facility 16 was set to 23,000 Nm ³ / hr. The heat storage type line switching damper 24 automatically controls to switch between the heat storage type A line 19 and the heat storage type B line 25 every 60 seconds. On the other hand, the exhaust gas to be processed by the direct combustion exhaust gas treatment equipment 17 is a flow rate of 1,500 Nm ³ / hr of the carbonized A furnace exhaust gas 11 and the carbonized B furnace exhaust gas 12 and a flow rate of 5,000 Nm of the direct combustion type A line 26. ^The total is 6,500 Nm ³ / hr at ³ / hr. The direct combustion type combustion region damper 33 is fully closed, and the flow rate 5,000 Nm ³ / hr of the direct combustion type A line 26 is all preliminarily heated via the direct combustion type heat exchanger 27, and then the direct combustion type. Processed in the combustion zone 28.

  The fuel is burned with kerosene so that the internal atmosphere temperature in the regenerative combustion region 21 and the direct combustion combustion region 28 is set to 800 ° C., and is continuously operated for 30 days under the operating conditions. The consumption was measured and the exhaust gas environmental load and the internal state of the equipment were observed. The results are shown in Table 1.

[Example 2]
A yarn obtained by bundling 12,000 PAN-based precursor yarns having a thickness of 1.1 dtex to which a silicone-based oil was applied was subjected to flame resistance and carbonization treatment in a process flow as shown in FIG. At this time, the direct combustion type damper 18 is fully closed and the heat storage type damper 32 is fully opened, and the flame-resistant furnace ambient atmosphere exhaust gas 13, the carbonized carbon A furnace ambient atmosphere exhaust gas 14, and the carbonized B furnace ambient atmosphere exhaust gas 15 are all regenerative exhaust gas treatment. It was made to process with the installation 16. However, no dust capturing means 35 is provided after the heat storage type damper 32 and before the heat storage type A line 19 and the heat storage type B line 25 branch off. In addition, about 90% of the flame-resistant furnace exhaust gas 10 is distributed to the direct combustion type heat exchanger 27 and the remaining 10% to the direct combustion type combustion region 28 by the flame resistant furnace exhaust gas damper 34.

All other conditions were the same as in Example 1, the amount of exhaust gas treated by the regenerative exhaust gas treatment facility 16 was 16,000 Nm ³ / hr, and the exhaust gas treated by the direct combustion exhaust gas treatment facility 17 was 13,500 Nm ³ / hr. Under these operating conditions, continuous operation was performed for 30 days, and the fuel consumption of each furnace was measured. The results are shown in Table 1.

  In addition, after the 30-day continuous operation of Example 2, the inside of the regenerative type A heat exchanger 20 and the regenerative type B heat exchanger 22 was checked. It has been confirmed that the continuous operation may require maintenance.

[Example 3]
Under the same conditions as in the second embodiment, a dust filter having a heat-resistant temperature of 200 ° C. or more and a dust collection efficiency of 99% or more as dust capturing means 35, and dust that is periodically deposited by compressed air can be removed and discarded separately. installed. Under these operating conditions, continuous operation was performed for 30 days, and the fuel consumption of each furnace was measured. The results are shown in Table 1.

  As in Example 2, after 30 days of continuous operation, the inside of the heat storage type A heat exchange 20 and the heat storage type B heat exchange 22 was checked. As a result, it was confirmed that there was a sufficient margin.

[Example 4]
The continuous operation was performed in the process flow including the dryer 36 as shown in FIG. However, the number of dryers 36 is one. Air is used as the atmosphere gas of the dryer 36. The amount of exhaust gas in the dryer exhaust gas 38 is controlled at 7,000 Nm ³ / hr. The exhaust gas 38 in the dryer is heated and kept at 200 ° C. by the electric heater 43 for exhaust gas in the dryer.

All other conditions are the same as in Example 1, the dryer exhaust gas damper 42 is fully closed, the direct combustion type damper 18 is an automatic flow rate adjustment type, and the flow rate of the heat storage type A line 19 or the heat storage type B line 25, That is, the amount of exhaust gas processed by the regenerative exhaust gas processing facility 16 was set to 30,000 Nm ³ / hr.

  Under these operating conditions, continuous operation was performed for 30 days, the fuel consumption of each furnace was measured, and the exhaust gas environmental load and the internal state of the equipment were observed. The results are shown in Table 2.

[Comparative Example 1]
A yarn obtained by bundling 12,000 PAN-precursor single yarns having a thickness of 1.1 dtex was subjected to flame resistance and carbonization treatment in a process flow as shown in FIG. All the generated exhaust gas is directly brought into the combustion type exhaust gas treatment facility 17 for combustion treatment. About 80% of the flue gas in the flameproofing furnace 10 is distributed to the direct combustion type heat exchanger 27 and the remaining 20% is distributed to the direct combustion type combustion area 28 by the damper 33 for the direct combustion type combustion area. All other conditions were the same as in Example 1. Under these operating conditions, continuous operation was performed for 30 days, and the fuel consumption of each furnace was measured. The results are shown in Table 1.

[Comparative Example 2]
A yarn obtained by bundling 12,000 PAN-based precursor yarns having a thickness of 1.1 dtex was subjected to flame resistance and carbonization treatment in a process flow as shown in FIG. All the generated exhaust gas is directly brought into the combustion type exhaust gas treatment facility 17 for combustion treatment. About 80% of the flue gas in the flameproofing furnace 10 is distributed to the direct combustion type heat exchanger 27 and the remaining 20% is distributed to the direct combustion type combustion area 28 by the damper 33 for the direct combustion type combustion area. All other conditions were the same as in Example 4. Under these operating conditions, continuous operation was performed for 30 days, and the fuel consumption of each furnace was measured. The results are shown in Table 2.

  In Example 1 and Example 2, the operating conditions are changed in order to prevent heat exchange blockage of the regenerative exhaust gas treatment facility depending on whether the precursor fiber contains a silicon-based oil. On the other hand, in Comparative Example 1, since the influence of the silicon compound contained in the exhaust gas on the direct combustion type exhaust gas treatment facility is small, the operating conditions are the same regardless of whether the precursor fiber contains the silicon oil. Shows constant kerosene consumption and environmental load. It is confirmed from Table 1 that the consumption of kerosene is greatly reduced by using heat storage type exhaust gas treatment equipment in comparison with Comparative Example 1, and the environmental load is also greatly reduced. Is done. In particular, in Example 1, since the silicon-based oil agent is not contained in the precursor fiber, the heat storage type exhaust gas treatment facility can be actively used, and the effect is great. Furthermore, in Example 3, it is possible to greatly extend the maintenance cycle by providing the dust capturing means in Example 2, and furthermore, it is possible to prevent the heat exchange performance from being deteriorated due to adhesion of the silicon compound. The amount of consumption is further reduced, which is a more preferable operation mode.

  Furthermore, in Example 4, in addition to Example 1, by treating the exhaust gas from the process flow having a dryer with a heat storage type exhaust gas treatment facility, the consumption of kerosene is greatly reduced compared to Comparative Example 2, and As a result, it is confirmed that the environmental load is greatly reduced. In addition, in the effect which compared Example 1 and Comparative Example 1, and the effect which compared Example 4 and Comparative Example 2, the effect in Example 4 is larger, and compared with Example 1, the amount of kerosene consumption and environmental load amount of From the viewpoint, it is a more preferable operation mode.

  As described above, according to the present invention, at least a part of the exhaust gas in the furnace of the flameproofing furnace, the exhaust gas in the atmosphere around the flameproofing furnace, the exhaust gas in the atmosphere around the furnace of the carbonization furnace, or in addition to this, at least a part of the exhaust gas in the dryer is stored. By using a waste gas treatment facility and providing dust capture means, the fuel of combustion energy can be greatly reduced without impairing the operation rate of the waste gas treatment facility, and the amount of environmental load generated by energy fuel can be reduced. Can be said.

  The exhaust gas treatment method according to the present invention is suitable for use in the production process of flameproof fiber or carbon fiber.

1: Precursor fiber 2: Flame resistance furnace 3: Carbonization furnace A 4: Carbonization furnace B 5: Flame resistance fiber 6: Carbon fiber 7: Flame resistance supply air 8: Carbonization furnace A supply 9: Carbonization furnace B supply 10 : Exhaust gas in a flame-resistant furnace 11: Exhaust gas in a carbonization A furnace 12: Exhaust gas in a carbonization B furnace 13: Exhaust gas around a flame-resistant furnace 14: Exhaust gas around a carbonization A furnace 15: Exhaust gas around a carbonization B furnace 16: Regenerative exhaust gas treatment Equipment 17: Direct combustion type exhaust gas treatment equipment 18: Direct combustion type damper 19: Thermal storage type A line 19
20: Thermal storage type A heat exchange 21: Thermal storage type combustion area 22: Thermal storage type B heat exchange 23: Thermal storage type exhaust gas blower 24: Thermal storage type line switching damper 25: Thermal storage type B line 26: Direct combustion type A line 27 : Direct combustion type heat exchange 28: Direct combustion type combustion area 29: Direct combustion type B line 30: Electric heater for exhaust gas in carbonization furnace 31: Direct combustion type exhaust gas blower 32: Regenerative type damper 33: Direct combustion type combustion area Outbound damper 34: Exhaust gas exhaust damper 35: Dust trapping means 36: Dryer 37: Dryer air supply 38: Dryer exhaust gas 39: Thermal storage type C line 40: Direct combustion type C line 41: Piping branch point 42: Dryer exhaust gas damper 43: Electric heater for exhaust gas in dryer

Claims (6)

After the production process of the flameproof fiber having a flameproofing furnace for making the precursor fiber flameproof with a heated oxidizing gas, and / or after the production process of the flameproof fiber, the flameproof fiber is carbonized with a heated inert gas. In the manufacturing process of carbon fiber having a carbonizing furnace, the exhaust gas in the furnace and / or the exhaust gas in the atmosphere around the furnace is collected and decomposed, and the flue gas treatment method in the manufacturing process of the flame resistant fiber and / or carbon fiber Of the exhaust gas, at least a part of the exhaust gas in the furnace of the flameproofing furnace, the exhaust gas in the atmosphere around the furnace of the flameproofing furnace, and the exhaust gas in the atmosphere around the furnace of the carbonization furnace is decomposed by a regenerative exhaust gas treatment facility. An exhaust gas treatment method comprising: The carbon fiber manufacturing process has a drying process having a dryer for drying the carbon fiber to which the sizing treatment liquid is attached with hot air, and at least a part of the exhaust gas of the dryer is the regenerative exhaust gas. The exhaust gas treatment method according to claim 1, wherein the decomposition treatment is performed in a treatment facility. The exhaust gas treatment method according to claim 1 or 2, wherein the exhaust gas other than the exhaust gas to be processed by the regenerative exhaust gas treatment facility is decomposed by the direct combustion exhaust gas treatment facility. On the introduction side of the regenerative exhaust gas treatment facility, both a line that enables exhaust gas decomposition treatment with the direct combustion exhaust gas treatment facility and a line that enables exhaust gas decomposition treatment with the regenerative exhaust gas treatment facility are provided. The exhaust gas treatment method according to claim 3, comprising switching means for switching. The exhaust gas treatment method according to any one of claims 1 to 4, wherein means for collecting a solid material of a silicon compound contained in the exhaust gas is provided before the introduction of the heat storage type exhaust gas treatment facility. The exhaust gas treatment method according to claim 5, wherein a bag filter is used as a means for collecting a solid substance of a silicon-based compound contained in the exhaust gas.

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