A free combination filtration system capable of online automatic backwashing and online screen replacement

Abstract

The present invention discloses a free combination filtering system capable of online automatic backwashing and online screen replacement, which belongs to the technical field of textile equipment and is particularly suitable for filtering Lyocell fiber (Lyocell) cellulose stock solution. It includes a filtering system platform with legs, two rows of single-cylinder filter units mounted on the filtering system platform, a feed main pipeline and a discharge main pipeline arranged longitudinally between the two rows of single-cylinder filter units, and a sewage recovery tank arranged longitudinally outside the two rows of single-cylinder filter units. The single-cylinder filter units are connected to the feed main pipeline, the discharge main pipeline, and the sewage recovery tank in parallel through branch pipes. The present invention can realize the online automatic backwashing of the net, the online replacement of the filter net, and the exhaust function of each filter unit, avoid clogging the filter net, avoid the filter net from being damaged and leaking impurities into the filtrate, improve the filtration accuracy and filtration efficiency, and ensure the quality of subsequent fiber spinning; it has a wide range of applications and high flexibility.

Description

Technical Field

[0001] The present invention belongs to the technical field of textile equipment, and more specifically relates to a free combination filtering system capable of online automatic backwashing and online screen replacement, and is particularly suitable for filtering Lyocell fiber (lyocell) cellulose stock solution. Background Art

[0002] Lyocell fiber is a solvent-based cellulose fiber. It was developed by Acordis in the UK over a period of ten years and was not put into commercial use until the 1990s. In 2004, it was merged with Lenzing in Austria and unified its production. Lyocell fiber has environmental protection characteristics: the raw material comes from wood, which is made into wood pulp. The spinning process uses water and N-methylmorpholine-N-oxide (NMMO) solvent. The wood pulp is dissolved in water and NMMO solvent and spun directly. It is completed completely under physical action. During the dissolution process, the cellulose molecules contained in the raw pulp will not produce any derivatives and chemical reactions. When heated until completely dissolved, its molecular structure is a simple carbohydrate. In addition, the NMMO solvent used in production is completely harmless to the human body, almost completely recyclable, and can be used repeatedly. The NMMO solvent can be recycled with a recovery rate of more than 99.9%, which is non-toxic and pollution-free. After use, the fiber product can be completely biodegraded in the soil. It is a 100% natural material and will not pollute the environment. It is also green and environmentally friendly, and can be called the green fiber of the 21st century. And obtained the international green environmental protection certificate. Later, Lyocell fiber was introduced to China. Lyocell fiber produced by Acocdis Company in the UK was registered as Tencel fiber in China. This fiber has the "comfort" of cotton, the "strength" of polyester, the "luxury beauty" of wool fabric, and the "unique touch" and "soft drape" of silk. It is very tough whether in dry or wet state, and it is the first cellulose fiber with wet strength far superior to cotton in wet state. In addition, Lyocell fiber has an environmentally friendly manufacturing process, and has the trend of replacing high-pollution and high-energy-consuming viscose process fiber, while also catering to the needs of modern consumers.

[0003] Among them, Lyocell fiber (Lyocell) cellulose stock solution filtration technology is one of the key technologies to be broken through. Since Lyocell fiber (Lyocell) cellulose stock solution is a mixture of wood pulp, water and solvent NMMO in a certain proportion, it must be filtered to remove impurities before it can be directly spun, and the filtration accuracy reaches 25um. Some of the impurities in the stock solution are cellulose particles that are not completely dissolved. These cellulose particles are caused by branch break marks, which are not easy to grind. Under extreme conditions, it is easy to clog the filter screen. If the impurities are not handled in time, it will affect the subsequent fiber spinning. In addition, NMMO solvent is irritating to the human body. Therefore, it is necessary to be able to realize online automatic backwashing of the net and online replacement of the filter screen in the filtration system. However, the filtration systems of several production lines that have been built in China have different technical problems and cannot realize online automatic backwashing of the net and online replacement of the filter screen. For example, the filtration system has imported multi-disc filters from Mika Company in Lebanon, and imported single-column four-station screen changers from BKG Company in Germany. Many reasons cause the filtration effect of cellulose stock solution to be unsatisfactory.

[0004] (I) The defects of multi-disc filters are manifested in the following aspects: 1. Although the multi-disc filter has a large filtration area and solves the problem of frequent screen replacement, the disc-shaped net plate is flat, and there are many dead corners in the flow channel, and the stock solution is seriously stagnant (retained). It is difficult to replace it within a few hours, but the correct process requires that it must be replaced within an hour, otherwise it will cause serious consequences for the overheating of the NMMO solvent, especially affecting the quality of the fiber. 2. Because the cavity volume of the disc filter is large and the material flow rate is slow, in order to eliminate the stagnation (retention) of the stock solution, a single set of filters needs to be disconnected from work every 12 hours or so, and all the net plates need to be thoroughly backwashed once, which is not only a serious waste, but also has a great impact on production efficiency and output. 3. Because the entire filter is composed of several mesh discs, when the filter is blocked, the filter is backwashed in turn (that is, the clean stock solution flows in reverse to discharge impurities outside the main body, also called a gravity-flow backwash filter). The backwash piston of this structure is easy to get stuck, causing the production line to shut down; at the same time, the gravity-flow backwash net has a small instantaneous flow rate and low melt pressure, which not only has a poor backwashing effect, but also wastes a lot of clean stock solution (the solvent is recyclable). 4. Whether it is the backwash piston getting stuck or the normal replacement of the disc net, due to the large size of the filter, the project volume is large, the cleaning time is long, and a lot of manpower and material resources are consumed. 5. The multi-disc filter is a filtration system composed of three sets of filter units in one line. Due to the structure, there are many melt valves and the melt pipe connection is complicated.

[0005] (II) The defects of the BKG filtration system are manifested in the following aspects: 1. The single-column four-station screen changer is composed of four meshes or flow channels. In order to achieve the purpose of diversion or confluence, multiple diversion channels are designed. The structure is complex, there are many right-angle turns inside, and stagnation exists. The entire production line consists of six single-column four-station screen changers to form a filtration system. 2. Due to the structure, the mesh column seal adopts a ring seal at both ends, which is easy to wear. There is retention at the joint between the mesh column and the main body, and the leakage is serious; in order to self-clean the residual material, the mesh column needs to move back and forth 20mm every few tens of minutes, which is not only wasteful, but also has a great impact on production efficiency and output. 3. Because a single-column screen changer is a four-station work at the same time, when the pressure of the whole system rises and the filter screen is slowly blocked, the filter screen is backwashed in turn. When this structure is backwashed, the filter screen is carried out in pairs but in different positions, and the backwashing time is long; the self-flowing backwashing net has a small instantaneous flow rate, low melting pressure, poor backwashing effect, and is easy to form a "short circuit", wasting clean raw liquid (solvent can be recovered). 4. Because a single-column screen changer has four screens, screen change must be done in pairs, with four screens at both ends. The entire process is labor-intensive and time-consuming, and has a long impact on the entire filtration system. 5. There are many branch channels and connectors, which makes processing difficult and costly. 6. A single screen changer cannot be repaired or replaced offline during normal system operation.

[0006] In summary, in order to mass-produce qualified Lyocell fibers in China as soon as possible, it is necessary to break through the Lyocell fiber (Lyocell) cellulose stock solution filtration technology as soon as possible, and design a filtration system that can smoothly realize online automatic backwashing and online filter replacement to timely and effectively discharge impurities in the cellulose stock solution, thereby avoiding clogging of the filter, avoiding damage to the filter and leakage of impurities into the filtrate, improving filtration accuracy and efficiency, and ensuring the quality of subsequent fiber spinning. Summary of the invention

[0007] The purpose of the present invention is to provide a free combination filtration system capable of online automatic backwashing and online screen replacement in response to the deficiencies in the above-mentioned prior art, which is particularly suitable for filtering Lyocell fiber (Lyocell) cellulose stock solution. The present invention can realize the online automatic backwashing of each filter unit, online replacement of the filter screen and exhaust functions in turn, and can timely and effectively discharge impurities in the cellulose stock solution, avoid clogging the filter screen, avoid the filter screen from being damaged and leaking impurities into the filtrate, improve the filtration accuracy and filtration efficiency, and ensure the quality of subsequent fiber spinning; in addition, the present invention can select the number of single-cylinder filter units according to the capacity of the production line, and the independent single-cylinder filter unit can be repaired or replaced during the normal operation of the filtration system if it needs to be repaired or replaced, which has a wide range of applications and high flexibility.

[0008] The purpose of the present invention can be achieved by the following technical measures:

[0009] A free combination filtering system capable of online automatic backwashing and online screen changing of the present invention comprises a filtering system platform with legs (serving as the installation base of the filtering system), two rows of single-cylinder filtering units (the single-cylinder filtering units are the main body of the filtering system) mounted on the filtering system platform, a feed main pipeline and a discharge main pipeline arranged longitudinally between the two rows of single-cylinder filtering units, and a sewage recovery tank (recovering impurities in the process of backwashing or screen changing) arranged longitudinally on the outside of the two rows of single-cylinder filtering units; the single-cylinder filtering units are connected to the feed main pipeline, the discharge main pipeline and the sewage recovery tank in parallel through branch pipes (Lyocell fiber cellulose stock solution is diverted from the feed main pipeline to each single-cylinder filtering unit, and after being filtered by the single-cylinder filtering unit, the clean Lyocell fiber cellulose stock solution flows into the discharge main pipeline, while impurities adhere to the filter screen. Filter for a period of time After that, the filter screen is backwashed, and the backwash impurities are discharged to the sewage recovery tank through the large semicircular ring-shaped impurity discharge channel and two backwash impurity discharge joints; when the backwashing number reaches the set value, a new filter screen is directly replaced); the single-cylinder filter unit includes a filter matrix, an upper net column, a combined filter screen, and a lower net column set from top to bottom in the inner cavity of the filter matrix, and a backwashing core rod inserted in the inner cavity of the filter (the backwashing core rod has two design functions. Function one is: the material enters the inner cavity of the filter chamber from the feed inlet through the backwashing bracket, the filter screen, and the cylindrical porous plate. The only place where the material can be retained along the way is the inner cavity of the filter chamber. In order to meet the needs of backwashing, the inner cavity of the filter chamber is designed to be relatively large. The material can stagnate here but must not be retained. Therefore, during normal operation, it is necessary to use the backwashing core rod to reduce the channel size of the inner cavity of this filter chamber to a cross-sectional area slightly larger than or equal to that of the main flow channel.Function 2: During the backwashing and exhausting operation of the single-cylinder filter unit, the volume of the inner cavity of the filter chamber needs to be variable, and the volume difference is more than twice the volume of the outer cavity of the filter chamber - including the backwashing bracket and the filter screen, which can store clean filtrate when it is enlarged and discharge the filtrate when it is smaller to achieve backwashing or exhausting), the backwashing cylinder connected to the top surface of the backwashing core rod, and the screen-changing cylinder connected to the bottom end of the lower net column; the filter cavity is formed by the upper column inner hole, the combined filter screen inner hole, and the lower net column inner hole connected up and down to form a stepped blind hole with a larger top and a smaller bottom. The upper column inner hole is smaller than the aperture of the combined filter screen inner hole (to facilitate the upward movement or downward insertion of the backwashing core rod, and the difference in cross-sectional area between the two is greater than or equal to the feed port A feed inlet flush with the bottom of the inner hole of the upper post is provided on one side wall of the filter matrix (under normal working conditions, the feed inlet and the bottom of the combined filter screen are flush with the bottom of the inner hole of the upper post, which can ensure that the cellulose stock solution to be filtered flowing in from the feed inlet can flow through the combined filter screen for filtration; during the backwashing or screen changing process, the lower screen post blocks the feed inlet and closes the channel as the screen changing cylinder moves upward, which has the function of a melt valve), and a discharge port flush with the bottom of the inner hole of the lower screen post is provided on the adjacent side wall of the filter matrix and the lower screen post (under normal working conditions, the discharge port is flush with the bottom of the inner hole of the lower screen post, which can ensure that the clean cellulose stock solution after filtration flows smoothly into the discharge main The pipeline has reasonable flow channels and similar processes, avoiding dead corners; during the backwashing or changing of the net, the lower net column blocks the discharge port and closes the channel as the net-changing cylinder moves upward, which has the function of a melt valve). In the filter matrix, a water inlet joint and two backwashing impurity discharge joints are arranged on the upper part of the side wall opposite to the side wall where the discharge port is located, and a large semicircular backwashing impurity discharge channel connected to the water inlet joint and the backwashing impurity discharge joint and having the same height is arranged on the inner wall of the filter matrix (the other ends of the water inlet joint and the two impurity discharge joints are connected to the large semicircular backwashing impurity discharge channel, and then connected to the inner cavity of the filter matrix, and at the same time, the impurity discharge joint is directly below the sewage recovery tank, thus forming a complete The filter substrate has a circular filter discharge channel and a filter discharge port, one end of which is connected to the inner cavity of the filter substrate and the other end is connected to the filter discharge port. The other end of the filter discharge port extends to the side wall where the water inlet joint is located (the circular filter discharge channel and the filter discharge port are connected, and the outer end of the filter discharge port is directly below the discharge recovery tank, forming a complete filter discharge channel for recycling impurities and materials discharged from the guide discharge hole during the filter change process); the discharge recovery tank is located directly below the water inlet joint, the backwash discharge joint, and the filter discharge port. (The impurities or materials discharged from the backwash discharge joint or the filter discharge port are recovered in time through the discharge recovery tank).

[0010] In the present invention, the feed end of the mono-cylinder filter unit is mounted with an inlet melt valve, the inlet of the inlet melt valve is connected to the feed main pipeline through a branch pipe, the outlet of the inlet melt valve is connected to the feed port in the mono-cylinder filter unit, and the bottoms of the inlet melt valves of the two adjacent mono-cylinder filter units on the left and right are connected through an explosion-proof connecting pipe and a connecting flange to form a communicating vessel structure (the inlet melt valve is provided to close the Lyocell fiber cellulose stock solution channel of the feed port, which is convenient for repairing and replacing the mono-cylinder filter unit).

[0011] In the present invention, an outlet melt valve is mounted on the discharge end of the single-cylinder filter unit, the inlet of the outlet melt valve is connected to the discharge port in the single-cylinder filter unit, and the outlet of the outlet melt valve is connected to the discharge main pipeline through a branch pipe (the outlet melt valve is provided, on the one hand, to close the Lyocell fiber cellulose raw liquid channel of the discharge port, so as to facilitate the maintenance and replacement of the single-cylinder filter unit; on the other hand, the repaired or replaced single-cylinder filter unit can discharge the (testing) waste material passing through the screen through the outlet melt valve and has a pressure relief function when the system pressure is abnormally high, thereby improving the safety of use).

[0012] The combined filter screen described in the present invention is composed of a cylindrical porous plate, a filter screen, and a backwashing bracket which are nested and installed in sequence from the inside to the outside and are in a cylindrical shape. The filter screen is formed by overlapping a number of rectangular filter screen sheets, and the backwashing bracket is formed by interlocking two semi-cylindrical structures (in the process of changing the screen, it is convenient to quickly remove the old filter screen and quickly install the new filter screen). The surfaces of the cylindrical porous plate and the backwashing bracket are covered with liquid flow holes with apertures larger than the filter mesh (to ensure that the Lyocell fiber cellulose stock solution flows smoothly before and after the filter screen, and to ensure smooth filtration when flowing through the filter screen).

[0013] In the present invention, a cylindrical guide is installed on the top of the net column, and a guide drain hole is opened on the lower shell wall of the guide (when the filter chamber is pushed to the outside of the filter matrix, it is instantly covered by the guide. After the pressure disappears, the residual material in the filter chamber will flow through the guide drain hole to the annular net-changing drain channel located on the top surface of the filter matrix, and finally to the drain recovery tank through the net-changing drain port); a guide slideway connected to the cylinder body of the backwashing cylinder and sleeved in the inner cavity of the guide to slide relatively (the guide has two design functions, function one: to push out the combined filter net when the net column is lowered In the process of reaching the screen changing position, the entire filter chamber is gradually covered by the guide at the moment of its push out. In this way, due to the height of the filter chamber, residual materials can be prevented from being sprayed from the "high place", and discharged to the sewage recovery tank through the guide hole set at the lower end of the guide through the screen changing sewage outlet. At the same time, before cleaning the filter chamber, lift the guide and rotate it on the fixed pin. Function 2: First remove the old backwash bracket and dirty filter, and then install the new filter and clean backwash bracket. In order to ensure that the backwash bracket collides with the external body during the return process, it is necessary to lower the guide to cover the filter chamber at this time to ensure smooth return).

[0014] In the present invention, four oil cylinder support rods are fixed to the bottom of the filter matrix, and the other ends of the four oil cylinder support rods are connected to the support of the net changing cylinder (the net changing cylinder and the filter matrix are connected as one through the four oil cylinder support rods).

[0015] In the present invention, the bottom end of the inner cavity of the filter matrix and the top end of the inner hole of the upper column are both processed with a stepped hole that is small inside and large outside, and the large diameter section of the stepped hole is processed with a thread, the small diameter section of the stepped hole is embedded with a flexible seal (to avoid or reduce leakage), and the large diameter section of the stepped hole is screwed with a clamping nut.

[0016] The design principle of the present invention is as follows:

[0017] The present invention arranges a number of independent single-cylinder filter units into two rows, and connects the main pipeline in parallel through the branch pipe to form a free combination filter system. The present invention can realize the online automatic backwashing net, online filter replacement and exhaust functions of each filter unit in turn, and can timely and effectively discharge impurities in the cellulose stock solution, avoid clogging the filter screen, avoid the filter screen damage to leak impurities into the filtrate, improve the filtration accuracy and filtration efficiency, and ensure the quality of subsequent fiber spinning; in addition, the present invention can select the number of single-cylinder filter units according to the size of the production line capacity, and the independent single-cylinder filter unit can be repaired or replaced during the normal operation of the filtration system if it needs to be repaired or replaced, which has a wide range of applications and high flexibility.

[0018] (i) During normal operation: All the single-tube filter units in the present invention are in the filtering state at the same time.

[0019] (II) Online automatic backwashing net: After filtering for a period of time, when the system pressure rises to meet the backwashing conditions, the cylinder rod of the backwashing cylinder automatically retracts, driving the backwashing core rod to move upward along the filter inner cavity, and the clean filtrate flows back into the inner cavity of the filter chamber for storage; after the storage is completed, the lower net column slowly moves upward under the push of the net-changing cylinder to reach the backwashing working position. At this time, the two sides of the lower net column block the feed inlet and the discharge port, that is, the fluid channel is closed; then, the backwashing cylinder pushes the backwashing core rod to move downward rapidly, and the clean filtrate stored in the inner cavity of the filter chamber passes through the cylindrical porous plate, the filter screen, the backwashing bracket in reverse order, and enters the sewage recovery tank through the large semicircular backwashing impurity discharge channel and the impurity discharge joint. In this process, the impurities adhered to the filter screen are discharged from the filter matrix together with the filtrate; then, the upper column, the combined filter screen, and the lower net column automatically move back to the working position. At this time, the water valve connected to the water inlet joint is opened to flush the residues in the large semicircular backwashing impurity discharge channel, the impurity discharge joint and the sewage recovery tank to prevent the impurities from being retained and degraded. Repeat the above steps to automatically backwash the other single-tube filter units in turn. In this way, the present invention can smoothly realize the online automatic backwashing of the net, timely and effectively discharge impurities in the cellulose stock solution, avoid clogging the filter screen, improve the filtration accuracy and filtration efficiency; and the online automatic backwashing of the net also avoids human contact with the NMMO solvent, avoids irritation and harm to the human body, and ensures the health of the operator.

[0020] (III) Online screen replacement and exhaust: When the number of backwashing times of the filter reaches the set value, it is necessary to directly replace the new filter to avoid the damage of the filter and the leakage of impurities into the filtrate: Before the filter replacement action is performed, the cylinder rod of the backwashing cylinder automatically retracts slowly and drives the backwashing core rod to move upward, and the clean filtrate flows back into the inner cavity of the filter chamber for storage; after the storage is completed, the lower net column drives the combined filter upward under the push of the net replacement cylinder until the combined filter is in the position of replacing the filter outside the filter matrix; when the filter chamber passes the backwashing position, the pressure is released. At this time, the water valve connected to the water inlet joint is opened to flush the filter chamber moving upward; when the filter chamber is pushed to the outside of the filter matrix, it is instantly covered by the guide. After the pressure disappears, it is necessary to prevent the residual material in the filter chamber from spraying. The residual material will flow through the drainage hole at the bottom of the guide through the annular net replacement drainage channel, the net replacement drainage port and finally to the drainage recovery tank. Wait for a while and lift the guide to rotate and fix it at the top of the guide slide; then , first remove the backwash bracket with a special tool, and then remove the dirty filter; then, install the new filter, and then install the new backwash bracket; then, drop the guide to ensure that the backwash bracket is completely stuck in the filter chamber, and control the filter cylinder to drive the lower net column to move downward to the exhaust position (close to the backwash position). At this time, the backwash core rod moves down quickly under the action of the backwash cylinder, and the clean filtrate stored in the filter chamber cavity reverses and quickly passes through the cylindrical porous plate, the new filter and the clean backwash bracket, and enters the sewage recovery tank through the large semicircular backwash impurity discharge channel and the impurity discharge joint. In this process, the air in the filter chamber is discharged from the filter matrix together with the filtrate. At this time, the water valve connected to the water inlet joint is opened to flush the large semicircular backwash impurity discharge channel, the impurity discharge joint and the residue in the sewage recovery tank to prevent impurities from being retained and degraded; after the exhaust is completed, the lower net column, the combined filter and the upper column continue to move back to the working position, and the online net changing operation is completed. Repeat the above steps to perform online net changing operations on other single-cylinder filter units in turn. In this way, the present invention can smoothly realize online screen replacement, avoid the damage of the filter screen and the leakage of impurities into the filtrate, ensure the filtration accuracy and filtration efficiency, and the online screen replacement will not disrupt the production rhythm and efficiency of the entire production line, ensuring the normal and smooth progress of production.

[0021] In addition, the feed port and the discharge port in the present invention are both connected to a melt valve, which has the functions of opening, closing, waste discharge and high-pressure load relief, and the single-cylinder filter unit can be repaired and replaced offline during normal operation of the system.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] The present invention provides a free combination filtration system capable of online automatic backwashing and online screen replacement, which is particularly suitable for filtering Lyocell fiber (Lyocell) cellulose stock solution. The present invention can realize the online automatic backwashing of the net, online replacement of the filter net and exhaust functions of each filter unit in turn, and can timely and effectively discharge impurities in the cellulose stock solution, avoid clogging the filter net, avoid impurities leakage into the filtrate due to filter net damage, improve filtration accuracy and filtration efficiency, and ensure the quality of subsequent fiber spinning; in addition, the present invention can select the number of single-cylinder filter units according to the size of the production line capacity, and the independent single-cylinder filter unit can be repaired or replaced during the normal operation of the filtration system if it needs to be repaired or replaced, which has a wide range of applications and high flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention (in the diagram, only a filtration system containing six single-cylinder filtration units is used as a representative).

[0025] Figure 2 yes Figure 1 Top view of the .

[0026] Figure 3 yes Figure 1 Left view of .

[0027] Figure 4 It is a three-dimensional structural schematic diagram of a single-cylinder filter unit.

[0028] Figure 5 This is the main view of the single-cylinder filter unit in normal working condition.

[0029] Figure 6 yes Figure 5 Top view of the .

[0030] Figure 7 yes Figure 5 The corresponding partial left view of the filter base part.

[0031] Figure 8 yes Figure 7 AA section view in.

[0032] Fig. 9 yes Figure 8 BB cross-section diagram in.

[0033] Fig.10 yes Fig. 9 CC cross-section diagram in .

[0034] Fig.11 yes Fig. 9 A partial enlarged view of point Ⅰ in the middle.

[0035] Fig.12 yes Fig. 9A partial enlarged view of point II in the middle.

[0036] Fig.13 yes Fig. 9 A partial enlarged view of point III in the middle.

[0037] Fig.14 This is the main view of the single-cylinder filter unit at the start of online backwashing.

[0038] Fig.15 yes Fig.14 A longitudinal cross-sectional view of the filter base portion.

[0039] Fig.16 This is the main view of the single-cylinder filter unit when the online backwashing net is terminated.

[0040] Fig.17 yes Fig.16 A longitudinal cross-sectional view of the filter base portion.

[0041] Fig.18 This is the main view of the single-cylinder filter unit in the online screen changing state.

[0042] Fig.19 yes Fig.18 A longitudinal cross-sectional view of the filter base portion.

[0043] Fig. 20 It is a schematic diagram of the structure of the filter unit guide.

[0044] Fig.21 It is a structural schematic diagram of the backwash support.

[0045] Description of the numbers in the figure: 1. Filter system platform; 2. Legs; 3. Single-cylinder filter unit; 3-1. Filter matrix; 3-1-1. Feed inlet; 3-1-2. Discharge outlet; 3-2. Upper column; 3-2-1. Guide; 3-2-1-1. Guide drain hole; 3-3. Combined filter screen; 3-3-1. Cylindrical porous plate; 3-3-2. Filter screen; 3-3-3. Backwash bracket; 3-4. Lower column; 3-5. Filter cavity; 3-6. Backwash core rod; 3-7. Backwash cylinder; 3-8. 7-1, guide slide, 3-8, net-changing cylinder, 3-9, water inlet joint, 3-10, backwashing and debris removal joint, 3-11, cylinder support rod, 3-12, flexible seal, 3-13, compression nut; 3-14, large semicircular backwashing and debris removal channel, 3-15, net-changing sewage outlet, 3-16, circular net-changing sewage channel, 4, feed main pipeline, 5, discharge main pipeline, 6, sewage recovery tank, 7, outlet melt valve, 8, inlet melt valve, 8-1, explosion-proof connecting pipe, 8-2, connecting flange. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with the accompanying drawings (the number of single-cylinder filter units in the present invention can be determined according to the production capacity of a specific production line, and the figure only uses a filter system containing six single-cylinder filter units as a representative):

[0047] like Figure 1 to Figure 21As shown, a free combination type filtration system capable of online automatic backwashing and online screen changing of the present invention comprises a filtration system platform (1) with legs (2) (serving as a mounting base of the filtration system), two rows of single-cylinder filtration units (3) mounted on the filtration system platform (1) (the single-cylinder filtration units (3) are the main body of the filtration system), a main feed pipe (4) and a main discharge pipe (5) arranged longitudinally between the two rows of single-cylinder filtration units, and a sewage recovery tank (6) arranged longitudinally outside the two rows of single-cylinder filtration units (recovering impurities in the process of backwashing or screen changing); the single-cylinder filtration units (3) are connected in parallel with the main feed pipe (4), the main discharge pipe (5) and the sewage recovery tank (6) through branch pipes. (Lyocell fiber cellulose stock solution is divided from the feed main pipeline (4) to each single-cylinder filter unit (3). After being filtered by the single-cylinder filter unit (3), the clean Lyocell fiber cellulose stock solution flows into the discharge main pipeline (5), while impurities adhere to the filter screen. After filtering for a period of time, the filter screen is backwashed, and the backwashed impurities are discharged to the sewage recovery tank (6) through the large semicircular ring impurity discharge channel (3-14) and two backwash impurity discharge joints (3-10); when the backwashing number reaches the set value, a new filter screen is directly replaced). The single-cylinder filter unit (3) includes a filter base (3-1), an upper column (3-2) arranged from top to bottom in the inner cavity of the filter base, a combined filter screen (3-3), and a lower filter. The net column (3-4) and the backwashing core rod (3-6) inserted in the filter inner cavity (3-5) (the backwashing core rod (3-6) has two design functions. The first function is: the material enters from the feed port through the backwashing bracket, the filter screen, and the cylindrical porous plate and enters the inner cavity of the filter chamber. The only place where the material can be retained is the inner cavity of the filter chamber. In order to meet the needs of backwashing, the inner cavity of the filter chamber is designed to be relatively large. The material can be stagnant here but must not be retained. Therefore, during normal operation, it is necessary to use the backwashing core rod (3-6) to reduce the channel size of the inner cavity of the filter chamber to a cross-sectional area slightly larger than or equal to the cross-sectional area of ​​the main flow channel. The second function is: during the backwashing and exhaust operation of the single-cylinder filter unit (3), it is necessary to reduce the inner cavity of the filter chamber. The volume is variable, and the volume difference is more than twice the volume of the outer cavity of the filter chamber - including a backwashing bracket and a filter screen, which realizes backwashing or exhaust by storing clean filtrate when it is enlarged and discharging the filtrate when it is reduced), a backwashing cylinder (3-7) connected to the top surface of the backwashing core rod (3-6), and a screen-changing cylinder (3-8) connected to the bottom end of the lower net column (3-4); the filter cavity (3-5) is a stepped blind hole formed by connecting the upper column inner hole, the combined filter screen inner hole, and the lower net column inner hole up and down to form a large upper and small lower step-shaped blind hole, the upper column inner hole is smaller than the aperture of the combined filter screen inner hole (to facilitate the upward movement or downward insertion of the backwashing core rod (3-6), and the difference in cross-sectional area between the two is greater than or equal to the diameter of the feed port), and the difference in cross-sectional area between the two is greater than or equal to the diameter of the feed port (3-1-1);A feed inlet (3-1-1) flush with the bottom of the inner hole of the upper column is provided on one side wall of the filter matrix (3-1) (under normal working conditions, the feed inlet (3-1-1) and the bottom of the combined filter screen (3-3) are flush with the bottom of the inner hole of the upper column, so that the cellulose raw liquid to be filtered flowing in from the feed inlet (3-1-1) can flow through the combined filter screen (3-3) for filtration; during backwashing or changing the screen, the lower screen column (3-4) blocks the feed inlet (3-1-1) and closes the channel after the screen changing cylinder (3-8) moves upward, thus having the function of a melt valve), and a filter element (3-1-1) flush with the bottom of the inner hole of the lower screen column is provided on an adjacent side wall of the filter matrix (3-1) and the lower screen column (3-4). The discharge port (3-1-2) is flush with the bottom of the inner hole of the lower net column under normal working conditions, so that the clean cellulose raw liquid after filtration can flow smoothly into the discharge main pipeline (5), the flow channel is reasonable, the process is not much different, and dead corners are avoided; during the backwashing or net changing process, the lower net column (3-4) blocks the discharge port (3-1-2) and closes the channel after the net changing cylinder (3-8) moves upward, and has the function of a melt valve. A water inlet joint (3-9) and two backwashing impurity discharge joints (3-10) are arranged on the upper part of the side wall opposite to the side wall where the discharge port (3-1-2) is located in the filter matrix (3-1), and a water inlet joint (3-9) and two backwashing impurity discharge joints (3-10) are arranged on the inner wall of the filter matrix. A large semicircular backwash impurity discharge channel (3-14) is connected to the water connector (3-9) and the backwash impurity discharge connector (3-10) and has the same height (the other ends of the water inlet connector (3-9) and the two impurity discharge connectors (3-10) are connected to the large semicircular backwash impurity discharge channel (3-14), and then connected to the inner cavity of the filter matrix. At the same time, the impurity discharge connector (3-10) is directly below the sewage recovery tank (6), so that a complete backwash impurity discharge channel is formed for recovering impurities or materials in the backwash filter or exhaust process). A circular net-changing sewage discharge channel (3-16) and a net-changing sewage discharge port (3-15) are opened on the top surface of the filter matrix (3-1). One end of the sewage channel (3-16) is connected to the inner cavity of the filter matrix, and the other end is connected to the screen-changing sewage outlet (3-15). The other end of the screen-changing sewage outlet (3-15) extends to the side wall where the water inlet joint (3-9) is located (the circular screen-changing sewage channel (3-16) and the screen-changing sewage outlet (3-15) are connected, and the outer end of the screen-changing sewage outlet (3-15) is directly below the sewage recovery tank (6), forming a complete screen-changing impurity discharge channel for recovering impurities and materials discharged from the guide sewage hole (3-2-1-1) during the screen-changing process). The sewage recovery tank (6) is located directly below the water inlet joint (3-9), the backwashing impurity discharge joint (3-10), and the screen-changing sewage outlet (3-15). (The impurities or materials discharged from the backwashing impurity discharge joint (3-10) or the screen-changing sewage outlet (3-15) are recovered in time through the sewage recovery tank (6). ;

[0048] In the present invention, the feed end of the mono-cylinder filter unit (3) is mounted with an inlet melt valve (8), the inlet of the inlet melt valve (8) is connected to the feed main pipeline (4) through a branch pipe, the outlet of the inlet melt valve (8) is connected to the feed port (3-1-1) in the mono-cylinder filter unit, and the bottoms of the inlet melt valves (8) of the two adjacent mono-cylinder filter units (3) on the left and right are connected through an explosion-proof connecting pipe (8-1) and a connecting flange (8-2) to form a communicating vessel structure (the inlet melt valve (8) is provided to close the Lyocell fiber cellulose stock solution channel of the feed port (3-1-1), so as to facilitate the maintenance and replacement of the mono-cylinder filter unit (3)).

[0049] In the present invention, the discharge end of the mono-cylinder filter unit (3) is mounted with an outlet melt valve (7), the inlet of the outlet melt valve (7) is connected to the discharge port (3-1-2) in the mono-cylinder filter unit, and the outlet of the outlet melt valve (7) is connected to the discharge main pipeline (5) through a branch pipe (the outlet melt valve (7) is provided, on the one hand, the Lyocell fiber cellulose stock solution channel of the discharge port (3-1-2) can be closed, so as to facilitate the maintenance and replacement of the mono-cylinder filter unit (3); on the other hand, the mono-cylinder filter unit (3) after maintenance or replacement can discharge the (testing) waste material passing through the screen through the outlet melt valve (7) and has a pressure relief function when the system pressure is abnormally high, thereby improving the safety of use).

[0050] The combined filter screen (3-3) of the present invention is composed of a cylindrical porous plate (3-3-1), a filter screen (3-3-2), and a backwashing bracket (3-3-3) which are nested and installed in sequence from the inside to the outside and are in a cylindrical shape. The filter screen (3-3-2) is formed by overlapping a plurality of rectangular filter screen sheets, and the backwashing bracket (3-3-3) is formed by two semi-cylindrical structures that are buckled and assembled (in the process of changing the screen, it is convenient to quickly remove the old filter screen and quickly install the new filter screen). The surfaces of the cylindrical porous plate (3-3-1) and the backwashing bracket (3-3-3) are covered with liquid flow holes with a larger aperture than the filter screen mesh (to ensure that the Lyocell fiber cellulose stock solution flows smoothly before and after the filter screen, and to ensure smooth filtration when flowing through the filter screen).

[0051] In the present invention, a cylindrical guide (3-2-1) is installed on the top of the upper column (3-2), and a guide drain hole (3-2-1-1) is opened on the lower shell wall of the guide (3-2-1) (when the filter chamber is pushed to the outside of the filter matrix, it is instantly covered by the guide (3-2-1), and after the pressure disappears, the residual material in the filter chamber will flow through the guide drain hole (3-2-1-1) to the annular screen-changing drain channel (3-16) located on the top surface of the filter matrix (3-1), and finally to the drain recovery tank (6) through the screen-changing drain port (3-15); a guide slideway (3-7-1) connected to the cylinder body of the backwashing cylinder (3-7) and sleeved in the inner cavity of the guide (3-2-1) to be able to slide relatively 1) It has two design functions. Function 1: When the lower net column (3-4) pushes the combined filter screen (3-3) to the screen changing position, the entire filter chamber is gradually covered by the guide (3-2-1) at the moment of its pushing. In this way, due to the height of the filter chamber, residual materials can be prevented from being sprayed from a "high place" and discharged to the sewage recovery tank (6) through the guide hole set at the lower end of the guide (3-2-1) and the screen changing sewage outlet (3-15). At the same time, before cleaning the filter chamber, the guide (3-2-1) is lifted and rotated to stop on the fixing pin. Function 2: First remove the old backwash bracket and dirty filter screen, and then install the new filter screen and clean backwash bracket. In order to ensure that the backwash bracket collides with the external body during the return process, it is necessary to lower the guide to cover the filter chamber to ensure smooth return).

[0052] In the present invention, four oil cylinder support rods (3-11) are fixed to the bottom of the filter matrix (3-1), and the other ends of the four oil cylinder support rods (3-11) are connected to the support of the net changing cylinder (3-8) (the net changing cylinder (3-8) and the filter matrix (3-1) are connected as one body through the four oil cylinder support rods (3-11)).

[0053] In the present invention, the bottom end of the inner cavity of the filter substrate (3-1) and the top end of the inner hole of the upper column (3-2) are both processed with a stepped hole that is small inside and large outside, and a thread is processed on the large diameter section of the stepped hole, a flexible sealing member (3-12) is embedded in the small diameter section of the stepped hole (to avoid or reduce material leakage), and a clamping nut (3-13) is screwed on the large diameter section of the stepped hole.

[0054] The specific use of the present invention is as follows:

[0055] (i) During normal operation: all the single-cylinder filter units (3) in the present invention are in a filtering state at the same time.

[0056] (ii) Online automatic backwashing net: After filtering for a period of time, when the system pressure rises to meet the backwashing condition, the cylinder rod of the backwashing cylinder (3-7) automatically retracts, driving the backwashing core rod (3-6) to move upward along the filter inner cavity, and the clean filtrate flows back into the inner cavity of the filter chamber for material storage; after the material storage is completed, the lower net column (3-4) moves upward slowly under the push of the net changing cylinder (3-8) to reach the backwashing working position, at which time the two sides of the lower net column (3-4) block the feed inlet (3-1-1) and the discharge port (3-1-2) , that is, the fluid channel is closed; then, the backwashing cylinder (3-7) pushes the backwashing core rod (3-6) to move downward rapidly, and the clean filtrate stored in the inner cavity of the filter chamber quickly passes through the cylindrical porous plate (3-3-1), the filter screen (3-3-2), the backwashing bracket (3-3-3) in reverse order, and enters the sewage recovery tank (6) through the large semicircular backwashing impurity discharge channel (3-14) and the impurity discharge joint (3-10). In this process, impurities adhered to the filter screen (3-3-2) are discharged from the filter base (3-1) together with the filtrate;

[0057] Then, the upper net column (3-2), the combined filter screen (3-3), and the lower net column (3-4) automatically move back to the working position, and the water valve connected to the water inlet joint (3-9) is opened to flush the residues in the large semicircular ring-shaped backwashing and impurity removal channel (3-14), the impurity removal joint (3-10), and the sewage recovery tank (6) to prevent impurities from being retained and degraded. Repeat the above steps to automatically backwash the nets of other single-cylinder filter units (3) online in turn. In this way, the present invention can smoothly realize the online automatic backwashing of the net, timely and effectively discharge impurities in the cellulose stock solution, avoid clogging the filter screen, and improve the filtration accuracy and filtration efficiency; and the online automatic backwashing of the net also avoids human contact with the NMMO solvent, avoids irritation and harm to the human body, and ensures the health of the operator.

[0058] (III) Online screen replacement and exhaust: When the number of backwashing times of the filter (3-3-2) reaches the set value, it is necessary to directly replace the new filter to avoid the damage of the filter and the leakage of impurities into the filtrate: before the filter replacement action is performed, the cylinder rod of the backwashing cylinder (3-7) automatically retracts slowly and drives the backwashing core rod (3-6) to move upward, and the clean filtrate flows back into the inner cavity of the filter chamber for storage; after the storage is completed, the lower screen column (3-4) drives the combined filter (3-3) to move upward under the push of the screen replacement cylinder (3-8) until the combined filter (3-3) is in the position of replacing the filter outside the filter matrix (3-1); when the filter chamber passes through the backwashing annular impurity discharge channel (3-14) has been depressurized, at this time the water valve connected to the water inlet joint (3-9) is opened to flush the filter chamber moving upward; when the filter chamber is pushed to the outside of the filter matrix (3-1), it is instantly covered by the guide (3-2-1). After the pressure disappears, it is necessary to prevent the residual material in the filter chamber from being sprayed. The residual material will pass through the guide drain hole (3-2-1-1) and flow through the annular screen-changing drain channel (3-16), the screen-changing drain port (3-15) and finally to the drain recovery tank (6). Wait for a while and lift the guide (3-2-1) and rotate it to fix it on the top of the guide slideway (3-7-1); then, use a special tool to first remove the backwash bracket (3-2-1-1). -3-3), then remove the dirty filter (3-3-2); then, install a new filter (3-3-2), and then install a new backwash bracket (3-3-3); then, drop the guide (3-2-1), so as to ensure that the backwash bracket (3-3-3) is completely stuck in the filter chamber, and control the filter cylinder (3-8) to drive the lower net column (3-4) to move downward to the exhaust position (close to the backwash position), at this time, the backwash core rod (3-6) moves downward rapidly under the action of the backwash cylinder (3-7), and the clean filtrate stored in the inner cavity of the filter chamber quickly passes through the cylindrical porous plate (3-3-1), the new filter (3-3-2) and The clean backwash bracket (3-3-3) enters the sewage recovery tank (6) through the large semicircular backwash impurity discharge channel (3-14) and the impurity discharge joint (3-10). During this process, the air in the filter chamber is discharged from the filter base (3-1) together with the filtrate. At this time, the water valve connected to the water inlet joint (3-9) is opened to flush the large semicircular backwash impurity discharge channel (3-14), the impurity discharge joint (3-10) and the residue in the sewage recovery tank (6) to prevent impurities from being retained and degraded; after the exhaust is completed, the lower net column (3-4), the combined filter screen (3-3) and the upper column (3-2) continue to move back to the working position, and the online net changing operation is completed. Repeat the above steps and perform online net changing operations on other single-cylinder filter units in turn. In this way, the present invention can smoothly realize online net changing, avoid the damage of the filter screen to leak impurities into the filtrate, ensure the filtering accuracy and filtering efficiency, and the online net changing will not disrupt the production rhythm and efficiency of the entire production line, ensuring the normal and smooth progress of production.

[0059] In addition, if a single-cylinder filter unit needs to be repaired or replaced offline, the corresponding inlet melt valve (8) and outlet melt valve (7) can be closed.

Claims

1. A free combination filtration system capable of online automatic backwashing and online screen replacement, characterized in that: It comprises a filter system platform (1) with legs (2), two rows of single-cylinder filter units (3) mounted on the filter system platform (1), a main feed pipe (4) and a main discharge pipe (5) arranged longitudinally between the two rows of single-cylinder filter units, and a sewage recovery tank (6) arranged longitudinally outside the two rows of single-cylinder filter units; the single-cylinder filter units (3) are connected in parallel with the main feed pipe (4), the main discharge pipe (5) and the sewage recovery tank (6) through branch pipes; the single-cylinder filter unit (3) comprises a filter base (3-1), an upper net column (3-2) sleeved in the inner cavity of the filter base and arranged from top to bottom, a combined filter screen (3-3), and a lower net column (3-4). , a backwashing core rod (3-6) inserted in the filter cavity (3-5), a backwashing cylinder (3-7) connected to the top surface of the backwashing core rod (3-6), and a screen changing cylinder (3-8) connected to the bottom end of the lower net column (3-4); the filter cavity (3-5) is formed by connecting the inner hole of the upper column, the inner hole of the combined filter screen, and the inner hole of the lower net column up and down to form a stepped blind hole with a larger top and a smaller bottom, and the inner hole of the upper column is smaller than the pore size of the inner hole of the combined filter screen; a feed port (3-1-1) flush with the bottom of the inner hole of the upper column is opened on one side wall of the filter substrate (3-1), and a discharge port (3-1-2) flush with the bottom of the inner hole of the lower net column is opened on the adjacent side wall of the filter substrate (3-1) and the lower net column (3-4). ), a water inlet joint (3-9) and two backwashing impurity discharge joints (3-10) are arranged on the upper part of the side wall opposite to the side wall where the discharge port (3-1-2) is located in the filter base (3-1), a large semicircular backwashing impurity discharge channel (3-14) connected to the water inlet joint (3-9) and the backwashing impurity discharge joint (3-10) and having the same height as the water inlet joint (3-9) and the backwashing impurity discharge joint (3-10) is arranged on the inner wall of the filter base, and a circular net-changing sewage discharge channel (3-16) and a net-changing sewage discharge port (3-15) are provided on the top surface of the filter base (3-1), one end of the circular net-changing sewage discharge channel (3-16) is connected to the inner cavity of the filter base, and the other end is connected to the net-changing sewage discharge port (3-15), and the net-changing sewage discharge port (3-15) is provided with a plurality of channels. The other end extends to the side wall where the water inlet joint (3-9) is located; the sewage recovery tank (6) is located directly below the water inlet joint (3-9), the backwashing impurity discharge joint (3-10), and the screen replacement sewage outlet (3-15); the combined filter screen (3-3) is composed of a cylindrical porous plate (3-3-1), a filter screen (3-3-2), and a backwashing bracket (3-3-3) which are nested and installed in sequence from the inside to the outside and are in a cylindrical shape; the filter screen (3-3-2) is formed by overlapping a plurality of rectangular filter screen sheets; the backwashing bracket (3-3-3) is formed by buckling two semi-cylindrical structures; and the surfaces of the cylindrical porous plate (3-3-1) and the backwashing bracket (3-3-3) are covered with liquid flow holes whose apertures are larger than the mesh size of the filter screen;A cylindrical guide (3-2-1) is installed on the top of the upper column (3-2), and a guide drain hole (3-2-1-1) is provided on the lower shell wall of the guide (3-2-1); a guide slideway (3-7-1) is connected to the cylinder body of the backwashing cylinder (3-7) and is sleeved in the inner cavity of the guide (3-2-1) to slide relatively; a stepped hole with a small inside and a large outside is processed at the bottom end of the inner cavity of the filter substrate (3-1) and the top end of the inner hole of the upper column (3-2), and a thread is processed at the large diameter section of the stepped hole, a flexible seal (3-12) is embedded in the small diameter section of the stepped hole, and a compression nut (3-13) is screwed on the large diameter section of the stepped hole. ; 2. A free combination filtering system capable of online automatic backwashing and online screen replacement according to claim 1, characterized in that: An inlet melt valve (8) is mounted on the feed end of the mono-cylinder filter unit (3); the inlet of the inlet melt valve (8) is connected to the feed main pipeline (4) via a branch pipe; the outlet of the inlet melt valve (8) is connected to the feed port (3-1-1) in the mono-cylinder filter unit; and the bottoms of the inlet melt valves (8) of two adjacent mono-cylinder filter units (3) on the left and right are connected via an explosion-proof connecting pipe (8-1) and a connecting flange (8-2) to form a communicating vessel structure.

3. The free combination filtering system capable of online automatic backwashing and online screen replacement according to claim 1, characterized in that: An outlet melt valve (7) is mounted on the discharge end of the single-cylinder filter unit (3); the inlet of the outlet melt valve (7) is connected to the discharge port (3-1-2) in the single-cylinder filter unit; and the outlet of the outlet melt valve (7) is connected to the discharge main pipeline (5) via a branch pipe.

4. The free combination filtering system capable of online automatic backwashing and online screen replacement according to claim 1, characterized in that: Four oil cylinder support rods (3-11) are fixed at the bottom of the filter base (3-1), and the other ends of the four oil cylinder support rods (3-11) are connected to the support of the screen changing oil cylinder (3-8).

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