A device for recovering waste gas for desulfurization and bleaching of viscose staple

Abstract

The utility model discloses a kind of waste gas recovery for viscose staple desulfurization bleaching device, it is related to viscose fiber production and resource recycling technical field, including waste gas recovery system, wastewater treatment system and desulfurization bleaching system, the waste gas recovery system includes spray tower, the desulfurization bleaching tank system includes desulfurization bleaching tank, desulfurization bleaching tank bottom is provided with desulfurization bleaching storage tank, desulfurization bleaching tank and desulfurization bleaching storage tank are connected by circulation pump circulation;By the H2S waste gas in the fiber tank is absorbed to form NaHS by alkali spraying waste water;Then the waste water containing NaHS is used for desulfurization, bleaching process of desulfurization bleaching system after membrane treatment system, wherein NaHS and sulfur element (S) reaction generates sodium polysulfide, effectively dissolves fiber surface scale, while NaHS desulfurization to sliver, Na2S x Sliver reduction bleaching, so that desulfurization process and bleaching process can be carried out simultaneously.

Description

Technical Field

[0001] This utility model relates to the field of viscose fiber production and resource recycling technology, and in particular to a device and control method for waste gas recovery for desulfurization and bleaching of viscose staple fiber. Background Technology

[0002] Currently, in viscose fiber production, viscose reacts with an acid bath to produce filaments. These filaments then undergo drawing, washing, desulfurization, bleaching, oiling, drying, and packaging before being processed into finished products for sale. During the refining process, the filaments release gas containing a high concentration of hydrogen sulfide (H2S) at high temperatures, approximately 3000-4000 ppm. This H2S gas is absorbed by a 5-10% NaOH spray system, generating wastewater (pH 10-12) containing sodium hydrosulfide (NaHS) and sodium sulfide (Na2S). This wastewater is typically discharged to environmental treatment facilities, but stringent emission standards place significant environmental pressure on the industry, resulting in high treatment costs.

[0003] During the spinning process, the acid bath reacts with cellulose xanthate and xanthation byproducts in the viscose to generate a large amount of colloidal sulfur. Some of these colloidal sulfur particles are dispersed in the acid bath, some form colloids floating on the surface of the bath, and some are carried into the next process by the filaments, affecting product quality. Elemental sulfur (S8) often combines with hydroxyl (-OH) or amino (-NH2) groups on the fiber surface to form stable sulfur-sulfur crosslinking bonds (-SS-). The presence of these bonds leads to the appearance of yellow or brown chromogenic groups on the fiber surface, greatly reducing whiteness. Therefore, desulfurization of the filaments is particularly important. Currently, the desulfurization process is mainly carried out in the refining stage. The desulfurization process requires cleaning the filaments with NaOH and NaHS solutions of a certain concentration and temperature. NaOH and NaHS react with sulfur to generate sodium sulfide and sodium sulfite, thereby removing elemental sulfur from the filaments. Although this process can efficiently and thoroughly remove sulfur carried by the filaments, it requires the addition of excessive amounts of NaOH and NaHS to ensure complete reaction, which wastes resources and significantly increases production costs.

[0004] Therefore, to control production costs, the amount of chemical reagents used is limited. Thus, a simple desulfurization process is insufficient to achieve the required whiteness of viscose staple fibers, necessitating an additional bleaching process. Traditional processes use oxidative bleaching, where hydrogen peroxide or sodium hypochlorite solution of a certain concentration is used for cleaning or soaking after desulfurization. While oxidation significantly improves the whiteness of the fibers, excessive oxidation can lead to cellulose chain breakage and a 5-8% decrease in fiber strength. Furthermore, the COD content of the wastewater after hydrogen peroxide bleaching exceeds 2000 mg / L, increasing environmental pressure.

[0005] Patent publication number CN105603557B discloses a traditional Chinese medicine-based health-promoting regenerated cellulose fiber and its preparation method. The post-treatment process omits the bleaching step. The post-treatment washing temperature is 55℃, the desulfurization temperature is 80℃, sodium hydrosulfide is used for desulfurization at a concentration of 6g / L, and the oiling temperature is 50℃. However, the sodium hydrosulfide used in this patent is purchased externally, resulting in high costs. Furthermore, the patent omits the bleaching step because the added traditional Chinese medicine components have their own color, causing the fiber to have its own color, making further bleaching pointless. Therefore, omitting the bleaching process limits its application and prevents the production of ordinary viscose fiber. Summary of the Invention

[0006] This utility model aims to provide a device for waste gas recovery for desulfurization and bleaching of viscose staple fiber. It achieves desulfurization and bleaching of filaments by recovering H2S from the waste gas in the fiber feeding tank. By reducing bleaching, it avoids the fiber strength reduction caused by excessive oxidation and cellulose chain breakage. It realizes the recycling of sulfur element, the near-zero discharge of wastewater, and the cascade utilization of thermal energy.

[0007] To achieve the above-mentioned objectives, the technical solution of this utility model is as follows:

[0008] An apparatus for waste gas recovery in viscose staple fiber desulfurization and bleaching includes a waste gas recovery system, a wastewater treatment system, and a desulfurization and bleaching system. The waste gas recovery system includes a spray tower; the bottom inlet of the spray tower is connected to a waste gas pipeline supplying the fiber trough; the top inlet of the spray tower is connected to the outlet of an alkali solution mixing tank; and the bottom outlet of the spray tower is connected to the inlet of a wastewater storage tank. The wastewater treatment system includes a filter assembly for filtering solid impurities from the wastewater; the inlet of the filter assembly is connected to the outlet of the wastewater storage tank, and the outlet of the filter assembly is connected to the inlet of an intermediate wastewater tank. The desulfurization and bleaching system includes a desulfurization and bleaching tank; a desulfurization and bleaching storage tank is located at the bottom of the desulfurization and bleaching tank; the desulfurization and bleaching tank and the desulfurization and bleaching storage tank are circulated together by a circulation pump. The outlet of the intermediate wastewater tank is connected to the inlet of the desulfurization and bleaching tank, and the drain outlet of the desulfurization and bleaching storage tank is connected to a sewage pipeline.

[0009] The desulfurization and bleaching tank includes a desulfurization and bleaching tank I and a desulfurization and bleaching tank II arranged in sequence according to the filament travel route, and a channel for the filament to pass through is provided between the desulfurization and bleaching tank I and the desulfurization and bleaching tank II.

[0010] Below the desulfurization bleaching tank I and the desulfurization bleaching tank II, there are respectively a desulfurization bleaching storage tank I and a desulfurization bleaching storage tank II; the desulfurization bleaching tank I and the desulfurization bleaching storage tank I are circulatedly connected by circulation pump I, and the desulfurization bleaching tank II and the desulfurization bleaching storage tank II are circulatedly connected by circulation pump II.

[0011] The outlet of the intermediate wastewater tank is connected to the inlet of the desulfurization bleaching tank I, and the outlet of the desulfurization bleaching storage tank I and the inlet of the desulfurization bleaching storage tank II are connected by pipes; the sewage outlets of the desulfurization bleaching storage tank I and the desulfurization bleaching storage tank II are respectively connected to the sewage pipes.

[0012] The desulfurization and bleaching system also includes a bleaching tank. The desulfurization and bleaching tank and the bleaching tank are arranged in the order of the filament travel route, and a channel for the filament to pass through is provided between the desulfurization and bleaching tank and the bleaching tank.

[0013] The bottom of the bleaching tank is equipped with a bleaching water storage tank, and the bleaching tank and the bleaching water storage tank are connected by a circulation pump III.

[0014] The inlet of the bleaching tank is connected to a hydrogen peroxide mixing tank; the outlet of the bleaching water storage tank is connected to a sewage pipe; and the bleaching water storage tank is equipped with a demineralized water inlet.

[0015] The filtration assembly includes an ultrafiltration membrane mechanism and a ceramic membrane mechanism. The ultrafiltration membrane mechanism has an ultrafiltration membrane pore size of 500 μm, and the ceramic membrane mechanism has a ceramic membrane filter plate pore size of 0.1 μm.

[0016] The ultrafiltration membrane mechanism and the ceramic membrane mechanism are each equipped with a backwashing component.

[0017] The outlet of the intermediate wastewater tank is equipped with a plate heat exchanger; the heating medium pipeline of the plate heat exchanger is connected to the steam pipeline.

[0018] The desulfurization bleaching tank I and the desulfurization bleaching tank II are each equipped with a steam heating coil.

[0019] The bleaching tank has a jacketed structure, and the jacket is connected to a steam pipe.

[0020] The intermediate wastewater tank is equipped with an alkali replenishment pipeline I and a demineralized water pipeline.

[0021] The desulfurization bleaching tank I, the desulfurization bleaching tank II, and the alkali replenishment pipeline II for the bleaching water tank.

[0022] The beneficial effects of this utility model are:

[0023] 1. In this invention, H2S waste gas in the fiber feed tank is absorbed by alkaline spraying to generate NaHS wastewater; then, the NaHS-containing wastewater is used in the desulfurization and bleaching process of the desulfurization and bleaching system after passing through a membrane treatment system. NaHS reacts with elemental sulfur (S) to generate sodium polysulfide, effectively dissolving sulfur scale on the fiber surface. While NaHS desulfurizes the filaments, Na2S... xThe reduction bleaching of the filaments allows the desulfurization and bleaching processes to be carried out simultaneously. This achieves comprehensive treatment of waste gas and tiered utilization of wastewater, while also reducing the use of alkali and bleaching agents. Furthermore, this invention creatively couples the desulfurization and bleaching processes into a single step, shortening the process flow and reducing energy consumption.

[0024] 2. In this utility model, Na2S x The process achieves reductive bleaching of the filaments. In reductive bleaching, sodium polysulfide breaks down the -SS-chromogenic groups without attacking the cellulose molecular chains, resulting in fiber breaking strength higher than that achieved by oxidative bleaching with hydrogen peroxide. Reductive bleaching specifically eliminates yellowing caused by sulfur bonds, improving whiteness and creating a softer color. It avoids the decrease in fiber strength due to excessive oxidation and cellulose chain breakage, achieving sulfur recycling, near-zero wastewater discharge, and cascade utilization of thermal energy.

[0025] 3. In this invention, while NaHS is used to desulfurize the filaments, elemental sulfur (S) reacts to generate Na2S. x Na2S x The silk strips are subjected to reduction bleaching, while in the invention patent with patent publication number CN105603557B, the silk strips are dyed by the added Chinese herbal ingredients, so further bleaching is meaningless and the bleaching process is eliminated. The technical concepts and purposes of the two are different, and the invention purpose of this application is fundamentally different from that of the prior art. Those skilled in the art have no motivation to combine the two. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the waste gas recovery system and wastewater treatment system in the device for desulfurization and bleaching of viscose staple fiber according to this utility model.

[0027] Figure 2 This is a schematic diagram of the desulfurization and bleaching system in the waste gas recovery device of this utility model used for desulfurization and bleaching of viscose staple fiber.

[0028] The system includes: 1. Waste gas recovery system; 2. Wastewater treatment system; 3. Desulfurization and bleaching system; 101. Spray tower; 102. Alkali solution mixing tank; 103. Wastewater storage tank; 104. Waste gas treatment unit; 105. Fiber feeder waste gas pipeline; 201. Wastewater intermediate tank; 202. Alkali solution replenishment pipeline I; 203. Demineralized water pipeline; 204. Ultrafiltration membrane unit; 205. Ceramic membrane unit; 206. Backwashing assembly; 3 01. Desulfurization and bleaching tank I; 302. Desulfurization and bleaching tank II; 303. Bleaching water tank; 304. Desulfurization and bleaching storage tank I; 305. Desulfurization and bleaching storage tank II; 306. Bleaching water storage tank; 307. Circulation pump I; 308. Circulation pump II; 309. Circulation pump III; 310. Hydrogen peroxide mixing tank; 311. Sewage pipe; 312. Plate heat exchanger; 313. Steam pipe; 314. Alkali replenishment pipe II. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0030] Example 1

[0031] This embodiment provides a method such as Figure 1 and 2 The waste gas recovery device shown is used for desulfurization and bleaching of viscose staple fiber. It includes a waste gas recovery system 1, a wastewater treatment system 2, and a desulfurization and bleaching system 3. The waste gas recovery system 1 includes a spray tower 101. The bottom inlet of the spray tower 101 is connected to a waste gas pipeline 105 supplying the fiber trough. The top inlet of the spray tower 101 is connected to the outlet of an alkali solution mixing tank 102. The bottom outlet of the spray tower 101 is connected to the inlet of a wastewater storage tank 103. The wastewater treatment system 2 includes a filtration system. The wastewater solid impurity filtration component has its inlet connected to the outlet of the wastewater storage tank 103, and its outlet connected to the inlet of the intermediate wastewater tank 201. The desulfurization and bleaching system includes a desulfurization and bleaching tank, with a desulfurization and bleaching storage tank at the bottom. The desulfurization and bleaching tank and the desulfurization and bleaching storage tank are circulated together by a circulation pump. The outlet of the intermediate wastewater tank 201 is connected to the inlet of the desulfurization and bleaching tank, and the drain outlet of the desulfurization and bleaching storage tank is connected to the drain pipe 311.

[0032] In this embodiment, the control of the device for waste gas recovery used in the desulfurization and bleaching of viscose staple fiber is achieved by the following method, including the following steps:

[0033] S1. The waste gas in the fiber feeder enters the bottom of the spray tower 101 through the waste gas pipe. After the alkaline solution is prepared in the alkaline solution preparation tank 102, it is introduced into the spray tower 101. The alkaline solution is sprayed from the top of the spray tower 101 to spray and absorb the waste gas. After spraying, the waste gas containing CS2 enters the waste gas treatment mechanism 104 for waste gas treatment. The wastewater containing NaHS is introduced into the wastewater storage tank 103.

[0034] The alkaline solution concentration is 12-15 wt%, the H2S concentration in the waste gas is 4000 ppm ± 500 ppm, and the ratio of waste gas flow rate to alkaline solution flow rate is 1.5-2.5 L / Nm³, adjusted according to the waste gas flow rate; the NaHS concentration in the wastewater containing NaHS is 8-10%, the NaS2 concentration is less than 0.2%, the H2S absorption rate in the spray tank is >98%, and the pH value of the wastewater containing NaHS is 10 ± 0.5;

[0035] S2. Wastewater in wastewater storage tank 103 is filtered by a filter assembly and then fed into intermediate wastewater tank 201201.

[0036] Before filtration, the suspended solids (SS) in the wastewater were 200-500 mg / L, and after filtration, the SS in the wastewater were <50 mg / L.

[0037] S3. Wastewater in intermediate wastewater tank 201 is fed into desulfurization and bleaching tank to desulfurize and bleach the filaments. Wastewater in desulfurization and bleaching tank circulates between the desulfurization and bleaching tank and the desulfurization and bleaching storage tank. Wastewater containing NaHS is continuously replenished from intermediate wastewater tank 201, and excess wastewater is discharged from the drain outlet of desulfurization and bleaching storage tank. This achieves balance of NaHS content, sodium polysulfate content and liquid level in desulfurization and bleaching tank. At the same time, the drain outlet can also discharge elemental sulfur from the circulating liquid, thereby achieving balance of sulfur content in the circulating liquid and enhancing the desulfurization and bleaching effect.

[0038] In this embodiment, the fiber feeding tank is a stainless steel rubber-lined tank with a volume of approximately 15 m³; the spray tower 101 is a Huadong Environmental Protection PPH-8000 with a tower diameter of Φ2.2 m and a packing height of approximately 3.5 m; the alkali solution mixing tank 102 is a glass-lined K5000L with a volume of 5 m³; the circulating pump I307 is a Southern Pump Industry CDLF20-8 with a flow rate of 20 m³ / h; when the filaments pass through the fiber feeding tank in the refining process, they will release gas containing a high concentration of hydrogen sulfide (H2S) at high temperatures, with an H2S concentration of approximately 3000-4000 ppm. The remaining waste gas is mainly CS2 gas. The solubility of CS2 in alkali solution is only 0.2 g / 100g water (25℃), and the reaction requires high temperature and high pressure.

[0039] In this embodiment, the waste gas treatment mechanism 104 includes a condenser and a CS2 storage tank. After the remaining waste gas passes through the condenser, the CS2 cools it into liquid and then flows into the storage tank for recovery. Finally, the remaining non-condensable gas is directly discharged.

[0040] In this embodiment, the residual sulfur content and whiteness of the filaments are detected by manual sampling at regular intervals. Sodium hydrosulfide (NaHS) reacts with elemental sulfur (S) in the desulfurization bleaching tank to generate sodium polysulfide (Na2S). x This effectively dissolves sulfur scale on the fiber surface. While desulfurizing the filaments with NaHS, Na2S...x The silk threads are subjected to reduction bleaching.

[0041] Example 2

[0042] Compared with Example 1, the difference in this embodiment is that, in this embodiment, the desulfurization bleaching tank includes desulfurization bleaching tank I301 and desulfurization bleaching tank II302 arranged in the order of the filament travel route, and a channel for the filament to pass through is provided between desulfurization bleaching tank I301 and desulfurization bleaching tank II302. Below the desulfurization bleaching tanks I301 and II302, desulfurization bleaching storage tanks I304 and II305 are respectively installed. Desulfurization bleaching tanks I301 and II304 are circulated together via circulation pump I307, and desulfurization bleaching tanks II302 and II305 are circulated together via circulation pump II308. The outlet of the wastewater intermediate tank 201 is connected to the inlet of the desulfurization bleaching tank I301, and the outlet of the desulfurization bleaching storage tank I304 and the inlet of the desulfurization bleaching storage tank II305 are connected via pipes. The drain outlets of the desulfurization bleaching storage tanks I304 and II305 are connected to the drain pipe 311. The remaining structure is the same as in Example 1.

[0043] In this embodiment, the wastewater in the intermediate wastewater tank 201 is fed into the desulfurization and bleaching tank I301 to desulfurize and bleach the filaments; the desulfurized and bleached filaments enter the desulfurization and bleaching tank II302, and the desulfurized and bleached wastewater circulates between the desulfurization and bleaching tank I301 and the desulfurization and bleaching storage tank I304.

[0044] The temperature inside the desulfurization bleaching tank I301 is 80℃±5℃, the pH value is 11.5±0.5, the NaHS concentration is 3%±0.2%, the liquid level is 60%±5%, the residual sulfur content of the filaments after desulfurization bleaching is ≤0.8 wt%, and the residence time of the filaments in the desulfurization bleaching tank I301 is 15-20 min.

[0045] The wastewater in the desulfurization and bleaching storage tank I304 is partially fed into the desulfurization and bleaching storage tank II305, and circulates between the desulfurization and bleaching tank II302 and the desulfurization and bleaching storage tank II305 to further desulfurize and bleach the filaments that enter the desulfurization and bleaching tank II302. The filaments after further desulfurization and bleaching enter the bleaching water tank 303.

[0046] The temperature inside the desulfurization bleaching tank II 302 is 65℃±5℃, the pH value is 11±0.5, the NaHS concentration is 1.5%±0.2%, the liquid level is 60%±5%, the residual sulfur content of the filaments after further desulfurization and bleaching is ≤0.2wt%, and the residence time of the filaments in the desulfurization bleaching tank II 302 is 15-20 min.

[0047] In this embodiment, the desulfurization bleaching tank I301 is made of 304 stainless steel with a volume of 8 m³; the desulfurization bleaching tank II302 is made of 304 stainless steel with a volume of 6 m³; the desulfurization bleaching storage tank I304 is made of PE material RPT-20 with a volume of 20 m³; and the desulfurization bleaching storage tank II305 is made of PE material RPT-20 with a volume of 15 m³.

[0048] In this embodiment, the high temperature of the desulfurization bleaching tank I301301 can remove particulate sulfur by washing with water, while the reduction bleaching effect breaks the SS-desulfurization. Therefore, the desulfurization bleaching tank I301301 mainly desulfurizes, but also has a bleaching effect.

[0049] The temperature of the desulfurization bleaching tank II 302 302 is relatively low, and the particulate sulfur has been basically removed in the desulfurization bleaching tank I 301 301. The main function of the desulfurization bleaching tank II 302 302 is to break the (-SS-) bond, so it is mainly for bleaching.

[0050] In this embodiment, the desulfurization bleaching tank II 302 mainly contains sodium polysulfide (Na2S) x The yarn is bleached, but sodium polysulfide is difficult to distinguish in solution and its concentration is difficult to detect. The yarn is yellow mainly because it contains two types of sulfur: elemental sulfur and colloidal sulfur, and sulfur-sulfur bonds that bind to the fiber. Sodium hydrosulfide reacts with sulfur to wash away the sulfur, which is desulfurization. Sodium polysulfide reacts with sulfur-sulfur bonds to remove the sulfur bound to the fiber, which is bleaching. There is a lot of elemental sulfur and less sulfur bound to the fiber. Desulfurization and bleaching cannot be discussed separately. Therefore, it is sufficient to detect the concentration of sodium hydrosulfide in the desulfurization and bleaching tank II 302.

[0051] Example 3

[0052] Compared with Embodiment 1, the difference in this embodiment is that, in this embodiment, the desulfurization and bleaching system 3 further includes a bleaching water tank 303. The desulfurization and bleaching tank and the bleaching water tank 303 are arranged in sequence according to the filament travel route, and a channel for the filaments to pass through is provided between the desulfurization and bleaching tank and the bleaching water tank 303. A bleaching water storage tank 306 is provided at the bottom of the bleaching water tank 303, and the bleaching water tank 303 and the bleaching water storage tank 306 are circulated together by a circulation pump Ⅲ 309. The inlet of the bleaching water tank 303 is connected to a hydrogen peroxide mixing tank 310; the drain outlet of the bleaching water storage tank 306 is connected to a drain pipe 311; and the bleaching water storage tank 306 is provided with a demineralized water inlet. The rest of the structure is the same as in Embodiment 1.

[0053] In this embodiment, the desulfurized and bleached filaments in the desulfurization and bleaching tank enter the bleaching water tank 303. The whiteness of the filaments entering the bleaching water tank 303 is tested by sampling. When the whiteness of the filaments is ≥85%, the filaments directly enter the next process.

[0054] When the whiteness of the filament is greater than or equal to 70% and less than 85%, adjust the NaHS concentration and residence time in the desulfurization and bleaching tank so that the whiteness of the filament is ≥85% before proceeding to the next process.

[0055] When the whiteness of the yarn is less than 70%, after the hydrogen peroxide bleaching solution is prepared, it is introduced into the bleaching water storage tank 306 and circulated between the bleaching water storage tank 306 and the bleaching water tank 303 to assist in the bleaching of the yarn. The yarn after the bleaching is then introduced into the next process.

[0056] The auxiliary bleaching temperature is 80℃±5℃, the pH value is 10±0.5, the hydrogen peroxide concentration is 0.3%±0.1%, and the liquid level is 60%±5%. The residual sulfur content of the filaments after auxiliary bleaching is ≤0.03wt%, the whiteness of the filaments is ≥85% (ISO brightness), and the residence time of the filaments in the bleaching water tank 303 is 20-25min.

[0057] In this embodiment, the bleaching water tank 303 is made of 304 stainless steel with a volume of 12 m³; the bleaching water storage tank 306 is made of 304 stainless steel with a volume of 30 m³.

[0058] In this embodiment, the bleaching tank 303 serves as a supplementary bleaching tool. The residual sulfur content and whiteness of the filaments entering the bleaching tank 303 are manually detected at regular intervals. When the whiteness is greater than or equal to 85%, no system adjustment is required. The filaments are directly introduced into the next process after being cleaned with demineralized water in the bleaching tank 303.

[0059] When the whiteness is greater than or equal to 70% but less than 85%, the whiteness of the yarn is slightly lower than the production process requirements. This can be achieved by adjusting the process parameters in the desulfurization and bleaching tank, including increasing the NaHS concentration and temperature in the desulfurization and bleaching tank and extending the residence time of the yarn in the desulfurization and bleaching tank, thereby achieving the requirement of a whiteness greater than or equal to 85%.

[0060] In actual production, incomplete bleaching may occur, and the whiteness of the filaments may be less than 70%. In this case, bleaching tank 303 uses low-concentration hydrogen peroxide for final auxiliary bleaching as a supplement.

[0061] Example 4

[0062] The difference between this embodiment and Embodiment 1 is that, in this embodiment, the filtration assembly includes an ultrafiltration membrane mechanism 204 and a ceramic membrane mechanism 205. The ultrafiltration membrane mechanism 204 has a pore size of 500 μm, and the ceramic membrane filter plate of the ceramic membrane mechanism 205 has a pore size of 0.1 μm. Both the ultrafiltration membrane mechanism 204 and the ceramic membrane mechanism 205 are equipped with backwashing components 206. The remaining structure is the same as in Embodiment 1.

[0063] In this embodiment, the ultrafiltration membrane mechanism 204 is a hollow fiber ultrafiltration membrane (PVDF material), Siemens UltraPURE UP-100, with a membrane area of ​​50 m² / membrane and a flux of 10 m³ / h; the inlet of the ultrafiltration membrane mechanism 204 is equipped with a feed pump, which is Grundfos CRN10-7 (316L stainless steel), with a Q=12 m³ / h and H=30 m;

[0064] The ceramic membrane unit 205 is a tubular ceramic membrane (α-Al2O3), TAMI Industries INSIDE CéRAM®, with a filtration area of ​​3.6 m² / unit. A circulation pump is installed at the inlet of the ceramic membrane unit 205, which is a NEMO®BY 40-16 screw pump.

[0065] In this embodiment, backwashing of both the ultrafiltration membrane module 204 and the ceramic membrane module 205 requires no additional components; backwashing can be achieved simply by changing the membrane inlet and outlet. Those skilled in the art can also use conventional backwashing components 206 to backwash the ultrafiltration membrane module 204 and the ceramic membrane module 205 using conventional techniques.

[0066] In this embodiment, the suspended solids (SS) in the wastewater from the intermediate wastewater tank 201 are controlled below 50 mg / L through the synergistic effect of the ultrafiltration membrane module 204 and the ceramic membrane module 205. Backwashing is initiated when the flow rate of the ultrafiltration membrane module 204 decreases to 70%-80% of its original flux or when the transmembrane pressure difference exceeds the specified range. Backwashing is also initiated when the flux of the ceramic membrane module 205 decreases to 70%-80% of its original flux or when the transmembrane pressure difference exceeds the specified range. After backwashing, the flux of both the ultrafiltration membrane and the ceramic membrane can be restored to more than 95% of their original flux.

[0067] After backwashing, the flux of both ultrafiltration and ceramic membranes can be restored to more than 95% of the original flux. The filtered wastewater can be sampled and monitored for values ​​such as suspended solids (SS) and COD to ensure that SS is controlled below 50 mg / L.

[0068] Example 5

[0069] In this embodiment, a plate heat exchanger 312 is installed at the outlet of the intermediate wastewater tank 201; the heating medium pipeline of the plate heat exchanger 312 is connected to the steam pipeline 313; steam heating coils are respectively installed in the desulfurization bleaching tank I 301 and the desulfurization bleaching tank II 302; the bleaching water tank 303 has a jacketed structure, and the jacket is connected to the steam pipeline 313.

[0070] In this embodiment, the water flowing from the outlet of the wastewater intermediate tank 201 to the desulfurization bleaching tank I301 is heated by the plate heat exchanger 312, thereby heating the desulfurization bleaching tank I301. At the same time, the temperature inside the desulfurization bleaching tank I301 is controlled by the amount of steam in the heating medium pipeline in the plate heat exchanger 312.

[0071] In this embodiment, when the temperature in the desulfurization bleaching tank I301 and the desulfurization bleaching tank II302 drops too much, steam is introduced into the steam coil to supplement the heating of the desulfurization bleaching tank I301 and the desulfurization bleaching tank II302.

[0072] In this embodiment, a steam heating coil is also provided in the desulfurization bleaching tank II 302. Steam is introduced into the steam heating coil to heat the desulfurization bleaching tank II 302 and maintain the temperature inside the desulfurization bleaching tank II 302.

[0073] In this embodiment, when it is necessary to replenish the bleaching of the filaments, steam is introduced into the jacket of the bleaching tank 303 to heat the circulating liquid in the bleaching tank 303, thereby reaching the temperature for replenishing the bleaching.

[0074] Example 6

[0075] The difference between this embodiment and the previous one is that, in this embodiment, the intermediate wastewater tank 201 is equipped with an alkali replenishment pipeline I202 and a demineralized water pipeline 203. The desulfurization bleaching tank I301, desulfurization bleaching tank II302, and bleaching water tank 303 are equipped with an alkali replenishment pipeline II314. The remaining structures are the same as in Embodiment 1.

[0076] In this embodiment, alkali and demineralized water are replenished promptly according to changes in pH and NaHS concentration to maintain a NaHS concentration of 3 ± 0.2% and a pH value greater than 10. In spray tower 101, when the amount of H2S is greater than an equal amount of NaOH, the reaction proceeds in two steps: first, sodium sulfide is generated: NaOH + H2S → NaHS + H2O; then, the excess H2S further reacts with the byproduct Na2S to generate sodium hydrosulfide (NaHS): Na2S + H2S → 2NaHS. The overall reaction formula (when H2S is in excess) is: NaOH + H2S → NaHS + H2O. Since H2S is always in excess in the system, the reaction ratio of alkali to H2S is 1:1, all alkali reacts, the alkali concentration is controlled at 8%, and the alkali flow rate is the set value. Therefore, the NaHS concentration is always higher than the set value. Demineralized water needs to be injected into the intermediate wastewater tank 201 according to the NaHS concentration to bring the NaHS concentration to the set value.

[0077] In this embodiment, since sodium hydroxide in desulfurization bleaching tank I301, desulfurization bleaching tank II302 and bleaching water tank 303 is constantly being consumed, it is necessary to add alkali solution to desulfurization bleaching tank I301, desulfurization bleaching tank II302 and bleaching water tank 303 according to the pH value in the desulfurization bleaching tank I, desulfurization bleaching tank II302 and bleaching water tank 303.

[0078] It is understood that this utility model has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this utility model.

Claims

1. A device for recovering waste gases for desulphurization bleaching of staple fibre, characterized in that: The system includes a waste gas recovery system (1), a wastewater treatment system (2), and a desulfurization and bleaching system (3). The waste gas recovery system (1) includes a spray tower (101). The bottom air inlet of the spray tower (101) is connected to the waste gas pipeline (105) for the fiber optic trough. The top liquid inlet of the spray tower (101) is connected to the liquid outlet of the alkali solution mixing tank (102). The bottom liquid outlet of the spray tower (101) is connected to the liquid inlet of the wastewater storage tank (103). The wastewater treatment system (2) includes a system for filtering wastewater. The filter assembly for solid impurities has its inlet connected to the outlet of the wastewater storage tank (103) and its outlet connected to the inlet of the intermediate wastewater tank (201). The desulfurization and bleaching system includes a desulfurization and bleaching tank, with a desulfurization and bleaching storage tank at the bottom. The desulfurization and bleaching tank and the desulfurization and bleaching storage tank are connected by a circulating pump. The outlet of the intermediate wastewater tank (201) is connected to the inlet of the desulfurization and bleaching tank, and the outlet of the desulfurization and bleaching storage tank is connected to the sewage pipe (311).

2. The apparatus for waste gas recovery and desulfurization bleaching of viscose staple fiber according to claim 1, characterized in that: The desulfurization and bleaching tank includes a desulfurization and bleaching tank I (301) and a desulfurization and bleaching tank II (302) arranged in sequence according to the filament travel route. A channel for the filament to pass through is provided between the desulfurization and bleaching tank I (301) and the desulfurization and bleaching tank II (302).

3. The apparatus for waste gas recovery and desulfurization bleaching of viscose staple fiber according to claim 2, characterized in that: Below the desulfurization bleaching tank I (301) and the desulfurization bleaching tank II (302), there are respectively a desulfurization bleaching storage tank I (304) and a desulfurization bleaching storage tank II (305); the desulfurization bleaching tank I (301) and the desulfurization bleaching storage tank I (304) are connected by circulation pump I (307), and the desulfurization bleaching tank II (302) and the desulfurization bleaching storage tank II (305) are connected by circulation pump II (308).

4. The apparatus for waste gas recovery and desulfurization bleaching of viscose staple fiber according to claim 3, characterized in that: The outlet of the intermediate wastewater tank (201) is connected to the inlet of the desulfurization bleaching tank I (301), and the outlet of the desulfurization bleaching storage tank I (304) and the inlet of the desulfurization bleaching storage tank II (305) are connected by a pipeline; the sewage outlets of the desulfurization bleaching storage tank I (304) and the desulfurization bleaching storage tank II (305) are respectively connected to the sewage pipe (311).

5. The apparatus for waste gas recovery and desulfurization bleaching of viscose staple fiber according to claim 2, characterized in that: The desulfurization bleaching tank I (301) and the desulfurization bleaching tank II (302) are respectively equipped with steam heating coils.

6. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 1, characterized in that: The desulfurization and bleaching system (3) also includes a bleaching tank (303). The desulfurization and bleaching tank and the bleaching tank (303) are arranged in the order of the filament travel route, and a channel for the filament to pass through is provided between the desulfurization and bleaching tank and the bleaching tank (303).

7. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 6, characterized in that: The bottom of the bleaching tank (303) is provided with a bleaching water storage tank (306), and the bleaching tank (303) and the bleaching water storage tank (306) are connected by a circulation pump III (309).

8. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 7, characterized in that: The inlet of the bleaching water tank (303) is connected to a hydrogen peroxide mixing tank (310); the outlet of the bleaching water storage tank (306) is connected to a sewage pipe (311); the bleaching water storage tank (306) is provided with a demineralized water inlet.

9. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 6, characterized in that: The bleaching tank (303) has a jacketed structure, and the jacket is connected to the steam pipe (313).

10. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 1, characterized in that: The filtration assembly includes an ultrafiltration membrane mechanism (204) and a ceramic membrane mechanism (205). The ultrafiltration membrane mechanism (204) has an ultrafiltration membrane pore size of 500 μm, and the ceramic membrane filter plate of the ceramic membrane mechanism (205) has a pore size of 0.1 μm.

11. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 10, characterized in that: The ultrafiltration membrane unit (204) and the ceramic membrane unit (205) are respectively provided with backwashing components (206).

12. The apparatus for waste gas recovery for desulfurization and bleaching of viscose staple fiber according to claim 1, characterized in that: The outlet of the intermediate wastewater tank (201) is equipped with a plate heat exchanger (312); the heating medium pipeline of the plate heat exchanger (312) is connected to the steam pipeline (313).

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