Oxidized tail gas treatment system in carbon fiber production and carbon fiber production system

Abstract

The utility model relates to an oxidized tail gas treatment system in carbon fiber production and a carbon fiber production system, the tail gas treatment system comprises: an ammonia gas absorption tower, the upper part of which is provided with an acid liquor feed port and a tail gas outlet, and the lower part of which is provided with a tail gas inlet and a liquid phase outlet; the upper portion of each hydrogen cyanide absorption tower is provided with a liquid alkali inlet and a gas outlet, the lower portion of each hydrogen cyanide absorption tower is provided with a gas inlet and a liquid outlet, and the gas inlet of the first-stage hydrogen cyanide absorption tower is communicated with the tail gas outlet. The gas inlet of the adjacent next-stage hydrogen cyanide absorption tower is communicated with the gas outlet of the adjacent previous-stage hydrogen cyanide absorption tower; and the phase splitting mechanism is communicated with the liquid phase outlet and is provided with an oil phase outlet and a water phase outlet. According to the utility model, the ammonia gas in the tail gas reacts with the dilute sulphuric acid introduced into the ammonia gas absorption tower to remove the ammonia gas, and the sodium hydroxide solution introduced into the hydrogen cyanide absorption tower reacts with the hydrogen cyanide in the tail gas to generate sodium cyanide and remove the hydrogen cyanide.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical production equipment, and in particular relates to an oxidation tail gas treatment system in carbon fiber production and a carbon fiber production system. Background Art

[0002] Carbon fiber (CF) is a recently developed reinforcing material with a carbon content exceeding 90%. Carbon fiber boasts excellent properties such as high strength, high modulus, low density, high-temperature resistance, corrosion resistance, electrical and thermal conductivity, low coefficient of expansion, shock absorption, and self-lubrication. It is widely used in aviation, aerospace, national defense, transportation, industrial production, textiles, and sports.

[0003] In the related art, the precursor fiber carbonization method is generally used to produce carbon fibers. Specifically, organic materials such as polyacrylonitrile precursor are used as raw materials and are oxidized at a temperature of 200-300°C in the presence of oxygen. During this process, cyclization, dehydrogenation, and oxidation reactions occur, and the polyacrylonitrile macromolecular chain is converted into a cyclic ladder structure, making it infusible and non-flammable during subsequent high-temperature carbonization, so that the fiber shape can be maintained. After the oxidation process, the fiber changes from white to yellow, brown, and then black to obtain oxidized fiber. Next, the oxidized fiber is carbonized in an atmosphere of protective gas (such as nitrogen, helium, neon, argon, etc.). After cross-linking, the straight-chain macromolecules are converted into a fused ring structure, and the carbon content also increases to about 95%, forming a layered graphite sheet structure connected by ladder-shaped six-membered rings. During the carbonization process, at low temperatures, the hydrogen and nitrogen in the macromolecular structure are separated from the fiber mainly in the form of water, methane, hydrogen cyanide, and ammonia. In order to improve the fiber morphology and increase the surface activity, the carbonized fiber is usually surface treated by surface oxidation, surface coating, surface chemical methods, etc.

[0004] The oxidation, low-temperature carbonization, and high-temperature carbonization processes generate large amounts of tail gas, releasing toxic and hazardous gases such as hydrogen cyanide and ammonia, along with some tar. Direct discharge into the atmosphere can cause severe air pollution. The oxidation stage produces a large amount of tail gas, with temperatures between 100-200°C, and contains relatively low concentrations of toxic and hazardous gases such as hydrogen cyanide and ammonia (less than 0.1%).

[0005] At present, the tail gas generated in the oxidation process is mostly treated by combustion emission or adsorption. The typical treatment method for the tail gas generated in the oxidation process is to use a box-type regenerative thermal incinerator (RTO). However, this method has high operating temperature, high fuel consumption, high operating cost, large incineration exhaust volume, and the treated hydrogen cyanide cannot meet the industrial pollutant emission standard (<0.3mg / m 3 ), and some hydrogen cyanide and ammonia will be oxidized into nitrogen oxides, which will cause secondary pollution to the air, and the tail gas is not comprehensively utilized. Utility Model Content

[0006] In view of this, the utility model provides a carbon fiber production oxidation tail gas treatment system and a carbon fiber production system, in order to solve the problem that the tail gas generated in the above oxidation process is mostly treated by combustion emission or adsorption method. The typical treatment method of the tail gas generated in the oxidation process is to use a box-type regenerative thermal incinerator (RTO), but this method has high operating temperature, high fuel consumption, high operating cost, large incineration exhaust volume, and the treated hydrogen cyanide cannot meet the industrial pollutant emission standard (<0.3mg / m 3 ), and some hydrogen cyanide and ammonia will be oxidized into nitrogen oxides, which will cause secondary pollution to the air, and there are technical problems such as the failure to comprehensively utilize the tail gas.

[0007] In order to realize the above scheme, the technical solution of the present utility model is as follows:

[0008] In a first aspect, the utility model provides an exhaust gas treatment system, comprising:

[0009] The ammonia absorption tower has an acid liquid feed inlet and tail gas outlet at the top, and a tail gas inlet and liquid phase outlet at the bottom;

[0010] At least two stages of hydrogen cyanide absorption towers, all of which are provided with a liquid alkali inlet and a gas outlet at their upper portions, and with an air inlet and a liquid outlet at their lower portions, the air inlet of the first stage of the hydrogen cyanide absorption tower being connected to the tail gas outlet, and the air inlet of the adjacent next stage of the hydrogen cyanide absorption tower being connected to the gas outlet of the adjacent previous stage of the hydrogen cyanide absorption tower; and

[0011] The phase separation mechanism is communicated with the liquid phase outlet, and the phase separation mechanism is provided with an oil phase outlet and a water phase outlet.

[0012] The principle of the tail gas treatment system of the present invention is: by arranging an acid liquid feed port at the upper part of the ammonia absorption tower, dilute sulfuric acid and other substances can be fed into the ammonia absorption tower through the acid liquid feed port; by arranging a tail gas inlet port at the lower part of the ammonia absorption tower, the tail gas generated in the oxidation process in the carbon fiber production can be fed into the ammonia absorption tower through the tail gas inlet port; the ammonia and other substances contained in the tail gas react with the dilute sulfuric acid introduced into the ammonia absorption tower from the acid liquid feed port, thereby removing the ammonia in the tail gas. By arranging a liquid alkali inlet at the upper part of the hydrogen cyanide absorption tower, substances such as sodium hydroxide solution can be fed into the hydrogen cyanide absorption tower through the liquid alkali inlet; by arranging an air inlet at the lower part of the hydrogen cyanide absorption tower and connecting the air inlet of the first-stage hydrogen cyanide absorption tower to the tail gas outlet, tail gas treated by the ammonia absorption tower can enter the first-stage hydrogen cyanide absorption tower through the air inlet, and the sodium hydroxide solution introduced from the liquid alkali inlet reacts with hydrogen cyanide in the tail gas to generate sodium cyanide, thereby removing hydrogen cyanide from the tail gas; and by adding a phase separation mechanism connected to the liquid phase outlet of the ammonia absorption tower, liquid-liquid separation can be performed on the liquid phase system after the ammonia is removed, thereby recovering by-products such as tar and ammonium sulfate in the liquid phase system, thereby improving economic benefits.

[0013] Optionally, a packing section and a tray section are sequentially provided between the acid solution feed port and the liquid phase outlet, and the tray section is provided with a plurality of sieve plates located on the side wall from top to bottom.

[0014] Specifically, the utility model arranges a packing section and a tower plate section in sequence between the acid liquid feed inlet and the liquid phase outlet of the ammonia absorption tower, and the tower plate section is provided with a plurality of sieve plates located on the side walls from top to bottom. The packing can ensure the absorption effect of the tail gas, and the plurality of sieve plates located on the side walls arranged from top to bottom of the tower plate section can prevent the extremely small amount of tar contained in the exhaust gas from clogging the ammonia absorption tower, thereby ensuring the smooth progress of production.

[0015] Optionally, a first spray assembly is provided on the top of the ammonia absorption tower, and the first spray assembly is connected to the acid solution feed port.

[0016] Specifically, the utility model provides a first spray assembly on the top of the ammonia absorption tower and connects the first spray assembly to the acid liquid feed port. The first spray assembly can increase the contact area between dilute sulfuric acid and other substances and the exhaust gas generated in the oxidation process in carbon fiber production, thereby better removing ammonia and other substances in the exhaust gas.

[0017] Optionally, the ammonia absorption tower is provided with a liquid level meter, and the liquid phase outlet is connected to the liquid level meter signal.

[0018] Specifically, the utility model is to configure the ammonia absorption tower to be equipped with a liquid level meter, and connect the liquid phase outlet to the liquid level meter signal, so that the material in the ammonia absorption tower can be discharged in time when the liquid level reaches a certain level, thereby improving the processing efficiency.

[0019] Optionally, the phase separation mechanism adopts a liquid-liquid separator.

[0020] Optionally, the hydrogen cyanide absorption tower is a packed tower.

[0021] Optionally, a second spray assembly is provided on the top of the hydrogen cyanide absorption tower, and the second spray assembly is connected to the liquid alkali inlet.

[0022] Specifically, the utility model provides a second spray assembly at the top of the hydrogen cyanide absorption tower and connects the second spray assembly to the liquid alkali inlet. The second spray assembly can increase the contact area between substances such as sodium hydroxide solution and the exhaust gas generated in the oxidation process in carbon fiber production, thereby better removing substances such as hydrogen cyanide from the exhaust gas.

[0023] Optionally, the tail gas treatment system further includes a tar storage container, which is connected to the oil phase outlet.

[0024] Optionally, an acid liquid circulation inlet is provided at the upper part of the ammonia absorption tower, and the acid liquid circulation inlet is connected to a connecting pipe between the phase separation mechanism and the liquid phase outlet. A first circulation pump is provided on the connecting pipe between the acid liquid circulation inlet and the liquid phase outlet, and the first circulation pump is connected to the phase separation mechanism.

[0025] Specifically, the utility model sets an acid liquid circulation inlet at the upper part of the ammonia absorption tower, and connects the acid liquid circulation inlet to the connecting pipe between the phase separation mechanism and the liquid phase outlet. A first circulation pump is provided on the connecting pipe between the acid liquid circulation inlet and the liquid phase outlet. The first circulation pump is connected to the acid liquid circulation inlet, so that the unreacted dilute sulfuric acid and other substances in the system can be sent into the ammonia absorption tower again, thereby improving the resource utilization rate of the dilute sulfuric acid and reducing the production cost.

[0026] Optionally, an alkali solution circulation inlet is provided at the upper portion of the hydrogen cyanide absorption tower, the alkali solution circulation inlet is connected to the liquid outlet, and a second circulation pump is provided on the connecting pipe between the alkali solution circulation inlet and the liquid outlet.

[0027] Specifically, the utility model provides an alkali solution circulation inlet at the upper part of the hydrogen cyanide absorption tower, connects the alkali solution circulation inlet to the liquid outlet, and adds a second circulation pump on the connecting pipe between the alkali solution circulation inlet and the liquid outlet, so that substances such as sodium hydroxide that have not reacted completely in the system can be sent into the hydrogen cyanide absorption tower again, thereby improving the resource utilization rate of substances such as sodium hydroxide and reducing production costs.

[0028] Optionally, a sampling port is provided on the connecting pipe between the alkali liquid circulation inlet of the last-stage hydrogen cyanide absorption tower and the liquid alkali inlet, and the alkali liquid circulation inlet of the upper-stage absorption tower adjacent to the last-stage hydrogen cyanide absorption tower is connected to the connecting pipe between the alkali liquid circulation inlet of the last-stage hydrogen cyanide absorption tower and the liquid outlet.

[0029] Specifically, the utility model provides a sampling port on the connecting pipe between the alkali liquid circulation inlet of the subsequent hydrogen cyanide absorption tower and the liquid alkali inlet, and connects the alkali liquid circulation inlet of the previous hydrogen cyanide absorption tower adjacent to the last hydrogen cyanide absorption tower with the connecting pipe between the alkali liquid circulation inlet of the last hydrogen cyanide absorption tower and the liquid outlet, so that the sodium hydroxide and other substances that have not reacted completely in the system of the subsequent hydrogen cyanide absorption tower can be sent back into the previous hydrogen cyanide absorption tower, thereby improving the resource utilization rate of the sodium hydroxide and other substances and reducing the production cost.

[0030] Optionally, the tail gas treatment system further includes a reactor, a first end of the reactor is connected to the second circulation pump, a second end of the reactor is connected to a drying device, and a delivery pump, a hydrocyanic acid removal device and a multi-effect evaporation concentration device are sequentially provided on the connecting pipe between the reactor and the drying device.

[0031] Specifically, the utility model adds a reactor connected to a second circulation pump, connects the reactor to a drying device, and sequentially provides a delivery pump, a hydrocyanic acid removal device, and a multi-effect evaporation concentration device on a communication pipeline between the reactor and the drying device. This allows for the recovery of substances such as sodium cyanide discharged from the waste liquid outlet of the second circulation pump, thereby generating by-products such as sodium sulfate and hydroxyacetonitrile, thereby improving resource utilization and economic benefits.

[0032] In a second aspect, the present invention further provides a carbon fiber production system, which includes the exhaust gas treatment system as described above.

[0033] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present application and, together with the specification, serving to explain the principles of the present application. It is obvious that the drawings described below are merely some embodiments of the present application, and a person of ordinary skill in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

[0035] Figure 1 Schematic diagram of the structure of the tail gas treatment system of Example 1;

[0036] Figure 2 Schematic diagram of the structure of the tail gas treatment system of Example 2;

[0037] Figure 3 Schematic diagram of the structure of the tail gas treatment system of Example 3;

[0038] Figure 4 Schematic diagram of the structure of the tail gas treatment system of Example 4;

[0039] Figure 5 This is a schematic structural diagram of the tail gas treatment system of Example 5.

[0040] Reference numerals

[0041] 1-Phase separation mechanism;

[0042] 2- ammonia absorption tower, 21- packing section, 22- tray section, 221- sieve plate, 23- liquid level gauge;

[0043] 3-hydrogen cyanide absorption tower;

[0044] 4- Tar storage container;

[0045] 5- Second circulation pump;

[0046] 6-reactor;

[0047] 7- Drying equipment;

[0048] 8- delivery pump;

[0049] 9-hydrocyanic acid removal device;

[0050] 10-Multiple-effect evaporation and concentration device;

[0051] 11-First circulation pump. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] It should be noted that all directional indications (such as up, down, top, bottom, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0054] In this utility model, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean mechanical connection or signal connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0055] In addition, the descriptions of "first", "second", etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "A and / or B" appearing throughout the text includes three parallel solutions, and "A and / or B" includes Solution A, Solution B, or a solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model. In related technologies, oxidation, low-temperature carbonization, high-temperature carbonization and other processes will produce a large amount of tail gas, releasing toxic and harmful gases such as hydrogen cyanide and ammonia, and carrying some tar. If directly discharged into the atmosphere, it will seriously pollute the air. The total amount of tail gas in the oxidation stage is large, the temperature is between 100-200°C, and the concentration of toxic and harmful gases such as hydrogen cyanide and ammonia is relatively low (less than 0.1%). At present, the tail gas generated in the oxidation process is mostly treated by combustion emission or adsorption method. The typical treatment method for tail gas generated in the oxidation process is to use a box-type regenerative thermal incinerator (RTO). However, this method has high operating temperature, high fuel consumption, high operating cost, large incineration exhaust volume, and the treated hydrogen cyanide cannot meet the industrial pollutant emission standard (less than 0.3mg / m 3 ), and some hydrogen cyanide and ammonia will be oxidized into nitrogen oxides, which will cause secondary pollution to the air, and the tail gas is not comprehensively utilized. Based on the above technical problems, one embodiment of the present invention provides a tail gas treatment system, which includes:

[0056] An ammonia absorption tower 2 is provided with an acid liquid feed inlet and an exhaust gas outlet at the top of the ammonia absorption tower 2. A first spray assembly is provided at the top of the ammonia absorption tower 2, and the first spray assembly is connected to the acid liquid feed inlet. A exhaust gas inlet and a liquid phase outlet are provided at the bottom of the ammonia absorption tower 2. A packing section 21 and a tray section 22 are provided in sequence between the acid liquid feed inlet and the liquid phase outlet. The tray section 22 is provided with a plurality of sieve plates 221 located on the side wall from top to bottom. A liquid level gauge 23 is provided at the ammonia absorption tower 2, and the liquid phase outlet is connected to the liquid level gauge 23 for signal connection.

[0057] At least two stages of hydrogen cyanide absorption towers 3, each of which is a packed tower. A liquid alkali inlet and a gas outlet are provided at the top of the hydrogen cyanide absorption tower 3, an air inlet and a liquid outlet are provided at the bottom of the hydrogen cyanide absorption tower 3, a second spray assembly is provided at the top of the hydrogen cyanide absorption tower 3, the second spray assembly is connected to the liquid alkali inlet, the air inlet of the first-stage hydrogen cyanide absorption tower 3 is connected to the tail gas outlet, and the air inlet of the adjacent lower-stage hydrogen cyanide absorption tower 3 is connected to the gas outlet of the adjacent upper-stage hydrogen cyanide absorption tower 3; and

[0058] The phase separation mechanism 1 adopts a liquid-liquid separator, the phase separation mechanism 1 is connected to the liquid phase outlet, and the phase separation mechanism is provided with an oil phase outlet and a water phase outlet.

[0059] In another embodiment of the present invention, the oil phase outlet is connected to a tar storage container 4 .

[0060] In another embodiment of the present invention, an acid liquid circulation inlet is provided at the upper portion of the ammonia absorption tower 2, and the acid liquid circulation inlet is connected to a connecting pipe between the phase separation mechanism 1 and the liquid phase outlet. A first circulation pump 11 is provided on the connecting pipe between the acid liquid circulation inlet and the liquid phase outlet, and the first circulation pump 11 is connected to the acid liquid circulation inlet, and the first circulation pump 11 is connected to the phase separation mechanism 1.

[0061] In another embodiment of the present invention, an alkali solution circulation inlet is provided on the upper portion of the hydrogen cyanide absorption tower 3 , the alkali solution circulation inlet is connected to the liquid outlet, and a second circulation pump 5 is provided on the connecting pipe between the alkali solution circulation inlet and the liquid outlet.

[0062] In another embodiment of the present invention, a sampling port is provided on the connecting pipe between the alkali liquid circulation inlet and the liquid alkali inlet of the last-stage hydrogen cyanide absorption tower 3, and the alkali liquid circulation inlet of the adjacent upper-stage hydrogen cyanide absorption tower 3 is connected to the connecting pipe between the alkali liquid circulation inlet and the liquid outlet of the last-stage hydrogen cyanide absorption tower 2.

[0063] In another embodiment of the present invention, the tail gas treatment system further includes a reactor 6, a first end of the reactor 6 is connected to the second circulation pump 5, a second end of the reactor 6 is connected to a drying device 7, and a delivery pump 8, a hydrocyanic acid removal device 9 and a multi-effect evaporation concentration device 10 are sequentially provided on the connecting pipe between the reactor 6 and the drying device 7.

[0064] Another embodiment of the present invention further provides a carbon fiber production system, comprising the exhaust gas treatment system as described above.

[0065] The present invention is described in detail below through specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not limited to the specific values ​​​​in the following examples.

[0066] Example 1

[0067] See also Figure 1 , Figure 1 Schematic diagram of the structure of the tail gas treatment system shown in this embodiment. The tail gas treatment system can be used to treat the tail gas generated in the oxidation process during the production of carbon fiber.

[0068] like Figure 1 As shown, the tail gas treatment system of this embodiment includes a phase separation mechanism 1, a tar storage container 4, an ammonia absorption tower 2 and at least two stages of hydrogen cyanide absorption towers 3 that are connected in sequence.

[0069] Please continue reading Figure 1 The ammonia absorption tower 2 is used as a place to remove ammonia substances from the tail gas. The upper part of the ammonia absorption tower 2 is provided with an acid liquid feed port and a tail gas outlet. The top of the ammonia absorption tower 2 is provided with a first spray assembly (not shown), which is connected to the acid liquid feed port. The lower part of the ammonia absorption tower 2 is provided with a tail gas inlet and a liquid phase outlet. A packing section 21 and a tray section 22 are sequentially provided between the acid liquid feed port and the liquid phase outlet. The tray section 22 is provided with a plurality of sieve plates 221 located on the side wall from top to bottom. The ammonia absorption tower 2 is provided with a liquid level meter 23, and the liquid phase outlet is connected to the liquid level meter 23 signal. In the ammonia absorption tower 2, substances such as ammonia in the tail gas react with substances such as dilute sulfuric acid entering the ammonia absorption tower 2 from the acid liquid feed port, thereby removing ammonia and other substances from the tail gas.

[0070] Specifically, this embodiment is provided with a packing section 21 and a tray section 22 in sequence between the acid liquid feed port and the liquid phase outlet of the ammonia absorption tower 2, and the tray section 22 is provided with a plurality of sieve plates 221 located on the side wall from top to bottom. The packing can ensure the absorption effect of the tail gas, and the sieve plates 221 located on the side wall provided from top to bottom of the tray section 22 prevent the small amount of tar contained in the tail gas from clogging the ammonia absorption tower 2, thereby ensuring the smooth progress of production. By configuring the ammonia absorption tower 2 to be provided with a liquid level gauge 23 and connecting the liquid phase outlet to the liquid level gauge 23 signal, the material level in the ammonia absorption tower 2 can be discharged in time when it reaches a certain level. By adding a first spray assembly to the top of the ammonia absorption tower 2 and connecting the first spray assembly to the acid liquid feed port, the contact area between the sulfuric acid solution and the tail gas can be increased by the first spray assembly, thereby better removing ammonia from the tail gas.

[0071] Please continue reading Figure 1 The hydrogen cyanide absorption tower 3 is used to remove hydrogen cyanide from the tail gas. A liquid caustic soda inlet and a gas outlet are located at the top of the hydrogen cyanide absorption tower 3. An air inlet and a liquid outlet are located at the bottom of the hydrogen cyanide absorption tower 3. A second spray assembly (not shown) is located at the top of the hydrogen cyanide absorption tower 3 and is connected to the liquid caustic soda inlet. The air inlet of the first-stage hydrogen cyanide absorption tower 5 is connected to the tail gas outlet of the ammonia absorption tower 2. The air inlet of the adjacent lower-stage hydrogen cyanide absorption tower 3 is connected to the gas outlet of the adjacent upper-stage hydrogen cyanide absorption tower 3. The final-stage hydrogen cyanide absorption tower 3 is provided with a tail gas exhaust port. Within the hydrogen cyanide absorption tower 3, the sodium hydroxide solution introduced through the liquid caustic soda inlet reacts with the hydrogen cyanide in the tail gas to produce sodium cyanide, thereby removing the hydrogen cyanide from the tail gas.

[0072] Specifically, this embodiment provides a second spray assembly at the top of the hydrogen cyanide absorption tower 3 and connects the second spray assembly to the liquid alkali inlet. The second spray assembly can increase the contact area between the sodium hydroxide solution and the exhaust gas generated in the oxidation process in the carbon fiber production, thereby better removing substances such as hydrogen cyanide in the exhaust gas.

[0073] Please continue reading Figure 1 The phase separation mechanism 1 is used as a place for liquid-liquid separation of the liquid phase system after the reaction in the ammonia absorption tower 2. The phase separation mechanism 1 is connected to the liquid phase outlet. The phase separation mechanism is provided with an oil phase outlet and a water phase outlet. The phase separation mechanism 1 adopts a liquid-liquid separator.

[0074] Specifically, this embodiment sets the phase separation mechanism 1 to be connected to the liquid phase outlet of the ammonia absorption tower 2, so as to perform liquid-liquid separation on the liquid phase system after the ammonia is removed, and then recover by-products such as tar and ammonium sulfate in the liquid phase system, thereby improving economic benefits.

[0075] Please continue reading Figure 1The tar storage container 4 is used as a storage place for the tar separated by the phase separation mechanism 1, and the tar storage container 4 is connected to the oil phase outlet of the phase separation mechanism 1.

[0076] All of the above communicating pipes are provided with switch valves (not shown).

[0077] The principle of the tail gas treatment system of this embodiment is: by setting an acid liquid feed port at the upper part of the ammonia absorption tower 2, sulfuric acid solution can be fed into the ammonia absorption tower 2 through the acid liquid feed port; by setting a tail gas inlet port at the lower part of the ammonia absorption tower 2, the tail gas generated by the oxidation process in the carbon fiber production (such as the tail gas from the oxidation furnace in the carbon fiber production process) can be fed into the ammonia absorption tower 2 through the tail gas inlet port; the ammonia contained in the tail gas reacts with the sulfuric acid solution introduced into the ammonia absorption tower 2 from the acid liquid feed port, thereby removing the ammonia in the tail gas. By arranging a liquid alkali inlet at the upper part of the hydrogen cyanide absorption tower 3, substances such as sodium hydroxide solution can be fed into the hydrogen cyanide absorption tower 3 through the liquid alkali inlet. By arranging an air inlet at the lower part of the hydrogen cyanide absorption tower 3 and connecting the air inlet of the first-stage hydrogen cyanide absorption tower 3 to the tail gas outlet, the tail gas treated by the ammonia absorption tower 2 can enter the first-stage hydrogen cyanide absorption tower 3 through the air inlet, and substances such as sodium hydroxide solution introduced from the liquid alkali inlet react with substances such as hydrogen cyanide in the tail gas to generate sodium cyanide, thereby removing hydrogen cyanide from the tail gas. By adding a phase separation mechanism connected to the liquid phase outlet of the ammonia absorption tower, liquid-liquid separation can be performed on the liquid phase system after the ammonia is removed, and by-products such as tar and ammonium sulfate in the liquid phase system can be recovered, thereby improving economic benefits.

[0078] Example 2

[0079] See also Figure 2 , Figure 2 This is a schematic structural diagram of the exhaust gas treatment system shown in this embodiment.

[0080] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that an acid liquid circulation inlet is provided at the top of the ammonia absorption tower 2, the acid liquid circulation inlet is connected to the connecting pipe between the phase separation mechanism 1 and the liquid phase outlet, a first circulation pump 11 is provided on the connecting pipe between the acid liquid circulation inlet and the liquid phase outlet, the first circulation pump 11 is connected to the phase separation mechanism 1, and the connecting pipes between the first circulation pump 11 and the phase separation mechanism 1 and between the first circulation pump 11 and the acid liquid circulation inlet are both provided with on-off valves. The first circulation pump can be a centrifugal pump, which is a prior art and will not be described in detail here.

[0081] Specifically, this embodiment sets an acid liquid circulation inlet at the upper part of the ammonia absorption tower 2, and sets a first circulation pump 11 and a switch valve on the connecting pipe between the acid liquid circulation inlet and the phase separation mechanism 1 and the liquid phase outlet. The first circulation pump 11 is provided on the connecting pipe between the acid liquid circulation inlet and the liquid phase outlet, which can send the unreacted dilute sulfuric acid and other substances in the system into the ammonia absorption tower 2 again, thereby improving the resource utilization rate of dilute sulfuric acid and reducing production costs.

[0082] Example 3

[0083] See also Figure 3 , Figure 3 This is a schematic structural diagram of the exhaust gas treatment system shown in this embodiment.

[0084] like Figure 3 As shown, this embodiment differs from Embodiment 2 in that an alkali solution circulation inlet is provided at the top of each hydrogen cyanide absorption tower 3, the alkali solution circulation inlet being connected to the liquid outlet, and a second circulation pump 5 is provided on the connecting pipe between the alkali solution circulation inlet and the liquid outlet. The second circulation pump 5 can be a centrifugal pump, which is a prior art and will not be described in detail here.

[0085] Specifically, this embodiment provides an alkali solution circulation inlet at the top of each hydrogen cyanide absorption tower 3, connects the alkali solution circulation inlet to the liquid outlet, and adds a second circulation pump 5 to the connecting pipe between the alkali solution circulation inlet and the liquid outlet. This allows unreacted sodium hydroxide and other substances in the system to be re-sent into the hydrogen cyanide absorption tower 3, thereby improving the resource utilization rate of sodium hydroxide and other substances and reducing production costs.

[0086] Example 4

[0087] See also Figure 4 , Figure 4 This is a schematic structural diagram of the exhaust gas treatment system shown in this embodiment.

[0088] like Figure 4 As shown, the difference between this embodiment and embodiment 3 is that a sampling port (not shown) is provided on the communication pipe between the alkali liquid circulation inlet and the liquid alkali inlet of the last-stage hydrogen cyanide absorption tower 3, and the alkali liquid circulation inlet of the upper-stage hydrogen cyanide absorption tower 3 adjacent to the last-stage hydrogen cyanide absorption tower 3 is connected to the communication pipe between the alkali liquid circulation inlet and the liquid outlet of the last-stage hydrogen cyanide absorption tower 3.

[0089] Specifically, this embodiment adds a sampling port (not shown) to the communication pipe between the alkali liquid circulation inlet and the liquid caustic soda inlet of the last-stage hydrogen cyanide absorption tower 3. The alkali liquid circulation inlet of the adjacent upper-stage hydrogen cyanide absorption tower 3 is connected to the communication pipe between the alkali liquid circulation inlet and the liquid outlet of the last-stage hydrogen cyanide absorption tower 3. The liquid in the communication pipe between the alkali liquid circulation inlet and the liquid caustic soda inlet of the last-stage hydrogen cyanide absorption tower 3 can be sampled and analyzed through the sampling port. If the sodium cyanide concentration in the liquid in the communication pipe between the alkali liquid circulation inlet and the liquid caustic soda inlet of the last-stage hydrogen cyanide absorption tower 3 is equal to or greater than a preset concentration threshold, the liquid in the communication pipe between the alkali liquid circulation inlet and the liquid caustic soda inlet of the last-stage hydrogen cyanide absorption tower 3 is fed into the upper-stage hydrogen cyanide absorption tower, thereby improving the resource utilization rate of substances such as sodium hydroxide and reducing production costs.

[0090] Example 5

[0091] See also Figure 5 , Figure 5 This is a schematic structural diagram of the exhaust gas treatment system shown in this embodiment.

[0092] like Figure 5 As shown, the difference between this embodiment and Example 4 is that: it further includes a reactor 6, the first end of the reactor 6 is connected to the second circulation pump 5, the second end of the reactor 6 is connected to the drying device 7, and the connecting pipe between the reactor 6 and the drying device 7 is sequentially provided with a delivery pump 8, a hydrocyanic acid removal device 9 and a multi-effect evaporation concentration device 10, and the connecting pipe between the hydrocyanic acid removal device 9 and the multi-effect evaporation concentration device 10 and the connecting pipe between the multi-effect evaporation concentration device 10 and the drying device 7 are both provided with a centrifugal pump (not shown) and an on-off valve (not shown).

[0093] Please continue reading Figure 5 The reactor 6 is provided with a liquid inlet, through which substances such as sulfuric acid solution can be added to the reactor. The sulfuric acid solution and other substances can react with the sodium cyanide contained in the waste liquid discharged from the waste liquid outlet of the second circulation pump 5 to generate sodium sulfate and hydrogen cyanide.

[0094] Please continue reading Figure 5, the delivery pump 8 is used to transport the reaction mixture in the reactor 6 to the hydrocyanic acid removal device 9. The hydrocyanic acid removal device 9 is provided with a hydrogen cyanide gas outlet. In the hydrocyanic acid removal device 9, the hydrogen cyanide in the reaction mixture is separated and discharged from the hydrogen cyanide gas outlet. The hydrogen cyanide gas outlet is connected to the hydroxyacetonitrile reactor (not shown). The production of hydroxyacetonitrile using hydrogen cyanide gas as raw material is an existing technology and will not be described in detail here. The hydrocyanic acid removal device 9 can adopt a distillation tower or the like. The system for removing hydrogen cyanide is pumped by a centrifugal pump to a multi-effect evaporation concentration device 10, where water and other substances evaporate from the system. Subsequently, the concentrated system (mainly composed of sodium sulfate) is pumped to a drying device 7. The drying device 7 is used to dry the concentrated system to obtain sodium sulfate as a by-product.

[0095] Specifically, this embodiment is configured to have a second circulating pump 5 with a waste liquid outlet, the waste liquid outlet is connected to a reactor 6, the reactor 6 is connected to a drying device 7, and a delivery pump 8, a hydrocyanic acid removal device 9 and a multiple-effect evaporation concentration device 10 are sequentially provided on the connecting pipe between the reactor 6 and the drying device 7. It is possible to recover substances such as sodium cyanide discharged from the waste liquid outlet of the second circulating pump 5, and then generate by-products sodium sulfate and hydroxyacetonitrile using sodium cyanide and hydrogen cyanide as raw materials, thereby improving resource utilization and improving economic benefits.

[0096] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed in the present invention are intended to be covered by the claims of the present invention.

Claims

1. An exhaust gas treatment system, characterized in that: The tail gas treatment system includes: The ammonia absorption tower has an acid liquid feed inlet and tail gas outlet at the top, and a tail gas inlet and liquid phase outlet at the bottom; At least two stages of hydrogen cyanide absorption towers, all of which are provided with a liquid alkali inlet and a gas outlet at their upper portions, and with an air inlet and a liquid outlet at their lower portions, the air inlet of the first stage of the hydrogen cyanide absorption tower being connected to the tail gas outlet, and the air inlet of the adjacent next stage of the hydrogen cyanide absorption tower being connected to the gas outlet of the adjacent previous stage of the hydrogen cyanide absorption tower; and The phase separation mechanism is communicated with the liquid phase outlet, and the phase separation mechanism is provided with an oil phase outlet and a water phase outlet.

2. The exhaust gas treatment system according to claim 1, characterized in that: A packing section and a tray section are sequentially provided between the acid liquid feed port and the liquid phase outlet, and the tray section is provided with a plurality of sieve plates located on the side wall from top to bottom; And / or, a first spray assembly is provided on the top of the ammonia absorption tower, and the first spray assembly is connected to the acid solution feed port.

3. The exhaust gas treatment system according to claim 1, characterized in that: The ammonia absorption tower is provided with a liquid level meter, and the liquid phase outlet is connected to the liquid level meter signal.

4. The exhaust gas treatment system according to claim 1, characterized in that: The phase separation mechanism adopts a liquid-liquid separator; And / or, the hydrogen cyanide absorption tower is a packed tower; And / or, a second spray assembly is provided on the top of the hydrogen cyanide absorption tower, and the second spray assembly is connected to the liquid alkali inlet.

5. The exhaust gas treatment system according to claim 1, wherein: The invention also includes a tar storage container, which is connected to the oil phase outlet.

6. The exhaust gas treatment system according to claim 1, characterized in that: An acid liquid circulation inlet is provided at the upper portion of the ammonia absorption tower, and the acid liquid circulation inlet is connected to a connecting pipe between the phase separation mechanism and the liquid phase outlet. A first circulation pump is provided on the connecting pipe between the acid liquid circulation inlet and the liquid phase outlet, and the first circulation pump is connected to the phase separation mechanism.

7. The exhaust gas treatment system according to claim 1, wherein: An alkali solution circulation inlet is provided on the upper portion of the hydrogen cyanide absorption tower, the alkali solution circulation inlet is connected to the liquid outlet, and a second circulation pump is provided on the communication pipeline between the alkali solution circulation inlet and the liquid outlet.

8. The exhaust gas treatment system according to claim 7, characterized in that: A sampling port is provided on the connecting pipe between the alkali liquid circulation inlet of the last-stage hydrogen cyanide absorption tower and the liquid alkali inlet, and the alkali liquid circulation inlet of the upper-stage hydrogen cyanide absorption tower adjacent to the last-stage hydrogen cyanide absorption tower is connected to the connecting pipe between the alkali liquid circulation inlet of the last-stage hydrogen cyanide absorption tower and the liquid outlet.

9. The exhaust gas treatment system according to claim 7, characterized in that: The invention also includes a reactor, wherein the first end of the reactor is connected to the second circulation pump, the second end of the reactor is connected to a drying device, and the connecting pipe between the reactor and the drying device is provided with a delivery pump, a hydrocyanic acid removal device and a multi-effect evaporation concentration device in sequence.

10. A carbon fiber production system, characterized in that: The carbon fiber production system includes the exhaust gas treatment system according to any one of claims 1 to 9.

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